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By T. J. Carew

The application of many standard estimation techniques to deposits with a significant degree of folding or faulting can be difficult, mainly because of the necessity to maintain the correct spatial relationship between the samples and the points being estimated. Various transformations must be applied to the points of interest before variography and estimation can be applied, followed by back transformation into the original space. This paper presents an unfolding technique developed by Gemcom Software International that minimizes the inherent distortion in the process and also provides an example of the technique in folded and faulted situations.

Jan 1, 2002

By K. E. Brown, T. D. Murphy

At Monterey Coal's No. 1 Mine in central Illinois, it became necessary to predict if the sulfur content of individual trainloads of coal would exceed a contract sulfur maximum. Using geostatistics and Monte Carlo-type simulations, a forecasting procedure was developed to meet this need. The developed procedure predicts the monthly, mean sulfur content of the coal shipped and the probability of individual shipments exceeding the contract limit. During the first five months of using this procedure, the forecasted, monthly mean sulfur value was within 0.03% of actual. This represents a significant improvement over the inverse-distance, gridding-based, forecasting used previously.

Jan 1, 1994

By P. J. Bethell

This paper reviews current fine coal cleaning circuitry, including water washing cyclones, tabling and froth flotation. It goes on to examine possible future beneficiation based on emerging technologies. Circuits considered include those incorporating spirals, fine heavy medium cycloning, hydrosizers and column flotation.

Jan 1, 1988

By J. W. Wilson, Y. Ding

In the ultrafine coal-cleaning process, small coal particles (-400 mesh) are produced during the pulverizing operation. After the coal-cleaning process, these ultrafine particles are very difficult to dewater and create problems in coal transportation, storage and handling at utility plants. Research on ultrafine coal dewatering and briquetting resulted in the development of a single-stage operation that is potentially more effective and economical than conventional thermal drying and briquetting processes. The final coal product has a moisture content of less than 15% and possesses high strength and water resistance that satisfies coal transportation, storage and handling requirements.

Jan 1, 1996

By Deepak Malhotra

The economic viability of mineral companies not only depends on maximizing mineral recoveries but also on their ability to do so at minimum cost. Increasing pressure to cut costs has resulted In reduced staff, thereby decreasing the capabilities of routine metallurgical audits. This paper reviews a systematic approach to plant auditing which has been used successfully at several operations. Several case studies illustrating the potential benefits that can be attained from flowsheet auditing of mineral processing plants are discussed.

Jan 1, 1991

By H. M. Breza

Recovery of phosphate concentrate at Texasgulf’s Aurora Mine has received increased attention as existing mine and plant production capacity limits are reached. Improved mining techniques and mineral processing of waste streams offer the potential to increase phosphate production without major expansion. Innovative processes are being identified to maximize pit mining recovery and to minimize waste stream losses. This results in more effective use of the phosphate. Texasgulf Inc., is a wholly owned subsidiary of Elf Aquitaine. The Aurora phosphate rock mine and refining facilities are located in North Carolina on the south shore of the Pamlico Sound. Phosphate ore is recovered by open- cast mining techniques. Draglines and other earthmoving equipment are used to uncover and mine the phosphate ore. The mined ore then is slurried and pumped about 8 km (5 miles) to the processing plant.

Jan 1, 1994

By Kadri Dagdelen

The definition and shortcomings of traditional cutoff grades are discussed. . The concept of optimum cutoff grade policy which maximizes the Net Present Value (NPV) of annual cash flows coming from a mining project is introduced within the basic framework outlined by K. F. Lane. Several examples are used to demonstrate the shortfalls of cutoff grade policies obtained by various heuristic optimization techniques. An algorithm to obtain an optimum cutoff grade policy which maximizes the NPV of a project is given and described in detail.

Jan 1, 1992

By F. M. Doyle

Metal removal kinetics and metal ion selectivity in ion flotation were studied from a thermodynamic perspective. Surface tension data could be used with the Gibbs adsorption equation to quantitatively predict the metal-ion removal kinetics in alkylsulfate-Cu systems. However, surface tensions predicted cation selectivity coefficients in the sodium dodecylsulfate (SDS)-Cu-Ca and SDS-Cu-Pb systems rather poorly, although the predicted order of the selectivity (Cu2+ < Ca2+ < Pb2+) was correct. Another thermodynamic selectivity model, which used the Grahame adsorption equation and a geometrical analysis, predicted cation selectivity coefficients that agreed very well with experimentally measured values.

Jan 1, 2002

By Maureen D. Carmen, Joseph L. Zaluski, Gladys Beck Green

The Federal Surface Mining Control and Reclamation Act (SMCRA) requires a surface mine operator to post a performance bond before a mining permit can be issued to that operator. Release of that bond is contingent upon the completion of all required reclamation, restoration, and abatement work on the permit area. This paper explores the requirements of each of the three phases of reclamation under SMCRA, as well as provisions of four exemplar state regulations of four states that have been granted "primacy" under SMCRA. Successful completion of these requirements is a condition pre cedent to the release of performance bond liability. Failure to secure a timely bond release will have an ad verse impact on an operator&apos;s other mine permitting activities throughout the United States.

Jan 1, 1991

By Ernst Raphael

Mechanical drives of belt conveyor drives have experienced a huge amount of improvements concerning technology, manufacture and product structure that reduced investment and maintenance cost significantly. Most of these improvements were of technological nature in the&apos;70s and &apos;80s of this century; whereas, the present decade requires products that meet technical excellence as well as commercial advantages such as quick delivery, low cost and reliable spare parts supply. The best approach to meet these requirements is a highly modular and standardized system of reliable components that cover all demands a conveyor drive might require.

Jan 1, 1998

By Louis L. Sirois, Kwang S. Moon

The flotation mechanisms of various flotation machines are briefly reviewed. The counter current column flotation mechanism is described in more detail. The merits of counter current column flotation include; improved metallurgical performance in terms of grade and recovery, effective cleaning action in the long cleaning zone with a blanket of fresh water, smaller floor space required due to the vertical configuration of a flotation column, low capital, operational, and maintenance costs due to the absence of moving parts and finally, easier flotation control due to the simplified circuit. The results of column flotation studies on various minerals and coal at CANMET are discussed. Some of the industrial experiences with the Canadian flotation column on various sulphides, oxides and coal are also presented.

Jan 1, 1988

By L. G. Tejada, T. Sjursen

In the production of ferronickel at Falconbridge Dominicana&apos;s plant in the Dominican Republic the Reduction Plant plays a vital role by partially reducing the nickeliferous oxide ore, and pre- heating the charge to the electric furnaces. Ore is agglomerated in the form of pillow-shaped briquettes which are screened and fed to 12 open-top shaft furnaces. Hot (over 1250°C) reducing gases are partially cooled (less than 1150°C) and introduced through a set of primary tuyeres. The reducing gas rises counter-currently to the flow of solids. A portion of the partially spent reducing gas is withdrawn at the furnace top and recirculated through a set of secondary tuyeres, 1800 nrm above the primary tuyeres. Together with the recycle gas a controlled amount of air is also added to react with the partially spent reducing gas in order to preheat and dry the charge in the upper part of the shaft furnaces. The calcine is discharged through three discharge legs and pusher block assemblies into open-top refractory lined cars. These cars are then hauled to the electric furnace, parked over selected feed ports, and discharged through bottom gates. The furnace exhaust gas is de-dusted in cyclones and then passed through Venturi scrubbers. The slurry is fed to a thickener, filtered, and recycled to the ore receiving hopper in the ore preparation area. Dust generated throughout the plant is collected, wetted to conform with briquette press feed, and recirculated in a controlled manner through the feed system.

Jan 1, 1979

By J. Loredo

Wastes related to abandoned mine sites can constitute important potential pollution sources, depending on their mineralogical and geochemical characteristics and volume. Mine waste disposal sites contain a diverse variety of wastes including overburden material and waste rocks, the ore which cannot be economically removed and wastes from the smelting processes when they are accomplished at the mine site. These materials are usually heterogeneous in size, mineralogy and metal concentrations. Asturias, in northern Spain, has an extensive mining history and, in consequence, there are abundant unreclaimed and derelict mine sites with abandoned mines and spoil heaps of different age, morphology, content and dimensions. In these spoil heaps, waste materials are subjected to the intense action of a humid environment, so the instability of sulphides and sulpharsenides results in the production of acid and metal-rich leachates, which are incorporated to surface water or infiltrated through the land reaching groundwater bodies. The mineralogical and geochemical characteristics of the stored materials are key data to evaluate if they represent an environmental risk. Mineralogy and geochemistry of wastes and the particular specific environmental conditions of each site affect the rate of weathering and therefore the metal release. The characterisation of mine wastes is a necessary step in order to establish suitable assessment strategies with the aim of reducing the leaching, transport and widespread of ecotoxic elements from mining wastes to the environment (surface water, sediments, soils and air). As a consequence of the weathering of As-rich mineral phases, high arsenic contents are commonly detected in effluents from mine voids and spoil heap leachates.

Jan 1, 2006

By V. Castranova, L. Wu, K. Van Dyke, J. Gutierrez, V. Vallayathan

Since it has been demonstrated that silica caused phagocytic cells to activate lipoxygenase metabolism of unsaturated fatty acids we thought selective inhibition of this metabolic pathway might be helpful in treatment of silicosis. It is known that lipoxygenase metabolism plays a role in the pathogenesis of a variety of inflammatory and hypersensitivity conditions. Further, it is believed that the alveolar phagocytic cells which engulf silica begin the inflammatory cycle which produces the metabolic products, cytokines and growth factors which causes fibrosis in the lung. There have been indications that drugs which inhibit lipoxygenase can inhibit fibrosis from other causes. Previously, we developed a method which detects the activity of lipoxygenase metabolism by measuring free radical oxidation via light production or chemiluminescence (CL). We decided to apply this method to phagocytic cells that would be found in the lung in the presence of silica with and without newly developed inhibitors of the lipoxygenase reaction. We used drugs which inhibit lipoxygenase directly including AA861 (TAKEDA), A63162 (Abbott), and an inhibitor that scavenges free radicals produced from the lipoxygenase reaction, nordihydroguairetic acid. In addition we used an indirect inhibitor, tetrandrine. We found drug inhibition of silica activated CL from alveolar macrophages, neutrophils and human leukemia (HL-60) cells differentiated with DMSO. Nordihydroguairetic acid 2x10-5M produced almost complete inhibition in all three cell types. In human leukemia cells (HL-60) A63162 and tetrandrine were equally inhibitory at 42% while in human neutrophils A63162 and tetrandrine were less active 22 and 10% respectively. In macrophages A63162 and AA861 were less than 50% inhibitory to cellular CL at 2xl0-5M. Direct assay of tetrandrine (2x10-5M) with sodium arachidonate and soybean lipoxygenase reveals no inhibition. All antilipoxygenase drugs regardless of mechanism were inhibitory to cellular chemiluminescence from all three types of phagocytic cells. These drugs alone or in mixtures could prove useful in treatment of silicosis.

Jan 1, 1991

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

Jan 1, 1986

By J. Iannicelli

Kaolin, normally an inert filler when compounded with polymers, is converted into a strongly reinforcing pigment by prereaction with certain functional silanes. Modification of kaolin with amino and mercaptosilanes allows it to form crosslinks and confers significant improvements in modulus, abrasion resistance, compression set and other physical properties of a broad range of polymers.

Jan 1, 1992

By Tim Avery, Steve Klein, Mark Schmoll

Tunnel boring machine (TBM) performance in hard rock is highly dependent on the geologic conditions, including the type of rock and hysical properties like the rock strength, hardness, and the spacing of the fractures. This paper examines TBM performance relative to the geologic conditions and rock mass properties at four recent TBM-bored tunnels in California.

Jan 1, 1995

By I. Toromanoff, F. Habashi

The transformation of a low-grade titanium slag into synthetic rutile or synthetic anatase can be enhanced by attrition grinding.

Jan 1, 1987

By J. F. Ziegler

The Silver Chert jasperoid, Mercur District, Utah, records a complex history or silicification and tectonic activity.

Jan 1, 1990

By J. A. Herbst, L. B. Hales, R. A. Ynchausti

Industrial application, theoretical discussion and technical research programs continue to stimulate acceptance of column flotation. Numerous authors have published model, parameter and application studies discussing advantages and problems which are associated with this minerals processing technique. This paper dispells the myth of the self-controlling column while focusing on the problems and opportunities which are inherent in the computer control of a column flotation cell.

Jan 1, 1988