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By David S. Yang, Osamu Taki

The innovative Soil-Cement Mixing Wall Technique, developed independently in Japan, consists of mixing in-place soils with cement grout using multi-axis augers and mixing paddles to construct overlapping soil-cement columns. The applications of overlapped soil-cement columns include cutoff walls for groundwater control and structural diaphragm walls for excavation support. The special features of this technique include water tightness, versatile strength design, and efficient installation in subsurface materials varying from clayey soils to cobbles or soft rocks. Through the introduction of two recent subway projects in Japan, this paper presents the design parameters, construction procedure, quality control and performance of soil-cement wall for excavation support and groundwater control.

Jan 1, 1989

By E. Ilgar

Biodegradation of spodumene by Asnergillus niger has been investigated. This organism oxidizes sucrose to citric and oxalic acids (in approximately 50-sot proportions) which degrade the spodumene mineral. The kinetic effects of leach variables on the dissolution of lithium were determined. The maximum theoretically attainable rate of lithium extraction was calculated for the effect of pulp density, to be V : 3.01 x 10 kg m sand the corresponding constant value, K = 12.47% pulp density. The apparent activation energy of lithium extraction vas found to be ^E = 20.3 kJ and frequency factor A = 5.66 x 10 s for S-spodumene leaching by synthetic -3 citric and oxalic acids (each in 0.05 kmol m-3 concentrations).

Jan 1, 1989

By Jean-Michel Rendu

Equipment capital operating costs represent a significant portion of the total cost of most mining operations, and a variety of computerized methods have been developed to assist in the selection and effective use of this equipment. The questions to be answered and the tools available to answer these questions vary with the type of mine to be analyzed, the stage of development of the mining venture, the size of the operation, the details required, and the technical or economic objectives to be reached. Even though a majority of publications are directed towards open pit mining operations, the underground environment is not neglected. In the early planning stages of a mining venture, equipment selection is the problem to be solved. The simplest computer systems are designed to' automate time consuming manual tasks. A data base is supplied to and maintained by the user, which describes the technical and economic characteristics of available equipment. The user specifies the physical environment within which the equipment will be used and chooses from the data base a combination of loading and transport equipment. The role of the computer is to detemine the production which will be likely reached, the associated costs, and other relevant statistics. This approach is most helpful when modeling small operations or isolated parts of larger operations.

Jan 1, 1989

By Eric K. Albert

The permit generation and review process represents both a time consuming and expensive task for industry and government alike. Changes in regulations and in review procedures cause additional delays. This leads to potentially higher costs of doing business and the extension of time for a project to lie started. This paper describes the motivation and methodology of applying an expert system to function in the role of a permit reviewer. The problems of representing the knowledge of the reviewer and regulatory criteria are illustrated. Futhermore, the selection method for the expert system shell is addressed. Finally, a sample review is demonstrated to show the results of applying this artificial intelligence method to the process of permit review.

Jan 1, 1989

By T. H. Parker

The Guasare Coal Project is located a short distance from Lake Maracaibo, in the Northwestern region of Venezuela. In 1987, Carbones del Guasare, a joint venture comprised of Carbozulia, ACC Venezuela, a subsidiary of ARCO, and AGIPCoal of ENI Group, Italy, was formed to develop the Guasare coal reserves for world markets. Drilling with the Venezuelan state of Zulia has indicated a coal resource of over 6 billion metric tons. Further exploration has delineated the Guasare deposit as an area particularly suited for cost-effective surface mining. The calculated mineable reserves of this area (300 million metric tons) and the coal quality characteristics are based on extensive core drilling programs.

Jan 1, 1989

By Cheryl Lee Vatter

The Lupin mine consists of a gold mining, milling, and refining complex located 400 km (250 miles) northeast of Yellowknife and 100 km (60 miles) south of the Arctic Circle on the southwest shore of Contwoyto Lake in Canada's Northwest Territories. (Fig.1). The mine was commissioned in 1982 and is presently producing 6 t/a (193,000 oz per year) of gold from 612 kt (675,000 st) of ore. The success of this operation is due to such factors as the continuity and grade of the ore body, the competency of the host rock, low mining costs, efficient milling, the transportation of people and materials to and from the mine site, and the unique work schedule resulting in a stable workforce. Echo Bay Mines operated a silver mine at Port Radium on Great Bear Lake, Northwest Territories, from 1965 to 1982. The company first obtained an option on the Lupin property from Inco in February 1979 and completed an underground exploration program in 1979-1980. Topographic relief is low and vegetation is sparse in the continental subarctic climatic zone, consisting mainly of moss and lichens. Temperature extremes are from 24°C to - 45°C (+75°F to -49°F) with an annual mean of -12°C (+54°F). Permafrost extends from near surface to 500 m (1640 ft) in the ore zone. Its remote location and harsh climate presented some challenging design and logistical problems. Construction began at the Lupin mine site in 1980. Before construction, a 1.5-km (5000-ft) gravel landing strip was prepared, suitable for landing a C 130 Hercules. The entire Lupin project took 20 months to build. All of the men and materials were transported to the site with some 1100 Hercules flights and several hundred Convair 640 flights. The Convairs transported construction crews, which numbered 400 at their peak, and also carried 3.2 kt (3535 st) of supplies during construction. The facilities were constructed and commissioned for a total cost of C$135 million. The operation was originally designed to throughput 860 t/d (950 stpd). Expansion in 1983, circuit refinements, and some capital projects brought the daily throughput to 1.7 kt/d (1850 stpd). The underground mine delivers 612 kt/a (675,000 stpy) of ore to the mill at an average head grade of 8.46 g/t (0.3 oz per st). The ore is nonrefractory and is processed in a conventional cyanide leach using the Merrill Crowe process. Gold recovery is about 95.0%. The average production cost is $US5.85/g ($US 182 per oz) based on 1987 figures. Mining at Lupin – Geology The Lupin deposit occurs in amphibolite grade iron formation overlain by mudstones (phyllites) and underlain by graywacke (quartzites). Contacts between the wallrock units and the iron formation are well defined. It has been folded and tilted into a megascopic antiform-synform-antiform structure (Fig. 2). Gold occurs primarily within the sulfide rich iron formation, with some minor occurrences in sulfide poor iron formation. The distinction between sulfide rich and sulfide poor iron formation is based on a visual cutoff of 5% total sulfide content. Mining widths are determined by an assay cutoff of 4.2 g/t (0.15 oz per st) gold. There are few tons between 1.7 and 4.2 g/t (0.06 and 0.15 oz per st). The amphibolitic iron formation at the mine ranges from 1.5 to 20 m (5 to 65 ft) wide and has been followed over a strike length exceeding 1.7 km (5600 ft). The wider portions of the ore body tend to occur at its north extent and south nose. The gold-bearing iron formation appears on plan as a Z-shaped structure made up of three zones: the West, Center, and East. The West and Center zones dip steeply to the East (75° to 90°). Each of the ore zones plunge at an angle of about 65°. Total strike length of the three zones is more than 610 m (2000 ft). The zones are confirmed at a depth of 650 m (2130 ft) below surface. The Center zone is the widest and varies from 4.5 to 20 m (15 to 65 ft) while the West is the narrowest, averaging 1.5 m ( 5 ft). The footwall is comprised of quartzites that are strongly jointed and locally grades into phyllite, which comprises the hanging wall. The hanging wall and footwall are reversed in the West zone. Mineralogy of the ore at Lupin consists of amphibole minerals (hornblende, cummingtonite, and grunerite), feldspars, quartz, occasionally garnet, pyrrhotite, arsenopyrite, minor pyrite, and trace chalcopyrite. Also found in minor amounts are scheelite, apatite, epidote, calcite, tourmaline, and some arsenides (notable loellingite). Quartz

Jan 1, 1989

By Tad S. Golosinsk

Use of computers for hoist evaluation and design dates back to the early 1960's. Mine hoist production calculations, repetitive in nature, were computerized first. More elaborate modeling of hoist operations followed soon. Typical for this, early period are the models described by Touwen (1973), and by Albert and McIvor (1984). Apart from the simple hoist production calculations, the models were very complex, typically written in Fortran, and often required advanced computing facilities and expertise to run the simulation. The early models were strictly deterministic, with no consideration given to the random nature of hoisting operations. The effects of randomness of the hoisting process on hoist performance were often accounted for by introduction of the deterministic factors, most notably of an "utilization factor" related to the hoist production. The value of the latter was based on observations of actual hoist performance, and could vary in a wide range. For example Harvey (1973) reports values of the "utilization factor" to be between 0.7 and 0.92.

Jan 1, 1989

By K. Osseo-Asare

Metal recovery from solution, i.e., the formation of a solid product from a purified aqueous electrolyte solution, is increasingly becoming more than a simple matter of bulk precipitation. In many cases, operating conditions must be carefully manipulated to control the rate and yield of the precipitation/crystallization process, as well as the purity and physical characteristics of the solid product. A review is presented of the underlying physico-chemical processes, with emphasis on solution and interfacial chemistry. Opportunities for the integration of hydrometallurgical metal recovery and materials processing operations are discussed.

Jan 1, 1989

By M. Misra

The interaction of xanthate with SO2 in the flotation of sphalerite and chalcopy.ite is discussed. 'The SO depression of sphaledte is due to the decomposition reaction of xanthate by SO2 The decomposition reaction is dependent on the cole ratios of xanthate/SO2, oxygen concentration and pH. Xanthate adsorbs at a faster rate by chalcopyrite than sphalerite. The faster rate of xanthate adsorption by chalcopyrite and the specific action of S02 on the surface of chalcopy.ite facilitate the selective separation of chalcopyrite from sphaledte.

Jan 1, 1989

By Jianping Sheng, Francis Otuonye

The potential for methane and coal dust explosions in underground coal mining operations has increased in recent years with the introduction of fast coal-cutting machines. Dust explosions usually follow accidental ignition of a methane pocket. The dynamics of the explosion may be strong enough to pick up and disperse coal dust deposited on mine surfaces and ignite the mixture. A self-sustaining dust explosion can then develop and propagate at large distances. Ignition of dusts can result in a fire, and this may also lead to a dust explosion if the burning dust becomes airborne. Entrainment of dust and the resulting dust concentration in the gas stream are some factors which determine the features of the subsequent explosion and flame propagation. A model of coal dust transport in the gas stream due to the initial explosion is presented. In this model, equations for the conservation of mass, momentum and energy are coupled with the convective-diffusive model of dust transport. The system of equations is solved numerically to obtain dust concentration, convective velocity and gas pressure profiles.

Jan 1, 1989

By Jr. McCulloch

Mining operations of Freeport Indonesia (FI) are located approximately 4 degrees -6' south latitude, 137 -7' east longitude in Irian Jaya the eastern most state of Indonesia (Figure I). The mines are located approximately 96 km (60 miles) from coast in the Carstenz Mountain range. The ore bodies are between 2900 and 4000 meters (9500 and 13 000 ft) elevation.

Jan 1, 1989

By John S. Thayer, Frederick E. Brinckman, Kenneth L. Jewett, Gregory J. Olson

Interest and research in biorecovery of metals has focused mainly on cell-based metal leaching and precipitation. However, production of non-enzymatic metabolic products by microorganisms related to metals bioprocessing also deserves attention. For example, it is well known that biogenic inorganic (e. g. H2S04 ) and organic acids play a role in metal dissolution. There are other metabolic products of microorganisms which can catalyze useful metals transformations. These include methylated metabolites such as alkyl halides which can dissolve metals from ores and also reduce certain metal ions in solution to pure metallic particles. This paper describes some of our research on metal dissolution and precipitation by such metabolites. Examples include the production of high purity elemental metal particles of gold, platinum and palladium by volatile metabolic products.

Jan 1, 1989

By N. S. Tanious

Retrievability of emplaced nuclear waste from the geologic repository is a performance objective imposed by Federal Regulations. This requirement is designed to provide confidence in the Department of Energy's repository design by keeping the option of retrieval open if the engineered or natural systems prove inadequate for containment and long-term isolation of high-level nuclear waste. This paper presents a summary of current Nuclear Regulatory Commission Staff thinking on the design of the repository for retrieval, and level of retrievability demonstration that may be required during site characterization. However, this paper does not represent official U.S. Nuclear Regulatory Commission position on this topic.

Jan 1, 1989

The purpose of this paper is to describe two systems designed to provide estimations in stratigraphic orebodies for the purposes of detailed mine planning. The first is a completely geostatistical approach and the second is a combined geostatistical/deterministic approach. The essential features of both systems are the estimation of stratigraphic ore boundaries and the subsequent use of those boundaries to provide stratigraphic (or zonal) control for block and point grade estimation (kriging). Both systems are illustrated by application to a section of, the Hilton orebodies, Queensland, Australia.

Jan 1, 1989

By R. Ramesh

Understanding the nature of coal surface heterogeneity is a prerequisite to accurate characterization and efficient control of coal surfaces. New techniques based on the centrifugal immersion of particles from the liquid/ vapor interface and film flotation have led to independent estimation of surface energy distributions in individual coal particles. Changes in the distribution of surface sites due to oxidation and polyacrylamide adsorption on coal are studied here using the above techniques. New information on -possible conformations of adsorbed polymers is also obtained.

Jan 1, 1989

By R. Larry Grayson

A menu-driven, linear-programming- based, user friendly computer program was developed to assist mine managers in determining optimal longwall panel dimensions for a given set of operating conditions. A sensitivity analysis must be performed by varying key mining and configurational parameters over an expected, practical range during the optimization process. Results from analysis of a base case mine indicated that no single combination of longwall panel length and face width is optimal for all operating situations. Each mine manager must therefore look closely at his operating situation and determine the proper dimensions to minimize total mining cost.

Jan 1, 1989

By B. C. Williams

The Bureau of Mines monitored the water quality in and near a copper/gold tailings impoundment. Samples were taken from the unsaturated %one. and dissolved concentrations of over ZO constituents were measured with respect to depth and moisture content, factors which influence oxygen content and sulfide oxidation. Samples from the unsaturated %one were drawn through a hypodermic needle sampler into individually evacuated vials fitted with septa, thus preventing oxygen contamination. Water quality was also monitored in the saturated tailings, underlying colluvial aquifer, and weathered andesite bedrock.

Jan 1, 1989

By M. L. Mellish

The year 1988 unexpectedly turned out to be a good year for the US coal industry. In fact, it was a third consecutive year of record coal production. Accord¬ing to preliminary Energy Information Administration data for 1988, domestic coal consumption went up 5%, or 41 Mt (45 million st), from 1987. Coal exports were up by a surprising 13.6 Mt (15 million st). In 1988, 22.7 Mt (25 million st) of coal were drawn from stockpiles for consumption. Even so, US coal production increased to 862 Mt (950 million st). That was up 28 Mt (31 million st) from 1987. While coal consumption, exports, and production were up, delivered prices for steam coal continued to slide during the year. Metallurgical coal prices, however, firmed up and showed a moderate increase. This reflected tight metallurgical coal markets at home and abroad. Coal consumption US coal consumption reached 800 Mt (882 million st), compared with 759 Mt (837 million st) in 1987. Increased metallurgical coal consumption was one factor. Most of the rise in coal consumption, however, was due to unexpectedly high electricity demand. Unseasonably hot summer weather al lowed added coal-fired electric generation to supplement the drought-related reduction in hydro-electric power supply. Electric utilities consumed 687 Mt (757 million st) of coal in 1988, 35.4 Mt (39 million st) more than in 1987. Coal-fired power plants remained the primary source of US electricity generation, providing 57% of the total in 1988. Coal consumption at coke plants increased 13%, to 38 Mt (42 million st), from the level consumed in 1987. This increase reflects the recent recovery in the iron and steel industry. Metallurgical coal consumption in 1988 could have been greater. But US coke plants reportedly reached their maximum practical production capacity. As a result, net US coke imports amounted to 1.45 Mt (1.6 million st). Despite increased industrial activities, steam coal consumption by industrial plants was up only slightly from the 1987 level, amounting to 69 Mt (76 million st) in 1988. Residential and commercial coal consumption remained virtually unchanged at 6.4 Mt (7 million st). Coal exports and imports US coal exports rebounded in 1988, reaching 86 Mt (95 million st). It was the highest level of annual US coal exports since 1982, when they reached 96 Mt (106 million st). An unusual set of factors led to an opening for US coal exporters in 1988: • a high level of industrial production in Japan and the European Economic Community, • supply disruptions due to labor problems at coal mines in Poland and Australia, • a drought-related reduction in hydro-electric power generation in Canada, requiring increased coal-fired generation, • China's problems in meeting its export commitments, and • a fall in the value of the US dollar. US metallurgical coal exports in 1988 amounted to 56 Mt (62 million st), 9.1 Mt (10 million st) more than the 1987 level. Europe, Japan, and Canada were the principal importers of US metallurgical coal in 1988. European countries, in particu¬lar, increased their take by one-third of US metallurgical coal. The labor problems in Poland and Australia contributed to these higher levels of imports. So did increases in pig iron production of 8% in Japan and 9% in the European Economic Community. US steam coal exports - including bituminous, anthracite, and lignite-increase to 30 Mt (33 million st). This was up from 25.4 Mt (28 million st) in 1987 Contributing to this overall rise were 1.8-Mt (2-million st) increase in shipments to Canada and a 2.7-Mt (3-million st) increase to Europe. Unaffected by the somewhat tighter world coal market, US coal imports showed a slight increase to 1.8 Mt (million st) in 1988. Colombia continue to be the leading exporter to the United States, followed by Canada and Venezuela. Venezuela's entry into the US market is a relatively recent one, having made its first significant shipment in the fourth quarter of 1987.

Jan 1, 1989

By L. A. Puchkov

The creation of automatic methane concentration control systems presupposes the use, as a control factor, of the air rates in workings and in mine as a whole. These systems present a complicated set of computers and software, including as major components the following - systems for detecting methane concentration and air rate; - telemechanics systems; - programs and means of data processing; - programs and means of air rate control in workings and main fan capacity control. The paper analyses the experience of development and exploitation of automatic methane control system in gassy mines of the USSR Donetz coal basin. Much attention is given to the study of technological factors influence upon aerogasdynamic process using automatic methane control system.

Jan 1, 1989

By W. C. Goldberg

This paper presents pit slope monitoring and back-analysis case studies con-ducted to evaluate and, if possible, stabilize slopes at the Berkeley Pit in Butte, MT. Two specific slopes were studied in detail. The first slope was determined to be near limiting equilibrium, as evidenced by its response to the initiation and cessation of mining, while the second failed on three occasions. Back-analysis of the failed slope verified the laboratory-derived geomechanical properties of the earth materials. Early detection of slope movement can show a need to take action, including modifying slope geometry, dewatering if the slope were wet, and/or investigating and implementing artificial supports. Monitoring slope displacements in open-pit mines can supply data for predicting collapses and preventing serious damage, injuries, and/or loss of life.

Jan 1, 1989