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By J. S. WARWICK, E. J. Browning

Ignitions continue to occur underground, sometimes leading to major explosions. There has been considerable effort in the UK, and more widely in the European Community, to formulate the best ventilation practices and other means of minimising these incidents. Practices and procedures to prevent ignitions are discussed in the light of the risks from current mining methods.

Jan 1, 1993

By Tuncel M. Yegulalp, Selamet G. Ergelebi

A description is given of a method of analysing modern mining systems in terms of reliability and their effects on productivity. Non-exponential distributions, such as the Weibull and lognormal distributions, for failure and equipment repair times are also considered. The resulting non-homogeneous Markov process is solved by the method of stages. A longwall mining system is analysed as an example.

Jan 4, 1993

By C. T. Shaw

Fur a secure mineral supply position to be maintained in the Fiuropean Community there must be a supply of qualified people in the minerals industries. The education of the people required to run and develop these industries should be a priority in the community. This means that there should be a strong capability in mining engineering education. The mining engineering professors decided in 1990 to get together in a new Society to discuss the problems. The Society of Mining Professors/Societat der Berg-baukunde was formed at a meeting in Austria in October 1990. It is basically a F.uropean Society with a few member professors from outside Europe to keep the Society conversant with trends elsewhere. The objectives of the Society are to see that the mining universities in Fiurope maintain standards and produce enough mining engineers. The present membership of the Society and the work of developing a database of current courses is described. Working from the knowledge base developed, it will be possible to design a 'European' mining degree course. The problems which will have to be addressed have been identified and are described in detail.The paper finally goes on to discuss the other problems that universities are facing, the economic problems and above all the lack of students applying for mining courses across Europe. The help and active participation of the mining industry, if that industry still wishes to employ mining engineers, is identified as the only possible solution to those problems.

Jan 1, 1993

By J. H. E. Jeffes, C. Diaz

The heat balance and chemical equilibria involved in the production of blister copper from a chalcopyrite concentrate in a single operation are examined. It appears that two stages—one oxidising and one reducing—will be required. The analysis indicates that on thermal grounds the process is possible with a dry, high-grade chalcopyrite concentrate, if oxygen enrichment to about 30 per cent is used, but that copper losses in the slag will be serious and will require a secondary recovery operation. More extensive data on the activities of copper oxide in slags are required to elucidate this point more effectively

Dec 1, 1971

By F. Reich, S. L. Chryssoulis, K. G. Stowe

The surface chemistry of particulates from mineral processing streams can be determined by laser-probe microanalysis. The small area of analysis (2-30 micrometres) enables the surfaces of individual grains to be characterised. Conclusions are based on data acquired from a statistically significant number of grains of a given type. Maps showing the distribution of elements on the surface of mineral particulates can be obtained by time-of-flight secondary ion mass spectrometry. The importance of such analyses in understanding the response of minerals to beneficiation practices is discussed with reference to three examples. The first relates to the loss of selectivity in the differential flotation of a base-metal ore, the second to the different flotabilities of coarse- and fine-grained pentlandite from a Cu-Ni ore and the third concerns the preg-robbing effects of organic matter in a carbonaceous gold ore.

Jan 4, 1992

By B. D. Rayment, J. D. Wilson, G. R. Davis

Wheal Jane, situated between Truro and the Carnmenellis granite, is under development by Consolidated Gold Fields, Ltd., as a tin producer. The main or B lode comprises a complex cassiterite-sulphide ore located in shear zones along the footwall of the lowest of a series of porphyry dykes (elvans) which strike ENE and dip 35° north. Minor mineralisation follows other elvan contacts and sets of later steeply dipping fractures. The localisation and overall geometry of the deposit is explained in terms of the complex structural geology of the Lower Palaeozoic metasediments and the shape and manner of emplacement of the invading Hercynian granite of Cornwall. Variations in the thickness and grade of the orebody, and in the nature of the mineralisation, are shown to be structurally controlled by undulations of the footwall contact of the B elvan. Wallrock sericitisation is present and is applied in exploration for ore

Dec 1, 1971

By S K. Das

An intensive investigation into modern roof support technology, including hy draulic and control systems, has been carried out against the perspective of global development and support behaviour on longwall faces across the Indian sub-continent. The wide ranging study examined various types and designs of modern supports used in seams of varying thickness and inclination where caving and stowing were practised. Consideration has been given to structural analysis, support resistance, the various forces acting over and on the powered supports and to support compatibility. The examination of the phy sical parameters has been allied to field experience and, together, have led to the formulation of standard designs for both the powered support structure and structural systems. A realistic mathematical model has been formulated for calculating the capacity of roof support requirements resulting from the actual behaviour of the immediate roof stratum. As a result of the work, it should be possible to readily select the most appropriate type of support sy stem for the conditions and longwall mining method that is to be employed.

Jan 4, 1997

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

Australia has large reserves of pisolitic limonite. Mining recently commenced on the Yandicoogina deposit to produce a high-grade sintering ore. The ore contains about 10 wt% combined water and simulated sintering temperature profiles indicate that progressive dehydration of ore particles occurs in the temperature range 300-700 degrees C. Studies by optical microscopy show that although the dehyrdrated ore particles contain numerous cracks, there is no change in the microstructure of the ore because topotactic transformation to haematite results in the formation of compact masses of very fine-grained haematite microcrysts. When the ore is held at around 1 200 degrees C for 1 min significant recrystallisation of these microcrysts occurs, resulting in the formation of optically visible, micrometre sized haematite crystallites. Studies to simulate the behaviour of ore particles during sintering (as nuclear particles surrounded by a standard adhering fines mixture) show that the recrystallisation process occurs much earlier at temperatures of about 900 degrees C. Further studies indicate that CaO in the adhering fines mixture enhances the recrystallisation of the ore nuclei. The results of the investigation indicate that the pseudo-relict haematite in sinters produced from ore blends that contain significant levels of pisolitic limonite consists of dehydrated goethite that has undergone significant recrystallisation and grain growth, a phenomenon that is facilitated by the presence of lime derived from the sintering melt.

Jan 12, 1992

By B. H. Smith

"Most of the discoveries of nickel sulphide deposits in Western Australia have followed the search for gossans. The chances of further discoveries depend on improving our understanding of the cover of strongly leached and transported materials that obscure approximately 85% of the area of the Yilgarn Block that has nickel sulphide mineralization potential. The lateritic profiles that are observed on the Yilgarn Block today were formed over a period of more than 100 m.y. of warm and humid climates. This lateritized land surface has been preserved by induration during subsequent arid climates as well as by the structural stability of the Yilgarn Block.In geochemical surveys of lateritied terrain samples have to be taken from at least the saprolite zone usually by drilling so that confident predictions can be made of the significance of analytical data. Account must be taken of the mineralogy of samples, as well as the nature of the horizon of a laterite profile that is being sampled, owing to the concentrating effects on trace elements of Fe and Mn oxides.Multivariate techniques have been applied successfully to analytical data in gossan recognition when textural evidence is ambiguous. Pathfinder geochemistry has also been used in gossan recognition and the most significant recent advance has come from studies of platinum group metals in nickel sulphides and their dispersion during weathering."

Jan 1, 1984

The Council of the Institution of Mining and Metallurgy submitted the report of the affairs of the Institution for the session 1970-71, and the Statement of Accounts for the year ended 31 December, 1970. The statistics given in the report refer to the calendar year 1970. Details are included of membership, officers, representation on other bodies, honours and distinctions, awards, meetings, publications, library, overseas activities, fellowships and grants, the revenue and expenditure account, the balance sheet, trust fund balances, contributing companies, and schedule of investments

Dec 1, 1971

By S. Vardy

The paper notes that the extraction of 22% of the remaining workable reserves in the north western area involves a risk of spontaneous combustion higher than is normal in Britain. Mining systems have been tailor made in order to minimize the risk of spontaneous heatings, and these systems are described. Well-proved methods of combating spontaneous combustion are referred to, as well as the limitations which now apply to them as the result of the introduction of modern mining techniques. A substantial part of the paper is devoted to the circumstances in which spontaneous combustion occurs underground in the north western area. Several actual incidents which have occurred in the last few years, along with the practical application of the lessons learned, are described. Of particular note are: a) the procedure adopted in the north western area to equalize pressure differences across stoppings using pressure chambers, and b) a retreat mining system, primarily designed to deal with high methane emission and steep gradients, which also affords some protection against spontaneous combustion.

May 23, 1905

By M. Riddell

This paper describes the incipient heatings that occurred below ground in the High Main and Main seams at the mine between the years 1963 and 1966. The possible causes, effects and activities associated with such heatings are discussed in an attempt to establish the precautions necessary to minimize such occurrences. The assessment of as many "norms" as possible is made to enable the earliest detection and level of activity to be determined.

May 23, 1905

By M. W. Davies, P. N. Smith

The activity of MnO has been measured in the system CaF2-MnO at 1773 and 1873 K and in the system CaF2-CaO-MnO at 1773 K by the method of equilibration with platinum. Large positive deviations from ideal solution laws have been found, but these became less as the lime content rose. The loss of a volatile component made activity measurements impossible in the CaF2-AI203-MnO system, but the boundaries of a two-liquid region have been measured at 1773 K.

Dec 1, 1971

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 D. R. Hudson, M. J. Donaldson

"Study of gravity concentrates from the gold-recovery circuit of the Kambalda nickel mill has enabled an assessment to be made of the nature, relative abundance and compositional variability of platinum group element (PGE) minerals and other associated heavy minerals that are present in the Kambalda nickel deposits. The major platinum minerals are sperrylite, PtAs2, and nioncheite, (Pt. Pd, Ni)(Te, Bi)2, and the major palladium minerals are sudburvite, (Pd, Pt, Ni)(Sb, Te, Bi), stibiopalladinite, Pd6Sb2, and palladoarsenide, Pd2 (As, Sb), together with a palladium antimonide and a palladium arsenide that have not been fully characterized. Palladian melonites, which contain up to 10 wt% Pd, and palladian nickeline are also important PGE hosts. Sperrylite and sudburyite are by far the most abundant discrete minerals in the gravity concentrates.Gold occurs as argentian, cuprian and nickeloan—cuprian gold, and as the tellurides calaverite, petzite and auriferous hessite. Silver is present in petzite, hessite and volynskite. Other rare phases contained in the gravity concentrates include native bismuth, altaite, frohbergite, breithauptite, gersdorffite, parkerite, scheelite, tantalite, cassiterite, rutile, bunsenite, gahnite, barite and uvarovite.Descriptions of in-situ occurrences of PGE minerals at Kambalda are rare. Michenerite, PdBiTe, and testibiopalladite, PdSbTe, have been described from a telluride-rich quartz-carbonate vein that intersects massive sulphide ore in Lunnon Shoot. Moncheite has been observed in chalcopyrite-rich stringers, and sudburyite occurs as inclusions in nickeline in a quartz- carbonate veinlet. No discrete PGE minerals have been found within the massive and matrix ore zones in the Kambalda ore- shoots, and the geochemical distribution of PGE suggests that the formation of discrete PGE phases may be related to post- magmatic processes—in particular, metamorphic segregation of sulphides, and the interaction of the ore sulphides, containing PGE in solid solution, with younger hydrothermal fluids. This has led to local redistribution of the PGE, with concentration in footwall stringers and veins, and in reaction zones."

Jan 1, 1984

By R. B. Scott, J. Hewitson

The paper investigates the historical information relating to spontaneous heatings which have occurred within the area from 1955 to date. From this information the seams most liable are identified and the location within the workings is enumerated, together with the possible reason for the occurrence of the heatings. Details are given of the precautions taken during development, working and withdrawal. Sampling procedures are outlined and the interpretation of the results is discussed. Reference is made to the various types of material and techniques employed in both preventing and combating heatings and examples are given of their relative cost and the operational experience obtained. Special observations are made on the changes in mining techniques and their influence on spontaneous combustion.

May 23, 1905

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 J. Laskowski, J. Lekki

"The mechanism of joint action of a frother (alpha-terpineol) and a collector (ethyl xanthate) in the flotation of chalcocite has been examined. In order to study the dynamic effects of frother and collector in bubble-particle collisions, the following aspects were investigated : determination of zeta-potential. Measurements of the thickness of fluid film on the surface of chalcocite and adsorption of xanthate, as influenced by alpha-terpineol, induction time and flotation versus concentration of alpha-terpineol and ethyl xanthate.The mechanism of the adsorption-desorption phenomenon on chalcocite with regard to non-ionic molecules, e.g. a-terpineol, has been considered, and the influence of this on the stage and thickness of the intervening wet layer between a bubble and a particle, changing the probability of collision and attachment, is suggested."

Dec 1, 1971

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 E. H. W. Hornbrook, P. W. B. Friske

Paper presented at the 28th International Geological Congress, Washington DC, July 1989 (International geochemical mapping sessions). The objective of the programme is to establish and maintain a nationally consistent geochemical drainage database. Towards this end systematic surveys have been conducted since 1973. To date more than 200 surveys have been completed to the required standards, representing 180 000 sites and covering about 2 100 000 km2 throughout Canada

Jun 13, 1905