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By Christie AB

Stream sediment geochemical analyses from 140 mining company exploration surveys of the Coromandel, Northwest Nelson, Marlborough and Westland regions of New Zealand have been compiled from open file reports and entered on a database called REGCHEM (for Regional Exploration GeoCHEMistry). REGCHEM is supported by GEOEXPL, a custom-written computer software application which operates under the Microsoft Access relational database mangement system on a PC-type computer. The data are plotted as maps using the Maplnfo geographic information system (GIS) package. Thesholds separating anomolous values from background values are determined using the PROBPLOT univariant statistical package, which enables the descrimination and modelling of several populations. Relevant REGCHEM data are being incorporated into a GIS for the Coromandel region as part of ongoing studies to sevelop mineral deposit and metallogenic models for the region, and to assess regional prospectivity.]

Jan 1, 1995

By G Davies, D Dunn, C Mawdesley, O Bertoli

The coal industry in Australia has been actively working in recent years towards the (re)integration of geostatistical techniques to the process of coal resource estimation. The benefits of using geostatistical techniques, over the current interpolation algorithms in use in coal modelling packages used to generate the grid estimates, need to be illustrated for the methodology to gain a broader acceptance in the coal industry. This paper focuses on the benefits gained at BHP Billiton Mitsubishi AllianceÆs Saraji mine for the estimation of the total product yield value at a 9.7 per cent product ash cut-off of a particular seam of the Saraji deposit. In order to perform this comparison, the results of the alternative estimation methodologies need to be benchmarked, which in most situations is achieved through the reconciliation of the estimates against production and/or process plant reconciliation data. Unfortunately, this benchmarking was not possible as no reconciliation data for the area of interest in the chosen seam was available, as it has not been mined at the time of the study. Where no reconciliation data is available, an alternative method is to use conditional simulations as the benchmark for comparison. The simulated values can be regarded as ærealityÆ, and the alternative estimation methodologies, based on a sampling of the underlying ærealityÆ, can then be compared using the simulated ærealityÆ as the benchmark for comparison.

Jan 1, 2009

In this paper presented are the criteria used when assessing the harmfulness of shocks affecting the buildings. Those criteria are based on the value of speed or accelerations of building vibrations. Presented is the scale of harmfulness of vibrations of Langefors and Kihlstrom, Bureau of Mines, and SWD contained in the Polish Norm PN-85/B-02170. The parameters of the mining shocks measured by the Lubin coal mine station were compared with the parameters calculated as per the correlations (regression curves). The average acceleration calculated from the correlations for eight measurements is only two per cent higher than the actual one. But the average frequency of vibrations calculated from the correlations for eight measurements is as much as 2.22 times lower than the actual one. In order to analyse whether that takes place in the whole range of the energy of shocks compared were the results of calculations from the correlations for various magnitudes of shocks and various distances from their epicentre with the results of the measurements. From that it follows that only for the shocks of the highest energies the lowering of the frequency of vibrations by two times causes movement from the higher zone of harmfulness to the lower one (for example from the IV to III). In the one-family houses in Lubin there were the damages that are characteristic for not only for the III but also for the IV sphere of harmfulness as per the SWD scale. That should be explained via further research and maybe it would be feasible to draw out a new correlation to determine the frequencies only for high values of energy of shocks and determine the preciseness of the acceleration and frequency correlations used presently.

Jan 1, 2003

By Thimons E. D, Derick R. L

In early June, 1986, a fire of unknown origin erupted in one of several main entries of a coal mine located in southwestern Colorado. The fire was aggressively fought with high-expansion foam. As a result of several strategic decisions, the fire appeared to be held in-check. Unfortunately, sufficient quantities of foam were unavailable and as soon as the foam was depleted, control of the fire was lost. To prevent further damage and the possibility of an explosion, all entries to the mine were sealed.

Jan 1, 1988

By C P. de Jager, J J. Taljaard

Over the past 75 years, the mining of platinum has predominantly focused on the Merensky Reef horizon in the western Bushveld region of the Bushveld Igneous Complex (BIC) of South Africa (Figure 1). The orebody is relatively flat dipping at 10¦ to 25¦, narrow tabular in shape and has been mined to a maximum depth of some 1600 m within Anglo Platinum. This has resulted in the installation of up to four generations of shaft systems as mining progressed into reserves at greater depth. In recent years, with the improvement in processing technology and improved economics, in particular with the improved price of palladium, the mining of the UG2 Chromitite Reef is proving economically viable. The UG2 Chromitite Reef occurs below the Merensky Reef in the succession and the normal separation varies from 15 m to 400 m, with the largest separation between the reefs occurring in the eastern region of the BIC. The UG2 Chromitite Reef horizon is now being accessed from existing Merensky mining infrastructure by cross-cutting back through the stratigraphy where appropriate, or by establishing new decline cluster systems from surface, along the extensive strike length of the various mining properties. These declines are generally established utilising mechanised mining techniques. This paper gives an overview of the techno-economic approaches considered and evaluated for the selection of the optimum mining and shaft systems. More specifically, the paper reviews the design parameters used, techno-economics, conveyor versus haul alternatives, logistics simulations, capital costs, system performance, time to market or ramp-up success, important system differences and lessons learnt.

Jan 1, 2005

By Fountain C. R

In April 1987, Mount Isa Mines Limited (MIM) commissioned an ISASMELT reactor to smelt 15t/h of copper concentrate at the Mount Isa Copper Smelter. This unit was based on the Sirosmelt lance technology and incorporated features proven in the Lead ISASMELT plant which has been operating in the MIM Lead Smelter since 1983. From April 1987 to June 1989, the copper smelting plant treated 167000 tonnes. Concentrate, coal and fluxes are fed continuously to the furnace. Oxygen enriched air is injected through a lance which is submerged in the slag bath. Matte and slag are tapped together through a single taphole into a reverberatory furnace, and from there are treated with normal reverberatory furnace production. Advantages of the process include its ability to eliminate most lead and arsenic in feed, its flexibility with respect to feed composition, sizing and moisture, and the plant's low capital cost. Acceptable refractory life has also been demonstrated. The commissioning of a 70 t/day oxygen plant has rerated the plant from 15t/h to 18t/h while allowing a reduction in fuel usage of one third. A trial using 150 t/day oxygen was carried out in May 1989, and showed that the furnace could treat 48 t/h chalcopyrite concentrate while maintaining a very low fuel requirement. The oxygen trial results have given considerable confidence for plant scale-up. Detailed project evaluation is currently underway for the replacement of the roaster and reverberatory furnaces at Mount Isa with a single 110 t/h ISASMELT reactor.

Jan 1, 1989

By Ueki S

Underground coal gasification (UCG) is a promising process for obtai- ning energy from coal, which is either unmineable with current mining techno- logy or uneconomic to recover, using conventional methods, in the present energy market situation. There are several coal fields, which could become new coal reserves, if the UCG process were successfully applied. In the 1960's Japanese researchers made a number of basic studies and field tests into UCG, although not all of them produced favourable results. This paper reviews Japanese research on UCG. This includs basic studies into coal gasification using a small, tube reactor fed by air and oxygen, and also large scale model stu- dies(reactor size of 8.Om x 2.4m x 1.5 m). Field test results from Akabira colliery in Hokkaido and a feasibility study of power generation using UCG from a coal field in Hokkaido are also Presented.

Jan 1, 1987

By Kohra A, Shoji S

The amount of copper production by flash smelting process occupies about 17% (equivalent to 1.4 million t/year) of total free world production. In Japan, 650,000 tons of copper is produced annually by flash smelting. This is 65% of the gross copper production of Japan. To reinforce pollution control, promote energy saving, and enhance production efficiency by increasing the size of furnaces, conventional blast furnaces and reverberatory furnaces are being replaced with the flash smelters worldwide. The Ashio Smelter started copper production in 1884 and developed in association with the Ashio mine. In those days, the Ashio smelter produced copper by using the blast furnace process designed for the high-grade ore from the copper mine. At that time, this process was specialized in Japan. In 1956, for the first time in Japan, the Ashio Smelter introduced the flash smelting process developed by Outokumpu Oy of Finland (it is suitable for treating the copper concentrate, producing sulfuric acid and improving production efficiency). The flash furnace in Ashio, the first ever in Japan, had a capacity of 230 t/day for copper concentrate and was operated up to 1962. During this period, various operational troubles were solved, and further improvements were made; and, in 1962, a Furukawa-type flash smelting furnace was completed in Ashio. This improved version of a flash furnace had a capacity of 450 t/day. There was one flash furnace and one waste heat boiler, which were arranged in a unique pattern for that time. This furnace may be said to be the prototype of the present flash smelting process in the world.

Jan 1, 1987

The major slime forming minerals in coal seams are generally montmorillonite, illite and kaolinite, and due to the consistant trend to full seam mechanisation in New South Wales and Queensland these minerals remain in the feed to a coal preparation plant. After coming into contact with water their size degradation is very rapid, and therefore they mostly report to the fine coal cleaning section of the plant. Froth flotation, being the most effective method of beneficiating fine coal, is widely practised in these two major coal producing states of Australia. Plant experience and laboratory tests suggest that the presence of these slimes in the flotation circuit depresses the flotation of fine coal. Although the deleterious effects of slimes on the flotation behaviour of minerals is well known, the mode of their adsorption at the mineral surface has been a subject of controversy for some time. In this paper, on the basis of the surface properties of slime forming minerals and coal, a model has been put forward to explain the adsorption of slimes at the coal surface. The degree of slime coating has been examined by scanning electron microscopy. Laboratory tests have revealed that with the appropriate use of polyvalent phosphate electrolytes these slimes can be liberated from the coal surface. Just attrition and desliming are not enough to ensure complete liberation of slimes. Coal, after treatment with these electrolytes and then deslimed, floats readily with a common frother, such as MIBC. Modifications in the conventional flotation circuits have been suggested to ensure an efficient flotation of fine coal.

Jan 1, 1978

This paper records the observations of faulting in the Black Star mine workings. By classifying the faults into two groups, i.e., strike faults and transverse faults, and by pointing out the differences between the groups and their effects on the silver-lead-zinc orebodies, a time relationship between the two groups of faults and the sulphide mineralisation is suggested.GENERAL GEOLOGY AND MINERALISATIONFolding and faulting are closely related to the mineralisation in the shales by silver-lead-zinc and iron sulphides.Commonly the various sulphides are fine-grained and closely associated with one another. However, exceptions do occur locally, where massive coarse galena, sphalerite, pyrite, and to a lesser extent chalcopyrite, have been observed singly or closely associated one with the other.In the main, the sulphide mineralisation forming the orebodies occurs as replacement of, and infilling along, the sheared bedding planes of the finely bedded shale host rock.The shales in general strike north-south with an average dip to 60° to the west; strong shearing along the bedding planes is evidenced by much slickensiding and slaty cleavage.Sequences of finely bedded shales of varying stratigraphic thicknesses alternate with very. massive beds, and it is in the more highly sheared thinner beds that the greatest concentration of sulphides occurs. The unmineraIised massive beds of shale, 11 in. up to 12 in. in thickness, occur singly or in groups between, and to a lesser extent. within, the orebodies. The massive beds resisted sulphide replacement and impart to the orebodies a most prominent banded structure.

Jan 1, 1953

By R Herbert, M E. Malmstr÷, S U. Salmon

The study focuses on sulfide oxidation processes in unweathered pyrite-rich mine tailings from a soil-covered impoundment in northern Sweden. To simulate the oxygen-limited conditions in water saturated tailings two long-term column experiments were performed. Results are presented for the first 11 months of the experiments at room temperature. The tailings used in the experiments were of two different grain sizes (one coarse grained, in the range 0.02 - 0.6 mm with a grain surface area of 1.86 m2 g-1, and one fine-grained, in the range 0.0015 - 0.06 mm with a grain surface area of 10.00 m2 g-1) and with slightly different mineralogical composition. The S:Fe molar ratio in the leachates (1.0 - 1.5) indicates either that pyrrhotite is the main iron sulfide undergoing oxidation in our experiments, or, alternatively that the S:Fe molar ratio in the leachate is determined by pyrite weathering in conjunction with other processes releasing iron or immobilising sulfate. However, speciation modelling of the leachates indicates that ferrihydrite was close to saturation, suggesting that a ferric oxyhydroxide may have dissolved/ precipitated during the experimental period, thereby affecting the S:Fe molar ratio. Pyrite oxidation rates obtained from the two column experiments during æsteady-stateÆ were 2.25 + 10-13 and 8.45 + 10-14 mol m-2 s-1 in the coarse and fine tailings, respectively. Pyrrhotite oxidation rates, as an alternative, were 2.31 + 10-12 and 1.24 + 10-11 mol m-2 s-1 in the coarse and fine tailings, respectively. Natural microbial activity was confirmed in both the tailings and the leachates; therefore, the obtained oxidation rates are not strictly abiotic. It is thus concluded, based on the experimental results, that tailing heterogeneity will result in zones with different oxidation rates, related to their physical and chemical properties.

Jan 1, 2003

By Musa MA

Tunnel excavation for sewer construction long remained a labour intensive, hazardous and costly operation. Even with the of mechanical and semi-mechanical shields for tunnel excavation, many problems remained until recently. In the past decade, however, the technology has changed dramatically which has made possible the use of advanced tunnelling methods for sewer construction.

Jan 1, 1993

By Y Potvin

Risk assessment in the mining industry is currently a topic of great interest with risk methodologies being increasingly applied beyond the traditional areas of finance and feasibility to analyses of risks due to various physical hazards including chemical, electrical, mechanical and geotechnical sources. The application of risk analysis and evaluation techniques to the management of personnel safety is being promoted by both industry and regulators but, particularly for geotechnical hazards, often there are inadequate databases for a meaningful quantitative calculation of risk. In Western Australia over the decade 1987 - 1997, the annual fatality rate for underground mining has averaged at approximately 1.3 in 1000 employees with rockfalls/rockbursts accounting for over half of these deaths (Prevention of Mining Fatalities Taskforce, 1997). Recent improvements have been made since this time, perhaps halving the annual fatality rate, mainly due to industry improving ground control measures and implementing various recommendations from the Prevention of Mining Fatalities Taskforce (1997). However there still remain a large number of unknowns when trying to address the complex area of geotechnical risk in mining. Risk calculations require information about the source of the hazard, the people or assets exposed to the hazard (the æelements at riskÆ) and the effects on these vulnerable elements if the hazard actually occurs (the potential consequences). To date, little information has been available on the exposure of mining personnel and equipment to underground hazards other than occupational safety studies on chemicals, heat, dust, etc. This paper concentrates on underground geotechnical risks and presents a data collection and rating system for the exposure of both the underground workforce and equipment to rockfalls and rockbursts. The methodology considers exposure times, personnel protection levels and hazard proximities to give exposure ratings for the major underground mining activities and hence rate different locations within a mine. This exposure methodology is then applied to the workforce and production/ development cycles in an actual WA underground mine, creating a snapshot map of differing levels of personnel exposure across the mine.

Jan 1, 2003

By E Widzyk-Capehart

The conventional ammonium nitrate fuel oil (ANFO) loader utilises a pneumatic system to control the flow of ANFO (via rotary actuator/ball valve) and air (via an auxiliary air valve). This system, though relatively simple and reliable, has several drawbacks with respect to ease of control and level of automation. In this paper, a radio frequency (RF) remote control for explosives charging is discussed. The system design incorporates electric solenoid valves to control the rotary actuator and the auxiliary air valve. All operations associated with explosives charging are selectable at the remote and are completed according to a modifiable time sequence. This allows the following charging sequence to be reduced to a single momentary application of the remote:removal of water from the hole prior to charging with ANFO; charging of the hole for a preset but adjustable period of time; and removal of the remaining ANFO from the ANFO hose. A specially developed remote switch allows the operator to maintain two-handed control of the ANFO hose whilst achieving full control of the charge-up process. Failsafe electronic architecture is incorporated into the systemÆs design to increase safety to the highest level. Should the RF remote control fail, a wired remote is included in the system to allow for the charging process to continue, albeit at a reduced level of control. The application of the RF remote control system in an underground explosives charging operation minimises and/or eliminates many problems associated with the use of the conventional charging system. These include: the wet-hole problem, trip and entanglement hazards, air embolism and the two-man loader control requirement. The developed remote control unit proved to be effective at removing water from wet holes leading to increased face advance per drilling operation. It proved to be economically feasible, allowed for an increase in systemÆs dependability and safety factor and for a truly one-man operation which resulted in reduced manpower.

Jan 1, 1999

By Alesse V, Belardi G

A new class of collectors, Mercapto-Benzo-Oxazoles (MBO), exerting selective action on copper sulphides in the presence of Pb, Zn and Fe sulphides (galena, sphalerite and pyrite), has been synthesised in co-operation with Enichem's Donegani Insitute. The collectors have a mixed aliphatic-aromatic structure and contain functional groups which form chelates with copper. Some reagents of this class having hydrocarbon chains of various lengths have been laboratory tested on a complex sulphide ore containing chalcopyrite, galena and sphalerite in pyritic gangue. Comparative flotation tests have permitted selection of the best collector for chalcopyrite, namely Methyl-Mercapto- Benzoxazole (MMBO). Systematic flotation tests have been performed with this reagent, varying collector concentration, grain size of the feed, pH and flotation time. The results obtained show that the synthesised collector is much better than potassium-amylxanthate (KAX) as regards selectivity towards Pb and Zn. Moreover, it is possible to work at natural pH (6-7) and the flotation rate is higher. In fact in the rougher stage with 80 g/t of collector at natural pH, a copper grade of 7.14 per cent was obtained with a recovery of 73.87 per cent, while the grade with KAX did not exceed 2.11 per cent for a recovery of 73.54 per cent. The amount of Pb and Zn reporting in the copper concentrate was eight per cent and ten per cent respectively, while with KAX it was no lower than 24.34 per cent and 22.71 per cent in that order. After two minutes flotation a copper grade of 5.2 per cent with 52 per cent recovery could be attained, against a grade of 2.5 per cent and a recovery of 44 per cent in the case of KAX. The efficiency of this new collector has been ascertained on two samples of complex sulphide ores of diverse mineralogical composition.

Jan 1, 1993

This paper will discuss specifically the performances of vibrating screens having circular motion with inclined decks and linear motion with horizontal or near horizontal decks and both related mainly to coal, metalliferous, and other granulated solids applications where screening and efficient classification is required. Some misconceptions have been applied in the past with regard to making a screen type selection using either circular throw or linear throw and therefore this paper will endeavour to clarify these misconceptions.

Jan 1, 1984

Acclaimed as one of the most remarkable orebodies anywhere on account of its length and richness, the Oroya Shoot occurs on the eastern side of the Kalgoorlie gold mining district close to the contact of a fine-grained with a coarse-grained greenstone, and in association with sediments. In the same stratigraphic position on the synclinal flanks of a large drag fold there are a number of other flat ore pipes, smaller, but almost as rich in tenor. Although differing in control structure they are believed to be related genetically as all show a characteristic development of a bright-green ore known locally as "green leader". Folding and bedding structures have played an important part in formation of the ore shoots.INTRODUCTIONThe Oroya Shoot is the biggest individual bonanza of Kalgoorlie's Golden Mile. It has been stoped almost continuously over a length of 4,300 ft., and about 2,000,000 oz. of gold have been won from it. Naturally pillars are not left in the best sections of such an orebody and the detailed geology of stoped out portions can only be inferred from examination of adjacent workings.No mention is made in the literature of the actual makeup of the orebody although a few structures are shown on some of the old cross sections. A diagrammatic cross section, Fig. 1, adapted from Stillwell (1929) illustrates the form of the Oroya Shoot.Gustafson (1937) drew attention to the role of folding, previously unrecognized, in Kalgoorlie geology, and indicated that the Oroya Shoot is associated with a minor drag fold on the east limb of the Brownhill Syncline, itself part of a larger left hand drag on the Central Anticline. The latter in turn appears to be part of a regional right hand fold system as shown by Campbell (1953).

Jan 1, 1959

By Pathan AG

This research work is concerned with an investigation of the fracture toughness of sandstone, siltstone, and coal. Tensile failure trades have been examined with three different specimen geonetries, i.e; rectangular bar, round bar (in three point bending), and diametral compression discs. The Stress intensity approach, and J-integral methods were used to evaluate fracture toughness. Results from both approaches are discussed. True crack length was determined after pre-cracking, using the compliance calibration technique. Fracture toughness results of sandstone are independent of crack length and the size of the specimen. Fracture toughness may hence be regarded as a material property for sandstone. In cxnntrast fracture toughness values for !siltstone and coal are dependent on crack Length.

Jan 1, 1986

By de Brodtkorb MK

Late Cenozoic ore deposits "Precious and base metal-rich" and " Sn-Ag-polymetallic"of Northern Puna are associated either with Middle Miocene dacitic volcanic-dome complexes or with Upper Miocene dacitic-andesitic volcanic centers. Ore mineralogies and their related volcanism are discussed. A strong link is observed between the Cenozoic Metallogenetic Province of Northern Puna and the Southern Bolivia Tin and Polymetallic provinces.

Jan 1, 1995

By McKenzie C, Michaux S

Modern quarrying operations focus attention on blasting operations as a critical component in the overall cost-effectiveness of quarrying. Generally, optimisation of blasting has been linked to the processes of drilling, explosive consumption, secondary breakage, and product haulage to the primary crusher. This approach gives no consideration to the impact of primary crusher feed size distribution on downstream processes, or on the quality (ie shape and strength) of the final product. Blasting operations can be manipulated to produce a wide range of muckpile size distribution. This paper presents the results of studies into the impact of muckpile fragmentation on downstream crushing and screening operations, and includes measurements of primary blast oversize and muckpile fragmentation, together with measurements of size distribution, circulating loads and flakiness for various process streams throughout a quarry processing plant. This paper is an extension of other studies investigating the prediction and control of fragmentation from blasting, and the role of explosive performance in controlling muckpile fragmentation.

Jan 1, 1995