?/EPA United States [Environmental Protection Agency EPA/540/SR-95/504 May 1995 SUPERFUND INNOVATIVE TECHNOLOGY EVALUATION Emerging Technology Summary Reclamation of Lead from Superfund Waste Material Using Secondary Lead Smelters Stephen W. Paff and Brian E. Bosilovich Hundreds of sites across the United States are contaminated with lead from various sources. Through a Coopera- tive Agreement with the U.S. Environ- mental Protection Agency's (EPA) Risk Reduction Engineering Laboratory, the Center for Hazardous Materials Re- search (CHMR), in conjunction with a major secondary lead smelter, has dem- onstrated that secondary lead smelters may be used economically to reclaim lead from a wide range of lead-contain- ing materials frequently found at Su- perfund sites. Such materials include battery case materials, lead dross, and other debris containing greater than 1% lead. During the study, CHMR and the smelter reclaimed lead from five sets of materials, including two Superfund sites containing primarily battery cases and one battery breaker/smelter site with a variety of lead-containing mate- rials. Between 4 and 1500 tons of ma- terials from each of these sites were excavated or collected and processed at the smelter, while the research team assessed the effects on furnace opera- tion and performance. Two additional sets of materials, one from the demoli- tion of a house containing lead-based paint and the other from work on a bridge coated with lead paint, were also processed in the smelter. The results showed that it was technically feasible to use the secondary lead smelter to reclaim lead from all of the materials. CHMR also assessed the economics of using secondary lead smelters to reclaim lead from Superfund sites and developed a method for estimating the cost of reclaiming lead. This method develops cost as a function of material excavation, transportation, and pro- cessing costs combined with cost ben- efits received by the smelter (in the form of recovered lead, reduced fuel usage, and/or reduced iron usage). The total remediation costs using second- ary lead smelters for the sites and ma- terials studied varied between $35 and S374/ton, based on a conservative mar- ket price for lead. The costs were pri- marily a function of lead concentration, the market price for lead, distance from the smelter, and the amount of materi- als that became incorporated into slag from the process, although other fac- tors affected the economics as well. Materials with high concentrations of lead were significantly less expensive to remediate than those with low con- centrations. The cost to remediate ma- terials that left few slag residues in the Printed on Recycled Paper ------- furnace was significantly lower than the cost to remediate materials that con- tained significant slagging components. This Project Summary was developed by EPA's Risk Reduction Engineering Laboratory, Cincinnati, OH, to announce key findings of this SITE Emerging Technology Project that are fully docu- mented in a separate report of the same title (see Project Report ordering infor- mation at back). Introduction Lead is used in the production of vari- ous consumer and commercial items, from automobile and equipment batteries to paints to crystal. This widespread use has made it one of the most frequent contami- nants at sites on the National Priorities List (NPL). The most common current treatment of lead contaminated wastes at Superfund sites is immobilization, either onsite or in a landfill. Remedial approaches involving recovery of lead are often pre- ferred over immobilization, which wastes usable lead. One such remedial approach is the use of secondary lead smelters for recovery. The objective of this project was to de- termine the technical and economical fea- sibility of processing select lead-containing wastes at secondary smelters. Five types of waste materials were processed a single secondary smelter in different tests. The materials tested include material from three Superfund sites (the Tonolli site in Nesquehoning, PA; the Hebelka site in Weisenburg County, PA; and the NL In- dustries site in Pedricktown, NJ) and two other sources (demolition material and abrasive bridge blasting material). The re- port summarized here presents the activi- ties conducted, the experiments performed, and the results obtained. Process Description The overall process for the project in- volves acquiring the waste material, trans- porting it to a secondary smelter, blending it with typical feeds, and smelting it to reclaim usable lead. A schematic of this process is shown in Figure 1, and the individual steps are described in more de- tail below. Material Acquisition, Preprocessing, and Transportation The first step in reclaiming lead from Superfund wastes is acquiring and trans- porting the material to one smelter. Gen- erally, this involves excavation or collection, pre-processing, and transport to the smelter. The lead-containing waste Transport of material 'CO Rocks, soils, debris Mixing Slag to disposal Smelter Typical smelter feed Figure 1. Schematic of reclamation process. material is typically excavated from lead- acid battery Superfund sites. Materials may be collected from other sources, such as bridge blasting or demolition operations. Some materials often require some type of processing before entering the furnace. Preprocessing includes screening to re- move soil, large stones, or non-contami- nated debris. Soil cannot be processed through a secondary smelter. Larger de- bris (>12 in.) is also removed because large material tends to remain unburnt in reverberatory furnaces. This causes slug- gish performance and slows productivity by the reverberatory furnaces. Preprocess- ing can be done at the site or at the smelter, depending on which is more cost efficient. Blending with Typical Furnace Feeds Once the material arrives at the sec- ondary lead smelter, it is blended with typical feed before processing through the smelter's reverberatory and blast furnaces. This mixing prevents problems associated with the layering of the test material in the furnaces. Typical blend ratios range from 10% to 50% by weight, and are deter- mined based on treatability tests and other factors, such as lead, sulfur, iron, or ash content. Smelting Process As part of normal secondary lead smelt- ing operations, spent batteries received at the smelter are crushed to release the sulfuric acid and then processed through a sink/float system to separate the battery cases. Dual reverberatory furnaces at the smelter are charged with material from the sink/float system as well as other lead- containing material. These furnaces are fueled with natural gas and oxygen. Re- verberatory furnaces are tapped for slag, which typically contains 60% to 70% lead, and a soft (pure) lead product. Dual blast furnaces are charged with the slag generated from the reverberatory furnaces as well as other lead-containing materials. These furnaces are fueled by coke and oxygen-enriched air. Iron and limestone are added as fluxing agents to enhance furnace production. The blast fur- naces are tapped continuously to remove lead and intermittently to remove the slag. The blast slag, which contains primarily silica and iron oxides, is transported to an offsite landfill for disposal. Lead produced in the blast and rever- beratory furnaces is transferred to the re- fining process where additional metals are added to make specific lead alloys. The lead is then pumped to the casting opera- tions where it is molded into ingots for use in the manufacture of new lead-acid bat- teries. Test Materials Materials from three Superfund sites as well as two additional sets of lead-con- taining materials were processed during this project. Table 1 presents a summary of the materials tested and the evalua- tions. A short description of each of the five evaluations follows the table. The feed rates are presented as weight ratios of test material to total furnace feed. Tonolli Superfund Site The Tonolli site was a battery breaking and smelting facility located in Nesquehoning, PA. Piles of ebonite rub- ber and polypropylene battery case pieces ------- Table 1. Summary of Demonstration Sites Test Parameter Tonolli Site Demolition Waste NL Industries site Pen n DOT Site Type Integrated battery breaker, smelter, and lead refiner Automobile junk and salvage yard Not applicable Integrated battery breaker, smelter, and refiner with onsite landfill Bridge blasting operation to remove lead paint site landfill Length of Test Material Type 5 days Rubber and plastic battery cases 1 day Rubber and plastic battery cases with some soil 2 days Demolition debris coated with lead paint Preliminary: 4 days Full: 3 months Lead slag, debris, dross, ingots; bat- tery case pieces, baghouse bags, pallets, cans 1 day Iron shot bridge blasting material Amount Processed Percent Test Material in Feed 84 tons 10% 8 tons 17% 4 tons 5% Preliminary test: 370 tons Full-scale test: 1200 tons 20% to 50% 6 tons 13% Lead Concentration Preprocessing Difficulties Encountered 3.5% None Attempted to process in reverb, but material was too large 14.7% Reduced to less than 1/4 in. in a hammermill None 1% Reduced in size with a pallet shredder Initial feed ratio was too high Preliminary: 57% Full: 30% to 50% Large pieces re- moved for process- ing in the blast furnace Reverb could not process 100% waste material 3.2% None Material was too moist to process in reverb furnace were tested, without any preprocessing. The material had an average lead con- centration of 3.5%. Approximately 84 tons of material were fed at a ratio of 10% through a reverberatory and blast furnace. The material was too large to be readily processed in the reverberatory furnace but was successfully processed in the blast furnace. Hebelka Superfund Site The Hebelka site was a former automo- bile junk and salvage yard located in Weisenburg Township, PA. The site con- tained battery case debris mixed with some soil that had an average lead concentra- tion of 14.7%. Approximately 20 yd3 of material were transported to the smelter. This material was first reduced in size to less than 1/4-in. with a hammermill. The material was successfully fed to one of the dual reverberatory furnaces at a feed ratio of 17%. Demolition Waste The demolition waste consisted mainly of wood coated with lead based paint and had a lead concentration of between 0.5% and 1% The test material was shredded in a pallet shredder before it was smelted. The demolition debris was processed through both reverberatory furnaces at feed ratio of 10% test material, by weight. At this weight ratio the test material com- prised 50% of the volume fed to the fur- naces. This high volumetric ratio caused malfunctions in the furnaces, so the feed ratio was reduced to 5%, at which point the material was successfully fed. NL Industries Superfund Site The NL Industries site in Pedricktown, NJ, was an integrated battery breaking, smelting, and refining facility with its own onsite landfill. There was a wide variety of materials at the site including lead slag, dross, debris, ingots, hard heads (large chunks of metallic lead), battery case de- bris, baghouse bags, and contaminated pallets and iron cans. The evaluation was conducted in two parts: a preliminary in- vestigation and a full-scale investigation. During the preliminary investigation, ap- proximately 370 tons of all types of the above materials were processed. Analy- ses revealed an average lead concentra- tion of 57%; however, the materials ranged in concentration from 7% to 69% lead. The larger pieces of debris were removed and processed through a blast furnace; while the bulk of the material was fed into a reverberatory furnace at feed ratios of up to 100%. The feed was sufficiently dense to cause breakdowns in the rever- beratory furnace conveyor feed system, so the feed ratio was reduced to 50% test material, by weight. During the full scale operation, approxi- mately 1200 tons of material were trans- ported to the smelter over a three month period. During the first two months the test material, which contained approxi- mately 45% by weight lead, was processed in the reverberatory furnace, at a feed ratio of 20% to 30%. The ratio was limited because of high amounts of calcium in the material. The high calcium concentra- tion slowed the operation of the furnaces. During the last month of the evaluation, the test material consisted mainly of larger pieces of slag and debris with an average ------- lead concentration of 30%. This material was charged to one of the blast furnaces at a feed ratio of approximately 30%. Pennsylvania Department of Transportation The Pennsylvania Department of Trans- portation (PennDOT) used an iron-shot abrasive blasting material to remove lead- based paint from a bridge in Belle Vernon, PA. Sixteen 55-gal steel drums of this material, containing an average of 3.2% lead, were processed at the smelter. The material contained too much moisture to be incorporated into the reverberatory feed. The test material, including the drum, was charged directly to a blast furnace at a feed ratio of approximately 13%, by weight. The bridge blasting material was primarily iron (60%) with 5% calcium and 5% to 10% misture content. Test Procedures Test material was charged to either the reverberatory furnaces or blast furnaces, depending primarily on the size of the material, but also on other factors such as lead content and percent ash. Project per- sonnel collected samples and data to as- sess the furnace performance, characterize the input material, and characterize the furnace outputs. Table 2 shows the pa- rameters that were measured and how they were obtained. The input material parameters were characterized to provide information related to the feed, so that comparisons of the effects of different feeds could be made. The furnace perfor- mance parameters, such as oxygen us- age, fuel usage, furnace feed rates, etc., provided important furnace operation in- formation while the experiments were con- ducted, principally indicating when production levels were falling or materials were clogging in the furnace. The output parameters were the most important mea- surements of furnace performance, includ- ing production rates and quality, as well as residuals generation. The data generated from measurements and sample analyses were used to com- pare the performances of the test and control furnaces. The amount of lead in each product is useful in making a mass balance for the lead. Other parameters, such as oxygen, air, and fuel, are useful in determining the cost for processing the test material. Results In general, the study demonstrated that various materials may be processed in secondary lead smelters with relatively few effects on overall furnace performance. Table 2. Input, Output, and Operating Parameters Input Material Characterization Furnace Performance Parameters Furnace Output Parameters total lead (S) sulfur (S) silica (S) calcium (S) moisture content (S) density (M) particle size distribution (M) BTU value (S) test material in the feed (M) air flow (M) % oxygen enrichment (M) fuel usage (M) lead inputs (S) iron inputs (S) % test material in feed (M) lead production rates (M) slag production rates (M) slag viscosity (Of % lead in the slag (S) % sulfur in the slag (S) back pressure (M) sulfur dioxide emissions (M) calcium sulfate sludge (S) *(S)=Sample (M)=Measurement (O)=Operator Observation The most significant effects were caused by processing materials in a furnace with- out properly preprocessing it or by pro- cessing too much material at one time. For example, the Tonolli feed was too large to be processed effectively in the dual reverberatory furnaces. This caused the furnace production to slow down sig- nificantly. Later, the same type of material from the Hebelka site was successfully processed in the reverberatory furnaces after it had been shredded in a hammermill to a particle size of less than 1/4-in. The NL Industries site material was initially unsuccessfully processed at a 100% feed ratio because it was too dense for the feed system. When the ratio of test mate- rial to total feed was lowered to 50% the material was processed with few prob- lems. Feed Ratios The normal feed-to-waste ratio for these materials was one of the parameters tested during this study. Based on furnace per- formance and operations results, it was possible to determine whether the furnace performed successfully or unsuccessfully at any given feed ratio. A test is consid- ered to be unsuccessful if the feed ratio of test material has to be lowered, or discon- tinued altogether. Test results show that the successful mix ratios are strongly a function of the percentage of lead in the waste material. Figure 2 shows the successful feed ratios, plotted against the percentage of lead in the waste material (i.e., before blending with normal feed). The results are nearly linear from streams containing 3% lead to those containing 60% lead. This delin- eates the region marked "successful" on the figure. When the feed ratios versus lead concentration for unsuccessful runs are plotted, a second region (the "unsuc- cessful" area) emerges. Finally, a third region, in which no tests were performed, is also marked on the figure. No test feed with more than 60% lead was fed to the furnaces, so the regions in the range above 60% lead cannot be determined from the experimental results. Reclamation Efficiency In determining whether the process is suitable for reclamation of lead, it is im- portant to determine whether the smelter actually reclaimed the lead in the test ma- terial. Unfortunately, there is no way to accurately measure the extent of recla- mation because the test material has to be mixed with typical feed. Based on con- servative assumptions and furnace output parameters such as initial lead content and percent ash, CHMR developed a method to estimate the minimum recla- mation efficiency. This method indicated that lead was reclaimed from all test ma- terials over a range of efficiencies, from an estimated 70% for the abrasive blast- ing material to 99.5% for NL Industries material. ------- 100% o" 80% "§ 60% .c I 40% I w ^ 20% 0% X-* \Unsuccessful x* *' 0% 10% 50% 20% 30% 40% % Lead in test material Successful experiment A Unsuccessful experiment 60% Figure 2. Percent lead in test material versus feed ratio. Economics CHMR used the experimental data and other information to develop an economic model based on the following costs and values of recovered materials: • Excavation costs • Transportation costs • Smelter processing base cost • Additional production costs associated with storage and handling of an atypical material at the smelter • Additional disposal costs • Lead recovery • Reduction of iron, coke, or other furnace feeds. With this model, the costs in the follow- ing table have been estimated for the ma- terials used in this evaluation. Table 3 includes two costs, the first is based on a conservative market value for lead ($6507 ton) and the second on a more plausible long-term value for lead ($750/ton). Note the relationship between the costs and some of the material characteristics. Lower lead content causes an increase in costs, whereas ash content and distance from the smelter have a lesser effect. Conclusions The conclusions drawn from the study are: • Lead was successfully reclaimed from a variety of materials found at many Superfund sites, including battery case pieces, slag, dross, lead debris, spent abrasive material, and demolition material contaminated with lead paint. The lead concentration in these materials ranged from 1 % to 45% • The economics of reclaiming lead depend on lead concentration, market price for lead, distance from the smelter, percent of test material that becomes incorporated into the final slag, iron content, BTU value of the test material, and sulfur content. • The cost for recovering lead from the five sites selected for this project, based on a conservative market price for lead ($650/ton), ranged between $80 and $374/ton. Overall, CHMR concludes that second- ary lead smelters provide a viable alterna- tive to stabilization and disposal for the treatment of wastes found at battery breaker and some Superfund sites. This process also makes it possible to recycle and reuse lead which is a useful resource. Table 3. Estimated Cost of Remediating Sites Site P=$650/ton P=$750/ton Distance(miles) %Ash % Lead Tonolli Hebelka Demolition Material NL Industries PennDOT $228 174 374 80 231 $224 160 373 35 228 40 75 100 300 250 20 30 4 65 70 3.5 14.7 1.0 45.0 3.2 ------- ------- ------- Stephen W. Paff and Brian E. Bosilovich are with the Center for Hazardous Materials Research. Laurel Staley is the EPA Project Officer (see below). The complete report, entitled "Emerging Technology Report: Reclamation of Lead from Superfund Waste Material Using Secondary Lead Smelters," (Order No. PB95-199022; Cost: $19.50, subject to change) will be available only from: National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 Telephone: 703-487-4650 The EPA Project Officer can be contacted at: Risk Reduction Engineering Laboratory U.S. Environmental Protection Agency Cincinnati, OH 45268 United States Environmental Protection Agency Center for Environmental Research Information Cincinnati, OH 45268 Official Business Penalty for Private Use $300 BULK RATE POSTAGE & FEES PAID EPA PERMIT No. G-35 EPA/540/SR-95/504 ------- |