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By C. D. Harrison

This paper presents the results of 18 high-G centrifuge tests performed at the Electric Power Research Institute's Coal Cleaning Test Facility in January 1985. These tests, using -28 mesh (0.6mm) froth flotation product, show that the high-G, solid-bowl centrifuge can produce clean-coal moistures of less than 12 percent at solids recovery rates exceeding 98 percent. The high-G centrifuge achieved these low moistures by applying centrifugal forces up to 2,000 times gravity. Because these forces are two to three times the forces used in a screen-bowl centrifuge, the high-G centrifuge can use a solid bowl and still produce a low-moisture product. The solid bowl captures ultrafines that would pass through a screen bowl, and thus obtains higher recovery rates than a screen-bowl centrifuge.

Jan 1, 1985

By D. C. Sisti

A paper was presented during the 1970 SME Fall Meeting on the Stinson Preparation Facilities by representatives of Beaver Creek Consolidated Cool Company and Heyl & Patterson, Inc. This paper summarized a combined approach to development of a flow diagram and selection of cleaning equipment required to produce a uniform metallurgical coal at maximum recovery with special emphasis on sulphur reduction. These facilities were located in the Elkhorn. Coal Fields of eastern Kentucky and, in particular, the area of Wayland, Knott County, Kentucky, where approximately forty-five- million tons of Elkhorn No. 3 coal could he recovered. The facilities incorporated a Bradford Breaker for reduction of the ROM coal to minus 1-1/2 x 0, 6000 ton-raw coal storage, preparation plant, water clarification and thermal drying facilities, clean coal storage and a 4000 TPH unit train loading facility.

Jan 1, 1973

By Terry D. Vandell

The purposes of this presentation are: (1) to discuss the actual as well as potential incidents that have caused and that could cause groundwater contamination at uranium in situ leach mining sites and (2) to discuss remedial actions and solutions that have been or that could be implemented in the future to stop or prevent serious groundwater contamination from in situ leach mining in Wyoming?s Powder River Basin. Open pit, underground, and existing and proposed in situ leach uranium mine sites in the Powder River Basin are shown in Figure 1. In situ leach mining or solution mining for extracting minerals in liquid form is a relatively new addition to the list of conventional mining methods currently used to extract uranium in Wyoming's Powder River Basin. Basically, the in situ leach mining method involves: (1) the injection of a leach solution lixiviant (an acidic or basic oxidizing solution) into a uranium-bearing ore body, via injection wells, to complex the contained uranium, (2) mobilization of the uranium complex from the host material via creation of a soluble complex salt, and (3) surface recovery of the solution bearing the uranium complex via production wells. Uranium is then separated from the leach solution by conventional milling unit operations (ion exchange).

Jan 1, 1981

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 J. E. Osmanski

This semantically ambiguous title purports to describe an examination of the question of automation and its effect on the industrial worker. More explicit titles might be "Painless Automation" or "Mechanization without a Sting" or, if I may steal a few phrases from the title of a recent interview Pith John L. Lewis, "More Machines, Fewer Men -- Is the Union Happy About It?" Automation has become the biggest ?scare word? for many industrial workers and their unions since "wage stabilization.? "To many a union orator," reports TIME of January 4, "automation is the sinister business of eliminating jobs." TIME might better have phrased this description by saying that many unions regard automation as the attempt to eliminate not jobs, but workers, The recent steel dispute was hung up for so long primarily because of the problems evolved of increased job efficiency through automation and job changes. Everywhere today there is heard the cry of our need for maintaining full employment within the context of an expanding economy echoing against the sheer reality of automation's displacement of thousands of workers through a rapid acceleration of productivity.

Jan 1, 1960

By Thomas J. Ferree

A Reichert cone concentrator was installed in an aggregate plant circuit to recover the extremely fine "flour gold" known to exist in the deposit. The gold content of the bank-run gravels averages about 0.1 grams per ton (about $1.45 per ton), based upon $14.47/g (345O/ounce) gold. Tine Reichert cone, in conjunction with a conventional shaking table, re- covers in excess of 85% of the gold. A screen analysis of the gold particles shows 44.1% is -i4 microns (-200 mesh) in size. The plant operates with a two-man crew.

Jan 1, 1981

By Robert H. Oliver

Flowsheet flexibility in new 750 TPH coal cleaning plant provides three unusual capabilities. Two compartment drum coarse H.M. washer can be adapted to provide two stage separation. Coarse section of plant can be operated without fine section when washing surface mined coal. Fine section can operate with flotation cells bypassed if strip coal oxidation kills the froth. Plant can be fed by belt from bulk storage, front end loader from storage piles and truck from the mines. Raw coal and each of four washed products can be fed by belts to three separate loading points on two separate railroads.

Jan 1, 1979

By Charles W. Rountree

Industrial Engineering in the industrial world is a relatively new field, having been conceived about the turn' of the century by Frederick W. Taylor, who was not satisfied with the hit-or-miss methods of evaluation and estimation. Through crude Industrial Engineering techniques never before used, he completely changed the bricklaying industry so that work accomplished was more than doubled. To help us better understand what we mean by Industrial Engineering, I think a very simple definition Is in order. Industrial Engineering is a scientific approach to problems in cost, production and operations: and is designed to provide a means of increasing producitivity and reducing costs through standards measurement and standardization of the best methods, practices and equipment, There are many complicated definitions, but pure and simply, it all boils down to providing the means for increasing productivity and reducing the cost. Industrial Engineering has been applied in manufacturing since Frederick W. Taylor?s time and in the last 20 years has grown in stature by leaps and bounds. It is a basic function of successful manufacturing companies and is an accepted fool firmly entrenched in manufacturing organizations. You may know of some successful manufacturing companies that do not employ Industrial Engineers as such, but someone in that organization is doing Industrial Engineering work. They have standards and controls whether they call it Industrial Engineering or not. The manufacturing industry has benefited from this tool; other wise, it would have been discontinued long ago.

Jan 1, 1958

By J. R. Knudson

A major contribution to the art of blasting was made at the Cleveland- Cliffs Iron Company?s Hawkins Mine in Cashwauk, Minnesota during April of 1956. It was here that the first experiments with fertilizer grade ammonium nitrate were conducted-experiments which led to the development of the ammonium nitrate and fuel oil method of blasting which has been eagerly adopted by open pit and quarry operators throughout the United States. While this new blasting agent was a more or less natural outgrowth of the Akremite Process devised by Maumee Colleries of Terre Haute, Indiana; no one, to our knowledge, had used this particular combination of ingredients prior to this time. Certainly this was a "break-through" as far as the Lake Superior District was concerned. Akremite consists of a mechanical mixture of grained ammonium nitrate and a solid carbonaceous material packed in a plastic bag. At the time of its introduction to the Mesaba Range, Akremite sold for 10.5 cents a pound as compared to the 18 cent powder previously used in both wet and dry large hole blasting. The discovery of this agent was indeed a remarkable achievement, one that afforded a substantial reduction in blasting costs. However, Akremite proved to be only an intermediate step in the evolution of our present low cost explosives. Cleveland-Cliffs utilized prilled ammonium nitrate and fuel oil and then eliminated the mixing and packaging plant entirely by combining the two raw materials in the field at the drill hole collar or in the hole itself. Thus we have approached the ultimate in simplicity, for the blaster and his helper now manufacture their own explosives not only as they are needed but where they are needed, and at a cost of under 4 cents a pound. This two-man crew may charge and explode as much as 8 tons of ammonium nitrate in an eight-hour shift and in so doing break some 65,000 tons of ore.

Jan 1, 1959

By R. W. O. Kersten

The shrinkage method of stoping with pillar support has been used at Agnes Gold Mine since mining commenced. Until recently, rock instability did not have any detrimental effect on safety or production. Presently sill pillars are failing not only on the current production levels, but also in shallower old worked-out areas. The incidence of failure raises the question as to whether the pillar dimensions are adequate at the current working depths and what their size should be at greater depths. The effect of pillar dimensions on the economics of the mining operation is of paramount importance because of the amount of ore that can be left unmined.

Jan 1, 1982

By Wolfram Schnabel

Recently Lurgi has succesfully commissioned Peru's first direct reduction rotary kiln at SIDERPERU?s Chimbote works. The order included comprehensive engineering services and supply of special equipment to modify three existing cement kilns according to the SL/RN process. The kilns were cut to 62m length and installed with a slope of 2.5%. A new heating system, including shell burners, was supplied and inlet and outlet ends of the kilns completely renewed. Figure 1 shows the kilns after modification.

Jan 1, 1981

By R. C. Runvick

Gypsum resources are significant in the midwestern United States, with specific deposits varying in "place value" relative to the major markets served. Underground and surface mining operations produce gypsum from sedimentary rocks ranging in age from Silurian through. Jurassic. Although reserves tend to be limited at individual operating properties, potential resources are vast and future development will hinge principally on market growth and changing economic conditions. Most critical of the variables affecting the industry in both the short and long term will be the availability, type and cost of energy and both processing and distribution.

Jan 1, 1980

By J. A. Herbst

Ball mill grinding circuits can be subject to upsets that arise from variable characteristics of the feed ore. These upsets are transients in critical circuit variables such as ball mill mass holdup, circulating load, sump level, cyclone efficiency and product particle size. They may occur frequently so that the operation is continuously fluctuating or they may be of such magnitude that some of the equipment is overloaded, resulting in shutdown, or an undesirable product particle size. The feed ore characteristics that influence ball mill circuit behavior in this manner include the grindability of the ore, the eventual transport characteristics of the ore in the mills and the feed ore size distribution. Control strategies for grinding circuits using conventional proportional-integral (PI) control have limitations to their effectiveness in controlling against feed ore disturbances. The first of these are the interactive nature of two or more control loops on a single circuit. Under some circumstances they begin to fight each other, increasing control error and settling time. PI control loop gain constants can be tuned to give best response for some set of conditions but once these change, as they would with a change in the feed ore, they are no longer the "best" ones (Shinsky, 1967). Due to these limitations, alternatives to conventional PI control strategies have been investigated for grinding as well as other mineral processing operations. These alternatives, all computer-based, include self tuning regulators, decoupling control and optimal control (Herbst and Bascur, 1983).

Jan 1, 1984

By C. Tom Blevins

LADIES AND GENTLEMEN : This presentation is to discuss production and roof control problems associated with directional lateral stresses in an in situ stress field and the approach that Inland Steel Coal Company made in trying to cope with them. Before proceeding, a brief description of the mine location, product, geology, restraints, and mine history is in order.

Jan 1, 1982

By R. L. Teseneer

Pyrite samples from twenty-one locations in the North Carolina Slate Belt were analyzed for cobalt, gold, mercury, and nickel by atomic absorption spectrophotometry. The geographic distribution of relatively high values of certain trace elements in pyrite suggests that, in addition to gold, cobalt and nickel metallogenetic provinces are possible in the slate belt. Northwest trends of province boundaries may be genetically related to subsurface features rather than to surface geology. Within province boundaries gold and nickel exploration programs should be concentrated in areas containing intermediate to mafic tuffs, while cobalt may be more concentrated in argillites and phyllites.

Jan 1, 1979

By Nicholas Chlumecky

A practical method is described for determining or checking whether underground supports such as props, posts and mechanized longwall supports have bearing areas of proper size in relation to the type of ground or floor strata on which they are standing, It is felt that this information provides an approach to eliminate, as much as possible, a potential grave source of error during the selection of roof supports. This would also affect the choice of costly mechanized longwall equipment where it is possible that the size of the bearing area is not as carefully determined as, for instance, the design strength of structural components.

Jan 1, 1967

By Robert A. Metz

During the past decade we have witnessed spectacular improvements in productivity of open pit mining equipment. Thousand-horsepower engines, 200-ton trucks and 15-yard electric shovels, which such a short time ago were just dreams on a drawing board, are now realities. More productive equipment and metal shortages have encouraged increased production at existing mines and the development of new larger tonnage operations. Operators and engineers have been able to employ computers and various other types of automation to "stay on top of things". The mine geologist, however, is merely faced with a bigger and more rapidly changing pit to pick in. Keeping geologic information current in these mines presents entirely new problems to mine geological staffs. To obtain adequate geologic information on the developing orebody requires enlargement of the staff to share the work load or revision of methods in keeping with the times. The former has the disadvantage of loss of the comprehensive knowledge of the pit that a chief geologist likes to have, not to mention management's usual lack of enthusiasm for force increases.

Jan 1, 1970

By J. E. Lonergan

The in-pit placement of crushing and conveying equipment results in a flattening of the pit slope of a multiple-bench open pit mine. To maximize the economic benefit of lower haulage costs associated with in-pit conveying, one must minimize the cost of the flatter slope which is expressed in terms of additional stripping or tied up ore. A computer program that compares the tonnage aspects of various conveyor layouts will be discussed.

Jan 1, 1985

By John T. Awald

The efficiency of search for porphyry copper and molybdenum deposits can be greatly increased. A model exploration system is here presented to show how geologic literature data and field surveys can be aided by modern statistical and computer methods. Assuming that major ore deposits occur in clusters, it is possible to evaluate rapidly large areas at modest cost and with minimum investment risk. An example of the success of these methods is given. Clusters of mine density and metal production covering the State of Nevada were plotted and machine contoured. Selection of a 47,300 square-mile area on the Nevada-California border was made. Within this area, detailed analyses were performed, and a 3000 square-mile site was picked for subsequent field examination. To initiate efficiently the field work, 81 stream sediment geochemical samples were collected and analyzed for copper, zinc, and molybdenum. These data established local variance and necessary statistical controls. Following this, a total of 151 geochemical samples were used to survey the 3000 square-mile area. Computer contouring of results directed attention to specific target areas for detailed geologic analysis, property acquisition and drilling. A total of 22 copper-zinc and molybdenum anomalies were identified. Four of these were recommended for further exploration. To date, two have been acquired and drilled and preliminary ore reserve and financial analysis have been made on one. The estimated cost and time for the regional exploration phases leading to these targets were thirty man-weeks and $16,000.

Jan 1, 1973

By J. Van Kleunen

In the Spring of 1959 the Riverside Cement Company, a Division of American Cement Corporation, placed into operation at their Oro Grande California plant a new crushing-blending-reclaiming facility. This new facility, in conjunction with other modernization in the plant, has established a degree of automation and reliability on a-plant-wide basis which heretofore had not been attained in the industry. The blending and reclaiming facilities for raw stone and cement clinker at this plant represent not only the first computer programmed materials handling system of its type in the industry, but also the first installation of specialized equipment which was designed for high capacity, fully automated operations.

Jan 1, 1963