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By Golubkov OL, Fedotov PB, Shkylar FR

One of the fundamental parameters of the race- way is its extent (a{ o), which has a significant effect on the distribution of gas and material flows in the lower region of the furnace. pp The known relationships for determination of aC o in most cases link the length of the raceway with the parameters of the blast, while the para- meters of the coke layer, in which the raceway is formed, are either ignored or else expressed in terms which are difficult to determine experimen- tally. Furthermore, the coke combustion propert- ies are not always taken into account in current blast furnace operating practice with combined blast. A complex dimensionless parameter, which re- flects the properties of the interacting media, is the ratio of the kinetic energy of the hot, com- bined gas stream to the potential energy of the coke flow, burning at the tuyere in a gas of known composition. Statistical processing of experimental data on the extent of the raceway zone, obtained from literature and our own work on operational furnac- es, has led to a working formula of the following Form:

Jan 1, 1981

By Moorrees C

Tests show how that temperature and rate of sparging to remove carbon dioxide determine the rate of precipitation and the chemical and physical properties of hydrated magnesium carbonates precipitated from clarified magnesium bicarbonate liquors derived from crude magnesia. At temperatures above 55°C the product is largely in the form ofhydromagnesite, Mg5(C03)4(OH)2.4H2O Between I5°C and 55°C the major product is nesquehonite, MgCO3·3H2O, although partial hydromagnesite precipitation can be induced by a high rate of aeration.As a result of the reduced time required to bring about greater than 95 per cent magnesium precipitation, the higher MgO content of the product, the ease of product recovery from the precipitation vessel, and the lower energy requirement for thermal decomposition of the precipitate to magnesia, it is preferable to precipitate hydromagnesite rather than nesquehonite. Moreover, the magnesia produced from hydromagnesite is somewhat more reactive than that formed from nesquehonite.Using precipitate calcination temperatures less than 1000°C, the chemical reactivities of the magnesias formed from both precipitates are greater than those of the crude magnesias derived from Savage River magnesite itself. The magnesias would be suitable for most uses developed for caustic-calcined magnesia. However, for refractory brick manufacture, it would be necessary to briquelle the caustic-calcined magnesia. adjust the CaO and SiO2 contents and sinter at temperatures in excess of 1600°C. This would bring about an increase in the bulk density and induce the appropriate chemical bonding reactions.Dead-burned magnesia produced from Savage River magnesite by the calcination/carbon dioxide route would have very low B2O3 contents, typically less than 0.0001 per cent.

Jan 1, 1985

By Siddall B

A brief review of the capabilities and practical limitations of blast simulation packages has been carried out. It is concluded that the simulators accurately reflect size distributions in the mid-ranges of 0.1 to 1.0 in, but are less reliable

Jan 1, 1998

By Brett D

Tailings disposal and water management are one of the most important environmental issues in mining projects. The nature and the method of disposal of the tailings will determine the long term environmental impacts and must be carefully considered at the planning stage so that final abandonment can be economically achieved. If not, long term and on-going treatment and amelioration may be required to achieve environmental standards. Final abandonment requires dam safety surveillance inspection to satisfy engineering stability and hazard requirements as well as environmental issues. Environmental issues include stability, as well as rehabilitation and long term contamination potential.

Jan 1, 1991

The major copper orebody at Mount Isa is being extracted at a rate of four million tonnes per year. The method used requires an equivalent rate of back filling with (mainly) cemented fill. There were three major incentives for developing this mining system. The first was the prospect of high ultimate recovery of the orebody. The target is 100% recovery. Also the proposed stoping layout appeared to offer significant advantages in development and production costs. Finally, extensive subsidence above the northern end of the orebody could have disturbed permanent surface installations and jeopardised a possible future open cut. The full implications of this ambitious strategy were not apparent in the early years. Now, after twelve years of production the benefits are being realised and they can be weighed against the costs. Probably the most interesting result which comes from this analysis is the significance of cutoff grades and dilution factors in balancing mining and filling rates.

Jan 1, 1980

By Sharma T

Laboratory investigations have been carried out on direct leaching of lead-zinc complex sulphide ore and zinc concentrate using ferric chloride. From the investigation it was observed that the use of 0.15 M and 2 M FeC13 gave an optimum dissolution of metal ions from ore and concentrate respectively. The kinetic studies conducted showed that the leaching reaction followed a shrinking core model for galena and sphalerite. The presence of impurities such as pyrite had increased the dissolution rate and reduced the consumption of ferric chloride. Further, the studies were conducted to recover dissolved zinc from the chloride solution by selectively precipitating it as zinc ammonium chloride.

Jan 1, 1992

By Tomlinson R. C

There are two main aspects of coal preparation to which the operational Research Executive of the National Coal Board has applied computer models. The first is in the planning of preparation plants and the first part of this paper discusses Simprep, a computer package that was designed to help on these calculations. The other is the development of control schemes to improve quality control, and the second part of the paper deals with the development of simulation techniques for this purpose.

Jan 1, 1977

By Watson K, Pollard D. M

The electrolytic recovery of metals from solution requires an understanding of the characteristics of the particular system employed, and the current efficiency and morphology of the deposit are influenced by such factors as cell design, metal ion and supporting ion concentration, acid concentration, temperature, impurity levels and cell design. The electrolytic deposition of both cadmium and silver present individual difficulties, and special cell designs are used for each of these metals. It was found that cadmium deposition was plate-like at lower cadmium concentrations, and at higher current densities. The presence of zinc in the electrolyte promoted nodular growth. Current efficiency remained high even at 50C in contrast to published information. Silver deposition morphology was relatively unaffected by changes in silver concentration, pH and current density. Current efficiency was reduced as temperature was increased.

Jan 1, 1989

The paper describes the geotechnical as- pects of design and construction of two 12 m diameter concrete lined tunnels from the start of design to completion of construction. Prob- lems occurred due to delay in supply of essen- tial rock support materials from overseas and alternative methods using locally available materials were developed. Several major rock- falls and rock movements occurred and remedial measures are outlined.

Jan 1, 1981

The preconcentration of uranium ore by radiometric ore sorting at Mary Kathleen Uranium Ltd. is described. The operation of the ore sorting machines is discussed in detail and performance results obtained with the existing system are presented.

Jan 1, 1978

By Nekitel S, Arumba J, Kopi G, Findlay RH

The Kainantu area lies within the composite Scrapland terrane which is composed of Mesozoic metamorphic and intrusive units, overlain by Cenozoic marine sediments, volcanic and intrus-ive units and Quaternary fluvial sedi-ments.Four deformations (Dl, D2, D3, D4) are recognised within the Mesozoic sequences, which consist of greenschist to amphibolite facies schist derived from felsic to intermediate pyroclastic rocks and pelitic sediments. The second, third and fourth fold events are present in the Cenozoic sequence, and these rocks are broken by thrusts related to northwest trending D3 folds. South-dipping, possibly lystric, normal faults are recognised and may be related to uplift and exposure of the metamorphic rocks as core complexes.Known mineralisation in the area consists of gold and copper skarn deposits, porphyry copper deposits, shear-hosted gold deposits, epithermal vein deposits and gold placer deposits. Over 35 hard rock and 18 gold placer deposits are known within the area. Of significance are the Kathnell shear-hosted auriferous quartz veins; such structurally controlled veins may be more widespread than proposed prev-iously and offer a new exploration target.

Jan 1, 1994

By Yan D. S

The removal of antimony from a refractory gold-bearing stibnite ore by roasting and selective chlorinating roasting was investigated. The influence of roasting temperature, roasting time, roasting atmosphere and type and amount of chlorinating agents on antimony removal were studied. The laboratory studies carried out included roasting tests of 4 g samples in a laboratory rotary kiln, followed by 400 g samples roasted in a fluidised bed. The test results revealed that antimony was efficiently removed by roasting at temperatures over 800¦C in a nitrogen atmosphere. The most efficient volatilisation of antimony was achieved with the addition of ferric chloride at temperatures between 350-600¦C.

Jan 1, 1995

By Johns AS

Comissioning of a new residue disposal tcluding upgraded classification for none backfill preparation, new variable speed pumps and a new residue dam took place in 1¦76. The system is described.

Jan 1, 1978

Pillar mining methods at the Pasminco Mining Broken Hill Operations are not new. Since mining commenced on Pasminco's leases at the turn of the century virtually every pillar extraction method tried throughout the world has been used. Much of the remaining mineral resource in the Pasminco Broken Hill leases is contained in pillars.However, due to the on-going need for mechanisation with bulk mining methods, and the very peculiar physical circumstances surrounding the formation of these pillars, their exploitation requires the development of a virtually new method based on excavation technology not previously used in the Australian mining industry. Trials of the method are to take place at the southern operations during 1991.

Jan 1, 1992

By Murakami T, Tamiya M, Mizokawa T, Matsumoto T

In the expansion program of the iron ore pelletizing plant at Kakogawa Works of Kobe Steel Ltd., an automatic computer control of products fineness on grinding department is practised. The main problem of the process control of a grinding system is scattering of measured fineness values of products. The scattering comes from the inherent nature of grinding systems, sampled powders and measuring systems. A method is developed to presume the exact status of the plant from scattering products (fineness values and to achieve a stable con trollability of the plant by utilizing the computer. An on-line fineness analyzer, an automatic sampling device and vari-speed air separators are also developed to compose the automatic grinding plant. This report introduces the fundamental epts and results of the automatic fineness rol system of the grinding plant.

Jan 1, 1977

The Peko copper orebody is associated with a body of magnetite rock which it has partly replaced. The primary ore averages about 9 per cent. copper and 4 dwt. gold per ton and locally IS much richer. It consists essentially of chalcopyrite and unreplaced magnetite, with lesser amounts of pyrite, marcasite, pyrrhotite, cobaltite, bismuthinite, native bismuth and native gold. The earliest formed mineral is wolfram, and the latest formed is goethite, so that the temperature of deposition ranged from about 5000 C. to 1650 C. or lower.Oxidation extends to 270 ft., which is 100 ft. below the present water level. The oxidized ore consists of cuprite and native copper, and has replaced more or less massive chalcocite of a former zone of secondary sulphide enrichment. The present zone of secondary sulphide enrichment extends from about 270 ft. to 310 ft. depth.INTRODUCTIONThe Peko mine is about 6 miles south-west of Tennant Creek township in the Northern Territory, adjacent to a small outcrop of hematite rock that projects above an otherwise featureless "bull-dust" fiat.The copper-gold orebody being developed in this mine did not outcrop. It was first detected in 1950 by a surface diamond-drill hole (DDH.1), which intersected primary copper ore at a depth of 400 to 425 ft. This ore contained from 4 to 11 per cent. copper and 1 to 25 dwt. gold per ton. Since then a shaft has been sunk, and crosscuts and development drives have been opened on the 210..ft., 300-ft. and 400-ft. levels, which are also connected by winzes. Two diamond drill holes sunk from the 400-ft. level have intersected theorebody at about 450 to 460 ft., and a winze from the 400-ft. level intersected the lode from 445 to 500 ft. At this point it is 54 ft. wide, and averages 9 per cent. copper. More recently an inclined surface drill hole (Peko No. 1) has cut the lode at 856 ft. to 921 ft., equivalent to a vertical depth...

Jan 1, 1955

By Gomm SA

The Mount Tom Price Concentrator, which contains a heavy medium cyclone plant for beneficiation of the -6+0.5mm fraction of low grade iron ore, is described. Testwork was carried out on an opportune basis over a period exceeding twelve months, to evaluate the separation performance of the heavy medium cyclones. Plastic density tracers were used and ore samples were taken and analysed. The effect of operating medium specific gravity (S.G.) on the separation parameters, the iron grade of the sinks product, and the mass and iron recoveries were investigated. Also examined were the differences in perform- ance between particles of different size. The implications of the findings for plant oper- ation are discussed.

Jan 1, 1987

By Trumpff H

Opencast Lignite Mining requires topwall strata of seams to be fully depleted and footwall aquifers sufficiently depressurized. To prevent a spread of the cone of depression into protected wetlands some distance away, alternatives had been investigated such as closing water works, underground slurry wall barriers and recharge by infiltration. As a result of these investigations, the infiltration method has been chosen and in a first phase during the next decade it will utilize as much as 55 x 106 m3/year. Using this approach, the survival of the wet lands is assured.

Jan 1, 1988

Draglines have been a significant part of world open cut mining since the early part of the 20th century particularly for the removal of overburden in the strip mining of coal. Since the mid-1960s draglines have played a major part in the large strip mining coal developments of Queensland and New South Wales.There are now over 60 large draglines operating in Australia ranging in size from 23 to 103 cubic metres bucket capacity, with digging depths to 60 metres, dumping heights to 50 metres and dumping radii to 100 metres. The application of these draglines has progressed through the uncovering of coal in shallow, single seam operations to deep multi-seam operations requiring a greater dependence on pre-stripping activities ahead of the dragline to remove overburden not able to be efficiently handled by the dragline.

Jan 1, 1992

By Forssberg KSE

The behaviour of cationic and anionic collector mixtures in the feldspar-quartz flotation system has been investigated througl conductivity, surface tension, zeta-potential and flotation studies. Tht results show the formation of molecular complexes between oppositel; charged collector ions through charge neutralisation. The molecular complexes are found to have a higher surface activity than the individua components. The mole ratio of the mixed composition is found to have, significant effect on flotation. Mole ratio less than unit} (anionic/cationic) of collector mixtures increases the flotation recoveries If the mole fraction of the anionic collector is greater than the moh fraction of cationic collector in a mixed composition, flotation ceases The flotation selectivity principally depends on the inherent differences it the surface charges of feldspar and quartz at the flotation pH values of

Jan 1, 1993