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By D. M. Muir

Thiosulfate offers a nontoxic alternative to cyanide for processing gold ores. The mechanism of leaching gold using ammoniacal thiosulfate solution is driven by the Cu(II)-Cu(I) redox couple and is complicated by competing ligands such as NH3 and S2O32; It is shown that an understanding of the copper speciation and sulfur speciation is required to optimize this system. This paper presents Eh-pH and speciation diagrams for varying concentrations of Cu(II), S2O32- and NH3 and discusses the conditions under which various copper and sulfur species are stable.

Jan 1, 2002

By A. Unal, R. L. Grayson

The use of radio frequency identification (RFID) technology to solve informational needs in isolated and restricted underground mining environments are reviewed, and the specifications of some of the past and currently available systems are presented. The advantages and disadvantages of using various frequencies, system configurations and specific components, including their construction standards and capability, are also discussed. The remaining challenges to the more widespread use of RFID systems for personnel and vehicle tracking are identified, and recommendations concerning the operating environment capabilities are detailed. Finally, the ultimate requirements for maintaining system integrity during and following a coal mine emergency are discussed.

Jan 1, 1999

By R. Y. Wan, Corby G. Anderson, L. Ernest Krys, M. C. Fuerstenau

Since 1942, refractory precious metal concentrates at the Sunshine mine have been processed for antimony metal recovery using a novel leach-electrowin method. This is counter to most antimony production facilities where pyrometallurgical techniques are usually relied upon. The key step for removal of the antimony has been an ambient pressure alkaline sulfide leach. In 1990, a comprehensive laboratory study was undertaken to better understand this process. Factors studied included temperature, agitation, concentrate regrind, alkaline species concentrations, sulfur species concentrations and solids concentration. Details of these studies, as well as a brief description of Sunshine metallurgical processes, will be presented.

Jan 1, 1993

By R. Larry Grayson

A survey of 1250 surface and underground coal mines across the United States was made according to a stratified sampling technique based on national coal districts. A total of 171 responses (13.7% response rate) have been returned and summarized, giving a picture of computer usage in the coal industry. Overall, 63.5% of the respondents use computers, but the percent varied from 100% for large mines to only 44.1% for small mines. As expected, a proliferation of microcomputers has pervaded the industry. Importantly, in spite of the high usage of computers in the industry, sophisticated engineering applications have not yet burgeoned.

Jan 1, 1989

By Samir Kumar Das

Presently Geographic Information System (GIs) is gaining wider acceptance id appreciation in various resource management surveys, generation of various thematic maps, various scientific investigations, environment assessment, disaster management, etc in India but they are general in nature. A huge number of Global Positioning System (GPS) based "Total Station" are playing good roles in India for accurate and quick surveying . The GPS based real time Mine Management and Truck Dispatching System for optimization of productivity is being installed in the Panchpatmali opencast bauxite mines of India. This paper dealt in depth on GIs and GPS and their present roles in the Indian mining scenario.

Jan 1, 2002

By Jack M. Jodrey, Neil D. O’Donnell, R. A. Metz

Bituminous sands of the Lower Cretaceous McMurray Formation in northern Alberta constitute the ore for the surface mining operation at Syncrude Canada Ltd. These sediments represent a complex succession of fluvial, estuarine and marine depositional environments. Grade prediction is realized through a combination of geological interpretation, computer modeling, and reference to past mining experience. Accurate forecasts of feed grade permit reliable predictions of volumes for removal to meet budgeted synthetic crude oil production. This planning facilitates efficient allocation of mining equipment and resources. The feed grade to the Extraction Plant is monitored at various points along the delivery system.

Jan 1, 1992

By Houston Kempton, David Atkins

Mining in semi-arid climates can produce environmental impacts that will not begin for hundreds of years, but once started, may continue for thousands of years. Pit lakes may eventually exceed toxicity thresholds as metals are evaporatively concentrated, and slow unsaturated flow through acid-generating waste can eventually load several kg-SO4/m2-yr to underlying water tables. U.S. regulations are poorly equipped to respond to delayed and long-term environmental impacts, delaying permits as operators and regulators grapple with uncertainty. Improved uncertainty analysis, additional long-term mitigation options, and explicit regulatory guidance offer solutions to this dilemma.

Jan 1, 2000

By I. Iwasaki, X. Cheng

A series of batch flotation tests was performed on chalcopyrite-quartzite, on pyrrhotite-quartzite and on chalcopyrite-pyrrhotite-quartzite mixtures. Pulp potential measurements in the flotation tests with single sulfide minerals indicated that each sulfide mineral had its own optimal potential range for flotation. When these results were used to select the potential ranges for the separation of the two minerals from their mixture, their flotation responses changed, and the selectivity of separation was adversely affected. A possible mechanism involving surface alteration through galvanic interaction is discussed, and a method to improve the selectivity of flotation separation is proposed.

Jan 1, 1993

By William G. Fischer

Equations developed by an early researcher in subsidence, F. Martos of Budapest, Hungary, have been slightly modified to produce effective equations for predicting the time-dependent nature of Green River trona mine subsidence. Following the initial study, a survey was run to check the results twenty years after mining of the area had been completed. The final results were within a few centimeters of the value that had been projected. Mining conditions in the Green River area are ideal for this sort of study with trough type subsidence being the surface manifestation of high extraction underground room and pillar caving operations.

Jan 1, 1986

By L. D. Jayaweera, R. G. Robins

The pocessing of gold bearing sulphide minerals wr ich contain arsenopyrite and other complex arsenic sulphide minerals results in arsenic containing emissions and effluents which must be given careful consideration in relation to clean air and clean water standards. The sources of arsenic and the various process options for treating arsenical gold ores and concentrates are briefly reviewed. The problem relating to the removal of arsenic from gaseous emissions from roasting processes is considered. Residues from aqueous processing contain a variety of arsenical materials which have not been characterised, and the long-term stability of these is suspect. 'rhe use of lime to stabilise aqueous residues as either calcium arsenate or calcium arsenite has been shown to be inadequate for long term disposal since both compounds are converted into calcium carbonate due to the influence of carbon dioxide in the atmosphere. Ferric ion solutions have been used to precipitate ferric arsenate or to form ferric hydroxide which binds the arsenic for short term disposal, The long term stability of these ferric materials is poor, but could lead to the acceptance of a slow release option rather than complete containment of residues.

Jan 1, 1991

By Michael Brittan

Diagnostic regression analysis has been used as a tool to improve the recovery efficiencies of numerous gold mills, yielding significant revenue increases. In the course of the analyses it has generally been found that ore head grade is a statistically dominant variable affecting the overall gold recovery. Higher grades invariably generate higher recoveries. Examples are given from several operations in the world's two largest gold producing countries, South Africa and the United States. The plants considered cover the treatment of both oxide and refractory ores. A simple generalized model is presented relating tails to head grade. Since ore grade variations are beyond operational control, operators should not be held accountable for decreases in recovery caused by lower head grades. Conversely, the ore must take credit for many a recovery increase. Rigorous metallurgical test work, feasibility analysis, production planning and budgeting should allow for recovery variations due to grade fluctuations. Since the phenomenon is a reflection of ore geology and mineralogy, which are ore specific, comparison of recoveries at different times or sites is not meaningful without a detailed understanding of the mineralogical constraints on gold liberation.

Jan 1, 1997

By Neil Jagger, Ian Arbuthnot, Mitchell Gordon

Ultra high density underflow is required in many thickener applications and in mineral processing is typically required for tailings to improve the thickened slurry rheology for either tailings dam development or for paste backfill applications. The improved liquid-solid separation resulting from the production ofultra high density underflow has both environmental and process benefits in the gold industry. Additional cyanide is recovered in the thickener overflow thus reducing plant cyanide costs and perhaps more significantly, a reduced quantity of cyanide is discharged to the tailings thus reducing either the toxic effect on the environment or the costs of cyanide destruction. Many gold and other mineral processing plants are situated in arid regions where the cost of water is high and the quantity often very restricted. Ultra high density thickened underflow results in increased recycle of tailings process water to the plant. In Countercurrent Decantation circuits, the wash efficiency is very dependent on the degree of liquid-solid separation in each thickener stage and the benefits ofultra high density underflow are either increased efficiency or decreased equipment costs as it may be possible to reduce the number of stages in the circuit.

Jan 1, 1995

By Darrell M. Hladun, Linda M. Dufour

The benefits of computer simulation in the design of a refracto­ry gold autoclave facility is discussed. Three computer simula­tion programs used for autoclave design are briefly described in this paper. 1) METS IM® - A Process Simulation Software Package Developed by Proware: Mass and energy balances are conducted around the auto­clave and its ancillary processes. Results from the process simulation define process equipment requirements and are used for establishing operating costs. The p_rocess model integrates various unit operations including grinding, acidu­lation, pressure oxidation, counter-current-decantation, neutralization, cyanide leaching, and carbon-in-pulp or car­bon-in-leach. 2) ALGOR® - Finite Element Analysis (FEA): A computer software program is used in the design and analysis of brick lined pressure vessels, such as autoclave, heater, and flash vessels. This software creates a steady state thermal model, and accurately predicts temperature distribution throughout the entire vessel, including nozzles, which represent regions of high thermal intensity. 3) Compress©: A software package developed by Codeware used for the sizing of pressure vessel components, includ­ing shells, heads and nozzles, according to ASME Boiler and Pressure Vessel Code, Section VIII, Division 1.

Jan 1, 1996

By M. S. Walton

A conference attended by a limited number of invited participants was held last September in Denver under the auspices of the Underground Construction Research Council of ASCE funded by the National Science Foundation (RANN) to explore the problem of accelerating the transfer of advanced geophysical technology, used principally in the petroleum exploration industry, into more effective and widespread use in subsurface investigations for underground construction. There are technological problems, but technical difficulties and unfavorable ratios of benefits to costs are not the major obstacles. The problem centers on the complex way in which potential net benefits are translated into effective incentives to innovate for each actor in the complex web of individual, corporate and institutional entities involved in the planning, designing, building, funding, operation and ownership of major underground construction projects. The entities responsible for site investigation, design concepts and specifications do not directly bear the risks of unanticipated costs and failures, nor directly gain from savings. The conventional unit-price construction contract is strongly implicated in blocking innovation. Problems of risks and incentives, more than technical feasibility, must be solved before large investments in technical adaptation and adoption can occur.

Jan 1, 1974

By L. C. Morales

Mexico has an area of about 2 million km2 (772,260 sq miles), with volcanic activity, large shores and mountainous areas reaching as high as 6000 m (19,680 ft) above sea level. These conditions are favorable for most mineral deposits, some of commercial value and others as a source of mineral samples. In addition to its vast mineral wealth, Mexico has another valuable asset in its people. Even before the discovery of America, natives were successfully mining metals. During the colonial days, the mineral deposits were mined to increase the wealth of Spain. All this experience was passed from generation to generation. It created a tradition of mining and minerals processing engineers that currently accounts for about 182,000 people supported by mining-related activities. Nonmetallic minerals in Mexico have been mined by natives since the early days. They knew the value of kaolin clays for pottery, as evidenced by archeological findings. This experience was also passed from generation to generation and has become recognized worldwide as ceramic wares of high quality. The Talavera ceramic from Puebla is an example of family traditions many generations old.

Jan 1, 1994

Iron removal using biologically produced organic acids was investigated as a treatment option for the production of refractory grade bauxite. A leaching solution containing 98mM oxalic and 67mM citric acid was prepared from a sucrose medium using for fermentation the fungus Aspergillus niger. The leaching capacity of the metabolic product was tested on a bauxite sample containing 16-19% iron (as Fe2O3). Aerobic and anaerobic leaching tests were carried out at pH 3, 50°C and in the absence of light. Results indicated that more than 80% of total Fe can be removed from the ore, when the sample is finely ground and applying a two stage treatment. The presence of oxygen was seen to affect adversely the kinetics of the process, suggesting that leaching follows a reductive mechanism. Experiments that were carried out with different particle size fractions indicated that for obtaining efficient removal of iron particles should be finer than 0.63mm. Reduction of the operating temperature from 50 to 30°C caused a decrease in the rate of iron removal by more than 10 times.

Jan 1, 2006

By Stuart K. Nicol, Malcolm D. Engel, Neville T. Moxon

Ion flotation of gold is a process continuing to be developed to selectively beneficiate dilute aurocyanide liquors using a novel surface­active complexing agent. Aeration of these liquors causes accumulation of the precious metal species in the froth concentrate produced in a flotation column. Successful development of ion flotation for concentrating solids-free liquors would offer a low--cost method for recovering specific metals from heap leach runoff or waste tailings solutions. The cost of constructing and operating a 100 tph gold ion flotation facility has been compared with the relevant carbon adsorption plant costs. Reductions in operating costs of 25% and installed capital of 40% are possible in relevant expenditure areas. For an 'average' processing plant, this equates to annual operating savings of A$ 170 000 and a capital saving of A$ 515 000, with a three-point increase in total (mine and plant) site DCF ROI. High gold inventories are eliminated and the number of processing steps is reduced. The application of gold ion flotation will initially be confined to heap leach operations in the western U.S.A., although use of the process in mine abandonment programmes elsewhere is also an area of future development.

Jan 1, 1992

By Kathryn C. Sole, Angus Feather, Leslie J. Bryson

A novel solvent-extraction route for the production of high­purity gold has been successfully demonstrated on a pilot-plant scale, and the first full-scale production plant is being commissioned. This plant, at Harmony Gold Mine in South Africa, is designed to refine 24 tons of gold per annum when operated for one shift per day. The commercial implementation of this process represents not only a significant advance in gold­refining technology, but may also be instrumental in initiating important changes in the legislation regulating the marketing of gold in South Africa. The Minataur™ Process (Mintek Alternative Technology for Au Refining) is able to produce gold of either 99.99% or 99.999% purity from intermediate process products having a wide range of gold contents. The process comprises oxidative leaching of the feed material, followed by selective solvent extraction of the gold from the leach liquor to reject impurities, and then precipitation of high-purity gold powder. This paper introduces the process, presents selected results of pilot-plant trials in which high-purity gold was produced from two significantly different feed materials, and illustrates some of the applicable cost benefits.

Jan 1, 1997

By M. David Monroe

Getting the best match between truck and haul road requires examining the cost effects of many factors. Most mines use a bottom line measure based on cost per ton of material moved. This measure focuses on the two components of truck haulage cost per ton: productivity (or performance) and operating cost. For specific tasks, productivity can be measured or predicted using either field measurement or modeling. Individual tasks can be combined to provide a larger scale, longer term net figure for total mine output. True cost is more difficult to capture. Factors are time- and task-oriented and can be influenced by a summation of factors over a truck's lifetime. For example, "allocated" costs, such as owning (depreciation) and some repair costs, are spread over long periods. Items such as fuel and tires can be tied more directly to certain tasks. This article focuses on the more direct, task-oriented factors that affect truck productivity and cost. Major factors The relationship of haul roads and trucks means that each must be examined separately to isolate the most important factors affecting performance and cost. There are many factors but the most important are:

Jan 1, 1992

By Andrew H. Stearn, Robert O. Agbede, Edward F. Divers

The ability to compete profitably in a competitive, demanding and specialized market, requires all components of productivity to be optimized toward the same manufacturing goal. This ever present requisite is seldom more apparent than with the quality control (PC) considerations that confront the super-refined metallurgical production necessary for today's exacting technical applications. In a work-place that already exceeds all environmental standards for cleanliness, this paper describes the development of specific environmental mechanisms and controls implemented at a titanium processing facility to impact both the minimal air-borne particulate contaminants and excessive process heat generation which are believed to degrade product purity. Based on the analysis of a carefully structured and instrumented field survey, two alternative solutions were proposed to modify the present facility utilizing a forced air (blowing) system. The first scenario requires ambient air to be drawn from a louvered rooftop installation and ducted to specific zones within the plant with appropriate weighted louvers and wall and roof exhausters designed into the system for air control. The second scenario incorporates a properly sized baghouse to be used in conjunction with the first system.

Jan 1, 1991