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By Slater R

The initial planning and detail design phase leading to the development of a 7.5 m internal shaft to service the deep 3000 and 3500 copper orebodies at Mount Isa, Queensland is well advanced. The choice of internal shaft access was made over alternative methods such as a decline from existing levels and borehole hoisting. The resulting access development requirements and shaft configuration for production have been determined. Several techniques are being studied for shaft development. These include the application of blind shaft drilling and large hole reaming methods as well as conventional sinking techniques. As the 3000/3500 Orebodies extend from 1000 metres to more than 1800 metres below the surface, high stress conditions and ground temperatures ranging from 45CC to 62CC are anticipated. The effect of these on the methods being investigated to create a favourable working environment will influence the final choice. Exploration diamond drilling is in progress to confirm the geology of the orebodies so that planning for their extraction including refrigerated ventilation concepts can proceed.

Jan 1, 1982

There is a difference in design aspects between steel linings and rubber linings for grinding mills. The basic design rules for rub- ber are described as well as the liner designs for different applications.

Jan 1, 1978

In the southern part of China, car-bonate rocks outcrop in large areas. Ka-rst develops owing to hot, humid climate and heavy rainfall. In deposits of coal, iron, bauxite, tungsten, tin and base metals exist karst formations within or near the mineralization zones. Three pro-blems should be solved in the mine cons-truction in karst region. The first is the drainage and safety control of karst groundwater. Different methods are used to cope with local hydrogeological con-ditions, e.g. drainage from surface by submersible pumps in wells penetrating groundwater seams; drainage from under-ground drifts which intercept groundwa-ter flow with clusters of holes drilled into karst aquifer or with vertical ho-les drilled from surface to the drift underground; cement grouting to block off channels or to seal a part of aqui-fer; groundwater pollution control; etc. With those measures many Chinese mines of tremendous waterflow were success-fully developed and valuable experiences were gained. The second problem is the stability of buildings deteriorated by surface subsidence due to drainage. The occurence and distribution of surface cavings by drainage were studied.

Jan 1, 1990

By Walker K, Burton RC

An outline of the ventilation and refrigeration requirements of deep South African gold mines is presented. This is followed by a brief description of the history of controlled recirculation in mines and the practical and economic benefits such schemes can offer. The potential hazard of a fire in a recirculation system is discussed.The major part of the paper describes the first large-scale field trial of controlled recirculation to be conducted in South Africa. Emphasis is placed on the monitoring system that was used for data acquisition during the trial, and also on a safety system designed to shut off the recirculation fans in the event of a fire.The paper concludes with a review of the latest development work taking place on recirc-ulation safety systems.

Jan 1, 1985

A system for rapid on-line determination of weight percentage coal in slurry and weight percentage ash in coal has been developed at the Julius Kruttschnitt Mineral Research Centre, University of Queensland. The gauging system is suitable for use with coal flotation slurries or slurries having a maximum particle size of about 1 millimeter. The system is based upon measurement of gamma ray transmission; radioisotope sources emitting photons of two widely different energies are employed. The inaccuracies of measurement that would normally result from variable amounts of air entrained in the slurry are substantially reduced by pressurising the slurry to approximately 2MPa (300 psi) using a Mono pump. The equipment can be used to make measurements on more than one slurry stream by pumping streams sequent- ially. The system is being tested at the Peak Downs Mine of the Utah Development Company in Central Queensland. This paper describes the theoretical principles of the gauge design, the experience gained to date in the commissioning of the equipment, including the installation of a PDP 11/03 computer, and the progress made in developing satisfactory interpretations of the gauge count-rate output.

Jan 1, 1978

By Bailey S, Avraamides J

Laboratory-scale experiments were conducted in a mechanically stirred aeration vessel to determine the rusting abilities of aerated water in the presence of various catalysts compared to the industrially used ammonium chloride. The catalysts used were tartaric acid and citric acid, firstly by themselves, and then in later experiments mixed with ammonium chloride. From these experiments it was found that leaching of iron from reduced ilmenite in the presence of either tartaric acid or its sodium salt was much slower than in the presence of ammonium chloride. Citric acid or its sodium salt also give a slower rate of leaching than the ammonium chloride system, but citric acid and its sodium salt mixed in equal proportions produced a rate of leaching approximately twice as fast as the standard ammonium chloride system. When tartaric acid was mixed with ammonium chloride the leaching rate was found to be equivalent to the leaching rate of the same amount of ammonium chloride alone, thus indicating that tartaric acid made no contribution to the leaching in this svstem_

Jan 1, 1996

The O.K. deposit occurs within a belt of cherts and spilitised basic volcanics near the western margin of the Hodgkinson Province. The tabular to lenticular shape and gross conformability of the ore bodies; the common occurrence of colloform, framboidal and banded textures in the ores; the lack of significant alteration adjacent to the massive ore horizons and the apparent restriction of stockwork mineralization to the foot-wall side of the massive ore zone at the O.K. mine, all favour a syngenetic origin for the massive sulfide bodies. Furthermore, the micro- structural evidence suggests that the ores have undergone the same deformational history as the country rocks. The invariable association of the ores with spilites; the S isotope values and Co-Ni contents of the pyrites, together with the primitive metal assemblage (Fe, Cu, minor Zn) strongly favour a basic magmatic source for the sulfides. It is suggested-that the sulfides were probably precipitated sub aqueous- ly during a hiatus in volcanic activity. The O.K. deposit is of the cupreous pyrite variety, but unlike other well known occurrences of this type, it does not con- stitute part of an ophiolite complex. While the host volcanics exhibit strong ocean floor tholeiitic affinities, no associated ultra

Jan 1, 1978

By Tyler DB, Thin LGT

Coal mass strength properties must be estimated to obtain realistic estimates of coal pillar strength. The limitations of existing techniques for approximating these properties are discussed. The coal mass is anisotropic. The Hoek and Brown approach to rock mass property estimation is modified to allow for this. This approach requires the Rock Mass Rating (RMR) for the strata. In the normal case where bedding is sub-horizontal, these major planes of weakness have little effect on the strength of pillars. As a result of this the RMR must be measured parallel to bedding. This means that a significantly higher rating than that usually obtained for coal is observed. The use of mass strength property estimates in extant empirical relationships is outlined. At high width to height ratios, an acceleration in the rate of increase in pillar strength with increasing width to height ratio has been observed. The empirical relationship developed by Salamon (the so called squat pillar formula) takes account of this. This relationship was found to have significant limitations with respect to its universal application. Modifications are made to Bieniawski's empirical formula to extend its use to large width to height ratio (squat) pillars. This new squat pillar formula has none of the disadvantages associated with Salamon's relationship. Strain softening was incorporated into non-linear finite difference numerical modelling to estimate pillar strengths. The technique outlined above is used to obtain peak coal mass properties. Modelled pillar strength was found to be sensitive to both peak and post peak mass strength properties. Post peak properties were found to be difficult to obtain and required some back analysis. Modelling results were used to estimate both the strength of squat pillars and parameters for use in a new squat pillar empirical strength relationship.

Jan 1, 1992

By Hochwimmer B, Baxter JL

Heavy minerals are mined from two fossil strandlines on the southern Swan Coastal Plain. The Capel shoreline, 7 km inland, and the Yoganup shoreline, 15 km inland are arcuate, northwest-facing, and remote from the modern coast. Based on foraminiferal and molluscan assemblages, the shorelines are probably of Pliocene age. The Yoganup shoreline is adjacent to the Whicher Scarp, which is cut into the Leederville Formation (Lower Cretaceous) at the southern boundary of the Swan Coastal Plain. Stratigraphic relations and detailed sedimentology have been studied from temporary exposures in the Yoganup Extended and Yoganup North mines, within a strandline complex at 27 m and 18-33 m above sea level respectively. Heavy minerals were deposited in thin, shallowing-upward sequences along a wave-dominated clastic shoreline cut into pre-Cainozoic sediments. Lithofacies units deposited in eolian, foreshore, shoreface and lagoonal environments are the most significant sites of heavy mineral accumulation. The data collected provide a basis for further exploration.

Jan 1, 1986

By Ellery B. I

Field investigations recently undertaken by Utah Development Company (U.D.C.) have been developed to allow the assessment of ground conditions relevant to the use of large bucket wheel excavators for pre-stripping overburden. "Bucketwheel diggability" predictions were made on the basis of a wedge test which was perform- -ed in the field on nominal 150 mm diameter drill core samples. Specific separation force (calculated from the wedge test results) for different rock horizons were theoretically related to the excavation rates of various sized bucketwheels, i.e., "bucketwheel diggability". The specific separation force was shown to vary with lithology, structure, weathering and moisture changes. By correlating these features between boreholes, an overall assessment of bucketwheel diggability was then made. The approach adopted to assess bucket- wheel diggability incorporated various levels of investigation. Initially, a reconnaissance stage provided information from widely spaced 150 mm cored holes to compare and contrast areas with differing bucketwheel digging char- -acteristics. The following stages progressive -ly added to this information, until finally, between hole correlations, allowed calculations to be made of volumes of materials of similar

Jan 1, 1981

The BLEG (Bulk Leach Extractable Gold) technique is a semiquantitative measure of cyanide extractable gold contained in a sample. A 5kg sample is leached in cyanide solution for 24 hours and gold is precipitated out of the pregnant solution using zinc and assayed by AAS. The detection limit is reported as ppb (parts per billion). Telfer is located 1300km north north-east from Perth in the Great Sandy Desert. The climate is one of hot summers with irregular rainfall and mild winters. A large portion of the area is covered by aeolian sand and seif dunes with poorly developed drainage, rare outcrop; topographic relief is a maximum of 96m. Poor outcrop and poorly developed drainage render conventional stream sediment sampling and soil geochemistry inadequate. Therefore a technique providing a minimum number of samples with maximum accuracy and sensitivity was needed. Consequently BLEG orientation surveys were conducted over the Telfer Mine area in 1983, 1984 and 1985.

Jan 1, 1988

By Szymanski J, Planeta S

For many hard rock mines with near surface deposits, the surface crown pillars form the first line of protection for the immediate underground workings. Underground stopes are typically contained by crown pillar, which protects the level above, rib pillars, and a sill pillar through which the ore collection system is cut. This paper discusses the mining of these pillars, with particular emphasis on the overall stability of the mined out upper part of the mine areas. An area of interest is located in the Canadian Shield, where the mining has progressed below four thousand foot level in the ultramafic high grade sulphide type of orebody.

Jan 1, 1995

Digital computers, by virtue of their capacity for high speed repetitive calculation at low cost, are finding increasing application to routine calcula- tions in the mining industry. In this paper techniques are shown whereby the use of computers can be extended to more complex tasks. The regular calculation of grades and tonnages of material to be extracted from specified areas of an operating open pit is a necessary part of production planning. In this paper it is shown how these calculations can be carried out by computer. thereby freeing planning staff from manual calculation. An operating open-pit mine can be described in terms of drill logs, geological ore boundaries and pit perimeters at various levels. These form the data base which must be suitable for frequent updating to incorporate new information. A suite of computer programmes is described which operates on this data base to calculate tonnages and grades of ore within extensions to the perimeters as indicated to the system by planning staff. Possible future extensions are discussed.

Jan 1, 1971

By J J. Campbell, G J. Wilkie

The ores of the Golden Mile exhibit considerable complexity. As a consequence, the operating company, Kalgoorlie Consolidated Gold Mines (KCGM), considered it important to develop a coherent database of information describing the nature of the many ore lodes in terms of (1) rock properties and mineralogical content, including relative proportions, grain size, associations and deportment of key elements between minerals, (2) the relative behaviour of consituent minerals in various stages of processing and (3) the nature of the final products and key intermediate streams. The paper describes a sequence of metallurgical tests covering comminution, flotation, gravity concentration, leaching and calcining, carried out on three lodes of the Golden Mile. Key samples generated by the testing were subjected to comprehensive size-by-elemental assaying and QEM*SEM mineralogical determinations of sulphide and precious metal associations. Significant differences between lodes were identified, and the impact of these differences on processing is discussed.

Jan 1, 1998

By Elliot B. J

Flash smelting is a complex and capital intensive technology. Although in use for 50 years the technology is still not well understood from a fundamental point of view and thus uncertainty is evident when significant change to the practice is necessitated. The application of effective design and process simulation tools has significant advantages when process change and improvement is required. Mathematical models have been used to simulate the processes occurring in the shafts of copper flash smelters. The present approach to flash furnace modelling differs from earlier work in that the burners were modelled in detail, the output from the burner model becoming the input to the shaft model. This paper serves as an introduction to the modelling process used to analyse the performance and provide a better understanding of the parameters applicable to the flash furnace at the Kalgoorlie Nickel Smelter.

Jan 1, 1992

By I Cameron

Simulation is increasingly being used to analyse mineral processing operations and explore efficiency options. Engineers that use simulation are rightly concerned with the quality and applicability of the underlying models. However, many of these models have a significant empirical component, and the best structure for this component may not be apparent. There is an opportunity to improve the quality and application range of these models by exploring potential structures for this empirical element. One approach to this problem is the use of structural optimisation, which is a formalisation of the model development process. This method searches through a family or hyper-structure of candidate models for a model that is optimal with respect to some measure of model quality. This method has been applied to the modelling of an industrial flotation circuit. The result was a model that was a significant improvement over a number of standard models reported in the literature. Structural optimisation provides a method to compare potential models in a systematic and efficient way, and hence to improve the structure of process models.

Jan 1, 1998

On Monday, October 25th, 1971 at approximately 12.15 a.m. the night shift proceeding underground discovered smoke at No.1 and No-3 cut throughs on the eastern side of the belt heading and in close proximity to the upcast shaft. Attempts to control the fire continued throughout the morning; as the position underground altered various procedures were adopted in an effort to contain and control the fire. Despite these efforts at approx. 12.40 p.m. a sudden change occurred which made it necessary to withdraw all workmen from underground, the vicinity of the Tunnel entrances and upcast shaft. Sealing of the mine at the entrances was the only remaining alternative. Several boreholes were put down to enable sampling of the atmosphere and air temperatures to be taken. This was essential as a guide to determining when conditions were suitable to allow exploration of the area using mine rescue self contained breathing apparatus.

Jan 1, 1972

By Singh RN

Monolithic packing systems have gained in popularity as a gate side packing method. However, there has been no detailed investigation to assess their underground strength behaviour. This work includes the laboratory and in situ investigation for strength behaviour determined on various monolithic packing materials namely Tekpak-XX, Hydropak-20, Hydropak-30, Astrapak-3R, Flashpak, Thyssen pack and Aquablends. A simple technique for assessing the pack strength was developed at the laboratory by using a penetrometer, of which penetration resistance can be directly correlated with the uniaxial strength of the pack. The in situ strength investigations were made on core samples obtained from three pipes inserted inside the pack, while the penetration test were made on the pack surface. The in situ results indicated that the packing material develops an inconsistent strength on various part of the pack which was mainly related to an inadequate mixing of grouts inside the pack.

Jan 1, 1992

Pillar mining methods at the Pasminco Mining Broken Hill Operations are not new. Since mining commenced on Pasminco's leases at the turn of the century virtually every pillar extraction method tried throughout the world has been used. Much of the remaining mineral resource in the Pasminco Broken Hill leases is contained in pillars.However, due to the on-going need for mechanisation with bulk mining methods, and the very peculiar physical circumstances surrounding the formation of these pillars, their exploitation requires the development of a virtually new method based on excavation technology not previously used in the Australian mining industry. Trials of the method are to take place at the southern operations during 1991.

Jan 1, 1992

The Hunter Valley Rail Project (HVRP) represents most of the coal producers using the Hunter Valley Rail System in NSW to haul coal to the port of Newcastle. This system carries over 70 per cent of NSW's coal exports, comprising over 30 per cent of total Australian coal exports. Hunter Valley coal is the largest export industry in NSW, and one of its largest export growth opportunities. However, the industry is under intense pressure in international markets from existing and new coal producers and from other energy sources. Whilst potential growth in demand is substantial, particularly for thermal coal in Asia, excess world supply has pushed prices down, and this underlying trend may well continue. The industry has lost international competitiveness and as a result, investment has dropped 44 per cent over the last two years. The industry must be rapidly structured to compete and attract investment on the basis that these pressures will continue. Substantial productivity improvement and cost reductions must be made for the industry to regain competitiveness, otherwise growth will not occur and the industry will decline, with serious implications for the Australian and NSW communities. The introduction of internationally competitive rail freight rates is an urgent and essential part of this process. It is the key objective of the HVRP.

Jan 1, 1995