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By J. Brent Hiskey, Srini Raghavan

The physical chemistry of dissolution of silicate and complex oxide ores in aqueous lixiviants has been reviewed. Particular attention has been paid to the analysis of dissolution mechanisms and kinetic models and to the elucidation of the role of the porous nature of the materials on dissolution behavior. Importance of the physico-chemical characteristics of the leach residues on leaching efficiency has been discussed.

Jan 1, 1989

By R. R. Tatiya

The algorithms to model three stoping methods - sublevel, down- the-hole (DTH) and cut and fill stoping have been developed. These algorithms are capable of designing and performing economic analysis for one or more number of stopes in a continuous orebody. The design and economic analysis of each individual stope are first obtained. This is followed by the composite stope design layout and overall economics of the stopes under study. This paper describes only the stope design aspects of these models. The programs have been written using Fortran 77 with Tektronix graphical aids available at Imperial College Computer Centre (ICCC) London and are based on the basic data obtained from Khetri Copper Complex (KCC) and Rajpura Dariba (a zinc mine) in India. Minor modifications, however, may be necessary in some routines when used on other systems and for other mines.

Jan 1, 1989

By Frank L. Bazzanella

Se presenta una breve introducción de la concentración gravimétrica, incluyendo alguna discusión sobre los minerales mas comunes recuperados normalmente. Se mencionan las consideraciones importantes para el diseño básico de una planta de concentración y se presentan cuatro esquemas de flujo sobre las operaciones más corrientes. Las plantas estudiadas en detalle incluyen: "Climax Molybdenum Co. By-Product Plant" y "Canada Tungsten Ltd. Plant". Las plantas brevernente reseñadas incluyen: "Palabora Mining Co. Uranium Recovery Facility" y "Bridge Hill Ridge Heavy Mineral Recovery Plant of Mineral Deposits Ltd."

Jan 1, 1982

By F. T. Paleari, J. A. Finch

Radial gas holdup profiles were measured in a 50-cm-diam, 400-cm-high flotation column using a multi-cell-conductivity probe. Three bubble-generation systems, including a system with up to eight vertical filter-cloth spargers, a system with three horizontal filter-cloth spargers and a system with three (horizontal) Cominco-type spargers, were examined. The variables investigated were the number of spargers, the symmetry of their arrangement and the height above the spargers. Batch water containing up to 20 ppm frother was used. Generally, the profiles tended to be uniform (flat) with some profiles exhibiting a slight "wavy" pattern. The vertical sparger arrangement proved to be the most difficult in which to achieve a profile symmetry. The horizontal spargers gave uniform profiles at right angles to their length but gave decreasing gas holdup along their length. The Cominco-type spargers gave slightly less scatter in the data. Switching off selected spargers to simulate a malfunction did not produce strong asymmetry in the profiles.

Jan 1, 1995

By Zhang Youdi

According to general guidelines, deposits suitable for surface mining can be divided into two basic categories: horizontal or flat-bedded deposits and inclined or dip-buried deposits. A series of mathematical models for surface mine long-term planning (SMLTP) has been developed and can be used for any kind of deposit. The basic theory and methodology of the models are oriented- graph simulation which combines graph and network theory with a systems simulation technique to form a new approach. From the viewpoint of surface mining and long-term plan modeling, the main differences between the two categories of deposits are analyzed, an important algorithm is put forward, and the structure of the models and some results of applications are introduced. Dynamic and comprehensive optimizations have been completed by the SMLTP model series. Combining different OR branches, the new approach has been proved to be a powerful tool to solve the strategic problems of surface mine planning.

Jan 1, 1989

By R. Poulin, A. Lamontagne, N. Tassé

This paper presents the results of a laboratory investigation aiming to verify the concept of co-mingling of waste rock with layers of compacted tailings. Overall, co-mingling is expected to delay the onset and reduce the magnitude of acid mine drainage (AMD) production in waste rock. To denionstrate the efficiency of the method proposed, five different column tests have been set-up. Columns were fed with deionized water at the top and drainage waters were collected and analyzed. Bacteria counts were done on the tailings and waste rock after the column tests. Permeability in saturated conditions and capillary parameters were measured for the tailings. The results obtained show that the co-mingling method would be effective in mitigating AMD by maintaining nearly water-saturated conditions in compacted tailings, thus reducing oxygen supply in waste rock by preventing thermal air convection and minimizing oxygen advection and diffusion.

Jan 1, 2000

By J. A. Herbst, K. N. Han, P. B. Queneau, S. W. Asihene

As hydrometallurgy matures as a technology, more of its existing process knowledge will continue to be summarized in the form of detailed mathematical models. This development is happening at a time when major improvements in computer hardware have reduced the cost of computing. The opportunity then exists, through the solution of these process models, to design, control, and optimize hydrometallurgical plants on the basis of the physics and chemistry of its processes and less on empiricism. In this paper, a review of the current capabilities of sensors and phenomenological models for selected hydrometallurgical processes is presented. Future trends, in terms of the control and optimization of hydrometallurgical plants, are then explored. The possibility of simultaneously optimizing plant design and associated process control system performance is discussed.

Jan 1, 1993

By Ernest Peters, Fiona M. Doyle

The leaching and bulk decomposition of sulfide minerals is of enormous commercial importance in several areas of the minerals industry. These include: direct leaching of ores or concentrates for the recovery of the contained metal values; decomposition of sulfides to recover associated values such as encapsulated gold; and the potentially hazardous oxidation of sulfides in waste disposal facilities. A significant challenge to successful future developments in these areas is to improve our fundamental understanding of the mechanisms of the chemical, electrochemical, and bacterially-mediated interactions between sulfides and aqueous solutions. The paper summarizes current understanding of these mechanisms, and discusses promising new directions for research.

Jan 1, 1989

By J. Willison

Over the past decade, the coal mining industry has faced the difficult task of remaining profitable in the midst of declining market prices. Historically, the industry has been quite capable of meeting this challenge by various means. As total costs to mine and market coal continue to increase, new methods of tackling the problem must be implemented. Studies have shown that although many options exist to influence both inby and outby costs, the greatest potential remains in addressing costs at the coal face. Mining operations can positively effect a change in their profitability by either reducing costs, or by increasing production to in turn lower their net cost per man-hour. Original equipment manufacturers can play a key role in both options through the introduction of new technology that permits higher extraction rates, as well as other advantages leading to lower cost coal. A leading advancement over the past 30 – 40 year period has been the advent of progressively higher voltages to operate the mining equipment. This advance enables higher power transmission for a given cable size, operation at lower amperages resulting in less voltage fluctuation, and reduced heat on the cable and electrical components.

Jan 1, 2003

By D. E. Ranta, Ora H. Rostad

Ore reserve estimation, from the earliest "quick and dirty" estimates made at the first consideration of a possible project down to periodic revisions of detailed estimates made during the life of a mine, should take into account many geologic and allied factors in order to obtain results that will provide proper guidance for necessary economic decisions. Factors include: sample collection and analysis, character of the vein and associated wall- rock, mineralogy, pre and post mine oxidation effects, core loss, sample correlation, internal vein structure, wallrock controls, geologic factors affecting dilution in mining and interrelated mining and milling problems.

Jan 1, 1992

By M. G. Bakker, D. D. Murphy, D. R. Spears

The US Bureau of Mines studied the mechanism of shear flocculation of silica with stearic acid. At pH 6 and 12, shear flocculation of silica was not observed with the addition of up to 4.5 x 10-4 M (5 lb/st) stearic acid. However, in the presence of 0.1 M NaCl at pH 6, shear-flocculation was observed at stearic acid concentrations = 10-4 M (22.5 lb/st). Adsorption of stearic acid on silica was studied using stearic acids spin-labeled with a doxyl group. The presence of the spin-labeling group did not greatly affect the shear flocculation properties of stearic acid. Adsorption of labeled stearic acid on silica was measured as a function of surfactant concentration with electron paramagnetic resonance (EPR) spectroscopy and gas chromatography (GC). The GC results indicated that the stearic acid was predominately adsorbed on the surface at concentrations above 10-4 M. From the EPR spectra, the formation of aggregates of stearic acid was apparent at concentrations of approximately 10-5 M (22.5 lb/st). The results are discussed in terms of a possible mechanism for shear flocculation.

Jan 1, 1995

By William H. Pomroy, Annie M. Carigiet

This U.S. Bureau of Mines report is an analysis of underground coal mine fire incidents occurring in the United States during the 15 years from 1978 through 1992. The fire data used in this analysis were obtained from Federal Mine Safety and Health Administration (MSHA) mine fire investigation reports. Fires were analyzed by year, state, coal bed thickness, mining method, evacuation measures taken, ignition source, burning substance, location, equipment involved, detection method, time of day, number of injuries and fatalities, and method of extinguishment. In all, 164 fires are reported, or an average of 10.8fires per year. The most common ignition source was electricity, the most common burning substance was coal, the most frequent fire location was the belt entry, belt conveyors were the most common equipment involved in fires, and water was the most common extinguishing agent.

Jan 1, 1995

By Charles D. Litton, Margaret R. Egan

In order to reduce the number of nuisance fire alarms in underground mines that use diesel-powered equipment, the U.S. Bureau of Mines has developed a diesel-discriminating fire detector (DDD). It was designed to discriminate between smoke produced by a fire and the smoke-laden exhaust of a diesel engine. Welding and cutting with arc or flame can also produce combustion products capable of triggering nuisance alarms. In this report, the response of the DDD to the emissions from diesel exhaust, arc welding, and flame cutting are compared to the response of conventional smoke and carbon monoxide (CO) detectors. The data show that when the DDD is set at an alarm threshold of 0.05 v, it will reliably detect a developing conveyor belt fire while remaining insensitive to other sources of nuisance combustion products. The alarm times of the three types of detectors were also compared. The DDD alarmed first in response to a smoldering conveyor belt in two of four experiments.

Jan 1, 1992

Mine managers need useful data to support production and maintenance decisions; for example, to evaluate the performance of replacement components. Today, managers rely solely on past experience, supervisors, opinions, and time studies. Our paper describes the concepts and algorithms we are developing for an automatic, intelligent decision support system (IDSS) that will aid managers by reducing and analyzing large amounts of, monitoring system sensor data and report only key production and maintenance information.. IDSS contains a pattern recognition, subsystem (IDSS/PRS) prototype to report graphical trends in traditional time study elements. We are designing. and prototyping a knowledge representation subsystem, using Knowledge Craft Tools, that will learn and adapt to the dynamic mine environment and reason about the recognized patterns using representations of manager's knowledge, equipment, capabilities, and mine layout and operating procedures. This subsystem will reduce, large quantities of time study type information to key issues that interest different managers.

Jan 1, 1989

By R. Y. Wan, J. D. Miller, P. L. Sibrell

Three different refractory carbonaceous gold ores from the Carlin operation in northeastern Nevada were investigated to characterize the effect of passivation treatments on the nature of the carbonaceous material. The carbonaceous material was chemically isolated from the ores and passivated residues, and examined by FTIR spectroscopy, elemental analysis, and gold adsorption capacity. The main component of the carbonaceous material in these ores was found to be a naturally occurring activated carbon-type compound. Hydro-carbons were detected on rare occasions, but no evidence was seen for humic acids. Ore samples were passivated by autoclaving, or by treatment with sodium hypochlorite or gaseous chlorine. In some of the passivation tests, a new peak was observed in the IR spectra of the isolated carbonaceous material, that was due to carbonyl functionalities. However, all of the passivation treatments tested decreased preg robbing significantly. This suggested that the appearance of the carbonyl peak was due to the severity of the conditions during passivation, rather than the method used.

Jan 1, 1990

By Michael J. Nicol

Hydrometallurgical processes involve the recovery of metals from ores, concentrates, calcines, mattes and scrap materials by a series of operations involving leaching or dissolution, separation, purification and reduction of metals in aqueous solutions. The underlying theoretical basis of many of these operations is electrochemical in nature and it is the purpose of this review to identify and illustrate, by way of examples from the author's experience and that of others, the central role of interfacial electrochemistry in the understanding, design and control of these operations.

Jan 1, 1993

By N. Colvin, J. W. Gulyas

HISTORY The Surigao Nickel Refinery of Marinduque Mining and Industrial Corporation is located on Nonoc Island off the northwestern coast of Mindanao in the Philippines. Nonoc Island is part of the Surigao Mineral Reservation which had been identified as early as 1912. Initial interest in these deposits was due to their iron content, and their value as a nickel deposit was not seriously entertained until the late 1950's. The Philippine government undertook extensive test pitting and sampling programmes at that time and in the early sixties Marinduque became involved in helping to establish firmer ore reserves. Evaluations of the test pitting programme indicated reserves of 75,000,000 tonnes of ore averaging 1.22% Ni, 0.1% Co and 38.5% Fe. The Philippine government called for bids on the reservation in 1962 and Marinduque and Sherritt Gordon carried out some feasibility studies for the recovery of nickel from the deposit. However, it was not until 1968 that Marinduque was granted proper authority to exploit the Surigao deposits. Marinduque and Sherritt then entered into an agreement which allowed Marinduque to utilize a process developed by Sherritt for treating lateritic ores. During 1968, a 25 st/d pilot plant was erected in Fort Saskatchewan, Alberta for the purpose of modelling all process steps. A 10,000 tonne ore sample was sent from Nonoc as feed stock for the pilot plant.

Jan 1, 1979

By H. Peter Knudsen

Karst hosted lignite deposits are characterized by variable thickness of lignite that was deposited in depressions in the karst topography and by the variable extent and shape of the lignite pods. Since the lignite to be mined will feed a mine mouth generating plant, an extremely important criteria in the mine plan is to assure continuous feed to the plant. The variability in both the extent of the pods and the thickness of the lignite within the pods must be taken into account in any mine design in order to quantify the risk that an area being developed will have enough lignite to feed the plant for the specified period. Indicator kriging was used to create a model of lignite thickness of the deposit. Pod boundaries were determined from the indicator kriging model by two methods. First, contour maps showing the probability that the lignite is above a minimum mining thickness were prepared. Using these maps the mine planning engineer can determine either conservative or optimistic boundaries. The second method recognized that the most costly error that can be made in the mine plan is to run out of lignite. Thus, a loss function was determined from the costs of overestimation and underestimation. Using this function, the probability that minimizes the risks of overestimation versus underestimation was calculated.

Jan 1, 1989

By M. H. Al-Dabbagh

In this paper, the authors outline the deficiencies of PERT/CPM as a method for scheduling complex projects such as mine development. In particular, PERT/CPM networks cannot accommodate logical nodes (events) or stochastic branches (activities). The Graphical Evaluation and Review Technique (GERT), developed by Pritsker and. co-workers, is introduced as an alternative to PERT/CPM that overcomes many of the deficiencies of the latter and enables a more realistic analysis of complex projects that are subject to significant uncertainties. A brief overview of GERT network structures and network analysis is given and a PC implementation of the method is described. The technique is illustrated by application to the development of an open-pit gold mine in Saudi Arabia.

Jan 1, 2002

By William N. Fitch, Valois R. Shea-Albin

In 1976, the Resources Conservation and Recovery Act (RCRA) aroused concern in the mining community about the regulation of mine waste streams under RCRA. In response, the Bureau of Mines initiated research in the late 1970's that addressed mine and minerals processing waste. Research included investigating improved environmental technology for metal, coal, non-metal, and emerging industries such as oil shale, tar sands, peat, and lignite. Environmental issues escalated in the 1980's. Proposed regulations addressing control technology for mining and mineral processing wastes prompted the Bureau of Mines to become involved in 1985 in an advisory capacity to the regulatory agency, the Environmental Protection Agency. In Fiscal Year 1988, the Bureau of Mines initiated a research program designed to provide the minerals industries with cost-effective solutions for ameliorating environmental effects of mining. Bureau research has led to advances in the areas of acid mine drainage control and mitigation, subsidence prediction and control, and control and treatment of solid wastes resulting from mining and mineral beneficiation. The Bureau also conducts research seeking new methods to remediate abandoned mine lands. A discussion of the mine waste issues is presented, followed by a summary of past and present research conducted by the Bureau of Mines.

Jan 1, 1991