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The effects of process variables such as solution chemistry, flocculent type and dosage, intensity and duration of mixing, and solids type and concentration, on the performance of flocculation/clarification/thickening processes are described. System response is evaluated in terms of the specific effects on floc settling, supernatant clarity and sediment compressibility. The implications of these results with respect to industrial practice are discussed and general guidelines for direct application to plant design and operation are suggested.

Jan 1, 1993

By Tuckey SH, Wake BA, Ariti J

Astute exploration on the northern Minahasa Peninsula, North Sulawesi, resulted in the discovery of the Toka Tindung, Pajajaran, Blambagan and Araren low-sulphidation quartz-adularia vein and stockwork gold-silver deposits. Combined, these deposits have estimated mineral resources in excess of I Moz gold at an average grade of 2.8 gAu/t and 7 gAg/t and are known as the Toka Tindung Gold Project. Gold typically occurs as fine grained electrum and is often associated with acanthite. The structurally controlled mineralised veins are hosted by Late Pliocene plagioclase and pyroxene-phyric basaltic andesite volcaniclastics and flows which form part of the Early Miocene to Pleistocene Sulawesi-East Mindanao Arc. Silica-adularia alteration dominates the volcaniclastic host of the Toka Tindung deposit. K-Ar dating of vein adularia indicates a 2.16 ¦ 0.04 Ma mineralisation age. Relatively narrow envelopes of silicification and argillisation surround the chalcedonic silica, quartz and adularia veins, stockworks and breccias at the other three deposits. Remnant hydrothermal breccias, chalcedony and anomalous arsenic, antimony and mercury indicate these gold deposits were part of a mineralised geothermal system.As of June 1997, Aurora Gold Ltd is finalising a feasibility study on exploitation of the four deposits and treatment of ore through a centrally located conventional CIP plant. Subsea tailings disposal is anticipated. Favourable metallurgy of the ore and logistics of the project area assist in minimising capital requirements.

Jan 1, 1997

By B Siddall, A Gunstone

The use of a partial secondary crushing circuit provides a flexible way to optimise existing SAG comminution circuits limited by rock competency or enables optimal processing of an ore through second hand equipment not specifically selected for that ore. This paper details the process involved in designing a partial secondary crushing circuit using the recent installation at Mt Rawdon Gold Mine in Queensland as an example.

Jan 1, 2004

Around no subject of technical )uterest have prejudice and wrong-thinking in the past so wrapped a web of obscurity as that of the corrosion of metals.It is a matter which has primarily concerned the engineer, but the paucity of his training in chemistry and electrochemistry has been the stumbling block to a better understanding of its mechanism.Now that the more important conditions controlling corrosion have been scientifically.established, it can be seen that, with the exception of but a few of the minor points, the electrochemical laws enunciated by Faraday, Helmholtz; Nernst, and others, are sufficient to include all the facts of the process.The word corrosion (derived from the Latin rodere-to gnaw) is so often wrongly applied that a definition at this stage would be useful. As now understood, it means the dispersion and waste of the useful solid metal by conversion into a useless compound which mayor may not be retained on or near the metal remaining.Commonly the presence of these compounds is regarded as evidence of corrosion, but the converse is not necessarily true; the lack of visible corrosion products on a clean surface of metal is no criterion of the absence of this change. It may be difficult to prove that the erosion of such a surface has been caused by chemical and not by mechanical effects alone.

Jan 1, 1932

This paper outlines some of the recent developments in Spiral Concentrator design, with particular reference to the range of Reichert spirals supplied by Mineral Deposits Limited, typical applications, and test or operating data, are also provided for the different series of spirals now available.

Jan 1, 1978

By Hollis R. G, Tuppurainen J. M I

Improved control of non-ferrous sintering operations requires the on-line measurement of sinter quality. No on-line measure of sinter quality is currently available, however, previous work has shown that the raw mix chemistry and peak sintering temperature determine the mineral phases formed and hence the resulting Blast Furnace behaviour. Control of these factors should therefore lead to improved quality control. In this paper, the development of a simplified heat and mass balance model of the Sinter Plant at Mt Isa is described. The model used available plant data to calculate raw mix composition and a simplified reaction scheme to predict sinter composition. The extent of reaction is inferred from the flue gas analyses. Off-line testing of a dynamic version demonstrated that actual plant performance could be predicted with reasonable accuracy.

Jan 1, 1989

By Tilyard P. A

Recent exploration has established depos its of nickel sulphide in several areas of Western Australia. To assist in their develop- ment Amdel has investigated the beneficiation of many samples from these deposits and has estab- lished flowsheets for the recovery of nickel values by flotation. Metallurgical data are presented for the samples according to four factors which were encountered in their respective treatments.

Jan 1, 1973

By M M. Tarshan

Separator performance is evaluated by the so-called separation efficiency. The concept of efficiency in mineral dressing operations must be interpreted with considerable care. Although qualitative use of term efficiency is valid and useful, difficulties arise in expressing it quantitatively because two conflicting criteria, grade and recovery are normally involved in its evaluation. It is undesirable to express efficiency as a single value, even though this is frequently done in practice, since there are strictly speaking an infinite number of combinations of grade and recovery that can give that one value. Inefficiencies in processes can be attributed to three broad sources: mineral limitations as represented by the separability curves, equipment limitations (which prevent the maximum separation indicated by the separability curves), and human failure to minimise these inefficiencies. In the present paper, the efficiency of a two-constituent separation process has been examined. The separation process has been evaluated by comparing the sharpness factor of the actual, the absolutely efficient and the absolutely inefficient operations.

Jan 1, 2000

By Harrison J

The correct selection of equipment to use in a mine is a problem which constantly faces the mining engineer. In some cases a wide choice of equipment with different operating characteristics is available. If this equipment is to be used to assist in moving the ore it may be possible to build a computer simulation model to predict how it will perform. Typical problems that lend themselves to this type of analysis are presented. The computer models are constructed using a recent form of the GPSS computer language, namely GPSS/PC for the personal computer. This language allows the programmer to construct models in a very short time and at a low cost. Of great importance is the easy way in which it is possible to change the models to answer any of the "what if?" questions the engineer may pose.

Jan 1, 1987

Rock bolting and rock-bolting systems depend for success on attention to a number of simple techniques. Failure to appreciate this fact can lead to disappointing results. Careful study of rock characteristics and placement methods can allow a change to highly successful rock bolt per- formance. A number of examples are quoted to illustrate the sig- nificant improvement in results which can be achieved by use of the most suitable combination of characteristics.

Jan 1, 1971

By Nemcik JA, Gale W. J

The magnitude and orientation of the in situ stressfield has been determined as a key factor in controlling the stability of openings for both coal mine development and extraction. Monitoring of roadway and pillar behaviour in conjunction with numerical analysis has identified specific stress control measures that have been successfully applied to improve productivity in underground coal mining operations. The influence of the major horizontal stressfield on the stability of openings has been identified at a wide range of sites including mines in Australia, Britain, the USA, New Zealand and Japan. Stress mapping, stress measurement and stress monitoring techniques have been applied to define the in situ stress regime and, together with the correlation of measurements of rock deformation and rock reinforcement behaviour, has enabled appropriate stress control measures to be developed. Stress control measures for development headings have required the selection of roadway orientation, roadway sequencing, reinforcement density and pillar size. The monitoring of behaviour at a range of trial sites has confirmed significant improvements in development stability. Stress control measures for longwall extraction have required rational selection of longwall orientation and extraction direction. Where a mine layout design incorporating the optimum longwall layout design has not been possible, the use of sacrificial roadways has been successfully applied to protect key roadways from stress concentration effects. Comprehensive in situ

Jan 1, 1992

By Payne P, Beirne W, Geldard D, O&apos

Whim Creek Consolidated N.L. has operated openpit mines at Meekatharra since 1980. Mining operations commenced with the Haveluck openpit and the Phar Lap openpit was started in 1 984. Grade control in the Haveluck mine was simple because the orebody showed good continuity along strike and down dip and had an easily recognisable hanging wall contact. Problems were encountered once mining corn menced at Phar Lap because of the complex lithologies, alteration and faulting involved. Simple grade control techniques developed for Haveluck failed and were not solved until an understanding of the ore bodies was achieved.The integration of all geological data into the interpretation of the developmentdrilling results has proved essential to achieve effective grade control atreasonable cost.

Jan 1, 1986

By D Brennan, S Jahanshahi, F Jorgensen

The recycling of metals can be very efficient with careful selection of the material being recycled. The volume and value of recycled ferrous scrap has lead to the development of steel mini-mills which in turn has caused major changes to the steel industry. Although much smaller in volume, the recycling of lead is very significant, with battery recycling accounting for 60 per cent of annual world production. This high recycle rate can be attributed to the relatively uniform feed-stock from lead-acid batteries. The recycling rates of other metals are considerably lower due to longer use and non-uniform product usage that results in less efficient segregation and processing. It is clear that recycling of metals has advantages but its sustainability is uncertain. What are the key benefits of metal recycling? Metal recycling has technical, economic and social impacts. It is relatively easy to assess recycling on a technical basis, but the social impacts are harder to evaluate. This paper examines some of the issues in evaluating the sustainability of metal recycling.

Jan 1, 2002

By Mould G. R

The paper presents a general background to the subsidence research programme being undertaken by the Department of Mineral Resources and Development in New South Wales. The results of the studies undertaken over the last ten years are summarised. The differences between these results and those obtained by the National Coal Board are discussed. The results of a study carried out on the effect of total extraction beneath a freeway in the southern coalfields are discussed in some detail. The procedures developed for the const- ruction of a 500 mm diameter natural gas pipe- line crossing a number of collieries in the northern coalfields are also outlined. The future direction of the Department's subsidence research programme is discussed.

Jan 1, 1980

By R L. Verburg, R Johnstone

DeBeers Canada Mining Inc (DeBeers) recently submitted an Environmental Assessment (EA) for its proposed Snap Lake Diamond Mine located in Northwest Territories, Canada. As part of the EA process, a site water quality management plan must be developed. Plan development requires an integrated approach such that the key factors influencing water quality can be identified and managed to minimise potential impact. A system model was therefore developed to simulate the site-wide water quality conditions and mass loadings to the principal environmental receptor of concern, Snap Lake, during operations and post-closure. Requirements of the simulation included integrating hydrology, geochemistry, hydrogeology and site management practices in a dynamic way. A unique feature of the site was the need to accommodate a complex flow system that included a feedback loop between lake water and mine water. A system model was constructed using the GoldSim software package that integrated on-site water quality and flow measurements, as well as results from independent groundwater flow and geochemical modelling efforts. The GoldSim model simulated concurrently the movement of 39 solutes through the subsurface mine and surface facilities. Solute sources considered included four different waste rock and tailings types, explosives use in the mine, treatment plant discharge, and recycled process water for dust suppression. Separate solubility constraints were identified for different regions of the flow system (eg underground mine; treatment facility; surface water bodies). Kinetic test data were used to derive temperature-dependent rate constants for use in calculating mass inputs from surface sources such as waste rock piles. The model generated water quality estimates over time for a variety of management scenarios at several potential discharge locations. The integrated approach used by the model was effective in identifying the significance of key factors influencing overall water quality such as explosives use, mine water inflow rates, waste rock reaction rates, site/mine management options, and effectiveness of treatment. The model provides an example of an effective tool for comprehensive, integrated system evaluation and management.

Jan 1, 2003

By Whittaker B. N, Reddish D. J

The rockbolting method of support is employed widely in several countries in different of mines. Hard rock mines use this method extensively. Soft rock mines, such as coal mines, have employed standing supports (steel sets) as the main method, although some countries such as the U.S.A. and Australia have preferred rockbolting. There is increasing interest in extending the rockbolting method in coal mines. The application of rockbolting techniques in an industry which traditionally has not applied such techniques, has required the development of a systematic design approach. This design approach uses extensive monitoring, to asses the viability of the support system in differing conditions. Currently at a number of new and existing mine developments in the U.K., rockbolting is being successfully applied. Although, inevitably some localised geotechnical problems have been encountered and have needed to be taken into account. The effect of faulting on roadway conditions is discussed in this paper and a design approach has been applied using a numerical analysis method, namely the Finite Element Method. The results presented in the paper serve as a useful guide to roadway support designers, and in particular the role played by different bolts in a range of conditions.

Jan 1, 1992

By A Thompson, E Villaescusa

The Western Australian School of Mines (WASM), Kalgoorlie, has been performing dynamic testing of reinforcement systems as part of the Minerals and Energy Research Institute of Western Australia (MERIWA) Projects M349 and M349A sponsored by WASM, the Western Australian State Government and the mining industry. These projects have resulted in the construction and commissioning of the WASM Dynamic Test Facility and a program of reinforcement system testing. The primary purpose of the WASM projects is to evaluate the performance of complete reinforcement systems when subjected to an axial dynamic load. The test procedure, monitoring and associated analysis enable assessments for each component (ie the element, the internal fixing mechanism and the surface hardware) of the reinforcement system. The performance of a reinforcement system is usually defined by a static force-displacement response to axial loading. However, this static response may not be applicable to dynamic loadings associated with violent failure of rock due to overstressing as mines progress to greater depths. It was therefore appropriate that the responses of reinforcement systems subjected to dynamic loading be defined and evaluated. The key findings from the tests on a number of reinforcement systems are presented and recommendations made regarding their application for dynamic loading.

Jan 1, 2008

The environmental and social responsibilities of the mining industry have long been recognized by the industry itself, but during the past decade it became one of the main targets for the more radical members of the community. This came as something of a shock to an industry which had always considered that it had acted responsibly within the standards of the day. As far back as early 1968, the Australian Min- ing Industry Council (AMIC) was clipping from newspapers the odd letter written by environmen- talists and critics of mining activities. In those days every such letter was carefully studied to ensure that AMIC, if not having the answers, at least had an understanding of the types of argu- ments then starting to be used against mining activity and in favour of environmental preserva- tion. Within 18 months, the infrequent letter to the editor had become a flood of such letters and feature articles, and the environmentalists' attack on mining activities had been launched in all its Vehemence.

Jan 1, 1978

In the general planning of this area, provision was made for the distribution over the whole area as required of the following services:(a) Power and lighting from the substation distribution boards 'located in the winder house.(b) Miscellaneous electrical indicating, control and signalling systems.(c) Telephone lines from the main internal automatic exchange located in the changehouse, the town exchange to the automatic exchange and also direct lines from the town exchange to selected offices.(d) Compressed air from the incoming 16-in. air main. (e) Water, both unfiltered and filtered; and the disposal of the following effluents:(f) Sewage from the area to the town sewage system.(g) Changehouse shower water to the regeneration area.(h) Storm water to the general mine surface drainage system leading out to the naturally drained area north of the No. 8 Shaft.

Jan 1, 1957

By Flann R. C

A small modification to current industrial practice should lead to better nickel powders for use in alloying, electroplating, and powder metallurgy. Nickel powder compacts sold for alloying are not always suitable for electroplating applications, since some presently used commercial powders will expand on sintering. Further, such nickel powders are unsuitable for use in the production of powder metal parts, because of expansion during heating of the near-net-shape preforms. Research in these laboratories has enabled the elimination of expansion, and led to techniques for the production of compacts suitable, in particular, for commercial use in both alloying and electroplating. The techniques include: powder pretreatment, cold pressing and sintering, hot pressing, and hot pressing and sintering. In this way compacts are readily prepared with densities of at least 93 per cent of solid nickel, and these, when used as anodes in Watts general purpose and bright baths, give both cathode current and plating efficiencies of 90-98 per cent.

Jan 1, 1979