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The treatment meIhods selected for the concentrator at Cobar Mines Pty. Ltd. called for a high degree of automatic control of both the grinding and flotation sections.The resulting concentrator layout includes a central control room overlooking both grinding and flotation sections. The control room houses process recorders, controllers, and indicators. together with motor stopstart stations and alarms.Plant instrumentation includes load cells and variable speed hydraulic drive feeders for feed-rate control of autogenous mills, together with nuclear density gauges, differential flow transmitters, and pneumatic control valves for water and pulp density control.Flotation cell pulp levels are controlled by floats and pneumatic actuators; flotation reagent controls include magnetic flowmeters and time-operated solenoid valves.

Jan 1, 1969

TasmaniaÆs mineral endowment has resulted in 600 abandoned mines. Commonly occurring sulfide minerals such as pyrite and pyrrhotite can generate acid drainage and also mobilise heavy metals. Due to the StateÆs steep topography and high rainfall the risk to water quality in the receiving environments is significant. Surface waters impacted by abandoned mine sites typically showed high sulfate and metal distribution at pH range of 2.0 to 5.0. The impacted waters generally showed metal distribution in the high acid/extreme metal to low acid/low metal range. A similar trend was shown by sulfate distribution. Elevated levels of metals and sulfate downstream from several abandoned mine sites indicated that active sulfide oxidation is occurring and these sites may be potential point sources of metal pollution in the receiving environment. High correlation between metal and sulfate distribution suggests that sulfate distribution in surface waters may be used as a cost-effective investigation tool for preliminary assessment of acid drainage.

Jan 1, 2003

By R Dimitrakopoulos

Optimisation and mathematical formulations for open pit design and long-term production scheduling have been available since the 1960s. There are two main concerns in the application of existing mixed integer programming (MIP) models in open pit mines: a. the feasibility of generating both optimal solutions and practically mineable scheduling patterns and b. the inability to deal with in situ variability in orebodies and account for uncertainty. In dealing with these issues, a general open pit production scheduling method for multi-element deposits is presented and subsequently used to optimise the long-term production schedule in a nickel laterite deposit. The application shows the weaknesses of MIP formulations in terms of generating optimal solutions as well as practically feasible mining patterns. The application of the same formulation in the presence of in situ orebody variability and uncertainty uncovers a major reason for deviations of scheduled production from actual production, and outlines additional limits of traditional optimisation formulations as well as future needs.

Jan 1, 2003

By Williams DJ, Battino S

The rapid crushing technique for the measurement of gas content of coal consists of accelerating the rate of gas desorption from coal by crushing. This technique allows the determination of gas content in the space of hours rather than days or weeks as required for the traditional slow desorption technique. The crushing technique is used particularly when gas content determinations are urgently required for mine safety purposes. The method is now routinely used in underground coal mines of NSW and to a lesser extent in QLD. Despite the rapidity and efficiency of this method, concerns have been raised upon the reliability of the method to deliver accurate results. Experience in Australia has shown that there is in fact some discrepancy in results between gas laboratories using the rapid crush technique. The development of rapid crushing techniques for seam gas content measurements in Australia and the main causes of variability in the gas content test results were investigated. The gas laboratories participating in the gas content testing were CSIRO Division of Coal and Energy, BHP Technical Services and GeoGas Pty. Ltd.

Jan 1, 1998

By Newman D, Wyslouzil DM

Different conventional and non-conventional flowsheet configurations were examined for the treatment of a number of refractory lead-zinc and copper-lead-zinc ores containing carbonaceous pyrite, flotable non sulphide gangue and pre-activated zinc. The flowsheet configuration for the processing of complex massive sulphide ores has a remarkable effect on the overall metallurgical results. Conventional sequential flowsheets, with circulation of intermediate products for both lead-zinc and copper-lead-zinc ores, gave poor metallurgical results and often saleable concentrates were difficult to produce. The concept of semi-bulk flotation and double bulk flotation with coarser grinding of the ore, followed by single or double-stage regrinding and sequential flotation was established to be most effective in achieving optimum metallurgical results. This flowsheet design gave superior results as compared to the conventional sequential flowsheet, and resulted in a lower reagent consumption, a significant reduction in the circulation load of intermediate products, and improvement in the rate of flotation of valuable minerals. Thus, optimum flotation conditions were provided for different products within the flowsheet.

Jan 1, 1993

The medical evaluation of the health effects of dust exposure in the mining industry should be based on the premise that the results of the medical examinations will be considered in relation to the previous history of exposure to dust.(l) To this end the Mines Regulation Act and the Regulations under that Act in West- ern Australia provide for: the prime responsibility for dust sampling to rest with the mining companies; the appointment of a Ventilation officer by each mine and the sampling and record- ing by him of dust and toxic gases in work places at three monthly intervals, or more frequently as required; the appointment of a Mines Medical Officer who shall make provision for the medical examination of persons and the prevention of occupational diseases; the appointment of a Ventilation Board, consisting of the State Mining Engineer, the Senior Inspector of Mines for the State, an Inspector of Mines having specialised training in ventilation tech- nology, a medical practitioner having specialised experience in occupational health problems relevant to the mining industry, and a Scientific Officer having duties under the provisions of the Clean Air Act, 1964;

Jan 1, 1979

By N J. Beukes, J Gutzmer, C Reinke, M Bau

In this study the light sparse phase search (SPL_Lt) mode on the Mineral Liberation Analyser (MLA) was successfully used to identify and quantify the abundance of rare earth element (REE) phosphates in Precambrian iron formations. Monazite (light REE phosphate) and xenotime (Y and heavy REE phosphate) are identified and data from the MLA combined with the mineral chemistry of the two minerals are used to calculate and model the expected REE concentration and distribution in these two REE phosphates. The REE phosphates account for up to 31 per cent of the REEs in the banded iron formations (BIFs) and excellent correspondence is observed between the modelled REE patterns and the whole rock geochemical data available for the same samples. Except for quantifying the mineral weights, the sparse phase search also allows for the localisation of REE phosphate grains and the observation of their association with other minerals using backscatter electron (BSE) imaging. These observations are used to conclude that the REE phosphates were most likely of diagenetic origin, with REEs and phosphate remobilised from primary chemical precipitates. It is demonstrated that automated mineralogical techniques can be used to qualitatively and quantitatively describe the influence of a rockÆs trace mineralogy on its geochemistry.

Jan 1, 2008

During the past decade geopolymer technology has emerged as a possible solution for the effective stabilisation and solidification of waste materials. Amorphous to semi-crystalline geopolymers form by the co-polymerisation of individual alumino and silicate species, which originate from the dissolution of silicon and aluminium containing source materials at a high pH in the presence of soluble alkali metal silicates. It has been shown previously that geopolymerisation can transform a wide range of waste alumino-silicate materials such as fly ash and blast furnace slag into building and mining products with excellent chemical and physical properties, including high compressive strength as well as fire and acid resistance. These chemical and physical properties suggest that geopolymeric matrices derived from waste materials are well suited for environmental and other applications such as the encapsulation of mine tails, the immobilisation of heavy metals and also the fabrication of structural products. The current challenge is to demonstrate that a wide variety of natural Al-Si minerals could serve as potential source materials for the synthesis of geopolymers. Moreover, it should be shown on a large commercial scale that it is possible to encapsulate waste materials into the geopolymeric structure without compromising the chemical and physical properties of the final product for the desired application.

Jan 1, 2000

Natural leaching of minerals has been recorded for some two millenia but surprisingly only in recent years has enough been known of the process for any serious design to be made. Copper has been recovered from natural mine waters since about the 17th century but again little progress was made in de- sign procedures until recently. Natural or dump leaching was started as a recovery process late in the 19th century and in the years up to the classic study of Taylor and Whelan in 1943 a series of impirical optimis- ations made it a valuable process for treating low grade or waste material. The biological nature of Sulphide leaching was proven by Colmer and Hinkle in 1947 and since then a large mass of data has accumulated on the microbiology, biochemistry, and response of ores to this form of attack. In spite of this knowledge and the vast amount of pract- ical experience available there are few recorded attempts to present methods of calculation or design procedures that can be used for setting up a leaching process. A framework is given here on which such procedures can be based and indications given of the inherent advantages and limitations of the process,

Jan 1, 1969

By Q Qian, M Karakus, J Wang, N Melkoumian, D Goodchild, Q Sui, C Wang

Probabilistic analysis is widely used in slope stability assessment because of its capability to take into account uncertainties associated with geotechnical parameters. There are, however, still many unresolved practical issues to the application of the method. One of these issues is the integration of assessments when multiple sets of fractures are considered for the entire slope. In the present study, this issue is addressed within the framework of Monte Carlo simulation. Probability of failure for pairs of fracture sets are assessed independently and the final assessment of the probability of failure for the entire slope is done using conditional probabilities. Prominent Hill open pit, in particular, the problematic fresh Bulldog shale formation, was used as a case study to test the method proposed. The SWEDGE program of the RocScience software package was used for the analysis.

Sep 26, 2011

By J Szymanski, Y Hu

Excavation engineering involves complex processes for primary and secondary extraction of materials. The shovel excavators bear varying mechanical energy input and stress loading across the working bench during excavation. These varying mechanical energy input and stress loading effects cause significant wear and tear and fatigue failure in equipment components. These effects further result in unplanned downtimes, reduced efficiency and high production costs. In addition, the mechanical and electrical control systems must be operated in efficient profiles to generate maximum outputs and efficiency from these excavators. Efficient technologies are therefore required to solve these problems in order to reduce production costs and increase efficiency. In this paper, the authors develop a rigorous simulator for a hydraulic shovel in a surface mining environment. The finite element model is used to capture the stress profile within the shovel components during excavation, such as, the bucket, stick and boom assemblies. The profiles are classified into normal, critical and extreme ranges, with appropriate corrective measures to avoid extreme loading conditions. The loading capability of shovel excavators can be examined by assessing its structural strength against all possible maximum loads working on the equipment. The dynamic model is used to define efficient profiles of the critical structural components of hydraulic shovels during digging operation. This assessment is used to locate the maximum possible loads and the critical sections of the structures. The method presented in this paper forms the basis for developing comprehensive simulator models for efficient shovel operations in constrained mining environments.

Jan 1, 2003

By C Li

Removal of gangue minerals from ilmenite concentrates can beaccomplished by relatively low temperature roasting in controlled gasatmospheres to selectively enhance the magnetic separationcharacteristics of the ilmenite. At roasting temperatures below 800¦C the magnetising reactions are often not consistent with phase equilibria considerations. Metastable phases can nucleate and control the roasting products. In weathered ilmenites the phase assemblages and microstructures in the altered ilmenite grains can influence the roasting reactions. In this paper we give an overview of the phase chemistry of chemically weathered ilmenites and of metastable phases formed by low temperature roasting. We also report the results of roast experiments conducted in a neutral gas atmosphere. Major increases in magnetic properties after short roasting times at low temperatures were obtained for a range of ilmenite concentrates. For example heating a secondary ilmenite concentrate from Western Australia for 15 minutes in nitrogen at 600¦C gave an increase in the three kilogauss magnetic fraction from three to 92 wt per cent. The solid state phase changes accompanying the inert atmosphereroasts were characterised by combining elemental analyses withquantitative phase analyses of the ilmenite concentrates and their roast products. It was found that the phase reaction that is principally responsible for the increase in the magnetic properties of weathered ilmenites involves a transformation of disordered ferrous-containing pseudorutile to an ordered ilmenite-hematite solid solution containing typically ten to 35 mole per cent of the hematite component. Examples are given of the application of the inert atmosphere roast to effect separations of ilmenite from gangue minerals.

Jan 1, 2001

The first 12 m diameter rakeless thickener in the Australian gold mining industry was installed to treat plant tailings at the St Ives gold plant in April 2000. The plant processes approximately 3.2 M tonnes of ore producing about 430 000 oz of gold per annum using conventional crushing, grinding, gravity and carbon in pulp processing methods.The main benefit sought from the thickener was to improve water recovery in the plant and provide water for a 55 000 oz per annum heap leach operation. The thickener design indicated that more than 128 m3/h of overflow water could be returned directly into the plantÆs water circuit, relieving the demand on the borefields. The resultant surplus in the water circuit would then be available for the heap leach project. Based on laboratory and pilot plant scale tests conducted by EIMCO the thickener was designed to handle up to 700 m3/h of tailings slurry (450 tph of solids) with a 40 per cent oxide component in the ore blend. The normal plant throughput is 565 m3/h of slurry (400 tph of solids). Gold mineralisation in most areas at St Ives comprises quartz-sulphide vein and breccia lodes with common albite-biotite-chlorite alteration assemblages. There are well developed supergene gold horizons in the clay-oxide profile above most of the deposits (Osborne, 2002). This results in a wide variety of ore types being treated. At times 40 - 50 per cent of the ore may be oxide in nature. After some commissioning difficulties associated with instrumentation, the thickener has performed satisfactorily although it has not reached its design capacity. The maximum density achieved under normal operating conditions with 20 per cent oxide ore is about two per cent below the design. The thickenerÆs performance deteriorates further with increasing amounts of oxide ore in the blend. The thickener has provided sufficient water for the successful operation of the heap leach and has also provided some down stream benefits for the gold plant by way of pH and cyanide conditioned thickener overflow water.

Jan 1, 2002

Solid EnergyÆs project evaluation process utilises a standard staged gate approach, with five levels leading ultimately to project execution (level 6). For a project to progress through each level, specific financial criteria need to be satisfied. Solid Energy primarily use value based (discounted cash flow) metrics to support investment decisions. Within this approach Solid Energy utilise a number risk-based techniques to quantify project uncertainty. This includes the use of risk-based probabilistic analysis using Monte Carlo simulation and probability-based scenario analysis. Figure 1 shows the net present value (NPV) cumulative probability. Project risks are identified through comprehensive risk workshops. The output of these workshops (list of key risks, ranges of uncertainty and probability of occurrence), is quantified within the financial models. Incorporating this risk information on a probabilistic basis allows an investment decision to be made with a robust knowledge of the range of possible project outcomes along with the likelihood (probability) of those outcomes occurring, for example 80 per cent confidence that the project value will be greater than NZ$10 M, 50 per cent confident it will be greater than NZ$50 M and ten per cent confident it will be greater than NZ$70 M. Incorporating risk implicitly into the financial analysis allows the business to easily evaluate/measure projects with different risk profiles. The detailed risk analysis does away with the complexity of arbitrary risk-based hurdle (discount) rates, as projects can be evaluated based on their specific risk characteristics. Whether a project will progress to the next level of investment and ultimately into implementation depends firstly on the value assessment in comparison with the associated risk/uncertainty, and secondly matching this with the businesses appetite for risk. At Solid Energy standard criteria are used for specific project evaluations, but in addition projects are considered on a portfolio or strategic basis also. Solid Energy attempts to maintain a mix of low risk (low value) projects with some high risk (high value) opportunities. The mix of projects must remain in line with the shareholdersÆ risk appetite. One of the keys to a successful investment decision is ensuring that the appropriate information is available to decision-makers so that they may proceed with a comprehensive understanding of the risks and impacts associated with the decision.

Jan 1, 2007

By M J. Kelleher

CREAM is an acronym for coal recovery, evaluation, analysis and management and is a business improvement project at BMAÆs Goonyella Riverside mine that is focussed on maximising coal recovered. In August 2003, Goonyella Riverside was set a challenge to quantify coal loss and dilution and their relationship to cost, revenue and ultimately profit. While the mine was confident in its site forecasts of recovery (and loss), it was clear that the traditional measurement and analysis systems were inadequate to firstly, identify key loss areas and mechanisms and secondly, successfully quantify the benefit of various coal recovery initiatives. The path that BMA Goonyella Riverside has travelled to maximise coal recovered can be divided into four key steps: Mapping the process û This step involved the development of a coal flow process map for Goonyella Riverside that stepped through each component of the process from the coal reserve to the customer and identified key measurement points for the purposes of reconciliation. Understanding coal loss and identifying opportunities û This step involved conducting two detailed Reserve to Customer projects at the mine site to track a block of coal from the reserve to the customer and to gain a greater understanding of the relationship of dilution, coal loss mechanisms, revenue and costs associated with recovering additional coal. Coal data systems development û Two important coal data systems have been developed and implemented at Goonyella Riverside in the past twelve months, namely SnowdenÆs Coal Reconcilor and SeamFix. These systems enable coal losses and dilution to be quantified and reconciled back to the initial coal reserve. Implementation of loss reduction initiatives û This step involved the formation of a business improvement project referred to as æCREAMÆ in August 2004, for the purposes of improving pit coal recovery and maximising business value. To date a series of coal recovery trials have been run in a number of pits at Goonyella Riverside that have yielded significant improvements in business value. The key to the success of this project has been the discipline to follow a defined process map, management commitment through resourcing and shared key performance indicators, a successful acceptance strategy resulting in holistic ownership and the implementation of sustainable reconciliation systems. Coal loss and dilution are now quantifiable and their relationship to cost, revenue and ultimately profit is well understood. This paper discusses the process that Goonyella Riverside has adopted to maximise coal recovered.

Jan 1, 2005

By N Murphy and, S Santomartino, M Cramer

Acid rock drainage (ARD) can have detrimental effects on mining infrastructure, water reuse options and environmental discharge. As a result, some form of short- or long-term treatment is required at many mine sites. Successful treatment depends on a number of factors including the selection of an appropriate treatment technology and its correct implementation. A variety of passive and active technologies are available for dealing with ARD. Passive treatment solutions do not require continuous chemical inputs but take advantage of naturally occurring chemical and biological processes. They are often low cost, site specific approaches and are predominantly used in post-closure situations. Passive systems are well suited to drainage with low acid loads and low soluble aluminium concentrations, and are more effective with highly reduced (ie low oxygen) water. While they are often regarded as permanent fixes, most require some form of ongoing maintenance and all have an engineered life expectancy (ie finite carbonate and organic matter budgets). Passive treatments include, oxic limestone drains, anoxic limestone drains, limestone diversion wells, various reducing and alkalinity producing systems, pyrolusite limestone beds, aerobic and anaerobic wetlands, permeable reactive barriers (organic ¦ carbonate and zero valent iron), slag leach beds, and gas redox and displacement systems (GaRDS). Active treatment solutions require a continuous or semi-continuous activity (eg reagent dosing) to correct water quality issues. They can be engineered to treat virtually any type of drainage or site specific ARD issue, and have no set acid load or redox limitations. Tasks handled by active treatment systems are almost invariably larger and more costly than for passive systems. Active treatment approaches include; pH control, adsorption/absorption, ion-exchange, electrochemical concentration, biological mediation/redox control, flocculation/filtration and crystallisation. A range of generally available and proprietary technologies has been developed around these approaches. Active treatment involving pH correction with alkaline amendments is the most common and cost-effective form of ARD treatment. A variety of fixed plant and portable treatment systems are available. Calcium-based reagents, including quicklime (CaO), hydrated lime (Ca(OH)2) and limestone (CaCO3) remain the reagents of choice for the majority of active ARD treatment worldwide. This is principally due to their widespread availability, non-proprietary nature, and variety of proven dispensing technologies and cost-effectiveness. Limestone, in particular, is a very low cost reagent. However, due to æefficiency of useÆ problems with limestone in passive treatment systems, combined with its very low cost, there has been a recent emphasis on developing active treatment systems that use limestone efficiently. As the requirement for treatment increases, there is a growing emphasis on treatment sludge management and sludge stability. The final choice of a suitable treatment technology is dependent upon water chemistry (eg pH, type of metal contamination, acidity), flow rates, acid load, local natural resources (neutralising materials, topography), climate, site logistics, environmental risk and economics. The benefits and limitations of both passive and active treatment technologies are summarised.

Jan 1, 2003

Aspects and anomalies in the present Standard Specifications for Blended Cements which may have operated in Australia against the development of the greater use of Slag Blended Cements are noted. Estimates of slag and ash usage in Australia are given and the need for further research with local materials stressed.

Jan 1, 1979

By Dunlop G. A, Cantrell R. A

The metallurgical and engineering requirements that form the basis for planning column flotation Pilot Plant testwork are reviewed. Pilot plant operating issues are discussed and a basis for the testwork program formulated. The application of the testwork results to engineering design and scale-up is briefly reviewed.

Jan 1, 1992

Activity-composition-temperature relations for both gold and nickel have been determined for the solid and liquid states of the gold-nickel system by the application of the Margules equations. These relations are in satisfactory agreement with activity measurements of nickel in the solid state, the observed phase boundaries of the system between 700 and 1725°K, as well as being consistent with data on the enthalpy of mixing.

Jan 1, 1971

The electrochemical dissolution of gold and other noble metals in hydrochloric acid using alternating current has been investigated. The experimental results show that this technique is efficient for dissolving pure noble metals and offers prospects for their extraction from wastes and poor ores.

Jan 1, 1992