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By Peter G. Chamberlain

Many mining engineers considering in-place leaching for the first time are uncertain as to how to evaluate ore bodies for potential leachability. Evidence presented in this report emphasizes the critical role of permeability in such evaluations. Whether an engineer is considering leaching "tight" formations typified by the porphyry copper deposits of the southwest or the permeable uraniferous sandstones of Texas and Wyoming, permeability measurements are the keystone of any testing program. Permeability tests range from cheap and easy to highly expensive and sophisticated operations. Constant head, variable head, and pumping tests all have application in evaluating ore bodies for in-place leaching. Costs of these tests will not unduly deflate the pocket- books of most mining companies. The basic procedures for selecting and running these field tests-including preparing suitable wells--are reviewed for the benefit of newcomers to in-place leaching.

Jan 1, 1979

By William Crowe Kellogg

By now the term AFMAG has been fairly well introduced to the mining industry. Several papers have been presented and published concerning AFMAG (references 1 and 2). However, the term AFMAG remains rather new to the industry, and the exact place which AFMAG occupies in the minerals exploration field is still somewhat uncertain in the minds of many who may have use for this new and interesting method of electromagnetic exploration for conductive minerals. It is the purpose of this paper to again review the basic theory of the AFMAG system, to describe and - illustrate the equipment and data presentation as used in aerial surveying, and to provide some idea of the cost and nature of airborne AFMAG surveys. This paper is primarily of a general descriptive nature and presents AFMAG theory in a schematic rather than mathematical form; emphasis is placed on the equipment, the present method of data presentation and survey operations, since it is believed that such, information will now generally best serve to inform the mining industry of the characteristics of the AFMAG system.

Jan 1, 1960

By Charles C. L. Smith

A review and comparison is made of the circuitry utilized for dc crane control systems. Anti-parallel three phase full wave thyristor bridges for dc motor reversing and speed control are compared with a single three phase full wave thyristor bridge for speed control and either contactor or static switching for reversing control to obtain complete four quadrant operation for crane material handling. In recent years the Harnischfeger Corporation has developed a solid state adjustable voltage control system to control the speed and direction of dc motors for crane applications and handling materia1.1 Shunt wound dc motors are utilized and speed is controlled in the motor base speed operating region at constant torque by a thyristor, silicon controlled rectifier (SCR), adjust- able armature voltage supply. The three phase thyristor bridge is the power controlling element of the dc adjustable voltage control. ELECTROTORQUE is the Harnischfeger Corporation registered trade name for this type of drive system. By controlling the gating signals or firing pulses to the thyristor bridge SCR's the dc output voltage can be varied over a wide range. This range is limited only by the magnitude of the ac applied voltage. To obtain operation of the motor in both directions two thristor bridges are connected in an anti-parallel arrangement. A typical schematic for two anti-parallel connected three phase SCR bridges is shown in Figure 1.

Jan 1, 1973

By E. R. Bauer

A primary goal of Ground Control Research, Bureau of Mines, U.S. Department of the Interior, is to develop information that can be used by the mining industry to reduce accidents and fatalities due to failure of mine roof. A specific research objective is to determine methods to detect hazardous coal mine roof. This paper reviews the existing and experimental techniques, and describes a recent Bureau of Mines contract research project that resulted in a simple technique and prototype instrument for evaluating mine roof competence.

Jan 1, 1986

By William T. Ingram

Early in the 60's the author served as Chairman of the Engineering Foundation's Coordinating Committee on Air Pollution Research. One of our objectives was the development of a study on the measurement of stack emissions. Three publications of the Foundation resulted from these efforts to focus attention on the stack sampling problem.1,2,3 Two of these were annotated bibliographies covering 197 references. The third reported the results of a workshop meeting at which some 21 individuals from research institutes, industry and government discussed the possible and probable areas of research that would add to or increase the ease, precision and utility of sampling gaseous and particulate matter emitted from stacks. The American Society of Mechanical Engineers has had in its Power Test Codes a Standard Code for Determining the Dust Concentration in a Gas stream4 since 1941, The American Industrial Hygiene Association has published, in its Air Pollution Manual,5 a Section on Stack Sampling. Industry and regulatory agency requirements for stack sampling have utilized some modification of the alternatives in methodology. There has been ho single guide to stack sampling that met the needs of those who have the need to know.

Jan 1, 1970

By Burton H. Boyum

The paper generally reviews the iron ore occurrences and regional geology of Western Australia, but features in particular the mesa deposits of PJasic Materials - Cliffs International. Initial production is planned from a aeries of mesa deposits of Eocene-Oligocene age. The ore is oölitic to pisolitic goethite and hematite. Source of the iron in the mesa deposits is thought to be from the Precambrian iron-formations. The geology and occurrences of the mesa iron ore deposits are summarized and illustrated.

Jan 1, 1964

By A. S. Atkins

The interest in the use of micro- organisms in the leaching of sulphide minerals has been traditionally exploited as a scavenger process for the recovery of valuable metal by- products from waste ore dumps. Environmental concern on sulphur emission from conventional pyrometallurgical plants together with the cost of stack cleaning systems to comply with legislative control also indicate baccerial leaching to offer a low cost treatment for the processing of sulphide minerals. The paper describes the effect and limits of relatively coarse particles on the complete leaching of pyrite and its importance to the practical application in dump leaching operations of sulphide minerals. It has also been demonstrated that static leaching techniques have encouraging economic potential for process plant operations compared with agitated leaching systems.

Jan 1, 1984

By Robert W. Bruhn

Ground movements associated with high extraction underground coal mining, such as pillar retreat and longwall, are sometimes large enough to disrupt the ground water regime as well as damage buildings and other surface structures. A U.S. Department of Energy/Bureau of Mines- sponsored subsidence study currently underway at Kitt Energy Corporation's Kitt No. 1 Mine near Philippi (Barbour County), West Virginia has provided an opportunity to monitor the ground water response above a mine panel during both developmental and pillar retreat mining. The initial findings concerning ground water effects presented in this paper indicate that total extraction mining produced significant water level declines in deep-lying strata but had little effect on water bevels at shallower depths.

Jan 1, 1985

By J. S. Wozek

In metallurgical applications, coal fulfills dual roles as a chemical feed stock and as a fuel source. These applications range from cokemaking, ironrnaking (including pulverized coal injection), foundry, basic oxygen furnace / electric arc furnace coal additions, direct ironrnaking, Corex, and the futuristic direct steelmaking. In all steelmaking related processes, chemical reactions are simultaneously temperature and chemical dependent. Therefore, coals used in these processes must consistently comply with specific quality parameters in order to promote efficient operations. This paper limits discussion of Metallurgical Coal Quality to cokemaking and ironmaking applications. Its purpose is to present the customer's perspective on the control of critical coal and coke properties.

Jan 1, 1994

By V. J. Hucka

A 0.5 m (20 in) diameter high pressure natural gas pipeline crosses over a coal mine located in Central Utah. Ground movement induced by the mining operation could possibly place excessive strain on the pipeline causing it to rupture. The mining operation extracts coal from two seams using the room and pillar method. The seams are situated one on top of the other and both lie directly under the pipeline. At present, only the upper seam is being mined beneath the pipeline. However, in the future, the mining operation of the lower seam will also affect the pipeline. As would be expected, mining of both coal seams causes surface subsidence. This is especially true when the pillars are extracted during retreat.

Jan 1, 1983

By Charles B. Dugger

Sacrificial linings for grinding mills have been a necessary state of the art of mineral dressing since the inception of comminution. Long recognized as the final link in energy transmission from power line to ore, mill liners as a scientific endeavor have not expanded as rapidly as other branches of mineral dressing engineering. Several reasons for this technological lag are apparent. Typically in the past, labor intensive foundries were freely located geographically, at a time when transportation charges made up a significant portion of the casting cost. Alloying agents had not gained their current level of sophistication and were relatively inexpensive in the quantities required. Precise foundry controls were not economically justified, or totally understood. Coincidental to these elements, liner consumption per unit processed did not categorically contribute as a major cost item to the mill operator. Grinding equipment was small, and many times lining life exceeded that of the promoter. These unique conditions no longer exist. Ore dressing equipment has grown to meet modern mining demands. Larger processing facilities, utilizing fewer pieces of equipment, have replaced operations of the past. Emphasis today and tomorrow is on larger and larger equipment, with an eye on lower and lower unit processing costs.

Jan 1, 1979

By Luis Yacher

CONTAC Engineers is a Chilean based company which works on process control and automation, principally for the minning industry. Jointly with other local and international engineering firms, CONTAC has participated in most of the last expansion and modernization plans being carried out at the Chilean pinning industry. At presente, CONTAC is involved on a research and development plan for the design and implementation of new instrument and process control procedures for mineral process automation. One of these efforts is the design of an ore size analyzer for coarse ore being transported over a conveyor belt. A feasibility and prototype study was made at a SAG Mill Plant and currently a high resolution, high speed analyzer is being developed. It will became available on early 1986.

Jan 1, 1986

By Marc Lonoff

Byproducts are more important to the copper mining companies than to the copper market. Copper ores frequently contain gold, silver, molbydenum and cobalt. With the increase in the prices of these metals copper mining has become more profitable. If byproduct prices remain high, additional firms will be attracted to the copper industry; the increased supply of copper will reduce the long-run copper price. However, this is unlikely to happen because the markets for the copper byproducts, especially molybdenum and cobalt, are small. Increased recovery from copper and other sources will depress the prices of these byproducts before the copper price is significantly affected. Should byproduct prices remain high the copper market will both settle at a lower long-run price and be more unstable in the short run. Since changes in the copper price do not affect the entire earnings of a multi-metal mine, the copper price must fall further before such mines reduce output in the short run. Higher byproduct revenues will make copper supply less responsive to copper price; shifts in copper demand will result in greater copper price fluctuations in the short run than they did before.

Jan 1, 1980

By E. H. Boswell

The Mississippi embayment east of the Mississippi River is part of a vast geologic and hydrologic province. The abundance of water available is largely responsible for the agricultural history of the area and is perhaps the key factor in the rapidly accelerating trend toward industrialization. The multiple artesian aquifer systems that underlie the region, and the alluvial aquifer along the Mississippi River are virtually undeveloped sources of fresh water in that they are yielding only a fraction of the water available. The potential yield of the 12 aquifer systems is estimated to be about 25,000 mgd (million gallons per day), of which only about 600 mgd is presently being withdrawn. The amount of water in storage in these systems is about 1,600 trillion gallons. Ground water having a dissolved-solids content of less than 500 parts per million is generally available at depths of less than 1,000 feet, and water having a dissolved-solids content of less than 1,000 parts per million is available in some places to depths of more than 3,000 feet. Iron is the most common troublesome chemical constituent in the ground water. Water in varying amounts is also available from streams within the region. The amount of water which originates within the region and which leaves it as streamflow during a year averages about 50 million acre-feet (about 45,000 mgd). An additional 375 million acre-feet (about 340,000 mgd) leaves the region as streamflow during an average year, this amount having originated outside of the region. Some streams have considerable flow during periods of no precipitation, and the water during these periods generally has a low dissolved-solids content.

Jan 1, 1966

By R. M. Kakwani

The filtration and dewatering results of -32 mesh Pittsburgh seam coal are discussed with reference to the microscopic structure parameters, i.e., particle segregation in the cake and particle and pore size distributions at different layers. At low solid concentration of 0.33 kg coal/kg water, a non-uniform cake structure is observed in which the particle and pore sizes increase from the top to bottom layers in the filter cake. An increase in the solid concentration in slurry produces more uniform cake structure and higher filtration and dewatering rates. Air bubble entrapment in the coal filter cakes is also discussed.

Jan 1, 1984

By Denis Yeung

In an effort to find better ways to dispose of potentially toxic material, the effect of longitudinal and lateral dispersion on the dilution of toxic fluids was investigated numerically and experimentally. Homogeneous and non- homogeneous tests were conducted to model this effect for surface mine backfills. These tests used a high-density zone [package] to bury undesirable material. The studies, utilizing inert tracers, showed that an increase in density in a soil will decrease the maximum level of tracer in the discharge. Within the range of experiments performed and using only natural materials, a 65 percent reduction in peak concentration was obtained.

Jan 1, 1982

By P. K. Chatterjee

Computer aided design and inter active graphics have been well established in the electronics, automotive and mechanical engineering industries. The use of such aids in underground mine design and planning, however, has been noticeably absent. The large expense involved in the research and development of CAD and graphics systems and their highly specialized techniques have rendered investment in these areas difficult to justify. Optimum mine planning involves an interactive procedure of evaluation of several alternative plans. Generally the development of each mine plan of a given operation can take many man-months. This time constraint on planning precludes any comparative analysis and evaluation of alternatives, thereby introducing the possibility of unrealized gains. This paper outlines the development of a computer aided mine design program utilizing interactive graphics for the design, simulation and scheduling of underground coal mines. The program developed examines exploratory borehole information and produces a structured database of the sampled data. This database is utilized to generate seam sections and different mine layouts. A simulation of mine extraction and production levels and a schedule of proposed alternatives are then performed.

Jan 1, 1984

By Andrew J. Gaber

Beginning in 1961 the Coal Research Bureau of the West Virginia University School of Mines began a program of research to investigate the potential of the magnetic separation process to remove sulfur of the pyritic form from pulverized coal. Using a so-called isodynamic magnetic separator (1) it was demonstrated that significant quantities of pyritic sulfur could be removed from coal. Pulverized coal samples representing several different coal seams were individually screened into sizes in the 48 mesh by 200 mesh (297 to 74 microns) range, and untreated and steam-air treated samples of each were processed by the magnetic separator. The results of the investigations to magnetically remove pyrite from coal were published in two separate reports issued by the Coal Research Bureau (2,3), The isodynamic magnetic separator was designed about 30 years ago for use in geological and mineralogical laboratories (1,4,5) to isolate one or more minerals exhibiting only small differences in their magnetic propertiese Specifically, to accomplish this, the air gap of the unit was designed to provide a nearly constant magnetic gradient both laterally and longitudinally in the separating zone. It is reported that mineral concentrates of 99.5 percent purity can-be produced on closely-sized fractions after several cleanings through the unit. The isodynamic magnetic separator, therefore, was not expected to process coal containing sizes smaller than 200 mesh, or to demonstrate commercial capability to process pulverized coal. The primary purpose of the Coal Research Bureau in using the unit was that of determining if the magnetic process could remove pyrite from coal, and thereby encourage further research directed toward development of acceptable full-scale processing equipment.

Jan 1, 1969

By O. E. Brown

The measurement principle of the Coulter Counter for particle size analyses is described. The application of the Coulter Counter to cement particle content and size analysis and to the size distribution of clinker from standard grindability tests are described. Methods of calibration, sample preparation and data reduction are presented. The results of the analyses obtained are compared with characteristics associated with performance showing both concordance and non-concordance of test data., Future uses of the Coulter Counter for particle size analysis in research and plant control adaptations are indicated.

Jan 1, 1960

By Joseph D. Martinez

Salt, because of its plasticity, exerts a major influence in deformation. Resulting salt structures are common world-wide. A special type, salt domes, are associated with thick sequences of sediments deposited over salt. Their upward intrusion is generally thought to be in response to buoyancy. Mines in salt domes reveal an internal pattern compatible with large amounts of vertical flowage. Caprock, the end product of accumulation of anhydrite from salt dissolution, attests to long continued upward growth and concomitant truncation by moving underground waters. Concepts of modes of growth are evaluated and related to problems in utilization.

Jan 1, 1979