Free Motion for Summary Judgment - District Court of Federal Claims - federal

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Exhibit 10

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United States Patent
O'Hara et al.
[~4]
IMMOBILIZATION OF LEAD AND CADMIUM IN SOLID RESIDUES FROM THE COMBUSTION OF REFUSE USING .LIME AND PHOSPHATE

[11] Patent Number: 4,737,356 * Apr. 12, 1988 [45] Date of Patent:
[56]
References Cited U.S. PATENT DOCUMENTS 3,676,165 7/1972 Sehneider.Arnoldi ............. 106/I 17 4,049,462 9/1977 C0eazza .................: ............ 106/118 4, t13,51M 9/1978 Chan et al ........................... 252/628 4,!24,405 11/1978 Quienot ............................... 210/912 4,354,876 10/1982 Webster .............................. 106/118 4,375,986 3/1983 Piehat .................................. 106/118 4,377,483 3/1983 Yamashita et al .................. 210/912 4,384,923 5/1983 Hillekamp ............................. 201/21 4,437,666 2/1984 Frey et al ............................ 106/900 4,496,267 1/1985 Gnaedinger ......................... 106/118 4,671,882 6/1987 Douglas et al ........................ 423/55

[75] Inventors: Mark J. O'Hara, Mr. Prospect;
[73] Assignee: [ * ] Notice:

Marion R. Surgi, Evanston, both of Ill. Wheelabrator Environmental Systems Inc., Hampton, N.H.

The portion of the term of this patent subsequent to Feb. 9, 1999 has been disclaimed.

[21] Appl. No.: 935,899 [22] Filed: Nov. 28, 1986
Related U.S. Application Data Continuation-in-part of Ser. No. 799,236, Nov. 18, 1985, abandoned.

FOREIGN PATENT DOCUMENTS 34389 8/1981 United Kingdom .................... 75/25 Primary Examiner--Gary 'P. Straub Attorney, Ageng or Firm--Thomas K. McBride; John F. Spears, Jr.; Eugene I. Snyder

[63]

[ST]

A~STRACT

Solid residues arising from the burning of solid wastes have lead and cadmium sufficiently insolubilized to pass [51] Int. C1.4 ......................... F233 1/00; EOIC 19/26; the EPA toxicity test only where the pH in the EPA C01G 11/00; C22B 1/243 [52] U.S. Ca ..................................... 423/659; 110/344;test is between 7.5 and 12.0. Addition of water soluble phosphate, especially phosphoric acid, increases the 75/25; 210/912; 210/901; 404/129; 423/92; immobilization of lead and cadmium so as to make such 423/I01 [58] Field of Search ............................... 252/626, 628; residues in e0mplianee with the toxicity tests over a substantially broader pH range. 204/DIG. 13; 423/92, 101, 659; 75/2, 24, 71, 25, 77; !06/1171 118; 210/901, 907, 908, 9!2; 110/344; 404/129 17 Claims, 1 Drawing Sheet

t~ 11 to 9

2

~/

6

6

IO I~ 14 16 19 ~0

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~U.S. Patent

Apr. 12, 1988

4,737,356

14

13 12 II I0 9 8

oo=~c--oo~°o~ i

-7-o

6 5 4
0 2 4 6 8 I0 12 14 16 18 20

Bottom Ash: Fly Ash Rotlo

Relotionship Between pH, Bottom Ash: Fly Ash Rotio ' And FGSP: Fly Ash RoNo

Symbol 0 "---0 D --~-. O 6 ---- 6 V ~V

¯ FGSP BO 67 50 30

¯ Fly Ash 20 33 50 70

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4,737,356

specified by the EPA. The invention herein is a solution IMB'IOBILIZATION OF LEAD AND CADMIUM IN to this problem. More specifically it is a method of SOLID RESIDUES FROM THE COMBUS~ON OF treating dry, solid residues, espeeiaily fly ash, and mixREFUSE USING LIME AND PHOSPHATE ' tures containing fly ash, so as to reduce the amounts of 5 cadmium and lead leached from such residues to a level CROSS REFERENCE TO RELATED below the toxic level specified by the EPA. Stated APPLICATION differently, the invention herein is a method of immobiThis application is a continuation-in-part'of eopendlizing, or insolubilizing, cadmium and lead in solid ing application Set. No. 799,236 Fried Nov. 18, 1985, waste, especially over a wide pH range. The method is now abandoned, all of which is incorporated by refer- 10 convenient, quite simple, very efficient, applicable over a wide pH range, and relatively low cost. The method once. is, therefore, commercially extraordinarily attractive as BACKGROUND OF THE INVENTION well as b.eing environmentally beneficial. An increasing world population leads to a continually The problem we have addressed is not new; only our increasing amount of refuse. Additionally, an increased 15 solution to this problem is new. Prior solutions have level of civilization appears to generate an increased relied on transforming metal-laden ash into a solid, amount of refuse on a per capita basis. Both factors in ' hardened, often brick-like consistency to immobilize combination lead to mounting pressure to devise mothlead and cadmium. Such solutions are based on produeods of waste disposal which are economically, energetiing a product largely impermeable to water, thereby 20 reducing, if not eliminating, metal transport by diffueally, and environmentally sound. In recent years, especially in urban areas, the in- sion. In contrast, our invention retains the powdery creased demand for usable land and other concerns has ¯ (particulate) nature of the ash.containing residues while caused one to turn from a landFril as the major mode of immobilizing lead and eadrninm; the treated residue refuse disposal ~o other options, especially the use of remains a particulate, non-hardened solid which does raw refuse as an energy source. One variant of the latter 25 not harden to a bri¢k-like consistency and this characis the mass burning approach, where all the refuse in its teristie serves as a distinguishing feature of our invenraw state is burned without any preliminary treatment tion. such as separating the noncombustible from eombustiThe precipitation of heavy metals, including cadble material. Quite briefly, in this method raw garbage is ¯ dumped into storage where it.is homogenized and dried 30 mium and lead, at high pH is a well-known analytical the to some degree. Refuse from the storage area is fed into teelmique, and the use of lime as solidbasic agent is a common procedure. For example, wastes containa combustion zone where the heated gases often are ing cadmium and lead were treated with 3-15% calused to genei:ate steam. Flue gases then pass from ~he cium hydroxide and/or magnesium sulfate, the pH was combustion zone to a separation zone, often an electrostatic precipitator, where dust and ash .are removed. 35 adjusted to 8-10.5, and the solid coated with asphalt to The ash so removed from the flue gas, called fly ash, is prevent the leaching of cadmium and lead. Chemical then mixed with the ash collected in the combustion Abstracts, 92; 1854!4d. The preceding method is a mixzone, called bottom ash, and the combined ash used for ture of coagulation-floeculation followed by encapsulation in a hydrophobie, petroleum-based solid. landfill, in road construction, and so forth, It is wel! "known that some of the more volatile eom-40 In U.S. Pat. No. 4,049,462 Cgeozzo treated industrial pounds of certain metals tend to accumulate in the fly desulfurization residues resulting from removal of sulfur ash. Especially where the latter is to be used as landfill, oxides from effluent gas with alkaline calcination stack leaching of.toxic me.tais, aspeeially cadmium and lead, dust and water under acidic conditions to form a solidi hardened, !each-resistant product. The patentee recogconstitutes a potential hazard to the ecosystem, for example, both surface water supplies and aquifers. The 45 nized that the cement-like product resulted from the Environmental Protection Agency (EPA) has'promul- reaction of eaieium oxide and silicate in the stack dust gated a procedure to determine the toxicity of solid with acid anions, whose nature was not significant so long as the mass reacted under acidic conditions to wastes, and where residues exceed the toxicity as stated in the Federal Register Code 40, No. 26124, the waste is provide a hardenable mass which upon drying became classified as a hazardous waste requiring control under 50 cementitious solid. the Hazardous Waste Management System. A recent Piehat describes a process to transform strongly report prepared for the Office of Solid Waste, U.S. acidic liquid wastes containing relatively high metals Environmental Protection Agency, whieh was alimited content, including cadmium, into solid materials by mixing the wastes with coal fly ash, adjusting the pH to survey of several kinds of solid waste, seems to suggest that levels of cadmium and lead in fly ash pose perhaps 55 about 7, adding a lime-containing substance and a the most serious environmental ~hreat, and that such fly binder, such as Portland cement, with the mixture setring to a petrified mass; U.S. Pat. No. 4,375,986. As the ash alone would need to be treated as a hazardous waste; EP Toxicity Test Results on Residues from patentee recognized, coal ash is pozzolanic, i.e., in the Eight Resource Recovery Facilities, SYSTECH Cor- presence of lime it agglomerates into a hard, compact, potation, February, 1981. 60 mortar type product. Clearly, Pichat's invention deThe environmental hazard of fly ash containing scribes a method to treat acidic liquid wastes and uses amounts of cadmium and lead greater than the toxin coal fly ash as an additive. The patentee also recognizes levels specified by the EPA is somewhat diminished by that coal fly ash does not contain sufficient amounts of mixing such ash with heavy ash, such that the resulting Pb and Cd to present an environmental concern. A1landfill mixture is within the toxic levels for the cited though Sehneider-Arnoldi et al. in U.S. Pat. No. 65 metals. Nonetheless, it is highly desirable to reduce the 3,676,165 teach that phosphorous furnace slag can. be amount of cadmium and lead leached from fly ash and substituted for lime as a binder, and that such slag conother solid waste to an amount below the toxic levels tains phosphorous compounds in the amount of

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0.5-2.0% reported as P205, the slag .i~ a hard vitreous DESCRIPTION OF THE FIGURE mass which fails to furnish soluble phosphate, an essenThe figure shows the final pH of the extract in an tial element of our invention. In fact, such slag contains EPA test of various solid residues from the burning of phosphorous chiefly as calcium phosphate, which we show to be inoperative in immobilizing lead and cad- 5 solid wastes. The cross-hatched part represents the sole region where the EPA Toxicity limits for both lead and In all instances reported in which a cement-like mate- eadminm are met in the residues. rial is fabricated from fly ash, the inventors use coal fly THE PROBLEM ash which due to chemical composition, surface compoFlue gas resulting from the combustion of refuse sition and morphology, and size distribution is pozzola- 10 nic. However, for these same reasons, incinerator fly often is passgd through lime to remove such materials as hydrogen chloride, sulfur dioxide, sulfuric acid, carbon ash is not pozzolanic and cannot form a stable cement in dioxide, nitrogen oxide, and other acidic compounds the absence of ordinary portland cement. The invention normally found in flue gas to afford a solid called flue described here does not require ordinary portland cement and neither requires nor utiliZes solidification or 15 gas scrubber product. Fly ash also frequently is mixed with lime, in part to immobilize (insolubilize) heavy agglomeration for its successful application. Methods found lead and applicable to agglomeration or fixation of coal fly ashes metals flue gastherein, includingis availablecadmium. scrubber product it is used are simply not readily applicable to incinerator fly Whereas the sole source of lime or as lime make-up for either ashes. treatment of the fly ash. The gas scrubA base course for pavement construction can be 20 ber product mixture is thenfly ash-lime/fluebottom ash admixed with made from incinerator ash reacted with lime and water for uses as mentioned above. However, the ratio of prior to compaction; U.S. Pat. No. 4,496,267, European bottom ash to fly ash varies considerably, as does the Pat. No. 34-389, directed toward the agglomeration of ratio of flue gas scrubber product to fly ash and the coal fly ash into pellets, discloses some phosphorous extent to which the lime in flue gas scrubcompounds in the ash and "reports the total phosphorous 25 ber product, according to is neutralized refuse, the operthe source of content as P205, but as with Sehneider-Arnoldi. et al. ational characteristics of the plant, and so forth. The this phosphorous source does not furnish soluble phosresulting mixture containing flue gas scrubber product, phates. We have discovered a method of immobilizing lead 30 fly ash, and bottom ash has an alkalinityawhich can vary cbnsiderably and additionally displays broadly vary"" and cadmium in refuse-to-energy combustion residues ing buffering power. As the data of Example 1 show, '": effective over a broad pH range to reduce the leaching such mixtures often fail the EPA test for lead and/or ~ of the aforementioned heavy metals to a level below the cadmium, essentially because cadmium precipitates at a maximum dictated by the EPA. Quite simply, the pH greater than about 7.5 but lead, being amphoteric, method involves treatment of the solid residues with 35 begins to redissolve at a pH greater than about 12. Conlime followed by addition of a water soluble phosphate. sequently, only in those mixtures whose final pH after Using this method levels of lead and Cadmium are re- extrantion in the EPA test (vide infra) is between about duced to less than 5 and l ppm, respectively. It is also 7.5 and about 12.0 are lead and cadmium immobilized desirable to immobilize the toxic metals to pass the sufficiently well for the mixture to be within the stated : regulatory limits with a typical acid rain or water ex- 40 regulatory limits. '". traction. This requires an immobilization system which The practical aspects of refuse burning dictate a is effective over the entire pH range above about 5.0; broad range of flue gas scrubber product-fly ash-bottom "": the method we have discovered meets this requirement. ash solid waste mixtures with an accompanying range Our method does not change the particulate nature of of alkalinity. The regulatory aspects of solid wastes the untreated solid residue; it generates no cement-like 45 dictate that leaching of lead be limited to less than 5 mass. Our method does not generate calcium phosphate ppm and leaching of cadmium to be no more than 1 as the metal binder; substitution of calcium phosphate ppm. The technical aspects of the aforementioned solid for our soluble phosphate fails to immobilize lead and waste mixtures demonstrate an enormous variation in cadmium. Whatever may be the detailed mechanism of the leaching of lead and cadmium depending upon pH. metals immobilization in our method, it appears that our 50The problem, simply stated, is to make the practical, immobilizing materials of lime and soluble phosphate regulatory, and technical aspects compatible. That is, remain quiescent and inactive in the dry solid residue, what can be done to immobilize lead and cadmium in the broad range of solid waste mixtures of flue gas but when water--the extractant--perfus.es through the solid the immobilizers raise a barrier to dissolution and- scrubber product-fly ash-bottom ash normally pro/or diffusion of the metals into the liquid phase. 55 duced in refuse burning plants so as to conform to EPA regulations? ' SUMMARY OF THE INVENTION THE SOLUTION The purpose of this invention is to increase the immobilization of lead and cadmium in solid residues from The solution, simpl~ stated, is to add water soluble combustion plants. In one embodiment fly ash is treated 60 phosphate. Stated somewhat more extensively, we have with lime, mixed with bottom ash, and the resulting discovered that addition of water soluble phosphate to mixture treated with a source of water soluble phosflue gas .scrubber product-fly ash-bottom ash solid phate. In a more specific embodiment the lime origi. waste residues of a broad compositional range insolubihates from flue gas scrubber product. In a still more lizes lead and cadmium to an~ extent as to make the specific embodiment the water soluble phosphate is 65 residue in total compliance with EPA regulations, notwithstanding a broad variation in alkalinity of such added in an amount from about 1% to about 8% by weight of the ash-lime mixture. Other embodiments will residues. The solution is remarkable in that it cures a vexing problem with an extraordinarily simple treatbecome apparent from the following description.

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merit. The remainder of this exposition is devoted to a fly ash. The lime-fly ash-bottom ash mixture is then treated with a source of water soluble phosphate to more complete description of our invention, Even more generally, our invention takes a particu- complete the immobilization of lead and eadminm. It is, ¯ late (powdery or granular) dry solid residue arising perhaps, most convenient merely to spray the mixture from the burning of solid waste in a mass burning plant, 5 with the phosphate source and then agitate the mixture .and from which lead and cadmium are leached at levels to ensure the dispersion of phosphate. However, merely of more than 5 and 1 ppm, resp., and treats the residue dispersing a good source of water soluble phosphate with lime, especially that arising from a flue gas .scrub- through the mixture also may be performed, although ber product of a mass burning plant, and one or more not neees'safily with equivalent results. water soluble phosphates, to obtain a particulate residue 10 ' Any convenient source of water soluble phosphate which maintains its particulate nature but from which may be used in the practice of this invention. By a water leaching of the aforementioned is below the stated lev- soluble phosphate is meant a phosphate soluble in water els. at about 20* C. at least to the extent of about five weight-volume percent. Phosphoric including .. DESCRIPTION OF THE INVENTION 15 orthophosphofic .aci.d, hypophosphorlcacids,metaphosacid, The solids being treated in our invention are residues phode acid and pyrophosphodc acid, can be converesulting from the burning of solid wastes, generally in niently used in this invention. Sometimes it is desirable commercial mass burning facilities, and from which to use a less acidic source of phosphate, and in fact it is cadmium and/or lead are leached at levels in excess of essential that the phosphate source and use level be such 1 and 5 ppm, resp., as determined by an EPA test. Ini-20 that a substantial part of the lime is not neutralized. tially such solids are a free flowing particulate mass, and Other less acidic sources of phosphates include phosa virtue of our invention is that after treatme~ft to immo. phate, monohydrogen phosphate, and dihydrogen bilize lead and cadmium the solids remain a free flowing phosphate salts, such as tdsodium phosphate, disodium particulate mass, even after water percolation, and hydrogen phosphate, sodium dihydrogen phosphate, maintain this characteristic. The solids treated generally 25 potassium phosphate, dipotassium hydrogen phosphate, are fly ash, in whole or in part, since lead and cadmium potassium dihydrogen phosphate, lithium phosphate, tend to be concentrated in the fly ash. In one variant of lithium hydrogen phosphate, and lithium dihydrogen our invention the solid residue treated is a mixture of fly phosphate. Quite generally, the salts of the various ash and bottom ash, usually containing between about 2 phosphoric acids may be utilized, and among these the and 25% by weight of fly ash, even more often between 30 alkali metal salts are most frequently employed. 5 and 20% fly ash. The following description of our The amount of water soluble phosphate source to be invention is couched in terms of the fly ash first being added to the solid residue to ensure adequate immobilitreated with lime or a time source, with this mixture zation of lead and cadmium will depend on such varisubsequently being combined with bottom ash prior to ables as alkalinity of the solid residue, its buffering capaaddition 0fa water soluble phosphate. This corresponds 35 bility, the amount of lead and cadmium initially present, to the most convenient way of ca .rr3dng out our invert- and so on. It has been found generally that an amount of tion, but the choice of this particular description is for the water soluble phosphate source equivalent to beexpository convenience only. It is to be clearly undertween about 1% and about 8% by weight of phosphoric stood that variants such as treatment of fly ash alone acid, HaPO4, based on total solid residue is sufficient, with lime and phosphate prior to mixing with bottom40 but isnot intended to preclude yet higher usage of an ash, or treating a mixture of fly and bottom ash with water soluble phosphate if needed. lime and phosphate, are intended to be subsumed under The examples below are merely illustrative of this our invention as claimed, as are other permutations invention and are not intended to limit it thereby in any which one skilled in the art will recognize, way. Using fly ash as an example of the solid residue t0 be 45 The following procedure, based on an EPA method treated, the fly ash is mixed with lime. By lime we mean as described in the Federal Register V. 45, No. 98, May calcium oxide (dry lime), calcium hydroxide (hydrated 19, 1980, pp 33099 et ff., was used to screen various lime), a lime source or any mixture thereof. Where flue methods. The EPA test was modified only as to scale, gas is scrubbed with lime, the flue gas scrubber product i.e., the test used by us was a scaled-down version of the ('FGSP) may be either the sole source of lime or may be 0 standard EPA procedure. Experiments were performed 5 used only in part as the lime source. In addition to conby mixing an immobilizing m~teriat with I0 g dry fly taining calcium hydroxide, the FGSP typically will ash in a 500 ml Erlenmeyer flask. Water (160 ml) was contain such materials as calcium sulfate, calcium sul- added and the mixture was agitated thoroughly on a rite, calcium chloride, and calcium carbonate. The per- wrist action shaker. After one hour the pH was recentage of calcium hydroxide in the FGSP is itself sub-55 corded and adjusted to 5.04-0.2 b~, addition of 0.5N ject to broad variation, and the amount of FGSP used acetic acid. Agitation was continued with. hourly adwill depend ha part on the amount of calcium hydroxide justment of pH to 5.0-1-0.2 until a stable pH of 5.0 was present. In the successful practice of this invention, lime reached or the maximum allowed amount (40 ml) of or FGSP will be added to fly ash in ar! amount from 1 0.5N acetic acid was used. The total mixing time on the to about 25 parts by weight of lime, based on its calcium60 standard test was 24 hours. Solids were separated on a hydroxide content, per 5 parts by weight of fly ash. vacuum Millipore filter XX!004700 using an AP type ' The fly ash-lime mixture is then mixed with bottom prefflter and an HA type 0.45 micron fine filter. If less ash in the. normal, commercial practice of this inven- than 40 ml acetic acid was used, the final volume was tion. The relative amounts of these two components adjusted with water in an amount determined by the often is expressed as a ratio of bottom ash to fly ash, and 65 following equation: normally varies from perhaps 3:1 to 49:1, i.e., the mixture contains from about 2 to about 25% by weight fly v=(20)(w)ash, most often being in the range of 5-20% by weight

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where: V=ml distilled water to be added. W=' weight in g of solid charged to extractor A-ml of 0.SN acetic acid added during extraction Ultrapure concentrated nitric acid in an amount of 1 ml per 100 ml leachate was added.after filtration to stabilize the solution, The modified EPA toxicity reference test itself is carried out without the addition of immobilizing material. Levels of cadmium and lead in leachate were

8
EXAMPLE 3

In this example solid residues of varying bottom ash:fly ash and FGSP:fly ash ratios were subjected to the EP toxicity test with and without the addition of 4.25% phosphoric acid; The following table again demonstrates the efficacy of phosphoric acid in immobilizing both lead and cadmium over the quite broad pH range from 5.2 to 12.6.
TABLE 2

Effect of 4,25% H3PO4 With Various Bottom Ash:Fly Ash and FGSP:FIy Ash Ratios 4:1 4:1 Bottom Ash;Fly Ash 7:1 7:1 7:1 7:1 9:7 9;7 3:7 2:1 2:1 hl hl FGSP:Fly Ash 4:1 4:1 3:7 4,25 -4.25 -4.25 -4.25 -% H3PO4 EP Toxiaity Test 7.07 12.60 12.67 12.60 12.68 Initial pH 12.63 12.60 -11.00 .Final pH 12.43 12.60 5.60 5.18 12.43 10.19 12.60 Extract mg/L 0.31 13.5 0.062 14.0 ' 0.063 Pb 17.0 1.2' 12.0 0.01 0.01 0.090 0.01 2,82 0.70 0.01 0.01 Cd

determined by atomic absorption spectroscopy. The bottom ash-fly ash mixtures used inour studies EXAMPLE 4 contained about 0.5 weight percent phosphorous, 25 In this example an ash composite was extracted with which is equivalent to 1.1% reported as P205. This synthetic acid rain. A blend of nitrates, sulfates, and shows that the phosphorous-containing m. aterials preschlorides was made to simulate acid rain representative ent in the ash residue is not a source of soluble phosof the Northeastern U.S. The following compounds phate necessary for immobilization. dissolved 30 werean acid rainin a total solution of four liters to preEXAMPLE 1 pare concentrate. Solid residues exemplifying .a broad spectrum of flue gas scrubber product-fly ash-bottom ash compositions g Compound were tested for lead and cadmium content using the 0.I 150 NaNO3 EPA test as described above. The FGSP typically had 35 0.2196 KNO3 0.0648 a calcium hydroxide content between 40% and 60%. NH4NO~ 0.0821 MgCI2' The final pH after extraction in the EPA test is plotted . 0.1755 H2S 04 for various compositions in the figure. It was observed 0,1057 CaSO4 that the EPA limits for Pb wei'e met only within the pH. range 6.7-12.0, and the EPA limits for Cd were met 40 The pH of the concentrated solution was 2.88. A only at a pH above 7.5. As can be seen from that figure,. only a limited number of sue.h compositions afforded a solution was prepared for use in the acid rain extraction final pH between 7.5 and 12.0, the range within which tests by diluting this mixture by a factor of 10; the resulting pH was 3.93. This dilute solution, which should be the EPA test for both lead and cadmium are met. 45 representative of a typical acid rain, was used as a reEXAMPLE 2 placement for 0.5N acetic acid to test blends of FGSP, fly ash, and bottom ash. Otherwise, the extraction was Solid residues were prepared using a ratio of bottom identical to the EP Toxicity Test. As the data of Table ash to fly ash of 19:1. To this was added flue gas scrubber product containing about 57% free calcium hydrox- 3 demonstrate phosphoric acid addition again was q.uite ide in different weight ratios. The EP toxicity test was 50 effective in reducing the levels of lead leached from
such a composite. then run on this mixture of FGSP-fly ash-bottom ash as well as one containing 4.25% phosphoric acid. The TABLE 3 results are tabulated below. Acid Rain. Extraction of Ash Composite; Effect of 4.2% H3PO4 TABLE 1 55 FGSP:Fly Ash hl hl 4:1 4:1 3:7 3:7
3:7 4.25 5.43 5,11 0.1 0.29 N % H3PO4 Acid Rain Extraction Initial pH 12.58 12.66 Final pH Extract m~/L, , 2.8 60 Pb 0.01 Cd 4.25 8,10 7.29 0.1 0.01 -4.25 N 12.70 12.73 3,5 0,01 12,67 12.54 12,78 12.50 0.71 0.01 1.5 0.01

Effect of 4.25% H]PO4 in Modified EP Toxinity Test FGSP:Fly Ash 4:1 4:1 hi hl 3:7 0 4.25 0 4.25 0 % H3PO4 EP Toxicity Test 7.40 12.46 Initial pH 12.62 t2,24 -Final pH 12.38 10.21 5.38 5.05 4.99 Extract mg/L 0.23 8.46 Pb 5.6 0,1 11.8 0.014 0,01 1,27 0.45 1.33 Cd

4.25 5.47 5.79 0.1 0.063

EXAMPLE 5

As can be seen, the EPA test limits for lead and cad- 65 Various ash composites were extracted with wayer mium are met over the pH range from 5.05 to 10.2, . alone to determine the effect of added phosphate on whereas in the absence of phosphate acceptable limits of heavy metal leaching. The experiments were performed in a 500 ml Erlenmeyer flask with 10 g of a FGSP:fly leaching were not met.

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ash blend and 200 ml H20 with agitation by a wrist action shaker for 24 hours.
TABLE 4 H20 Extraction of Ash Composite: Effe¢i of 4.2%'H3PO4 FGSP:Fly Ash 1:1 1:1 "2:1 2~1 4:1 0 4.25 0 4.25 0 % H3PO4 H20 Extraction test Initial pH 12.42 7.30 12.60 11.[18 12.61 Final pH 12.70 8.07 12.66 10.48 12.67 Extract mg,/L Pb 14.9 0.1 6.5 0.19 5.8 0~01 0.01 0.01 0.02 0.01 Cd 5

4:1 4.25 12.51 12.57 0.93 0.01

I0

As in the prior examples, addition of phosph0de acid substantially reduces the amount of lead leached under 15 the conditions of this test. . Lcvela EXAMPLE 6 Composites containing a !9: I ratio of bottom ash:fly ash were tested with either phosph0de acid or disodium 20 hydrogen phosphate, Na2HPO4 as the source of water soluble phosphate. In both cases the solid residue easily met the EPA toxicity test. TABLE 5 25 Comparison of H3PO4 With Na2HPO4 Modified EP Test FGSP:FIy Ash 4tl 4d ltl I:1 3:7 3:7 4.25 -% H3PO4 4.25 -4,25 -2.0 -5;0 -- 5.0 -5.0 % Na~HPO4 EP Toxicity Test Initial pH 12.70 12.69 6.27 12,30 5.50 11.88 30 Final pH 6,50 11,62 5.11 5.18 .5.07 5.10 Extract mg/L Pb 0,1 0,075 0.1 0.24 0.1 0.15 Cd 0,036 0.015 0,34 0.33 0.19 0.50
35

temporary, and that the lead and cadmium in the treated material remained immobilized. A mixture of fly ash and flue gas scrubber product (Ca. 30:70) was sprayed with water containing a variety of phosphates to afford a mixture with 20% moisture and containing various levels of phosphates, reported as weight percent phosphorous. (A level of 2.6 weight percent phosphorous is equivalent to 8.0 weight percent phosphate as phosphoric acid.) This mixture was aged in a closed bottle and subjected to the EPA leach test at interVals for lead and cadmium. In all cases the leachate contained <0.01 ppm cadmium. Results are reported in Table 7. TABLE 7
Stability of Immobilization Phosphate Lead in Leaehate Source Day Level" 0 44 Na2HPO4 0 3.6 4 3.1 7 3.0 28 2.1 85% H3PO4 0 3.9 4 2.7 Na4P2OT. 10 H20 0 6.0 5 3.2 b Na4P2OT. 10 H20 0 6.5 5 5.1 b NasP3OIo 0 6.8 3 5.3 0 7,2 (NaPO3)6 NaH2PO4.2 H20 NasPaOto Na2HPO4 NasP3010--85% H3PO4 (I:1) 0 5 0 5 0 4 0 5

10

none 2.6

5

7.5
5.7 5.5 4.5 4,7 7.9 6.5 4.4 6.4

EXAMPLE 7
A composite containing a ratio of bottom ash:fly ash ..... of 19:1 with varying ratios of FGSP:fly ash were tested using from 1% to 4.25% phosphoric acid. As can be 40 " seen, even 1% phosphoric acid was generally effective in reducing leaching of lead and eadminm to an acceptable level except with a FGSP:fly ash ratio of 1:!.

qn wt. % budded as solid, water st~bsequently sprayed on to 20% moisture level.

EXAMPLE 9 A 19:1 bottom ash-fly ash composition was mixed with an equal amount of flue gas Scrubber product and treated with various acids and the anions of these acids.

TABLE 6 Effect of H3PO4 Content Immobilization of Pb and Cd in FGSP:FIy Ash:Bottom Ash Blends 9.5 g Bottom Ash + 0rSg Fly Ash FGSP:Fly Ash 4:1 4:1 4:1 4:1 I:1 1:1 I:1 1:1 3:7 0 4.25 2.1 1.0 0 4.25 2.1 1.0 0 % H3PO4 EP Tokielty Test 7.40 12,25 12.42 12,46 Inidal f~H 12,62 12.24 12.60 12.64 -Final pH 12,38 10.21 12,45 12.24 5.38 5.05 5.14 5.08 4,99 Extract mL/~ Pb 5,6 0.1 0.46 0,36 11.8 0,23 0.1 0.49 8.46 Cd 0.014 0.01 0.01 0.01 1.27 0.45 0.51 1.2 1.33

3:7 3:7 4.25 2.1 5.43 5.11 0.1 0.29

3:7 1.0

7.03 12.04 5.16 5.11 0.1 0.24 0.38 0.83

EXAMPLE 8 The following study was performed to show that the initial leaching results in the EPA test were not merely

The data in Table 8 shows unequivocally that phosphate is unique; neither sulfuric nor nitric acids immobilize lead and cadmium, nor do their salts.
TABLE 8 Effectiveness of Various Acids and Their Salts in Immobilization None H3PO¢ H2SO4 HNO3 Na2HPO4 4.3 4.3 4.3 3.5 12.16 7.40 10.48 11.88 12.30

Addend Concentration (meq/g residue) EP Toxicity Test initial pH.

Na2SO4 3.5 12.21

NAN03 3,5 12.14

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11
TABLE 8-continued
Final pH Extract mg/ml. Pb Cd

12

Effectiveness of V~Hous Acids and Their Salts in Immobilization 5.38 5.05 5.01 5.18 5.18 11.8 1.27 0.23 0.45 4.7 1.2 6.6 1.39 0.24 0.33

5.12 14 0.93

5.21 8.9 0.82

5. flue gas scrubber product of a mass burning facilI0 is theThe method of claim 1 where the free lime source ity. To he ash-flue gas scrubber product .mixture of the 6. The method of claim 1 where the water soluble prior example was added 4.25% by weight phosphoric phosphate is selected from the group consisting of phosacid. This mixture was placed in a column and three phoric acid, polyphosphoric acid, hypophosphorie volumes of water was percolated through the pax'lieu- 15acid~ metaphosphoric acid, and salts thereof. late mass to simulate landfill conditions. The mass was 7. The method of claim 6 where the salts are alkali removed, air dried, and subjected to a particle size dis- metal salts. tribution analysis whose results appear in Table 9. 8. The method of claim 7 where the salt is trisodium TABLE 9 20 phosphate, disodiurh hydrogen phosphate, sodium dihydrogen phosphate, tripotassitun phosphate, dipotassinm Particle Size Distribution of Ash Before hydrogen phosphate, potassium dihydrogen phosphate, and After Immobilization by Phosphate trilithium phosphate, dilithium hydrogen phosphate, Percent of Total Untreated Ash Treated Ash lithium dihydrogen phosphate or mixtures thereof. Particle Size, mm ' 3.7 <0.074 3.9 25 9. The..method of claim li where the water soluble 0.074-0.42 8.2 8.9 phosphate is phosporie acid. 21.3 0.42-2 23.6 10. A method of immobilizing lead and cadmium as a 2-9.5 64.3 66.1 free flowing particulate mass in a free flowing dry partieulate mass of a fly ash and bottom ash mixture where These data show that the partiealate nature of the 30 each said ash results from the incineration of municipal mass remains virtuallyunaffected by the immobilization waste in a mass burning facility comprising contacting the dry ash mixture with at least one water soluble treatment of this invention. phosphate in an amount equivalent to about 1 to about EXAMPLE 11 8 percent by weight of phosphoric .acid based on the The same mixture of fl'y ash and flue gas scrubber total ash mixture in the presence of a free lime source 35 selected from the group consisting of lime, hydrated prodhct as described in Example 8 was treated with 0.6% phosphorous as phosphate from insoluble Ca3(lime, flue gas scrubber products, and combinations thereof, in an amount sufficient to furnish from about 1 PO4)2 and then subjected to the EPA leach test. The leachate had 19 ppm lead, showing that calcium phos- to about 25 parts by weight of calcium hydroxide per 5 phate is ineffective as a phosphate source in the immo. 40 parts by weight of fly ash whereby the leaching of cadmium and lead is reduced to a level no more than 1 bilization of lead by our method. What is claimed is: ppm cadmium and 5 ppm lead as determined in an EPA 1. A method of immobilizing lead and cadmium in a test performed on the resulting treated ash mixture. 11. The method of claim 10 where the dry particulate free flowing particulate dry solid residue which maintains its free flowing particulate nature afterthe immo- ash mixture contains from about 2 to about 25% by 45 weight of fly ash. bilizing treatment, said dry solid residue comprising fly 12. The method of claim 11 where the dry particulate ash and mixtures of fly ash with bottom ash resulting from the .incineration of muuleipal waste, eomprislng ash mixture contains from about 5 to about 20% by contacting the dry solid residue with at least one water weight of fly ash. soluble phosphate in an amount equivalent to about 1 to 50 13. The method of claim 10 where the free lime so.urce is the flue gas scrubber product of a mass burnabout 8% by weight of phosphorle acid based on the total residue in the presence of a free lime source seing facility. 14. The method of claim 10 where the water soluble lected from the group consisting of lime, hydrated lime, phosphate is selected from the group consisting of phosflue gas scrubber product, and combinations thereof, in an amount sufficient to furnish from about 1 to about 25 55 phofie acid, polyphosphorie acid, hypophosphoric parts by weight, calcium hydroxide per 5 parts by acid, metaphosphorie acid, and salts thereof. weight of fly ash whereby the leaching of cadmium and 15. The method of claim 14 where the salts are alkali lead is reduced to a level no more than 1 ppm cadmium metal salts. and 5 ppmlead as determined in an EPA test performed 16. The method of claim 15 where the salt is tfisoon the resulting dry treated residue. dium phosphate, disodium hydrogen phosphate, sodium 2. The method 9f claim 1 where the dry solid residue60 dihydrogen phosphate, tripotassium phosphate, dipotasslum hydrogen phosphate, potassium dihydrogen phoscontains from about 2 to about 25% by weight of fly phate, trilithium phosphate, dilithium hydrogen phosash. 3. The method of claim 1 where the dry solid residue phate, lithium dihydrogen phosphate or mixtures contains from about 5 to about 20% by weight of fly 65 thereof. ash. 17. The method of Claim 14 where the water soluble 4. The method of claim 1 where the dry solid residue phosphate is phosporie acid. is essentially fly ash.
EXAMPLE I0

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UNITED STATES PATENT AND TRADEMARK OFFICE

CERTIFICATE OF CORRECTION
PATENT NO. : 4,737,356 DATED : April 12,.1988 INVENTOR(S): Mark 3 O'Hara and Marion R. Surgi
It is certified that error appears in the above-identified patent and that said Letters Patent is hereby corrected as shown below:

T~tZe page (cover page), in the first column, please delete: "[*] Notice: The portion of the term of. this patent subsequent to Feb. 9, 1999 has been disclaimed."

Signed and Sealed this Third Day of September, 1991
Attest:
HARRY" F. MANBECK, JR.

Attesting Officer

Commissioner of Patents and Trademarks