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Reduction of Iron Content from Silica by Gravitational Processes In this research work, it was attempted to reduce the iron contents (Fe2O3) in silica sample which was provided from Shenin silica mine using gravitational processes including jig machine, multi gravity separator (MGS), shaking table and spiral. The silica sample contains 93.75 per cent SiO2, 0.44 per cent Fe2O3, 2.78 per cent Al2O3, and 0.08 per cent TiO2 and the Fe2O3 has to be reduced to about 0.1 per cent or less than 0.02 per cent. Mineralogical studies and XRD analysis indicated the presence of haematite, pyrite and goethite as the major iron impurity phases. Mineralogical studies of polished and thin sections yielded that the degree of freedom of silica is more than 80 per cent in the range of -300 +212 mm. After elimination of fine particles, at first nine tests were carried out on crusher product (in two size fractions), wet rod mil product and scrubber product by means of Jig Machine. The best results were obtained with about 0.15 per cent Fe2O3 on rod mill and scrubber product which was not desirable. Thereafter 7 tests were carried out using shaking table; the best results were obtained with about 0.14 per cent Fe2O3 on rod mill and scrubber product which was not desirable. MGS showed the worst result in order to iron removal from silica which was not desirable. Finally 9 testes were carried out using spiral whish is the best gravitational separator for elimination of iron impurities from silica. The best result of spiral tests were achieved on scrubber product. In this test concentrate weight percent and its Fe2O3 grade were 82.32 per cent and 0.085 per cent respectively. Finally a test was carried out using 2 stages of spiral in order to develop flow sheet. In this test concentrate weight percent and its Fe2O3 grade were 78.8 per cent and 0.1 per cent respectively. This product can be used to produce float (clear flat) glass.

Sep 13, 2010

When lying over 200-250m depth, many seams and surrounding strata are gassy enough to create mining difficulties , particularly in highly productive longwalls as well as in their development headings. In addition to the gassiness of seams or stra- ta in the outgassing volume around working, the shape expansion and limits of this one influences much the intensity of gas emission. These charac- teristics of outgassing volume differ very much ac- cording to the permeabilities of the seams and strata encountered by their fracturation due to mi- ning. Moreover, the shape of the outgassing volume is very much modified by the rate of advance of the face. In nearly impermeable deposits, gas flows from a limited outgassing volume. When the rates of advance of a face are medium or low, the shape and dimensions of this volume do not change very much and outgassing volume is translated progressi- vely with the face advance. This explains why, in the past, it was observed that there was for each seam an average steady specific emission of gas, round which the volume of gas evolved per mined ton or per mined unit area, calculated over a cer- tain time, was oscillating. Combined with a statisti- cal irregularity coefficient, this allowed prediction gas of emission and thus to take decisions for air ventilation, drainage, and eventually production.

Jan 1, 1988

By Glaessner M. F

The island chains of the Western Pacific (Fig. 1), on account of their related origin, and the similarity of the rocks that compose them, constitute in the main a most homogeneous mineral province. They lie in a complex "mobile" zone of the earth's crust, that formed a geosynclinal area separating the continental margins of Australia and South-Eastern Asia (the so-called Sundaland) from each other, and from the margin of the Pacific Ocean proper (FIg. 2). The whole region was drowned at the close of the Ice Age, as a result of the rise of sea-level that accompanied the melting of the great ice caps in the polar regions, leaving only the higher portions as islands and peninsulas, many of them separated only by shallow seas or "shelves."The geosyncline was infilled with Mesozoic and Tertiary sediments that have undergone varying intensities of folding and metamorphism, and has been subject to intermittent periods of volcanic activity, continuing into the present. Midway between the two continental margins there is a narrow belt of pronounced negative gravity anomalies, with an extraordinary S-shaped convolution in the vicinity of the Banda Sea and Celebes, that marks the core of this unstable region. The folding within the "mobile" zonetrends parallel to it, so that the islands in its vicinity, which are regions elevated by folding, are all elongated in the strike direction of the folds. This explains not only the linear shape of Sumatra and Java, but the arc of islands enclosing the Banda Sea, and the peculiar shape of Celebes.Parallel to the belt of negative anomalies, at a close remove from it, is the line of Recent, or active volcanoes, that extends along the whole length of Sumatra and Java...

Jan 1, 1947

By Bhattacharyya A. K

A major constraint on sustaining high rates of production in the collieries of the Southern Coalfield of New South Wales is the inability to develop panels fast enough to match the rates of extraction. This inability is particularly crippling in the case of retreat longwall mining and is due to nearly half the time in roadway drivage being spent on strata control operations such as roof support.Increased rates of roadway drivage and significantly improved roadway stability can be achieved by the application of yield pillars between parallel roadways. These pillars are designed to yield immediately upon formation and transfer the damaging roof loads away from the immediate vicinity of the roadways. Since the width of the yield pillar is the key to their successful application, it was determined through the Yield Pillar Experiment conducted by Kembla Coal and Coke Pty Ltd at West Cliff Colliery.Three experimental headings, each nominally 5.5 m wide and 2.8 m high, were driven to form two tapering pillars. The width of these pillars progressively decreased from 24 m to 3 m over a length of 154 m. The convergence between the roof and floor of the headings measured at various cross-sections corresponding to predetermined widths of the pillars are analysed in this paper to evaluate the stability of the tapering pillars at the different widths.The width of the yield pillar in a three heading development layout at West Cliff Colliery was determined to be 7.5 m.

Jan 1, 1995

Mine planning typically involves designing an operation to uncover coal with the minimum initial costs with reclamation planning and earthworks being done as an "add on" task. The landform is too steep to remain stable, has no drainage and frequently has areas of excessive acidity or alkalinity. Extensive earthworks are required to reduce grades to an acceptable level and create a drainage system. The flexibility available to the mining engineer to alter the post mining landscape clearly depends on the mining methods. Straight dragline stripping provides virtually no flexibility. However most mining operations over the term of current ten year plans have a substantial pre-strip component. It is this pre-strip material which has the potential to reduce the final reshaping earthworks. The reshaping operation itself is subject to some flexibility with various options being available to re-grade and provide drainage. The full utilisation of this flexibility to minimise earthworks cost should be the aim of reclamation design. ACIRL's current thrust in reclamation is aimed at the integration of mine planning and reclamation earthworks. This involves gathering all environment and agricultural criteria and designing the earth works necessary to produce an acceptable final landform. A key component of our work is the use of computer aided design (CADD) for the design of spoil piles, pre-strip dumps and spoil re-shaping. This approach has been applied to a number of mine sites with earthworks operations covering hundreds of hectares and hundreds of millions of cubic metres volume. We are continuing to provide that consultancy service and at the same time are involved in the development of more sophisticated software tools to apply to reclamation design.

Jan 1, 1991

By Wharton C. L

This paper describes a new computer program which can significantly increase the Net Present Value of either an open cut or underground mine by optimising the cut-offs used during the operating life of the mine. It was developed over a period of about three years by Whittle Programming Pty Ltd of Melbourne, Australia. Several authors have contributed to the theory behind this work, but the ideas were further developed, consolidated, and clearly explained by Lane (1988). It was this book that triggered the development of the new program. The paper starts with an explanation of the theory behind this type of optimisation, and then goes on to describe the computer methods used to optimise the different parts of the problem.

Jan 1, 1995

By Nag D. K

The Dolphin Scheelite orebody is located near the old mining town of Grassy on the south-east comer of King Island in Tasmania. Surface open cut mining of the Dolphin deposit was conducted for a number of years, then the proximity of the sea and adverse stipping ratio led to underground mining. As a result of the variable orientation and dimensions of parts of the orebody a number of mining methods were practiced at the Dolphin mine until 1990 when a combination of high processing and surface site costs coupled with low tungsten prices led to the cessation of operations. In this paper the different mining methods practised are examined and critically reviewed. The more successful mining methods were developed with experience and improving equipment technology to the extent that the underground operation produced ore at the lowest unit cost during the final years of operation.

Jan 1, 1995

Lightweight polymer grids have recently been introduced to the mining industry. They are currently being used for roof and rib control, longwall shield recovery, safety guarding or barricade, highwall screening, internal reinforcement of gunnite/shotcrete applications, sub-base reinforcement, construction of steepened slopes, retaining walls, mine reclamation (i.e. erosion control, turf reinforcement), and in numerous mining waste related projects. These polymer mining grids utilize a strong, lightweight polymer, usually special grades of polypropylene or polyethylene. High tensile strengths are achieved by molecular orientation of these polymers in the manufacturing process. The first step in the manufacturing process is to extrude the polymers into thick continuous sheets. These sheets are then punched, and drawn into open grid structures. Aperture size and configuration are controlled by the geometry of the punched hole and the degree to which the grids are stretched. The drawing process is the key to the molecular orientation required for the tensile strengths. These long chain polymer molecules in their natural state have a random orientation. When stretched, the molecules are pulled into a parallel alignment, thus creating a lightweight product with tensile strength comparable to Steel.

Jan 1, 1992

The orebodies at Kambalda are complexly faulted, folded and intruded. It is realized that the ore reserve calculations will be wrong and steps are taken to minimise the errors. The calculations are a combination of computer data handling and manual input. Initially Geological Ore Reserves are calculated and then production data and experience are used to produce a Planned Mining Reserve. At all stages maximum professional judgement is incorporated. The basis of the calculation is the polygonal method of area estimation, and production reconciliations together with the style of data available indicate that it is a most suitable technique. It is also a tech- nique that is easily communicated to all levels from operators to management.

Jan 1, 1979

By Amelunxen R, Finch JA

Flotation columns represent an important addition to flotation practice. Columns have largely replaced. conventional machines in molybdenum cleaning in Canada. Columns have been successfully tested on bulk copper/molybdenum cleaning at Gibraltar Mines Ltd. A rougher cleaner/scavenger cleanercombination was shown to be capable of giving higher grades and recoveries compared with three stages of conventional cleaning. A control strategy for the columns has been developed. An interaction between gas hgldup and wash water rate has been exploited to control performance.

Jan 1, 1985

By Williams SR

Column Flotation cannot be used indiscriminately. Based on extensive pilot plant experience at Lakefield Research, a number of limiting parameters have been identified for the application of column cell flotation. Parameters of importance are the use of wash water, flotable mineral content, pulp viscosity, type of mineral selectivity being sodght and degree of mineral liberation. The paper discusses when wash water should be used and the positioning of a column within the circuit as this is important to maintain a sound water balance for the circuit and prevent excessive circulating loads. Other areas of debate are pulp chemistry, very low and high weight recovery, for which the conventional column is a poor selection of equipment, and treatment of complex ores, where the separation of valuable minerals is more difficult than non-sulphide, sulphide mineral separation. Based on these observations, the application of column flotation must be carefully considered or can be optimised.

Jan 1, 1993

By Readett D. J

Soluble salts can be removed from Bowmans lignite by water and acid leaching. The success of the removal of water soluble or acid exchangeable impurities is directly associated with the efficiency of dewatering these slurries. The filtration characteristics of a slurry at its natural pH (4.0) were poor, with a filter cake moisture of 65%. Acid treatment of the slurry at pH2 caused the filter cake moisture content to drop to 61 %. Various oils, oily surfactants and a flocculant were tested to determine the conditions for minimum filter cake moisture. A series of pilot scale filtration tests were conducted on flocculant dosed slurries with and without washing on a horizontal test unit. Moisture contents of 54% were obtained in laboratory testing using high additions of oily surfactant. For the pilot scale test work, moisture levels close to 60% were obtained with low flocculant additions, similar to results obtained in laboratory studies. Removal of soluble salts could be correlated directly to the final moisture content of the filter cake. This process of leaching followed by filtration resulted in the removal of approximately 75% (more than 80% with washing on the cloth) of the sodium chloride originally present in the lignite.

Jan 1, 1989

A modular computer-based monitoring system for mines is dis-cussed. The system consists of the following modules : production moni-toring system HADES, methane monitoring system CMC, seismoacoustic and seismometric systems SAK and SYLOK, communication systems. The system enables one to compose flexible,` economic structures according to the specification of a mine. Application of microcomputer-based monitoring and control systems in coal preparation plants also is discussed.

Jan 1, 1985

By Wilson A. F

The use of stable isotopic measurements as a technique for elucidating the origin and history of the water in hydrothermal fluids is relatively new. Recent studies have emphasized the importance of meteoric water in the formation of many hydrothermal ore deposits including many epithermal gold-base metal deposits which occur in faulted volcanic terrane. Other vein-type gold ores are be- lieved to have formed from fluids of magmatic or metamorphic origin and exhibit characteri stic 6180 values. These values also give information regarding temperatures and the degree of equilibrium. Preliminary oxygen data for some important gold deposits of eastern Australia are evaluated in the con- text of styles of mineralization.

Jan 1, 1980

New Zealand contract mining has been well established for close to 50 years. The opencast industry has grown from mining quantities of less than 1 million bcm per year in the 1950s to around 20 million bcm in the late 1990s. Trends here are following those in other countries with mining companies looking to contract out more of the so called traditional mining work. The key driver behind this trend is not unique to the mining industry, but is simply a matter of concentrating on doing a few things well. In the case of the mining company this has come to mean owning and developing orebodies and where appropriate, marketing mining products, and leaving owning and operating of mining fleets to the contractor. This has the effect of reducing risk to the mining company as well as lowering costs. Both can be achieved without losing control of the key elements of the operation. Optimising performance is simply a matter of identifying the key drivers behind performance, having the right plant and the right people at the right place and providing these people with the information they need to manage the operation.

Jan 1, 1997

By Grobler H. P, Chitombo G. R

Production blasting of Dc Beers Consolidated Mines Limited, Koffiefontein and Finsch Mines involves both uphole trough rings of 9 to I I holes and near vertical 360 degree compound rings of 42-54 holes. The rate of production from these stages is dependent upon being able to achieve a specified fragmentation size range and this has driven the derivation of blasting practices to consistently achieve this target fragmentation. At the Dutoitspan Mine, in Kimberley, where mining of the kimberlite pipe is by block caving, 100 per cent extraction of the undercut level by ring blasting is essential. If this is not achieved, pillars are formed which not only inhibit the efficient initiation of the caving process, but also concentrates load onto the extraction level, causing damage to draw points and pillars. These two case studies demonstrate the importance of achieving optimum blasting performance for downstream mining efficiency; ie fragmentation for increased productivity at Koffiefontein Mine and 100 per cent undercut extraction for efficient initiation of the caving process at the Dutoitspan Mine. The case studies also serve to highlight the long road towards blast optimisation taken by De Beers Consolidated Mines Ltd (Koffiefontein. Finsch, Premier and Kimberley Mines) since 1989.

Jan 1, 1995

Comminution Kinetics equations are developed to take into account difference of grindability of mineral components. The equations describing both batch and closed circuit grinding or crushing processes are given. These equations are applied to industrial data to derive comminution kinetic and classification characteristics of the component minerals in a multi-mineral ore. Control strategy based on these concepts is presented.

Jan 1, 1985

By Y Peng, D Liu, S Vink, B Wang

There have been strong industrial observations that clay minerals have a deleterious effect on mineral flotation grade and recovery. However, rigorous explanation on the role of clay minerals in flotation and effective ways to reduce their negative effects are not available. In this study, the flotation behaviour of low quality and high quality coal samples were examined at the Xstrata Oaky Creek Coal plant, and laboratory in fresh and recycled water with high ionic strength. Anionic and non-ionic dispersants including lignosulfonates and triblock copolymers were also tested with an objective of improving coal flotation in recycled water. It was found that overly stable froth was produced in the flotation of both low quality and high quality coal samples in saline water. Speciation modelling indicated precipitation of hydrophilic components which may adversely affect the flotation. Despite the overly stable froth, saline water produced much higher combustible recovery than fresh water without significantly losing the product quality. Lignosulfonate dispersants displayed a potential to improve the flotation in fresh water, but not in saline water. Significant flotation improvement was achieved with the triblock copolymer examined in both fresh and saline water.CITATION:Liu, D, Wang, B, Peng, Y and Vink, S, 2012. Determining the effect of clay minerals on coal flotation using saline water, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 151-158 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Hayward N, Sutherland D, Wilkie G

A pilot plant study has been made of the liberation characteristics of a nickel ore under different milling conditions. A series of runs were made ranging from fully autogenous grinding to semi-autogenous grinding with a ball load of 8%. The mill products were sized and assayed then analysed by QEM4SEM. This enabled a full liberation analysis to be carried out to see whether the autogenous grinding leads to improved liberation by promoting selective breakage. Though it is frequently claimed that fully autogenous grinding yields superior liberation this could not be detected in the present study.

Jan 1, 1991

By Korsch RJ

Permian oroclines in eastern Australia must have formed by sliding on a detachment surface. It is identified as a westward- dipping Devonian and Carboniferous sub- duction zone. Major strike-slip faults probably sole out on the same surface. One major fault with an associated serpentinite belt was pulled away from the craton abd bent into loops. Basins formed in the loops.

Jan 1, 1987