Search Documents

By J. W. Leonard

Since the interpolation of exploratory data 1 can be no better than sampling procedures, a series of field experiments were conducted in an effort to determine whether hand-cut channel or core washability determinations best represent continuous miner produced run of mine coal. By obtaining a core drilled to within a few feet of channels taken from an underground face and then overmining both locations; core, channels and run-of-mine coal allocations were obtained from a common sample and all allocations were subjected to identical washability determinations. In order to compare results, basic rules2,3 previously anticipated and later published by the writer were employed. The first rule states that "For any full seam washability determination, the sulfur versus ash function for increasing cumulative specific gravity float coal fractions is linear". The second rule states that "For any full seam washability determination, the recovery versus ash function for increasing cumulative specific gravity float coal fractions is logarithmic".

Jan 1, 1988

By Donald G. Foot

The Bureau of Mines, U.S. Department of the Interior, devised a direct flotation method for treating low-grade carnallice (KC1.MgC12. 6H20) and sylvinite (a mixture of KC1 and NaC1) ores characterized by a high content of water-insoluble impurities. The procedure consists of (1) flocculation-depression of the insoluble slimes, (2) decomposition leach (carnallite only), (3) potash rougher, cleaner and recleaner flotation, and (4) final product leaching. The technique eliminates the necessity of removing the water-insoluble slimes by mechanical or flotation desliming. Laboratory results demonstrated that the direct flotation procedure, when compared with conventional techniques, yielded equivalent or improved flotation results with equal or less reagent consumptions. The direct flotation method recovered 81.6% of the solid-phase KC1 from carnallite ore and 79.7% of the KC1 from sylvinite ore in final products containing 60.5% and 60.9% K20, respectively. A flowsheet incorporating the described flotation procedure is presented.

Jan 1, 1981

By Francis X. Murray

Synthetic fuels will be the first major development effort to feel the effects of a new set of opposition forces. These confrontations will not be of the same variety as those which occured in the 1970s. Instead the synfuels industry, particularly in the West, will find itself confronting a new coalition of local political, community, and state spokesmen. They will oppose synfuels because the projects will represent a threat to existing lifestyles, political structures, taxes, social life, water rights, economics, and other politically sensitive considerations. In short, they mean change -- usually dynamic, full of unknowns and always threatening. The battles themselves may be fought technically over environmental issues, law and regulations; often these will be the instruments of the opposition. The real underlying problems will likely lie much deeper. In many cases environmental groups will be enlisted as the standard bearers; however, this approach may simply reflect the fact that environmental objections are convenient or at times the only tools at hand.

Jan 1, 1981

By F. Ikumapayi

Hydrogen peroxide production was measured during the grinding of a complex sulfide ore, and its oxidizing effect on solid surfaces was investigated using Fourier transform infrared spectroscopy (FTIR) with diffuse reflectance attachment measurement. In turn, an attempt was made to correlate the formation of hydrogen peroxide, surface oxidation and sphalerite flotation. Additionally, in order to predict and minimize detrimental production problems due to the recycling of process water in sulfide ore processing, the effects of major components of calcium and sulfate species present in recycled process water and the effect of temperature on sphalerite flotation were investigated through bench-scale flotation tests using complex sulfide ores. The significance of process water species in flotation was studied using tap water, process water and simulated water containing calcium and sulfate ions. Formation of hydrogen peroxide was revealed during the grinding of the complex sulfide ore, and its formation was counteracted by diethylenetriamine (DETA). The FTIR spectrum of the pulp solid fraction showed varying degrees of oxidized surface species, which are related to the concentration of H2O2 analyzed in pulp liquid. Bench-scale flotation using two different complex sulfide ores showed that sphalerite recovery is better in process water than in tap water. Flotation results also indicated a varied recovery of sphalerite at different temperatures in either tap water or process water.

Newmont has been producing gold from the Carlin Trend for over 45 years. Naturally the focus, scale and complexity of the operations have changed considerably over this time. Newmont discovered and developed the Carlin Main ore body which is located about 32 km (20 miles) north of Carlin Nevada. The property was developed as a one mine one gold mill treatment plant operation which produced about 6,200 kg (200,000 Troy ounces) of dorè gold bars per year. The initial mine, mill and gold refining facilities were relatively small in comparison to today?s standards. The milling circuit used the Merrill-Crowe zinc precipitation process to recover dissolved gold and prepare a concentrated precious metal ?precipitate? to be melted into a dorè bar for sale.

Jan 1, 2012

By M. Adnan Göksel

Pyrite cinder is generated by roasting pyrite for sulfur dioxide production. It contains up to 62% iron, but also may contain other hazardous or toxic materials such as Zn, Pb, As, T1, Cd, Cu, Sn and S. Furthermore, the physical characteristics are not properly suited for conventional sintering. As a result pyrite cinder is considered to be unsuitable for iron and steelmaking or for outside storage because of its potential for causing environmental problems. In recent years industrialized nations have put increasing pressure on the manufacturers to either use such waste products or properly dispose of them. In this study, solutions to both the iron recovery and disposal problem were attempted by pelletizing the pyrite fines with internal carbon. The pellets, after hydrothermal hardening, were reduced and melted in a furnace for hot metal production. Hot metal of usuable quality was produced and the hazardous materials were either collected with the fumes or in the slag.

Jan 1, 1984

By R. Bhaskar

The results of an experimental study on the dispersion and deposition characteristics of fine coal dust in mine airways are presented. Experiments were conducted at various flow velocities using bituminous and semi-anthracite-coal dust which had a large proportion of dust in the respirable size range. Cross sectional variations in the concentration of dust at various points in the airway were also measured. Instruments used in the experiments included gravimetric samplers and impactors. Concentration measurements were made both for the respirable and total airborne dust. The experimental design, sampling procedures and results are discussed. The study is aimed at providing a better understanding of the temporal and spatial behavior of dust particles in underground mine airways.

Jan 1, 1986

By F. G. Miller

Over the past 30 years, the coal industry has been continually striving to perfect methods for cleaning fine coal to acceptable ash and sulfur contents while maintaining maximum product yield. The flotation process has been part of this effort and its importance is expected to grow as new utilization technology demands finer and purer coal products. The work outlined in this paper is part of a larger effort aimed at development of new and improved flotation systems for removing sulfur and ash from as-mined coal as well as for producing super-clean coal for future markets. The concepts and data presented are now serving as a basis for designing fine-coal circuits in which improved efficiency is obtained by optimum use of flotation.

Jan 1, 1986

By Robin G. Adams

The market prices received by producers of internationally traded commodity metals have been, and continue to be remarkably volatile and unpredictable compared with most other traded goods and services. This volatility results in an erratic financial performance on the part of producing companies, disruptive and often inflationary cost changes for consumers, unreliable tax revenues and export earnings for host governments and severe social and economic pressures on local, sometimes remote, communities which are dependent on the activity in question. Generally speaking, price volatility appears to be associated with the inability of the metal producing side of the industry to regulate the volume of supply in a manner that is consistent with metal demand, which in turn reflects broad macroeconomic and industrial developments around the world. This statement does not purport to apply to all metals or to all instances of volatility of course. Price movements may occur as a result of pure speculation or even illegal manipulation of the commodity markets. Embargoes, boycotts and other politically induced supply changes may contribute. Threatened or actual strikes also cause artificial swings in sales volumes and prices. How- ever, most of these developments are of a short-term nature. Yet metals price cycles may last for several years, as demonstrated by the extended copper price trough from 1981 to 1986. This paper deals with price volatility which reflects long-term economic cycles and the adaptive processes that exist within the industry in response to such cycles. Special emphasis is placed on the role of forecasts and forecasters in these processes. It should be said at the outset that this reflects the personal experience of one forecaster working in private sector commercial consulting practices that are independent of producers, consumers and host governments. However, the experience does cover the entire period since 1973 and has involved working with a substantial majority of the major companies that supply high volume commodity metals. By way of background it should be stated that the post-1973 world economy has provided a challenging environment for forecasters. One cannot be precise about the forecasting record of either industry insiders or outside consultants, financial analysts and academic forecasters because comprehensive records have not been kept, or if they have the results are too embarrassing to be published. Institutions such as the World Bank have published forecasts of the prices of major commodities on a regular basis and these have, presumably, had some influence on financing decisions in the industry. This record along with our own experience and numerous discussions with metal producers, major consumers and host governments permits certain generalizations to be made. The most important of these is that during the early 1980s. from about 1980 through 1985/6, the forecasters system- atically and substantially over- estimated metal prices. While some fore- casters did correctly anticipate a recession in the early 1980s and some consequential decline in prices, the magnitude and duration of the decline was far greater than anyone foresaw. This systematic forecasting "failure" appears to have occurred independently of the forecasting methodology employed. Moreover, its extent cannot be explained by obvious factors such as incorrect macroeconomic assumptions. There appears to have been some kind of structural change in the world mining and metals industry over this period

Jan 1, 1989

By Daniel A. Payne

For many years underground mining in the Sydney Coalfield has suffered from the effects of high horizontal stresses. It is only in the last 15 years that they have come to be recognized, understood, predicted and even avoided. This paper relates experiences in three coal mines in three different seams in the Sydney Coalfield. The effect of the direction of the principal horizontal stress on the direction of drivage of gate roads, access roadways and longwalls is described. Results of a monitoring program to measure the change of magnitude and direction of the principal horizontal stress in the gate roads as a result of longwall mining are also presented as well as the effect of the direction of principal horizontal stress on the shape of sandstone/gas outburst cavities.

Jan 1, 1998

By Nancy J. Wheatley

I. INTRODUCTION The Massachusetts Water Resources Authority (MWRA) is a regional water and sewerage authority which provides wholesale water and sewer services to the Metropolitan Boston area. The MWRA was created by the Massachusetts Legislature as an independent authority in 1985 following the filing of a lawsuit in federal court to correct the pollution of Boston Harbor resulting from inadequate and inadequately maintained sewerage facilities. Immediately upon its creation, the MWRA began to tackle treatment plant issues, including addressing the need for a secondary treatment plant, planning for ceasing ocean discharging of sludge, and making interim repairs to the existing, antiquated treatment plants. The MWRA's initial activities led to a court-ordered schedule for construction of a single new primary and secondary treatment facility, for development of sludge management plan focussed principally on reuse, and for completion of a short term program of repairs to existing facilities. Once a schedule for completing these activities had been negotiated, the U.S. Environmental Protection Agency (EPA), a plaintiff in the federal court case, asked that the MWRA take "responsibility" for controlling discharges from combined sewer overflows (CSOs) within its service area. Combined sewers (sewers in which both sanitary sewage and storm water runoff are carried in a single pipe) presently discharge over 10 billion gallons of untreated wastewater into Boston Harbor and its [ ]

Jan 1, 1991

By Gordon M. Pugh, David G. Rasmussen

INTRODUCTION This method is a variation of cut-and-fill mining where either the wall rock or the vein is too unconsolidated to permit safe mining by conventional cut-and-fill methods. Basic development consists of driving a 2.4 x 2.7-m (8 x 9-ft) haulage heading laterally in the footwall side of the vein. Crosscuts are driven over to the vein at 91-m (300-ft) intervals. Then the vein, at each inter¬section, is mined out to a distance of about 9 m (30 ft ) above the track level. After the installation of an ore chute, scrams or intermediate drifts are driven in both directions along the vein. Mining then starts imme¬diately below the level bounding the upper limit of the stope. A cut varying between 3 and 4.2 m (10 and 14 ft) in depth and mined for a distance of 45.7 m (150 ft )along the strike is taken from the orepass in each direction (Fig. 1). In this mined-out void, the floor of the cut is equipped with 203 x 203-mm (8 x 8-in.) caps hitched into the wall with steel saddle hitches installed on 1.5-m (5-ft) centers. Double wood stringers, 152.4 x 152.4 mm (6 x 6 in.), are then installed on 1.2-m (4-ft) centers longitudinally down the length of the stope. Reinforc¬ing wire mesh is also placed, overlying each mat of timber. Directly above the stringers, stulls are installed from hanging wall to footwall to hold the timber in place during the sand-filling operation. Then a cement¬sand mixture in a ratio of about 1:10 weight is poured to a depth of about 2.4 m (8 ft). The entire cycle is then repeated down to the scram drift. Another variation of timbering is illustrated in Fig. 2. There is a vein width of approximately 5.5 m (18 ft) with the same unconsolidated ground conditions. The primary difference between handling this situation and the previously described undercut-and-fill method is that standard timbered sets are installed in each excavated stoping void rather than stulls. Once again the basic method is to work down the ore block from an upper timbered drift to a lower timbered drift. Cuts are taken from a timbered raise with a chute on the stope side. Each piece of ground excavated is essentially two sets high, 5.5 m (18 ft), by two sets wide, 5.5 m (18 ft), by the length of the cut along the strike of the vein. The timbered sets are 2.4 x 2.4 x 2.4 m (8 x 8 x 8 ft). The net result is, therefore, two sets of timber on a top floor separated by doubled-up 76-mm (3-in.) lagging from

Jan 1, 1982

By Yu. A. Polozov, V. A. Lagunov, O. Yu. Lushinkova, Yu. I. Svirskiy, Eh. Ya. Kipko, Roy A. Williams

Hydrodynamic investigations in exploratory boreholes and grouting holes are conducted for the purpose of obtain¬ing information about the hydraulic properties of the hydrostratigraphic section to be intersected by the proposed underground workings. The information obtained from the investigations provides the basis for calculating the hydrau¬lic coefficients of fractured permeable rock, the dimensions of the anticipated grout isolation curtain(s) around the un¬derground workings, the number and location of grouting holes, the injection pressure modes, and also the volume(s) of grout that will be required (Anon., 1976, 1978). The following data on each aquifer are obtained from the investigations conducted in monitoring and grouting bore¬holes and the analysis of the results: 1) the top of each hydrostratigraphic unit, 2) the thickness of each unit, 3) the ground water fluid potential distribution in each unit, 4) the coefficient of permeability, 5) the piezoconductivity, 6) the fracture porosity, 7) the geometry of the fractures in the rock, 8) the elasticity-compressibility coefficient of the fractured rock, 9) the chemical composition of the ground water, 10) the direction of flow of the ground water, and 11) the expected inflow rate of water into the shaft, drift or tunnel. STG uses its DAU-3M type flowmeter to conduct in¬vestigations of directions of flow in vertical, inclined and horizontal drillholes. The DAU-6 instrument is used to de¬termine the direction of flow of ground water in each frac¬ture or fractured aquifer. Various singular and double DAU type packers are used for pumping and for injection studies (tests) and for flowmeter investigations. Normally the instruments enumerated above permit in¬vestigations to be conducted in each separate aquifer with¬out reinforcing the holes with casings. On the basis of these investigative data, both the hydraulic properties of unfractured rock and the hydraulic properties of the fractured rock are estimated. Dual porosity rocks require special attention because they tend to segregate the grout. 3.1 FLOWMETER INVESTIGATIONS IN BOREHOLES The STG flowmetric methodology is based on the mea¬surement of the ground water flow rate through the borehole by hydrostratigraphic interval after the disturbance of the hydrostatic equilibrium in the "hole-aquifer system" (after pumping or injecting). The relationship of the head changes to the discharge into or from a particular hydrostratigraphic unit obtained during the tests serve as the basis for calcu¬lating the hydraulic properties. Flowmetric investigations facilitate the determination of the number of aquifers, their depths, their thickness, the hydraulic properties of the fractured rock and the magnitude and direction of the flow of ground water. 3.1.1 FLOWMETER HARDWARE STG conducts flowmetric investigations in boreholes using its DAU-3M-108, DAU-3M-73, DAU-3M-57 and DAU-3M-44 instruments.' They have respective external diameters of 108, 73, 57 and 44 mm. The type of flowmeter selected for use depends on the borehole geometry and the technological scheme for carrying out the investigations. Boreholes with a drilling diameter of 76-93 mm are inves¬tigated with the DAU-3M-73 flowmeter; boreholes drilled by bits with a diameter of 112 mm and more are investi¬gated using the DAU-3M-108 flowmeter. The DAU-3M¬108 and DAU-3M-57 instruments are used for flowmetric investigations with a packer. 3.1.1.1 The Downhole Sensor The sensor design of the DAU-3M-73 hole flowmeter is shown in Fig. 2. The design of the DAU-3M-108 instru¬ment is similar to the design of the DAU-3M-73 instrument. The frame of the flowmeter sensor shown in Fig. 2 consists of a casing, an upper and lower centering mount and two rings to which the guiding rods are attached. The upper rods are built into the connector bushing; the lower rods are built into the coupling sleeve. The borehole cable is attached using a half-coupling, a packing ring and a constriction nut. Thus, the frame of the flowmeter sensor is made so that the free passage of water to the impeller is facilitated along with the necessary rigidity. The primary moving component of the flowmeter is the double-bladed impeller, which rotates on cobalt-tungsten pivots and agate thrust bearings. Special extended air cham¬bers protect the supports of the impeller from the action of the borehole fluid which may contain fibrous and abrasive particles. The air located in the chambers shields the sup¬ports from direct contact with the borehole fluid when the sensor operates in a borehole. The hollow casing of the impeller serves the function of a lower cap. The upper cap is attached to the casing using a threaded connector; it is affixed also with a lock-nut. An adjusting screw with a

Jan 1, 1993

By M. O. Woodburne

The Mojave Desert province is comprised of a diverse group of mountains that range in elevation from about 2,000' (600 m) to 3,000' (900 m), separated by tracts of alluvial cover. The province is bounded on the southwest by the San Andreas fault, on the north by the Garlock fault, on the east by the Death Valley- Granite Mountains fault. Rocks preserved in the Mojave Desert Province collectively record a rich assemblage of Precambrian crystalline basement' ranging in age from ca. 1.8 to 1.35 Ga, upper Precambrian and Paleozoic Cordilleran miogeoclinal sediments and platform rocks, Mesozoic backarc and interarc shallow marine and continental sequences, locally emplaced Permian- Triassic syenitic plutons, extruded hypabyssal volcanic rocks of the ?Jurassic "Sidewinder Volcanic Series," and regionally intruded late Mesozoic granitoid batholithic rocks (Dokka et al., 1988). The Mojave block apparently was a high-standing element for much of the early Tertiary, with strata of Late Cretaceous or early Tertiary age preserved only on its margins. Beginning about in the late Oligocene an intense episode of regional north-south extension was developed in a roughly east- west trending belt that traversed the central part of the province. This extensional belt has been termed the Mojave Extensional Belt. The extensional regime lasted from about 22-17 Ma, and is generally divided into two phases. The first, from about 22-20 Ma records intense extension via the activity of crustal-scale, simple shear, low- angle normal faults, high-angle normal faults, and extensional fracturing, along with intrusion of intermediate to silicic volcanic rocks, including episodes of explosive volcanic activity. The Peach Springs Tuff, a major regional marker unit that extends across the Mojave from Arizona to about Barstow, forms an effective stratigraphic lid on the extensional interval, (i.e., is not rotated) and is dated isotopically at about 18.5 Ma. The extensional episode was followed by an interval of high- angle normal faulting and dike emplacement from about 19 to 17 Ma, and was accompanied by at least local uplift and volcanism. Most volcaniclastic and epiclastic sedimentary units of the central Mojave block post-date the interval of extension and normal faulting, and occur as a complex of marginal alluvial and more interior lacustrine facies that formed as recently as late Miocene (ca 13 Ma). Local sequences (e.g., Lava Mountains) record deposition up to about 8 Ma, but there appears to be a regional "gap" from then until at least local successions record Pleistocene deposition. Magnetic and isotopic age studies indicate a complex history of crustal rotations, distributed across a number of discrete domains, during the past 10 Ma. Some of the youngest volcanic and geomorphic features apparently developed at "holes" formed at the edges of rotated blocks.

Jan 1, 1995

By Dirk van Zyl

Natural materials can be used successfully in the construction of heap leach pads. The use of these materials usually result in the least expensive approach for such facilities. Sufficient geotechnical experience has been gained in the design and construction of clay heap leach pads so that they can be used with confidence. A number of operators presently use clay pads in their heap leach facilities; these include Alligator Ridge, Ely, Nevada (gold), and Union Carbide, Gas Hills, Wyoming (uranium). This paper describes the construction and field investigation of a clay pad for the heap leaching of agglomerated precious tailings. The project is located in the Mojave Desert, Southern California. The design had to satisfy operational requirements as well as regulatory requirements. The California Water Quality Control Board (WQCB) was one of the agencies which had to issue a permit for the project. Their biggest concern was the discharge or escape of cyanide into the environment. Rather stringent requirements were therefore placed on the pad design criteria, especially in terms of permeability.

Jan 1, 1983

By Paul Eimon

In the world of minerals exploration, computer-oriented data storage and retrieval methods are being talked about, studied and researched. The goal is to facilitate the recording, collating, indexing, recovery, and analysis of mineral deposit-prospect data. A survey has been made of the various report forms, suggested outlines, and computer coding forms that are currently used in mineral exploration to index and/or describe mineral deposits and prospects. These forms have a number of common characteristics: location, commodities, type of deposit, host rock, etc. Such basic mineral deposit-prospect "data units" are part of most exploration programs. "Data units" may be comprehensive bound published descriptions of mines or mining districts or 3x5 file cards or elaborate computer coding forms being developed in Canada. Initial attempts to develop computer-oriented information systems have run into the same roadblock: the lack of a body of organized, processible data describing the basic qualities of mineral deposits and prospects. To solve this problem, international committees are considering coding forms, world-wide semantics, and rules or standards for data collection and description. It appears that mistrust and lack of understanding of the computer; fear of loss of proprietary information; and disagreements over terminology are distorting the picture of what has to be done if the mining industry is to grow into more meaningful information systems for mineral exploration.

Jan 1, 1969

By Bruce S. Brown, Jeremy P. Haile

The construction of tailings facilities and heap leach pads for gold mining operations generally requires the installation of one or more impermeable liners beneath the structures to satisfy environmental regulations and prevent the leakage of gold bearing solutions. Liners are usually constructed using clay soils or synthetic membranes, such as high density polyethelene. Low permeability soil liners can be constructed from natural clays, well graded soils with only a small clay content, or sandy soils blended with a small quantity of imported clay such as bentonite or kaolinite. The permeability of such materials, prgperly pped with good quality control, generally lies in the range of 10- to 10- cm/s, and can be designed to meet minimum prescriptive standards set by regulatory agencies. Important benefits resulting from the use of clay liners include the slow rate of penetration of a saturated wetting front, the decrease in permeability of the liner as it consolidates under the applied load of tailings or ore, and attenuation of potential contaminants in the process solutions. Synthetic liners can be attributed a finite permeability as a result of minute perforations and seaming deficiencies, and possess none of the above properties. Synthetic liners are also, by their nature, relatively thin and even a small head build-up above the liner will result in a large hydraulic gradient across it.

Jan 1, 1988

By C. D. Anderson

A variety of processing technologies exist for recovery from both primary and secondary sources of rhenium. Currently, there are no known primary rhenium deposits; thus, the method in which primary rhenium is produced is dependent on the commodity of which it is a byproduct, e.g., copper, molybdenum, uranium, etc. In addition, focus on the recovery of rhenium from secondary sources, such as alloy scraps and catalysts, is continually growing. This paper presents a review of both primary and secondary processing technologies for the recovery of rhenium.

By G. Karahalios

Industrial minerals have always enjoyed an important share in the technological growth of any country in the world. Today, extraction and trading of industrial minerals has expanded, but is also subject to stricter environmental guidelines. This paper presents the current status as well as the growth potential in the exploitation of industrial minerals in the countries of the south eastern European region, i.e. Albania, Bosnia-Herzegovina, Bulgaria, Croatia, F.Y.R.O.M., Greece, Italy, Serbia and Montenegro, Slovenia and Turkey. More specifically, annual production figures per country are presented for1992-1998. These figures are compared to each other and, where applicable, to world production figures. Trading of industrial minerals from these countries to Europe and the world and its effect to the local economies is also evaluated were such data is available.

Jan 1, 2000

By Paul Richardson

This paper discusses the drilling techniques and equipment used by Loffland Brothers Company to drill the AEC's UC-3 large diameter shaft in Nevada. Included are pictures and illustrations of the drilling-mud circulating system, the surface and downhole drill-string and the special heavy-duty mast and hoisting equipment required to do the job. The purpose and method of lining the large diameter holes along with the technique and materials used to backfill the lining to hole annulus are discussed briefly. Areas requiring improvement in both equipment design and technology for large diameter shaft drilling are discussed briefly. Shafts as large as 140 inches in diameter to depths of 5,000 feet can be drilled with existing equipment and technology.

Jan 1, 1969