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By C Philander

The West Coast of South Africa is well known for its placer gem quality diamond deposits and also associated with these hosts of Cenozoic unconsolidated marine and aeolian sand and gravel are significant concentrations of heavy minerals. Exploration for economic concentrations of zircon, ilmenite and rutile along the coast started in the mid-1980s. This resulted in the discovery of an inferred 1.6 billion tonne resource with a grade of ten per cent total heavy minerals (THM), which developed into the Namakwa Sands Mine, a world-class producer of heavy minerals. Several other resources, including satellite deposits proximal and distal to the mine area, extensive diamond mine dumps and present day beach placers, demonstrate the vast heavy mineral potential along the West Coast. The favourable gangue to economic mineral ratio, a higher zircon content compared to other similar deposits, relatively lower U+TH content of zircon, low slimes content and effectively pristine low chromium-manganese ilmenite of these deposits, render them attractive exploration targets. Negative factors that will affect conventional mineral beneficiation and liberation include secondary mineral coatings and the regional coastal development of several layers of superimposed duricrust. The economically attractive heavy mineral assemblage along the West Coast is the result of erosion of the proximal, gneissic Namaqualand Metamorphic Province and mature Table Mountain Group sandstone, concentration by marine and aeolian processes and preservation under arid climatological conditions over a period of more than 100 Ma.

Jan 1, 2008

By D Van Doorselaere

The purpose of blasting during mining is to produce a muck pile that can be efficiently loaded and transported. There is an increasing awareness of the variation in muck pile characteristics and its economic implications. It is well known that good fragmentation by itself is not sufficient to optimise the muck loading efficiency. The swelling and configuration of the muck pile also significantly affect the productivity of the loading equipment. The characteristics of a muck pile depend upon the blast design parameters, explosive properties and rock mass geology. This study has focused on the dependence of muck pile configuration on blast design parameters, explosive properties and size distribution of the muck.The field work was done in two phases. In the first phase 12 blasts were monitored, while in the second, three blasts were monitored. The blast design parameters and explosive properties for each blast were documented and the following muck pile characteristics were measured:muck pile height and its distance from the facedistance of throwwidth of the power troughsize distribution by image analysis technique.The effects of burden, bench height, heave energy of explosive, row-to-row delay, powder factor and the mean particle size of the fragments on muck pile configuration were examined. It was observed that muck pile height and distance of throw are strongly influenced by the burden, bench height, heave energy of the explosive and the size distribution of the muck. The width of the power trough depends upon the row-to-row delay, powder factor and total burden. In addition, the effect of the fragment size distribution on the muck pile parameters has also been discussed.CITATION:Singh, S P and Van Doorselaere, D, 2015. The relationship between blasting parameters and muck pile configuration, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 369–374 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By M Wortley, A Cantarutti, G J. Clarke, C

As part of a broad program to optimise the performance of their grinding circuit, BHP Billiton Cannington have installed an OCS¬ Expert system together with three VisioRockÖ online particle size analysis cameras. The main purpose of the system is to stabilise grind size and feed to the flotation circuit. This particular application of OCS¬ is the first installation to incorporate Metso Minerals Process Technology-Asia PacificÆs (MMPT-AP) Dynamic SAG/AG Mill Model, which is able to predict numerous mill parameters that were previously unable to be measured with the existing plant instrumentation. Integrated into the logic of the control algorithm are online vision based, particle size measurements of the AG mill feed and recycle crusher product. This paper will describe the history of the project from initiation to date, the model and OCS¬ logic configuration, and demonstrate the significant benefits realised at Cannington mine.

Jan 1, 2007

With mining development on hold and other underground works in a slowdown, the development of nuclear wa te repositories takes centre tage on the American rock engineering scene. Three repositorie for commercial spent fuel-in salt, tuff, and basalt-are in the phase of site characterisation and conceptual design, and one pilot project for defense high-level wa te in salt is under construction. A repository design for crystal line rock has recently been postponed.Because of strict quality assurance requirements throughout design and construction, and because of the need to predict and ascertain in advance the satisfactory performance of the underground openings, much intellectual energy has been expended to analyse underground openings in the unusual circumstances of the repository environment. In the long term, these efforts will lead to an improved understanding of rock behaviour and improved methods of underground analysis and design. For the shorter term, a formalised ground control plan was developed, the principles of which may be applied to other types of projects.This paper summarises the status of underground design and construction for nuclear waste repositories and presents some details of the ground control plan and its individual elements.

Jan 1, 1988

Experience in evaluating grade control at operating mines has shown that a number of similar errors re-occur in diverse settings. These can be broadly classed as technical errors, and procedural or grade contra management errors. Examples of typical errors are presented a; generalised case studies. A brief explanation of why the recommender solution worked is also presented for each case.

Jan 1, 1993

By P Ireland, S Mitra, G Evans, A Wang, M M. Hoque

This work presents an experimental study of flow dynamics in a bubble column system (crosssection: 100 mm × 100 mm) using a non-intrusive optical technique with targeted application in a novel REFLUX™ Flotation Cell. The study had two aims – measurement of the bubble size distribution (BSD) and local energy dissipation rate in the system due to bubble motions over a low range of gas flux varied from 0.02 to 0.08 cm/s without impairing the visibility of the system. A central bubble plume was generated by injecting compressed air through a sintered glass distributor in quiescent liquid. Highspeed shadowgraphy imaging was performed to determine the BSD in the presence of surfactant (Sodium Dodecyl Sulfate (SDS) concentration ~ 10 ppm). The BSD exhibited a unimodal shape at different locations of the column for all gas flux cases. A non-intrusive particle image velocimetry (PIV) technique was used to quantify the flow field generated by the bubble motions, which was used to estimate the local energy dissipation rate. The local energy dissipation rate exhibited an increasing power-law dependency on the gas flux.

Aug 24, 2022

Caving is the lowest cost underground mining method, provided that drawpoint spacing, drawpoint size and ore handling facilities are designed to suit the caved material and that the drawpoint horizon can be maintained for the draw life. In the near future several open pit mines that produce in excess of 50 000 tons per day will have to examine the feasibility of converting to low cost, large scale underground operations. Several other large scale, low grade underground operations will experience major changes in their mining environments as large dropdowns are implemented. These changes demand a more realistic approach to mine planning than has occurred in the past, where existing operations have been projected to increased depths with little consideration of the change in mining environment that will occur. As economics force the consideration of underground mining of large, competent orebodies by low cost methods, the role of cave mining will have to be defined. In the past caving has generally been considered for rock masses that cave and fragment readily. The ability to define cavability and fragmentation, the availability of large, robust LHDs, a better understanding of draw control requirements, improved drilling equipment for secondary blasting and reliable cost data have shown that competent orebodies with coarse fragmentation can be exploited by cave mining at a much lower cost than with drill and blast Methods.

Jan 1, 1995

By A Logan, B Cuthbert

Brown and Chitombo (2007) indicated that during the last two decades, the international mining industry has been using mainly mass mining methods to extract safely and economically some of the important commodities such as copper, diamonds, gold, iron and nickel. Mass mining may be implemented either on the surface through large open pits or underground using mining methods such as sublevel, block and panel caving. Developments in the last ten years have demonstrated that caving methods can be applied successfully in strong orebodies at greater depths and in increasingly challenging geotechnical environments for which more traditional mining methods would be unsuitable, unsafe and/or uneconomic. These underground mass mining challenges require æfront endÆ investigation and analysis, robust engineering design and disciplined implementation and operation. Newcrest Mining Limited has focused its efforts on the development of gold/copper projects of substantial scale and margin. To help achieve this, the company is applying and further developing mass mining methods. These include large-scale open pits (OP) and underground mining methods such as sublevel (SLC), block (BC) and panel caving (PC). Block and panel caving now offer economies of scale opportunities for Newcrest to achieve high production rates at lower production costs; thus enabling the exploitation of mineral endowments at higher margins. This paper discusses the practical aspects of caving technologies that Newcrest continues to develop through its expertise at Telfer and Ridgeway SLC operations, Ridgeway Deeps BC and Cadia East PC projects.

Jan 1, 2008

The originally estimated mine life at Kidston (starting 1984) was 12 years. Through a continuing process of re-evaluation and improvement in the operation and by expanding the geological knowledge in the region, the mine life has been considerably extended. With falling grades and harder ore, the additional reserves have come with increasing risk - not only in an economic sense associated with diminishing profit margins but also operationally, requiring innovative milling technology and geotechnical designs to provide a lower cost environment for continued profitable mine production.

Jan 1, 1994

By Jones BH

Discovery of the Vera-Nancy deposit in late-1995 followed 12 years of active exploration in and around the Pajingo Epithermal System, an andesite hosted veinfield covering an area of 150 square kilometres at the northern end of the Devono-Carboniferous Drummond Basin in North Queensland. Early exploration targeted open-pittable resources in the numerous auriferous veins and it was not until 1994 that exploration focus shifted to drilling to depths below about 100 metres from surface, which resulted in the Vera-Nancy discovery. That deeper drilling process is still at a very early stage of coverage of the epithermal system as a whole and substantial potential exists for additional discoveries.Drill-out of Vera-Nancy has to-date established a gold resource in excess of 1.4 million ounces. Mine development is proceeding via a twin decline system with first stoped production scheduled for August 1997.

Jan 1, 1997

Recent work has shown that, in at least some instances of regional metamorphism, metamorphic diffusion has been restricted to such relatively minute distances (of the order of 1.0 mm and much less), that there is no clear, direct evidence of prograde metamorphic mineral reactions, and that metamorphic equilibrium does not appear to have been attained through even very small domains.A number of stratiform orebodies and their immediate metapelitic environments exhibit very large, seemingly "disequilibrium", assemblages of regional metamorphic index materials. One such, in north-eastern Australia, includes laumontite, prehnite, chamosite, stilpnomelane and related hydrous iron silicates, primary chlorite, sericite-muscovite, epidote, actinolite, biotite, almandine, andradite, metamorphic hornblende and clinopyroxene, scapolite, staurolite and sillimanite, all within a 20 metres length of a single diamond drill core. In this and several related occurrences it appears that metamorphism has involved very small scale in situ transformation of pre-existing materials rather than large-scale diffusion and reaction, and hence that the observed metamorphic minerals have probably been derived directly from precursor materials of sedimentary/diagenetic origin.It is concluded that the fluctuating seafloor interplay between warm, acid, concentrated hydrothermal waters with cold, alkaline, dilute seawater during stratiform ore formation, together with diagenetic processes, leads to the formation of a wide range of clay, chlorite, mixed-layer clay and clay/chlorite, and zeolite precursor materials and hence, later, to the complex assemblages of metamorphic minerals closely associated with some stratiform ores. Commonly included in highly localized assemblages of this kind are various minerals which, in conventional regional metamorphic studies, are generally regarded as indicating widely different grades of metamorphism.

Jan 1, 1982

Traditional techniques for extracting pillars in thick underground coal seams in India are reviewed. Problems encountered are principally control of roof strata and low recovery. Recently developed mechanized methods and projected newer techniques are discussed.

Jan 1, 1986

By Polthier K

A short discussion of the salient aspects of a dispersed flow model in relation to the gas flow in blast furnaces is given. The use of the theory in assessing vessel performance is mentioned. Tracer results of a blast furnace (688 m3) from three furnace levels and different radial positions are analysed and results presented as D/ud values. The significance of the shapes of experimental tracer curves are included and comparison is made with results obtained on other furnaces.

Jan 1, 1975

By Chappel R. A, Fishburn B. R

The Eastern Distributor Tunnels - the first major road tunnel project in Australia - are the preferred solution to traffic congestion problems, when compared with alternatives, in this inner urban environment. This is because of the reduced impact on residential housing, the improvement of the existing environment, less restrictions on future developments, and a reduction in noise and pollution. Developments leading to a tunnelled solution, traffic needs and reasons for route location are discussed. Criteria for design of tunnel alignments and geometry are described, including the restraints imposed by surface connections on profiles and grades resulting in low rock cover at tunnel portals. The main geotechnical restraints are a major weathered dyke at the shallow large span underground fork and the weathered Ashfield Shale capping the Hawkesbury Sandstone at a portal. Rock cuttability and excavation methods are discussed. Roadheader machines are the most suitable for the varying shallow arched cross sections required and the tunnel lengths involved but the use of blasting in special situations cannot be ruled out. Initial support for the major tunnel lengths will be provided by rock reinforcement in conjunction with shotcrete. Steel ribs are proposed in areas of low cover and weak ground. Final support will comprise an insitu concrete lining. Construction concepts and special tunnelling methods required at the shallow underground forks and tunnels are described.

Jan 1, 1987

By T Berryman

The Fimiston reserve is being depleted at the rate of one million ounces per year; most of which is processed by the Fimiston plant, with the remainder being stockpiled. As for most other large open cut mines around the world, Fimiston has an excellent dispatch and tracking system. Reconciliation is used to determine how the various models used in mine planning (such as a reserve, budget and schedule models) are tracking against production. It is also used to gauge the performance of grade control estimation against production; however, analysing the results of this can be complicated and, at times, misleading. The reconciliation process involves adjusting the monthly production data to equal the mill reported tonnes and grade, plus the change in stockpiles. This adjusted number is then compared to the grade control reported tonnes and grade, the scheduled model (monthly planning model) tonnes and grade and against budget (Reserve) tonnes and grade. This paper includes explanations of all assumptions made in the reconciliation process, including the end of month closing stocks balance, the application of adjustment factors to the dispatch data to create a new balanced set of production data and the monthly sign off to comply with the Sarbanes-Oxley requirements of the North American owners. The reserve is reconciled by proved and probable classification. This tool is used to assess the robustness of the classification scheme utilised and identify any reconciliation issues as they arise. Within the Fimiston deposit there are still issues that are clouded by the assumptions made concerning the scale of observation, poor data support and the mining of the narrow lode areas of the deposit. The declared ore mined (DOM) number (which is defined in the paper) can be significantly affected by these assumptions, and these need to be clearly stated and understood when looking at the reconciliation data. The DOM tonnes and grade is a good indicator of real mine performance as it adjusts mined tonnes and grade to take into account the milled tonnes and grade each month, and prevents cumulative errors from building up in mine predicted dispatch numbers or end of period stockpiles. This number allows monthly monitoring of the mine to mill performance and allows valid comparisons to be made back to budgets and reserves over a period of time. KCGM uses three month rolling averages to monitor performance against reserve and budget models. This ensures that monthly distortions in the figures due to stockpiling issues or over mining in a particular period do not lead to false conclusions. Reconciliation performance over a longer period (12 - 18 months) is used to adjust reserve models should significant variance be observed. By closely monitoring the reconciliation performance at the Fimiston operation, fine tuning of all aspects of the grade estimation process from reserve through to grade control can be made. This allows the most accurate data to be used when planning from reserve data for the Life of Mine Plan through to grade control data for short-term mill feed.

Jan 1, 2006

By M Pratt

For up to 75 years large scale coal mining has been carried out within the Latrobe Valley region of Victoria. Withdrawal of groundwater from Tertiary aged sediments within the Latrobe Valley is essential to allow coal mining to proceed to depth. Water within the overburden layers, coal seams and interseams must be drained to avoid flooding during the mining process. The pressure in deeper aquifers must also be lowered to avoid floor heave, batter instability, and to maintain safe operating conditions as the mines develop in size and depth. The cost-effective management of the groundwater systems at and adjacent to the mining operations in the Latrobe Valley is essential to enable the efficient utilisation of the coal resource whilst minimising the environmental impact of this major industry in rural Victoria. Large-scale depressurisation and dewatering programs within the Latrobe Valley mines are managed through the use of detailed groundwater management plans. These incorporate:an extensive monitoring network which extends up to 60 kilometres from the mines; detailed mine scale and regional groundwater and hydrogeological models; and established operational procedures aimed at minimising capital and operational costs associated with the mine groundwater systems. Groundwater extraction system optimisation programs have been introduced into two of the mines with the aim of reducing extraction rates, improved risk management, and reducing operational costs by approximately whilst not compromising mine safety. This paper reviews the aquifer depressurisation and mine dewatering operations of the Latrobe Valley mines and illustrates the techniques utilised to ensure that high artesian pressures do not adversely impact on the mining operations.

Jan 1, 2003

By Warner N. A

There is an inherent problem in producing simultaneously lead, zinc and copper as metals in a single polymetallic smelting furnace. It relates to the condensation of lead and zinc from the gas phase under vacuum conditions such that metals in bulk form, either solid or liquid, are obtained as products rather than a fume or dust containing both metallic and non-metallic components. To understand this phenomenon, it has been necessary to establish mathematical models with computer simulation to identify the process requirements for effecting the objective of maximum bulk metal production with minimum fog formation. The theoretical framework of simultaneous heat and mass transfer involved in condensation from gas mixtures containing a non-condensable gas has been extended to the high temperature and reduced pressure conditions. These apply to new technology for polymetallic smelting now being developed in a project currently funded jointly by the Commission of the European Communities and the Mineral Industry Research Organisation. Under the right conditions it is theoretically possible to condense out both lead and zinc with minimal fume formation, but in all practical cases it is anticipated that some circulating load for reversion back to the smelter will be needed.

Jan 1, 1989

Different mineral structures can act as mineral reservoirs for the immobilisation of toxic compounds. In the paper different mineral structures will be explained and their potential for incorporation of heavy metals and anions will be shown. The following structures will be explained (P÷llmann, 2007):apatites (incorporation of heavy metals, silicate apatites);ettringites (fixation of oxo-anions);layered double hydroxides (fixation of heavy metals, fixation of anions, fixation of organics, sorption materials); andmanganese oxides. Different possibilities of solid solution and incorporation in crystal structures will be explained and advantages of stable minerals be proved using experiences with real toxic wastes. In the process of thermal treatment the formation of primary mineral reservoirs will be shown. The precursor phases (similar to well known cement minerals) react in contact with water to form secondary mineral reservoirs (cement hydration mineral products). The formation condition of primary and secondary mineral reservoirs and their stabilities and incorporation possibilities will be shown. Examples for incorporation of various elements are given. Application for water clarification will be outlined.

Jan 1, 2008

The City of KalgoorlieBoulder is situated approximately 600 kilometres to the east of Perth, and as the major regional centre of the Eastern Goldfields, supporting a population of approximately 25 000. The formation of Kalgoorlie Consolidated Gold Mines in 1989 brought the existing operating entities adjacent to the city under common ownership and management. The Joint Venturers forming the management company are Homestake Gold of Australia and Gold Mines of Kalgoorlie (a Normandy/Poseidon company).This traditional underground mining centre has been worked since 1893, yielding 40.5 million ounces of gold ore with an average head grade of TEN grams per tonne. Historically the heart of the operation has been the famous Golden We located on the Eastern perimeter of the city, in the area known as Fimiston. The other significant operations that form KCGM are the Mt Percy Open Pit and the Mt Charlotte Underground Operation.

Jan 1, 1992

By N Voller, A Ishmurzin, G Hackl, M Wu, A Kharicha, M Chintinne, C M. G Rodrigues, A Ludwig

Slag fuming (SF) is a critical process for recycling zinc-containing slags, but the corrosive nature of molten slag poses challenges to the reactor durability. The freeze-lining (FL) technique offers a solution by forming a protective layer on the reactor wall. It requires intensive cooling using watercooled jackets, which can stabilise the FL while compromising the energy efficiency of the process. This study presents a computational fluid dynamic (CFD)-based model to optimise the SF process by considering FL formation and its impact on heat transfer and reactor wall temperature. A volumeof- fluid (VOF) model is coupled with a mixture continuum (MC) solidification model to capture the intricate multiphase flow dynamics within the SF furnace. Two FL types are considered: FL solidifying on the reactor wall in the slag bath region; and FL solidifying on the reactor wall in the freeboard region. The FL of the first type forms when the slag temperature drops below liquidus temperature. The FL of the second type only forms when a splash-induced slag droplet collides with the freeboard wall and solidifies. A series of splashing events are necessary to coat the freeboard wall. The simulation was run until a global energy balance was reached. This means that the heat losses from the water-cooled jacket, bottom wall, outlet and fuming balance the heat gains from the hot gas injected through the submerged plasma torches. The increase in FL thickness, due to its low thermal conductivity, reduces the heat losses through the reactor walls. The calculated FL thickness and heat fluxes were in good agreement with industrial data, validating the model’s credibility. The simulation results provided valuable insights into the fuming process, including slag bath temperature evolution, slag splashing dynamics, FL formation patterns, local heat fluxes through the reactor wall and overall energy balance. These findings can inform process optimisation strategies to enhance the energy efficiency and sustainability of SF operations. The authors have built a prior version of the model framework and applied it to simulate FL formation in an electric smelting furnace (ESF). The results from both the ESF and the current SF highlight the applicability of such model framework to a range of industrial processes involving FL formation. This model framework can ultimately contribute to more energy-efficient and sustainable industrial operations.

Aug 21, 2024