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By M E. Malmstr÷m

Quantification of site-specific sulfide oxidation rates is crucial to accuracy of prediction of, for example, the environmental impact of a mine site. Sulfide oxidation reactions are reportedly increased by bacterial mediation; determination of abiotic and biotic weathering rates thus requires the establishment of sterile control samples. However, sterilisation often involves exposure of samples to extreme conditions that may alter the physical, chemical, or mineralogical characteristics of the tailings and hence affect element release rates. The impact of various sterilisation techniques, common and novel, on the element release rates from tailings from the Kristineberg site, northern Sweden, has been investigated. Batch weathering experiments indicated that the different methods of sterilisation (autoclaving, heat treatment, ethanol/heat treatment, application of antibiotics, rinsing with distilled water, and γ-radiation) did not greatly affect long-term element release rates. Long-term experiments (>30 days) are thus to be recommended for establishment of weathering rates. Sterilised and untreated control samples showed similar element release rates after ~100 days of experiments; possible explanations include that microbial oxidation is not important under our experimental conditions (Po2 = 0.2 atm, pH ~2.3, 22¦C, 0.01 M HNO3, no additional nutrients).

Jan 1, 2003

In planning and operating mining projects, managers must take into account economic conditions in foreign markets in addition to Australian conditions. As the manager has little influence over the price or the demand for the product, it is particularly important that close attention is paid to the control of costs to ensure that the mining operation remains competitive with foreign producers. This is not necessarily true for some sectors of the domestic manufacturing industry where foreign competition is restricted and costs can be passed on to consumers because of the protection afforded by tariffs. The effects of protection on the cost structure of Australian industry are more pervasive than is commonly understood. The issue of protection is particularly important to the Australian mining industry management because the cost burdens imposed by local protection must be absorbed within profit margins. Furthermore, because protected industries are effectively subsidised to use scarce resources such as skilled labour, the development of more efficient industries such as mining is inhibited. The mining industry has much to gain from any relaxation in protection policy, and hence the issue is of considerable importance to all managers in the mining industry concerned with costs.

Jan 1, 1980

By S C. Goel

The Obuasi Mine in Ghana, West Africa is the largest producing gold mine in Africa, outside South Africa. The mine has changed from a mine producing from narrow vein, high grade quartz orebodies to a mine producing from wide, lower grade sulphide rebodies. Traditionally mining methods were cut and fill and sublevel caving. Now the preferred stoping methodologyis long hole open stoping. Transverse or longitudinal methods are both used, dependent on the orebody characteristics. The change has been technically, socially, economically and politicallychallenging and at times has tested the abilities of those responsible for the operation of the mine. However, the benefits have been many. Safety has improved significantly, ounces from underground have doubled. Productivityhas doubled and underground unit costs have reduced bya third. These achievements have allowed the Obuasi mine to staycompetiti ve in this time of falling gold price. During 1999 and 2000 a full review of the mining and processing operations was undertaken, and as a result, the mine is now in a phase of restructure. Efforts are being made across the mine to improve efficiencies and to reduce costs. The future for the Obuasi Mine is an exciting one.

Jan 1, 2000

The P49 Shaft, Hilton Mine, was sunk and equipped for Mount Ise Mines Limited by con- tractors Cementation - Thiess Joint Venture. The leached siltstones to a depth of 150m were known to contain large volumes of water. These siltstones were cored and tested in the laboratory. Field results confirmed that cement grouting was relatively ineffective but that chemical grouting was effective. The Sm diameter shaft was sunk to a depth of 1040m. Weak strata to the full depth re- quired continuous temporary support by rock bolts and mesh before the concrete lining was poured, and made sinking conditions difficult. After completion of the shaft sinking the headframe was redesigned and modified to allow shaft equipping as a combined service and hoisting shaft with seven compartments. The shaft steelwork was designed and fab- ricated for service with high speed conveyances operating under corrosive conditions. The steelwork, weighing approximately 1500 tonnes, was installed to a high degree of accuracy which required guides not to depart from true verticality by more than 2mm over any 5m, or 15mm over the full shaft depth.

Jan 1, 1976

By West Coast Staff

Attention to the design of facilities for drainage, of both surface water and seepage, made it possible to attain, for a qam impounding residues from a concentrating mill, a more stable sand wall which can eventually be carried to a greater height.EXPERIENCE WITH No. 1 DAMResidue from the lead zinc concentrating mill, which treats the ore from the Rosebery and Hercules Mines, was pumped 3,600 ft. through a 5-in. diameter woodstave pipeline to the site of the dam. It was formerly delivered through a 4-in. steel pipeline.State laws prevent the residue being discharged to waste into the Stitt River. Furthermore, as a pyritic residue it is a potential source of sulphur.Between 1936 and 1956 more than 1,000,000 tons. of residue was paddocked. The run-of-mill product was roughly classified at the dam in a 6-ft. diameter cone classifier and the sand fraction was pumped by a 3-in. pump to the front wall of the dam across a shallow valley. The overflow gravitated to the rear of the dam (Fig. 1). Typical sizings were:

Jan 1, 1958

The word "optimization", refers to the search of an economic optimum, or, more precisely, to the choice of technical parameters which will define the more profitable mining project, knowing the values of the economic parameters. In fact, there is no direct way to perform this optimization, because the extremely large number of technical factors involved, from the type of working and its selectivity to the characteristics of the mill and its flexibility, makes it impossible to make a comprehensive survey of all possible projects. Beside, it would be meaningless to engage in such a task as the deposits themselves are not really known, but only estimated, with sometimes a high level of imprecision. Not to mention the numerical instability which would affect such a computation! In addition, the "best" project is not necessarily the one which strictly maximizes a given profit formula. There also exist human factors which have to be complied with, when choosing the cutoff grades for instance. Finally, there are other non-numerical factors which interfere with the choice between several projects: the shape of the bottom of a pit of the layout of the access road for instance.

Jan 1, 1986

By P Waters

BHP Billiton Iron Ore initiated a program in January 1995 at the Mt Whaleback operation in Newman, Western Australia to develop a closure plan for the overburden storage areas (OSA), which have the potential to generate acid rock drainage. The primary research program includes the development of technology for the long-term performance of OSAs with respect to slope stability, surface run-off, erosion, water infiltration and vegetation. The objective is to control acid rock drainage by preventing moisture movement into and through the OSA material. Infiltration to the underlying OSA material and closure costs are minimised due to the presence of the run-of-mine (ROM) cover material. A summary of the field data is presented to illustrate low percolation rates to the underlying OSA and key performance characteristics of the moisture store and release cover system design. Field data collected to date demonstrates that a moisture store and release cover system constructed with suitable ROM material has good potential as a final cover system at the Mt Whaleback site. The performance of the cover system on a sloped surface was significantly different as compared to placing the cover system on a horizontal surface.

Jan 1, 2003

By Gillies A. D S

Replies to a comprehensive questionnaire on mine water resource management systems (WRMS), which were distributed to a selection of Australian mining operations in 1991, are analysed. Although the replies cannot be considered fully representative of the industry, they do provide a good qualitative indication of water resource management in the industry at that time.Within Australia's largely arid land mass, a majority of mines nonnally need to conserve water, a few need to dispose of water and a number face a seasonally varying position. An assessment of the importance of WRMS compared with management of ore extraction and processing is given. A risk assessment of failure is given; there is more acceptance of WRMS failure in the mine compared with the mill. An assessment is made of considerations in WRMS design. Managements are generally pro-active in the design of WRMS and in the setting of perfonnance standards. The operational characteristics of mine systems are examined in detail.Companies generally do not appear to allocate sufficient resources for the collection of basic WRMS monitoring data and knowledge of the water budget to efficiently manage the system. This indicates scope for considerable cost savings in most mines.

Jan 1, 1995

By Richardson G. W, Yap L. C

Friction rock stabilisers (FRS) are the most common steel-based ground reinforcement used in underground mines in Western Australia. As with any other steel-based product used in underground mines they are susceptible to corrosion, particularly under aggressive minewater and mineral conditions. Because of their thin-wall tubular construction and large surface area, the potential damage resulting from corrosion is considered to be more severe for this type of reinforcement than for other forms of reinforcement made of solid steel bars. Because of the obvious safety problems which may result from corrosion, both mine operators and regulators have raised concerns regarding the long-term effectiveness of FRS installed in underground mines in Western Australia. Although corrosion has been recognised as an important safety issue, the controls of corrosion in varied underground mining environments has not been well understood. To improve the understanding of the corrosion behaviour of FRS, the Department of Minerals and Energy has initiated a research project focused on the mechanisms and extent of corrosion attacks, and their influence on the effectiveness of the reinforcement. This paper describes the research project and presents the interim results achieved To-date.

Jan 1, 1995

Gold mineralization belt of eastern China in the adjacent part of the northwestern Pacific rim is orientated NE to NNE and as-sociated with Mesozoic faults and igneous intrusives and Mesozoic to Cenozoic volcanism and subvolcanism extending more than 3000 km in length and 300 to 800 kni in width affected by the movement from the Pacific Plate subducted against the Asian Plate.The relative movement between the Pacific and the Asian plates give rise to two types of fracture zones, the tensional ones providing the space for the formation of fissure-filling type of auriferous quartz veins and the shear zones providing the space for the formation of hydrothermal replacement type of gold de-posits in Shandong Peninsula. The fissure filling type of quartz vein, is represented by Linglong gold deposit which is hosted in Mesozoic Linglong Granite and consists of hundreds of quartz veins filling fractures trending NE to NNE and the hydrothermal replacement type is represented by Sanshandao gold deposit which is hosted in crushed and hydrothermally altered Mesozoic Linglong Granite in contact with Archaean metamorphic complex of Jiaodong Group along a Mesozoic upthust fault zone trending NE.

Jan 1, 1990

By Skaviniak M

Some better perspectives applying to the exploitation and dressing of polymetallic ores in the Banskfa. gtiavnica-Hod- rusea Ore District are supposed to be achieved after a suc- cessful investigation and proving there the existence of deep-seated mineralization as well as due to increasing de- mand for non-ferrous metals and consequently to higher mar- ket prices of those recently noticed. With respect to the present situation in mining and to the further technical development as well, a several times higher exploitation may be in this region expected, especially in the deeper .eated parts of the deposit. When solving the tasks of a complex economic exploitation over the whole region, consi- derable attention is paid to regional relations and impact studies (due to expected exploitation and ore dressing but also to very difficult problems of dewatering (drainage pro- blems-). It will be first of all necessary to find there an equilibrium between the consequences resulting from the re- naissance of mining industry and environmental requests un- dispensable for the city of Banska 9tiavnica and the other neighbouring towns in the vicinity of mining plants.

Jan 1, 1988

By Muir D. M

Highly saline process water has a number of implications for the CIP process during the leaching, adsorption and recovery of gold. The reduced oxygen solubility in saline water can seriously reduce the rate of gold leaching, while dissolved oxygen meters do not necessarily reveal actual oxygen concentrations in saline water. High levels of magnesium in the ground water necessitate operation at lower pH (-9), with the potential for greater cyanide loss via HCN stripping. In addition increasing salinity renders viscosity modifiers largely ineffective.The adsorption capacity of aurocyanide onto activated carbon is improved with increasing salinity, but misleading results can be obtained in assessment of gold loading kinetics of plant carbon samples already loaded, or partially loaded, in saline water if subsequently tested in fresh water. Elevated chloride levels in the Zadra elution process can cause severe anode corrosion in the elecuowinning cell. The Anglo elution process is tolerant to only slight increases in water salinity, but elution times can be reduced by ethanol addition. Care is required in carbon regeneration, as salts can catalyse carbon decomposition as well as increase kiln corrosion.

Jan 1, 1994

By U Dzharlkaganov, B Bekmurzayevand M

The principle conception is presented of timely planning of winning operations in complex-structural blocks and faces in week-24-hourly regime. For adequate description of complex interconnections of open cast operation in space and in time and solving of optimisation problems in timely regime it is necessary using of complex logical and calculation procedures.

Jan 1, 2003

A unique opportunity is presented to Australia by recent developments in the Carpentaria and Mount Isa Mineral Province.Unique in two ways:The size, diversity and multiplicity of mineral finds in the region, and the continuing prospectivity.The approach being undertaken to accelerate development, increase the value generated for all stakeholders, and the value added in the region.

Jan 1, 1993

The international scientific and engineer-ing community is being challenged to take advantage of the opportunity offered by the U.N. International Decade for Natural Disaster Reduction (IDNDR) program to reduce rapid onset geological hazards along the Pacific Rim. Natural disasters observe no national boundaries; international cooperation offers the best opportunity to reduce the losses these catastrophic events create.

Jan 1, 1990

By Zhijing Z, Huiling Z

The influences on flotabilities of dolomite and magnesite with modifiers and influences on the function of collectors and modifiers with Mg+z Ca+2 were studied. The flotation results of artificial mixed mineral showed that using combined salified water glass and (NaPO3)6 as a modifier for magnesite-dolomite separation can obtain an excellent Selectivity.

Jan 1, 1993

Oxidation or sulphidization of the surface of pyrrhotIte partIcles enhances atomic interdiffusion at elevated temperatures and provides a mechanism for interface growth between particles in contact. In a mass of pyrrhotite-rich ore or tailing, where oxidation heating is not controlled, bonding of particles by diffusional mass transport contributes significantly to the agglomeration of the mass.

Jan 1, 1976

By Langberg D, Gray N. B

The flocculation of hydrophobic magnetite with gold was examined as a possible means of recovering fine (95 per cent were possible for 1.5 - 3.0 ¦m and 5.5 - 7.5 pm gold sizes. The effect of process variables on the flocculation process was explained by variations in the adhesive force between the gold and magnetite.

Jan 1, 1991

This address was delivered at the Annual Conference Presidential Dinner held in Sydney on 11 July 1988.The Australasian Institute of Mining and Metallurgy brings together, voluntarily, people with a professional interest in the disciplines and skills which are employed in the mineral industry, and in relation to that industry.We come together because we have a mutual interest in improving what is done by the mineral industry, in all its aspects. It is this sense of continuing improvement, of doing better, of doing as well as we can, as our knowledge and skills improve, that unites us in creating and fostering a professional association of likeminded people.We know from our professional training and experience that enormous progress has been made, at an ever-increasing rate, in the mineral industry, particularly this century. We know that the mineral industry has played a very major role in providing the means by which so many more people survive to live longer, healthier ,and more interesting lives, than ever before. Indeed, together with the oil and gas industry, which is an integral part of the mineral industry but has achieved its own commercial distinction, it is fair to claim that the mineral industry has played the major role in providing the means for the advancement of the human, quality of life.We do not need to make any great claims on human society in consequence of our statement of these contributions. The facts, for those who are aware of them, speak for themselves. Our more modest interest, as members of our professional association, is to look to the future, while conscious of our heritage as a guide to what more might be done, in that future.We certainly do not claim that this indisputable contribution made to human welfare by the mineral industry gives us some moral position of superiority from which to claim greater support or understanding from the wider community of people.On the other hand we know that as members of the mineral industry we have a responsibility to do what we can to help other people to be aware of, and to understand the significance of, those facts which will only speak for themselves if we take the trouble to make them known. And we have a number of organisations. The Institute itself, The Australian Mining Industry Council, the various State Chambers of Mines, the industrial relations body, The Australian Mines and Metals Association, and others, each of which in its own way endeavours to add strength to the individual efforts which we each should make.We may look at these facts about our mineral industry as simple dry statistics, even with their undoubtedly improving trends, or we can see them, and portray them to others, as expressing something which is much more. We can portray them as expressing the outcomes of our professional determination to strive to do better, whatever it i,s we find ourselves doing in this mineralindustry.We may seek to describe our efforts as being in pursuit of excellence, or by other such high-sounding phrases, but I prefer to describe those efforts as simply our strivings to make everything we do better next time-much as the dedicated golfer tries to do, but with, may I suggest, more evident success achieved in the mineral industry; which is one reason why I don't try to play golf.May I suggest to you that trying to do better, is very simply the true basis of professionalism? We are trained and practised to see the opportunity for improvement-not to be static in a world which we know is changing so rapidly in every aspect around us. We must be dynamic, which means optimistic, about improving the world in which we find ourselves.

Jan 1, 1988

By N Murphy and, S Santomartino, M Cramer

Acid rock drainage (ARD) can have detrimental effects on mining infrastructure, water reuse options and environmental discharge. As a result, some form of short- or long-term treatment is required at many mine sites. Successful treatment depends on a number of factors including the selection of an appropriate treatment technology and its correct implementation. A variety of passive and active technologies are available for dealing with ARD. Passive treatment solutions do not require continuous chemical inputs but take advantage of naturally occurring chemical and biological processes. They are often low cost, site specific approaches and are predominantly used in post-closure situations. Passive systems are well suited to drainage with low acid loads and low soluble aluminium concentrations, and are more effective with highly reduced (ie low oxygen) water. While they are often regarded as permanent fixes, most require some form of ongoing maintenance and all have an engineered life expectancy (ie finite carbonate and organic matter budgets). Passive treatments include, oxic limestone drains, anoxic limestone drains, limestone diversion wells, various reducing and alkalinity producing systems, pyrolusite limestone beds, aerobic and anaerobic wetlands, permeable reactive barriers (organic ¦ carbonate and zero valent iron), slag leach beds, and gas redox and displacement systems (GaRDS). Active treatment solutions require a continuous or semi-continuous activity (eg reagent dosing) to correct water quality issues. They can be engineered to treat virtually any type of drainage or site specific ARD issue, and have no set acid load or redox limitations. Tasks handled by active treatment systems are almost invariably larger and more costly than for passive systems. Active treatment approaches include; pH control, adsorption/absorption, ion-exchange, electrochemical concentration, biological mediation/redox control, flocculation/filtration and crystallisation. A range of generally available and proprietary technologies has been developed around these approaches. Active treatment involving pH correction with alkaline amendments is the most common and cost-effective form of ARD treatment. A variety of fixed plant and portable treatment systems are available. Calcium-based reagents, including quicklime (CaO), hydrated lime (Ca(OH)2) and limestone (CaCO3) remain the reagents of choice for the majority of active ARD treatment worldwide. This is principally due to their widespread availability, non-proprietary nature, and variety of proven dispensing technologies and cost-effectiveness. Limestone, in particular, is a very low cost reagent. However, due to æefficiency of useÆ problems with limestone in passive treatment systems, combined with its very low cost, there has been a recent emphasis on developing active treatment systems that use limestone efficiently. As the requirement for treatment increases, there is a growing emphasis on treatment sludge management and sludge stability. The final choice of a suitable treatment technology is dependent upon water chemistry (eg pH, type of metal contamination, acidity), flow rates, acid load, local natural resources (neutralising materials, topography), climate, site logistics, environmental risk and economics. The benefits and limitations of both passive and active treatment technologies are summarised.

Jan 1, 2003