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This paper reviews the historical literature and the author's experience with regard to the effect that the selection of grinding ball size or sizes has on ball mill grinding efficiency. The conclusions presented provide guidelines for single and multi-size charging prac- tices in commercial milling operations.

Jan 1, 1998

By Terry Ramsey, N. Finkelstein

INTRODUCTION The Cyprus Pima Mine is located 20 miles southwest of Tucson, Arizona and about fifty miles north of the Mexican border. The Cyprus Pima orebody was discovered in 1950. Feasibility studies were begun in 1952 employing underground development. Economic studies showed open pit operations to be feasible and stripping of overburden was begun in late 1955. The first ore was reached in October of 1956. A 3,000 tpd (tons per day) concentrator was completed and began operation January 1, 1957. From these beginnings, Cyprus Pima Mining Company has expanded into a plant processing approximately 54,000 to 56,000 tpd. Four expansions were required to bring the plant up to its present capacity. Each expansion incorporated what had been learned in previous operation of the plant. The first expansion was completed in August of 1963 doubling design capacity to 6,000 tpd. In reality, because of softer than average ore, capacity was closer to 8,000 tpd. Expansion I1 was completed in July 1966 bringing design capacity to 18,000 tpd. Expansion I11 followed immediately. Completed in the summer of 1967, this expansion increased the design capacity to 30,000 tpd. The actual dry tonnage of this portion of the operation in 1974 averaged 38,400 tpd, again, primarily as the result of treating softer than average ore. The latest expansion (Expansion IV), completed in December 1971 and utilizing a semi-autogenous grinding circuit, is located in a separate building (Mill 11) approximately 200 yards southeast of the original mill (Mill I). Expansion IV was designed for 14,000 tpd, but after circuit modifications, averaged 16,500 tpd in 1974.

Jan 1, 1976

By Jean-Michel Rendu

The semivariogram is one of the most important tools available to the geostatistician for the analysis of mineral deposits. To be complete, a semivariogram study must include a minimum of three parts which are highly interdependent. These are: calculation of the semivariogram, mathematical modeling, and geologic interpretation. The known factors and conditions which controlled or influenced the distribution of mineralization within the body being studied should be considered in the analysis .of the semivariogram. The presence and characteristics of successive phases of mineralization, the chemical and physical properties of the host rocks and the mineralization should all be considered. This requires close and continued communication between the geologist and the geostatistician prior to and during the semi-variogram study. Geologic stationarity is needed if meaningful semivariogram results are to be obtained. The first step is, therefore, to determine whether the mineralization can be analyzed as a whole or if different geologically homogeneous sections must be defined and evaluated separately. Different methods can be used to calculate an experimental semivariogram from known sample values. The method chosen will depend not only on the anticipated and actual statistical properties of the deposit, but also on its geologic characteristics.

Jan 1, 1982

By J. C. Yingling, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

Much of the land reclaimed since enactment of the 1977 Surface Mining Control and Reclamation Act is overcompacted. Research has shown that excessive compaction in replaced growing media is detrimental to the establishment of trees. If trees are to be grown on reclaimed surface mined sites, something must be done to alleviate this excessive compaction. Dry bulk density and penetration resistance are two soil parameters that can be used to indicate the level of compaction in reclaimed growing media. The University of Kentucky developed test cells on reclaimed areas at a surface mine in eastern Kentucky to determine the impact of tillage (ripping) on soil compaction and tree survival rate. The ripping methods being evaluated include shallow tillage using conventional farm equipment and deep tillage using a dozer with a ripping arm. Each test cell was planted with various species of trees, and for the first two years of tree growth, data were collected at these test cells for soil dry bulk density, penetration depth and resistance, and survival rate of trees. These data were statistically correlated to determine how ripping affects the relationship between soil compaction and tree survival rate.

Jan 1, 2003

By J. W. Shuster

Test of trolley-diesel prime power is another step in the search to exploit the unused potential of electric wheel driven haulage trucks. The output of the present engine - a 700 horsepower diesel - is not adequate to exploit fully the 1200 horsepower potential of the two electric wheel drive motors. Power was supplied to a modified 100-ton haulage truck through a double wire trolley system. The vehicle was tested with various payloads on a 7% adverse grade haul road. More significant conclusions developed are: Power - Horsepower to propel the vehicle can he more than doubled to improve truck cycle time. Productivity - Trolley power up adverse grades can improve [producivity] rates from 18 to 36%, dependent upon haul road profile.

Jan 1, 1968

By R. Jovanovic

The main technological indicators of copper flotation which determine the level of revenue per mass unit of processed copper are utilization and the content of copper in concentration. This study describes the economic-technological model of copper flotation which can help determine, for the given technological and market conditions, an optimal percentage of copper in concentration, whereby the maximum revenue is achieved per ton of the processed ore in the process of flotation.

Jan 1, 2006

When multiple mines operate in an area there are social, economic and environmental impacts which cumulate over space and time. These impacts require special attention. A collective approach is required to identify, assess and manage them. No assessment of sustainability of mining can be considered complete without accounting for cumulative impacts. This paper proposes a framework and typology to deal with cumulative impacts and tests this in a coal mining area in NSW Australia.

Jan 1, 2007

By M. L. Nave, R. E. Melley

DC motor drives are available technology for belt conveyors. The success of the application in mining depends on adequate and timely consideration of DC drive features. The purpose of this paper is to familiarize and inform possible mining users of DC drive attributes.

Jan 1, 1996

By K. R. Price, M. Gauna

Jim Walter Resources No. 4 mine produces coal through retreat longwall mining at 610 to 670 m (2000 to 2200 ft) of depth. A three entry, total yield pillar, longwall development experimental region was established for three adjacent longwall panels utilizing 6.1 m (20 ft) wide gate section pillars. Presently, the first longwall panel is completed with roadway deformational behavior monitored for a ground control assessment of the mining system. Data illustrate that the total yield pillar gate section design at No. 4 mine is presently comparable to gate section designs having large equal size chain pillars. Ground conditions will continue to be monitored during the mining of subsequent longwall panels in order to determine the ground control implications from multiple panel extraction.

Jan 1, 1986

By Viacheslav Lyakhov, Cornelis H. Iestra, Victor I. Beloborodov, Vitaliy Bogdanovich

The results of a study and effective use of flotation for processing of ores with complex mineral composition containing fine-disseminated minerals with high specific density are presented in the paper. The object of research was complex baddeleyite-containing ore from Kovdor deposit (The Kola peninsula, Russia). Baddeleyite is a valuable, rare mineral, natural Zirconium dioxide with 5.8 - 6.0g / cm density, grade content 0.15 - 0.17 and dissemination less than 0.2 mm. The authors carried out a thorough investigation of baddeleyite- containing products selected in different sites of gravity flowsheet. It was determined that due to similar specific weight some sulphide minerals (pyrite, pyrrhotite) come into concentrate together with baddeleyite and, also, minerals of pyrochlores group (hatchettolite). The results obtained revealed the possibility of use the flotation for retreating rough baddeleyite concentrate. he given gravity concentrate has a number of specific features, e. g. high density of its minerals which, in its turn, provides for high speed of sedimentation of solid phase in pulp, and for the presence of large amount of sulphide minerals (up to 10%) having good flotability. With these features being taken into account a technology for flotation of baddeleyite-containing products after their preliminary gravity concentration has been developed (up to 5 - 10% Zirconium dioxide). The technology has three flotation stages. At the first one the reverse flotation of baddeleyite is carried out during which "light" minerals (forsterite. apatite and carbonites) come into froth product and at the second one flotation of sulphide minerals and at the third one direct flotation of baddeleyite is performed from the underflow product. The following reagents were used for flotation: of phosphate type (sodium tripolyphosphate, mono and diethers of alkylphosphpric acid) and sodium xanthate as collector for sulphides. The given set reagents provides for high effectiveness of flotation due to selective of collectors and presence of froth layer with high carrying ability. New flotation technology of recovering of baddeleyite from complex ore was developed and applied at the Kovdor Mining Plant, using AKER flotation machines.

Jan 1, 1995

By Leo J. Laughlin

In recent years, heavy mining applications have put an increasing demand on conveyor pulleys. This has resulted in the increased usage of turbine pulleys. The designs of these pulleys are often based upon the failures seen in the conventional welded designs, overlooking the interaction of pulley-shaft system components as the profile of the disc is modified. This paper will focus on the development of balanced design philosophy using case studies of turbine pulleys in heavy mining applications, evaluated with FEA.

Jan 1, 2002

By Stephen Utter

One function of mining is to supply oil shale of the required grade and characteristics to surface retorts. The mining methods must he safe, efficient, and environmentally acceptable. Although the Bureau of Mines no longer conducts research on methods of mining fossil fuels, including oil shale, its many years of activity in that field resulted in a significant body of findings. This article summarizes some of these findings, with respect to oil shale mining. The large areal extent of Green River formation oil shales and the diversity of geologic, hydrologic, topographic, and other conditions, preclude the use of any one single mining and waste management technique. Instead, in most instances, methods and equipment will be chosen to meet site-specific conditions. Such methods include conventional surface mining (open-pit and strip), underground mining (room-and-pillar, sublevel stoping, caving) and in situ extraction (true in situ from surface drill holes and modified in situ from underground retorts containing rubblized oil shale). Combination or hybrid systems may prove suitable. Both surface and underground backfilling of spent shale waste may be practiced. Tremendous amounts of oil shale must be mined, processed, and the waste shale properly disposed of in order to meet projected industry production goals. For example, about 1.4 tons of oil shale averaging 117 L of shale oil per ton are required to produce one bbl of oil. A plant with a daily production of 8 dam' (50 000 bbl) of oil would thus require some 68 kt of raw shale daily. This is more than the average daily production from any underground mining operation.

Jan 1, 1981

By Carmel Bofinger, Maureen E. Hassall, David Cliff, Eric Stemn

e Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

By L. G. Austin

Equations are derived to allow for different mean velocities of axial flow for different sizes of particles in fully mixed ball mills. The equations are modified to allow for the exit classification that occurs in grate-discharge autogenous and semiautogenous tumbling mills. An approximate treatment is given that applies for other forms of residence time distribution, provided that the mill contents are close to fully mixed.

Jan 1, 2000

By Timothy J. Orr, Jami M. Girard

A NIOSH study on occupational deaths between 1980 and 1989 indicated that in the United States, mining had the highest average annual fatality rate (3 1.9 per 100,000 workers) of any other major industry. Since "lack of training" was often cited as the primary cause of accidents, NIOSH has been investigating new methods for effective training. One such method is the use of low- cost, desktop computers to simulate a virtual mining environment. Computer-based training offers several advantages over conventional training because the computer programs provide a three- dimensional environment that allows the trainee to practice using evacuation routes, encounter mining hazards, and view mining operations without being exposed to any real danger. One major focus of the project is mine escapeway multiuser training using desktop virtual reality programs. Researchers have imported mine maps into the software for the purpose of practicing actual evacuation routes and procedures. Various scenarios for evacuation can be practiced in a three-dimensional computer simulation of the mine in a disaster situation, complete with smoke, fire, and other dangers. Depending on the trainee's job description (i.e., foreman, shift boss, beltman, etc.), certain tasks need to be performed in addition to navigating primary and/or secondary escape routes. Each scenario allows for individual or team-based training and provides a means to educate mine workers in hazard recognition and hazard avoidance. Using this program, mine workers can practice evacuating various mine layouts without the danger and expense associated with escapeway training in an actual underground mine. Each scenario can be changed to test the trainee's reaction in a variety of circumstances and run many times so the trainee can practice concepts. This training experience will help reinforce the knowledge acquired during more conventional classroom instruction, and the inherent flexibility of the program allows training materials to be tailored to meet the specific requirements of individual mines.

Jan 1, 2002

By Earle J. Klohn

Tailings disposal has rapidly become an area of increasing importance to both existing and planned mining operations. In recognition of the significance of this topic, MINING ENGINEERING is presenting a series of articles on tailings disposal. The first, published in June, outlined some site criteria that influence tailings disposal and some of the design options available to meet these criteria. The following article explores in more detail important design criteria for tailings dams and provides several case study illustrations.

Jan 7, 1981

By N. Dahotre, C. Blue, C. Zhao, B. Parekh, D. Tao, G. Engleman, R. Honaker

Equipment wear is one of the major concerns in screening of coal and minerals. Not only does it decrease the screen service life, it also results in inconsistent aperture sizes and deteriorates the efficiencies of downstream operations. In this research, a coating technique based on laser surface engineering (LSE) was successfully developed to increase the life span of raw coal screens. The microstructure and wear properties of the coating were investigated in this study. Enhanced wear resistance performance (up to 11-fold increase) of coated screens has been achieved in laboratory wear tests.

Jan 1, 2006

By Prasannarao Dontula, Kal V. S. Sastry

Advances are made in the field of mineral processing on a continuing basis both in the industry and the academia. These advances do not always get used fully because of the inherent difficulties in the transfer of knowledge and reduction to practice. In recent years, knowledge engineering is being increasingly employed in other fields to overcome some of these difficulties. This paper presents a vision of how knowledge engineering can be applied to the benefit of the mineral processing industry and includes a discussion of associated principles, techniques, and advantages.

Jan 1, 1993

By Shamsuz Zaman, Barry Hansen

The major development in the evolution of the conventional subaeration flotation machine has been the steady increase in the size of the individual units. In 1950, large machines were of 1.35 m3 (48 ft3) volume capacity. In 1989 the largest volume capacity operating is 85 m3 (3,000 ft3 ) These improvements have enabled the mining industry to operate successfully in the face of declining ore grades and adverse metal prices. This paper describes the design features and performance characteristics of a number of significant flotation machine designs.

Jan 1, 1989

I met Austin Taylor in Vancouver on my way home from my first Pioneer examination. He asked me to examine the unsuccessful old Lorne mine, adjoining and west of the Pioneer. I had no idea that this meeting would lead to one of the outstanding successes and pleasant associations of my career. I knew nothing of Taylor, except that Gen. McRae and associates said that he had been engaged in lumbering and was interested in an oil and gasoline marketing company called Home Oil. But even if the Lorne examination would be only a small one, in the depths of the Depression in 1931, I was glad to have a chance to look at another gold property, so I agreed to visit the Lorne early in August. The start of the trip was not auspicious. I had been working hard on an unproductive study, and was greatly worried by my father's hopeless illness with tuberculosis. To get a little rest on my way north I had arranged to go from Seattle to Vancouver on the night boat that connected with my train. To my surprise, Bill Boultbee, an associate of Taylor, met me at the train in Seattle at 9:30. He said he would drive me to Vancouver, arriving at one In the morning. I was so tired that I begged off and let him take the drive alone Boultbee was most understanding and friendly, but I knew how I would have felt if I had been kind enough to take the long drive to help a stranger and then had been forced to make the return midnight drive alone. I was lucky they did not call off the examination at once. I got a good sleep on the Vancouver boat and Austin Taylor met me at the Hotel Vancouver for breakfast. After a brief talk he took me to the small steamer that made the 4-hr sail up Howe Sound to the village of Squamish. This was the end of the Province-owned Pacific Great Eastern Railway that was eventually to be a shortcut from Vancouver to the Canadian National main line at Prince George. Because

Jan 1, 1976