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By W. Nahas, T. C. Watson, A. R. Maycock

The development of roasting technology for the oxidation of sulfides in refractory gold ores is discussed. Case studies covering operations dating from the mid-1930's to the present day are used to illustrate this development. The roasting of ores and concentrates is reviewed and various gas cleaning flowsheets are discussed with particular reference to environmental requirements. A sequence chart is provided to show the development path of a potential roasting project.

Jan 1, 1990

By H. Soto

As a follow-up to a laboratory study, a pilot scale column for the flotation of coarse particles was designed and then tested in two different applications. In the first test, the concentration of a coarse phosphate ore (normally beneficiated by skin flotation in spirals) was carried out in a flotation plant in Florida. In the second pilot test, the column was used as a scavenger cell in the coarse flotation section of a potash beneficiation plant in Saskatchewan, Canada. Particle size of the phosphate feed was of the order of 0.6-1.0 mm and the potash feed 1-3 mm. The column was 1 feet diameter and was fed at rates between 0.5 to 1.4 tph. The effect of operating variables such as air and water flow rates, bubble size, frother concentration, residence time, sparger, etc were evaluated. The most important factors in column performance were found to be bubble size, air flow rate and the thickness of the froth bed. Best results were obtained in the absence of a froth bed, with low air flow rates and with small bubbles. The paper presents comparative performance and discusses details of the column design. Phosphate recoveries in the column were better than 90% whereas the conventional skin flotation circuit normally yields about 60% recovery for a comparable concentrate grade. Potash recovery from the tailings of the conventional flotation circuit was as high as 42% recovery. Particle size distribution of the potash concentrate was coarse enough to meet requirements for potash fertilizer.

Jan 1, 1993

By Edgardo I. Cifuentes, Andrew L. Mular, Andrew Burkert

Experimental designs are data acquisition plans which, if followed exactly, will quickly provide process engineers with information to assess statistically the individual and joint influence of factors on responses to permit of rapid decision making. Methodology employed to construct data acquisition plans is described in some detail. In production environments, factorial designs are appropriate for most purposes. Use of two level factorials to make decisions is described for a grinding circuit.

Jan 1, 1991

By Jorgen Elbrond

The mineral industry shares a particularity- heterogeneity-with the other primary industries exploiting nature such as agriculture, fisheries, and forestry, which may not be found in the secondary industries, In the mineral industry heterogeneity is evident both in the raw material, the ore in situ, and in the working conditions. Mining engineering, which encompasses the tools for designing mine production systems, is mostly an assembly of the other branches of engineering and applied science. The assemblage's goal is to arrive at an optimal production system. As such, mining engineering is similar to systems engineering. The technique for the development of systems-mine production systems or mining operations -is operations research with its succession of activities: observations, modeling, experimentation, and verification. Comparisons among alternative systems are highly desirable during the development phase of a mining operation as well as during later phases where modifications, ameliorations, and expansions are carried out on the existing system. The role of the independent consultant in systems design and development lies in the collection and breadth of experiences from modeling and model verification in other operations, which he can add to a new system's development and thus in- crease its credibility with management.

Jan 1, 1979

By Donald Lau, Adrian Crawford

In the field of grouting, practitioners fre¬quently advocate procedures that are often unique and contradictory. As a result there has been considerable debate as to what constitutes optimum grouting practice. A knowledge of both the rheological properties and the flow characteristics of grouts is essential to the development of a rational understanding of the grouting process. Flow models and viscosity experiments have been conducted using cement grouts comprising High Early Strength Portland and Microfine cements. The addition of superplasticizers was found to enhance the flowability of the grouts as well as to reduce the effective groutability ratio. Steady state flow equations and design charts for predicting the radial penetration of cement grouts have been developed.

Jan 1, 1986

By J. Mark Richardson

Modern mining operations are increasingly affected by complex economic factors. Broad and rapid fluctuations in metal prices, rising operating costs, socio-political trends and the inherent technical difficulties encountered in most operations, all can combine to quickly change once-profitable ventures into money-losing propositions. Accurate knowledge of metal inventories during all phases of an operation has become essential to wise management decision-making. This paper reviews key elements of metallurgical accounting: sampling theory, measurement technology and computerized data adjustment. Application of current technology to the reconciliation of a hypothetical operation is discussed.

Jan 1, 1991

By E. Topuz, M. J. McPherson, I. M. Konduri

This paper describes experiments conducted to evaluate the effectiveness of jet fans for ventilating blind headings in under- ground mines. A laboratory model of a mine heading was built by using dynamic similarity criteria, and water as the fluid medium. In order to verify laboratory test results, field experiments were designed and carried out in a full scale mine model and in a coal mine in West Virginia. Using CO, as the tracer gas and in combination with a computerized gas monitoring system, tests were conducted to evaluate jet fan performance. The results highlight the flexibility and versatility of jet fans for ventilating blind headings. Numerical modeling of a jet fan in a typical coal mine heading was carried out to evaluate the potential of computational fluid dynamics.

Jan 1, 1997

By D. B. Stephens

Assessing the occurrence of natural ground-water recharge at mine and mill waste disposal sites may be crucial to addressing regulatory agency concerns regarding the potential impact of waste seepage on ground-water resources. Recharge has been shown to occur even in semi-arid areas where annual lake evaporation exceeds precipitation. Permanent storage of waste seepage in the unsaturated zone is not to be expected if recharge occurs under natural conditions. Establishing the direction and rate of fluid movement in the vadose zone by field measurements is an important element that should be included in the site selection process.

Jan 1, 1987

By L. A. Puchkov

The creation of automatic methane concentration control systems presupposes the use, as a control factor, of the air rates in workings and in mine as a whole. These systems present a complicated set of computers and software, including as major components the following - systems for detecting methane concentration and air rate; - telemechanics systems; - programs and means of data processing; - programs and means of air rate control in workings and main fan capacity control. The paper analyses the experience of development and exploitation of automatic methane control system in gassy mines of the USSR Donetz coal basin. Much attention is given to the study of technological factors influence upon aerogasdynamic process using automatic methane control system.

Jan 1, 1989

By V. K. Gupta

A detailed experimental study of the variations in grinding rate with particle size, particle load, ball diameter, ball load, mill diameter, and mill speed was carried out for a soft cement clinker and a hard cement clinker. The effects of the ball diameter, ball load, and particle load were observed to be material (hardness) independent, and those of the particle size, mill diameter, and mill speed to be material dependent. A sharp change in grinding behavior was observed for both the clinkers at about 150 µm size. Below this critical size: (1) the hardness difference between the two clinkers became insignificant, (2) variation in the grinding rate with particle size became markedly more pronounced, and (3) mill speed had little or no effect on grinding rate. The importance of these results in the context of process optimization and control is discussed.

Jan 1, 1988

By Vas Choudhry, Randhir Sehgal

Conventional clean coal technologies which consist of coarse coal cleaning by gravity methods and treatment of natural fines by flotation can only remove a portion of the pyritic sulfur and ash in the coal. Higher (+90%) pyritic sulfur rejection is attainable when coals are ground to ultrafine sizes to enhance liberation of the mineral matter and then cleaned. However, cleaning of coal at very fine sizes poses a number of unsolved problems, the chief one being the loss of cleaning efficiency. This, of course, means that liberation of pyrites does not always equal its rejection. In addition, the dewatering of fine- cleaned coal, and its handling, transportation, and acceptability to the utility industry a1 so pose considerable technical and economic problems, especially when compared to the FGD alternative. This paper addresses some of the critical issues involved in the cleaning of ultrafine coal s.

Jan 1, 1989

By G. M. Bernard

Cerro Colorado lies on the eastern edge of the Atacama Desert in the foothills of the Andean Cordillera of northern Chile. Compañía Minera Cerro Colorado SA (CMCC) operates Cerro Colorado. CMCC, headquartered in Santiago, Chile, is wholly owned by Rio Algom Ltd., of Toronto, Ontario. Cerro Colorado is located 120 km (75 miles)east of the port city of Iquique. Access is by 30 km (19 miles) of paved highway and 70 km (43 miles) of upgraded road. The mine site is located at an altitude of 2600 m (8531 ft) on a gentle west-sloping plateau adjacent to a deep canyon (Quebrada de Parca) to the north. Temperatures are moderate, ranging from 5° to 30° C (41° to 86° F) with an average annual rainfall of 20 mm (0.8 in.). The plateau is generally covered with 20 to 30 m (65 to 100 ft) of Quatemary sand and gravel overlaying bedrock. In the immediate vicinity of the Cerro Colorado deposit, a semicircular embayment has been eroded into a steep canyon wall that cuts through the surface gravels to expose a considerable section of the underlying bedrock.

Jan 1, 1995

By Thomas E. Shufflebarger

Glass sand is a virtually pure, fine- to medium-grained, quartz sand. It is produced in 25 states from a variety of chemically different source rocks. Deriving their raw material largely from either friable sandstones or loosely consolidated sands, 59 operations produced 14.9 million tons of melting sand in 1976. About one-third of this tonnage was obtained from the Oriskany and St. Peter Sandstones. Glass-sand prospects are discussed in this paper with regard to chemistry, environment, transportation, and costs. Demand for a quality product will range from 36 million to 46 million short tons in 1995.

Jan 1, 1978

By Kent G. Homewood

The well-being of any company is directly related to the well-being of its employees and to the effectiveness with which the personnel resource is managed. In an era when personnel management has steadily become more complex, there is an increased awareness of employee information systems at all levels of management due to: (1) regulations enacted by federal, state, and local government agencies; (2) technological advances within the mining industry which have resulted in the requirement for highly skilled personnel; (3) increasing concern for the confidentiality of employee information; and (4) management's need for information for planning purposes to control costs and for early recognition of trends and potential problems. In the past it was sufficient to maintain records manually. Today computers are necessary to provide information on short notice and effectively manipulate large volumes of' data. This discussion will describe the following aspects of employee information systems: (1) collection and maintenance of information, and (2) applications which include employee health, salary administration, management re- sources, and labor negotiations.

Jan 1, 1979

By Michael P. Foose

In 1994, more than 41 of the approximately 160 coal-fired, electrical- power plants within the six-state Ohio River Valley region used flue-gas desulfurization (FGD) units to desulfurize their emissions, an approximately 100% increase over the number of plants using FGD units in 1989. This increase represents a trend that may continue with greater efforts to meet Federal Clean Air Act standards. Abundant limestone resources exist in the Ohio River Valley and are accessed by approximately 975 quarries. However, only 35 of these are believed to have supplied limestone for FGD electrical generating facilities. The locations of these limestone suppliers do not show a simple spatial correlation with FGD facilities, and the closest quarries are not being used in most cases. Thus, reduction in transportation costs may be possible in some cases. Most waste generated by FGD electrical-generating plants is not recycled. However, many FGD sites are relatively close to gypsum wallboard producers that may be able to process some of their waste.

Jan 1, 1999

By C. J. Pritchard

Productivity improvements reduced the number of continuous miner sections from seven to three while maintaining full productive capacity. So a decision was made to test an advancing tailgate ventilation system on the shortwall mining section. Having the shortwall mine its own return air system has freed the third mining section for more productive, less costly mining. The advancing tailgate has provided effective ventilation across the face and gob with acceptable pressure losses. The low-productivity, tailgate-development, continuous-miner section has been transformed into to a high-productivity, development-retreat section that is also available for long-term mine development duties, increasing mine planning flexibility.

Jan 1, 1991

By J. Partyka, J. S. Stachulak

Dust produced during blasting in a copper/nickel based mine was studied and characterized. A stope utilizing the crater blasting technique, or the vertical retreat mining (VRM method), was examined. Two dust monitors were used to measure an airborne dust produced during blasting operations. The data collected in situ was primarily used to formulate the boundary value problem for a generalized equation that describes the transportation process of airborne dust from all places where dust is produced by the VRM mining method. The field data was also used to define the analytical forms for the initial and boundary conditions, to provide a simple and reliable equation for flow of dust in a stope vicinity, and to identify the non-measurable constants. The effects of the amount of blasting material and of the ventilation system in use on dust concentration are also discussed.

Jan 1, 1995

By G. Johnston, P. K. Chatterjee, S. Holguin

Underground mine planning is largely manual and can demand considerable resources to generate a working plan and to perform limited tests of sensitivity to variations in geological and mining conditions. It is possible to use computer aided mine planning to automate many of the manual procedures to allow the planner to evaluate a number of layouts, extraction strategies, and schedules. his paper examines the simulation and scheduling of an under- ground coal mine operation through the-use of on- screen graphics. The simulation will provide a basis for predicting productivity and other relevant information over a specified number of shifts. The software developed is extremely user friendly and reduces the tedium of repetitive manual calculations inherent to mine planning and drafting to a minimum, thus offering considerable savings in an area that is widely recognized as extremely labor intensive.

Jan 1, 1988

By S. Pignolet-Brandom, E. Fregeau-Wu, I. Iwasaki

To recycle steelmaking slags for their iron, manganese and lime contents, removal of the phosphorus-bearing dicalcium silicate and calcium phosphate is essential. Slow-cooling of slags was necessary to promote sufficient grain growth to achieve liberation. In situ grain size distribution determination showed that a high soaking temperature, a long soaking time, a very slow cooling rate and the addition of fluorspar promoted grain growth. High gradient magnetic separation on slow-cooled slags removed much of the dicalcium silicate. Liberation modeling was used to discuss the breakage and beneficiation characteristics of the slow-cooled slags.

Jan 1, 1993

By K. Ohga, V. J. Hucka

The presence of methane gas in mines creates hazards of explosions, fire and suffocation. Under certain conditions the occurrence of methane also poses a danger of gas and coal outbursts. Consequently, prevention of gas and coal outbursts in coal mines requires a sound knowledge of methane gas occurrence in mine workings. However, the direct method of determining methane content of coals developed by the U.S. Bureau of Mines is time and labor consuming for measurement, a new transportable methane tester was developed for Japanese coal mines. The instrument automatically measures emission gas from coal samples in the underground and also records and stores the data. Back on the surface, the tester can be connected via a RS 232 port to a PC computer for methane content estimation. Details of this technique are described here. Results on methane content determined in Japanese and U.S. western coal seams are discussed, as well.

Jan 1, 1991