Search Documents

By Dugan K. J

Mine operators are currently in a situation where market forces are acting to reduce profit margins and at the same time, regulatory bodies are insisting on improved mine safety and stability. This means that ground support must be made more cost efficient while maximising operator and equipment safety.A key aspect of ground support efficiency is the 'in the ground' performance. This paper discusses the factors that influence the way rock bolts and cable bolts perform. It highlights the need to know how support efficiency varies in different ground conditions.

Jan 1, 1992

Pongkor Gold Mines is one of seven units of production owned by PT Aneka Tambang (State owned mining company). The mine is located in the western part of Java Island, Indonesia. It is in the Bogor District and approximately 110 kilometres to the south of capital Jakarta. It is located in very steep hilly terrain intersected by many river valleys and the mine site is approximately 500 metres above mean sea level (see Figures 1 and 2 - Mine location map and picture)

Jan 1, 1997

By Mimura K

The carbon reduction of tantalum pentoxide was investigated in a plasma-arc furnace. The sample was a mixture of tantalum pentoxide and graphite, vacuum pressed into a briquette and was reduced at about 3100¦C. Argon was used as the are gas. The optimum mixing ratio of carbon and tantalum pentoxide, C/Ta205 is 5.10--5.15. The sample, weighing 7 g is fused within 60^ 70 seconds by plasma-arc heating and the reduction of molten tantalum oxide with solid carbon pro- ceeds rapidly to approximately 99.5 % Ta during this period. The reduction that follows in the molten state is slow. Within about 10 minutes, the maximum tantalum content of the massive metal product reaches 99.9 % and the oxygen and carbon remaining in the product are 50 ppm and 400. 500 ppm respectively.

Jan 1, 1980

By Lawson E, Purkiss S. A R, Van Ashwegen p C

It is only in the past decade or so that industrial exploitation of biological resources and techniques has become regarded as a distinct discipline. Commonly referred to as Biotechnology, it embraces biochemistry, microbiology and the engineering sciences and is mainly aimed at the biological conversion of suitable raw materials into desired end products. The catalytic agents are more often than not bacteria although other micro-organisms such as fungi are used. The range of micro-organisms used is wide and the choice depends upon the desired end product, which in turn depends upon the metabolic attributes, genetically engineered or otherwise, of the cells. The metabolic diversity of micro-organisms has been applied to processes such as antibiotic production, food processing, brewing and chemical production, and of course extraction of metals from ores. Metabolic diversity is, to a certain extent, based on nutrition, which, in its simplest form, can be divided into energy source, carbon requirements and nature of the electron donor producing reducing power to the cells. The source of energy may be light, in which case the organisms are phototrophic (eg green plants, algae). The carbon requirements and reducing power may come from organic sources. These organisms are then called heterotrophic (eg man and most bacteria, including the well known Escherichia colt). However, there is a group of bacteria whose energy metabolism depends upon chemical redox reactions, use inorganic carbon (CO2) and obtain their reducing power from reduced chemicals such as metal sulphides. These are known as chemolithotrophs. They play an important role in mineral recycling in nature and are also ideal for extraction of metals from ores. This is because they are extremeophiles being acidophilic (grow at very low pH) and sometimes also thermophilic (grow at very high temperatures). These bacteria operate in such hostile environments that competition, or contamination, by other organisms does not occur. Extraction of metals from ores by chemolithotrophic bacteria is commonly referred to as biohydrometallurgy. Other related areas are bioadsorption of metals from dilute solution,- microbial treatment of metal contaminated wastes and removal of toxic chemicals produced or used during mineral processing. This paper basically reviews the work that Gencor has undertaken in the field of biohydrometallurgy and the advancements it has made in commercialising the technology, but also touches on certain long-term areas of research that are currently under investigation.

Jan 1, 1995

The moisture content of clean coal contributes significantly to the product's transportation costs, handleability characteristics and/or energy value. A major contributor to the total moisture is the ever increasing proportion of fine coal in

Jan 1, 1994

By Royle A. G

The paper describes a geostatistical structural analysis of an 80 square mile lease of the Athabasca tar sands. Each step of the analysis is presented with the ultimate objective of condensing the principal structural characteristics of the chosen regionalised variables into the opera- tional form of the variogram model. The variogram model is then used to form kriged local and global estimates, with the corresponding estimation errors.

Jan 1, 1977

In 1980 Pancontinental Mining Limited decided that while the Jabiluka uranium project was still a major focus of the company's efforts some diversification was necessary. At this time it was decided to include precious metals in Pancon's exploration and acquisition objectives. As a result the now Paddington Gold tenements were acquired, explored and developed. Today, it rates as the 6th largest gold mine in Australia and at an expanded throughput of 1.2 million tonnes per year of ore it will produce about 110,000 ozs of gold per year. Following extensive exploration activities by Pancon's Exploration Division the Operations Division continued with development drilling finally proving up a reserve of about 8.4 million tonnes at an average grade of 3.2 g/t. An in- house preliminary feasibility study was followed by a two phase feasibility study by Davy McKee. This resulted in a recommendation to the Pancon Board of Directors to develop Paddington with an annual throughput capacity of 875,000 tonnes. This paper describes the acquisition, exploration and development of the Paddington project. It goes on to

Jan 1, 1986

On-line radioisotope gauges determine information on the characteristics of ore to enable improved control of processing operations. In the metalliferous mineral industry, in-stream analysis systems based on radioisotope X-ray techniques determine concentrations of valuable minerals at various stages of the concentration process. In the coal industry, on-line gauges determine ash and moisture contents, and the specific energy of coal.In-stream analysis systems developed in Australia are installed in about 30 mineral concentrators. Their use has led to the increased recovery of valuable minerals, and the time taken to recover the cost of installation is usually several months. The savings to Australia resulting from use of these analysis systems is estimated to be more than $A 15 million per year.Australian experience in the training of mineral industry personnel shows that the most effective approach is to combine courses on nuclear techniques and control of processing operations. This is the basis of Australia's contribution to the minerals sub-project of the United Nations Development Program (UNDP) Industrial Project.

Jan 1, 1985

By Pitkajarvi J

Waste rock dilution causes mill feed grade to be lower than mineral resource grade. In nickel mines relative grade decrease (dilution) may be tens of per cent because of irregular ore boundaries and weak wall rocks. Five per cent dilution costs millions of dollars annually in medium size underground mine. In Outokumpu Group selective bench and fill stoping, cable bolting/shotcrete-skin support and fast ore boundary definition (OMS-logg in-hole logging or sludge sampling) are the key tools in dilution control. Commitment of the whole organisation to keep dilution low is also needed. Dilution sources and effects are discussed with examples of the dilution control methods applied in Outokumpu mines.

Jan 1, 1996

By Cunneen R. D, Murray A. M

Exploration in the vicinity of the abandoned Mt Coolon mine has shown that the shape and attitude of the quartz lode is controlled by the interaction between the lode and a converging syncline. Gold grades within the lode are enhanced along intersections with a welded ignimbrite, and decline rapidly where the lode intersects unwelded ignimbrite. Mineralogy and textures indicate the vein has an epithermal origin modified by a later intrusive event.

Jan 1, 1989

The success of any industry depends on the planned integration of the policies and resources of the key components of the Australian economic and political structure - government, industry management, education, research, and the human resources of the industry. The Australian Mineral Industry, like Australia itself, has grown and developed at a rate not foreseen by many of our founding fathers and early industry leaders. Hence, now, as we approach the 21st Century, we need to re-think our approach to the significant new problems that are beginning to face both government and the Mineral Industry. Government initiatives, government information and support services, industry re-structuring, and research and development support, need to be carefully re-evaluated, re-diredted,. and strengthened, so that government, the community, and the Mineral Industry produce and receive the optimum education and research strategies and services. The support of academics and researchers, the development of facilities, and the design of new Courses for the future successful and beneficial exploitation of minerals need particular consideration.

Jan 1, 1986

By Sauer P

The paper deals with the method of operat- ion, types of construction and sizing of screening machines as well as the selection of suitable screen decks. The application of novel screening mac- hines in hard coal preparation plants is explained in detail by way of examples.

Jan 1, 1984

By Bonsall EM, Schwabe MR, Hamlyn DA

Historically, most of the gold produced from Kalgoorlie has been derived from the gold and gold telluride Golden Mile lode systems dominantly hosted within the Golden Mile Doler-ite and to a lesser extent, Paringa Basalt. In more recent times the gold-quartz stockwork ore bodies within Unit 8 of the Golden Mile Dolerite at Mt Charlotte have become increasingly imp-ortant.Extensive low grade gold mineralisation has now been defined to the north and east of Kalgoorlie within rock units of the Golden Mile sequence not generally considered to be highly prospective.Two main types of mineralisation have been defined. The first comprises variably mineralised and altered quartz-albite porphyr-ies emplaced within talc-carbonated Hannans Lake Serpentinite (Mystery deposit). There is intense fuchsitic, pyritic and carbonate alter-ation of the serpentinite adjacent to the porphyry bodies. Gold mineralisation is assoc-iated with fine-grained disseminations and veinlets of pyrite and narrow quartz and quartz-tourmaline veining within the porphyry and adjacent fuchsite-carbonate rock. Several sets of vein directions are present, some of which typically exhibit sulphide alteration haloesnnA H] rhina_

Jan 1, 1984

The Boddington Gold Mine orebody is a large tonnage, low grade gold deposit located within the Archaean Saddleback greenstone belt within the south-western region of Western Australia. The orebody consists of laterite caprock (30 per cent) and clays (70 per cent) produced by lateritisation of felsic volcanics and intrusives. The caprock comprises gravel, hardcap and B-zone which have a specific gravity of 1.8, 2.4 and 1.8 respectively. The clay has a specific gravity of 1.5.

Jan 1, 1993

Thank you chairman, good afternoon ladies and gentlemen. In my talk this afternoon I intend to cover a brief history, some of the recent experiences and an overview of the McArthur River project.If we consider the themes of this forum, Obstacles and Opportunities, I can confidently say that in attempting to develop the McArthur River deposit Mount Isa Mines Limited (MIM) must have encountered almost every obstacle that can be imagined. However the large size and the high grade of the deposit has ensured an opportunity, from which it is very difficult to walk away from.The McArthur River Here's Your Chance (HYC) Deposit is located in the Northern Territory of Australia. It was discovered by Mount Isa Mines Limited geologists in 1955 and is one of the largest known sedimentary stratiform zinc-lead-silver deposits. The deposit has been the subject of numerous investigations and considerable expenditure culminating in a major feasibility study in 1979. There were a number of factors which prevented development, these being the size of the project, the fine grained mineralization, geographical location, market, social and capital cost. The latter had been estimated in the 1979 study to be $800 million at that time.

Jan 1, 1993

By Brinkmann J. R

In the narrow stopes of South African gold mines, rockbreaking is carried out by drilling and blasting with safety fuse and igniter cord being used as the initiation system. The fuse/gniter cord system is used primarily because of its low cost, however several limitations of this method include: inaccurate delay time, unreliable firing, inflexible application to varied configurations, and the absence of dynamic interaction between holes. Alternative initiation systems that incorporate millisecond timing are being developed to overcome the limitations of fuse(tgniter cord systems. Current investigations by the Stoping Technology Division of the Chamber of Mines Research Organization (COMRO) into the effects of millisecond initiation are being conducted at a deep test site. Experimental blasts using various millisecond delays and the independent firing of holes with fuse/igniter cord are being studied in order to quantify the influence of delay time on the blasting process and to identify the best methods of applying millisecond initiation systems. The effect of design variables such as delay time, hole firing pattern, stemming, and panel layout are discussed. Blast results including throw distance and direction, muckpile profile and rock cleaning times are used in the discussion of different combinations of blasting variables.

Jan 1, 1990

By McHaina D. M, Hardcastle S. G

A description is given of an investigation into the feasibility of using controlled recirculation of warm exhaust air into the cold intake air of underground mines during winter. Canadian mines can experience inlet air temperatures of minus 30 ¦C and less, requiring them to pre-heat their intake air. The use of controlled recirculation would reduce the inlet air quantity and thus reduce heating costs which exceed $1M on some mines.

Jan 1, 1988

By Burford B. D, Johnson N. W, Rohner P

Under design philosophy, the Hilton concentrator produced lead, zinc and LGM (lead plus zinc) concentrates. The LGM (Iow grade middling) concentrate was produced by combining coarse middling streams from the lead and zinc circuits, regrinding and subsequent flotation. Mineralogical examination of the zinc circuit middling stream prior to regrinding suggested that production of zinc concentrate from the zinc circuit middling stream should be possible by rearranging existing plant equipment. Laboratory testing of samples of plant products, however, showed that regrinding combined wi th the usual reagent suite was nO1 sufficient to produce a zinc concentrate of the required specifications.Examination of the process water highlighted a problem with dissolved salts in the circuit water, which was solved by in-circuit precipitation of the dissolved ions with soda ash. Implementation of the procedure in the concentrator effectively transferred to the zinc concentrate all sphalerite previously recovered to the LGM concentrate.

Jan 1, 1994

By Nevolina VG, Zakharova IB

The results of a study on the flotation of baddeleyite and associate minerals are presented, together with effective flotation reagents. Detailed microcrystallomorphological analysis of the benefication products were made to find out the features of distribution of different baddeleyite generations between froth and chamber products. To reveal the dynamics of interaction of technological properties of minerals with their morphology and constitution, a method of onthogenetic analysis was used. It is well known that the difference between technological properties of the particles of the same mineral depend greatly on its genesis, but also the relation is direct - by means of constitution (habit). Thus, flotation behaviour of minerals depends on morphology microinclusions, distribution of impurities, dislocations and physical properties of individual particles. The microrelief of baddeleyite grains and crystals from froth and chamber products was studied with an electron scanning microscope. Chemical composition was determined by means of laser, microprobe and chemical analyses. The difference between baddeleyite generations, their distribution in benefication products, and the effects of grain sizes, number of inclusions and chemical compositions were valuated. Conclusions on baddeleyite flotation properties were made. Mineralogical study on eudialite grains from rough ore and eudialite concentrate was carried out. The interrelation between eudialite and associate minerals and negative effect of aegirine on technological properties of eudialite were revealed as well.

Jan 1, 1993

By Beattie T. A

The ability of explosives to fragment rock has been assessed in small scale trials at the Granite Rock quarry, Baimsdale, Victoria. Three 65 mm diameter holes were fired simultaneously in a five metre bench, and the rock collected, screened and weighed. The mass of fines increased as the explosive strength increased in the series 30(10 ANFOPS

Jan 1, 1990