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By G C. Kiel, G J. Nicholson

Corporate governance has never been more topical. A glance at any major newspaper or business publication will reveal a litany of corporate failures based upon the governance of the organisations involved (eg Byrne, 2002; Hayes, 2002; The Economist, 2002). The increased compliance requirements and speculative nature of our industry means that corporate governance systems are, if anything, more important than in the general business community (Arthur, 2001). Rather than focus exclusively on the contribution of governance to corporate failure within the mining industry, however, our objective in this paper is to examine how boards can add value to the corporations that they govern. In order to highlight how a board can add value to a company, we commence by outlining the role of the board in the modern corporation in general and the mining industry in particular. We then introduce the concept of shareholder value and identify the steps on which a board needs to focus to enhance shareholder value through value tracking processes. Our discussion pays particular attention to the importance of organisational culture to the companyÆs activities and utilises three case studies from the mining industry. We conclude with an overview of what mining boards can do to enhance their culture and drive performance changes for the benefit of the companies they govern.

Jan 1, 2002

By De Broglio R

The Mae Moh coal deposit was discovered some 60 years ago by villagers who noticed spontaneous combustion of coal outcrops. The first production began in the 1950's to fuel a fertilizer plant and a 12.5MW power station. During the period 1976 to 1979, three 75MW power station units were constructed on site. These have a total daily coal consumption of some 5000 tonnes and are served by a stockyard of approximately 60 000 tonnes total capacity. Stacked coal is reclaimed by means of a front end loader onto reclaim conveyors. During the years 1983 to 1986 four 150MW power station units were constructed east of the eastern seam subcrop, sons 2 km from the original power station complex. These have a daily coal consumption of nearly 12000 tonnes and are served by a stockyard of total capacity 270000 tonnes, equipped with two stackers and two bucket-wheel reclaimers for a totally mechanised system.

Jan 1, 1986

The Southern Mines Rescue Station (S.M.R.S.) has been established for 55 years and in the past 15 years has had only 4 major call-outs. Whilst the mines rescue training program has continued to expand, the Station has become involved in other work which includes mine worker training and limited research. Notwithstanding, the prime role of the Mines Rescue Station has not been overlooked and the Station has only advanced with the many changes that have occurred in the coal industry. The Rescue Station activities are financed by contributions from Colliery proprietors and the aim of the S.M.R.S. Committee is to provide a service in which colliery management and mine workers will have a high degree of confidence.

Jan 1, 1981

The metallurgical testwork program is generally the most important critical path item for the completion of a bankable feasibility study and hence can become the critical parameter for financing of potential mining projects. This paper presents generic detailed testwork programs suitable for bankable feasibility studies for a gold leaching and polymetallic flotation study. The design of the metallurgical testwork program for each of the two differing processes is discussed and the critical factors that effect the selection of the testwork programs are highlighted. The importance of the metallurgical testwork results in predicting the metal recoveries and cash flow prediction for the project is presented. The detail of the testwork programs costing is broken into activity based methods based on the laboratory and management hours/costs, such that generic rule of thumb costing guidelines can be generated. The scheduling, costing and importance of the metallurgical testwork program to process feasibility studies are discussed in this paper.

Jan 1, 2000

By Shinnosuke U, Zhang HE, Qian X

In this paper it is recommended that pyrite is to be separated as froth from arsenopyrite by selective depression of arsenopyrite in strong alkaline medium (1), by oxidation with chlorinated lime (II), by co-use of chlorinated lime with sodium carbonate (III), and by modification with `L' reagent (know-how) without filtering to get rid of residual copper ions after Cu activation (IV). The corresponding principles of these (new) effective methods were briefly discussed. The artificial mixture (1:1) of pyrite and arsenopyrite could be successfully separated, and concentrates of pyrite containing 2.12 per cent (I), 7.00 per cent (II), 2.60 per cent (III) and 3.16 per cent (IV) arsenic with recovery of 90.9 per cent (1), 89.5 per cent (II), 89.0 per cent (III) and 81.4 per cent (IV) respectively can be obtained by only one flotation. Some effective precautions were suggested to improve the separation of arsenopyrite and pyrite (or other sulphides) by flotation.

Jan 1, 1993

Bacterial leaching of sulfide minerals are fairly well established in heap, dump and in situ leaching and the primary bacterial treatment of refractory gold concentrate using CSTR have gained industrial prominence in recent years. Three cultures, a mesophile T ferrooxidans (DSM583), a moderate thermophile Sulfobacillus acidophilus (strain YTF1) and a extreme thermophile (Sulfolobus strain BC65) were used for the biooxidation (pre-treatment) of the Porgera gold-bearing pyrite concentrate under optimum O2 and CO2 enriched air (30 per cent O2 and ten per cent CO2) based on volume ratios. The positive effect of using oxygen and carbon dioxide enriched air for the biooxidation of gold-bearing pyrite mineral was clearly demonstrated where an increase in Fe release rate by a factor of 2.8, 1.8 and 1.5 for DSM583, YTF1 and Sulfolobus respectively were observed compared with the shake flask tests. The lag phase observed with the other test conditions such as in shake flask or with air decreased by about 80 per cent for all three cultures. The average observed dissolved oxygen concentrations in the pulp for these tests were 8.7, 5.8 and 5.0 mg/L for DSM583, YTF1 and Sulfolobus respectively, indicating that O2 was not limiting in these tests. The pulp redox potential was observed to increase with time for all tests coincident with the leaching rate and reaching a maximum of 663 mV, however the maximum value differs for each strain, with DSM583 exhibiting the highest followed by YTF1 and Sulfolobus. Biooxidation of pyrite under optimum gas enrichment at different pulp densities showed near total Iron extraction occurred for pulp densities of three, ten and 20 per cent (w/v). At high pulp densities, more so at 40 per cent than 30 per cent (w/v), the leaching rate decreased rapidly for tests with YTF1 and Sulfolobus. Monitoring of dissolved O2 shows that O2 demand increased with increasing pulp density and the average dissolved O2 concentration observed for YTF1 and Sulfolobus at 40 per cent solids concentration was 1.0 mg/L and below, suggesting limiting oxygen and carbon dioxide conditions for these two cultures. The decrease in leaching rate observed at high pulp densities (30 and 40 per cent) under optimum gas enrichment was accompanied by low metal dissolution and low redox potential values which was attributed to shear stress due to attrition of cells by high solids concentration, toxicity of metal ions especially Ag and Fe and the formation of precipitates and jarosites as confirmed from XRD analysis of leach residues hence impeding the leaching process. Limiting conditions due to high pulp density and viscosity were only observed for YTF1 and Sulfolobus. The subsequent cyanide leaching for precious metals from the pre-treated pyrite concentrate in all cases shows the extent of gold and silver recovery increased with the degree of pyrite oxidation and Au and Ag recoveries in excess of 80 per cent were achieved compared with only 18.1 per cent and 35.9 per cent for gold and silver respectively when treated by direct cyanide leaching on the original, untreated concentrate.

Jan 1, 2004

By B Bendtsen, L McQueen

The use of shotcrete as an efficient means of both temporary and permanent ground support has continued to grow over the last 30 years, with its use underground now commonplace around the world. However, the development of analytical design methods has lagged advances in material and application technologies. Historically, part of the reason for this was a lack of understanding of how shotcrete linings actually worked. Considerable progress has been made in this area in recent years and this paper attempts to summarise the current state of practice with respect to shotcrete lining design. It then concludes by summarising areas where the authors consider future research and development is still required.

Jan 1, 2008

The last two years have seen a rapid change-over from mechanised cut and fill. stoping to the more economic and productive long hole open stoping method, such that today more than 80 per cent of total production is won from open stopes. At first drilling was by sub-level rings and/or parallel up and down holes from inter- mediate sill horizons using conventional exten- sion rod equipment. Sub-levels were developed no more than 40 metres apart to allow accurate drilling. Compact, crawler mounted in-the-hole hammer equipment was introduced as soon as it became available in Australia. Today, all open stope drilling is done with three Atlas Copco ROC306 rigs and two Ingersoll-Rand CMM jumbos. Fans of 115 mm diameter holes, varying from near vertical down holes to horizontal, are drilled with a burden of 3 m. Toe spacing varies from 3.5 m to 4 m. An Atlas Copco DG418 booster compressor is used to boost run-of-mine air from 700 kPa to 1400 kPa in the areas of longest drilling. This has improved overall drilling performance in these areas by 40 percent.

Jan 1, 1977

By Farley RJ

The use of D-H Vacuum treatment at the Waratah Works of Commonwealth Steel Coy Ltd is broadly discussed in relation to the wide variety of products manufactured by the Company. The metallurgical features of the process are considered and related to the quality benefits deriving from its use.

Jan 1, 1972

By Van Rooyen F

An introductory review of the current grade control blasting techniques (selective mining strategies) used in the Eastern Goldfields has recently been undertaken. The survey was initiated and conducted by the Western Australian School of Mines. Four distinct selective mining strategies have been identified and a number of trends have been highlighted. Many operations, however, have developed techniques which use a hybrid method to suit the site conditions. The aim of all the mining strategies is to produce an optimum product. The optimum product is one which contains no diluent and experiences no mixing of the various identified ore and waste blocks and is fully reco- vered at the minimum overall operating cost. Due to this unified aim all of the grade control blasting techniques have many common design Features.

Jan 1, 1988

The success of the In-Plant dust collection at the Albion Reid Quarry Plant situated at Para Hills, South Australia, is discussed in the light of co-operation at the design stage with particular emphasis on the duct- work and filter design. Other dust control facilities at the Plant are mentioned.

Jan 1, 1976

An attempt was made to determine the lateral extent of analcite in the Newcastle Coal Measure sediments of the Sydney Basin. From an examination of the cores of eleven bores it was concluded that the mineral is concentrated in the western sector of the original Newcastle Basin and this presumably was the region of greatest sodium concentration and aridity. The distribution of the analcite is such that it appears to have little correlative value.

Jan 1, 1967

By K Williams

Marvel Loch South Pit has had a number of stages of open and underground mining activities before acquisition by Sons of Gwalia. The historical pit had achieved a completed pit depth of 150 metres and the shaft and decline mine had reached approximately 220 metres in depth using open stope mining methods. The various mining methods reflect the various economics and industry practice at the time. The South Pit ore zones are medium grade (~2.5 g/t) but have a regular geometry and large tonnes per vertical metre. A number of studies have been completed up to a pre-feasibility stage looking at options to extend the pit depth and to lower the unit cost of gold production. The options considered were the re-optimisation of the pit to determine further cutbacks or the innovative use of an in-the-wall ramp. The in-the-wall ramp (tunnel) would permit the removal of the in pit ramp to expose additional ore that was within the footprint of the ramp design and to provide the opportunity to increase the final pit depth. Similar mining method has only been used at Three Mile (Coolgardie, WA) and Chalice Mine (Norseman, WA). The tunnel would serve as a gateway for further extension of the south mine and the central ore zone via underground mining methods. The ultimate depth of the South Pit has been extended to 310 metres below surface and significant additional ore has been recovered. This paper will give an insight into the various studies to optimise the Tunnel mining method, the determination of the various tunnel dimensions, and the phases of mining to arrive at the completed design.

Jan 1, 2003

By J M. Menacho, L Zhang, A Hoadley, L Verdugo, B Etschmann, W Bruckard

Since the introduction of Lithium-Ion Batteries (LIBs) in 1991, the market for lithium-ion cells has been driven by the high demand for portable electronic devices and more recently for batteries for the electric car industry. It is expected to grow rapidly to reach 2600 GWh globally by 2030 (US Government, Office of Energy Efficiency and Renewable Energy, 2021). However, there is a desperate need to recycle LIBs to recover valuable cathode materials and graphite. For this reason, several physical and chemical recycling technologies have been proposed to recover these materials from spent batteries. Amongst these, froth flotation technology is a potential cost-effective technology for separation of the graphite fraction from the lithium oxide components due to the natural hydrophobicity of graphite and density difference between graphite and cathode materials (Folayan et al, 2021).

Aug 24, 2022

By R H. Yoon, M Gupta, A Noble, K Huang

Froth flotation is the most commonly used separation technology in the mineral industries. Given the complexity of the pulp and froth phases as well as the multitude of operational parameters that influence flotation performance, purely fundamental models with strong predictive capacity are limited. As a result, accurately modelling modifications to an existing flotation circuit are challenging, particularly when using empirically-derived models from a different operating configuration. Despite these complexities, a recent publication by the authors (Huang et al, 2022) has shown that flotation rates can be accurately predicted from a first-principles model that incorporates hydrodynamic parameters (eg pulp density, superficial gas velocity, feed flow rates etc), surface chemistry parameters (eg contact angle, zeta potentials and surface tension), and size-by-class liberation data. Circuit simulations using this model were shown to be effective in predicting experimental graderecovery curves from the size-by-class mineral liberation matrix. Since the model is derived from fundamental characteristics of the flotation system, it can be used to simulate alternative circuit configurations with varying degrees of recycle. Conventional flotation circuits are operated in a closed-circuit configuration by routing the cleaner scavenger tails (CST) back to the rougher feed to provide an additional opportunity to recover the slow-floating particles. This widely-used flotation strategy has been under constant debate, and several researchers have provided evidence that open circuit configurations provide higher separation and better circuit control (Konigsman, 1985; Bulatovic et al, 1998; Thompson, 2016). Recently, Finch and Tan (2021), used linear circuit analysis to show that open circuit configurations have a fundamental advantage when stage recoveries are high. Given the limitations of these prior studies, the objective of the current work is to further evaluate the merits of the open circuit configuration through a detailed circuit analysis and simulation study incorporating the first principles model described above.

Aug 24, 2022

By T Smith

The evaluation of a new mineral resource and its economic viability is critically dependant on the quality of the assay data as it is this data that defines the grade of the resource. However, all too often the procedures of sampling and chemical analyses used to generate such data are neglected or given little consideration until final modelling and evaluation are under way. This approach frequently requires large reassay and/or re-sampling programs to be undertaken to validate or to improve the integrity of the data base. This paper outlines a step by step approach to ensure quality data is achieved and then maintained throughout the entire exploration and resource development program. This involves the use of correct field sampling methods, assay methods designed to give the required levels of accuracy and precision and quality procedures in place to monitor the effectiveness of the overall process. Thorough documentation is an overriding and necessary part of the entire process. Practical examples are given to demonstrate the use and value of these methods.

Jan 1, 1998

By S C. Dominy

A high nugget effect and the presence of coarse gold characterises many vein-gold deposits. The effective sampling of these deposits is often difficult because of the relatively low concentrations involved and erratic nature of the gold. Geological complexity often compounds this effect. Underground development, in-fill drilling and bulk sampling/trial mining are often required to delineate Ore Reserves. Winzing is an historical technique that was used to gather geological and sampling data during underground exploration. It permits access to the mineralised structure below the current datum to help determine viability. Winzing has always been considered an arduous and dangerous task. Modern technology has led to the development of the Mobile Supersucker, essentially a giant vacuum cleaner. This system permits safe and efficient winzing activities, and allows the collection of bulk samples for grade estimation. Bulk samples from horizontal development have long been collected to help define mineable grade. However, when defining blocks below current development, there has been over-reliance on ineffective æsmall sampleÆ drill data. The Mobile Supersucker permits safe and cost-effective development of winzes and off-winze sublevels.

Jan 1, 2003

By Y A. Stepanyants, J Crawford

A practical field method for determining the maximum value of the intrinsic oxidation rate, Smax , of sulfidic materials in waste rock dumps is proposed. Knowledge of the intrinsic oxidation rate of sulfidic materials distributed in a dump is necessary for predictive modelling of oxidation and pollutant generation over time. The suggested method uses the fact that drilling waste rock dumps to install probes for monitoring temperature and oxygen concentration causes large volumes of air to be injected into a dump by the drill rig. By measuring the rate of decrease of oxygen concentration along the length of a borehole immediately after installation, it is proposed that Smax can be calculated at different depths. The aims of this work were: to derive a simple, practical formula for the estimation of Smax from the oxygen concentrations measured over time, based on some simplifying assumptions; to use a two-dimensional numerical model that incorporates all the necessary physical processes to model the behaviour of an aerated dump over time for a reasonable range of dump and material parameters; and to compare the results of the two approaches to assess the validity of the simple formula as a method for estimating Smax. It has been found that the technique can provide reliable estimates of Smax when the value is of the order of 10-7 kg(O2) m-3 s-1 or greater. At the lower end of the range however the radius of the zone aerated during drilling becomes an important parameter and further work has been recommended to investigate this aspect of the method.

Jan 1, 2003

Both blast furnace and steel furnace slags have been used extensively and successfully on main line railroads in the United States for more than 25 years. Annually, these slags are being used as ballast at the rate of about 4 million tonnes of blast furnace slag and 1 mil- lion tonnes of steel furnace slag, much of it on main line with 90 metric tonne car loadings. More steel furnace slag would be used if it was available. Both slags meet all the specification limits of the American Railway Engineering Association. Actual use on high density rail- roads has confirmed the long range economics of their use. Comparison of laboratory tests, such as Los Angeles abrasion, with actual field per- formance has shown conclusively that commonly used laboratory tests can not be used to accu- rately compare the quality of various types of ballast materials.

Jan 1, 1979

By G Partington

A regional scale prospectivity model was developed for Papua New Guinea (PNG) to identify areas of porphyry Cu-Au mineralisation. Weights of evidence modeling techniques were used to determine spatial correlations between porphyry Cu-Au mines and predictive maps created from available spatial data. These predictive maps were then combined into a final prospectivity map. Despite limited regional scale data the model has successfully identified areas of known porphyry mineralisation as prospective and has also identified areas where new mineralised systems may be discovered with further exploration. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008