ZEOLITES By Robert L. Virta

Natural Zeolites catalysts, and water purification, in decreasing heavy metals from wastewaters. One study order of consumption. As in previous years, demonstrated that a calcium clinoptilolite Zeolites are hydrated aluminosilicates of the over 50% of the natural zeolite was consumed removed low levels of cadmium, manganese, alkaline and alkaline-earth metals. as pet litter. Consumption patterns for most and zinc from mine wastewater, providing Approximately 40 natural zeolites have been applications did not change. The only additional options for sludge disposal and lower identified over the past 200 years, the most exception was with pet litter applications, where costs for water treatment. Another study common of which are analcime, chabazite, the reported consumption of zeolites declined. involved the pretreatment of natural zeolites clinoptilolite, erionite, ferrierite, heulandite, The properties that made natural zeolites with ferric sulfate solutions. The iron laumontite, mordenite, and phillipsite. Zeolites commercially valuable included ammonium precipitates on the zeolites served as the are commercially valuable because of their adsorption (aquaculture, aquarium filters, odor collector for arsenic. unique ion-exchange, molecular sieving, and control applications, pet litter, and water catalytic properties. purification), moisture adsorption (desiccants, Synthetic Zeolites Commercial zeolite deposits in the United odor control, and pet litter), and ion-exchange States are associated with the alteration of capabilities (wastewater cleanup and water Producers of synthetic zeolites announced volcanic tuffs in saline, alkaline lake deposits purification). plans to construct new plants and expand and open hydrologic systems. The deposits are Successful marketing of natural zeolites is existing plants and introduced several new located in Arizona, California, Idaho, Nevada, dependent on selecting the proper zeolite for a zeolites. Akzo Nobel began construction of a New Mexico, Oregon, Texas, Utah, and specific application. A review paper discussed zeolite plant in Pasadena, TX and W. R. Grace Wyoming. The major components of these the properties of zeolites and recommended that announced plans to build a zeolite plant in deposits are chabazite, clinoptilolite, mordenite, information such as form, color, crystal Louisiana that will supply catalysts to its and phillipsite. Erionite, orthoclase and structure, pore diameters, void volume, packing, fluidized cracking catalyst plant. This activity plagioclase feldspar, montmorillonite, opal, etc. be determined for each zeolite product. is in response to growing demand for refinery quartz, and volcanic glass may be present in This information will help the customer choose catalysts in Asia.5 United Catalysts Inc. some deposits. The composition of these the proper zeolite for a specific application.1 introduced a new zeolite catalyst for use in deposits was determined primarily by the World Review.—Australia.—Zeolite manufacturing ethylbenzene from benzene and temperature and pressure of formation and the Australia Ltd. worked with Global Soil Systems ethylene feedstock. The zeolite was developed chemistry of the altering fluids. If the alteration and Envirosciences Pty. Ltd. to market its jointly with Fina Technology. ABB Lummus process has gone to completion, the zeolite natural zeolites. Their primary markets were Crest Inc. and Sinopec Technology Co. began content of portions of some deposits may animal feed supplements and acid mine work on commercializing its process for approach 100%. drainage clean-up.2 manufacturing ethylbenzene from benzene and Production.—Conventional mining Canada.—Princeton Zeolite Products Inc. dilute ethylene feedstock. The process uses a techniques were used in the mining of natural and Princeton Industrial Mineral Joint Venture pentasil-type zeolite catalyst. The zeolite is not zeolites. The overburden was removed to allow signed a letter of intent to sell their zeolite affected by impurities, such as H2S, H2O, CO, access to the ore and the ore was stripped for properties in British Columbia to I.M.P.A.C.T. and CO2, thereby reducing the need for processing using front-end loaders or tractors Minerals Inc. I.M.P.A.C.T. Minerals will begin feedstock pretreatment.6 Engelhard Corp. equipped with ripper blades. Fractured ore was a bulk sampling program of the deposit and do introduced a zeolite catalyst for fluid catalytic dried and then crushed using either jaw market development.3 cracking applications. The zeolite is more crushers or roller mills. The crushed ore was Cuba.—The International Marketing Firm tolerant to nickel and vanadium and allows packaged directly for shipping or was screened for Industrial Minerals S.A. reported zeolite better control of the residual feedstock to remove fine material when a granular product production of 600,000 tons per year in Cuba. processing than other zeolite catalysts.7 was required. Exports, primarily to Brazil, Colombia, Crosfield introduced a new zeolite, A24, which Eight companies mined or sold natural Ecuador, France, Italy, Mexico, and Spain, were was developed specifically for detergent use. zeolites in the United States in 1994. reported to be greater than in the previous 4 The zeolite consists of smaller crystallites and Clinoptilolite was mined and/or processed in years combined.4 has better calcium and magnesium exchange California, Nevada, New Mexico, Oregon, and Current Research and Technology.—The properties than other detergent-grade zeolites.8 Texas; chabazite was mined in Arizona. Total U.S. Bureau of Mines continued its work on Two companies announced plans to expand domestic production was 52,800 metric tons. using natural zeolites for treating acid mine facilities that use synthetic zeolites. Georgia Consumption.—Sales were 35,200 tons in drainage. As part of the study, the recycle Gulf will upgrade its Pasadena, CA, cumene 1994, a slight decrease from that of 1993. characteristics of zeolites were determined. No facility to use zeolite-based catalyst technology.9 Natural zeolites were used for pet litter, animal decrease in the cation exchange capacities of Lyondell Petrochemical Co. announced plans to feed supplement, fertilizer carrier, oil absorbent, the zeolites tested were detected after 40 add 2,000 to 3,000 barrels per day capacity to odor control, aquaculture, horticultural loading and stripping cycles. Other work its zeolite-based methyl tert-butyl ether process applications, desiccants, gas absorbents, focussed on the removal of arsenic and other line.10

1 Current Research and Technology.— 94-16, 1994, 7 pp. Mobil Research and Development Corp. 2Industrial Minerals (London). Zeolite Australia developed a new zeolite structure. The Marketing Drive. No. 320, May 1994, p. 9. 3 structure is composed of cages with dimensions Industrial Specialties News. I.M.P.A.C.T. Eyes of 0.71 by 0.71 by 1.82 nanometers and 10-ring Zeolite Deposit in British Columbia. V. 8, No. 16, Aug. 29, 1994, p. 3. apertures. Hexamethyleneimine was used as the 4Mining Journal. Cuban Zeolite Exports. V. 324, template during the synthesis process. The No. 8308, Jan. 6, 1995, p. 7. zeolite may be synthesized as an aluminosilicate 5Chemical Week. Grace's $58 Million Expansion 11 or a borosilicate. Targets Asia's Booming FCC Markets. V. 155, No. In other research, scientists at Perdue 17, p. 12. University synthesized oriented zeolite crystals. 6Chemical Week. UCI Makes Debut in EB The crystals were grown on a gold coated Market with Zeolite Catalyst. V. 155, No. 119, Nov. silicon substrate which had been modified with 16, 1994, p. 16. an organophosphate. Oriented growth was Chemical Engineering. A Zeolite Catalyst largely attributed to the organophosphate Eliminates the Need to Pretreat Ethylene Feed. V. 101, No. 12, Dec. 1994, p. 19. coating. Possible uses for oriented zeolite 7Chemical Marketing Reporter. Engelhard crystals include catalytic membranes or Introduces FCC Catalyst for Resid Feedstocks. V. chemical sensors for environmental 246, No. 16, Oct. 17, 1994, p. 24. 12 monitoring. 8———. Crosfield Claims Zeolite Breakthrough. Surface modification improved the sorption V. 246, No. 1, July 4, 1994, p. 9. characteristics of clinoptilolite for oxyanions. 9Chemical and Engineering News. Georgia Gulf Clinoptilolite was treated with to Upgrade Texas Cumene Facility. V. 72, No. 49, hexadecyltrimethylammonium (HDTMA). The Dec. 5, 1994, p. 11. 10 surface-modified zeolite removed chromate, Chemical Engineering. Zeolite-Based selenate, and sulfate from solution while the Isomerization Cuts Cost of MTBE Production. V. 101, No. 1, Jan. 1994, p. 23. untreated zeolite did not remove these species. 11Haggin, J. Molecular Sieve with Unique Anion retention was attributed to the formation Structural Features Synthesized. Chem. and Eng. of HDTMA-anion precipitates on the zeolite News, v. 72, No. 27, July 4, 1994, p. 23. 13 surface. 12Haggin, J. Oriented Zeolite Growth on Surfaces The National Institute of Standards and Achieved. Chem. and Eng. News, v. 72, No. 18, Technology awarded a $2 million grant for a May 2, 1994, p. 6. project to synthesize catalysts, including 13Haggerty, G. and R. Bowman. Sorption of zeolites, on a microcrystalline scale. The Chromate and Other Inorganic Anions by Organo- objective is to synthesize crystals of uniform Zeolite. Environ. Sci. Techno., v. 28, No. 3, 1994, size and composition. These catalysts could pp. 452-458. 14Chemical and Engineering News. Project exhibit unique properties that could improve 14 Targets Technology to Make Nanoscale Catalysts. reactivity and selectivity. V. 72, No. 48, Nov. 28, 1994, p. 32.

Outlook OTHER SOURCES OF INFORMATION

Mining and sales of natural zeolites U.S. Bureau of Mines Publications increased from 12,000 tons in 1988 to 35,000 Minerals Yearbooks, annual (Also available tons in 1994 with the peak year being 1993. by FAX by dialing 202-219-3644 and Most of the sales increase resulted from the ordering document 860100). increased use of zeolites in animal feed and pet Information Circular 9140. litter applications. Increases of the magnitude Other Sources experienced between 1988 and 1993 are not Chemical and Engineering News, monthly. anticipated to continue into the future. Chemical Marketing Reporter, weekly. Domestic consumption for the next few years Company annual reports. should be between 35,000 to 45,000 tons per European Chemical News, weekly. year. Industrial Minerals (London), monthly. With regards to synthetic zeolites, the Mining Engineering, monthly. market with the largest growth potential are detergent applications, particularly in Asian markets. Another area for growth will be in environmental applications such as emission controls.

1Eyde, T. Using Zeolites in the Recovery of Heavy Metals From Mining Effluents. SME Preprint

2 TABLE 1 DOMESTIC ZEOLITES PRODUCERS, 1994

State and company Type of zeolite Arizona: GSA Resources Inc. Chabazite UOP Inc. Do. California: Steelhead Specialty Minerals Clinoptilolite Nevada: American Resource Corp. Do. New Mexico: St. Cloud Mining Co. Do. Oregon: Teague Mineral Products Co. Do. Texas: Zeotech Corp. Do.