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This paper concerns a pragmatic approach to a problem that is common to many operations in the mining industry: how, over the short-term, to grasp the extent and distribution of long-term financial risk from environmental causes and reduce these risks strategically, in order to maintain stability and flexibility in the operations. Surprisingly, many companies operate without an environmental master plan or tools that can help managers measure and reduce financial risks. Such companies may be subject to unknown unacceptable financial risks from environmental causes. While many companies have some kind of internal system of environmental standards, it is often the case that such systems have uneven or limited effect, and offer no opportunities for visualising, measuring or managing aggregate financial risks from environmental causes. `Aggregate risks' are defined here as the calculated total expected financial costs to a company, or a subdivision of a company, from environmental causes at nominated operations over a defined time period. Aggregate risks take into account the type and magnitude of an environmental problem set, the likelihood of occurrence, and the time frame during which the problems will develop or solutions are required. For the large corporation, the 'amount of' aggregate environmental risk is a statistic that can be managed, along with other financial parameters, at the corporate level to improve the stability and predictability of operations, and protect the interests of shareholders. This paper concerns development of a management framework and a tool for the large corporation that responds to the need for managing aggregate environmental financial risks. The logical framework proposed to overcome the need for strategic vision is the Environmental Master Plan, and this is described in the next section. The analytical tool proposed to measure aggregate risks and provide relevant data and insights to managers, is called an Environmental Risk Management Information System, and its mechanics are described in a subsequent section.

Jan 1, 1994

A contract for three 20 ft diameter vertically mounted axial flow fans of the same aerodynamic design, was placed by Mount ]sa Mines Limited in 1963. The hydraulic blade pitch changing mechanism, the method of blade fabrication, and the roll out centre casings are features of these fans. Protection devices and fan control are designed for unattended operation and remote control. The erection and commissioning of the fans during 1964-65 is described.

Jan 1, 1967

Computer-based block modelling of orebodies is now used at Renison Tin mine for the estimation of ore reserves. It is considered that this has resulted in improved reserve estimation for complex 'stratafault' orebodies. The results for all orebody types are more easily understood by the mine planning section and provide greater scheduling capability than those from the previous manual isoline reserve estimation method. A structural overview of the deposit can be gained by combining geological block models for the various orebodies. It is anticipated that upon completion of block modelling for all the orebodies the time spent on the annual ore reserve estimate will be significantly reduced.

Jan 1, 1990

By Bourke J. H, Ashcroft T. B

Many changes have occurred in the world market for manganese over the last five years. Among these, the emergence of divided steel processes for the hot metal refining of pig iron is affecting the use of both ferruginous manganese ore and ferro manganese, at this stage particularly in the Japanese steel industry. Subsequent demand for higher quality manganese materials is promoting the use of thermally beneficiated products such as sinter. In addition, many processes are being developed for the direct smelting of fine manganese ores, of which plasma technology is the most advanced. Cost pressures and product quality requirements are encouraging pre- viously self sufficient countries such as The People's Republic of China and the USSR to import high grade manganese ores to supplement indigenous lower quality supplies. At the same time, Brazil has been provided with the impetus to convert its substantial reserves of ore to value added products.

Jan 1, 1988

By La Brooy S R, Fenton K

A low grade copper flotation tailing from Telfer containing 1.2% Cu as chalcocite and cuprite and 5 gt-t Au was leached with ammonia, cyanide and ammonia-cyanide mixtures to extract copper and/or gold. Direct cyanidation extracted both copper and gold but consumed about 30 kgt 1 NaCN. Pre-leaching the tailing with an aerated ammonia solution containing 28 kgt 1NH3 and 17 kgtl(NHa)2S0a at pH 10 readily extracted up to 95% Cu in about 6 hours under optimum conditions. However pH and total ammonia concentration were critical factors. Subsequent cyanidation ex- tracted 80% Au using 6 kgt NNaCN. Ammonia-cyanide mixtures werefound to selectively leach gold over copper depending on the concentration and relative proportion of NH3 and CN. The best composition for leaching up to 80% Au from Teller tailing was 1.6 kgt t NaCN and 1.1 kgf 1 NH3 in the presence of 0.3 kgt t Cue+. Such a mixture left only 50 mgL-1Cu in the final solution after precipitation of some of the initially dissolved copper.

Jan 1, 1991

By Ho E

Analyses of several nickel mattes from around the world show a significant variation in their copper content. Typically, matte contains an alloy, heazlewoodite and a copper sulphide phase. The various commercial methods of processing these mattes are reviewed and some of the fundamental factors which determine the choice of leaching system are discussed. Electrochemical studies on pure heazlewoodite and millerite in sulphate and chloride media are compared which show that nickel sulphides react via a series of nickel deficient sulphides and exhibit passivation as nickel is removed. Differences in the electrochemical behaviour of nickel sulphides in chloride media are attributed to greater crystallinity of sulphur and less formation of'NiS2. The electrochemistry of mattes differs because of the presence of alloy and copper. Copper in the matte modifies the potential for alloy dissolution and the rate of anodic dissolution of nickel. At elevated temperatures, Cu(II) in solution exchanges with NiS and completes the leaching of nickel at relatively low potentials without significant oxidation of sulphur to sulphate. It is concluded that there are fundamental advantages to leaching nickel matte in chloride media using Cu(II)/Clz as the oxidant.

Jan 1, 1996

By Smith Z, Huppert P, Charbucinski J

The paper describes a spectrometric method and apparatus developed for lithology logging in brown coal formations. The nuclear spectromet- ric technique developed is able to delineate coal/sand/clay seams. One requirement was to log inside drilling rods, as well as cased or open holes. The method described is based on combined natural gamma and gamma- gamma techniques using a spectrometric system for signal acquisition and subsequent computer based on-line data analysis and interpretation.

Jan 1, 1989

By Mathew P. J

The CSIRO Division of Mineral and Process Engineering in Melbourne has been developing on-stream analysis sensors based on neutron and gamma radiation for better control of quality and process operations. This has resulted in the development of Ironscan, an on-stream analyser that measures the iron content of both lump and fine iron ore on conveyor belts. It can be mounted under existing conveyors with minimal modifications to the conveyor structure and can cope with steel cables in the belt. An interface gauge and an on-stream coal ash analyser have also been developed, both based on measurement of natural radioactivity. The interface gauge monitors the interface between liquor and mud in thickeners and washers, provided the natural radioactivity of the mud is sufficiently high to detect it above background. The natural-gamma ash gauge is a valuable addition to the Coalscan range of ash gauges. It is applicable to heavily laden coal conveyors or bins where the coal bed thickness exceeds 30 cm, and also to lightly laden conveyors, provided the coal is profiled on the conveyor.

Jan 1, 1991

By Etheride MA

The evolution of economic precious metal and copper-gold deposits in high-level igneous terranes is dependent on very efficient fluid focussing. This is most readily achieved by contemporaneous deformation, igneous intrusion and hydrothermal activity. Mineralisation in these environments generally occurs in fault and fault-vein arrays developed in the cover sedimentary and volcanics sequences above older regional scale fault systems. Such reactivated fault systems an particularly prone to developing the complex fracture arrays, extreme local dilation and dramatic increases in permcahilit} that are necessary to efficiently focus hydrothermal fluid and produce large mineral deposits.

Jan 1, 1995

By Floyd JM, Bultitude-Paul J

The development of a process for the extraction of antimony from materials produced by Greenbushes Tin Limited has been carried out based on theoretical and laboratory studies. The materials treated have included concentrates of tantalite and cassiterite containing antimony at levels ranging from 0.3% to 2%. Roasting under controlled atmospheres is required to stabilise Sb203 rather than the low vapour pressure metal or higher oxide. Sulphidising additives such as pyrite, pyrrhotite or sulphur give enhanced antimony removal from tantalite and cassiterite at roasting temperatures of 900¦ to 1100¦C. Substantial elimination of antimony to levels of 0.1% or less was Achieved.

Jan 1, 1986

By Bedford D. J

The post pillar cut and fill stoping method has been adopted by King Island Scheelite for the extraction of the main Dolphin orebody. The orebody is a massive, tabular deposit varying from 10 to 50 metres in thickness, and dipping at approximately 30¦ towards and under the sea bed. The mining method was selected for 1. maintenance of hangingwall support under the sea bed; 2. maximisation of first stage ore extraction; 3. flexibility of mining, allowing maintenance of grade and selective mining around waste bands within the orebody, and 4. compatibility of existing equipment both with stoping and the on-going underground mine development programme. Stope parameters were established on the basis of initial rock stress analyses, and since the undercut phase of mining the stoping programme has been monitored with various types of deformation measuring devices installed in a series of large diameter boreholes.

Jan 1, 1977

Ore Reserves estimation for the two producing copper orebodies at Isa Mine, Mount Isa, Queensland is discussed. The principal estimation techniques used and discussed are first, a computer based inverse power distance weighted assay meshing technique, and second, a manual arithmetic averaging technique. The principles involved in these techniques are compared, and their areas of application indicated. A general comparison of the estimation of reserves with eventual production is presented.

Jan 1, 1979

By Freeman N

A microcomputer based control system has been developed and implemented at ZC Mines (now Pasminco Mining). The control system maximises throughput at a product size set point while maintaining a "safe" cyclone underflow and mill operating pulp density.To characterise mill and cyclone operation over a range of ore types, 60 circuit surveys were carried out by ZC Mines personnel over a period of four months. The data for each test were model fitted to check for data consistency and to accurately estimate circulating loads.The model fitted results were combined with instrument readings (including in-stream analysis probe assays) and the data checked for ability to predict key variables such as product size and underflow density from measurable inputs.In the resulting control scheme, panicle size and underflow density are not monitored directly, but are predicted by regression equation models based on directly measured variables. The tonnage control loop uses a dynamic model to maximise responsiveness.The system provides a data log output to an mM compatible personal computer at programmable intervals. Comparative data logging over a period demonstrates substantially smoothed circuit performance.The grinding control system was originally implemented using Fischer and Porter micro-DCI controllers. The program has also been implemented on a distributed control system using a sequence oriented programming language.

Jan 1, 1990

By Coombes J, Richards W. L

The objective of this paper is to illustrate, in a practical way, how both geologists and mining engineers can use conditional simulation to add value to their decisions. Inherent assumptions, requirements and essential components of condition

Jan 1, 1998

By Mousset-Jones P, McPherson M. J

Underground airways are characterized by irregular shape and uneven surfaces including large-scale natural roughness, fractures, and a super-imposed sand roughness. Swirls in the grooves of the wall and separation because of the periodic variation of the open cross sec- tion, due to the blasting patterns, make it almost impossible to calculate average con- vective heat transfer computationally on the bases of the geometrical description of the surface. However, dimensionless friction factors can be used to characterize the surface effect of an airway and an analogy between heat and momentum transfer can be applied to calcu- late an average convective heat transfer Coefficient.

Jan 1, 1988

The development of the Australasian Code for Reporting of Identified Mineral Resources and Ore Reserves is a significan step towards informing the financial community and the public about the future profitability and risks of investing in resource companies. The Code is also important from the accountants' point of view because it provides them with a well-defined bash for assigning costs or attributing value to the assets of resource companies and hence improving their financial reports. Although reporting to the public is ultimately the responsibility of management, accountants, like geologists, are frequently required to provide information for inclusion in these reports. Jr the last ten years, there has been a considerable refinement in the reporting of mineral resources which can be attributed mainly tc the progress made towards developing the Code. It seems tha the classification and terminology that the geologists have developed are widely used in the annual reports. However, little progress has been made by accountants in improving the financia information. The purpose of this paper is twofold: (a) to outline briefl) some of the major problems in accounting and reporting fo; mining companies and; (b) to examine the potential contribution of the Code in solving those problems.

Jan 1, 1990

A Kellogg type computer model of the slag fuming process is applied in reverse to derive some thermodynamic properties of components in lead blast furnace slag. At 1200¦C, the average activity coefficients calculated were 3.40 (S.D. 0.50) for ZnO referred to the pure solid; 0.657 (S.D. 0.022) for PbO referred to the pure liquid; for the ratios y 3.175 y (referred to the Feo.9450, Fe304 pure solids) 4.19 (S.D. 1.15), and for yCaS/ 1CaO (referred to the pure solids) 5.10 (S.D. 2.96). Statistical relationships were derived for these activity coefficients and ratios as functions of the composition of slag, which contained in molar percentages 1.9 - 12.6% ZnO, 19.8 - 24.9% Fe0.9450, 0.9 - 1.6% Fe304, 0.002 - 1.9% PbO, 16.1 - 18.6% CaO, 25.9 - 31.0% SiO2, 4.8 - 5.5% MnO, 9.2 - 10.3% A101.5, 1.2 - 1.4% CaS, and 5.1 - 9.6% "Mgo" (the balance).

Jan 1, 1980

By Menne D. M, Ladyman R

Camel Creek Mine operated by Lynch Mining Pty Ltd is located 65 km west of inghain and 160 kin north west of Townsville in North Queensland. (Figure 1). The Camel Creek gold mineralisation was discovered in mid-1987 in an area previously known for its tin workings. Mining commenced in January 1989 after an oxide reserve of 1.2 million tonnes @ 2.1 g/t gold had been delineated. The first gold pour was in May 1989. The mine developed into a medium sized open cut operation, with full site facilities. The initial mining rate was 500 000 tpa utilising run-of-mine (ROM) heap leaching to recover the gold. By the end of 1990 the wider orehodies were mined and efforts were focused on the narrow orebodies, of width typically less than three metres. Smaller earth moving equipment was employed to selectively mine the narrow orehodies leading to a decrease in the mining rate to 200 000 tpa. The Red Gold deposit (80 000 tonnes « 3.0 g/t to 18 in vertical) was mined in mid-1990 and ore was hauled approximately 8 kin to the Camel Creek heap leach operation. The ore was hauled in a dedicated campaign after being stockpiled. The cost of dedicated ore haulage ensured that only the more exceptional of the remote orebodies could be mined in this manner. The Golden Cup orebody, some 20 km from Camel Creek, was too distant to permit ore haulage. However, this prospect contained sufficient gold (initially 90 000 tonnes @ 3.0 g/t) to warrant the installation of a small mobile adsorption facility. Construction of the second heap leach operation commenced in late-1990. Gold production commenced in early April 1991. Mining of several smaller orebodies remote to the second heap leach facility has been undertaken and further mining is planned. This paper outlines heap leaching practice at Camel Creek Mine and summarises the success of the Golden Cup heap leach.

Jan 1, 1994

Alluvial gold exploration is aimed at recognizing areas of anomalous gold content as evidenced by the nature of the drainage system, its age, geomorphic history and other features of the geological environment including the provenances. Subsequent studies to quantify the findings are governed by the need for accurate data based upon precise measurements. Computerization allows the use of more complicated mathematical procedures than are feasible manually, thus promoting the development of more advanced technological aids. Data banks provide the means of storing vast quantities of information for instant recall.Sample representivity is a major problem and a clear understanding of both sampling and analytical requirements is essential for dealing with problems arising from variations in sample size and particle size distribution. Field samples must always be large enough to ensure adequate representivity or the sampling has failed in its purpose.

Jan 1, 1984

Since the announcement of early experimental work on rotating magnetic field (RMF) separation at the Sixth Mill OperatorsÆ Conference in 1997, the concept of RMF separation has been developed and tested further, and a range of separator designs is now being developed for the mineral processing industry. Shortened, but full diameter, prototypes of these designs are now available for test separations. The main advantage of RMF low and medium intensity attraction separation is the significant reduction in particle entrapment. This reduction is so significant that RMF separators are capable of operating very close to their theoretical limit for separator precision. This makes small laboratory RMF attraction separators ideal for low to medium intensity magnetic sample analysis, and larger separators ideal for applications requiring sharp magnetic susceptibility splits. Feedrates and separation rates are comparable to those of conventional attraction separators. Although RMF attraction separators are now well advanced in development, RMF rotation separation is still in the early experimental stage. The exception to this is the dry particle rotation eddy current separator that offers eddy current separation of small non-ferrous metallic particles from about 2 mm down to about 100 microns. Wet small particle eddy current separation is also possible, but has not yet been developed to a practical stage.

Jan 1, 2000