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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

The following procedure was used to determine cut-off grades: define the orebody profile; plan the stope layout and quantify the work involved; formulate equipment-performance norms; calculate unit costs; input process recoveries and metal prices; and calculate the cut-off grade. Use of the method is illustrated using data from a copper mining complex in India. Results from the study led to the following conclusions for underground mines in general. Cut-off dependent costs vary significantly with the stoping method employed, orebody thickness, the degree of mechanisation and the working efficiencies of the workforce and equipment. This applies even within the same deposit. Sub-level stoping and its variants can be operated at a lower cut-off grade than cut-and-fill and its variants. Thinner orebodies affect cut-off grades adversely, but with thinner orebodies very little further reduction in cut-off grade can be achieved once a certain minimum width has been exceeded. For the same stoping method and in the same mine the cut-off grade varies with the degree of mechanisation. Labour-intensive methods require higher cut-off grades. An allowance for working efficiency should be made when calculating cut-off grades. Higher process recoveries allow a significant lowering of cut-off grades

Jul 1, 1996

By Tawsaporn Nuchanong, Ian Nichol

Investigations of the dispersion of gold in soils and stream sediments associated with three gold deposits in Thailand indicate the existence of different geochemical dispersion patterns in the three areas, demonstrating the need for the adoption of a variety of exploration techniques. The three gold deposits which were investigated were the Phu Tham Phra-Phu Thong Daeng copper-gold prospect, the Doi Tung and the Huai Hin Lab gold prospects. Overall the investigations at the three localities demonstrate clearly that the chances of exploration success can be significantly enhanced if composite soil samples are analysed to ensure a more reliable estimation of the gold content in soils and if both the 63 micrometre fraction and the field-panned concentrates of stream sediments are analysed because of the variable grain size of the gold characterising different gold deposits and surface environments.

Jan 4, 1992

By D. J. Fray, F. Tailoka

Microporous ceramic tubes (15 micrometre pore diameter) and PVC membranes (10 micrometre diameter) have been used as spargers in the electrowinning of copper from concentrated and dilute chloride electrolytes. At a current density of 600 A/m2 and a nitrogen gas sparging flow rate (at NTP) of 1.53 cm3/s per unit electrode length, it was possible to electrowin planar rather than powdery deposits with copper concentrations as low as 0.157 M. To obtain a planar deposit at higher concentrations of cupric chloride the most realistic optimum current density appears to be between 1 000 and 1 500 A/m2.

Jan 4, 1993

By R. E. T. Hill

"A laboratory study was undertaken to determine the condensed equilibrium phase relations at 600°C in that portion of the quaternary Fe-Ni-Cu-S system which lies in the neighbourhood of the monosulphide solid solution (MSS). The study sought to determine to w hat extent copper affects the temperatures of stability and compositions of iron-nickel sulphides in bulk compositions similar to those of massive Fe-Ni-Cu ores. Experimental data, including stable phase assemblages and phase compositions, are presented.In the quaternary system at 600°C MSS forms stable phase assemblages with pentlandite, chalcopyrite solid solution, pyrite and vaesite. Over the range of bulk compositions displayed by natural ores copper as well as metal/sulphur ratio have a significant effect on the thermal stability of pyrite and pentlandite. Errors therefore accompany the widespread practice of ignoring copper or chalcopyrite when the mineralogical and compositional changes that have accompanied the initial cooling of primary magmatic sulphides or their subsequent homogenization during isochemical metamorphism are being deciphered. These errors are most significant for ores the bulk compositions of which lie tow ard the sulphur-deficient side of the cupriferous MSS. Temperatures as much as 300°C above the copper-absent value are possible for the interpreted upper stability limits of pentlandite in these ores.The experimental data show that up to 2.0 at% copper can occur in pentlandite stable at 600°C in a bulk composition equivalent to natural magmatic ores. This is equivalent to nearly 10 vol% chalcopyrite. Pentlandite contains more copper than coexisting MSS and the copper content of both phases increases with increasing iron."

Jan 1, 1984

By Groom P.

Discussion of the paper presented at the Midland Institute of Mining, Civil, and Mechanical Engineers' general meeting held in Leeds, March 21st, 1916, with T. Beach, vice-president, in the chair included contributions by Beach T., Fearnsides W.G., Lloyd W.D., Gill J. and Nadin R.

Dec 1, 1916

By G. Merrington, B. J. Alloway

Tailings from three historical mining areas in the UK were leached in columns under a simulated weathering programme which was chosen to represent periods of 1 and 2 years at 3 different ambient temperatures. The total concentrations of Cd, Cu, Pb and Zn in the primary ore minerals present in the tailings showed only a limited correlation with metal concentrations in the leachate. The leachate from columns of tailings that were maintained at a temperature of 25 (+/-3) degrees C contained, on average, 50% more Pb and 75% more Cu than leachate from tailings that were maintained at a temperature of 10 (+/-3) degrees C. The pH values of leachates from all three types of tailings at 25 (+/-3) degrees C were 0.2 units lower than those from columns maintained at 10 (+/-3) degrees C. The concentration of Cd and Zn in the tailings leachates showed no marked difference at the different temperatures. The composition of the leachate was found to be dependent on the type of gangue mineral, the presence of other sulphide minerals and the formation of secondary iron minerals. A comparison of the concentrations of heavy metals in the leachates produced in the laboratory with those in leachates that were collected in the field over a similar period of time from two of the mine sites showed that concentrations were of a similar order.

Jan 8, 1993

By T. F. Bamber

The South Nottinghamshire Area has not been greatly troubled by spontaneous combustion until the last few years, during which the Blackshale Seam has been developed and exploited. The problem was first encountered at a colliery which was heavily preoccupied with a major reconstruction scheme, and with the sudden appearance of a completely new hazard both men and management had to adapt themselves very quickly to meet the situation. The paper contributed to the Symposium by the South Nottinghamshire Area illustrates the problems by reference to actual incidents, and shows how the lessons learned from them have been applied to the shaping of future policy on the avoidance and treatment of spontaneous combustion.

May 23, 1905

By A. D. Read

Selective flocculation was investigated as a possible method of recovering values from mineral slimes which are too finely divided to be treated by conventional mineral processing methods. It has proved possible to flocculate selectively either haematite or a silicate from a stably dispersed mixture by varying the anionic character of the high-molecular-weight, partially hydrolysed polyacrylamide employed. Different separation methods have been developed for hard and soft water media. Electrokinetic and infrared techniques have been employed to elucidate the mechanism whereby selectivity has been attained in the different cases. The following influences on the various selective flocculation parameters have been investigated: (a) the level of the different reagent additions and (b) the shear conditions during and after flocculant addition. A feature of the particular system studied was the high solids content at which it was possible to achieve good selectivity. Probable reasons for this are advanced, and the possibilities and potentialities of the process are discussed.

Dec 1, 1971

By R. I. Jeffery, J. W. Summers

An account is given of the verification and calibration of a numerical modelling technique that has been developed for the prediction of subsurface strata deformation following the extraction of coal by longwall mining methods.

Jan 4, 1992

By T. Guyaguler

An analytical technique using computer-based multiple-regression methods was employed to determine the relation between the dust-producing index and inherent rock properties of typical samples from a coal-producing area, one of the aims being to provide a preliminary predictive tool for practical use. The investigation demonstrated that factors varied in their influence under different conditions, the brittleness:toughness ratio and the hardness being the most significant inherent properties with hardness showing the highest positive correlation coefficient

Jun 13, 1905

By Z. Sawlowicz

Finely dispersed, primary sulphide mineralisation in the Cu-Fe sulphide zones of copper-bearing shale of the Polish part of the Permian Kupferschiefer is mainly present in the form of framboids and spherules. This type of mineralisation is especially well preserved in organic-rich shale, where it often dominates over a later diagenetic mineralisation that consists of large grains and veins. In microscopic observations special attention was paid to composite grains of copper and iron sulphides. The results suggest that the Cu-Fe and Cu sulphides precipitated in the Kupferschiefer sediment before pyritisation of the framboids had ceased and that they replaced metastable precursors of pyrite. The precipitation of copper sulphides could have been delayed owing to the formation of Cu-organic complexes.

Jan 4, 1992

By L. T. Matthews, C. E. Loo

During sintering, porous ore particles are easily assimilated by liquid melt. Two simple models of the process are considered: the dissolution of a solid by a liquid and the penetration of a liquid into a porous solid. Laboratory sintering studies covering a range of experimental conditions were undertaken to characterise the assimilation of large particles of ore and flux by melts formed from different mixes of fines. For ores, the process appeared to be complicated by the detachment of fines from the ore surface prior to melt formation, according to the mass of adhering fines and surface roughness of the particle. This delayed the onset of assimilation and sometimes reduced it, although melt penetration was fast and effective. Studies using different temperature profiles suggested that the assimilation of haematite was controlled by the transport of Fe2O3 away from the surface of ore particles. The assimilation of limestone depended more on thermal conditions than on the three magnesia-bearing minerals considered. Changing the composition of the initial melt significantly altered the extent of assimilation of ores and limestone, but again had a less marked effect on the magnesia-bearing fluxes.

Jan 8, 1992

By Gibson J.

Written discussion contributions to the paper presented at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 12th February 1916, with Mr. T.Y. Greener, President, in the chair, comprise comments by Kilpatrick W.M., Routledge W.H., Watson J. and Smith W., along with the author's reply. Also briefly noted are the demonstration of two pieces of equipment, an incline chock and a cage arrestor

Dec 1, 1916

Summary of the morning's events with a Written Contribution to Paper No. 4 and author responses

Jan 1, 1947

By D. J. Reddish, B. N. Whittaker, G. X. Sun

An image analysis technique has been used in the assessment of subsurface fracture levels in the context of water inflow into longwall mine workings. The technique was used to analyse results from physical modelling which are represented by black and white photographs taken directly from the model tests. Binary images of fracture patterns are obtained by scanning the photographs with an image analyser coupled to a video camera. The images are manipulated by a C program which allows them to be processed in vertical and horizontal directions and filtered to differentiate quantitatively between vertical and horizontal fracture intensities. The fracture density distributions provide a valuable database for further numerical and statistical analysis. This allows assessment in terms of water inflow into the excavation. A comprehensive image analysis was undertaken on several extraction models. Results indicate that extraction thickness has a significant effect on the fracture pattern and the fracture density distributions. The results can be used to adapt model findings to situations with a range of extraction thicknesses. The technique has allowed improvement in image enhancement and in the interpretation of model results. In particular, a qualitative comparison between different models is possible.

Jan 12, 1992

By J. M. Smith

This resume provides an account of the work of the Bureau and it's establishment by an Act of Parliament in August 1916. The Medical Bureau is concerned solely with the administration of the medical provisions of the Act. Its main functions are to conduct and to direct or control the medical examinations provided for in the Act. The paper covers the changes in type of silicosis, classification into the three legal stages of silicosis, cancer of the lung and tuberculosis.

Jan 1, 1947

Thermodynamical data of importance in connection with copper smelting have been reviewed and a collection of the most reliable information is presented in Tables XXV-XXVIII and Figs. 67 and 6 8 (folding plate). The data given in these figures and tables consists of (i) graphs and equations showing the variations in the temperature range 0-2000°C. of the standard free energies of formation of most of the oxides and sulphides met with in copper smelting (Table XXV and Fig. 67); (ii) equations showing the temperature variation of the free energy of formation of iron silicates (Table XXVI); (iii) graphs showing the variation with temperature in the range 1000°-1600°C. of the standard free energies of the principal reactions occurring in the smelter (Fig. 6 8 ); (iv) the standard heats of formation at 1200°C. of the main iron and copper compounds and gases reacting in the smelter (Table XXVII); (v) the standard heats of reaction at 1200°C. of a few of the reactions for which the free energy relationships were given in Fig. 6 8 (Table XXVIII). The data presented are discussed in more detail.

Jan 1, 1953

By R. W. Ruddle

The advent of new methods of roasting, “flash roasting and fluidisation”, which are now under development, combined with the use of oxygen-enriched air, may markedly increase the SO2 content of roaster smokes. Skogmo suggests that the production of smokes containing as much as 50 per cent SO2 should be feasible. The use of flash smelting processes may well enable a similar increase in the SO2 content of smelter smokes to be made. In this event the recovery of sulphur would be greatly cheapened and the process might well be much more economic, even if allowance is made for the cost of generating the oxygen

Jan 1, 1953

Discussion following the presentation at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 8th April 1916, included the author's introduction, written contributions by Bedson P.P., Gregory T.W.D. and Morgan J.D., oral contributions by Louis H., Greener T.Y. and Severs W., and the author's reply

Dec 1, 1916