Free Reply to Response to Motion - District Court of Federal Claims - federal

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used as sources of sulfate in certain.solid wastes that contain sufficient calcium to begin with. Application of the "MAECTITE- Treatment Process" Step One (I) requires a thorough and uniform mixing of gypsum powder with the solid waste. The calcium ions from the gypsum powder displacelead from soil complexes and organic micelles present in the contaminated soil and solid waste material. The following equations (i) and (2) describe the reaction of leachable lead with gypsum.
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Pb-Micelle + CaSO4.2H20~PbSO4 + Ca-Micelle + 2H20 ..........

(i)

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Pb(HC03)2 + CaSO4.2H20--~PbSO4 + CaCO3 + 3H20 + C02 ......... (2) Anglesite The ~eaction of lead .with gypsum forms a "hard sulfate" which crystallizes into mineral species of the barite family. Specifically, these mineral salts are anglesites and calciumsubstituted anglesites which are insoluble in water. The solubility product of lead sulfate is 1.8 x10-8, indicating that anglesite crystals would continue to develop over the geo!ogic periods. In the second step of the MAECTITE- Treatment Process, the gypsum powder amended solid waste material is treated with a phosphate supplying reagent which in contact with the soil ~reacts chemically to immobilize the remaining leachable lead. The phosphate supplying reagent includes phosphate ion source having one or more reactive phosphate ions; for example, phosphoric acid, trisodium phosphate, a potassium phosPhate 'and mono basic or dibasic calcium phosphates. The lead, along with the calcium ions, reacts with the phosphate to form insoluble "super-hard" rock phosphates or calcium substituted hydroxy lead apatites as shown in equation (3a and b):

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4PbC0~+CaC03+3H3PO4-~Pb4Ca(OH) (P04) 3 + 5C02 + 4H20 ....... Hydroxy Lead Apatites 4PbCO3+CaSO4.2H20+3H3P0~Pb4Ca(OH) (PO4)3 + H2SO4 + 4C02 + 5H20.. (3b) Hydroxy Lead Apatites The phosphate ions are added to the contaminated soils in solution form; for example, phosphoric acid may be added to water in amounts ranging from about 2 percent to about 75 percent by weight. Phosphoric acid decbmposes carbonates and bicarbonates in wastes leading to the synthesis of aPatites and evolution of carbon dioxide gas. Although water molecules are generated during the carbonate and bicarbonate decomposition process, it is preferred to have sol! moisture at about i0 per cent to about 40 per cent by weight of the soil in order to accelerate the fixation of the leachable lead with the phosphate ions. At this moisture range, material handling is also easy and efficient. It is apparent from Equation (2), (3a) and (3b) that gypsum and phosphoric acid decompose carbonates and bicarbonates during synthesis of new stable minerals of the barite, apatite, and pyromorphite families in soils. Decomposition of carbonates/bicarbonates is usually associated with the evolution of carbon dioxide, formation of hydroxyl group, (OH-), and release of water molecules. The solid sulfate powder and the phosphate supplying reagent are added to contaminated soil and solid waste material having a typical moisture content ranging from about I0 percent to about 40 percent by weight.. At a moisture.level within the foregoing range, the curing time of the treated materials is approximately 4 hours, which provides adequate time for chemical reactions to occur and immobilize the leachable lead species. Crystals of various lead mineral species begin to form immediately as the drying continues. Under the foregoing conditions, the immobilization of leachable lead occurs in a relatively dry environment because no wet byproducts, slurries and wastewaters are produced by the MAECTITETreatment Process. Operation of Steps I and II under relatively' dry conditions allows cost-efficient handling of the contaminated soils and the waste materials. This allows compliance with Paint Filter

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Test for solid wastes (Method 9095) required by USEPA and RCRA approved solid waste landfill facilities. The Water resistant and insoluble lead minerals synthesized in soils and solid wastes according to this economically, practical, and demohstrably proven technology are stable, and would behave like naturally occurring rock phosphates and hard sulfates. A list of these synthetic lead mineral species and complexes is presented below (Table I), in order of the relative abundance found during characterization of treated soil by x-ray florescence spectrometry, polarized light microscopy (PLM) and scanning electron microscopy. (SEM). TABLE ~ I Synthetic Mineral Species of Lead Detected in a Treated sample. (Listed in Decreaslnq Order of Abundance)

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31-41%, 2O 28-29%,

¯ Calcium Substituted Hydroxy Lead Apatites, Ca0.5-1.5Pb3.5-4.5(OH) (PO4)3 Mixed Calcium Lead Phosphate Sulfates, Ca0..05-0.2Pb0.8-0.95(PO4)0.15-0.5(SO4)0.25-0.75 Mixed Calcium Angiesites, Ca0.05.0.3Pb0.7_0.95SO4 Anglesites, PbSO4 Lead Hydroxy/Chlor Apatite, Pb5(PO4)3(OH)0.5CI0.5 Pyromorphite, Pb~(P04)2 Organo-Lead Phosphate Sulfate, Humus-o-Pb3(PO4) (S04)

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21-22%, 3-6%, 2-7%, 1-3%, I-2%,

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Some of the chemical reactions that occur during the curing stag'e, and lead to the development of mixed minerals containing both sulfates and phosphates, are illustrated in equations (4) and (5). 18PbCO3+5CaSO4.2H20+I2H3PO4 Curing Time of 4 hours under Ambient Temperature (>30° F) & Pressure

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20Ca0.1Pb0.9(PO4)0.5(S04)0.25 + Ca3(PO4)2 + 18CO2 + 28H20... (4) Sulfate MixedCalcium Lead Phosphate
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6Pb[Humus]+2CaSO4.2H20+3H3PO4 C~urinq time of 4 hours under Ambient Temperature (30 F) & Pressure Ca(9H)[Humus]-Pb3(P04)SO4 +2H20+Ca0.3Pb0.7S04 +Ca0 7Pb2.3(PO4)2"~(5) Organo-Lead phosphate Ca substituted Ca substituted Pyromorphite Anglesite sulfate The "MAECTITE- Treatment Process" decreases the volume of the waste materials. This is due to: (i) the evolution of carbon dioxide during the chemical decomposition of carbonates and bicarbonates, upon reaction with the acidic components in gypsum and phosphoric acid, and (ii) hardening and compaction as a result of the synthes~s.of new minerals which lead to changes in interstitial spaces and interlattice structures. Application of MAECTITETreatment Process on a lead contaminated soil was associated with pore space decrease from 38.8% to 34.3% by volume. A decrease in pore space was associated with increased compaction of the treated soils and a decrease in overall waste volume ranging from 21.4% to 23.0%. For different waste types, volume decrease varies depending on the amount of treatment chemicals used in MAECTITE~ Treatment Process. In another lead toxic solid waste, application of MAECTITE- Treatment Process resulted in a volume decrease of the order of 36.4% while decreasing the leachable lead to levels'below the regulatory threshold. The reduction in volume of the contaminated soil and the. solid waste material makes the MAECTITE- Treatment Technology particularly beneficial for off-site disposa! in a secured landfill by cutting down the costs of t~ansportation and storage space. The "MAECTITETreatment Process" can be assembled at a cost-efficient engineering scale on-site or off-site for ex-situ treatment of lead-toxic solid wastes. " This innovative treatment technology offers a great potential for in-situ application to immobilize lead most economically without generation of any wastewater or byproducts. The MAECTITE~ Treatment Process is schematically represented in Figure I. The lead-contaminated uncontrolled hazardous .waste site 00 with lead-toxic wastes is subject to excavation 02 and segregation of waste piles based on their total lead and TCLP lead contents into (a) heavily contaminated pile 04a; (b) moderately

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contaminated waste 04b and, (c) least contaminated waste material 04c. The staged soil and solid waste material 04 is subjected to grinding, shredding, mixing 06 and screening 08 through an appropriately sized mesh sieve. The screening yields particles that are usually less than 5 inch in diameter for mixing with~ gypsum powder I0 in a grizzly that allows a uniform coating of calcium sulfate dihydrate (the solid powder i0) over the soi! particles and waste aggregates during the grinding, shredding and/or mixing step. Or alternatively, as shown by the dashed line, gypsum powder i0 is added continuously to the screened solid waste material in prescribed amounts as determined during treatability trials. Most of the leachable lead binds chemically with gypsum at molecular level and forms lead sulfate, which crystallizes into a synthetic nucleus ~of mixed calcium anglesite and pure anglesite minerals identified in the treated material by chemical microscopy techniques. The gypsum-coated waste particles and aggregates are then transported on a Belt Conveyor 12 to an area where an effective amount of phosphoric acid solution 14 of specified strengths in water 16, is added or sprayed just prior to thorough mixing in a pugmill 18. The temperature of the phosphoric solution must be maintained above 30 F to prevent it from gelling. The treated soil and wastes are subject to curing 20 and .drying 22 on a curing/drying pad. The end product of the MAECTITE- TreatmentProcess passes the paint filter test ~(USEPA approved procedur~ 9095, SW 846). During the curing time of about four hours, various "super-hard phosphate" mineral species such as calcium-substituted hydroxy lead-apatites, and mixed calcium-lead phosphate-sulfate mineral species are formed in treated waste media 24. Poorly deve!oped crystals of these mineral species have been identified in the treated soil materials and solid wastes by chemical microscopy techniques like PLM and SEM. The proportions of waste materials and reagents used in the MAECTITE- Treatment Process may be varied within relatively wide limits. For example, the amount of gypsum powder ~should be sufficient to produce lead sulfate in contaminated soil or solid waste material. In addition, the amount of phosphate supplying

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EXAMPLE I Nearly twenty (20) different chemicals and produGts from various vendors and supply houses were screened for chemical fixation of leachable lead in hazardous solid waste samples. Only six (6)' of these treatment chemicals were found effective in decreasing the leachable lead as measured by: (i) EP Toxicity test (USEPA approved Method 1310) and (2) TCLP test (USEPA approved Method 1311). Table III presents a summary of leachable lead found in untreated and treated waste samples allowed to cure for a minimum of 4 hours. Evaluation of a single treatment chemical in one step reveals that phosphoric acid was most effective in fixation of leachable lead followed by granular super-pho'sphate, a fertilizer grade product available .in nurseries and farm supply houses. However, neither treatment effectively treated leachable lead to the USEPA treatment standard of 5.0 milligrams per liter by TCLP methodology.

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TABLE Ill Relative effectiveness of various treatment chemicals screened to d~characterize the lead-toxic solid wastes.

Treatment Chemical~[Ste~)_ I. Untreated Control
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Leachable Lead in mq/l EPToxicity, Test TCLP Test
221.4 704.5

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Single Treatment Chemical (One Step Treatment) 11.7 a. Sulfuric Acid (I) b. Phosphoric Acid (I) 1.0 c. Superphosphate Granular(I) 2.7 d ¯ Li~id Phosphate Fertilizer(I) 19.4 24.9 e. Gypsum Powder (I) f. Sodium Phosphate (I) 28.7 III. Two Step Treatment g. Sulfuric (1) & Lime (II) 20.6 3.9 h. Gypsum Powder (I) & Alum (II) i. Sodium Phosphate (I) & Phosphoric (II) 3.1 j. Gypsum (I) & Phosphoric (If) N.D.* IV. Three Step Treatment k. Gypsum (I), Alum (II) & Sodium Phosphate (III) 12.8 N.D.*

39.8 5.9 11.4 64.3 81.8 93.9

68.1 15.3
12.6 1.6

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i. Gypsum (I), Phosphoric (II) & Sodium Phosphate (III)

1.4

* N.D. means non-detect at <0.5 mg/1.

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Although both phosphoric acid and granular superphosphate were effective in meeting the EP Toxicity test criteria at 5.0 milligrams per literbut this USEPA requirement is now obsolete and has been replaced by TCLP lead test criteria of 5.0 milligrams per liter. Single application of the phosphoric acid, granular ~uperphosphate or any other chemical was short of meeting the regulatory threshold of 5.0 milligrams per liter by TCLP-Iead test criteria. And hence, two-step and three-step processes were designed and tested for leachable lead. In a two-step treatment Process, application of gypsum during Step I and treatment with phosphoric acid in Step II resulted in decrease of TCLP-Iead consistently and repeatedly below the regulatory threshold of 5.0 milligrams per liter. The results of this two-step treatment process utilizing gypsum in Step I and phosphoric acid in Step II were not only reproducible but also applicable to a wide variety of lead contaminated wastes as exhibited in Example II. The' three-step process, though tried with Success, was not perceived as economically viable as a two-step treatment process. And hence, the following examples illustrate the deployment and commercialization of the two-step process under the trademark MAECTITE- Treatment Technology where amendment of lead-toxic waste with gypsum powder in Step I and treatment of gypsum amended waste with phosphoric acid in Step II leads to the fixation and stabilization of lead in a variety Of solid wastes. Current land ban regulations prohibit the landfilling of lead-toxic waste containing TCLP-Iead >5 milligrams per liter. The MAECTITETreatment Process is available to decharacterize the lead-toxic wastes. After a curing time of 4 hours, the treated waste usually meets the regulatory requirement for TCLP-Iead as well as EP toxic lead. In order to illustrate the relative proportions of two chemicals, gypsum and phosphoric acid, needed for treatment of leadtoxic wastes, three soil samples from a lead contaminatid test site were processed using MAECTITE- Treatment technology in two steps: Gypsum powder was used in the first step and phosphoric acid DG0183

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solution in water at concentrations of about 7, 15 and 22 percent by weight in the second step. The soil was measured for lead content in accordance with the Extraction Procedure (EP) Toxicity Test before and after treatment. A level of leachable lead below 5 milligrams per liter was considered non-hazardous according-to this procedure. During these test runs of MAECTITE- Treatment Techno!ogy, the EP Toxicity Test criteria was in force for treated waste material. The results are shown in Table IV:
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TABLE IV Effectiveness of MAECTITE- Process in Fixation and Stabilization of Leachable Lead in lead toxic soils.
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EPTOX LEAD TEST RESULTS
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Soil Sample (Lead-toxic waste)

MAECTITE- TREATMENT PROCESS Gypsum Phosphoric Step I Step II (g/kg soil) (g/kg soil)

Before After Treatment Treatment milliqr.~s.~....per liter.

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i. Low lead contamination 20 2. Moderate contamination 30

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30

8 61
3,659

< 0.i < 0.i
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3. High lead contamination

40

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The foregoing results demonstrate that the MAECTITE~ Treatment of the lead-toxic sold waste was effective in al! three sampl~s, depicting 3 different levels of lead contamination. The MAECTITETreatment technology is flexible and is usually optimized during bench scale treatability studies for each waste type to immobilize the leachable lead and to decharacterize or transform the lead-toxic waste into non-hazardous solid waste acceptable to TSD facilities. During commercial application on a full-scale, a net reduction of 36.4% in waste volume was noted as a result of MAECTITE- T~eatment.

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Typical volume reductions attributable to MAECTITE~ Treatment technology are given in Table V. ,TABLE V

Change in Solid Waste Volume as a Result of MAECTITE~ Treatment

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SOLID WASTE MATERIAL (Treatment Scale)

(SOLID WASTE Initial (Before MAECTITETreatment Process)

VOLUME) Final (After MAECTITEtreatment & curing)

DECREASE IN WASTE Volume

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i. Lead toxic soil 3850 cu. yd. (full scale)
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2. Lead-toxic Solid Waste (Bench Scale) Test Run I Test Run II 106.1 cu. in. 22.0 cu. in. 81.51 cu. in. 17.3 cu. in. 23.0 21.4

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Most profound effect of MAECTITE- Treatment Process ,is at structural level where breakdown of granular aggregates is associated with a loss of fluffiness and a decrease in pore space with increased compaction due to physical, .mechanical and chemical forces at different levels. At molecular level, phosphoric acid. breaks down the carbonates and bicarbonates including cerussites in stoichiometric proportions. Soon after the addition of phosphoric acid to a solid waste containing cerussites, extensive effervescence and frothing becomes evident for several minutes and sometimes for few hours. The phosphoric acid breaks down the acid sensitive carbonates and bicarbonates leading to the formation of carbon dioxide, water and highly stable and insoluble sulfate and phosphate mineral compounds. Thus, structura! changes due to interlattice reorganization as well as interstitial rearrangement in waste during MAECTITE~ processing are associated with an overall decrease in waste volume. Depending on the extent of carbon dioxide loss from DG0185
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the breakdown of carbonates and bicarbonates present in the leadtoxic solid waste, MAECTITE- Treatment Process may lead to a sl~ght loss of waste mass as wel!. The cost of the MAECTITE~ Treatment technology is moderate to low depending upon (i) waste characteristics, (ii) treatment system sizing, (iii) site access, (iv) internment of final disposition of' treated materia! and (v) site support requirements. On a commercial scale, the costs of treatment and disposal were approximately $115 per ton of lead-toxic waste, as compared to disposal costs of~over $250 per ton if no treatment had been executed using the MAECTITE~ Treatment Process. Recent land ban regulations would prohibit the landfilling of all lead-toxic wastes. From the foregoing example, it is clear that ¯ the MAECTITE- Treatment Process provides an efficient technology which, is economically attractive and commercially viable in meeting regulatory criteria for landfilling. MAECTITE- Treatment Process has proven to be an acceptable treatment technology for control of leachable lead. in ~ontaminated soils and solid waste materials.

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EXAMPLE II MAECTITE- Treatment Process was applied on bench scale to five different lead-toxic waste materials that were characterized for total lead, TCLP-lead, moisture content and pH before and after the MAECTITE- Treatment. A curing time of 5 hours was allowed for completion of the.treatment process. The results compiled in Table VI exhibit profound-effect of the MAECTITE- Treatment technology in decreasing the TCLP lead in a wide range of lead-toxic soils and solid wastes containing total lead as high as 39, 680 mg/kg and TCLP lead as high as 542 milligrams per liter. In each of the' five cases, MAECTITE- Treatment Process immobilizes the leachable lead to levels be!ow the regulatory threshold of 5 milligrams per liter by the TCLP-Iead test criteria currently in force under the land ban regulations of the United States Environmental Protection Agency.

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TABLE Vl Typical changes in solid waste characteristics due to MAECTITE~ Treatment Technology.
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SOLID WASTE CHARACTERISTICS I. Lead-toxic SW-A Total lead, % TCLP-Lead, mg/l Moisture, % pH, S.U.
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MEASURED VALUES After MAECTITE~ Before MAECTITETreatment & Curin~ Treatment
1.442 542.0 23.0 8.1 ' 1.314 2.0 33.0 4.8

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II. Lead-toxic SW-B 0.847 Total lead, % 192.0 TCLP-Lead, mg/1 27 Moisture/ % 8.0 pH, S. U. .III. Lead-Toxic SW-C 3.968 Tota! Lead, % 257.6 TCLP-Lead, mg/l i0.0 Moisture, % 7~2 pH, S. U. IV. Lead-Toxic SW-D 2.862 Total Lead, % 245.3 TCLP-Lead, mg/l 71.6 Moisture, % 8.1 pH, S. U. V. Lead-Toxic Soil SW-E 0.16 Total Lead, % 7.5 TCLP-Lead, mg/l 12.3 Moisture, % 7.0 pH, S.U.

0.838 2.4 36 5.3 3.066 1.0 18.1 4.5
2 .862 0.38 84.1 6.3

0.12 1.87 23.0 5.4

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It is obvious from Table VI that MAECTITE- Treatment Process operates under a wide range of moisture and pH conditions It is

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associated with 8 to 11% rise in moisture content. The end product of the treatment process may contain moisture in a~ typical range of 18% to 36% on a dry weight basis. The end-product passes the paint filter test for solids (USEPA Method 9095 in SW-846) and there are no other byproducts or side streams generated during the MAECTITETreatment Process. The treated solid waste is cured in 4 to 5 hours and may be allowed to dry for 2. to 3 days after treatment for loss of unwanted moisture prior to final internment and disposition. This time is sufficient for the TCLP tests to complete as part of the disposal analysis under land ban regulations. No attempt has yet been made ~o establish a quantitative relationship between the amount of treatment chemicals needed for MAECTITE- Treatment Process with the total lead content and/or TCLP~. lead level of solid waste because the chemical consumption to a large extent depends on other waste characteristics such as cation exchange capacity, total buffering capacity, amount of carbonates and bicarbonates present in various~ forms and amount of lead in the hazardous solid waste material. Optimum leve! of gypsum and phosphoric acid required during the MAECTITE- Treatment Process must be determined directly by bench-scale treatability studies for each solid waste considered for lead fixation and stabilization. Wq{AT WE CLAIM IS: i. A chemical treatment technology that has been innovated to bind and stabilize the leachable lead in hazardous solid wastes (D008, lead wastes) under substantially dry to moist conditions ranging in moisture from about 10% to about 40%. This treatment technology currently being commercialized under the trademark, "MAECTITETreatment Process" consists, of two steps: Step One (I) consists of mixing the contaminated soi! or solid waste materials with a solid gypsum powder, chemically called as calcium sulfate dihydrate, or CaSO4.2H20. For maximum effectiveness, the gypsum powder must be at least 95% finer that an i00 mesh size and 100% finer than a 20 mesh size. Coverage of the waste particles and aggregates with gypsum powder during mixing operations must be as uniform and homogeneous as technically

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practical. The physical contact allows chemical reaction of calcium sulfate with a large portion of the leachable lead in the D008 waste materialsand transforms it into a substantially insoluble, stable, and non-leachable form. Step Two (II) comprises the blending of gypsum-amended soils and waste materials with a phosphate reagent, preferably phosphoric acid solution, for ~a period of time sufficient to react with the remaining portion of the leachable lead in the contaminated soil or solid waste materials, and to transform it into a stable, insoluble, and non-leachable form. Both Steps One (I) and Two (If) of the MAECTITE- Treatment Process provide Ca+2, H30+,SO~2 and PO~3 ions essential for rapid stabilization and complete immobilization or fixation of lead in solid wastes to pass USEPA criteria for TCLP lead. 2. The treatment technology according to claim 1 wherein the amount of gypsum added during Step One (I) of the MAECTITE~ Treatment. Process ranges from nothing up to 25% of the waste material by weight. Waste conditioning and uniform coating or dry coverage of waste particles and aggregates with calcium sulfate dihydrate or gypsum powder is an essential step in lead fixation and solid material handling over the conveyor belts just prior to Step Two (iI) of the MAECTITE~ Treatment Process. If the waste contains both calcium and sulfate in sufficient amount, no additional amount of gypsum may be needed. The amount of phosphoric acid treatment during Step Two (II) of the MAECTITE- Treatment Process ranges up to 20% of lead-toxic weight depending on the waste characteristics, leachable lead content, total lead and various forms of lead, buffering capacity and reaction, and waste physicochemical composition. The liquid phosphoric acid is dissolved in water in amounts ranging from about 2% to ¯about 75% prior to application on gypsum-amended waste material and is maintained at temperatures above 30% F to prevent its gelling and thereby, allowing the handling of the phosphoric acid solution as a liquid ~eagent. 3. The process of lead-fixation according to claim 1 and 2 wherein the gypsum powder is substituted in equivalent amounts by

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sulfuric acid and lime, alum, and/or other forms of sulfate and calcium sources in liquid.~ or powder form. Also wherein, the phosphoric acid may be substituted by TSP (trisodium phosphate), potassium phosphates, super phosphate and/or other salts of phosphates in dosage equivalent to those prescribed in claim 2 for lead fixation in solid wastes. 4. The treatment technology according to claim 1 wherein a portion of leachable lead is converted within 4 hours to (a) synthetic hard-minerals species selected from the group consisting of anglesite and calcium-substituted aglesites; (b) superhard rock phosphate minerals including calcium-substituted hydroxy lead apatites, pyromorphites and calcium-substituted pyromorphites; and (c) mixed minerals of phosphate sulfate with Various combinations of calcium and lead. The MAECTIT~- Treatment Process is associated with decomposition of carbonates and bicarbonates including the destruction of cerussites and hydroxy-cerusittes present in certain lead-contaminated soils and solid wastes. 5. The treatment technology according to claim 4 wherein the curing time needed to stabilize and fix the leachable lead in solid waste takes approximately 4 hours. Although further drying of the ¯ treated and cured waste may take 2 to 3~ days in a well-vent~lated building, the development, and growth of mixed calcium/lead sulfate/phosphate minerals may continue for indefinite geQlogic periods. 6. A treatment technology according to Claims 1 through 4, wherein the waste volume is decreased due to MAECTITE~ Treatment Process. Although the volume reductions of the order of 21.4% to 36.4% have been noted for the solid wastes cited in the examples, the range will vary and broaden depending upon the initia! Waste characteristics and amount of treatment chemicals needed for the MAECTITE- Process.

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ABSTRACT A twoLstep treatment technology for treating lead-toxic soils and solid waste materials (USEPA/RCRA and CERCLA D008 waste) has been innovated to stabilize and immobilize the leachable lead and thereby comply with the USEPA land ban regulations that require TCLP lead (USEPA Method 1311) levels below 5 milligrams per liter in the leachate or extraction fluid. The first step of MAECTITE- Treatment Process comprises a uniform and thorough mixing of solid gypsum powder with the leadtoxic solid waste which leads to synthesis of a substantially insoluble lead sulfate and calcium, substituted lead sulfate minerals that develop into anglesite and calcium-anglesite crystals over time. The second step comprises the blending of gypsum-amended waste with a phosphate supplying reagent, particularly phosphoric acid solution in water at temperatures greater than 30%F. Chemical reactions due to this step. synthesize substantially insoluble phosphate mineral species of the apatite and pyromorphite families. Both steps create an excess of Ca+2, S04-2, H30+ and P04-3 ions for the fixation and stabilization of leachable lead in the .solid wastes. This treatment.technology originally deve!oped on a bench scale, has been commercialized on a full scale under the trademark, "MAECTITE- Treatment Process" The curing time for the treatment process is approximately 4 hours after both Steps have been completed. The novelties of the MAECTITE~ treatment t~chnology are that: (i) it fixates and stabilizes TCLP-lead completely and irreversibly meeting the USEPA regulatory threshold and thereby decreasing the imminent risk to human health and environment, (2) it generates an end product that has been decharacterized for lead toxicity and no other byproduct or wastewater stream is generated during or after the MAECTITE~ Treatment Process, (3) it decreases the waste volume significantly and cuts down internment costs eventually, (4) it is univers~l in its application to a wide variety Qf lead-toxic solid (5) it works under a wide range of ambient wastes and soils, DG0191 T-X006 28

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pressure, humidity with exception of rain, and temperature preferably above 30 F, below which phosphoric acid begins to gel creating problems of material handling, (6) it is fairly rapid with a curing time of less than 5 hours, and (7) it is cost-effective and commercially available, flexible and economically scalable, mobile and readily transferable from one site to another containing leadtoxic wastes.

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66338-3
ProposedNew Claim

--21. A treatment process for treating lead-toxic solid wastes to stabilize leachable lead contained therein, said process comprising the steps of: mixing a solid waste containing leachable lead with one of a sulfate compound having at least one sulfate ion and a phosphate reagent having at least one phosphate ion, said sulfate ion or said phosphate ion for reacting with said leachable lead to produce a first mixture, said first mixture containing a substantially insoluble lead compound or mineral species; and mixing said first mixture with the other of said sulfate compound and phosphate reagent for reacting with leachable lead remaining in said first mixture to produce a second mixture, said second mixture containing a substantially insoluble lead compound or mineral species; curing said second mixture for a period such that the material so treated is substantially solid in format the end of curing, the material passes the paint filter test, TCLP lead levels are decreased below 5.0 mg/l, the volume of said solid waste is reduced as a result of treatment and curing, and no secondarywaste streams are generated.--

DG0193