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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 Daxian Z, Youdi Z, Shucai Y

The Huolinhe surface mine is a very large-scale surface coal mine, located in the north-east area of China with a production rate of 1.2 Mtpa. Its coal haulage system has a large capacity, long transportation line and high degree of automation. The system comprises two crushing plants, many belt conveyors, four surge bunkers, one loading bunker, one coal storage and five end product bunkers. In this paper, the network patterns of semi-continuous systems in surface mines are studied, the reliability calculation methods and a simulation model are established and the software for computing the reliability of a semi-continuous system is worked out. By considering the whole coal haulage system in the Huolinhe surface mine, the authors developed the system reliability-numerical simulation method. The steps and the computing results of this method are described in detail. Through the calculation, we can master the present situation of system reliability and the main factors impairing system reliability, expose the system weak links, put forward the ways of enhancing system reliability and furnish the basis for improving the system and equipment. The way of increasing capacity and methods of enhancing system reliability are further raised.

Jan 1, 1995

The Lennard Shelf is an Upper Devonian carbonate reef complex striking northwest for 350 km along the northeast margin of the Canning Basin. Numerous small Mississippi Valley type (MVT) Pb-Zn prospects occur within this belt, including the Wagon Pass prospect, located 105 km east of Derby in the Napier Range. At Wagon Pass, the base of the Upper Devonian sequence is a cobbly, dolomitic sandstone, the Van Emmerick Conglomerate. This is conformably overlain by the Frasnian to Famennian Pillara cycle Lower Napier Formation fore-reef deposits. These are characterized by red algal wackestones and terrigenous stylo- bedded packstones, with common dolomitization. The conformably overlying Famennian Nullara cycle contains a classic reefal assemblage, consisting of flat lying Nullara Limestone back-reef, fore-stepping massive Windjana Reef, and steep basinward dipping Upper Napier Formation marginal slope. The Nullara cycle is not dolomitized. The Wagon Pass mineralization is hosted by Lower Napier Formation dolomite. Mineral- ization consists of complex intergrowths and semi-massive assemblages of sphalerite and galena, with subordinate pyrite, marcasite, chalcopyrite, bornite, digenite, covellite and bravoite. Ore textures include granular and colloform. Gangue minerals are dolomite and very fine grained green chloritic clay. Although mineralization commonly occurs as reticulate fracture fillings, its overall distribution is stratabound. Ore paragenesis involved early "diagenetic" dolomitization, followed by breccia formation with chloritic and granular dolomite matrices. Main stage galena-sphalerite mineralization then occurred, accompanied by pervasive chloritization of silty units. Ore genesis was probably related to basin-derived "oil field" brines, with open space textures in the mineralization quite comparable to textures seen in Canning Basin dolomitic hydrocarbon reservoirs. Fluid inclusions in the host dolomite have typical MVT homogenization temperatures of 70-1150 C, and contain minor organic phases. The Van Emmerick Conglomerate, with its high porosity, dolomitization and weak Pb-Zn anomalism, was probably the aquifer for the mineralizing brines. Access of ore solutions to the Wagon

Jan 1, 1986

According to our experimental results, the following oxygen probe recommended, that is, the magnesia stabilized zirconia was employed as a solid electrolyte and Fe.FexO solid elect- rode was used as a reference electrode. Using such an oxygen probe, we tried to measure the oxygen potentials in molten metals, mattes and gases in the following fields of non-ferrous metal industry, molten copper in the side launder before casting, molten crude lead in the forehearth of ISP blast furnace, molten copper mattes in the forehearth of blast furnace and in the settler of flash smelting furnace, gas in the settler of copper flash smelting furnace and flue gas in the electric furnace for ferro-silicon. In the past ten years or so, many experi- mental results in the field of fundamental studies have confirmed that the equilibrium oxygen potential could be measured conveniently and accurately by an electrochemical method using a zirconia solid electrolyte. Recently, such an electrochemical technique has been also applied to a device for physicochemical invest- igation or process control in the non-ferrous metal industry. Such a device consists of an oxygen con- centration cell with stabilized zirconia, and it is commonly called an "oxygen probe" or "oxygen sensor".

Jan 1, 1980

By Walter GW

Rock mass classification systems for stable excavation design have been studied. The parameters which are important in such a classification system and those which should be included in a classification system formulated to predict explosive fragmentation behaviour are briefly reviewed and compared. There is significant overlap in the data requirements for excavation design and explosive blast de- sign. Recently there has been a trend to ob- tain some of the data required for excavation design by the use of both field and laboratory seismic investigations. The theory of seismic techniques is summarised and the results of seismic investigations carried out for excava- tion design are reviewed. On this basis it is considered that seismic techniques have the potential to be used for data collection prior to blast design. A programme designed to de- velop such techniques and which includes both field and laboratory experimentation is Presented.

Jan 1, 1978

By Gray J, Krouse HR, Changkakoti A, Morton RD

A group of stratabound-stratiform Fe-Ba-Zn-Pb-Ag deposits within the La Minita mining district of Michoacan, southwest Mexico have been investigated. The results of the study show that these deposits were generated around submarine hot-springs issuing in a Cretaceous island-arc environment. The exhalative mineralization, which is both epigenetic and syngenetic in character, was developed above fault-systems which constituted the loci of both volcanism and subsequent hydrothermal systems.Fluid inclusion data suggest two hydrothermal events during ore mineralization, one at 240¦C and the other at 161 to 205¦C, with salinities between 2.1 and 12.8 wt.% NaCl equivalent. Stable isotope data support a marine origin for the ore-fluids, as well as, for carbon and sulfur. Strontium isotope data suggest that Sr in the barites was extracted from the volcanics and limestones by circulating seawater. The ore-depositional environment was one of shallow, sub-tropical marine character, where mineralization was in part geochemically controlled by carbonate reefal facies within the volcanic/pyroclastic suite.

Jan 1, 1990

By Evans R, McCallum P

Modem blast initiation systems allow users many options for connection and application in the field, and have resulted in more innovative and complex uses of sequencing to influence blast outcomes. However, no tool existed which allowed the blaster to easily and quickly assess the effect of different options. The original requirement was for a computer program which allowed the easy input of blast patterns and the associated initiation sequence, and then permitted the evaluation of different options with respect to established criteria such as the number of holes per delay and angle of initiation. The implementation of this goal saw the development of the SHOTPIan blast sequence design software, with particular emphasis on an easy-to-use menu driven interface and visualisation of the blast sequence. Extensive trialling during development saw the incorporation of additional features requested by industry such as the ability to import from established mine design software packages, and further features such as the calculation of burden relief times. Case studies of the use of the program are provided, where the rapid evaluation of a number of options has enabled blast results to be optimised. Examples are also given of cases involving two-path initiation

Jan 1, 1995

This paper addresses the area of utilising automatic data capture systems in the metalliferous mining environment for the purpose of tracking personnel and vehicles, for both safety and productivity purposes.As automatic data capture systems in the form of barcodes have revolutionised the stock control procedures in retail establishments in recent years, so too will similar systems in the form of radio frequency identification products (an electronic version of the barcode) transform the way in which many aspects of mining operations will be managed.

Jan 1, 1992

By Hall S. F, Quast K. B Newell R, Ketteridge I. B

For the past six years research funded by the State Energy Research Advisory Commit- tee of South Australia has been conducted at the South Australian Institute of Technology, School of Mining and Metallurgy on South Australian lignites. A major part of this work has been a study of the potential bene- fication of Bowmans lignite using hydrometal- lurgical techniques. The Bowmans lignite de- posit is the largest of its type in South Australia and is a major energy reserve for the state. The utilization potential of this deposit is reduced by its very high insitu NaCl content which presents serious problems for any process. Previous research conducted by Readett and co-workers (1984a & b) has shown that NaCl is amenable to extraction using simple batch water leaching operations. This leaching has been successfully described using a two stage diffusion model derived from first principles based on a simple diaphragm cell.

Jan 1, 1987

By Pollard D, Meadows N

The presence of impurities which are electropositive to zinc in acid zinc electrolyte causes changes to deposit morphology and reduced current efficiency. Glue may be added to control some impurity effects, but assaying for animal glue concentration is difficult and seldom done. Measurement of the activation overpotential for zinc deposition by cyclic voltammetry is used in some plants to monitor electrolyte quality and control glue additions.The deposit morphology and current efficiency of zinc deposition from commercial electrolyte were investigated for various glue additions in the presence of increased levels of antimony. Cyclic voltammetry was investigated as a method of optimising glue additions in the presence of antimony.Scanning electron rnicroscopy showed deposits characteristic of the impurity element present and the glue addition rate. Cyclic voltarnmetry measurements showed some correlation between current efficiency and activation polarisation potential. The importance of using tankhouse electrolytes where results are to be related to tankhouse operation was noted.

Jan 1, 1988

By Mandzic E. H

The Dome Mine of Timmins Mining company is located in South Porcupine, N.W. Ontario. The orebody being mined partially lies in the No. 3 shaft pillar. Stability analysis has been carried out to establish the influence of nearby mining on ground movement in the shaft vicinity. Mathematical modelling of shaft displacement has been done for stope layout at depths from 180-210 m and distances of 10-50 m from the shaft. Analysis indicated that ground displacement around the shaft is below 1 mm/m and one third less for cut and fill than in the case of open stope mining. The result of the investigation was later confirmed by cut and fill mining of this orebody.

Jan 1, 1986

By Virtanen M

Grinding has been one of the areas of major development at Outokumpu's concentrators. During its early years the company used entirely rod and hall mills, but due to the high costs of metallic grinding it began the testing of autogenous grinding as early as the 1950s. In the late-1970s, the company's own modification for two stage autogenous grinding was ready for industrial use. Surprisingly late, in the 80s - 90s, an interest rose to check also the effects of grinding methods on flotation results. This paper firstly gives a short history of the development work of Outokumpu type autogenous grinding, called 'Outogenius'. The effects of some grinding methods on the process results of two nickel ores are then reviewed. The tests to date show notable effects of grinding methods on flotation.

Jan 1, 1996

This paper presents a method for estimating the strength and stability of model coal pillars with bedding planes (weakness planes) inclination. The strength of coal relative to the angular difference between the principal stress direction and bedding planes is considered. The failure behaviour of model coal pillars containing weakness plane inclination by using servo-control Schenck Machine are shown. Uniaxial and triaxial compressive strength of coal specimens are investigated, and test results indicated that the strength of coal pillars depends on the weakness planes inclination with respect to the principal stress direction. However, it is shown that with increasing confining pressure, the effect of weakness planes inclination on the strength of the coal specimens is reduced. An empirical method is given for prediction the compressive strength of coal containing weakness planes inclination. The results of this method are compared with the experimental results and Jaeger theory. Finally, three well-known empirical strength criteria were tested against the triaxial test data for coal containing weakness planes inclination.

Jan 1, 1995

By Blair J. R

A Train Performance Calculator (TPC) is an essential tool in railway operations, as a means of acquiring quickly a precise measure of the performance of the system. Traditionally the TPC was used in the form of program for a large computer. By employing an efficient integration algorithm and tailoring the program to suit the computer system it is shown that it is possible to devise a TPC for a mini computer. The resulting low running costs and flexibility of operation makes this a useful design tool. This TPC was developed to study problems associated with a single track railway operation. It was applied specifically to study the railway operated by the Mt. Newman Mining Co. Limited in the Pilbara region of W.A. to transport iron ore from the mine to the port. The TPC was used to calculate the effects of changes to locomotive power, to train size, to the track and to the amount of traffic. Its accuracy was checked by comparing its performance with that of the actual trains.

Jan 1, 1977

Using normal low pressure filtration methods for the dewatering of fine china clays, the best that can be achieved is cakes with about 30% moisture. In order to get the moisture levels down to acceptable levels the traditional method used is thermal drying, which is both costly and dust creating. It was to improve this process that ECC International embarked upon a programme of development of filtration equipment using high pressure to achieve significantly lower moisture levels. This development work investigated several design philosophies and culminated in the production of two quite different solutions. The High Pressure Plate Press uses round plates / chambers of one metre diameter and a filtration pressure of 70 bar. This press is fully automatic and produces a surface dry cake that has sufficient plasticity for the further processing that is required on specific qualities of china clay. The TUBE PRESS on the other hand uses a unique design configuration and operates at a filtration pressure of 100 or 140 bar, depending upon the model. The TUBE PRESS produces a brittle, surface dry cake that is easy to handle and a filtrate that is usually crystal clear. The TUBE PRESS achieves a much higher degree of separation than is possible with conventional equipment, which is particularly important if the filtrate is the product. Over the past 15 years plants incorporating both HP Plate Presses and TUBE PRESSES have been installed in the china clay operations of ECC International and are giving excellent trouble free service. The TUBE PRESS has also proved to be extremely versatile, effectively dewatering a wide range of fine particled slurries, in a number of diverse industries.

Jan 1, 1989

Sampling criteria and practical implementation of these criteria are discussed with a view of achieving and maintaining a high level of quality for minerals at their various stages of production through to their utilisation. From this it will be shown the advantages that can be gained by producers who undertake stringent quality control programmes for their ores, thus ensuring they have a competitive edge over other producers.

Jan 1, 1985

By McPherson M. J

This paper describes a major ventilation study for the expansion of the El Teniente mine operated by Codelco, Chile. El Teniente is one of the world's largest under- ground mines. The design effort was under- taken in three stages and involved a partial mine ventilation survey with network simula- tion, detailed stope ventilation investiga- tions, and design of the entire mine ventila- tion circuit based on production plans to achieve 112,000 tons per day by 1995. The partial ventilation survey provided values of representative friction factors and resistances for typical ventilation raises and airways. These values were used to conduct detailed modeling of the block caving levels to investigate the most cost effective and practical means of providing the required ventilation. The results of these analyses were extrapolated to the proposed expanded mechanized zones.

Jan 1, 1988

By Goldstone A

The paper introduces a newly developed multi-function test rig for fracture grouting. This test rig has many functions and its performance is consistent. It can control and adjust accurately the opening degree of fissures and static pres- sure; it can measure automatically the quantity of grout injected; it can measure precisely pressure drop of grout in fissures; it can test the results of injection, including effective dispersed distance, anti-filtration capacity of consolidated body, mechanical strength, etc. It can inject a single or two grouts into one or several fissures at a pressure of 16 MPa. Therefore, it is an ideal test rig for fracture injection. The paper depicts all the components of the test rig, its performance and application of the results obtained from fracture grouting tests. Examples are briefly described.

Jan 1, 1988

By Piotto P

Pit optimisation algorithms are designed to produce a pit with maximum value, but for certain minerals like iron ore, limestone, coal, etc, it is also necessary that the designed pit contains ore which meets the customer's chemical specifications. This paper describes a technique of using linear programming for blending optimisation and the Lerchs-Grossmann algorithm (as in Whittle's 3D software) for pit optimisation in tandem, to achieve pit designs of targeted grade specifications.

Jan 1, 1996

By Fee DJ

Some four hundred million tonnes of low rank sub-bituminous coal occurs in four separ rate lobes at Leigh Creek. These deposits are in a sparsely populated pastoral area remote from industrial centres. Early development was retarded because of high mining and haul- age costs and the availability of other fuels. The search for additional fuels after the second world war led to thorough investigations into the burning characte-,istics of the coal and the discovery of shallow coal suitable for open out mining. The development of the field included the establishment of water supply, improved rail facilities and a town.

Jan 1, 1975