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By M Logsdon, T R. Clark, T I. Mudder

Oxidation of pyrite and other metal sulfides is accelerated by the activity of acidophilic iron- and sulfur-oxidising microorganisms. The ideal biocide for controlling biocatalysed acid rock drainage (ARD) would be inexpensive, inhibitory toward sulfide-oxidising bacteria at low concentrations, relatively non-toxic toward non-target organisms, degradable in the environment outside the zone of application, stable and long-lived in the impacted environment, sufficiently mobile to penetrate into piles of waste rock or tailings, and effective regardless of the metal sulfides present. A potent agent for combating ARD that fits these criteria is the thiocyanate anion (SCN-). The objective of this study was to determine the effectiveness of thiocyanate in controlling or preventing ARD within several types of sulfidic waste rock and tailings. Results were evaluated within a context encompassing process water and solids management strategies employed at different precious and base metal mines. Sulfidic rock was treated with solutions of potassium thiocyanate and subjected to accelerated weathering tests in lab-scale humidity cells, trays, and columns. Certain tests also utilised solid phase copper thiocyanate (CuSCN) to evaluate a ærelease on demandÆ strategy. Leach solutions were analysed for parameters indicative of ARD including pH, redox potential, conductivity, acidity, sulfate, iron, and certain heavy metals. Two larger scale field tests were also initiated by personnel at separate mines using, in the first case, ore containing a pyritic component in large columns and, in the second case, waste rock containing base metal sulfides in lined pits. Humidity cell tests showed low concentrations of thiocyanate solution applied to pyritic waste rock could reduce ARD formation by 90 per cent or more compared to untreated controls, with the residual release of ARD components (eg sulfate, Fe, acidity) probably reflective of strictly chemical oxidation of the sulfides by molecular oxygen. Thiocyanate applied at a concentration of 22 mg/kg to waste rock from a base metal mining operation in large laboratory scale columns reduced acidity and sulfate release by 75 per cent to 80 per cent compared to untreated controls. This extent of reduction in ARD may not meet discharge water quality criteria, but has the potential to significantly reduce lime consumption and sludge production in a conventional neutralisation facility. The use of a solid-phase metal thiocyanate compound (CuSCN) at a dosage of 194 mg/kg pyritic ore resulted in the following per cent reductions in leach solution parameters in comparison to controls: sulfate (78 per cent), acidity (93 per cent), dissolved Fe (99.4 per cent), and dissolved arsenic (99.9 per cent). This compound has the further advantage of being relatively stable until needed, dissolving only in the presence of an acidic and oxidising ARD solution. If this line of investigation progresses favorably, it offers the possibility of an ARD prevention technique that may be applicable in some settings. Mine-site pilot scale tests with pyritic ore resulted in reductions in sulfate (56 per cent) and Fe, As (66 - 68 per cent). In sum, thiocyanate at relatively low concentrations dramatically reduced ARD from sulfidic rock in a simulated heap. The pilot test using waste rock containing base metal sulfides has begun only recently. A preliminary process design and cost estimate was made for fullscale application of thiocyanate to waste rock at a hypothetical gold mining operation producing 5000 tpd of ore and 10 000 tpd of sulfide containing waste rock. The combined capital and operating costs for the full-scale thiocyanate application facility were about $US 0.25/tonne of waste rock and $US 0.50/tonne of ore. Although thiocyanate is readily available commercially, it also occurs in process solutions associated with certain types of mining processes. Such solutions after selective treatment might be recycled to sulfidic waste rock or tailings, rather than being treated for thiocyanate degradation.

Jan 1, 2003

By M Hassall

There is a plethora of activities that have been, and continue to be, performed to improve the health, safety and well-being of workers involved in resource industry activities. These activities include implementation of risk management systems, performing risk assessments, constructing bow-ties, implementing critical control management systems, undertaking personal, process and functional safety initiatives, implementing psychological and physical health as well as industrial hygiene programs. Despite the significant work that has occurred over the last several decades, unacceptable levels of fatalities, injuries and illnesses continue to persist as evidenced by Safe Work Australia statistics.

Apr 16, 2024

R F Johnston 1 ABSTRACT The possibilities for bacterial leaching of refractory gold ores found in the Central Victorian region of Australia are examined. The behaviour of bacteria, especially 77iobacillus ferroaridans is outlined and the effects of these when they are exposed to pyrite, arsenopyrite and stibnite are examined. The factors which are particular to Central Victoria are outlined and the possibility of adapting a bacterial culture to suit the conditions is discussed. It is concluded that a bacterial leaching system is a feasible proposition and that it could enhance leaching rates and yields.

Jan 1, 1994

By Han Kook-Nam, Lawson F

The recoveries of the three cobalt minerals in the Mount Cobalt deposit, cobaltite CoAsS, erythrite CO3(AS04)8H20, and new cobalt mineral with a composition approximating 2CoO.CaO.Fe203.2As205.11H2O were investigated using physical and surface-chemical processes.Over 80 per cent cobalt recovery was achieved by tabling a cobaltite-mineralized sample, while about 76 per cent cobalt recovery was obtained by dry feed magnetic separation of a sample containing erythrite and the new cobalt mineral. The resultant primary magnetic concentrate with a cobalt grade of 5.5 per cent, was able to be upgraded to 14.4 per cent cobalt by regrinding .and a further magnetic separation.Electrophoretic mobility - pH responses for each of the three cobalt minerals were found to be similar. Each mineral remained negative over the pH range 3 to 11 and was most negative at mildly alkaline pH values.Cobaltite was floated effectively with amyl and ethyl xanthate collectors under acidic conditions at collector concentrations of 10-2M to 10-5M. Erythrite showed a similar flotation response using 10-sM amyl xanthate. The practical application of these laboratory separations to an industrial process is suggested.

Jan 1, 1976

By L Keeney

Cu-Au porphyry deposits are large tonnage low-grade resources dependent on processing large volumes of material. The ability to understand and predict comminution performance is critical, as it is frequently the rate-limiting step during processing. Parameters required from geometallurgical mapping and modelling of comminution performance are: A×b processing domains based on impact breakage variability, and BMWi processing domains showing grind response variability which lead to Mine throughput domains for a specific comminution circuit configuration. Due to the cost and/or large sample requirements of traditional comminution tests, insufficient data density and distribution of comminution indices commonly exist, making it difficult to model and map deposit scale variability. One method routinely applied to three dimensional domaining is to have an a priori zoning based on geological features (lithology, alteration, mineralogy, textures), and then apply to all material within a given domain the metallurgical values measured on a single sample or average of samples from that domain. The problem with this approach is that commonly the geological domains do not reflect comminution response, therefore compromising the quality of the average domain estimate. To resolve this problem an alternate integrated geometallurgical mapping and modelling method is applied to model and map comminution performance at Cadia East. This paper uses a data set of ~32 000 assay measurements and geological logging information, integrated with ~150 comminution measurements to analyse and develop proxy support models for comminution indices (ie A×b, BMWi, and throughput) based on inherent geological variability. Discrete downhole comminution processing domains are created, mapping orebody response while maintaining inherent variability.

Sep 5, 2011

By M, C A. RosiFre, R C. Figueiredo e Silva

Jaspilites and underlying basalt contacts of the Archaean volcano- sedimentary Grpo Parß Group, Carajßs, host giant iron mineralisation in the ~100-km long, E-W trending Carajßs fold. Preliminary, unpublished geochronological data point to a Palaeoproterozoic mineralisation event. Geochemically, jaspilites are typical volcanogenic banded iron formations. Basalts exhibit evidence of spilitic seawater interaction. Iron-associated hydrothermal alteration of mafic rocks was induced by fluid infiltration in amygdales, with development of chlorite- and hematite-dominated zones. In the case of jaspilites, iron mineralisation encompasses: partial replacement of jaspilitic microcrystalline hematite by blasts of martitic magnetite; jasper recrystallisation, producing fine-grained, hematite-free granoblastic quartz; martite recrystallisation, forming lobate¦subhedral hematite; pervasive porosity development by quartz-chert leaching; incipient cavity filling by microlamellar hematite; and advanced filling by coarser, euhedral and comb-textured, tabular- shaped hematite.Peak hydrothermal ore textures indicate typical epithermal-crust conditions, supported by preliminary fluid-inclusion calculations at 160 - 200¦C. Such temperatures and extreme fluid-to-rock ratios during alteration must have exceeded the ambient metamorphic conditions, with the infiltrating fluid relatively hot and capable of leaching SiO2. Therefore, mineralisation developed over exhumed, Archaean, brittly deformed rocks, with mineral associations representative of very low- to low-grade metamorphism. Considering that chlorite (¦talc) abounds in mafic rocks; hydrothermal albite is developed; dolomite fills veins and vugs; the typical rare-earth-element (REE) pattern of jaspilites is significantly modified in higher-grade hard hematite ores (higher LREE); pyrite, copper sulfide minerals and rare gold occur in association with carbonate-quartz-rich alteration zones, it is suggested that an alkaline, H2O-Fe-CO2 mineralising fluid dominated, also containing species like S¦Cu¦Au. Peak-mineralising conditions are likely to have resulted from a single, evolving fluid, via incipient- through advanced-stage alteration phases. The porous, high-grade soft hematite-type ore (SH), rich in microlamellar and anhedral hematite, must have derived from interaction with this relatively hot SiO2-leaching fluid, whereas the high-grade massive hard hematite-type ore (MH) developed due to closer fluid-rock temperature equilibrium conditions, attained by mineral reactions, with relative increase in the Fe/Σcations ratios allowing the precipitation of subhedral-tabular hematite that partially cements the soft-hematite ore. SH and MH hematite ore types must thus reflect intermediate and high fluid:rock ratios, respectively. Since the N5 deposit is to date understood to contain the largest amount of the MH ore, its units are interpreted as the loci of the highest fluid:rock ratios in the district. Preliminary mineralogical information regarding the S11 deposit of the Serra Sul (south range) implies higher-temperature conditions. The near-equant grain size and the granoblastic intergrain relationship, coupled with the presence of riebeckite, augitic pyroxene and garnet, suggest hornfels textures. The data collected, though still relatively sparse, permit the speculation that the immense driving force for the Carajßs world-class iron deposits was a relatively shallow, igneous-related hydrothermal system. If such a model is correct, then the Carajßs Palaeoproterozoic iron deposits could represent an end-member of the iron oxide-copper-gold hydrothermal system in the province.

Jan 1, 2005

After four or so long years at university, where life revolves around lectures, assignments, and drinking coffee strong enough to keep you awake for five nights in a row to finish your thesis, preparing yourself for employment is not an ea

Jan 1, 1994

By H R. C Pratt, G W. Stevens

Hydrodynamic and mass transfer performance are presented for a 72.5 mm diameter pulsed disc and doughnut column of the type used by Western Mining Corporation, Olympic Dam Operation, for the extraction of uranium from sulphate media using Alamine 336 as extractant. For the present purpose, 4.0 g/L sulphuric acid was used as solute. The mass transfer data were interpreted in terms of the diffusion model, thus accounting for continuous phase axial dispersion. The results indicated that an efficiency corresponding to approximately one transfer unit over the 1.0 m height of the column was obtained. This efficiency is comparable to that observed by Gottliebsen (1997) for a pulsed perforated plate column using 173 gm/L sulphuric acid.

Jan 1, 2000

By Johnson N. W, Manlapig E. V, Alexander D. J, Franzidis J. P

The importance of the froth region on flotation performance is often emphasised in the literature. It is well-known that decreasing froth depth or increasing air flowrate results in increasing cell recovery at the cost of lower concentrate gra

Jan 1, 1997

Accounting for borehole damage in analytical modelling of explosively generated stress waves is important for predicting the finer details of the stress wave patterns observed in the field. The classical Sharpe's [19421 concept of an effective borehole larger than the initial borehole diameter has been widely accepted to explain material damage around a borehole. A new analytical model based on dynamic compaction is advanced to predict far-field stress wave patterns. This model supports field data corresponding to reduced frequency of oscillations and increased damping. The present model recovers the earlier result when compaction around the borehole representing borehole damage is ignored.

Jan 1, 1990

By L Yang, L Chen, E Hu, D Tang

Online monitoring of particles cumulative percent passing (PCPP) for a target size at hydrocyclone overflow, compared with traditional offline methods, provides PCPP feedback in real time, and is advantageous in enabling energy-efficient comminution, increasing downstream flotation efficiency, and improving upstream resource knowledge. However, existing online approaches are generally costly and bespoke, and some are sensitive to operational changes. Therefore, this study proposes a new low-cost alternative based on accelerometer measurement for online PCPP monitoring in the overflow of hydrocyclones and provides a preliminary experimental investigation under dry condition. The proposed method uses a sensing probe inserted into the overflow pipe of a hydrocyclone to receive particle impact from the incoming slurry, with accelerometers attached to the probe and mounting frame outside the pipe for particle-probe impact detection. As a preliminary investigation before studying particle-probe impact events in slurry, tests under dry condition without fluids were conducted using dry sand particles in free fall from a fixed height. Accelerometer measurements are analysed in both time and frequency domains through root-mean-square (RMS) and fast Fourier transform (FFT). Results show that accelerometer measurements are useful in estimating mass flow rates, which are correlated to the accelerometer output amplitude RMS values in time domain, in a non-linear mapping. Different particle size classes can be identified by examining the accelerometer output amplitude at a known mass flow rate. Different particle size classes feature their distinct signature frequencies (SFs) that can be examined via FFT and the SF is found to be independent of the mass flow rate. The results imply that any PCPP changes can be detected by the change in the accelerometer output amplitude as well as a shift in SF, which demonstrates the effectiveness of using accelerometers to gauge changes in PCPP. Based on the current findings in dry condition, future work will investigate particle-probe impact events in slurry.

Aug 24, 2022

There are significant Mineral Resource and Reserve reporting challenges facing a mining company operating in the global arena. This paper specifically examines the Mineral Resource and Reserve reporting challenge facing BHP Billiton. The changing regulatory environment creates a significant challenge for global mining companies when reporting Mineral Resources and Reserves. The development and implementation of internal policies and standards for collecting and collating resource and reserve information is required for corporate governance, however the challenge is then to report this information publicly in such a way as to comply with the various codes and requirements in the many jurisdictions in which the company is required to report. The move to an International Code is not only desirable but is an essential requirement in todayÆs global market. The agreement to report using a single code internationally is however only the first step. A truly practical international reporting system must have common definitions and guidelines for interpretation as well as an international approach to the definition of a Competent Person, and even more importantly a common acceptance of that code by the relevant investment regulatory bodies. Without the universal acceptance of the concept of an international reporting code by the major regulatory bodies, implementation of such a code will be limited. With the major global mining companies seeking to raise capital in the USA, the worldÆs largest capital market, the Securities and Exchange Commission (SEC) and its approach to reserve reporting is becoming increasingly important. The development and implementation of an International Code must gain the support and acceptance of the SEC if it is to be successful.

Jan 1, 2002

By P J. Harper

Maximising shareholder value is a widely stated strategic goal of many mining companies. Mining projects can be capital intensive and achieving good returns is essential to encourage future investment in the industry. Despite the widely accepted importance of shareholder value, the minerals industry is often accused of providing relatively poor returns when compared to other industries. There are many recent and well publicised examples of minerals companies that have failed to deliver value to their shareholders. There are numerous business improvement initiatives employed within the mining industry to assist mine operators improve performance. Some are more effective at creating value than others. Benchmarking is one technique that is commonly used to identify performance gaps and target and prioritise opportunities for improvement. However to be effective, Benchmarking must be used appropriately and result in actions that lead to measurable operational improvement. When conducting a Benchmarking project it is important to remember that the aim should be to improve value. For this to be achieved, the strategic goals must be incorporated into the process. This paper details a structured and comprehensive approach to conducting a successful Benchmarking project. Focusing on Benchmarking as a technique for measuring and improving operational performance in underground mines, the underlying drivers of best practice in underground mining are identified.

Jan 1, 2005

The Porgera gold project is now in its seventh year of operation as one of the world's prime gold mining projects in one of the most underdeveloped and remote regions of the world. The unique gold deposit was development in stages to its present size of operation with an underground mine of 2000tpd, an open pit operation moving 210,000tpd and a complex metallurgical plant treating an average of 16,500tpd of ore. During the past years the operation had to address an array of issues relating to the "development" of the region and this is still ongoing. Development means different things to different people and though the parties that signed the different agreements relating to the Mining Development Contract were aware of this, none has real- ised the extent to which this is true. The developing company (a joint venture between Placer Pacific as the Manager, Goldfields Porgera, Highlands Gold and the Government of PNG), provided funds for risky exploration and the capital for development of the project. Its shareholders ex- pect an economic and viable mine operation from the deposit to ensure them returns on their investment. The local people gave up their land, their isolated way of living and accepted to be out of their comfort zone for some time in anticipation of a better lifestyle and economic benefits in support of that lifestyle. The PNG Government has a leg in both camps and expects both outcomes at the same time. The Government is also the regulator and expects compliance on top of that. If development in general is to be successful, all parties must substantially satisfy all expectations. It is evident that the outcome of some elements of development are reasonably defined (i.e. develop a viable mine to exploit the deposit), whilst other elements are moving targets (i.e. a better lifestyle). The seeds for conflict are thus abundantly present and to resolve them requires the will of all parties in all areas to come to a solution. This path to problem solving is many times torturous as each party comes from a different culture and background and has a different understanding of the parameters in the equation.

Jan 1, 1997

By Howlett P. F, Courtley S

A problem with secondary breaking at one of the mines of Pasminco Mining led to a study of new rock breaking technologies. Many of the techniques being developed had emerged from the thrust in the USA for continuous drill=break excavation. Such approaches to rock breaking highlighted the applicability of what would normally be classified as tunnelling techniques, to the secondary breaking sector - and possibly the reverse. As a direct result of the investigations for suitable technologies, Pasminco Mining supported the development of two improved rock breaking methods specifically targeting secondary breaking, one of which could be applied to continuous excavation.

Jan 1, 1993

By Coxhead B. A, Brandt B. A

The geological exploration and evaluation of coal reserves involves the appraisal of very large amounts of data. Computers afford an ideal means of handling and manipulating the data, thereby avoiding the laborious and expensive method of manually compiling the logs in full descriptive language. The Minad system of computer storage and retrieval of geological and analytical data is particularly suited to the description of cores and cuttings from exploration drill-holes. The encoded data is arranged in a 120-column computer output sheet format; descriptive geological information in a 54-column geolog and analytical information in a 64-column assaylog. The acquired data is quantitative, uniform and relatively complete and can be selectively retrieved for processing by a wide range of specialized computer programs developed for the coal mining industry. Visual retrieval of data for manual processing is facilitated by the use of simple codes and logical word abbreviations.

Jan 1, 1977

The Ausmelt Catalytic Waste Converter (CWC) has been developed for use in the treatment of industrial wastes and for the recycling of secondary materials. Ausmelt Technology uses a top submerged lance system within a versatile and efficient slag bath reactor. High temperature pyrometallurgical reactions are carefully controlled within an oxidised molten siliceous slag such that metals can be extracted from waste feedstock for recycling, with non-volatile elements reporting to the slag, usually as oxides. Modification of the slag chemistry results in a final slag product that is stable, vitrified and is able to pass standard leach tests such that it is safe to discard or be used in civil engineering applications. Toxic components in the wastes such as organohalides can be completely destroyed and are prevented from reforming. Waste to energy conversion is practiced by the addition of a heat exchanger/steam generator in the converter offgas system. The Ausmelt CWC has been used for recovering zinc from residues and slags, treating spent potliner (SPL) from the aluminium industry and a wide range of electronic and other potentially valuable waste materials. Methods of monitoring the exhaust gases at different stages in the CWC gas handling system are discussed. The assay of these gases prior to emission is used to assist in the control of the converter chemistry to ensure the complete oxidative breakdown of the feedstock.

Jan 1, 2002

By X Li, H Alehossein

The oscillating disc cutter (ODC) is an innovative technology for the continuous excavation of hard rock. This paper will discuss:the reasons for its development;its method of operation;current experimental results and mathematical modelling undertaken at the CMTE; andapplications in the mining and rock excavation industry.

Jan 1, 1999

The paper describes the $US240 million expansion at Hudson Bay Mining and Smelting Co LimitedÆs operations in Canada. The company has been continuously producing copper and zinc from local area mines at its Flin Flon metallurgical plant since 1930. The paper details the companyÆs operational turnaround since 1995 and æThe 777 ProjectÆ which includes: two new mines, expansion and modification of the concentrators, expansion of the zinc pressure leach plant, a new zinc electrolytic cellhouse and the modifications to the copper smelter gas handling system to reduce ground level gas emissions.

Jan 1, 2000

In June 1996, Nord Resources Pacific (Nord) decided to work towards obtaining all necessary approvals from the government of PNG for a mine on Simberi Island in the Tabar Island Group, New Ireland Province. On the 9th of September 1996, Nord submitted a Proposal for Development and an application for a Mining Lease to mine the oxide gold deposits on Simberi Island. The Mining Lease was granted on the 3rd of December 1996 in a signing ceremony on Simberi Island. This was achieved in the extremely short time frame of less than 3 months and this paper attempts to explain the processes which made it possible.

Jan 1, 1997