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By John P. Hunt

Early disseminated copper mineralization at Quebrada Blanca, Chile, accompanied 38 million year old quartz monzonite stocks and dikes. Early mineralization was followed by hydrothermal mineralization, mineralized breccias, and post-mineral faulting. After supergene leaching and enrichment, Quebrada Blanca was buried under late Tertiary gravels, and then partially re- exposed in Quaternary time. Based on work to date the orebody appears to contain more than one hundred million tons of plus one percent secondarily enriched copper ore, overlying several hundred million tons of protore averaging more than 0.5% copper. A source of industrial water appears to have been located. Pilot scale metallurgical tests, mine planning, and feasibility studies are in progress.

Jan 1, 1981

By Jean-Michel Rendu

Accurate modeling of the semivariogram is an extremely important step in the geostatistical analysis of mineral deposits. Automatic fitting of a mathematical model is often possible but not necessarily desirable. Significant geologic and statistical information must be taken into account in the fitting process, which is not always available to the computer. Manual fitting of the model is, on the other hand, extremely time consuming. Interactive graphics are best suited to optimize the process. A number of interactive methods are described, which are adapted to the modeling of semivariograms in one-, two-, or three-dimensional environments.

Jan 1, 1982

By John T. Cantwell

INTRODUCTION The process engineer usually is responsible for the design operating philosophy and/or day-to-day operations of a process. Since instrumentation is an integral part of the operation, it is essential that engineers understand the general capabilities of the different types of control equipment available. Many "noncontrol" engineers have become involved with instrumentation for machinery monitoring and control as well as other plant applications. The advent of the microprocessor has led to significant changes in control, both in systems configurations and man-machine interfaces. Today's concept is called simply "distributed control." What is distributed control? Distributed control is exactly what the name implies; the control system is divided into several functional segments and spread out to cover a process. The systems are distributed for physical, functional, and risk reasons. Before delving further into the specifics of distributed control, let's look at the evolution of control systems to see how we got here. Instruments initially were located near measurement and control points in the field. Operators physically had to go to the instrument to change setpoints or take measurements. As processes became more complex, it became evident that a central control area was required. This allowed an operator to monitor and control many variables. The operator's effectiveness was increased dramatically, which resulted in greater efficiency, better quality control, and lower personnel requirements. At the same time, plants became much larger, control applications became more complex, energy became expensive, and the industry became more competitive. All of these factors placed pressure on process and production engineers to get the most for the money. The result was a continuing push to put more instrumentation into a central control room to maximize efficiency and productivity and minimize manpower. This chapter deals in some detail with devices for measuring physical and chemical properties of coal; devices for measuring the weight and weight-rate of flow of coal; devices for the monitoring and control of conveyor systems, solids inventory, fluid flow, liquid level, density, and specific gravity. These instruments have a multitude of uses throughout a coal preparation plant. The discussions cover advancements in "on-line analysis," nuclear control devices, and distributed control using microprocessors, mainframes, and soft-

Jan 1, 1991

By H. B. Charmbury

The acid mine drainage problem in Pennsylvania is of continuing and growing interest to the coal mining industry, the state government and the citizenry at large. Approximately one-third of the total volume of mine drainage presently polluting the streams of the Commonwealth originates from active coal operations and two-thirds come from ?abandoned mine discharges.? For this reason the Pennsylvania Department of Mines and Mineral Industries has mounted a significant research and action program seeking solutions to this two-fold problem. The Coal Research Board of the Department has sponsored a wide variety of research projects in an effort to study the treatment of acidic and highly ferruginous mine waters. A review of the published literature on the treatment of mine waters indicated that many laboratory and theoretical studies had been undertaken on various aspects of the coal mine drainage problem, but little applied, developmental, or engineering study had been undertaken. In January of 1964 the Board commenced a rigorous program using state and industry funds in an effort to find a ?least cost? solution or solutions to this vexing problem.

Jan 1, 1967

By F. Vincent, A. Boulet, M. Noaparast, F. Woodcock, A. R. Laplante

A novel methodology to estimate gold recovery by gravity is presented. It makes use of a population balance model which represents gold liberation, breakage and classification behaviour and applies pre-concentration and recovery data to gravity recoverable gold (GRG) to predict overall recovery. The methodology is designed for gravity circuits located in the circulating load of secondary grinding mills. Gold liberation is estimated by processing a sample of representative ore with a laboratory Knelson Concentrator (LKC) in three successive steps, each at a finer grind than the previous one. Breakage behaviour is represented by a matrix H, which redistributes GRG in the feed of the secondary mill in the various size classes of its discharge. Provision is also made to account for gold overgrinding, which decreases the overall amount of GRG. Classification, pre-concentration and recovery data are estimated from plant performance, and are represented by the diagonal matrices C, P and R. The methodology is demonstrated with case studies of greenfield, retrofit and optimization applications.

Jan 1, 1995

By Alain A. Sonntag

The MBS Solvent Extraction System utilises a unique design of mixer- settler having very high capacity per unit area and great flexibility. The development of the mixer-settler is traced through its various stages wherein the independence of mixing and pumping, reduction in settler area requirements and simplicity of plant layout were achieved. The laboratory, pilot plant and full scale tests contributing to the development of the machine are described. The existing KREBS SX plants in Europe and Africa are described as well as the plants presently under design. Results of recent testwork are also given.

Jan 1, 1981

By R. G. Reddy

Spent potliner is generated in the electrolytic process of reducing alumina to make aluminum metal using molten fluoride electrolytes. Spent potliner (SPL), obtained at the end of the pots life contains a small amount of cyanide and fluoride which present environmental problems. SPL became a listed hazardous waste under RCRA (K088) in July, 1990. One of the possible uses of spent potliner is as a substitute for Calcium Fluoride (CaF2) as a fluidizer in iron-and steel making and in the glass industry. A low viscosity and a low melting point are prime requirements for accomplishing the above. In the present study, viscosity measurements were performed. Effect of various additives, such as sand, limestone, dicalcium silicate dust, and MgO baghouse dust on the viscosity of SPL was studied. The results showed that with the addition of sand and limestone, very high fluidity of SPL melt can be obtained at significantly low temperatures. The results suggest that spent potliner mixed with additives could potentially be used as a substitute fluidizer.

Jan 1, 1999

By George F. McKeregahan

Phosphate production of the Central Florida Phosphate District has been predominantly from the unique and lucrative Bone Valley Formation, with local and minor amounts coming from the underlying Hawthorn Formation. As the Bone Valley is depleted, replacement production will move progressively into areas of total Hawthorn Production. Significant changes in the characteristics and make-up of the deposit dictate required modifications in mining and beneficiation. Failure to tailor technology to fit the deposits of the future will result in vast "reserve" losses. In the Southern Extension of the Central District - two distinct "ore types" exist. These are presently referred to as the upper (high grade) zone and the lower (low grade) zone. The upper zone is somewhat similar to the Bone Valley Formation and will respond favorably to present beneficiacion practices. The lower zone is strikingly different and its response to conventional beneficiation is not acceptable. The major differences are in grain size distribution and mineralogical make-up of these grains. The Hawthorn differs from the Bone Valley by exhibiting lower grades, lower tonnage yield per acre foot, lower pebble percent of product, higher mining ratios, higher slimes (-150 mesh) content and deeper mining depths. Physical characteristic changes include more frequent occurrences of competent bands or lenses of "limerock" which are submarginal in value.

Jan 1, 1983

By Taghi Sherizadeh, Kutay E. Karadeniz, Dogukan Guner, Samuel Nowak

Underground mining environments bring occupational health and safety issues with some severe dangers such as mine disasters like explosions. During such events, miners might escape using main access openings, or find a safe haven like refuge alternatives (RAs) to wait and be rescued and evacuated to the surface. In this paper, RAs are explained with their early and current applications. A classification as permanent and portable is explained depending on the conditions and their abilities. This classification is followed by the utilization and survivability of RAs with the requirements and recommendations of the main mining countries. Based on the utilization and survivability constraints, basic human requirements, waiting for a rescue team, and the required physical specifications of RAs during the events are analyzed in detail for various countries with their regulations. Among these, the specification, resistance to the explosion, is discussed in particular, and the studies in the literature are examined in terms of structural deformation. The highest deformed zones, the beneficiation of reinforcing steel components such as stiffeners, and the simulation approaches are investigated through this review.

Sep 24, 2022

By V. Svalbonas

In the establishment of a useful failure criteria for complicated, fabricated structures, two basic areas of knowledge must be evaluated: 1. The accuracy of the applied stress analysis must be known in comparison with actual stresses encountered during mill operation. 2. The metallurgical fracture properties of the basic materials must be established with reference to non-destructive examination (NDE) methods to be used during fabrication. Both of the above can only be evaluated by use of full scale tests on the structures, and/or components, of interest. This paper describes such tests and comparisons as applied to several large mill installations. In addition, weldment component fatigue tests arid flawed casting strain gauge tests are also discussed. The combination of such test results allows for the formulation of failure criteria directly applicable to the fabrication and examination procedures followed in grinding mill structure manufacture.

Jan 1, 1982

By Robert D. Deister

The Buick Concentrator represents state-of- the-art technology in automated digital process control operation utilizing a centralized computer. The process control strategies implemented at Buick are no longer new to the industry but the successful application of these developments is still rather unique in North America. Productivity improvements, determined to be a direct result of the process control developments, are the primary topics of this paper. Emphasis is placed on metallurgical benefits including both lead and zinc recoveries, lead concentrate grade and reductions realized in reagent consumptions, operating costs and personnel. The productivity improvement discussion is preceded by a concentrator description and a brief history of the process control development at Buick. Current control strategies and future applications are presented afterward.

Jan 1, 1985

By Phillip J. Maddex

Transportation is a major part of yours in the industrial minerals industry. Whereas federal income taxes merely take 50 per cent of your firms profits, transportation cost may take 50 per cent of the gross realization - selling price plus transportation - on your product, f. o. b. customers plant.

Jan 1, 1969

By H. C. Juvkam-Wold

The design of an aquifer depressurization system is discussed. The system uses a number of wells surrounding a mine shaft to reduce the aquifer pressure in the vicinity of the shaft. The effect of various parameters such as number of wells, wellbore diameter, time and well location is discussed. It is concluded that, with a properly designed depressurization system, the aquifer pressure and the water inflow rate to the shaft may be reduced to less than 15X of their potential values in the absence of wells

Jan 1, 1980

By T. Y. Yan

A method has been developed to remove calcite from the leaching circuit in the uranium in situ leaching system. The process involves injecting the leachate and a pH control agent tangentially into an inverted cone reactor containing calcite seed catalyst. The leachate can be treated at high throughput to obtain clear effluent containing 5 ppm or lower Ca. Both lime and ammonia are effective pH control agents and consumed according to stoichiometry.

Jan 1, 1983

By A. K. Sinha

A great potential market for the high BTU midwestern thermal coal exists if the coal is desulfurized and prepared to meet the environmental restrictions and the utility customer specifications. Because the midwestern coal is very high in pyritic sulfur, it can be adequately desulfurized by removing the pyrite with the help of such coal cleaning techniques as the froth flotation. Froth flotation cells are now commonly employed in modern coal preparation plants for recovering the fines but they are not utilized for desulfurizing the coal probably due to a lack of system operating data for such applications. A research project recently conducted at Southern Illinois University shows that the total sulfur in the midwestern coals can be successfully reduced from as high as 5.3 percent to less than 1.4 percent by single stage froth flotation. The results obtained on ten different samples of high sulfur coal obtained from different areas in the Illinois Basin are presented and discussed.

Jan 1, 1985

By Christopher J. Bise

The potential of the coal reserves in the western United States for meeting future energy needs has been recognized for quite some time. However, two of the major constraints which have tended to limit the development of these reserves which can only be deep-mined are the great thicknesses of the coal seams encountered and their high pitch. Although new mining methods may need to be developed to recover these reserves, at least in the short- term the industry has to incorporate presently available equipment which were not originally designed for thick-seam mining. The purpose of this paper is to present an analysis of the various equipment that are in use today and their possible application to thick-seam mining. The paper also addresses the various ground control and safety considerations that are unique to thick-seam extraction.

Jan 1, 1981

By A. E. Aldrich

The Pittsburg & Midway Coal Mining Co. (P&M) is expanding a combination of surface and underground coal mining operation in Northeastern New Mexico. The York Canyon Complex, located 35 miles west of Raton, New Mexico, is aggressively pre-paring for increased production while meeting present requirements. Surface mining activities in four separate mining areas are preparing the complex for additional markets. Drag-line, truck/shovel, highwall miner and contour stripping are surface mining methods currently planned. In addition, P&M will move a Marion 8200 dragline from Kansas to the York Canyon site, finish constructing a $20 million coal preparation plant, and complete conveyor upgrades to the existing underground mine. This paper will describe the diverse York Canyon Complex.

Jan 1, 1993

By R. J. Beckman

This paper traces the history of mica mining in Alabama from 1870-1970. The decline of sheet mica production is noted and emphasis is placed on the more recent activity of scrap mica production and the development of the U. S. Gypsum Co. mica properties in Randolph County, Prospecting for weathered pegmatites of sufficient size to warrant development is a continuing challenge since most deposits are too small and all exhibit varying characteristics as to size, shape, and weathering. Quantity and quality of muscovite mica in the pegmatites is of utmost importance and its recovery during processing of the ore is described.

Jan 1, 1970

By A.M. Wala

A new radioactive tracer method to measure airflow in inaccessible airways has been developed for situations when studies of the mine ventilation system are not possible using conventional flowmeters (anemometers). The new method has been tested in the ventilation laboratory at the University of Kentucky and in the Experimental Underground Coal Mine at the U.S. Bureau of Mines. This new tracer method has been utilized in leakage, dilution and flow velocity measurements in laboratory and field (mine) experiments.

Jan 1, 1996

By Z. Hladysz

It is common to nine a coal seam affected by previous extraction of a coal seam below. As a result of that severe problems may occur during the extraction process. This paper presents the analysis of undermining effects based on field observations. A simplified method for the evaluation of risk in undermining operations is presented and predictions of the degree of possible damages to the undermined coal seam is given.

Jan 1, 1985