EPA-450/3-74-010 May 1973 NATIONAL EMISSIONS INVENTORY OF SOURCES AND EMISSIONS OF MAGNESIUM U.S. ENVIRONMENTAL PROTECTION AGENCY Offire of Air and Waste Management Office of Air Quality Planning and Standardg Research Triangle Park, North Carolina 27711 ------- EPA-450/3-74-010 NATIONAL EMISSIONS INVENTORY OF SOURCES AND EMISSIONS OF MAGNESIUM by GCA Corporation GCA Technology Division Bedford, Massachusetts 01730 Contract No. 68-02-9601 EPA Project Officer: David Anderson Prepared for ENVIRONMENTAL PROTECTION AGENCY Office of Air and Water Programs Office of Air Quality Planning and Standard* Research Triangle Park, N. C. 27711 May 1973 ------- This report is issued by the Environmental Protection Agency to report technical data of interest to a limited number of readers. Copies are available free of charge to Federal employees, current contractors and grantees, and nonprofit organizations - as supplies permit - from the Air Pollution Technical Information Center, Environmental Protection Agency, Research Triangle Park, North Carolina 27711, or from the National Technical Information Service, 5285 Port Royal Road, Springfield, Virginia 22151. This report was furnished to the Environmental Protection Agency by GCA Corp- oration, Bedford, Massachusetts, in fulfillment of Contract No. 68-02-9601. The contents of this report are reproduced herein as received from GCA Corporation. The opinions, findings, and conclusions expressed are those of the author and not necessarily those of the Environmental Protection Agency. Mention of company or product names is not to be considered as an endorsement by the Environmental Protection Agency. Publication No. EPA-450/3-74-010 11 ------- TABLE OF CONTENTS SECTION TITLE PAGE I II III IV V VI VII ABSTRACT ACKNOWLEDGEMENT INTRODUCTION A. PURPOSE AND SCOPE B. CONCLUSIONS OVERALL U.S. MATERIAL FLOW CHART FOR MAGNESIUM A. MINING OF MAGNESITE, BRUCITE AND OLIVINE B. MINING OF DOLOMITE C. RECOVERY OF MAGNESIUM FROM SEAWAIER AND WELL BRINES D. IMPORTS AND EXPORTS E. MAGNESIUM OXIDE F. MAGNESIUM METAL G. REFRACTORY MAGNESIA H. MAGNESIUM CHEMICALS SOURCES AND ESTIMATES OF MAGNESIUM - CONTAINING EMISSIONS A. DATA PRESENTATION AND ACCURACY B. DEVELOPMENT OF EMISSIONS ESTIMATES - 1970 C. SUMMARY OF PRINCIPAL EMISSIONS REGIONAL DISTRIBUTION OF PRINCIPAL SOURCES AND EMISSIONS NATURE OF EMISSIONS UPDATING OF EMISSIONS ESTIMATES A. VERIFICATION OF CURRENT ESTIMATES B. PERIODIC REVIEW OF ESTIMATES REFERENCES V vi 1 1 2 4 4 4 4 6 6 6 7 7 9 9 13 20 21 25 29 29 29 31 111 ------- LIST OP TABLES AND FIGURES TABLE NO. 4a 4b SOURCES AND ESTIMATES OF MAGNES lUM- EMISSIONS SUMMARY OF PRINCIPAL SOURCES AMD EMISSIONS OF MAGNESIUM REGIONAL DISTRIBUTION OF PRJNCIBAL SOURCES AUD EMISSIONS DESCRIPTION OF MAGNESIUM MI81RALS AH) PRODUCTS PROPERTIES OF MAGNESIUM METAL PAGE 10 20 22 26 26 FIGURE NO, MAGNESIUM MATERIAL FLOW - 1970 IV ------- ABSTRACT A national inventory of the sources and emissions of the element negnesium was conducted, , The study included the preparation of an over- all material flow chart depicting the quantities of magnesium moving from sources of mining and importation through all processing and repro- cessing steps to ultimate use and final deposition. All major sources of magnesium-containing emissions were identified and their magnesium emissions into the atmosphere estimated. A regional breakdown of these sources and their emissions was also provided. The physical and chemical nature of the magnesium-containing emissions was delineated to the extent that information was available, and a methodology was recom- mended for updating the results of the study every two years. ------- ACKNOWLEDGMENT The continued cooperation and dedication of Mr. Carl Spangler of EPA, who served as Program Monitor until his death,, is deeply appreciated, GCA would like to extend thanks to Mr. David Anderson and Mr. James Southerland of EPA for their cooperation in the preparation of this study. In addition, special thanks are also due to Mr. E. Chin, Conmodity Specialist, Bureau of Mines; Ms. Marie Harris, Dept. of Commerce; and The National Lime Association, Washington, D.C., who provided significant technical inputs to this program. VI ------- I. INTRODUCTION A. PURPOSE AND SCOPE The Monitoring and Data Analysis Division, Office of Air Quality Planning and Standards of the U.S. Environmental Protection Agency (EPA) has contracted with GCA Technology Division to conduct a national inventory of the sources and emissions of the element magnesium. The purpose of the study was to define as accurately as possible, based on existing and available published and unpublished information, the levels, nature, and sources of magnesium-containing emissions for defined geographic regions throughout the United States. The scope of this program is outlined below. . Develop an overall material flow chart depicting the quantities of magnesium moving from sources of mining and importation, through all processing and reprocessing steps to ultimate use and final disposition as far as the movements can be traced. . Identify all major potential magnesium- containing emission sources and estimate the total quantity of magnesium emitted to the atmosphere from each source. Emission factors and level, and types of air pollution control, are also provided for each of these sources to the extent that available information permits. . Define those sources which contribute at least 80% of the total emission of magnesium. . Provide a regiona1 breakdown of these major sources and their emissions. . Present the nature of the magnesium- containing emissions for each of these major sources, including a delineation of their physical and chemical form and particle size distribution, to the extent that information is available. ------- . Provide recommendations as to a methodology for updating the results of this study every two years. B. CONCLUSIONS 1. Mater ial Based on all available data, 905,000 tons of magnesium was consumed in the U.S. in 1970, in various chemical and pure forms. The sources of magnesium included sea water and other brines, the mining and importation of magnesite, and the mining of dolomite. By far, the largest portion of the magnesium was consumed in the form of fire brick and other refractory materials, especially within the iron and steel industry. Very little magnesium was consumed as metal, and of this, only about 10 percent was recycled as scrap. 2. Principal Emis s ion Sources Due to a large emission of flyash from the combustion of coal, and a small yet significant concentration of magnesium in the flyash, the largest source of magnesium emitted to the atmosphere was found to be the combustion of coal. Almost 57% of all U.S. emissions of magnesium was from this source. Within the magnesium and magnesium compounds industries, the largest source of emissions was estimated to be the production of refractory materials, accounting for 10 percent of the total U.S. emissions. Taken together, mining, processing, and calcining of magnesite and dolomite were estimated to be responsible for about 17% of all U.S. emissions of magnesium. 3. Regiona 1 Emis s ions The region of the U.S. in which most of the estimated magnesium is emitted is Region 5* (Ohio-Minnesota), with about 33 per- cent of the U.S. total. The region in which the total emission per square mile is greatest is Region 3 (Pennsylvania -Virginia). Although the emissions from these areas are strongly weighted by the estimated emission from coal combustion, similar conclusions would be made in the absence of coal combustion emissions. *See page 21 for a list of regions. ------- 4. Mature of Emissions Magnesium is believed to be emitted predominantly in the carbonate and oxide chemical forms, usually not alone but included in most particles along with ash, slag, and other mineral material. A wide size range of particles containing magnesium is generated. However, after particulate control equipment, and/or gravitational settling, the remaining particles containing magnesium are typically on the order of 1 micron diameter. "With regard to the magnesium content of these particles, they probably tend to be both stable and relatively inert. 5. Degree of Control The overall level of control of magnesium emission is estimated to have been about 87 percent in 1970. All of the large sources of emissions were controlled at levels ranging from 82 to 99 percent. Of these large sources, coal combustion, the largest, was also one of the most poorly controlled at an estimated 82 percent. The production of refractory materials was estimated to utilize a control level of only 80 percent. ------- II. OVERALL U.S. MATERIAL FLOW CHART FOR MAGNESJEIM Figure 1* presents a flow diagram depicting the total quantities of magnesium products moving from sources of mining and importation through the processing and reprocessing steps to ultimate use and final deposition. Each of these sources is discussed below. Process descrip- tions are given in Section II. A. MINING OF MAGNESITE., BRUCTTE, AND OLIVINE Magnesite and brucite are presently mined at only the basic open-pit mine in Gabbs, Nevada. Total ore production in 1970 was 631;000 tons. Based on an approximate magnesium content of 35 percent, the magnesium content of the produced ore is estimated at 221,000 tons. Operations at or near the mine, after removal of a large overburden, include blasting, crushing, screening, washing, and drying. divine, another magnesium ore, is presently mined in Washington and North Carolina. No data could be found to estimate its production. Its predominant use is as a molding sand in foundries and it is not in demand specifically for its magnesium content. No other magnesium ores are presently mined, except dolomite. B. MINING OF DOLOMITE Deposits of dolomite are quarried throughout the United States, using processes similar to the above. It is found extensively with limestone and shares many of the same properties. Total reported pro- duction of dead burned dolomite for use as a magnesium compound totaled (2) 1,373,000 tons. Based on a magnesium content of 13 percent, magnesium from dolomite mining totaled 173,000 tons. C. RECOVERY OF MAGNESIUM FROM SEAWATER AND WELL BRINES All magnesium metal in produced by electrolysis of magnesium chloride recovered from seawater. In addition magnesia (MgO) and magnesium * Data in Figure L and in this section are left unrounded, for purposes of information control. On the average, the typical statistic is accurate to within 10 percent, in the opinion of the authors. ------- Magnesium Material Flow-1970 (thousand tons contained Mg) ------- chloride recovered from seawater are used to produce other magnesium compounds. The total reported recovery of magnesium compounds (MgO (3) equivalent) from seawater and brines is 625,618 tons. ' Converting to magnesium content, magnesium compounds from seawater and well brines totaled 378,000 tons of magnesium. In addition, 112,000™' tons of magnesium metal was produced from seawater. Thus, total production of magnesium and magnesium compounds from seawater and well brines was 490,000 tons. D. IMPORTS AMD EXPORTS Imports of magnesite in 1970 totaled 128,193 tons.K ' Con- verting this into total contained magnesium, assuming a 29 percent magnesium content^ * gives an import of 37,000 tons. Total contained magnesium in imported magnesium compounds reached 8,000 tons, predominantly in the form of epsom salts (magnesium sulfate). U.S. exports of magnesium and magnesium-containing materials totaled 98,937 tons^ ' ' or 29,000 tons of contained magnesium. E. MGHESIUM OXIDE Magnesia (magnesium oxide) consumed other than in refractories and in the production of other magnesium compounds is reported at 198, 00( tons (119,000 tons of contained Mg). It is produced predominantly from seawater and well brines by calcining. A primary use is as a stabilizing or vulcanizing agent in rubber. Chemical manufacturers use it in the production of roofiag cement. The distribution of uses appear' ing in the flow chart Is based on a percentage breakdown provided by (2) the U.S. Bureau of Mines. v/ F. MAGNESIUM Magnesium metal is presently produced solely from seawater, although it has been recently, and may possibly in the future be produced from dolomite in a thermic process. By far the major consump- tive use has been in the production of alloys. Its uses are divided between structural and nonstructural. Major notistructural uses ------- include use as a reducing agent and for cathodic protection of other metals, particularly iron and steel, in underground pipes, water tanks, and water heaters. The predominant structural consumers are the aluminum industry, which uses magnesium in the production of alloys; and Volkswagenwerk A.G., which uses magnesium extensively in its engines. The distribution in the flow chart is based on data from the U.S. Bureau of Mines.W Secondary magnesium is obtained from new scrap and old scrap. New scrap consists of borings, skimmings, slags, drosses and defective articles produced in mills and fabricating plants. Old scrap is metal recovered from old aircraft and other obsolete equipment. Secondary magnesium is used in alloying, rather than in pure material. Secondary metal production totaled 12,042 tons in 1970.' ' G. REFRACTORY MAGNESIA Refractory grade magnesia is produced by high temperature calcining from magnesite, seawater, and from dolomite. It is the major consumption of magnesium compounds, equal to 483,000 tons of (2) contained magnesium. The refractory material is used primarily in steel and nonferrous furnaces for the parts exposed to molten metal and slag. Raw dolomite is also used as a flux and for patching open hearth furnaces. Magnesia is also used in conjunction with chromium to produce chrome magnesite or magnesite-chrome brick. H. MAGNESIUM CHEMICALS 1. Magnesium Chloride Magnesium chloride is the primary product from all brines (21 and seawater. According to the Bureau of Mines,v ' 513,029 tons con- taining 131,000 tons of magnesium were shipped and utilized for non- metal producing uses. It should be noted, however, that almost three times that quantity was utilized as a feed material in the manufacture of magnesium metal, refractory materials, and primary magnesium chemicals. 2. Magnesium Hydroxide Magnesium hydroxide is a common intermediate product in the production of several magnesium compounds and in metal production. ------- Its major uses are in sugar refining and pulp and paper, with some use as a pharmaceutical. These three applications consumed 36,000 tons of magnesium. 3. Magnesium Carbonate Magnesium carbonate is used as a thermal insulator for boilers and pipes, and in table salt to prevent caking, as veil as in Pharmaceuticals and cosmetics. The total reported to be shipped or used in 1970 by the U.S. Bureau of Mines was 6,799 tons or 2,000 tons (2) of contained magnesium. 4. Magnesium Sulfate Magnesium sulfate or epsom salt is a major pharmaceutical. It is also used in explosives and matches, in the pulp and paper indus- try, and in dyes. A major portion (34,939 tons) was imported in 1970. ( 2) This contained 4,000 tons of magnesium. ' Magnesium sulfate is also produced from magnesium hydroxide by treatment with tiulfuric acid. A total consumption of 6,000 tons of magnesium sulfate was estimated for the U.S. in 1970. ------- III. SOURCES AHD ESTIMATES OF Mft.GNESIUM-CONIAINING EMISSIONS A. DATA MES1OT4TION AND ACCU1ACX Table 1 presents a summary of the data from which emissions were estimated for all major potential sources. Each of the columns comprising this table will be discussed below. 1. Emission^Factors Except where indicated, this gives the pounds of total particulates emitted per ton of production. Such considerations as: . variations in process conditions among individual plants comprising a source category . inaccuracies in existing data . a limited quantity of existing data may however, result in an average emission factor for a source category varying by more than an order o£ magnitude from the value presented. In recognizing the need to indicate the level of accuracy of these emission factors, a reliability code is presented along with each emission factor value appearing in the table. This reliability code system is described below and is based on the system utilized in EPA Document No. AP-42, "Compilation of Air Pollutant Emission Factors";^ ' A; Excellent This value is based on field measurements of a large number of sources. B; Above average This value is baaed on a limited number of field measurements. C: Average This value is based on limited data and/ or published emission factors where the accuracy is not stated. D: Below average This emission factor is based on engineering estimates made by know- ledgeable personnel ------- TABLE 1 SOURCES AND ESTIMATES OF MAGNESIUM-CONTAINING EMISSIONS Source tanSS, &. Olg^PKOjCgSSIHG Mining, crushing, and drying Of dolomite Mining, crushing, drying, and briquettiog of raagneslte OXIDE FK0DUCTIOH Dolomite - vertical kiln* Dolomite - rotary kiln* Magnesite - rotary kiln* Hydroxide - rotary kilns METAiLUggt Magnesium production Alloying and refining REFRACTORIES Grinding and mixing Electric casting IHAIITE&tESHT SOURCES Iron and Steel Sinter Procea* Blast Furnace Open Btarth Baale OxvgMt Electric Arc Coal Oil Asbestos Cement Uncontrolled Particulate Efciasion Factor (Ib/ton) 465 475 7 180 180 180 0 4 150 75 20 Ib/ton sinter 130 Ib/ton pig iron 17 Ib/ton steel 40 ib/tas •teal 10 Ib/ton steel H/A H/A N/A (kg/kgxlO3) 233.0 238.0 3.5 90.0 90.0 90.0 0 2 75.0 37.5 10.0 65.0 8.5 20.0 5.0 H/A H/A H/A H/A Reliability Code (C) (W (B) (C) (C) (D) (C) (C) (C) (B) W (B) (B) (B) Total* Production level (tona/yr) 2,200,000 631,000 137,300 1,236,000 125,000 625,618 136,500 124,000 483,000 44,000 51,000.000 88,800,000 65,800,000 48,000,000 16,800,000 33,800,000° 287,000C 6,579C 7,790,000° % Mg in Emissions 13 (A) 40 (B) 17 (C) 17 (C) 50 (C) 60 (B) 60 (D) See Note a. See Note a. O.fr-6.0 (C) 0.1 •* 3.6 (C) 0,2 - 0.7 (C> 0.4-0.7 (C) 0.2-9.2 (C) 0.70 (A) 0.15 (C) 19.0 (A) 0.07 - 1.15(C) Mg Emissions Before Control* (tone/yr) 66,500 59,950 82 18,911 5,620 33,700 0 149 36,200 1,650 (3,060 - 30.600) 15.3006 (5,770 - 207,900) 69,300b (1,130 - 3,5)70) 1,700* (3,840 - 6,700) 4,800b (168 - 7,700) 4.200b 236,000 430 1,250 (5,400 - 89.000) 31.1006 Estimated Level of Control 95.0 90.3 39.0 81.0 80.0 95.0 0 90.0 80.0 85.0 90.0 99.0 40.0 99.0 78.0 82.0 0 0 88.0 Mg Eodssionj After Control* (tona/yr) 3,320 5,790 50 3,593 1,130 1,690 0 15 7,250 250 (306 •* 3,060) l,530b (58 - 2,079) 693b (670 - 2,340) l,000b (38 •* 67) b (37- •» 1,700) 42.600 430 1,250 (650 - 10,700) 3.73011 586,842 87-°* 75'2« MOTES: a. Badifion factor multiplier equal to tons of Mg processed or handled annually. b. Intermediate value (see text). c. Particular generated, before control. N/A - Not applicable. ------- 2« Level of Production.Activity This column depicts the quantity of material produced (un- less otherwise stated) annually. When multiplied by the emission factor, an estimate of the total particulate emissions for that source in pounds per year is obtained. The values in this column are based on the material flow calculations presented in Section II, Consequently, they have the same accuracy as those material flow values which are estimated at + 10%. 3. Percentage of Metal in Emissions The method of analyzing or assaying a dust sample for the amount of metal it contains determines to a large extent the reliability of the data. For example, analytical chemistry techniques for dust containing substantial fractions of metal can be accurate to within a small percentage. On the other hand, optical spectroscopy methods for determining concentra- tions or the order of parts per million can be inaccurate by a factor of 2, Because of this variability, the reliability codes discussed above for the emission factors are also utilized to estimate the relative accuracy of the percentage values listed in Column 3. ^* Level of Magnesium Emissions Before Control The values in this column are derived by multiplying the values in Columns 1 through 3. The result is converted to tons/year of emissions before control. 5. EstimatedLevel of Emission Control The overall effectiveness of control for a source category is based on two factors: . the portion of the processes that are under control . the typical degree of control For example, if 60 percent of vertical roasters have some type of particu- late emission control and these include both scrubbers and precipitators 11 ------- such that the apparent weighted average efficiency of control is 85 per- cent, the overall control effectiveness is estimated to be 60 x 85 = 51 percent. The accuracy of control efficiency data varies with the degree of control. For a set scrubber operating at 80 percent efficiency (i,e,, pass 20 percent material) the actual emission may safely be assumed to be between 15 and 25 percent because of the relative ease of making de- terminations at this level. Thus, the emissions after control may be as- sumed to be accurate within + 5/20 or 25 percent. On the other hand, for a baghouse reported as being 99 percent efficient, or passing only 1 percent of the material, the actual emission may vary from 0.5 to perhaps 2 percent because it is frequently difficult to make low-level measure- ments with accuracy. In such cases, the resulting emission data could, be in error by a factor of 2, Unless otherwise specified, it is assumed that the reported overall level of particulate control applies equally to all magnesium- containing particles, independent of size, resistance, and other impor- tant collection parameters. This assumption results in a correct esti- mate of magnesium emissions after control when the particulate is chem- ically homogenious; i.e., the magnesium is contained in the same concen- tration in all particles. If however, magnesium is concentrated in cer- tain particles and in addition, the efficiency of the control equipment is not uniform for all particles, then the utilization of an average con- trol level is less valid for calculating magnesium emissions after control. Data on the preferential control of magnesium-containing particles is seldom available, but is included in this report, when possible. The accuracy of estimating the level of control for a spe- cific source category is dependent on the quality of available data. The investigators feel that, in general, the level of control data will con- tribute an accuracy to the resulting emission estimates within + 25 per- cent. 12 ------- 6. Level of Metal Emissions After Control The values in this column are derived by multiplying the values in Column 4 by the value (100 minus estimated level of control). B. DEVELOPMENT OF EMISSIONS ESTIMATES - 1970 1. Mining of Dolomite Dolomite and limestone are mined and treated much in the same manner, in that dolomite is the double carbonate of calcium and magnesium (CaCO-'MgCO,,). Emissions are generated from open-pit mining; crushing and screening; and washing and drying operations, preparatory to burning. Mining is estimated to generate emissions on the order of 1 Ib/ton and is uncontrolled. Crushing and screening are estimated to generate 24 Ibs/ton, and since most emissions are uncontrolledj the over- all level of control effectiveness is estimated at 20 percent. Drying the washed, crushed rock generates an estimated emission of 440 Ibs/ton (Q\ which is well controlled at an estimated 99 percent. These three emission sources combine to 465 Ibs/ton, before control, and 24.6 Ibs/ ton after about 95 percent control. The typical magnesium content in dolomite is 13 percent. An estimated 2.2 x 10 tons of rock was pro- cessed in 1970, of which only about two thirds was converted to magnesium oxide. Further processing of dolomite will be discussed under magnesium oxide production (Section 4). 2. Mining of Magnesite At present, only one magnesite and brucite mine is operating in the U.S. In preparing magnesite, the steps are similar to dolomite; i.e., crushing and drying. An overburden and waste tonnage equal to twice the magnesite produced, triples the emission up to the point of drying, but simultaneously reduces the magnesium content of the dust by the same proportion. At this mine, the mining, primary crushing, and screening operations are understood to be controlled, resulting in 3332Q 13 ------- tons of magnesium emitted. The drying operation is estimated to be con- trolled at 96 percent efficiency, resulting in an emission of 2,220 tons of magnesium. After drying, binding ingredients are added to the magne- site concentrate to make it the consistency of heavy dough. It is then pressed into briquettes, and dried in rotary kilns at moderate tempera- tures. It is next crushed, screened, and stored. The drying and crushing- screening operations are estimated to generate 100 Ibs/ton and 25 Ibs/ ton of emissions, respectively, at 99 and 96 percent control for a net emission of 631 tons of dust or 250 tons of magnesium. Thus, the mine and plant together are estimated to produce a total of 5,790 tons of magnesium emission, after an average control level of 90.3 percent. 3. Recovery.. From Salt Brines Sea, well, or lake waters containing magnesium chloride are treated with ground, roasted oyster shell or with a magnesium compound to form a precipitate of magnesium hydroxide. This precipitate is subse- quently calcined to MgO (Section 4) or treated and electrolytically separ- ated to magnesium metal (Section 5). Although substantial quantities of precipitate are produced, no emissions are expected except in the case of plants that dry the precipitate for sale or prior to calcining. Emissions from drying in a rotary drier would be expected on the order of 100 Ibs/ton, and would be fairly well controlled (90 to 95 percent, probably). However, no data on the drying of precipitate was obtained. It is assumed that any emissions from this process are included with calcining emissions. 4- Magnesium Oxide Production A variety of oxides are produced for various uses by varying the feed material and the temperature of calcining. Magnesite or MgOH calcined at temperatures below 900 C produces caustic-calcined magnesia, a relatively reactive material used in cements, Pharmaceuticals, and the rubber industry. Dolomite is normally calcined at about 1100 C. However, dead-burned dolomite is produced in rotary kilns at about 1700 C, and dead-burned magnesite at up to 1460 C. Dead-burned magnesias thus produced are used largely in refractory materials. 14 ------- The quantity of emissions from these processes probably depends more on the preparation of the feed material and the type of cal- cining equipment than on the temperature of operation. Material prepara- tion and equipment used are similar to the lime industrys for which data is more readily available. Emissions factors are estimated at 180 Ib/ton for rotary kilns and 7 Ib/ton for vertical kilns, with levels of control at 81 and 39 percent, respectively. ' * It is estimated that 10 per- cent of the dolomite is processed in vertical kilns, and that all hydroxide precipitate and magnesite are processed in rotary kilns. The magnesium content of the particulate is taken to be midway between those of the feed and the final product. The levels of emission control for hydroxide and magnesite calcining are estimated at 80 and 95 percent, respectively, for 1970, Recently, the installation of new control equipment has, no /Q \ doubt, raised these levels of control substantially. The total emis- sion estimate for production of magnesium oxide is 6,463 tons of magnesium into the atmosphere. 5, MagnesiumMetalProduction In 1970, the only process for producing primary magnesium was the electrolytic reduction of magnesium chloride to magnesium and chlorine. The precipitated hydroxide (Section 3) is concentrated by filtration, then redissolved in hydrochloric acid to form a much more concentrated solution of magnesium chloride than the original salt brine. This solution is then fed to electrolytic cells for reduction. In addition to the production of commercial magnesium by this process by a single plant in Texas, between one and three plants in the titanium industry also use the process to recycle magnesium for their own use. The production of chlorine gas from all these processes requires that the emission be well controlled. Even before control, only minute quantities of magnesium would be emitted with droplets in the gas stream. Therefore, it is assumed that emissions from the production of magnesium metal were negligible in 1970. 15 ------- 6• Refining and Alloying Since molten magnesium reacts vigorously with oxygen and nitrogen, precautions are taken to avoid contact with air. The two methods for doing this are: (1) use of fluxes floated on top of the molten metal in the open pots or crucibles and (2) melting in a closed pot con- taining sulfur dioxide. No magnesium emissions are expected from the molten metal in alloying. However, magnesium chloride is a basic con- stituent of the fluxes used with the open pot crucible. The chloride forms magnesium oxide when in contact with water, and slight emission of fluxing magnesium may result. The emission factor of 4 Ib/ton is for a pot furnace. The assumption is made that all primary plus secondary magnesium metal (124,000 tons) was refined, alloyed, or smelted by the open pot process. An estimated level of control of 90 percent is based on controls commonly used in alloying and secondary metal refining. The resulting emission estimate is a negligible 15 tons. 7. Refractory Material Production Fire brick and both wet and dry patching compounds are made in large quantity from magnesia derived from both magjnesite and dolomite. After being calcined at 900 to 1700 C, the magnesia is finely ground, classified, and mixed with other brick ingredients such as chromite or clay. To mix well, drying may be necessary. These processes appear to be major sources of emission, although data are scant. Subsequently, the mixture is cast into brick and dried in stationary kilns at low temperatures; or if fused-cast, melted in an electric arc furnace at up to 2500 C and then poured and cast. During the drying in kilns and through the miscellaneous process of handling, the bricks and compounds appear to generate negligible emissions. The electric casting operation is estimated to be a substantial source of emission, however. Based on emissions estimated for clay refractory materials, and for similar grinding and melting operations, emission factors of 150 Ib/ton for all mechanical operations, and an additional 75 Ib/ton for melting and casting, are assumed. Of the 483,000 tons of magnesium used 16 ------- in refractories, it is estimated that about 10 percent is used in patch- ing materials, and that only about 10 percent of the brick is cast, or about 44,000 tons. The level of emission control should be higher than in the case of clay refractories (64 percent) because the materials are more valuable. A level of control of 80 percent for the mechanical pro- cesses is assumed, and 85 percent for the electric melting and casting processes. The resulting total emission estimate is 7,500 tons of mag- nesium emitted to the atmosphere; the largest estimated emission from the magnesium industry, 8. Magnesium Chemicals Emissions from the production and use of magnesium-based chemicals are estimated to be negligible. a. Magnesium Chloride In addition to usage in the production of oxide and metal, MgCl is also used in oxychloride cements for flooring and plaster, as a fireproofing agent for wood, as a dust binder, and in fluxes for alloying. A small segment of the wood pulpina; indus- try uses magnesium-based chemicals for separating wood fibers. None of these processes appear to generate emissions of any magnitude. b. Magnesium Hydroxide This is used in the pharmaceutical, milk o£ magne- sia, in sugar refining, and by the paper industry. None of these pro- cesses appear to generate emissions of any magnitude. c. Magnesium Carbonate This is used in the production of insulation for steam pipes; in paints, plastics, and paper; and as a soil conditioner. The total quantity of carbonate consumed is very small. 17 ------- d. Magnesium Sulphate This Is used as spsom salts, dyes, drying agents for organic solvents, tanning agents , and fireproof ing , The total con.siitnp- tioa is small. a. Iron: and Steel Production The iron and steel industries use raw dolomite and limestone (containing small amo'mcs of magnesium) as fluxes in the pro- duction of iron and s<;ael. Magnesium metal is also used as a scavenger deaxidixar . Ffrctharmoita, the furnaces and containers used for most molten iron and steel ere lined v;ith refractory material, much of which contrains magnesia , Open hearth furnaces require about 10 Ib of msgnesite brick per ton of .steel produced, for example. It is, of course, not expected tha<: all these sources of magnesium will result in emissions from the fieas-ces. Since magnssiuro has a much lower vaporization tempera- ture than most of the Q'cher elements present, at least some magnesium emission is expected. Table 1 gives the quantities of iron arid steel produced by the major processes , together with generally accepted emission and con- trol factors. Data concerning the amount of magnesium contained in the emission was found to be as follows: Sintering Blast Open Basic fun iscc hearth oxygen Electric arc a. b. c. 0. 0, 0. 0. 0. 6-6a 1-3 2-0 4-0 2-9 Reference Reference Refer en ce a ,7s ,7a a 7 12 14 R 0. 2-3. 6b 0. 0.23° O.le 0, 0. 2-9d 9.2,4S8C 1.2e 0. d. Reference 13 e. Reference 15 6- 1- gj 6 3. 2-0. 4-0. 2- 9. s 6 7 7 2 Est. 3. 1, 0. 0. 5. Ave 0% 2% ^&/ 5% 01 18 ------- These Figures indicate a total estimated average of 4,195 tons of magnesium after control, b. Coal Combustion Coal consumption in 1970 amounted to 517,000,000 tons. The particulate generated has been estimated at 33,800,000 tons of which 82% was controlled, leaving 6,100,000 tons of emission to the atmosphere. Spectrochemical analysis of 373 samples of coal from across the U.S. indicated an average content of 0.70 percent maenesium in the ash. Thus, it is estimated that 236,000 tons of magnesium before control or 42,600 tons of magnesium after 82 percent control, was emitted into the atmosphere. This is almost six times greater than the next largest source of magnesium identified in this study (refractory production). c. Oil Combustion It is estimated that 287,000 tons of particulate are generated by the combustion of residual oils in the U.S. and that this particulate is not under any significant degree of control. The con- tent of magnesium in this particulate has been reported as 0.27 percent (two samples, Ref. 7); 0.053 percent (three samples, optical emission spectroscopy, Ref. 17), and 0.20 percent (one sample, several analytical techniques, Ref. 18). Using an average 0.15 percent, results in an esti- mated emission of 430 tons. d. Asbestos Emissions of asbestos are estimated to have been 6,579 tons in 1970, after control. Chrysolite, the predominant fiber of asbestos, is a silicate of magnesium containing approximately 19 percent magnesium. This results in an estimated emission of 1,250 tons of mag- nesium in 1970. e. Cement Production It is estimated that 934,000 tons of particulate after con- trol were generated from the various processes of cement production in 19?0. 19 ------- Based on limestone, which is distinguished from dolomite in that it con- tains a low percentage of magnesium, one expects that cement emissions will contain significant, but highly variable amounts of magnesium, Partieulate concentrations of magnesium are reported to be: 0,07 percent (three samples of kiln and clinker cooler dust, Ref. 19); C.4 percent (three samples from air separators, Ref. 19); and 1.15 percent (kiln dust, Ref. 7). Based on these percentages, the range of magnesium emissions is 650 to 10,700 tons/year after 88 percent controls with an intermediate value of 3,730 tons/year, C. SUMMARY OF PRINCIPAL EMISSIONS Table 2 summarizes the major sources and estimated emissions of magnesium, as developed in Table 1 and accompanying discussion. The sources are grouped Into two categories, those directly originating within the magnesium industry, and those having no relationsiiip to the magnesium industry, called inadvertent sources. The latter category represents about 62 percent of the total estimated emissions. These principal esti- mates are examined further in section IV of this report. TABLE 2 SUMMARY OF PRINCIPAL SOURCES AND EMISSIONS OF MAGNESIUM Inadvertent Sources Coal combustion Iron and steel production Magnesium Industry Sources Refractories production Magnesite mining and processing Dolomite mining and processing Dolomite calcining, rotary kilns U.S. Tons/ Year of Mg 42,600 4,195 7,500 5,790 3,323 3,593 % of U.S. 56.5 5.6 10,0 7.7 4.4 4.8 89.0 - - i 20 ------- IV. REGIONAL DISTRIBUTION OF PRINCIPAL SOURCES AND EMISSIONS For the purpose of showing geographical distribution, the United States was divided into ten regions identical to the Regional Branches of EPA. Region States I Conn., Me., Mass., N.H., R.I., Vt. II N.J., N.Y., P.R., V.I. Ill Del., Md., Pa., Va., W.Va., D.C. IV Ala., Fla., Ga., Ky., Miss., N.C., S.C., Tenn. V 111., Ind., Mich., Minn., Ohio, Wis. VI Ark., La., N.M., Okla., Tex. VII Iowa, Kans., Mo., Nebr. VIII Colo., Mont., N. Dak., S. Dak., Utah, Wyo. IX Ariz., Calif., Nev., Hawaii and the South Pacific X Alaska, Idaho, Oreg., Wash. The principal emission sources listed in Table 2 are distributed among these ten regions, as shown in Table 3. Also, the number of plants pro- ducing the emissions are shown in the table, when such information is available. When the estimated number of plants was greater than 100, and the distribution of plants was not known, the regional breakdown was made on a different basis, such as population, geographical area, or shipments reported, as most appropriate for that category. Whether the distribution was by plant size, number of plants, or another statistic, the distribu- tion is believed to be accurate to within 10 percent in most cases. The accuracy of the distributions by region varies with the category. The number of plants per category varied from one to several thousand in this study. When the number of plants was less than 100, an attempt was made to identify each plant and plant location, and include it in one of the ten regions. When production or capacity figures for these plants were available, total production or capacity for each region was computed, 21 ------- TABLE 3 REGIONAL DISTRIBUTION OF PRINCIPAL SOURCES AND EMISSIONS Principal Sources Inadvertent Sources Coal combustion Iron and Steel Production Magnesium Industry Sources Refractories production Magnesite mining Dolomite mining Dolomite calcining TOTALS : EPA REGION 1 298 0.7 232 23 357 3 0 0 237 2 257 2 1381 1.8 2 242S 5.7 334 33 833 7 0 0 0 0 0 0 3595 4.8 3 9,287 21.8 1121 111 2025 17 0 0 475 4 513 A 13,421 17.8 4 8,989 21.1 395 39 357 3 0 0 119 1 128 1 9,988 13.3 5 17,422 41.3 1477 146 2975 25 0 0 1539 13 1668 13 25,081 33.3 6 597 1.4 201 20 0 0 0 0 0 0 0 0 798 l.l 7 174 4.1 50 5 120 1 0 0 119 1 128 1 2,164 2.9 8 1406 3.3 20 2 357 3 0 0 237 2 257 2 ,220 2.9 9 298 0.7 294 29 476 4 5790 1 594 5 642 C -) 8,094 10.8 10 128 0.3 70 7 0 0 0 0 0 0 0 0 198 0.3 TOTAL (units) 42,600 (tpy) 100 (% of U.S.) 4,195 (tpy) 415 (U.S. plants) 7,500 (tpy) 63 (No. Plants) 5,790 (tpy) 1 (No. Plants) 3,320 (tpy) 28 (No. (Plants) 3,593 (toy) 28 (No. (Plants) 66,997 «9-0 (% of U.S.) Ref. 4 20 21 4 22 22 ------- and the U.S. emission estimate for that category was distributed by region accordingly. When production or capacity figures were not available, the emission was distributed by the number of plants in each region. If the number of plants was very small or there was reason to believe that cer- tain plants were larger or produced more emission, distributions were weighted accordingly. Specifically5 the largest emission estimate; i.e., from the combus- tion of coal, was distributed percentagewise, according to coal shipments in 1970, by state of destination. Emissions from iron and steel produc- tion were distributed by total number of iron and steel producing plants, by state. This is an approximation since emissions from certain processes, notably sintering and open hearth steel production, are larger than from other processes. Information is not available as to numbers and sizes of sintering equipment by state in the U.S., nor for open hearth production. It is implicitly assumed that the distribution of these largest emission processes will be similar to that of the overall iron and steel industry. Emissions from production of magnesium-containing refractories are distributed by number of plants reporting products of that type, by state, as no information as to the relative sizes of the plants was available. Only one plant was engaged in the mining of magnesite in 1970. Nearly all dolomite mining and calcining were done in the same locations, with the possible exception of a small quantity of additional calcining per- formed by manufacturers of refractory materials to meet their own speci- fications. Ihus, emissions from mining and calcining were distributed in the same way. A map of locations of plants operating rotary kilns for dolomite calcining was obtained from the National Litne Association. The list was supplemented by a list of five additional plants producing dead- burned dolomite, also obtained from the same source. Again, distribu- tion by number of plants does not reflect the relative sizes of the plants, nor the relative cleanliness of their operations. As a result of these distributions, Region 5 was estimated to release the largest amount of magnesium to the atmosphere, 23 ------- about 33 percent of the U.S. total. Reeions 3 and 4 were next, with another 31 percent combined. These results are largely due to the estimates regarding emissions from coal combustion, which contributed roughly two-thirds of the emissions from each of these regions. Considering the geographical area of the ten regions, the most con- centrated emission of magnesium, averaged over the area, was in Region 3, with 0.11 tons of magnesium per square mile per year, closely followed by Region 5 with 0.075 tons per square mile per year. 24 ------- V. OF EMISSIONS The physical characteristics of the particles emitted to the atmo- sphere containing magnesium, and the chemical form of magnesium, are the results of the exact process variables, feed materials, and the nature of magnesium itself. Tables 4a and 4b describe some of the important min- erals containing magnesium, and some of the properties of the metal. The boiling, or vaporization temperature of the various minerals and of mag- nesium is probably the most important property from the standpoint of emissions. Processes that exceed that temperature may be expected to generate large fractions of the magnesium compound present, while pro- cesses operating at lower temperatures should be relatively non-emitting of that magnesium compound as a vapor. Magnesium is among the most readily oxidized elements, which is one of the reasons it is used as a scavenger in steel making. It can be ex- pected to form chemical bonds with oxygen and other elements and element groups rather than remain in metallic form. This is highly probable when hot finely divided particulate is exposed to oxygen. Subsequently the oxide may absorb water or carbon dioxide. The combustion of coal generates the largest emission of magnesium to the atmosphere. The form of magnesium in the coal, before combustion, is not established, but is probably a carbonate. Combustion at tempera- tures on the order of 1500 G is expected to partially reduce the carbon- ate to the oxide. Since, however, the oxide has a vaporization tempera- ture on the order of 3600 C, the oxide will probably not be emitted as a vapor, but as an inclusion with the flyash. Analysis of several sizes of flyash particles for magnesium con- tent showed a uniform 0.6 percent magnesium contained in all parti- cles greater than 1.7 micrometers, and 0.8 percent in particles smal- (25) ler than 1.7 micrometers. Flyash particles themselves vary in size from submicron to greater than 100 micrometers, but average (mass median) diameters are typically from 3 to 10 micrometers. 25 ------- TABLE 4a<8<23»24> DESCRIPTION OF MAGNESIUM MINERALS AND PRODUCTS Mineral Brucite Dolomite, raw Dolomite, calcined Dolomite, dead- burned Magnesite, raw Magnesite, dead- burned Magnesia Magnesia, caustic calcined Magnesium peroxide Olivine Periclase rl Formula MgO' 1^0 CaC03MgC03 MgC03 . MgO MgC03 or MgOH Mg02 (Mg,Fe)2Si04 MgO Process Temp. Natural Natural 1100°C 1700°C Natural Same as magnesia Over 1460°C 950°c or less Natural 1700°C (Also natural) Hardness 2.5 3.5-4.5 —~— 3.5-4.5 „__ 6.5-7.0 Specific Gravity (g/cc) 2.4 2.8-3.0 ,__ 2.95-3.2 3.3-3.4 3.58 Natural materials include varying amounts of other ingredients. Temperature required fot process completion. Standard minerology scale of hardness. TABLE 4b (Ref. 23, Table 3-169) PROPERTIES OF MAGNESIUM METAL Melting point: 650°C Boiling point: 1107°C (MgO boiling point: 3600 C Density; 1.74 g/cc Atomic weight: 24.3 a.w.u. Heat of vaporization: 32.5 kg-cal/g atom 26 ------- Most of the equipment used to control flyash emissions tends to remove the larger particles and allow the smaller ones to escape. Particles on the order of 1 micrometer and smaller may be expected to travel in- definitely (i.e., tens of miles) before being removed from the air by natural processes (settling, agglomeration, washout, etc.). No physi- cal or chemical changes of the magnesium contained in the particles are expected to take place during this period, except for possible absorp- tion of water or carbon dioxide. The next largest estimated source of emission, the production of re- fractory materials, is due mostly to mechanical processes including grinding, crushing, screening and classification mixing, etc. Grind- ing may be expected to generate a substantial quantity of particles on the order of 10-micrometer diameter, as well as some on the order of 1-micrometer diameter. The smaller ones will tend to escape, while the larger, if not immediately controlled, will tend to settle in the vi- cinity of the grinders. The particles that escape will be non-spherical, and will contain magnesium predominantly as an oxide. Screening and mixing operations, being less intensive in terms of the stresses applied to the particles, will tend to emit 10- to 100~mierometer particles and agglomerates, while a relatively small fraction of the material in particles 1 micrometer and smaller will escape the vicinity of the plant. Emissions from mining and calcining are expected to include both the carbonate and oxide forms of magnesium. The emissions from a concentrate drier ahead of the kiln are reported to be 95 percent less than 5 mi- crometers, 85 percent less than 3 micrometers, and 10 percent less than / Q \ 1 micrometer. The literature reports analysis of particulate emitted (*? £c\ from 20 dolomite kilns in Russia as follows: 30- to 70-micrometers diameter before control 40 to 50 percent potassium oxide plus magnesium 10^ to 10 megohm-cm electrical resistance Both calciner or kiln and drier particles are expected to be non-spherical and fairly inert chemically. 27 ------- Dusts in the vicinity of iron works have been analyzed for particle size distributions and MgO content. The average particle sizes ranged from 1 to 4 micrometers; the MgO content ranged from 3,3 to 6,8 percent. The variation of MgO concentration with particle size was not reported, however. In conclusion, the sizes and chemical forms of magnesium containing particles are such that most of the particulate emitted without control measures, and a modest fraction of the particulate emitted despite con- trol measures, will probably not travel far from the emission source. However, a large portion of the U.S. emissions of magnesium will exist in micrometer and smaller particles and will travel long distances from the plant. This magnesium is expected to be chemically inert except for some possible absorption. The magnesium content of city air is reported in one instance as 3 0.42 (total particulate concentration = 44.7 pg/jn ) to 7,21 micro- grams per cubic meter (total particulate not measured) in particles averaging (mass median diameter) 4.5 to 7.2 micrometers. Between 17 and 23 percent of the mass was contained in particles less than 1 (27) micrometer diameter. 28 ------- VI. UPDATING OF EMISSIONS ESTIMATES The following recommendations are made for periodically updating the estimates made in this study; A. VERIFICATION OF CURRENT ESTIMATES 1. Verify that the estimated concentrations of magnesium contained in emissions from the production of iron and steel are representative. Although the concentrations are small, the tonnages of emissions from these pro- cesses are potentially large enough to affect the con- clusions of the study, if the concentrations are in fact higher than estimated. If the concentrations prove to be higher, the emissions estimates should be distributed by region, by types of iron and steel processes, rather than number of plants of all types. 2. Verify that the emission factors for the production of refractory materials, and for the calcining of dolomite and magnesite, are representative. The es- timates used in this study are based on a limited quantity of data which also showed considerable vari- ation from data source-to-source. B. PERIODIC REVIEW OF ESTIMATES 1. The Bureau of Mines estimates for material flow, in- dustry practices, and trends provide the best esti- mates of the size of the industry. 2. EPA activities are currently generating the best emissions data and should be reviewed using: a. Overall industry studies (e.g., Reference 25), b. The Source Test Program in which specific indi- vidual plant emissions are measured. This in- formation provides emission factors for speci- fic examples of typical industrial operations; and also provides some analyses of the particu- late usually including trace metal content and particle size. c. NEDS (National Emissions Data System) is steadily being enlarged and improved. This system can provide emission factors for specific plants and plant operations, the type of particulate control equipment in use, and the actual, or estimated, control efficiency. The system may eventually be expanded to include description of the emissions. 29 ------- 3, The magnesium Industry should be consulted for Its opinion and suggestions on the most recently pub- lished estimates. This may be best accomplished by interviewing the Magnesium Commodity Specialist, Division of Non-ferrous Metals, Bureau of Mines, in Washington, B.C.; or by interviewing one or more of the principal companies in the industry. 4. The literature should be reviewed, using (a) indus- trial views as published from time to time in Chemical Engineering, for example and (b) environ- mental views as summarized in Pol1ut ion Abstracts, for example. 5. Individual companies or plants may be approached for opinions, data, or cooperative tests of their own operations. This is a difficult approach to the problem of obtaining fresh information due to the natural reluctance of the plants to discuss environ- mental problems. However, data thus obtained have a relatively high degree of reliability. 6. State agencies in which specific plants are located may be able to provide useful information, and should be contacted. 30 ------- VII. REFERENCES 1. 1971 Engineering and Mining Journal International Directoryoj Mining and Mineral ProcessInformation, Mining Information Services, New York (1971). 2. Preprint from Mineral Yearbook /'Magnesium Compounds," U.S. Bureau of Mines, Washington, D.C. (1971). 3- 1971 Statistical Abstracts. U.S. Dept. of Commerce, Washington, D.C. (1971). 4. Minerals Yearbook. 1971, U.S. Bureau of Mines, Washington, D.C. (1971). 5. Hazel B. Cornstock,"Magnesium and Magnesium Compounds, A Material Survey," U.S. Bureau of Mines Information Circular 1C 8201, Washington, D.C. (1963). 6. "Compilation of Air Pollutant Emission Factors," U.S. Environ- mental Protection Agency, AP-42, Research Triangle Park, N.C. (1972). 7. A.E. Vandergrift, et al., "Particulate Pollutants Systems Study," Handbook of Emlssion Properties, Vol. Ill, Midwest Research Institute, Kansas City, Mo. (1971). 8. Personal Communications with members of the Magnesium industry. 9. Oliver Bowles, "Limestone and Dolomite," U.S. Bureau of Mines Information Circular IC7738, Washington, D.C. (1956). 10. NEDS (National Emissions Data System) data was used to supple- ment data more readily available in the literature. 11. D.J. Kusler and R.G. Clarke, "Impact of Changing Technology on Refractories Consumption," U.S. Bureau of Mines Information Circular No. 8494 (1970). 12. V. Masek, "On the Composition of Dusts on Work Locations and in the Near Vicinity of Iron Works," Staub, 31(2), 27 (Feb. 1971). 13. W.W, Campbell and R.W. Fullerton, "Development of an Electric Furnace Dust Control System," JAPCA, 12(12), 574 (Dec. 1962). 14. Southern Research Institute, Birmingham, Ala.,"A Manual of Electrostatic Precipitator Technology," Report to NAPCA (EPA), Contract No. CPA-22-69-73 (August 1970). 15. Public Health Service, U.S.D.H.E.W., Air Pollution Engineering Manual, 99-AP-40 (1967). 31 ------- 16. R.F. Abernathy, et al. , "Major Ash Constituents in U.S. Coals," Bureau of Mines, U.S. Dept» of the Interior, Report of Investi- gation No. 7240 (1969). 17. A. Levy, et al., "A Field Investigation of Emissions From Fuel Oil Combustion for Space Heating," Report by Battelle Institute, Columbus,Ohio, to American Petroleum Institute, API Proj. No. SS05 (1 Nov. 1971). 18. D.J. Lehmden, R.H. Jungers, and R.E. Lee, "The Determination of Trace Elements in Coal, Flyash, Fuel Oil, and Gasoline," Part 1. Presented at the American Chemical Society Meeting, Dallas, Texas (April 1973). 19. Source Test Reports of emissions from specific industrial opera- tions, obtained in part from EPA. 20. American Iron and Steel Institute, "Iron and Steel Producing and Finishing Works of the U.S.," a table in the Directory of Iron and Steel Works of the U.S. and Canada (1970). 21. Product Directory of the Refractories Industry in the U.S.. The Refractories Institute, Pittsburgh, Perm. (1968). 22. Commercial Lime Plants in U.S. and Canada (Map), National Lime Association, Washington, D.C. (1970). 23. Perry's Chemical Engineers Handbook, 4th Edition, McGraw Hill Inc., New York (1963), 24. "Mineral Facts and Problems 1970," U.S. Bureau of Mines Bulle- tin 650, Washington, D.C. 25. R.E. Lee, "Trace Metals in Fly Ash as a Function of Particle Size," a single page unpublished table, obtained via R.E. Lee, Research Triangle Park, N.C. (EPA). 26. L.C. Chally, "Physics - Chemical Properties of Dust in Waste Gases During Firing of Refractory Raw Materials in Rotary Kilns," Stal, 30(10), 931, Oct. 1970 (Russian), English abstract, APTIC No. 28311. 27. R.E. Lee, et al., "Particle Size Distribution of Metal Compo- nents in Urban Air," Env. Sci. and Tech., 2(4}, 288 (April 1968). 32 ------- TECHNICAL REPORT DATA (Please read Instructions on the reverse before completing} 1 REPORT NO, 2. EPA-450/3-74-010 4. TITLE AND SUBTITLE National Emissions Inventory of Sources and Emissions of Magnesium 7. AUTHOH(S) 9. PERFORMING ORGANIZATION NAME AND ADDRESS GCA Corporation 6CA Technology Division Bedford, Massachusetts 01730 12. SPONSORING AGENCY NAME AND ADDRESS Environmental Protection Agency Research Triangle Park, N. C, 27711 3. RECIPIENT'S ACCESSION-NO. 5. REPORT DATE May 1973 6, PERFORMING ORGANIZATION CODE 8. PERFORMING ORGANIZATION REPORT NO. 10. PROGRAM ELEMENT NO. 2AE132 11. CONTRACT/GRANT NO. 68-02-9601 13. TYPE OF REPORT AND PERIOD COVERED Final 14. SPONSORING AGENCY CODE 15. SUPPLEMENTARY NOTES 16. ABSTRACT A national inventory of the sources and emissions of the element magnesium was conducted. All major sources of magnesium-containing emissions were iden- tified and their magnesium emissions into the atmosphere estimated. Also, a method for updating the results of the study every two years was recommended. 17. KEY WORDS AND DOCUMENT ANALYSIS •». DESCRIPTORS b.lDENTIFIERS/ Magnesium Air Pollution Emission Inventories Sources 13, LISTmBUTION STATEMENT 19. SECURITY C Uncl Release Unlimited 20. SECURITY c Uncl OPEN ENDED TERMS C. COSATI Field/Group ) i L.ASS (This Report/ 21. NO. OF PAGES assified 32 LASS (This page) 22 . P R I CE assified EPA Form 2220-1 (9-73) 33 ------- |