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By G T. Hefter, P Singh

Sulphur dioxide oxidation is an attractive alternative anodic reaction to the evolution of oxygen in copper electrowinning. Accordingly, the electrochemical oxidation of SO2 in aqueous 1.0 x 10-1 mol/L NaClO4 has been studied at pH 2.3 using platinum and glassy carbon electrodes. On the platinum electrode SO2 oxidation occurred on the forward scan at 0.96 V and on the reverse scan at 0.63 V. For GC, a single SO2 oxidation peak occurred at 1.40 V on the forward scan. SO2 oxidation on both electrode substrates was hampered by oxide layer formation. The electrode could be reactivated however, by oxide layer reduction. Although reactivation was most successful for platinum, SO2 oxidation on platinum is quite complex, with this evidenced by the reverse scan anodic peak. Glassy carbon shows simpler behaviour and thus, is the preferred substrate for SO2 oxidation.

Jan 1, 1998

XstrataÆs Mount Isa Copper Operations (MICO) is a world-class mining operation producing in excess of six million tonnes of copper ore per annum from its underground mining operations. The Mount Isa Copper Mines have been producing from the underground operations since 1952. Current copper reserves are 87 million tonnes at 2.8 per cent Cu, extending the mineÆs life beyond 2018. The underground orebodies in the copper mines are divided into nine distinct areas and are mined by sublevel open stoping techniques. One of the nine areas is the hanging wall lens, which consists of two sections; a northern lens (NHWL) and a southern lens (SHWL). The SHWL has a proven reserve of 2.2 million tonnes with an average grade of 2.9 per cent copper. Stopes in the SHWL have an average size of approximately 245 000 tonnes and will be extracted in a primary-secondary mining sequence, producing ore until 2009. This paper discusses various aspects of stope design applied in the southern hanging wall lens, including sequencing options and the rationale for the selected sequence. Design features are also discussed and how they have evolved as more is learnt about the SHWL orebody. These include mass firing techniques, focusing on minimising ground vibrations, using seed wave form analysis and prediction. Rock mechanics issues will also be discussed, in particular the reinforcement of stope hanging walls and the use of instrumentation to monitor behaviour within the hanging wall.

Jan 1, 2006

Timestudy analysis of mining operations at North Broken Hill Limited has been carried out by dissecting operations into small elemental components, and accurately timing these elements. Over a wide range of observations, this has enabled standard time values to be calculated for all underground work.The application of the standard values is in calculating performances as a measure of work output and Performance Controls are kept on approximately two-thirds of underground employees. Through the Controls it has been possible to stimulate supervisory action to improve low performance, and to reduce delays and lost time.The values are used to calculate contract" prices, and anomalies in previous prices have been adjusted on work values and not on arbitrary standards. In out-of-the-ordinary circumstances, the request for a timestudy investigation has been made by both operatives and foremen, and the contract set following the timestudy analysis has been to the satisfaction of both parties.The range of values enables contracts to be applied to work which was previously performed on a day basis, resulting in improved performance.A natural corollary of timestudy is the analysis of methods, and in some cases method improvements have been introduced.It is anticipated that further investigations will be made on methods.INTRODUCTIONIn 1953, a Timestudy analysis of mining operations at North Broken Hill Limited was commenced under the guidance of management consultants. Its aim was, to determine standard time values for specific operations, which would provide management with a measure of productivity beyond the existing measures of tons or feet of advance, and also to determine whether increased output was available under existing operating conditions.

Jan 1, 1956

By G R. Hancock

A common and cost-effective method for post-mining landscapes is to construct linear hillslopes with a break in the hillslope at appropriate distances to reduce hillslope length and resultant erosion risk (Figure 1). The break in slope occurs at a point that has been found by local experience to be appropriate for the materials and climate. Further enhancement of the linear hillslope may be assisted by surface treatment such as ripping (Saynor, Lowry and Boyden, 2019) (Figure 1). Firstly, ripping introduces surface roughness which breaks up flow paths reducing flow velocity thereby reducing erosion potential. The depression produced by the ripping acts as a trap which captures water, sediment and organic matter

Aug 2, 2023

By J Webb

Anoxic limestone drains (ALDs) have been widely used in the passive treatment of acid mine drainage (AMD), but their effectiveness has often been less than anticipated. Iron hydroxide often precipitates around limestone particles and inhibits neutralisation. To determine the conditions under which iron hydroxide precipitates, a small-scale laboratory ALD system was built to enable a detailed examination of the chemistry of iron within the drain. For one experiment, a mixture of limestone and quartz was introduced to the drain to assist in the determination of the key mechanism governing iron precipitation. Synthetic anaerobic acid mine drainage containing Fe2+ (~130 ppm), SO4 2- and H+ was pumped at a rate of 30 mL/min up a 90 cm tall, 15 cm diameter vertical column filled with limestone gravel of 98 per cent purity. Three sampling ports were fitted at equal intervals along the column; water was periodically extracted for analysis at the sampling ports over an 11-hour period. Experiments were run at influent pH levels of 2 and 4. Results show that acid neutralisation to pH greater than 6 occurred at the inflow end of the drain. The greatest amount of iron precipitation (19.5 per cent) also occurred in this area. The lack of iron precipitation on the quartz surfaces in the quartz/limestone mixture indicates that neutralisation is the key mechanism for the precipitation of iron hydroxide on limestone particles. A pe-pH stability diagram derived for the laboratory ALD system indicates that ALDs will not be effective for AMD with pH 2. Influent waters with pH 2 require a pe of -2 (Eh: -118.4 mV) to avoid Fe precipitation upon neutralisation. Influent waters of pH 4 require a pe between -2 and -4.

Jan 1, 2003

A review is presented of techniques cur- rently in use, or being developed, to enable the determination of virgin rock stress at consid- erable depth (> 1000 m) from small diameter sur- face drill holes (

Jan 1, 1975

By G W. Wilson

Rehabilitation of tailings impoundments is one of the most challenging aspects in mine closure, as not only does the potential for producing leachate pose a challenge to the rehabilitation designer, but also other aspects such as stability and settlement must be considered. The water balance of a tailings impoundment is unique in the sense that it usually hosts a pond that in turn causes a phreatic surface in the impoundment. The position of the phreatic surface defines the saturated and unsaturated zones in the impoundment, which of course varies spatially and temporally. Predictive modelling for this hydrologic system becomes difficult, as numerical models capable of analysing the combined saturated/unsaturated zones are not adequately refined to accurately solve the flux boundary problem for infiltration at the surface of the tailings. This paper describes the development of a flux boundary model that enabled accurate modelling of the unsaturated zone in the tailings impoundment at Kidston Gold Mine, Queensland, Australia. The technique made it possible to accurately predict the spatial variation of infiltration to the tailings as a result of the presence of the phreatic table. The conceptual model defines the boundaries for the Kidston tailings dam, based on a generalised cross-section through the dam. Firstly the shape of the top boundary is described as a function of the particle size of the tailings associated with particle segregation that occurs due to the hydraulic placement of tailings. This function was rigorously tested using in situ infiltration tests and laboratory materials testing. Defining the bottom boundary of the section, ie the phreatic level was done by physically monitoring the phreatic level with 42 piezometers strategically located on the tailings dam. Analysis of this data led to the fixing of this bottom boundary through the introduction of a function that mimicked the shape of the phreatic level. The material properties of the surface layer, specifically the saturated permeability that would govern the infiltration/exfiltration rates of moisture through the top boundary layer were defined on the basis of extensive field and laboratory material testing. A function for the saturated permeability was developed on the principles of particle segregation. Finally a procedure is described for the application of the new conceptual model for the evaluation of the spatial infiltration to a tailings surface using the rigorous one dimensional surface flux boundary code SoilCover. The solution of the calculation described above was then used as the top boundary condition in conventional three dimensional saturated/ unsaturated flow codes, and verified against measured seepage rates from the tailings impoundment under drains. It was concluded that the developed spatial flux function was in deed a most rigorous representation of reality. Although the methodology presented here was applied to the Kidston tailings impoundment only, the authors believe that the principles are directly transferable to any tailings impoundment that has a varying phreatic zone thickness due to the presence of a pond. The mathematical equations describing the typical cross-section would be site specific, but the approach and ultimate solution methodology would be directly transferable.

Jan 1, 2003

The complicated mining-geological conditions in the Kuzbass have led to some difficult mining situations in the past. Now, with historical data, supplemented by geomechanical information and measurements, together with an appropriate kinematic theory, a more reliable basis exists for prediction and control of the geomechanical state during extraction, with caving and with backfilling. Continued progress and improving reliability comes from data banks and computations, and now prediction of geomechanical situations is upgraded by more routing measurements and monitoring. Not only in the Kuzbass, but throughout the USSR, 14 dedicated groups are ready to solve various specific problems of prediction an control of geomechanic situations with assured increase in the quality of mining.

Jan 1, 1991

By F R. A Jorgensen, G W. Jensen

A pilot scale experimental investigation of the condensation of zinc vapour from smelter off-gases was performed in conjunction with a mathematical modelling study of the system. The work investigated the feasibility of using the high heat and mass transfer rates associated with a fluidised bed to condense zinc directly from smelter off-gases containing zinc vapour. Of particular interest was whether zinc would revert to zinc oxide during the process of condensation, and whether a zinc fog would form and be carried out of the condenser. A 0.1 m diameter fluidised bed condenser was mounted on the top of a 200 kVA DC electric arc furnace in which mixtures of vapours and gases were generated at 1150 - 1300¦C. The gas/vapour mixtures investigated included Zn/N2, Zn/N2/CO/CO2 and Zn/N2/H2/H2O. Greater than 90 per cent of the zinc was deposited on the zircon sand bed of the condenser, and there was no sign of zinc oxide formation, suggesting that the rate of heat transfer was faster than the reaction rate for zinc oxide formation. There was also no evidence that fog was being formed in the condenser. Using the methods of Kunii and Levenspeil (1991), a mathematical model was developed to predict the behaviour of the fluidised bed condenser. The model enabled the distribution of gas/vapour temperature and bed temperature to be determined as a function of distance from the condenser inlet. Similarly the partial pressure of zinc vapour in the gas mixture, and hence the mass transfer rate of zinc to the particles, was determined. Experimental data allowed validation of the predicted bed and gas/vapour temperatures.

Jan 1, 2000

By T Klinge, P Field, N Sugden, D Trenberth

Mining remains one of the key industries in Australia and many other countries with mineral wealth. In Australia, mining contributes 8.8 per cent to the countryÆs gross domestic product (McKay et al, 2000). In Queensland alone, mineral and petroleum industries contribute approximately $9.4 billion to the StatesÆ gross state product (2001/02) (Young, 2003). Increasing pressure on mining companies to perform in a global marketing environment requires mine management to consider more innovative ways to manage their resources û human, plant and equipment û which includes the gathering and analysis of operations data and information for improved decision making. For any mining operation utilising rubber tyred equipment such as trucks, front-end loaders and ancillary equipment, annual expenditure on tyres and related items can be significant. Even a small reduction in tyre operating costs can have a real effect on the business bottom line performance in the short term. Tyre Application Risk Management (TYREARMÖ) can provide substantial benefits in the long term across a number of KPIs not just through reduction in direct tyre expenditure but through flow-on improvements in safety, productivity and reduced environmental impacts. Several accidents involving tyres have also highlighted an increased need to consider the hazards and resultant risks arising from operations of rubber tyred mining fleets (Torlach and Johnston, 1990). This paper presents the process and results of achieving sustained safety and business improvement through the strategic alliance between an earthmover tyre management service provider, Klinge and Co (Klinge) and a BHP Billiton coal mine. The accompanying case study demonstrates in some detail the overall methodology, and the tools and technologies used where active management of data, its analysis and decisions taken have resulted in a 43 per cent improvement in tyre cost performance and a corresponding reduction in tyre-related downtime since the beginning of the alliance.

Jan 1, 2003

Near Kangiara in south eastern New South Wales, Australia, a number of polymetallic (copper, lead and zinc, with minor silver and gold) mineral deposits occur within a relatively broad volcanic rock belt, intercalated with limestones, sandstones and shales, of Silurian age. The Kangiara deposit was the most significant for the region.Adjacent to the Kangiara deposit, the unaltered country rocks are more rhyolitic than elsewhere in the volcanic rock belt, and the mineralization is accompanied by silicification, chloritization, sericitization and argillization. The host rocks typically contain a higher K20:Na2O ratio than the volcanic rocks not associated with mineralization.In the Kangiara deposit the mineralization consist of massive (in part banded), fragmental, disseminated and vein-type copper-lead-zinc ores, with the massive and fragmental types divisible into pyrite-rich, chalcopyrite-rich and sphalerite-galena-rich varieties. With respect to this mineralogy, the ore textures and sulphur isotope compositions the deposit can be compared to the stratiform mineralization associated with Silurian acid volcanic rocks at Woodlawn, Captains Flat and elsewhere in the Lachlan Fold Belt, as well as the Tertiary Kuroko deposits of Japan.

Jan 1, 1990

By R Heath, P Rose, L Coetser

A sustained eight-year major research effort has been undertaken in South Africa to develop integrated passive water treatment systems for the sustainable removal of sulfates, while simultaneously addressing the removal of metals and acidity. The research effort addressed the problem both at a fundamental science level and at the more empirical pilot plant level. Whereas there are numerous anaerobic sulfate reducing reactors in operation on mine waters that remove some sulfate together with metals and acidity, these are typically plagued by low sulfate removal efficiency and gradual reductions in overall reactor efficiency with time. The South African research effort has focused on understanding the fundamental microbiological and biochemical reactions that occur in anaerobic reactors filled with lignocellulosic material and subjected to high sulfate water. Hypotheses have been developed that differentiate the reactions occurring in such a reactor into groups that should be individually optimised and these hypotheses have been verified through rigorous laboratory and pilot scale studies. The results of this research are incorporated into a patented multi-stage integrated passive treatment system that is capable of sustained high rate removal of sulfates, metals and acidity.

Jan 1, 2003

By A E. C Peres, J D. Donda

With the aim of producing a concentrate with silica content lower than 1.0 per cent SiO2, laboratory experiments were conducted using a sample of the final concentrate from the Samarco iron ore flotation plant (mechanical cells circuit). The sample contained 3.08 per cent SiO2. This sample was split in two size ranges: >105 ¦m and 2. The >105 ¦m fraction, representing 23.3 per cent of the initial mass, was re-ground to 100 per cent 2 content were obtained. Considering the mass proportions of the two size fractions, the calculated silica content of the combined concentrate was 0.68 per cent, which is considered satisfactory for the objective of this investigation. The major reasons for the higher (0.90 per cent) silica content of the concentrate from the coarse fraction are the presence of silicon in the lattice of goethite and the presence of residual silicious slimes in the pores of porous hematite.

Jan 1, 2005

In the 1890s, The Goldfields Water Supply Department in Western Australia commissioned the diamond drilling of two deep artesian exploratory water bores near Coolgardie (Blatchford, 1899). At the time, in spite of strongly-worded advice to the contrary from the Government geologists, there was a wide popular belief that you could obtain artesian groundwater virtually anywhere providing you drilled deep enough. The first Coolgardie hole was drilled to over 900 m, despite the fact that the bore penetrated granite from a depth of 5 m below the surface. Drilling proceeded for more than 16 months, between July 1896 and November 1897. A small quantity of salt water was struck at a depth of 36 m. The second bore was mercifully terminated at a depth of 50 m, also in granite, with again only a small inflow of salt water. Such were the desperate lengths that were pursued to obtain a reliable water supply for the influx of people in the Eastern Goldfields gold rush. The WA Goldfields continued to rely on huge condensers for water supply until that great engineering feat, the construction of a water pipeline from Mundaring Weir to Coolgardie, was completed in 1903. An enormous network of rail tracks penetrated outwards from Kalgoorlie and Coolgardie for the collection of timber, principally to feed the condensers. Remnants of the rail network are still visible today. The acute shortage of fresh water led to great deprivation, disease and death among the early miners. Today, the water problems faced by the mining industry are thankfully not as severe, but they are nevertheless no less challenging. The southern part of the WA Goldfields is a notoriously difficult area for finding potable quality groundwater. Even as recently as the 1990s, there were occasional serious efforts to find potable groundwater in that area, some very imaginative and innovative. One mining company, working south of Southern Cross, spent many months experimenting with recovery of potable quality water from a shallow freshwater lens overlying hypersaline water in a low permeability weathered granite aquifer. They used very low capacity pumps manufactured from car windscreen washer pumps powered by solar panels.

Jan 1, 2000

By Andersson PO

Boliden Mineral AB Boliden Mineral AB operates nine mines in Northern and Central Sweden, producing zinc, lead and silver concentrates and copper and gold. Seven of these mines use cut and fill (C&F) mining with a total production of 2 Mtonnes of ore per year.

Jan 1, 1998

By Wang QP, Quan YH

Mechanical models are established in accordance with the degree of mining on both sides of the coal pillar, and formulae were derived which calculated the superposition stress distribution and the width of the plastic region. The stability of the coal pillar was analysed and a reasonable size of coal pillar determined, in accordance with the elastic region rate. Further practical examples for the stability of the coal pillar are calculated and simulated.

Jan 1, 1992

Magmatism and mineralization are features of the New England Orogen in late Palaeozoic- Mesozoic time. Voluminous silicic and mafic magmatism, both orogenic and post-orogenic in association, was accompanied by abundant mineralization in the earlier phases. Later activity passed transitionally into less vol- uminous felsic to mafic intraplate basaltic volcanism, with possible migratory hot spot activity through the flanking Oxley and Sydney Basins. Only minor mineralization took place at this stage. A new inerpretation links these magmatic and mineralizing events to a major thermal cycle. A New England hot spot(?) complex evolved in latest Carboniferous/early Permian time. Its activity was partly obscured by orogenic magmatism as Australia moved slowly over magma sources in the deep lithosphere. In Triassic time Australia's movement changed direction and faster drift over the waning hot spot complex produced multiple migratory intraplateòactivity. The volume of magma and hence abundance of ancillary mineralization was related to age of the hot spot, speed of the continental movement over thermal sources and extent of accompanying orogenic activity. The New Eng- land Orogen hot spot(?) possibly existed for 165 Ma, with mineralization changing over this Period.

Jan 1, 1987

By Williams RC

Overlying the coal deposits of the Sydney Basin are several lakes and other bodies of water. These include the Pacific Ocean, Lake Macquarie, the Tuggerah Lakes and the stored waters of the dams of the New South Wales Metropolitan Water Sewerage and Drainage Board. The coal beneath these bodies of water amounts to hundreds of millions of tons. Colliery workings have approached these areas of water and in some instances first 1"orkings of bord and pillar have taken place oi_eshh the water. he problem which now faces mine manage- and other interested authorities involves the determination of the maximum ;mount of coal which can be safely extracted from beneath the water. There are many factors to be considered including the depth of cover, seam thickness, geological details and strata movements.

Jan 1, 1972

By Yongjin S

Datong coal Mine suffers from delays and sudden caving of its massive competent conglomerate roof. Detailed geological studies of the nature of pebbles and matrix of the conglomerate and its sparse bedding, joint and fracture structure, gave rise to investigation of water injection to destroy its strength and to control caving. Comparative investigations, including porisity, permeability, compressive strengths and water injection of conglomerate and sandstone led to empirical expressions relating various properties and to guidance for effective injection and caving practice. This new safe roof control practice should be even more improved with further research, including Modelling.

Jan 1, 1992

By Zervoudis J

Limitations of current touch-up solders for galvanised steel include coating thickness control problems and poor corrosion and abrasion resistance as well as health and environmental concerns due to toxic constituents such as lead. This paper reports on progress in ILZRO-sponsored research to develop an improved touch-up solder. Encouraging results were achieved in torch soldering trials with experimental zinc-tin-based alloys. Mouldability and coating thickness control were achieved over a practical working temperature range in which the solders consisted of a viscous mixture of solid primary zinc phase particles in a liquid zinc-tin eutectic matrix. The mouldability was dependent on the microstructure of the solder sticks, and optimum structures could be obtained through control of casting solidification rates and by the addition of small amounts of copper. Hardness, abrasion resistance, adhesion and corrosion tests on experimental Zn- (40 - 50 per cent) Sn-I per cent Cu also showed improved performance over lead-tin-zinc solders and compared the effects of tin content within this range. Atmospheric corrosion testing and optimisation of alloy composition and methods of solder stick production are continuing.

Jan 1, 1993