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By K L. Avarmaa, M A. Rhamdhani, A D. P Putera, H T. B M Petrus, G A. Brooks

Multistage slag treatment was carried out to investigate boron removal from metallurgical grade silicon. Boron is known to be one of the most difficult elements to remove from silicon. Depending on boron initial concentration, boron can be removed from silicon into certain level; most previous studies have attained final 50–100 ppmw (parts per million weight) boron in the silicon using slag treatment. The term ‘multistage’ refers to a process where the resulting silicon from the initial slag treatment is further refined multiple times using a new slag. In this study, an initial slag composition of 45CaO-45SiO2-10Al2O3 (wt per cent) was utilised. Using this technique, boron level in the silicon was expected to be gradually lowered because the new slag will always have more capacity to reach the equilibrium distribution coefficient (LB = (ppmwB)slag/(ppmwB)Si). The current study was carried out through combined thermodynamic calculations (using FactSage™ ver 8.2, by Thermfact Ltd, thermochemical package) and high-temperature experimentation. The thermodynamic calculations were carried out for reactions at 1500, 1550, and 1600°C for three different scenarios: 1. Single stage refining with varied slag to Si ratio. 2. Multistage refining with slag to Si ratio of 1:1. 3. Multistage refining with slag to Si ratio of 2:1. The multistage experimental work was carried out at 1550°C under inert gas atmosphere each time for 2 hrs, with slag to Si ratio of 2:1. The simulation results indicate that the boron distribution coefficient stay essentially constant with varying slag to Si ratio and temperature, around 1.8 to 2, and the experimental results measured LB in the same range, between 1.5 and 2.5. By harnessing this feature, the simulation showed that boron can be removed by approximately 78 per cent in each stage. The experimental result confirmed that the boron concentration in the silicon was reduced by a total of 97.8 per cent from its initial value using four stages of slag treatment, from initial 270 ppmw down to 6 ppmw.

Aug 21, 2024

Faced with low prices and weak demand in an oversupplied market, the Australian coal industry must seek to further reduce its costs. The paper examines minesite competitiveness of the open cut coal industry in Australia with some references to the coal operations of M.I.M. Holdings Limited. The make-up of F.O.R. mine costs is analysed in order to identify where efforts should be directed to maintain competitiveness. The scope for mine site improvements through changes to working practices, the application of new technology and cost management is examined.

Jan 1, 1987

Grey River Gold Mining Ltd commenced dredging alluvial flats in the Grey River Valley in 1989.Previous drilling indicated over 100 million cubic metres of gravels with some 90% of the gold in the bottom 7 metres.The dredge built by Rahco, Spokane, was innovative in a number of aspects but particularly in the fact that a separate ladder with a cutter and pump was used to strip the overburden and a bucketline to mine the gold bearing wash below.Metallurgical studies and exploration were initiated when the project commenced; Leasing and environmental considerations were investigated and action taken.While progress is being made, the operation at this stage is not meeting required production and performance. Main problems have been with the stripping system and wear.

Jan 1, 1990

Western Mining Corporation, managing partner of the Windarra Nickel Project are in- stalling a raise-bored haulage shaft and under- ground crushing system at the Mt. Windarra Nickel Mine. The system will be the second of its type installed by W.M.C., the first being in- stalled at the Otter-Juan mine in Kambalda in 1976/77. Both haulage systems became necessary as a result of the increasing production limi- tations, and escalating costs of a deep decline mine. The Windarra haulage system required a single 3m diameter vertical raise drill hole to a depth of 470 metres. Two five tonne skips in balance will hoist crushed ore and mullock to the surface, at a design rate of 200 tonnes per hour, effectively reducing truck haulage leads by up to 50%. It is expected the project will be in full operation by mid 1982 and will enable the mine to achieve an annual production rate of 600,000 t.p.a. by 1983.

Jan 1, 1982

The light microscopic study of the physical structures of coal and associated mineral matter is an important technique in providing information on the characterisitics and possible behaviour of coals in industrial processes. However the ultrafine nature of coal and mineral particles together with the limits of resolution of the light microscope restrict such studies. Scanning electron microscopy (SEM)with its better resolution and higher magnifications is the means by which further information on coal properties can be obtained. An associated energy dispersive X-ray specrometry (EDS) method allows non-destructive in-situ chemical analyses to be carried out at the same time.

Jan 1, 1989

By Liu C. H, Juang Y. F

Coal/gas outbursts were one of the rather difficult safety problems faced in the coal mines of this Country, with coal fields characterized by frequent disturbances of folds, faults and pinch-offs. With average mining depth about 500m below surface, several such accidents occurred with up to 500 tonnes of coal outburst. In recent years, after a series of improving countermeasures had been undertaken, gas outburst accidents had been greatly decreased. The characteristics of gas outbursts in Taiwan coal mines include relating to coal petrography, mining depth and the other deformation forces. All these have been investigated, trying to determine the parameter of outbursts under natural conditions. The preventive countermeasures include predicting tests, de-stressing boring in coal seams, the emergency procedures during outbursts and certain improving options.

Jan 1, 1988

By Mayer TE

The Granites Goldfield is located 550 km northwest of Alice Springs. Mineralisation was discovered in 1900 and intermittently worked along nine km of strike until the early 1950's, yielding a recorded production of 470 kg of gold. The geological environ- ment, pre-existing exploration drilling results, and an optimistic view on gold, prompted acquisition of the property by North Flinders Mines Limited in 1975. An agreement was signed with the Central Land Council in August 1983 and drilling commenced in the same month. In the past, gold was won from alluvial deposits, rich quartz veins and lower grade, disseminated stratabound mineralisation. The last is contained within a distinctive unit in the Mt. Charles Beds, of the Early Proterozoic Tanami Complex. This informally named "Host Unit" is a metamorphosed, chemical- pelitic sediment. The schist contains variable proportions of amphibole, quartz, garnet, clinopyroxene, carbonate and sulphide, inter- calated with recrystallised chert beds. Free gold occurs in several mineralised horizons within the Host Unit, generally conformably distributed within lithologic bands or at lithologic contacts. The Host Unit occurs within a sequence of metamorphosed pelitic sediments and intermediate volcanics. Although mostly confined to the Host Unit, stratabound gold mineralisation also exists in both Footwall and Hanging Wall Schists, usually within zones displaying certain Host Unit characteristics. The deposits may be loosely categorised as being of banded iron formation (bif) type, although some important differences are noted between them and classical bif type orebodies.

Jan 1, 1984

Conveyor belt haulage offers the advan tages of continuity of operation, minimum labour requirements, and the ability to handle large volumes of material over extended periods. However, breakdown of critical con- veyors in the system can cause undue and substantial losses in production output at the working faces, unless adequate surge bin capacity is incorporated in the haulage system. A conveyor belt simulation programme, code name 'Beltsim' was developed by Bucklen et al (1968) at the Virginia Polytechnic Institute in the U.S.A. and provides a quantitative measure of the performance of a conveyor belt network design. A limitation still exists with the computer programme and involves the inability of the programme to predict the necessary surge bin capacity to overcome conveyor belt downtime. The computer programme was modified to overcome this limitation, to simulate a con- veyor belt breakdown, and to provide a quantitative prediction of the surge bin capacity necessary to permit a modern mining system to operate effectively and continuously.

Jan 1, 1977

A brief history of the significant haulage truck feature changes and the factors that influenced those changes during the 60's and 70's provide a basis for forecasting the changes that can be expected in the 1980's. A review of the impact factors and changing requirements that currently exist that will create changes. Define the critical requirements of a successful haulage truck design and discuss the availability of bigger engines and better electric drive componetry to provide deeper pit capability and improve reliability. The Unit Rig Trolley Assist System to provide improved productivity and diesel fuel savings and an economic analysis to evaluate the Trolley System is covered. The Unit Rig Automatic Truck System for a driverless truck is covered in concept and discussed from the point of view of the experience in a test in a New Mexico mine. INTRODUCTION A good basis for trying to forecast what is going to happen in the future is to go back a little bit in history, to see what the influencing elements were in different periods of time as a foundation for the forecast. INFLUENTIAL FACTORS IN THE 1960'S If you look at the truck development that occurred in the 1960's, there were some identifiable factors that give us insight. (See Fig. 1) Several things happened at the beginning of the 1960's. Mechanical drive haulage trucks were introduced that were

Jan 1, 1982

By I R. F MacCulloch

Bacterial oxidation of sulfide minerals is a familiar and commercially available process to enhance gold recovery with problem ores. Pintail Systems, a Colorado, USA based company had developed bio-processes for gold recovery based on natural mineral formation and transformation in a global mineral cycle. The biological recovery of precious metals from ore involves a number of mechanisms that are dependent on the metal-mineralogical association. These processes include: partial bio-oxidation of sulfide ores; oxidation of gangue minerals exposing gold to leaching; surfactant properties of bacteria/nutrient solutions that improve wettability of ores and solution contact with leachable gold and silver; and microbial production and excretion of trace amounts of gold lixiviants, and bio-fracturing or biological alteration of ore minerals. Pintail has demonstrated enhanced recovery of precious metals during cyanide detoxification of spent heaps at the end of mine life. Biological recovery processes also have the potential to be applied to in situ mining technologies. The in situ process application could recover gold from subgrade deposits, small deposits or those ore bodies with uneconomic stripping ratios for conventional mining. In situ biomining can be accomplished at a fraction of the cost of conventional mining and leaching and does not have the environmental liabilities associated with many conventional gold lixiviants.

Jan 1, 2004

Authority to Prospect 57P lies within the Surat Basin',' an eastern lobe of the Great Artesian.Basin, a major Mesozoic . downwarp that,had its inception'in Triassic time. The northern edge of the Mesozoic Surat Basin overlaps the southern extension of the Bowen Basin, a 'major structure that warped do*nWard in varying degrees from Permian time into Early'Triassic time: The axis of the Bowen Basin may be superimposed on the axis'of a still older structure, the Tasman Geosyncline, that probably originated in Ordovician time culminating in Late Carboniferous time.Within. or bordering the area the geologic record 'clearly marks.major differences in the stratigraphy and structure related, to"the successive evolution of these three distinct structural units. Three major phases of sedimentation have been recognised; one related to the development of the Tasman Geosyncline froi'n. Devonian to.Early Permian time (Horton group), one related to-the development of the Bowen Basin from Early Permian to_Early Tri= assic time (Bowen group), and one related to the development of the Great Artesian Basin from Triassic to Cretaceous time (Great Artesian . Group).

Jan 1, 1962

By Trumpff H

Opencast Lignite Mining requires topwall strata of seams to be fully depleted and footwall aquifers sufficiently depressurized. To prevent a spread of the cone of depression into protected wetlands some distance away, alternatives had been investigated such as closing water works, underground slurry wall barriers and recharge by infiltration. As a result of these investigations, the infiltration method has been chosen and in a first phase during the next decade it will utilize as much as 55 x 106 m3/year. Using this approach, the survival of the wet lands is assured.

Jan 1, 1988

By Boyd D. M

Minor magnetic anomalies which may be un represented on a magnetic contour map can be extracted from the original survey data and plotted by the described method to provide a rapid interpretation of the magnetic survey, provided that the data has been recorded digi- tally on magnetic tape. The example used comes from 40 kilometers south of Charters Towers, Queensland.

Jan 1, 1977

By B M. H Sharp, R P. Hide, S P. Devine

Uncertainty and debate currently pervade the mining industry in New Zealand. The operational uncertainties, whether external (eg gold prices, the exchange rate), or internal (eg coal expansion difficulties), are large. In addition, many wider factors which influence mining are in a state of flux. State Coal Mines, the operating branch of the Mines Division of the Ministry of Energy I may be made a state corporation, with the remaining Mines Division functions being revamped. The agencies administering environmental legislation are to be restructured. Mining legislation amendments have been proposed and then dropped, and the area is now to be reviewed (The Press, 31 July 1985). Some mining licences have been withdrawn, and become the subject of heated debate in the community (The Press, 19 July 1985, and subsequent letters to the editor).

Jan 1, 1985

By Waladan M, Elliot B, Rankin W. J

A survey was undertaken on the Kalgoorlie Nickel Smelter in which samples of slag and matte were taken along the length of the integrated flash smelting furnace and analysed to determine the variation of nickel and iron concentration. At the same time the oxygen potential of the slag and matte was measured using disposable tip solid-state oxygen probes. The results show that the oxygen potential of the slag is higher than that of the matte and that both decrease from the reaction shaft end to the slag tap hole end of the furnace. The slag and matte are not at equilibrium except towards the tap hole end. Reduction of nickel and magnetite from the slag occurs before the slag enters the slag-cleaning appendage by reaction with iron in the matte. Thermodynamic modelling and laboratory experiments showed that the equilibrium nickel and magnetite contents of the slag in the absence of a carbonaceous reducing agent are about 0.4 per cent and 7.5 per cent, respectively. A carbonaceous reductant is required to obtain a lower nickel content in the slag.

Jan 1, 1991

By Frew J. A, Harris M. C, Manlapig E. V

The recovery achieved in a flotation process is a function of both the characteristics of the feed stream and the operating conditions within the flotation cell. In this paper, the flotation characteristics of the streams within the Red Dog le

Jan 1, 1997

Developments in furnace construction and design have been very rapid in recent years. Larger furnaces operating at high top pressures with much improved burdens are giving extremely high production rates. Modern scientific techniques and the use of computer control are contributing to these Rates.

Jan 1, 1972

From the mid-1970s ZC Mines at Broken Hill had a policy to increase ore production rates at progressively lower head grades. In the mid-1980s the mine suffered crippling losses at a time of low metal prices. An important contributory factor was the inherent geological distribution of metal grades in the seven defined ore lenses. Grades are bimodal, and perhaps, trimodal, in each ore lens. There is a tonnage deficiency in the critical cut-off grade zone of 7-10% Pb+Zn. Lowering the cut-off grade introduced siliceous and pyrrhotitic material which resulted in significantly poorer metallurgical performance. This example shows that the mine geologist needs to know the grade distribution of the orebody and to convey clearly the downstream implications of changes in the head grade.

Jan 1, 1990

The Kidston breccia pipe is situated approximately 280 km west northwest of Townsville, north Queensland. It is currently Australia's largest gold producer with production varying between 8,000 and 16,000 tonnes of ore per day. Current reserves are estimated at 36.2 million tonnes averaging 1.74 C/t Au and 2.21 g/t Ag. Alluvial gold in the gullies surrounding the deposit was first discovered in the 1880's and between 1907 and 1948 small scale open cut and underground mining was undertaken. Advances in extractive metallurgy and an increase in the gold price were major factors influencing the recent exploration and development of large scale mining of the deposit by Placer Pacific and Kidston Gold Mines. The breccia pipe is trapezoid in shape with surface dimensions of 1100 m by 900 m. Clasts show only limited evidence of mixing during brecciation, with the pre-breccia stratigraphy still discernible on the basis of clast types. This lack of mixing together with the intimate association with intrusive activity, suggests that the brecia formed by collapse, probably associated with the escape of a large volume of irothermal fluid from a crystallising hatholith. Mineralisation and alteration are also sratially and temporally associated with rhyolite emplacement and brecciation. Pre-breccia mineralisation consists of laminated stockwork quartz veins associated with muscovite, quartz and orthoclase-epidote alteration. Stockwork veins contain either anomalous molybdenite or gold. Uneconomic early stage post-breccia mineralisation and alteration consists of cavity infill quartz-epidote and calcite associated with potassic and propylitic alteration respectively. Economic late stage post-breccia cavity infill and sheeted veining consists of quartz-carbonate-sulphide infill associated with phyllic alteration. The grade of gold mineralisation generally decreases downwards in the system with an increase in the amount of pyrrhotite relative to pyrite. Pre-breccia stockwork quartz veins mineralisation is genetically related to the

Jan 1, 1987

A brief review of the problems in ventilating and cooling deep and hot Australian mines is presented. An overview is given on the development of the controlled partial recirculation concept. The main part of this paper describes the first majo

Jan 1, 1994