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By Schmidt CG

Parameters affecting gold elution using the AARL process are reviewed and critically analyzed in an attempt to optimise metallurgical efficiency and minimise costs in both current and future carbon adsorption operations. Such factors as acid washing, column geometry, elution temperatures and pretreatment reagents are discussed together with eluant water quality and eluate flowrates. Hot acid washing of carbon prior to gold elution has many benefits. Besides improving elution efficiency when eluting with regional water, a hot acid treatment preheats the carbon without causing any gold leakage. Laboratory data indicated that hot acid washing reduces the mass loss of carbon during thermal regeneration. The eluate going to either zinc precipitation or electrowinning is also relatively free of troublesome impurities (organic contaminants and ferrocyanides in particular). Because of the chromatographic character of the AARL elution where an ionic strength gradient is used to inhibit the readsorption of gold, column geometry plays a significant role. While practical considerations and capital costs may restrain the length of the elution column, high length/diameter ratios are advocated in order to promote the plug flow of column eluate. From both a metallurgical and costing viewpoint, the two significant factors affect- ing the AARL gold elution are temperature and cyanide addition. High temperature and high reagent additions within prescribed limits will improve metallurgical efficiencies, but a balance between energy and reagent costs is required in order to minimise overall elution costs. As pretreatment reagents constitute a considerable portion of the total elution costs, both the addition and consumption of sodium cyanide must be carefully considered. Lower cyanide additions may be effective in certain instances, but the more practical use of 0,6 bed volume of a 2-3 per cent NaCN reagent containing 2 per cent NaOH is advocated. This is equivalent to an addition of 20-30 kg NaCN and 20 kg NaOH per ton carbon Treated.

Jan 1, 1986

By Wickham P, Raeburn M. R

The design and development of slurry sampling equipment for the Mount Isa Mines Limited on stream analysis installations is discussed in detail. Emphasis is given to the critical areas of slurry transport, screen design, pump selection, elimination of fast wearing components and maintenance reduction. Sample point design to fulfil the specific accuracy requirements for On Stream Analysis (3% to 10% relative) is discussed.

Jan 1, 1976

By Aziz N

The objective of the paper is to develop an understanding of the influence of caving on powered support rating by examining the geology and support performance at two sites which represent the current extremes in support rating, ie 6/240 Ton supports operating in the Hirst Seam at Solsgirth Colliery, Scotland, and 4/900 Tonne supports operating in the Bulli Seam, West Cliff Colliery, Australia. A conceptual model is introduced which considers the coal ahead of the face, the powered support, and the caved waste to be three yielding foundations which interact to control the subsidence of the roof strata. Different caving mechanisms are identified for the strata of the Hirst and Bulli Seams, ihese mechanisms being related to rock properties, ie to the palaeogeography and depositional conditions at each site, producing caved wastes with different yield characteristics. The results obtained for convergence and support reaction during production cycles at both sites are analysed to show the manner in which support reaction is developed, indicating the importance of high setting load densities in the Bulli Seam. Evaluation of the work done on the subsiding roof strata during typical production cycles by two of the yielding foundations, ie the powered support and the caved waste immediately behind the powered support, is used to further demonstrate the influence of caving mechanisms on support rating.

Jan 1, 1986

By Merry N, Cocks T

The mineral exploration industry is increasingly aware of the importance of the relationship between mineralogical data and geochemical assay results. However, until recently, the cost and time constraints of most techniques for analysing alteration mineralogy have precluded detailed alteration studies. These impediments have been reduced by the development of the Portable Infrared Mineral Analyser (PIMA), a field portable infrared spectrometer that allows rapid (in field) and cost effective analysis of alteration minerals including subtle variations in mineral crystallinity and Composition.

Jan 1, 1995

Traditional vat leaching has been done on a batch basis, which involves loading the vats, leaching, drainage, washing, draining again, and unloading. As a result of these many steps and the attendent cost of labor, vat leaching is generally not an economic proposition. Also, like heap leaching, there is a tendency for channeling to occur within the bed, whether the leach solution flow is by percolation upwards or downwards. No doubt experimenters over the decades have been enticed by the idea of fluidization induced by upward flow through the ore bed. If the bed could be fluidized, then a continuous flow of material could be set up, dispensing with the high cost of loading and unloading the vat. A quick calculation of solution flow requirements, however, soon reveals that the volume of constant liquid movement necessary to sustain fluidization is prohibitive from a power and cost standpoint. The premise of the Mackie Vat Leaching Jig (MVLT) concept was that the large volume of liquid flow required for fluidization could be achieved instantaneously, and that during this small element of time, the solids would flow under the influence of the hydraulic gradient in the vat. If this procedure could be repeated in a cyclic manner, then a steady-state condition could be set up. Experiments in the laboratory demonstrated that solids flow could be achieved in this manner.

Jan 1, 1991

By Russell F. M

Following the accident in the Peterson section of Mufulira mine in September, 1970, a method had to be found of extracting up to 300 000 tonnes of ore per month from this area without inducing caving. Sandfill mining methods were chosen, necessitating a plant capable of producing both cemented and uncemented fill on a large scale. The paper covers the design and construction of this sandplant which is thought to be unique for its size, as it incorporates three 3 000 tonne capacity settled storage silos, a 500 tonne capacity cement silo, mixing tanks and a control room situated underground. The plant is designed to handle an aver- age of 440 tonnes per hour with a maximum of 660 tonnes per hour for limited periods, delivering either uncemented fill or cemented fill in proportions varying from 1:6 to 1:30. The instrumentation and equipment necessary to give one man operation of the plant is described and the fill mining methods now in use at Mufulira are briefly outlined.

Jan 1, 1973

The Porgcra gold deposit is an epithermal gold base-metal deposit located in the Enga Province of Papua New Guinea. Gold-silver- spha le rite-galena-pyrite mineralization is related to stocks and dykes of dioritic composition which have intruded a series of folded marine sediments, mainly shales and siltstones, often with calcareous and carbon- aceous horizons, of middle Jurassic to middle Eocene age. The most intensely mineralized zone is at Waruwari Hill, where the mineralization occurs predominantly as massive mixed sulphide veins, and less frequently as quartz-chlorite veins and as disseminations. Mineralization occurs in all rock types and several phases of mineralization have been Recognized.

Jan 1, 1980

Results of investigations on adsorption and desorption of CO M CH and a mixture of the two gases are described.4 Results showed that even when the equilibrium conditions contains 50% Co and 50% CH4, the gas emission in the initia' stages will contain as much as 80% CH . 4 The temperature has a small effect and so also particle size for 1.4-11.2mm. The ratio of CO2/CH gases adsorbed in coal samples depends upon t4he equilibrium pressure and this ratio decreases with pressure. Results of field tests support laboratory studies.

Jan 1, 1988

By Richmond A

Like many industries the coal mining industry has, since the beginning of this century, undergone many changes. Technological advances and the increasing demand for fossil fuels have introduced new mining methods and techniques which allow the extraction of thicker and deeper coal seams at higher rates of production. Most new methods of mining (or for that matter any other processes) introduce problems which the engineers of the industry are expected to face and resolve. Unfortunately, spontaneous combustion has plagued the coal mining industry since the first attempts to mine coal, and is no doubt partly responsible for the reputation that coal mining is a hazardous industry. The financial loss and toll of human lives due to the occurrence of spontaneous combustion of coal in coal mines is enormous, if not incalculable. Its occurrence today is less likely to claim lives, due to both improved methods of working and in the detection of spontaneous combustion sites.

Jan 1, 1983

The approach to this subject is a very general one, but an attempt has been made to cover briefly a very wide field in the nationally important job of manufacturing iron for the iron and steel industry.Some historical data concerning the development of the furnace itself from early days have been followed by the modern ideas on raw materials and their beneficiation. Recent furnace design and modern auxiliaries have been given attention with, finally, some developments in practical operation.HISTORICALWhen dealing with such large 'and costly operating units as blast furnaces, there is not the same opportunity for research in design as in most other metallurgical processes. Over past generations the development of furnace design, or "lines" as it is usually termed, as well as most radical operating changes, has been very gradual.However, there have been some periods of rapid progress due to revolutionary changes. One such was the adoption of the steam engine for blowing and charging operations, and also, during this same era, about 1750, coke was first used as fuel in place of charcoal. Another revolutionary change came some 100 years later, when heating the blast became usual practice.Since then there have been great improvements in mechanical equipment and in the preparation of raw .materials. These factors, together with a better understanding of what happens inside the furnace, have led to the development of those large mechanically operated structures which are the most modern in blast furnace design.For many, years America has led the world in pig iron production and in furnace development, so that American design and practice is now recognised almost as standard. This type of furnace replaced the older stacks in England, Russia, Germany, South Africa and India, as well as here in Australia.

Jan 1, 1947

Most types of nuclear power reactors use uranium dioxide fuel. Power reactors using natural uranium dioxide'fuel are of special interest to countries such as Australia that have their own uranium supplies. A wide range of uranium dioxide powders can be fabricated and the ideal one flows readily, presses without the need for binders or lubricants, sinters to the required density and gives low reject rates at all fabrication stages. Sinterable uranium dioxide is usually produced via the ammonium diuranate route. The A.A.E.C. is aiming to demonstrate production of nuclear grade uranium dioxide from Australian concentrates, improving technology where possible. Details are given of the dissolution, solvent extraction, precipitation, filtration, drying, and calcination-reduction steps. Solvent extraction from sulphate media is also under study with a view to developing a process to produce a nuclear grade product at the mine treatment plant site,

Jan 1, 1969

The tankhouse of the electrolytic zinc plant at Nordenham is operating with a very high operating efficiency of 99 per cent. This has been achieved not only by strict control of the quality of the zinc sulphate cell feed solution but also by all the improvements in housekeeping in the tankhouse developed during the past years: aluminium cathode specification, cathode stripping cycle, edge strips, copper contacts, anode isolators, cell cleaning, fittings and washing devices. During 1987 to 1992 the casting department was completely remodelled in order to improve the quality of the zinc products, the safety of the operations and the flexibility. The remodelling includes the enlargement of the area for the casting shop, the storage buildings and the five casting lines on the same ground level. New lines for alloying products and for SHG25 kg zinc ingots have been constructed. The line for galvanising products has new equipment in some parts and the other lines have been modified.

Jan 1, 1993

Discontinuities often have a very detrimental effect on the stability of mine highwall faces. The west wall of the Muja open cut is remarkable for the number and variety of discontinuity sets which occur over a relatively small area. To-date 14 separate structural domains have been identified over an area measuring approximately 560 m by 120 m.The structural domains have been grouped into four structural assemblages on the basis of their angular relationships to each other and to regional folding and faulting. The distribution of these structural assemblages appears to be erratic and no controlling factors have been identified to explain or predict them other than in the most generalised terms.

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 Woodhouse M, Drew GJ, Andrews DL

The Honeymoon nickel sulphide deposits are located 45 km south of Wiluna in the 2.7 Ga old Agnew-Wiluna greenstone belt in the NE of the Yilgarn Craton (Figure 1). Both disseminated and massive nickel sulphide deposits are present within the deformed and metamorphosed Honeymoon Well ultramafic complex and are hosted by distinctly different komatiitic lithologies (Gole et al, 1996). The deposit styles and host rock lithologies reflect formation in markedly different volcanic settings. Metasomatism has affected parts of the ultramafic complex, including sections of the sulphide deposits, and has had a marked impact on mineralogy and bulk sulphide compositions. The present indicated resource is 158 Mt at 0.71 per cent Ni in four deposits (0.4 per cent Ni cut-off, resources above 300 m depth, December 1995). This includes a massive sulphide resource of 2.5 Mt at 3.36 per cent Ni.

Jan 1, 1996

By McCarthy P. L

A distinctive feature of the goldfields of Victoria was the extrac- tion of gold from deep leads, that is the buried river beds of Vic- toria's ancient rivers and streams. It is estimated that about 265,000 kg of gold was produced from Victoria's deep lead mines which comprises about 11.5% of Victoria's total production of gold (Bowen, 1974). The significance of deep lead mining for Victoria, however, went far beyond its economic contribution to Victoria. If Profes- sor Blainey is correct it was the frustrations of mining gold from deep alluvial leads in Ballarat during 1854 which precipitated the Eureka Stockade (Blainey, 1963, 46-52). This event resulted in the implementation of a fair mining administration and was an emphatic statement of the rise of democratic movements in Australia. Much of the technology and skill for mining deep leads had to be developed locally because at that time no other major gold- field elsewhere in Australia or the world had gold deposits with comparable problems. Deep lead mining in Victoria was there- fore largely a home grown industry and the equipment for that industry was often designed and produced in Victoria.

Jan 1, 1988

By Manca PP, Rossi G, Lipari D, Knissel W, Massacci G, Licheri P, Fioravanti E, Helms W, Lai S

Mining of the massive complex sulphides orebodies of Campo Pisano and San Benedetto (Southern Sardinia, Italy), dates back to before Christ, though their exploitation with modern technology was only resumed in the middle of the last century. The increasingly adverse economic conditions and the weakness of both country rock and mineralization were concurrent in forcing the Company's management to develop suitable high-productivity stoping methods. In the framework of a project fi- nanced in part by the Commission of the European Coranunities, and carried out in cooperation with the Universities of Cagliari (Italy) and Clausthal (Germany), a cemented backfill stoping method was developed. The concrete mix preparation and placement facil- ities, study of the cement mixes and endeavaa-s to optimize the methods are described. The monitoring system for measuring stress evolution within the emplaced backfill is illustrated together with the successful replacement of part of the Portland cement

Jan 1, 1992

By Swain H. D, Kay R. L

Assessment of mineral reserves in any ore- body hinges on both mineralisation characteris- tics and the economics of extraction. The mineral reserves statement depends on interpre- tation of diamond drill information by geolo- gists, determination of the production plan and operating costs by mining and metallurgical engineers and prediction of future income by economists. The techniques used to generate the mineral reserves statement for Bougainville Copper Limited in 1969 are described and the accuracy of predictions discussed. Preliminary results from a geostatistical reassessment are comp- ared with the ore zone model, blast hole data and concentrator reconciled production results.

Jan 1, 1979

SOME 70 miles south-east of the of Auckland lies the town of Waihi-the centre of the Waihi goldfield, at present the mining pride of New Zealand. That the glory of most mining camps is evanescent forms an axiom to which it may be expected Waihi will prove no exception. For the last fifteen years, however, Waihi has been an important gold-silver producer, with an annually increasing output, so that now the area ranks as one of the leading goldfields of the world.

Jan 1, 1911

By Bishop I, Toon S

To determine whether 130 felt earth tremors around Edwinstowe, Nottinghamshire U.M, which also experienced severe surface fissuring, were caused by coal extraction, a surface seismometer array was established around Thoresby Colliery. Over the next year, 785 microseismic events were detected. The spatio- temporal seismicity patterns are clearly associated with the commencement, continuing extraction and closure of faces. Of particular note are events which locate at the surface and appear to be related to the active fissuring. Events occur within days of commencement of production and cease when production finishes, with good correlation between face advance and hypocentral position. Naturally occurring microseismic events have also been detected up to 1 km ahead of active longwall faces in the Midlands using triaxial geophone packages grouted into the seam together with a surface seismometer in the top of the borehole. The quality of these data were very high and guided waves can clearly be seen with the dispersive characteristics associated with seam waves. In one experiment more than 2000 events were detected in only two days of monitoring even in a relatively noisy surface environment. This paper demonstrates how very accurate locations (5 10 metres) can be generated using three-component digital data from only one borehole. The surface seismometer and the borehole P-wave onset can give extra precision for the height of the event relative to the seam. The event distributions give a dynamic, three-dimensional image of the developing patterns of fracturing above, below and ahead of the longwall face with important implications for roof control, subsidence prediction and gas Migration.

Jan 1, 1992