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In the first half of this century a mining industry was developed in Indonesia under Dutch colonial rule. World War II and the subsequent struggle for independence resulted in the destruction of most of the infras- tructure and much of the data. After independence, restrictions on for- eign investment and internal turmoil prevented re-establishment of a viable mining industry until the formation of the present Government after 1965 and the enactment of sound laws in 1967 to encourage foreign investment. Rebirth of the mining industry was followed initially by slow growth, but in the 1980's, spurred by the worldwide interest in gold, Indonesia has become the focus of an intense exploration boom for gold and other precious metals. 103 Contracts of Work for gold have been awarded since 1985 with Australian companies being the most predominant. Since 1985 three new gold operations have been commissioned and another two are nearing completion. Several more are undergoing feasi- bility studies. There is reason to predict that Indonesian gold produc- tion will grow to place the country in the ranks of significant producers during the 1990's.

Jan 1, 1988

By M Hino, D R. Swinbourne

The thermodynamic properties of arsenic in metal, speiss, matte, slag and gas phases are first summarised in this paper. Arsenic associates with sulphide minerals and generally has compounds of high volatility, but it has a weak affinity for sulphur and a strong affinity for metals, especially copper and iron. In the initial stage of the oxidation of sulphide concentrates arsenic is volatilised easily prior to the oxidation of FeS, although it tends to be fixed in the condensed phase as FeAsO4 if the concentrate is over-oxidised. Thermodynamic simulation of oxidative copper smelting reveals the distribution of arsenic between matte, slag and gas, and the possibility of condensation of arsenic from the resulting waste gas is discussed. In reductive smelting more arsenic remains in the metal or matte, and is sometimes concentrated as a separate speiss phase. The phase relations and thermodynamic properties of speiss are also summarised briefly. Arsenic refining from smelted copper metal is shown, from an examination of the basic principles of arsenic removal into slags, to be difficult. Owing to its weak affinity for lead however, arsenic refining from lead bullion is seen to be much easier.

Jan 1, 2000

The Perth Mint receives gold and silver from various sources for evaluation and refining. The metals are received in many forms and vary widely in assay. Refining is carried out using the Miller Process and the and the resulting market quality bullion is sold in a range of weights and alloys to suit the international bullion market and public demand. INTRODUCTION The Perth Mint was established in the late nineties as a branch of the Royal Mint, London, to refine the gold from the newly established gold- fields in Western Australia. The branch was opened for business in June, 1899. After refining, the bulk of the gold was used in the manufacture of sovereigns and half-sovereigns. Nowadays, although most of the gold received comes from the W.A. goldfields, some gold is deposited by producers in other states and in Papua-New Guinea, as well as scrap and trade wastes from manufacturing jewellers and old jewellery from the general public. Silver is deposited in the form of old silverware, recoveries from-photographic processes etc. Gold or silver may be lodged at the Mint in person, through a bank or other agency or by registered post. Telegraphic advice is usually given when gold is sent by the latter, so that insurance may be effected.

Jan 1, 1982

By Roberts JD

The design and installation of a major on-line stores and purchasing system, with built-in maintenance reporting and plant register capabilities, needs more than just close attention to computer design details. When the system must be available almost 24 hours a day to a number of mine stores sites, and is used by a variety of mining staff including engineers and stores clerks, as well as by remote purchasing and office staff, then simplicity of use, availability, fast response times, and other human factors become vital. Critical aspects include easy to use screen design, involving a change from the traditional hierarchical menu system, and fallback and recovery to the last transaction. Business, people and systems objectives need to be established at the preliminary design stage, so that results can be measured and corrective action taken. The amount and type of user involvement and training, at all stages from initial design to systems tuning, has a major effect on people wanting to use the system. Active user participation in systems design, data definition and collection, and use of relevant training material is needed. Project management and design problems can arise in working with database oriented computer staff, and certain design features are found useful in ensuring a responsive, robust overall system.

Jan 1, 1983

By T Tran, F Lucien

Supercritical fluids (SCFs) have gained recognition as solvents for the extraction of a wide range of organic materials. Their principle advantages over conventional organic solvents are that they possess much more favourable transport properties and that such properties can be easily altered by adjusting the system temperature and/or pressure. More recently, SCF solvents have been employed in the extraction of metal ions. The direct extraction of metal ions using SCFs such as CO2 is normally not possible due to the charge neutralisation requirement for solubilisation. However, extraction can be achieved with a SCF solvent containing an organic complexing agent as a cosolvent (Laintz et al, 1992; Laintz and Tachikawa, 1994; Dehghani, 1996). The role of the SCF is therefore similar to the role of a diluent in conventional liquid-liquid or solvent extraction processes. In this regard, SC-CO2 is a particularly good diluent since it exhibits good solubility for many organic complexing agents. The extraction of metals with SCF solvents has been examined mainly in the analysis of environmental samples and the treatment of metal contaminated wastes. Nonetheless, some interesting results have been reported recently on the extraction of rare earth metals, which highlight the potential of SCF solvents in mineral processing applications (Laintz and Tachikawa, 1994; Dehghani, 1996).

Jan 1, 2000

Study on Preparation and Gel Performance of High Purity Montmorillonite In order to research the colloidal and thixotropic performance of the inorganic gel prepared by high purity montmorillonite, this study uses the moderate grade bentonite ores from Weifang (China) as raw material. Two-stage hydrocyclone classification was applied to obtain the high purity montmorillonite with its content of 94.8 per cent. In contrast to other methods of montmorillonite purification, two-stage purification by hydroclone has the advantages of larger throughput and easily achieving auto-control in industry, and purified products with different montmorillonite content can be obtained by this method. And then the inorganic gel was prepared by the prepared high purity montmorillonite and its colloidal and thixotropic performances by measuring the flowability and thixotropy were further studies. Research results show that the inorganic gel has plastic body liquidity, the viscosity decreases with the increase of the shear rate, the static and dynamic shearing stress values are 33.98 Pa and 91.89 Pa, respectively, and the thixotropic value is 95.2 dyne+s/cm2, which indicates that it has preferable colloidal and thixotropic performance. Montmorillonite inorganic gel prepared by bentonite with high montmorillonite content and low-layer charge has better gel performance.

Sep 13, 2010

This paper discusses the significant land use changes that have occurred in the Latrobe Valley during 150 years of white occupation. The developments and changes were haphazard and made with little thought as to their setting or their environmental consequences. As a result many landscape and land management problems have not been addressed.This paper contends that the mistakes will continue unless an overall plan for the landscape of the area is developed and implemented. The concept of 'Greening the Valley' is introduced. It aims to provide focus for a comprehensive co-ordinated plan which caters for the need to restore the landscape and the need to provide for future land use. The plan will seek to draw on three major landscape features of the Latrobe Valley: the natural setting of the hills, rivers, valleys and forests; the agricultural land use including the forestry plantations; and the industrial complexes and urban areas.Rehabilitation of mining areas is a key element of the plan but must be put in a regional context and not be treated as an isolated function of a single organisation. A major challenge will be to integrate the worked out areas into useful and significant landscapes. The paper concludes by explaining the process that will be followed in an attempt to realise the concept.

Jan 1, 1992

THE following description of the surface plant of the Great Fitzroy Mines is to be understood as having been compiled by a mechanical engineer, who concerns himself more with the various appliances used, their correct construction to enable them to accomplish their prescribed work, and the production and transmission of the power required to operate them, than with the reasons for the physical and chemical processes which those appliances are called upon to assist in carrying out. Hence the metallurgist will not find herein more than the skeleton of the organism, which perhaps he would wish to be clothed with the detailed description of the substances undergoing treatment, in their various combinations, at all stages, and the results attained in separating the valuable constituents from the worthless. So, also, no details will be found of the methods employed by the management for. the purpose of determining by sampling and assaying the nature of the various products obtained.GENERALThe ore being worked at the Great Fitzroy Mine is divided into two classes :-1. Ore that requires concentration before smelting.2. Ore that can be smelted direct.Flow-sheet (Fig. 1) shows in outline the process of treatment to which ore of the first class is subjected, and the writer will endeavour to fill in that outline with some details of the appliances used.

Jan 1, 1911

By Leigh G, Gottleb G, Wilkie G

The estimation of particle liberation is important in the study of mineral concentration. With simple systems, where the densities of the components are low, the liberation can be studied directly by density fractionation. For most practical systems, and particularly for the dense, complex sulphides, the only method known is by measurement in polished section. There are two major difficulties with such measurements. Firstly, the measurements themselves are difficult and considerable care is needed before reproducible results can be achieved. Secondly, a well known stereological problem arises which gives the estimates an inherent bias. The paper discusses both aspects of the problem. The practical features of measurement are treated in detail and a method described which has been developed and proven to give reproducible estimates of the liberation in the section. This discussion relates to automated measurements by QEM*SEM and presents a way of estimating the confidence limits within which measurements lie. Comparisons are shown between measurements made by the traditional manual optical technique and automated equipment. Stereological reconstruction is also discussed briefly. Several methods have been presented in the literature but all are complex and none is yet widely accepted. Area measurements are less biased than linear estimates so a practical approach is to use area measurements in uncorrected form. The topic is still being actively researched so it is expected that one method will soon emerge as the standard technique.

Jan 1, 1993

By McCarthy J

In both the U.S.A. and Canada regulations concerning the reporting on mineral resources and especially ore reserves have been established. The regulations are virtually identical for the two countries with the main exceptions being who is franchised to write the report and how the various reserve categories may be used in reports to the public. Both countries divide ore reserves into "proven", "probable" and "inferred" categories. "Proven" reserves are those for material for which tonnage is computed from dimensions revealed in outcrops, trenches, underground workings or drill holes and for which the grade is composed from the results of adequate sampling. "Probable" reserves are those which are less well defined than "proven" while "inferred" reserves are generally those which may exist through geological and geophysical interpretation. The AusIMM/AMIC draft guidelines as proposed for use in Australia define more rigidly the ore reserve categories into "proved" and "probable" terms, which can only be applied following a full and favourable analysis of economic, mining, metallurgical, marketing and sociopolitical factors. If the ore reserves are not supported by this analysis they are placed into a "resource" category. Proper application of this proposed Australian model could prove useful when dealing with grass-root prospects or mining properties in the pre-feasibility stage. Combined with competent reporting, use of the proposed guidelines should ensure standardised and more verifiable analysis/valuation of a company's mineral assets.

Jan 1, 1987

By O Ostrovski

Iron ore reduction and iron cementation by CH4-H2-Ar gas was investigated in a laboratory isothermal fixed bed reactor. Iron ore was first reduced to metallic iron by hydrogen, then carburised to cementite by methane. Increasing temperature and hydrogen content accelerated the reduction process. Methane had almost no effect on the reduction process. Meanwhile, higher temperatures increased the rate of cementation and also the rate of free carbon deposition. The optimal temperature for cementite formation was found to be 750¦C. At this temperature, reduction of iron ore to cementite by gas containing 55 vol per cent hydrogen, 35 vol per cent methane and 10 vol per cent argon was completed in about 15 minutes. Addition of sulphur into the reducing/carburising gas strongly retarded the process of cementite formation and free carbon deposition. Cementite is an unstable phase which decomposes to iron and carbon. The rate of cementite decomposition increased with temperature up to 600¦C and above 750¦C . In the temperature range from 600¦C to 750¦C the rate of cementite decomposition decreased with temperature. Cementite was the most stable at 750¦C and least stable at 600¦C. The two-interface grain model was used to describe the process of iron ore reduction and the volume reaction model was employed to model the iron cementation process. The simulated results for both reduction and cementation are consistent with the experimental data.

Jan 1, 2000

Obvious differences in mineral deposit types occurring in Outer Melanesia and Northern Chile can be related to the sub- marine-dominated nature of volcanism in the' former area and the subaerial-dominated nature in the latter area. Subtle variations in subvolcanic epithermal-porphyry ore systems between the two areas probably result from differing ore fluid compositions. Hydrother- mal convection cells in Outer Melanesia will be seawater-dominated, consequently rela- tively high salinities and chlorine contents will characterise the ore solutions. Trans- portation of metals as chloride complexes is likely and the ease of seawater sulphate reduction to sulphide in the ore systems will lead to widespread, sparse dissemination of sulphide minerals. Relatively low grade por- phyry copper deposits will typify these ore systems. In Northern Chile hydrothermal convection cells will usually be dominated by meteoric waters. Consequently ore fluid salinities are likely to be lower and chlorine will be less abundant. Under these circum- stances transport of ore metals as bisulphide complexes could be important. Boiling and loss of H2S gas from these fluids would lead to rapid precipitation of metals and higher grade deposits. Erosion rate is a very important factor in the preservation of ore deposits and this may be the major control on the richness of a metallogenic province. The abundance of mineral deposits in the El Salvador region of Northern Chile compared to Fiji is probably a function of the much lower rates of erosion in the former area.

Jan 1, 1987

By E Werner, B R. Leavitt

The chemistry of acidic mine drainage discharging from flooded coal mines is commonly reported to improve with time after flooding. This investigation describes a 18-year dataset of post-flooding water chemistry for a below-drainage underground coal mine within the northern Pittsburgh coal basin (Pennsylvania, USA). The Montour mine is a 5650-hectare below-drainage coal mine of maximum 260 metres depth. Montour was closed in 1980 and flooded to within 38 metres of land surface within 4.8 years. Pumping averaging 210 L/s was then employed to maintain water levels at this elevation. The flooded proportion of the mine (by volume) at full flooding was 56 per cent. The shaft where water was pumped from Montour for water control is located about 70 per cent of the distance between the mine water table and the back of the mine ù that is, it is close to the back of the mine. The residence time (total water volume at flooding divided by pumping rate for control) is estimated at 5.6 years. Time series of chemical analyses show three phases of chemical behavior in post-flooding discharge. In Phase I (zero to two years after flooding), iron concentrations were high and reached their maximum (1100 mg/L). In Phase II (two to four years after flooding), a transition was begun to alkaline conditions, with decline in iron and other solutes. In Phase III (>4 years), net alkaline conditions began, with iron concentrations declining exponentially to 50 per cent of mined volume. This attainment of net alkalinity in this case may have also depended on abundant calcite in overburden extended up to 30 m above the mine floor.

Jan 1, 2003

By S Morrell, D Clark

æMine to MillÆ improvement involves optimising the chain of rock breakage processes from the in situ rock in the mine to the output of the concentrator. A growing number of paper studies and case histories from metalliferous mines (AusIMM, 1998; JKMRC, 1998; Clark and Scott, 2002) demonstrate that generating more breakage in the pit and the primary crusher can lead to benefits to milling that result in significant improvements to the economic performance of a mining project. However, unless the ævalueÆ of doing this (benefit over cost?) can be appropriately quantified, the approach cannot be effectively managed and the increases in blasting and monitoring costs cannot be justified.Mining operations have traditionally been organised into the separate departments of geology, mining and processing based on the specialist skills required and the different professional disciplines involved. Process optimisation across these boundaries has commonly been frustrated by management requirements to minimise the costs incurred by each department without adequate reference to the ævalueÆ being created. Companies have tended to discard positions that provide a technical over-view of the value chain, reducing the number of people with the opportunity to influence practices across these process boundaries.This paper discusses these issues and identifies measures required to quantify and manage the ævalueÆ provided by æMine to MillÆ improvement generated by the intense blasting of ore.

Jan 1, 2002

By Dixon D. R, Sparrow G. J

Pressure leach liquors from the pressure oxidation of a bulk flotation concentrate prepared from a complex Cu-Pb-Zn sulphide ore were treated to remove iron, either by pressure oxidation (the Hematite process) or with particles of magnetite (the Magnetite process), followed by cementation of various metals with zinc dust to obtain a purified solution from which zinc was electrowon. Satisfactory iron removal was achieved by both processes after neutralisation to pH 4.5 or 5.5. Pressure oxidation of the liquor at 200¦C and 690 kPa oxygen overpressure, conditions similar to those of the Hematite process used in the zinc industry, resulted in the precipitation of the iron as hematite. With the Magnetite process, an iron hydroxide was precipitated onto magnetite at atmospheric pressure and ambient temperature and removed by a magnetic separation step. The performances of both these processes for the removal of iron are compared. It is concluded that the Magnetite process offers considerable cost savings. Other impurities, in particular arsenic, were also removed with the iron in both processes. Cementation at pH 5.2 and 85-90 ¦C with 3.5 g/L zinc dust reduced the levels of copper, cadmium, and nickel to a satisfactory level and subsequent electrolysis in a laboratory cell gave an acceptable deposit of zinc.

Jan 1, 1989

The Archean Gossan Hill Group at Golden Grove, Western Australia, hosts two potentially economic volcanogenic massive sulphide deposits. The volcanic-sedimentary succession hosting this mineralisation is composed of a facies association which includes the products of rhyodacitic to,andesitic effusive volcanism, mass-flow sedimentation and concentrated hydrothermal fluid discharge, in a deep subaqueous setting. The Tertiary Kuroko deposits of Japan are widely compared to Archean volcanogenic massive sulphide deposits and a comparison of the facies associations hosting this style of mineralisation, in these two successions separated widely in time, allows a refinement of facies models suitable for exploration in ancient successions. The required deep subaqueous environment for the formation of volcanogenic massive sulphide deposits places constraints on the physical processes that can operate during accumulation of the host stratigraphy. Limitations on the operation of physical processes is reflected by the resultant facies association which can be used to characterize suitable volcanic-sedimentary successions in which volcanogenic massive sulphide mineralisation may be present. The facies association includes: (1) proximal effusive volcanic products - lavas and associated autoclastic breccias (2) distal volcanic products - mass-flow resedimented pyroclastic debris (3) background sedimentation - reworked volcanogenic and terrigenous mass-flow sediments and (4) chemical sediments - exhalites including cherts, sulphides and oxides, with perhaps various carbonates and sulphates. Primary pyroclastic deposits are not expected to be present, other than distal water-lain air-fall deposits, derived from shallow to emergent basin margin explosive volcanic centres, which also provide a source for the resedimented pyroclastic debris.

Jan 1, 1987

Of all of the processes in the mining cycle, blasting has the greatest impact on the efficiency of both mining itself and the initial stages of ore processing. The cost of blasting can be readily accounted for, but the true benefits of an effective blasting operation are seldom measured or reported. This means that blasting is seldom optimised in terms of its overall economic impact on an operation. Blasting operations have evolved according to the environment provided by mine management. Most operations seek to minimise the unit cost of each component process (overburden removal, blasting, excavation and transport, crushing or grinding) without recognising the impact that blasting performance has on subsequent activities. The creation of æcost centresÆ or æmanagement unitsÆ that isolate blasting from its downstream impacts reinforce this trend. Modern blasting technology is regarded as sophisticated by virtue of the mechanical design of the drills, the chemistry of the explosives and the flexibility and reliability of modern blast initiation systems. However, blast performance is controlled by the nature of the rock mass and there is generally an inadequate appreciation of how blast designs should be tailored to suit different rock mass conditions or to meet different blasting objectives. Most operations utilise a limited suite of standard designs without routinely tailoring designs to suit the actual conditions at hand or the objectives of each blast. Mining operations would benefit from tackling the following specific challenges:What is the appropriate target performance for blasting operations to generate the maximum economic benefit for the operation as a whole? How should designs be configured to suit the changing rock mass conditions and operating constraints? What compromise (if any) should be allowed from the ideal to assist conflicting scheduling or other operational requirements? How can blast performance be measured and reported to provide appropriate guidance to future operations? These challenges can be tackled through the process of æblast engineeringÆ. This paper discusses the potential impact of blasting performance on the economics of mining operations and the author argues that very considerable benefits over and above those currently being achieved could be realised by improving the routine engineering of mine blasts. The paper then explores how the industryÆs failure to recognise the economic importance of blasting has resulted in the engineering of blasting operations receiving less management and technical support than is appropriate. Finally, a simple approach to the engineering of routine blasting operations is described as an example of how these challenges can be tackled.

Jan 1, 1999

Exploration and mining title administration in the Northern Territory has changed dramatically over the last 20 years. These changes have occurred due to legislative amendments, technological developments, and the changing face of the mining industry. The first legislation to control mining in the Northern Territory was the Northern Territory Gold Mining Act (1873) of South Australia. In 1911, control of the Northern Territory was passed from South Australia to the Commonwealth. As a result of the mining boom which followed the discovery of gold in Tennant Creek in 1932, the Commonwealth passed the Mining Ordinance of 1939. This legislation was amended 39 times and stayed in force until July 1982, when the self-governing Northern Territory passed the Mining Act 1980. This Act is still in force and is continuously under review. The first computerised mining titles system, REGIS, was created in 1984/85 and was, to all intents and purposes, just a computerised index. Various modifications ensued, and in 1989 the Titles Database was unveiled. The database has developed to be one of the most sophisticated yet user-friendly mining titles databases in Australia. In excess of 50 companies have access to the database from their own offices. Work continues on its development and fine-tuning. The paper outlines the development of the database since inception.

Jan 1, 1994

By A B. Christie

In Northland, Coromandel, Taupo and Canterbury, weathering and hydrothermal alteration of Cenozoic volcanic rocks has resulted in the formation of various types of clay deposits. Subtropical weathering of rhyolite in the Matauri Bay area (Matauri and Mahimahi deposits) in Northland has formed high quality halloysite deposits. The Matauri Bay halloysite is mined and processed to produce reputedly æthe world's whitest clayÆ that commands a high price in niche ceramic markets. In the Coromandel, some argillic alteration zones contain kaolinite clays (at Hahei) and advanced argillic alteration zones contain kaolinite-gibbsite-pyrophyllite assemblages (at Pumpkin Hill and Lookout Rocks). In addition to known halloysite and kaolinite clay deposits, there is also economic potential for smectite clays produced by hydrothermal alteration of volcanic rocks. Bentonite (mainly ferriferous-beidellite) is mined from weathered basaltic ash in Miocene lake beds at Coalgate in Canterbury.   We have compiled interim mineral deposit profiles for bentonite in basaltic ash, halloysite in rhyolite, kaolinite in altered rhyolitic rocks, kaolinite-gibbsite-pyrophyllite clays in advanced argillic alteration zones and for smectite clays in argillic alteration zones. These deposit profiles include geological and mineralogical attributes, which are linked to the underlying volcanic, hydrothermal and weathering processes that have produced the clay minerals from their source volcanic rocks. Further work on refining the deposit profiles includes characterising the composition of selected deposits to determine spatial trends in mineralogy and geochemistry.

Jan 1, 2007

By H W. Scriba

The development and improvement of computer-based process simulation packages over the past 20 years has provided process engineers with a powerful tool to use in the design of complex metallurgical plants. The use of such modelling tools has enabled the design of process plants that minimise operating and capital costs whilst optimising plant efficiency and recovery. Almost every new project developed in the current market is underpinned by a simulation of the process. In line with engineering best practice this simulation should be based on laboratory/pilot plant test work results and sound assumptions. Any errors that are not identified in the development of the process simulation may have significant effects on the final design and operation of the processing plant. Developing a simulation of the process in a comprehensive, logical and auditable manner is thus essential in ensuring the simulation accurately represents the expected process plant behaviour. A methodology that ensures these requirements are met has been developed by SNC-Lavalin Australia and is described in this paper. The methodology includes the major review stages of data collection, model planning, model building and optimisation, model review, scenario testing and options development, and model reporting. All of these stages should incorporate comprehensive client interaction and review by a suitably qualified representative. In applying these methodologies SNC-Lavalin Australia ensures that the process simulation model developed can be confidently utilised in the design of the process plant, and in the estimation of operating and capital costs, whilst ensuring that engineering best practices are met.

Jan 1, 2008