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RMCMl PRESIDENT CHARLES W. MARGOLF on behalf of The RMCMI Board of Directors and Officers invites you and your family to attend The 81st Regular Meeting and Convention of The Rocky Mountain Coal Mining Institute to be held at Tamarron, Durango, Colorado JUNE 30, JULY 1 AND 2, 1985

Jan 1, 1984

By G. Gabra

The kinetics of acidified thiourea leaching of pyrite concentrate was investigated at temperature ranging form 20 °C to a 60 °C. The effect of various parameters on the dissolution rates are discussed. The gold extraction was found to be zero and first orders with respect to Fe (111) and thiourea concentration, respectively. The order of the reaction with respect to sulfuric acid was found to be zero. The activation energy was determined from the Arrhenius plot as 2,039 kcal mole -1 (for a freshly prepared acidic solution containing Fe (111) as the oxidant and at 800 rpm stirring speed. This relatively low activation energy value suggests that the gold extraction is controlled by a-physical phenomenon. Under optimum conditions, more than 90% of gold has been dissolved in about 30 min. and 95% in 60 min. Attempt to recover gold from thiourea solution using active carbon is also discussed.

Jan 1, 1984

By Terje Preber

Undisturbed sampling of shale has always been difficult. As pert of a comprehensive subsurface investigation for a nuclear power plant in northwestern Illinois, the Maquoketa shale, which contains seams of argillaceous dolomite, was sampled using different coring techniques. Since the Maquoketa shale is extremely fissile, careful sampling preservation by both lateral and vertical confining was utilized. The samples were tested to determine both static and dynamic properties. A relationship between void ratio and compression index, swell index, and swell pressure ratio was established. Correlation was found between the dynamic properties and both undrained shear strength and confining stress. Based on the results of the sampling and testing programs, recommendations for sampling and sample preservation techniques are given. INTRODUCTION Undisturbed sampling and preservation of samples of weathered, fiasile shale is often a very difficult task. The often erratically varying degree of weathering with depth complicates sampling and makes reproducibility of testing results difficult. Therefore, the testing of weak, weathered rock very often yields a wide variety of test results with large data scatter. The reproducibility of teat results usually associated with water-deposited soils is seldom, if ever, obtained. The testing and sampling program described in this paper was part of a comprehensive subsurface investigation for a nuclear power plant in northwestern Illinois. The sampling, preservation and testing program of shale samples taken from the Maquoketa shale are described, and, in particular, the different sampling techniques and sample preservation procedures are evaluated with respect to their effectiveness. The samples obtained by these procedures were subjected to a comprehensive testing program, including both static and dynamic testing in order to provide input for soil-structure interaction analysis. GEOLOGY The Maquoketa Shale Group is of Ordovician age and is part of the Cincinnatian Series. The area where the shale samples were taken was in a broad sea far from sources of clastic sediments during most of Ordovician time. However, during Cincinnatian time when large deltas in the Appalachian region were being formed, clastic sediments from the east dominated the sedimentation ii. Illinois, resulting in formation of the shale and dolomite shales of the Maquoketa Shale Group (Willman et al., 1975). The geologic unit sampled consists of a greenish gray to gray silty shale containing numerous 1- to 12-inch (2.5- to 30.5-cm) thick interbeds of argillaceous dolomite. The dolomite comprises up to 40 percent of the profile studied. The shale

Jan 1, 1984

Develop an inexpensive, reliable means of quickly detecting and locating trapped miners in underground coal mines, particularly after a mine accident. The Limitations Although the Bureau of Mines has performed extensive research on the use of electromagnetics for locating trapped miners, much of its research trends toward the development of long-range systems designed to locate an underground transmitter from the surface. Such location systems are beneficial; however, there are several limitations regarding their use. Two limitations are weight and cost of the equipment. Most long-range detection systems would be too heavy and cumbersome to be accepted by miners as part of their daily protective equipment. Since such long-range detection systems are usually expensive, it would not be economically feasible for every miner to be provided with a system.

Jan 1, 1984

By Dirk van Zvl

The design of cover systems for reclamation schemes in tailings requires estimation or determination of tailings materials properties such as compressibility, shear strength and consolidation characteristics. It is very difficult and expensive to obtain truly undisturbed tailings samples for laboratory testing. In situ testing methods have been developed for economically obtaining large amounts of information. Two of these methods are described, the piezocone and the flat plate dilatometer. Both of these methods provide a rapid means of detailed material identification in a nearly continuous fashion for the entire depth investigated. The equipment is described and typical data from a uranium tailings impoundment is presented. The results are compared and the advantages and disadvantages of these methods are discussed.

Jan 1, 1984

A co-operative research project, combining Commonwealth Scientific and Industrial Research Organisation (CSIRO) research scientists findings and company iron ore geologists' expertise, resulted in new concepts about the origins, distribution and complexitie of iron ores and their parent rocks (banded iron-formation or BIF) in the Hamersley Iron Province of Western Australia. Understanding these problems was important to the efficiency of exploration, development and ultimate mining of iron ores. This genetic model, based on a detailed mineralogic background, was modified by Mt Newman geologists to obtain a user oriented classification for practical application in the field.The proposed Pilbara Iron Ore Classification (PIOC) gives iron ore geologists a basis from which to understand, identify and record the various mineralogic and physical characteristics of the many genetically different ore types occurring within and between orebodies in the Pilbara. More definitive quality control over ore products can be achieved based on the detailed understanding of ore types which the PIOC allows, compared to current classifications which deal only with the physical nature of ores. Of equal importance, the classification remains sufficiently simple to enable owners, operators and buyers to achieve a basic appreciation of ore type variations.With little modification, it is believed the classification has applications beyond the Pilbara, to iron ore worldwide.

Jan 1, 1984

By Paul E. Epstein

Despite the controversies that have surrounded asbestos over the past 20 to 30 years, no knowledgeable authority has doubted the usefulness of this material. Were it not for the health risks associated with the manufacture and use of asbestos products, its physical and chemical characteristics would continue to be hailed as an undeniable boon to mankind. However, it has become clear over the past 30 years that like other major contributors to our modern industrialized society, asbestos must be handled responsibly and with the full understanding that lack of care can lead to injury, suffering and death. In this sense, asbestos shares characteristics with nuclear power, pesticides and even motor vehicle usage. It is unlikely that modern society would be willing to walk away from the benefits bestowed by any of these valuable resources. Rather, the appropriate response to the identification of danger is to define the type of risk, quantify its incidence, search for methods of decreasing the risk and implement programs to achieve the goal of minimization of risk. We should recognize at the outset that the risk cannot be diminished to zero without elimination of the material entirely from our midst. The concept of acceptable risk is a complex issue involving medical, legal, financial, moral and even psychological factors that defy precise quantification. In essence, the major danger produced by exposure to asbestos is its potential effects on the respiratory system. Despite the fact that asbestos workers have constant skin contact with the material and porbably swallow it in the course of their activities, inhalation of the fibers is recognized as the major health risk associated with its use. Aerosols of asbestos are inhaled not only by miners, millers and fabricators but also by urban dwellers who have no direct occupational contact with the material. This occurs because asbestos has been applied to our buildings and has been used in a wide variety of products that touch our daily lives. While it is estimated that three to four million people in the United States have been occupationally exposed to asbestos, the number who have been non-occupationally exposed is many times that number.

Jan 1, 1984

By M. M. Tilman

The Bureau of Mines evaluated corrosion resistance of Split Set friction rock stabilizer mine roof bolts to aid in better prediction of useful service life. Electrochemical corrosion testing was conducted utilizing an automated corrosion measurement system. Natural and/or synthetic mine waters from four uranium and two copper mines were the test media for the two types of high-strength, low-alloy (HSLA) steels from which Split Set stabilizers are manufactured, and for galvanized steel. Tests were conducted with waters of minimum and maximum dissolved oxygen content at in-mine water temperatures. Retrieved Split Set stabilizers were also evaluated for property changes. Galvanized steel was found to be far superior to the unprotected steel in general corrosion resistance; limited tests indicate little ten.dency to pitting, contrary to behavior for the uncoated steel. Copper-bearing HSLA steel was slightly more corrosion resistant than non-copper-bearing HSLA steel. Statistical analyses resulted in development of equations relating dissolved oxygen, chloride, sulfate, and magnesium contents of mine waters to corrosion rates of the two HSLA steels (nongalvanized). An equation was developed that relates corrosion rates of galvanized steel to mine water temperature and dissolved oxygen content. Variable conditions in mine environments make corrosion damage difficult to predict and emphasize the need for corrosion prevention and control.

Jan 1, 1984

By D. Marcus

A methodology was developed wherein. the increase in compressive strength, mineralogical changes and pore water composition were all studied simultaneously as a function, of moisturized spent shale curing time. From these results the relationship between the nature of cementation process and the composition of pore water was established. Heavy metals were entrapped in the cementing constituents and the pore water became mainly a solution of alkaline sulfates. While the specific data are applicable only to the material studied, the methodology and general conclusions are useful for evaluating the environmental factors in spent shale disposal and expected leachates composition.

Jan 1, 1984

Jan 1, 1984

This paper describes the operating practice and design features of an intensive-cyanidation plant at the East Gold Plant of Vaal Reefs Exploration and Mining Company Limited (V.R.E.M.). After the development oh cyanidation route for the treatment of gold-plant gravity concentrates by the Anglo American Research laboratories (A.A.R.L.), a full scale plant was commissioned at Western Holdings (Welkom Division) Gold Mine in March 1977, and the V.R.E.M. plant was commissioned in August 1981. Although the gravity-concentration route does not now enjoy the prominence of former times, in an existing conventional plant the intensive-cyanidation route can successfully replace mercury amalgamation.

Jan 1, 1984

"The sulphide nickel resources of Australia are concentrated in the Western Australian Shield. This shield is considered to have developed by extensive, but incomplete, Proterozoic reworking of once-continuous Archaean crust. It now constitutes relic Archaean cratons and intervening orogenic mobile belts transected by narrow, curvilinear tectono-thermal mobile belts of younger Proterozoic age. Remnants of the Archaean cratons are exposed in the Yilgarn and Pilbara Blocks. In the former an ancient (to ca 3600 m.y.) high-grade gneiss terrain (Western Gneiss Terrain) occurs along the western margin of the block and is interpreted to flank younger (ca3000-2800 m.y.) greenstone belts to the east. Ancient (to ca3500 m.y.) granitoid-greenstone terrains dominate the Pilbara Block.Proterozoic mobile belts contain only traces of nickel mineralization, except for one locality in the Halls Creek Province. The Archaean high-grade gneiss terrains contain no important mineralization, and the Pilbara granitoid-greenstone terrains contain only scattered examples of less important types of mineralization.The important deposits (e.g. Kambalda, Windarra, Agnew, Mt Keith) are all of komatiitic affinity and are best developed in the youngest greenstone belts of the eastern part of the Yilgarn Block. In particular, they are concentrated within, and adjacent to, the Norseman-Wiluna Belt, which contrasts in age, lithofacies and structural style with all other greenstone belts in the shield. It is interpreted to have been a rift zone. Within this belt the two main deposit types—the volcanic peridotite-associated and intrusive dunite-associated deposits—are concentrated into spatially separate zones. Precise controls on this heterogeneous distribution cannot be determined unequivocally from available data. One possibility is that the major volcanic peridotite-associated deposits were developed selectively in the actively subsiding axial part of the rift zone during the early extensional phase, whereas intrusive dunite-associated deposits were formed during a subsequent (less active?) stage of volcanic basin development. Distinctive sub-types (facies) of the volcanic peridotite-associated deposits form clusters that are generally within the rift zone. These may represent deposits related to discrete eruption centres, and at least part of their variation is due to relative position within extensive, topographically confined, linear flows."

Jan 1, 1984

By Richard H. Olson

Talc is currently mined in the U.S. in six major districts. The size and depth of the ore bodies and their mineralogy dictate the types of products manufactured and the mining and processing methods which must be employed. The geology of the major deposits is well known and will be but briefly discussed The major emphasis will be placed upon the past history of the districts, the size and depth and configurations of the ore bodies, the ore mineralogy, and how all of these factors govern the types of mining and processing operations which may be employed in each of the districts.

Jan 1, 1984

By Taylor G. R

Fluid inclusions within quartz accompanying several stages of mineralization at Hillgrove are de cri bed. Pyrite-arsenopyrite-gold mineralization shows uncorrected filling temperatures of between 195°C and 250°C. Later stibnite-antimonide-siderite and stibnite-calcite mineralization has filling temperatures between 100°C and 195°C and a bimodal distribution of temperature peaking at 175°C and 145°C, possibly correlated with the two stages of mineral deposition. Secondary included fluids within an earlier generation of deformed quartz veins are derived from hydrothermal fluids contemporary with the main-stage mineralizing fluids described above. Primary inclusions within latestage, cross-cutting quartz-chlorite-calcite veins show these veins to be unrelated to the mineralization.A correlation between filling temperatures and salinities indicates that mineralization accompanied the mixing of a hot, partly saline, fluid (at 5 per cent equivalent NaCI) with cooler, less-saline meteoric or connate water. Over a vertical distance of 200 m, equivalent mineral assemblages were deposited over the same temperature range. Studies on single crystals suggest rapid deposition with fluid temperature dropping 45°C during their growth. Ore mineragraphy and the fluid inclusion data suggest that the metals were transported by sulphur-poor, relatively low-temperature, low-salinity solutions, possibly as carbonate complexe , and that a vertical zonation of the W-Sb-Au mineralization is compatible with the mixing of this hydrothermal fluid with cooler groundwater. Regional metallogenic and geological considerations suggest that ore metals are derived from the remobilization of deep-seated stratabound deposits or from metamorphic fluids expelled from deepseated volcanoclastic sediments.

Jan 1, 1984

By H. M. Varner

Under sponsorship of the US Bureau of Mines and the Department of Energy, a new type of rotary rock drill was developed by The Bendix Corp. Originally developed for the production of holes for the installation of longer than seam height roof bolts, the flexible drill is a useful tool for many drilling applications. It allows hands-off or remote production of holes for increased drilling speed and greater operator safety in any strata suitable for rotary drilling. This paper discusses various applications and experience for the flexible drill system in coal, metal/nonmetal mining, and for civil engineering uses. Manual, remote control, and automatic roof bolter modules are also discussed.

Jan 1, 1984

By C. P. Mangelsdorf

Between June of 1975 and November of 1978 Stateham and Radcliffe of the Denver Research Center of the Bureau of Mines in cooperation with officials of the Bear Coal Company of Somerset. Colorado Conducted extensive studies of the roof conditions in the Bear Mine. The purpose of the investigation was to determine the relationship if any between the length of time the roof was left unbolted and the subsequent stability of the roof. Using the comprehensive information available from Stateham and Radcliffe (1), (2), (3), (4) the author has proposed a design for a roof truss installation which might have been used in lieu of some of the bolting in the areas where bad roof was encountered. Historically roof truss installations like bolting patterns have been applied rather than designed. The purpose of the present paper is to demonstrate how with the information available, one might proceed through a semi-rational design. In spite of the very extensive documentation by Stateham and Radcliffe, it was still necessary to make some working assumptions. It is, therefore, not intended that the process here illustrated be used without modification in any other mine nor is there any criticism implied or otherwise, of the way in which Bear Coal Company conducted its operations. The author has never visited the mine in question. This paper is meant to be an encouragement award a more rational use of roof trusses in situations where it is economically and structurally reasonable to do so.

Jan 1, 1984

By Catherine T. Aimone

Specimens of copper-bearing quartz monzonite were subjected to a plane shock wave simulating high compressional stresses in the proximity of a borehole wall. Fragmentation was studied as a function of stress levels between 1.6 GPa (23 x 104 psi) and 7.3 GPa(105.8x104 psi) and pulse durations ranging from 1.1 µs to 6.9 us. Both explosive pressure and pulse duration were shown to have a strong effect on particle size distribution. While the effect of pressure is well recognized, the effect of pulse duration indicates that ultimate fragmentation increases with the time of application of a plane wave pulse. At high pulse durations, degree of fragmentation is more sensitive to changes in pressure than at low pulse durations.

Jan 1, 1984

By Thomas C. Jones

The purpose of this paper is to disseminate new information for nonelectric blasting in trenching and construction work. The presentation is not designed or intended to discredit conventional electric detonators or use of MS connectors and cord. Its sole purpose is to inform the S.E.E. of new and exciting benefits realized by the use of the Hercudet non-electric system in the construction industry.

Jan 1, 1984

By B. Amero, W. Petruk, D. R. Owens, D. R. Morris

Samples taken at different heights in the lead blast furnace of Brunswick Mining and Smelting corporation were studied to determine the phases present in order to interpret the reactions In the furnace. The main phases in the blast furnace feed are Pb3Ca2S13011, Zn ferrite (ZnFe204), and hardystonite (Ca2ZnSi207); rninor ones include lead and a Pb silicate. The temperature in the furnace varies from about 300°C at 4.2 m above the tuyeres to 1150°C at 1.1 m. There is no evidence of reactions in samples from points cooler than 800°C. Some reaction occurs between 950° and llOO°C and the lead sinter is nearly decomposed at about 1150°C. The first evidence of reaction was the decomposition of Pb silicate to lead and S102. At higher temperatures the Pb Ca2Si3011 decomposed to form lead and hardystonite (Ca2ZnS120rf. The Zn required for hardystonite was derived from the Zn ferrite which apparently re-equilibrated to a new Zn ferrite with less Zn. The decomposed sinter consists essentially of lead, hardystonite, wustite and a Zn ferrite with a low Zn content.

Jan 1, 1984

By C. Hosten, K. V. S. Sastry, D. J. Kawulok-Englund

Since the last decade the iron ore processing industry has undergone drastic changes from supplying screened and natural ores to manufacturing tailored concentrates and pellets. Increased need for the beneficiation of lower grade iron ore deposits and the increased demand for higher grade concentrates necessitate finer grinding of iron ores before concentration. The normal filtration stations used in the past are experiencing difficulties in dewatering the finely ground concentrates to moisture levels acceptable for balling. In addition to finer grinding, applications of complex beneficiation techniques has decreased the filterability of the concentrates and create problems in filtration of iron ore concentrates. An overview of the filtration literature indicates there are few research reports on the dewatering of iron ore concentrate slurries. There exists a need to understand the principles and mechanisms involved in the filtration of iron ore concentrate slurries with a goal of developing more efficient filtration techniques. This paper presents the results from the first phase of our research program that included the development of a reproducible benchscale filtration technique and the investigation of the filtration behavior of eight iron ore concentrates.

Jan 1, 1984