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By Y. Ichihara, H. Matsumoto, K. Itakura, H. Eguchi, G. Deguchi, K. Sato

Mechanical data from a rockbolt drilling machine, such as torque, thrust, revolution and stroke, are useful for understanding the geological and geomechanical conditions around roadways and hence selecting the optimum bolt type and density. Laboratory experiments showed that the level of torque or thrust reflects differences in rock type, with separation of strata and cracks appearing as a specific pattern. Algorithms of neural networks based on adaptive resonance theory and back-propagation were used to extract the pattern and estimate the location of discontinuities. For field testing in an underground coal mine, a prototype data acquisition system was attached to a portable drilling machine. Several sets of logging data from one locality were combined to construct a two-dimensional model of the strata, from which the slope angles of discontinuity faces could be estimated

Jun 19, 1905

By E. Niehuis, J. Y. Kim, H. G. Cramer, S. L. Chryssoulis, K. G. Stowe, C. Bendel

TOF-SIMS was used to detect, identify from parent molecular ions and determine the relative concentrations of collectors sorbed on the surface of mineral particles in concentrate and tailings samples from three Canadian concentrators. In the Kidd Creek Zn circuit, sphalerite lost to tailings carried on average a quarter of the amount of isobutyl xanthate present on that recovered to Zn concentrate; amyl xanthate, which is not reported as added to the circuit, was also detected on floated sphalerite and pyrite. At Brunswick, sphalerite particles lost to the scavenger tailings had ten times less amyl xanthate and isobutyl xanthate than those recovered to the Zn final concentrate, while both xanthates were detected on sphalerite floated to the Cu-Pb cleaner circuit. At Matagami, significantly more isopropyl xanthate and isopropyl dithiophosphate were detected on sphalerite recovered to the final Zn concentrate than on that lost to the Zn rougher tailings

Dec 1, 1995

By M. K. Abd El-Rahman

A complete chemical analysis of the waste showed that it contains 15.64% P2O5; X-ray diffraction analysis revealed that it is composed mainly of francolite, calcite, pyrite, quartz and dolomite. The phosphate values were recovered and the settling rate of the wastes enhanced by the use of hydrocyclone and flocculation techniques. The hydrocyclone produced an underflow enriched in phosphate and an overflow enriched in clays. The former represented 39.8% by weight of the phosphatic clay waste and assayed 26% P2O5 at a recovery of 66.36%. The results of flocculation of the phosphatic clay waste showed that both the degree and rate of settling were increased and that the process water could be recycled. The settling rate was 37 times greater when anionic polyacrylamide A130 was used

Jun 21, 1905

By S A. M Crawshaw, J A. B Fortune

Trackless battery powered haulage vehicles have been in operation in British coal mines principally for longwall face transfer and personnel transportation. Changes within the industry have resulted in the introduction of room and pillar coal mining methods and the introduction of increasingly heavier longwall roof supports This has resulted in the introduction of: • Battery powered coal haulage machines, which, without the need for trailing cables, increase productivity within room and pillar mining. • Battery powered longwall shield haulers which are capable of carry ing the heaviest shield supports currently being utilised within the British coal mining industry. The conventional machines have been adapted from an American design to meet the requirem ents of European legalisation. This has seen the- emphasis being placed upon the supplier with the European M achinery Directive being introduced, necessitating the assigning of a 'C E ' m ark to each vehicle. Battery vehicle technology has advanced to meet the demands of the ever changing market and will no doubt he further adapted to meet the requirement of the British coal mining industry.

Jan 10, 1996

By M. A. Leosson, S. H. Bottrell, R. J. Newton

Sylvite at Boulby is mined 1 140 m beneath the sea and the mine suffers from the influx of water. This is of two kinds: persistent flows originating in the Sherwood Sandstone aquifer and entering the evaporite sequence through fractures in the intervening mudstone, and impersistent flows which are transient in nature and of uncertain origin. Water from the overlying sandstone has become enriched with NaCl and large amounts of KCl and some Mg and Br have been added by interaction with the evaporites. Waters from the transient flows are isotopically distinct from those in the Sherwood Sandstone, being enriched in H and O. They are also saturated with respect to halite and sylvite, but have higher K/Na than the persistent flows and are much more enriched in Mg and Br

Jun 18, 1905

By Winmill T. F.

Among the various theories proposed to account for the spontaneous ignjtion of coal, one which has at times been very strongly held is that the initial heating is due to the oxidation of iron pyrites. From the results described in this paper, it is possible to calculate roughly the rate of spontaneous heating of a specimen of finely-divided pyrites, on the assumption that all the heat developed is used in raising the temperature of the pyrites, and that none is lost. It is clear that where finely-divided pyrites occurs in considerable proportion among coal, it may be the chief factor in originating combustion, but that pyrites can only be the cause of a heating when it is present in considerable proportion, and in a very finely-divided state

Dec 1, 1916

By A Cox

It has been demonstrated that all the cadmium from spent batteries, typically 4 g per battery, can be recovered by burning polyvinyl chloride waste to yield hydrogen chloride; this reacts to produce volatile calcium chloride, which can then be condensed and collected in a separate reactor. Alternatively, chlorine may be used to chlorinate the cadmium with equal efficiency. There is also a prospect of using very low concentrations of these gases, less than 1%, to effect the separation. The Cd was recovered more quickly when exposed to sustained, controlled flow rates of chlorinating gases, whereas when PVC was burnt most of the gas was produced in a very short time, not allowing complete reaction. This problem can be overcome by recirculation of the gas into the reactor. The technology is efficient and clean and the equipment used is simple, enhancing the prospects for a pilot-scale version of the process

Jun 21, 1905

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 Eric Forssberg, Vigen Zeng

During mechanical grinding high intensity vibration is emitted that contains information on the mill's operating state. Tests, using a laboratory ball mill, studied the influence of operating parameters on the vibration signature. The parameters studied were: mill speed; powder filling; pulp density; grinding period; and pulp temperature. Vibration signals were detected by an accelerometer, amplified by a vibrometer and recorded onto digital audio tape. A digital oscilloscope converted the signals into IBM-compatible data format. Digital signal processing and multivariate data analysis were carried out with specially developed software. The power spectral density was estimated from the time-domain vibration signal. Four new latent variables were used to describe changes in the vibration spectra. A relationship was established between operating parameters and latent variables which could form the basis of a quick and automatic method of monitoring operating parameters in ball mill grinding.

Jan 4, 1993

By R. R. Liebenberg, M. I. Brittan

The kinetics of the copper segregation process has been investigated. The experimental strategy used to isolate the rate-controlling reaction step is described. This step was found to be the chloridisation of the oxide copper minerals in the ore. The link between the rate of chloridisation and the overall rate of segregation is demonstrated experimentally. The influence on the kinetics of the various parameters in a TORCO system is examined and the implications are discussed

Dec 1, 1971

By A. Sutherland Strachan

Before regulations governing the work on the mines, it was not uncommon in the Rand for a miner to die within a period of 2-3 years as the result of exposure to dust. This paper considers mine and tunnel conditions promoting silicosis and measures to avoid dust exposure in the Rand, South Africa.The relationship between blasting and lung lesions is explored. Evidence is presented that improved working conditions and lowered dust levels reduce the incidence of silicosis.

Jan 1, 1947

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 Mowat D. M., Louis H., Smith W. Mackey W. M., Dron R. W., Ellison C. C., Winmill T. F., Kerr G. L., Haldane J. S., Ashworth J., Garforth W., O'Shea L. T.

Discussion of Winmill's paper, including various anecdotal examples, is presented together with the author's response; topics included: the need to distinguish cubic pyrites from the rapidly decomposing rhombic form known as marcasite; the effects of moisture content in the coal and air; the possible effect of pressure; the heat insulation resulting from heap/stack size; and the means of determining pyrite and moisture contents

Dec 1, 1916

By S. G. Ozkan

An investigation was carried out into the effect of physical parameters, such as particle size of the sample, residence time, solid/liquid ratio and impeller speed in the flotation cell, on the solubility in soft tap-water of colemanite (calcium-bearing borate) from Emet, in Turkey. Solubility increased steadily with residence time from 5 to 20 min but only minimally thereafter. There was a similar increase with impeller speed from 500 to 1 500 rev/min, beyond which a solubility of around 1.05 g/l was again established. There was a slight decline in solubility as the solid/liquid ratio was increased from 1 to 30%, with stable values around 1.05 g/l at a 20% ratio, while a sharp decrease was observed with decrease in size down to the -20 micrometre fraction. The effect of solubility should be taken into account if the application of a wet-processing method is being considered for the ore, while it can also result in losses of material during handling and storage

Jun 21, 1905

By G. D. Schena, M Zanin

A numerical approach is presented for predicting the liberation of phases during comminution, with direct calculation of a liberation spectrum giving the fraction of the particulate system in each narrow size-composition class. The numerical model uses a Poisson flat process for stochastic generation of the non-convex three-dimensional Poisson polyhedral textures and the system of fractures that give rise to convex fragments. With this numerical approach, there is no need to assume random uniform isotopic fracture (lack of selective liberation); only computational geometry primitives are exploited for the derivation. The agreement with relationships obtained previously under the random uniform isotopic fracture hypothesis demonstrates that the approach is capable of deriving full liberation spectra directly. Both volumetric and superficial composition can be calculated

Jun 21, 1905

By J. Ivon Graham, T. D. Jones

This paper presents methods in use in British coal-mines for the suppression of dust. While the effect of present-day treatment will not be apparent for several years, in pits in South Wales, concentrations as high as 50 gm./1,000 cu. ft. were some years ago fairly common in various operations at or near the coal-face, with an average concentration of 20 gm./1,000 cu. ft. Now the average concentration in what were previously dusty pits is probably not greater than 3 gm./1,000 cu. ft.Nevertheless, every effort must be made to improve conditions still further. In South Wales it is claimed that 99% of the coal-faces requiring treatment have been dealt with either by wet cutting, infusion, or hand-spraying. The extent of the treatment by these methods can be gauged by the fact that the total length of coal-faces now being treated by water infusion in Cardiff and Swansea areas is about 33,000 yds., by wet cutting 25,000 yds., and by hand-spraying nearly 14,000 yds. The influence of methods of mining upon dust production is only mentioned very briefly in this review, and there is no doubt that much more is to be learned concerning this aspect. It can be stated, however, that good mining practice is essential to prevent unnecessary dust production, and the problem of dust in mines will be solved only by the closest co-operation between mine managers, workmen, and scientists.

Jan 1, 1947

By H. L. Willett

Wrapping up the symposium, covers incidence of spontaneous combustion in British mines, assessment of liability to spontaneous combustion, precautions, rate of advance, starting a line of a coalface, local heatings at roadsides, burying packs, coal headings, retreating longwall, detection and sealant coatings.

May 23, 1905

By S. P. Mishra, G. R. Chaudhury

The adsorption of Cu2+ ions by Penicillium sp. displayed a dual rate, with an initial faster phase followed by a slower one. The adsorption rate increased with increasing pH due to chemical and biochemical reactions. The Cu-loading capacity of the biomass increased at higher initial Cu2+ concentrations. Above 40 degrees C the adsorption rate decreased which may be due to partial hydrolysis of biopolymers which are essential constituents of the cell wall. Adsorption kinetics followed the Freundlich isotherm and the equilibrium concentration that was calculated on the basis of the isotherm matched the observed value well. A series of theoretical adsorption curves were produced using mathematical correlations between the mass transfer coefficient, the Cu2+ ion concentration at equilibrium and at time t. The correlation between the theoretical and observed adsorption rates for different experimental conditions was good. It was concluded that the results from the study were best explained using a mass-transfer adsorption model

Aug 1, 1995

By G. R. Doughty

It is shown that sodium can be removed very readily from molten aluminium by the use of a beta"-alumina, the more highly conducting form of beta-alumina, provided that the surface of the tube is wetted by a layer of salt. From current/time plots the theoretical amount of sodium removed has been calculated and excellent agreement obtained. The beta"-alumina tubes can be immersed directly in the Al without fracturing if they are pre-heated for a few minutes prior to immersion. According to its stability beta"-alumina should be attacked by molten Al at low Na contents, but in these experiments the salt acted as a protective layer. Magnesium chloride is a relatively cheap salt, whose Mg product can be used within a foundry. The only other product is NaCl, which can be used in-house as a flux or sent for disposal. No polluting gases are used or produced and no drosses created. The time for removal of sodium was quite short, comparable to that for chlorination

Jun 21, 1905

By F. J. Tavera, J. A. Finch

A probe suitable for on-line measurements of gas hold-up in industrial flotation systems has been developed. It is based on an open cell for measurement of slurry-gas conductivity and a novel syphon cell for measurement of slurry-only conductivity. The desired behaviour of the two cells was demonstrated and estimates of gas hold-up were shown to be in good agreement with independent measurements. The gas hold-up probe was used as a diagnostic tool to assess the operation of flotation columns. Differences in gas hold-up between baffled sections in two industrial columns were detected

Jun 18, 1905