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By C. W. Overton

The operations of Bethlehem Copper are situated in the south-central interior of British Colombia at an elevation of 4900 feet above sea level. Main road and rail transportation systems pass through Ashcroft in the Thompson Valley, which is 28 miles by road from the minesite. The operation was the first low-grade open-pit porphyry copper mine in British Colombia. The minerals are chiefly chalcopyrite and bornite, while the rock is principally feldspar and quartz. In the outer fringes of the orebodies sane pyrite is present. Average grade of mill feed is 0.55% copper.

Jan 1, 1973

By A. G. Naguib

In essence, any magnetic separator operates on the basis of imparting a preferential magnetic force on particles of higher magnetic susceptibility which are to be separated from particles of lower magnetic susceptibility. A certain amount of directional deviation to the particles takes place thus allowing for collecting each category of particles separately. The forces in action on particles in a wet magnetic separator of the established designs can be analyzed in a simple manner as shown in Figure 1.

Jan 1, 1972

By Haydn H. Murray

The term clay is somewhat ambiguous unless specifically defined, because it is used in three ways: 1) as a diverse group of fine-grained minerals, 2) as a rock term, and 3) as a particle size term. As a rock term, clay is difficult to define because of the wide variety of materials that comprise it; therefore, the definition must be general. Clay is a natural, earthy, fine grained material comprised largely of a group of crystalline minerals known as the clay minerals. These minerals are hydrous silicates comprised mainly of silica, alumina, and water. Several of these minerals also contain appreciable quantities of iron, alkalies, and alkaline earths. Many definitions state that a clay is plastic when wet. Most clay materials do have this property, but some clays are not plastic, e.g., halloysite and flint clay. As a particle size term, clay is used for the category that includes the smallest particles. The maximum size particles in the clay size grade are defined differently on various grade scales. Soil investigators and mineralogists generally use 2 pm. as the maximum size, whereas the widely used scale by Wentworth (1922) defines clay as material finer than approximately 4 pm. Some authorities find it convenient to use the term clay for any fine-grained, natural, earthy, argillaceous material (Grim, 1968). When used this way, the term includes clay, shale, or argillite, and some argillaceous soils. Even though no standard definition of the term clay is accepted by geologists, agronomists, engineers, and others, the term is generally understood by those who use it. Clay is an abundant natural raw material, and it has an amazing variety of uses and properties which will be discussed in this chapter. Clays rank among the leading industrial minerals in both tonnages produced and total value. Their importance is indicated in Table 1, which lists the 1988, 1989, and 1990 productions according to the US Bureau of Mines (Ampian, 1992). As industrial minerals, clays are a complex group that consists of several mineral commodities, each having somewhat different mineralogy, geologic occurrence, technology, and uses. In this section these commodities are organized as follows: 1) bentonite, 2) common clay, 3) hormites, and 4) kaolin. Fuller's earth is discussed in both the bentonite and hormite chapters. Fuller's earth is a term based on use, and both bentonites and hormites are sold as fuller's earth. The overlapping is particularly evident where both bentonite and non-bentonite fuller's earth are used for the same purposes or products, such as in drilling mud, bleaching or clarifying fats and oils, and carriers for insecticides and fertilizers. Kaolin, ball clay, halloysite, and refractory clays are grouped together because they consist mainly of minerals of the kaolin group. Common clay is a grouping of several fine-grained materials, including shale, sometimes referred to as miscellaneous clay. The scientific and technological publications pertaining to clays

Jan 1, 1994

By Robert C. Edmiston

"Further, we search for the veins by observing the hoar-frosts, which whiten all herbage except that growing over the veins, because the veins emit a warm dry exhalation which hinders the freezing of the moisture, for which reasons such plants appear rather wet than whitened by the frost," Georgius Agricola, De Re Metallica, 1556 In view of Agricola's statement, made in 1556, the concept of using the heat released by oxidizing sulfides as an ore guide can hardly be considered a product of twentieth-century technology. In fact, thermal exploration has received relatively little attention in modern times compared to other potential field geophysical methods. There have evolved, however, two basic approaches to thermal exploration for subsurface heat sources. These are 1) the measurement of surface temperatures by infrared, thermal imagery and 2) the measurement of geothermal gradients in exploratory drill holes.

Jan 1, 1974

By Kenneth J. Reid

The application of computers for control purposes in hydrometallurgical processes is not as well-established as in mineral processing plants. This is not only due to the comparatively new development of large-scale application of hydrometallurgy and the relatively small number of operating plants, but also due to some of the basic dynamic characteristics of hydro- metallurgical processes., Basically there is little difference in the development and application of digital control techniques in hydrometallurgical plants from those techniques widely in use throughout the chemical process industry and in nonslurry applications; particularly for those cases involving liquid streams only, the primary sensing elements are essentially the same. On-stream X-ray fluorescence analysis is a well-established method for determination of metal content in the process streams, and standard equipment is used for the measurement and control of pH, flow, density, temperature, pressure, and other variables. Nevertheless, the high proportion of corrosive slurry streams at elevated temperature and pressure poses a challenge to the instrument engineer concerned with developing long-life, reliable instrumentation. One major difference and potential problem area in developing control systems for hydro- metallurgical processes is related to the very long time constants which are common in the larger plant. In these circumstances, it is important to define the overall control objectives very carefully and be prepared to allow for considerable drift in intermediate variables. In larger projects with many control loops the general advantage of lower costs compared to conventional analog instrumentation can be confidently expected. Also in most cases, the process analysis necessary to design and specify a comprehensive computer control system and the increased operator involvement in implementing digital control systems yield additional benefits due to the increased understanding of the dynamic characteristics of the process.

Jan 1, 1979

By William R. Bond

The pressure/vacuum lysimeter is being used as an effective vadose zone monitoring device for mining heap leach facilities, tailing disposal ponds and tailing waste sites. Their use has proven reliable for baseline data collection, early warning leakage detection and analyzing geochemical variations in the vadose zone. The lysimeter structure utilizes a closed cylindrical chamber made of PVC or inert material. The soil water intake portion of the cylinder is made of a porous material of low permeability. The application of vacuum or pressure to the unit is via two access tubes from the ground surface. Available soil moisture is drawn by vacuum through porous material into the lysimeter chamber and then collected from the access tubes. Case studies show their usefulness for monitoring around a uranium tailing pond constructed in glacial till material, under heap leach pads and pregnant, barren, and overflow ponds, and investigating the movement of contaminant moisture through old tailing deposits. Relatively easy to install and sample, regulatory agencies and facility operators are accepting and negotiating for their application as a site integrity monitoring device and unsaturated zone research tool. Their use at heap leach facilities lends credibility to solution balance calculations when considering a leachate loss of 5 or 10 percent can make or break a mine's profitability.

Jan 1, 1984

By Ernest Y. Baafi

This paper describes the results of a series of comparative studies in which polygonal, IDS, and kriging were compared for their local estimation accuracy. The specific objective of this study was to determine the impact that the particular nature of the mineralization has on the results of such comparative studies. The study was performed on simulated coal deposits and the evaluation parameter chosen was the coal thickness. For this study, many conditionally simulated deposits having different degrees of seam thickness continuity were first developed. Each simulated deposit covered an area of 30,000 ft x 30,000 ft which was, in turn, subdivided into 100 mine planning blocks of 3,000 ft x 3,000 ft in size. Thickness estimation was made for these mine planning blocks using surrounding DDH assays. In all cases tested, e.g., from a perfect continuity to a complete lack of continuity in coal seam thickness, kriging gave the best estimates among the three, followed by IDS and polygonal methods. As expected, the relative efficiency (i.e., superiority) of kriging over other estimators was highly dependent on the nature of mineralization.

Jan 1, 1982

By C. Cho

One problem with the application of neural networks to the multivariable control of mineral and extractive processing is deciding whether and how best to use them. The objective was to compare neural network control to more conventional strategies and find any advantages in terms of set point tracking, rise time, settling time, disturbance rejection, and other criteria. The procedure was to develop neural network controllers using both historic plant data and simulation models. We tried various neural network control patterns including both inverse and direct neural network plant models. These were compared to state space controllers that were, by nature, linear. For grinding and leaching circuits, a nonlinear neural network-based model predictive control strategy was superior to a state space-based linear quadratic Gaussian controller. We also learned the importance of incorporating state space into neural networks by making them recurrent--feeding certain output state variables into input nodes in the neural network. We concluded that neural network controllers can have better disturbance rejection, set point tracking, rise time, settling time, lower set point overshoot, and can be more foolproof and easy to implement in complex, multivariable plants.

Jan 1, 1996

By R. A. MacGregor

The Stanreck mine of Stanreck Uranium Mines Limited in located on Quirks Lake in the Elliot lake - Blind River area of Northern Ontario. It is approximately 25 miles north of the north shore of Lake Huron, equidistant between the cities of Sudbury and Sault Ste. Marie. The property was developed ad brought into production at a rate of 3,000 tens of ore/day during the uranium boom of the mid 1950's. By 1960 mine waters were becoming quite acid through the activity of bacteria. Treatment of this water was begun for pollution control and a small amount of uranium which had been leached from the ore by these acid waters was recovered. Development of bacterial leaching with a view to increasing production by this method commenced in December 1962. Subsequently, it was succeesfull in producing 10,000 - 15,000 lbs. of U308/month. Since late 1964 uranium production has been obtained solely from bacterial leaching. A rare earth concentrate was also made for its yttrium content during 1966 and 1967. This paper describes the development, operation and methods used in the underground bacterial leaching process.

Jan 1, 1969

By V. I. Lakshmanan

Crystalline Flake Graphite is a strategic mineral. Since 1954 nearly all North American consumption has been imported from offshore. The Bouthillier Project in Quebec, Canada, is Orrwell Energy's bid to enter the market. Milling of flake graphite is considered easy, yet more problems have been encountered in flowsheet and plant design than in most other minerals. A fresh approach to existing technology was taken, giving results that are highly satisfactory. The key to graphite liberation without flake deterioration is found to be in autogenous grinding. In addition to producing marketable coarse graphite by such autogenous grinding, flotation and tabling, super purity fines can be produced using repeated regrinding, elutriation and flotation. This paper discusses the design of a 500 TPD plant based upon the results obtained from bench and pilot plant studies.

Jan 1, 1984

By B. Basim

Novel chemicals that can be used for increasing the efficiency of fine coal dewatering were developed at Virginia Tech. Reagent A was tested on three different coal samples in laboratory vacuum filtration tests. These included flotation products from Middle Fork plant, Elkview Mining Company, and CONSOL, Inc. The tests conducted with the Middle Fork coal sample (100 mesh x 0) showed that cake moisture can be reduced by more than 10% beyond what can be achieved without using dewatering aid. This improvement was achieved at 1 lb/ton of Reagent A and 0.1 inch cake thickness. At 0.5 inches of cake thickness, the improvement was limited to 8% at the same reagent dosage. The results obtained with the Elkview coal (28 mesh x 0) showed similar advantages in using the novel dewatering aid. Depending on the reagent dosage, cake thickness, drying cycle time and temperature, it was possible to reduce the cake moisture to 12 to 14% range. In addition to achieving lower cake moisture, the use of Reagent A substantially decreased the cake formation time, indicating that the reagent improves the kinetics of dewatering. The test results obtained with CON SOL coal were not as good as with the other coals tested in the present work, which may be attributed to possible oxidation and/or contamination.

Jan 1, 1998

By Haydn H. Murray

Kaolin is an important industrial mineral because it exhibits desirable properties in many applications and because of its relatively low cost, Approximately 2,000,000 tons of kaolin from Georgia and South Carolina are processed and used commercially in the United States each year. Strictly defined, the name kaolin is applied to a group of hydrous aluminum silicates of which the mineral kaolinite is the most common. Kaolinite has such desirable properties as natural whiteness, chernical stability, non- abrasiveness, and very fine particle size. Kaolinite particles are characteristically thin, flat, and hexagonal in outline. The particles range in size from submicron to as much as 40 microns (equivalent spherical diameter). In addition to the general properties mentioned in the first paragraph, it is soft, has low viscosity at high solids content in many systems, is readily wet and dispersed in water and some organic systems, and can be produced with a controlled particle size distribution. Some of the important physical constants of kaolin are: specific gravity, 2.60; index of refraction, 1.56; hardness (Mohs scale), 2; fusion temperature, 1850°C; dry brightness, 78-92 percent.1

Jan 1, 1965

By T. W. West

INTRODUCTION This paper presents an assessment of conventional flotation technology. In addition it presents some ideas which can be used to change the perception of what may be done with conventional flotation equipment to maximize its efficiency. Perspective of Conventional Flotation Technology 1. Flotation in many coal preparation plants is defined as something between a necessary evil and a non-viable concept because: -Too much art is required on a continuous basis to achieve uniformly acceptable results. -It is expensive, the capital cost in dollars per ton of circuit feed for flotation and dewatering is high. -It is a difficult process to use when SO2 reduction governs system design and equipment selection. -It creates a product (fine coal froth) that is difficult to dewater in the presence of BTU/lb as-received pressures. -It is a difficult process to control from a management standpoint, there are no dependable set points to rely on. 2. Many froth cell circuits are 0.5m x 0 (nominal 28 M x 0) feed which is sourced from screen/cyclone underflows. The original intent was to obtain maximum yield at acceptable product quality and moisture using disc filters. (See Figure #1) 3. An alternate to conventional flotation and its perceived to be limits of efficiency, capital costs, etc. is to move towards such developing flotation technologies as column flotation, reverse flotation, and microbubbles. A lot of work is being done to move these concepts thru pilot stages into full scale, commercial plant operation. The majority of the coal producers and coal preparation plant designers view these concepts as being in the development/pilot plant stages. OBJECTIVES Based on the preceeding comments of the perspectives of the coal producers and plant designers, the options are limited. They can make do with what they have available to them in the way of industry standard equipment and practices or they can move forward with developing technology. I feel there is a third option: what can we really do today with what is available to us, without reinventing the wheel? APPROACH 1. When processing coal against ash and SO2 restrictions, the fine clean coal stream can be the best stream on the clean coal conveyor due to the release by size and the ability to create a high BTU/low sulfur (dry basis) product. 2. Targets: -Consistent raw coal size consist in the plant feed . -Do not put pyrites in the froth cells. -Adjust criteria defining good flotation away from yield towards maximum BTU recovery at minimum ash. -Limit the froth cell feed size consist to 0.15 mm x 0 (nominal 100M x 0). -Establish and maintain a correct, consistent percent solids in the froth cell feed. -Select flotation reagents with care. -Introduce reagents in the proper sequence.

Jan 1, 1988

By M. R. Grundy

The Robinson project is based on the porphyry copper and gold deposits in the Robinson Mining District, near Ely in Eastern Nevada. The district was mined from the late nineteenth century to 1978 by Kennecott Copper Corporation and its predecessors. Operations ceased when falling copper prices in the late 1970's made their outdated mill and smelter complex at McGill uneconomical. In October 1991, Magma Copper Company (Magma) acquired the many claims that cover the known porphyry copper deposits in the district These occupy a disturbed area about nine miles long and three miles wide between the towns of Ely and Ruth. Magma proposes to build a copper / gold mine and concentrator and expand the existing gold leaching facilities. Several pits, previously mined by Kennecott Copper Corporation, will be enlarged; the use of larger, more modem equipment will result in higher productivity and lower operating costs in general. ICF Kaiser Engineers, of Oakland, California, were awarded the con-tract for detailed design of the process facilities, which was essentially complete by the end of 1993. The project at present is awaiting completion of the environmental permitting process; state air and water permits are in hand, and the Bureau of Land Management's (BLM) current schedule indicates that the final obstacles to construction will be cleared by early fall of this year.

Jan 1, 1994

By III Kimball

For many years, Arizona merely shadowed EPA's environ-mental regulation of mining operations and waste. During this period, Arizona generally assisted EPA in the implementation of federal programs and enacted environmental laws patterned closely after their federal counterparts. A growing public concern about protecting water quality, particularly groundwater quality, eventually caused the State to depart from this pattern.

Jan 1, 1989

By Felicia F. Peng

Two modes of collector addition techniques are applied in the column flotation for cleaning ultra fine coal. The collector can be: 1) added directly into the coal slurry through the feed system; and 2) gasified collector and transported in the gas phase through the bubbles. Operating parameters of the column flotation were investigated through three phases of work plans for Pittsburgh No.8 seam coal. In present study, the column flotation using two modes of collector addition techniques were tested and compared. Ninety percent or higher combustible recovery can be achieved by using both methods. However, utilizing the gasified collector addition technique in column flotation has more potential than direct liquid addition technique to obtain the higher recovery at same collector dosage.

Jan 1, 1993

By D. B. Dreisinger, H. J. Sohn, J. S. Sohn, G. A. Kordosky

The transport of lithium through a supported liquid membrane was studied with a mixture of D2EHPA and TBP in kerosene as a mobile carrier. In the flat- sheet supported liquid membrane(SLM) system, experiments were carried out to investigate the effects of concentration of mobile carriers in the membrane solution, hydrogen ion in the feed solution, and temperature on the transport of lithium. Experimental results agreed well with a transport model for permeating lithium across the liquid membrane. The permeation rates of lithium can be explained in terms of diffusion of a Li-complex through the membrane phase. For a practical application of an SLM method, a hollow fiber module has been used and lithium can be concentrated more than three times in 24 hours.

Jan 1, 1993

By John R. Marks

In April 1990, the Homestake Gold Mine embarked on a five year, $US 23 million underground drifting and drilling program to explore promising ore targets north of the current mine. This paper describes the ventilation and air-conditioning system that was installed for the 4m x 4m x 5.2 km (ultimately) drift, which is being driven at about 8m per day in 48OC (118.5 F) crystalline rock. Design parameters are described first. Differences in South African, Canadian and U.S. drift ventilation and civil tunneling techniques proved interesting. Details are then given on equipment selection, installation and performance. Costs are included. Special note is made of safety considerations for a long, dead-end drift.

Jan 1, 1991

By A. M. Johnson, D. H. Carlson, D. L. Johnson, S. T. Bagley

A biologically assisted ferric iron leaching system was evaluated for in situ recovery of three copper sulfide oresfrorm northern Michigan. Laboratory scale bacterially assisted ferric sulfate leaching tests were run on the three ores. A T. ferrooxidans strain was found that could be adapted to copper in solutions at concentrations as high as 20 g/L. Column leaching of 4.5 to 2 mm (-4 +I0 mesh) material yielded extractions of 80-90% copper from one ore and 70 and 60% from the other ores. The highest copper extractions were from the Mount Bohemia ore deposits located in the Keweenaw Peninsula, which have fracture controlled chalcocite mineralization. The Bohemia ores are apparently well-suited for in situ solution mining.

Jan 1, 1987

By Risto Lindsberg

A wide concept of flotation equipment and technologies is presented in this paper. The basis for the presentation in Outokumpu's world-wide experience in mineral processing and other related areas, and continuing research and development work done in Finland as well as abroad by Outokumpu's subsidiaries (and customers). It is understood that flotation equipment selection for a certain process stage is becoming more complicated. It is obvious that flotation equipment in grinding circuit needs different design from a multistage cleaning process. In this paper, column flotation is compared with other flotation methods. Thus three areas of flotation are discussed in this paper: 1. Flotation in the grinding circuit, Skim-Air machines 2. Rougher-scavenger flotation, conventional cells vs columns 3. Cleaning flotation, columns

Jan 1, 1988