PILOT SCALH UP 01: PROCESSES TO DEMONSTRATE
UTILIZATION OF PULVERIZED COAL FLYASII
'KJUIFILD BY THE ADDITION OF LIMESTOMi-
DOLOMITE SULFUR UIOXIDL REMOVAL ADDITIVE
FINAL REPORT
CONTRACT CPA 70-66
I-.MURONMENTAL PROTLCTION AGENCY OFFICL OF
AIR PROGRAMS CONTROL SYSTEMS DIVISION
COAL RESEARCH BUREAU
MINERAL INDUSTRIES BUILDING
WEST VIRGINIA UNIVERSITY
Morgantown, West Virginia
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•West Virginia
"CJniversity
MORGANTOWN, WEST VIRGINIA 26506
School of XtCixiOG
March 2, 1972
Mr. Luis H. Garcia
Environmental Protection Agency
Research Triangle Park
North Carolina 27711
Dear Mr. Garcia:
SUBJECT: Final Report, Contract CPA 70-66
Enclosed is a summary report of the research performed under Contract
CPA 70-66
The most promising areas of modified flyash utilization were found to be
the production of calcium-silicate and cement-like structural products,
the controlled production of sulfur gases (specifically 802) from heated
ash, the production of mineral wool insulation and the use of modified
ash as a soil stabilizer and amendment. All of these applications incor-
porate whole or total utilization of modified ash. These processes are
examined In detail along with the results of a rigorous characterization
study.
All pertinent technical and contractual data are attached.
Sincerely yours,
VJJL,
William F. Lawrence
Project Supervisor
Coal Research Bureau
WFL:sfs
Enclosre
Approvalftfor submittal:
leph W. Leonard
Director
Jal Research Bureau
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PILOT SCALE UP OF PROCESSES TO DEMONSTRATE UTILIZATION
OF PULVERIZED COAL FLYASH MODIFIED BY THE
ADDITION OF LIMESTONE-DOLOMITE SULFUR DIOXIDE
REMOVAL ADDITIVES
Coal Research Bureau
School of Mines
West Virginia University
Morgantown, West Virginia
FINAL REPORT
October, 1971
CONTRACT CPA 70-66
Environmental Protection Agency
Office of Air Programs
Control Systems Division
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TABLE OF CONTENTS
Abs tract ...................... .
Acknowledgments
Introduction
1. Characterization
A. Sources of Modified Ash ......................................... 1
B. Chemical and Physical Analyses .................................. 4
C. Sieve Analyses .................................................. 6
D. Microscopic Analyses ............................................ 8
E . X-Ray Analyses .................................................. 10
F. Summary [[[ n
2. Calcium-Silicate Building Products
A. Calcium-Silicate Brick .......................................... 14
B. Aerated Concrete ................................................ 22
C. Formed Concrete Products ........................................ 25
D. Conclusions [[[ 27
3. Sulfur Dioxide Regeneration
A. Experimental Method ............................................. 29
B. Results [[[ 31
C. Conclusions .............................. . ...................... 37
A. Mineral Wool
A. Modified Flyashes Tested ........................................ 49
B. Quality Tests ................................................ [[[ 51
C. Cost Analysis [[[ 54
D. Conclusion [[[ 57
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LIST OF TABLES
Page
Table 1-1 Chemical and Physical Analyses of Ashes Studied 5
Table 1-2 Chemical Analysis of Modified Ash Fractions 8
Table 4-1 Production Characteristics of Mineral Wool 50
Table 4-2 Quality Tests on Mineral Wool 52
Table 4-3 Preliminary Production Cost Estimate 55
LIST OF FIGURES
Page
Figure 2-0 Flow Sheet: Optimum Conditions for the Production of
Calcium-Silicate Brick From Dry-Collected Modified Ash... 15
Figure 2-1 Flow Sheet: Optimum Conditions for the Production of
Calcium-Silicate Brick From Wet-Collected Modified
Ash 16
Figure 2-2 The Relationship of the Ratio of Compaction and
Pressing Load for KPL Brick 17
Figure 2-2a The Relationship of the Ratio of Compaction and
Pressing Load for CM Brick 18
Figure 2-3 The Relationship of Pressing Load to Percent
Absorption and to Compressive Strength in KPL
Brick 19
Figure 2-4 The Relationship of Humidity Storage Time to
Compressive Strength and to Percent Absorption
in KPL Brick 20
Figure 2-5 The Relationship of Curing Time to Compressive
Strength and to Percent Absorption in KPL Brick 21
Figure 2-6 Flow Sheet: Aerated Concrete 24
Figure 2-7 Flow Sheet: Formed Concrete 26
Figure 3-0 Schematic of Experimental Design 30
Figure 3-1 The Amount of Sulfur Dioxide Generated by Heating
Sample CM at Various Temperatures 33
Figure 3-2 The Amount of Sulfur Dioxide Generated by Heating
Sample KPL at Various Temperatures 34
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Page
Figure 3-3 "Free" Lime Content of Wet and Dry-Collected Modified
Flyashes [[[ 36
Figure 3-4 CM Flyash - The Relative Concentration of Sulfur
Dioxide Evolved and The Total Amount Evolved at
1922. 0°F [[[ 33
Figure 3-5 CI1 Flyash - The Relative Concentration of Sulfur
Dioxide Evolved and The Total Ariount Evolved at
2012 .0°F [[[ 39
Figure 3-6 CM Flyash - The Relative Concentration of Sulfur
Dioxide Evolved and The Total Amount Evolved at
2127. 2°F [[[ 40
Figure 3-7 CM Flyash - The Relative Concentration of Sulfur
Dioxide Evolved ami THe Total Amount Evolved at
2177. 6°F [[[ 41
Figure 3-8 KPL Flyash - The Relative Concentration of Sulfur
Dioxide Evolved and the Total Amount Evolved at
1742°F [[[ 42
Figure 3-9 KPL Flyash - The Relative Concentration of Sulfur
Dioxide Evolved and The Total Amount Evolved at
1922°F [[[ 43
Figure 3-10 KPL Flyash - The Relative Concentration of Sulfur
Dioxide Evolved and The Total Amount Evolved at
2012°F [[[ 44
Figure 3-11 KPL Flyash - The Relative Concentration of Sulfur
Dioxide Evolved and The Total Amount Evolved at
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ABSTRACT
Bench-scale experiments to examine methods for potential utilization of
modified flyash indicate that this ash, the solid by-product resulting
from the limestone/dolomite process for fixing gaseous sulfur oxides as
solid sulfates, can be considered a suitable raw material for a number
of new products and processes. The most promising methods of utilization
incorporating the total utilization of modified flyash are the production
of calcium-silicate and cement-like structural products, high temperature
production of materials such as mineral wool insulation and the use of
modified flyash as a soil stabilizer and amendment.
Other utilization areas were examined and are mentioned; also, several
process problems and limitations are discussed.
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ACKNOWLEDGMENTS
Research was performed by the Coal Research Bureau, School of Mines,
West Virginia University under contract with the Office of Air Programs—
Environmental Protection Agency. The principal investigator and project
director for this contract is Mr. Joseph W. Leonard, Director, Coal Research
Bureau and the project officer is Mr. Luis Garcia of the Control Systems
Division, Environmental Protection Agency. The authors of this report
are Messrs. William Lawrence, Richard Muter, Ronald Anderson and Mrs. Linda
Condry.
Appreciation is due to Mr. Charles F. Cockrell, former Assistant
Director of Research of the Coal Research Bureau, for initiating and
directing the contract research and to Messrs. Benedict St. Jermaine, Jr.,
Edward Simcoe, Jr., and Gerald Moore, lab technicians, for performing the
many necessary experimental procedures.
ii
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INTRODUCTION
The increasing waste disposal problem associated with coal combustion
may be compounded several fold by the greater amount of waste generated if
potential alkaline earth sulfur dioxide abatement systems are implemented.
Although utilization schemes for normal flyash are available, the modified
flyash resulting from limestone/dolomite wet and dry sulfur sorption programs
represents a new type of solid waste material having different chemical and
physical properties from regular flyash. In addition, simple disposal of
this ash by land fill or lagooning may result in serious water or solid waste
pollution problems. Previous research ' ' has shown that very little
potential exists for mineral separation and beneficiation of this new ash
and indicates that the most economical utilization scheme would involve total
utilization of the ash. For these reasons the Coal Research IJureau of
West Virginia University has been performing basic research under a cost sharing
grant from EPA (Environmental Protection Agency) to develop and evaluate
total utilization processes. As a result of this research, several promising
ash utilization schemes have emerged. These include: production of autoclaved
structural materials such as calcium-silicate brick, concrete and aerated
concrete; production of high temperature materials such as mineral wool; and
use of modified ash as an agricultural soil amendment.
iii
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1. CHARACTERIZATION
Characterization of modified flyash was a continuation and expansion of
studies initiated under Contracts PH 86-67-1221"1 and PH 22-68-18.1~2 The general
objectives were to determine the physical and chemical characteristics of
modified ashes and to monitor variability of the ash samples produced from
several different magnesium oxide and calcium oxide based processes for the
adsorption of sulfur dioxide. The modified flyash samples were examined by means
of atomic absorption and atomic emission spectrophotometry, wet chemical analysis,
microscopic analysis, wet and dry-sieve techniques and x-ray diffraction.
Because the genesis of the ashes involved is a most important factor
in analyzing characterization data, a detailed description of the sources
of the seven different modified ashes studied is included.
A. Sources of Modified Ash
1. Detroit Edison Company, St. Clair, Michigan (PIJ) and DW)
The project undertaken at the St. Clair, Michigan Power Station was a
joint effort by Detroit Edison Company and Combustion Engineering, Inc. to field
test the limestone/dolomite injection, dry- and wet-collection, sulfur oxide
removal system under development by Combustion Engineering, Inc. In these tests,
a small stream of the dust-laden stack gases were diverted to a wet scrubber
so that both wet-and dry-collected modified flyashes were available. When
the dolomite tests were completed, a high purity limestone was also injected into
the boiler. Thus, it was possible to obtain both wet- ant! dry-collected
limestone and dolomite modified flyashes from this teat series. PIJ) is a
sample of the limestone modified material collected by a combination of electro-
static and mechcanical precipitators rated to be 99.5% effective and DW is
dolomite modified wet-collected ash obtained from the settling tank of a wet-
scrubbing circuit.
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In these tests the coal (3% sulfur—Ohio strip coal) and stone were
pulverized to approximately 95 percent passing 200 mesh. The crushed stone
was injected through the top burner, oriented 30° above the horizontal,
of a 325 megawatt Combustion Engineering twin furnace unit at a rate of
approximately 10 tons per hour (180 percent of the stoichiometric sulfur
gas absorbent requirement.
2. Union Electric Company, St. Louis, Missouri (SLD)
Samples of wet-collected dolomite modified flyasli were obtained from
the Merrimac Plant of Union Electric at St. Louis, Missouri. A dry injection
wet-collection technique was employed; the coal used contained 3% sulfur.
When the samples were taken, one of the two scrubbers was shut down for
modification; but, the water requirement was not reduced. Dolomite of
approximately 85 percent passing a 200 mesh sieve was added at the rate of
60 percent stoichiometric to the 2000°F temperature zone of the furnace.
Approximately 3,000 gallons per minute of water were used; 90 percent of the
water could be recycled from a clarification system. The slurry concentration
of the SLD material was about two percent solids.
3. Chevrolet Motor Division Plant. St. Louis. Missouri, (CM, CI and CU)
The injection tests undertaken by Chevrolet Motor Division at their St.
Louis assembly plant were performed in a small Babcock and Wilcox boiler having
a capacity of two tons of coal per hour. Pre-ground commercially available
dolomite was tested both by intermixing with the coal and by injection above
the flame envelope.
CM modified flyash was produced by pre-mixing dolomite and coal before
combustion while the CI material was produced by injecting the material above
the flame envelope. CU is unmodified flyash from the same unit.
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In these tests, the dolomite, vended as "dolcito,"* was injected into
the boiler at a rate of 200 percent of the stoichiometric amount required.
The dolomite had been pulverized by the supplier to 76 percent passing 230
mesh and 4.4 percent passing 325 mesh. The coal burned during the tests
contained 3 1/2 percent sulfur and was obtained from the River King Ho. 2
Mine of Peabody Coal Company and the Sparta Mine of Bell and Zoller Company.
The coal was fed into a B & W Type E pulverizer in a ratio of 60 percent River
King to 40 percent Sparta where it was pulverized to 70 percent passing 200 mesh
prior to combustion. The dry, modified flyash was collected in an electrostatic
precipitator rated to be approximately 99 percent efficient.
In the initial test, dolomite was admixed with the coal by adding 50
pounds of dolomite every three minutes through the exit port of the weigh
feeder. A 45 minute delay occurred between the time dolomite was first
added and a stable 20% reduction of sulfur dioxide occurred. After the stable
reduction occurred, the test was continued for three hours.
In the second test, dolomite was injected from a spider system
specifically designed to permit the dolomite to be uniformly sprayed, via
six nozzles, into the boiler above the flame envelope at an angle of
approximately 45 degrees above the horizontal. This test was also of three
hours duration; however, a 30% reduction of sulfur dioxide in the stack gases
occurred almost immediately.
4. Kansas Power and Light Company, Lawrence, Kansas (KPL)
The tests undertaken at Lawrence, Kansas were a Joint effort by the
Kansas Power and Light Company and Combustion Engineering, Inc. on a full-
scale, permanent wet scrubbing installation. The system used dry injection,
wet-collection in which limestone, ground to approximately 60 percent
*Use of trade names does not imply endorsement by the Coal Research Bureau
but is intended for clarification purposes only.
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passing 200 mesh, was injected at the rate of 110 percent stoichiometric
into the 2100°F temperature zone of the furnace. Two separate scrubbing
units were incorporated, both of which employed an over-bed recycle system
whereby water and modified ash from the bottom of the scrubber were passed to
a delay and mixing tank and then recycled by being sprayed above the marble
bed in the scrubber. The system used about 3,000 gallons of water per minute
of which 700 gallons per minute were obtained from blow down of the cooling
tower. The remaining water came from a recycle pond adjacent to the settling
pond. Sulfur dioxide in the stack gases was monitored both before and after
the scrubber. The coal being burned contained 1,960 parts per million (ppm)
sulfur as sulfur dioxide and 760 ppm was sorbed by calcined stone in the
dry state. The remaining 1,200 ppm entered the scrubber and 400 ppm were
emitted to the atmosphere after scrubbing.
5. Shawnee Steam Plant, Paducah, Kentucky (TVA)
The tests performed at Paducah, Kentucky were a project of the
Tennessee Valley Authority at their Shawnee Steam Plant. A limestone
injection, dry-collection method was used.
High purity limestone was injected into the boiler and the resulting
modified ash was collected in three different precipitators. The ash and off-
gases were first passed through a mechanical precipitator and then cycled through
two electrostatic precipitators before the effluent gas was fed to the stacks.
Sample TVA is a sample of the flyash collected in the mechanical precipitator.
B. Chemical and Physical Analyses
Chemical analyses and physical properties of all the modified flyashes
examined under the subject contract are given in Table 1-1. The chemical
analyses were performed by wet chemical, atomic absorption and atomic emission
spectroscopic methods; the physical properties were determined in the normal
manner. The analysis of a sample of unmodified flyash (sample CU) is also
incorporated in the table for comparison purposes.
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TABLE 1-1
CHEMICAL AND PHYSICAL ANALYSES OF ASHES STUDIED
Zdentlf Icatlon
N«EM
Source
Scone
Node of Collection
CliDtlfAL PRnPEKTIKS (*)
510,
A1263
FejOj
T.Uj
c»o
"free" linn
HfO
NnjO
KiO
s53
Moisture
Loo on Ignition
Water SoluMe
Fraction
Detroit
Edison
Lines Cone
ury
Detroit
pdliion
Dolor.lt e
Wet
Union
Electric
Doloalte
Met
Chevrolet
St. Louts
Premised Dolonlti
Dry
30.85
13.70
11.59
O.bH
29.79
1.4"
1.12
0.71
a. 20
1.12
0.00
1.03
22.11
raica ra:LTiiin PROPLKTJES CF)
LtiAl Information 2071
Softenlnf Terperature
Fluid Temperature
2138
2172
23.34
9.03
9.99
0.43
13.U4
9.24
0.65
U.U3
1H.6H
2.11
elurry
9.00
21.UK
2237
30. an
14.70
7.03
O.h4
19.56
4.77
0. J6
1.42
11.33
1.49
9U.OU
6.13
25.10
1780
2140
2150
21M)
35.90
14.40
7.7ft
0.71
19.18
8.96
12.61
0.34
0.72
0.05
3.29
0.24
3.79
25.61
1870
2260
2270
2300
Chevrolet
SC. Louis
Injected Dolomite
Dry
33.10
11.BO
7.18
0.65
17.92
7.70
11.45
A.46
0.72
6.95
5.64
0.26
B.34
19.14
1720
2250
2270
P. 2 80
Chevrolet
Si. Lai,In
Unrwdlfled
40.40
1H.40
13.60
1.10
5.18
0.00
1.66
0.58
1.30
3.18
9.67
0.30
11.58
8.90
1890
2250
2260
Kansnfi Povrr
an*: Mp.ht
LlrwQLOnG
U'et
29.90
U.42
12.40
0.4(1
2H.60
6.US
2.14
0.23
1.29
12.93
1.12
97.70
10.110
20.24
1620
2140
2150
2165
Llneaco
Ilrv
32.60
K..70
4.2U
0.56
36.HO
24.hv
O.i4
5.10
0.92
2.05
3.34
0.03
9.00
6.94
2010
21,f,J
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As shown in Table 1-1, relatively large amounts of calcium, reported as
the oxide, were present in all of the modified ashes. Also, as would be expected,
samples of dolomite modified ashes contained a higher percentage of
magnesiiun oxide. Although the difference in chemical composition could
be explained by a simple dilution effect of the alkaline earths on normal
flyash, modified ash should be considered a "new-ash" material. The uniqueness
of'modified flyash is best characterized by the physical properties of the
material. Fusion characteristics, as indicated in Table 1-1, show that
initial deformation and melting occur at significantly lower temperatures
than for normal flyash. Mineral wool testing, employing a mixture, of
normal flyash and equivalent amounts of lime as in the modified ash,
demonstrated that the viscosity of molten modified flyash at a specific
temperature was lower than that of a normal flyash-lime mix. Further
evidence of the uniqueness of modified flyash is supplied by the fact
that due to the high resistivity of modified flyash the efficiency of
electrostatic precipitators drops markedly when alkaline earth injection
is used.
Using a modification of the Moorehead and Taylor method for calcium
oxide determination, "free" lime determinations were performed to measure
the amounts of unreacted calcium oxide (CaO) and calcium hydroxide [CaCOH^]
present in the modified ash samples. This "free" lime is capable of mixing
with the inherent pozzolanic portions of flyash to form natural cementitious
materials. The greater the amount of "free" lime present in a modified ash,
the greater are the potential cementitious properties of the ash.
C. Sieve Analyses
Particle size analyses using both dry- and wet-sieve methods were
performed on three modified ashes—limestone injected wet-collecterl KPL,
limestone injected dry-collected TVA and dolomite mixed dry-collected CM. In
this analysis, dry-collected ashes were dry sieved and KPL was wet sieved. These
tests were performed to determine the size distribution of the ashes and to
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provide necessary data for possible beneficiation processes. The size
distributions of the three ashes are:
WEIGHT PERCENT OF TOTAL FRACTION
U. S. S. Sieve KPL TVA CM
+60 mesh 0.6 0.1 0.0
60 x 200 mesh 2.3 33.6 4.6
200 x 325 mesh 5.9 25.6 36.6
325 x 400 mesh 6.5 18.U 56.2
-400 mesh 84.7 21.7 2.6
KPL and CM contain large amounts of fine particles (over 95%, -200 mesh)
which is due, in part, to the mode of collection. Sample KPL was collected
by a wet-scrubbing system; sample CM was collected by an electrostatic
precipitator. On the other hand, TVA modified flyash was collected by a
mechanical hopper which is not as effective for trapping very fine
particles as the other methods. Hence, TVA had the coarsest particle
size distribution of the three samples.
The chemical analysis of each sieve fraction can be found in Table 1-2.
The results are reported as percent of the total compound present in the head
sample. As can be seen from the table, little or no beneficiation of the elements
listed were attained through sieve methods.
D. Microscopic Analyses
Microscopic analyses were performed on wet-collected samples from the
Kansas Power and Light Company (KPL) and from Union Electric of St. Louis
(SLD). Samples were dried and examined under magnification (50x, 500x, 900x)
and appeared to be very similar to the samples of PID, dry-collected limestone
modified flyash, previously studied.
KPL was then separated, using the sink-float technique employed on PID,
into specific gravity fractions ranging from 2.00 to 2.96 SG. The most
visually distinct, separation was observed when using a r.iedium of 2.20 SG. The
float portion was gray in color while the sink was black. Microscopic
observation indicated that the float fraction consisted of approximately
equal amounts of white or yellow, irregulary shaped particles and irregular
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TABLE 1-2
CHEMICAL ANALYSIS OF MODIFIED ASH FRACTIONS
Chemical Analysis
(% of Total Amount Present in Head Sample)
I
CO
Jample
KPL
(wet-sieved)
CM
(dry-sieved)
TVA
(dry-sieved)
Size
Fractions
(USS Mesh)
Head Sample
-1-60
60 x 200
200 x 325
325 x 400
-400
Head Sample
+60
60 x 200
200 x 325
325 x 400
-400
Head Sample
+60
60 x 200
200 x 325
325 x 400
-400
Weight % of
Total Fraction
100.0
0.6
2.3
5.9
6.5
84.7
100.0
0.0
4.6
36.6
56.2
2.6
100.0
0.1
33.6
25.6
18.3
21.7
Si02
29.9
0.3
3.0
8.2
8.0
80.5
35.9
5.1
37.6
54.7
2.6
32.6
0.0
31.2
24.3
20.3
24.2
A1203
8.4
0.0
2.3-
7.0
6.8
83.9
14.4
5.6
42.2
49.4
2.9
16.7
0.0
27.8
26.0
21.6
24.5
12.4
0.3
2.2
6.3
8.3
82.9
7.8
— 4
3.0
20.5
73.4
3.1
4.3
0.0
16.0
28,
23,
Ti02
0.4
0.4
2.0
6.1
6.9
84.7
0.7
5.0
34.7
57.7
2.6
0.6
31.3
0.1
25.7
24.9
21.4
27.9
CaO
19.2
MgO
28.6
0.9
2.0
5.3
4.4
87.4
2.1
0.6
2.3
6.5
7.4
83.2
12.6
1.9
54.3
41.7
2.1
36.8
0.2
42.8
23.8
17.9
15.4
4.4
37.3
88.7
3.2
0.5
0.1
34.0
23.5
19.8
22.8
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black particles. The light colored irregular particles, when hand crushed,
broke into clear hollow spheres, clear solid spheres which were siliceous
in nature and a very fine white powder—calcium constituents. It appeared
that this white powder coats the spheres and binds them together to form
the larger irregular particles. The sink portion was composed of black
spherical particles with a few scattered irregular white ones. When the
black particles were hand crushed, it was observed that they consisted of
ferruginous shells over white spheres which appeared to be siliceous in
nature. Thus, it was found that this wet-collected modified flyash was
physically very similar to the dry-collected material previously tested.
In order to further study the binding of the lighter colored particles,
a head sample of KPL was leached with hydrochloric acid and examined under the
microscope. It was noted that after leaching very little of the bonding
material evident before leaching remained. The leached sample was filtered,
dried and observed again under the microscope. It was evident that the particles
consisted of distinct white spheres and irregular black shapes. The leached
sample was then submitted for chemical analysis by emission spectroscopy.
The analysis showed a reduction in CaO from 27.13 to 21.91 in the leached
portions. Thus, it appears that the particle binding may be attributed to
the calcium constituents of sample KPL.
Flyash sample SLD was also examined using the same methods. The
results were very similar to those reported for flyash KPL except that the
sharpest visual color separation occurred at a specific gravity of 2.30. The
float material was slightly darker to the eye than the float of KPL and upon
microscopic observation was seen to contain a higher percentage of irregular
black particles.
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E. X-ray Analyses
To further characterize modified flyash, samples were submitted for x-ray
analysis. Diffraction patterns were obtained but could not be analyzed as
interpretive difficulties were encountered due to the massive number of
diffraction lines detected and to inconsistent results obtained using
an ASTM program for computer-assisted data reduction. The three most
probable explanations of this are 1) that modified flyash contains a
high percentage of low-ordered structures which produce random
scattering and do not yield distinct patterns which can be resolved; 2) that
the high heats involved in the coal-limestone combustion process produce high-
temperature, metastable structures which cannot be analyzed by diffraction
methods; (These high heats also thermally damage known compounds so that even
those compounds whose diffraction patterns can be found in ASTM specifications
would be very difficult to analyze) and 3) that a more complete chemical analysis
of modified ash is needed. This analysis must determine the presence of not
only the main constituents of the ash (such as calcium or silicon), but
also trace elements and anion constituents so that more information could be
made available. This added information would make the computer program
more reliable.
Concurring with other research^~^ we must conclude that due to the
many low-ordered structures and the few crystalline materials present in
modified flyash, great difficulty is experienced in interpreting x-ray
diffraction pattern of modified flyash. This difficulty is encountered because
x-ray diffraction results are almost entirely dependent on the presence of
crystalline material. Therefore, if a molecular analysis of modified ash
is considered desirable, other methods of investigation should be employed.
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F. Summary
The main constituents of modified flyash are silicon, calcium (and
magnesium if dolomite is used as the modifying stone), aluminum, iron and
sulfur. Wet-collected modified ashes usually have a higher sulfur content
than dry-collected ashes though the amount of sulfur present in the ash is
determined not only by the efficacy of the collection system but also by the
amount of sulfur found in the coal used. The physical melting properties
of modified flyashes are quite similar and all ashes tested melted within a
temperature range of 2150-2300°F. This similarity of physical characteristics
is further substantiated by microscopic analysis. Modified flyash is normally
a powder-like material of small particle size. Predominant size fractions
of almost all ashes tested were 325 x 400 or -400 mesh. Sieve analysis
of the three ashes most often used in this contract showed little or no
beneficiation of elements upon sieving.
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Characterization
1-1 Cockrell, C. F., Muter, R. B., and Leonard, J. W., "Study
of the Potential for Profitable Utilization of Pulverized Coal
Flyash Modified by the Addition of Limestone-Dolomite Sulfur
Dioxide Removal Additives," Final Report, Contract PH 86-67-122,
National Air Pollution Control Administration, April, 1969.
1-2 Anderson, Ronald E., Cockrell, Charles F., _et ial., "Study of
Potential for Recovering Unreacted Lime from Limestone Modified
Flyash by Agglomerate Flotation," Final Report, Contract
PH 22-68-18, National Air Pollution Control Administration,
May, 19770.
1-3 Personal Communication, David T. Clay, Air Pollution Control
Office—Resident Engineer, Shawnee Steam Plant, Paducah,
Kentucky. April 20, 1971.
1-4 Walker, A. B. and Brown, R. F., "Effects of Boiler Flue Gas
Desulfurization Dry Additives on the Design of Particulate
Emission Control Systems," Paper presented at the Dry-Limestone
Injection Process Symposium, National Air Pollution Control
Administration. Gilbertsville, Kentucky, June 22-26, 1970.
1-5 Moorehead, D. R. and Taylor, W. H., "Sucrose Extraction Method
of Determining Available CaO in llydrated Lime," ASTM Bulletin.
No. 236, 1967, pp 45-47.
1-6 Minnick, L. John, "Reactions of Hydrated Lime with Pulverized
Coal Fly Ash," USBM Information Circular 8348: Fly Ash Utilization.
1967, p 312.
-------
-13-
2. CALCIUM-SILICATE STRUCTURAL PRODUCTS
Because modified flyash liberates sorbed sulfur dioxide at elevated
temperatures (between 1700 and 2200°F), it is necessary to find a total
utilization method which would either lock the sulfur into a product or
which would require no large external application of heat. Preliminary research
investigating the natural pozzolanic activity of limestone modified flyash
indicated that some cementitious setting occurred. Such setting is sufficient
to obstruct power plant process lines if water flow should stop, but does not
appear to impart enough strength for structural products. In an effort to
increase pozzolanic activity and consequently strength characteristics and
since the technology has been well developed in Europe using normal flyash,
autoclaved calcium-silicate (CS) building materials were examined as a potential
use for modified ash.
The most common types of CS structural products are brick, concrete and
aerated or foamed cellular concrete. The primary difference between CS brick
and common American products such as cement block or concrete block is that
the CS brick are autoclaved instead of air or steam cured. Autoclaving
produces the desired tobermorite (5CaO * 6Si02 * 5H20 • 6CaO • 6Si02 • 5H20)
type cement binding in a span of hours rather than the days or months
needed to cure cenent or concrete block. Thus, strength and final
dimensions are acquired during the manufacturing process end large curing
storage areas are not required. In addition, the production of CS-type
structural products has two major advantages as a utilization process
for modified flyashes. These are:
1. There are no sulfur gas capture or marketing problems.
All processing occurs below the temperatures necessary
for sulfur dioxide regeneration; and
-------
-14-
2. There have been no pollution problems from soluble
sulfur noted, as the sulfur components of modified
flyash are combined chemically and are bound with-
in the matrix structure of the autoclaved product.
A. Calcium-Silicate Bricks
Calcium-silicate bricks of superior quality (compressive strengths in
excess of 7000 psi) were produced from limestone and dolomite modified flyashes
through the process illustrated in the accompanying flowsheets, Figures 2-0 and 2-1.
Experimental work proceeded in three phases with pellets (1" diameter by
3/8" thickness) being made initially to determine basic composition
mixtures, forming pressures and autoclaving conditions for each
individual modified flyash examined. Samples CM*, dry-collected modified
ash, and KPL*, wet-collected ash, were selected for the second phase of
research—the production of 2" x 4" x 1 3/8" bench-scale brick—as they were
the only ashes of their types available in sufficient quantity. This
phase of the research dealt primarily with such processing variables as
forming pressure, mixing, humidity curing, etc. In the final phase, full
size brick were produced using common commercial equipment to determine
whether, in actuality, the process could be scaled up.
Data obtained from the pellet tests indicated that CS brick could be
produced from modified flyash. When using dry-collected modified flyash, the
brick mix consisted of 50% (on a dry basis) modified flyash, 50% silica sand and
approximately 20% water (see Figure 2-0); when wet-collected modified flyash was
used, CS brick could be produced containing 50% (on a dry basis) modified flyash,
39% sand and 11% calcium oxide (see Figure 2-1). Using wet-collected KPL flyash,
the process involved a dewatering of the slurry to 34% water before mixing.
Such a composition provides sufficient water for mixing and forming of the
green brick.
*These ashes are described in detail in the Characterization Section of this
report.
-------
-15-
Figure 2-0
Silica Sand
(30x100 Mesh)
Dry-Collected Dolomite
Modified Flyash
50% Flyash + 50% Silica Sand
+ Water
Muller-type Mixer
(10 Min.)
Slaking Reactor
(1 Hour)
Pressing Load
3750 psi, 17% HO
47 Hour Humidity Storage
95% Rel. Humidity at
Room Temperature
Autoclave, 8 Hours
190 psig, 185°C
Water
(20% of total weight)
72 Hours Air
Drying
Flow Sheet: Optimum Conditions for the Production of Calcium-Silicate
Brick from Dry-Collected Modified Flyash.
-------
FIGURE 2-2
THE RELATIONSHIP OF THE RATIO OF COMPACTION AND PRESSING LOAD FOR
KPL? BRICK MIX
1.9 -
1.8
1.7
o
o
ii_
O
o
!5
or
1.6
1.5
/ I
Ratio o1 Compaction- Ratio of Ihe Volume of a Brick Pressed
at Load "n" to the Volume of a Brick
i
al Zero Load.
Pressed
i
2 KPL - Wei-Collected
Limestone Modified
1.4
Flyosh - Kansas Power and Light Co.,
Lawrence, Kansas.
1.3
_L
-L
_L
J_
625
1250
1875 2500 3125
PRESSING LOAD - (psi)
3750
4375
500O
-------
2.0
1.9
FIGURE 2-2o
THE RELATIONSHIP OF THE RATIO OF COMPACTION AND PRESSING LOAD FOR
CM BRICK MIX
o
Q.
5
O
o
u.
o
o
1.8
1.7
1.6 -
i •
CM - Dry-Collected Dolomite Modified Flyash-
Khevrolet Motor Division, St.Louis,Mo.
1.5
_L
_L
625
1250
1875
2500 3I25
PRESSING LOAD-(psi)
3750
4375
5000
5625
-------
FIGURE 2-3
THE RELATIONSHIP OF PRESSING LOAD TO PEKCENT ABSORPTION
AND TO COMPRESSIVE STRENGTH IN KPL BRICK
40
- 3400
Q.
cc
o
V)
CD
UJ
O
cc
UJ
OL
20
1875
2500
3125 3750 4375
PRESSING LOAD- psi
50OO
5625
2200
i
M
VO
-------
FIC"
THE RELATIONSHIP OF HUMIDITY STORAGE TIME TO COMPRESSIVE
STRENGTH AND TO PERCENT ABSORPTION IN K PL BRICK
42
40
O
t-
a.
tr
o
to
m
u
UJ
a
38 -
36 -
34 -
32 -
3O
3500
30OO
2500
10
a.
o
z
UJ
cr
20OO
N)
O
a:
a.
Percent Absorption
1500 o
1000
0
24
48
72 96 120
HUMIDITY STORAGE- HOURS
144
168
5OO
-------
RE
THE RELATIONSHIP OF CURING TIME TO COMPRESSIVE STRENGTH
AND TO PERCENT ABSORPTION IN KPL BRICK
36
35
Q.
(E
O
CO
CD
Z
UJ
O
£E
UJ
Q.
33
32
31
30
3200
300O
2800 •
X
I-
o
UJ
o:
2600
UJ
>
to
CO
Q.
2400 O
22OO
8
12 16 20
CURING TIME - HOURS
24
28
2000
i
N)
-------
-22-
Ratio of compaction diagrams included as Figures 2-2 and 2-2a, were
prepared for CM and KPL brick mixes to aid in the determination of optimum
pressing loads. Figures 2-3 through 2-5 illustrate how other process
factors for the production of brick fron KPL were optimized. In addition
to such factors as pressing load, humidity curing time and autoclaving time
shown in these figures, it was noted that intimate mixing is a necessity.
A muller-type mixer proved satisfactory for this step.
In the final phase of the testing program, 2" x 4" x 8" full size brick
samples were prepared using a hydraulic-toggle dry-press. The final products
met or surpassed ASTM (73-51 and 73-67) specifications of 4500 psi compressive
strengths and less than 1% shrinkage for grade SW, severe weathering, calcium-
silicate brick. An average batch of brick made from dry-collected ash dis-
played characteristics of 4600 psi compressive strength, 20% absorption
and no measurable shrinkage; wet-collected ash produced brick with an average
4500 psi compressive strength, 28% absorption and no measurable shrinkage.
Production conditions for an optimum product can be found in Figures 2-0 and 2-1.
B. Aerated Concrete
Aerated or foamed cellular concrete is a lightweight structural material
consisting of small non-communicating gas cells entrained in a calcium-
silicate matrix. It is produced by inducing gas bubbles within a cementitious
paste normally composed of cement and/or lime and a fine grained siliceous
material.
The bubbles of gas are produced by one of two general methods:
1) By the formation of gas by chemical reaction within the
mix during the liquid or plastic stage, for example:
2A1 + 3Ca(OH)2 + 6H20 - »3CaO • A1203 • 6H20 + 3H2 f ;
or
2) By introducing air from without, either by adding a preformed
foam or by incorporating air by whipping.
-------
-23-
When the first method is used, the hydrogen in the cells are replaced
by air in a short tine. Therefore, no fire hazard exists when foam is formed by
2—Q
hydrogen gas. 7 The gas-cement mixture is allowed to set in air and is then
steam cured at high pressure. Aerated concrete made in Europe using normal
coal flyash as the siliceous component is high in strength and light in
weight—their beat products having compressive strengths of 200-800 psi for
concrete with a desntiy range of 30-45 Ib/cu ft. Aerated concrete also exhibits
advantageous thermal insulation and acoustic proper!tes.
Aerated concrete was produced from dry-collected limestone modified
flyash using the process shown in Figure 2-6. The technology employed is
essentially that used by European manufacturers with one basic exception.
Utilizing the "free" lime content in dry-collected modified ash, the addition
of lime is not required—a significant cost factor. Aluminum powder is used
to generate gas bubbles and portland cement is added to provide strength.
Dry-collected limestone modified flyash from the Shawnee Steam Plant
at Paducah, Kentucky (TVA) was selected for the bench-scale production of
aerated concrete because of its high reactive or "free" line content and its
large siliceous component. It was found that aerated concrete could be
prepared from this ash without the use of any additional material except
water and aluminum powder—the aerating agent. The cured concrete had a com-
pressive strength of 400 psi at a density of approximately 50 lbs/ft3. Portland
cement was then added to the mix to increase the compressive strength of the
product. Although the density increased to 56.3 Ibs/ft3 when using cement, the
compressive strength was increased to more than 855 psi. The addition of
Portland cement also stabilized the aerated mix prior to autoclaving. This is
a critical factor, as setting must occur after aeration is completed and before
the entrained bubbles collapse.
-------
-24-
FIGURE 2-6
Mech. Precip. - Dry-Collected
Limestoae Modified Flyash (92%)
', Portland Cemeat
Type I, Normal
0.16% Aluminum
Powder
Paddle Mixer
(10 Minutes)
Pour into Molds
8 Hour
Air Set
Autoclave, 16 Hours
190 psig, 185°C
72 Hour Air
Drying
FLOW SHEET: AERATED CONCRETE
-------
-25-
Only a preliminary investigation has been completed concerning the
production of aerated concrete from modified flyash. Results of this work,
however, are highly promising as the compressive strengths obtained in a
few tests rivaled those found in the European product and it is felt that further
study should be conducted in this area by testing other setting agents (such as
CaClo and triethanolamine) to further increase the strength and lower the
density of the final product.
C. Formed Concrete Products
The natural pozzolanic properties of modified flyash indicated that a
potential use might be as a cementing agent in concrete materials. Because
research on CS brick production showed that autoclaving increased calcium-
silicate bond formation, further research was performed to investigate the
feasibility of using modified ash as the cementing agent for the production
of concrete block.
Included as Figure 2-7 is the process flowsheet employed in this phase
of research. It should be noted that the composition is the same as for CS
brick with the exception that less dewatering is required. Also, it should be
pointed out that the material is poured into molds instead of pressed. As
with CS brick, this composition consisted, on a dry basis, of 50% wet-collected
modified flyash, 39 percent silica sand (30 x 100 mesh) and 11 percent lime
(95 percent CaO). The resulting poured concrete which is similar to concrete
3 3
block had a bulk density of 90 Ib/ft as compared to 150 Ibs/ft for
conventional concrete block and a compressive strength of approximtely 900
psi as compared to 1000 psi for conventional block. Although addition of the
2
necessary aggregate could raise the bulk density to 100 Ib/ft , this would still
be only 2/3 the bulk density of standard block. Storage requirements could also
be reduced as this is a full strength, non-shrinking product out of the
autoclave and does not require the 3 to A weeks air curing time before sale as
-------
Silica-Sand
30 x 100 Mesh
-26-
FIGURE 2-7
Wet-Collected Limestone
Modified Flyash (1% Slurry)
Dewater Ash
to 58% H20
50% Ash + 11% CaO
+ 39% Sand
Paddle Mixer
(10 Minutes)
Pour into
Molds
24 Hours Thermal
Set (110°C)
Lime (CaO)
96% Pure
Autoclave, 16 Hours
190 psig, 185°C
72 Hours Air
Drying
FLOW SHEET: FORMED CONCRETE
-------
-27-
does conventional concrete block. In addition, besides low cost of the raw
material, an advantage of the use of modified ash is that no prior grinding or
crushing of the raw material is required.
D. Conclusions
Modified flyash is an acceptable raw material for calcium-silicate
building products. Brick, concrete block and aerated concrete have been
produced from modified ash and display physical characteristics that approach
\
or equal those of conventional materials. However, certain cost factors and
marketing situations effect the practicality of producing calcium-silicate
building materials from modified ash. The low cost of raw materials (eg,
in some areas flyash sells for as little as $1 per ton) reduces the production
of CS material and the reduced weight of the material decreases the handling
and labor costs at final construction sites. Conversely, in the United States
the production of CS building material involves new techniques of production such
as autoclaving and dewatering. In addition, there exists a lack of acceptance
by American industry of new building products. Therefore, even though the
production of CS building material from modified ash has been shown to be an
implemental flyash utilization scheme and a practical method for producing
quality building products, the large capital investments involved in structuring
new processing plants and the resistance of labor and the structural clay
products industry in accepting new building materials appear to be an overwhelm-
ing economical deterrent to the commercial production of CS building products.
-------
-28-
Sand-Lime Brick
2-1 Brick and Tile Construction. Structural Clay Products Institute,
Washington, D. C., 1964.
2-2 Mateos, Manuel, "Heat Curing of Sand-Lime-Flyash Mixtures,"
Materials Research and Standards. May, 1964, pp 212-217.
2-3 Oberschmidt, Leo E., "Widespread Interest Signals The Resurgence
of Sand-Lime Brick," Brick and Clay Record. Vol. 154, No. 4,
April, 1969, pp 16-18.
2-4 Redecker, Iramo H., "Sand-Lime Bricks," Speech delivered at the
Southeastern Section American Ceramic Society, Gatlinburg,
Tennessee, July 1, 1966.
2-5 Seigle, H. D., "Method of Making Bricks," U. S. Patent No. 3499069,
March 3, 1970.
2-6 Society of Chemical Industry, Autoclaved Calcium Silicate Building
Products. Gordon and Breach Scientific Publishers, Inc., New York,
1967.
2-7 "Standard Specifications for Calcium-Silicate Face Brick
(Sand-Lime Brick)," ASTM Designation C73-67, ASTM Standards
Part 12, 1968, pp 686-687.
2-8 Taylor, W. H., Concrete Technology and Practice. American Elsevier
Publishing Company, New York, 1965.
2-9 PFA Data Book. Central Electricity Generating Board, England, 1969.
-------
-29-
3. SULFUR DIOXIDE REGENERATION
The primary purpose of limestone/dolomite injection scrubbing systems
is to entrap the harmful sulfur dioxide gas produced during the combustion
of coal thereby resulting in cleaner effluent gases. Theoretically, the
carbonate rocks are calcined by the high heats present in the boiler during
combustion,
A t
eg, CaC03 » CaO + C02 I . (1)
The calcined lime (CaO) then reacts with the sulfur dioxide present in the
stack gas to form sulfate, and some sulfite or sulfide compounds. Some
possible reactions are:
CaO + S02 »CaS03; (2)
CaS03 + 1/2 02 ^CaSO^; and (3)
4CaS03 *-3CaS04 + CaS. (4)
If regeneration is feasible, the high concentration of sulfur compounds present
in modified ash could prove to be a practical reservoir of sulfur dioxide gas
for later use by industry.
A. Experimental Method
Tests were undertaken to determine the feasibility of regenerating
sulfur dioxide from modified flyash. A pre-heated tube furnace was continuously
flushed with compressed air, the carrier gas, to effect an oxidizing atmosphere.
Once a specific temperature was obtained, measured samples of both dry- and
wet-collected modified flyash were placed in the center of the heated tube.
Due to the small sample size, it was assumed that the equilibration of sample
temperature to tube temperature was immediate. The effluent gases from the
heating process were passed through an infrared spectrometer to identify the
evolved gases. They were then passed through specific absorbing mediums (such
as ascarite) to absorb any carbon dioxide or water vapor before sulfur dioxide
-------
-30-
FIGURE3-Q
SCHEMATIC OF EXPERIMENTAL DESIGN
SAMPLE
THERMOCOUPLE
FLOW
METE
CARRIER GAS VESSEL
TO AIR:
UNTREATED
CARRIER GAS
OVEN
\ /
'/////////A
POTENTIOMETER
FOR SETTING
SPECIFIC
TEMPERATURE
STRIP
CHART
RECORDER
TITRATION
ANALYSI S
INFRARED
SPECTROMETER
-------
-31-
levels were measured by titration methods. Other experimental parameters
were:
Diameter of Reactor Tube 2.8 cm
Sample weight 2.0 g.
Temperature Range 1100-2200 °F
Rate of Heating* rate of equilibration (less than 1 minute)
Carrier gas ~ compressed air
Approximate gas velocity over sample 33.5 cm/rain.
Infrared frequency band for S02 determinations 1340 cm~^
The resultant ash was also tested to determine what effect heating
had upon the "free" lime (CaO) values of the ash, ie, the amount of unreacted
calcium oxide present in the ash after gas evolution. For a schematic of the
experimental set-up, see Figure 3-0.
Other measurements determined included the temperature of maximum sulfur
dioxide evolution, the rate of evolution and the relative concentration of
sulfur dioxide.evolved.
B. Results
Both wet-collected KPL and dry-collected CM evolve sulfur dioxide
when heated in an oxidizing atmosphere. Carbon dioxide and water vapor
are also evolved. The rate of evolution of sulfur dioxide is temperature
dependent; evolved concentrations, however, are dependent both on temperature
and on the flow rate of air which causes dilution effects on the evolved gases.
Sulfur dioxide slowly evolves from CM when the ash is heated to
temperatures over 1800°F. The rate of evolution increases with increasing
temperatures until approximately 2180° + 10°F above which the sample melts.
For example, under constant air flow and at 2130 + 10°F, 43% of the total
sulfur dioxide present in the sample (6.32 wt. %) is evolved within 5 minutes,
while at 2180 + 10°F, over 90% of the total sulfur dioxide is evolved in the
same time period. If the sample is allowed to remain at 2180 + 10°F for 10
minutes, 99% of the total sulfur dioxide is evolved. Therefore, this temperature
may be considered the lowest temperature of maximum evolution, ie, the maximum
-------
-32-
amount of sulfur dioxide is evolved in the shortest time period. Also,
at this temperature the physical integrity of the sample is not affected.
The relationships between temperature and the amount of sulfur dioxide evolved
for sample CM are shown graphically in Figure 3-1. The concentration
of the evolved sulfur dioxide gas is dependent upon the air flow sweeping the
sample. By adjusting the rate of air flow, concentrations of nine to thirteen
percent sulfur dioxide were obtained. These concentrations are within the
optimum concentration range of sulfur dioxide for use as a sulfuric acid
plant feed stock. Figures 3-4 through 3-8 illustrate the relative concentrations
and total amounts of sulfur dioxide evolved at various temperatures. The
sulfur dioxide gas evolved upon heating is relatively pure. Only two
impurities were noted; they are carbon dioxide (C02) and water vapor. Both
impurities are completely evolved within the first three minutes of heating
and can be removed at much lower temperatures—approximately 1380°F. Also,
in sulfuric acid manufacture, carbon dioxide is usually considered an inert gas
which does not disturb the process. Therefore, the sulfur dioxide gas released
when heating sample CM in an oxidizing atmosphere can be considered to be a
pure acid feed stock that is evolved in a short time and in large
quantities.
Sulfur dioxide begins to evolve from dried KPL ash at 1700 + 10°F. Like
CM, the rate of evolution increases with increasing temperatures but for KPL
this increase is much less rapid (See Figure 3-2). Although KPL begins to melt
at 2150 + 10°F, a slightly lower temperature than the initial melting point
of CM, longer times were required to evolve the same fraction of the theoretical
yield of sulfur dioxide when heating KPL than were observed when heating CM.
The theoretical total yield of sulfur dioxide in sample KPL is 10.34% by weight.
For example, at 2150 + 10°F, 96% of the total yield is given off in 20 minutes,
while at 2010 + 10°F only 24% is evolved in the same time period. The temperature
-------
FIGURE 3-1
THE AMOUNT OF SULFUR DIOXIDE GENERATED BY HEATING SAMPLE CM?
AT VARIOUS TEMPERATURES
100 -
T1
A- 2177.6* F
B- 21 27.2 • F
C- 2OI2.O* F
D- I922.O* F
Dry-Collected Dolomite Modified Flyash
10
15
20
25
30
35
40
45
TIME- MINUTES
-------
FIGURE 3-2
100
80
CNJ
o
I
O
60
-------
-35-
of maximum evolution of sulfur dioxide is 2150 + 10°F, 30°F lower than the
maximum evolution temperature CM. Figures 3-9 through 3-13 illustrate the
relative concentrations and the total amounts of sulfur dioxide evolved from KPL
at various temperatures. Particular notice should be given to the late
breakdown of one of the sulfurous constituents of KPL which is noted by the
infrared spectrometer as the third peak found in Figures 3-9 through 3-13.
This late sulfur evolution lengthens the time necessary to drive off the sulfur
dioxide from the sample. The origin of this peak of sulfur dioxide evolution
cannot be determined under the scope of the present contract and no plausible
explanations have been speculated. Even with an extended heating period, however,
concentrations of 9 to 13 percent sulfur dioxide have been obtained. Impurities
found in the evolved gases are again carbondioixde and water vapor. However,
less carbon dioxide is evolved when heating KPL than when heating CM. The
average amount of carbon dioxide evolved from KPL is 0.05 grams per gram of
sample; when heating CM, 0.135 grains per gram of sample is evolved. Again,
both impurities may be fractioned off at temperatures lower than those necessary
for sulfur dioxide evolution.
Studies were also performed on both the ashes to determine what effect
heating had upon the "free" lime (CaO) content or cementitious capability of
each ash. Prior to heating, sample CM contained approximately 9 percent "free"
lime—KPL about 2 percent. Measured samples of modified ash were heated under
oxidizing conditions and their "free" lime contents were measured at various
temperatures (See Figure 3-3). The "free" lime contents of both sample KPL and
CM increased in the temperature range of 1290 + 10°F and 1740 + 10°F. In this
temperature range the "free" lime content of CM doubled, while in the same range,
KPL displayed a three-fold increase in CaO. This increase in "free" lime is not
a function of sulfur dioxide evolution or the breakdown of calcium sulfates since
this increase occurs below the minimum sulfur dioxide evolution temperature.
It is the decomposition of uncalcined calcium carbonates (CaCO-) present in
-------
IGL
3-:
"FREE" LIME CONTENT OF WET AND DKY-COLLECTED MODIFIED FLYASHES
25 -
4- SAMPLE KPL,WET-COLLECTED
B- SAMPLE CM, MY-COLLECTED
i
10
I20O
1300
1400
I50O I60O
TEMPER ATURE-°F
I7OO
I8OO
I9OO
-------
-37-
the ash that increases the CaO content of each ash. This increase is compound
specific and it is well to note that the maximum increase of "free" lime
content for both ashes occurs at the decomposition temperature of calcium
carbonate (V*1500°F). This "free" lime content decreases at higher temperature
due to the dead or hard burning of the lime. Therefore, sulfur dioxide
regeneration of modified ash does not beneficiate the cementitious capabilities
of the heated ash.
Conclusions
Both dry- and wet-collected modified ash regenerate sulfur dioxide in
concentrations favorable to sulfur acid manufacture. To use modified flyash
as a sulfuric acid feedstock on an industrial scale, modified flyash may be
considered analogous to pyrite. Both raw materials must be roasted or burned
in air to produce sulfur dioxide gas; and when the pyrite considered is a by-
product from flotation separation, both raw materials are finely sized. Also,
the heating temperatures of both materials are somewhat similar (about 1700-
2000°F for pyrite and 1900-2200°F for modified ash.) Therefore, under favorable
conditions, the gross processing variables of both raw materials are similar
and it would initially appear that the cost of producing sulfuric acid from
modified flyash is economically similar to the cost of producing sulfuric
acid from finely ground pyrite.
From a practical point of view, however, it would take ten times more
modified ash to produce the same amount of sulfur dioxide as pyrite. (Pyrite
contains 35-52% sulfur; flyash contains about 3.6% sulfur on the average.)
Even selling as cheaply as $1 per ton, it would cost $10/amount of S02 for
a modified ash raw material while the same effective amount of pyrite
would cost $7.50. Also, this increase in raw material volume would appreciably
increase the production costs, the cost of waste disposal and the initial
investment cost. For these reasons the production of sulfuric acid from
modified flyash cannot be competitive with existing processes unless a major
supplementary use can be made of the non-sulfur bearing portions of the ash.
-------
FIGURE 3-4
CM FLY ASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED AND
THE TOTAL AMOUNT EVOLVED AT 1922.0° F.
100
80
UJ
£ 6O
•t
o
40
20
O
I
OJ
00
o
z
o
o
CM
o
V)
o
Ul
(E
o
INFRARED ABSORPTION-RELATIVE CONCENTRATION
_L
10
15 20 25
TIME-MINUTES
30
35
40
-------
FFGURE 3-5
CM FLY ASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED
THE TOTAL AMOUNT EVOLVED AT 2012.0° F.
AND
100 r
vO
IS 20
TIME-MINUTES
25
3O
35
40
-------
FIGURE 3-6
CM FLYASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED AND
THE TOTAL AMOUNT EVOLVED AT 21272° F.
100 r
80 -
_
o
uj
-------
FIGURE 3-7
100 -
o
I-
UJ
g
CM FLYASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED AND
THE TOTAL AMOUNT EVOLVED AT 2177.6°F.
I.R. ABS. R£L. CONC.
<
UJ
>
IE
CM
O
CO
20
TIME-MNUTES
25
30
35
40
-------
100
80
(M
O
in
I
3 60
O 40
Id
X
20
FIGURE 3-8
KPL FLYASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED AND THE
TOTAL AMOUNT EVOLVED AT
1742° F.
z
o
ID
o
z
o
o
UJ
IT
O
% YIELD
LR. ABS. REL. CONC.
T.
10
15 20
TIME- MINUTES
25
30
35
40
-------
I 00 r-
FIGURE 3-9
KPL fLYASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED AND
THE TOTAL AMOUNT EVOLVED AT 1922° F.
80 -
(VI
O
eo
UJ
K
3
40
20
I.R. ABS. REL. CONC.
ui
00
o
CO
to
tr
o
10
I 5
20 25
TIME-MINUTES
30
35
-------
100
FIGURE 3-10
KPL FLYASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED AND
THE TOTAL AMOUNT EVOLVED AT 2012° F.
80
£
a
Ul
O
UJ
I
6O
40
V)
O
z
I
z
O
LU
O
O
O
eg
O
-c-
I.R ABS. KEL. CONC.
UJ
(E
40
-------
FIGURE 3-11
KPL FLYASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED
THE TOTAL AMOUNT EVOLVED AT 2102.0° F.
AND
100 r
80 -
-------
FIGURE 3-11
KPL FLYASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED AND
THE TOTAL AMOUNT EVOLVED AT 2102.0° F.
100 r
80 -
CJ
O
co
I
Q
_l
UJ
60 -
UJ
cc
S40
20 -
CO
}-
z
O
<
oc.
O
O
O
(M
O
tn
CO
<
UJ
cc
O
Ul
I
10
15
20 25
TIME-MINUTES
30
35
40
-------
THE
FIGURE 3-12
KPL FLYASH
RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED AND
THE TOTAL AMOUNT EVOLVED AT 2127.2* F
100 i-
80 -
CM
O
0
_l
UJ
>-
60 -
UJ40
g
20
/. R. ABS. fffL. CONC.
15
20 25
TIME-MINUTES
30
35
40
-------
FIGURE 3-13
KPL FLY ASH
THE RELATIVE CONCENTRATION OF SULFUR DIOXIDE EVOLVED AND
THE TOTAL AMOUNT EVOLVED AT 2147.0° F.
100 r-
IA. ABS. PEL. CONC.
I
-C-
10
IS
20 25
TIME-MINUTES
30
40
-------
-48-
Sulfur Dioxide Regeneration
3-1 Boynton, Robert S., Chemistry and Technology of Lime and Limestone.
Interscience Publishers, Inc., New York, 1967, pp 5-31.
3-2 Karchraer, J. H., "The Analytical Chemistry of Sulfur and Its
Compounds," Chemical Analysis. Vol. 29, Interscience Publishers,
Inc., New York, 1970.
3-3 Moorehead, D. R. and Taylor, W. H., "Sucrose Extraction Method
of Determining Available CaO in Hydrated Lime," ASTM Bulletin.
No. 236, 1967, pp 45-47.
3-4 Duecker, Werner W., and West, James R., The Manufacture of Sulfuric
Acid. Robert E. Krieger Publishing Co., Inc., Huntington, Hew York,
1961.
3-5 Connor, J. M., "The Economics of Sulfuric Acid Manufacture," Preprint 6D
American Institute of Chemical Engineers, Sixty-First Annual Meeting,
Los Angeles, California, December, 1968.
-------
-49-
4. MINERAL WOOL
As a result of highly promising data obtained in earlier phases of
(4-1)
research, mineral wool production was continued under this contract
in order to (a) test a wider variety of modified flyashes and (b) produce
samples for additional quality testing and comparative economic evaluation.
A carbon-arc tilting furnace was used to melt the samples and mineral wool was
produced by pouring the molten material from the furnace in a thin stream and
into a Jet of compressed air. The air imparted a shearing force to the
molten mass, breaking the stream into small droplets which were propelled
through the air and formed fibrous "tails." Any solid remnants of the
original droplets are termed "shot."
A. Modified Flyashes Tested
The modified flyashes tested and their mineral wool production
characteristics are given in Table 4-1.
As shown in Table 4-1, the pouring temperature of the modified ashes was
approximately 2700°F with the exception of SLD which was poured at 2800°F.
All pouring temperatures were below those necessary for wool production from
bottom ashes and current commercial raw materials. Blowing pressures ranged
between 90 and 95 psig, and were within the range utilized in the previous
tests on coal bottom slag and modified flyashes.
A significant difference was observed in the production yields from the
individual samples. A much higher yield was obtained from sample KPL, the
only wet-collected limestone modified flyash available, than from the dolomite
flyash. The lowest yield was obtained from sample CM, dry-collected dolomite
modified flyash, in which the coal and dolomite were premixed upon entering
the combustion area. In comparing the acid/base ratios (percent silica plus
percent alumina)/(percent lime plus percent magnesia) sample KPL at 1.30 falls
-------
TABLE 4-1
PRODUCTION CHARACTERISTICS OF MINERAL WOOL
Sample
KPL
SLD
CI
CM
Type
Wet Collected Limestone Modified
Wet Collected Dolomite Modified
Dry Collected Dolomite, Mixed
Pouring Blowing
Acid/Base Temp. Pressure
Ratio ^F psig
Dry Collected Dolomite, Injected 1.58
Yield
1.30 2700 92 High
1.87 2800 90 Moderate
2700 93 Moderate
1.52 2700 95 Low
Comments
Light brown, short fluffy
fiber, very little shot
Gray, some brittle fiber,
moderate shot
Gray, resilient fiber,
moderate shot
Gray, fluffy fiber, heavy
shot
i
?
CU
Unmodified
9.79
3000
95 None
No fiber formed
-------
-51-
closest to the generally accepted mineral wool production range of 0.85 to 1.25.
SLD and CI (1.87 and 1.58 respectively) had lower yields than KPL.
Although samples CM and CI were produced from the same coal and the
same dolomite, a difference in their yields of mineral wool was noted,
possibly due to the different methods of introducing the dolomite at the
boiler. Sample CM was formed by premixing the dolomite and coal before
pulverization and entry into the boiler while sample CI was formed by
injection of the dolomite above the flame envelope.
Unmodified ash sample CU was utilized as a control. As shown in Table
4-1, no fiber could be produced even at temperatures as high as 3000°F.
B. Quality Tests
Results of quality tests performed to date are given in Table 4-2. These
tests were performed in accordance with the Department of Commerce, Commodity
Standards Division: Commercial Standard CS 131-46. All test samples were
shaken on a Tyler laboratory screen (6 mesh) prior to quality testing in
order to remove any loose shot. A sample of commercial mineral wool was also
tested for comparative purposes.
Attached Shot Attached shot is a measure of the shot attached to the
fibers or entrapped by them. The shot content of commercial products
range from 30 to 40 percent. The dolomite modified flyash samples fall
within these limits while mineral wool produced from limestone modified
flyash, KPL, has an even lower percentage of attached shot. The attached shot
could be removed by regular processing methods used in the mineral wool
industry.
Shot formed during the blowing of samples KPL and SLD was collected and
reheated to determine if remelting of the shot would be feasible. The
mineral wools produced were of the same quality as those obtained from
the initial ashes under the same test conditions.
-------
TABLE 4-2
QUALITY TESTS ON MINERAL WOOL
Average Attached Moisture
Fiber Shot Adsorption
Sample Diameter wt. 2 wt. Z
KPL 2.5/j 14.0 0.001
SLD 3.0^j 32.0 0.00
CI 5.6^ 34.0 0.00
CM 5.4^/ 36.0 0.00
Commercial 8.4*
N/A
0.00
Odor
Emissions
Fire
Resistance
No Apparent Difference Incombustible
No Apparent Difference Incombustible
No Apparent Difference Incombustible
No Apparent Difference Incombustible
No Apparent Difference Incombustible
Corrosion
Re tardance
Non-corrosive,
no etching
Non-corrosive,
no etching
Non-corrosive ,
no etching
Non-corrosive ,
no etching
Minor Corrosion,
no etching
to
I
-------
-53-
Moisture Adsorption Ten gram samples of each test batch were dried to a
constant weight at 120°F in a drying oven and placed in a humidity chamber.
The samples were held at 120°F, 95 percent relative humidity for 96 hours and
were then immediately reweighed and the percent moisture adsorption by
weight determined. As shown in Table 4-2, none of the samples adsorbed a
noticeable amount of moisture. These values compared favorably with those
found for commercial mineral wool.
Odor Emissions For the odor emissions test, equal volumes of mineral wool
samples were separately placed in closed petri dishes beside a 1" x 1" x 1/4"
pat of fresh butter. After 24 hours, the pats of butter were smelled and
tasted by three laboratory technicians. No apparent difference was found
between the test samples and the control.
Flammability Mineral wool test samples were placed on a wire screen and
backed with asbestos board. They were then placed above a natural gas-air
burner. The hottest point of the flame was adjusted to touch the samples.
The temperature was brought to 1600°F and maintained for forty minutes. All
of the test samples were rated incombustible.
After the test, it was noted that the wool produced from sample KPL
was a lighter color where it had been in contact with the flame. This phenomenon
is presumably due to the oxidation of surface of the sample. The commercial
wool, however, lightened to a greater degree.
Corrosion Retarding Properties Cold rolled steel strips were covered with
mineral wool and placed in a humidity chamber for 96 hours at 120°F and
95 percent relative humidity. All of the modified flyash mineral wools
tested proved to retard corrosion of the test strips. No chemical etching
of the test occurred although extensive surface rusting and pitting was
noticed. The modified flyash mineral wools also showed superior corrosion
retarding properties when compared with commercial wool.
-------
-54-
Fiber Diameter
Random samples were taken from the modified flyash mineral wools and
examined microscopically to determine the fiber diameters and to check for
unfavorable crystalline inclusions. Commercial mineral wool was utilized
as a control. The most satisfactory mineral wools have average fiber
diameters which range from two to ten microns. In this range, they exhibit
the softness and resiliency desired. As shown in Table 4-2, all of the
modified flyash mineral wools are within this range. It was noted that
the commercial wool averaged many more fibers above the range of two to ten
microns than did the four modified flyash mineral wools tested. This uni-
formity of fiber diameter for modified ash base mineral wool is dependent
upon a uniform viscosity at pouring temperatures. Although modified ash is
composed of distinct particles of lime and flyash, when heated it acts
as if it were a homogeneous mixture of silica and lime and, therefore, the
melt is more uniform than that obtained from the industrial cupola charge of
siliceous and calcareous material.
In addition, microscopic observation indicated that no unfavorable
crystalline inclusions existed in any of the modified flyash mineral wool
samples.
C. Cost Analysis
The economic feasibility of mineral wool production was estimated
based upon information received from Combustion Engineering Company, Inc.
Data show that moderate to good profits may be anticipated from modified
flyash mineral wool production. A copy of the preliminary production
cost estimate can be found in Table 4-3.
For mineral wool selling at $100 per ton and a plant producing six
thousand (6,000) tons of mineral wool a year, the cost of production would
be about 75% of the final product value. Using these assumptions, the
plant payout time is a very attractive 1.5 years. However, because suitable
-------
TABLE 4-3 .55.
WEST VIRGINIA UNIVERSITY
COAL RESEARCH BUREAU Dal
PRELIMINARY PRODUCTION COST ESTIMATE By.
Copital Investment:
Total
Less Working Capitol
Less Salvage Value
Depreciable Investme
Raw Materials
(1) ««h 19 1 1TT/T Unnl
Olrolus 0 6500/T Wool
(V)
la
(5)
Mix Credits and Debits
(£)DlBpoBnl nf • ,,
(71
mi
(9)
Direct Expense
(II) Steam
(B) Vjater (reciri) mat. up
113) fS&r (90 psfl e10*
(14) Electricity 150 Cfn
(IS Fuel ( Coke)
(16) Fuel ( )
(17) Labor
(18) Supervision
(19) Maintenance
CO) Factory Supplies
(21) Indirect Overhead
(22) Payroll Overhead
(23) Laboratory
(24) Contingencies
(2S Tol
Indirect Expense
(26) Depreciation
(27) Real Estate Taxes Q Insurant
(28) Depletion Allowances
(29) Amortization
(30) Tola
(3D
02)
(34) TO
o™M, WVU Coal Research
• MAS 'Prtf' N"A" A"""
FNP l-Hf. "•** no,.
Annual Quantity Unit Cost f/Yeor
c,n
0.21
11.10
4.44
0.74
1.00
4.17
0.83
_
5.00
545. UU
55.87
20 00
75.87 (.vnr\
-------
-56-
Estimate does not include buildings and working capital, or shipping costs,
Value of Product - $100/Ton FOB Plant
250.000
Plant Payout Time - 169,800 =1.5 yrs.*
*Appears attractive if building costs are not considered.
If buildings are included in the investment figure, payout time will be
approximately 3.0 years which is marginal for investment purposes.
Conclusion: Moderate profits can be anticipated from this process.
However, the payout time indicates that the investment
is not exceptionally attractive in comparison to other
investments unless existing buildings can be made available
for use.
-------
-57-
data was not available, this cost analysis does not include costs of buildings
and working capital, shipping cost or pollution control devices. These expenses
would increase the plant payout time considerably (eg, considering building
costs alone, payout time approximates 3 years). This analysis does not assume
recycling of the shot or the practical usage of the sulfur dioxide gas evolved
during the heating of modified flyash. If employed, both of these factors
could effectively reduce the production costs and payout time. Therefore, if
existing buildings can be made available for use and if the resulting sulfur
dioxide gas can be marketed, investments in mineral wool production may
prove attractiwe.
Conclusion
Modified flyash is an excellent raw material for the production of
mineral wool. The physical characteristics of wool fibers produced from
modified ash equal or excel commercially available mineral wool. They dis-
play negligible moisture absorption values and superior corrosion retarding
properties and may be rated as incombustible. Also, modified ash based
mineral wool is soft, resilient and has uniform fiber diameter. Cost-
figures received from a mineral wool manufacturing company show that a
modified flyash based mineral wool plant is economically attractive. Also,
due to the growing energy crisis, especially with respect to natural gas reserves,
more and more construction companies are building electrically heated homes
and buildings. Electric heating, however, requires an increased degree
of insulation. It is felt that this situation will, in the near future,
increase the demand for mineral wool and will make the production of modified
ash based mineral wool even more promising.
-------
-58-
Mlneral Wool
4-1 Lawrence, W. F., jt _al, "Production of Mineral Wool from Coal Ash
Slag," Final Report, Grant No. SWD-9, U. S. Bureau of Mines,
Solid Waste Disposal Program, September, 1969.
4-2 Johnson, R. C., "Development of a Process for Making Mineral
Wool and Producer Gas from Carbonaceous Shales and Fuel Ashes,"
Chemical Engineering Thesis, University of Pittsburgh, Pittsburgh,
Pennsylvania, 1940.
4-3 Lamar, J. E., Fryling, C. F., Voskuil, W. H., and William, H. B.,
"Rock Wool from Illinois Mineral Resources," Bulletin 61. Illinois
State Geological Survey, Urbana, Illinois, 1934.
4-4 Crawford, T. S., £t_ al, "A Slagging Gas Producer for the Production
of Mineral Wool from Rhode Island Meta-Anthracite," Bulletin No. 3,
University of Rhode Island Engineering Experimentation Station, 1953.
4-5 Thoenen, J. R., "Mineral Wool," U. S. Bureau of Mines Information
Circular 6142. 1929.
4-6 Wood, F. C., "Rock Wool Possibilities in Oklahoma," Bulletin 60.
Oklahoma Geological Survey, 1939.
-------
-59-
5. SOIL AMENDMENT
The Coal Research Bureau of West Virginia University and the Virginia
Polytechnic Institute and State University, Department of Agronomy, entered
into a cooperative study to determine the soil amendment and stabilization
properties of modified flyash. The scope of this study included the following
objectives:
(1) a direct comparison of modified flyash and calcium carbonate
(€3003) as amendments for Increasing soil pH;
(2) a determination of the relationship between the chemical
properties of different modified flyashes and increases in
soil pH; and
(3) a determination of the effect of modified flyash upon the
availability of boron, molybdenum, potassium, phosphorus
and zinc in plants which were potted in certain nutrient
deficient soils.
The research was divided into two phases—chemical laboratory
determinations to study objectives one and two, and greenhouse studies
for objective three. Six different flyash samples were studied in phase one
for chemical characteristics and neutralizing power. They were:
1. Presque Isle (PID) limestone injected, dry-collected;
2. Drummond Island (DW) dolomite injected, wet-collected;
3. Chevrolet Motor Division Plant (CM) dolomite premixed, dry-collected;
(CI) dolomite injected, dry-collected;
(CU) unmodified, dry-collected; and
4. Kansas Power and Light Company (KPL) limestone injected, wet-collected.
The greenhouse experiments (phase two) dealt specifically with sample KPL.
This ash was selected because:
1. It was the only ash readily available in sufficiently large quantities;
2. A limestone modified ash would be less susceptible to leaching of
potential water pollutants than a dolomitic ash; and
-------
-60-
3. This ash was produced in a commercial on-streara process.
From information based on the VPI study, it was concluded that the
application of modified ash did increase the pH of acidic soils. However,
modified flyash was only half as effective by weight as calcium carbonate in
its neutralizing capacity. Also, when added to the soil in proper amounts,
modified flyash additions increased the boron supplying power of some boron
deficient soils. Further research is being continued to study the causes of
neutralization efficiency. A copy of the study report can be found in
Appendix I.
Another property of modified flyash is its soil stabilization character-
istics. Prior research^5'1' 5~2^ has indicated that modified flyash is
texturally a silt loam or silt material and that its application would convert
both sandy and clay-like soils into loam soils.
Considering the projected availability and low cost of modified ash,
its neutralizing powers and soil stabilization properties may find use in the
reclamation of strip mines, spoil banks, and other areas which are highly
acidic and texturally unable to support plant growth. Its soil amendment
characteristics may be utilized agriculturally to regulate soil pH and the
boron supplying power of certain soils. In addition, dewatering of the wet-
collected modified ash may not be required for direct application of the
ash to problem areas. Also, these applications would constitute alarge
tonnage utilization of modified flyash.
-------
-61-
Soil Amendment
5-1 Wright, James D., Jr., "The Physical Properties of Flyash and Flyash-
Soil Mixtures," Preliminary Report, USBM Grant No. G0101677, September,
JL y / X •
5-2 Personal Communication, John Capp, U. S. Bureau of Mines, Morgantown
West Virginia, summer, 1970.
-------
-62-
6. NUCLEATED CERAMIC MATERIALS
In conjunction with heating modified ash to evolve sorhed sulfur dioxide,
other high-temperature process applications were examined to utilize the
remaining "de-sulfurized" ash. The two major areas of investigation were
the production of mineral wool (Section 4) and trie production of nucleated
castable ceramic products. Results have shown that modified flyasli can be
considered a potential raw material for the production of nucleated or glass-
formed ceramics. Ceramic samples produced to date, however, do not display uni-
form crystal growth and show signs of zoning. These problems could be solved by
the addition of specific nucleating agents or by using higher melting temperatures.
To produce glass-formed ceramics from modified ash, the raw material was heated
until it attained a pouring consistency. The melt was poured into pre-heated
graphite molds to prevent thermal shock and subsequent cracking and was then
allowed to cool to its temperature of nucleation. This is the temperature at
which the nucleating agent (for example, titanium oxide) provides sites or nuclei
for crystallization. For modified ash the nucleation temperature is believed to
lie in the vicinity of 1500°F. After the desired nucleation period, the temperature
of the sample is raised so that crystal growth may occur. When crystallization
is completed, the temperature of the sample is reduced slowly to avoid thermal
shock until it reaches room temperature.
Since nucleated ceramics can be used in such a wide range of diverse items—
from drain pipes to dishes—the production of glass-formed ceramics from modified
ash could provide a potential large-scale flyash utilization. However, the
large quantity of heat energy required in the production of castable ceramics
from modified flyash indicates that the process is economically unfeasible at
this time.
-------
-63-
Nucleated Ceramic Materials
6-1 Emrich, Barry R., Technology of New Devitrified Ceramics—A Literature
Review. Technical Documentary Report No. ML-TDR-64-203, AF Materials
Laboratory, Air Force Systems Command, Wright-Patterson Air Force
Base, Ohio, September, 1964.
-------
-64-
7. FLOTATION
Flotation is a physicochemical technique used to separate physically
distinct mineral entities of small particle size. This technique involves
the addition of a chemical reagent (collector) to a water and mineral
slurry to render a specific mineral surface hydrophobic or water repellent.
While the slurry is mechanically agitated, air is induced into the system so
that the hydrophobic mineral system collides with and attaches to the
air bubbles. This mechanical action, along with the addition of frothing
agents, which produce a more stable froth, physically lifts and supports the
hydrophobic material which then floats atop the remaining slurry. The
concentrate can then be removed by displacement (such as skimming the slurry
surface) or mechanical action.
Flotation studies were undertaken as a continuation of the flotation
tests performed under Contract PH 22-68-18 to separate either the calcium
oxide or sulfur rich portions of flyash from the remaining slurry. As was
the case in the previous contract, attempts at froth flotation of specific
elements proved relatively unsuccessful. Solutions of soda ash (specifically
sodium carbonate (Na2CO.j)) and soap solutions (eg, sodium oleate) were added
to heated and cooled flyash mixtures to no avail. No other sufficiently
selective reagent was found. The lack of flotability of lime or sulfur
particles may be due to the physical character of modified flyash. According
to a report by Battelle Memorial Institute for the Environmental Health Service,
it is believed that the lime binds with the ash by forming a calcareous shell
around it. The sulfur dioxide is then sorbed on and into this shell in
such a manner that the three basic constituents are bound together to form
discrete particles. The flyash, sulfur and lime constituents, therefore,
are not physically distinct (a fact which was also determined by microscopic
analysis). For these reasons the separation of limestone modified flyash
-------
-65-
into its components by flotation as a means of achieving improved or
partial utilization does not appear feasible.
-------
-66-
Flotation
7-1 Coutant, R. W., Barrett, R. £., Simon, R., and Lougher, E. H.,
"Investigation of the Kinetics of Reaction of a Limestone with
S02 In Flue Gas," Battelle Memorial Institute—Columbus Laboratories,
Paper presented at the Dry Limestone Injection Process Symposium.
Gilbertsville, Kentucky, June, 1970.
7-2 Apian, F. F., and Fuerstenau, D. W., "Principles of Non-Metallic
Mineral Flotation." Froth Flotation. D. W. Fuerstenau (ed.), AIME,
New York, 1960, p 211.
7-3 Glembotskii, V. A., Klassen, V. I., and Plaksin, I. N., Flotation.
Primary Sources, New York, 1963.
7-4 Plaksin, I. N., Flotation Properties of Rare Metal Minerals.
Primary Sources, New York, 1967.
-------
-67-
SUMMARY
Several promising areas for whole utilization of limestone/dolomite
modified flyash liave been examined. These areas include:
1. Production of autoclaved structural products;
a) calcium silicate brick - Brick made using mix proportions
of 50% modified flyash, 39% silica sand and 11% lime dis-
played coinpressive breaking strengths in excess of 7000
psi and exceed ASTM standards for grade SW (severe
weathering) brick;
b) aerated concrete - Lightweight material having the workability
of wood and the thermal properties of concrete were produced
from mixtures of 90% modified flyash, 10% portland cement
and 0.15% aluminum powder; and
c) poured concrete - Autoclaved concrete material having the
same compressive strength but only sixty percent of the
bulk density of conventional concrete was produced from
mixes of 50% modified flyash, 39% silica sand and 11%
lime.
2. Controlled production of sulfur dioxide;
When heated in an oxidizing atmosphere, relatively large amounts
of sulfur dioxide evolve from modified ash. Potential uses are
feed stock for the production of sulfuric acid or for the bottling
of pure sulfur dioxide.
3. Production of mineral wool insulation;
Mineral wool fibers produced from modified flyash displayed
excellent resiliency, fire resistant and rust retarding
properties, and
4. Use of modified ash as a soil amendnient;
Application of modified flyash has neutralized acidic aoils ami
lias increased the boron supplying pov/er of souc boron deficient
soils.
-------
APPENDIX I
-------
1971
ANNUAL REPORT
ON
MODIFIED FLY ASH INVESTIGATIONS
CONDUCTED BY
THE AGRONOMY DEPARTMENT
RESEARCH DIVISION
VIRGINIA POLYTECHNIC INSTITUTE
AND STATE UNIVERSITY
.IN COOPERATION WITH THE
UNITED STATES DEPARTMENT OF INTERIOR
BUREAU OFMINES
PREPARED BY
DAVID C , MARTENS
ASSOCIATE PROFESSOR OF AGRONOMY
-------
TABLE OF CONTENTS
Page
INTRODUCTION 1
THE NEUTRALIZING POWER OF MODIFIED FLY ASH 1
Methods and Materials 2
Equilibration study 2
Laboratory determinations 2
Results and Discussion 3
THE AVAILABILITY OF BORON, POTASSIUM, MOLYBDENUM, PHOSPHORUS,
AND ZINC IN MODIFIED FLY ASH 6
Methods and Materials 6
Boron greenhouse experiment 6
Potassium greenhouse experiment 7
Molybdenum greenhouse experiment 7
Phosphorus greenhouse experiment 8
Zinc greenhouse study 8
Laboratory analyses 9
Results and Discussion 10
Boron greenhouse study 10
Potassium greenhouse study 10
Molybdenum greenhouse study 11
Phosphorus greenhouse study 11
Zinc greenhouse study 11
SUMMARY 12
LITERATURE CITED 13
-------
ii
LIST OF TABLES
Page
Table 1. Samples of fly ash under study 14
»
Table 2. The pH of three soils as related to levels of
calcium carbonate (CaCO_) application 15
Table 3. The pH of three soils as related to levels of
modified fly ash application 16
Table 4. Neutralizing power of modified fly ash determined
by titration procedures 17
Table 5. The concentrations of aluminum (Al), calcium (Ca),
iron (Fe), and magnesium (Mg) in modified fly ash . . 18
Table 6. The concentrations of boron (B), potassium (K),
phosphorus (P), and zinc (Zn) in modified fly ash . . 19
Table 7. Yield of alfalfa as related to application of boron
as Na2B 07'10H20 and as modified fly ash 20
Table 8. The boron concentration of alfalfa tissue as related
to application of boron as Na.B 0 '10H,0 and as modi-
fied fly ash . .... V . 7 21
Table 9. Yield of alfalfa as related to application of
potassium (K) as potassium chloride (KC1) and as
modified fly ash 22
Table 10. The potassium concentration of alfalfa tissue as
related to application of potassium as potassium
chloride and as modified fly ash 23
Table 11. Yield of soybeans as related to application of
molybdenum (Mo) as Na MoO,^H^O and as modified
fly ash ...... 7 24
Table 12. Yield of corn as related to application of
phosphorus (P) as CaCH^PO,) -H 0 and as modified
fly ash ..... 4.2 ,2 25
Table 13. The phosphorus concentration of corn tissue as
related to application of phosphorus as Ca(H PO.^'H-O
and as modified fly ash . . . . . . ? . . . 26
-------
ill
Page
Table 14. Yield of corn as related to application of
zinc (Zn) as ZnSO 'T^O and as modified fly ash . . 27
Table 15. The zinc concentration of corn tissue as related
to application of zinc as ZnSO,'7H00 and as modified
fly ash .../.... 28
-------
AVAILABILITY OF SELECTED NUTRIENTS IN
MODIFIED FLY ASH AND NEUTRALIZING
POWER OF THE BY-PRODUCT
INTRODUCTION
»
Attempts to control SO in flue gases have resulted in large-scale testing
of the limestone injection process. The availability of high lime fly ash
from these sources and the probability that the amount of this material will
Increase make its use in agriculture attractive. Therefore, research was
undertaken to evaluate agronomic properties of fly ash. The objectives of
the research were:
1) To compare modified fly ash with calcium carbonate (CaCO-j) as
amendments for increasing soil pH.
2) To relate chemical properties of modified fly ash to
increases in soil pH due to application of the by-
product.
3) To determine the plant availability of boron (B),
potassium (K), molybdenum (Mo), phosphorous (P) ,
and zinc (Zn) in modified fly ash.
THE NEUTRALIZING POWER OF MODIFIED FLY ASH
Research has shown that acidic soils must be neutralized in order
to attain high yields of certain crops. Calcitic and doloraitic lime-
stones have been applied most frequently to increase the pH of acidic
soils. Industrial by-products, such as paper mill sludge, have been used
as liming materials in localized areas. The research reported herein was
initiated to obtain a preliminary evaluation of the suitability of modified
fly ash as a liming material.
-------
2
Methods and Materials
Three acidic soils varying widely in buffer capacity were selected
for a laboratory equilibration study. The soils selected for the study
were Davidson clay loam, Marlboro fine sandy loam, and Tatum silt loam.
The soils were passed through a 10 mesh screen in preparation for the
equilibration study.
»
Equilibration study. Increments of calcium carbonate (CaCO ) ranging
from 0 to 210 milligrams (mg) and two levels of six modified fly ash samples
(Table 1) were mixed in duplicate with 30 gram (g) portions of the sieved
soils. The mixtures were placed in plastic bags and were watered to approxi-
mately field moisture capacity. The bags then were partially sealed with
a rubber band to avoid excessive water loss. The watering procedure was
repeated 28 and 60 days after the initial wetting of the mixtures. The
mixtures were dried in preparation for pH determinations after an equilibration
period of 85 days.
Laboratory determinations. The pH of soil: fly ash mixtures was
determined with a Beckman Zeromatic pH meter using a 1:2 soil-to-0.01 molar
(M) calcium chloride (CaCIO ratio and a 1 hour equilibration period. The
procedure is described in detail by Peech . For determination of neutralizing
capacity, 2 gram subsamples of modified fly ash were equilibrated with
50 milliliters (ml) of distilled water for 11 hours, heated for one hour on
a steam plate, and titrated to pH 6.5 with 0.01 normal (Np hydrochloric acid (HC1).
The titration and heating procedures were repeated four times. The neutralizing
capacity is reported as the total amount of hydronium ions (H_0 ) consumed
during the four titrations.
The modified fly ash samples were prepared for aluminum (Al), calcium
(Ca), iron (Fe), and magnesium (Mg) determinations by a sodium carbonate
n
(Na2CO ) fusion procedure . One gram samples were fused in platinum crucibles
-------
3
with 6 grams sodium carbonate. The fusion product was taken up in 35 ml of 6
1J HC1 and dried. The acidifying and drying steps were repeated to assure
dehydration of silica. The dried sample was transferred to polyethylene tubes
with 0.5 1? HC1 and the mixture was centrifuged. The acidification with 0.5
N^ HC1 and centrlfugation vrere repeated. The concentrations of Ca, Fe, and
Mg in 100 ml of the supernatant were determined by atomic absorption
spectrophotometry. t
The total amount of aluminum and iron in 5 ml of the supernatant was
determined as outlined in an unpublished procedure by Rich and Singh . A 5 ml
aliquot of the sample in 0.5 £ HC1 was transferred to a 125 ml Erlenmeyer flask.
Five milliliters of 0.5 N NaOH, 10 ml of 0.05 M sodium EDTA, 25 ml of an
ammonium acetate-acetic acid buffer solution (pH A.8), and 25 ml of deionized
water were added to the flask. The flask was shaken, was heated to a boil,
and was cooled to room temperature. Ten drops of a sulphosalicylic solution
were added to the mixture and the sample was titrated to a light brown endpoint
with 0.025 M ferric chloride (Fed ) to determine the excess EDTA. The
aluminum content of the sample was obtained by subtraction of the iron content,
determined by atomic absorption spectrophotometry from the total aluminum and
iron content determined as described above.
Results and Discussion
Application of calcium carbonate (CaCO ) increased the pH of the three
acidic soils as expected (Table 2). Generally, the pH of the soils varied
proportionally to the level of CaC03 application. The pH of the soils was
also increased by application of modified fly ash (Table 3). In all cases,
the 1800 mg level of modified fly ash caused a higher soil pH than the 300 rag
level.
'A soil pH of 6.8 was obtained in the Davidson clay loam by application
of 150 mg of CaCO (Table 2) or by application of 300 mg of modified fly ash
-------
A
samples PID and CM (Table 3). These data show that the two modified fly ash
samples were approximately one-half as efficient as CaCO., in increasing the
pll of the Davidson soil. The other samples of modified fly ash were less
effective in increasing the pH of the soil. The neutralizing power of the
4
modified fly 'ash samples was higher than that reported for unmodified fly ash
or than that obtained for the unmodified fly ash sample CU used in this study
(Table 3).
The results of the equilibration study show that samples PID, CI, and
CM have a higher neutralizing power than samples DW, CU, and KPL (Table 3).
A similar trend was shown by neutralizing powers determined by the titration
procedure (Table 4). It can be concluded from these results that the titration
procedure could be used to depict modified fly ash samples which differ widely
in neutralizing power. The overall lack of agreement between the two procedures
shows that the titration procedure would be unsuitable for estimating the
neutralizing power of samples where high accuracy is required.
Modified samples containing the highest amounts of total calcium (Ca) and
magnesium (Mg) have the highest neutralizing power (Tables 3 and 5). This
relationship implies that samples containing the highest amount of free calcite.
or dolomite have the highest neutralizing power. Verification of this im-
plication requires further knowledge regarding the mineralogical composition
of the modified fly ash samples.
It was reasoned that the variables, neutralizing power determined by
the titration procedure and the contents of aluminum , calcium, iron, and
magnesium might give a good predicition of the neutralizing power of modified
fly ash. The results of the elemental composition analyses indicate that the
samples are very high in total calcium and magnesium compared to aluminum and
iron (Table 5). It seems likely that the neutralizing power of the calcium
and magnesium compounds will mask the neutralizing power of the aluminum
-------
5
and Iron. The relationship will be subjected to multiple correlation and
regression analyses for more detailed study.
-------
THE AVAILABILITY OF BORON, POTASSIUM,
MOLYBDENUM, PHOSPHORUS, AND ZINC
IN MODIFIED FLY ASH
Research has shown that application of selected samples of fly ash
to soil has beneficial effects on plant growth. Certain samples of fly
ash have been shown to correct boron and zinc deficiencies and to partially
correct potassium (K), molybdenum (Mo), and phosphorus (P) deficiencies ' ' .
The research reported below was designed to determine the effect of modified
fly ash application to soil on the plant availability of these elements.
Methods and Materials
Five soils were obtained for these experiments from locations near
Blacksburg, Charlotte Courthouse, Orange, and Tazewell, Virginia. In
preparation for the greenhouse research, the soils were passed through a
stainless steel screen with one centimeter openings, mixed, and stored in
plastic bags. Use of this procedure avoided excessive drying of the soils,
which may affect nutrient availability.
Boron greenhouse experiment. Five treatments applied to a Tatum silt
loam were a check and two levels of boron as Na^O^K^O and as modified
flyash. The amendments for the treatments and reagent grade compounds
containing 52.5 mg N, 231 mg P, 210 ing K, 105 mg Mg, 138 mg S, 0.42 rag Mo,
18.9 mg Zn, 15.8 mg Mn, and 4.2 mg Cu were mixed with portions of the moist
Tatum soil equivalent to 2100 grams of dry soil. The amended soils were
placed in plastic lined pots and the pots were arranged in a completely
random design with three replications.
Thirty 'Williamsburg' alfalfa seeds were planted In each pot and when
seedlings were approximately three centimeters tall; they were thinned to
15 plants per pot. The pots were watered daily to approximately field
moisture capacity throughout the experiment. Supplemental potassium, magnesium,
-------
7
and sulfur were added to the pots at levels of 105, 52.5, and 69 milligrams,
respectively, during the growth period. The top growth of alfalfa was
harvested after an overall growth period of 74 days.
Potassium greenhouse experiment. Six treatments applied in triplicate to
a Groseclose silt loam were a check, one level of potassium chloride (KC1),
one level of CaCO., one level of both potassium chloride and CaC03, and two
levels of modified fly ash. The amendments for the treatments and reagent
grade compounds containing 52.5 mg N, 231 ing P, 105 mg Mg, 138 mg S,
0.42 mg Mo, 18.9 mg Zn, 15.8 mg Mn, 3.2 mg B and 4.2 mg Cu were mixed with
portions of the moist Groseclose silt loam equivalent to 2100 grams of dry
soil. The amended soils were placed in plastic lined pots and the pots were
arranged in a completely random design.
Thirty 'Williamsburg' alfalfa seeds were planted in each pot and when
seedlings were approximately three centimeters tall, they were thinned to
15 plants per pot. The pots were watered daily to approximately field moisture
capacity throughout the experiment. Supplemental magnesium and sulfur were
added to each pot at levels of 52.5 and 69 mg during the growth period.
Alfalfa top growth was harvested after an overall growth period of 74 days.
Molybdenum greenhouse experiment. Six treatments applied in triplicate
to a Cecil fine sandy loam were a check, two levels of Na.MoO,'2EjO, one
level of CaCO,, one level of both Na2MoO^*2H_0 and CaCO-j, and one level of
modified flyash. The amendments for the treatments and reagent grade
compounds containing 52.5 mg N, 231 mg P, 210 mg K, 105 mg Mg, 138 mg S,
18.9 mg Zn, 15.8 mg Mn, 3^2 mg B, and 4.2 mg Cu were mixed with portions
of the moist Cecil soil equivalent to 2100 grams of dry soils. The amended
soils were placed in plastic lined pots and the pots were arranged in a
random design.
E_ght soybean seeds, variety V66-318, were planted in each pot and,
-------
8
when seedlings were approximately 5 centimeters tall, they were thinned
to five plants per pot. The pots were watered daily to approximately
field moisture capacity throughout the experiment. Supplemental potassium,
magnesium, and sulfur were added to all pots at levels of 105, 52.5, and
69 mg, respectively, during the growth period. The top growth of soybeans
was harvested after an overall growth period of 45 days.
Phosphorus greenhouse experiment. Six treatments applied in triplicate
to a Groseclose silt loam were a check, one level of CaC^PO,) "l^O, one
level of CaC03, one level of both Ca(H PO.) 'H20 and CaC03, and two levels
of modified fly ash. The amendments for the treatments and reagent grade
chemicals containing 105 mg N, 105 mg K, 105 mg Mg, 138 mg S, 3.2 mg B,
18.9 mg Zn, 15.8 mg Mn, and A.2 mg Cu were mixed with portions of the moist
Groseclose soil equivalent to 2100 grams of dry soil. The amended soils
were placed in plastic lined pots and the pots were arranged in a completely
random design.
Eight 'Pioneer 3369A1 corn seeds were planted in each pot and when
seedlings were approximately A centimeters tall, they were thinned to A
plants per pot. Supplemental nitrogen, potassium, magnesium, and sulfur
were applied to all pots at rates of 315, 105, 105, and 138 mg, respectively,
during the growth period. The top growth of corn was harvested after an
overall growth period of A3 days. Each pot was watered daily throughout
the growth period.
Zinc greenhouse study. Six treatments applied in triplicate to a
Westmoreland silty clay loam were a check, one level of ZnSO^'7H20, one
level of elemental sulfur, one level of CaCO.,, one level of modified fly
ash, and one level of both ZnSO^'7H_0 and CaCO_. Amendments for the
treatments and reagent grade compounds containing 105 mg N, 105 mg K,
116 mg P, 105 mg Mg, 138 mg S, 3.2 mg B, 15.8 mg Mn, and A.2 mg Cu were
-------
9
mixed with portions of the Westmoreland soil equivalent to 2100 grams dry
soil. The amended soils were placed in plastic lined pots and the pots
were arranged in a completely random design.
Eight 'Pioneer 3369A1 corn seeds were planted in each pot and when
seedlings were approximately 4 centimeters tall, they were thinned to 4
t
plants per pot. Supplemental nitrogen, potassium, magnesium, and sulfur
were applied to all pots at rates of 315, 105, 105, and 138 mg, respectively,
during the growth period. The top growth of corn was harvested after an
overall growth period of 43 days. Each pot was watered daily throughout
the growth period.
Laboratory analyses. Plant tissue from the various greenhouse ex-
periments was dried at 70°C for 48 hours and ground to pass a 20 mesh
screen. Boron in the dried sample was determined by a modification of
the curcumin procedure 8. A one gram subsample of the ground tissue was
•
ashed at 450°C for 2.5 hours and the ash was dissolved in 100 ml of 0.3 N
nitric acid (HNO ). Potassium in the acidic sample was determined by
atomic absorption spectrophotometry and phosphorus by a molybdivanadophos-
phoric acid procedure . Zinc in the ground sample was determined by the
procedure outlined by Schnappinger et al.
The modified fly ash samples were prepared for boron, potassium,
phosphorous and zinc analyses by a modification of the Kanehiro and
Sherman procedure2 as outlined in a previous section of this report. The
boron in the 0.5 N hydrochloric acid leachate of the fusion mass was
determined by a carmine procedure . Potassium and zinc in the acidic
solution were determined by atomic absorption spectrophotometry and by a
12
molybdenum blue colorimetric method
-------
10
Results and Discussion
The sample used to study the availability of boron (B), potassium (K)
phosphorus (P), molybdenum (Mo), and zinc (Zn) in modified fly ash was
obtained from the Kansas Power and Light Company, Lawrence, Kansas (Table 1).
*
This sample was chosen because it was indicated that the limestone injection
process was very successful at the plant and, consequently, it is expected
that modified fly ash would become available at the plant. As compared to
other samples, the modified fly ash from the Kansas Power and Light Company
was low in boron and potassium and intermediate in phosphorus and zinc (Table 6)
Boron greenhouse study. Application of boron as modified fly ash and
as Na B 0 'lOHjO increased the yield of alfalfa on a soil that supplied
inadequate amounts of the element (Table 7). The boron concentration was
not as high where the modified fly ash was applied as where Na B.CU'IOH-O
was applied (Table 8). This was expected for less boron was applied to the
soil as modified fly ash than as Na2B,0_'lOHpO. The lower level of boron
application as modified fly ash was felt desirable to avoid confounding
effects on boron availability of high levels of pH due to application of
high amounts of the by-product.
Potassium greenhouse study. Alfalfa yield was not increased by
application of potassium as either potassium chloride (KC1) or modified
fly ash to the Groseclose soil (Table 9). It is felt that the soil must
be cropped for several cuttings before the deficiency will occur. The
experiment will, therefore, be continued for several cuttings starting the
fall of 1971 when conditions in the greenhouse are suitable for growing
alfalfa. Application of calcium carbonate (CaCO-j) has been shown to
T *\ 1 /
decrease potassium availability in some soils '. This relationship was
-------
11
not shown for the Groseclose soil by either yield of alfalfa or con-
centration of potassium in alfalfa tissue (Tables 9 and 10).
Molybdenum greenhouse study. Application of 42.7 grams modified fly
ash increased the pH of the Cecil fine sandy loam from 5.0 to 7.5, whereas
2.1 grams of calcium carbonate increased the pH of the soil to 6.3. Neither
*
molybdenum nor calcium carbonate application increased yield of soybeans
on the acid soil (Table 11). Application of the modified fly ash decreased
soybean yield. The decrease in yield probably resulted from boron toxicity
or soluble salt damage as soybeans are very sensitive to both abnormalities15.
Phosphorus greenhouse study. Application of Ca(H PO.^'H-O to the
Groseclose silt loam increased yield of corn grovm in the greenhouse
(Table 12). These data indicate that the soil supplied inadequate phosphorus
for corn growth. Corn yield was not increased by application of 126.3 or
252.6 grams of modified fly ash. These data show that modified fly ash
did not increase the phosphorus supplying power of the soil. The phosphorus
concentration data show that the amount of phosphorus absorbed by corn plants
was not greatly altered by application of modified fly ash (Table 13).
Zinc greenhouse study. Application of ZnSO,'7H20 increased corn grown
on Westmorland silty clay loam (Table 14). These data show that the soil
supplied an inadequate amount of zinc for corn growth. Application of
elemental sulfur decreased the pH of the soil from 6.1 to 5.7. This decrease
in pH probably increased the availability of residual zinc in the soil and
thereby corrected zinc deficiency. Application of calcuim carbonate in-
creased the pH of the soil from 6.1 to 6.3. This increase in pH probably
decreased the availability of residual zinc in the soil and thereby resulted
in the decrease in corn yield (Table 14). Application of modified fly ash
did not affect corn yield. The pH of the soil was increased from 6.1 to
-------
12
7.6 by application of modified fly ash. Neither the residual soil zinc
nor the zinc in modified fly ash would be expected to have high availability
at a soil pH of 7.6. The zinc concentration data (Table 15) closely parallel
yield data (Table 14).
SUMMARY
The results of this research show two possible'beneficial effects
from application of modified fly ash to agricultural soils. That is,
application of modified fly ash increases the boron supplying power and
pH of soils. Increasing the pH of acidic soils increases yield of certain
crops.
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13
LITERATURE CITED
1. Peech, M. 1965. Hydrogen-ion activity. Agronomy 9(2):914-926.
2. Kanehiro, Yoshinori, and G. Donald Sherman. 1965. Fusion with sodium
carbonate for total elemental analysis. Agronomy 9(2):952-958.
3. Rich, C. I., and R. N. Singh. 1963. Determination of iron and
aluminum in soils, clays, and plant materials using EDTA. Unpublished
procedure. Department of Agronomy, Virginia Polytechnic Institute and
State University.
4. Martens, D. C. 1970. Chemical and physical reactions of soils with
fly ash of importance to its agricultural utilization. Annual Report
prepared for the United States Department of Interior, Bureau of Mines.
Project No. G0180091 (SWD-14).
5. Martens, D. C., M. G. Schnappinger, Jr., and L. W. Zelazny. 1970.
The plant availability of potassium in fly ash. Soil Sci. Soc. Amer.
Proc. 34:453-456.
6. Martens, D. C., M. G. Schnappinger, Jr., J. W. Doran, and F. R.
Mulford. 1970. Fly ash as a fertilizer. Bureau of Mines Information
Circular 8488. p. 310-326.
7. Mulford, F. R., and D. C. Martens. 1971. Response of alfalfa to boron
in fly ash. Soil Sci. Soc. Amer. Proc. 35:296-300.
8. Mulford, F. R., and D. C. Martens. 1970. A simple procedure for dry-
ing solutions for boron determinations by the curcumin method. Soil
Sci. Soc. Amer. Proc. 34:155-156.
9. Kitson, K. E., and M. G. Mellon. 1944. Colorimetric determination
of phosphorus as molybdivanadophosphoric acid. Ind. and Eng. Chem.
(Anal. Ed.) 16:379-383.
10. Schnappinger, M. G., Jr., D. C. Martens, and G. W. Hawkins. 1969.
Response of corn to Zn-EDTA and ZnSO, in field investigations.
Agron. J. 61:834-836.
11. Hatcher, J. T., and L. V. Wilcox. 1950. Colorimetric determination
of boron using carmine. Anal. Chem. 22:467-569.
12. Olsen, S. R., and L. A. Dean. 1965. Phosphorus. Agronomy 9(2):
1035-1049.
13. Rich, C. I., and W. R. Black. 1964. Potassium exchange as affected
by cation size, pH, and mineral structure. Soil Sci. 97:384-390.
14. Rich, C. I. 1964. The effect of cation size and pH on potassium
exchange in Nason soil. Soil Sci. 98:100-106.
15. United States Salinity Laboratory Staff. 1954. Diagnosis and
improvement of saline and alkali soils. Edited by L. A. Richards.
United States Department of Agriculture Handbook No. 60.
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14
Table 1. Samples of fly ash under study.
Sample
No. Source
1 Drummond Island, dolomite modified,
wet-collected fly ash (D.W.)
2 Presque Isle, limestone modified,
dry-collected fly ash (P.I.D.)
3 Chevrolet Motor Division Plant, St.
Louis, Missouri; dolomite injected,
dry-collected fly ash (C.I.)
4 Chevrolet Motor Division Plant, St.
Louis, Missouri; unmodified fly ash
(C.U.)
5 Kansas Power and Light Company,
Lawrence, Kansas; limestone injected,
wet-collected fly ash (K.P.L.)
6 Chevrolet Motor Division Plant, St.
Louis, Missouri; dolomite premixed,
dry-collected fly ash (C.M.)
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15
Table 2. The pH of three soils as related to levels of calcium carbonate
(CaCO-j) application.
Treatment
rag CaC03/30g soil
0
30
60
90
120
150
180
210
Davidson
clay loam
5.0
5.4
6.0
6.3
6.5
6.8
6.8
7.0
Soil type
Marlboro fine
sandy loam
4.9
5.8
6.4
6.9
7.1
7.4
7.5
7.6
Tatum
silt loam
4.4
4.8
5.1
5.4
5.9
6.3
7.2
7.4
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16
Table 3, The pH of three soils as related to levels of
modified fly ash application.
Treatment
Modified Level of
fly ash application
mg/3Qg soil
DW 300
1800
PID 300
1800
Cl 300
1800
CU 300
1800
KPL 300
1800
CM 300
1800
Soil type
Davidson Marlboro fine
clay loam sandy loam
6.3
7.8
6.8
8.2
7.1
8.0
5.4
6.7
6,0
7.7
6,8
7.8
6.6
8. A
7.6
8.6
8.1
8.9
5.4
7.9
6.4
8.0
7.6
8.6
Tatum
silt loam
4.9
7.8
6.2
8.6
6.7
7.9
4.2
5.8
4.9
7.5
6.0
8.1
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17
Table A. Neutralizing power of modified fly
ash determined by titration pro-
cedures .
Modified
fly ash
DW
PID
CI
CU
KPL
CM
Neutralizing
Power
meq H 0+/g
2.8
8.0
9.2
1.9
1.9
10.4
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19
Table 6. The concentrations of boron (B), potassium (K), phosphorous (P)
and zinc (Zn) in modified fly ash.
Modified
flv ash
DW
PID
CI
CU
KPL
CM
B
ppm
253
673
740
993
48
923
Concentration
K
%
0.57
0.97
0.63
1.02
0.71
0.76
of
P
ppm
875
1550
250
250
625
425
Zn
ppm
81
135
294
480
353
359
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20
Table 7. Yield of alfalfa as related to application
of boron (B) as Na^Oy'lOl^O and as modified
fly ash.
Treatment*Yield**
g/pot
Check 6.Ob
27.9 rag Na2B40?'10H20 7.la
55.8 tag Na2B407'10H20 7.0a
7.6 g modified fly ash 7.la
22.8 g modified fly ash 7.2a
*The modified fly ash was obtained from the Kansas
Power and Light Company, Lawrence, Kansas.
**Means followed by different letters are significantly
different at the 5% level of probability.
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21
Table 8. The boron (B) concentration of alfalfa tissue
as related to application of boron as
10H20 and as modified fly ash.
Treatment* B concentration
ppm
Check 9.7
27.9 me Na2BA07'10H20 151.0
55.8 mg Na2B407'10H20 149.5
7.6 g modified fly ash 31.0
22.8 g modified fly ash 44.0
*The modified fly ash was obtained from the Kansas Power
and Light Company, Lawrence, Kansas.
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22
Table 9. Yield of alfalfa as related to application of
potassium (K) as potassium chloride and as modified
fly ash.
Treatment*
Check
200.5 rag KC1
2.1 g CaC03
200.5 mg KC1, 2.1 g CaC03
3. A g modified fly ash
13.6 g modified fly ash
Yield**
g/pot
7.4
7.6
7.6
7.9
8.4
7.7
*The modified fly ash was obtained from the Kansas
Power and Light Company, Lawrence, Kansas.
**Differences in yield were not significant at the
5% level of probability.
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23
Table 10. The potassium (K) concentration of alfalfa tissue
as related to application of potassium as potassium
chloride and as modified fly ash.
Treatment* K concentration
Check 1.6
200.5 mg KC1 2.6
2.1 g CaC03 1.5
200.5 mg KC1, 2.1 g CaC03 2.3
3.4 g modified fly ash 1.5
13.6 g modified fly ash 1.6
*The modified fly ash was obtained from the Kansas Power
and Light Company, Lawrence, Kansas.
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24
Table 11. Yield of soybeans as related to application of
molybdenum (Mo) as Na2MoO,'2H20 and as modified
fly ash.
Treatment* Yield**
g/pot
Check 12.7a
2.12 mg Na2Mo04'2H20 12.la
4.24 mg Na2Mo04-2H20 12.8a
2.1 g CaC03 13.Oa
2.1 g CaC03, 2.12 mg Na^toO^I^O 12.4a
42.7 g modified fly ash 11.Ob
*The modified fly ash was obtained from the Kansas Power and
Light Company, Lawrence, Kansas.
**Means followed by different letters are significant at the
5% level of probability.
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25
Table 12. Yield of corn as related to application of phosphorus (P)
as Ca(H2POA)2'H20 and as modified flV ash.
Treatment*Yield**
g/pot
Check 8'0b
854 mg Ca(H2P04)2'H20 i8-83
2.1 g CaC03 8'€b
2.1 g CaC03, 854 mg CaO^PO^'H^ 17.9a
126.3 g modified fly ash 9.3b
252.6 g modified fly ash 3.0c
*The modified fly ash was obtained from the Kansas Power and
Light Company, Lawrence, Kansas.
**Means followed by different letters are significantly different
at the 5% level of probability.
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26
Table 13. The phosphorous (P) concentration of corn tissue
as related to application of phosphorous as
Ca(H2P04) 'H20 and as modified fly ash.
Treatment* p concentration ~~
Check 0.14
854 mg Ca(H2P04)2-H20 0.21
2.1 g CaC0 0.16
2.1 g CaC03, 854 mg CaO^PO^'l^O 0.24
126.3 g modified fly ash 0.22
252.6 g modified fly ash 0.21
*The modified fly ash was obtained from the Kansas Power
and Light Company, Lawrence, Kansas.
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27
Table 14. Yield of corn as related to application of zinc (Zn)
as ZnS04«7H20 and as modified fly ash.
Treatment*~~~Yield**
g/pot
Check . 11.2b
83.3 ing ZnS0^7H20 15<9a
1.0 g elemental sulfur 15.5a
2.1 g CaC03 7<5c
2.1 g CaC03, 83.3 mg ZnS04*7H20 15.ba
165.1 g modified fly ash 9.4bc
*The modified fly ash was obtained from the Kansas Power and
Light Company, Lawrence, Kansas.
**Means followed by different yields are significantly different
at the 5% level of probability.
-------
28
Table 15. The zinc (Zn) concentration of corn tissue as related
to application of zinc as ZnSO^l^O and as modified
fly ash.
Treatment*Zn concentration
ppra
Check 14.7
83.3 mg ZnSO^'7H20 19.0
1.0 g elemental S 13.3
2.1 g CaC03 15.3
2.1 g CaC03, 83.3 mg ZnS04*7H20 21.3
165.1 g modified fly ash 20.0
*The modified fly ash was obtained from the Kansas Power and Light
Company, Lawrence, Kansas.
-------
CONTRACT: PILOT SCALE-UP OF PROCESSES TO DEMONSTRATE UTILIZATION OF
PULVERIZED COAL FLYASH MODIFIED BY THE ADDITION OF LIMESTONE-
DOLOMITE SULFUR DIOXIDE REMOVAL ADDITIVES.
CONTRACTOR: COAL RESEARCH BUREAU, WEST VIRGINIA UNIVERSITY
CONTRACT NO. CPA 70-66 Controclor Project Off.: J.W. uebnord
CONTRACT DATES-5/1/7u-8/3u/?i NAPCA Proj.Off: T.A.Kittlemon
Mt - Chorocferizof/on Tests
Afe- Mineral IVoo/Tesfs
Mj - Hear Treated Motor/off fesfs
M* - Soil Amendment Tests
Mf-SO? Rcgeneratio nTj>s>*
U
M« - Sondlima Brick Tests
Mr- Flotation Tests
Ma - Pilot Scale fad.. Demonstration81 Evaluation
Mf-Finol Report
! !
o
60.CX30
50^00-
40POO
30,000
20POO-
10,000
PROGRKS m September 30, 1971
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