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When lying over 200-250m depth, many seams and surrounding strata are gassy enough to create mining difficulties , particularly in highly productive longwalls as well as in their development headings. In addition to the gassiness of seams or stra- ta in the outgassing volume around working, the shape expansion and limits of this one influences much the intensity of gas emission. These charac- teristics of outgassing volume differ very much ac- cording to the permeabilities of the seams and strata encountered by their fracturation due to mi- ning. Moreover, the shape of the outgassing volume is very much modified by the rate of advance of the face. In nearly impermeable deposits, gas flows from a limited outgassing volume. When the rates of advance of a face are medium or low, the shape and dimensions of this volume do not change very much and outgassing volume is translated progressi- vely with the face advance. This explains why, in the past, it was observed that there was for each seam an average steady specific emission of gas, round which the volume of gas evolved per mined ton or per mined unit area, calculated over a cer- tain time, was oscillating. Combined with a statisti- cal irregularity coefficient, this allowed prediction gas of emission and thus to take decisions for air ventilation, drainage, and eventually production.

Jan 1, 1988

By Grader F. E

A linear motor properly wound can serve as a mechanism for separating paramagnetic sulphide minerals, like pyrrhotite, from other sulphides and associated gangue minerals. The effective- ness of separation depends on the energising current of the separator, the frequency of the a.c. cycle, and the particle size of the minerals. The speed of travel of the minerals over the surface of the separator is also a function of particle size, and appears to be constant. The movement of pyrrhotite, magnetite and iron filings of comparable size fraction (150um +74pm) on the linear motor surface has been observed using a cine camera. An attempt has been made to give a theoretical basis for the movement of the particles by calculating the minimum electrical energy required to move them. Further, the rate of decay of magnetic moment of the particles has been estimated for magnetite and it has been found that sufficient residual magnetism existed in the particles after they had been exposed to the first half of an a.c. cycle for them to have like polarity with the second half of the cycle. The particles are therefore repelled from the motor surface every second half of the cycle. This repulsion due to remanent magnetism is the probable cause of particle movement over the linear meter surf, e.

Jan 1, 1980

Gas dynamic phenomena, particularly instantaneous outbursts of coal and gas are problems experienced in gassy, highly stressed coal, both usually the result of depth. Diff- erent mining geometries present different opportunities for seam gas to escape, starting from the virgin condition unaffected by mining and ending with the mining of the coal. The mining of the coal varies from entering a virgin seam cross-measure, heading out into virgin seam, advancing longwall faces into virgin seam and extracting developed blocks from large longwall retreating blocks to small pillars. Each method has its particular gass- iness patterns and particular stress patterns, both changing to some extent with time, and changing as mining progresses. Geological structural anomalies are the cause of gas and stress anomalies, causing in turn greater gas and stress manifestations. Pre-drainage of gas from the working seam not only degasifies the coal but causes it to shrink and so may affect stress as well as gas patterns. Unfortunately prior degasification is not all benefit, and there are some d13- advantages to its use. Also although it is possible to degasify places ahead, gassiness will return if drainage holes are shut down or sealed up and other deleterious aspects may be induced. Research should continue into the problem of instantaneous outbursts of coal and Gas.

Jan 1, 1986

A thick sequence of alkaline intrusions and volcanic rocks underlies a Quaternary caldera on Liliir Island. The sequence is host to a still active sub-aerial hydrothermal system and associated epithermal gold mineralisation. Sub-horizontal alteration horizons exhibit progressively increasing chondrite norma-lised (La/Lu) en and (La/Sm) cn ratios from unaltered shoshonites, to the potassic alteration zone, to the argillic altera-tion zone to the advanced argillic alte-ration zone. The increasing fractionation of HEE, and especially of LHEE, up the alteration sequence is the result of de-creasing pH, temperature and alkalinity of the hydrothermal fluids with increa-sing alteration intensity. HRE3 were especially mobile in argillic and advanced argillic alteration units characterised by acid fluid conditions and large fluid volumes. Abundant Cl, S and CO2 within the hydrothermal fluids and thus abundant REE complexing agents and large fluid volumes favoured the mobility of REE during hydro-thermal alteration of the volcanic rocks and intrusions. Steam escape, mixing of the gases with groundwater and a change from a magmatic neutral chloride hydro-thermal system to a meteoric acid sulphate system was accompanied by liquid/vapour ratio changes, pronounced alkalinity, pH and temperature decreases, and fluid/rock ratio increases. This caused the mobili-sation, fractionation and deposition of PF.F.

Jan 1, 1990

The continuous casting of zinc alloys has been of fundamental importance for many years in the production of a number of products, including sheet for architectural applications, battery cans for dry cells and wire for metallising. The intrinsic benefits of continuous casting, including efficiency and high tonnage capability, uniformity of metallurgical structure and properties, and absence of voids and other defects, have contributed to the success of these products. Less well known, but of growing importance, is the more recent application of continuous casting technology to the production of zinc alloy bar stock products, including bearing stock, machining bar stock, forging stock and cathodic protection anodes. A wide range of zinc alloys are now continuously cast in a variety of cross sectional shapes and sizes to suit the diverse characteristics of these products. Of particular significance are the introduction of hollow zinc-aluminum bearing stock, and the availability of zinc alloy machining bar stock for hydraulic applications and for producing prototypes of zinc alloy pressure die castings. In addition to the traditional benefits, continuous casting provides special properties which are important in the application of these bar stock products. The list of successful applications of continuously cast zinc alloy bar stock is growing rapidly, and the market potential for resultant new zinc applications appears to be significant.

Jan 1, 1993

Published information on technical and market developments in the uses of zinc tends to dwell very largely on two groups of uses of zinc - zinc coatings (mainly galvanising) and zinc casting alloys. These two groups account for two-thirds of primary zinc consumption. However, if total zinc consumption is taken into consideration, coatings and casting account for a little over half the total. Either way, the health - or otherwise - of these 'other' uses of zinc can have a substantial effect on the industry as a whole. The aim of this paper is to put the whole market picture for zinc into better focus, concentrating on the factors which can affect consumption in the 'other half' of zinc's markets: ò brass - the third most important market for zinc at around one million tonnes - responds to changes in the economic cycle. It has seen substantial changes in the balance between different forms of semi products, and, in Europe at least, some real market gains; ò zinc sheet - one of the original uses of zinc in Europe - has grown substantially in some countries, but remains almost unknown elsewhere; and ò zinc pigments and compounds are so numerous that - barring the substitution of zinc oxide in rubber - major overall changes in the market are unlikely. The paper examines these markets and assesses their potential and implications for zinc markets as a whole.

Jan 1, 1993

By E Breese

The Grey River dredge is the first large scale alluvial operation to be permitted under the Mining Act 1971 and the Water and Soil Conservation Act 1967. The experience of Grey River Gold MiningLimited in pursuing these statutory approvals has identified weaknesses and strengths in the present system and problems which need to be resolved. The Company has learnt lessons, which if heeded, will assist future large scale alluvial mining projects.

Jan 1, 1989

By L Gladysiewicz

This paper deals with the current situation in the mining industry in Poland. An overview of typical transport systems working in the different branches of mining is provided. The transport systems currently used in lignite mining, particularly in the Belchat=w mine û the largest brown coal mine in Poland, and those operating in copper mines are described in detail. New designs of belt conveyors used in underground hard coal and copper mining are presented.

Jan 1, 2003

This paper introduces a new, safer bulk emulsion loading system for underground mining operations. The features and benefits of the equipment, along with the use of Dyno Nobel Inc patented gassed emulsion technology, is summarised in the application of a stope blast with very difficult and complex ground conditions. The paper describes methods used to optimise the amount of energy required to break the ore while protecting the integrity of the surrounding backfilled pillar.

Jan 1, 2004

The future of the United States (US) mining industry will be affected greatly by recent coal mining disasters. These have resulted in new legislation which will have an impact on mining economic costs as well safety and health of miners. This paper discusses the changes that new legislation and regulations are making to the industry and current research that is producing technologies to make mining safer and will likely impact the future of mining.

Jan 1, 2008

The restructuring of the minerals industry has created new challenges for the design and delivery of professional development, and difficult decisions for potential participants. New technologies offer some new methods of delivery, but fall short in providing all of the benefits of face-to-face participation. This paper is intended to be a catalyst for discussion of the issues involved in delivery and participation in cost-effective, relevant and timely professional development.

Jan 1, 2000

Evaluation of tyre chains has been taking place at King Island Scheelite for several years. Results indicate that tyre life has been greatly improved in all cases. Good cost sav- ings are resulting on small loaders. The worth of chains is difficult to prove on larger loaders under the conditions at King Island Scheelite. However, the dramatic decrease in the number of punctures has convinced the Company that chains are worthwhile on some larger loaders.

Jan 1, 1977

The title of my address today is "Oil and Gas Valuations - A Simplistic View of Some Critical Issues". Alternatively I could have called this address "Pitfalls for investors' and corporates in accessing Independent Experts Reports" 'as in this brief 12 minute talk I will briefly comment on some common misconceptions with regard to the valuation of exploration areas and production interests, and comment on how the draft release guidelines address these issues.

Jan 1, 1989

The (SA Mine at Cobar produces a mix of copper and copper lead and zinc ores fran long hole open stopes. Primary jaw crusher product is fed to two parallel primary autogenous mills followed by a secondary ball mill. Each mill operates in closed circuit with cyclones. Grinding equipment and the main operating variables are described. Copper lead and zinc flotation concentrates are produced sequentially. The control systems and operating strategies are described.

Jan 1, 1983

By Braes J. R, Neale J. R

The New Broken Hill Consolidated Limited (NBHC) mine currently produces 1.42 million tonnes of silver, lead and zinc ore annually. All of this ore is treated by the NBHC milling ccx[plex. This paper describes the crushing, grinding, flotation and filtration circuits used in the treatment of this ore and lists the major items of equignent used in these circuits. Metallurgical results, manning levels and consumption rates of reagents and grinding media are shown.

Jan 1, 1983

By Baoqi S, Zhengbing C, Wenguang L

A new flotation method is introduced for separating zircon from rutile and other Ti-bearing minerals at normal temperature, using a mixture of cationic and anionic collectors without any acid, alkali or fluoride as regulators. By combining the method with gravity concentration and magnetic separation to process the seabeach placer, the technological flowsheet can be simplified and the pollution of environment and the corrosion of acids, alkalis and fluorides on equipment can be removed.

Jan 1, 1993

Polarization phenomena associated with the use of an agitated bed of particles as an electrode for metal deposition were studied. The concentration polarization at this type of electrode is much smaller than that occurring at a fixed or moving electrode surface. Agitated particle electrodes can be used to electro-reduce copper from solutions over a wide range of concentration and at cur·rent densities up to 2000 AIsq. ft. of bed cross section.

Jan 1, 1971

This paper provides a financial perspective to the valuation of Australian resource companies and projects. Valuation exercises need, however, to be seen in the broader context of a thorough business appraisal, one that incorporates all disciplines employed in the resources industry. Fine tuning a discount rate or determining a particular capital structure is likely to be less important to valuation than an adequate understanding of industry dynamics and a company's likely performance in future years.

Jan 1, 1989

An increase in the silver to gold ratio with increase in depth in the main ore shoot of the Crown-Crescent lode in the Emperor gold mine, Fiji, was found to be due mainly to vertical zoning of gold-silver tellurides. The zoning resulted from a two-stage sequence of ore mineralization.The application of some recent studies of the synthetic Au-Ag-Te system to natural gold-silver telluride assemblages is discussed.

Jan 1, 1971

By Weatherhead J, Grounds J

The Nabarlek Uranium Project located in Arnhem Land in the Northern Territory of Australia was a small high-grade deposit which was the first uranium mine brought into operation following the extensive Commissioner Fox Inquiries into uranium mining during the late 1970s. The operation is almost complete and decommissioning plans have been prepared. This paper reviews all phases of the water management and tailings disposal for the project and compares results with design predictions.

Jan 1, 1988