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By G. Adachi, K. Machida, T. Ozaki, K. Murase

The chlorination rate with CCl4 was unexpectedly slower than carbochlorination using chlorine under the same reaction conditions. Chlorination with CCl4 was topochemical and the amount of monazite reacted after different periods suggested that the kinetic control step was the reaction between CCl4 and the monazite core at the interface. The kinetic order of the reaction was 0.5. The presence of a complex former, AlCl3, promoted the chemical vapour transport of rare-earth chlorides as complexes

Jun 18, 1905

Studies were carried out to examine the effect of introducing varying levels of a pisolitic limonite (Yandi) into an Australian iron ore blend. Compared with other ores in the blend Yandi is more porous. This structure is found to have a considerable effect on the sintering behaviour of the blends. Pilot-scale sintering studies and plant trials showed that sinter plant productivity, sinter reducibility and the low-temperature reduction degradation index altered significantly when the level of Yandi in the ore blend exceeded 15 wt%. The improvement in the reducibility is thought to be a direct result of increased porosity in the sinter and the presence of highly reducible pseudo-relict haematite. Plant trials have also shown that operational changes could be made to the sinter plant to avoid potential deterioration of productivity

Dec 1, 1991

By Fearnsides W. G.

The map shows the sites of collieries and important boreholes in the district, with approximate underground contours of the pre-Permian surface of the Coal-Measures and of the Barnsley Bed

Dec 1, 1916

By Briggs H.

The illustrated device uses the principle that the lamp can burn with a smaller inlet passage if the air is rich in O2 and that the size of the inlet can be made a measure of O2 percentage. The appliance consists of an adjustable cut-off applied to the inlet of a safety lamp of the improved Gray pattern. Precision is assessed from tables of calibration tests in air contaminated with blackdamp of CO2:N2 composiiton 1:5.67 at temperatures of 40-70 degrees F. Results are presented of tests at St. Germain's colliery, of tests in air contaminated with pure CO2 and of air contaminated with both blackdamp and inflammable gas; published ranges in mine-air blackdamp compositions are tabulated as ranging from 90.06% N2 to 43.90% CO2. When firedamp is present at 1.25-2.5%, its content must first be estimated by means of the cap and a fifth of its value then deducted from the lamp reading for O2

Dec 1, 1916

By Bakker J. de, P. A. Leest, W. L. Dalmijn, H. J. Glass

The test facility at the Delft University of Technology, in the Netherlands, was characterised. Advantages include the possibility of separating particles with high but different densities up to 9 g/cm3, the ease of adjustment to any required separation density and the absence of moving parts. Simultaneous separation of more than two types of particles is possible and the magnetic fluid is safe and convenient to use compared with other heavy liquids. Disadvantages include loss of magnetic fluid with outgoing particles (cost approx US $10/l) and degeneration of fluid due to bacterial activity, reaction with particles and with surroundings. Only non-magnetic materials can be separated, there is limited potential for scaling up and high investment is required on account of the cost of magnets. Future improvements in the design of the apparatus and the properties of the magnetic fluids can only enhance its attractiveness for commercial applications

Jun 18, 1905

By J. Temporal

An introduction to the conference material in this issue is given together with the issue contents list, closing remarks by its chairman Dr. J. Temporal, the list of contributors and their companies, and the information that the 26th Sir Julius Wernher memorial lecture had had to be presented by the lecturer's wife, M. Biggart, in his absence due to site problems on the Storebaelt project

Jun 16, 1905

By G. Zhan, P. Mousset-Jones, G. Danko, J. J. K. Daemen, C. Mezei

Paper presented at the conference Risk assessment in the extractive industries, held in Exeter, 23-24 March 1994, and first published London: IMM, 1994, preprint volume. 18pp., 12 refs. (Originally entitled: Tunnel roof diagnosis using a robotic sensor test bed.) An integral roof diagnosis method is proposed to assist in assessment of risk regarding the stability of an excavation. A Robotic Sensor Test Bed (RSTB) is being developed for the characterisation of roof stability. The sensor test bed consists of a sonic/ultrasonic wave response sensor, a laser surface profiler and a surface temperature sensor. These sensors are mounted on an articulated robot manipulator for performing remote-controlled or fully automated diagnoses. A number of laboratory and field sonic/ultrasonic tests were conducted. A high-energy ultrasonic transducer and an impact device were used to resonate rock slabs. The fracture depths of the slabs were found to be inversely related to the measured resonance frequencies. The agreement between identified and actual dimensions was acceptable. Field tests also showed that loose rock on the surface can be clearly distinguished from solid formation by comparing their wave responses. The robotic laser profiler part of the RSTB was used to measure surface geometry. Different scanning methods are being developed to achieve the fastest and most precise measurements and to provide pertinent information about rock joints and major fractures

Dec 1, 1994

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 R. Poulin, C. F. Gleeson

The Birimian rocks of the region are gold-bearing and show many similarities to those of Burkina Faso. All three greenstone belts (Goroual, Tera and Sirba) host gold-bearing quartz veins. It appears that, contrary to previous misconceptions, lateritic terrain is not an unfavourable environment for exploration geochemistry. This is demonstrated by the results for the Koma Bangou area, where soil and termite-mound geochemistry have been successfully used in the search for gold. Soil provides an effective sampling medium where it is shallower than about 2 m; there is evidence that some soil anomalies are enhanced by the presence of secondary (botryoidal) gold. In areas of thicker, allochthonous soil cover, termite-mound sampling is more effective. At Koma Bangou an identified resource of some 11 100 000 tonnes with an average gold grade of 2.44 g/t has been reported. The gold mineralisation occurs in quartz veins and stockworks aand in the wallrocks of shear and fault zones that trend N, NW and NE. The host rocks are a granodiorite-syenite porphyry and intermediate metavolcanic rocks and tuffs

Apr 1, 1996

By Haldane J. S.

(Paper presented at the Institution of Mining Engineers' general meeting held in London on 8th June 1916.) It was shown in the last Supplement to the Registrar-General's Reports, in connection with the census of 1901, that the general death-rate among colliers was considerably lower than in the great majority of occupations but that there is an exception to this in the case of colliers above the age of 55. Examination of the statistics finds that the excessive death-rate among old colliers is to a large extent only apparent, and that the real excess of bronchitis from which they have suffered has greatly diminished. It is concluded: (1) that good ventilation is of considerable importance to the health and continued working efficiency of miners, as well as to their safety from accidents; and (2) that there is no real statistical evidence of harm resulting from the inhalation of coal-dust or shale-dust in the quantities ordinarily breathed by miners, and a strong presumption that the dust they breathe protects them against serious dangers from bacilli that are removed from the lungs by the dust-clearing cell mechanisms

Dec 1, 1916

By Qing Wang, H. Sevim

Belt network simulators are the most widely used models in the design of belt networks. The simulators developed in the past two decades are reviewed and their limitations are discussed. To overcome these limitations and to provide a design model that can be used efficiently in real-life applications, a comprehensive non-simulation model has been developed. The features of this model are briefly discussed. A real example is used to demonstrate the model's superiority over belt simulators

Sep 1, 1991

By A. Berckmans

The key variables in the financial analysis of a mining project include the metal price and the quantities of ore and metal. In general, if the metal price drops, the cutoff grade is increased so as to increase the average grade. This causes recovered tonnages of ore and metal to drop. Discussion is presented of the development of a new method to evaluate the relationship between the cutoff grade, z, the ore tonnage above cutoff, T, and the metal quantity above cutoff, Q. Detailed information is provided on the QTz curves for lognormal and inverse gaussian (Sichel's) distributions. Both these distributions are used as models for the grades in different types of ore bodies, and they are both T-symmetric. The geometry of the QTz curves is simplified, making it easier to work out the impact of minor variation in the parameter values for each distribution

Dec 1, 1996

By D. M. Milne, P. J. Lunder, R. C. Pakalnis

During the mining of an open stope, deformation of the hanging-wall and the potential for dilution generally increase with the size of the exposed hanging-wall. Excluding discrete structures that may delineate unstable blocks, the mechanisms that drive hanging-wall deformation and possible dilution comprise several factors which can include elastic, plastic and discontinuum deformation. These stages of deformation are not mutually exclusive and at any point during mining all three of these mechanisms may be acting on the hanging-wall rock mass. Computer modelling techniques are available to analyse the three stages of deformation, but the difficulty lies in trying to obtain realistic rock mass properties for input and in determining when each stage of deformation is acting. Instrumentation data can be used to predict the effect of continued mining. However, it is often difficult to calibrate numerical models against field data owing to the large number of input parameters required. An empirical approach is recommended that uses two new parameters, the radius factor and the effective radius factor. A method is proposed for predicting the effect of continued mining from existing deformation and dilution data for a given hanging-wall

Apr 1, 1996

By C. L. Schneider, C. O. Gomes, R. P. King, J. A. Finch, D. Lin

Discussion is presented by Prof. King and Dr. Schneider of the paper by Lin, Gomez and Finch published in Trans.IMM C, vol.104, 1995, p.C155-C161. They conclude that the correction procedures used for simulated observations of simulated capped spheres are not reliable when applied to mineralogical data and that their relative ranking should not be extrapolated to other situations. Properly regularised solutions obtained with the use of appropriate kernels can be safely used for routine mineral liberation work and can be calibrated accurately against real mineralogical samples in the laboratory

Jun 19, 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 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 P. A. Rossouw, G. A. Fourie

Several attempts have been made over the latter half of the twentieth century to devise a system for the classification of underground mining methods. None of these are found to be totally successful. A revised classification is suggested with three main categories being identified by reference to fill requirements, steep stopes and stratified geological environments. Methods always needing lasting mass or structure fill include methods with timber-structured stopes and those with mass-filled (or cut-and-fill) stopes. Methods associated with steep stopes are subdivided into steep-stope-specific caving and steep-stope-specific non-caving (or self-supporting) methods. Methods not in the first two categories, often used in stratified geological situations, are not necessarily restricted to stratified environments and include caving as well as non-caving varieties. This category is further divided into room-and-pillar mining, longwall and shortwall coal mining and the type of open stoping found in gold or platinum reefs comprising overhand, underhand and breast-stoping variations

Dec 1, 1996

By S. P. Singh

The purpose of the cut is to provide a free face to which the remainder of a development or breasting round can break. The results of field testing in drifts and at a quarry face were used as a basis for a description of the rock breakage and flushing mechanism in the cut. It was concluded that the important features of a cut design are proper hole spacing, sufficient relief volume, drilling accuracy and relief holes slightly longer than the planned length of the round. The void space provided by the relief holes should be about 15% of the cut volume, with more required in weak, highly fissured rocks. The importance of drilling accuracy increases with round length, an error being magnified by the small blasthole spacing. The first hole pulls only about 20% of the round length, 4-6 holes having to be fired before the cut is pulled close to its design depth. The first four blastholes should be fired with a minimum inter-hole delay of 100 ms to provide progressive relief of burden and avoid the superimposition of ground vibrations. The earliest-firing charge should be closest to the relief area and act laterally, while the first of the vertically-fired charges to be detonated should be the uppermost. Problems during cut-pulling include sympathetic detonation, dynamic pressure desensitisation, charge disruption and freezing of the cut

Dec 1, 1995

By P. H. Morris

To achieve the full potential of sub-aerial co-disposal the properties of the co-disposed wastes must be known and understood. A description is given of the morphology and properties of waste deposits that were formed during 19 field trials of sub-aerial co-disposal at the dual Goonyella-Riverside mine in Queensland and at Hunter Valley No.1 and Warkworth mines in New South Wales

Jun 19, 1905

By R. A. Lord, H. M. Prichard

Paper presented at Mineralisation in the Caledonides, the Mike Gallagher memorial meeting held in Edinburgh, 27-28 June 1996. The complex exemplifies a class of olivine-rich, platiniferous ophiolite complexes generated by unusually high degrees of hydrous melting above a subduction zone. Crystallisation of abundant olivine from unusually picritic magmas produced an exceptionally thick sequence of crustal dunite cumulates. Significant (1-4 ppm) concentrations of Pt+Pd occur where sulphide-bearing dunites are spatially associated with podiform chromite concentrations. In the area north of the Balta Sound, the chromitites appear to lie in distinct stratigraphic zones. A detailed programme of lithogeochemical and soil-rock interface geochemical exploration led to the intersection by diamond drilling of three stratiform horizons of sulphide-bearing dunites and associated precious-metal mineralisation. Patterns of cryptic geochemical layering, at scales from 200 m to less than 1 cm, suggests open-system fractionation

Jun 19, 1905