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By Byron K. nelson, David Mathieson

Until quite recently concentration of free gold in gravity circuits ahead of froth flotation and/or chemical treatment was considered an uneconomical pursuit in many gold pi.ants in Australia. Over the past 10 yenrs since initial introduction of the Knelson Gold Concentrator, over 600 hnvc been surpl led world wide and they have been developed to the stage that Lhey can now be utilised in almost all instances where free gold appears in significant quantltles ln grinding circuits. They out perform and displace more conventional gravity sepnration equipment such as spirals, tables, sluices, jigs, drum separators etc.

Jan 1, 1991

By Jody Kelso, Thomas R. Clark, Gregory J. Olson

Refractory, sulfidic gold ore from the Metates deposit in Mexico was tested to determine if it could be heap biooxidized to improve gold extraction. Small column tests were conducted in a manner consistent with anticipated process conditions: increased tempera­ture due to oxidation of the high sulfide content ofMetates ore and full recycle application of leach solutions containing high concen­trations of dissolved solids. Biooxidation by thermophilic (heat­loving) microorganisms was tested to determine: 1. the extent of sulfide oxidation and bottle roll precious metal recovery, 2. reagent consumption, and 3. potential solution flow problems due to mineral precipitation.

Jan 1, 1998

By Hans von Michaelis

Very little has been published about Cia de Minas Buena­ventura. Don Alberto Benavides Quintana, now in his seventies, founded the company in 1953. This venerable gentleman is a Doyon of the Peruvian mining industry and more has been known about him than about his company. Buenaventura is a highly profitable gold producer with excellent potential to expand gold production in joint ventures with Newmont, Southern Peru Copper (ASARCO), and BRGM as well by developing their own new gold mines. On September 15, The Wall Street Journal published an article titled "Peru's Big Rebound Sets Off Foreign Investors' Enthusiasm."

Jan 1, 1995

By Brian T. Field

Development of cost effective technology for whole ore roasting of refractory gold ores is an important requirement to increase recovery rates as ore grades become more carbonaceous and sulfidic in nature. It is important that the industry focus on the further development of cost effective, environmentally sound technologies to roast this ore. Traditional technologies have centered around bubbling and circulating fluidized beds with and without oxygen enrichment. Fuller Company has developed a process to flash roast refractory ores in its pilot plant with the R&D results, commercial scale up issues, and indicative economics discussed herein.

Jan 1, 1993

By H. S. Rathor

In a major hydropower project in the Himalayas, during excavation of tunnel, hydrothermal gradient line appeared and caused extremely unfavorable conditions with rock and water temperature varying between 55°–66°C and nearly 100% humidity. Major changes in method of excavation, schedule of works, deployment of additional equipments and acclimatization of personnel were made to complete this unfavorable stretch of world’s longest Head Race Tunnel. The case study covers the various aspects of tunneling in geothermal rocks, inhuman working conditions, loss of production, cost overrun, contractual claims and strategy to manage such unfavorable working conditions.

Jan 1, 2003

By A. D. Davis, D. J. Dixon, J. L. Sorenson, C. J. Webb, S. Dawadi

Limestone-based material appears to be an effective arsenic removal process that has great potential for source reduction in drinking water. Limestone-based material offers several benefits to the drinking water community: 1) reasonable removal efficiency as compared to material cost, 2) broad geographic and water system applicability, 3) compatibility with other water treatment processes, 4) ease of technical use, and 5) low-cost disposal in ordinary landfills. Batch and column experiments have evaluated the removal efficiency of several limestone types. Additives and material alteration have increased the removal efficiency. Granulation of powdered limestone as a filter media currently is being investigated.

Jan 1, 2006

By A. D. Shuloyakov, V. A. Zukerman, G. A. Finkelstein, V. I. Kurets

Possibilities of electric pulse disintegration are discussed with emphasis on high selectivity of the process as compared to mechanical comminution methods especially when applied to polymineral ores. Physical explanation of this phenomenon is suggested. The authors present results of some experimental tests illustrating regularity of this phenomenon irrespective of origin of ores or dissemination pattern of valuable minerals including both dissipated and accessory minerals. Some operating plants applying this principle are described the plants used either for mineral research purposes or for obtaining pure monomineral fractions or for treatment of gems to be faceted. Obstacles for implementation of this technology are mentioned.

Jan 1, 1995

By D. D. Harbuck

The US Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent, such as SO2 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage countercurrent leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with SO2 or sulfuric acid.

Jan 1, 1991

By S. K. Mishra, R. L. Lytton, D. Sinn, D. Saylak

Calcium chloride is widely used for dust control on unpaved roadway surfaces, in base course stabilization, full depth reclamation and for total reconstruction of asphalt roads. Fly ash produced from coal-burning electric power plants have also been used in road construction. This paper examines the synergistic effect of calcium chloride and fly ash on compaction density and strength development of unpaved roadways. A mathematical model has been developed which provides excellent agreement with the experimental data. Based on these results, the potential of calcium chloride - fly ash treatments for typical mine road construction is discussed.

Jan 1, 2004

By Barbara Fotta

This article examines health and safety trends during the past 10 years at Appalachian surface and underground bituminous coal mines. Data for Appalachia include Pennsylvania, West Virginia, Virginia and eastern Kentucky. These states account for more than 90% of the coal production in the Appalachian region. (Production, accidents and fatalities in Ohio, Maryland, Tennessee and Alabama are not included in computing Appalachian trends.) Trends for Appalachian underground mines are differentiated by size and mining method into three categories: - Small mines with fewer than 50 employees. - Large nonlongwall mines with 50 or more employees. - Longwall mines (mines with at least one longwall production face).

Jan 1, 1995

By J. C. Judd, D. D. Harbuck, M. D. Odekirk

The US Bureau of Mines investigated germanium and gallium extraction from an ore containing 0.089% Ge and 0.036% Ga. While previous researchers concluded that a reducing agent, such as SO2 is needed to extract germanium and gallium from such ore, this research showed that high extractions (87% Ge, 97% Ga) were possible using sulfuric acid alone, if the acid concentration were properly controlled. This control was achieved using a two-stage countercurrent leach circuit. Microprobe analyses revealed that the non-extracted germanium is in solid solution with quartz, and therefore cannot be leached with SO2 or sulfuric acid.

Jan 1, 1992

By L. Xiao, P. Somasundaran

Using potassium oleate as a collector and alizarin red S as a modifying agent, selective depression of dolomite from francolite was achieved in an alkaline medium (pH > 9.0). Adsorption of alizarin reds alone on dolomite was found to be higher than that on francolite. Complimentary adsorption experiments of alizarin red S and oleate showed that oleate adsorprion was increased in the presence of alizaring red S. The results are explained in terms of comparative adsorption for the active sites on francolite and dolomite by oleate and alizarin red S and their interactions with dissolved mineral species in solution.

Jan 1, 1990

By C. R. Jenkins, G. S. Taylor

Three sedimentation ponds had their performance evaluated before and after installation of modifications. Each pond had a floating baffle installed, two had siphon outlets, and one had a floating outlet device. Baffles inhibited short circuiting, and the outlet devices retarded flow following a rainfall event and drained the pond, creating a large storage volume to maximize detention time. Total suspended solids and settleable solids tests were measured on samples of influent and effluent to evaluate pond performance. Particle size analyses were conducted on samples containing measurable amounts of solids. Performance improved in each pond, with baffles providing the major improvement.

Jan 1, 1987

By Y. Akin, M. S. Celik, T. Batar, F. Arslan

Despite its importance in various diverse industries, research on beneficiation strategies of boron minerals has not received enough attention. Boron minerals are primarily upgraded by wet processing methods. However, severe environmental constrains have accelerated the development of dry processing techniques such as calcination. Interestingly, the boron minerals colemanite, ulexite and borax undergo decrepitation, shrinkage and expansion, respectively, upon heat treatment. Each mineral then requires a different beneficiation scheme. In this study, laboratory and pilot-plant studies conducted in our laboratories on the calcination of boron minerals are briefly reviewed and their implications to commercial operations are discussed.

Jan 1, 1999

By C. Alexander

Stillwater Mining Company is developing a second underground palladium and platinum mine approximately 21km (13 miles) west of their existing Nye operation in south central Montana. A 5650 meter (18,550-foot) tunnel is required to gain access to the ore bearing horizon (J-M Reef). Access and primary mine development can be accelerated through the use of two 4.6 meter (15-foot) diameter tunnelboring machines (TBM). One TBM was purchased new while the other was purchased used. Machine specifications, site support facilities, portal/launch chamber construction, TBM assembly, startup and operation are discussed in this paper.

Jan 1, 1999

By D. Papacharalampos

A combination of decision- theoretic and knowledge-based methods can be used to classify rock-types from satellite data both efficiently and accurately. An expert system utilizes knowledge-based rules, as a field geologist does, to produce results that make geological sense. Our expert system (GEMS), first processes background information from preexisting knowledge and develops a plan, then classifies individual pixels, and finally generalizes the results using geological rules and plots a map. The system is implemented on a microcomputer and is inexpensive enough to be a part of the standard equipment of any geologist who prepares reconnaissance maps.

Jan 1, 1986

By Zhou Aimin, Xie Benxian, Song Chongkai, He Zhexiang, Zhang Changqing

Concrete pump is commonly used to transport paste and high-density backfill over relatively long horizontal distances. However, since the investment in concrete-pump and its operating cost are quite high, the application of paste backfill is limited in China. For seeking an alternative paste backfill technology, squeezed-transport technique and equipment has been developed. The new technology has been adopted at Tonglushan Copper Mine of Daye Nonferrous Metals Corp for overcoming a difficulty of long-distance transportation of high-density cemented tailings fill. It proved to be an alternative paste backfill method with simple backfill system, saving investment and low operating costs.

Jan 1, 2001

By H. Kandemir, G. Neeling, P. A. Spencer

Gold extractions from three refractory sulphide concentrates have been increased by bacterial oxidation with T. ferrooxidans prior to cyanide leaching. Arsenopyrite, pyrite and stibnite were the major sulphide components associated with gold in the concentrates examined. Kinetic oxidation tests were conducted for each concentrate by monitoring iron and arsenic levels in leach slurry. A correlation has been established between the level of bacterial oxidation and gold extraction from cyanide leaching of oxidised residues. High levels of bacterial oxidation have been achieved in approximately 8 days at pulp densities of 20-25/ w/v solids, resulting in 70-90% gold extraction.

Jan 1, 1987

By R. J. Wesely, A. D. Zunkel, Tracy B. Braun, Philip L. LeHoux

An overview of gold processing operations at Barneys Canyon Mine is presented with particular emphasis on ore agglomerating experience, leaching and metallurgical accounting practices, and carbon column plant operating approach. The mine, located thirty kilometers from downtown Salt Lake City, is just eight kilometers north of the Bingham Canyon copper mine. Mining was initiated in February 1989 and the first gold was poured in September 1989. Through year-end 1992, approximately 7 million tonnes of ore have been processed and 12,000 kg of gold have been produced. Gold recovery is in excess of 85 percent.

Jan 1, 1993

By A. Knoll, J. W. Beck, W. C. Brice, E. K. Lehmann

A cooperative study was undertaken in a neutral atmosphere by representatives of the environmental community, the mining industry and state government to identify and resolve environmental issues associated with base and precious metal mining before a commercial mining development is announced. The study included testing Minnesota's as-yet-untried nonferrous mining regulatory program using three hypothetical mining developments sited in environmentally sensitive areas where future mining could occur. Results include identification of critical paths for regulatory decision making, identification of particularly sensitive environmental issues that mill need continued deliberation before resolution and characterization of data necessary for environmental review and permitting decisions.

Jan 1, 1992