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By N J. Beukes, S T. Netshio, M O. de Kock

The Thabazimbi iron ore deposit comprises a series of stratabound orebodies, on average 18 - 25 m thick that are aligned along the faulted basal contact between the Penge Iron Formation and dolostones of the Malmani Subgroup, Transvaal Supergroup. Field geological relationships and petrographic observations suggest that the formation of high-grade iron ores took place after contact metamorphism related to the intrusion of the Bushveld Complex (2.06 Ga) but before the deposition of red beds of the Waterberg Group at ca 1.9 Ga. Hard, high-grade iron ores are predominantly composed of martite and microplaty hematite. Goethite is restricted to supergene-modified ores close to the Late Cretaceous û Early Cenozoic Old African land surface. At depth, the high-grade hematite ores interfinger with low-grade dolomite-hematite and calcite-hematite ores. Iron oxides (martite, microplaty hematite) present in these low-grade ores are texturally indistinguishable from those in the associated high-grade ores, ie ore formation is genetically associated with carbonate metasomatism. Microthermometric studies of fluid inclusions in sparitic carbonates and rare megaquartz reveal their hydrothermal origin. Two compositionally distinct aqueous fluids of shallow crustal origin are identified, namely a Ca-Na-rich high-salinity brine (26 wt per cent NaClequivalent, TH ~160¦C), and an aqueous Mg-K-bearing fluid of intermediate salinity (8.3 - 12.6 wt per cent NaClequivalent, TH~120 - 150¦C). The results confirm that high-grade hematite orebodies at the Thabazimbi deposit owe their origin to an event of extensive oxidative carbonate metasomatism (calcification), similar to that recognised at other important high-grade iron ore deposits in the world. Hydrothermal ore formation is both structurally and lithologically controlled. Size and quality of the orebodies was improved by Late Mesozoic-Cenozoic deep lateritic weathering as carbonate-hematite ores were enriched to friable high-grade ores, but this supergene modification is second in importance compared to the primary event of hydrothermal ore formation.

Jan 1, 2005

By J P. Jona, S R. Poulson, C H. Gammons

Spatial and temporal trends in water chemistry in the acidic (pH ~2.6) Berkeley Pit lake, Butte, Montana, can be explained by a newly developed iron-cycling model. Key elements of this model include: subaqueous oxidation of pyrite and other metal sulfide minerals by dissolved ferric iron, producing Fe2+ as a by-product; re-oxidation of Fe2+ to Fe3+ in the epilimnion, assisted by A ferrooxidans; precipitation of secondary ferric minerals (schwertmannite, jarosite) in the epilimnion; and replenishment of the Fe3+ concentration of the hypolimnion by seasonal lake turnover and gravitational settling and re-dissolution of ferric precipitates. Pyrite oxidation rates were approximated by using published rate laws and information on the Fe3+ concentrations (~5 mmol) of the Berkeley Pit as a function of depth. The results indicate that subaqueous pyrite oxidation may be releasing as little as 6 + 106 or as much as 600 + 106 moles of H+ each year to the lake; the large range reflects uncertainty in calculation of the specific surface area of pyrite in the flooded pit. This helps to explain the observation that the pH and metal concentrations of the Berkeley Pit have not improved with time since mine flooding began in 1983. Vertical cycling of ferric iron in the pit lake permits pyrite oxidation to continue in deep water, even in the absence of dissolved oxygen. This hypothesis is supported by preliminary stable-isotope data.

Jan 1, 2003

By Woodcock J. T, Zhu T, Sparrow G. J

A lead-zinc-pyrite flotation middling was pressure oxidised to give residues containing iron hydroxy sulphates (a mixture of basic iron sulphate (BIS) and a hydrated iron sulphate (HIS)) and lead sulphate. Direct thiourea leaching of this residue gave over 90 per cent extraction of gold and silver, but thiourea consumption was high (56 kg/t) because of soluble iron(M) in the residue. Attempts were made to decrease the thiourea consumption by removing the water-soluble iron(M) or reducing it to iron(II). Water washing of the pressure oxidation residue removed most of the hydrated iron sulphate but little of the basic iron sulphate. Iron removal was only 12-20 per cent, depending on the number of washes, from one sample which was low in HIS, and 40-45 per cent in another which was high in HIS. Iron extraction was not appreciably increased by using dilute sulphuric acid (with or without additions of sodium sulphite), dilute phosphoric acid, or sodium chloride solution (150 g/L NaCI). Direct thiourea leaching of the water-washed residue gave over 90 per cent extraction of gold but only 49 per cent of silver, with a thiourea consumption of 27 kg/t. However, the application of a water wash followed by reduction of dissolved iron(III) with sodium sulphite in the presence of thiourea, and then thiourea leaching resulted in over 98 per cent extraction of gold and silver for a thiourea consumption of 26 kg/t.

Jan 1, 1991

The Kelian gold mine which was developed in East Kalimantan Indonesia in 1990 - 1992 is scheduled to complete mining and processing operations in 2004. This will have a major impact on the neighbouring communities who have benefited from the jobs, economic activity and infrastructure development which has been generated by the mine. Currently, there are no formal regulations or standards specifying the procedures for relinquishment of mining leases in Indonesia. Furthermore, a move towards regional autonomy, providing greater authority and responsibility to local (regional) areas, has recently been implemented in Indonesia and limited capacity exists in the new regional governments. Consequently, in October 2000, Kelian Equatorial Mining (KEM) initiated a partnership with the local community and government to explore sustainable post-closure options for the mine site and community development programs. The Kelian mine closure strategy seeks full involvement of all stakeholders through the Kelian Mine Closure Steering Committee (MCSC) in the development of sustainable solutions which will enable communities to secure long-term benefits and minimise post-closure risks from the KEM operations. This organisation, jointly chaired by the Head (Bupati) of the regional West Kutai government and the KEM President Director, with representatives from the local communities, governments and NGOs, has developed a Charter, a website and evaluation criteria to ensure accountability and transparency. There are four technical working groups, consisting of representatives from the mine, local community leaders, NGOs, Universities, Local, Provincial and Central Government Departments, which report to the Steering Committee. These working groups have researched, developed and recommended sustainable options to the Steering Committee. The MCSC has met quarterly to examine options in accordance with the criteria set out in the Charter and has endorsed sustainable solutions which have support from Government, Community and the mine. This paper describes the closure risks, sustainable outcomes derived through the Kelian mine closure steering committee process and outlines the methodologies used to develop and endorse sustainable solutions in a society with limited capacity undergoing enormous change and uncertainty.

Jan 1, 2003

This paper explores the use of a Process Safety Management (PSM) system to manage risk in the mineral processing and metallurgical refining industries. Important elements of a PSM system are described. International regulations and non-regulatory guidelines covering PSM for high hazard industries are reviewed. Case studies of incidents in the mineral processing and metallurgical refining industries are presented to understand the lessons learned from failure to manage risks using a PSM system. Conclusions are drawn to adopt PSM in the minerals and metals processing industry as a tool for loss prevention and risk management.

Jan 1, 2003

By Z Li, Z Yan, T Htet, S Zhang

During the pyrometallurgical processes, a substantial quantity of high-temperature ironmaking and steelmaking slags, generated at temperatures ranging from 1400 to 1600°C, is wasted, as the heat contained in these slags is released into the environment during the tapping process without effective utilisation. On the other hand, a significant amount of energy is required to reheat the cold materials for the manufacturing of glass and mineral-wool, often necessitating the addition of high-silica materials to facilitate the production process. In this study, an innovative approach is presented to harness the heat present in molten metallurgical slags to directly produce new raw materials for glass and mineral-wool manufacturing while simultaneously reducing energy consumption and mitigating CO2 emissions. The theoretical amount of waste glass that can be effectively added in the process has been estimated via thermodynamic calculation. Experimental assessments were conducted to examine the impact of high-silica waste materials on the dissolution, melting and fluidity. Potential recipes for glass and mineral-wool manufacturing were suggested and an assessment of the energy savings, and reduction in CO2 emissions with manufacturing of glass and mineral-wool using this innovative approach were included. It was determined that the processes could lead to a reduction of over 26 kg of CO2 emissions per 100 kg of new material used, primarily due to the utilisation of heat from slag and the accelerated smelting process.

Aug 21, 2024

By Mahyera A, Sakashita B, Ahmed U, Abou-Sayed AS

Gas in U.S. coals is primarily composed of 90 to 99 percent methane and up to 10 per- cent carbon dioxide. In composition and heat- ing value, this coal-bed gas is similar to natural gas and can be introduced directly into commercial pipelines after standard condition- ing. The high permeability cleat system in the virgin coal can be exploited in order to drain the coal gas well in advance of mining. Two premining drainage methods have been extensive- ly evaluated in the U.S.; they are 1) horizon- tal boreholes collared from within the mine, and 2) vertical drilling from the surface with fracturing. Limited-size fracture treatments are advocated in order to prevent potential roof damage and the need for added support. An engineering approach to predicting gas flow for different drainage techniques near mining locations is presented. Results can be used in design, i.e. pipeline, compressor. Coal gas drainage from a horizontal borehole and a treated (contained fracture) vertical well for a 6 foot seam have been evaluated. Based on these results, it was concluded that selection of gas drainage techniques will depend primar

Jan 1, 1982

By A Parry, C Fitzmaurice

After conducting laboratory ore sorting testwork on samples of a low grade nickel ore stockpile at Western Areas’ Flying Fox nickel mine, a mobile crushing, screening and ore sorting plant was located adjacent to the stockpile. An initial two month trial of the ore sorter program proved successful and was extended to process the entire Flying Fox low grade stockpile in a further four month campaign. A total of 167 660 t of low grade ore was processed, providing highly upgraded feed trucked 26 km to the Cosmic Boy concentrator. A more than three-fold grade increase was achieved on ore sorter accepts. The moderately upgraded fines that by-passed the mobile ore sorter were also subsequently blended into plant feed. This paper describes the mineralogy of the Flying Fox low grade ore, the mobile ore sorting campaign and provides some commentary on the economic and environmental benefits achieved in the ore sorting campaign. The ore sorting campaign demonstrated the benefits of being able to utilise mobile ore sorting equipment temporarily located adjacent to sub-economic low grade stockpiles in order to effectively treat these stockpiles and produce viable plant feed.CITATION:Parry, A and Fitzmaurice, C, 2018. The upgrading of low-grade nickel ore stockpiles at Western Areas Ltd Forrestania operations, using a mobile ore sorting plant, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 541–550 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By M Chen, G H. Wang, J R. Zhou, P Yan, W B. Lu

Blast vibration analysis is one of the important topics in the control technology of blast vibration damage. Nowadays, blasting vibration safety standards are based on both the particle velocity and the frequency of vibration and they have been adopted widely and internationally. However, the analysis on vibration frequencies is less studied compared to investigations of peak particle velocity. For the vibration induced by a spherical charge in a viscoelasticly infinite rock mass, an expression of vibration spectrum taking into account the damping effect of rock mass is inferred. Then the attenuation laws of dominant frequencies and centroid frequencies are compared theoretically. For the case of cylindrical charge, dynamic finite element method (DFEM) software of LS-DYNA is employed to analyse the attenuation laws of characteristic frequencies. The research demonstrates that, no matter whether it is a spherical charge or a cylindrical charge, there is a local mutation or fluctuation at some distance when the blast proceeds, while the centroid frequencies conform to a smooth attenuation law. Both the multipeaks structures of vibration spectra and the decay rate difference between high- and low-frequency components contribute to the mutation or fluctuation investigated in this study. Additionally, an increase in longitudinally sonic velocity or the quality factor of rock mass produces an increase in the vibration frequencies, whereas an increase in blast source diameter or the rise time of blast load produces a decrease in vibration frequencies from a spherical charge. In borehole blasting, there is a positive correlation between the vibration frequencies and charge diameter, whereas there is a negative correlation with charge length. And altering the initiation plan will change vibration frequencies to various degrees. Finally, theoretical analysis results were validated by the empirical data from field experiments of Fengning pumped storage power station.CITATION:Zhou, J R, Lu, W B, Chen, M, Yan, P and Wang, G H, 2015. A further study on the attenuation laws of blasting vibration frequency, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 673–682 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

This paper covers only the energy uses of natural resources and does not deal with non- energy uses, which in 1975 were of the order of 10 per cent of the total consumption of energy resources. The United Nations `J' Series of Statistics ex- presses each of the various forms of energy in terms of its coal equivalent in metric tonnes and this basis is followed in this paper. One tonne of black coal (referred to as tce) has been taken as the equivalent of the following. 29 X 109 joules or 27.5 X 106 Btu 0.68 tonnes or 4.8 barrels of crude oil 750 cubic metres or 26.5 X 103 cubic feet of natural gas 1 ò5 to 3.3 tonnes of peat or lignite (world average 2.54; Victorian brown coal 3 0) 8055 kWh (at 3.6 X 106 joules or 3412 Btu per kWh at 100% efficiency) 2660 kWh at 33% efficiency of generation 50 grams of uranium present in natural uranium reactors (see note later under nuclear energy) 0.8 grams natural uranium in breeder reactors Nuclear and hydro electricity are expressed as the coal equivalent required to produce, at 33 per cent efficiency, the same amount of electricity. In other words, electricity produced by these sources is converted to its coal equivalent at the rate of 2660 kWh = 1 tonne coal.

Jan 1, 1978

By J T. Sharp, M A. Styler, D McGowan, P W. Mayne

Static liquefaction is a geotechnical hazard in mine tailings facilities. Soils that are contractive in shear are susceptible to static liquefaction. Tailings facilities are dynamic structures, typically growing in height each year. Dilative tailings may become contractive under increased effective stress. In this paper we show that Cone Penetration Test (CPT) data can be used to estimate the future state of in-place tailings under changes in effective stress. Susceptibility to static liquefaction is typically evaluated with the CPT by using a clean-sand equivalent normalized cone tip resistance (Qtn,cs) or by estimating the state parameter (?). An alternative approach is to evaluate the soil-state using the yield-stress-ratio (YSR = ?’y/?’v0). If the YSR equals one it is on the normal consolidation line and the soil-state is contractive. YSR values greater than three are typically dense of the critical state line (CSL) and the soil-state is dilative. In this paper we review how to calculate Qtn,cs, ?, and ?’y; and how the YSR can be used to screen for contractive soil behaviour. Unlike Qtn,cs and ?, it is very simple to estimate how the YSR will change due to an increase in overburden stress. This YSR approach was evaluated at three locations that saw increases in overburden of 10 m, 20 m, and 25 m. We show that the ?’y calculations are consistent and the increase in effective stress moves the soil state towards looser soil states. CITATION:Styler, M A, Mayne, P W, McGowan, D and Sharp, J T, 2018. Predicting changes in static liquefaction susceptibility using cone penetration test results, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 317–332 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018

Since the 1950's drilling has been rapidly mechanised. First from hand held drills with air legs to pneumatic jumbos, then to more effective hydraulic jumbos. Development of underground drilling equipment naturally could not have stopped here. Hydraulic drilling saw an improvement in drilling capacity and efficiency after the introduction of second generation drifters in the early 1980's. Also in the early 1980's a few equipment suppliers started to study how to improve the efficiency in operating the rigs. The first computerised rigs for tunnelling were delivered to work sites in mid 1980's. At the same time a few computerised longhole drills started drilling in mines.

Jan 1, 1988

By A Singh, C Da Corte

Banded Iron Formations or more commonly known as BIF are sedimentary rock formations with alternating silica-rich layers and iron-rich layers that are typically composed of iron oxides (hematite and magnetite), iron-rich carbonates, and/or iron-rich silicates. Considering the depletion of highgrade iron ore reserves in South Africa, there is a need to maximise resource utilisation through the exploitation of sterile resources in particular BIF material which makes up greater than 65 per cent of current reserves. BIF, like most resources, is non-renewable and the deposition of BIF is thought to have come about by the reaction of Fe2+ ions in the ocean water with dissolved oxygen billions of years ago. BIF ore derived from the Limpopo region in South Africa (SA) located in the Penge Iron Formation is according to Cairncross, Kramers and Villa (2018) equivalent to that contained within the Asbestos Hills Iron Formation of the Transvaal Supergroup in the Northern Cape, SA. Considering that these are one of the largest iron ore deposits in SA, the case study involved mineralogical characterisation followed by beneficiation of BIF from these two regions to ascertain the comparability. Coarse and fines gravity separation comprising of Heavy Liquid Separation/Dense Media Separation on the +1.18 mm size fraction and shaking table on the -1.18 mm size fraction was conducted to ascertain whether an on-grade product or blended feedstock could be produced. The Limpopo mixed and Northern Cape conglomerate BIF samples achieved similar overall responses due to the conglomerate sample containing 15.3 per cent additional -1.18 mm fines. A combined coarse and fines product grading at 60 per cent Fe could be achieved at a yield and recovery of 43.9– 53.0 per cent and 62.2–63.8 per cent respectively. Increasing the grade to 63 per cent Fe reduces the overall recovery by 13.3 per cent. At the higher target grade, the contaminant specifications could be achieved for both samples. The Northern Cape laminated BIF sample is the most promising of the three samples studied. At the two iron target grades overall yields and iron recoveries of 72.9–65.4 per cent and 85.2– 80.2 per cent was achieved. In both instances the silica grade exceeded the product specification, however if the silica content is the driver the target iron grade should increase to 63.32 per cent. This will result in a minimal decrease in recovery of 0.4 per cent. The promising results of this study indicate that coarse beneficiation of BIF material is possible. These ore types could be blended with superior grade products to improve overall yields and recoveries or sold directly at a 63 per cent Fe product grade whilst sacrificing 0.4–13.3 per cent recovery.

Nov 8, 2021

By Coulter L. J

THE method of stope surveying as practised at the Mount Lyell Company's mines has been evolved out of the exigencies created by special conditions. It presents some novel features, and has proved effective for all requirements. All stope measurement work is brought under one complete system, to which office methods are standardized. Before proceeding to deal with the subject a brief description of the physical characteristics of the ore-bodies of each mine and the method of stoping will serve to show, cause ,for departure from ordinary survey practice.NORTH LYELL MINEThe ore-bodies of this mine occur on or near the conglomerate schist contact, and, being probably the result of replacements of both rocks, they rarely present any definite walls. It is usual for the payable material to merge into the respective countryrocks, and the limit of the occurrence is defined rather by assay value than by any distinct natural boundaries. The general configuration of these ore-bodies, therefore, is highly erratic both in horizontal and vertical section, so that, in order to obtain an accurate record of any occurrence, the measurement of the actual contour at short vertical intervals is essential.Stoping is carried out on a modification of the "rill." system, perhaps more properly described as "arched back" or "dome" stoping. Mullock rises are placed in as convenient positions as the erratic configuration of each ore-body will allow, and aroundthese rises the back is kept well arched, both longitudinally and transversely. The larger stopes are divided into arbitrary sections in which ore-breaking and mullocking are carried out in rotation, so that the whole of the excavation is seldom open for measuring at anyone particular time. Stacking or square-setting on the...

Jan 1, 1915

By Jones JJ

A laboratory study of size segregation is described using a model of a Paul Wurth hopper industrailly employed for blast furnace charg- ing purposes. Experimental charge materials used in the study were glass ballotin.i (1-4mm dia.) and sinter fines (0.25-4mm). The tracer material employed consisted of coloured glass beads. The results of the study show that the discharge stream from a Paul Wurth hopper is characterised by an initial negative segregation followed by a positive segregation and that this segregation pattern is a property of the hopper geometry and the filling conditions. A simple computer model based on experimental tracer concentration results is proposed. The measured segregation results and those predicted by the model show close agreement. Application of the results with special reference to the effect of size segregation on charge permeability in blast furnaces is also included.

Jan 1, 1984

Teleseismic travel time residuals measured on 600-1000 km seismic arrays across the Rio Grande and East African rifts provide evidence for upper mantle low velocity zones beneath each rift of velocity contrast 6%-8%. Refraction studies show thinning of the crust below the rift axes. Regional uplift which extends hundreds of km either side of the axes, is isostatically compensated by negative density contrast at depth. Since the refraction argues against compensation by thickened crust, compensation in the upper mantle low velocity zones is suggested. Temperature effects alone can not explain the reduced velocities. Generation of a few percent of partial melt is the most probable source of the reduction. A passive extensional mechanism is investigated for the Rio Grande rift in which hot asthenosphere intrudes the lithosphere raising its temperature and generating moderate melting. It requires less than 1% extension to explain the melting but a prodigious 26% to raise the temperature from a pre-rifting continental geotherm to the solidus. Geological estimates find that extension is less than 10% over the uplift zone. Such a mechanism is possible only if the prerifting lower lithosphere geotherm lies closer to the solidus than that of stable continent. This is supported by the observed high heat flow in the Rio Grande rift uplift region which, given the long time constant for thermal diffusion, reflects elevated temperatures at depth well in advance of the onset of rifting.

Jan 1, 1987

By Jarvensivu M, Ylinen R, Jamsa-Jounela S-L

The paper presents a new integrated system for control of concentration processes. The system is based on cluster-based modelling taking the ore quality into account and a new on-line particle size analyser capable also for reliable measuring of particle size distribution of concentrate. A metallurgical precontrol audit was performed at the Hitura concentrator in order to design the control strategy of the integrated grinding and flotation control. A new analyser PSI-200, was used to the measurement and control of the distribution of nickel in the total particle size range. An expert control system using the cluster model together with a new control strategy for decision of necessary control actions is outlined. The method has been tested to real data from mineral processes. The results are in good correspondence with empirical process knowledge. KEYWORDS: Cluster analysis, expert control, flotation control, mineral processes, modelling, particle size.

Jan 1, 1993

The Australian Coal Combustion Testing and Research Facility has been operating commercially for one year and during that period coal product evaluations have been conducted on behalf of four coal companies and one electricity commission. The facility is equipped to assess the behaviour of steaming coal in milling, combustion (including flame stability, burnout and heat transfer), ash deposition and erosion, fly ash collection and gaseous emissions. The relevance of the results of the pilot testing to industrial practice was demonstrated during the calibration of the facility using four coals burnt in Australian power stations. The calibration coals were from the Tarong and Gladstone Power Stations in Queensland, tluja Power Station in Western Australia and Bayswater Power Station in New South Wales. Also an opportunity arose to visit an overseas power station to observe a full scale test burn using one of the early coals tested on a commercial basis in the combustion test facility. The calibration trials showed excellent agreement with industrial coal performance in t:orms of flame stability, turndown, carbon burnout and gaseous emissions. Encouraging correlations were also found in the case of furnace radiation, boiler deposits (slagging and fouling) and electrostatic precipitation. In the case of the last group the only real reservations about the correlations are due to the non-availability or qualitative nature of results collected around the power stations. In all cases there is a high degree of confidence in the facility's ability to predict the relative performance of different coals and in some cases direct numerical predictions can be Made.

Jan 1, 1987

By Rowlands N. J, Zimmermann D. O

The Engel Model search simulator is described with particular emphasis on preparation of input parameters. The computer has a "black box" role in the same way a telephone or radio is a "black box" in communications. A search technique (sensor) is selected and applied in two stages of'search, namely, reconnaissance and detailed. The model relies on knowing and quantifying the parameters of the target sought and the search technique; this is usually done by analogy studies from available literature and experience. The parameters are then balanced by feasibility studies on the search area. Case histories show that the study makes the user aware of what he is likely to find rather than what he wants or needs to find to be viable. Two case histories are presented: one for Mississippi Valley type lead- zinc deposits and another for stratiform copper. The first study showed particular benefits in the input stage and highlighted the fact that one could expect a lot of encouragement by way of interesting results but with little chance of finding the high-grade,

Jan 1, 1974

The hydraulic backfilling of mine tailings has proven very successful at the Homestake Mine in Lead, South Dakota. It allows greater versatility, selectivity and safety in mining. It has also minimized surface subsidence and underground rock movement. The tight filling also eliminates underground fires. This paper explains the hydraulic backfill method used and the problems encountered by so doing.

Jan 1, 1973