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By K. A. Wheeler

To evaluate the effects on groundwater of a proposed in-pit disposal operation at an east Texas lignite mine, the local geologic, hydrogeologic, and geochemical features were thoroughly characterized. Resultant data were used in a flow and transport model (SWIFT) to simulate migration of the ash leachate. Computer simulations indicate that the leachate plume will travel 61-152 meters from the disposal area in 100 years after resaturation of the spoils. A 61-meter buffer zone of mine spoils without ash will surround the disposal area. The proposed landfill operation received regulatory approval and is currently operating as a Class 2 non-hazardous landfill.

Jan 1, 1994

By Zvi Rivlin

Classical nucleation theory states that in first order phase transformations, such as liquid to solid transition, nucleation of the product phase starts with the formation of small, unstable clusters (embryos). When the thermodynamic barrier to nucleation is overcome, the embryos grow and attain a critical size, beyond which they are stable, i.e. they become nuclei. If nucle- ation does not occur, the parent, liquid phase remains in metastable equilibrium. At temperature lowers, undercooling increase and atomic mobility decreases. The viscosity change in the undercooled liquid may result in the formation of glassy state. As demonstrated in previous papers [I-21, in solidification involving surface nucleation of the product phase, as the case is in rapid quenching by melt-spinning, both nucleation temperature and nucleation time depend upon the number of atoms available at the isothermal surface in contact with the substrate. As a result of the thinness of the melt-spun ribbons, the embryo clusters that form at the freezing temperature may not be supplied by the amount of atoms necessary for their growth to critical nuclei sizes. In such extreme conditions, the liquid does not crystallize, it forms a metallic glass. A numerical simulation method is proposed for the reactions involved in embryo cluster formation and growth, at the atomic level. The simulation enables the caIcuIation of either the nucleation or the glass transition temperatures. Calculations made for the well-known glass forming CuZr and FeB systems afford prediction of the geometrical and thermodynamically conditions necessary for the formation of either crystalline or amorphous ribbons in melt-spun ribbons.

Jan 1, 1994

By J. Shahabpour

"Abstract - Breccias with angular and rounded clasts of a late-mineralization, ""barren"" hornblende porphyry dike set within a comminuted matrix consisting of rock fragments and quartz, cemented by quartz and K-feldspar of hydrothermal origin is observed in diamond drill cores from the Sar Cheshmeh porphyry copper deposit. Studies of age relationship between vein types, phyllic-altered clasts and the breccia groundmass suggest that the brecciation is a late event. The breccia clasts record evidence of hydrothermal reaction between the clasts and fluids responsible for the brecciation.Formation of bornite, in the breccia clasts of the originally barren hornblende porphyry dike, and in the breccia matrix, along with the scarcity of bornite in the Sar Cheshmeh deposit itself suggest involvement of fluids which are later and of different composition from the fluids responsible for the known mineralization at Sar Cheshmeh. These later fluids may be related to a later plutonic event and suggest the possibility of a later, and concealed deposit."

Jan 1, 1994

AQUILA Mining Systems Ltd., designs, develops and delivers systems for measurement, analysis, simulation, control and automation to the mining, construction and petroleum industries. The objective of current efforts by AQUILA is the continued development and refinement of computerbased systems and techniques to automatically process monitored performance data from surface blasthole drills and mining shovels, and the management and coordination of these pieces of equipment by GPS (Global Positioning Systems).

Jan 1, 1994

By Sridhar Komarneni

"Microwave-hydrothermal processing is a novel technique which combines the conventional hydrothermal processing with microwave field and we previously showed for the first time, that ceramic powders can be rapidly produced by this technique. This review paper deals with the synthesis of unary oxides such as Fe203, Ti02, Zr02, etc., binary oxides such as BaTiO3, SrTiO 3, PbTiO 3, SrZrO 3, KNbO3, etc., and ternary oxides such as NaTi2 (PO4)3 and pyrochlore phases of Pb(Mg1/3Nb2/3)O3, Pb(Zn1/3Nb2/3)O3 etc. and metal powders such as Cu, Ni, etc. below 195°C. This method can be adopted to the synthesis of a large variety of powders by the appropriate control of pH, Eh, temperature/pressure and concentration of chemical species. The main advantages of this method compared to conventional hydrothermal processing are (a) it increases the kinetics of reaction by one to two orders of magnitude, and (b) it can lead to novel phases especially those with layered structures.IntroductionConventional hydrothermal processing is a well-established synthesis technique which has been extensively used in the preparation of fine ceramic powders [1-5], large single crystals [6-8] and massive cement blocks [9]. Technologically important ceramic powders such as BaTiO 3, Al203 etc. made by the hydrothermal process are now commercially available. Although there are numerous methods for materials synthesis, hydrothermal method is truly a low temperature and environmentally benign process. For example, ZrSi04 (Zircon) which is extensively used in ceramic industry can be prepared hydrothermally at 150·C [10] compared to sol-gel or solid-state method [11,12] which require a temperature of about 1000·C. The hydrothermal method is environmentally benign because hydrothermal reactions are carried out in closed systems at low temperatures and the contents can be recovered and recycled after cooling to the ambient conditions. One of the disadvantages with any low temperature processing method is slow kinetics. For this reason we have combined the hydrothermal method with microwaves to enhance kinetics and we named this method as ""Microwave-hydrothermal"" processing [13- 16]. Although the combination of microwave and hydrothermal techniques has been used in the past few years to dissolve all kinds of inorganic (e.g. alumino silicate rocks) and organic materials rapidly for chemical analysis, we were the first to show its potential value for the synthesis of various ceramic powders [13-16]. In this paper, I show that this novel method is applicable to the synthesis of all unary, binary and multinary oxides by the appropriate control of pH, Eh, temperature, pressure and concentration of chemical species. In addition, this method is also found to be useful for the preparation of metal powders."

Jan 1, 1994

By M. J. U. T. Van Wijngaarden, A. T. Pieterse

An account is given of the performance of a 37 MVA electric-arc .furnace in which bottom stirring with inert gas by an indirect-contact stirring-plug system was applied. The system, which was developed and patented by Thyssen-Stahl AG, and which is the first inert gas stirring system to be installed in South Africa, was commissioned in January 1992. Initial problems were experienced due to the blockage of stirring plugs by molten steel. The causes of these malfunctions are examined, and an account is given of how they were overcome. The system is described and evaluated. A comparison with direct-contact stirring systems shows why Iscor Vereeniging Works considered it to be more suitable for their Vaal Melt Shop. The results show that, through the successful application qf this technology, Iscor Vereeniging Works has achieved an annual cost saving of more than R2,5 million.

Jan 1, 1994

By Keith Eldridge, Robert Kelly

"Quality management has a/ways played an important role at the Iron Ore Company of Canada; particularly since the early eighties when the iron ore markets favoured buyers as opposed to sellers.Since thot time, IOC's quality system has evolved from basic quality control to the Deming philosophy and its 14 points, and on through various other phases to the ISO 9000 series.ISO 9002 Registration was' first requested by IDC's customers and development plans were prepared in 1988. At this time, Quality System Registration was unheard of in the mining sector and TDC found itself struggling with the concept. The 1U!Xt three years saw the company develop a Quality System to meet ISO 9002 in a two phased approach, setting new standards for the mining industry when registration was achieved in December 1991.The company now sees ISO Registration as the cornerstone of its future quality efforts. IOC's quality system has been integrated with several other initiatives such as loss control and functional training, both of which focus on training and management the workforce to do the job safely, the right way.This paper addresses the steps required to develop a quality system for the mining industry within the guidelines of the ISO 9000 Series and the subsequent integration of other quality related initiatives."

Jan 1, 1994

By Kenneth Pidgeon

The Boston Marine Industrial Park (BMIP) Boat Section, which is part of contract C04A2 of the Central Artery/Tunnel (CA/T) project, is currently under construction in South Boston, Massachusetts (Fig. 1). The Boat Section is approximately 900 feet long and varies in width from about 135 to 185 feet (Fig. 2). The depth to the top of the Boat Section base slab varies from about 28 to 31 feet below final ground surface and about 23 to 26 feet below normal ground water levels. The Boat Section is supported on 578 anchors drilled into the underlying bedrock each designed for a working load of 630 kips. Design and Construction Team The owner of the project is the Massachusetts Highway Department (MHD). The owner's representative is the Management Consultant, Bechtel/Parsons Brinckerhoff. The section design consultant (SDC) consisted of HDR Engineering, Inc. with GEI Consultants, Inc. as the geotechnical subconsultant. The general contractor was the joint venture of Kiewit, Perini, Atkinson, and Cashman. The boat anchors were installed by the subcontractor Delta Geotechnical Services, Inc.

Jan 1, 1994

By Nott M. C

The oxidation of xanthate collectors to xanthate/dixanthogen results in a higher hydrophobicity of sulphide minerals surfaces due to the action of dixanthogen. This higher hydrophobicity can be proved on a fundamental level by examining the st

Jan 1, 1994

By J. L. Ellenberger

The U.S. Bureau of Mines has cooperated with Cyprus Casa Grande Corporation Cyprus Casa Grande Mine, Cas a Grande, Arizona, since 1988 to assess the hydrology of an in situ leaching test facility. This work has resulted in an in situ design for leaching copper oxide ore that takes advantage of the increased mineral access associated with poor quality rock surrounding mine drifts. Blasting and bulkheads are used to produce readily-leachable rubble and contain and control solution movement, respectively. The design reduces the need for handling solution under high pressures in an injection/recovery system for in situ leaching of underground ore bodies. Early work at the site recognized a stress redistribution zone and increased transmissivity near drifts. Fracture data from a corehole oriented parallel to the dip of the ore body indicated an increase in fracture frequency around drifts a distance of 21 m (70 ft) away from the 5 m (16 ft) diameter drifts.

Jan 1, 1994

By P. G. Kovalchik

Safe electrical operation of shuttle cars depends upon maintaining the trailing cable's conductor temperature below 90° C. However, trailing cables are wound on and off reels, which changes the heat transfer characteristics of the cable-reel system. Derating factors for trailing cables are an attempt to adjust for this changing heat transfer mechanism in a practical way. The U.S. Bureau of Mines conducted research to determine acceptable derating factors for reeled mine trailing cables, using four cable-reel combinations, representative of industry usage. Cables were continuously and intermittently loaded at different duty cycles with direct currents of different magnitudes. Relationships between the average temperature rise and current load were established for each layer of each cable. Two models were constructed; one used empirical data from the continuous and intermittent load tests, and the other was based on thermodynamic theory. Results obtained from the theoretical model were compared with those from the empirical model for the rated temperature rise of the cable. Both models can be used to simulate a variety of test conditions including those that normally cannot be conducted in the laboratory. This information was used to determine acceptable derating factors for each layer of these cable-reel combinations.

Jan 1, 1994

By Jr. Gabler

The U.S. Bureau of Mines (USBM) has developed a computerized commodity flow model for strategic and critical materials This flow model is generic and applicable to most commodities and amenable to updating supply, demand, and/or production data change. The original model, with slight modifications, was used to track the flow of chromium. This report follows the flow of chromium through its metallurgical, chemical, and refractory applications, and highlights areas where significant losses occur because of downgrading, export, or disposal. The study indicates that materials containing 451,769 mt of chromium were consumed, including 99,221 mt of chromium from recycling, Chromium losses from all causes in 1989 were estimated to be 345,347 mt from a variety of areas. These areas and their chromium losses are as follows: processing losses, 38,825 mt; processing-downgraded scrap, 18,227 mt; manufacturing losses, 18,128 mt; manufacturing-downgraded scrap, 56,595 mt; prompt scrap exported, 1,531 mt; obsolete scrap exported, 43,443 mt; recovery losses, 155,529 mt; and recycling losses, 13,069 mt. Recycled chromium-containing material accounted for 22 pct of the apparent consumption of chromium in 1989.

Jan 1, 1994

In late 1993, Inco Ltd. completed a $600-million environmental improvement project at its Sudbury, Ontario operations -the largest single environmental project ever undertaken by a Canadian corporation. Efficient new facilities and innovative technologies installed during the course of the project have also significantly improved Inco's productivity and competitiveness. In early May 1994, a panel of 18 Inco authors contributed to a Technical Forum, "Environmental Programs at Sudbury," presented at the 96th Annual General Meeting of the Canadian Institute of Mining, Metallurgy and Petroleum (CIM) in Toronto. Their papers have been published in CIM's Toronto `94 Proceedings Volume, pp. 62-77. The following report draws primarily on discussions of Inco's milling and smelting operations published in the Proceedings Volume. The Proceedings Volume also includes papers on the acid and oxygen plants and on engineering, construction and commissioning of the project. The 222-page Proceedings Volume is available from CIM, $C27 plus shipping. To order, contact: V. Ward, CIM, Xerox Tower, 1210-3400 de Maisonneuve Blvd W, Montreal, Quebec, Canada H3Z 3B8; phone 514-939-2710, fax 514-939-2714. Lane White, Publisher.

Jan 1, 1994

AUSTRALIA CHAPMAN Gary JOHN WAGSTAFF CONTSRUCTIONS PTY. LTD. 1 Ashgrove Crescent 4060 ASHGROVE BRISBANE HILLAR Jaaes Director J.A. HILLAR & ASSOCIATES 99 Woolwich Road WOOLWICH, NSW 2110 WAGSTAFF John Managing Director JOHN WAGSTAFF CONSTRUCTIONS PTY. LTD. 1 Ashgrove Crescent 4060 ASHGROVE, BRISBANE AUSTRIA FUCHSBERGER M. TECHNISCHE UNIVERSITAT INSTITUT FUR BODENMECHANIK Rechbauerstrasse 12 8010 GRAZ

Jan 1, 1994

By G. T. Austin

Every year the United States consumes millions of dollars worth of abrasive materials as blasting media. Entrained in either a gas or liquid stream or propelled by paddles or wheels, they are directed onto the surface of another material to modify that surface. The modifications to impacted surfaces include cleaning, cutting, deburring, etching, finishing, and peening. Blasting media can be either organic or mineral abrasive materials. Information and data presented are for only a portion of the mineral abrasives, they are; fused aluminum oxide, coal slag, copper slag, garnet, metallic shot and grit, nickel slag, olivine, silica sand, silicon carbide, and staurolite.

Jan 1, 1994

By Robert C. Freas, Donald D. Carr, Lawrence F. Rooney

Perhaps no other mineral commodities in this volume have as many uses as limestone and dolomite. These carbonate rocks are the basic building blocks of the construction industry, the material from which aggregate, cement, lime, and building stone are made. Carbonate rocks, and their derived products, are used as aggregates, fluxes, glass raw material, refractories, fillers, reactive agents in sulfur-oxide removal, abrasives, soil conditioners, ingredients in a host of chemical processes, and much more. Although the use of limestone and dolomite goes back before recorded history, new uses and products are continually being found. Carbonate rocks form about 15% of the earth's sedimentary crust and are widely available for exploitation. Found extensively on all continents, they are quarried and mined from formations that range in age from Precambrian to Holocene. Reserves of carbonate rock are large and will last indefinitely, although high-purity deposits may be absent or have limited availability in certain areas. Limestone and dolomite are so useful and so abundant that in 1989 about 798 Mt were produced in the United States. In fact, about 75% of all stone quarried or mined in the United States was carbonate rock. Sand and gravel was the only mineral commodity produced in greater quantity. In this chapter we have sought to provide the general reader an overview of carbonate rocks, their composition, distribution, production, and uses. The literature on the limestone and dolomite resources of the United States and Canada is so vast and diverse that one can easily become mired in print. We tried to list those references that are easily accessible and that provide the economic geologist with a starting point for more intensive study. The table listing selected references on limestone and dolomite resources in Canada and the United States reflects our attempt to be selective rather than exhaustive and to direct the reader to the best sources of detailed information.

Jan 1, 1994

By Haydn H. Murray, Fred G. Heivilin

The "Hormite Group" was proposed for palygorskite (attapulgite) and sepiolite for their complex magnesium silicate composition and elongate crystals (Martin-Vivaldi and Robertson, 1971). These minerals occur in close association with each other and more complex structural variations may exist (Bailey, 1972). In 1862 Savchenkov used the name palygorskite to describe a mineral from the Palygorsk locality (Hay, 1975), near the Ural Mountains. Ovecharenko and Kukovsky (1984) mention that when mountain leather deposits were prospected in the Palygorsk Division mine it was assumed this unusual mineral was a variety of asbestos. Early mineralogists used the terms "mountain cork" or "mountain leather" when referring to palygorskite. Robertson (1986) mentions that it appears palygorskite was known since Theophrastus&apos; time, ca. 314 BC. J. de Lapparent used "attapulgite" for clays from Attapulgus, GA, and Mormoiron, France, because he thought them different from palygorskite, but the two types were proved to be the same (Bailey et al., 1971). The name attapulgite is still used for the Florida and Georgia deposits when the crystal length to diameter ratio does not exceed 10:1(Merkl, 1989). Georgia palygorskite clays are of much shorter length compared to classic palygorskite. In 1847 Glocker first used the name sepiolite which was called "Meerschaum" by Werner (1788) and Hauy (1801) namedit "Ecume de Mer." Brochant (1802) described low density and white magnesium silicates adding the name Talcum Plasticum and Ecume de Mer. In the Meigs-Attapulgus-Quincy district palygorskite (attapulgite) commonly occurs in two distinct forms referred to as short length palygorskite (Meigs Member) and long length palygorskite (Dogtown Member) (Merkl, 1989). Long length palygorskite crystals (> 10 pm) are rarely observed in the Meigs and Dogtown Members, but when present are in association with dolomite crystals. The short length form is usually less than 2 pm in length and has a low magnesium content whereas the long length form has a high magnesium content and a length greater than 2 pm. The distinctions in morphology are not only important because of the relationship to the origin of the deposits, but also in relation to activity in causing membranolytic activity related to data on palygorskite samples from 9 locations ranging from relatively inert to active in work reported by Nolan et al. (1989). The > 10 pm lengths amounted to only 51 of 17,401 fibers sized. The shortest lengths (< 0.5 pm) were relatively inert. This study pointed out that surface activity, morphology, and chemical differences may be distinctly different within the definition of palygorskite, or for that matter for any individual mineral so that health and other properties must be measured because the name alone does not necessarily indicate uniformity. Palygorskite (attapulgite) fuller&apos;s earth was first sold for drilling mud in 1941. The market for this use expanded slowly and has maintained a level of 7 to 10% of the total US production during the last few years. Most of the fuller&apos;s earth sold for drilling mud comes from the southern part of the Meigs-Attapulgus-Quincy district of Georgia and Florida. Palygorskite clays produced in this area are superior to most other fuller&apos;s earth for mud used in drilling salt formations, but because of high water loss, they are inferior to bentonite where the rocks drilled contain no saltwater. According to Oulton (1965), more than 90 different grades of fuller&apos;s earth are produced. Some of these grades are used for pharmaceuticals designed to absorb toxins, bacteria, and alkaloids; for treatment of dysentery; for purifying water and dry cleaning fluids, dry cleaning powders and granules; for the manufacture of NCR (no carbon required) multiple copy paper; for the manufacture of wallpaper; and as extenders or fillers for plastic, paint, and putty. Fuller&apos;s earth mined near Ellenton, FL, was used for making lightweight aggregates for the construction of concrete barges during World War I1 (Calver, 1957). Still other uses of fuller&apos;s earth and its suitability for uses in new products are outlined by Haden, Jr., and Schwint (1967), Haden, Jr., (1972), and Haas (1970). One special use of fuller&apos;s earth is as a carrier of platinum catalysts that are made in the United Kingdom from sepiolite clays mined in Spain. Other uses of sepiolite fuller&apos;s earth (Chambers, 1959) are similar to those of the palygorskite (attapulgite) type mined in the United States.

Jan 1, 1994

By Godwin J. Igwe

For soil remediation technology to be effective, a thorough understanding of the interactions between a targeted contaminant and the soil matrix is crucial. Proper selection of remediation technology, based on understanding the bonding/binding characteristics of the soil and contaminant, can often result in significant remediation cost savings. Contaminated soil cleanup is complicated by both the physical nature of the soil formation and the behavior of contaminants introduced into the formation. Contaminants can exist in the subsurface in different phase attached to the soil surfaces, dissolved in the ground water, or occupying pore spaces as a separate gaseous or liquid phase. Contaminants properties and how they exist in the subsurface influence their toxicity, mobility and treatability with different remediation technologies A soil characterization study was performed to provide information for remediation technology selection for an inorganic lead contaminated soil. The soil pH, TCLP analysis, thermogravimetric analysis, the soluble anions and cations present, equilibrium leaching tests, analysis by x-ray fluorescence, sequential extractions and speciation analysis using scanning electron microscopy, were all used. Results provided many insights into contaminant behavior in the soil, indicating ultimately whether soil washing or solidification/ stabilization remediation technologies were applicable.

Jan 1, 1994

By Erhard M. Winkler

The rapid decay and disfiguring of stone monuments in urban and desert rural areas has challenged conservators to protect stone surfaces from premature decay. They attempt to halt the natural process of stone decay and possibly to restore the original strength lost mostly by chemical weathering and the loss of binding cement. Ageneral solution is not possible because the physical and chemical characteristics must be considered for different stone types. The failures of stone preservation and restoration are greater in number than the cures. The need for repair of stone decay goes back to evidence of Roman replacement of decaying stone. The presence of excess water in buildings has long been recognized. Moisture tends to enter masonry from air in humid climates, a most important but often underrated factor (Fig. 1) suggesting that sealing should be the answer. Undesirable staining and efflorescence result in accelerated scaling. Today, the great variety of chemicals available to the modem conservator for sealing. consolidating, or hardening stone fall into two very different categories: surface sealers and penetrating stone consolidants, or a combination of both. SEALERS Sealers develop a tight, impervious skin which prevents access of moisture. Surface sealing has saved monuments from decay by eliminating the access of atmospheric humidity. Pressure tends to develop behind the stone surface by moisture escape. Efflorescence, crystal growth action, and freezing can cause considerable spalling (Anderegg, 1949). Flaking results when moisture is trapped behind the sealed surface. Yellowing and blotchiness are also frequently observed. The following sealants are in common use today: linseed oil, paraffin, silicone, urethane, acrylate, and animal blood on stone and adobe. Extensive cracking and yellowing has resulted soon after application. In the past many such treatments have created more problems than cures: 1. Linseed oil and paraffin have been in use for centuries. Embrittlement and yellowing occur rapidly because these are readily attacked by solar ultraviolet radiation. 2. Animal blood as paint has temporarily waterproofed adobe mud and stone masonry. The origin of blood paint has a religious background rooted in the Phoenician and Hebrew cultures. Instant water soluble dried blood can substitute for fresh blood. Winkler (1956) described the history and technique of the use of blood. 3. Silicones have proven very effective and are long lasting. In contrast, acrylates, urethane, and styrene are generally rapidly attacked by UV radiation (Clark et al., 1975). Sealing of Different Rock Types Granitic rocks have a natural porosity traced to 4.5% contraction of quartz, during cooling of the parent magma, compared with only 2% contraction of all other minerals; protection against the hygric forces may require waterproofing of granite in some in- stances. The Egyptian granite obelisk in London is an example. Soon after its relocation from Egypt to London, Cleopatra&apos;s Needle was treated, in 1879, with a mixture of Damar resin and wax dissolved in clear petroleum spirit; surface scaling became evident after half a year of exposure to the humid London atmosphere. The treatment of the ancient granite monument from Egypt has denied access of high relative humidity (RH) in London to the trapped salts inherited from the Egyptian desert and has protected the monument from decay (Burgess and Schaffer, 1952). The sister obelisk set up in Central Park, New York City, has fared less favorably because similar treatment was done too late, only after the salts hydrated and hundreds of kilograms of scalings disfigured the obelisk surface (Winkler, 1980). Surface coating of other common stones may be needed. Crystalline marble absorbs moisture from high RH atmospheres: dilation may ensue when curtain panels bow as the moisture starts to expand during daily heating-cooling cycles. A good sealer may prevent the moisture influx provided that no moisture can enter from the inside of the building. Limestones, dolomites and all carbonate rocks are subject to dissolution attack by rainwater, especially in areas where acid rain prevails (Fig. 2). The interaction of sulfates in the atmosphere with the stone can be halted by waterproofing to avoid the formation of soft and more soluble gypsum. The stone surface attack can be diminished if nearly insoluble Ca-sulfite crusts can form, instead of Ca-sulfate. Replacement of fluorite or barium compounds at the stone surface acts as a hardener, rather than a sealant. Sandstones have generally high porosity and rapid water travel can occur along unexpected routes and from any direction. Any surface sealing may do more damage by scaling and bursting than if the stone is left without treatment. Sealing of sandstones is therefore not advised at any time. Testing the efficiency of sealants: Several authors discuss waterproofing materials, silicones, urethanes, acrylates and stearates, as to their water absorption, spreading rates of water on the treated surface, water vapor transmission, resistance to efflorescence, and general appearance (Clark et al., 1975). De Castro (1983) measured the angle of contact of a microdrop (0.004 cm3) on a stone surface as characteristic of the wettability. Laboratory tests and limited field performance are described by Heiman (1981). The crest of a Gothic sandstone arch, which was sealed with silicone,

Jan 1, 1994

By Noel A. Genco, Edward F. McCarthy, Robert J. Piniazkiewicz

Talc, when it can be isolated as a pure mineral, has a composition of 63.36% SiO2, 31.89% MgO, and 4.75% H,O. However, as a commercial commodity less than half of all talc sold has a purity exceeding 95%. Nevertheless, impure talc products find a multitude of uses and few substitutes in many industrial applications. Minerals commonly associated with and sold together in talcose mixtures are chlorite, dolomite, mica, magnesite, and tremolite. Steatite was originally a mineralogical term applied to pure talc. Today steatite usually denotes a high-talc ceramic body used as an electrical insulator, and the talc used in such applications is known as steatitic talc. Steatitic talc generally is found in massive, high- purity form and in the past was machined directly into electrical parts, which rarely is done today. Impure varieties of massive or block talc are still commonly termed soapstone. Soft massive talc, suitable for crayon manufacture, has been referred to as French chalk. It has been common practice to discuss talc, soapstone, and pyrophyllite under the same general heading. In the case of soap- stone and talc this is natural, since many different types of platy, soft minerals exhibiting a high degree of lubricity (commonly referred to as slip) have been grouped together and called soapstone or talc. Further, there are mineralogical relationships between pyrophyllite and montmorillonite and between talc and hectorite. Thus, talc and pyrophyllite are sometimes referred to as clay minerals. When finely divided talc or pyrophyllite are combined with water in proportions to make a slurry, the end product does have the appearance of a clay-water mixture. Soapstone for utensils and ornaments was mined by prehistoric Native Americans on Santa Catalina Island, CA. In the mid- 1800s soapstone from deposits along the western foothills of the Sierra Nevada Mountains was used by white settlers as building and ornamental stone and for the linings and foundations of furnaces (Anon., 1956). Previous to 1916 the annual recorded production in California did not exceed 1.8 kt. From 1912 to 1918, however, output rose sharply when the Talc City, Western, and Silver Lake mines were put into operation. From 1916 to 1935, the state&apos;s annual output of talc was in the range of 8.2 to 18.2 kt. There was another increase in the mid-1930s, when the use of talc in wall tile grew rapidly. In California the production of talc grew to 57.2 kt in 1943. The post-war building boom helped California&apos;s production to grow to 108.9 kt in 1951. Production stood at 149.8 kt in 1968, 13 1.6 kt in 1969, 167.9 kt in 1970, and 140.7 kt in 1972. In the mid-seventies and early eighties, however, California&apos;s talc production declined to approximately 20 kt in 1992 due to reserves exhaustion and the material&apos;s tremolite content, which raised significant product liability concerns at the time. Talc mining in New York State dates from about 1878, when a Colonel Palmer and associates opened the first commercial talc mine on the Nelson Freeman farm near Talcville. In 1893 this operation was sold to International Pulp Co., which changed its name to International Talc Co. in 1944. The company was acquired by R.T. Vanderbilt Co., Inc., in 1974. A new talc operation, Gouverneur Talc Co., owned by R.T. Vanderbilt Co., began operations near Balmat, NY, in 1948. The initial capacity of the processing plant was 180 tpd (Gillingham, 1950). Subsequent expansions have increased capacity to more than 725 tpd. Talc was discovered in the area of Johnson, VT, in 1902, marking the birth of the Vermont talc industry. American Minerals Co. initiated plant operations at Johnson in 1904. MagnesiaTalc Co. opened a plant at Waterbury, VT, in 1913 (Burmeister, 1963, Trauffer, 1964) and acquired American Minerals Co. in 1923. The Waterbury mine had a long history as a producer of talc crayons. Eastern Magnesia Talc Co. was formed in 1924 by the merger of Eastern Talc Co. and Magnesia Talc Co. In 1956 Vermont Mineral Co., with a talc mine at Hammondsville, VT, was also acquired. A new plant was then built at Gassetts to produce roofing products. In order to produce high grade products for several markets, Eastern Magnesia Talc Co. began operating a modem froth flotation plant at West Windsor, VT, in 1964. The ore was provided by the Hammondsville mine. This operation, known as Windsor Minerals, Inc., continued from 1972 to 1989 as a subsidiary of Johnson and Johnson Co. In 1989 Cyprus Minerals Co. acquired Vermont Talc, Inc. and Windsor Minerals, Inc.. thus consolidating the talc mining and processing operations at Hamm, Windham, Johnson, Chester, Ludlow, West Windsor, Troy, and Reading, VT, under one ownership. As the result of Cyprus&apos; sale of its worldwide talc assets to the RTZ Group in 1992, its US talc operations are now part of Luzenac America, Inc.

Jan 1, 1994