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The aspect ratio (mill diameter/mill length) of autogenous and semi autogenous mills varies widely and can be as high as three or as low as 0.5. The literature on the subject of what effect aspect ratio has on grinding mill performance or energy efficiency is almost non-existent. However, at the design stage of many grinding circuits the subject is often vigorously debated amongst metallurgists. In this paper the performance characteristics of mills with different aspect ratios are examined to determine whether process performance characteristics are a function of aspect ratio and whether high aspect ratio mills are any more or less energy efficient than low aspect ratio units. Data from both pilot and full-scale mills are used for this purpose in open and closed circuit configurations.

Jan 1, 2007

The Australasian Institute of Mining and Metallurgy brings together, voluntarily, people with a professional interest in the disciplines and skills which are employed in the mineral indus- try, and in relation to that industry. We come together because we have a mutual interest in improv- ing what is done by the mineral industry, in all its aspects. It is this sense of continuing improvement, of doing better, of doing as well as we can, as our knowledge and skills improve, that unites us in creating and fostering a professional association of like- minded people. We know from our professional training and experience that enormous progress has been made, at an ever-increasing rate, in the mineral industry, particularly in this Century. We know that the mineral industry has played a very major role in providing the means by which so many more people survive to live longer, healthier and more interesting lives, than ever before. Indeed together with the oil and gas industry, which is an integral part of the mineral industry but has achieved its own commercial dis- tinction, it is fair to claim that the mineral industry has played the major role in providing the means for the advancement of the human quality of life.

Jan 1, 1988

By Windsor C

A review of the current pit design procedures and their performance has been undertaken recently by Mining Research Associates (MRA) and the CSIRO Division of Geomechanics. Visits were made to mines covering a wide range of operations. A questionnaire was completed by each mine in order to collate the relevant information. Interviews were also made with representatives of the Mines Departments to ascertain their role in regulating mine designs. Design expectations were compared with field performance, and reasons for variations noted. Problems associated with designs were identified and suggested methods of alleviating the problems have been made.

Jan 1, 1986

By W A. Tchernykh, R P. Strelnikova

In connection with the fact that technology of ore mining by caving system is often used when mining of deposits, characterising by low stability of surrounding rock mass, the main problem for such ore mines is ensuring stability of mine workings, placing in a zone of influence of winning operations. Besides natural disturbance of ore mass, stability of workings depends on the dynamic effect of blasting operations and also on the dynamic effect of structural blocks detaching from the ore mass and colliding with crests of ore pillars in the bottom of a chamber. Decreasing of dynamic stresses may be achieved by way of creation of a compliant porous screen or an ore cushion in the chamber bottom. It is established that maximum levels of compression take place when the first impact impulse occurs, and after that increase of compression of protective slice decreases. Necessary thickness of screen slice was substantiated theoretically with due account of height of structural blocksÆ fall, their mass, deformation modulus of ore mass and ore cushion.

Jan 1, 2003

By A S. Ray, P S. Thomas

The characterisation of the surface area and porosity of opals derived from Tintenbar, a volcanic environment, and Lightning Ridge, a sedimentary environment, using nitrogen gas adsorption at -196¦C is reported. Both opal types were found to have relatively low surface areas and displayed little porosity. The low surface areas observed is indicative of the ability of silica to infill voids and interstices. Thermogravimetric analysis of the samples before and after degassing was carried out to determine the amount of water removed by the degassing process. Negligible difference was found in the water content before and after degassing in the case of the Lightning Ridge sedimentary opal, while the Tintenbar volcanic opal was found to have lost more that 60 per cent of its water during the degassing process. These differences were ascribed to the differences in the silica structure of the opals with the Lightning Ridge opal having a denser cage structure, which traps the molecular water, while a more open structure is postulated for the Tintenbar opal, allowing the water to be relatively easily removed.

Jan 1, 2008

Modern off-highway trucks have evolved over 30 years from small 20 ton units to vehic- les with capacities of up to 170 tons. Diesel engines are used by all manufacturers while transmissions are either mechanical or electri- cal. Development over the years has kept pace with component availability from engine, trans- mission and tyre manufacturers.Computer simula- tion studies are recognised for purposes of vehicle evaluation and costing under various op- erating conditions. Several manufacturers are currently manufacturing or evaluating vehicles with capacities of up to 260 tons. This paper describes the essential facts associated with the operation of off-highway trucks of the rear dump type in the mining industry.

Jan 1, 1973

By M L. Habner, S D. Munro

In a gold CIP/CIL circuit, adding new circuit water to a final tails thickener and then directing the thickener overflow to the head of the circuit significantly reduces the cyanide concentration at the TSF discharge spigot. The new water is used to dilute the final tails. The dilution and recycle of the tails in this manner may have the added benefit of reducing reagent consumption, in some cases to the point where the reagent savings justify the expenditure and Cyanide Code compliance is achieved at no extra cost. Potential circuit configurations and water recycles can be modelled by splicing a flowsheeting and thermodynamics package, such that changes to the composition of the water can be reduced to chemical speciation with a Gibbs free energy minimisation enabling a complete understanding of the circuit water chemistry.

Jan 1, 2007

By Giannini L, Kelsey P

A fundamental problem in mine planning is the determination of the production schedules over the life of the mine. The objective is to maximise profit in terms of the net present value without transgressing the physical constraints of the mine

Jan 1, 1998

By Bennet A. G

As part of the construction of the Melbourne Underground Rail Loop it was necessary to construct two 7 metre diameter tunnels, each 100 metres in length, by shield driven excavation through an alluvial valley at Elizabeth Street. The tunnels had a primary support of bolted precast reinforced concrete liner blocks and were excavated with the aid of compressed air. The work was undertaken by the Tunnelling Group of the Melbourne and Metropolitan Board of Works as nominated sub-contractor to John Holland (Constructions) Pty. Ltd. The paper describes some of the problems associated with the construction of the above tunnels and the methods used to overcome them. In particular

Jan 1, 1981

Diagnostic Monitoring of Concentrator Circuits with Random Forest Models

Sep 13, 2010

Longhole stope overbreak has always been a source of unwanted cost within the underground mining industry, and efforts to control it using various rock reinforcement systems have long been a rock engineering challenge. At the Pasminco Mining Broken Hill Operations trials have been carried out using an innovative cable bolt reinforcement system known as Rib-Roc. The system, based loosely on the Swedish Rib-in-Roc concept, utilises zones or ribs of heavily reinforced rock in the troublesome hangingwall and back areas of longhole stoping. The trials were carried out under a strict qualitative and quantitative scientific stope measurement program utilising rock mechanics instrumentation. Not only did the trial demonstrate the success of the system but data obtained was useful in implementing the system virtually as standard practice throughout the operation.

Jan 1, 1995

By Isokangas T. A

With some two-thirds of the production exported, coal mining prac- tices of the last few years in Australia have been much influenced by the decline in the price received. It became essential to improve efficiency and rationalise operations. Trends in underground practice vary. On the one hand many additional longwalls have been installed and most recently the results achieved by them have shown a significant up-turn; this may be correlated more with increases in equipment capacity than with utilisation which has altered little during the past six years. Varied constraints remain affecting cur- rent and future longwall operations. On the other hand a number of mines have been closed whilst others have sought to improve results by various installations including miniwalls, shortwalls, and use of continuous haulage and mobile breaker line sup- ports. All mines continue to review working practices.

Jan 1, 1988

Polyacrylamide flocculating agent has been used in the Leaching Division of the Risdon Works of the Electrolytic Zinc Co. of Australasia Ltd since October, 1960. Since the introduction, the.: number of thickeners in use in the continu-ous thickening stage has been reduced from eight to three; there has been an increase of 25% in throughput and a reduc-tion of solids in.:thickener overflow from 3-4 gòpòl . solids to 0.5 g.p.l. solids. Reagent addition has been at the rate of 0.25. lb SEPARAN, NP10 per ton solids.Additionally there has been a gain of 3% in current efficiency as the direct result of the addition of SEPARAN NP10 to purified cadmium sulphate solution prior to electrolysis for cadmium metal. A smoother deposit has resulted and it has been possible to increase deposition time between strip-pings from 47 to 71 hours. However, there has been a slight increase the lead content of the cadmium-metal produced.

Jan 1, 1963

Both innovation and excellence are desirable attributes of education, as they are also markers in the progression of the human race, but how attainable are they? The interaction of minerals and humanity provides a special insight into the development of both criteria, from the discovery that chert cuts, through the Bronze Age and the first use of metal alloys for implements, to using coal, oil and uranium as sources of fuel. However, there have been many hiccups along the way, where excellence in one respect has meant disaster in another. Examples are in the exploitation of asbestos, and in traditionally poor work practices in mining, both contributing to the widespread public belief that minerals and mining are ecologically undesirable. Yet is this perception based on the unrealistic expectation of innovation and excellence being simultaneous qualities of any given process? Common sense born of experience indicates that the journey from one, to the other, is usually a long and often tedious process, with much trial and error before excellence is attained. In our time, the partnership between academia and industry is the usual pathway to achieve it. Even so, we should take care that innovation does not become overwhelmed by the pursuit of excellence: as history clearly demonstrates, humanity depends upon both.

Jan 1, 2004

By Binns RA, Murao S

The PACMANUS and Jade deposits are two active hydrothermal fields that are forming massive sulfide deposits at the Pacific rim margin. Both are associated with felsic submarine volcanic rocks and both occur in back-arc settings. However, PACMANUS is associated with almost sediment-free dacites and lies on the crest of a volcanic ridge, whereas Jade occurs in a heavily-sedimented tectonic depression associated with a basement of pumiceous rhyolite. The PACMANUS deposit is richer in Cu and Au, and Jade in Pb. Zinc, Ag, As and Sb contents are similar. Sulfide textures at PACMANUS suggest formation of Cu and Zn sulfides by simultaneous double-diffusion involving inwards-moving seawater mixing with outwards-moving hydrothermal fluid. By contrast, at Jade there is a more complex history of formation where initial growth of barite on the sediment surface, probably associated with microbial activity, formed an impervious cap which trapped higher temperature hydrothermal solutions.

Jan 1, 1995

This paper presents a summary of the technical achievements of the Port Pirie Smelter in 100 years of lead smelting and refining. It also aims to give where possible the reasons or circumstances that led to the achievements. The major achievements took place in the areas of sintering, blast furnace, copper drossing, copper recovery, lead refining and slag fuming.

Jan 1, 1989

By Bell MG

At various decision points in the development of a project, a developer, joint venture partner or financial institution may require an independent review of the basic assumptions and technical aspects of the project. This type of review or technical audit is becoming a more common feature of the project development process. This feature has evolved because of the need of investors and lenders to be more confident of the viability of a project by the confirmation of its technical and cost aspects. Technical Audits offset some uncertainties introduced by the combination of longer development periods for, projects and the highly dynamic world economic scene. This paper reviews the place, nature and process of the technical audit by examining the circumstances when it might be needed, the typical scope of work or brief, the responsibilities of and relationship between the auditor and the client, and the auditing procedure. Detailed aspects of technical audits are discussed followed by a case study of the Hail Creek Coal Project Audit.

Jan 1, 1983

By Huajun W, Long LZ

The composition of fly ash and formation mechanism of cennospheres are introduced in this paper. The signification of using this potential new mineral processing resource is emphasised. The beneficiation properties of the components of fly ash, such as susceptibility, specific gravity, size, shape and flotability etc have been examined in detail. A technique was designed to process fly ash from the XiGaoJing power plant in Beijing, and a flowsheet is also presented. Flotabld cennospheres, magnetic beads, sinkable beads, carbon and advanced pozzolamics can be obtained as separate products through this flowsheet. It is emphasised that the beneficiation of fly ash is an efficient means of totally utilising the resource. Examination of the products show that they have good physico-chemical properties. Possible areas of their application are also Suggested.

Jan 1, 1993

By L Gladysiewicz

This paper deals with the current situation in the mining industry in Poland. An overview of typical transport systems working in the different branches of mining is provided. The transport systems currently used in lignite mining, particularly in the Belchat=w mine û the largest brown coal mine in Poland, and those operating in copper mines are described in detail. New designs of belt conveyors used in underground hard coal and copper mining are presented.

Jan 1, 2003

Two separate mine rehabilitation programmes carried out by Australian Consolidated Industries Limited (A.C.I.) in South Australia at Normanville and Port Lawler are discussed. Emphasis is given to the methods used, the results achieved and to possible future improvements.

Jan 1, 1976