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By Benjamin K. Pocock

When considering alternative equipment choices in mill or process flowsheets, it is important to determine both capital and operating costs of such equipment as well as other possible savings related to downstream operations. This paper presents a few case studies and shows cursory guidelines for the selection of equipment for new installations or in the retrofitting of existing plants. Based upon recent plant experience, suggestions are given to improve the operation of clarifiers, thickeners and vacuum filters.

Jan 1, 1986

By K. G. Sutterer, P. T. Wang, R. Sweigard

One possible alternative for the disposal of flue gas desulfurization (FGD) by-products is to use it as backfilling support material in highwall mine adits. The finite element method was used to analyze the variation in stresses and displacements within and around a highwall adit backfilled with FGD materials. The engineering properties of the rock material and the optimum mix of the FGD materials were obtained from laboratory tests. Finite element analyses show that, for the case in question, the roof displacement would decrease about 48% and the peak stress could be decreased by about 58%. The study indicates that fairly weak FGD materials can eventually lead to the stability of backfilled highwall adits.

Jan 1, 1998

By D. W. Fuerstenau, J. Vazquez-Favela

This paper shows how the efficiencies of size-reduction processes depend on the mode of particle constraint and energy transfer within the comminution device: namely, whether the process consists of single-particle loading, confined-particle-bed comminution or loose- (unconstrained-) particle grinding. The relative efficiency of single-particle comminution, ball-mill grinding and particle-bed comminution in the recently invented high-pressure roll mill is evaluated by making use of the self-preserving nature of the size distributions of comminuted products. The highest energy efficiency can be achieved by utilizing a hybrid two-stage system in which the material is first ground in the high-pressure roll mill and then the ball mill.

Jan 1, 1998

By M. K. Larson, R. G. Wade

Researchers at the National Institute for Occupational Safety and Health (NIOSH) are studying the time- dependent response of rock stressed along weakness planes. The objective is to improve mine safety by reducing the number of roof falls that cause injuries and fatalities to miners. Researchers conducted direct- shear tests on mudstone overcored from a coal mine roof. Results showed frictional strength weakens with displacement along the shearing planes. Results of direct-shear creep tests also showed time-dependent deformation. Test measurements were compared to classical analytical models. Results suggest that the risk of roof collapse may be decreased through layout and support design to reduce creep rates and thus slow progression toward failure.

Jan 1, 2002

By S. Monette, D. B. Dreisinger, D. Vleeschhouwer, G. B. Harris, G. A. Kordosky

A new process for the recovery of pure (>99.95%) palladium and platinum is described. The process, which has been tested at the pilot scale, comprises (i) the simultaneous solvent extraction of palladium and platinum by a new Schering Berlin reagent, TN 1911, (ii) washing of the loaded extractant to remove co- extracted impurities, and (iii) differential stripping of first platinum at pH 3, and secondly palladium with strong hydrochloric acid, and (iv) precipitation of palladium and platinum salts, followed by reduction to metal. The process is, unusually, a non-ammonia one requiring only small amounts of ammonia at the end where final purification may be necessary for particularly complex feed solutions.

Jan 1, 1993

By S. K. Kawatra

In order to meet federal air pollution guidelines, it is necessary to remove a considerable quantity of sulfur from many North American coals. This may be accomplished by oxidizing the sulfur to water soluble forms, followed by washing the coal. Selective oxidation of the various sulfur forms can be accomplished through the use of a variety of types of bacteria. In this paper, the various bacteria and their requirements are described, and processes using bacteria to remove coal sulfur are discussed.

Jan 1, 1987

By J. W. Jang

The wear behaviors of grinding media with different chemical compositions and microstructures in wet grinding of a quartz-pyrrhotite mixture was investigated under various environments. The marked ball wear tests showed that the wear rate could be minimized by a suitable combination of martensite and ferrite within the same ball. A ball composed solely of hard martensite exhibited increased wear under an oxygen environment, while balls composed of both soft ferrite together with hard martensite exhibited decreased wear due presumably to the difference in their passivation? behaviors. The galvanic interactions between the two phases as well as among these phases and an electroactive mineral were investigated through electrochemical measurements under abrasive conditions in a slurry. The rates of formation of passive films controlled the corrosion currents of the high chromium steel media. Corrosive wear and its effect on flotation are discussed using the passivation kinetics model thereby developed.

Jan 1, 1989

By W. G. Lacy

Anticipation of problems and the adoption of corrective measures in the design of engineering structures, establishment of pertinent building codes, and urban planning and zoning to obtain optimum land usage and conservation of natural resources demands a thorough understanding of geological conditions of a developing urban area. In the and to semi-arid southwestern United States erosional and depositional processes result in special situations that require special precautions in building practices. A series of studies currently underway in the Tucson area prompted by foundation failures and breaking, of buried service lines serve to illustrate some of these relationships between the geological environment and history, and engineering problems.

Jan 1, 1963

By F. H. Muge

The problem of how to handle heterogeneous populations in an ore reserve global estimation arises in many geostatistical studies. In some cases it is possible to split data into different significant types of ore in such way that non-overlapping subpopulations are obtained, and a separate study is possible. In other cases the subpopulations are intermingled and a set of nested structures may model the spatial variability of the ore. Finally, one of the populations, consisting of a small proportion of high grade values of economical meaning, may disturb the structural analysis. In this paper, some methods are proposed to cope with these kind of problems and typical case studies are presented.

Jan 1, 1986

By R. L. Grayson

Compliance standards for respirable dust, which are reduced because of high quartz concentrations, have become an industry-wide problem. Research on the physical and chemical character of quartz-classified particles in respirable coalmine dusts indicates that they mine exist in intermixed layers or may be coated by clay or coal material. The relative amount of intermixing varies with the coal seam being mined. If most of the quartz particles of a mine dust are "pure," then the dust may have a high fibrogenic risk potential because of truly free silica and the compliance standard should be lowered. If, however, the quartz is locked inside another material matrix or coated, a reduced compliance standard may not be appropriate.

Jan 1, 1992

By Brij M. Moudgil, Shoulian Zhu, J. L. Pinault

A new technique, prompt neutron activation probe (PNAP), for analyzing phosphate rock slurry in-situ was evaluated both in the laboratory and at the plant. The technique yielded a high precision in the analysis of Ca, Si and H using 252Cf source. Low accuracy of the direct measurement of P using 241Am/Be in the laboratory tests was attributed to the interference of rare earth elements present in the samples, particularly Gadolinium. No significant effect of variables such as solids loading, particle size distribution, and flotation reagents was observed on the probe performance. The probe can detect the compositional changes of the feed, tailings and the concentrate streams in the plant.

Jan 1, 1993

By Hassan El-Shall, M. N. Ahmad, Ponisseril Somasundaran, C. R. Holland, G. M. Walker, N. Iles, R. D. Chandler, Regis Stana, B. Duddy, Patrick Zhang

Phosphoric acid is a major raw material for the production of ammonium phosphate (AP) that is used as an intermediate in fertilizer production. Impurities within commercial grade wet process phosphoric acid are important in producing a fertilizer granule with good handling properties. The impurities identified as being important are; iron (III), aluminium and fluorine-containing compounds. Results show that the viscosity of the AP slurry produced increases by increasing the amount of impurity in the acid. Bench scale tests have been successfully replicated on a plant scale leading to a better understanding of the composition of impurity levels within phosphoric acid required to produce a high quality, free flowing, hard, spherical and non-caking granular fertilizer.

Jan 1, 2002

By J. R. Sturgul

Computer simulation models of working mines can be of great benefit to the mining engineer. Such models have been used in mine planning (how many trucks/shovels to have, when to add new equipment, etc.), mine design (should a dispatch system be purchased, where is the optimum location for mine equipment, etc.). A simulation model can be thought of as a dynamic representation of the mine and can easily be changed to reflect a wide variety of different situation. Often a major problem for the engineer is how to present the results of the simulation study. Using PROOF(R) animation it is now possible to interface the results of the simulation and project them onto a computer screen in cartoon fashion.

Jan 1, 1993

By D. Robert Weir, Roman M. G. S. Berezowsky

Pressure oxidation can virtually always render refractory auriferous sulphidic ores and concentrates amenable to cyanidation. Its effectiveness as a pretreatment of refractory gold feedstocks is reflected by the successful startup and operation, over the past four years, of four commercial plants. At least three more are scheduled to come on stream during the next three years. Over the past eight years, a variety of ores and concentrates have been subjected to integrated miniplant testing and process demonstration by Sherritt, and data derived from these studies have been used in the design and construction of several of the commercial facilities. Some factors affecting the selection of pressure oxidation in gold recovery processing are discussed.

Jan 1, 1989

By Darold Woodward, Stefan Haydn, Petr Pospisil

Most fatalities in tunnel fires are caused by the spread of toxic smoke. Controlling the spread of smoke is crucial to provide a survivable environment for emergency egress. A properly designed and tuned feedback control loop is required to achieve a target flow that is slow enough to allow pedestrians to escape under different boundary conditions. Feedback control loops are also helpful in optimizing energy consumption under moving traffic conditions. A reliable feedback flow control system requires sophisticated engineering knowhow and experience, careful selection of instruments and controlled variables, and thoughtful implementation from design through field testing and commissioning.

Dec 1, 2022

By G. H. Matthes

Many mines, in particular coal mines, use inclines or slopes as an access to seam or seamlike deposits which outcrop at or close to the surface. In general, from the surface or from a certain depth, inclines or slopes follow the dip of the deposit with length up to 30,000 feet and by that going under an overburden cover of several thousand feet. The common outbye transport system for mine products is the conveyor. Material and men to be transported down into the mine are handled by rope driven systems when the angle of inclination exceeds the employment of locomotive traction. The transport volume can be sizeable and reach 200 to 300 tons of material and 500 men to be handled daily in a medium size coal mine with a production of 10,000 tons ROM.

Jan 1, 1986

By D. Yadon, P. Lee, W. Kelly, C. Stilwell

Rico is a small town in an old zinc mining district in a mountain valley of southeastern Colorado. Mine waste rock and mill “tailings” remained after over 100 years of mining in the area, leaving associated surface water and groundwater impacts. Atlantic Richfield Company is proposing an innovative approach, which uses lime precipitation and wetland ponds (semi-natural system, also called treatment lagoon in a wetland setting) to treat adit water in the Rico area. Besides using a non-conventional treatment approach, a non-conventional (non-Superfund) regulatory/administrative approach is being proposed. This paper will focus on the water treatment issues and solutions, as well as describing the innovative “watershed” regulatory process.

Jan 1, 2004

By William F. Butler

I propose to do three things today. First, take a broad look at the role of mining in the Latin American economy; then, review briefly the current situation in four principal metallic mineral exporting nations -- Chile, Mexico, Peru and Venezuela; and. finally, raise some, policy questions that seem to me to be important. The Role Of Latin America In World Mining First, let's consider Latin America's position in world mining markets. Latin America provides more than 5% of world output in 16 metals or ores, ranging from antimony and barite to Tungsten and Zinc. Latin America supplies a fifth or more of the world's antimony, beryl, bismuth, copper, fluorspar, silver and Tellurium.

Jan 1, 1962

By M. L. W. Tuttle, B. R. Berger

Our study focuses on the geology, hydrology, and geochemistry of a variety of molybdenum (Mo) porphyry systems. The systems are either high fluorine, granite, Climax-type, systems (e.g. Mount Emmons/Redwell Mo deposit, Colorado and Questa Mo deposit, New Mexico) or low fluorine granodiorite systems (e.g. Buckingham Stockwork Mo deposit, Battle Mountain, Nevada and Cannivan Gulch Mo deposit, Montana). The water quality of streams, natural springs, mine discharge, and ground water from drill holes were assessed in the region of these deposits. The ultimate goal of our study is to understand the environ-mental behavior of these Mo porphyry systems in the context of geologic setting, hydrologic regime, and climate.

Jan 1, 2004

By D. R. Babich, E. R. Bauer

Noise induced hearing loss (NIHL) continues to be a problem in the mining industry. New noise standards (Part 62) promulgated by the Mine Safety and Health Administration (MSHA) are aimed at reducing NIHL in the mining industry. The National Institute for Occupational Safety and Health (NIOSH) is conducting a cross-sectional survey of noise sources and worker noise exposures to address NIHL in mining. Noise surveys, including full-shift worker noise exposure and equipment noise profiling, have been completed in several surface coal mines, with an emphasis on draglines. The results of these studies are reported, their implications concerning worker NIHL are addressed, and their application to administrative and engineering controls is discussed.

Jan 1, 2003