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By Lunarzewski L

Gas problems, largely instantaneous outbursts of coal and gas, arose in the early days of coal mining in Australia, leading to attempts at predrainage often including destressing. With deeper mining and new gassy areas being mined, gas problems have increased. This has led to more research, such as into coal-gas relationships, and more practical trials into seam gas drainage in both the Sydney and Bowen basins. Predrainage techniques have been devised to suit the special Australian geological conditions and to take into account the erratic occurrence of CO, (nearly 100 per cent in some cases) in the seam gas. Better mining methods and other improvements are continuing. The introduction of post-drainage has been simplified by the adaptation of long established overseas techniques and equipment.Utilisation of seam gases in Australia is complicated by the presence of CO, but even with pure CH. little has been done.Seam gas drainage has some disadvantages such as the need for, and the dangers of, complex and rigorously controlled plant. Also drained coal becomes harder and dustier.

Jan 1, 1985

By Ryan A, Dennis R, Dekker D, Ellis W, Sowerby B

An automated facility for non-destructive elemental analysis of mine samples has been developed and tested at Mount Isa in association with the CSIRO. The analysis is based on the prompt and delayed measurement of gamma radiation emitted by the sample during and after separate fast and thermal neutron irradiation. No sub-sampling or sample preparation is required and the analyser is operated by one person that would otherwise be splitting drill core in preparation for conventional analysis. The analyser has been calibrated to measure the following (precision in parenthesis): Ag (14 ppm), Pb (0.5 wt%), Zn (0.5 wt%), Cu (0.04 wt%), Fe (0.7 wt%), S (1.1 wt%), SiO2 (0.8 wt%), A1203 (0.07 wt%), Mn (0.05 wt%), specific gravity (0.02 g cmt). Crushed or whole drill core samples that range in size between 0.5 m and 1.8 m of equivalent BQ size drill core can be analysed at a rate of six samples per hour. If required, drill core samples can be re-packed in their original configuration for storage following analysis. Standard samples are measured every day to ensure operational stability. The analyser is controlled by a personal computer which prints the results and stores them along with the raw data on the computer hard disk. This paper reports the performance of the analyser during 1992 for routine analysis of drill core from the lead ore bodies of both Mount Isa and Hilton mines.

Jan 1, 1993

An improved technique for the quick and accurate measurement of the weight and centre of mass in the horizontal plane of large machines has been developed. On-site weighing of large plant such as bucket wheel dredgers is an important part of the commissioning procedure. The results from the weighing assist in determining the stability of the machine and also enable confirmation of the structural weight distribution used for stress analysis at the design stage. In this paper the techniques previously used for weighing are reviewed and the sources of error using these methods examined. A full descrip- tion of the current technique and procedure is given explaining how the measurement system comprising strain gauge load cells, displacement transducers, wind speed and direction sensors, data logger, computer and software was developed to enable quick and accurate measurements to be made. Proposed modifications to software necessitated by the replace- ment of current measuring instrumentation and computer are discussed. A typical example of measurements from the weighing of a large dredger, illustrating the accuracy of the new technique is given and the calibration technique used to check the accuracy of the force and moment measurements is explained. An outline of how the results are used to certify the machine for operation is given.

Jan 1, 1989

Studying the ore textures in a discrete orebody is a novel approach to estimating liberation potential of the ore minerals present. As part of a PhD thesis, this project aims at classifying and quantifying the textures of the Hilton North orebodies, and at estimating their liberation characteristics.

Jan 1, 1993

A sample of fifty fractured low chromium-molybdenum alloy drill steel rods was investigated. Each rod was of the forged collar integral tungsten carbide type in common use in Australia.Examination of a new rod of the same type showed that a zone of spheroidized carbide about 0·25 in. wide was present about 12 in. from the shank end.Examination of the fractured rods revealed that 78 per cent. of failures occurred within 0·25 in. of the spheroidized zone at the shank end but in the main stem of the rod rather than actually in this softened zone where it might be expected to occur.This predominant type of failure at the shank end in the steel rods is caused by a highly anodic region corresponding to the first stages of spheroidization of carbides present in the steel. Accelerated corrosion in the narrow band havil\g this structure induces the formation of stress-concentrating corrosion pits, 78 per cent. of failures in this region being due to corrosion fatigue.The remaining 22 per cent. of failures, occurring in the as-rolled stem, were due to either corrosion fatiglie if failure were initiated at the water-hole surface of the drill rod, or to a decarburized outer surface if failure originated at this surface.Temperatures producing spheroidization were determined as 6007600C.Evidence suggests that approximately 75 per cent, of shank-end failures in all forged collar drill rods can be attributed to corrosion fatigue occurring preferentially in that section showing partial spheroidization of carbides· produced by the forging and hardeningoperations.Methods are suggested for reducing the frequency of fatigue failures in drill rods.INTRODUCTIONAn integral part of all tunnelling operations through rock is the drilling of suitably placed holes i:n.to which explosive is subsequently rammed and exploded.The drilling operation, whether for metalliferous mining or for general civil engineering constructional work; is...

Jan 1, 1955

By J C. de Vries

When times are tough in the mineral industry û as they have been for some time û typical responses by mining companies are to cut costs and/ or increase production. The latter is seen to spread fixed costs, thereby also reducing unit costs per tonne mined. However, most mineral deposits respond to increased production rates by lowering ore grades, so the reduction in cost per tonne of ore does not necessarily result in a reduced cost per unit of metal produced. The authorsÆ experience is that this process often leads to a mine plan that is a long way from optimal. Producing to the point where marginal cost equals marginal revenue may work well in a manufacturing operation, but it is not necessarily the best strategy for a mining company with a depleting resource. Variations in tonnage and grade with depth, ore reserve optimism and a variety of other factors conspire to produce variations in production rates and grade that often result in suboptimal outcomes and potential mine failure. Added to this is the focus of industry analysts and senior corporate management on such measures as unit costs and ounces in reserves. This is perceived to have the perverse effect of driving the share price down when strategies are adopted that actually improve the value of the mining operation, and vice versa! Many mine failures can be prevented by a close examination of the tonnage grade curve and an understanding of how margins, net cash flows and resulting business risk change with cut-off grades and rates of production. A few relatively simple analyses early in the evaluation of a project can demonstrate the tradeoffs between the main decision parameters, leading to right-sizing of the operation. Once major commitments to major capital items have been made, and reserves have been publicly reported, optimisation of the operation becomes much more difficult than if it had been done earlier. Such investigations can also identify the upside potential and downside risks associated with factors outside the companyÆs control. Many strategies that may enhance value in the good times significantly increase the downside risk in the bad times. What is often called risk analysis typically looks at superficial issues, and does not evaluate the major factors leading to the potential for financial disaster. This paper illustrates some of these major risks, and demonstrates how they may be fully evaluated so that corporate decision makers can make fully informed decisions that take account of the real risks.

Jan 1, 2003

By Shu DM, Moxon P

Subsidence profiles over longwalls at West Cliff Colliery (WCC) are predicted by three methods, NCB Emperical Method, Salustowicz's Profile Functions and Superposition of Two Critical Profiles. A method of deriving maximum subsidence using local data is also presented. For the first four longwalls, the results are compared with those from the subsidence surveys conducted during and after the extraction of each longwall. Longwall V has not yet been extracted, so the results are for the predicted subsidence profile. Superposition of two critical profiles is carried out in an attempt to check the principle of superposition. In addition, strata movement above the extracted longwalls is discussed.

Jan 1, 1986

In the search for significant new economic base-metal resources within Australia during the early 1970s BHP's Exploration Department had observed that the majority of lead and zinc con- centrate production in Europe and the USA came from carbonate- hosted Mississippi-Valley-type (MVT) zinc-lead deposits, but Aus- tralia had no history of production from this class of deposit despite several very favourable geological environments, par- ticularly in the large Palaeozoic sedimentary basins. An exploration-research team was established in 1975 and the Lennard Shelf region, near Fitzroy Crossing, was selected as a most promising geological environment. Previous exploration for this class of deposit by other companies in Australia had largely used conventional exploration philosophies (geological mapping, geophysics and geochemistry to identify specific drill targets) but BHP sought specialist advice from a North American expert and adopted a grid-drilling philosophy, which involved wide spaced relatively deep diamond drill holes on a regular grid pattern, and statistical evaluation of the results. This technique resulted in the discovery of the Blendevale Deposit in 1978 in an area which had previously been explored by other companies using conventional methodologies. The deposit was delineated and a pre-feasibility study carried out in 1985 indicated that the resource of 20 Mt @ 8.3% Zn, 2.5% Pb was a marginal proposition.

Jan 1, 1988

By N Davies, M J. Coward, P L. Hissey

Mount Isa Mines has four mining operations in Mt Isa with the X41 and Enterprise Mines producing copper and the Lead Mine and George Fisher producing lead zinc and silver. Each stream contributes ore to their respective concentrator at a feed rate and therefore metal ratio set out by the monthly schedule. Mine Planning and scheduling lead to a sales and operating plan (S&OP) and revenue projections which ultimately derives actual revenue /tonne and therefore cost/tonne. At Mount Isa, both the copper and lead/zinc streams produce ore from relatively new operations to be blended with material from more mature operations. It is critical to accurately predict the metal contribution from each operation in order to gauge the relative performance of each mine. Development mining ore contributions are estimated and reconciled, as are stope and bench sources. Performance is continually measured and assessed during extraction and grade adjustments are made to account for underbreak, overbreak and design modifications. It is critical to not understate or overstate the contribution from one operation relative to the other as this can produce a false picture of operational performance. Identifying process improvements are key to improving the business overall. Ore from the lead stream passes 17 measurement stations and two midstream reconciliation points before delivery to the heavy media plant (HMP), where the metallurgical circuit begins. From this point two concentrates are produced. A zinc concentrate for treatment off site and a lead concentrate for further on site processing. The lead smelter takes 100 per cent of Isa concentrates as well as a contribution from BHP-BillitonÆs Cannington Mine.

Jan 1, 2002

By Beeby C. j, Fernando W. J, Ming M. Q I, Guang Li Xi

Removal of moisture in steam-fluidized, mainly steam-heated, fluidized beds makes possible significant energy savings over conventional forms of large-scale drying. The systens are described and their applications to brown coal and alumina hydrate are reviewed. In application to brown coal the use of the system to permit meeting diurnal variation in power station output, and the use of triple-effect drying to minimise coal usage and to avoid the necessity of recovering in the turbines the energy in the steam from the last dryer are discussed. To facilitate the rapid adoption of the systems proposed, studies are being made of heat-transfer to dried coal, of moisture equilibrium in pressurized and vacuum systems, of tapered beds as a means of reducing carrier steam and permitting wider size variation, and of the use of carrier solids for drying lump materials.

Jan 1, 1989

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 Bartosiewicz H

A method for the determination of the gas content of coal seams is presented which improves upon existing methods. The method makes use of a gravitational technique for measurement of the gas desorbed. The amount of lost gas is estimated by determining an empirical relationship relating the desorption of gas with time for each sample separately. This is to replace the assumption that desorp- tion follows a square root law with time. Laboratory investigations have been conducted which indicate that the square root desorption law does not hold good for carbon dioxide. Results of investigations on various factors influencing the technique are presented. It is shown that co-efficients of the empirical equation are dependent upon the elapsed time and the period of observation. Data about gas pressure measurements is presented and it is concluded that gas pressure can be approxi- mated to 0.6 times the pressure below a column of water equal to the depth of cover. This estimate is good enough for adsorption tests to evaluate desorption co-efficients. The technique for repressurisation of the sample,

Jan 1, 1982

By Kadoya H, Kondo Y

The Harima works were established in 1964 and started operation in 1966. The initial capacity was 3500 t/month of zinc and 1500 t/month of lead. Until 1990 a lot of improvements had been made and the capacity had increased 6600 t/month of zinc and 2200 t/month of lead without enlarging the furnace size. During the ten weeks campaign shut-down at the end of 1990, many modifications were carried out including the enlargement of the furnace shaft area. By these changes, the capacity has gone up to 7500 t/month of zinc and 2500 t/month of lead. In the sinter plant, the amount of SO2 rich gas supplied to the acid plant was raised to 50 000 Nm3/h from 43 500 Nm3/h. An electrostatic precipitator was adopted instead of a venturi scrubber to clean the rich gas. Oxygen enrichment has been continuously operated since August 1991, because the furnace capacity is more than the rate of sinter production. Utilisation of the sinter plant is high being as much as 97 per cent and the sulphur burning rate has been increased. In 1990 the furnace was replaced except the hearth. The shaft area was enlarged to 19.4 m2 from 15.3 m2. The target blast was designed to be more than 36 000 Nm3/h. Tuyere layout was changed to prevent slag breakouts. Due to these modifications shaft condition has been very good. Automatic launder jacket cleaners were installed to increase the lead cooling efficiency. Many other improvements and developments were also made. Coke powder injection from the tuyeres has been successfully operated since April 1987.

Jan 1, 1993

The Peko copper orebody is associated with a body of magnetite rock which it has partly replaced. The primary ore averages about 9 per cent. copper and 4 dwt. gold per ton and locally IS much richer. It consists essentially of chalcopyrite and unreplaced magnetite, with lesser amounts of pyrite, marcasite, pyrrhotite, cobaltite, bismuthinite, native bismuth and native gold. The earliest formed mineral is wolfram, and the latest formed is goethite, so that the temperature of deposition ranged from about 5000 C. to 1650 C. or lower.Oxidation extends to 270 ft., which is 100 ft. below the present water level. The oxidized ore consists of cuprite and native copper, and has replaced more or less massive chalcocite of a former zone of secondary sulphide enrichment. The present zone of secondary sulphide enrichment extends from about 270 ft. to 310 ft. depth.INTRODUCTIONThe Peko mine is about 6 miles south-west of Tennant Creek township in the Northern Territory, adjacent to a small outcrop of hematite rock that projects above an otherwise featureless "bull-dust" fiat.The copper-gold orebody being developed in this mine did not outcrop. It was first detected in 1950 by a surface diamond-drill hole (DDH.1), which intersected primary copper ore at a depth of 400 to 425 ft. This ore contained from 4 to 11 per cent. copper and 1 to 25 dwt. gold per ton. Since then a shaft has been sunk, and crosscuts and development drives have been opened on the 210..ft., 300-ft. and 400-ft. levels, which are also connected by winzes. Two diamond drill holes sunk from the 400-ft. level have intersected theorebody at about 450 to 460 ft., and a winze from the 400-ft. level intersected the lode from 445 to 500 ft. At this point it is 54 ft. wide, and averages 9 per cent. copper. More recently an inclined surface drill hole (Peko No. 1) has cut the lode at 856 ft. to 921 ft., equivalent to a vertical depth...

Jan 1, 1955

By R Belissont, C Veloso, L Senez, F Vasconcelos, E Kleiderer, J Mesquita, Y Basselin

Mont-Wright mining complex is an important asset of ArcelorMittal located in the province of Quebec, Canada. It is composed by Mont-Wright and Fire Lake mines, operating 365 days per annum, and producing 25 Mtpa of iron ore concentrate with 66 per cent Fe. Mont-Wright concentration plant is composed by seven lines with a flow sheet encompassing AG/SAG milling, primary and secondary classification stages, spiral concentrators (rougher, cleaner and recleaner stages) and dewatering unit operations. In this context, an equation called ‘Wrec’ was developed in 1971 with the objective of estimating the mass recovery of the different blocks in the beneficiation plant and support the mining planning works of Mont-Wright complex. This equation was based on the correlation between the results of heavy liquid tests performed with drill core samples and spiral concentrators pilot scale tests, returning an estimative of concentrator yield. However, since its first development, no updates have been done in the equation, which lead to some deviations from expected recoveries in the last years. This is probably due to the changes in the process and in the ore fed into the concentrator during the period. In this way, the study presented here corresponds to the execution of heavy liquid/spirals pilot scale tests with 26 composite samples collected at Mont-Wright deposit aiming at revising and updating ‘Wrec’ equation. Based on test work results, an updated formula was established to estimate the plant recovery and a comparison performed using industrial data showed that the old formula overestimated the real yield by 5.40 per cent, on average. At the end of the study the new equation was incorporated into the mining planning process.

Sep 18, 2023

By Hill G

The Boddington Gold Mine (BGM) is managed by Worsley Alumina Pty Ltd (Worsley) and is located 110 km south-east of Perth, Western Australia. The gold mine, which has operated since mid-1987, was originally constructed to treat 3 Mtpa of gold bearing oxide ores, has subsequently been expanded to treat 7 Mtpa and is presently one of the largest gold producing operations in Australia.During 1990 a Supergene/Basement Plant was constructed to treat 250 000 tpa of copper supergene and hypogene ores and basement ores which contain significant gold grades and which are encountered at the lower levels of the existing oxide orebody. The SupergeneBasement Plant has the versatility to treat a wide range of ore types, producing both gold bullion and copper-gold concentrates. It is a stand-alone facility adjacent to the existing 7 Mtpa gold plant.

Jan 1, 1992

By J O. Okonkwo

AngloGold operates various gold mines in South Africa, the largest of which are situated in the North West province. The impact of AngloGold Vaal River mining operations on the environment and, specifically, on aquifers and groundwater is assessed. The location of such aquifers and plumes is determined by remote-sensing and ground-sensing operations, followed up with the correct placement of monitoring boreholes from which information such as water rest levels, chemistry and geological data is gathered. This study utilises an integrated approach consisting of the following mutually reinforcing phases: Phase 1: Airborne multi spectral scanning; Phase 2: Airborne thermal remote sensing; Phase 3: Ground resistivity survey; Phase 4: Borehole placement; and Phase 5: Sampling and monitoring. The integration of the investigation tools and phases in use at AngloGold Vaal River has been found to be very useful in determining the exact sources of contamination, the direction of flow of such contamination, the positioning of interceptive measures and the analysis of such contamination. This adopted approach will enable the development of flow transport models that will further enhance our knowledge of contaminants in aquifers at the mine and enable management to conduct educated interventions.

Jan 1, 2003

It is hypothesised that increasing the number of loading passes will produce a reduced range of truck payload outcomes compared with four-pass loading. The paper provides analysis to support this hypothesis. It is shown that, hypothetically, loading trucks with five or more passes will result in reduced tendency for overloading and reduced confidence interval for truck payloads that increase the confidence level of containing high end payloads within safe and commercially acceptable limits. Furthermore, increased number of passes provides for more precise bucket load spotting and so improves distribution of payloads within truck bodies. Truck-loading issues examined by the paper include: Improvement in life of driveline components and tyres. Generally tyre costs are relatively moderate; but tyres tend to become an increasingly sensitive performance/cost component as truck scale increases; Reduction of site severity fects flowing on to suspensions, truck frames and structural components generally with potential for reduced long-term repair costs; Less physical body damage due to smaller load increments; Reduced risk of non-compliance with payload limitations for safe braking standards; Increase in loading cycle times tend to increase with scale of loading machinery within the limits of a specific type of equipment (ie rope shovels or hydraulic shovels). Production increase with increased bucket capacity is, to a degree, offset by slower loading cycle times. This is particularly pronounced with front-end loaders but tends to be less noticeable with hydraulic excavators/shovels and electric rope shovels. Decrease in loading time, as a proportion of total truck-cycle time as open pits deepen and dump reaches increase. The production and cost benefits of four-pass loading tend to diminish as truck cycle times increase. The paper also discusses the implications for loading-equipment philosophy to satisfy the future needs of the industry. Cost benefits from upscaling tend to diminish as truck scale increases, so increasing management diligence and close monitoring are required to ensure that expected outcomes are realised. These truck-loading issues have been researched to assess the benefits positive or negative) of four-pass loading in practical scenarios. An attempt is made to determine whether four-pass loading is a æmust-haveÆ or merely a æmythÆ.

Jan 1, 2003

By C Tapia Cortez, C Sammut, S Saydam, J Coulton

‘Like every other commodity, the value of the metals is subject to variation’ (Ricardo, 1817). Mineral commodity price uncertainties have always been a significant issue in mining business due to the close relation between global economic conditions and commodity prices, which commonly generates significant and unexpected price fluctuations. Price forecasts have been driven by economic theory, which states that in the long-run market will be balanced and that prices tend to the marginal cost of production. However, this theory has been misunderstood in the mining industry and future prices through time, in real terms, are assumed to be unchanged. This is unrealistic due to regardless of the cycling nature of economy and the omission of uncertainties. Furthermore, using historical data in traditional price forecast approaches does not guarantee realistic predictions as past events will not necessarily be repeated at the same intervals and with the same intensity. Mining, finance and economic sectors have made significant research efforts to predict prices and control uncertainties through classic linear, Gaussian and probabilistic simulation approaches. However, by definition, uncertainties cannot be measured or accurately modelled. Uncertainties can be identified to measure and manage the associated risks; therefore, uncertainties in mining projects have been historically misinterpreted, erroneously measured and poorly controlled. It is widely known that supply and demand functions drive market prices. While technological development noticeably influences supply, demand is strongly driven by psychological factors, mainly related to customer preferences and lifestyle expectations. Thus, human behaviour is one, or if not, the most important variable to determine commodity prices in a competitive market. During the last decades, alternative methodologies have been used to study uncertainties in human, environmental and market behaviours. Chaos theory, fractals, artificial intelligence and econophysics have been widely and successfully used to investigate complex dynamic systems to address uncertainties over time in the fields of neurosciences, meteorology, aviation and market trading. The application of these techniques in the market suggests a more realistic approach to the business environment. Through the combination of the methodologies above a novel long-run price uncertainties simulation approach that emphasise the differences between risks and uncertainties is proposed in this paper. CITATION:Tapia Cortez, C, Saydam, S, Coulton, J and Sammut, C, 2015. Copper price uncertainties – chaos theory to manage risks in mining projects, in Proceedings Third International Future Mining Conference, pp 261–272 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 4, 2015

By J T. Smit

The theory of froth flotation developed slowly, in almost all cases lagging behind practical developments in the operation of flotation processes. This was largely the result of a lack of understanding of the required basic principles of chemistry and physics, many of which were being developed at the same time. A review of some of the early theories propounded is worthwhile, and should encourage those who are presently studying or practicing flotation to exercise some care in claiming a complete understanding of the underlying phenomena in the art. This paper considers theories presented up to and including those in Principles of Mineral Dressing by Antoine M Gaudin (1939). Of course, developments since that time are important, but they are beyond the scope of this discussion.

Jan 1, 2005