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A synthetic gold-silver telluride material (mainly sylvanite) has been prepared and its physical and chemical properties checked. Flotation tests using a Hallimond tube were conducted using commercial xanthate collectors. At collector concentrations of 10-3M with the addition of 5 × 10-4 M CUS04, no obvious differences in the mineral recoveries were seen irrespective of whether amyl, secbutyl, isobutyl or isopropyl xanthates were used. However, when the concentration of xanthate was reduced to 10-4 M or in the absence of the copper sulphate activator, the effectiveness of the collectors was in the order: amyl > secbutyl > isobutyl > isopropyl > ethyl. Changes in the slurry pH appeared to have little effect on the recovery of the telluride mineral.Leaching tests of the precious metal telluride showed that both gold and silver dissolve in alkaline oxygenated cyanide solutions but at a much lower dissolution rate than metallic gold or silver. Both leaching tests and electrochemical measurements indicate that the dissolution rate of gold-silver telluride is controlled by the pH and cyanide concentration of the leachant.Roasting the gold-silver telluride materials in air at temperatures between 550 and 750°C resulted in its decomposition into a metallic gold-silver alloy and tellurium dioxide.

Jan 1, 1994

A consideration of mining ventures and the changes of an environmental nature that occur. The paper is introduced with a general statement claiming recognition that mining ventures are important to human well-being but that these need to be justified against the environmental changes that they bring about. The various factors that need to be considered are cited followed by an historical review of mining activities. The various environmental issues are discussed under three headings; socio-economic, physical and biological, prior to reviewing the world's demand for minerals including fossil fuels. In conclusion guidelines for appraising mining ventures relative to environmental changes that may occur, are given.

Jan 1, 1981

Conditional simulation is a branch of geo- statistics which allows the simulation of a mineral deposit so that predictions can be made about the variability of some particular parameter of the deposit. A summary of the general principles, advantages and limitations of conditional simulation is presented together with an example based on coal seam thickness.

Jan 1, 1981

Rockbursts, as they occur in South African deep level gold mines, have a lot in common with natural earthquakes. Both violently release seismic energy and cause damage to underground and surface structures. Rockbursts are the main cause of fatalities in deep gold mines and the problem may increase in severity with future mining at greater depths. Although the emphasis in Rock mechanics is on the prevention of rockbursts, prediction would provide a partial solution to the rockburst problem. A research project was initiated in 1981 on Western Deep Levels to investigate the possibility of detecting and identifying precursive microseismic activity. This project has succeeded in locating potential sources of seismic events with reasonable confidence. The timing of these events may be estimated with less confidence, and an important parameter, namely the potential size of the rockburst, still cannot be determined. An example of a large seismic event and its associated precursive activity are discussed. Practical prediction systems will, at least for some time, involve subjective decision making which will place a new responsibility on the mine manager as well as the rockburst specialist. The moral pressure on the manager as the final decision maker will probably be greater than the fear of leqal prosecution.

Jan 1, 1986

By P Hucker, E Hall

Harmony Gold operates the Mount Marion underground gold mine near Kalgoorlie, Western Australia. The mine consists of two ore zones, East and West, and mining of these zones is currently conducted using the sublevel caving method. When mining commenced in the Western zone, the span was insufficient to induce caving of the country rock above. Dyno Nobel, together with Harmony and 360 Drilling, developed an innovative drill and blast solution in order to promote cave propagation and improve the safety of personnel at the operation. The solution involved a series of shallow angle drill holes up to 90 m into the hanging wall of the West zone. These were charged with Titan« 7000 underground bulk emulsion and the HotShotÖ electronic initiation system. The blast used over seven tonnes of emulsion and 46 detonators and achieved the desired result without damaging nearby mine infrastructure.

Jan 1, 2007

By Equivar J, Mirabal C, Pyper R

In 1984, work was started to determine the viability of heap leaching silver-containing waste dumps from Cerro Rico near Potosi - Bolivia, at an elevation of 4300 meters (14 100 ft.). The result today is an unusual heap leach utilizing fine crushing, grinding, and agglomeration to process 1000 tonnes per day of ore containing 200 g/tonne silver. The unique metallurgi- cal, economic, and political factors will be discussed which led to the decision to build a heap leach rather than a conventional agitation leach plant. Capital and operating costs will be given along with some of the uncommon process design and equipment problems encountered while developing the operation.

Jan 1, 1991

Blasting, particularly bench blasting, uses finite length cylinders of explosive close to two free faces. The rock to be blasted is usually intersected by a complex 3-D system of joints. To fully simulate a blast, a 3-D dynamic model is required. It is shown that the static stress distribution around a long cylinder can be reproduced by superposing the static stress distribution of a suitable chain of spheres. Thus, the dynamic results for individual spheres given by Favreau (1969) can now be substituted for the static results to give a dynamic model of the stress distribution around a long cylinder. Comparison of measured and computed waveforms show that the measured waveforms are much more attenuated and dispersed than expected. The consequences for explosive evaluation and design are Discussed.

Jan 1, 1990

Magneto flotation is a recently developed method aimed at simultaneous utilisation of the magnetic and flotation properties of minerals in separation processes. In this method, magnetic minerals are prevented from reporting to the froth product while non-magnetic minerals are being floated. With suitable ores, this makes it possible to reduce or entirely eliminate the cleaning and scavenging operations that are otherwise necessary in conventional flotation and magnetic separation systems. This paper describes the testing of magneto flotation on a Canadian magnetite ore. The ore sample used in the experimental work contained a total of 32.89 per cent Fe of which 87.60 per cent was magnetic in the form of magnetite. Magnetoflotation yielded, in a single step, a final concentrate assaying 69.10 per cent Fe and with an overall recovery of 84.84 per cent representing a magnetic iron recovery of 96.39 per cent. Comprehensive comparisons were made with conventional magnetic separation and flotation, and it was found that with these methods at least four processing steps were required to achieve results similar to those obtained with single-stage Magnetoflotation.

Jan 1, 1993

The problems associated with achieving adequate accuracy for on-site axial flow fan performance measurements are discussed. The ability to test accurately rests heavily on equipment and installation design detail.Aerodynamic performance trials frequently cannot be carried out due mainly to the poor standard of installation design. In a majority of cases this results in unsteady, non-uniform inlet flow conditions to the fan. Details of installation design features and instrumentation, necessary for successful testing, are given for different types of installations and methods of testing. These cover both conventional practice, and new innovations which can provide solutions to difficult problems. Quantitative aspects of flow measurement are considered for various fan and duct configurations.Although the main emphasis is on large primary mine ventilation units which require on-site testing, the principles outlined have wide application to many other types of fan installation.

Jan 1, 1973

By Clark I, Stockton N, Warren L

Nickel flotation circuits currently experience difficulties in recovering fine particles of pentlandite less than ten microns. By agglomerating these particles using shear-flocculation it is hoped to improve the recovery of these fine particles. A sample of massive sulphide ore from the Kambalda region was separated using magnetic separation to obtain a high grade pentlandite concentrate (> 90 per cent). This was finely ground to produce a sample with particles of 50 per cent minus 10 um in size. This sample was then shear-flocculated using a variety of reagents, including xanthates, dithiophosphate and mercaptobenzothiazole (MBT). The effects of reagent type and concentration, conditioning time, impeller speed and type, and pulp density were studied. Froth flotation tests were also conducted on the shear flocculated pulps to compare the effects of xanthate and MBT on the recovery of pentlandite.

Jan 1, 1992

By Moorrees C, Koh P. T L, Tsambourakis G

Examination of Ihe calcination and carbonic acid leaching behaviour of a number of Australian magnesites shows that there are substantial differences between the massively crystalline and the cryptocrystalline forms of magnesites. Crude magnesias formed by calcination of the massive variety of magnesite have considerably smaller surface area and show lower rates of reaction with carbonic acid when compared With those derived from cryptocrystalline magnesites. In order lO producc a rcactivc magncsia from massive magnesite, the calcination conditions must be carefully controlled over a narrow temperature range (eg 680-720°C). For the cryptocrystalline calcines, the temperature of formation has little effect on reactivity.The results confirm the general applicability of the calcination/carbonic acid leach process for producing magnesia from magnesitc. If a mixed crystalline/cryplocrystalline feed is to be processed, then processing conditions must be optimized in terms of the behaviour of the crystalline component of the feed.

Jan 1, 1985

By J G. Webster-Brown

The Tui Mine is located near Te Aroha at the base of the Coromandel Peninsula. It was a lead-zinc mine, which closed in 1973 due to declining concentrate prices, high overheads, and high mercury levels in the ore. The site was abandoned, leaving behind an acid rock drainage generating system, including a sulfide-rich tailings dam which has since caused pollution of Tui Stream, as well as open adits and waste piles which drain predominantly into the neighbouring Tunakohoia Stream. At the AusIMM conference in 2003, Harvey and Webster-Brown presented water quality results from the Tui mine site and lower stream catchments in 2002. In April 2006, Environment Waikato undertook remediation works to stabilise the dam and reduce acid drainage entering Tui Stream. In this study, water quality results from the Tui mine site and lower stream catchments are again being determined, in order to compare with the pre-remediation results. Preliminary data collected for summer indicate a minor but consistent improvement in water quality in the lower stream catchments, although lower Tui Stream continues to exceed ANZECC (2000) aquatic life guidelines for Cd, Cu, Pb and Zn. This slight improvement may be due to a decrease in the flow of ARD into Tui Stream, as there does not appear to have been an improvement in quality of the contributing ARD waters.

Jan 1, 2007

By E Kozan

The paper presents new developments of the methodology of open pit coal production scheduling optimisation. They deal with the specific features of the exploitation of single coal seam and utilisation of truck-shovel and dragline systems. A production scheduling optimisation model is developed as a linear programming problem. The objective function maximises the net present value of the mining project under the technological constraints for meeting the demand function of the coal processing plant and effective utilisation of the available production equipment. Both principles of mine planning, coal quality optimisation and waste deferment are incorporated in the model. Results of a case study are provided to illustrate the applicability of the optimisation model.

Jan 1, 2003

Mine dewatering has long been a problem with mines and some of the shallowest mines have the biggest problems. Machinery was developed by the ancients for raising water by rope buckets with treadmills or by horse whim. From the 1700's on into the early part of this century, massive cornish pumps or equivalent were the vogue powered by steam. One Australian mine pumping system was claimed to be the largest in the world just after the turn of the century. It was installed at Beaconsfield in Tasmania and the mine, like so many other mines of the period, were beaten by problems and cost associated with mine dewatering. The owners of that mine are looking at the feasibility of dewatering using surface drilled wells. Much simpler and smaller pumps are the order now and it is feasible to use boreholes instead of shafts to contain the pumps or else to use the holes to convey discharge waters to the surface from pumps located in drives or stopes.

Jan 1, 1988

It is now becoming mandatory in Australia to rehabilitate ponded fine grained coal mine tailings, which may well have been deposited initially with no consideration as to how or whether this could be done nor to the costsinvolved. Of prime importance to the rehabilitation of tailings ponds are the bearing capacity and deformation characteristics of the tailings. Since the tailings are fine grained, time effects will govern the self-weightdeformation of the tailings initially deposited as a slurry and the subsequent deformation of the deposit under the weight imposed by rehabilitation fill. The engineering properties of a particular deposit of ponded tailings havebeen investigated and its response to the placement of fill monitored and analysed.

Jan 1, 1987

The Queensland Magnesia Project is based on a unique cryptocrystalline nodular magnesite orebody which required an innovative approach to process design in order to economically exploit the characteristics of the ore and produce a marketable range of high quality refractory magnesias for a declining world market. High quality natural refractory magnesia must have an MgO content in excess of 95 per cent with a very strictly controlled content and ratio of residual impurities such as calcium, silica and iron. The natural products compete with magnesias derived by chemical extraction from sea water or brines which exhibit very high purity but often lack other characteristics which are of value to refractory brick makers. Since start up in late-1991 QMAG has achieved a remarkable market penetration for both its deadburned and electrofused products with sales for the 1993/94 financial year representing 92 per cent of deadburned capacity and 138 per cent of original electrofused capacity respectively, all at a time when the world steel industry has been in recession.

Jan 1, 1995

By Peng S. S

Measurement of pressure distribution under the base plate of the Hemscheidt 2-leg 800-ton shield was performed underground for two shifts using 12 pressure cells installed in two rows, one each under each split base plate. Pressure distribution was uneven depending on contact condition. In general the highest base pressure occurred at 1/3 of the base plate contact length from the rear edge. The resultant was near vertical, and the pressure under the tail side split base plate was always higher than the head side. For comparison, pressure distribution on the canopy and under the base plate was also measured under controlled conditions at the USBM's Mine Simulator Testing Facilities in Pittsburgh, PA. A total of 45 tests were conducted under several simulated contact conditions. The results showed that the actual contact area is highly dependent on the compliance of the immediate roof and floor due to the sloped canopy tip and a base lifting device under the base tip. The loading distribution tends to change in magnitude and profile as the leg pressure increases. The base lifting device exaggerates the high toe loading on the base plate characteristics of this type of shield support.

Jan 1, 1992

This paper describes a case history of using an integrated geochemical and hydrogeological approach to predicting solute transport from gold mine tailings in highly fractured volcanic terrain. Two modes of transport are identified, namely discrete fissure flow and diffuse seepage through the intervening weathered rock. A simple mass balance approach is used to predict concentrations at points of emergence because most of the seepage migration will be by way of the discrete fissures where advective transport will predominate. The mass balance method has been modified to allow for natural degradation of weak acid dissociable cyanide. The long term effects of diffuse seepage are also examined.

Jan 1, 1988

By Larke R, Warnock J

Although Western Mining Corporation has been producing high grade nickel ore at Kambalda since 1967, it has only recently become a significant gold producer.The main source of Gold ore has been the Victory Gold Mine located 17 kilometres South of Kambalda.This mine produced small tonnages of high grade gold ore from a sediment horizon within a complex sequence of mafic flows, in the 1890's, early 1900's and 1930's.Today, mining is centred around 2 com-pletely different ore bodies named Victory and Defiance, and involves several different mining methods. This paper describes the Operation's history and gives an outline of the proposed stoping methods.

Jan 1, 1984

Sasol Roche Blasting Services (SRBS) has undertaken a process of trialing and evaluating the use of the SMI electronic initiating system with the specific purpose of being able to fully quantify the benefits of the system over a pyrotechnic system. After an initial trial of three shots in mid-2001, it was decided that to fully quantify the system, a complete strip would need to be fired using the system so that any losses due to ramps or end walls would be the same for both scenarios. The results have shown a significant improvement over the use of pyrotechnic initiators in several key areas including percentage cast. Through the use of survey results, the increase in cast and subsequent net improvement in blasting has been quantified. These trials have set out to compare each system in comparable situations to determine the real benefits, if any, of the electronic system over the pyrotechnic one. As the percentage cast is relatively easy to quantify using modern survey techniques, it was decided that this would be the principle method of comparison. However, while the assessment only included survey results, any improvement in fragmentation size and consistency would have flow on effects on reduced running and maintenance costs.

Jan 1, 2003