Stabilizing toxic metal concentrates by using SMITE
Transcript of Stabilizing toxic metal concentrates by using SMITE
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I
Overview
Stabilizing Toxic Metal Concentrates by Using SMITE
Tim White and Irfan Toor
Synthetic mineral immobilization technology is an approach for the treatment of heavy-metal concentrates. Although the notion of using synthetic mineral analogs for the stabilization and consolidation of nuclear waste has been discussed for more than 40 years, its application to inorganic hazardous waste, in general, is only now being realized. The advantage of this technology is that high-waste-Ioaded and high-density waste forms can be fabricated while maintaining excellent chemical durability. These properties translate into considerable savings during transport and disposal.
INTRODUCTION
Synthetic mineral immobilization technology (SMITE) is emerging as an important methodology for the treatment of hazardous inorganic wastes. The first significant research program began in the 1970s at Pennsylvania State Universityl,2 to develop materials for the stabilization of high-level and defense nuclear wastes. The success of this work spawned a host of similar efforts3--5 based upon different classes of mineral analogs (excellent reviews of these strategies are given by Lutze and Ewing6); however, these studies were curtailed in 1982 after vitrified waste forms were selected as the preferred stabilization media? Nonetheless, persistent doubts concerning the suitability of glasses for all nuclear waste types remained, leading to a resurgence of interest in synthetic mineral waste forms, particularly for the immobilization of both mixed waste8,9 and weapons-grade uranium and plutonium.1o
The treatment of nonnuclear hazard-
High
ous wastes by SMITE is less developed, Traditionally, hazardous waste concentrates have been stabilized by cementation processes, usually by blending Portland cements and pozolanic materials, and large volumes of contaminated soil and sludges have been treated using a variety of in-situ and ex-situ processes. However, this approach has a number of drawbacks, Perhaps the most serious is that many inorganic salts are encapsulated in the cement rather than incorporated in insoluble phases, and these may release catastrophically through the ingress of ground water or because of physical disturbance. This limitation can often be addressed through the dilution of waste in the concrete or by the introduction of additives (e.g., clays and zeolites), although this adds substantially to the cost of stabilization, Furthermore, the use of high chemical doses increases bulking factors considerably, which, in tum, translates into uneconomic landfill charges. ll
Neither is the development of new cementitious treatment regimes a simple matter. The hydration mechanisms in ordinary Portland cement continue to be a subject for debate, and the mechanisms by which inorganic salts interfere with and retard setting processes are difficult to define. More seriously perhaps, the chemical and microstructural complexity of these systems makes it virtually impossible to routinely validate the speciation and fixation of all the components in a real waste system-the continuing discussion concerning the nature of arsenical phases in cement reflects this uncertainty.12-14 In combina
High tion, these factors mean that the economics of cement stabilization are not always viable and the long-term stability of Portland cements cannot be reliably predicted.
System Low~ ______ ~ __ ~ __ ~~ ____ ~ Low Type 3
Just as the limitations of cementitious systems are being tested, the criteria for materials that are to be classified as landfill-compliant are becoming increasingly stringent. Internationally, the waste management industry is confronted with meeting not only current
Type 1 Type 2 Hydramelallurgy Hydrametallurgy Pyrametallurgy
+ Pyrametallurgy
Figure 1. Properties and processing regimes for SMITE types.
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Type 2 SMITE
Figure 2. General flow sheet for type two SMITE stabilization of toxic metal concentrates.
disposal criteria but also those criteria likely to be enshrined in legislation before the tum of the century. In some instances, this uncertainty has paralyzed waste management programs, resulting in waste stockpiles on industrial sitesa scenario that arguably increases the chances of accidental releases. Therefore, alternative strategies for the treatment of hazardous inorganic wastes are urgently needed.
THE SMITE APPROACH
Synthetic mineral immobilization technology is defined as follows:
"Upon the basis of established geological principles, a mineral or group of mutually compatible minerals is selected whose crystal structures can incorporate all the species of a given waste stream, and which, by the addition of certain chemicals, may be prepared economically without the generation of secondary waste streams, to produce a durable waste form."l5
All SMITE types are fundamentally two-stage preprocessing and consolidation procedures (Figure 1), In stage one, the waste may be purified, redox adjusted, or prestabilized. In stage two, the intermediate product is converted into the final waste form, Type one SMITEs require multiple hydrometallurgical stages, which are low-cost, often technologically straightforward, and suitable for application in the field, In contrast, type three processes (e.g., as applied to high-level nuclear waste) are based on technically complex pyrometallurgical treatments and undertaken at central waste treatment facilities, The interme-
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diate type two approach, which is the major focus here, combines the best features of these pre-existing applications so that hazardous waste disposal is optimized in terms of cost, portability of plant, and durability of waste forms.I6
icsY Nevertheless, true vitrification of waste solutions can achieve substantial volume reductions.I8 In contrast to vitrification, SMITE methods routipely achieve waste loadings that are in excess of 20 wt. % with systems tailored to maxi-
~ ____ I,~j:I ___ I __ w_M~;R I \/\/\/
L SL.;R_.R •• ~1 .. , I NITROGEN I
In type two SMITEs, the waste is first reacted with acidic or basic initiators that either precipitate the toxic metals from solution and/ or convert them into nonvolatile substances. Tailoringchemicals are also introduced at this point so that they are intimately combined with the waste and are available during the second pyrometallurgical reaction to produce compositions appropriate for the desired synthetic mineral assemblage. The fired product may be formed as a powder, gravel, or monolith suitable for future extraction of valuable components, direct disposal in landfills, or fabrication of concrete waste forms. A general flow sheet for stabilization is shown in Figure 2.
mize this parameter. A potential problem associated with glass manufacture is that it is not inherently suited to minimizing sublimation of waste species, particularly if highly volatile compounds are abundant. For example, even though cesium isotopes are introduced at less than 3 wt. % during highlevel nuclear waste glass fabrication, losses from the melt must be cap
OPTION 1,.c-1 FIRE ... t """' ...... ""1· OPTION 2
\/ 'v'
\/\1 _ ..
LANDFILL
DISPOSAL
CEMENT
!tis important to differentiate between type two SMITE procedures and vitrification. Although both use high-temperature processes to achieve consolidation, the general approach as well as the form of the final products are quite different. Glasses immobilize waste to a dilute limit, which, depending on composition, will not usually exceed 15 wt.% and in many cases is considerably less. Although claims are made for vitrification at higher waste loadings, close examination usually reveals that significant crystallization has occurred, and many products are best described as glass ceram-
Figure 4. Flow sheet for SMITE stabilization of thallium chromate sludge.
tured and recycled,t9 or alternatively, cesium is ion-exchanged onto zeolite and introduced to the melter with the glass frit.2° Many metals and oxides sublime even more easily than cesium. During experiments to prepare glassy slags for arsenic stabilization, it was found that more than 90 percent of the arsenic sublimed.21 SMITE is not generally limited in this way, provided that a low vapor pressure precursor can be prepared by hydrometallurgical reaction. Energy costs also differ as SMITE products rarely
::::::~:;::::::~;:;:::~~::::::~::::::l requiretreatrnentabove I 1,100°C and lower tem-
I As<5ppm I~
TCLP < 0.5 ppm As loading - 22
L..-.----::----'
OVEN DRY
FIRE
Figure 3. Flow sheet of SMITE stabilization of arsenical flue dust.
1996 March • JOM
peratures are often satisfactory,22 whereas vitrificationis usually carried out at temperatures greater than 1,150°C.23
ARSENIC TRIOXIDE FLUE
DUST
Design Arsenic trioxide (ar
senolite) is a voluminous by-product generated by roasting arsenopyritic ores of base and precious metals to reduce sulfur levels sufficiently for smelting. Flue dust often occurs as nearly pure arsenolite, although it commonly coexists with antimony, lead, or cadmium oxides. Extensive experimentation has shown that the most durable mineral currently recognized for incorporating arsenic at high concentrations is an apatite-type (known as sva-
bite), which has the ideal stoichiometry of Cas(AsO 4)3F. The overall stabilization reaction, which is promoted by the addition of lime (the initiator) and calcium fluoride (the tailoring chemical), can be written thus:
3AsP3 + 9CaO + CaF2 + 30) ~ 2Cas(As04)3F (1)
There are two important points concerning this reaction. First, for apatite to crystallize the arsenic must be oxidized to the pentavalent state. This has important waste management implications as the trivalent form is generally considered more soluble and toxic. During SMITE processing, oxidation is achieved by firing in air, and complete conversion to apatite is readily monitored by powder x-ray diffraction (hydrogen peroxide or manganese oxide is often used to achieve the same effect in cementitious waste forms). Second, if a perfectly stoichiometric waste form were fabricated, an arsenic loading of 35.4 wt. % would be produced although, in practice, either lime or calcium fluoride are added in slight excess to accommodate fluctuations in flue-dust composition.
Solidification
A basic process for stabilizing arsenic is shown in Figure 3. Slacked lime and calcium fluoride are slurried together
Table I. TCLP Test Results from Arsenical Waste
Waste Form
Smelter Flue Dust Cement Encapsulation SMITE Ceramic SMITE Concrete
Arsenic TCLP Loading Results (wt.%) (As ppm)
60 20 22 18
4520 790 0.4
<0.1
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ppm
6 7 8
Extraction Number 9 10
concrete. The cement acts as a secondary barrier to dissolution and can be used to pump the waste into landfills.
Testing
tain TP+ and Cr3+ rather than TP+ and Cr6+, as these latter species display higher toxicity. One compound that satisfies these requirements is a thallium analog of the mineral redledgeite having the ideal formula of TlzCrzTi6016.z7
Solidification Powder x-ray diffraction confirmed that apatite was the dominant product while microanalysis using energy dispersive x-ray spectroscopy showed that calcium and arsenic appeared in the expected Figure 5. Multiple extraction TCLP data for thallium chromate
bearing SMITE concrete. ratio of 5:3; fluorine cannot be detected using this technique. A small amount of silica, probably introduced with the lime, is also present and partially replaces arsenic by the coupled substitution
The SMITE waste form was prepared on the benchscale by solid-state reaction of TlzCrp7 and TiOz (Figure 4). Ingredients of appropriate proportions were weighed into a beaker and slurried for two hours with water using a solid:liquid ratio of about 1 :2. The suspension liquor was filtered using a Buchner apparatus and Whatman paper, which generally collected all solids although some finely divided material passed through the filter paper until a filter bed built up. The filtercake was warmed in an oven (110°C) until dry, then fired at 700-1,150°C for one hour under a stream of nitrogen. Using this regime, neutral conditions were maintained and the reduction of Cr(VI) to Cr(Ill) accelerated. The overall reaction was:
Table II. TCLP Test Results for Thallium-Chromate Products
Waste Loading TCLP
TI+Cr (ppm)
Waste Form (wt.%) TI Cr
Original Sludge 82 130 21 SMITE Concrete 30 0.7 0.08
with the arsenolite at room temperature for periods of 30 minutes for up to several hours. The reaction is regarded as complete when arsenolite can no longer be detected by x-ray diffraction. During this hydrometallurgical reaction, a finnemanite-like compound (probably containing water of crystallization) precipitates according to the reaction believed to approximate the following:
3AsP3 + 4.5CaO ~ 2Ca4S(As03)3 (2)
Fluorspar does not participate in this reaction, but is intimately mixed with the finnemanite precursor so that it will be available during firing. The precipitate is separated from the liquor by vacuum filtration until a solid containing less than 10 wt.% water remains. (In full-scale production the liquor that contains <5 ppm arsenic is recycled.) The filtercake is oven-dried at 80-100°C to reduce water content to less than 5 wt.% and produce a robust gravel, which is sometimes reduced to centimeter fragments by light milling.
The gravel is converted into the stabilized waste form by firing in air for 30-60 minutes at l,OOO-l,100°C. A rapid-rise time of one hour is appropriate if sufficient oxygen is available to ensure the oxidation of arsenic. The second reaction is:
2Ca4S(As03)3 + CaF2 + 30) ~ 2Cas(As04)l (3)
The final product approaches theoretical density (3.5 g/ cm3). This procedure (including deliberate addition of excess lime and/or calcium fluorite) yields a final waste loading of ",22 wt. % arsenic, which may be disposed of directly or used as aggregate to produce a SMITE
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AsS+ + F- f-7 Si4+ + n. The durability of the waste form was
tested using the toxicity characteristic leach procedure (TCLP) method described elsewhere.z4,zs Typical results for the SMITE products are summarized in Table I, together with data for the untreated flue dust and direct cement encapsulation. As a guide, arsenical-solidified products are usually classified as suitable for secure or municipal landfill disposal when the total arsenic extracted in a single TCLP experiment does not exceed 5 ppm and 0.5 ppm, respectively. Both the SMITE ceramic and SMITE concrete easily meet the requirements for landfill disposal while maintaining high waste loading.
THALLIUM CHROMATE SLUDGE
Design Thallium chromate (TlzCrp7) precipi
tation is used in several industrial processes for reducing thallium levels. Although this compound is sparingly soluble, it does not meet regulatory criteria for landfill disposal and new methods are required for treating this residue. The problem is nontrivial as thallium salts are almost uniformly soluble and chromate (VI) is not readily incorporated in cement-hydrate phases.z6 Ideally, any stabilization matrix will con-
35 38 25 A
TlzCrp7 + 6TiOz ~ TlzCrzTip16 + 1.50z1 (4)
The fired powder was mixed with cement in a redledgeite:cement ratio of 3:1 and allowed to cure for one month in a sealed plastic bag. The final product contained greater than 30 wt.% Tl + Cr.
Testing
Within the detection limit of powder x-ray diffraction, TlzCrzTi6016 was the only product present, suggesting that thallium volatilization was minimaL In actual use, titania would be added in excess to serve as a buffer against variation in solids content of the sludge. Energy dispersive x-ray analyses were consistent with the expected stoichiometry, while scanning electron microscopy confirmed complete encapsulation of the redledgeite by cement.
The cement-encapsulated redledgeite was tested by TCLP. For the first extraction, an unbuffered acetic acid extractant (pH 2.88) was used, while for subsequent extractions the buffered solution (pH 4.95) was employed. The data are presented in Table II and Figure 5. Losses of thallium and chromium are low and
22 28 J.8
D Apatite II Spinel II Anhydrite Figure 6. Powder x-ray diffraction pattern of SMITE stabilized municipal incinerator fly ash.
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Table 1111. TCLP Results for Incinerator Fly Ash and SMITE Ceramic (ppm)
Arsenic Chromium Cadmium Lead 0.60 0.25
Zinc Sulfur 21,285
34 Untreated Fly Ash Treated Fly Ash
4 0.20
0.22 0.006
within regulatory limits. Significantly, the losses continue to fall during successive extractions, giving a high level of confidence that the waste form will display long-term durability. It is expected that even lower leach rates could be achieved if greater attention were given to modifying the surface properties of the redledgeite to match those of the hydrating cement phases.
MUNICIPAL INCINERATOR ASH Design
In this test work, fly ash produced by a municipal incinerator was studied. Unlike the two previous wastes, ashes are chemically diverse, containing a range of toxic metals, and (as Kirby and RimstidF8 recently described) a wide range of compounds of various reactivities are usually present. For the ash used here, conclusively identified phases included anhydrite (CaS04), halite (NaCl), sylvite (KCl), and calcium silicate (Ca2SiOJ29 Such is the complexity of the ash that a polyphase synthetic mineral assemblage is required to stabilize all of its components. This assemblage would normally consist of apatite, spinel, olivine, and anhydrite structure types.3D
Solidification
NaCl in the as-delivered fly ash had been introduced as a volatilization suppressant. Because the formation of soluble toxic-metal compounds such as NaAs03 is unavoidable, excess salt was partly removed by cold-water washing. For this washed material, a mineral assemblage was designed to accommodate the remaining toxic metals. In selecting the stabilization minerals, care was taken to exploit the presence of dominant species in the waste (particularly calcium, aluminum, and sulfur) and to enhance the propensity of the waste to form sparingly soluble refractories such as apatite. The major synthetic minerals and the waste-element partitioning included: Spinel ABp4,where A = Cu, Zn, and Ti and B = Fe, Cr, AI, and Mn; Apatite As(B04)3Cl, where A = Ga, Pb, Cd, Ba, Sr, and Na and B = As and P; and
Table IV. Physical Property and Cost Comparisons for Arsenic Stabilization
Cement Property SMITE Encapsulation As Loading 20-30wt.% 5-10wt.% Costs
Stabilization $241-437 $750-1,500 Disposal $490-754 $2,695-5,145
Vol. Increase 0-2x 5-10x Wt. Increase 2-2.5x 5-20x
1996 March • JOM
9 0.045
310 0.188
Anhydrite AB04, where A = Ca, Sr, and Ba and B = S.
To promote the formation of these minerals, the washed fly ash was slurried in a controlled manner with dilute phosphoric acid (supplying phosphorus for apatite stabilization), lime (providing calcium to react with sulfate and ensure apatite crystallization), and aluminum hydroxide (capturing transition metals in aluminate spinel). The proportions of additives were determined on the basis of stoichiometric requirements and introduced in slight excess to accommodate ash nonhomogeneity. The precursor was then filtered, dried, and fired at 1,100°C to stabilize the final assemblage at a loading of 54 wt.% ash.
Testing
X-ray diffraction confirmed that the desired mineral assemblage had crystallized (Figure 6). The predominance of apatite was to be expected as calcium and the majority of minor metals entered this phase. The apatites showed complex and variable chemistries reflecting the flexibility and adaptability of the structure. Stoichiometries ranged from near prototype CaS(P04)3Cl to apatites dominated by waste constituents including Si, P, AI, and S. TCLP tests confirmed that losses oftoxic metals from the SMITE waste met with the regulatory criteria for landfill disposal (Table III).
Although the direct treatment of incinerator ash is feasible, it seems more likely that SMITE will be applied to the treatment of heavy metal evaporates that will be removed from ash to render it nonhazardous and suitable for use as a construction material or roadfill.31
COMMERCIAL PROSPECTS
The commercial viability of adopting SMITE is presently undergoing detailed assessment; however, a single example will serve to illustrate the potential savings. The quantity of arsenic released annually by smelting and other activities has been estimated to approach 2.5 million tonnes per annum.32 Present practice is to solidify arsenic in cement or store it as a dilute slurry in tailings dams.33
Neither of these approaches will prove satisfactory in the long term. In the case of cement encapsulation, arsenic loadings must be maintained at below 5 wt. % to maintain the chemical and physical integrity of the solid (see Table 1).34,35 In tailings dams, arsenic trioxide is first slurried with iron chloride and lime (Fe:As ratio 1-4:1) to achieve overall arsenic loadings of -5 Wt.%.36 Alternate stabilization strategies such as glassy
slags retain even lower waste loadings. In comparing the bulking factors of
arsenical waste forms, iron-arsenate tailings dams increase waste volume by more than 25 times while cement encapsulation results in at least a six-fold volume increase because SMITE waste forms (even as concrete) yield loadings in excess of 20 wt. %. As this technology offers considerable savings when the cost of transport and landfill is considered, recent cost estimates suggest that, depending on local conditions, SMITE treatment of arsenical fumes can reduce stabilization and disposal charges by 5-10 times (Table IV).
CONCLUSIONS
The primary technical advances of SMITE over conventional technologies are the ability to predetermine and force metals into their least toxic states; the capacity to cope with wastes containing high concentrations of volatile inorganics; and the potential for achieving waste loadings at least double those presently realized. This last property is particularly important as it opens the way for adopting more cost-effective and flexible hazardous waste management strategies. In particular, because the waste is immobilized in a compact and durable form, it may, on occasion, be reasonable to store waste above ground if it is believed that a metal may become valuable in the future and extracted. An example would be antimony, whose price during the past two years has risen several fold. 37 If antimonical residues were diluted and dispersed in cement, it would be impossible to extract antimony economically; however, when incorporated in a SMITE mineral (in this case Ca2Sb20l pyrochlore1S) interim storage may be feasible until extraction using established mineral processing techniques became viable. A second consequence of adopting high-density and high-waste loaded solids is that lifetime landfills could be extended significantly to yield social and political dividends.
References
1. G.J.McCarthyeta1.,"CrystaIChemistryoftheSupercalcine Minerals in Current Supercalcine-Ceramics," Ceramics in Nuclear Waste Management, DOE CONF-790420 (1979), pp. 315-320. 2. B.E. Scheetz et aI., Waste Mange., 14 (1994), pp. 489-505. 3. P.ED. Morgan et aI., J. Am. Ceram. Soc., 64 (1981), pp. 249-258. 4. A.E. Ringwood et aI., Nature, 278 (1979), pp. 219-223. 5. P.J. Haywood and E. V. Cecchetto, "Development of SpheneBased Glass Ceramics Tailored for Canadian Waste Disposal Conditions," Scientific Basis for Nuclear Waste Management V, ed. S.V. Topp (New York: Elsevier, 1982), pp. 91-98. 6. W. Lutze and RC. Ewing, Radioactive Waste Forms for the Future (Amsterdam, Netherlands: North Holland Physics Publishing, 1988). 7. TD. Bemadzikowski et aI., Ceram. Bull., 62 (1983), pp. 1364-1390. 8. V.M. Oversby et al., "Imrnobilisation in Ceramic Waste Forms of the Residues from Treatment of Mixed Waste," Scientific Basis for Nuclear Waste Management XVII (Pittsburgh, PA: MRS, 1994), pp. 285-292. 9. M. Genet et aI., "Thorium and Uranium Phosphatte Syntheses and Lixiviation Tests for Their Use as Hosts for Radwastes," in Ref. 8, pp. 799-806. 10. A. Jostons et aI., "Synroc for lmmobilising Excess WeapORS Plutonium," in Ref. 8, pp. 775-782. 11. Anonymous, "Turn Hazardous Wastes into Nonhazard-
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ous Wastes," Modern Metals, (May, 1995), pp. 54-56. 12. M. Carter et aI., "Inunobilisation of Arsenic Trioxide in Cementitious Materials," 6th AusIMM Extractive Metallurgy ConJerence (Melbourne, Australia: AusIMM, 1994), pp. 275-280. 13. J.5. Forrester, J.H. Kyle, and T.J. White, "Stabilization of Arsenic Trioxide Waste in Cement," Ceramics Adding Value, vol. 2 (Sydney, Australia: Australian Ceramic Society, 1992), pp. 104G-1046. 14. V. Dutre and e. Vandecasteele, Waste Manage., 15 (1995), pp.55-62. 15. T.J. White et aI., "Xtaltite-A Mineralogical Approach to the Disposal of Mercury and Arsenic Wastes," Extraction and Processing for the Treatment and Minimization of Wastes (Warrendale, PA: TMS, 1993), pp. 217-227. 16. T.J. White, Environ. Intern. (1995). 17. E. Wang et aI., "Effect of Fluoride on Crystallization in High Calcium and Magnesium Glasses," in Ref. 8, pp. 473-479. 18. e.M. Jantzen, Ceram. Bull., 74 (1995), p. 11. 19. J.P. Giraud, J.P. Conord, and P.M. Saverot, "Conceptual Design for Vitrification of HLW at West Valley Using a Rotary Calciner/Metallic Melter," Nuclear Waste Management, Advances in Ceramics, vol. 8 (Columbus, OH: ACerS, 19B4), pp. 132-142. 20. N.E. Bibler et aI., "Initial Demonstration of the Vitrification of High-Level Nuclear Waste Sludge Containing an Organic Cs-Loaded Ion-Exchange Resin," Scientific Basis Jor Nuclear Waste Management XVI (Pittsburgh, P A: MRS, 1993), pp.81-86. 21. F.RA. Jorgensen et aI., "The Safe Disposal of Arsenic in Metallurgical Slags," 2nd National Hazardous & Solid Waste Convention and Trade Exhibition-Achievements and Challenges (Sydney, Australia: Australian Water and Wastewater Association, 1994), pp. 405-412.
Process-Oriented Topics
22. T.J. White et aI., "Xtaltite-An Advance Ceramic System for Immobilisation of Arsenical and Heavy Metal Wastes," Innovative Solutions for Contaminated Site Management (Alexandria, VA: Water Environment Federation, 1994), pp. 437-448. 23. J.F. Sproull, S.L. Marra, and e.M. Jantzen, "High Level Radioactive Waste Glass Production and Product Description," in Ref. 8, pp. 15-25. 24. J.R Conner, Chemical Fixation and Solidification oJHazardous Wastes (New York: Van Nostrand Reinhold, 1990), pp. 639-{;51. 25. T.J. White, "Design, Testing and Economics of Xtaltite Toxic MetaICeramics," Proceedingsofl00thAnnualNorthwest Mining Association Convention (Spokane, WA: Northwest Mining Association, 1994). 26. A. Kindness, A. Macias, and F.P. Glasser, Waste Manage., 14 (1995), pp. 3-11. 27. T.J. White et aI., "Xtaltite-Ecologically Sustainable Disposal of Heavy Metal Smelting and Refinery Waste," International Symposium on the Treatment and Minimization of Heavy Metal Containing Waste (Warrendale, PA: TMS, 1995). 28. e.S. Kirby and J.D. Rimstidt, Environ. Sci. Techno!., 27 (1993), pp. 652-{;60. 29. T.J. White, "Synthetic Mineral Immobilization Technology for the Ultimate Disposal of Hazardous Inorganic Waste," (Paper presented at the International Congress of Waste Solidification-Stabilization Processes, Nancy, France, 28 November-1 December 1995). 30. T.J. White and I.A. Toor, "Synthetic Mineral Immobilization Technology for the Stabilization of Incinerator Ashes," (Paper presented at the Fourteenth International Incineration Conference, Seattle, WA, 8-12 May 1995). 31. A. Jakob, s. Stucki, and P. Kuhn, Environmental Sci. Technol., 29 (1995), pp. 2429-2436. 32. R Frost, Search, 23 (1992), pp. 164-165.
UPCOMING EDITORIAL TOPICS
April 1996 1996 Review of Extraction and Processing
Materials-Oriented Topics
Nitrogen-Strengthened Powder Metanurgy Alloys .
May 1996 The Coating of Materials Recent Advances for for Corrosion Resistance Electrical Interconnects
PLUS: Quarterly Coverage of the Aluminum ProceSSing Industry
June 1996 The ThermQplasma Aluminum AllQys fQr Packaging Processing of Materials
July 1996
August 1996
The Cost-Effective Synthesis of High-Performance Materials
ReCent Developments in Copper Hydrometallurgy
Car Wars-Steel Strikes Back (Steel vs. Competitive Materials)
Semiconductors: The Nanoscale CharacterizatiOn of Heterostnwture Devices and thE! Comparison of Wide-Bandgap Structures
PLUS: Quarterly Coverage of the Aluminum Processing Industry
September 1996 Emerging Sensor Technologies for the Intelligent Processing of Materials
October 1996 The Processing and Application of Reactive Metals
PLUS: CeramicS in Micro-electro-mechanical Systems
November 1996
December 1996
Developments in the Primary Aluminum Industry
Innovations in Pyrometallurgy
Micromechanical Composite Materials
Materials for the Bulk Application of High-To Superconductors
High-Temperature Materials: Environmental Effects, Degradation, Failure, and Solutions
The Computer Simulation of Structllre/Property RelationShips in Irradiated Materials
PLUS: The Application of MathematicS to Problems in-Materials Science and Engineering
SUBMITIING PAPERS TO JOM
33. RG. Reddy, J.L. Hendrix, and P.B. Queneau, Arsenic Meta/lurgy~Fundamentals and Applications (Warrendale, P A: TMS,1988). 34. T.J. White, Search, 26 (1995), pp. 148-151. 35. A. Samarin, Waste Management and Environment (April 1995), p. 39. 36. G.P. Demopoulos, D.J. Dropper!, and G. Van Weert, Hydrometallurgy, 38 (1995), pp. 245-261. 37. P. Crowson, Minerals Yearbook (New York: Stockton Press, 1994).
ABOUT THE AUTHORS
Tim White earned his Ph.D. in solid-state chemistry at the Australian National University in 1982. He is currently a professor of environmental technology at University of South Australia and project manager of SM ITE International Pty. Ltd. Dr. White is also a member of TMS.
Irfan Toor earned his Ph.D. in chemical engineering at the University of Florida in 1985. He is currently president of Texilla Environmental. Dr. Toor is also a member of TMS.
For more information, contact T. White, the Ian Wark Research Institute, University of South Australia, the Levels, SA 5095, Australia; telephone 61-8-302-3694; fax 61-8-302-3683.
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editing, proofing, typesetting, design, and printing. Since each issue carries a number of articles that must fit within topical and size constraints, author cooperation is expected. Minor delays can be very disruptive to the production process, and the editors should be quickly notified of problems.
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In brief, a correctly prepared manuscript is typed, double spaced, on 8.5 x 11 inch (22 x 28 cm) paper. Manuscripts (text and graphics) prepared on computer diskettes are not only welcome, but encouraged. The editorial office can handle a variety of formats. Papers must include: a title, a byline, a summary, an introduction, appropriate subheads, a conclusion, author biographies, references, glossy prints and/or high-quality artwork, and the address, telephone, and fax numbers of the designated contact author. All units must be in metric; SI is preferred.
To Receive an Author Kit, Call or Write: JOM, 420 Commonwealth Drive, Warrendale, Pennsylvania 15086; telephone (412)
776-9000, ext. 224; fax (412) 776-3770; e-mail [email protected]
James J. Robinson, Editor
JOM • March 1996