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The initially cautious approach taken towards ground support and reinforcement at the Porgera Underground Gold Mine in the Highlands of Papua New Guinea has evolved rapidly in the two years since stoping commenced. The confidence to continue the evolution process has grown from an increasing knowledge of mining conditions as stoping has progressed, to the extent that reinforcement requirements have decreased by 50 to 75 per cent depending on local circumstances. Changes to mining practices have significantly assisted and influenced this process.Empirical observations of ground behaviour, assisted by a deliberately selective extensometer monitoring program, provided the stimulus for early changes to ground support and reinforcement practices. Further optimisation of the ground support and reinforcement effort is being pursued through an active monitoring, measuring and analysis program. Ultimately, situation rather than site specific design will ensure continuing high quality ground support and reinforcement installations. However, local structural and lithological factors will continue to become more critical as the optimum position is reached.

Jan 1, 1993

By Richard F. Hammen

Mineral extraction from sulfide ore deposits usually leads to the combined action of oxygen and water on the newly exposed ore. The result is acid mine drainage, a low pH solution of various metal sulfate salts and sulfuric acid. Paradoxically, the valuable metals dissolved in acid mine water are a liability because they are too toxic for discharge but too dilute to recover economically. The expense of compliance with water quality release standards has reduced the profitability of many mining operations. Solid phase extraction (SPE) columns have been developed to extract metals from acid mine water. These columns are designed to remove the toxic elements from water and recover the metals as purified fractions. This article describes the results of a Phase 1 bench-scale project to test the performance of the SPE columns. The tests were conducted with water collected from the abandoned Berkeley Pit copper mine in Butte, MT.

Jan 1, 1993

Martin Mining and Tunnelling Pty Ltd is a mining contractor with offices in Kalgoorlie, WA, Australia and Timmins, Ontario, Canada.Martin Mining and Tunnelling Pty Ltd offers services in mine contracting which include shaft raising, raise enlarging, excavation of rock passes and ventilating systems. It also offers the mining industry a unique mining method using the Alimak raise climber system.The Alimak raise climber system may be utilised in various types of orebodies, as the system is flexible to change. Sloping widths, drill hole patterns and changes in dip can all be accommodated with this method.This system allows for a highly productive, cost-efficient alternative to conventional longholing methods. This paper will focus on various aspects of the Alimak system which inherently make it a safe, viable method of ore extraction.

Jan 1, 1993

Novel techniques were developed to obtain samples from and make measurements in the shaft of the flash furnace at the Kalgoorlie Nickel Smelter. The data obtained was used to validate mathematical models of the burners and the reaction shaft. Particle, gas and wall temperatures were measured along with the oxygen potential of the molten particles. Collected particles were characterised by sizing, chemical analysis and optical microscopy. The region of the shaft immediately beneath the burner where the rate of change was most rapid received special attention.

Jan 1, 1993

By J. A. Arias

The oxidation kinetics of pyrite and refractory gold concentrates in acidified ferrous sulfate solutions in the presence of oxygen-sulfur dioxide gas mixtures has been studied. The effect of temperature, pulp density and gas composition were determined. The optimum oxidation rate was obtained at 80°C and 2 percent sulfur dioxide in the gas mixture. The oxidation of the sulfide minerals is attributed to the presence of ferric ions, which are continuously regenerated by the gas mixture. The objective of this study is to find a new hydrometallurgical method to render sulfidic refractory gold ores amenable to cyanization.

Jan 1, 1993

By Stephen R. La Brooy, Tong Deng, Pritam Singh, David M. Muir, A. J. Monhemius, G. W. Warren, E. Peters

The controlled addition of ammonia to cyanide solutions inhibits the leaching of copper minerals but extracts up to 80% Au using as little as 10% of the cyanide compared with conventional cyanidation of copper-gold ores. The solubility of copper minerals and copper speciation in solution is dependent on NH3, CN-, pH and Eh. Rotating disc and electrochemical studies show that gold is leached by a mixed Cu-CN--NH3 complex with either Cu(II) or O2 as oxidant. This complex is slowly oxidised to CuCN and Cu(OH)2 by air.

Jan 1, 1993

By M. England

A method for the analysis and prediction of single pile displacement behaviour is described. It is the displacement in time, under constant load, based on the use of hyperbolic functions to characterise individual constituents of the displacement-time behaviour. Extensive use of this technique has confirmed its validity in a variety of soils and that consolidation and creep settlement appear to be indistinguishable. The algorithms employed are suitable to model the displacement behaviour from the onset of load to infinite time for all types of piles and surface foundations. Until the advent of computer controlled static load testing, analysis of the displacement-time characteristic during pile load tests has been hindered by the quality of the data recorded and inconsistency of loading. This has hitherto made the development of suitable behavioural models very difficult. Understanding the soil deformation within a proper time framework allows the subject of pile instrumentation and testing to be developed. The equipment required is basically a computer controlled loading and pile head displacement measuring system which allows accurate analysis of the settlement characteristic in almost every situation.

Jan 1, 1993

By Gutsche O, Kapur PC

Experimental data on the production of fines as a function of specific grinding energy consumption show that in general the energy utilisation in a choke fed high-pressure roll mill is higher than in a ball mill, but lower than in the single-particle mode of comminution under slow compressive loading. There is some evidence to suggest that the presence of water in feeds improves the energy efficiency of pressurised roll milling somewhat. Within a wide range of energy input, the size distributions of the ground product are self-similar, the logarithmic median size decreases linearly with the amount of fines produced and the inverse of the median size increases linearly with the energy spent. The production of fines as a function of energy expended follows essentially the same pattern as the one frequently encountered in media mills. The kinetics of grinding in the high-pressure roll mill can be simulated satisfactorily by modifying the standard particle population balance equation in order to account for energy dissipation in the tightly compressed bed. Common characteristics and important differences in grinding by the media mill and the high-pressure roll mill are highlighted.

Jan 1, 1993

By Carla J. Moore

The National Geophysical Data Center (NGDC), Marine Geology and Geophysics Division and co-located World Data Center-A for MGG archives and distributes global marine sediment data from U.S. and international sources. NGDC is part of the U.S. Department of Commerce, National Oceanic and Atmospheric Administration (NOAA), National Environmental Satellite, Data, and Information Service. NGDC offers a variety of digital marine sediment data sets including sediment descriptions, textural analyses, geochemistry, paleontology, paleomagnetism, and well logs. Some data sets are compiled by outside sources and sent to NGDC for distribution; many are received under exchange agreements and through the World Data Center system. Other data sets are compiled at NGDC, frequently in cooperation with other government agencies or academic institutions. One of the best examples of the latter is the Index to Marine Geological Samples, or "Core Curators' Database".

Jan 1, 1993

By Krokhmai VS, Sayko OP

The paper summarises the theoretical and experimental studies which led to the development of new industrial equipment designed to recover liberated gold from placer gravity concentrates. The new technology is based on environmentally clean magnetic methods, which avoids use of mercury in the production process and obtains higher gold recoveries compared to the amalgamation technique, and which can reach 98.6 - 99.5 per cent. The complex of equipment thus developed is now commercially used at nine Russian gold mining operations. Six more such complexes are due to come on stream in 1993, some of them outside the CIS. The new technology appears to hold much promise for the recovery of precious stones (diamonds, rubies etc) semi-precious stones (pyropes, chrysolites etc) and also artificial diamonds, for which case there are encouraging laboratory results.

Jan 1, 1993

By W. M. Cross

The hydrophobic character of sapphire surfaces in SDS solutions was examined with respect to the aggregative nature of the adsorbed surfactant phase. It was found that, at equilibrium, sapphire surfaces having adsorbed SDS bi-layers exhibited no contact angle. Conversely, when the adsorbed SDS was found to be mi-cellar in nature, sapphire surfaces developed significant hydrophobic character. The surface states as detected by Fr -IRIIRS conformational analysis were found to be reversible with temperature. The variation in adsorption density with temperature was studied by in situ Fr-IRIIRS. The isosteric heat of adsorption was calculated to be -1.6 kcal/mole. Although the adsorbed SDS was found to undergo a reversible phase change between 25 and 32°C, similar to SDS in solution, the extent of adsorption was not reversible with temperature.

Jan 1, 1993

By Jin C, Shu H

The effect of operating parameters of a shaking table on the separation of mixed quartz-magnetite artificial feed has been experimentally investigated by use of laboratory-scale shaking table. Based on a great number of experimental data collected, the multi-variate non-linear model of shaking table has been developed. The model allows for the calculation of the product grade and recovery. A computer model has been programmed, for inclusion in a software package for the simulation and optimisation of shaking table if the feed characteristics and the concentrate grade are given.

Jan 1, 1993

By Richard L. Ranich, Frank F. Aplan, J. B. Hiskey, Robert S. Thompson, B. J. Scheiner

Acidic waters typified by acid mine drainage, copper dump leach solutions and steel pickle liquors will typically contain SO4-2 and cations such as Fe+3, AI+3 and for the pickle liquors, sometimes Cr+3. These acidic waters will often react with limestone, present naturally or introduced for purposes of solution neutralization, to form reaction - inhibiting coatings of gypsum and gelatinous, metal hydroxide precipi¬tates. The coating thickness, as a function of pH, was quantified for both reactive (calcite, limestone) and non-reactive (quartz, barite, fluorite) minerals, and the data were related to the hydroxy species diagrams and to solution turbidity measurements. Coatings were found on the reactive minerals at a lower bulk solution pH than on the non-reactive minerals.

Jan 1, 1993

By Tong Zhilin

The reasons why the pits were formed on the cathode in the process of Ni electrowinning and the methods how to prevent these pits from forming are described. Some examples are presented. It has 'been proven that P507 and P204 present in the electrolyte can effectively prevent pits from forming on the cathode.

Jan 1, 1993

By Ray Zelinski

Caltrans sponsored a research project in 1992 which incorporated proprietary and generic pile types. The piles were subjected to axial tensile/compressive loads in deep, soft soils. Descriptions of various pile types and systems, scenarios leading to the proposal to test the systems, and load test results were/will be provided by other presenters at this seminar. Therefore, this paper will focus on the issues surrounding use of test results and proprietary pile systems on Caltrans construction projects. The primary issues facing Caltrans during implementation are as follows: 1) producing pile cap designs for a range of pile types and loads; 2) providing construction specifications which allow fair competition among the system vendors, yet assure design and ultimate capacities; 3) Develop quality control standards for pile system materials and installation techniques which guarantee pile durability for static and dynamic loads; and 4) assure that foundations have adequate lateral capacity.

Jan 1, 1993

By Zhanjing Yu

In this paper, an equation is developed to characterize the relationship between the UBC and plate size using a boundary integral approach. The equation was validated by the results from mo& than seventy (70) plate loading tests of different sizes conducted in various underground coal mines throughout the Illinois Coal Basin. The equation indicates that the UBC decreases as the plate size increases. The fundamental solution for this boundary integral problems is the Boussinesq equation. The load exerted by the plate on the floor surface is assumed to be uniformly distributed. Both normal and tangential loads are considered. It is also assumed that the floor fails in shear in a plate loading test. The equation may provide the mine operators with a useful tool to obtain from a plate load test of any plate size the UBC value required by the regulations.

Jan 1, 1993

By R. V. Ramani

One area of study in the Coal Mine Injury Analysis project was to illustrate and enhance the ability of mine safety management personnel to apply analytical techniques to injury experience data and to justify requests for funds for safety enhancement actions on a cost/benefit and other quantitative basis. Four volumes of this final project report detail (1) the objectives and scope of the mine safety management research, (2) the results of literature review, and case studies, and (3) models developed for mine safety management. The four volumes are titled as Volume III: Mine Safety Management, Volume IV: Analytical Techniques for Mine Safety Management; Volume V: Mine Safety Management Case Studies and Volume IX: Training Cost Model. In this volume, the quantitative procedures that have been developed for the mine-specific analyses of accident/injury experience data are presented and their applications are demonstrated in a summary form through case study examples. The quantitative procedures will aid mine safety management personnel to develop focused accident prevention strategies including training, as well as to justify the investment in such proactive programs through cost-benefit analyses.

Jan 1, 1993

Mining software systems have provided a basis for integration of resource, survey, and design functions. They can similarly provide a basis for incorporating ground conditions into the process.Exploration and mine geologists have a prime role to play in this process, extending their responsibilities further across the geological spectrum, into exploration of ground conditions, analyses of results, and assessments of their implications for mining. Ground conditions are as much a part of the geology of a prospect or mine as its mineralisation, and can have critical imnlicationa for mining.

Jan 1, 1993

By Richard C. Travis, Edward C. Dowling

A detailed kinetic study of the flotation installation at the Metcalf Concentrator revealed a rougher flotation circuit operating under less than optimal conditions. Based on these results, a project was initiated to approximately double the rougher flotation capacity by increasing the installed volume from 780 cubic meters to 1,560 cubic meters. This project, which was completed in early 1991, replaced the existing cells with larger capacity cells. A comprehensive analysis of results demonstrates significant metallurgical benefits. INTRODUCTION/BACKGROUND The Metcalf Concentrator is located in Morenci, Arizona and is part of Phelps Dodge Morenci, Incorporated. Sumitomo Metal Mining of Arizona is a minority partner in the operation with 15% interest. The Metcalf Concentrator is the newer and smaller concentrator and operates in conjunction with the Morenci Concentrator. Operating capacity at Metcalf is currently 48,000 TPD of ore on a 365 days per year basis. The Metcalf Concentrator was commissioned in 1974 at a 30,000 TPD operating rate for the purpose of treating ores originating in the Metcalf Mine. The mine takes its name from the former town of Metcalf which was named for Robert Metcalf who was credited with discovery of the mineral district. The predominant ore mineral is chalcocite which occurs as a secondary enrichment closely associated with iron pyrite. The host rock is largely granodiorite and quartz monzonite. The original rougher flotation circuit consisted of a total of six rows of Wemco 8.5 cu. meter (300 cu.ft.) flotation machines treating pulp from the two grinding sections (Sections A and B). Each row was configured in a 4-4-4 arrangement. Shortly after startup the throughput rate was increased significantly without sustaining a recovery loss. This increase was achieved by raising the target value for the particle size of the cyclone overflow which is the rougher flotation feed. Shortly thereafter, the capacity of the pump and cyclone began to restrict further increases in throughput. After testing, two 66 cm. (26-in.) cyclones and a 12-in. X 12-in. centrifugal pump replaced the original classification equipment. As a result of these modifications, the grinding section could routinely process in excess of 42,000 TPD. Due to the increased tonnage rates, limitations in the rougher flotation circuit performance were observed. In an effort to improve the performance of rougher flotation with this higher throughput, the speed of the flotation mechanisms was increased from 230 RPM to 250 RPM. This change improved the suspension of the coarser feed and induced additional air into the pulp. It did, however, apply additional strain to the motors, shortening their life. At these elevated processing rates, it was found that the dart valves operated almost entirely at the top end of the control range and could not efficiently handle upsets from the grinding section. This was remedied by lowering the end overflow weir and allowing some of the tailings to overflow the end weir. However, in order to obtain acceptable recovery levels, the flotation pulp was maintained at a high level, adversely influencing the rougher concentrate grade.

Jan 1, 1993

By R. Gong, R. Bhaskar

The development of a three-dimensional mathematical model for evaluating airflow fields at a continuous miner face is described. The model utilizes three-dimensional incompressible flow, mass continuity, and momentum (Navier-Stokes) equations to predict the airflow velocity at the face. Obstacles and equipment in the face area are modeled using appropriate boundary conditions. Parameters such as flow velocity and face dimensions can be modified and evaluated for various schemes, such as exhausting and blowing ventilation, using either brattice or tubing. A model such as the one described, with additions for local effects, can be used to evaluate novel face ventilation ideas before initiating expensive full-scale tests or field studies. The model described is a step in the direction of advanced predictor models.

Jan 1, 1993