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Heavy medium separation is widely used because of the precision of separation achievable and the flexibility of control. Good design is manifest in the eventual achievement of the operational objectives. These objectives which take account of the assessed quality of raw feed, market requirements and production cost levels need to be carefully prepared and realistic.

Jan 1, 1987

Sasol Roche Blasting Services (SRBS) and its former owners have been in the process of developing and utilising low-density explosives over the last ten years. Many blasts have been fired in varying strata types in a number of mining operations. This has led to a good understanding of the product and the best methods to exploit its characteristics when designing blasts. Unlike some other low-density products, SoftLOAD« is a homogeneous mix that is easily handled and able to be loaded at high load rates. This paper discusses the physics of SoftLOAD« low-density explosives and how through correct utilisation, blasting outcomes can be significantly improved. It also touches on the various side benefits that can provide the blast designer with a more controlled blast.

Jan 1, 2004

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 Aust M. I E

IT is the custom, I must admit, for a presidential address to be a review of the progress during the year of the institution presided over, and of the sciences and arts within its ambit. On this occasion precedent is departed from in favour of a subject by request.As man has at last, in employing gravimetric and electrometric methods of subsurface research, started on the rational use of divining rods with some knOWledge of their governing laws and principles, and with some ability to interpret the results obtainedfrom them, I was asked to add to the voluminous literature of the quack or empiric divining rod. James Mansergh, the author of Melbourne's sewerage system, in his presidential address before the Institution of Civil Engineers in 1901, admitted he was afraid touse the hazel rod lest in sinking on its indications to some solution.

Jan 1, 1928

By Linge H. G

The effect of the presence of ore pulp on the adsorption rate of gold on activated carbon has been studied. A substantial reduction in the rate occurs when the pulp is present. The reduction in rate appears to be caused by two effects: permanent carbon pore blocking by ore particles and temporary shielding of the carbon particle surface, slowing gold access to the carbon due to the physical presence of the fine pulp. There is no significant effect arising from the presence of a pulp viscosity modifier even for conditions when mass transport dictates the loading rate of carbon in clear Solution.

Jan 1, 1987

The underwater test is now being used routinely to characterise explosives and initiators. However, several outstanding issues regarding the role of confinement and the usefulness of the test results in predicting expected blasting performance require further elucidation. This paper reviews the underlying principles governing the test, and highlights its relative advantages and disadvantages in product development and applications. It deals with topics of energy release, energy partitioning, confinement and efficiency, supported by illustrative examples from tests with various products and geometries. The results are analysed in terms of both the detonation parameters measured and their extension to predicting blasting performance in the field. It is emphasised, that just as with other performance tests, the results and conclusions are only valid under the particular test conditions employed, and over-generalisation of these results can lead to erroneous conclusions.

Jan 1, 1999

By S M. C Verryn

The amount of raw material used in the production of cement can be reduced by partially supplementing it by pozzolanic waste material without changing its properties negatively. This paper discusses results of an investigation using slag from the Pt industry, from the production of steel using Midrex processes as well as fly ashes from different coal power plants in South Africa. These are blended in a 20 per cent slag or fly ash to 80 per cent cement ratio. The properties of the mixtures depend on the phase composition, chemistry, grain size and the sources of the materials. The results are promising, but show variable behaviour depending on slag and cement composition. Compressive strength tests as well have heat flow curves showing the hydration behaviour, indicating that 20 per cent addition of slag or fly ash to ordinary Portland cement is viable. There is a large potential to use slag in cement mixtures and this study can be used to develop cements that will positively influence CO2 emissions and help to reduce large slag and fly ash stockpiles.

Jan 1, 2008

The major heavy industrial consumers of limestone are the cement, lime'and steel ind- ustries. Each of these requires large quantities of cheap raw material. Other ind- ustries such as glass and chemical manufactur- ing are significant consumers and agricultur- al and constructional activities provide additional demand which is usually more local in its occurrence. Limestone is widely dis- tributed throughout Australia but location in relation to major markets, and transport con- siderations render most deposits of no economic value. Among deposits which are sufficiently close to the major metropolitan markets many must be rejected as being unsuitable on grounds of quality, inadequate size for major.develop- ment, or other reasons such as environmental considerations. The major producing locations are sit- uated in a variety of geological environments. Most have limited reserves and require partic- ular attention to quality control. Planned extraction programmes based on detailed geo- logical investigations enable not only satis- factory grade control but also permit, by the adoption of appropriate quarry procedures, the use of sub-grade material, thus optimis- ing utilisation of the available reserves.

Jan 1, 1976

By D J. Clark, S Hewson, T Li

Cadia Hill Pit is a gold copper porphyry deposit hosted in monzonite. The pit slope design is primarily based on structural controls related to faults and shears with largely massive rock masses between the structures. The slope design attempts to achieve an optimum configuration at a bench to overall scale, considering economics and safety implications against the geotechnical and structural conditions. To date the slopes have been mined at interramp angles of up to 60¦ over heights of 120 m. Limited slope and batter failures that have occurred are structurally controlled and occur rapidly. The pit-mining schedule requires concurrent mining of part of the final pit walls and the progressive interim cutbacks. Engineering and operational solutions to hazard reduction and risk management issues have been implemented wherever viable to æengineerÆ out the hazard and mitigate the risks. However, comprehensive management plans and operating procedures have also played a vital role. This paper details the management plan and the operating procedures that have been developed and implemented to mitigate the risks associated with rock falls.

Jan 1, 2003

By Brady B. H

Increasingly, consideration is being given to the nominal `outcomes' of degree courses in engineering, including mining engineering. These are concerned not only with knowledge and technical understanding but also with capabilities in the professional application of engineering principles to problem solving, multi-disciplinary teamwork, communication and life-long learning. This paper discusses concepts of education, professional formation and training and the associated development of competencies in applying knowledge, understanding and technical insights and skills to new situations. In developing guidelines on preferred attributes and competencies in graduate mining engineers, a survey was conducted of a range of industry personnel involved in selecting graduate mining engineers. The results not only clarified the spectrum of competencies sought but also provided valuable detailed views to assist in defining a mining engineering curriculum. Considering a greater concern with the development of more `well-rounded' graduates, the implications are discussed with regard to teaching and assessment activities and the time demands on academic staff when a `coaching' role is emphasised. In line with international and Australian moves in engineering education, notions on education of mining engineering graduates in Australia are under review. The results will provide continuing challenges to all involved.

Jan 1, 1997

Pyrite is a significant gangue sulphide mineral in the Ok Tedi copper ore. Its presence in the flotation concentrate is not entirely desirable since it lowers the grade of the final copper concentrate. Lime depression of the pyrite has been practiced with some success. However, it has been observed that at the pH for pyrite depression a significant amount of the pyrite particles still float. To obtain further insight into the problem this work has been conducted to determine the composition, natural floatability and xanthate flotation behaviour of the various types of pyrite in the ore. The flotation results show that while some types of pyrite float well at high pH values, others are readily depressed. The implications of these results for Ok Tedi flotation plant have been Considered.

Jan 1, 1997

By E Villaescusa

This paper summarises research work carried out at the Western Australian School of Mines on mine backfill properties in the last few years. The fill properties presented relate to cemented aggregate fill and cemented tailings fill. Emphasis of these studies has been placed on the composition of backfill materials including aggregate particle size distribution, cement dosage and influence of cement admixtures. The unique features of the backfill research carried out at WASM during the last few years are the accomplishment of a study into the properties of large cemented rockfill samples by triaxial testing and the investigation of the properties of fill material made from highly saline ground water prevailing in the Goldfields region of Western Australia. Exploring different cost-effective binding agents for mine backfill was also carried out at WASM. Special effort has been put on the development of fill materials compatible with hydraulic and paste fills. During the process, specific methods and procedures for laboratory testing of backfill material have been formalised. The on-going backfill research on sample scaling is summarised and the future direction of WASMÆs backfill research focus is outlined.

Jan 1, 2000

A continuous casting machine, of the Concast curved mould design casting billets in four strands, was commissioned at the Newcastle Works of The Broken Hill Proprietary Co. Ltd., in November, 1967. Quality assessment of early casts from this plant indicated that steel cleanliness was sometimes inferior to that of equival- ent ingot cast steel. Extensive trials to develop a modified deoxidation technique were not successful in improving clean- liness to the desired level. A "contra-flow" gas shroud, to cover the steel stream between the tundish and the mould, was developed, and proved successful in achieving the required levels of product cleanliness. The inclusion content of six grades of steel ranging in carbon content from 0.10 to 0.70 per cent is examined, and an attempt is made to explain theoretically some of the results obtained.

Jan 1, 1972

By G Mulder, M Adams

Since the introduction of raiseboring 30 years ago there have been many operational and mechanical design improvements in the raiseboring machine, its reamers and associated cutters. These have now made the technology of raiseboring a routine and practical operation within the underground mining world. Over the last decade these advances have been aided by the introduction of robust automation packages which have allowed unattended drilling and reaming, real time performance monitoring and enhancement and the rapid diagnostic investigation of mechanical and electrical abnormalities. The constraint to higher raiseboring performance is now the drill string. However when it comes to a cost-effective solution of applying the high drill string torque and tension necessary for the next step change in performance, designers have æhit the wallÆ. Whilst carbon fiber reinforced plastic composites with abrasive resistant sheaths may offer a solution, the limit of conventional steel, drill string technology has been reached. This limit to advancement is however based on the drill string being in tension and alternative solutions may exist by literally turning the raiseboring paradigm on its head. This paper describes the story of a small Australian company engaged in the design and manufacture of mechanical excavation machines, two Australian raiseboring contractors and three Australian mines going against tradition and pushing down rather than pulling up.

Jan 1, 1998

Water is a key resource input to copper heap leach operations in both quality and quantity. A number of recent developments in analysis of the technology have shown that water consumption can be optimised. The leach consumption has been generally considered in terms of minimisation of the evaporative loss by changing the application method (drippers or wobblers). Modelling of the irrigation effects on leach rate has shown that the poorer surface coverage from drippers has an adverse effect on the leach extraction rate. This is particularly evident in the early part of the leach. The use of different irrigation systems during alternate parts of the leach cycle can have benefits in minimising the water consumption without an unacceptable outcome from extended extraction times. By combining the leach rate effect with the evaporative loss estimates, an economic decision matrix can be generated to allow the operator to select an appropriate leach irrigation strategy, combining both irrigation delivery and irrigation rate. In the SX-EW plant, the total quantity of EW bleed and SX scrub stage bleed (both for iron control) can be reduced to an absolute minimum. The economic minimum may be different depending on the cost of producing the high-quality water used to replace the bleed streams. Adjustment of the SX process, in particular use of multiple entrainment control steps, can provide significant reductions in the total bleed and make up requirements.

Jan 1, 2003

By Waters CA, Happ JV

The debismuthising plant, commissioned in 1980, is based on the Kroll-Betterton process for preliminary bismuth removal with subsequent antimony treatment for fine debismuthising. Bullion flowrate is continuous and the plant was designed to achieve low bismuth lead product at rates of up to 20 tonne/h.Development of the first stage of the operation has enabled reliable operations at 25 tonne/h to be achieved. Thesedevelopments also introduced the opportunity to treat higher bismuth bullion at up to 35 tonne/h when operating the first stage only to produce product lead of 0.029 per cent Bi, meeting the ASTM B29-55 Corroding Lead Standard.

Jan 1, 1985

The Mineral Research Centre is located at Perth in the suburb of Waterford, adjacent to Curtin University of Technology and within a Technology Precinct which includes Technology Park. The Centre, constructed by the WA Government at a cost of $16 million and occupied in late-1994, comprises three separate buildings housing the CSIRO Division of Minerals, Curtin University's School of Chemical Engineering and the Mineral Processing Laboratory of the Department of Minerals and Energy. The emphasis on R&D at the Centre is primarily in hydrometallurgy as a result of staff expertise, extensive bench and pilot-scale facilities, track record with the industry and, very importantly, two of the occupiers being partners in the AJ Parker Cooperative Research Centre for Hydrometallurgy. Staff in the Centre have a long involvement with R&D agencies such as AMIRA and MERIWA. The hydrometallurgical focus of the Centre complements that of pyrometallurgy at the GK Williams CRC in Melbourne and the Centre for Mining Technology and Equipment in Brisbane, to ensure that the mineral processing industry in Australia has access to a complete range of expertise and facilities to serve its needs.

Jan 1, 1996

S. A. Tomich (Consulting Geologist, Perth) : I would like to commend Mr. Haycraft on his presentation on the economic geology of the North End of Kalgoorlie. This is an intriguing area which is in the Kalgoorlie field but not of it, inasmuch as it is separated spatially from the main Golden Mile by the Golden Pike Fault. Mr. Haycraft has stressed the differences-the mineralogical and structural differences of economic significance between the two areas.I would like to ask whether he is satisfied that the lithological sequence in the North End is the duplicate of that in the main Golden Mile area irrespective of the postulated effects of erosion, and more specifically whether there is any chance that the quartz-dolerite-greenstone of the North End may be in any way dissimilar from the quartz-dolerite-greenstoneof the Golden Mile which is tellurude bearing.J. A. Haycraft: In relating the quartz-dolerite in the Hannan's North-Mount Charlotte area back to the Golden Mile, we find some quite close similarities. Although the rocks are similar they are not necessarily one and the same.At Mount Charlotte we have three varieties of dolerite- a coarse-grained gabbroic dolerite on the eastern side of the orebody, the host rock medium grained and on the western side, a fine grained dolerite. Further west we have an amphibolitic variety of quartz dolerite.Recent drilling south of the Golden Pike fault on the Enterprise No. 20 level had indicated a remarkably similar sequence of rocks. We drilled west through a wide section of medium grained rocks into a fine grained rock and then into amphibolitic quartz dolerite before intersecting the Golden Pike fault. Williamstown dolerite was located west...

Jan 1, 1965

The paper gives details of the performance of a 6-ft. by 6-ft. grate discharge ball mill which was converted into a rod mill of the overflow type and then into a grate discharge rod mill. Proposals for further alterations are outlined.INTRODUCTIONThe mill of King Island Scheelite (1947) Limited recovers scheelite by gravity methods.Crushed ore at the rate of 34 tons per hour is divided between two mills. (6 ft. by 6 ft. and 8 ft. by 6 ft. respectively), the mill discharges being pumped to a common distributor which feeds seven Hummer Screens. Each screen has three 4-ft. by 2-ft. Ton-cap sections and repulping compartments are provided. The screen oversize is returned to the mills whilst the screen undersize is finished grinding section product. A third (6 ft. by 6 ft.) mill regrinding the coarser table tailings also discharges into the common Hummer Screen Distributor.The screen undersize is pumped to a bowl classifier which separates at 200 mesh. The bowl classifier sands are treated on tables whilst the bowl classifier overflow, after thickening, is treated in the slime plant by flotation. The flotation concentrate is further concentrated on vanners and slime tables.A recovery of 80 per cent. is possible by tabling whereas only 50 per cent can be recovered in the slime section. The object of comminution is, therefore, to reduce all the new feed to less than a certain mesh (22 mesh Tyler) with the production of a minimum quantity of minus 200 mesh material. cheelite is, a very friable heavy mineral (Sp.Gr. 6'0) and is therefore susceptible to overgrinding. For the evaluation of grinding performance it is hence advisable...

Jan 1, 1955

Mond gas-producer tar, and, in fact, all tars obtained from the retorting of coal where steam and air are admitted to the retort, are of entirely different chemical composition to the ordinary coal tar made in the gas or coke works. These tars contain none of, the aromatic hydrocarbons - benzene, toluene, naphthalene, and anthracene, sought after by the ordinary coal-tar refiner.The distillation of Mond tar shows it to consist of phenols of high molecular weight, unsaturated hydrocarbons of high gravity and low viscosity, paraffin wax, and resinous substances of whose composition little is known.The physical properties of Mond producer tar are also peculiar. It has a "short," granular texture when cold, which might be likened to candied honey. It "dries" (hardens) when exposed in thin layers to the air, and, for a coal tar, it cannot be considered sticky. This latterò property, combined with the short texture, prevents its being used successfully for road-making or macadamizing.The drying properties and the paraffin wax contained in: this tar cause it to hold up large percentages of water, probably in the form of emulsion. When containing as much as 10% to 15% moisture it appears to be quite dry.

Jan 1, 1918