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By R. M. Board

This paper will focus on measurement and control of four main aspects of crushing, namely horsepower, bowl level, mantle position and feed rate, and will discuss related sensors and control techniques, some of them designed specifically for crusher control, that have proven successful and reliable in many installations.

Jan 1, 1982

By John De La Vergne, Morri Medd

"This paper describes the sinking of a circular concrete ventilation shaft through 110feet of water-bearing overburden. The brine circulation freezing method was used to stabilize the walls during excavation. In order to take advantage of the cold winter weather, a custom-built heat exchanger (natural radiator) was installed in place of the standard mechanical refrigeration plant.IntroductionIn the late fall of 1979, Les Mines Selbaie awarded a contract to the firm of 1.S. Redpath Limited to sink a ventilation shaft on its property in northwestern Quebec. The shaft was to be sunk through 110 feet of water-bearing overburden and approximately 90 feet of rock to a final depth of 200 feet below surface. The water table was measured at 16 feet below the surface elevation.After examining the soils report and diamond drill core from the shaft area, Redpath came to the conclusion that freezing was the best way to stabilize the overburden for sinking. LocationThe mine site is 420 statute miles due north of Toronto, just east of the Ontario/Quebec border (Fig. 1). Access to the site is provided by a development road built by the Quebec government from the Matagami/lames Bay Highway. History of Ground Freezing In the Mining IndustryIn 1862, shortly after the development of mechanical refrigeration, a mine shaft was sunk through an artificially frozen water-bearing formation in the United Kingdom. The first application of ground freezing in North America was for a Michigan iron ore shaft in 1888. Since that time, the freezing method has been used to sink hundreds of shafts throughout the world. Its best known application was to sink sixteen shafts through the Blairmore Formation in Saskatchewan.The same method has been used in every case. It involves chilling a calcium chloride brine solution and circulating the brine in concentric pipes, spaced between 3 and 6 feet around the shaft perimeter and usually 4 to 5 feet from the limits of the proposed shaft excavation."

Jan 1, 1982

By W. E. Lamont

The Bureau of Mines studied the potential for recovering marketable barite concentrates that meet oil well drilling-mud specifications from barite waste pond materials. The study was conducted as part of the Bureau's research program to conserve domestic mineral resources by advancing mineral recycling technology. The samples, which were obtained from Georgia, Nevada, Missouri, and Illinois, varied widely in character, particle size, and barite content. The samples were treated with sodium silicate and sodium cetyl-stearyl sulfate and then floated. The flotation flow sheet was modified to reject barren coarse and/or slime fractions from some of the samples, and one feed sample had to be scrubbed prior to flotation to remove residual flotation reagents. The cleaned concentrates had BaS04 contents ranging from 95.0 to 96.9 percent, while recovering 81.2 to 95.9 percent of the barite in the feed. The specific gravity of each concentrate exceeded the specification of 4.2. The removal of the flotation reagents from the flotation concentrate was not investigated.

Jan 1, 1982

By M. Katzer, R. Klimpel, J. Sewell

The effect of using selective dispersants as wet grinding aids for ores is demonstrated on laboratory scale batch and continuous grinding equipment. A complete characterization of behavior is performed on a given ore to demonstrate correlations involving torque, % solids, net production rate, and slurry weight and volume loading. The relationship between such laboratory data and industrial scale testing results is very consistent.

Jan 1, 1982

By Larry D. Nichols

Poroplastic membranes containing ion exchange liquids were studied for separating cobalt from nickel-containing solutions similar to ammoniacal laterite leaches. The driving force for cobalt transport was differences in pH and composition between the leach and extraction streams. Using a diketone ion exchange liquid, a leach pH of 6.5 to 7.0, and a strip pH of 2.3, cobalt was extracted from a 750 ppm solution containing 2500 ppm of nickel at rates ranging from 1 to 10 µg/cm2 .min in single membrane cells, and from 10 to 100 in more closely spaced multiple membrane cells. Rates were variable, with evidence that cross -membrane flow pasterns were a key factor; a reproducible rate of 30 pg/cm .min would be economically viable. Loss of transport observed after several days of continuous operation was restored by flushing membranes with fresh ion exchange liquid. A major effort was devoted to preparation of thin, leak-free membranes; the resulting membranes endured operating conditions without mechanical failure.

Jan 1, 1982

By D. J. Barrett, M. A. Sochocky

INTRODUCTION Summary of Factors Influencing Comminution Circuit Design The selection of an appropriate comminution circuit for a specific ore is one of the most important decisions in the design of a processing plant. The importance is related to the fact that the capital and operating costs for crushing and grinding plant generally represent, as is well known, the major portion of the plant costs. This chapter will, therefore, identify as many as possible of the factors which influence the selection of a comminution circuit. The number of factors which will have to be considered for any comminution project will depend, among other things, on the type of project. If, for example, the project is an entirely new mining development, then most, if not all, the factors identified will have to be analyzed. If the project is an expansion of a developed mining operation or if the new orebody is adjacent to a viable operation, then the existing operation will influence the choice of factors or design constraints which need to be considered. The existing infrastructure or supporting systems may be quite adequate to accommodate the requirements of any expansion or new development. Hence, those factors may not have to be considered. To cover, however, the widest spectrum of projects, the factors which have been identified in this chapter are those which will have to be considered for the most complex of projects, that of developing an entirely new mining operation. The range of factors is as broad as the range of different ore types. Thus, each development must be treated with individualized care. The most important step in the development is the analysis and understanding of the ore characteristics. The hardness of the ore, its abrasiveness, friability, moisture content, grade, mineralization including gangue mineralization, liberation size, chemistry, and other characteristics should be the first to be analyzed in the investigation. The next should be the determination of factors such as plant size, throughput, location, climate, accessibility, and availability of water. The selection of samples for initial bench scale work and bulk sampling (when needed) for further

Jan 1, 1982

By S. V. Krishnan

In the upgrading of finely-disseminated iron ores, selective desliming is the critical step which must be controlled in order to achieve efficient flotation. A prerequisite for selective desliming is a properly-dispersed pulp; sodium silicate is commonly used as a dispersant. The mechanism by which sodium silicate acts as a dispersant in the presence of calcium ions was examined by streaming potential measurements, settling tests, abstraction density determinations, selective flocculation tests and scanning electron microscope observations. The study established that calcium silicate precipitates on the mineral surfaces dispersed the pulp. Although sodium silicate was a nonselective dispersant, the addition of corn starch aided the flocculation of goethite over quartz at low silicate additions, but became ineffective at higher silicate levels. A model is presented to explain the dispersant mechanism of sodium silicate in the presence of calcium ion for selective flocculation of iron ores.

Jan 1, 1982

By James H. Boettcher

Inflation and increasingly complex tax laws in the United States combined with rising national ism overseas have made the structuring of viable financing plans which meet the requirements of the various parties involved equally important in determining project success as the design of an efficient mining plan or selection of the optimal size equipment. Whereas the use of computerized analysis to design and evaluate the technical parameters of resource ventures is well accepted, computerized evaluation of the investment criteria (qualitative and quantitative) of the various parties to the project (mining firm, financial institution, product buyer, host government, etc.) is a more recent application which can make a material impact in strengthening project economics. By identifying the objectives of the parties and critically evaluating and testing them with the technical and economic/financial constraints on the project the sponsors can design a financial structure tailored to the attributes of the deposit. A myriad of new financial techniques have evolved for financing natural resource ventures, from "Commodity-backed bonds" to tax based limited partner- ships, but in every case the structure of the financing mechanism depends on carefully matching the parameters of the financial structure with the economic characteristics of the project and the objectives of its sponsors. This presentation outlines a methodlogy for computer based project evaluation in the design and structuring of stronger financial plans for natural resource ventures.

Jan 1, 1982

By D. M. Thayer, P. B. Linkson

High intensity wet magnetic separation methods have received much attention in the search for alternative and effective methods to treat weakly magnetic minerals. This paper examines the incorporation of such techniques in the beneficiation of a non-sliming specular Michigan Hematite. The dependence of separation efficiency and beneficiation of specular hematite on various parameters controlling the operation of such a device is investigated experimentally. Particular attention is focused on particle size limitations imposed in these separations. In light of these data, metallurgical balances are presented and an attempt made to rationalize the various models suggested in the literature.

Jan 1, 1982

By A. N. Brown

The importance of the minerals industry in the economy of the country is discussed, and the tremendous changes that have taken place over the past two decades, including the widespread application of computers and the use of mechanization, are outlined. A discussion of the future of the minerals industry points out that, with the rise in the price of gold, the life of the gold-mining industry can be expected to extend beyond that previously predicted, and that the demand for uranium, which has been depressed, is uncertain. As a result of the oil crisis, the demand for coal has increased and large expansion programmes are planned. These involve coal exports and the use of coal for the generation of electric power, for the production of liquid fuels, and for the smelting of metals. Technical challenges face engineers in every avenue of the minerals industry: in deep gold mines, underground coal mines, strip coal mines, and open-pit mines. Studies indicate that only one-third of the demand for trained mining and metallurgical engineers is being met and that the position is worsening. However, there are indications that the industry is succeeding in attracting more engineering students, and the supply is expected to improve. These efforts should be co-ordinated, expanded, and intensified. There is a need to ensure that sufficient teaching staff of the right calibre and experience are attracted to universities and technikons. The first degree course is comprehensive and basic, and specialization through post-graduate study should be encouraged. The influence of national service on the education and training of engineers is discussed.

Jan 1, 1982

To develop and design a bit that will rapidly drill smooth and precise instrumentation holes in soft rock. Approach Use a one-piece bit made by combining a drag bit and a diamond bit. Because a smooth-walled borehole with a precise diameter is needed for borehole pressure cells (BPC) and other borehole instruments, a diamond bit is usually used. However, diamond bit drilling is slow, and the bit will tend to bind when squeezing ground is encountered. On the other hand, the drag bit will cut faster, but the walls of the drill hole will be rough and the diameter will not be as precise. The combination will provide a bit which penetrates as rapidly as a drag bit, but retains the smooth-wall and precise borehole diameter of a diamond bit. How It Works A three-foot-length of EW-size drill rod is centered in a diamond bit by welding it to three equally-positioned spacers at each end of the bit. A drag bit is attached to the EW rod with a standard EW-to-drag bit adapter as shown in the diagram. Three equally-spaced diamond inserts are set to the desired hole size and welded to the diamond bit barrel behind the crown. These inserts increase the smoothness and precision of the hole by cut-ting away any hole closure. Three equally-spaced shims are set approximately 0.020-inch under the overall insert diameter size and welded to the rear of the diamond bit barrel. The combination bit should be used on a diamond drill with either water, mist or air as the coolant.

Jan 1, 1982

By Robert W. Zimmerman

POROUS SOLID COMPRESSIBILITIES There are four different compressibilities associated with porous solids, each relating the fractional change in either bulk volume or pore volume with the change in either pore pressure or confining pressure. These will be referred to as Cbc, Cbp, Cpc, and Cpp, with the first subscript denoting the relevant volume, and the second subscript denoting the relevant pressure. They are defined as: [ ] Note that minus signs are included in two of the definitions so that each of the compressibilities will always have a positive value. In general, each compressibility depends on the elastic moduli of the matrix material, the porosity, and the exact geometry of the pores. Taking the latter factor into account calls for separate analysis for each different pore shape, which of course can only be attempted for a few relatively simple cases. But lower bounds for each of the four compressibilities can be found, independant of pore structure, in terms of only the porosity (0) and the elastic moduli of the matrix material (any pair chosen from K, E, G and V). The first step is to find relationships between the four compressibilities, starting with the following observation: If a porous solid made of a linear elastic, isotropic and homogeneous matrix material is subjected to uniform hydrostatic pressure of magnitude P on its external and all of its internal (pore) surfaces, the state of stress in the solid will be exactly the same as that which would occur

Jan 1, 1982

On April 1, 1982, the Bureau of Mines and the Department of Energy entered into an Interagency Agreement to develop an enhanced computer cost model for uranium in situ leach mining. The original computer cost model contained data base information related to two regions; the Wyoming basin region and the South Texas trend area. The enhanced cost model contains additional information on San Juan Basin type deposits. This addition is significant because it expands the model's capabilites to include one of the largest uranium producing areas in the United States and developes costs related to uranium production from in situ leach mining. The data base was expanded and modified to include changes necessary for San Juan basin type deposits. These changes included, but were not limited to, state and local taxes, royalty payments, depth of deposits, drilling costs, and electrical costs. Also site visits were taken to verify many of the base case parameters. Consequently, the data base has been incorporated into the computer program and existing software was modified to provide for the additional data. Information was obtained on drilling coats and therefore the current program more accurately reflects these costs to depths of 2500 feet. This depth parameter has been expanded to include Wyoming Basin and South Texas scenarios also. Verbal communications were held with one operator in the Crownpoint, New Mexico area as well as the state regulatory agencies to help validate the expanded model. As a result of these changes, several tables have been included, summarizing changes in the new default parameters and the overall range of input parameters.

Jan 1, 1982

By Thomas D. Boyce

Minewater from many western U.S. uranium mines often contains radioisotopes in concentrations higher than permissible for discharge to unrestricted areas. .Radium 226 has the lowest permissible concentrations of all radioisotopes and usually greatly exceeds this limit in untreated effluents. This radionuclide is derived from the natural radioactive decay of uranium: [ ] The treating of minewater effluents has been studied previously (1) and the classical removal method for radium has been adsorption on barytes or freshly precipitated barium sulfate. This paper describes the removal of radium from minewater by utilizing a selective complexer based on a crosslinked organic polymer matrix.

Jan 1, 1982

By Walter E. Dean

Deep-sea manganese nodules are considered to be potential ores of manganese, nickel, cobalt, and copper. Considerable time, effort, and funds have been applied to the study of Se distribution of nodules on the sea floor and the location of economically important areas, but little effort has been spent in understanding the origin of nodules. Most theories that have been proposed to explain the origin of manganese nodules have been based on inorganic physicochemical processes. It is not by coincidence, however, that the area considered to be most economically feasible is in the zone of high biological productivity in the eastern equatorial Pacific Ocean and underlain by siliceous biogenic sediment. The genesis of manganese nodules and the concentration of many trace elements are intimately associated with biological processes.

Jan 1, 1982

By M. L. Jeremic

Mining practice and underground studies show that, besides mining stresses, lateral tectonic stress also influences roadway stability. Roadways perpendicular to the direction of major lateral stress experience the majority of roof falls, accelerated floor heave, and extrusion of coal ribs into openings. They have the most severe deformations and their maintenance is difficult. Roadways parallel to the major lateral stress exhibit roof sagging and bed separation, moderate though sometimes uneven floor heave, and slabbing of coal ribs into openings. Roadways oblique to lateral stress have, to a certain degree, self-supporting roofs, uniform floor heave, and limited sloughing of coal ribs into openings. The optimal orientation of roadways is, therefore, oblique to the lateral stress direction with fewer crosscuts between them.

Jan 1, 1982

By R. Guest

Reichert cone concentrators are used successfully in many applications, but have as yet not found favour in the gold mining industry on the Witwatersrand, because, for optimum operation, the cones need to have specially designed feed-preparation and circuit details. In addition, good liberation of the valuable minerals is essential. Gravity tests, in which a pilot plant was used on refractory gold ore, showed that 94 per cent of the gold could be extracted after gravity concentration and preferential grinding, roasting, and cyanidation of the concentrate, whereas 96 per cent could be extracted by flotation followed by the same preferential treatment. However, the capital and operating costs for gravity separation are expected to be considerably lower than those for flotation.

Jan 1, 1982

The carbon-in-pulp (CIP) process is now well established in the South African gold industry, with a total of over I million metric tons of material being treated each month in six large plants. This tonnage is derived from ground ore, from filtered pulp, from calcine, and from reclaimed sand-tailings dumps. With this new process and the new large plants, those concerned with CIP are experiencing a learning process, since each new plant presents a different set of problems to be overcome. The knowledge and experience gained from these plants is being shared, and will be of benefit in the design and operation of new plants. The CIP process can be subdivided into the following unit operations: prescreening at a fine size, adsorption, acid-washing and elution, reactivation, and electrowinning. Results concerning each of these unit operations, which were obtained from pilot plants and from large-scale CIP plants in South Africa, are presented. The latest developments in each of these areas is summarized. Tables that are included as an appendix contain some information concerning the equipment in these new CIP plants plus operating results from some plants.

Jan 1, 1982

By Anil Mahyera

Towards the goal of achieving uniform-high-tensions in roofbolts to provide superior roof support[1-7] for extended periods, Terra Tek installed mechanical-anchor bolts in a mine in eight different ways -- under torque/thrust control with and without hardened washers, belleville washers and tension equalization; in a conventional manner with and without a hardened washer. The various bolt groups were analyzed in terms of their tension uniformity and mean tension levels. Installing the bolts accurately with ? a hardened washer under the bolthead, and ? proper torque/thrust control resulted in the mast uniformly tensioned bolts -- with a coefficient of variation of only 14%, an improvement of 3 times over a conventional installation. Also, these bolts maintained a high tension level -- 80% of the installation tension, compared to 50% achieved conventionally.

Jan 1, 1982

By Terry J. Close

The Anaconda Pintlar Wilderness has a significant mineral resource potential. Five deposits have resources totaling about 180,300 tons (163,600 t) containing silver, copper, lead, gold, and zinc. Another 11, not sufficiently exposed to allow resource estimates, may have additional mineral potential. No placer deposits are indicated. There is little potential for the production of sand, gravel, or stone; alternate sources are closer to markets. No oil, gas, uranium, or geothermal energy sources are known to be present.

Jan 1, 1982