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By Gray N. B, Floyd J. M

To gain further understanding of the operating efficiency of the BHP Slab and Plate Products Division (SPPD) RH vacuum degasser, physical and mathematical model studies of the process have been undertaken. The purpose was to investigate how the various process parameters affect the liquid circulation rate, to visualise the flow patterns, and to identify and eliminate the cause of localised wear in the downleg. In the physical model mixing times were measured using an acid tracer technique. The results were applied to predicting trends in times required to obtain homogenous melt composition under varying conditions. A 2-dimensional mathematical model describing the liquid metal flow has been developed using the PHOENICS fluid-flow package. The physical model results were simulated and incorporated into the mathematical treatment and an improved design for vessel geometry is proposed. The effect of rounding the downleg entrance or installing a baffle between the legs is discussed.

Jan 1, 1987

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

Grade control is an important factor in the on-going success of a mining operation. Grade control criteria will vary depending on the commodity being mined. Financial considerations determine the actual grade control criteria at any one mine site. Mining and metallurgical capital and operating costs are ultimately used in ascertaining cut-off grades employed in grade control. The metallurgical characteristics of the ore, and ultimately the equipment selection and design of the plant, are based on samples provided by the exploration geologist. Ore variability is an important factor in designing the process plant. Ore variations, outside of those catered for in the design, as well as large ore changes on a daily basis, will impact on the metallurgical performance, and hence the economics of a mining operation. Therefore good liaison between the grade control geologist and metallurgist will undoubtedly lead to a more consistent, and more profitable mining operation.

Jan 1, 1993

By Wright D. C

The operation of the cyanide-sensitive Mintek/TB1 kegold electrode was studied in the laboratory, with regard to equilibration time and drift, the effects of pH, stirring, salinity, dissolved oxygen, zinc and copper(I) ions. Methods for valid calibration in the range 20-600 mg(NaCN)/L and pH values in the range 9 - 12 in the absence of copper were also studied. Increasing the salinity beyond a threshold of 40 g(NaCI)/L improves calibration and measurement. The sensitivity is 91 mV per decade change in the concentration of ionic cyanide, and output is reproducible to within 10 mV with attention to the factors listed above. However, salinity of 40 g(NaCI)/L also sensitises the electrode to interference by copper(1) ions. This copper sensitivity seems capable of saturation, suggesting a research strategy for possible remedies.

Jan 1, 1996

By Dredge K, Becker G

The successful dissolution of the valuable metal components of a solid phase is often a basic requirement for a successful hydrometallurgical treatment process. Sulphide concentrates are often an intermediate product in the production of refined metals. These concentrates need to be further processed to realise the contained metal values in a useful form. Pyrometallurgical techniques have tended to dominate, at least the initial treatment of metal sulphide concentrates. The technology described, Activox«, has been developed specifically for the hydrometallurgical treatment of these sulphide mineral concentrates, in particular those containing copper, nickel or gold. The Activox« dissolution technology coupled with the use of existing, or newly developed, downstream processing techniques, offers alternative processing options for the recovery of full value, saleable metal products. The technology is suitable for application down to relatively small scales opening up the opportunity for on-site production of metals even at modest scale mining Operations.

Jan 1, 1995

By Bangerter PJ

The use of gravity concentration is, and has always been, the conventional primary method for gold recovery from alluvial deposits. The development of high capacity cone concentrators and metallurgically efficient wash-waterless spiral separators has had some impact in the technology for alluvial gold processing, but perhaps more significantly has led to the relatively recent use of this gravity concentration technology in grinding circuits of hard rock ore for "coarse" gold removal and for scavenging gold locked in sulphides from cyanidation tailings streams.Gravity concentration systems are relatively low-cost, non-polluting and energy efficient; and their judicial use in gold treatment plants can significantly reduce overall capital and operating costs.The application of modern gravity concentration technology to hard-rock and alluvial gold ore treatment is discussed. Flowsheets and test and operating data from a number of gold processing operations incorporating gravity concentration treatment are presented.

Jan 1, 1984

By E E. Hall, C D. Taylor, D S. Yantek

Regular monitoring for methane gas is required near working faces in gassy underground mines where the potential for methane ignitions is greatest. However, high concentrations of methane can also accumulate outby the face where methane levels are monitored less frequently. Wearing a personal methane monitor equipped with an alarm could protect persons working in these outby areas from injury or death due to methane ignitions. The National Institute for Occupational Safety and Health (NIOSH) has conducted studies to evaluate methanometers that could be used as person-wearable monitors. For the present study, seven different person-wearable monitors that are not currently approved for underground use were evaluated. This paper describes test procedures used to evaluate performance of methane monitors that could be used underground for continuous personal monitoring of methane. The information in this report provides data that allows the reader to make side-by side comparisons of these instruments.

Jan 1, 2005

By Heape JM

Production from the Cattle Grid orebody commenced in August, 1974. This followed a recent discovery arising from an extensive exploration programme involving stratigraphic drilling, geochemistry and geophysics. Located some 4 km west of the original copper occurrences at Pernatty Lagoon the discovery was found to contain 4.6 million tonnes of ore averaging 2.4% copper. The ore is a "sandstone copper" type localised near the disconformity between two Precambrian (Adelaidean) stratigraphic units, the Pandurra Formation and the Whyalla Sandstone. The mineralisation roughly follows the interface between these units and occurs in fractures, vugs and along bedding planes. The mineralogical character of the ore is somewhat complex consisting of chalcocite and bornite, with associated chalcopyrite, sphalerite, pyrite and other less common sulphides. 1. Senior Geologist, Pacminex Pty. Limited, Sydney, N.S.W. 2. Mine Geologist, for Mt. Gunson Mines, Pacminex Pty. Limited, Mt. Gunson, S.A.

Jan 1, 1975

To gain further understanding of the operating efficiency of the BHP Slab and Plate Products Division (SPPD) RH vacuum degasser, physical and mathematical model studies of the process have been undertaken. The purpose was to investigate how the various process parameters affect the liquid circulation rate, to visualise the flow patterns, and to identify and eliminate the cause of localised wear in the downleg. In the physical model mixing times were measured using an acid tracer technique. The results were applied to predicting trends in times required to obtain homogenous melt composition under varying conditions. A 2-dimensional mathematical model describing the liquid metal flow has been developed using the PHOENICS fluid-flow package. The physical model results were simulated and incorporated into the mathematical treatment and an improved design for vessel geometry is proposed. The effect of rounding the downleg entrance or installing a baffle between the legs is discussed.

Jan 1, 1987

The Lake Rotokaua sulphur deposit, near Taupo, New Zealand, is a lacustrine sedimentary ore body, 220 acres in area and from 7 ft to 96 ft thick, containing, within the area drilled to date, some 20 million long tons of ore averaging 25% elemental sulphur in unconsolidated tuffaceous diatomaceous clay, overlain by about 120 ft of pumice sand and by the shallow Lake Rotokaua. An additional amount of perhaps 4 million tons of sulphur is regarded as probable in the area remaining to be drilled. Current economic studies cover the problems of mining an unconsolidated water-saturated formation with some residual thermal activity nearby; conservation and restoration after mining in a scenic recreation area; beneficiation of the ore and extraction of high- purity sulphur, principally for fertilizer manufacture. The deposit has additional importance as a pointer to possible further discoveries in the Thermal Region.\

Jan 1, 1971

By Rieniets S, Somerville J. L

In Morwell Open Cut brown coal mine, the overburden 'firehole' materials which have resulted from ancient coal fires vary-from hard baked clays to firm laminated lacustrine clays. The need to pre-strip designated areas to reduce the slope height and attain safe digging conditions for the bucket wheel excavator operation is now accepted practice at the open cut mine. In this study, the inherent spatial variability of undrained shear strength of the clay materials has been incorporated in a visco plastic, finite element based, probabilistic slope stability analysis. Data on the costs of initial pre-stripping, excavation and slope failure are collected to provide an economic basis for the optimisation of the design of the overburden batters in Morwell Open Cut. This improved stability modelling is enabling costly pre-stripping to be minimised while ensuring acceptable slope stability conditions and minimising the risk to personnel and plant.

Jan 1, 1994

By Kissell F. N, Thimons E. D

The Bureau of Mines used sulfur hexafluoride (SF6) tracer gas to evaluate the effectiveness of gob ventilation and/or sealing practices at three coal mines, each having different problems associated with their mined- out areas. The purpose of these ventilation studies was to better understand whether current techniques employed for ventilation or sealing are successful at minimizing the potential for gob fires and explosions. The work performed at each mine is discussed: One is a longwall operation that uses ventilation to carry off hazardous gases, and two are room- and-pillar operations, each with far different concerns, that seal off the gobs to isolate them from the main mine ventilation. In all cases, employment of the Bureau's SF6 tracer gas technique resulted in answers to questions raised by the mine operators concerning the effectiveness of their gob ventilation or sealing practices in preventing mine fires.

Jan 1, 1988

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 Waters A. G, Nightingale R. J

The quartzite added at the blast furnace for the purpose of adjusting the chemistry of the burden inputs is shown to have a disproportionate impact on both the level and the variability of the hot metal silicon (HMSi). This conclusion is supported not only by direct correlation involving data from five blast furnaces, but also by mass balances. In one case the R2 correlation coefficient was 0.96 and the mass balance was accurate to within five per cent for a wide range of quartzite additions. The results indicate that as much as 43 per cent of the silicon in the added quartzite reports directly to the hot metal. Indeed, silicon from quartzite was found to be much more likely to report to the hot metal compared to silicon from regular sources (eg coke and sinter), reflecting differences in the activity of the silicon source.

Jan 1, 1994

By Smith PE

The main components of face design are the power loader, face conveyor and powered support system and the interaction of these components determines the effectiveness of strata control. A major influence upon the interrelationship of this equipment is the geological environment, of which seam thickness appears to play an important role. Recent thick seam experience indicates a significantly different characteristic behaviour pattern from that observed in thin seams The structural integrity of the face wall is particularly influenced by seam discontinuities such as natural joint planes and mining-induced fractures in the yield zone ahead of the faceline. In addition, the presence of stone bands or dirt partings in the seam offers interfaces for uncontrolled release of blocky material. Some case study experience at British collieries provides a comparison with performance data at a specific location, that highlights the importance of coal face layout and design.

Jan 1, 1986

Since the discovery of coal of the Southern coalfield (Illawarra 1797, Burragorang 1806) coal mining has grown progressively to the thriving industry of today. Early shallow escarpment mining required no serious access development, but with extension of mining to further and deeper areas, sinking became necess- ary. Now, with 17 major shafts and 7 decline drifts in current use, new mining activities involve several current sinking and drifting projects, with more in prospect. Conventional sinking and drifting, using blasting and mucking techniques proven in recent years are normally in use, with attempts, recent and current to accelerate advances by boring techniques. With export and to less extent local market unpredictability, it is vital to produce mine establishment times to allow advantage to be taken of market upswings and there is great need for research and improvement of mine access construction as the major aspect of establish- ment.

Jan 1, 1976

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

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

The stratigraphy of the Singleton Coal Measures is reviewed and a revised stratigrapixy which has been ratified by the N.S.W. Standing Committee for Coalfield geology is nominated and defined by a selected type section. Withir the type section the occurrence of repetitive phases are illustrated and described. Coal. Measure units within the Singleton Coal Mean sures, termed the Wollombi and Wittingham Coal Measures respectively, are correlated with the Newcastle and Tomago Coal Measures. In formal nomenclature the Singleton Coal Measures are designated the Singleton Super Group. The major depositional cycles within the Coal Mea- sures are outlined together with those lesser phases within the Coal bearing sequences that influence the mining conditions likely to be encountered. Both tectonic and sedimentary features of the Singleton Coal Measures are considered and the localized post depositional effects on the coal seams and roof strata in- duced by differential, compactions are emphar Sized.

Jan 1, 1972

In comparisons of a trial extruded brick containing 33 per cent coalwash and 67 per cent clay and a trial pressed brick containing 100 per cent coalwash with a standard extruded clay face brick, the mixed feed stock trial brick compared favourably with the standard brick. If a highly plastic clay is used to mix with the coalwash, satisfactory results are obtained in respect to dimension, strength, water absorption, efflorescence, resistance to salt attack, hardness, colour, weathering, mineralogy and porosity. Although a brick containing only coalwash can be successfully manufactured in a press, its mechanical and physical properties are inferior. This mixed feed stock brickmaking technology leads to the utilisation of a by-product with a potential saving of raw material costs. The extent of use is likely to depend on the proximity of the coal washery and the brickworks and the economicsof transportation costs.

Jan 1, 1992