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By Chenggang W, Junhua D

Fragmentation variation laws in loading and non-loading areas are obtained by cement block model blasting experiments under various stemming lengths. A reasonable ratio between loading length and stemming length is worked out according to minimum average fragment size. The present continuous loading structure, for its very long length to be stemmed, leads to insufficient fragmentation in the upper part of bench. So a new loading structure with bottom air cushion is put forward. The author analyzes blasting effects and processes of two loading structures' and proves that there exists a optimal length of air cushion.\

Jan 1, 1990

During the drilling campaign conducted between October, 1942; and May, 1943, to prove the extent of the scheelite deposit worked by King Island Scheelite N.L. at Grassy, King Island, Tasmania, 35 holes were drilled and 606 samples recovered and assayed for their content. Of these, 238 came from outside the limits of the orebody and were for the most part barren, although a few contained some scheelite. The present statistical analysis is made only of the 368 samples taken from diamond-drill cores of the orebody itself.Drilling Pattern and Sampling MethodsFrom the purely statistical viewpoint, it is realised that methods employed in selecting sites for diamong.-drilling, and of collecting samples from drill cores, do not give a completely unbiassed set of data for analysis. Fig. 1 is a sketch plan showing the relativepositions of the drillholes, which were inclined at an angle of depression of 50 deg. The pattern does not conform to a properly randomized and' regularly-spaced grid, the positions of the later holes being determined by the results obtained from previous holes.Statistically, the bias is, therefore, favourable. The unequal spacing of the drill holes and the lack of uniformity in direction of the lines along which the holes were drilled are unsatisfactory from the mathematical viewpoint; but it is realised that these irregularitiesare difficult to avoid in determining by the most economical methods the extent of such an orebody, and are dictated by geological rather than mathematical necessity.Sampling, also, is lacking in complete uniformity. Each sample is approximately 10ft. in length. However, owing to the fact that 100% recovery of core is rarely achieved, and actual lengths of samples taken are ,primarily governed by the length of the drill runs,and secondarily by lithological changes, there is a considerable amount of variation in the sample length.AssayingWith the exception of 28 samples from three drill holes all samples dealt with in this paper were assayed in the Melbourne University Ore-Dressing Laboratory of the Commonwealth Scientific and Industrial Research Organisation. These assays were given to the nearest 0.05% WOg as it was considered that more accurate determination was not possible. This fact has been taken into consideration in the frequency analysis below. The 28 assays determined by the Tasmanian Mines Department were given to the nearest 0.01%.

Jan 1, 1950

By R Ayothiraman

Tunnel excavation may induce adverse effects on nearby existing structures/foundations in urban areas. Accurate prediction of tunnelling effects on pile foundations of nearby structures in the urban environment poses a major challenge during design. Several studies have been undertaken to understand the mechanisms of the soil-tunnel-pile interaction, which focused only on influence of tunnelling on nearby existing building and foundations. However, effect of pile loading on existing tunnels did not receive enough research attention so far. So it is essential to measure the response of existing tunnel-lining due to loading on newly constructed pile to assess to the safety against the additional forces/moment caused by pile loading and to evaluate the critical distance for the proposed construction of any structures from the tunnel location. This paper presents result of three-dimensional (3D) finite element analysis carried out in ABAQUS to investigate the effects of pile loading on existing tunnels embedded in cohesive soil. It is found that the effects on tunnel lining depend on horizontal separation distance between pile and tunnel as well as location/elevation of pile tip with respect to tunnel location.

Mar 8, 2011

Parallel lenticular orebodies occurring at the C.S.A. mine of Cobar Mines Pty. Ltd. are mined by mechanized cut and fill stoping over the full strike length. Access is provided for each stope lift from an inclined drive adjacent to the orebody. Mobile drill jumbos mounting hydraulically-operated booms are used for drilling upholes which are subsequently charged with ANFO explosive.Close control of drilling has been found essential for good back conditions and to ensure optimum fragmentation.Broken ore is transported from the face to the main ore pass by rubber-tyred, diesel-powered, load-haul-dump units. Initially, the units trammed ore to the main pass via the incline drive. As the stopes advanced and the lead distances increased, stope passes were developed in the wall rock and raised concurrently with each stoping lift. The passes terminate in drawpoints and production loaders are used to transport ore from the drawpoints to the main ore pass system.Two parallel ore pass systems have been developed to cater for both copper and copper-zinc ores. These systems terminate above a 48 in. by 60 in. jaw crusher. The crushed ore is conveyed to a traversing rock box and thence to one of two crushed ore bins adjacent to the main hoisting shaft. A loading station conveyor is interlocked with the winder to provide automatic ore hoisting.All phases of ore handling have been mechanized as completely as possible. Results to date indicate this policy has been vindicated but highlight the need for tight operating control and close liaison between operating and maintenance personnel.

Jan 1, 1969

The kinetics of chlorination of alumina and bauxite with CO/CI2 mixtures were studied in the range 300-1100°C. The temperature of prior calcination is critical in determining the reaction rates. An optimum chlorination temperature in the range 600°C-750°C was demonstrated such that there is no increase in reaction rates with increasing temperature. This lack of rate sensitivity to rising temperature is largely a function of the influence of gaseous diffusion gradients in the porous alumina together with a progressive decrease in surface area.

Jan 1, 1976

By Harris RW, Wood BR

At any given time, the tidal force subjects massive regions to a spatially uniform load. The deformation of any large structure due to these forces is proportional to the elastic properties of the structure. In this aspect, the tidal force applies a load in a manner similar to that of a large-scale testing machine. Any anomalies in the measured tidal response must reflect alterations in the average elastic response of the massive structure. In the present work, tidal tilt measurements obtained in the wall of a large dam are used to infer changes in the response of the dam to applied loads. In particular, it is found that the dam response has changed by approximately 13 percent, on average, for two monitoring periods separated by 5 years. It is possible that these changes were produced by the different volumes of water in the dam for the monitoring periods. The tidal measurement technique can also be applied to monitor changes In the average structural response of large underground and surface masses relevant to coal and metal mines.

Jan 1, 1992

By Restarick CJ

Plant data are presented which indicate a relationship between flotation rate constants and pulp density in zinc cleaning circuits at Broken Hill. The data were obtained from down the bank sampling of cleaner and recleaner banks at North Broken Hill and New Broken Hill Consolidated Concentrators. It was found that, under normal plant operation, flotation rate constants increased at the lower pulp densities existing in the later cells of cleaner banks. The addition of dilution water to the feed to the bank increased flotation rate constants, thereby confirming the relationship. It is shown that the relationship between flotation rate constant and pulp density is size dependent, being most pronounced for larger sized particles. In contrast, the effect is not markedly dependent upon mineral type. Possible consequences of this relationship for control of cleaner operation are discussed with the aid of some simulated results.

Jan 1, 1978

By Turner T. M

The problem of metering fine particulate material at low flowrate is often encountered in metallurgical experiment. This note describes a feeder which wa developed to provide metered flows of copper sulphide concentrate in the range of 0'1-0'7 g/min.It is believed that the present device is easier to operate than previously described feeders (e.g. Hamor and Smith, 1971). It may have applications in the field of analytical chemistry, as well as in metallurgical investigations.

Jan 1, 1978

By J Mercuri, S Dunford, P Rothman, E Bartsch, J Snyder, D Newton, R Maron, D Cirulis

The purpose of a mineral comminution circuit with a ball mill running in closed-loop with a hydrocyclone classification cluster is to feed the downstream process with the target particle size. Maintaining the optimal particle size in the flotation feed can significantly improve plant cash flow. In particular, reducing the amount of coarse material is often a major challenge. Existing instrumentation to provide particle size measurement is considered standard equipment in most modern concentrator plants. However, availability is often very low, mainly owing to high maintenance requirements of the analyser and associated sampling system.CiDRA Minerals Processing has developed two novel and robust technologies that address this challenge by providing high reliability and very low maintenance systems for on-line measurement of coarse material in the overflow of individual hydrocyclones. The first system is non-invasive and measures pebbles and rocks greater than 6 mm. This paper focuses on the second system, which is a ruggedized wetted sensor design with no moving parts and provides a real-time trend of the desired target grind size parameter, such as percentage above 150 micron.Both systems have simple robust designs and measure in the primary overflow stream of the individual hydrocyclone. Individual hydrocyclone measurement enables identification of poor performing hydrocyclones in addition to providing a representative measurement of the whole hydrocyclone cluster. The systems do not require sampling and associated sample transfer piping circuits that are prone to plugging, thus avoiding high maintenance requirements.The wetted sensor will be described in detail along with its implementation in a robust control scheme in a major copper concentrator in North America. Plant data shows very high availability, achieved with very low maintenance, has enabled improved process control, thereby maintaining throughput and ball mill target power while reducing grind size.CITATION:Cirulis, D, Dunford, S, Snyder, J, Bartsch, E, Rothman, P, Maron, R, Newton, D, O’Keefe, C and Mercuri, J, 2015. Process optimisation using real-time tracking of coarse material in individual cyclone overflow streams, in Proceedings MetPlant 2015, pp 93–109 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 7, 2015

By Lauha E. A

The Goldstrike Mine is in Eureka County, Nevada, U.S.A., approximately 23 miles northwest of the town of Carlin. The mine is at the north end of the Tuscarora Spur of the Tuscarora Mountains at elevations of 5,300 feet to 5,950 feet. It is part of the Bluestar/Goldstrike subdistrict of the Carlin Trend, a northwest alignment of sediment hosted, disseminated gold deposits. The Carlin Trend includes over 15 major gold deposits with production, reserves and geological resources of approximately 65 million ounces of gold (Figure 1). In the Bluestar/Goldstrike subdistrict, there are seven major deposits; Betze, Lower Post, Post, Genesis, Bluestar, Purple Vein and Deep Star, plus numerous smaller deposits (Figure 2). Production, reserves and resources for the subdistrict are approximately 40 million ounces. Betze and Purple Vein are located on property controlled by Bamck Goldstrike Mines and Bluestar and Genesis on Newmont Gold property. Post, Lower Post, and Deep Star occur both on Barrick and Newmont Property.

Jan 1, 1991

In the minerals industry allocating capital for setting up a new project or for upgrading an existing facility usually requires that a compromise be found between the initial cost of equipment, its operating performance and on-going operating costs. To maximise the return on the investment usually requires that various possible combinations and layouts of equipment be assessed. This task is both difficult and time consuming. Computer simulation can be used as a means of determining the expected operating performance of a range of alternate equipment configurations. Simulation is a particularly important technique for analysis as it is one of the few approaches that allows the analyst to take into account the variability inherent in a mining process. While computer simulation is a well established technique its use, until recent years, has been limited to large organisations with access to substantial computing facilities. However, with the current availability of low cost computing platforms combined with easily understood animated displays, simulation is now becoming more widely used across the industry.

Jan 1, 1990

G. R. Compton (Gold Mines of Kalgoorlie (Australia) Ltd., Fimiston, W. A.) : In congratulating Mr. Hooker upon his resume of Mr Parry's paper I have in mind the fact that he carried out the research into pipe pressures. Hydraulic filling as practised in Kalgoorlie has created world wide interest, with these pressures and percolation being vital points.Early in the 1950s, representatives of the Kolar field were conduGted over the local mines where stopes at depths below 2,000 ft were being filled. The problems of pipe pressures were their main consideration since depths of up to 10,000 ft were envisaged.Mr Krishnaiah and Mr Murthy from the same field are with us today and perhaps we may hear of their experiences with depths of 6,000 ft and long lateral lines.J. Holly (Lake View and Star Ltd., Fimiston, W.A.): There is one phase, which I would like to mention myself, that has been very evident in Kalgoorlie operations. That is, we do not get the percolation properties that are obtained on many other fields in the world, and our tendency here has been to assess the quality of our fill more by its settling rate, i.e. the rate at which we can draw off clear water at the surface of the filling levels, rather than the rate that this water percolates down through the fill before it consolidates.We are tending now to measure the quality of our fill as a settling rate rather than as a percolation rate.Americans talk about percolation rates being the important property: If anyone has any experience on operating with fills with different percolation rates, I think their views would be very interesting to the meeting art this stage. Mr ...

Jan 1, 1965

The mobility of radionuclides released into aquatic, terrestrial and subsurface environments by mining, industrial processes is an area that deserves significant scientific attention. The presence of microorganisms in these environments can influence the transport of radionuclides. Free-living microorganisms constitute mobile suspended particles that may have a radionuclide sorbing capacity higher than that of the environment. Radionuclide transport will then proceed faster with than without microorganisms. In contrast, if the majority of the microorganisms are growing in biofilms on surfaces, transport of radionuclides may be reduced. Microorganisms can directly sorb radionuclides either within the cell structure or on the cell wall. Radionuclides could also be sorbed by minerals precipitated by microorganisms. Microorganisms produce complexing agents that can influence radionuclide mobility. The involvement of microorganisms in biogeochemical processes is related to their ability to include various chemical elements and their combinations into biochemical redox reactions. Microorganisms can alter the extent of radionuclide oxidation that results in their deposition as a result of the formation of insoluble forms. Some studies have shown the bioremediative potential of stimulating reducing bacteria to use some of the soluble radionuclides as electron acceptors and thus precipitate them out of solution. The microbial involvement in providing a barrier for radioactive element migration (uranium, technetium) and the formation of ores (eg uranium) has been justified. The mediated impact of microbial activity on radionuclide migration occurs through its effect on the ambient geochemistry by geochemical speciation changes, pH changes and changes to the ambient redox potential. As the mobility of many radionuclides depends on the pH and redox potential of the environment, these microbially mediated geochemical changes can influence radionuclide migration through changes to both the dominant radionuclide species and mineral phases.

Jan 1, 2004

By Morrison RD, Simmons CJ

A bewildering array of process control instrumentation is currently available for mineral processing plants. For sequencing control, special purpose microprocessors or the process control computer can be used. Where continuous control is required, then the choice is between pneumatic controllers, electronic controllers, shared display micro- processor systems and direct digital control. The benefits of each system are discussed and the advantages of using direct digital control in mineral processing plants are outlined. The factors which need to be considered when selecting control systems for new plants are listed. Instrumentation systems designed by Fluor Australia are used as case studies to illustrate the selection process. For established plants, conversion to direct digital can be advantageous, and case studies are given. However, replacement of existing systems requires justification based on a productivity improvement which will allow the control equipment to be paid for within a specific time period. Productivity improve- ments maybe assessed in terms of increased

Jan 1, 1978

Taking the third meridian as the eastern boundary of proved payable auriferous country, there is a stretch of country, nearly 600 miles in width, in which no appreciable amount of gold has yet been discovered. Many prospectors have attempted to .penetrate or traverse it, but comparatively few have thought it worth while proceeding with the examination.The desolate stretch of waterless desert-the very few and insignificant outcrops through the sand and the almost total absence of feed for horses have, combined, presented such a barrier as to preclude prospecting. The few who have traversed the country are eloquent in denunciation, yet their investigations, necessarily hurried, are not quite satisfactory. The absence of water utterly debars a thorough examination being made. Gold may exist in quantity, yet it would have to be extraordinarily plentiful to render its obtaining profitable. Too fantastic is the idea of its ever being a mining district; shifting sand to traverse, utter absence of wood and water render the notion absurd. Likely looking belts occur, but these in all "cases are small and remote from water. Gold has been obtained from likely look ing quartz reefs, but only by fire assay, and then but a few do to the ton. Without wishing to be pessimistic, I would unhesitatingly declare that east of the third meridian, and between the parallels 25 and 30 degrees in West Australia, there is no gold in payable quantities.

Jan 1, 1901

The paper outlines the history and current status of the VALMIN Code and sets out the background, methodology, results and recommendations of the Independent Review of the VALMIN Code undertaken during 2001 under the Chairmanship of Ian Goddard. The paper is based on the final report of the Taskforce, which was submitted to the Board of The AusIMM for consideration.

Jan 1, 2002

The high cost of sampling systems is largely due to the fact that indiv- idual mechanical type sampling units must be installed at the discharge end of ore/pulp pipelines, that is, at points where the pipeline discharges into pump sumps or the like. A considerable economic advantage may be obtained in the use of a samp- ling device that can be installed at any point in the path of the trans- porting pipe line. Initial tests on a vertical line with an injection sampler using iron ore concentrates reveal the validity of this type sample versus that taken with a mechanical sampler. A descrip- tion of the injection sampler shows its simplicity of installation, requir- ing minimum downtime on existing lines.

Jan 1, 1976

Kumba Iron OreÆs Sishen Mine is one of the worldÆs largest iron ore mining operations situated in the Northern Cape, South Africa. It produces 29 million tonnes of iron ore products per annum using a dense medium separation (DMS) beneficiation process. Kumba is currently commissioning the Sishen Expansion Project (SEP) which will produce a further 13 Mtpa product through a jigging beneficiation process. The products from the Sishen Mine are highly sought after and consumed by domestic and various European and Asian customers. During beneficiation iron ore slimes are generated and discarded as waste material to the slimes dams. A study was initiated in 2005 to investigate processes to beneficiate these slimes to saleable products û prompted by the current high demand for iron ore products and the high grade in the Sishen slimes thickener underflow of approximately 54 per cent Fe. Initial laboratory scale test work indicated that a 66.5 per cent Fe iron ore concentrate could be produced from the Sishen slimes thickener underflow through a process of classification, two stage wet high intensity magnetic separation (WHIMS) and five stage flotation. This process, however, did not produce the desired results during pilot plant testing and numerous alternative process routes were investigated. The process that did achieve the desired product grade of 66.5 per cent Fe at economically feasible product yields consisted of two stage WHIMS using SLON magnetic separators. Results achieved indicate that the thickener underflow slimes can be upgraded from 54 per cent Fe to 66.5 per cent Fe at a product yield of ca. 40 per cent. Product yield could be increased through the further beneficiation of the SLON tails. The Sishen slimes thickener underflow production rate is ca. 3 Mtpa û resulting in a potential concentrate production of ca. 1.2 Mtpa. The slimes concentrate will be fed to a pelletising plant that will produce 66 per cent Fe pellets destined for domestic and or export markets.

Jan 1, 2008

A general approach to the analysis of processing technology is presented using the concepts of Process Aims, Process Characteris- tics and Process Costs. From an examination of the processes used in extractive metallurgy a hierarchy of process aims is identified, these aims are separation, compound formation,, metal production and metal purification. The application of this methodology to process flowsheet development is described.

Jan 1, 1984

By Evans A. F

Arising out of the increasing demands for efficiency in modern ore-dressing operations has grown a requirement for fuller knowledge of the characteristics of the ore treated. In part, this is being met by improved methods of study of the mode of occurrence of the constituent minerals, and of the intricacies of their physical relationships.A typical instance of the need for such a study is the presence of some undesired mineral in a flotation concentrate or tailing, which may be due either to mechanical association through insufficient grinding, or to incomplete separation in the flotation operation.Again, with modern practice in fine grinding, which often requires that from 70% upwards of the ground ore shall pass a 200-mesh screen, it is obviously impossible to obtain data on comparative grinding efficiencies, for instance, unless there is adequate knowledge of the size-composition of the material passing the finest available screen.Studies like these can be made satisfactorily only after size-separation (which may be carried out conveniently by elutriation) and by actual visual examination with the aid of a microscope, and the minute size of the mineral grains to be examined has necessitated the development of a new technique of sizing and microscopic examination.

Jan 1, 1932