The following abstracts are presented in alphabetical order by author. An asterisk (*) indicates the speaker in presentations with more than one author. The proceedings of the conference are being edited and will be published by the Wyoming State Geological Survey within the next few months. For further information about the proceedings, contact Mr. Ray Harris, Wyoming State Geological Survey, P.O. Box 3008 University Station, Laramie, WY 82071, tel. (307) 766-2286, fax (307) 766-2605. For copies of individual papers, contact the authors directly.

Process Selection Criteria for Refining Trona to Commercial Products

by Roger Aitala, Isonex, Inc., Austin, TX

tel. (512) 264-2802 fax (512) 264-2950

Trona deposits vary in geological and chemical characteristics. Geographical location and site characteristics, such as environmental matters, specific energy resources, distribution methods, and trade barriers are important considerations. A commercially successful project capable of surviving the inevitable competition of this global business rests on the rational integration of the major project parameters.

There cannot be any inconsistency between the product from the mine, the feed to the refinery, and the market requirements. They must match or economic disaster is possible after investing the several hundred million dollars required to build a world-class trona refinery. Process selection must match: the reality of the deposits; local energy availability and costs; and the geographical market under consideration for soda ash and suitable derivatives.

This paper outlines a logical methodology for process and product slate selection, possibly using a specific example of an existing deposit in the United States, Turkey, or East Africa as a candidate for commercial development. Existing commercial technologies are briefly reviewed. Mining and refining technologies under development will also be mentioned.

A Mineralogic and Stratigraphic Profile of Trona Bed 17 in the Solvay Trona Mine near Green River, Wyoming (poster) by Paul Boni, University of Colorado, Boulder

tel. (303) 492-2612

A detailed study of trona bed 17, using techniques of petrography and x-ray diffraction, has been undertaken in the Solvay trona mine near Green River, Wyoming. A continuous, vertical channel sample was taken from near the production shaft for this study. At this location bed 17 is 12.6 feed thick and includes several, easily recognizable, stratigraphic markers, which can be correlated throughout the mine and bed 17 at large.

The mineralogy and stratigraphy of trona bed 17 evolved throughout The life of its depositional history in cyclic and linear patterns. Data indicate that this region of bed 17 was deposited subaqueously during its early and late history and may have undergone periods of subaerial deposition. The lower four feet of bed 17 exhibits couples of sparry and laminated trona capped with microscopic dolomite rhombs and dark organic matter (algae?) which are likely controlled by periods of cooler air temperatures and rainfall in the Green River Basin. If these cyclic textures represent annual climatic cycles, then trona accumulated at an annual rate of two to three inches per year.

The lower eight and a half feet of bed 17 is relatively pure with respect to insoluble and trace minerals whereas the upper four feed contains increased accumulations of dolomite, nahcolite, shortite, trace searlesite, and other unidentified minerals. The upper four feed were likely precipitated from late-stage concentrated brines, and contain dissolution-recrystallization textures and trona breccias indicating occasions of turbulent water.

Computer Modeling of Trona Reserves (poster) by Neil Brown, Union Pacific Resources-Minerals, Ft. Worth, TX

tel. (817) 877-7228

Union Pacific Resources uses a computer software package to model and track its trona resources. UP's database contains information from 692 bore holes drilled in or near the known sodium leasing area. Reserves are generally modeled into a polygon using an inverse distance algorithm. The polygon table contains the vertexes of all of the lease properties (generally these are whole sections of land) and by modeling the bed data to the polygons we can generate a reserve number by section, by lease, or by bed. This has allowed UP to essentially crease a GIS for the trona district. We can update lease maps, monitor our trona leases, map lease conflicts, and trace surface ownership. Some drill core containing trona will also be displayed.

Microwave-Induced Wet Calcination of Trona, by Chang Yul Cha, University of Wyoming, Laramie, WY

tel. (307) 766-2837

The technical feasibility of a microwave based trona processing method has been investigated in various laboratory experiments. The results of these experiments will be discussed. It has been found that this process allows the trona to be directly calcined while in solution without the need for high temperature or pressure. Some of the advantages of this technique when compared to conventional processing methods are: (1) decrease in decomposition temperature, (2) greatly decreased apparent activation energy, and (3) increased rate constant at 100 degrees C.

Microwave induced wet calcination of trona has the potential to eliminate many of the steps currently necessary in the conventional processing of trona into soda ash including crushing and high temperature calcination, with the goal of improving economics and simplifying the process.

A Review of the Supply and Demand of Soda Ash in southeast and East Asia, by Judith Chegwiden, Roskill Information Services, London, England

tel. 44-171-582-5155 fax 44-171-793-0008

The overview of supply will cove local production, including the recent rapid expansion of output in China, declining output in Japan, the producers in South Korea and Taiwan and the potential for new soda ash plants. Imports of U.S. soda ash are an important component of supply and this paper will examine the pattern of investment in the U.S. industry by Asian soda ash producers and consumers. Other exporters are targeting the region and an account will be given of trade from the former Eastern Bloc as well as the role of China.

The main force behind the growth in demand for soda ash in the region has been the burgeoning glass industry. An account will be given of the glass industry in the region with particular emphasis of the Indonesian glass industry. Production of container and flat glass as well as tableware are all important in Indonesia, but the country is entirely dependent on imported soda ash. A project to build a local soda ah plant has been revived and the potential impact of this plant will be examined. The review will conclude with a forecast of likely patterns of Asian supply and demand over the next few years.

Solution Mining Colorado Nahcolite

by Roger Day, White River Nahcolite Minerals Co., Rifle, CO

tel. (913) 344-9202

The Green River Formation in the Piceance Creek Basin in northwestern Colorado is estimated to contain 30 billion short tons of nahcolite (NaHCO3). White River Nahcolite Minerals (WRN) developed commercial nahcolite mining in 1991 by combining horizontal drilling and hot water solution mining technology. The hot aqueous solution is pumped from the cavity to the surface facility where it is cooled, causing dissolved nahcolite to recrystallize as high purity sodium bicarbonate. Dewatering, drying, and sizing prepares this product for the USP, food grade, industrial, and animal feed markets. White River Nahcolite's solution mine has become a high quality low cost sodium bicarbonate source which is annually expanding sales since start-up in 1991.

The mining interval is a 24-foot-thick bed averaging 75 percent nahcolite located 2,000 feet below the surface. Two widely spaced production wells are connected by a horizontal bore hole drilled near the base of the mining interval. A mining chamber or cavity results as hot water solution passes along the horizontal bore hole between the wells dissolving the nahcolite. A chamber and pillar mining method results. Currently, active mining chambers have produced 85,000 tons per 1,000 feet of chamber and show no signs of exhaustion. The recovery goal is 220,000 tons per 1,000 feet.

Exploration for Sodium Carbonate Deposits

by John R. Dyni, U.S. Geological Survey, Denver, CO

tel. (303) 236-5544; fax (303) 236-0459

Controls on the origin of deposits of high-quality sodium carbonate include: (1) a tectonic basin in which downwarping keeps pace or exceeds the rate of sedimentation, (2) a closed hydrographic basin in which evaporation exceeds outflow, (3) a more-or-less permanent body of nutrient-rich water, (4) evolution of solutes in the lake waters that lead to high Na/(Ca+Mg) and (HCO3+CO3)/(SO4+Cl) ratios, (5) a warm climate favoring high productivity of algae, and (6) a high rate of bacterial sulfate reduction. The latter two controls are believed to be especially important to achieve deposits of high purity like those of the Eocene Green River Formation in Wyoming, Colorado, and Utah. Some areas favorable for exploring for economic sodium carbonate deposits include the Great Basin in western United States and northern Mexico, Turkey, China, the East African Rift, and possibly southeast Asia including Thailand and Burma.

A New Technology for the Soda Ash Deposits Near Trona, California

by James L. Fairchild*, Michael E. Lovejoy, and Gail F. Moulton, Jr., North American Chemical Co., Trona, CA tel. (760) 372-2440; fax (760) 372-2232

Mineral extraction in Searles Valley began in 1873 with borax and raw trona scraped from the surface. Brine processing started in 1914 with potassium chloride and borax recovery. Expansions over the years added sodium sulfate and soda ash to the product mix. The deposit characteristics and limited availability of water resulted in the need for a different application of technology to remain competitive. Today, Searles Lake is one of the largest saline mineral producers in the United States.

A new understanding of lake geology has allowed the development of new more productive solution mining technology. Minerals currently solution mined include trona, borax, and thenardite. Products are recovered from the resulting brines using carbonation for soda ash, refrigeration for borax and sodium sulfate, and solvent extraction for boric acid. Trona is also dredged as a crude product from extensive surface deposits.

Evolution of Wyoming Soda Ash Processes

by W. R. Frint, Consultant to FMC Corp., Green River, WY

tel. (307) 875-2713

The production of useful alkaline chemical products from Wyoming trona has resulted in major changes in the world soda industry during the past 50 years. This paper summarizes the processing technological changes which have occurred to date. So far there have been four different processes used to produce different grades or types of soda ash, and there are at least six different plants producing other primary products and a couple of secondary product plants. A brief comparative description of the four basic processes is given following the time line as the events evolved.

Overview of Air Pollution Issues Facing the Trona Industry

by David Gaige, Woodward-Clyde Consultants, Denver, CO

tel. (303) 594-3946

The combination of new regulations, and new revelations, will present some challenges to the trona industry in the next decade. This discussion focuses on the air pollution issues that will affect the trona industry. The new and proposed regulations that will affect the facilities in the trona industry include: (1) compliance assurance monitoring (CAM), (2) credible evidence, (3) 112(r) and the toxic release inventory, (4) new standards for fine particulate and ozone, and (5) new source review reform (NSRR).

The CAM requirements go hand in hand with the Title V permit applications that Wyoming DEQ will be developing in the near future. The credible evidence rules establish that any reasonable evidence can be used by a regulatory agency, or the public (in the case of citizen suits), to determine compliance (or non-compliance). In response to environmental disasters such as the release of toxic gases at Bhopal, Congress added the 112(r) requirements in the Clean Air Act Amendments of 1990. These regulations require industry to prepare a Process Safety Management Plan and an Emergency Response plan and communicate the potential risk to the public. The new proposed standards for fine particulate and ozone may require a reduction in emissions of NOX and VOC's. The NSRR formalizes the involvement of the Federal land manager (FLM) early in the permitting process. Recent permitting has indicated a FLM concern for Air Quality Related Values in southwest Wyoming that could shape the future of development.

In summary, several new and proposed regulations will create additional challenges for the trona industry as soda ash production continues to grow and additional resources are developed.

Chemical Considerations in the Origin of the Green River Trona Deposit

by Donald E. Garrett, Saline Processors, Inc., Ojai, CA

tel. (805) 646-0159

The carbonate source and reason for the purity of the Green River trona deposit are unknown. Quite likely, river and runoff water, even with sulfate reducing bacteria, could not have formed it. High-carbonate springs could have, and several trona deposits have somewhat different compositions before, during, and after the deposition period. The trona's purity is similar to other large saline mineral formations, and in marine deposits partial leaching, followed by seepage and/or periodic flushing of the end liquor, accounts for their composition and purity. The Green River and Farson Eden brines may be similar end liquors.

Building an International Soda Ash business

by D. George Harris, D. George Harris & Associates, New York, NY

tel. (212) 207-6400; fax (212) 207-6450

Harris group chairman, D. George Harris, will outline the strategy behind the growth of the Harris companies, with a focus on how this strategy has been implemented in the development of the group's soda ash business. He will also discuss his views on why one should have a global position in this business segment. And, he will speculate on whether synthetic soda ash plants have a viable future.

A Model for the Solution Mining of Trona

by Animesh Ukidwe, Graduate Student, and Professor Henry Hayes, Jr.*, University of Wyoming, Laramie, WY tel. (307) 766-4923

In the solution mining process subject of this study, two wells are drilled into a horizontal seam of trona and connected by some means (hydraulic fracturing or horizontal drilling). A brine is produced at the other well. Processing economics generally dictate that the brine be concentrated to a point near saturation.

The University of Wyoming model is entirely predictive, and is based upon transport correlations taken from the literature. In the current version of the model, all processes assumed to be mass transport controlled. This generally represents the most optimistic scenario. For example, the inclusion of finite kinetics for the reaction between sodium hydroxide and sodium bicarbonate would only reduce the concentration of the product brine. Following similar thinking, no allowance has been made for heat losses in the surroundings. Again, the inclusion of heat losses would reduce the concentration of the output brine. Our reasoning is that if the model in its current state of development fails to predict favorable results, then there is no need to consider the process further.

The following process variables have been explored: (1) solvent composition (pure water or caustic solution in various concentrations), (2) flow rate (5-50 gpm), (3) well spacing (100-300m), (4) temperature 25 degrees C-100 degrees C), and (5) recycle ratio (0-50). The calculations span the transition from a process initially dominated by forced convection to a process initially dominated by free convective mass transport as the cavity enlarges. Only in the latter stages of operation, i.e., free convective dissolution, does the process begin to become attractive. Our calculations indicate that a two-well solution mine started from scratch will initially produce very low concentrations of brine with only nominal improvement as time progresses over a period of years. The reason for the poor performance is the limited rate of mass transport, and not the often touted binding of the trona surface by sodium bicarbonate. On the other hand, solution mining of a large diameter cavity such as an existing mine appears to be much more attractive.

The Wold Benetron Process

by Wayne Hazen, Hazen Research, Golden, CO

tel. (303) 279-4501 fax (303) 278-1528

The Wold Benetron process produces soda ash from trona by dry separations methods. It is based upon the characteristics of the mineral impurities associated with the trona and the degree of liberation as a function of particle size. This paper discusses the mineral associations for bed 17 trona and how they impact dry separation methods.

The Beypazari Trona Deposit, Ankara Province, Turkey

by Cahit Helvaci, Professor, Dokuz Eylül University, Izmir, Turkey

tel. 90-232-3881089 fax 90-232-3742373

The Beypazari district is a large area of volcano-sedimentary rocks of Miocene age in the interior of the Central Anatolia situated approximately 100km northwest of Ankara. Trona, lignite, and bituminous shale occur in the lower part, and sodium sulfate and gypsum occur in the upper part of the sedimentary sequence in the Miocene Beypazari basin.

The trona deposit, located north of the village of Zanviye, is associated with shale in the lower part of the Hirka Formation and alternates with bituminous shale and claystone. Based on borehole data, the areal extent of the deposit is estimated to be 8 km2. The trona beds were deposited as two lensoidal bodies within a 70- to 100 meter thick zone in the lower part of the shale unit. A total of 33 trona beds are known: 16 in the lower trona lens and 17 in the upper lens. The thickness of individual trona beds in both lenses ranges from 0.4 to 2 m. Isopach contours of both trona lenses are restricted by the Zaviye fault. The trona beds grade laterally into dolomitic mudstones and claystones toward the edges of the basin.

The principal sodium carbonate minerals are trona, minor nahcolite, and trace amounts of pirssonite and thermonatrite. Trona and dolomite are associated throughout the trona zone. Calcite, zeolites, feldspar, and clay minerals are the most common minerals found within the associated rocks of the trona deposit. The trona crystals, which are generally white and occasionally gray due to impurities, occur in massive units and as disseminated crystals in claystone and shale.

Leasing State Trona Lands

by Harold Kemp*, Wyoming State Land & Farm Loan Office, Cheyenne, and Ray Harris, Wyoming State Geological Survey, Laramie, WY

About one fifteenth of Wyoming's land area is controlled by the State. The Wyoming State Land and Farm Loan Board leases surface permits and mineral leases. Minerals are leased on a first-come-first-serve basis. The terms of the lease are $1.00 per acre per year for the first five years, then $2.00 per acre per year for the next 5 years. After 10 years, if there is a discovery of economically viable minerals, the lessee has the statuary right for preferential renewal of the lease at the continuing rate of $2.00 per acre, but the lessee must initiate the renewal for each ten-year interval.

The royalty rate for sodium is currently 5 percent and the State of Wyoming has been accepting the company conversion rate for trona to soda ash. Figures on the acreage of state lands under lease, revenue generated to the state of Wyoming from trona and other mineral production from state lands, and Wyoming's reliance on mineral royalties will be presented.

The History of the U.S. Soda Ash Industry

by Dennis S. Kostick, U.S. Geological Survey, Reston, VA

tel. (703) 648-7715 fax (703) 648-7722

The first International Soda Ash Conference (ISAC) being held in June 1997 celebrates the beginning of the Wyoming trona industry as we know it today. Fifty years have passed since the Westvaco Chemical Corp. (now known as FMC Corp.) sunk the first mine shaft into the Green River Basin in Wyoming, and workers stood upon the top of bed 17 for the first time. Since then, more than 200 million tons of soda ash have been produced from this mine and the four others that joined the industry in the following years.

To appreciate the significance of Westvaco's endeavors, we need to recall the achievements and events that helped shape the history of the U.S. soda ash industry. The history begins with the Jamestown settlers in 1607 that needed a source of alkali to manufacture their glassware, and continues through the late 1800's and into the twentieth century, when natural sodium carbonate deposits were being developed in the West and synthetic soda ash plants were being constructed in the East.

Most of these older operations have vanished with very little physical evidence remaining to show they once existed. They have become distant memories, but their successes, and failures, are the foundation of the present U.S. soda ash industry. Some of the technical achievements and accomplishments by some of the individuals attending this conference today will be added to the history our successors will be reading about in the future.

Trona Solution Mining Feasibility

by Wolfram Kube* and Edward C. Rosar, consultants, Denver, CO

tel. (303) 773-8265

This paper discusses the present status of solution mining cavities which are developed by directionally-controlled drilling techniques to produce confined elongated cavities as opposed to hydrofractured cavities. Drilling accuracy, effecting communication, and projected costs of drilling and completion are covered. Also, estimated operating costs for proprietary technologies as developed by the authors are included for the congruent dissolution of trona in a temperature range of 22 degrees C to 100 degrees C. These technologies are applicable to solution mining directionally drilled cavities and/or abandoned underground workings.

Wyoming Trona: A Geological Overview

by R. Terry Leigh, Tg Soda Ash, Inc., Granger, WY

tel. (307) 875-2700

Trona, an evaporite mineral of the compound sodium sesquicarbonate, was precipitated in a lacustrine environment during the restrictive stages of the Eocene Wilkins Peak Member of the Green River Formation in southwestern Wyoming. At least three textural variations of trona are observed in the thickest 25 trona beds which indicate multiple depositional scenarios.

Characteristic depositional features are observed with each textural form: light brown, fine-grained to amorphous, to "maple-sugar" type trona; amber, translucent, coarse-crystalline, random to radiating rosettes, referred to as "root beer" trona; and clear, crystalline, vertically oriental columnar "spar" type trona.

Hydrocarbon Phases in the Oil Shale of the Green River Basin of Southwestern Wyoming

by Gordon G. Marlatt, University of Wyoming, Laramie, WY

tel. (307) 742-6736

Three hydrocarbon phases with separate genetic pathways have been identified from the oil shale in the Green River Basin of southwestern Wyoming. Two phases were recognized in core from a drill hole in the central part of the basin. The first consists of a paraffin-like material that was deposited with the trona on the bottom of Lake Gosiute. This material appears to be the waxy portion of the organics that was not susceptible to dissolution by the high pH lake brines and that precipitated from suspension with the trona. The second is tar that evolved, upon burial-related heating, from the kerogen that partially forms the oil shale itself. The third is the organic portion of the black trona brines found in geopressured reservoirs in the northern part of the basin. This last is not strictly a hydrocarbon but comprises humic and fulvic acids, the base-soluble algal components subsequently rained to the bottom of the lake to form the pre-kerogen portion of the muds. The genetic pathways of these three hydrocarbon members will be discussed.

Terms and Conditions of the Federal Leasing Processes

by Ted Murphy, U.S. Bureau of Land Management, Rock Springs, WY

tel. (307) 352-0321 fax (307) 352-0328

Competitive leasing is the procedure for offering to the public mineral deposits which are not under an outstanding permit or application for preference-right lease. The BLM advertises and conducts competitive mineral sales of certain Federal lands. Lands which are classified as known to be valuable for leasable minerals, are subject to competitive leasing. Competitive leases containing sodium mineral deposits are offered to the highest bidder(s) at a sale, provided that the amount of the bid(s) equals or exceeds the fair market value.

Soda Ash Goes Global for Growth

by Charles Raleigh*, Chem/Minerals Marketing Services, Princeton Junction, NJ, and Peter Harben, P.W. Harben, Inc., Morris, NY

tel./fax (609) 799-0681

The United States soda ash industry owes much of its success over the past decade to an increase in its sales to markets outside of the U.S. While total U.S. soda ash production grew from 8.4 million short tons in 1986 to 11.2 million tons in 1996 (a 2.9 percent annual growth rate), U.S. exports increase from 2.1 million tons to 4.2 million tons (a 7.2 percent annual growth rate). Domestic demand, on the other hand, grew at a more modest 1.0 percent rate.

Exports now account for 38 percent of all U.S. soda ash sales. This paper looks at some of the reasons behind the U.S.'s success in the world export market, and takes a brief look at what the future may hold for the soda ash industry worldwide.

Soda Ash: A European Producers Perspective

by Brian Rischmiller, Brunner Mond Ltd., Northwich, Cheshire, England

tel. 44-1606-724195 fax 44-1606-724433

This paper considers areas of world consumption and growth, suggesting that the areas of greatest growth will be those recovering from political turmoil and third world developing economies.

The alternative methods of production of soda ash are reviewed and the place of the synthetic producer is considered. There have been significant developments in the technology of the synthetic process in recent years, making it not only more efficient and cost effective, but also removing the environmental disadvantages from which it has suffered over many years.

These, plus business re-engineering of the operating companies,means that the cost base of several companies operating the synthetic process has reduced significantly, making them able to compete easily with soda ash produced from other sources and delivered into the synthetic producers home markets.

Trona Tailings Disposal Methods

by David Scriven, Western States Mining Consultants, Casper, WY

tel. (307) 266-9117 fax (307) 235-7086

Trona is currently being produced from beds 17, 20, 24, and 25 in the Green River Basin, Wyoming. These trona beds are comprised of sodium sesquicarbonate (trona), oil shale, mudstone, and claystone. The trona beds are underlain and overlain with oil shale, mudstone, and claystone. The mining processes mine the trona bed and periodically portions of the underlying floor and overlying roof rock. The resultant feedstock to the plants range in purity from a low of 75 percent to a high of nearly 95 percent trona.

Each of the five operating plants uses a process to dissolve the trona. The portion which is non-soluble, the oil shale, mudstone, and claystone, is referred to as insols or tailings and must be disposed of. The methods to dispose of the tailings differ for each of the operations. Both surface and underground methods are used and range from rather simple to highly sophisticated processes. Basically, five disposal methods are used in the basin.

The methods are: (1) Surface-non-managed; this method transports tailings via slurry pipelines to a tailing reservoir and deposits the tailings in a single point discharge. (2) Surface-managed; tailings are transported via slurry pipelines to a tailings reservoir using a multi-point discharge system for controlled deposition. (3) Underground-non-managed; tailings are pumped down blind drill holes into mined out, inaccessible ares of the mine, (4) Underground-managed; tailings are pumped into the mine through a pipeline installed in the shaft and into mined out, accessible areas of the mine. Retaining walls are constructed to contain the tailings in the mined out rooms. (5) Underground-highly managed; tailings are converted to a low-liquid paste and pumped into mined out, accessible areas of the mine.

History of Leasing Union Pacific Railroad Trona Lands

by Robert See* and Neil Brown, UP Resources-Minerals, Fort Worth, TX

tel. (817) 877-6738 fax (817) 877-7260

This paper will describe the history of the Union Pacific Land Grant and the leasing of Union Pacific trona resources in Wyoming. It will begin with the discovery of pure massive trona in the John Hay, Jr. #1 well by Mountain Fuel and will outline the role of Union Pacific in the promotion, development, and production of soda ash. The subsequent leasing and development activities of the five current soda ash producers is also described.

The Role of Soda Ash in the Chloralkali Family of Chemicals

by Roger E. Shamel, Consulting Resources Crop., Lexington, MA

tel. (617) 863-1222 fax (617) 863-1441

Soda ash plays a unique role in the chloralkali family of chemicals. Its long-term outlook depends on the outlook for chlorine and caustic soda. Predictions for the growth of the latter two products vary, with the latest thinking increasingly favorable towards a reinvigoration of chlorine growth. A significant imbalance between chlorine and caustic typically creates substitution problems or opportunities for soda ash. This paper will explore the key relationships linking soda ash to chlorine and caustic soda (both electrolytic and "chemical" forms), offer some thoughts on the evolution of the ever-changing chlorine regulatory scene, and conclude with a likely scenario for the resulting impacts on soda ash.

Trona Crystallization: Observations During 1970-77 at Owens Lake, CA

by George I. Smith*, U.S. Geological Survey and Irving Friedman, Menlo Park, CA and Denver, CO

tel. (415) 329-5188

During the winter of 1968-69, runoff from the Sierra Nevada caused fresh water to flood normally dry Owens Lake and dissolve the top 20 percent of its 2.5 m thick salt layer which is composed primarily of trona, halite, and burkeite. Recrystallization of the dissolved salts started in August 1970 and was completed by August 1971. Using observational, chemical, mineralogical, and stable-isotope data, we monitored from the primary deposition of, and subsequent seasonal changes in, the CO3 and HCO3 bearing minerals because they best illustrate how complex crystallization processes can be. Isotopic data from core samples showed that seasonal changes were still occurring in 1977.

Soda Ash Industries of Russia and Ukraine

by Charles Watts-Jones, Chem Systems Ltd., London, England

tel. 44-171-839-4652 fax 44-171-930-1504

The USSR used over 5 million tons of soda ash in 1985 when it represented more than 18 percent of global consumption. Although the country had production capacity nominally capable of supplying its domestic requirements of soda ash, it was in fact a significant importer of ash from other COMECON member states. The region's consumption of soda ash fell in the following years with the decline becoming precipitate following the introduction of economic reforms. By 1996, regional consumption was under 3 million tons, less than 10 percent of global consumption.

Approximately 15 percent of the FSU's production capacity is based upon nepheline as its raw material, the remainder uses the conventional ammonia-soda (Solvay) synthetic process. Production from natural sodium carbonates, which was always small, stopped in the mid 1970s.

This paper reviews the operating characteristics of the region's eight soda ash sites and examines historic consumption patterns. In conclusion it considers the outlook for the industry in the coming years.

The Anomalous Zone in Trona Bed 17, Green River Basin, Wyoming

by Michael Weller, Solvay Minerals, Inc. Green River, WY

tel. (307) 872-6548

The anomalous zone is an area of mineralogical and physical changes in trona bed 17 between mixed halite and trona mineralization and "normal" trona. The principal changes in the anomalous zone are the presence of major quantities of wegscheiderite (Na2CO3.3NaHCO3) and nahcolite (NaHCO3) in the bed, changes in the roof and upper insoluble bands of the bed to a rock consisting of northupite, shortite, and quartz, and a thinning of the bed thickness. This paper examines the nature of the anomalous zone from core and underground workings and discusses its effect on mechanical mining.

Developments in the European Soda Ash Market 1990-1996

by Tony Whiteside, Harriman Chemsult Ltd., London, England

tel. 44-171-490-5100 fax 44-171-490-3991

The 1990s have seen Solvay consolidate its position as the biggest soda ash producer in Europe. Also in this decade, ICI and Rhône-Poulenc have sold off their operations and the Bulgarians and Poles have privatized their industries. The collapse of the Soviet empire had a catastrophic effect on domestic East European soda ash markets at the beginning of the 1990s, from which they are only slowly recovering. Looking ahead to the rest of the decade and into the early part of the next millennium, there will probably be further rationalization and integration in the European soda ash industry. East European soda ash consumption will see some growth as regional economies benefit from closer relationship with the EU, but there will be very little growth in Western Europe.

Trona Resources of Wyoming (poster)

by Stephen V. Wiig*, U.S. Bureau of Land Management, Rock Springs, WY and John R. Dyni, U.S. Geological Survey, Denver, CO

tel. (307) 352-0321 fax (307) 352-0328

A chart in two sheets summarizes the economic geology of trona deposits in the Wilkins Peak Member of the Eocene Green River Formation in the Green River Basin in southwest Wyoming. The first sheet includes a structure map of the Green River Basin drawn on the base of the Wilkins Peak Member, a generalized columnar section of the Wilkins Peak Member showing numbered beds of trona, oil shale, marlstone, and mudstone-sandstone based on earlier work by W.C. Culbertson, and a summary of the trona resources. The second sheet shows isopach maps of currently mined trona beds 17, 20, 24, and 25, as well as eight other thick beds of trona of economic interest. A summary of the chemistry of the trona beds is on the second sheet.

A New Entrant's Perspective of the Wyoming Soda Ash Industry

by John Wold, Wold Trona Co., Casper, WY

tel. (307) 265-7252 fax (307) 265-7336

Wold Trona Company's entry as the sixth Green River Basin soda ash producer is the culmination of 30 years' acquisitions of prospecting permits and sodium leases. The large investment requirements of the conventional monohydrate mine/plant operations has led the Wold approach to conventional underground mining and dry beneficiation of trona ore to 98 percent purity soda ash (Benetron process) acceptable to a major portion of world markets.

The fines and rejects of the dry process has led Hazen Research to pursue the successful development of a revolutionary "Crystaltron" process, a 99.5+ percent soda ash product, which has significant economic and physical advantages over the current Green River monohydrate product.

The Natural Soda Ash Deposits of China

by Professor Zhang, Chending, Inner Mongolia Polytechnic University, Hohhot, China

fax 86-471-6963298

The total production of soda ash in China in 1996 was about 6.5 million mt. The proportion of exports to output was about 8.5 percent. Synthetic soda ash has always dominated the soda ash industry in China. The synthetic soda ash production of China has expanded rapidly in the last 20 years, and the natural soda ash deposits of China have been developed simultaneously. Four natural soda ash deposits are introduced in this paper, two in Henan Province and two in Inner Mongolia Autonomous Region. The character of the deposits, their components of sodium carbonate-bearing minerals, and their reserves are described. Exploration methods, refining processes, and basic studies are explained and a brief evaluation of the deposits is presented. The current status of the Chinese synthetic soda ash plants and markets is summarized.