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By Bowden MW

Sintering of lead-zinc concentrates is practised by Sulphide Corporation to provide both desulfurised lump sinter feed, for simultaneous reduction to zinc and lead in the Imperial Smelting Process blast furnace, and sulfur dioxide gas for sulfuric acid manufacture.Moisture control of feed mixes is of paramount importance in the sintering operation and improvements in this area have realised increases in overall plant performance.

Jan 1, 1985

Copper heap leaching involves both the simultaneous and sequential leaching of very large tonnages of ore over long periods of time. It is not unusual to be leaching three or four million tonnes over periods of 12 to 18 months. As a consequenc

Jan 1, 1998

By Wilkinson RDB, Van Der Meer FP

In order to overcome the statistical limitations imposed by the need to recover density tracers by hand, magnetic density tracers were developed to determine the efficiency of dense medium separators treating porous materials. The tracers were manufactured by extrusion of polypropylene ferrosilicon mixtures and subsequently coated with a distinctive paint to allow hand sorting according to density. Fifteen tracer batches were manufactured in the range 1.61 - 1.94 g/cm3. The tracer densities were determined by a hydrostatic method. The tracer method was applied to the dense medium separation of a Moroccan oil shale in a pilot scale Dyna Whirlpool separator. For each test, about 20,000 tracers were added with the plant feed and subsequently recovered from the products with a dry low intensity magnetic separator. The Tromp curve determined by conventional heavy liquid analysis was displaced towards lower densities compared with that determined by tracers, indicating that the porous shale particles absorb heavy liquid. It is concluded that for porous materials like oil shale and coal, the tracer method gives the most accurate results. In pilot scale testwork the tracer method is also much faster than the conventional heavy liquid analysis, as rather large samples have to be processed by the latter method to ensure Representativeness.

Jan 1, 1987

By Milner SC

Four quartz latite rheoignimbrite units (units I to IV) mapped in the Goboboseb Mountains have been traced to their eruptive source, the Messum intrusive complex; this is a complex multistage ring structure (18 km diameter) with well defined gabbroic, monzonitic, and syenitic intrusive phases, and a central ring zone containing mixed rhyolitic to latitic agglomerates. Three of the four quartz latite units are correlated with the upper and lower (2 units) Springbok quartz latites outcropping some 90-130 km north of McIsum. This implies minimum volumes of 300-500 km for wits I and III (Lower Springbok) and 2200-2600 km for unit IV (Upper Springbok). This latter unit is still ti 300 m thick at its outcrop limit, some 130 km from Messum. Each of the four units represents single cooling units. Lithologically, each can be divided into three zones: A basal, dark grey to black flinty or glassy zone, often with highly attenuated fiamme (ressembling flow banding); a central massive and strongly recrystallised zone; and an upper variable zone which exhibit breccias, contorted flow banding, and amygdaloidal to pumiceous clasts. Their overall characteristics tend to be intermediate between ash flows and lava flows. The rheoignimbrites are interpreted as the oproducts of dense, high temperature (950¦-1100 C) ash flows which underwent rheomorphism and lava-like flow prior to their final cooling.These large scale eruptions are related to the initial rifting of Africa and S. America, possiby in response to a major hot spot.

Jan 1, 1990

By Snowdowne J. B H

Rand Mines, Limited, located in Johannesburg, Republic of South Africa has recently completed feasibility studies which have lead to the initiation of two major coal strip mining ventures. A minicomputer based mine planning system was developed to perform the feasibility studies. The broad approach of this system is to utilise inter.-actively the specialist skills and interpretative abilities of mining engineers and geologists. This paper reports briefly on the outline of the system and at greater length upon certain aspects of its use.

Jan 1, 1977

By Wills BA, Barley RW

A brief description of viscosity measuring devices used in Dense Media Separation (DMS) plants is given, including a new On-line viscometer system. The various factors which affect suspension viscosity are identified. The effect of temperature variation on viscosity and viscosity measurement is examined in detail. Practical problems in using a modified Stormer viscometer for laboratory testwork are noted. Likely problems of continuous viscosity measurements are also discussed.

Jan 1, 1987

By James S. E

Financial risk of environmental problems is the key to many important business decisions within the mining industry. Massive uncertainty makes it difficult to choose a strategy for managing environmental problems to reduce corporate financial exposure to environmental impairment. A correct and practical method exists to clarify the risks and help make decisions. A case study on an insurance problem illustrates the method.The approach used is to translate existing data on environmental problems into probabilistic expressions of financial risk, and organise the expressions to reveal alternative solution strategies for the insurance problem.

Jan 1, 1993

The iron ore deposits of-the Port Hedland distract of North-Western Australia are associated with banded-sedimentary iron., formations that.form part of the local succession. of folde.d..and faulted Archaean volcanic and sedimentary. rocks., The iron formations are regarded as the pr.otore,beds or sources of.the. iron which became;.,c,o.ncentrated by supergene.,processes. to form c,omznercial grade.. iron ore deposits,, ;-ò; Iron oxide ' deposit's occurring in"situ' within' the prot'ore beds are considered to be of residual--repplacement,origin`, due to supergene leaching of gangue minerals and deposition of secondary iron oxides in their'place'. Two types of deposit have been recognized. Lode deposits are deep lenses of massive hematite located adjacent to major, fau.lts... - These; deposits are-thought-to be very.,,old' and-to: have originated by supergene processes:.. during the, long: period of_ erosion represented- by the major, unconformity between the, Archaean .rocks and the, over!.

Jan 1, 1964

By Svensson J

The nickel segregation process is one of the methods for treating nickel oxide ores. In this process nickel oxide ores are heated together with a small amount of the carbonaceous reductants and halides to about 800-950¦C. The reduced nickel segregates onto the surface of the carbonaceous reductants in the form of metallic particles which are recovered by magnetic separation or flotation. Pilot plant tests for the extraction of nickel from nickel oxide ores have been made using nickel segregation process by means of a new roasting installation which is called the "Mechanical Kiln" (2.5m~ x 3m,') with autogenous heating. Nickel oxide ores containing about 2.5%Ni were mixed with 2.5%CaC12 and 2.7%coal, and continuously charged into this installation at the rate of 60kg/h in continuous operation for 30 days per trial.

Jan 1, 1980

By J F. C L Costa, J C. Koppe

The goal of this study is to characterise co-processed clinkers by identifying the most common minor elements, their distribution in the clinkers and possible effects on the mineralogical properties of the same. The results show the presence of an elevated content of transition metals, especially manganese concentrated in the matrix (up to three per cent) of the clinkers. Anomalous concentrations of arsenic have also been detected, especially at silicate crystal edges. The results indicate that the tracer elements can perfectly be associated to the mineralogical characteristics of the clinkers.

Jan 1, 2008

of the multitude of physiographic problems of immediate interest in volcanic terranes, it is the origin of the magma forming the magnificent volcanoes that is perhaps the most mysterious. Unlike anywhere else on earth, the possible locations of magma production beneath the convergent margins are strongly limited in depth and areal extent. Yet the exact process by which magma is produced still stands elusive, even in light of tremendous gains in analytical and physical insight. The principal aim here is to discuss some of what has been revealed about the physics and chemistry of the origin and evolution of island are magmas.

Jan 1, 1987

Misima Mines Pty Ltd (MMPL) operates a large open cut gold mine on Misima Island in the Louisiade Archipelago in Papua New Guinea. Misima Island lies approximately 600 km east-south-east of Port Moresby. The island is 40 km long by 10 km

Jan 1, 1994

The methods used by the Anglo American Corporation for analysis of long-term metal markets and prices are described. The principal factors affecting the relationships between production costs and metal prices are analysed. These are firstly the type of market, - speculative or consumer commodity, free market or subject to price control; and secondly the rate of growth of demand for the metal. It is shown that virtually all metals will have relatively low rates of demand growth for the foreseeable future, due to market saturation, increased economisation, substitution and product obsolescence. Metal prices have a clear dependance on production costs, however forecasting future costs is by no means simple; amongst other things, account must be taken of changing exchange rates, inflation rates, and the potential for operating more efficiently. The paper concludes by giving brief assessments of the long-term future for aluminium, copper, zinc, nickel and tin.

Jan 1, 1986

By E S. Souza, H Delboni Jr, M F. Calixto

This paper aims at presenting the results of laboratory, pilot plant and simulation studies for the design of the grinding circuit for the beneficiation of compact itabirites from the Conceitpo mine. Two alternatives were investigated, both utilising the current crushing circuit up to tertiary crushing. Under alternative #1, quaternary crushing was considered to produce the feed of the ball mill; under alternative #2, high pressure grinding rolls were selected to prepare the ball mill circuit feed. Pilot scale studies pointed towards the use of high pressure grinding rolls (HPGR). The circuit design was based on a throughput of 720 t/h, representing a nominal solids flow rate of 600 t/h, considering a design factor of 1.2, and P80 of 95 ¦m.

Jan 1, 2007

Grade control aims to deliver quality tonnes to the mill via accurate definition of ore and waste. It comprises data collection and interpretation; local reserve estimation; supervision of development and mining; and stockpile management. The foundation of all grade control programs should be that of high quality sampling supported by geology. The requirement for quality grade control samples has long been recognised, where they should be representative, unbiased, safe and operationally timely. Underground sampling methods include chip and channel samples; grab samples; and drill-based samples. To achieve quality samples, collection techniques employed should minimise delimitation, extraction and preparation errors. Grade control staff should be well-trained and motivated, and mining staff should understand the need for grade control. This paper reviews grade control sampling methods and presents recommendations for best practice and minimisation of sampling errors.

Mar 1, 2010

By W T. Pate, A V. Potapov, J K. Lichter

Even though flotation is one of the most important unit operations of mineral processing, accurate modelling of this process for plant performance prediction has remained elusive. In the last four to five years dramatic changes have occurred in our ability to make credible model based predictions. This paper briefly traces the history of flotation modelling from simple (lumped pulp-froth) æchemical kinetic analogueÆ models for single cells to more detailed multi-phase, multi-component population balance models for banks of cells. It then focuses on recent developments in physics-based modelling tools. This includes current efforts to model the forces of attachment and detachment at the individual event level as well as multi-event levels in individual cells and circuits. Two examples of these tools are presented. The first is DEM modelling of the mechanics of motion of bubbles in froths. The second is population balance modelling of the dynamics of flotation circuits describing how they are influenced by upstream processes (such as crushing and grinding) as well as internal process variables (such as aeration, agitation and reagent addition). Applications of each of these tools are discussed.

Jan 1, 2005

By E Taylor, F Lebbing

The $2.5 billion EastLink project is a 39 km tollway and includes twin three-lane, 1.5 km long, undrained driven tunnels with cross passages every 120 m. The hard rock tunnels are being built to avoid passing the motorway through the Mullum Mullum Valley and help preserve the unique flora and fauna in the area. The design of the permanent concrete lining and waterproofing system for the EastLink tunnels was both innovative and practical, to meet the demanding environmental and production constraints of AustraliaÆs largest road project. This paper describes several key aspects of the tunnel design and construction, including: design of fully tanked, permanent concrete tunnel linings for the main tunnels and cross passages to withstand 37 m head of water pressure in combination with potential rock loading in the future;optimisation of the tunnel shape to minimise the amount of reinforcement required and the design of special welded mesh which was developed within manufacturing constraints;100 year design life and durability considerations in every aspect and detail of the design including concrete mix design and stray current mitigation;development of a precast invert solution for the main tunnel permanent concrete lining to enable faster lining construction and to minimise risks to the tunnel membrane associated with fixing reinforcement and construction traffic;development of prefabricated reinforcement details for the junctions between the main tunnels and the cross passages to enable faster construction and minimise risks to the membrane associated with fixing reinforcement; andincorporating the tunnel drainage sump at the lowest cross passage in the alignment, resulting in deep excavation to satisfy the required storage volumes for drainage.

Jan 1, 2008

By Chia A. H

This paper presents an overview of the development and operation of the PT Adaro Indonesia coal mining project. This operation is an initial two million tonne per annum mine, located in South Kalimantan, Indonesia.The paper places emphasis on some of the more unique infrastructure development and operational challenges that exist in such a remote location environment.A brief summary is also given of the Indonesian coal industry, its direction and position as a significant coal producing competitor for Australia.

Jan 1, 1992

By Gleadow AJW, Foster DA, Kohn BP, Raza A

A large and increasing data base of apatite fission track results from sedimentary and granitic rocks exposed within the southeastern highlands and along the continental margin of Australia provides constraints for the tectonic development of the southeastern passive margin. The fission track results suggest that many regions of the southeastern margin of Australia experienced distinct episodes of relatively rapid cooling during the middle Cretaceous to early Tertiary that can be attributed to the effects of rifting. One cooling episode is middle Cretaceous in age and related to denudation of the southeastern highlands from Tasmania to northern New South Wales between -90-100 Ma. Rocks exposed along the present coast line record a later episode of rapid cooling, which is diachronous and decreases in age northward from -80 to 90 Ma in northern Tasmania to southern New South Wales, -60-80 Ma in central and northern New South Wales, and to -50-60 Ma in southern Queensland.

Jan 1, 1995

By Thornton D, Firth B, Kojovic T, Brien G, O&apos

Coal fragmentation is a function of coal type and mining process. Each unit step in the mining, handling and crushing chain of coal imparts energy to the material and impacts on size degradation and consequent mineral matter liberation and pla

Jan 1, 1998