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By M Miettinen

That microorganisms, both living and dead, and products derived from the organisms, can function as flotation agents and flocculation agents is abundantly clear. They can modify the surfaces of minerals. They can function as flotation collectors and as flotation depressants and activators. In many cases they or their products can function as specific flocculation agents. Problems that must be solved before such microorganisms or products from the organisms can be used in commercial operations include culturing the organisms at a cheap cost and reduction in dosages required for various separations. These tasks are formidable. However, the concept of using such natural materials in place of various chemical reagents that may be toxic is very attractive. An attempt is made to show some of the promise of microorganisms in mineral bioprocessing and to consider the problems that must be overcome before commercial application of the technology is realised.

Jan 1, 2005

By Bell MG

At various decision points in the development of a project, a developer, joint venture partner or financial institution may require an independent review of the basic assumptions and technical aspects of the project. This type of review or technical audit is becoming a more common feature of the project development process. This feature has evolved because of the need of investors and lenders to be more confident of the viability of a project by the confirmation of its technical and cost aspects. Technical Audits offset some uncertainties introduced by the combination of longer development periods for, projects and the highly dynamic world economic scene. This paper reviews the place, nature and process of the technical audit by examining the circumstances when it might be needed, the typical scope of work or brief, the responsibilities of and relationship between the auditor and the client, and the auditing procedure. Detailed aspects of technical audits are discussed followed by a case study of the Hail Creek Coal Project Audit.

Jan 1, 1983

Oxy-ACETYLENE system of welding and cutting is at present practised in two forms, which may be described as the high and lowpressure systems. In the high-pressure system the two gases, oxygen and acetylene, are delivered. to the blow-pipe under pressure from properly constructed trade cylinders. Oxygen cylinders are in two sizes, each containing 100 and 200 cub. ft. of gas respectively. These cylinders are charged to a pressure of 120 atmospheres, or 1800 lb. per sq. in. approximately. The acetylene cylinders are made in one size as far as the writer knows, and contain 200 cub. ft. of acetylene gas at a pressure of 10 atmospheres. Each cylinder is provided with a valve and connection for attaching a regulator to "break down" the high pressure in the cylinders to the necessary low working pressure of the blow-pipes, and to deliver the two gases at a constant pressure irrespective of the variable pressures in the cylinders. These regulators can be adjusted down to as low as 1 lb. and are provided with two pressure gaugesone reading the contents of the cylinder in atmospheres, and the other the working pressure in lb. per sq. in. The high-pressure, or "two cylinder" system is compact and can readily be transported from place to place in the works. For this purpose the two cylinders are mounted on an easy-running 4-wheeled truck, which the operator and assistant find no difficulty in manipulating. In the low-pressure system the two gases are delivered to the blow-pipe, one from the oxygen cylinder and the other from the acetylene gas generating plant, which consists of the following:Generating cylinder, half filled with water, into which the cathoide is plunged. The generated gas is passed through a filter to the gasometer, then through a water washer on to the hydraullic seal...

Jan 1, 1922

By B Brattli

The dispersion pattern of heavy metals in soil and water is a consequence of complex geophysical and geochemical processes. Metal release from mining sites and subsequent migration occur primarily through acid mine drainage and erosion of waste and tailings dumps. Water plays a significant role in heavy metal mobilisation. Whilst it acts as a storage buffer for the pollutants, it is also the medium in which most of the reactions take place, and is undoubtedly the most significant transport vector in the pollution process. The intrinsic properties of the acidic drainage such as chemical composition, speciation of key mineral components, redox potential and pH are master variables controlling metal release, transport, deposition, reactivity and availability to biota. The mobility of heavy metals is strongly increased by acidification from acid mine drainage, and the discharge of these metals into the receiving waters results in numerous physical, chemical and biological responses in which the environment can affect the metal and vice versa. The result is an overwhelming number of association/dissociation, substitution, adsorption/desorption reactions, giving rise to a complex migration pattern. The attempt to understand and describe the dispersion pattern of heavy metals is complicated by the nature and level of interaction between the geochemical and hydrodynamic processes that generate and control the movement of the pollutants in the geosphere. Transport models which can be used to predict the behaviour of metal pollutants in a natural environment are still in the initial phases of development and their application to real life situations is limited. The Biochemical Cycle adds another dimension to the mobility of heavy metals. Metals form an important component of the food chain for man and plants. Biological uptake of metals from the bedrock and soil by organisms can result in migration paths very difficult to follow. Biodegradation or assimilation is just a tip of the iceberg.

Jan 1, 2003

By D Brennan, S Jahanshahi, F Jorgensen

The recycling of metals can be very efficient with careful selection of the material being recycled. The volume and value of recycled ferrous scrap has lead to the development of steel mini-mills which in turn has caused major changes to the steel industry. Although much smaller in volume, the recycling of lead is very significant, with battery recycling accounting for 60 per cent of annual world production. This high recycle rate can be attributed to the relatively uniform feed-stock from lead-acid batteries. The recycling rates of other metals are considerably lower due to longer use and non-uniform product usage that results in less efficient segregation and processing. It is clear that recycling of metals has advantages but its sustainability is uncertain. What are the key benefits of metal recycling? Metal recycling has technical, economic and social impacts. It is relatively easy to assess recycling on a technical basis, but the social impacts are harder to evaluate. This paper examines some of the issues in evaluating the sustainability of metal recycling.

Jan 1, 2002

The implementation of the Mining Further Amendment) Act, 1970, and later the Coal Mining Act, 1973, placed a requirement on the Department of Mines to accept an initiative in relation to coal exploration and coal mine development which does not apply in the case of other minerals. It is necessary to consider the exploration of the total coal resources of the State when considering exploration rather than one individual basin or deposit. If the level of knowledge of the coal resources in these basins is considered in relation to their potential for development it is possible to allocate broad scale priorities to their assessment. Due to the enormity of the task which involves a conservative estimate of in excess of 400 000 m of drilling to reach a broad reconnaissance level of understanding the involvement of industry with the Department in the exploration programme is necessary. The development of the coal deposits by mining operations must give consideration to a number of constraints apart from the simple availability of the resources. Principal among these are aspects

Jan 1, 1976

Alliance Gold Mines was established in the early part of 1994 to acquire the assets of Diamin Resources NL at Maldon, Victoria. These comprised Exploration Licence 3422, some 20 sq km in area and enclosing the main part of the Goldfield, and a CIP plant - with a nominal capacity of 250 000 tpa - which was commissioned in 1988. Between 1988 and 1992 Diamin had mined - by open pit methods - and milled around one million tonnes of low grade gold ore, and recovered 55 000 ounces of gold. By 1992 the known shallow resources had been depleted. Historical gold production from the Maldon field is about 1.75 million ounces, at the surprising average recovered grade of 28 g/t. The last significant mine closed in 1926: since then there has been no comprehensive exploration program, though Lone Star Exploration NL tested part of the field for shallow open-pittable resources in the 1970s and Carpentaria Exploration Company Pty Ltd carried out widely-spaced drilling on the three main reefs from 1979 to 1982. Diamin (1983 - 1994) commenced a careful compilation of old mine records and newspaper clippings, and drilled several cored holes.

Jan 1, 1996

By D Ryan

Following a long period of increase, there has been a reduction in exploration expenditure and activity in Australia over the past two years. During the post Second World War period, exploration was largely driven by mining companies seeking resources to satisfy an increase in world demand, while increasing their asset base as a result of mineral discoveries. In general, return on investment to shareholders was not the major driving force. With the exception of gold the mining industry has been faced with a long-term fall of metal prices in real terms. As a result the net profit return on average shareholderÆs funds in the Australian minerals industry has fallen from over 20 per cent in 1990 to less than five per cent today. Mining is now competing for funds with communication and finance based industries yielding high returns on shareholder investment. Shareholders and superannuation fund managers seeking a high return on short-term investments have indirectly reduced the funds available to the mining industry. Globalisation of the mining industry is leading to the rationalisation of the Australian mining industry as witnessed by mergers and acquisitions of local companies by foreign investors. The return on capital invested in the Australian mineral exploration industry must improve if the industry is to be competitive on a worldwide basis. Failure to achieve this will result in capital flowing overseas or to other industries. Relatively short-term upswings in metal prices which are generally driven by threats to the supply base (eg strikes, mine closures, increases in country risk) often lead to increased capital raisings for exploration funding. As a consequence of the time taken to raise the capital and increase exploration activity, measured exploration activity lags the metal price increases. There are also lags between commencement of exploration and discovery and ore production. In the case of gold exploration expenditure peaked six years after the price rise of 1980 Companies persevering with exploration in the current difficult period will be rewarded because they will be able to capitalise on future metal price rises and a minimised time lag.

Jan 1, 2000

By V S. T Ciminelli

This work aimed at evaluating the acid rock drainage (ARD) potential of five samples of a Brazilian gold sulfide mine in a decommissioning process. Three of the most traditional ARD prediction techniques, Standard Acid Base Accounting (Std ABA), Modified Acid Base Accounting (Modified ABA), as static methods, and humidity cells as a kinetic method were tested. Both the Std ABA and the Modified ABA results indicated an acid generation potential for some of the studied samples. In the other cases the results were inconclusive. The five samples were then submitted to humidity cell tests during 27 to 30 weeks. At the end of the period, the leachate pH was stabilised in a range from 3.4 - 4.1 (four samples) to 5 (one sample). The presence of relatively high levels of sulfate and dissolved metals was detected throughout the operation, specifically, Ni and Zn, and less frequently, As. These findings are discussed with the help of the samples mineralogy and Eh-pH diagrams. The results obtained in this investigation indicated potential environmental risks of this mining area. In this particular case, the kinetic tests were shown to be essential to the identification of the samples ARD potential.

Jan 1, 2003

This paper examines the operational characteristics and requirements of crushers and screens. Several possible control loops are considered and it is shown how these can be used to satisfy particular requirements.

Jan 1, 1978

THE following paper is a description of the plant and operations of the above company in their recovery and treatment of the quartz tailings deposited as final residues by the various mining companies. at Waihi, Karangahake, and Waitekauri into theOhinemuri River. During the past few years the silting of the Ohinemuri River has increased to such an extent as to cause considerable interest and discussion, and has lately been the subject of a most extensive inquiry by a Royal Commission, to consider the best means of dealing with what is generally spoken of as a public nuisance.Ever since the commencement of mining in this district, which was opened as a goldfield in 1875, the various mines operating have been discharging their tailings into this river, it having been proclaimed a sludge channel in 1895. Up to the year 1900 the quantity of quartz crushed was not large, probably not exceeding 500,000 tons; but since that date the annual tonnages discharged have increased enormously, and at the present time would total from 550,000 to 600,000 tons per year. Records show that up to the end of 1910 at least 5,000,000 tons have been crushed, for an actual yield of bullion considerably exceeding £10,000,000 in value, and all the valuable tailings from...

Jan 1, 1911

Blasting is at first sight a simple operation. Blastholes are drilled in a suitable pattern, primed, charged with explosives, stemmed and finally the blastholes are connected together to give the appro- priate initiation sequence. In practice the action of the explosive takes place in the interior of an opaque rock mass and only the external faces of the rock mass to be blasted can be easily observed. The mechanisms of blasting cannot be observed directly and must be inferred from observations of the free face and meas- urements of particle movement made by sensors grouted into holes in the rock. Explosives react very rapidly, in some microse- conds and any instrumentation of a blast must have an appro- priate response time. In many mines several rock types can be encountered during production. Several different methods of blasting may be necessary to cope with changes in rock types espe- cially if weak rocks are found in the final limits. This also makes it difficult to be sure of getting a large enough volume of rock to perform a series of reproducible experiments. While there appears to be agreement on the mechanism of blasting it is unlikely that a detailed understanding of how all the variables that can be encountered in practice affect blasting. The ease of assessment of the results of blasting depends on the criteria used. It is easy to isolate, measure and count over- size boulders. It is however difficult and costly to get a complete fragment size distribution. Methods used to assess blasting can vary significantly from site to site and the ways in which data are collected, presented and analysed will vary making compari- son of blasts at several locations very difficult. The definition of an optimum blast can also vary with the type of blasting. The muck-pile profile and fragmentation will be different for a dragline to that for a truck and shovel operation. In order to be able to assess blasting the mechanism has to be understood. Th rock and explosive properties considered rele- vant to blasting can then be determined. This paper discusses the generally accepted mechanism of blasting. The on-site observa- tions to assess blasting are-then listed. The mechanism of blast- ing can also be modelled and the use of modelling to optimize hlaetina ie thPn Aiernccarl

Jan 1, 1988

By Larsen E. R

We discuss the concept of optimal cut-off grade policies and their advantages in terms of maximisation of net present value of mining operations. There are indications, however, that such optimal policies are not widely used in the mining industry. In order to explore why this is the case we identify a number of stakeholders who may have diverging interests in the operating policies of a given mine. These various interests are mapped and a number of important relationships are explored in a large qualitative systems dyanmics model.

Jan 1, 1995

Mount Isa mine is the largest underground mine in Australia and is located 2,000 kilometres north-west of Brisbane. This mine has been in continuous operation since 1931 and in 1986/87 the silver/lead/zinc stream achieved the peak annual mining rate of 4.7 million tonnes. At present about fifteen different steeply dipping stratiform orebodies are being mined to maintain an annual production rate of around 3.0 million tonnes. Out of these, only two orebodies (2 & 5) are amenable to sub level open stoping (SLOS) type bulk mining methods. This year only 150,000 tonnes are scheduled from pillars and remnant areas but in future, more sources will be required to meet the budget production targets.

Jan 1, 1990

By R Willis, D Cooke, G J. Davidson

Mine-groundwater interaction at the Pasminco Rosebery Mine (PRM), western Tasmania, deserves special attention due to the unique climate and mining environment present. High rainfall and low evapotranspiration result in an excess of water, an uncommon problem at Australian sulfide bearing mines. Research is being undertaken to delineate current subsurface fluid flows and predict future fluid flows in order to improve management after mine closure. Acid mine drainage generation is well developed in abandoned mines throughout the area. If acid mine drainage is not controlled after mine closure, significant environmental degradation could occur in the receiving waters of the Pieman River system. The study area encompasses the heavily forested Mount Black, and underlying PRM workings. Groundwater flows beneath Mount Black through a crystalline fractured rock aquifer with faults and underground mine workings observed to act as the major hydraulic conduits. Recharge is controlled by local precipitation, and the ultimate discharge is thought to be the Pieman River system, which forms the topographic low in the area. Slug tests have been used in conjunction with the mineÆs extensive geotechnical database to spatially evaluate variation in hydraulic conductivity. In fractured rock terrain associated with mining, rock quality designation data can be a useful tool in delineating areas of similar hydraulic conductivity when combined with conventional hydrogeological methods. A GIS, mine planning software, an environmental and a geological database are linked to form the input for groundwater modelling.

Jan 1, 2003

By Barria J, Mencho J, Gonzalez GD

An extended Kalman Filter is used to build an on-line estimator of total ore, fine ore and water hold-ups in a SAG mill. In addition, an equivalent grinding rate from coarse to fine ore, as well as the discharge rates of solids (fines) and water are also estimated as part of the adaptation procedure of the model used for the Kalman Filter. The measurements used in the Kalman Filter estimator are the total mill weight provided by load cells, and inferred discharge flows of fines and water from flow and density measurements performed downstream. The net ore and water feed to the SAG mill are used as inputs to the estimator, and also the proportion of fine ore in the feed. As an example of how to introduce robustness in the estimation in the face of sensor bias errors, an estimation of the load cell bias error is introduced in the estimator, thus providing self calibration. The estimator presented in this paper has been tested by simulation using a detailed SAG mill mechanistic dynamic model comprising 27 size fractions well fitted to a pilot mill. The maximum error in the estimation of the operational variables - total and fine ore as well as the mill contents under different operating conditions - is about ten per cent.

Jan 1, 1993

By Firkin GR, Allen RJ

Sulphide Corporation Pty. Limited has roasted a number of different zinc sulphide concentrates on its sinter machine which pro- duces zinc-lead sinter for an Imperial Smelting Furnace, and results have varied widely. The differences are considered to be functions of !concentrate particle size and reactivity. Amdel have used differential thermal analysis to examine these concentrates and two major effects have been found. Firstly, in concentrates 1containing small quantities of pyrite and chal- L [copyrite, heat is liberated at 400¦C to 650¦C [by oxidation of these two sulphides. Secondly, as particle size decreases, heat release from the oxidation of zinc sulphide commences at flower temperatures and rate of heat release In a sinter bed, the presence of some rite and chalcopyrite would help to heat the cc sulphide to ignition temperature in a orter time, while a finer concentrate would sult in roasting being completed more ickly. Both of these effects result in a arper flame front and minimise the chance heat and combustion fronts being mismatched. is theory is supported by sintering results tained by Sulphide Corporation. As a result

Jan 1, 1975

By K Brown, J Webster-Brown

Coal mining activity first began on the West Coast in 1864 and has since led to the exposure of large areas of coal and host rock to chemical weathering. These exposed abandoned workings have led to the formation of acid mine drainage, which flows into selected rivers and streams impacting on the natural environment. A previous study conducted for the West Coast Regional Council identified four catchments receiving mine drainage which had elevated arsenic concentrations. The aim of this research is to expand on this initial study by determining the spatial distribution and attenuation of the arsenic within the sediment and water column in each stream of concern. Cannel Creek is influenced from drainage from the Bellevue coal mine adit and exhibits a low pH of ~3, elevated sulfate concentrations and high arsenic and iron concentrations in the sediments. This pattern is repeated in the Rapid Stream and Soldiers Creek catchments, which are also affected by adit inflows from the Sullivan and Blackball coal mines respectively. Soldiers Creek also has significantly high arsenic in the waters, with an accompanying pH of ~5.5. Snowy River exhibits a similar trait with a pH also of ~5.5, but with very low sulfate concentrations. Arsenic concentrations in the waters are consistently around 30 ppb, with sediment concentrations up to 900 ppm. These sediment values might be partially attributable to the operation of the Snowy battery gold ore production facility, but the consistently high As concentrations in the water column and in the sediment upstream of the battery have an as yet unconfirmed source.

Jan 1, 2002

A significant resource of uranium has been discovered within a buried palaeochannel located in the south western corner of the Officer Basin of Western Australia by PNC Exploration (Australia) Pty. Ltd. The mineral- isation is redox controlled and is hosted by Eocene organic rich paludal sediments. Prob- able insitu reserves are 13,000 t of contained uranium with an average ore grade of 0.12% at a cutoff grade of 0.03% U. The Mulga Rock palaeochannel has been traced for at least 100 km beneath the Quaternary surficial cover. The main channel is horseshoe shaped with the channel arms vary- ing from 5 to 15 km in width. The western arm connects to the Lake Raeside-Ponton Creek drainage system, whilst the eastern arm'is open to the south. The headwaters of the palaeo- channel are thought to have been the Lake Minigwal drainage system, prior to its capture by the Lake Rason system. Differential.erosion of the basement rocks during the Late Cretac- eous to Early Tertiary strongly influenced channel shape and resulted in the main channel being confined to a Permian,mudstone filled valley. Upwards of 100 m of fluviatile sediments accumulated within the palaeovalley during a period of subsidence in the Early Tertiary. Three broad stratigraphic units have been re- cognised within the channel: 1. An upper unit of fluviatile sands with interbedded lacustrine sediments, which have subsequently been wholly oxidised and variably silicified and ferruginised. 2. A middle unit of lacustrine to paludal sediments, which host the main mineral- isation. 3. A basal unit of fluviatile gravels and sand. The presence of excellently preserved Nothofagidites in organic rich paludal sediments from the middle unit, suggest that unit was laid down in a non-marine, fluviatile, humid environ- ment during the Middle Eocene.

Jan 1, 1988

By Plyley WF

Kidston Gold Mine is a 3.5 million tonnes per year operation located 280 kilometres west of Townsville, Queensland. Kidston's ore body consists of 44.3 million tonnes graded at 1.79 grams per tonne gold and 2.22 grams per tonne silver. Full production commenced in March, 1985. During the remainder of 1985, Kidston milled 3.77 million tonnes of ore and produced 213,614 ounces of gold.The ore is comprised of granodiorite, polymictic and volcanic breccias. The degree of oxidation of the rock influences the milling capacity and therefore determines the cut-off grade; ore is categorised as oxide, transition and fresh. The milling rates are 15,400, 12,000 and 9,600 tonnes per day for oxide, transition and fresh ore respectively.The ore is treated in a conventional cyanidation/ carbon-in-pulp plant (CIP). The plant consists of a primary crusher, semi-autogenous grinding (SAG) and ball mills, leach circuit and carbon-in-pulp circuit. Carbon stripping and dore smelting are done on site. The major difference between the Kidston plant and other Australian CIP plants is that a cyclone separation and washing circuit rejects half of the dry tonnage as a sand tail prior to CIP treatment. This difference allows the CIP circuit at Ki.dston to be smaller and makes the CIP less sensitive to the grind circuit product size.

Jan 1, 1986