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By P. H. Carr, G. G. Marino, K. A. Patel

Extensions to a correctional institution at Wabash Valley, Indiana, required development over abandoned coal-mine workings, at 90 m depth, where subsidence was possible at surface. Backfilling of the flooded mine in critical areas was determined to be the most cost-effective method of limiting the risk of damage to the buildings. Containment grout was first placed in selected entries and cross-cuts of each mine area; the remaining volume was then filled with a readily flowing infill grout. Where a high proportion of an area was taken up by rubble, calcium lignosulphonate was used as a retarder and plasticiser to increase penetration. Grout movement was monitored from adjacent boreholes with an electrical resistivity probe during grouting, while after the work was finished core samples were obtained from verification holes drilled in the backfilled areas

Jun 19, 1905

By S. P. Godby, S. P. Sharples

Wind-tunnel tests were carried out of the conditions under which nuisance dust particles (100-1 000 micrometres) become entrained by wind. A laser entrainment monitoring system (LEMS) was used, and was found to provide an accurate means of assessing nuisance dust emissions from a surface. Accurate determination of the threshold entrainment velocity of dusts using the LEMS gives a baseline against which the performance of dust control techniques can be evaluated. Minerals tested included coal, petroleum coke, limestone, sand and pulverised fuel ash. Pilot field trials of a portable wind tunnel equipped with the LEMS have been successfully completed, providing a means of validating laboratory results in the field

Jun 19, 1905

By A. E. Tercan, D. Mamurekli

Ordinary kriging on the assumption of a gaussian error distribution and indicator kriging were used to derive the probability that a given calorific value would or would not be exceeded by coal from an area of a deposit. The two techniques led to similar probability maps despite local differences; the lack of an absolute reference makes it impossible to judge which method is better for this particular application

Jun 19, 1905

By O. Dojcar

The results of a laboratory investigation of rock fragmentation conducted with a model material were partially verified under field conditions. The object of the investigation was to study the qualitative and quantitative relations between the parameters of the primary blast and fragmentation to enable the planning of an economically efficient degree of disintegration with optimum utilisation of the blast energy. The three blast parameters that were considered were burden, specific charge and the ratio of spacing to burden

Jan 1, 1991

By I S. Lowndes, K. Moloney

Diesel powered equipment is currently used extensively in mining and tunnelling operations around the world due to its mobility, flexibility and through selective application to enhance productivity. However, the increased use of diesel equipment has exacerbated the pollutant load (including heat, humidity, exhaust gases and particulates) placed upon the environmental systems of many underground operations. This expansion in the use of diesel equipment has prom pted researchers to evaluate m easure ment and control technology. This paper reviews the recent research conducted in various countries.

Jan 10, 1996

By R. A. Halatchev

A risk model for assessment of the uncertainty in the forecasts of the planned profit is developed. It is based on the selling price of the metal recovered from the ore and the production per shift of the excavators. These two critical variables characterise the economic and technical aspects of the mining venture. Time-series methodology is used to describe the behaviour of the economic variable, which improves the adequacy of the modelling. A hypothetical open-pit gold mine is used to illustrate the application of the model. Results obtained show that the model is a good alternative to sensitivity analysis in taking account of the stochastic character of the price of the metal recovered from the excavated ore and the production per shift of the excavators used. The model can be extended by the inclusion of new variables that have a probabilistic nature

Dec 1, 1996

By R. D. Stewart

Paper presented at the conference: Risk assessment in the extractive industries, held in Exeter, UK, 23-24 March 1994, and first published London: IMM, 1994, preprint volume, 18pp., 5 refs. A seismic risk assessment method has been developed for application to rockburst prone deep-level mining sites which have sufficient seismic coverage. The technique utilises several seismic hazard parameters simultaneously and assesses the seismic risk on a daily basis according to the individual levels of these parameters. Critical levels are determined from investigation of the long-term behaviour of the parameters in relation to recorded potentially damaging seismic events. The method has been applied to a data set comprising 15 months' worth of seismic data, with encouraging results

Aug 1, 1995

By W. P. C. Duyvesteyn, B. J. Sabacky

Reprinted with revisions from Extractive metallurgy of copper, nickel and cobalt, volume I: Fundamental aspects. ed. Reddy R.G., Weizenbach R.N. Warrendale, Pennsylvania: The Minerals, Metals and Materials Society, 1993. Development work on the Escondida process, concluding with the successful operation of an integrated leach-SX-EW pilot plant and a pilot flotation plant for the upgrading of leach residues, demonstrated that all major process objectives could be achieved. Extraction of 40% of copper in concentrates containing monovalent copper was achieved with essentially no oxidation of sulphide sulphur. The Cu contents of leach residues from four different types of concentrate were successfully upgraded to the original feed grades, giving a product that has potential as a high-quality concentrate for the smelter market. A compact solvent extraction section effectively recovered the ammonia lixiviant for recycling to leaching and selectively transferred Cu into a conventional acid sulphate electrowinning system. High-quality "six-nines" copper cathode was produced on commercial-scale stainless steel blanks, demonstrating that the process will be able to compete effectively in the premium cathode market

Dec 1, 1995

By P. J. Rowsell, M. D. Waller

Paper presented at a meeting on: Artificial intelligence in the minerals sector, held in Nottingham, UK, 20 April 1993. The applications of artificial intelligence systems in the upstream petroleum industry are reviewed. Particular emphasis is placed on current and potential applications in drilling engineering. Several recent advances in drilling technology have led to a large increase in the quality and volume of data available. This combined with the escalating cost, particularly of off-shore operations, is testing the traditional reliance on the skill and judgement of rig operators. AI systems offer enormous scope in enhancing and aiding the performance of these operations

Apr 1, 1994

By A. P. Whittlestone, J. D. Johnson, R. J. Pine, M. E. Rogers

standpoint. The effect on efficiency of collisions

Apr 1, 1995

By Jinsheng Chen, S. S. Peng

The relationship between support performance parameters and parameters representative of mining and roof conditions is characterised by uncertainty, non-linearity and dependence, so the theory of artificial neural networks was selected as a basis for shield design. A computer program based on a back-propagation training algorithm was written to derive the weighting factors between inputs and outputs from field data; once these had been established two mathematical models were developed to describe the relationship. Back-calculation of field data indicates that the results generated from the neural network models are much more accurate than those derived by traditional methods and can be used with a higher level of confidence. The support density, possible yield frequency of face supports and interval of periodic roof weighting under specific mining and roof conditions can be determined by application of the models

Jun 21, 1905

By G. S. Camm

Gwynfynydd is a small, high-grade black shale-hosted vein-gold deposit. The Chidlaw Link Zone is the only area being mined and contains 24 000 t ore grading 15.2 g/t gold. Within the Link Zone a complex vein structure occurs consisting of a mother vein up to 5 m thick and narrow (less than 0.5 m) leader veins. The former shows minor variations in dip, strike and thickness, whereas the latter show marked changes in all three. The leader veins are hosted within the footwall zone of the mother vein and both are composed of quartz with galena, sphalerite, chalcopyrite, pyrite and minor arsenopyrite. The vein system is transected by a series of cross-vein and intra-vein dip-slip faults. Pockets of gold occur at vein intersections or branches and within the complex footwall zone and are often related to variations in vein attitude and/or geometry. The Chidlaw Link Zone displays a complex, erratic distribution of gold mineralisation and a multi-stage history of structural activity, fluid flow and mineral deposition

Jun 18, 1905

By F. M. Vokes, P. M. Ihlen

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. Ore deposition was related to three major stages: continental rifting and separation (Vendian-Late Cambrian), convergence (Late Cambrian-Early Silurian) and collision (Early Silurian-Devonian). The first stage included deposition of volcanogenic massive sulphide Zn-Cu and stratabound or stratiform Fe and Zn-Pb(-Cu) on continental margins, as well as less economic Nb and Fe in carbonatites, U, Mo, Ni and V in Alum Shales and orthomagmatic Cr, Fe-Ti and Ni(-Cu). The numerous volcanogenic massive sulphides formed during convergence included Early Ordovician Cu-Zn, mature-arc Cu, Zn, Pb and Fe-oxide deposits, Besshi-type deposits dominated by Cu or Zn in gabbro-intruded sediments and minor Cu-Ni(-PGE), Cu-Mo and skarn deposits. The collisional stage is represented by epigenetic deposits including sandstone Pb deposits (Pb, Zn, Ba, F and Cu) and minor vein deposits with variable Au, Ag, Pb, Cu, Zn, Fe, As, Sb, W and Mo

Jun 19, 1905

By J. Hurdley, J. A. Plant, H. Robotham, P. R. Simpson, G. C. Lalor

Paper presented at the 28th International Geological Congress held in Washington DC, July 1989 (International geochemical mapping sessions). The results of orientation studies for a regional geochemical survey of Jamaica and the CARICOM countries of the Caribbean region are described. The survey is designed to provide systematic geochemical information for a wide variety of applications and, especially, to form a basis for agricultural development in the region

Jul 1, 1991

By J. S. Duval

Paper presented at the 28th International Geological Congress held in Washington DC, July 1989 (International geochemical mapping sessions). The compilation of the National Uranium Resource Evaluation aerial gamma-ray data to produce maps of the apparent surface concentrations of potassium, uranium and thorium for the conterminous USA has resulted in a reasonably accurate representation of the distribution of these elements in the surface rocks and soils. This claim is supported by the general agreement between the mapped geology and the patterns seen in the data

Jul 1, 1991

By S Colak, M Tunc, C Celik, M. M. Kocakerim

The most important parameters affecting the solubility of ulexite (sodium calcium borate) in H2SO4 were found to be reaction temperature and solid:liquid ratio, in that order. Dissolution increased with increase in temperature and stirring speed and with decrease in solid:liquid ratio, particle size and acid concentration, the last effect as a result of decreased precipitation of CaSO4 on unreacted particles. Optimum conditions, in which around 99.5% of the ulexite could be dissolved, were a reaction temperature of 60 degrees C, a solid:liquid ratio of 1:8 g/ml, an acid concentration of 8 mol/l, particle size smaller than 425 micrometres, a stirring speed of 52.33/s, a reaction time of 1 800 s, a calcining time of 3 600 s and a calcining temperature of 170 degrees C. These conditions, determined by the Taguchi method, are reproducible in a commercial production environment

Jun 21, 1905

By D. M. A. Flight, G. E. M Hall, P. R. Simpson

theoretical viewpoints.

Apr 1, 1994

horizontal-type classifier prior to charging into a blastfurnace.

Apr 1, 1995

By J. A. Hudson, X. D. Pan

A rock mass responds to excavation according to the properties of the intact rock, the network of contained discontinuities and the susceptibility of the rock mass to weathering. Large deformation often occurs when one of these components causes the rock mass to have a low strength relative to the stress conditions. Analysis of such large deformations forms a significant feature of current numerical modelling in rock mechanics. A practical large deformation problem of roadways in a coal mine is described, demonstrating the requirements for improving numerical techniques. The development of a numerical model is then summarised with particular attention to several concepts pertinent to large deformation analysis in geomechanics. A numerical case study is presented in which the developed finite-element model is used and the results are compared with the in-situ measurements. Conclusions are drawn for rock engineering that are also relevant to both civil engineering and mining engineering projects

Sep 1, 1991

By J. L. Robson, C. M. Bristow

mass flow rates of particles and air (the loading ratio).

Dec 1, 1994