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By J J. Cilliers, K Hadler

The potential of air rate profiling to significantly improve the flotation performance of a bank of cells has been shown by numerous studies. To date many profiles have been evaluated; balanced, increasing, decreasing and combinations of these. An increasing air rate profile, where the air rates are increased proportionally to each cell down the bank, has been typically found to yield improved flotation performance compared to other profiles. Air rate profiling has two distinct components; determining the correct total air rate for the bank, and determining the correct distribution of that air. This can be done simultaneously by finding the optimal air rate to each cell in the bank in turn through air recovery optimisation. Air recovery is the fraction of the inlet air which overflows the weir of a cell as unburst bubbles. The peak in air recovery (PAR) is a robust measurement of optimal performance for the operating conditions in the cell, and sets the PAR air rate. In this study, plant trials of different air rate profiles and profiling based on PAR, were evaluated. The total air rates to the bank for all profiles tested were approximately equal, allowing direct comparison. The highest cumulative mineral recovery was achieved by operating at the PAR air rates for each cell down the bank. Different distributions of the same total air rate to the bank gave the same cumulative upgrade ratio, but lower cumulative recoveries. In this work the upgrade ratio is defined as the ratio of the concentrate grade to the feed grade. The increase in cumulative mineral recovery, at the same upgrade ratio, in this study was greater than 33 per cent. Air recovery based optimisation of air rates to banks of cells significantly improves flotation performance as it simultaneously determines the optimal air rate to the bank, and the optimal distribution of that air.

Jan 1, 2009

IN carrying out experiments to determine the amount of metal taken away by fume or fine dust the apparatus used requires to be strong and compact, as it is generaIIy necessary to work on a staging fixed at considerable distance above the ground and against a smoke stack or flue. It is essential that the test be carried out at a part of the stack welI away from any bends, to prevent eddies. The method described below has been used for estimating the dust losses from Dwight & Lloyd sintering machines, antimony drossing furnaces, pot sintering trials, etc., and has been founc! satisfaetory. It is welI to bear in mind that the longer the period over which dust coIIection is extended, the more valuable the result is likely to be. The rateof aspiration of the gases through the apparatus is kept as regular as possible by changing the filter thimbles frequently, and the rate of flow should correspond closely with the rate of flow of the gases up the stack.The apparatus required for carrying out a test is as folIows :-{a) Thermometers : two are required, one for taking the temperature of the gas in the stack and one for giving the temperature of the gas in the aspirating drum. If the temperature in the stack is over 400° C., it is advisable to use a pyrometer such as the "Bristol" the couple being standardized before use at about the temperature of the stack.(b) Pilot Tube: The foIIowing sketch (Fig. 1) iIIustrates the principle of the pitot tube. The readings are to be taken in a straight flue, or stack, preferably 20 diam. away from any bend. A, which is open, faces the air current and...

Jan 1, 1922

The methods employed in dressing 'the tin ore up to the required percentage of purity depend mainly on the type of ore crushed.These may be briefly divided into two distinct classes-viz., q, free: milling ore and a complex milling ore. In the former the ore is practically free from the common metallic sulphides, such as pyrites, mispickel, blende, galena, etc., and 1!' clean concentrate of 70 per cent metallic tin can be directly obtained in one continuous act of concentration; in the latter, however, in order to get a good extraction, it is only advisable to primarily concentrate up to 30 to 40 per cent. tin oxide, the rest being the sulphides of the metals. This concentrate is then roasted, re-ground, and re-concentrated up to 70 per cent. metallic tin on a separate set of tables.In the complex milling ore the tin is intermixed very closely with the sulphides, so that it becomes necessary to collect all the mineral present in order to obtain clean tailings. Stamp mills are the most popular machines for the primary crushing in the district, but whether they are invariably the best for the purpose is rather an open question. No doubt for some of the very tough chloritic ores they are the most efficient, but for a brittle quartzose ore, such as the free milling proposition usually is, the writer thinks Oornish rolls would well hold their own, especially when the tin occurs coarse, as is so often the case with this class of ore. Of course, the great drawback to stamps is the excessive quantity of tin slimed and slime tin is one of the problems of tin-dressing-while rolls give...

Jan 1, 1907

With the advent of the resources boom in the late-1960s most of the larger scale resources projects in Australasia were commissioned on an æowner miningÆ basis, where the mine owners owned and operated the primary mining equipment. Then, in the 1980s with the arrival of the gold mining boom in Western Australia and elsewhere, a change occurred û most of the mining activities were carried out on a contract mining basis. Over recent years, however, there has been a marked trend amongst larger Australasian open pit mining operations back towards owner-controlled and operated mining operations. The reasons for this are many and are addressed in the paper, but centre on the concept of the owner being prepared to assume more of the mining risk in exchange for the advantage of not having to pay a contractorÆs profit margin. Where mining contracts are entered into, the older æschedule of ratesÆ format is being replaced with less adversarial and more entrepreneurial contract alternatives involving operating cost and risk sharing in a spirit of æfair dealingÆ. Leasing and maintenance issues have also been influenced in recent years by the advent of more flexible contract arrangements with equipment suppliers. Group purchasing has also had some influence for project operators. For many mine owners, the optimal risk management profile involves a practical offsetting of the assumption of mining risk on the one hand, against the removal of litigation risk and potentially reduced operating costs on the other. Potential pitfalls may arise where equipment size and type requirements vary with time or where manpower management, mining flexibility, job skills or safety exposure factors are relevant. These issues are commented on in the context of some well known examples, and an update is provided on contract mining versus owner operation in large-scale Australasian open pit mining generally.

Jan 1, 2002

By Derham DW, Newcombe LA

The operations of the Mount Morgan gold tailings retreatment plant were significantly improved in 1984 by the desliming of the CIP plant feed, which reduced cyanide consumption and increased percent gold dissolution. Subsequently, the development of slimes treatment, incorporating gold leaching from slimes solids by copper cyanide complexes in the process water, and gold adsorption on to carbon in an environment lacking free cyanide was successfully implemented. Mount Morgan was initially mined for gold commencing in 1882 on the auriferous ironstone cap to the sulphide ore body. During the history of mining and processing at Mount Morgan the operations have developed through numerous phases of gold and copper production, operating almost continuously through until the final closure in late 1990. The final phase of processing was the retreatment of tailings, predominantly flotation tailings accumulated since the 1930s, for the recovery of gold and minor silver. Tailings retreatment commenced in 1982 with the commissioning of a 10 000 tonnes per day CIP plant to treat some 40 million tonnes of tailings at an average grade of 1.08 g/t Au. The initial operations were hampered by high cyanide consumption and poor gold dissolution on the mixed siliceous/pyritic tailings. The successful development and implementation of the desliming of the CIP plant feed in 1984 (as described by Parsons and Hampshire, 1986) reduced cyanide consumption by 40 per cent, and raised gold extraction by 13 per cent points by virtue of significantly higher dissolved oxygen levels. The finer portion of the reclaimed tailings were deslimed by eighty 100 mm diameter AKW cyclones, with the desliming cyclone overflow thickened in a Warman 30 in diameter thickener for water recovery and slimes disposal. Operation of the desliming plant involved the discarding of a slime fraction representing about 15 per cent of the reclaimed feed. Although gold-bearing, the high content of cyanicides and oxygen consumers within the slime negated any conventional treatment of this stream with free cyanide for gold recovery. The natural lixiviant behaviour of the soluble copper cyanide complexes for gold, which was extremely evident at Mount Morgan, directed efforts in this area. Enhancement of gold leaching with a deficiency or near absence of detectable free cyanide, but with significant levels of copper cyanide complex from recycled process water were examined. Adsorption of this solubilised gold onto carbon in a similarly difficult environment required close examination.

Jan 1, 1993

The hydrological cycle in nature, with particular reference to Australia . 2. The definition of water pollution drawing on the experience of several major countries. 3. A description of the pollutants in water, and why they are pollutants. 4. The classification of waters as defined by major overseas countries. 5. The criteria and standards developed by major overseas countries for the classification of waters. 6. A brief- summary of the legislation adopted by overseas countries for the control of water pollution, and of the organisation and administration of controls. 7. A study of Australian legislation and administration of controls of water pollution. 8. General observations and conclusions.

Jan 1, 1971

I am honoured to have been asked by Sir James Foots, the President of the Congress Organising Committee, to open this, the 13th Congress of the Council of Mining and Metallurgical Institutions. The theme you will be addressing over the next few days is "The Twenty First Century - Mining, for Mankind" - a theme that must be regarded as an enormous challenge for the entire minerals industry. Previous conferences, starting in 1924 in London and followed by two others in the United Kingdom, have also taken place in Canada (three), Southern Africa (three), Australasia (two), and Hong Kong (one), but this is the first to be held in Singapore.

Jan 1, 1986

The operation of a one tonne submerged combustion pilot plant for the recovery of copper from anode furnace and converter slags is described and the effects of variables discussed. Using coal as reductant, copper levels of anode furnace slag were lowered to 1% or less, with batch times of approximately 120 minutes. Fluxing with limestone was required to produce a fluid slag at temperatures of 1200 - 1300¦C. For converter slags, reduction to 0.5% Cu or less was achieved in batch times of 35 minutes. The chemistry of the pyrometallurg- ical recovery of copper is briefly reviewed in relation.to copper recovery methods.

Jan 1, 1978

By Dawes C. A, Mitchell R. A

A process control strategy has been developed for the lead circuit of the lead- zinc concentrator at The Zinc Corporation, Limited (ZC), Broken Hill, Australia. The general aims of the control system were to produce a final concentrate with a zinc content below a certain limit and, at the same time, obtain the highest lead recovery possible. As presently arranged the system involves control of the cleaner feed mass flaw by cleaner diverter tray manipulation and control of xanthate addition based on per cent lead in feed. Generally this approach works well but for abnormal conditions such as very high or law pH the system requires further improvement.

Jan 1, 1983

No paper was submitted for the proceedings, verbal presentation only (no material available).

Jan 1, 1998

Someone once said "Leadership is the ability to inflict pain and get away with it." The same can be said about successful management of equipment suppliers. Improved performance will not be achieved without some pain, but it should be evenly spread between both parties. In practically all mining situations there is a great deal of scope for improving performance and reducing maintenance costs on an extremely wide range of plant, but it requires co-operative effort. Most mine maintenance engineers attribute the main problems to the equipment suppliers, unsuitable designs, lack of spares, untrained servicemen, lack of standardisation, poor maintenance manuals, and so on. Conversely the suppliers' engineers are usually convinced that problems with their product are exclusively due to poor maintenance management, after all they never have the same problem elsewhere. Of course both are correct to some degree. My aim in this paper is to explore the opportunities for substituting collaboration for confrontation between the engineers of the mining and supplying companies. I will also propose that contrary to common belief, the mines rather than the suppliers, should be taking the management initiative needed to achieve a closer and more effective relationship, Many would argue that this initiative should remain solely with the supplier; after

Jan 1, 1980

The geochemistry of waste rock from mining operations is critical to the development of acidity-related environmental problems during mining operations, and following mine closure. Failure to recognise the potential for waste rock to produce acidic oxidation products may cause mobilisation of heavy metals into ground and surface waters, and create heavy metal levels in soils which are toxic to plants, causing the failure of revegetation programs. Although more usually associated with wet tropical environments, the potential exists for these problems to occur even in and regions such as the Eastern Goldfields region of Western Australia unless appropriate pre-planning is undertaken.Acidity-related mine waste problems can be extremely expensive to rectify, but can be avoided by waste rock characterisation, and pre-planning of waste rock deposition based on this information. Integration of knowledge of waste rock geochemistry with geotechnical engineering, and application to likely problems, is essential for the successful planning and implementation of cost-effective strategies to avoid problems occurring. Pre-planning to avoid problems is likely to be significantly less expensive in most cases than remedial actions to rectify problems after they have occurred, and in fact may involve no additional cost if it requires only rescheduling or redesign of existing or planned Activities.

Jan 1, 1993

The Curragh mine has complex operating conditions. The mine operates in four seams to produce two coal qualities and is divided into five pits which have different qualities and coal preparation characteristics. The combination of all of the necessary controls to achieve maximum resource utilisation has necessitated the development of suitable software to assist the quality control engineering function. The required software had to be able to plan the optimum yield of coking coal whilst achieving the quality parameters for the coking coal and co-produced steam coal. The program has been designed to evaluate all of the mine faces available for coking coal production. The optimisation of coking coal production is planned and co-produced middlings steam coal determined. The optimum steam coal product is determined using the middlings in combination with bypass production.The computer software to carry out these functions has been designed by using an exploration data base as the raw data source. The program accesses this data and uses a coal preparation prediction program to determine the yield vs. ash relationship for each coal face. A linear program selects the optimum -combination based upon equal incremental ash values. The final output lists feed tonnages, coal preparation conditions, product tonnages and full coal quality data.

Jan 1, 1985

The value of water is defined by its marginal utility. Challenges arise where the marginal utility is difficult to estimate. Therefore, when two or more interested parties wish to access water and they cannot use commensurate units for marginal utility; other means of value comparison must be sought. It is asserted here that sustainability principles can be used to guide this valuation if this is supported by a transparent decision framework. This paper proposes that the ICMM sustainable development principles provide appropriate guidance. In addition, a generic framework for decision making is suggested as a complement. Indicators of water management are recognised widely as an integral part of the accountability of minerals companies towards meeting sustainability goals. Less widely recognised are the ways in which sustainability principles can be used to guide decisions on water management which demonstrate growing awareness of its value. This paper illustrates the use of this logic in water issues associated with global sustainability challenges. It then goes on to demonstrate, using examples, that these links exist at all levels of the minerals industry and that indicators of this type are potentially as powerful as those currently being used. The reason for this is that the path from cause to effect is transparent and direct.

Jan 1, 2006

By T Tran, F Lucien

Supercritical fluids (SCFs) have gained recognition as solvents for the extraction of a wide range of organic materials. Their principle advantages over conventional organic solvents are that they possess much more favourable transport properties and that such properties can be easily altered by adjusting the system temperature and/or pressure. More recently, SCF solvents have been employed in the extraction of metal ions. The direct extraction of metal ions using SCFs such as CO2 is normally not possible due to the charge neutralisation requirement for solubilisation. However, extraction can be achieved with a SCF solvent containing an organic complexing agent as a cosolvent (Laintz et al, 1992; Laintz and Tachikawa, 1994; Dehghani, 1996). The role of the SCF is therefore similar to the role of a diluent in conventional liquid-liquid or solvent extraction processes. In this regard, SC-CO2 is a particularly good diluent since it exhibits good solubility for many organic complexing agents. The extraction of metals with SCF solvents has been examined mainly in the analysis of environmental samples and the treatment of metal contaminated wastes. Nonetheless, some interesting results have been reported recently on the extraction of rare earth metals, which highlight the potential of SCF solvents in mineral processing applications (Laintz and Tachikawa, 1994; Dehghani, 1996).

Jan 1, 2000

International tenders for contract mining opportunities require the Contractor to make an assessment of risk for an operation with a life span of up to twenty-five years usually based on data made available by the Client. This paper seeks to address how the Contractor assesses the data and quantifies the risks associated with the project. The areas of risk are common to most projects, but in the--Lontractor's case, risk assessment is carried out on the Client's data base and within a compressed time frame of usually less than six months. Incorporation of that risk assessment into the contract documentation is also discussed. Practical examples are given in a number of areas.

Jan 1, 1986

By G D. Cooper

There are no manuals or handbooks for budding mill superintendents or process plant managers. Most who obtain this level of responsibility have gained their training from watching the good and bad of their predecessors and the successful ones have themselves graduated from the school of hard knocks. This paper attempts to provide some helpful guidelines and direction for those who aspire to better manage a mineral processing facility. The authors have 20 years combined experience in senior management roles at nine different mineral processing operations in Australia and overseas, covering gold, base metals and mineral sands. This summary of tips and pitfalls will hopefully benefit future leaders in mineral processing and metallurgy.

Jan 1, 2007

By Gluch KD

The current Mining Act has been the mechanism for administering and encouraging the State's mining industry through the 1970's up to the present. Although it has been subjected to considerable amendment there continues to be judicial challenge as well as criticism in relation to ambiguity of interpretation. Expansion of the mining industry and pressures placed upon "it by the ever increasing interaction with other land users have highlighted deficiencies in the current legislation and the need for a strong and progressive Act covering the rights and obligations of miners and their relationships with those outside the industry. - It is considered that the most positive results can be achieved by a complete redrafting of Queensland's mining administrative legislation.

Jan 1, 1987

The optimisation of human resources provides the path to improving productivity. British Coal has the goal of competitiveness with a quality product in ensured supply. High class skilled professional management teams will analyse job definition and selection procedures for posts, as well as objectives for and delivery of effective management training.Some fundamental changes in attitudes towards training as a means of achievement may be by managers at all levels self-examining their abilities to improve their styles, and by moving training more into the world of high technology techniques. The resulting improvements to management and training with attendant cost benefits will be enjoyed by the companies responding most effectively to these challenges.

Jan 1, 1991

By West R

Since its introduction in 1989, the Australasian Joint Ore Reserves Code (the JORC Code or the Code) has been one of the success stories of the informational interface between the mining industry and investors. This is due variously to the user-friendly nature of the Code itself, to its practical approach to this complex subject, and to the way in which its requirements have been implemented in practice. Recognition of its utility and effectiveness has influenced a significant number of mining countries to re-assess their reporting standards with the positive outcome being that for the first time, a set of standard international definitions for reporting of mineral resources and reserves is a realistic possibility.

Jan 1, 1996