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By M. J. Howes

The high degree of mechanisation, which is mainly diesel-powered, has a significant effect on heat loads; heat output from this source often exceeds the heat flow from the surrounding rock. The extensive use of diesel-powered equipment also influences ventilation rates and minimum values are necessary to ensure that emissions of diesel exhaust are adequately diluted. Many Australian mines are in subtropical or tropical areas with high ambient wet- and dry-bulb temperatures on surface. This, coupled with the large amount of heat from mechanisation, usually means that refrigeration is required at much shallower depths. A secondary problem is associated with the definition of acceptable thermal environment conditions, which are sometimes based on the assumption of no air movement. This gives rise to very stringent thermal environment acceptance criteria, which, in some areas, would prohibit work on surface, let alone underground

Jun 12, 1905

By Marshall Charles Riddell, John Carlon

local news

Jan 12, 1997

By Q. H. Liao, B. G. Monaghan

The options for designing slopes in complex geological conditions are reviewed. It is shown that modelling, especially numerical modelling, allows a degree of analysis that cannot otherwise be achieved. Examples are presented of how numerical modelling can be used to investigate fundamental aspects of rock mass behaviour. It is demonstrated that an important consequence of change in scale is that the mechanisms of failure also change. The complex failure of the footwall slope at Aznalcollar, a large open-pit mine in southern Spain, is discussed. Numerical modelling with UDEC (universal distinct-element code) has allowed the realistic simulation of displacements measured in the field

Jun 18, 1905

By O. Dojcar

Equations for calculating the parameters of controlled blasting (burden and spacing of boreholes and weight of the bottom charge) are derived and analysed on the basis of empirical values and made more precise through incorporation of the properties of the rock being blasted and explosive applied. For the success of controlled blasting the correct choice of the blasthole diameter/charge diameter ratio is critical. This relation is defined as the coefficient of radial decoupling of the charge; it is recommended that it is chosen to be between 3 and 3.5. Analysis of smooth blasting, cushion blasting and presplitting indicates that cushion blasting is a less destructive alternative to smooth blasting, but it has a slightly higher blasthole consumption and limited possibilities of use. There are definite economic advantages to controlled blasting, especially in rock masses of low and medium strength

Dec 1, 1996

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

The report of the Annual General Meeting of the Institution of Mining and Metallurgy held on Thursday, 20 May, 1971, in the rooms of the Geological Society of London, Burlington House, Piccadilly, London, W.1, at 4 p.m. (Chairman : M. J. Cahalan, President) includes details of awards and prizes presented to William Justin Kroll, Sir Gordon Colvin Lindesay Clark, John Convey, Evert Hoek, Peter Reginald Dawson and Christopher Michael St. John

Dec 1, 1971

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 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

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

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 A. L. W. Lips, B. P. J. Stevens, T. J. R. Bareley, E. Rothery, S. H. White

B.P.J. Stevens contributes a further response to the authors' earlier lengthy reply regarding their paper published in Trans.IMM B, vol.104, 1995, p.B1-B17, contending that despite the positive contribution clarifying their interpretations they perpetrate some misquotations, attempt to rewrite history and fail to understand the New South Wales Geological Survey's stratigraphic interpretation of the Broken Hill area. The paper's authors, in their further response, robustly defend their views, insisting that Stevens tends to misquote or take out of context what they have written and reiterating their findings that Zn is tectonically stacked above Pb at the north end of the orebody, that the written development of the stratigraphic interpretation is as they have stated, that shearing has attenuated or removed fold limbs in the Broken Hill block and that the 1:100 000 stratigraphic map reveals that magnetic anomalies are oblique to and truncated by the Geological Survey's interpreted stratigraphic boundaries

Jun 19, 1905

By G Williams

Discussing equipment, systems of work, the need for updated programmes of local seismic exploration, and developments within the South Wales coalfield.

Jan 1, 1993

By B. Sonmez, B. Aksanl, S. Ersaym, I. F. Erkal, S. L. Ergun

The comminution circuit at the plant has experienced severe problems arising from a feed containing much larger amounts of clay and having a higher moisture content than expected. Three solutions were proposed: replacement of the crushing circuit by tooth roll-type crushers; using washing drums; and introducing primary autogenous/semi-autogenous millling instead of crushing. Computer simulations studied the effects of the first two solutions on the circuit capacity. Laboratory and industrial scale ball mill batch grinding tests were carried out. The parameters of a kinetic model were determined. The ball mill circuit was sampled and operating model parameters were calculated. The ability of batch grinding parameters to represent the operating conditions was studied. Tests failed to find acceptable model parameters, but parameters from an industrial size batch mill were found to be suitable for simulation studies. The simulations indicated that a continuous feed of -12 mm provided by tooth roll crushers would maintain the desired capacity. Increasing the feed size to -25 mm would reduce the capacity by 8-15%. The use of washing drums could also solve the capacity problem, but small fluctuations in water flow rates might result in problems of excess water in the grinding circuit.

Jan 4, 1993

Jan 1, 1947

By A. Policard

The bodies of mammals possess a very efficient mechanism for ridding themselves of inhaled dust. When the lung is healthy this mechanism works very well, and dust is quickly and completely expelled from the lung either by the respiratory tract or the lymphatics. The mechanism, however, is easily upset, and slight alterations in the condition of the ciliated epithelium or the circulation of lymph are sufficient to interfere with it, therefore the second mechanism comes into play and the dust is fixed and immobilized in some part of the lung. This, however, is not a real cleansing process, since the lung becomes a dust-trap, and may become'pneumokoniotic. The mechanism is protective at first, but later, when the accumulation of dust is considerable, it gives rise to trouble. The lung cannot become, so to speak, a physiological dust-trap, and still retain its normal structure and function; pneumokoniosis begins, which is essentially a disease due to the mechanical presence of large amounts of inert foreign material.

Jan 1, 1947

By A. Z. Lang, D. A. Hall

After a brief description of the causes of spontaneous heating and of general preventative methods, a detailed account is given of occurrences of spontaneous heating in the Main Seam (locally known as the 5/4 Seam) at Westoe Colliery. This seam is about 12 feet thick consisting of hands of coal and shale, but only 4 feet 6 inches is worked because of the thickness os strata in water-bearing rocks and the worked section is selected on quality considerations. An advancing longwall face in this seam (2nd South) began to heat after working for six months and ultimately had to be abandoned. By adopting retreating methods and mining narrow panels it has been possible to extract this coal at an excellent rate of productivity. The system of goaf ventilation is important, because the use of a bleed road would have given rise to dangerous conditions in a goaf which of necessity would have contained fallen coal. Preparatory seals were prepared at selected sites so that, if necessary, a panel could be sealed off quickly; these seals are completed as soon as possible (within three weeks) of finishing a panel. A gas sampling system has been instituted which includes daily sampling on the face and in the goaf, and weekly sampling at the stoppings of all completed panels. The coal has now been extracted from this seam for three years without any further difficulties from spontaneous heating.

May 23, 1905

By L. J. Barnes, R. O. Koch, J. H. Versteegh, P. J. H. Scheeren, F. J. Janssen

Following two years of laboratory research with bench scale reactors, a 9 m3 experimental process demonstration reactor was installed at Budelco's zinc refinery to treat their underlying groundwater. A 600-fold scale-up was successfully achieved. It has demonstrated that this anaerobic microbial process can remove a wide range of heavy metals and sulphate to the required levels. Extended operation of the demonstration unit has shown that the process is robust, can withstand wide variations in feed composition, rapidly recovers from operational upsets and is easy to start up and shut down. The metal sludge produced can be processed in a metal refinery to recover both metals and sulphur.

Jan 12, 1992

By J. H. E. Jeffes, K. T. Jacob

The activity coefficients of oxygen in liquid Pb-Sn alloys have been measured between 550 and 1100°C by use of solid oxide galvanic cells: Pt, Ni-NiO | Zr02 Solid electrolyte | O (Pb + Sn), Cermet, Pt; and Pt, Fe-FeO | Zr02 Solid electrolyte | 0(Pb + Sn), Cermet, Pt. Alcock and Richardson's quasi-chemical equation, with the coordination number of atoms set to 2, is found to predict successfully the activity coefficients of oxygen in these alloys. The relative partial molar enthalpy and entropy of oxygen at 1 atom per cent in the alloys have been calculated from the variation of the activity coefficient with temperature. The addition of Sn to an unsaturated solution of O in Pb is shown to decrease significantly both the partial molar enthalpy and entropy of O. As the measurements were restricted to a narrow range between 750 and 1100°C in Pb-rich alloys, however, the pronounced variation of the partial molar enthalpy of O with temperature at constant alloy composition predicted by the quasi-chemical model could not be verified.

Dec 1, 1971

By M. Rahman, P. C. Kapur

The fixed-time locked-cycle grinding test is employed to simulate the industrial closed grinding circuit on the laboratory scale. A mathematical algorithm for 'cyclewise' computer simulation of the locked-cycle test has been derived and used to study an idealised laboratory-scale model of a closed ball-mill circuit. The agreement between simulated and experimental results is reasonably good, except when the grinding times are relatively long

Dec 1, 1971

By C. H. J. Beaven, M. P. Jones

Since the various new techniques of automation and computing have enabled vast numbers of mineralogical observations of relatively small samples to be made cheaply and rapidly, the statistical assessment of these measurements has become of vital importance. Much of the theory and most of the procedures of sampling that are used in the mineral industry are based on Gaussian statistics, but modern measuring techniques show that many mineralogical parameters do not necessarily follow the Gaussian distribution function. Consequently, it has become necessary to examine the application of other, more suitable statistical methods in order to derive the maximum amount of useful information from the examination of mineralogical samples. Some of the errors that can be introduced by the use of incorrect distribution functions are discussed and the value of determining the function that is appropriate to the particular parameter that is being measured is shown. Examples are provided of non-Gaussian distribution functions in mineralogical materials that were encountered during prospecting and during mineral treatment operations: a Canadian uranium ore, a Thai tin ore, and gold ore tailings.

Dec 1, 1971