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By Laird CH

Large quantities of brown coal are excava ted from open cut mines in the Latrobe Valley to fire the base load thermal power stations of the Victorian Electricity System. Most of the coal is removed using bucketwheel excavators which have been modified or specially designed for the conditions encountered. The actual digging efficiency of the bucketwheel excavator is strongly influenced by such factors as wheel speed, slewing speed and tooth design and arrangement. The coal deposit, although not difficult to work, is not uniform and the operation of the machine is influenced by the stability re- quirements of the excavation face.

Jan 1, 1978

By Kristiansen J

A series of laboratory blasting and ball mill grinding tests have been done on four different types of hard and competent rocks. The results show that exposing these rock types to a higher level of explosive energy will enhance their grindability. True blasting optimisation should therefore look at the whole comminution process from solid rock to a marketable product.

Jan 1, 1995

With the recent increase in the number of underground secondary sulphide dust explosions in Canada, Australia and elsewhere in massive sulphide ore mining industry, establishment of quantitative and realistic methods of analyzing the mine dust is of paramount importance. This paper examines and analyses dust samples from a mine area that has very recently experienced sulphide dust explosions. Also, it attempts to evaluate the physical and chemical characteristics of the dust. Explosibility of the dust samples was determined by quantifying the oxidation reaction of the sulphide dust particles in a 1.2 L, Lindenberg open horizontal tube furnace. Percentage sulphur', % S oxidised during ignition of a dust sample of known assay, % S and dust concentration (g/m3) were determined by the quantitative chemical analysis of SO2 gas produced during the oxidation reaction. A dust sample with high sulphur content, 22.3% S (assayed) and mean particle size 9.82 pm, was found to exhibit a low degree of oxidation compared with a sample of low sulphur content, 15.44% S and mean particle size 21.7 tcm, at the same Temperature.

Jan 1, 1988

The scheme of rehabilitation of surface plant commenced in 1936, included the provision of improved and more hygienic changing and bathing facilities for the employees.At that time the Thompson's Shaft section of the British Mine was being prepared for a resumption of operations, and it was decided to repair and re-equip the existing building. Thus any new scheme adopted could be given a thorough trial, and the proved arrangement used as a basis for the contemplated new main changehouse on the North Section.Investigations were carried out to determine the most suitable arrangement for the Thompson's Shaft changehouse, to provide for a total of 120 men, with particular regard to the internal fittings and fixtures. Also, as the mining conditions were such that a large proportion of clothes worn underground by miners, etc., were wet by the end of the shift, the problem of drying these clothes in the availaole time from a man coming off shift to his commencing again some sixteen hours later was one of the most important to be dealt with.The changehouses in use on the North mine section of the lease were provided with racks around the walls for the men to hang their street clothes on, and a section was partitioned off to house the mine clothes and their drying facilities. The actual drying was carried out by means of hanging the wet clothes over racks between which ran pipe coils heated by means of hot water circulated from the hot water boiler supplying the showers.This method had proved to be far from satisfactory for several reasons, the main objections being:-

Jan 1, 1940

By Jowett A

To compare open circuit lead primary rougher results at Mount Isa Mines Ltd., eleven surveys were made over five weeks of plant operation with varying ore sources, including a specially hauled sample of 100% Black Star ore. Three of the surveys which represented extremes in performance were selected for sizing, cyclosizing and assaying for lead, zinc and iron. A comparison of the flotation kinetics has revealed the similarities (including common problems) and differences for the surveyed ores. The concepts of entrainment and collectorless flotability are used to aid interpretation of the kinetic data.

Jan 1, 1978

From the ventilation aspect, there is a basic difference between advancing and ezreating longwall layouts. Particular rroblems with retreating, using differing mining methods and layouts include high gas emissions, spontaneous combustion and -radients. There is an acceptable method of crntrolling the environment at the return end a retreating longwall face without the use a multiple heading system. Incorporated in the design is the facility to practice xtensive methane drainage, thus ensuring a ntrol of the rate of methane emission into the main roadways. Case studies highlight varying mining editions under which the proposed system of Ctised.

Jan 1, 1982

The Matakan Unit of New Ireland, Papua New Guinea is a highly fossiliferous lagoonal deposit containing numerous coal pods and lenses. The unit is strati graphically part of the massive reefal Lelet Limestone of Miocence age. These organic-rich sediments have a high hydrocarbon potential as evident from microscopical observations as well as Rock- Eval pyrolysis data. The coal is varied in regard to dominant macerals, vitrinite being predominant in some parts and pollen and spores present in sufficient proportions to constitute a cannel coal elsewhere. The highly fossiliferous carbo as Rock-Eval pyrolysis data. The coal is varied in regard to dominant macerals, vitrinite being predominant in some parts and pollen and spores present in sufficient proportions to constitute a cannel coal elsewhere. The highly fossiliferous carbonaceous sedimentary rocks associated with the coal are rich in pyrite expressed in the sulphur content (19.7 - 22.8%). A high primary productivity and anoxic sediment pore waters or just above sediment - water interface have given rise to sufficient organic matter accumulations to yield a potential hydrocarbon source rock. Atomic H/C ratios of the coals are between kerogen type III and type II mainly, expressing the mixed nature of the coal and that of the associated sediments is type II. Early generated hydrocarbons (exsudatinite) have formed from pollen exines filling the pollen cavities and in places filling micro- fissures in the surrounding vitrinite.

Jan 1, 1987

By Dorricott M. G, McAllister J

This paper is concerned with the application of a probabilistic approach to the risk assessment of mining projects.In current practice, sensitivity analysis is the most commonly used deterministic approach of accounting for the uncertainties involved in mining project evaluation, while Monte Carlo simulation is considered to be the best probabilistic method available for the same purpose. The methodology of the approach proposed in this paper is as simple as that of sensitivity analysis. However, the results obtained can be more comprehensive than those obtained from Monte Carlo simulation. Various important statistical features, such as correlation and skewness, of the basic random parameters can be easily taken into account by the proposed approach. Example studies are demonstrated. Lotus 123 was employed for the associated probabilistic calculations.

Jan 1, 1992

By Membrey W. B, Partridge A. C

Lower transportation costs, improved handling and better utilization efficiency are some of the reasons that make low moisture coal product desirable. There has been considerable interest in the development of effective coal dewatering techniques to achieve this result. One avenue of considerable merit for enhancing dewatering processes is by modification of the surface chemistry of the coalwater slurry system by chemical means, resulting in better performance of existing equipment. This paper reports the results of an investigation of the utility of surface active agents in the enhancement of fine coal dewatering. A large variety of proprietary dewatering agents have been studied in relation to their efficiency in enhancing the dewatering of a number of Australian coals. Properties of particular coals that make them amenable to improved dewatering by particular chemical agents have been identified. Surface studies, including surface tension and zeta potential measurements as a function of surfactant concentration, as well as dewatering assessments, were used. Particular attention was paid to filtration, but the results could be applied to other dewatering systems.

Jan 1, 1989

By Ellery B. I

Field investigations recently undertaken by Utah Development Company (U.D.C.) have been developed to allow the assessment of ground conditions relevant to the use of large bucket wheel excavators for pre-stripping overburden. "Bucketwheel diggability" predictions were made on the basis of a wedge test which was perform- -ed in the field on nominal 150 mm diameter drill core samples. Specific separation force (calculated from the wedge test results) for different rock horizons were theoretically related to the excavation rates of various sized bucketwheels, i.e., "bucketwheel diggability". The specific separation force was shown to vary with lithology, structure, weathering and moisture changes. By correlating these features between boreholes, an overall assessment of bucketwheel diggability was then made. The approach adopted to assess bucket- wheel diggability incorporated various levels of investigation. Initially, a reconnaissance stage provided information from widely spaced 150 mm cored holes to compare and contrast areas with differing bucketwheel digging char- -acteristics. The following stages progressive -ly added to this information, until finally, between hole correlations, allowed calculations to be made of volumes of materials of similar

Jan 1, 1981

By Garrigan J. S, Oakes I

Current operating practice in a plant commissioned some five years ago to treat ferritic zinc plant residue by the "Jarosite" process is described. Major problems overcome include obtaining reliable pH measurements at 100¦C, prevention of scale build up in spent electrolyte heaters, blinding of jarosite filter cloths and the deposition of gypsum in filter presses.

Jan 1, 1977

The first introduction of automatic control systems for flotation occurred about fifteen years ago. The early control work coincided with the introduction of on-line assaying using XRF techniques. This OSA availability, coupled with the emergence of small digital computers suitable for process control in the late 1960-s, meant that the necessary process information and control hardware existed for flotation control experiments. A period of intensive research related to flotation control. ensued. A great deal of effort was devoted to the development of mathematical models of flotation. Plant experimentation sought to understand the effects of a range of flotation variables on the process. Finally, control loops were proposed and plant tested. An evolutionary pattern emerges when the range of flotation control installations is examined. The earliest systems had as objectives process stabilisation using reagent control. There were also some early attempts at flotation optimisation procedures, again using reagent variation. Current work is still associated with the same objectives. One of the difficulties with flotation control has been to recognise and define clear and precise control objectives. More emphasis is now placed on cleaner control which has the advantage that the objectives are usually well defined. A number of flotation control systems which cover a range of control system types is discussed. Based on this accumulated experience,a list of good and bad practice in flotation control is Proposed.

Jan 1, 1983

By W Boughton, L Gilbert

The Australian Water Balance Model (AWBM) has found widespread use in Australia in estimating the streamflow behaviour of catchments. It has been used at the Ridgeway Gold Mine, in central west New South Wales, to estimate streamflows in creeks potentially affected by loss of spring-fed baseflow due to mine dewatering. The AWBM estimates are used to assess the effect of mining on streamflows and the need to provide compensatory flow releases, which would be drawn from mine water supplies, into the creeks, in compliance with regulatory consent requirements. The monitored flows in some of the creeks exhibit non-typical behaviour, with streamflows increasing in autumn months despite a lack of significant rainfall. This behaviour is believed to be due to the combined effects of discharge from rock fractures and the effects of evapotranspiration in the riparian zone. A modified version of the AWBM has been developed which much more closely simulates the observed flow behaviour and which will be used in ongoing flow assessments for the mine. This paper outlines the difficulties involved in modelling low flows in small catchments that are subject to a number of influences (other than mining), describes the development of a refined model to improve simulation of low flows and baseflow in small headwater catchments and highlights the need for good baseline data to calibrate such models.

Jan 1, 2006

By Ryan CG, Cousens DR, Griffin WL

The proton microprobe is developing into a vital tool in the geosciences, through its high sensitivity for in-situ detection of trace elements in the ppm regime. This paper will describe the instrument at the CSIRO Heavy Ion Analytical Facility at North Ryde, including features crucial to its successful application in the geoscience. Examples of applications in the basic geoscience and mineral industry related research are described briefly. Conditions required for widescale applications in the minerals industry are Discussed.

Jan 1, 1989

Mineral sands are different to almost any other commodity; however, it shares similarities with other commodity types, such as the importance of quality constraints of iron ore and coal or the importance of physical properties of diamonds. The mineral sands industry consists of two principal product streams; titanium dioxide minerals û in the form of rutile, ilmenite and leucoxene, and zircon. The principal valuable heavy minerals (VHM) include ilmenite, leucoxene, rutile and zircon. Variations of other titanium minerals occur between the end members of ilmenite and rutile, including pseudo rutile and anatase. Most mineral sands deposits are found in unconsolidated fossil shorelines several hundreds of metres to tens of kilometres and occasionally hundreds of kilometres inland from the present coastline. Mineral sands orebodies essentially fall into two categories based on the mode of deposition: alluvial or aeolian. Alluvial deposits are further split into marine beach placers (or strandlines) and lacustrine heavy mineral (HM) accumulations. Exploration for mineral sands involves the positive identification of key criteria leading to the focus of exploratory surface sampling, augering and drilling. Assaying is primarily focused around determining the percentage of HM contained within a given sample. Other results of interest include clay fines, sand and oversize. Metallurgical/mineralogical assessment is often undertaken via laboratory scale bench tests that replicate the wet concentration and dry mill processing routes. The most critical component in resource assessment for mineral sands is about quantifying HM grade, then mineralogical assemblage and then quality of those mineral species. This will determine whether a mineral sand final product is marketable or not. Mining of mineral sands is conducted either wet or dry. Wet methods are generally preferred for large tonnage, unconsolidated and low clay orebodies. Where ground conditions are hard and orebodies are small, high grade and discontinuous, dry mining techniques are generally employed. Concentration of mineral sands from the primary ore is carried out in two sections; wet, utilising sizing and gravity differentiation between HM, VHM, clay and quartz, and dry, exploiting the magnetic, electrostatic and to a lesser extent specific gravity (SG) properties of the minerals of interest. Mineral sands exploration, mining and processing faces the same operating challenges as the rest of the resource sector. Added to this are the issues that are unique to mineral sands and to which the industry devotes considerable resources to developing solutions.

Jan 1, 2009

By Hare S. M, Griffin P. T, O&apos

Chalcopyrite ore and converter slag treatment to produce copper concentrates is undertaken at the Copper Concentrator of Mount Isa Mines Limited. This concentrator was commissioned in May 1973, replacing the original No 1 Lead-Zinc Concentrator, for the processing of all chalcopyrite ore coming from Mount Isa Mine.Treatment of chalcopyrite ore at rates of up to 125 000 l/week is described here; the treatment of converter slag is described later.

Jan 1, 1993

By Ranklin W. J

The mechanism and rate-limiting step of carbonaceous reduction of zinc from slags was investigated in the laboratory. Disks of graphite were rotated in ZnO-containing slags at various speeds for fixed periods at 1250 to 1325¦C. The mass loss was used as a measure of the amount of ZnO reduced. Application of the Levich equation indicated that at rotation speeds at which it is valid, the reduction was chemically controlled with an activation energy of 27 kcal/mol. At zero rotation speed the reduction of ZnO by carbon appeared to be slag-phase mass transfer controlled with an activation energy of 38 kcal/mol. An increase in the FeO content of the slag increased the rate of reduction while an increase in sulphur content decreased the rate of reduction. When FeO was present in the slag, reduction appeared to occur by a combination of indirect reduction of ZnO by carbon and by reduction by FeO with reduction of Fe203 back to FeO by carbon. The effect of sulphur was consistent with a surface blockage mechanism due to the surface active nature of sulphur in slags.

Jan 1, 1993

By O&apos, Malley G. B

The properties of bearing metals are of considerable interest to mine engineers, since continuous running of mine and mill machinery is of vital importance. Of the several available types of bearing metal, the low melting point lead or tin base alloys are most generally used in mining plant because of the ease of replacement and the possibility of remelting scrap metal from old bearings. The most valuable property of these "white metals," however, is the plasticity which gives a self-aligning character to the bearings, enablingthem to adjust themselves to inequalities which may exist at the time of fitting, or which may develop during running. The object of the present paper is to explain in general terms the physical structures of white bearing metals, and to point out that constitution rather than composition determines the physical properties of these alloys. The same, indeed, is true of most engineering alloys. In steels, for example, a change in the structure may affect the properties to a far greater extent than a change of chemical composition.Structural changes in steels are produced chiefly by heat treatment. In the case of bearing metals no good purpose is served by heat treatment; the microstructure is determined by the conditions of casting, and striking differences in constitution (and therefore in properties) are encountered in an...

Jan 1, 1932

By Mack JF

A metallurgical evaluation of the Argyle Kimberlite No. 1 (AKl) orebody has been carried out using a 40 tonnes per hour pilot plant. Pilot plant results, together with laboratory investigations provided a basis for the determination of process design criteria for a major treatment plant. Various sampling programmes were carried out to determine specific aspects in the evaluation of diamond liberation. Treatment parameters such as the top crush size, recrush size and the bottom cut-off size were investigated. A description of the pilot plant is given together with the design criteria for a 3 million tonne per annum treatment plant

Jan 1, 1984

The influence of strongly chemisorbed solutes such as oxygen and sulphur on the rates of reactions at the gas-liquid iron interface is briefly reviewed. Deductions from recent studies of the rates of decarbur- ization of carbon-saturated liquid iron indicate ideal adsorption behaviour for sulphur over a wide temperature and composition range. This is in fair accord with available infor- mation on surface tensions in the Fe-C-S system. Previously unpublished results for the kinetics of the 14C02-CO exchange reaction are in accord with ideal absorption of oxygen on liquid iron. The derived value for the ideal adsorption coefficient of oxygen at 1550¦C is in quantitative agreement with measurements of the depression of surface tension in the Fe-0 system. Consideration is given to the applicability of such results to the violently agitated systems of steelmaking.

Jan 1, 1980