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By D. R. East

Recent experiences within certain sectors of the international mining industry suggest an underestimation of the environmental risk associated with the design of mine waste management facilities. These experiences show that the technical and managerial challenge of responsible mine waste management is not always fully appreciated. Unfortunately, the image of the mining industry's environmental performance is negatively impacted by a relatively few number of failures. This negative view overrides the many positive contributions made by the majority of mining companies. The fact that these failures continue to occur to this day in both developed and developing countries is indeed remarkable, and indicates a degree of risk-taking approaching unacceptable levels. The design requirements for tailing storage facilities are, in many cases, more demanding than those of conventional water dams, because seepage of fluids which contain dissolved metals may pose a greater threat than the mere loss of water.

Jan 1, 1999

By Betty L. Gibbs

The ultimate objective of mine design is to determine the development and untilization of mining resources. Computer Aided Design (CAD) and automated mapping are becoming very popular in engineering and in mining. Any computer program which produces a design or model with the interaction of an engineer can be considered computer-aided design (CAD), but' the term CAD is often associated with interactive graphic design and mapping capabilities. Graphics can be effectively used to describe and model two-or-three dimensional mine workings, orebodies, and geologic structures. Interactive computer graphics is applied to mine design with a combination of deposit modeling techniques and the use of AutoCAD for interactive graphics and mapping. The combined system can perform a large part of the calculations and drafting work for geologic and mining design. Using computer calculation and graphics techniques, comparisons of alternatives, can be made quickly.

Jan 1, 1989

By P. Ollivier

The ore-processing plant of the Soremib mine Pour a (Burkina Faso) has now been in uninterrupted operation for 3 years. Ores from the oxidized and non-oxidized zones of the deposit are processed together in one flotation unit. About 60% of the gold is free and is recovered in a gravity processing unit. The residual gold in the flotation concentrate is processed on the spot by cyanidation and carbon-in-pulp.

Jan 1, 1998

By W. T. Plummer

• The SuperBowl is a fluidized bed, semi-continuous, enhanced gravity separator for gravity gold recovery. The market for this type of equipment has, until recently, been dominated by a single supplier. Many mineral processors have encouraged the SuperBowl designers to develop competitive equipment for obvious reasons. • The primary beneficiary of competition in this field will be the mineral processing community because legitimate competition fosters continuous improvement in product and price.

Jan 1, 1996

By S. G. Tough, H. J. Hignett

The Transport and Road Research Laboratory is carrying out tunneling trials at Chinnor, Oxfordshire, with a 5-m-diam, full-face tunneling machine. The work, which is for research purposes only, involves driving the tunneling machine through chalk with most of the physical characteristics of the machine and its power consumption closely monitered. At the Conference a film was shown about this work, illustrating both the tunnel construction and the research program.

Jan 1, 1974

By B. Beatty

This is a response to M. J. Hrebar's paper, which tracks in detail the highly productive stripping capabilities of modern large bulldozers at two separate installations. It proves the old adage "economies of scale" and quantifies the advantage of being able to move large loads of dirt over comparatively short haul distances by sliding rather than carrying the load. This discussion examines whether a bulldozer is the most efficient way of using this geotechnical principle.

Jan 1, 1994

By Michael J. Virnig, Keith E. Weerts

The development of heap leach technology for the treatment of low grade gold and silver ores has led to a boom in gold production in the Western United States in the last 15 years. The heap leaching process consists of stacking the mined ore on a specially prepared leach pad followed by leaching with dilute alkaline cyanide solution. Depending on the nature of the ore, it may require crushing and/or agglomeration prior to stacking on the leach pad. As the dilute alkaline cyanide solution migrates down through the stacked ore, the precious metal values along with a portion of the base metal values present in the ore are dissolved to give a pregnant leach solution which is collected at the base of the stacked ore. The precious metal values are then recovered by zinc precipitation or by adsorption on activated carbon. Once all of the economic metal values have been leached from the ore, the spent heap leach pad, the leached materials, and associated process solutions must be decomissioned. Decommissioning requires that the spent heap leach pad along with the leached materials and process solution be treated to reduce the concentration of the residual cyanide, base metal cyanide complexes, and other anionic metal species to levels where they no longer represent a long tenn liability for the environment and the operator. The levels to which these components must be reduced is dependent upon the applicable water quality standards as determined by the responsible federal, state, and local agencies. As environmental awareness has grown, these standards have become increasingly stringent. A number of treatment options have been developed for the de-toxification of the process residues. These include natural degradation which incorporates bio-degradation, fresh water rinsing, alkaline chlorination, hydrogen peroxide, and sulfur dioxide/air. Each of these options has been reviewed with regard to relative effectiveness, generation of hazardous by­products, reagent handling considerations, relative costs, and time requirements by Denton, Iverson, and Gosling I. As an outgrowth of the program to develop Henkel's guanidine based gold extractants, COGNIS, Inc., the environmental ann of Henkel, has developed the CyanoMet R process for the extraction and concentration of the various cyanide and anionic metal species from the dilute aqueous alkaline solutions generated during the process of detoxifying spent heap leach pads. This paper describes the CyanoMet R process, its application to three different feed solutions, and treatment of the concentrate generated by the process.

Jan 1, 1993

By Kenneth L. Clifford

We have heard a lot during the recession about the mining industry now competing in a world market for sales of such commodities as copper, lead, zinc, molybdenum, iron ore, and phosphate. If the US mining industry is to survive, do we not have to reduce direct operating costs to a minimum? How significant is labor cost compared to consumables, electricity, fuel, maintenance, materials, and transportation? Ore grade is ultimately the dominant factor; but can we offset its dominance by improving productivity? Is the US mining industry perhaps only 25-30% as productive as it might be? What prevents the industry from being more productive? Can we retrofit older plants to be more productive or does it take a new plant with the largest equipment available for each unit operation? Present Productivity A copper industry study a few years ago covering 13 US copper concentrators ranging from about 10-45 kt/d (11,000-50,000 stpd) showed that productivity did not vary with capacity above 18 kt/d (20,000 stpd). Operating productivity varied significantly, however, from about 180-635 t/d (200-700 stpd) per operating hourly worker in most units, but one operation had 900 kt/d (1,000 stpd). Concentrators with more than 545 t/d (600 stpd) per hourly worker were in the 23 kt/d (25,000 stpd) or more category. Maintenance productivity covered about the same range, but most concentrators were in the 270¬635 t/d (300-700 stpd) per hourly maintenance worker. Again, one company stood well above others by exceeding 1 kt/d (1,100 stpd). Total hourly productivity ranged from 125-280 t/d (140-310 stpd) per hourly worker for most concentrators. The company with the most productive operation, however, was above 455 t/d (500 stpd). Salaried worker productivity for most operations was in the 725 t/d to 1.2 kt/d (800-1,300 stpd) per salaried worker range. The best operation was 2.2 kt/d (2,400 stpd). The end result is, of course, tons per day per total personnel. Most operations fell in the 110-220 t/d (120-240 stpd) range with the best operation at 400 t/d (440 stpd). This is the productivity definition that is most directly related to unit costs. Many of these operations have made some productivity progress

Jan 11, 1983

By S. K. Kawatra

Although temperature is known to have a substantial effect on many processes, this parameter has been widely dismissed as insignificant for mineral comminution. For this reason, temperature effects on grinding have largely escaped notice. However, it has been observed that processing plants which are subjected to large seasonal temperature variations show a change in performance which appears to be due to changing feed temperatures. The general effect is an increase of the specific energy consumption as the temperature decreases. In autogenous mills, an increased rate of production of critical-size material has also been observed. This is due, at least in part, to changing rheological conditions in the mill, with the slurry viscosity increasing markedly at low temperatures. Mechanical changes in the rock with temperature, such as increased brittle fracture, is also responsible for a portion of the observed seasonal effect, and may account for this phenomenon being observed only in certain plants.

Jan 1, 1989

By James M. Barker

IARC classified crystal-line silica as a Group 2A (probable) carcinogen in humans. Adverse classification by IARC, which is a non-regulatory agency, is very significant because many regulatory bodies follow or consider its findings. California included IARC findings in its listing of toxic materials under Proposition 65. OSHA considered IARC findings while promulgating its regulations on hazardous air contaminants. The impact of these scientific and regulatory trends in the mineral industry will be broad. Minerals and materials bearing silica at very low levels will be affected by the "IARC threshold of 0.1% crystalline silica. The regulatory track should follow that of talc and asbestos including the emotional aspects. Silica is much more common than talc or asbestos so, in the final analysis, it may have the farthest reaching impact on industry. Permissible levels set by California and OSHA have usually been lower than industry desires but higher than environmentalists desire. This pragmatic approach will blunt the impact somewhat.

Jan 1, 1989

By J. Rothschild

I would like to thank the Society of Mining Engineers for inviting me as well as the other distinguished panelists to spend a morning reviewing and discussing the handling and shipping of industrial minerals. I also would like to thank my management, Cometals. Inc. for permitting me to take time out from the daily hectic pace of marketing and trading to share with you some of our experiences and expertise. Cometals, Inc. is a wholly-owned subsidiary of Commercial Metals of Dallas. The transportation and handling costs of industrial minerals frequently are a major component of the value of the goods marketed and, therefore, it is only natural that close attention should be paid to them. Many of the industrial minerals require special handling to assure that the material reaches the consumer without being contaminated or getting wet. I invite you to accompany me through the various steps involved in "delivering the goods" to the consumer.

Jan 1, 1989

By Tony Stephens

In this paper I will try to give an overall picture of the use of pure oxygen in gold leaching in South Africa. Pure oxygen has been overlooked as a reagent for many years. Only with the increased sophistication of gold plant instrumentation, greater recognition of the technical abilities of the plant management and a more definite attitude towards plant efficiency has the recent break-through been achieved. There are, today, twelve plants using pure oxygen in this way as a permanent part of their operation and another three or four presently carrying out long-term evaluations. I believe that this number will double over the next few years as more and more plants identify potential benefits. I have, therefore, set out to look at the background and chemistry behind these innovations, describe the various methods available to dissolve oxygen, briefly look at the laboratory and trial work carried out by ourselves at Afrox and then the different installations, both ours and those of our competitors.

Jan 1, 1998

By A. R. Laplante

In this paper, the performance of the Knelson Concentrator and of the batch and continuous Falcon Concentrators are compared. The units are based on different operating principles, and perform quite differently. The Knelson yields very high free gold recoveries over a wide size range of both the recovered and rejected species. It is less effective in recovering very fine (<15 μm) or very flaky gold, as encountered in flotation feeds, concentrates or tails. It is the preferred unit for gold recovery from grinding circuits. The batch Falcon is effective in the fine range, typically less than 37 μm for gold. Its recovery zone is quickly saturated when there is significant heavies in the feed. It works best as a pre-concentration unit, or when sulphide content is low. The continuous Falcon is a versatile unit which is capable of recovering fine heavies (density down to 5 g/cm 3), especially from coarser gangue.

Jan 1, 1993

By Victor F. Hollister

The Society for Mining, Metallurgy, and Exploration has compiled a number of exploration discovery case histories. This section in Volume 3 of the series describes the case histories of deposits found in layered rocks. Metallic and nonmetallic ore deposits described in this section include diverse minerals such as copper-nickel sulfides and carbonate-controlled base metals. Other case history compilations include epithermal precious metal deposits and porphyry systems. The importance of ores in layered rocks justifies their inclusion in a case history compilation. Mineral deposits occurring in layered rocks form an economically important class of ores. For example, most sulfide nickel ores are mined from basic layered intrusive rocks. Although the geologic setting is completely different from economic nickel sulfide concentrations, most barite produced also comes from stratiform and strata-bound ores. Zinc and lead ores importantly occur in beds in carbonate host rocks. Gold and other heavy minerals are concentrated in placer deposits. Indeed, the world&apos;s largest gold deposit, the Witwatersrand, is a fossil placer.

Jan 1, 1991

By K. Brady

Making progress on sustainable development will require greater attention to the management of materials produced from mine exploration through use to reuse, recovery and recycling. Material stewardship is a concept that embodies the range of activities required for optimal and appropriate use of minerals and metals in society. The following paper provides an overview of some recent initiatives that promote the stewardship of minerals and metals in society. The initiatives described are being conducted by organisations ? the International Zinc Association, the Canadian Copper & Brass Development Association and the International Council on Mining & Metals. These associations illustrate stewardship activities at three different levels: - an international association representing companies that produce a range of minerals and metals; - an international commodity association; and - a regional association. For each initiative, information is presented on its development, scope and outlook. This paper draws heavily from work of the associations but the viewpoints are the responsibility of the authors.

Jan 1, 2007

By Keith J. Henley, Nicholas C. Clarke, Paul Sauter

A detailed investigation of the stability in cyanide solutions of native gold and gold-silver tellurides in a flotation concentrate from the Golden Mile, Kalgoorlie, has been undertaken to assess whether leaching under different conditions can be used to quantify the distribution of Au between native gold and gold-silver tellurides, as suggested by, for example, Chryssoulis and Cabri (1990). The leaching was carried out on +20 µm native gold and gold-silver tellurides separated from a high-grade flotation concentrate and then diluted with barren quartz. The material leached assayed 270 ppm Au and 118 ppm Te and the leach conditions used were:- Stage 1: Leaching in dilute cyanide (0 .1 % ) at pH 9 .5 for 24 hours to dissolve native gold but not gold-silver tel­lurides. Stage 2: Leaching the residue from Stage 1 in strong cyanide (2%) and pH 12.5 for 96 hours to dissolve gold-silver tellurides.

Jan 1, 1995

By Luis Tondo, Gary Johnson, Steve Morell

High pressure grinding rolls have been demonstrated by numerous researchers, and at a number of commercial installa­tions to be power efficient comminution devices. They have become almost "standard equipment" in the grinding of cement clinker. However, the technology has been relatively slow to catch on in the mineral processing industry. Part of this may be due to the fact that this relatively expensive machine has not been incorporated into the plant flowsheet so as to fully exploit its power efficiency, and therefore realise the maximum economic benefit. This paper describes the results of a pilot scale test program designed to evaluate the performance of the device with the aim of developing a circuit configuration that better exploits the inherent power efficiency of the machine. The results of the test program clearly show that power savings of about 50% over conventional technology are achievable when the machine is made to produce the final product grind size.

Jan 1, 1995

By J. A. Meech, C. A. Harris

Expert Systems are being used in the Mineral Industry with ever­increasing frequency. A major advantage of these systems over conventional computer programs is that the knowledge and intelligence of human experts can be captured directly onto a computer for transfer to novices or other lesser experts. These programs allow rapid construction of process models that are not well-understood in fundamental terms, but for which good operational reasoning exists. In addition, user-friendly access to "high-tech" knowledge can be provided to unsophisticated personnel who otherwise might be turned off by unintelligible jargon. As such, these systems can be important training tools for new operators. This paper describes the features of Expert Systems that relate to gold processing plants. Applications include grinding circuit control, supervisory control of reagent addition and pulp density, monitoring and control of CIP/CIL carbon inventories and the operation of carbon stripping and regeneration facilities. A consultative Expert System is described that provides advice on laboratory cyanidation testwork

Jan 1, 1992

By David A. Collins

Red Dome Gold Mine classifies ore types within the pit by gold and copper grades. Copper grades are further distinguished by total copper and cyanide soluble copper levels. At present, Cyanide Soluble Copper samples take six hours of agitating before they can be assayed. This agitation time produces results which are a proportion of the total cyanide amenable copper. This relates to our plant's performance. Frequently the total copper result is needed before we can begin the cyanide soluble copper analysis. This caused a protracted tum around time. Mennetech Pty. Ltd has produced a catalyst proven by David Martin Menne to accelerate the cyanidation of gold. David said that the information at hand indicated that Leach WELL TM also accelerates the leaching of cyanidable copper substantially. Test work was undertaken on-site at Red Dome Gold Mine to investigate the potential of Leach WELL TM to reduce the leaching period and therefore, the overall tum around time required for cyanide soluble copper determinations.

Jan 1, 1995

By Antonio Dominguez-Perez, Annette Dickmann, Roy Norcross, Andreas Rubo, Stephen Gos

With increasing cost pressure in the production costs of gold, there have been great efforts made to reduce the gold production costs as much as possible and a great deal of effort and lateral thinking is required to maintain a cost effective gold production facility. In a difficult economic environment, there is always the danger of saving in the wrong place. Just like it can be fatal to cut down on innovative research and development for long-term existence and sustainability in most industries, savings in safety and visionary planning of regulations expected in the future can become very costly on the long run, if preventative measures are not taken, observed or ignored. This paper deals with some current topics pertinent to the gold mining industry with regard to the interaction between potential risks, regulations and the costs that arise and can be saved in relation to these. Only an optimal combination of cost effective, safe and technically feasible regulations enable an operation to work economically.

Jan 1, 1999