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By R. F. Holub, P. J. Dallimore

Basic to solving the problem of the role of radon transport on radon concentrations in mines is to establish whether it occurs primarily as diffusion and forced flow through porous rock or through fissures in the rock. The laboratory experiments performed involved measurements of diffusion and emanation coefficients, porosity and permeability of representative rock samples. Significant differences have been found when comparing the results of the laboratory permeability determinations to those of the mine determinations. Considerations of underlying principles, however, suggest that the diffusion and emanation coefficients are the same in laboratory and mine. It was also found that moisture content plays a dominant role in radon transport through rock. Using these concepts and findings, some conclusions about the radon concentrations in mines have been drawn.

Jan 1, 1981

By Odin D. Christensen

Gold deposits of the Carlin Trend occur within sedimentary rocks deposited across the Paleozoic continental margin. Lithologically dissimilar units, juxtaposed along the Roberts Mountains Thrust Fault system, constitute three distinct stratigraphic packages: autochthonous miogeoclinal carbonates, allochthonous eugeoclinal siliciclastic rocks, and an overlying coarse clastic overlap assemblage. Gold deposits occur within all three stratigraphic packages, with economic concentrations localized at structural and stratigraphic settings similar to those which host petroleum traps. Along structural breaks, gold is selectively concentrated within favorable stratigraphic units. Host stratigraphy controls the character of the ore, including average grade, grade variability, physical properties and metallurgical response.

Jan 1, 1989

By T. van Sandwijk, G. Van Weert, E. Molleman

This paper reports on test work that explored the dissolution/precipitation reaction: ZnS + 2HCl - ZnC12 + H2S, which is part of a process used in the production of pure ZnS. The research focused on the influence of proton activity on the dissolution of zinc concentrates obtained from the Brunswick Mine No. 12 in Canada (Brunswick Mining & Smelting); the Red Dog deposit in Alaska (Cominco Ltd.); and the Tara deposit in Ireland (Outukumpu Zinc). A comparison between the results of the experimental dissolution as a function of pH and the dissolution predicted by thermodynamics suggest that the three concentrates contained sig¬nificant amounts of the more reactive mineral wurtzite, although XRD analysis showed mainly the presence of the mineral sphalerite.

Jan 1, 1999

By Ed Van Eeckhout

The rockburst monitoring system at the Sunshine Mine has recently been improved to increase the certainty of burst locations and to output location results in a manner amenable to easy interpretation. Three methods of location calculation were used: a computer code provided with the hardware in-place (the MP-2501, a code based on the least-squares method (Blake et a1, 19741, and a nonlinear iterative code written by the principal author. The more accurate locations are given by the latter two codes, but still are only correct to within about 100 ft. This error is due to uncertainties introduced by the geologic and mining variations versus the assumptions made in the location codes. Software was then written to make two-dimensional plots of burst location by level, so management could monitor problems easily.

Jan 1, 1986

By I. S. Parrish

Gold deposits in Hebei and Shanxi provinces in northeast China fall into three general classes: - Placer deposits - Mesothermal vein deposits - Disseminated and oxidized volcanogenic deposits Past production dating back thousands of years has all but exhausted the placers. The mesothermal vein deposits, incorrectly considered in the past as "greenstone" type, are small to moderate in both size and grade. Production from these granulite and amphibolite hosted veins, at present greater than from the newly discovered disseminated deposits, is expected to wane. Production from the disseminated deposits achieved only in the past few years is expected to equal or surpass that from the other classes of deposits. At least one "world-class" deposit is being developed.

Jan 1, 1989

By C. Orf. Chukabarah

Erratic behavior in convergency during iterative numerical-method evaluation of mine ventilation fan characteristic curves is one of the common problems encountered in mine ventilation network analysis. Five different sets of mine fan data points, that had resulted in unsatisfactory fan characteristic curves, were re-analyzed in the present study, using an embedded mine network optimization computer program. Current results revealed that all five fan data sets not only can be satisfactorily fitted as Yang (1992) did with MFIRE subprogram, but can further be optimized with unique solutions as implemented in the present study. It was concluded, inter alia, that the improved MFIRE-based mine fan curve-fitting computer subprogram (SPLINE) produces satisfactorily similar fan curves as SPSS-based curve-fitting algorithms, including when the latter method uses either standardized or unstandardized fan curve data sets.

Jan 1, 1993

By V. Srajer

The loading and hauling equipment simulation model was developed to satisfy, the requirements and need of the mining industry in western Canada. It is expected the model will be used to determine the' impact of various combina¬tion of loading and hauling equipment, company policies and maintenance procedures, haulage requirement, to evaluate possibilities, of the use of truck monitoring and dispatch systems, and to access loading and hauling equipment productivities. To evaluate the model, and to access its capabilities in addressing the above requirements, the model was validated. The validation was based on the following: 1. Running the model in-house to evaluate its structure, 2. Running the "test case" by timing models developed elsewhere to compare the results of simulation, 3. Soliciting of model critique from outside agencies, and 4. Comparison of calculated data with real time study data. The presented paper provide overview of the validation processes and summarize" results obtained during comparison and evaluation studies.

Jan 1, 1989

By Z. Zhang, R. G. Reddy

The viscosities of industrial lead slags of varying compositions were measured as a junction of temperature using a Brookfield viscometer. Based on the experimental data obtained from this study and based on other investigations reported in the literature, an expression was developed to correlate the viscosities of industrial lead silicate slags as a function of composition and temperature. The effect of each individual slag component on the variation of the slag viscosity is identified. The composition dependency of lead silicate slag viscosity is discussed. The calculated results using this viscosity expression are in good agreement with the measured data. Key words: Viscosity, Lead silicate slags

Jan 1, 2003

By K. L. Branham, D. W. Steeples

Surface collapse over abandoned sub- surface coal mines continues to be a problem in many parts of the world. High-resolution P-wave reflection seismology was successfully used to locate water-filled cavities in a 1-m (3-ft) thick coal seam at depths of 9 m (29 ft) in southeastern Kansas. A dominant frequency of 275 Hz was attained enabling us to delineate the top of the coal seam. To our knowledge, this study is one of the first to locate water-filled coal mine cavities at depths of less than 30 m (100 ft) wing high-resolution P-wave seismic reflection techniques.

Jan 1, 1987

By J. Ragot, D. Maquin, N. Heraud

Acquisition of coherent and representative data about the state of processes remains a major problem of process control. This paper proposes an approach that ensures coherence in measurements on an operational industrial process. The basic technique employed relies on balance equilibration of resource mass flow. An interesting particularity of the set up is the ease with which it can be adapted to check productivity or detect sensor failures. In the case of sensor failure, it suffices to examine the evaluations before and after balance equilibration. The algorithm was tested by means of computer simulation using data from an industrial metallurgical flowsheet.

Jan 1, 1992

By A. J. Surtees, M. P. Evans

This paper discusses the development and application of sophisticated monitoring equipment used to measure the operating parameters of conveyor systems. With the radical reduction in price of computer hard- ware and software during the last decade and an associated increase in memory capacity, the concept of continuous conveyor monitor is now a reality. With this tool, the various problems normally encountered in large conveyor installations can now be avoided at an early stage. • The four main areas of application are: • Design verification • Hand-over certification • Preventative maintenance and increase of system availability Failure analysis The paper introduces the techniques used and gives examples where the service has been used.

Jan 1, 1996

By B. Cristol, G. Benier

Laboratory and pilot tests have shown that the grinding of some aluminas makes two populations appear : agglomerates’ and ultimate crystals’. Classical breakage functions (Size Mass Balance Method) aren't able to describe correctly this kind of grinding. So we have optimized a particular breakage matrix which takes into account the fact that the agglomerates can either be reduced in size or either be blown up to liberate the ultimate crystals. The models which were developed using this breakage matrix are in good agreement with the experimental results of the pilot tests. The industrial breakage functions were estimated from pilot breakage functions, using scale up prediction procedures and plant tests. The agreement between predicted and actual plant performance is excel1ent.A 20 % increase in capacity was predicted to be available by improving the grinding circuit classifier performances.

Jan 1, 1992

By M. S. Celik, A. Aslanbas, B. Pehlivanoglu, R. Asmatulu

The principal impurities in some feldspar ores are titanium and iron, which impart color and degrade the quality of the ore. Mineralogical investigations indicate that, while titanium originates mainly from rutile with small amounts of sphene, iron originates mainly from mica minerals. Fatty acids, particularly oleic acid, are extensively used, with reasonable success, in the flotation of colored minerals from feldspar ores. In this study, potassium oleate, oleoyl sarcosine and hydroxamate were used to float colored impurities both before and after magnetic separation. Oleoyl sarcosine is found to exhibit better results compared to other reagents. Magnetic separation followed by flotation is found to produce a feldspar concentrate of superior grade.

Jan 1, 2002

By W. E. L. Minter

The most important Witwatersrand gold placers occur on extensive unconformity paleosulfaces that were produced during protracted periods of fluvial degradation. The erosional etches on what was generally unlithified sub-strate indicate that low sinuosity erosion patterns prevailed. The transport systems were dominantly braided fluvial with a minor debris-flow component. The placer sediments were non-cohesive sands and gravels. They were evidently transported by fluctuating, yet perennial, discharges across extensive, low relief braid plains, not far from littoral environments. Progress made in understanding heavy mineral transport processes now emphasizes the importance that selective entrainment probably had in producing concentrations. Cognizance that these characteristics are not unique to the Witwatersrand should be taken into account when designing exploration models.

Jan 1, 1991

By Edward R. Torak

The Ohio Coal Testing and Development Research Facility (OCTAD) was commissioned in 1992 by the Ohio Coal Development Office and the Ohio Power Company to support evolving process technologies that will lead to increased environ- mentally sound use of coal. OCTAD is equipped with advanced physical concentration devices and processes capable of beneficiating coal to levels beyond conventional practice. The first task of OCTAD operators was to test the cleanability of the Meigs Creek Seam Coal in advanced circuitry and compare the results to conventional cleaning levels. In testing the seams, OCTAD circuitry was configured to produce middlings on the coarse and intermediate size fractions. These middlings were subsequently crushed to a finer size (28M x 0) and subjected to cleaning in fine heavy-media cyclones and advanced froth flotation circuitry. Nearly thirty-six full-scale production runs at various operating conditions were completed during the campaign. The results of the test program are examined in this paper.

Jan 1, 1995

By Frédéric Flament, Daniel Hodouin, Claude Bazin

A control strategy is proposed to meet the following specifications of flotation control: minimize the variations of concentrate and tails grades and recovery while limiting the amplitude of variations of the manipulated variables. The strategy consists of determining future control actions which optimize a performance criterion over a limited time horizon. The desired dynamic behaviour of the controlled flotation plant is specified using reference models. The strategy is tested on a 2-computer plant simulator working in an environment which emulates the industrial conditions.

Jan 1, 1993

By Paul M. Godlewski, Gerry Millar, Harvey W. Parker

Recently, over 70 railroad tunnels in the western USA have been enlarged and rehabilitated "live track," utilizing modern excavation and lining methods, in most cases to clear the larger double-stack container cars. This paper presents the general conditions of the tunnels and the technical aspects and costs of the rehabilitation of approximately 40 kilometers of tunnels, which range in length from a few hundred meters to 13 kilometers. Concrete-lined tunnels were rehabilitated by grouting and rock bolting, while unlined or timber-supported tunnels were relined with shotcrete and rock bolts. High output lining methods were required because of limited track time. Enlargement has been accomplished primarily by carving notches out of the concrete linings with a roadheader, or occasionally with saws. Unlined tunnels were enlarged by drill-and-blast or roadheader excavation.

Jan 1, 1991

By K. A. Natarajan, Namita Deo

Strains of Bacillus polymyxa, preadapted and grown in the presence of corundum, were found to be capable of the efficient separation of hematite from alumina. Results of tests performed using binary hematite-corundum and ternary he- matite-quartz-corundum mixtures in the presence of cells and metabolic products separated from the adapted bacterial culture indicated that more than 99% of the hematite could be efficiently separated through selective flocculation after desliming. It was found that alumina-specific bioproteins and other nonproteinaceous compounds were secreted by bacterial cells after adaptation to the mineral. The utility of this bioprocessing is demonstrated in the removal of iron from bauxite ores through selective

Jan 1, 2000

By D. O. Shah, K. C. Adiga

Flotation of coal after multistage addition of frother was found to yield coal fractions with significantly lower ash content as compared to the feed. Ignition and combustion characteristics of different coal fractions were evaluated using a differential thermal analyzer (DTA). A correlation between low ash content, low specific gravity, and high reactivity of coal was observed. It is suggested that in the ignition stage, removal of mineral matter enhances reactivity through the physical changes brought about by ash removal. A detailed analysis of pre-ignition kinetics indicated the possible effect of bulk density of coal in terms of resistance to volatile release and effective (available) surface area of coal. In the char combustion stage, mineral matter seems to influence reactivity through catalytic activity of surface concentrations of metal ions, ratio of combustible/non- combustible material, internal pore structure, and surface roughness.

Jan 1, 1988

The definition of sustainable development is often taken from the so-called “Brundtland” report, requiring that activities of the current generation not detract from the potential welfare of future generations. Mining is often held up as unsustainable in this regard, since the extracted resource is non-renewable. Yet Brundtland’s definition of sustainable development also requires that the current generation address the disparity in welfare across the globe, a facet of Brundtland’s report that most have ignored. This paper examines the impact of mining on the welfare of the poor, empirically assessing mining’s contribution to this second facet of sustainable development.

Jan 1, 2004