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By Will D

This presentation is to outline the current practice of mechanised stoping a one-metre wide, gold bearing ore body to optimise fragmentation, minimise dilution and reduce stoping costs.Coolgardie underground operations have historically been mined using traditional shrink stope methods, but in this recent economic environment (with falling gold prices and high costs of traditional methods) it was necessary to look for alternative methods in order to reduce costs and increase productivity.Although still in a learning and refinement phase, CGNL is satisfied that it is feasible, practical and more economic to use mechanised long up-hole stope and long-hole rising methods to significantly reduce the mining cost, reduce dilution, increase safety and increase productivity three-fold compared to traditional airleg methods used throughout the Fasten Goldfields.

Jan 1, 1993

By Freeman N

A microcomputer based control system has been developed and implemented at ZC Mines (now Pasminco Mining). The control system maximises throughput at a product size set point while maintaining a "safe" cyclone underflow and mill operating pulp density.To characterise mill and cyclone operation over a range of ore types, 60 circuit surveys were carried out by ZC Mines personnel over a period of four months. The data for each test were model fitted to check for data consistency and to accurately estimate circulating loads.The model fitted results were combined with instrument readings (including in-stream analysis probe assays) and the data checked for ability to predict key variables such as product size and underflow density from measurable inputs.In the resulting control scheme, panicle size and underflow density are not monitored directly, but are predicted by regression equation models based on directly measured variables. The tonnage control loop uses a dynamic model to maximise responsiveness.The system provides a data log output to an mM compatible personal computer at programmable intervals. Comparative data logging over a period demonstrates substantially smoothed circuit performance.The grinding control system was originally implemented using Fischer and Porter micro-DCI controllers. The program has also been implemented on a distributed control system using a sequence oriented programming language.

Jan 1, 1990

Brunswick Mining and Smelting Corporation Limited operates a large base metal property near Bathurst, New Brunswick in eastern Canada. Nominal capacity for the underground mining operation and concentrator is 10 250 DMT/day. Four concentrates are produced by differential flotation technology to recover minerals containing copper, lead, zinc and silver. Two characteristics of the Brunswick ores have a major impact on mineral processing operations. The mineralogy of the ore is complex with a total sulphide mineral content of 85 per cent. In addition, the ore is extremely fine-grained, and satisfactory liberation is difficult to achieve. These characteristics directly influence flotation selectivity and thereby affect metallurgical performance. Significant improvements in metallurgical performance have been achieved through the application of basic grinding and flotation principles using conventional milling equipment. Current operating practice and the metallurgical advancements are detailed.

Jan 1, 1993

By Newell R

The situation in which a gas stream flows through a bed of solids is found in many extractive metallurgy operations. Examples include blast furnace smelting, sintering and pellet firing. In such cases the resistance of the bed to fluid flow and heat transfer is of major significance to the operation of the process. This depends on the structure of the bed, which in turn is influenced by the manner in which the materials are charged to the bed. In this work, packed beds of hematite pellets of two different sizes were prepared in which the pellets were charged as a uniform mixture and in layers. The porosity, flow resistance and heat front velocity were measured and compared for the different bed configurations. For layered beds, the overall porosity and heat front velocity increased while the flow resistance decreased when compared with the values obtained for the uniform mixture. The size of the layers also had an effect on flow Properties.

Jan 1, 1991

By Jensen B

The investigation of the explosion characteristics of nine Bowen Basin (Central Queensland) dust samples in a suitable coal dust explosion chamber using a new dust concentration probe provides several advances in the area of coal dust explosibility testing. The 20 litre explosion chamber, of novel design, uses rotation of the main body of the chamber together with air jets for dust dispersion, and allows testing of different types of explosion initiators and analysis of the explosion characteristics of coal dust/methane mixtures of varying concentrations.A new development was a dielectric dust probe for the measurement of coal dust concentration. A capacitive micrometry technique was successfully adapted to measure dust concentration. The system uses a ratio-transformer bridge for measurement of small changes in a capacitive probe designed to sample a representative volume. The device is accurate, and is capable of operating in the hostile environment within the explosion chamber.The explosion chamber and dust probe characterise the explosive potential of coal dust samples by determination of the dust lean limit concentration in varying mixture with methane. Plots of lean limit points obtained in this way present an explosion curve for each sample which indicates the potential of the coal dust/methane to explode under the conditions of initiation in the chamber. The explosion curve obtained for each sample presents a unique signature that appears to reflect the physical and chemical characteristics of the dust.The results from this series of laboratory experiments appear to provide a useful index and indicate potential areas of interest for future research.

Jan 1, 1991

By Hagen G, Uhlig H

In the Federal Republic of Germany the thermal environment in underground coal mines has deteriorated progressively over the past years. The number and capacity of refrigeration plants have increased correspondingly. In recent years high capacity spray coolers have been used in addition to conventional cooling coils.

Jan 1, 1988

By Hermann J. A

Over the last few years enormous dapooits of high-grade bauxite have been discovered in Australia, ;_ d an alum .nium smelting industry based on them is rapidly being developed,, This industry requires large amounts of carbon, as about 60 pounds of carbon anodes are consumed for every 100 pounds of aiumin.'.'-n produced. Tie anodes are usually made by mixing finely ground petroleum coke with coal tar or petroleum pitch, forming the mix into shapes under pressure, and baking them at around ?.200¦C0 Petroleum coke is ussd uecause its high density gives good strength and conductav_ty to the finished electrode, and its purity ensures that contamination. of the alumin- ium by extraneous i,iorganic material from tho carbon is low,

Jan 1, 1969

By Chugh Y. P

A generalized void diffusion model for subsidence prediction has been developed based on theoretical concepts and physical principles. The general form of the model is a three-dimensional differential equation. With a few assumptions on the characteristics of overburden strata overlying typical room-and-pillar mining or longwall mining systems, specific solutions for the differential equation were obtained. A brief description of these solutions and their applications in the United States and China are presented in this paper.

Jan 1, 1992

By Potter DJ, Firkin GR

The Imperial Smelting Furnace operated by Sulphide Corporation Pty. Limited at its Cockle Creek zinc-lead smelter was recently equipped with tuyeres angled at 25 degrees instead of the usual 10 degrees. This change was prompted by the results of model studies undertaken by tha Research Department of Imperial Smelting Processes Limited, at Avonmouth in the United Kingdom, and by the favourable results of operating trials on the Cockle Creek furnace using bent-tip tuyeres to simulate 25 degree inclination. The use of 25 degree angle tuyeres has made it possible to operate with lower zinc values in discard slag and has improved hearth stability over a wider range of sinter quality and composition.

Jan 1, 1981

There are a number of examples of how environmental factors have been integrated into the water management aspects of mining projects. The Kingston Lignite project in South Australia, Pine Creek Gold Mine in the Northern Territory, gravel and sand extraction from the Nepean River flood plain near Penrith, and the Olympic Dam Project have all illustrated that consideration of environmental factors can be integrated with project developments, with beneficial outcomes for both the project and the environment.Each of the above cases demonstrated an individually significant environmental issue, directly related to the interaction between the proposed project and its environment. In each case, careful research and an integrated approach to the problem resulted in a solution that gave both maximum protection to the environment and optimum consideration to the economic feasibility and success of the proposed project.The solutions ranged from alternative mining methods and improved waste and water management through to the ultimate objective of converting a mining project into a major water-based recreation source. These examples have set a precedent that will contribute ignificantly to the successful development of future projects.

Jan 1, 1988

By Lawson F

Synthetic calaverite (Au Tez) has been prepared and its physical properties checked.Simple flotation tests indicate that the recovery of calaverite should be possible using n-butyl or sec-butyl xanthate collectors under approximately pi I neutral conditions with a copper sulphate activator.Roasting calaverite in air at moderate temperatures resulted in its decomposition with the formation of elemental gold and tellurium dioxide.In alkaline oxygenated cyanide solutions, both gold and tellurium tend to dissolve. At pHs less than 14, about 50 per cent of the tellurium remains as elemental tellurium; however in very strongly alkaline solutions, essentially all of the tellurium is converted to the soluble tellurite ion (TeOl-).However, even at high pHs, the solubility of gold in the cyanide solution is still low due almost certainly to passivation effects.

Jan 1, 1991

The Cadjebut Mine is located 80 km southeast of Fitzroy Crossing. Cadjebut is owned 58 per cent by BHP Minerals and 42 per cent by Billiton Australia. Cadjebut is a 'Mississippi Valley Type' (MVT) deposit. Minerals present are sphalerite, galena and marcasite in a sedimentary host of dolomite and siltstone. The ore contains few deleterious impurities and no silver. The mill was commissioned in the first half of 1988 at a rate of 320 000 tonnes per annum. An expansion in the latter half of 1989 has since increased production to 550 000 tonnes per annum. The initial geological resource at the commencement of mining was 3.8 million tonnes at 13.5 per cent Zn and 4.4 per cent Pb. There is sufficient ore left to sustain operations to 1995 at a grade of 11.2 per cent Zn and 3.9 per cent Pb. The ore from underground is stockpiled on the surface via a drift conveyor and from the stockpile is fed into a grinding circuit consisting of a SAG and ball mill. Cyclone overflow at a Pgp of 90 pm gravitates to the flotation circuit. Lead and zinc are sequentially floated to produce an 80 per cent Pb grade at 90 per cent recovery and a 61 - 62 per cent Zn grade at 96 per cent recovery. The concentrates are thickened and filtered before being trucked to the port of Wyndham 600 km away. From Wyndham the concentrates are shipped to smelters in Asia, Europe and Australia.

Jan 1, 1992

By Bhattacherjee A, Makesh S

Mechanised sub-level stoping is one of the most widely accepted stoping practices followed in base metal mines in India. As a general practice, blast-scheduling of rings in these stopes is done either heuristically or randomly which leads to a high fluctuation in ore grade when drawn and delivered to the mill. In this paper, dynamic programming has been investigated as an optimisation technique for optimal blast-scheduling of rings. A microcomputer based dynamic programming algorithm has been developed in C language which runs under the UNIX environment. A case study based on Indian mine data is presented to demonstrate the application of the dynamic programming concept and use of the developed software. It is concluded that dynamic programming can be used as a production planning tool in Indian mines practicing sub-level stoping and following heuristic/random approaches for blast-scheduling of rings.

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

A Kellogg type computer model of the slag fuming process is applied in reverse to derive some thermodynamic properties of components in lead blast furnace slag. At 1200¦C, the average activity coefficients calculated were 3.40 (S.D. 0.50) for ZnO referred to the pure solid; 0.657 (S.D. 0.022) for PbO referred to the pure liquid; for the ratios y 3.175 y (referred to the Feo.9450, Fe304 pure solids) 4.19 (S.D. 1.15), and for yCaS/ 1CaO (referred to the pure solids) 5.10 (S.D. 2.96). Statistical relationships were derived for these activity coefficients and ratios as functions of the composition of slag, which contained in molar percentages 1.9 - 12.6% ZnO, 19.8 - 24.9% Fe0.9450, 0.9 - 1.6% Fe304, 0.002 - 1.9% PbO, 16.1 - 18.6% CaO, 25.9 - 31.0% SiO2, 4.8 - 5.5% MnO, 9.2 - 10.3% A101.5, 1.2 - 1.4% CaS, and 5.1 - 9.6% "Mgo" (the balance).

Jan 1, 1980

The calibrated thermal IR data of part of Cambay Basin is used to determine surface temperatures and to detect the heat flow. Applying the conductive heat flow continuation technique, the three dimensional configuration of the hydrocarbon bearing reservoir was defined. The zone delineated by the present study coincides with the oil-bearing structures inferred by seismic survey. The results indicate the possibility of the technique as an effective tool in hydrocarbon exploration.

Jan 1, 1986

By Gross A. E, Neville P. C

Over the last decade heap leaching with a cement binder has allowed the economical leaching of low grade gold ores of less than 2 grams/tonne. Despite the continued use of cement as an agglomeration aid, numerous leaching operations continue to experience channelling and blinding problems. This paper describes the development of polymeric agglomeration aids, Extract Ore 9760 and 9960, which when used as a partial cement or lime replacement can result in a higher rate of and/or a higher total gold recovery in plant evaluations. Extract Ore in combination with cement acts to produce a stronger agglomerate which results in reduced fines migration during leaching and helps prevent blinding of the heap. Both of these changes will give a more even flow of cyanide solution throughout the heap and improve solution contact efficiency within the ore. Polymeric agglomeration aid programs are now being used by heap leaching operations in three different countries. A summary of benefits identified at some of these operations are presented in this paper.

Jan 1, 1994

By Peverett N. F

The purpose of filtration in a gold reco- very plant is to separate the gold bearing liquid from the solids in the slurry. Some of the gold is inevitably lost due to incomplete separation. An investigation recently completed by the authors has brought to light a method of reducing such losses. In this investigation, the filtration pro- cess was represented by a steady-state mathema- tical model which took account of 14 indepen- dent variables and three parameters. One of the filters in the plant at West Driefontein Gold Mine in South Africa was isolated from the rest and fully instrumented. A computerized data acquisition system was installed close to the filter, and the data obtained from it served to test the model. Using the model together with an optimizing program, the optimum operating point for the filter as a function of throughput was found, and a control strategy developed to minimize the total gold losses in the filter plant.

Jan 1, 1977

Having provided basic data in the main paper I would now like to move on to discuss these areas in broader terms and to examine the various coalfields in terms of their tectonic setting and depositional environment and ultimately to make some brief comments on the factors which may have controlled deposition.

Jan 1, 1975

By Wasp E. J

A review is given of recent commercial long distance slurry pipeline systems in- stalled worldwide. The technological advan- ces in slurry engineering and system opera- tion are discussed, together with a brief re- view of the economics of slurry transportation and future trends in the industry.

Jan 1, 1973