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By R. G. Church

Belle Ayr Mine was established in 1972 as the first large surface coal mine in the Powder River Basin of Wyoming. During the mid-1980s, it was eventually out-distanced in productivity by newer mines, and management recognized that the mine must recapitalize its major mining equipment and enhance its workforce flexibility in order to be competitive in the deteriorating market situation. Therefore, state-of-the-art haulage and loading equipment was placed into service, and a 12-hour rotating shift and a technician-based workforce was implemented. Belle Ayr Mine is located 29 km (18 miles) southeast of Gillette, Wyoming, in Campbell County (Figure 1). The mine is a part of AMAX Coal West, Inc., and with its sister mine, Eagle Butte, located 8 km (5 miles) north of Gillette, is a major contributor to the overall coal production of AMAX Coal Industries, Inc., headquartered in Houston, Texas. This paper addresses mine planning, recapitalization initiatives, and innovative workforce changes which propelled this large, surface coal mine to the forefront of productivity in the ever tightening low sulphur coal market.

Jan 1, 1994

By L. A. Panek

A new pillar strength formula is presented, incorporating a function P of size and shape, which takes into account the size-shape interaction effect as well as the enhanced strength exhibited by wide pillars. Existing pillar formulas, lacking these capabilities, are not suitable for extrapolating small-specimen test results to mine-pillar sizes and shapes. Interpreting compressive-strength test results as function of P clearly reveals wide-pillar behavior in much old test data. Model relationships are discussed, along with their scaling implications.

Jan 1, 1994

By V. E. Housman

EPA's Mining Waste Section within the Office of Solid Waste is continuing to collect and analyze information on mining waste management practices. Starting in 1991, the Mining Waste Section has continued to conduct site visits and prepare case study reports on the waste generation and management practices of operating mines. In choosing sites to study, a reasonable attempt was made to provide diversity in mining commodity types, geographic regions, geology, climate, and environment. To date, EPA has visited the following mines: Asarco Troy (copper) in Montana, Newmont Rain in Nevada (gold), Cyprus Thompson Creek (molybdenum) in Idaho, LTV Steel (iron) in Minnesota, Phelps Dodge Morenci (copper) in Arizona, Doe Run Fletcher (lead) in Missouri, Brewer (gold) in South Carolina, IMC Four Corners (phosphate) .in Florida, Pennzoil Culberson (sulfur) in Texas, Nerco Cripple Creek (gold) in Colorado, Copper Range White Pine (copper) in Michigan, Magma San Manuel (copper) in Arizona, Colosseum (gold) in California, and several gold placer mines in Alaska, including the Valdez Creek Mine. EPA has prepared a case study report on each facility. The mine operators were provided an opportunity to comment on their respective site visit report and their comments have been included in' each respective report. These site visit reports have in turn been incorporated into technical resource documents which provide a detailed description of each mining sector. EPA is currently reviewing the technical resource documents and plans to release the documents in the Spring of 1994.

Jan 1, 1994

By J. C. Haptonstall

The Bismark Mine is located in northern Chihuahua, 150 km southwest of Ciudad Juarez. The ore deposit was discovered in 1979, and was placed in production in 1992. The production rate is about 2400 tpd from an ore reserve of 8.5M tonnes. Grades average about 8 % Zn, 0.5 % Pb, 0.2 % Cu and 50 g Ag per tonne. Substantial inflows of water into the under-ground mine complicate the operation. Complex metallurgy poses another challenge for the operators. Bismark was operated through a joint venture, Minera Bismark, S.A. de C.V., with U.S. and Mexican partners, but since early 1993, it is wholly Mexican-owned and operated.

Jan 1, 1994

By D. Shuck

Incorporation of a 2,727 mtpd, $5.7 million flotation circuit into the Mclaughlin flowsheet was completed in November 1991. This capital addition reduced overall operating costs and improved the gold recovery of the low grade refractory reserves over that expected for direct cyanidation. In addition, flotation provided a means to generate a sulfide concentrate which is utilized to supplement feed to the pressure oxidation circuit.

Jan 1, 1994

By D. Crouse

A significant wollastonite resource has been discovered and evaluated near Seeley's Bay in southeastern Ontario. The deposit occurs in Grenville Frontenac Terrane granulite facies rock within a calc-silicate skarn in contact with Proterozoic-age gabbro. The steeply-dipping and tightly-folded wollastonite skarn beds are interlayered with diopside and quartz-feldspar skarns in a southwest-plunging synclinorium. More than 9 million tonnes of a drill-proven and inferred resource grading 41 % wollastonite has been identified, as well as an additional 3 million tonnes grading 30%. Mineralogical and process test work with the wollastonite from this deposit has demonstrated the potential to produce a high purity, high aspect ratio wollastonite product.

Jan 1, 1994

By Thomas A. Wheeler

The reagents commercially used in coal flotation and their roles are reviewed and discussed According to their function the reagents are divided into often overlapping groups: 1. Collectors 2. Frothers 3. Conditioning Reagents Frothers have by far the largest effect on the amount of coal recovered They act not only in their traditionally accepted function of “bubble makers”, but in coal flotation they serve in a seldom acknowledged role of collectors. A lab flotation study on four samples of different coal ranks shows how these react to various frother families and proves that no froher is the optimum reagent for all types of coal. The advent of new technology in flotation equipment in the past decade has resulted in various novel designs of column cells, Jameson and Centrifloat™ cells, air-sped hydrocylones, etc. All should require special frothers or blends of frothers to meet their specific needs.

Jan 1, 1994

By R. Fields

Nevada is primarily known today for its nation-leading production of gold and silver. However, industrial mineral production continues to play an important role in providing construction materials to help make the state the fastest growing in the United States. Aggregate production in Nevada was about 20 million tons in 1991. Most of that was used in construction in the fast-growing Las Vegas area. The state leads the nation in the production of barite and mined magnesite and has significant production of lithium carbonate, diatomite and gypsum. Other industrial minerals produced in the state include specialty clays, silica, lime and dolomite and relatively small production in salt, perlite and dimension stone. Industrial minerals operations are subject to state and federal permitting requirements, especially in the areas of air and water quality and mined land reclamation. As in all segments of the mineral producing industries throughout the nation, the amount and complexity of regulations affecting industrial minerals has increased significantly in recent years. Nevada is no exception.

Jan 1, 1993

By I. H. Gundiler

Although cyanidation has been universally applied in the processing of gold and silver ores, the search for less toxic alternatives continues. Difficulties encountered in processing ores containing oxidized copper minerals and the inherently slow kinetics of cyanidation have generated a renewed interest in thiosulfate leaching. This process, as well as the catalytic effects of copper ion, were well recognized and widely applied towards the end of the past century. In this study, the effects of copper, ammonia, and thiosulfate concentrations on gold dissolution were investigated using the rotating disk technique. Extraction of gold and silver from an oxidized copper-bearing ore was also studied utilizing a statistical experimental design, and these results were displayed in the form of contour plots.

Jan 1, 1993

By M. P. Oommen

This paper provides a brief look at a proposed short-longwall for coal, development. The proposed method is an attempt to realize the advantages of longwall mining in deposits that, historically, would only be minable by continuous mining methods. An overview of the proposed layout, development requirements, production rate, ventilation scheme and other associated features is provided. This mining method could help operators in above-drainage seams where minable areas are smaller. It may also have application in areas that are peppered with gas wells and in environmentally sensitive areas which preclude the use of conventional longwalls.

Jan 1, 1993

By Dr. -Ing. Rainer Alles

Introduction Belt conveyors usually run in a straight line. The correct alignment is a major criterion for reliable functioning and optimum running properties. Any misalignment of the conveyor, especially mistracking of the belt, can have many negative effects. As a consequence of this, damage can occur on the belt and conveyor, some material can he thrown off at the edges and serious running problems can arise. In the worst case the belt can come off its supporting structure so that operations are brought to a halt. The absolutely straight alignment of a belt conveyor is actually impossible so that on closer observation every belt conveyor contains more or less sharp curves. Whereas on non-movable conveyors the deviations from the straight can he kept within the range of practical measuring accuracy by careful installation, movable conveyors in surface mining or belt systems in difficult terrain often contain curves that are easy to see with the naked eye. Below ground, too, alignment cannot always achieved to a desirable extent or is changed by geological faults over the years. Despite these unwanted curves, most belt conveyors perform their function reliably. In view of the belt tension, the belt tends to take the easiest path. This in general is the shortest distance between the pulleys on which the belt is tensioned and bent. This means for example that for a curve radius of 10,000 m over a flight of 100 m the greatest deviation from the ideal line is as much as 12 cm. And a figure of this magnitude cannot normally he accepted. In such cases, use is made of guide devices to properly train the belt if it doesn't center itself anyway. If it's possible to control the belt position over such unwanted curves. it can also he expected that the belt tends to follow the desired curved path within certain limits. I'd now like to cite a few examples to illustrate the ways and means of guiding a belt conveyor in curves. Cost-effectiveness The advantages of belt conveyors, in particular for longer conveying distances and mass flows have been known and undisputed for some time. However, there are often obstacles standing in the way of the concept of straight routing. If a belt conveyor is to bypass elevations or existing buildings or to follow the seam of underground deposits or a predetermined path, then substantially tighter radii and longer curves are desirable or necessary.

Jan 1, 1993

By S. M. Khandrika

It is shown that dewatering of fine coal particles (D50 : 21 microns) is enhanced near the point of zero charge. The coal surface is modified by the addition of copper ions and adjusting pH to precipitate surface active metal hydroxy species which promote agglomeration and produce low moisture cakes. Filtration kinetics data are used in calculating filter cake parameters from an integrated form of Darcy's law. The influence of copper ions and pH on filter cake parameters and correlations among them are presented.

Jan 1, 1993

By G. H. Harris

The flotation behavior of two high sulfur coals using a non-ionic surfactant as collector from two series of compounds containing oxygenated functional groups was studied in detail using a 2-liter Denver flotation cell. The performance of these reagents was compared with that of an oily collector, namely dodecane. The results showed that at the same coal recovery, a much lower dosage of these non-ionic surfactants was required as compared with that of dodecane. More import was the performance of these compounds as promoters for oxidized as well as un oxidized coal. Mechanisms of interaction of these compounds with the coal are suggested.

Jan 1, 1993

By D. R. Hembree

This paper discusses the mineralogy and metallurgy of the Kuroko-style volcanogenic massive sulfide ores mined at Formosa Exploration Inc. I s Silver Butte Mine located in southwest Oregon. The principle ore type is pyrite + chalcopyrite + sphalerite, while subsidiary pyrite + bornite + sphalerite ore is also mined. The two styles of mineralization have distinctly different metallurgical behaviors and must be treated separately. Selective flotation methods are used to produce copper and zinc concentrates from the first ore type, while bulk concentrates are produced from the bornite ore. Careful mine planning and coordination between the mine and mill are utilized to achieve optimal recoveries.

Jan 1, 1993

By A. Henchiri, G. A. Gruber

INTRODUCTION Phosphatic resources may be quantified in terms of ore tons and phosphate analyses; however, to quantify phosphate reserves it is necessary to estimate the tons and quality of phosphate rock that can be extracted from the ore. The yield and grade of phosphate rock that can recovered from sedimentary phosphate deposits are usually difficult to estimate because of variations in stratigraphy and/or mineralogy. Prospecting phosphorite ores for purposes of estimating reserves and preparing mine plans requires considerably more effort than defining ore thickness and P205 content. In Florida, for example, it is standard practice to prospect by core drilling and to subject each strata (split) to beneficiation testing, and to perform detailed chemical analyses on the beneficiated products from each strata. For a completed drilling pattern the area of influence of each hole is 2.5 acres. The number of strata per drill hole typically varies from two to five, and thus complete prospecting of a 40acre tract requires drilling 16 core holes and beneficiation testing of about 48 ore samples. Florida practice is not appropriate for all phosphorite deposits. Functional drill rigs and trained drillers may not be readily available. Water for core drilling may be unavailable and the characteristics of either the overburden or ore may require careful attention and excessive cost to obtain representative core samples. Alternate ore sampling methods include auger drilling, rotary drilling to obtain cuttings, and the excavation of trenches, pits, and shafts. Drill cuttings samples are generally the least expensive to obtain, but they are usually unsuitable for beneficiation testing because of particle size reduction during drilling. Ore samples from surface trenches and pits are expensive and may not be representative of deeper ore. Ore samples from shafts are the most expensive to obtain, but if taken properly they are reliable for use in laboratory and pilot plant testing. Regardless of the prospecting technique used, reliable estimates of the yield and grade of phosphate rock that can be extracted from an ore deposit are required: • to justify capital expenditures for a new mine • for mine design and mine planning • for beneficiation plant design • for production forecasts, quality control, and marketing. This paper describes models that predict the beneficiation response of ores from three phosphate ore deposits. The purpose of these models is to obtain maximum utilization of available prospect data with the least cost. ORE DEPOSITS Simple beneficiation models have been developed for ores from three sedimentary phosphate deposits around the Mediterranean area. The first deposit, herein described as "A" ore, is located north of the Mediterranean Sea. The second deposit, designated as "B" ore, is located east of the Mediterranean Sea, while the third deposit, "C" ore, is located south of the Mediterranean Sea. Ore "C" is from the Sra Ouertane deposit in northwestern Tunisia.

Jan 1, 1993

By K. L. Kayler

Ball clay production in 1991 amounted to about 800 kt (880,000 st), about the same as in 1990. 1992 estimates show a 5% decrease to 750 kt (827,000 st). This decrease continued a trend of reduced production that began after the peak of 900 kt (1 million st) that occurred in 1988. Use of ball clay in sanitary ware was about 2% less in 1992, although levels of use in floors and wall tile, dinner ware and pottery remained constant. Filler, extender and binder applications continued to be important end uses, accounting for about 17% of total market. Refractory uses maintained their market share of about 17 kt (18,700 st). Use of clay liners in toxic and waste dumps is an application widely found in Germany. However, its use has not been fully exploited in the United States. This could represent an opportunity for domestic clay producers. Tennessee remained the leading source of ball clays. Other producers were Indiana, Kentucky, Mississippi and Texas. Tennessee's production, however, decreased about 3% in tonnage produced and its value dropped from 68% to 65% of total production. The ceramics division of Southern Clay Products, Inc., was bought from LaPorte plc by United Clays of Texas, Inc., a US subsidiary of Watts Blake Bearne & Co. The purchase included ball clay reserves at Troup, TX. The acquisition makes United Clays the second largest ball clay producer in the United Sates. United is also the only company mining clay in Texas. Fire clay production decreased 5%

Jan 1, 1993

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

Microorganisms have been widely used for hydrometallurgical operation and effluent treatments(Smith, et. al., 1991a; Gadd, et. al., 1986; Darnall, 1986; Paponettis, et. al., 1991; Mihaylov, et. al., 1991; Rusin, et. al., 1991; Noble, et. al., 1991; Yang, et. al., 1991). In recent years there is a growing interest in using microorganism for flocculation of minerals fines and flotation collector (Smith, et. al., 1991b, 1991c; Misra, et. al., 1991a, 1991b, 1992a, 1992b). It is envisioned that the utilization of nonpathogenic microorganism and/or extracellular surfactant derived from microorganism as a flotation collector will replace some of the environmentally toxic flotation collectors and at the sometime improve flotation efficiency. The selection screening, and judicious selection of appropriate microorganism as flotation collector has been a challenge to process engineers. Over the past five years, continued research at the University of Nevada has shown that certain microorganism Mycobacterium phlei (M. phlei) can be a good flocculating agent and has potential to be used as a flotation collector (Dubel, et. al., 1992; Misra, et. al., 1991a, 1991b, 1992a, 1992b; Smith, et. al., 1991d; Chen, et. al., 1992a, 1992b)).

Jan 1, 1993

By Donald L. Meredith, Jeffrey Harris, Donald A. Stanley

Principal Components Analysis (PCA) is a versatile, multivariate statistical method that the Bureau of Mines is applying to mineral processing data to achieve data simplification and pattern recognition. The principal components are obtained from an eigenanalysis of the data matrix. To achieve data simplification PCA replaces a larger number of measured variables with a smaller set of principal components and at the same time removes a significant amount of experimental error. Data simplification and error reduction make PCA useful in process control. Plots of the individual principal components form the basis of a pattern recognition technique that allows detection of significant variations in the structure of the data. These applications of PCA are illustrated with appropriate mineral processing data.

Jan 1, 1993

By Lit-Mian Chan, David H. Carlson, John H. Johnson

This paper presents an apparatus and procedures to implement a methodology for controlling ambient air quality in a confined working environment, such as an underground mine, an underground storage area, or a tunnel. The air quality control methodology is directed at limiting the quantities of exhaust pollutants emitted by diesel-powered vehicles into the confined space by identifying vehicles that are excessive polluters. The methodology is based on tailpipe and ambient air measurements in the confined space, and the ambient air threshold limit values (TLVs) for the various diesel exhaust pollutants. The methodology consists of two computational methods; a deterioration criteria computational method to identify excessive polluting vehicles, and an engine performance computational method to determine engine performance and to provide information needed to diagnose engine faults. The methodology is designed for implementation in conjunction with a preventive maintenance program. The first part of the paper describes the mine air and tailpipe emissions measurement apparatus and techniques used to obtain data. This is followed by sections discussing the deterioration criteria and the engine performance computational methods. A section discussing some common engine emissions-related faults is also presented. Lastly, a proposed procedure to implement the methodology including a possible hierarchical structure for mine personnel involved to implement the procedures is presented.

Jan 1, 1993