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By J. H. Lalor

The Olympic Dam deposit was discovered in July 1975 with the intersection of 38 m (125 ft) of 1.05% copper in diamond drill hole RD 1. A further eight holes were drilled with only marginal encouragement to November 1976 when RD 10 cored 170 m (558 ft) at 2.12% copper and an economic discovery was confirmed. The discovery of Olympic Dam is an excellent example of the application of broad-scale scientifically based conceptual studies to area selection combined with the backing of an exploration management willing to support its exploration scientists in testing their ideas with stratigraphic drilling. It also illustrates the persistence required in mineral exploration. The project began in 1969-1972 with the development of a conceptual model for the formation of sediment-hosted copper deposits. This model suggested that the alteration of continental-type basaltic rocks could release copper into solution from which it could be concentrated in favorable stratigraphic positions. In mid-1972, this concept was applied to a review of the Proterozoic and Lower Paleozoic rocks in South Australia aimed at defining targets for stratigraphic copper deposits.

Jan 1, 1991

The reduction in the number and duration of machinery and equipment failures is an important source of economical efficiency enhancement in the Polish coal mining industry.Non-dismantling methods have been thus developed to evaluate the technical state of machines. Among these viroacoustical methods are the most effectively employed. Two-directional organisation of the testing can be chosen, such as periodical and continuous inspection. The monitoring methods for ball bearing, rope tension uniformity, longwall shearers, main fans and shafts installations etc. Instrumentation for monitoring measurements are either of intrinsically - safe or explosion - proof construction, which enables using them in a gas-hazard atmosphere. The development of these procedures has led to the trials to insert the diagnostic methods into the organisational scheme of a coal mine.

Jan 1, 1991

By Alan B. Wagner

Data from seven instrumented pile load tests in Milwaukee, Wisconsin and two other instrumented load tests reported in the literature, one in Evanston, Illinois and one in Houston, Texas were reviewed. The data were for pipe piles having diameters from 9-5/8 inches to 18 inches, driven to depths between 36 and 96 feet. These data were used to develop a relationship between effective vertical stress and unit side friction and unit end bearing. These relationships were based on readily measured soil parameters, undrained shear strength, Cu, and Standard Penetration Test (SPT) values. This Beta (ß) and Nt approach and four other methods were then used to calculate the bearing capacity of the nine cases analyzed. The results from each of the methods are compared with the measured results.

Jan 1, 1991

Two types of low-sulphidation epithermal mineralisation may be recognised in volcanic terranes. Chalcedonic Silica- Adularia-Illite type mineralisation is most common in rhyolitic terranes, whereas Crystalline Quartz-Illite-(Adularia- Kaolinite) type mineralisation is more typically formed in andesitic terranes. A third type of epithermal mineralisation, the high sulphidation or Vuggy Silica-Alunite- Kaolinite-Illite type, is also common in andesitic terranes. Episodic violent boiling, accompanying hydraulic fracturing and hydrothermal eruptions, characteristic of geothermal systems in rhyolitic terranes, is stressed for the formation of Chalcedonic Silica mineralisation. Such boiling of deeply circulating meteoric groundwater, with some magmatic fluid contribution, provides chalcedonic veining, episodic banding and brecciation textures, adularia stability, bladed calcite, and extreme loss of H2S from the fluid to cause major gold deposition. Crystalline Quartz mineralisation is probably caused by the mixing of shallow acidic groundwater with ascending deep geothermal fluids beneath andesitic strato- volcanoes. The cooling effect, oxidation, and increased acidity, overcomes the dilution effect, and results in quartz deposition, illite (and locally kaolinite) alteration, and precipitation of metals. Extensive formation of base-metal sulphides further enhances gold deposition. Violent boiling is restricted to local structural dilation sites, potentially producing high grade "bonanza" gold mineralisation.

Jan 1, 1991

By M. ]. [Mohkam

The paper describes the features of the problems encountered and the countermeasures taken for two different tunneling projects. Where, slurry shields were used to excavate, in soft heterogeneaous water-bearing grounds, tunnels passing at very low cover beneath existing foundations of H.T. electric pylons, underground structures and major utilities. In order to avoid any ground failure and/or damage to the existing structures, one option was ground treatement by grouting or freezing technics. However, it was judged that, based on previous experiences, excavation with slurry shield could be carried on securely using an appropriate slurry enriched with polymers and applying a well determined pressure at ground face. A three dimensionnal limiting equilibrium analysis model was used to determine proper confinement pressures. And, the appropriate slurry compositions were stabilished based on laboratory test results. The tunnels were excavated successfully, no ground failure was experienced, and the maximum settlement recorded (on pylons) didn't exceed 3 mm.

Jan 1, 1991

By Michael J. Cruickshank

A workshop to examine recovery systems for selected strategic and critical materials in the U.S. National Seabeds for the National Defense Stockpile in the 21st Century was held in Hawaii September 26-28, 1991, sponsored by the National Science Foundation and the Marine Mineral s Technology Center. The National Defense Stockpile of critical and strategic mineral commodities is presently in a deficit position of more than 7.5 billion dollars. Current domestic reserves of some commodities are limited or nonexistent. As defined by the U.S. Bureau of Mines, "Reserves are select resources . . . which at the time of classification, can be mined at a profit." Occurrences of these minerals have been discovered offshore within U.S. jurisdiction. If the technology could be developed to convert these resources into usable ore reserves, our dependence on foreign ores could be greatly reduced. Preliminary estimates indicate that a ten-year program of ore reserves definition, with appropriate technical developments to demonstrate a recovery system, could cost less than half the amount authorized for stockpile acquisition in FY 1989 alone.

Jan 1, 1991

By Mark S. Stagg, Rolfe E. Otterness, Stephen Rholl

The Bureau of Mines is engaged in research to develop and test high explosive fracturing and rubblization techniques that will enhance ore body permeability and thus increase recovery during in situ mining. The natural permeability of many ore bodies is too low to allow successful in-place leaching. These deposits could be profitably mined if flow rates of leach solutions could be increased. Blasting represents a potentially low-cost and effective permeability enhancement technique.

Jan 1, 1991

By Bahne C. Cornilsen, X. Shan, David H. Carlson, John H. Johnson

The air in three U.S. underground coal mines has been sampled. The data developed show the relative importance of the various pollutants and quantify the need for control. Total respirable particulate matter (TRPM) was found to be the critical pollutant (the one requiring the most dilution for control). TRPM is considered to be "respirable coal dust" by procedures approved for sampling in U.S. underground coal mines. However, this "respirable coal dust" also includes diesel particulate matter (DPM) and particulate from other sources. While "respirable coal dust" was the critical pollutant, Raman spectroscopic analysis showed that more than half of this "respirable coal dust" was DPM. The DPM in the samples ranged from 22 to 152% of the 2 mg/m3 limit for respirable coal dust. Thus DPM was the critical pollutant using the 2 mg/m3 respirable coal dust limit. SO2 gas produced by the combustion of diesel fuel containing sulfur was the second-most critical pollutant. Characteristic curve slope (CCS) values were calculated to determine the quantitites of the various pollutants generated per unit of diesel haulage activity. Mine 1 had the highest TRPM CCS values with 29 mg/m3/%C02 for the Ramcar and 57 mg/m3/%C02 for the Haulageway location. The highest coal particulate CCS measured was 30 mg/m3/%CO2 and the highest diesel particulate CCS measured was 27 mg/m3/ %C02. Both of these high values were measured in the Mine 1 haulageway location. Calculations were made to determine the controlling CO2 concentrations (CCC) at which all other measured pollutants would be within their limits. These CCC values, which, for the mines sampled, were based on TRPM, varied from a low of about 0.07% for the Mine 1 haulageway location, to a high of about 0.15% for the Mine 2 Ramcar and haulageway locations. Weekly average CO2 concentrations measured in these mines ranged from 0.09 to 0.11 % for the Ramcar, from 0.05 to 0.09% for the haulageway, and from 0.08 to 0.11 % for the return. The concentrations of TRPM ranged from 1 and 2 mg/m3 in mine areas frequented by personnel, and to greater than 4 mg/m3 in returns where personnel are not exposed.

Jan 1, 1991

By M. Scobie, T. Atkinson

"This paper reviews the development of new designs in extensible and high angle conveyor systems. These aim to overcome the limitations of prior alternative concepts in design. The application of such systems in strip, terrace, open pit and mountain mining is reviewed. IntroductionTruck haulage costs have tended to escalate in recent years. This has been primarily due to operations generally moving to greater depths with associated increases in haul distances . Periods of high inflation rates have also been experienced for diesel fuel oil, tires and other petroleum based products. Recent international political events have tended to regenerate concerns over future oil supply and price stability. For such reasons, conveyor based transport is becoming increasingly attractive. Truck haulage maintains an inherent flexibility and improvements continue to be made in performance and capacity. Doubts must exist, however, over the extent to which further economies of scale may be made. Conversely, belt conveyor systems do not suffer this constraint and have the following advantages:• Electrical power is used and the specific energy consumption is at least half that required for truck haulage.• Operating costs and skilled labour requirements are lower.• Equipment has superior longevity and is ""inflation proof"" .• Access roads can be steeper and narrower in most mine environments, reducing construction and maintenance costs.• They are less prone to breakdown and bad weather delays .• In long haul, high capacity operations conveyors can save substantially on capital cost.• Environmental impact is improved with reduced noise level, dust and atmospheric pollution. Although conveyor systems are less flexible in operation than truck haulage and although a breakdown in any part of the system can immobilize the total system, mechanical availabilities of + 80% are constantly reported by large operators. There would appear in the past to have been some prejudice against conveyor systems in hard rock mines due to lack of experience. Apparent reservations would apply equally 10 underground coal mines, yet practically all of these mines (and some underground hard rock mines) find conveyor systems more economical than other transport systems."

Jan 1, 1991

By L. G. Austin

Development of an equation for tumbling charge and balls plus comparison to plant data suggests that the net mill power for cylindrical semiautogenous mills can be calculated from

Jan 1, 1991

By Napier-Munn T. J, Morrison R. D, Moloney M. J, Corrans I. J

A dynamic simulator for CIP / CIL gold recovery plants has been developed at the Julius Kruttschnitt Mineral Research Centre within a collaborative, industrially - funded AMIRA project and with the participation of the Western Australian School of Mines. The simulator incorporates kinetic models for the leaching of gold from ore and its adsorption onto activated carbon, and the residence time distributions of the leach liquor, pulp solids and carbon in the circuit. Features of the simulator include the effects of gold loading distributions on both the ore and carbon on reaction rates, and the difference in residence time distribution between the leach liquor and pulp solids. The simulator allows for the estimation of kinetic model parameters from full scale applications, as well as some scale - up of parameters from laboratory batch tests. The laboratory tests were conducted at the WASM as part of the collaborative research project. The simulator can operate in both steady - state and dynamic modes, and has potential applications in design, optimisation and control of CIP / CIL plants.

Jan 1, 1991

By X. J. Wu

Effects of various factors such as diaphragm materials, composition of electrolytes and current density on copper electrowinning from cupric chloride solutions was investigated. It is found that the crux of this process is to prevent the dissolution of copper by cupric ion and the formation of suspended CuCl precipitate. A process with high difference of copper concentrations between the feed solution and the spent electrolyte was selected. With this process, in which the feed solution contains 90 g/dm3 [Cu"], 3M NaC1, and 10mg/dm3 bone glue, and the spent electrolytes contains 10 g/dm3 [Cul, a very smooth and dense copper cathode can be produced with current efficiency above 93% and energy requirement less than 1.7 kwh/kg Cu at 25°C with N2 sparging. If a slightly higher energy requirement is permitted, smooth and dense copper cathodes can be produced at the current density up to 800 A/m2 with the identical solutions.

Jan 1, 1991

By Robert R. Tarver

A long history of gold production at Nome, Alaska has resulted in long term interest in the nearshore environment as a production target. Mining by Western Gold Exploration and Mining Company offshore of Nome yielded approximately 100,000 troy ounces of gold in the period 1986 through 1990. This study was designed to determine the relationship between heavy minerals, sediments, and gold concentrations which occur in the upper meter of sediment offshore of Nome. Standard procedures were implemented for grain size analysis, heavy mineral separations, and heavy mineral frequency determination.

Jan 1, 1991

By M. A. Gibson

Ilmenite-rich lunar deposits can be converted to liquid oxygen to support lunar base operations and space transportation propulsion needs by a Carbotek-developed process. Iron oxide in ilmenite is reduced at elevated temperatures by hydrogen in a fluidized-bed reactor to water vapor which is electrolyzed to product oxygen and recycle hydrogen. Reaction rate, thermodynamic equilibrium, and lunar-gravity fluidization behavior are key factors which have been considered. Fluid-solids behavior has been modeled from data taken at lunar gravity conditions aboard NASA KC-135 flights. Large-scale pilot plant operations are planned to complete the development.

Jan 1, 1991

By A. J. Partos

The figures and tables referred to herein are presented in the Proceedings; Volume I, Pages 309 through 316. The 61-story One Liberty Place, at 315 m., is the tallest building 1n Philadelphia and was in 1987 the ninth tallest building in the world. One Liberty Place is supported on drilled piers socketed in heterogeneous metamorphic rock. Design load distribution was 40% on the base and 60% by shaft resistance. Drilled Pier G-10 supporting a T13-A type outrigger column was instrumented. There 1s no uplift load on the exterior outrigger columns. This column supports a 53,850 kN compressive load which includes a 13,440 kN windload. Table 4 presents experimental parameters from straight line interpolation of Mohr failure envelopes for the Wissahickon schist. Lowest values of cohesion (12,200 kN/m2) and angle of internal friction (19°) are at a 50° - 59° angle of foliation. Figure 3 presents a typical pier supported by shaft resistance 1n decomposed (D) and coreable (C) rock and by end bearing (B).

Jan 1, 1991

By Arpad E. Torma

The identification and characterization of lithographic iron and sulfur oxidizing bacteria in the 1940' s. opened up new possibilities and challenges for the mining and metallurgical industries. These were exploited during the 1950's and' 1960's, when it was demonstrated' that mining wastes and complex unused mineral resources could be economically treated by bacterially assisted heap and dump leaching processes?. During the 1970's this technology grew into a more structured discipline called "biohydrometallurgy". In the l980's efforts were devoted to the identification of a variety of organisms involved in naturally occurring leaching processes. Further efforts dealt with the elucidation, of leaching mechanisms; the leach ability of nickel, coban, zinc, and precious metals; the desulfurization of coal; and diverse biosorpion phenomena. The application of genetic engineering techniques for the improvement of microbial performance was also initiated?. Current trends in biohydrometallurgy include improvement of many of the techniques noted above, as well as application of leaching. technolog.ies to. environmental remediation scenarios. These activities afford considerable opportunities for research in the 1990's. For example, bioremectiation of abandoned mining and processing sites requires development of new and economically viable technologies capable of removing low concentrations of toxic metals from high volumes of solid and/or liquid wastes.

Jan 1, 1991

By M. Misra

The bacterium?Mvcobacterium Phlei has a demonstrated potential to be used for the flocculation of a variety of finely divided minerals. The microorganism possesses both hydrophobic surface and high negatively electrostatic charge. It can adhere to many mineral surfaces ?if the charge and hydrophobic interaction? between the microorganism and the minerals are favorable to adhesion. Experimental results showed that the dolomitic phosphate slime from Florida and fine hematite can be :readily flocculated from dilute suspension.. In the case of dolomitic phosphate slime, a consolidated sediment containing 24'-25 weight% :solids can be obtained from .a dilute slurry .in a short time. Sediments obtained from hematite flocculation are rather massive and more .consolidated than phosphate slime. Mycobacterium Phlei has a specificity for selective flocculation of hydrophobic fine coal particles from pyrite and ash containing minerals. Because of mutual hydrophobic interaction of coal and Mycobacterium Phlei, it was noticed that coal particles appear to be strongly held in the aggregate by adhesion or bridging of bacteria. However, Mycobacterium Phlei is not a good flocculant for either associated pyrite or ash present in coal.

Jan 1, 1991

By Ting Chinsu

Diaphragm wall with tie-back cable is widely used for deep excavation, especially in the area with high density of buildings. This paper presents the measured earth pressure distribution on diaphragm wall during excavation. The earth pressure cells used in field were successfully installed in deep slurry trench by a new type of simplified manipulator. The sizes of the deep excavation are 26m X 36m on plane and 9m in depth. The construction site is located between two multistorey buildings at the main business section of Beijing city. In this paper the field measurements of earth pressure distribution and the analyses based on the comparison between calculation and measurement are very valuable to improve the current calculation method for diaphragm wall design.

Jan 1, 1991

By Thomas P. Meloy

The understanding, quantification and use of locked particles. Specifically discussed is the use of Textural Transforms (Meloy, 1991) for the implementation of the Interfacial Area Conservation hypothesis (Meloy, 1984); the quantification of the locked particles as a function of fragment to inclusion size ratio; and the selection of set points.

Jan 1, 1991

By S. S. Hsieh

As part of a program to address the long-term need to ensure adequate supplies of domestic phosphate raw materials, the Tennessee Valley Authority (TVA) has conducted considerable research on dolomitic phosphate rock beneficiation. The discovery that alkyl diphosphonic acids act as phosphate mineral depressants led to the development of several processes involving a carbonate flotation step for the effective beneficiation of these problem ores. Most recently, a partial deoiling process in which the reagent consumption is greatly reduced has been developed. The reduction is achieved because part of the initial feed is beneficiated without passing through the separate carbonate flotation step. Using this method, a phosphate product containing 30.6-30.9% P2O5 and 0.7-0.8% MgO was obtained from a Florida dolomitic phosphate pebble that contained about 23% P2O5 and 2.0% MgO. The P205 recovery was 80.8-86.5%.

Jan 1, 1991