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By D. J. McKee, D. M. Wiseman

The usefulness of simulation as a technique for metallurgical process design and optimization studies has been greatly extended over the last few years by the development of a number of general purpose simulation packages. The packages, or simulators, all have the common objective of presenting the mathematical models and simulation methods in a form which is readily usable by plant engineers and metallurgists. To date, most simulators have been concerned with steady state simulation, but packages capable of dynamic simulation are now becoming available. The paper outlines the essential features of versatile steady state and dynamic simulators. Typical applications are presented by considering examples of design and optimization studies. Limitation on the use of simulators are also presented.

Jan 1, 1991

By Harry R. Dahlberg

Heap leaching is discussed as a unit process. Five factors are identified as the principal elements that can be measured and/or controlled. These are: 1. Material Size 2. Volume of solution 3. Tonnage of heap 4. Time 5. Solution concentretion. The Rate of Extraction Curves obtained from an actual heap or column tests describes the economic viability of the unit process. By analysis of these curves and the five factors end their inter-relationship it is possible to determine how the extraction rate can be increased. The practice of leach and rest used by many operators is analyzed and shown on a hypothetical rate of extraction curve. The influence of the driving force of the hydrogen ion and ferric Lon as Lixivants and its effect on the rate of extraction curve is discussed.

Jan 1, 1979

By A. L. Mular

Steady-state material balances calculated from data measured at various locations around process units are useful for many purposes, such as metallurgical accounting, on-line control, and the development of mathematical models. Often it is possible to calculate material balances by several independent procedures when excess measurement information, i.e., redundant data, is available. Clearly, if the data were collected without measurement errors, a theoretical condition never found in practice, all material balances calculated from redundant data would be in agreement. The real situation is that error exists in practical measurements, so that the results of material balances determined from available optional procedures differ. Consequently, best fit computational procedures to improve the material balances by taking measurement errors into account have been formulated. Such procedures can be used also to judge whether measurements are grossly in error due to either faulty observations or defective data sensing devices. A variety of mathematical techniques are available which serve to adjust raw data. The adjusted data permit mass balancing that does not depend on the computational method. To illustrate the need for an adjustment procedure, Table 1 shows a raw data set acquired around the Brenda Mines Ltd. No. 4 grinding circuit shown schematically in Fig. 1. At least seven optional ways to calculate a circulating load ratio may be employed. These are shown in Table 2 where, depending upon the calculation [ ]

Jan 1, 1979

By Frank Littlewood

Research over a period of ten years resulted in the development of an efficient automatic ore feed regulator for mill grinding circuits. The facilities that a large mining company gave the inventor made it possible to develop the control apparatus under actual mill operating conditions. The Littlewood Regulator automatically determines the optimum power input at which a mill should operate, and controls the rate of ore feed to maintain this optimum power for any predetermined operating conditions. It is to be noted that the optimum power varies with many factors such as ball, rod, and mill liner wear, therefore the regulator is designed to automaticall keep itself properly calibrated. To efficiently control the rate of ore feed of a mill grinding circuit the regulator analyzes and interprets all power changes of the mill motor. The critical electrical measurements for this type of control are made possible by a patented device that has the ability to detect and integrate minute changes in power. In ball mill operation the small but significant changes in power serve to select the rate of ore feed in accordance with the rate at which ore accumulation takes place within the mill, and in rod mill operation they serve to select the rate of ore feed in accordance with the degree of rod spread.

Jan 1, 1970

By John G. Watson, Judith C. Chow, Richard T. Egami, Daniel L. Freeman

A methodology for apportioning ambient PM-10 (particulate matter) concentrations to sources is described and applied to PM-10 concentrations in the vicinity of a large gold mining operation. With this methodology, samples representative of particulate sources such as desert overburden, diesel equipment, milling operations, road surfaces, and others are collected and analyzed to derive chemical source profiles. Ambient 6-hour PM-10 samples collected downwind from the mine are analyzed and used with the Chemical Mass Balance model to apportion ambient PM-10 among the various sources. In an example application, primary contributing source types are found to be desert overburden and diesel equipment. Relative contributions vary according to time of day, with diesel equipment frequently being the dominant contributor during nighttime periods.

Jan 1, 1991

By Janusz Szywacz, Bozena Bojko, Stanislaw Wasilewski

Two groups of computer programs are described in the paper. First one is the OWEN system containing software modules designed for air flow distribution analysis and prediction within the whole ventilation network of a mine. The second group is a set of programs commonly used in a routine design work connected with chosing the optimal ventilation schemes and equipment for individual areas of a mine (headings. longwall districts etc). All the programs are designed for running on the IBM PC/XT, IBM PC/AT and compatible computer systems.

Jan 1, 1989

By Koehler Stout, Leroy Friel

INTRODUCTION Hydraulic sand fills have been extensively used in the United States in deep metal mines since 1940, and hydraulic fills have been placed in coal mines in Europe for many years. Numerous surface hydraulic fills exist in Appalachia for the disposal of coal mine waste and throughout the United States for the disposal of other mining, manufacturing, city, and paper company wastes. Hydraulic fills, as they are now deposited in stopes in mines, are often deposited at near minimum density and hence provide very little support to stope walls and pillars. If the support strength of fills could be increased, perhaps ground conditions in deep mines could be improved making them safer and more efficient. Surface fills deposited at higher densities could be covered with top soil upon which grass could be planted. The purpose of this paper is to describe procedures where the support strength of hydraulic fills can be considerably increased, and the focus of the paper is on applications to deep mines. In deep mines the objective of increased fill strength is to reduce heavy ground problems, improve destressing techniques, reduce or eliminate rock burst incidences, provide better working conditions, provide wall support so that more or all ore pillars can be removed, and improve mine safety, efficiency, and reduce surface environmental problems. The authors have shown that it is possible to improve fill strength used in deep mines. This paper reports the slurry filling procedure, fill testing techniques, and some recommendations for application in deep mines. Some of the reasons for low strength hydraulic fills are:

Jan 1, 1979

By James M. Reichman

Waterjet assist of mechanical cutters has been demonstrated in a variety of laboratory studies as well as on field equipment. As this technique becomes more widely accepted, it will be necessary to develop methods of minimizing the horsepower and water requirements. In machines such as roadheaders, continuous miners, and longwall shearers, the use of waterjet assist can be optimized through the development of phasing valves. Phasing valves will allow only the cutters in contact with the rock to be assisted. Since only 30 - 40% of the cutters are in contact with the rock, the saving power is significant. Flow Industries has developed a phasing system for use on roadheading machines. This system allows the operator extensive control of the angle of assist as well as the quadrant being assisted. This system could be greatly simplified for production machines and adapted for use in continuous miners and longwall machines.

Jan 1, 1985

By W. B. Hayes

The origin of the titanium pigment and metal? industries began with the discovery of the element titanium in 1791 by an Anglican clergyman named William Gregor. The titanium was discovered in magnetic black sands found in the beaches near Cornwall. England. The name titanium was established by the German chemist who discovered the mineral rutile in Hungary. Rutile is the oxide of the element titanium, which he called titan alluding to the mythological titans, giants of ancient Greece. The commercialization of titanium minerals began probably in 1916 with the production of titanium tetrachloride which was to be used in tracer bullets, flares and smoke screens during World War 1. In the 1920's composite pigments based on TiO2 barium sulfate and calcium sulfate were produced, followed by the introduction of the sulfate process anatase TiO2 crystal in the 1930s. The U.S. Bureau of Mines in 1938 began investigating titanium metal technology and promoted the development of the Kroll process. which is the magnesium metal reduction of titanium tetrachloride to produce titanium metal sponge.

Jan 1, 1989

By K. E. Hjelmstad, W. H. Pomroy

In the event of fire underground, it is essential that all miners be warned as quickly as possible. With mine air rapidly depleted of oxygen and contaminated with smoke and toxic fire gases, any delay in the warning signal could have disastrous consequences. Unfortunately, present mine fire warning systems, such as stench, audible or visual alarms, telephones, and messengers, are often slow, unreliable, and limited in coverage. Recent research by the US Bureau of Mines has established the feasibility of ultralow frequency electromagnetic signaling for underground mine fire warning. Infield testing completed thus far at five mines, signals of from 630 Hz to 2000 Hz were transmitted through rock up to distances of 1645 m (5400 ft) to a pencil-sized ferrite-core receiving antenna and intrinsically safe receiver circuit. Theoretical analysis indicates a capability to transmit effectively for distances in excess of the maximum depths of most American mines, which is about 900 to 1000 m (2950 to 3280 ft) . The prototype system uses off-the-shelf components and state-of-the-art technology to ensure high reliability and low cost. This technology would enable simultaneous and instantaneous warning of all underground personnel, thereby in- creasing the likelihood of successfully evacuating a mine during a disaster. This report discusses the theoretical basis for through-the-rock ultralow frequency electromagnetic transmission, design of the prototype transmitter and receiver, and the results of in-mine tests of the prototype system.

Jan 1, 1991

By Donald M. Duncan

An acceptable source of concrete aggregate is available in Kansas City in a continuous, medium bedded, slightly dipping limestone unit. Removal is accomplished in shallow depth, 12 feet to 17 feet high, room and pillar mines. The accepted empirical design spaces 20 foot pillars 60 feet on center. A portion of the 20 foot unit is left in place for roof support. Rock and soil cover is variable to 100± feet maximum. Long-term stability of these mines is affected by numerous factors, including the above mine-rock profile, ground water conditions and mining practice. Crusher-run aggregate sells at the mine for $2.20 per ton, yielding a gross income of $2.00 to $2.80 per square foot of mine. Use of mine space for real estate development requires a new perspective in mine development. Mining practices to obtain long term stabile structures can become an over-riding factor as compared with minimum production costs and maximum extraction ratios. Poorly mined areas are unusuable for secondary purposes. Development cost for lease space in less desirable mines is substantially greater than those planned for a secondary use. Real estate development in mine space involves unique engineering problems. Properly engineered developments offer singular advantages. Warehouse lease space sells for $.50 to $1.00 per square foot per year; fully developed office areas may double these values.

Jan 1, 1968

By K. Papke

Nine western states contain significant barite deposits, but most deposits are in Nevada, which has been the principal western producer for more than three decades. Nevada produces about 85% of the total United States production, but about one-half of the barite consumed in the country is imported. Approximately 95% of the barite is used in drilling muds. Sharply decreased oil and gas drilling, starting in early 1982, severely depressed the domestic barite industry. Other problems for western barite include long distances to the areas of major drilling, high railroad-freight rates, and increased barite imports. Bedded deposits, formed by submarine exhalative processes, account for almost all western production, and reserves are large.

Jan 1, 1983

By S. W. Kan, M. G. Kakarkis, J. Zelanco

Grouting has been used in underground mining for more than 20 years. Chemical grouting is often used as a remedial measure when the implemented ground-control program is unable to completely prevent structural failures or when there is a need for preventing a structural member from unraveling. The utilization of polyurethane grout is restricted by its limited range of physical and mechanical properties. To overcome some of the drawbacks of polyurethane, research is being conducted on a newly developed polyester based grout. The polyester resin, identified by Sandvik as Strata Grip, provides a number of features, including variable gel times and a much-reduced chemical hazard. Equally important are the mechanical properties of the product. The strength and deformability of any chemical grout must be compatible with the intended purpose of grouting and the expected deformation of the rock that is to be grouted The assessment of the mechanical properties of polyester grout is the focus of this work. Field experiences and laboratory research defined the properties of an effective grouting material. Experimental results indicate that the polyester grout meets or exceeds the recommended properties for many injection applications. Furthermore, the results suggest that the ability to adjust mechanical properties via resin formulation has the potential to expand the applicability of chemical grouting in ground control.

Jan 1, 1999

By M. N. Brodie

The paper examines the requirements for electric power used in concentration and dewatering circuits, the effects of plant capacity and process type, the restraints imposed by the primary supply and applicable codes and outlines the procedure by which effective design is carried out.

Jan 1, 1986

By S. S. Nadgauda, A. J. Hathaway

Typically, as long as the coal quality is within the specified range, electric utilities have used delivered cost of fuel per million Btu as the primary criteria for qualified coals when making coal-procurement decisions. Such an approach may not fully address the total cost of using different quality coals at a given plant. A practical and easy-to-build model is described for estimating plant-specific utilization costs for coals of different qualities. Examples are included to illustrate the modeling results for plants operated by two utilities. While the model has certain limitations, it does represent an improved method for evaluating coal bids, and, consequently, reducing generation costs.

Jan 1, 1990

By Peter C. Lighthal, Harvey N. McLeod, Iain G. Bruce

This paper describes the practical aspects of handling cyanide leach tailings. Alternative systems for cyanide destruction are briefly discussed. The provision of adequate retention time to allow natural degradation of cyanide during summer months is the most economical method of cyanide destruction. Cyanide in ground- water can frequently be both persistent and mobile, so that tailings basins should be designed to limit seepage. Common methods for limiting seepage are presented. Other aspects addressed are water balance, winter operation and abandonment of cyanide tailings systems. A case example of the Cheni Gold Mines Lawyers Creek Project tailings handling system is presented.

Jan 1, 1987

By R. L. Hills

America's industry uses about 44% of the total energy consumed by the nation directly as fuel burned in industrial plants or indirectly as fuel burned by utilities to provide electric power. In addition, industry requires raw materials or feed stocks derived from fuel sources or having fuel value. This represents about 11% of total U. S. energy consumption, bringing industry's portion to about 55%. Adding that portion of energy consumption required by the transportation sector to move raw materials, intermediates, and finished products, the total energy impact of industry approaches 213 of total U. S. consumption. It is obvious that American industry has the largest share in the task of balancing energy demand and supply. What are we going to do? -- We must increase the supply of energy and increase the beneficial results obtained from each unit expended. Both avenues, unfortunately, are limited in extent and speed. Increases in supply cannot occur without drastic and permanent increases in cost. These increases in cost are un- desirable and inflationary but do provide incentive for the rational businessman to expend the effort and money required to improve the effectiveness of energy in industry.

Jan 1, 1975

By T. W. Oshnock

Pulverized coal (PC) and other injectants can be injected into the blowpipes of a blast furnace to decrease coke requirements. Throughout the history of blast-furnace development, there have been many attempts at injecting PC. In the 1960's a more serious effort was made to improve pulverized coal injection (PCI) technology. However, because of the additional capital requirements and the projected near-term inexpensive cost of other injectants, very few PC1 systems were installed. When the second oil crisis occurred around 1979, the shortage and high cost of fuel oil caused blast-furnace operators to operate without oil injection. It was soon discovered that blast- furnace operation without oil was not as smooth or efficient. Experiments with PC1 quickly showed that coal was a good replacement for oil which resulted in the rapid application of PC1 in both Europe and Japan. As a result, PC1 technology for blast-furnace operation has progressed rapidly during the 1980's. This paper will describe the worldwide status of PCI, characteristics of different PC1 systems, the effect of PC1 on blast-furnace process parameters, and the economic effects of using PCI. Results from the USS Blast-Furnace Thermochemical Projection Model comparing the effects of different coal properties and the effects of other tuyere injectants such as oil and natural gas will also be described.

Jan 1, 1988

By F. L. Jackson

When using perlite as an insulation, it is important to determine the requirements for different applications as this influences the processing of the perlite. In cryogenic application, perlite properties of low density and fine particle size are desirable, while loose fill insulation applications require similar properties and water repellency. However, in perlite insulating concrete applications, a coarser particle, of higher density, is required to provide improved compression strength. The essential properties of perlite including particle size, density, and surface treatment are discussed in relation to the various insulation applications. Also, typical mineral processing and manufacturing techniques are reviewed.

Jan 1, 1987

By W. D. Monaghan, A. J. Kwitowski, A. L. Brautigam

Teleoperation is a technology that can provide significant health and safety improvements in mining operations by locating machine operators hundreds of meters away from the face area. The US Bureau of Mines recently developed a teleoperation system for continuous mining and haulage equipment. This system features near real-time closed-loop control. A prototype system was developed and demonstrated. This system could be used in thin-seam applications down to 36 in (914 mm). Provided are details of the teleoperation system, the results of testing and the expected applications of this technology.

Jan 1, 1996