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By Spark R. F

The copper deposits at Pernatty Lagoon are predominately djurleite-digenite bodies beneath the permanent water table, and chrysocolla-atacamite-malachite above the permanent water table. The minerals havebeen deposited as sheets, lobes, and pods in zones suggestive of permeability channels or permeability basius with respect to groundwater circulation.Pyrite is deposited in the form of framboids, which reflects its biogenic origin. Copper-iron sulphides deposit by replacement of pre-existent pyrite, and rarely by direct deposition. The latter mode of formation results in complex crustification bandings of chalcopyrite, bornite, sulphur rich bornites, digenite, and blue remaining covellites. The copper-iron sulphides appear to reequilibrate under constrained oxidation, resulting in an iron depletion and associated copper enrichment, the final product of which is a djurleite-digenite assemblage and associated with goethite. Where copper mineralization/ host rock relationships have rendered the rocks entirely impermeable to post ore groundwater movement, then the copper-iron sulphides are preserved as the ore assemblages.Minor and trace minerals observed include sphalerite, carrollite, galena, wittichenite, and possibly tetrahedrite in the primary ores. In the oxidized ores cllprite, tenorite, and trace brochantite have been found.

Jan 1, 1976

This paper deals with the Australian taxation laws, and in particular the income tax laws, as they apply to mineral exploration and development both in Australia and off-shore. The Australian tax laws are imposed principally at a Commonwealth level. The most important Commonwealth taxes are Income Tax, including Capital Gains Tax, Fringe Benefits Tax, Sales Tax, Customs Duty, Excise Duty and Bank Accounts Debits Tax. The States of Australia impose Stamp Duties and Financial Duties, Payroll Tax and Land Tax. The Australian Income Tax Law including Capital Gains Tax, is the most significant tax in the country. The principal features of the income tax law are as follows: tax is imposed on a taxable income being the assessable income less allowable deductions; a full imputation system of company tax applies; a foreign tax credit system applies to both companies and individuals; capital gains are taxed as income and subject to income tax rates but the gain is inflation adjusted. Australia has negotiated tax treaties with most of its trading partners based on the OECD model; and special tax concessions apply to the mining industry.

Jan 1, 1987

It is a pleasure for me to be able to address you today. My Chairman, Sir Eric Neal will not be able to be here until later in the morning and he has asked me to deliver this speech on his behalf.

Jan 1, 1990

It is argued that the capture of par- ticles by bubbles is primarily caused by hydrophobic ("structural") attraction forces. Neither dispersion forces nor double-layer forces can account for hydro- phobicity, though the latter are known to influence the kinetics of capture. The recent experiments of Israelachvili and Pashley (Nature, 300: 341-342, 1982) with hydrophobic mica plates provide the first measurements of the range and magni- tude of hydrophobic interaction forces.

Jan 1, 1984

By Troman L, Groutsch J. V

The Kwinana Nickel Refinery began operations in 1970 processing sulphide concentrates from Kambalda using the Sherritt Gordon pressure leach and hydrogen reduction process to produce nickel metal as powder and briquette. Over the years a number of changes have seen the refinery capacity increased from the original design capacity of 15 000 tpa nickel on an all concentrate feed to its current design capacity of 42 000 tpa nickel on an all matte feed. This paper outlines the changes in plant equipment and process for the most recent refinery expansion from 35 000 tpa to 42 000 tpa which have been implemented since 1992.

Jan 1, 1996

By M Vavro, V Slivka, J èterba

In the course of the last ten years the development of the mining industry in the Czech Republic has been influenced by the pushing through of economic and ecological criteria. Due to this coal mining was ended in the whole series of the underground coal mines. These mines become the source of ecological and safety risks û methane leakage, surface deformation, etc. The way of solving of these problems is by stowing of underground spaces, and also surface fault basins with the help of mixtures produced from industrial wastes. The presupposition of this procedure is knowledge of prescriptions for production of the mixtures, and of the economic advantageousness of carrying out these activities. This contribution pays attention to the utilisation of power-gypsum as a raw material in the production of mining-construction materials.

Jan 1, 2003

Comalco Aluminium Limited uses a computer system for cost, supply and maintenance reporting and control at its bauxite mine in Weipa, North Queensland. The system collects data on a daily basis at a high level of detail on both cost and maintenance history. This allows useful reporting to all levels of management from the shop floor to the General Manager. The most successful aspect of the system is that the information is available in all workshops on visual display units. This allows the real spenders of the Company's money, Foremen and Tradesmen, to make well informed decisions. The system has also decreased the time taken to find parts and information which gives the Foremana greater opportunity to do his real job of supervision and quality control.

Jan 1, 1983

An integrated approach to risk management to complement insurance is the sustainable way forward for the modem organisation. For risk management to work, its various aspects need to operate interactively, not in isolation from insurance. This is the approach recommended in this paper. The risk management process is a strategic method for reducing an organisation's total cost of risk. Well established and basic risk management techniques will help identify and achieve risk management Objectives.

Jan 1, 1994

This paper suggests the models for determination the optimum life of machines on the basis of sum and difference of investment and maintenance costs. The economic-mathematical models are based on complex percentage method taking into account the time factor of referring cost. The following strategies of maintenance policy have been considered in machines repair: a strategy without investment, a strategy with continuous investment and a strategy with step-like investment. The effect of value of investment in repairing and time interval of investment on optimum machine exploitation life has also been considered. An illustrative example is presented.

Jan 1, 2003

Traditionally mill operators have been employed with varying educational backgrounds with little if any formal training in aspects of mineral processing. Pasminco Mining-Rosebery, in line with other organisations, saw the need for a prerequisite entry level for operators to enter the industry. After initial discussions between various West Coast Mines personnel, union and government representatives, an industry working group was formed in 1989 with the aim of developing a traineeship suitable for the mineral processing industry. Training and technical representatives from four of the West Coast Mines and TAFE were commissioned with the curriculum development. The resultant course, which is recognised under the Australian Traineeship system, involved an integrated on and off-the-job training program, including 13 weeks of formal off-the-job instruction.

Jan 1, 1991

By Concha F, Sampaio R

In most of the literature, the hydrocyclone is viewed as a black box in which only global variables are present and where the equations are obtained by curve fitting. Recently some work has appeared where the Navier Stokes equations are solved numerically in the hydrocyclone geometry. However, in all of these works the air core surface, which has an important influence on the hydrocyclone dynamical behaviour, is modelled as being a cylindrical surface of fixed radius. In this work, we model the surface of the air core as a free-boundary which has to satisfy a jump condition, the Young-Laplace equation, relating the physics to the geometry. Based on this model, we are able to explain, qualitatively, some phenomena that have puzzled research workers in the field for many years, and can show, through the air core behaviour, the influence of material parameters on the performance of the hydrocyclone.

Jan 1, 1993

By Hughes A

Nchanga Division of ZCCM has installed and operated a trolley assist system on part of their truck fleet for some three years. This paper examines how the system came to be chosen and how the many features of construction and operation were dealt with. The economics and productivity of the system are presented as are the personnel aspects of acceptance and training. Zambia Consolidated Copper Mines is a state controlled copper mining company formed by the amalgamation of the former Nchanga Consolidated Copper Mines and Roan Copper Mines. The company operates seven copper mines the largest producer being the Nchanga division, which is scheduled to produce some forty-two percent of Zambia's copper production. The division operates four open pits and an underground mine which produce annually some 192 000 and 96 000 tonnes respectively of copper contained in ore.

Jan 1, 1986

In this paper the reactions which may lead to particle hydrophobicity/hydrophilicity as a function of grinding environment-are reviewed. The results of pulp chemical investigations related to a Cu-Pb-Zn ore on a pilot plant scale and laboratory tests with a Pb-Zn ore to evaluate the effect of some inhibitors on grinding/flotation are presented. The flotation recoveries of the ores treated by conventional and autogenous grinding methods show only a marginal difference and the results favour autogenous grinding. Iron originating from several sources manifests in the form of insoluble hydroxy complexes in the pulps. Such metal hydroxy complexes are hydrophilic and coat the mineral surfaces indiscriminately. On the other hand, selectivity is a problem for pulps ground by autogenous milling. Some corrosion inhibitors used in the laboratory grinding/flotation tests on a Pb-Zn ore showed maximum reduction in the wear of the grinding media ranging from 25 - 36 per cent, depending on the type and concentration of the inhibitor.

Jan 1, 1993

By A Saghafi, S Day

The control of spontaneous combustion in spoil piles is an area of concern for a number of open cut coal mines. Spontaneous combustion in spoil may occur when carbonaceous waste materials are exposed to air. In large piles, the relatively high voidage within the pile may allow sufficient movement of air through the pile to sustain oxidation and heat generation. Over the past decade, ACARP and CSIRO have funded a number of projects aimed at providing a better understanding of the causes of spontaneous combustion in spoil piles and the development of control strategies. Work has focused on prevention measures but has also considered measures available to deal with well-developed fires. Field, laboratory and numerical modelling methods have been brought to bear on the issues. Individual projects have addressed: causes of spontaneous combustion including the relative reactivities of mine waste materials; the use of cover layers to prevent spontaneous combustion; the use of flyash grout to control an active fire; the emissions of air pollutants; and the emission of greenhouse gases. This paper provides a description of the work carried out to date with an emphasis on the major findings of the research and its application to open cut mines.

Jan 1, 2005

In the years prior to the outbreak of war in 1939 Australia's production of copper had declined from a peak of about 80,000 tons in 1911-1915 to approximately 25,000 tons in 1939. This production met the need of the slowly growing national requirement and gave an excess for export. However, with the intensification of the war effort in 1942 due to the imminence of a Japanese invasion of this country, or at least a blockade of the sea lanes, it became necessary to expand production of armaments, and consequently the demand for copper increased beyond the capacity of the industry. Importation of copper to Australia during the period 1940-1944 was 131,000 tons.When exploration of the Mount Isa orebody was first being carried out in 1928, No. ID diamond drill disclosed the presence of some copper ore lying outside the limits of the Black Star orebody2, but it was not until 1941-1942 that the development of No. 7 level in the Black Star orebody enabled the existence of a lode of copper ore of economic grade to be established. At the request of the Commonwealth Government of the day a programme of development for copper production was undertaken whilst lead smelting was continued as before the war.A series of flotation tests on up to 1,500 tons of ore at a time, was undertaken and the concentrate so obtained was stockpiled. These tests were conducted, using one section of the lead mill, and demonstrated that a concentrate grade of 22-23% Cu with a recovery of 80-85% might be expected.These recovery figures were afterwards much improved, and 93-95%was obtained before the close of smelting in 1946.

Jan 1, 1953

By R Dunne, D Yan

In flotation where a bulk flotation concentrate is produced or a gangue sulfide such as pyrite contaminates a concentrate, residual collector has to be removed from the sulfide surfaces to allow selective separation in a subsequent flotation step. Depending on the sulfide mineral, the main species that needs to be removed when using a xanthate collector is either a metal xanthate or dixanthogen. For the identification of surface species, specific solvents may be used to remove each species û metal xanthates are known to be soluble in acetone whilst dixanthogens are known to be soluble in non-polar solvents such as diethyl ether. Xanthates break down with time, temperature and pH into various decomposition products. The major decomposition product is dixanthogen which can aid flotation but other products such as perxanthate and carbon disulfide can have an adverse effect on flotation. Various analytical techniques can be employed to monitor the formation of decomposition products on the surface of the mineral and in solution. The best of these is ultraviolet spectroscopy as it has diagnostic peaks for decomposition product determination. In this work two approaches were taken to understand the relationship between the flotation of a chalcopyrite and pyrite from an ore containing these two minerals. One approach was to remove the xanthate species with an organic solvent and then use ultraviolet spectroscopy to determine the concentration of dissolved species. The second method involved measuring xanthate decomposition in solution by measuring the residual xanthate concentration using ultraviolet spectroscopy. These experiments confirmed the species adsorb at the surface of the mineral and how these species affect the recovery and grade of the valuable mineral. In both cases pH and temperature were varied and two xanthate collectors (SEX and PAX) were used to study these relationships. These relationships could be applied to industrial flotation systems and allow for more accurate determination of optimal xanthate dosage and hence save on reagent costs.

Jan 1, 2005

As previously advised, two of the raw materials for Wilsons Portland Cement are cement rock and limestone, both of which are quarried by the company. We now wish to give you a brief outline of these operations. The major material, cement rock, is obtained for our Portland Quarry at Tikorangi Hill, which is one mile west of the Works and a familiar landmark to travellers on state Highway 1. The geological structure of this deposit is involved, having intensive and irregular earth movements interpreted as large scale slumps where older rocks overlay younger rocks - numerous folds, faults and overthrusts are clearly visible.

Jan 1, 1978

EARLY HISTORYIt is 91 years since the epic discovery of gold at the eastern end of Kalgoorlie's main street appropriately named Hannan's Street after the prospector who found the first gold here on17 June, 1893.The Spirit that motivated the early prospectors in their search for gold in this thirsty sun-burned land, unmapped, uncompromising and difficult is characteristic of gold prospectors the world over. Conditions have changed since then substituting comparative comfort for previous austerity and privation, but the quest-ing spirit, the everlasting optimism, the perseverance in the face of frustration .and disappointment still exists.It exists with the prospector who more often than not is a company geologist; it exists with the shareholder enjoying through his investment a vicarious participation in this wonderful, exciting industry and not the least with those people who have chosen the goldmining industry as their career.

Jan 1, 1984

A pilot pump rehabilitation programme commenced at Isa Mine in the late 1960ts. Over the years, it has now been developed into a full scale repair programme resulting in large operating cost savings. This paper will examine various materials used as wear media in the rehabilitation of pump parts for recycling, the use of other materials in manufactured design and appli- cations of these principles to other process Equipment.

Jan 1, 1978

The able address on the currency question given by the Right Honorable A. J. Balfour, M.P., late leader of the Government, at the Mansion House lately, before a large and influential audience, will strike a key-note that will resound throughout the world. It is high time that gentlemen of position and influence should come forward and express their views on this subject, so as to cause the matter to be,more seriously considered than it has been. The question can be no longer ignored or treated with indifference by bankers, financiers, merchants, miners, and others interested in the settlment on some basis the relative values gold and silver bear to each other. It is gratifying to not that such a great leader of political opinion as Mr. Balfour has given serious attention to this important question.The address created a deep impression ,on the minds of many who probably had not given the matter much att.ention, and Mr. Balfour's words will re-echo over a wide range of thought with such effect that I have no doubt they will materially help to check the downward tendency of the value and uses of silver. As a mining engineer, interested in the development of our mining resources for increasing gold aud silver for currency, and having devoted much attention to the subject, I cordially approve of the views set forth by Mr. Balfouf, and I think the general body of all interested in the production of gold and silver will do the same.