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By A. Iordanidis

Mining activities have recently been taken place in Vourinos mountain, northern Greece, exploiting the so-called ?olivinite?. A representative sample was collected from this mining area. Mineralogical analysis was conducted using X-Ray powder Diffraction (XRD). A thin section was prepared and analyzed under optical microscope. X-Ray Fluorescence (XRF) was employed for the chemical analyses of major, mi-nor and trace elements. Environmental Scanning Electron Microscopy coupled with energy dispersive x-ray analysis system (ESEM-EDX) was also applied for the characterization of the sample. Forsterite (Mg-rich olivine) and enstatite (Mg-rich orthopyroxene) were the main mineral phases determined by XRD, with a 56% and 44% content respectively. Trace amounts of chromite spinels were also determined. Based on this characterization, the industrial rock proved to be a hartzburgite (a type of peridotite in petrological terms). Optical microscopy and ESEM-EDX provided similar observations and confirmed the above-mentioned results. XRF revealed a composition of 43.31 MgO, 44.25 SiO2, 9.98 Fe2O3, 1.40 CaO, 0.67 Al2O3, 0.22 MnO, 0.01 TiO2 and negligible amount of LOI (<0.1%). Trace elements with high concentrations were Cr (2678 ppm) and Ni (2044 ppm). The comprehensive characterization of this mining product suggested the suitability for various uses, such as refractories, foundry and slag conditioner. Additional experiments are being carried out for environmental applications, e.g. wastewater treatment.

Jan 1, 2006

By W. Kemp Wait

Electronic ore sorting is a coarse particle beneliciating process which performs a function which in the past was primarily achieved through the use of hand picking belts. Photometric ore sorting is capable of separating waste from mineral bearing rock having a distinct difference in surface light reflectance levels. This type of ore sorter can be applied to gold and silver ores which are contained in quartz veining. Photometric ore sorting has been used at gold mines in South Africa as well as the Black Pinc silver mine in Montana. A new ore sorter has recently been developed with precious metal ores in mind. This ore sorter is capable of sorting ores on both photometric and conductivity sensing parameters. The first production machine has been installed at a gold mine near Beardmore, Ontario and currently is being used to process low grade waste dumps.

Jan 1, 1998

By Y. Topkaya, R. E. Johnson, D. Buttinelli, B. R. Palmer, A. Geveci, L. Stoppa, C. Lupi, F. Pochetti

Representative samples of a composite mixture of three typical Cu/Zn complex sulphide ores, namely Black-, Yellow- and Altered-ore, from the Cayeli deposit in Turkey, were used for leaching tests in 2.2 M FeCl3, or 1 M CuC12-2 M NaCl solution in the temperature range from 313 K to 363 K (40O to 90O C), with and without the presence of an organic solvent for elemental sulphur, such as CCl4. The leaching rates of copper and zinc were quite high, as expected, in FeCl3 solution and complete recovery of both metals was obtained at the highest temperature when the solvent was present. However in CuC1, solution, extraction yields of the order of 95% only for Cu and Zn were achieved and the positive effect of the solvent was not clearly shown. The kinetics curves of Cu leaching by FeCl3 indicated a model of reaction rate depending on the particle surface, as in a chemically controlled reaction, in tests with the presence of CCl4. Without the solvent, or in CuCl2 media, the model of the diffusion controlled reaction seemed to prevail. Values of apparent activation energy, in both of the leaching processes, were determined and compared with those reported in literature.

Jan 1, 1993

By W. L. Wilson

This article could be entitled "The Rediscovery of the Windfall Mine," since it was originally discovered early in this century. The "Rediscovery" was made by personnel of Idaho Mining Corp. during the course of an investigation of the Windfall mine beginning in 1967. There had been historic production from the Windfall mine sporadically from 1908 until 1951 and there was present during much of this time a mill that vat leached crushed ore. Mining was underground to a depth of 91 m (300 ft). Prior to Idaho&apos;s activities, the mine had been inactive since the early 1950s. Idaho Mining Corp. was an "exploration company," privately owned and based in Reno, NV. The writer was at that time manager of exploration for Idaho Mining. The company held interests in the Cortez Gold mine, then being readied for production, and had conducted exploration for various mineral commodities in Nevada for several years. Idaho&apos;s attention was first directed to the Windfall mine in the Eureka District, Eureka County, Nevada (see Fig. 1, Nevada map) by a search of published geologic literature of the state of Nevada. An attempt was made to acquire a library consisting of all of the published geo-data for the state of Nevada as well as to obtain as much of the unpublished material as could be acquired. A study of these data, and in particular Tom Nolan&apos;s Professional Paper 406 (1962), indicated that the Windfall mine was anomalous for the Eureka District in that it contained deposits of disseminated gold. This source and other sources indicated that the Windfall had produced from underground operations approximately 59 kt (65,000 tons) grading 12.6 g/t (0.368 oz per ton) gold ore that was processed in a vat leaching operation and that the gold was "invisible" to the naked eye and could not be panned. It was ascertained that there were no active operations near the mine and a geologic reconnaissance was made and a few samples were taken to attempt to determine if the mineralization was indeed disseminated. The initial group of samples around the mine area averaged 1.25 ppm [11.5 g/t gold (0.036 oz per ton)] and the mineralization did appear to disseminate into the wallrock. The next step involved researching the ownership of property in the immediate area of the mine, and [ ] a property map was constructed that showed six or seven different ownerships of patented and unpatented claims, as well as some open ground, in the target area. Negotiations were commenced with the claim owners, ultimately resulting in the acquisition of all of the desired property, although some of

Jan 1, 1990

By Kaye P. Strong, Desmond M. Levins, Anthony G. Fane

1. INTRODUCTION The safe disposal of tailings is the most important environmental question facing the uranium mining industry today. This is because tailings present a major long term radiological hazard as they contain about 71% of the radioactivity originally in the ore. The magnitude of the problem can be appreciated by considering the quantity of tailings involved. For example, projections of milling programs in Australia indicate that there will be 100 million tonnes of tailings produced by the year 2000 (Levins 1980). The United States currently has in excess of 100 million tonnes and by the year 2000 will have between 900 and 1700 million tonnes (Landa 1980). Present options for tailings rehabilitation include leaving them above ground, returning them to the mine or placing them in specially excavated pits. In any event, the tailings will be covered with earth and revegetation attempted. This will remove the problems of airborne radioactive dust and water erosion of the tailings, at least in the short term, but diffusion of radon-222* from the tailings may still occur. The Atomic Energy Control Board of Canada (1981) has proposed a maximum allowable radon flux from rehabilitated tailings of 0.074-0.37 Bq m -2s-1(2-10 pCi M-2 s-1); the exact level is to be determined "after discussion with other regulatory agencies and the industry". The United States Nuclear Regulatory Commission (USNRC 1980) has been more restrictive in recommending a maximum flux of 0.074 Bq m -2s-1 (2 pCi m-2s-1). As a guideline they also suggested a minimum depth of covering material of 3 m to achieve this surface flux for tailings typically found in the western milling regions of the United States. The design of rehabilitation schemes is aided by a knowledge of radon transport through tailings piles. In this paper we present the results of a theoretical analysis and experimental study of radon diffusion through selected Australian tailings and cover material. The minimum cover criteria of 3 m is reexamined in the light of these findings. [ ]

Jan 1, 1981

By A. J. Lynch, M. J. Lees

Introduction The design of wet grinding circuits may vary considerably according to the duty which is to be performed. Grinding machines which are commonly used in these circuits are rod mills, ball mills, autoge¬nous mills, and pebble mills while size separation machines commonly used are vibrating and wedge-wire screens, hydrocyclones, and rake classifiers. In some circuits, such as those producing feed to cement kilns, all the ore entering the circuit is discharged in a single product stream. In others, such as those operating on magnetite-taconite ores, the feed entering the circuit leaves in two or more streams. Grinding circuits in flotation plants normally include sections in which either the concentrate or the tailings from the primary flotation circuit is reground and these additional sections should be regarded as an inte¬gral part of the grinding circuit. A typical circuit is shown in Fig. 18. Problems in achieving maximum efficiency may occur at three stages: 1) At the design stage when the optimum size reduction flow¬sheet must be selected with respect to the types, numbers, and sizes of processing units. 2) At the operating stage when the correct selection of values must be made for those variables which may be altered while the circuit is off-line but which are constant while the circuit is on-line, for instance the vortex finder diameter of the cyclones. 3) Under conditions of continuous operation when changes in the circuit feed or in the mechanical operation of the circuit may cause undesirable changes in the circuit product. The first two prob¬lems are concerned with optimization, that is, with making the best choice from many possibilities, and the last with control. Optimization Problems. The main purpose of a wet grinding circuit is to produce particles with a sizing distribution which will ensure optimum performance of the later chemical reaction or physical concentration circuits, because it is on the efficiency of these later circuits that the economics of the total mineral treatment process depend. The size distribution of the product from a grinding circuit may be affected by many variables, some concerned with the arrange¬ment and operation of the machines and some concerned with the ore characteristics, and it is important that these should be recognized in the design and operation of the circuit. For instance, in a simple ball mill-cyclone circuit the variables which affect the product size even for constant feed characteristics are shown in Fig. 19. In addition, the rate, size, hardness, and mineralogical composition of the feed will affect the performance of the circuit and the product size. When the circuit contains more than one mill, both the number of choices available and the complexity of the problem are increased consider¬ably. Consequently, one type of problem which is to be solved if an optimum product is to be obtained from an existing grinding circuit is that of circuit design, and this includes arrangement of processing units and selection of those operating conditions which cannot be altered when the circuit is operating, such as mill speed and cyclone inlet and outlet dimensions. The other major problem in optimization is encountered at the design stage when a choice must be made about the type, number, and size of processing units. For instance, for a typical high-capacity size reduction operation, should two circuits each containing one rod mill and two ball mills or three circuits each containing one rod mill and one ball mill be used? Alternatively, should ball mills only be used and if so, how many, what size, and what arrangement?

Jan 1, 1985

By Edgardo I. Cifuentes, Andrew L. Mular, Andrew Burkert

Experimental designs are data acquisition plans which, if followed exactly, will quickly provide process engineers with information to assess statistically the individual and joint influence of factors on responses to permit of rapid decision making. Methodology employed to construct data acquisition plans is described in some detail. In production environments, factorial designs are appropriate for most purposes. Use of two level factorials to make decisions is described for a grinding circuit.

Jan 1, 1991

By K. Adam

Uncontrolled disposal of pyrite wastes and concentrates comprise a major source of acid drainage in active and abandoned sulphide mines. In this paper, the state?of-the-art mitigation measures implemented for the final reclamation and closure of a pyrite concentrate stockpile at Platia Karra, Stratoni mines, Greece, are presented.

Jan 1, 2002

By Gordon M. Pugh, David G. Rasmussen

INTRODUCTION Square-set timbering of stopes developed from stull support methods because veins too wide for stulling were being mined. In general, the void caused by the stoping of the ore is filled with a system of interlocking timbers. Timber framework supports the wall rock, the mining operations, and provides access. A timbered stoping method can be used in all widths of veins at any dip. The timbering can be normal and parallel to the planes of the walls or at angles to these planes. Irregularly shaped ore bodies can be worked by timbered methods. Pinching or swelling of the vein will not adversely affect the method. Timbered stoping is especially advanta¬geous where weak ground is encountered in the vein or the wall rock. The ground is unsupported only until timber sets are stood. These stopes can be filled with sand or waste when desirable. The customary method of developing a square-set timbered stope with haulage drifts above and below and timbered raises on each endline is shown in Fig. 1. The drifts are timbered the full stoping length. The raises have two compartments with the manway and timber slide in one compartment and the chute in the other. The drifts and the raises cannot be widely spaced as handling timbers is an important consideration. Stoping can begin immediately above the drift timber and continue in both directions and upward from the raise. Breasting down each blast round for only one timber set laterally is the common practice. The blasted ore falls to a lower floor where it is slushed or trammed to the chute. Drilling can proceed on the upper floor while broken ore is being removed from the stope. As shown in Fig. 2, square-set timbering may be used in cut-and-fill stopes to support the back and walls until fill is added. There are various ways of developing an ore block for timbered stoping. Fig. 3 depicts the situation for the main haulage in the vein with an intermediate drift separated from it by a sill pillar. The ore is slushed into the chute connecting the two drifts. The situation in Fig. 4 is identical to that in Fig. 3 except that no sill pillar is used. In Fig. 5, the haulage drift development is done in the footwall with crosscuts driven to intersect the ore body. The intermediate drift development is above the crosscuts with a minimal sill pillar. The main bottleneck in timbered stoping is in the timbering process. Drilling in the stope is generally held up while timbering is done. Two or three men are re¬quired to do the timbering and an additional one or two men are needed to transport and raise or lower the tim¬ber. Good organization is essential to timbering. Skill must be exercised in standing the timber to support the ground and still maintain good production. COSTS AND PRODUCTIVITIES Development and stoping costs are presented in Tables 1 through 7 for the situations in Figs. 3 and 5,

Jan 1, 1982

By J. Herbst, A. J. Lynch, E. V. Manlapig, G. C. Throne, J. S. Hall, G. Poling

Modelling of industrial sulphide flotation based on data collected in several flotation plants is discussed. A mechanistic approach is used in which it is recognised that flotation is a two stage process with concentration occurring both in the pulp and in the froth. The important features of the model, which is a kinetic model, are – 1. for each particle species there is a range of flotation rates which corresponds to the range of particle sizes, 2. the flotation rates of the liberated gangue particles which have no hydrophobic properties are dependent on the flotation rate of water and are controlled by variables such as the air and frother addition rates, and the pulp level, 3. as an approximation the valuable sulphide particles may be regarded as being present in two groups with high and low flotation rate constants, 4. increase in the addition rate of collector tends to increase the proportion of sulphide particles which are in the high flotation rate constant group. The actual flotation rate of each group of particles is a combination of an "inherent" flotation rate and a flotation rate which is dependent on the flotation rate of water, at particular air and frother addition rates and pulp levels there is a physical limit to the rate at which particles can be transported into the concentrate and this is recognised in the

Jan 1, 1976

By Joel Nonnweiler, David Young, John Hawley

The Sacramento Regional County Sanitation District has implemented a billion-dollar interceptor system master plan, including the 31 km (19 mile) long Lower Northwest Interceptor (LNWI). For the two LNWI Sacramento River crossings, pipe-jack/micro tunnel drives in excess of 300 meters (1,000 ft) from 30 meter (100 ft) deep shafts in mixed soil conditions below the water table were considered, as were600 meter (2,000 ft) tunnel drives utilizing pressurized-face tunnel boring machines. Operation and maintenance concerns, predicted flood scour, and levee concerns are discussed. A risk assessment process was used to select both profile and construction method. Construction will begin in mid 2004.

Jan 1, 2003

By Edmond O’Donovan

Mooranbah North is a new greenfield project in Australia&apos;s Bowen Basin that is projected to produce 4 mtpa of hard coking coal from a single longwall. Located in Central Queensland in Australia&apos;s northeast, this is one of Australia&apos;s main coal producing regions. From the outset, Mooranbah North&apos;s approach to equipment selection has differed markedly from that usually taken in the mining industry, and the conveyor industry in particular. Until recently, no performance requirements have been placed on conveyor equipment suppliers. This arose from a practice of purchasing components in an ad-hoc manner from a variety of sources, and the mine then configuring the system. More recently, single source supply has been adopted as a means of obtaining some performance guarantee, usually expressed in terms of system availability. Unfortunately, the term "availability" has a multitude of definitions, particularly in the underground coal sector. A conveyor availability of 98% is a common goal but this rarely means the conveyor must operate 165 hours/week, 52 weeks/year. There are mines that have one maintenance shift for each production shift and claim availability of 100%. What is meant is that no down time is logged to the conveyor during the hours that it is wanted. This "generous" definition of availability would not be tolerated in many industries and nor should it. Unfortunately, a true definition of availability, such as is applied to steam turbines in the power generation industry, is not particularly helpful. Five day/ week operations would immediately face a 28% penalty against 7 day rosters, and there would be no sensible manner in which weekend maintenance could be incorporated into the availability formula. The approach adopted by Mooranbah North was to specify a period of "Failure Free Operation," which would be followed by a maintenance period. This

Jan 1, 1998

By William F. Riggs

In the fresh application of a frother, collector, or the change of any particular reagent, the interaction caused by this change is often overlooked since we attempt to solve a problem or improve a situation with use of a particular reagent without regard for the Interactions or side effects. When a particular reagent is added to a flotation circuit or substituted for another reagent, a series of chemical reactions occurs which. In turn, will create different physical responses. This discussion will provide a series of examples which have actually been experienced by the author.

Jan 1, 1994

By G. R. S. Smith

In any filtration, it is primarily the filter medium (cloth) and cake filtering properties that control the type of filtration equipment used and filtration conditions. The advent of new types of filter cloths, such as the membrane cloth discussed in this paper, can result in significant changes in filtration techniques and areas of application for filtration. For many suspensions, for instance, conventional filtration is uneconomic compared to gravity separation or not filtering at all (as with product recovery from dilute streams) because the solids are very fine, are hard to retain and build up filter pressure rapidly, and once retained are hard to remove. As a result of the developments discussed here, this is no longer the case. This technique and the use of the membrane filter cloth is well established. This filtration is currently being used for white liquor filtration in twenty-four mills worldwide in the chemical recovery step of the kraft process for producing paper pulp where it is replacing gravity thickeners in new plants. Filters up to 1000 sq. ft. (100 sq. meters) are filtering large volumes of solids from hot caustic solutions. The filtration materials and techniques discussed in this paper open the way to new methods and applications for filtration in the mining industry. It is not the intention of this paper to give a vigorous analysis of the different separations, but to outline some of the ways in which this filtration technique might be used in the mining industry.

Jan 1, 1989

By S. D. Bearden

The world&apos;s barite reserve base is adequate for at least 100 years at the current consumption rate. China, India and the United States are expected to remain the leading producing countries, and the United States will continue to be the largest consumer. None of the known substitutes for barium sulfate are expected to impact existing applications. World production in 1995 was 4.41 Mt (4.86 million st), which is about 50% of capacity. Consumption is directly proportional to hydrocarbon well installation activity. Imports are expected to continue to supply more than half of the US requirements.

Jan 1, 1998

By Oleg N. Tikhonov

The paper deals with computerized analytical design of separational mineral processing flowsheets for flotation, gravity separation, magnetic separation, etc. (without comminution). Initial data include fractional composition of the feed ore, separational characteristics of the unit operations, and optimality criterion. Computer-calculated results display optimal flowsheet configuration and optimal parameters of unit operations like tonnage, residence time, etc., which allows the choice of equipment. An example of apatite flotation flowsheet design is given. This analytical approach may be used for automatic process control purposes as well.

Jan 1, 1989

By N. T. Rempe

The underground voids that result from mining provide opportunities for deep geologic waste disposal (DGWD). Such disposal could solve many environmental problems. DGWD takes careful planning, technology transfer and true partnership between waste generators and mine/repository operators. The US government is now planning on using specially mined excavations to dispose of radiotoxic and mixed waste. Using the experience gained from the domestic projects that are now in preparation and from foreign repositories that are now in operation, US mines can claim their rightful share of the growing market for DGWD.

Jan 1, 1998

By Bonn J. Macy, David A. Gulley, William A. Vogely

INTRODUCTION Some of the most famous and graphic environmental incidents have arisen from mineral extraction, including oil spills, the Reserve Mining asbestos tailings case, Kaiparowitts surface mining and coal combustion, and other environmental causes celebre. The remote location of much of the mining industry to some extent reduces the human health hazards from pollution, but often times the pristine locale in which mining is conducted provides a sharp contrast to the impacting industry. This prompts questions as to what the research literature says about the true costs and benefits of environmental compliance. We survey the state of this knowledge. Where possible, we discuss studies focused on mining and related industries, such as primary metals production. In many cases, how- ever, the studies pertain to the economy as a whole. For present purposes, the mining industry is defined as companies engaged in the production and refinement of minerals, including metals, fuels, and nonmetallics (e.g., phosphate, sand and gravel). There are several stages in mining, with environmental effects occuring at every stage. The exploration stage comprises the period from initial prospecting to the point where the deposit has been located and delineated in sufficient detail to permit development decisions to be made. Geophysical and geochemical surveys, diamond drilling programs, and exploratory stripping and excavation are activities that may be employed during this stage. Some forms of prospecting are relatively benign, al- though even airborne surveys and motor vehicles generate noise pollution. Roads and the passage of vehicles and equipment affect land surfaces and vegetation, and attract heavier backcountry use. Clearings, stream crossings, and borrow pits can lead to increased erosion and sedimentation of streams. Geological survey grids disrupt vegetation and appearance. Moreover, prospecting can involve the excavation and stripping of overburden, resulting in soil and vegetation disruption as well as in- creased sedimentation of streams and lakes. The effects of exploration are often temporary, and frequently less severe than for other activities. Nevertheless, exploration-related impacts vary with the intensity and type of exploration effort, and can be significant. During the development stage of mining, shafts are sunk, pits excavated, buildings erected, and transportation facilities established. Dust, noise, and other socioeconomic and environmental impacts are generated by the relatively large and sudden influx of people, equipment, and activity. Surface disturbance and solid waste are generated by development, and liquid wastes form when mines are dewatered. The extraction phase is associated with a variety of environmental impacts. These impacts may differ for surface and underground mines. In surface mining, surface disturbance is obviously a major consequence. Piles of overburden and waste accumulation mar land surfaces. Wind and water erosion tend to spread the dis-

Jan 1, 1985

By Frank R. Field, Joel Clark, Walter C. Labys, William A. Vogely

Mineral models provide a systematic and comprehensive approach for analyzing and fore- casting the behavior of mineral markets and industries.&apos; They also permit the analysis of a wide range of policy decisions. Obviously such models cannot capture all of the intricate relationships that shape the behavior of a mineral market. However, such models have become extremely useful and in many cases support the decision making approach of judgmental analysts. They tend to narrow the range of likely outcomes and thus reduce the risks and uncertainties of investing, trading, and speculating in minerals. Mineral models provide not only answers to "what-if" questions, they also inform analysts of the benefits and costs associated with mineral investment decisions. More recently they have been applied to specific mineral issues of the possible impact of buffer stock stabilization schemes and of import supply restrictions. Mineral Models Defined Because mineral models are so diverse, we must begin with a fairly broad definition. A mineral model is a formal representation of a mineral market, industry or system where the behavioral relationships included reflect the underlying economic and engineering factors as well as the political and social institutions. Of ten, but not always, a mineral model will consist of some combination of the following components: demand, supply, inventories and prices. Modeling of demand behavior normally begins with an interpretation of basic demand responses to prices and income (i.e., the associated price and income elasticities). Price elasticities vary among different minerals and among their diverse uses. They tend to be lower for minerals without close substitutes than for those where such substitutes exist. In addition, these elasticities vary with time as well as with the actual excess demand or excess supply. Variations like these, coupled with the relative instability of prices for a number of minerals, make explanations of demand behavior difficult. The degree to which demand responds to changes in income depends on the income elasticity of the end products to which the minerals serve as inputs. Those products with a relatively low income elasticity tend to experience proportionally smaller swings in sales than those with higher elasticities. The transmission of demand cycles to minerals producers comes through a series of stage-of-process effects. Demand measurement also is influenced considerably by mineral substitution patterns. The cross-price elasticity of a competitive or complementary commodity also varies with minerals, markets, and time. Where minerals easily substitute for one another, as in the case of cop- per and aluminum in electrical conductor applications, cross-price elasticities are relatively high. Modeling of mineral supply behavior normally involves consideration of resource development, economic conditions, geologic

Jan 1, 1985

By C. D. Wittreich

The results of an engineering study of fiber-reinforced cemented tailings are presented. These tests were conducted to evaluate the potential for using fibers to increase the strength of cemented tailings used as backfill for ground support in the undercut -and - fill mining method in a mine subject to high horizontal stresses and rock bursts. Stress-strain measurements indicate that fibers not only increase the peak compressive tensile and flexural strengths of cemented tailings, but limit reductions in residual strength following failure. Results also show the effect of water content, fiber type, fiber density, and curing time on strength.

Jan 1, 1987