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By Agrawal R. D, Kapoor M. L

Activity of FeO in the ternary system MgO-FeO-CaO in contact with metallic iron has been measured at 1000 K employing the cell.PtIFe, (Mg, Fe, Ca)OIZr02 - CaOIFe, FeOlPt. Measured data are used to study the phase stability relations in the system MgO-FeO-CaO and an isothermal section at 1000 K through this system is drawn.

Jan 1, 1987

The CSIRO acid alumina employs the essential steps of digestion, hydrolysis and calcination to produce pure alumina from ores too high in silica or too low in grade for the Bayer process. The two latter stages have been described in some detail previously but the digestion stage requires separate dis-cussion since ores vary widely in composition and reactivity. Kaolinitic clays require. roasting to 8000C to render the alumina soluble in the 11 per cent sulphuric acid used in the process while some ferruginous laterites require roasting to reduce the reactivity of iron minerals. The iron content of pregnant solutions is kept at a low figure by digesting at temperatures where the solubilities of ferric oxide or basic ferric sulphates are small. A.two-stage, counter-current digestion is necessary to extract a high percentage of alumina from the ores and to pro-duce a basic pregnant liquor, with an S03:Al203 ratio of 1. 9 suitable for high temperature hydrolysis. The second stage of digestion, called the modification stage, treats slightly acid liquors with exces's of ore in the temperature range 1200- 1400C. The first stage operates at 1700-190 C to extract further alumina from modification residues, using recycled acid obtained from later steps of the process. Both temperature ranges are critical for economic operation and for proper con-trol of the iron content of solutions. In batch experiments, thirty minutes is regarded as a suitable retention time for digestion and modification; ores which require much longer than this are less suitable for the process. Impurities. such assilica, titanium and vanadium oxides are discarded in the residue along with iron oxide and do not contaminate the final product. Bivalent metallic sulphates such as MgSO4 can build up in the circuit to a very considerable degree without affecting. product purity.Comparison with other processes shows that the C. S. I. R. O. process is superior for control of contamination by iron, which is the major problem in acid processes. The pure intermediate product (3 A1203. 4 S03. 9 H2O) is also more convenient for cal-cination to alumina than the hydrated aluminium sulphate usually recovered in other processes. Detailed cost comparisons must await pilot-plant evaluation of the C. S. I. R. O. process.

Jan 1, 1963

Wet mining of auriferous gravels at L & MÆs Waikaka operation in Southland creates spoil dumps derived from stripping of a clay rich overburden, tailings from past dredging and the processing of auriferous sands and gravels. Over recent times, spoil dumps have slumped on six occasions, threatening the viability of the wet mining operation. Close examination of slump morphology, coupled with the sequence of material placement and rate of dumping suggested a mechanism associated with undrained failure of a 2 m layer of silt and sand tails forming the base of dumps.Commencing with some information on the geotechnical properties of source overburden, back analysis of failure morphology and sequence and development of undrained loading conditions from first principals, the most likely failure mechanism and factors controlling failure were defined. Based on analysis results, a scheme to stabilise the lowwall dumps was developed and implemented, augmented by continuous monitoring of pore pressures in the basal wet tails, and laboratory testing for confirmation of computed material properties.Lowwall spoil stability has improved since implementation involving changes to the method of spoil loading, and modification of wet tails composition to improve permeability and drainage of the basal wet tails under load. The method and approach to prediction and verification of failure mechanism provide a sound basis for continued mining of deeper auriferous gravels.

Jan 1, 2002

By R Lau

The fire safety design for road tunnels includes the following aspects: active systems, passive provisions and operational procedures. The active systems include the smoke control system, fire suppression system, detection system and fire fighter’s assistance systems. Passive provisions include escape passages, fire separation and fire resistance systems. The operational procedures refer to fire fighter access, reporting and alerts, evacuation processes and crowd control.Currently, these systems are typically designed by different designers or teams. These systems are intended to work together in a coordinated manner to provide the desired safety outcome. However, in practice, this is not always happening. The fire engineering process is supposed to bring together all these aspects and arrive at an integrated safety system. The fi re engineering process in practice is not integrating the design with the practice or reality and is thus arriving at less than desirably efficient safety systems.The example of design inputs shows how disconnected each system design basis is. The smoke control system design is based on the design fire size. The performance of the smoke control system is to achieve a smoke free environment for a defined space for a particular fire size – the design fire. The fire suppression system – most commonly sprinklers or deluge systems, is designed according to codes and to achieve a certain water discharge rate. The fire detection system is designed to detect temperature rise/rate of rise and perhaps density of smoke. Fire separation is determined to provide a certain period of service – mostly for structural elements. Escape route size and location is determined mostly by code compliance. Evacuation procedures are determined by Authority operational requirements rather than human behaviour.To arrive at an integrated fire safety system, the design basis and performances must be coordinated. An approach using fire scenarios would ensure all systems are designed to a common performance requirement. This paper will discuss how the current design approach outcomes compared with a fire scenario approach. More effective and efficient fire safety systems would require the stake holders to understand the implication of this approach and to embrace this through the fire engineering process.

Mar 8, 2011

Traditionally, the gravity cleaning of coal has been evaluated in pilot plant tests. Attention is now turning to the development of empirical models of gravity cleaning equipment that can be used for the design and evaluation of circuits. This paper presents some preliminary information for spirals and water-only cyclones treating fine coals. Also discussed is how such information gives a better understanding of the operating and performance characteristics of this equipment, how realistic comparisons can be made between different types of equipment, and how small mobile plants could be designed for treating the fine coals 'stockpiled' at many NZ mines.

Jan 1, 1985

Thank you for this opportunity to address your conference on 'The role of coal in the New Zealand energy market'. New Zealand's energy market has, in common with much of New Zealand, undergone major change following the market reforms of the Labour Government. As far as the energy sector is concerned this change has been for the better, as it has created for the first time in a very long time a 'true economic market' for energy in New Zealand. This is in marked contrast to the previous regime where: ò Electricity was state operated, subsidised and cross subsidised. ò Oil was imported and subject to a raft of taxes and duties. ò Coal produced by state mines was priced by cabinet committee, based on other energy prices rather than on the costs of production and delivery of the energy product. Today, with the establishment of the SOE's we have a market of competitive supply, where the customer has the choice of energy with prices based on the true costs of production and delivery. This can only be good for the customer as the cost is now based on the real costs of production, not on political whim. So where does coal fit in this brave new world of free market energy supplies? Well, opportunity, they say, knocks but once.

Jan 1, 1990

By D Thomas

Geochemical data related to AMD for the West Coast and Southland regions have been collated into a relational database and GIS system. The types of information include; rock geochemical data, water chemistry data and aquatic macro-invertebrate abundance data. This information will be combined with eco-toxicology experiments to determine impact thresholds on aquatic ecosystems. Ultimately these datasets will be combined with remediation investigations to produce a Framework to assist decision making related to mine planning, consent and compliance.   Current geochemical research examines the controls on As concentrations downstream of gold mining areas and the variability of AMD from Brunner Coal Measure rocks. Assessment of factors that control the chemistry of Brunner Coal Measure AMD such as mine type, hydrogeology, geology, geochemistry and climate is in progress. Minerals that control the concentration of aluminium downstream of AMD point sources include alunite, jurbanite and various forms of Al(OH)3.

Jan 1, 2005

By W J. Rankin, D R. Swinbourne

There are large tonnages of low-grade manganese ores in India fromwhich it is uneconomic to produce ferroalloys by conventionalsubmerged arc furnace smelting. A possible way to utilise these ores is to smelt them with carbon to produce pig iron and a manganese-rich slag, then to metallothermically reduce the molten slag to silicomanganese. Thermodynamic modelling of the metallothermic reduction stage using aluminium, silicon or aluminium-silicon alloy as the reductant at 1450¦C showed that an acceptable grade of silicomanganese could be produced. Manganese recoveries were predicted to be about 80 per cent. Heat balances indicated that silicothermic reduction may not produce enough heat to maintain reaction temperature. Small-scale laboratory experiments showed that the manganese grade of the alloys, and the manganese recoveries, were close to those predicted, but those for silicon were muchlower. Aluminothermic reduction produced the highest grade manganesealloy. The slag-metal equilibrium involving manganese, silicon and their oxides was investigated and it was found that equilibrium was not attained in any of the experiments, due probably to the very low rate of reactions involving silicon. This could be used to advantage in practice to achieve higher manganese levels in the alloys.

Jan 1, 1998

By R L. Brathwaite

In New Zealand, volcanogenic massive sulfide (VMS) deposits are found in three main geological environments associated with: 1.   ophiolitic basalts of Oligocene age in Northland and East Cape (eg Pupuke, Pakotai, Parakao and Lottin Point); 2.   with chert and pillow lava in greywacke sequences of Permian-Jurassic age (Torlesse and Waipapa terranes; eg Kawau Island, Te Kumi and Maharahara) and their metamorphic equivalents (Haast Schist; eg Moke Creek and Waitahuna); and 3.   with greenschists (metabasalts) and metaserpentinite of Permian-Triassic age (Ponamu Ultramafics) in Westland (eg Bowen and Wilberg ranges). The deposits consist of small lenses of disseminated to massive sulfide minerals, mainly pyrite and chalcopyrite. Small quantities of copper ore were mined from some deposits in the 1800s (eg Kawau Island from 1846), with the last mining at Parakao from 1961 to 1966. Several deposits have been recently examined for their gold potential with assays on sulfide rock samples as high as 75 g/t Au (Lottin Point).

Jan 1, 2005

Downhole survey uncertainties observed at various De Beers operations prompted an investigation into their possible effect on deposit shape and volume. An accurately surveyed artificial æboreholeÆ was constructed and different downhole survey instruments tested. In this way an empirically determined error range of 0.1 per cent to ten per cent was derived for downhole survey data. These survey errors were applied to an orebody model at an existing mine. Visualising the sphere of uncertainty associated with a borehole trace using a general mining package (GMP) gives an indication of possible volume variance. The resulting orebody maximum and minimum volume scenarios for three different depths (200 m, 500 m and 800 m) are presented. For certain instruments and borehole angles, the 3D positional error can be as high as 100 m at 1000 m down the hole. At depths below 200 m the resulting volume deviations can become significant for borehole survey errors exceeding 0.35 per cent. At 800 m depth the volume difference can approach 25 per cent. These figures assume that the error is compounded. The impact of these downhole survey errors is greatest for pipe-like orebodies such as porphyries and kimberlite pipes. Subhorizontal sill-like orebodies (and coal seams) will not be significantly affected by these errors. The impact of this type of survey error needs to be stated (and quantified) and is significant in JORC classification.

Jan 1, 2009

By O Jones

Longstanding occupational health challenges of the underground hard-rock mining sector require both an analysis of historical data to assess evidence of linkages between the source of the problem and subsequent illnesses, as well as investigating the means by which health risks to workers can be eliminated or minimised. This paper refers briefly to a recently established National Health and Medical Research Council (NHMRC) sponsored Epidemiological Study into the incidence of Lung Cancer, contracted by mineworkers in Western Australia (WA) due to the inhalation of diesel exhaust fumes from 1996 to 2012. Thereafter it reviews current knowledge of the nature of the challenges facing those responsible for the health and wellbeing of underground hard-rock miners in WA, commencing with the recent categorisation of diesel exhaust as ‘Carcinogenic to Humans, Group 1’, by the World Health Organisation’s (WHO) International Agency for Research on Cancer (IARC). An attempt is also made to explore how the challenge has changed with the adoption of more advanced engine technologies, including the increased generation of ultra-fine volatile organic and other nucleates, submicron carbonaceous agglomerates and toxic gases.The compounding effect of using the mine decline access entry as both the primary ventilation intake and haulage-way is also discussed, as is the need to develop a more appropriate metric for regulating diesel engine emissions. Finally the paper refers to ongoing in-mine research pursued by the National Institute for Occupational Safety and Health (NIOSH) at its Diesel Laboratory in an underground limestone mine near Morgantown in the USA.CITATION:Jones, O, 2015. Diesel exhaust and the underground miner in Western Australia, in Proceedings The Australian Mine Ventilation Conference, pp 167–172 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 31, 2015

By C Li, S Wang, L Qiao

Jinchuan nickel mine is the largest nickel mine in China. Cut-and-fill mining method with high density cementing materials is used in the mine. The original mining design divided the mining operation into two steps. The first step stopped the mining rooms and the second step stopped the pillars. Because the two-step method made big trouble for finally mining pillars and strongly limited the mining speed and production, it was successfully changed to a continuous cut-and-fill method without pillars. However, the mining operation in the mine has been down to 800 m and the mining condition is getting worse and more complicated. Through systemetical field investigations and 3D FEM analysis, it is proved that the mining method without pillars is feasible for mining deeper orebodies in Jinchuan nickel mine.

Jan 1, 2000

The importance of reducing the moisture content of fine coal, the nature of the retained water, and the means of its removal are discussed. A statistical technique, using a balanced block design, was used to isolate the significant factors determining water content of a coal filter cake. The most significant factor was particle size distribution. A simplex evolutionary operation (evop) was used to determine the optimal quantities of additives required to produce the lowest moisture content for a selected coal size. For this optimum condition (18·6 Ib H20 per lOO Ib dry coal), additions of 0·045 Ib magnesium ion, 0·0026 lb Separan AP30, and 0·098 Ib Aerosol OT, per lOO Ib dry coal were required. The work illustrated the uses of a statistical evop technique for the determination of optimal conditions in industrial research projects.

Jan 1, 1970

By J M. Galvin, B J. McKinnon

Lightning Ridge, Australia, is the largest opal producing area in the world. Most opal is mined from shallow underground mines by individuals or small partnerships with the industry having been protected from large-scale development to date. The safety performance of opal mining has lagged both general mining industry standards and community expectations. The application of geotechnical analysis to the opal fields has the potential to considerably reduce injuries and fatalities. With consideration of the local culture, preliminary geotechnical analysis has been applied to some current methods of work utilised at Lightning Ridge. Practical solutions have been advocated and are presented in this paper. Improvements to safety generated by these practical solutions indicate that further geotechnical research at Lightning Ridge is warranted and would be beneficial.

Jan 1, 2002

By B Bamford

High speed diamond cutting has extensive applications in civil and mining engineering. A project involving the diamond sawing of black granite is investigating the nature of the diamond cutting process. A sawing machine was devised to adjust the cutting load and measure cutting speed. Cuttings were collected for size distribution analysis. The surface produced by interaction between diamond. grits and the rock was subjected to microscopic investigation. Increasing load prompts the proportional increase in the cutting rate. But the mean size of cuttings shows little change. The photomicrographs of the cutting tracks indicate neither patterns of crack formation nor signs of the ductile behaviour of the rock. A diamond cutting model for hard rock is formulated on these observations. Diamond cutting is a process of surface failure, which advances in four stages. The polycrystalline characteristics of a hard rock and the action of high-speed diamond grits guarantee the creation of crack nuclei which develop into cracks in various directions. This network crisscrossing cracks enable the stripping of this surface layer from the rock.

Jan 1, 1992

By Hawkins L. V, Seedsman K

A combined reflection seismic and magnetic survey off the south coast of New South Wales has revealed six distinct reflection horizons within the Lower Triassic- Upper Permian sequence, and has enabled the upper part of the Illawarra Coal Measures to be mapped in considerable detail. Large magnetic anomalies in the eastern half of the survey area appear to originate in the Gerringong Volcanic Sequence which forms the magnetic basement in this survey. Small residual anomalies in the western half of the area can be correlated with small scale faulting and folding in the uppert part of the Illawarra Coal Measures, as revealed by the seismic reflection survey. A synclinal axis striking at approximately 55¦ has been mapped near the western margin of the survey area, and areas of faulting and folding have been outlined by com- bined analysis of seismic and magnetic results.

Jan 1, 1969

By Tilley H. L

The 90 m deep Yallourn Open Cut brown coal mine in the Latrobe Valley, Victoria is developing into an area close to a reverse fault. A major batter stabilisation program, matched to ongoing operations, has com- menced to maximise coal recovery where the fault is within 100 m of the Open Cut. The various mine development options considered during the planning stages are outlined. These options were formulated in a back- ground of geotechnical constraints and the need to maintain continuous and reliable coal supply at a time when a new coal field would be developed. The geotechnical investigations and analysis procedures under- taken to determine stability of the batters during their excavation are presented. The geotechnical constraints on the mine design and opera- tions required to ensure safe working conditions are detailed. Current operational and batter stability conditions are considered satisfactory.

Jan 1, 1989

By Moritz P

Thiourea has been recognised for a long time as an acid-stable complexant for gold. Generally, the use of thiourea has been shown to exhibit enhanced leaching kinetics compared to cyanide but suffers the disadvantage of excessive reagent consumption. Thiourea leaching is particularly com- patible with the extraction of gold from refractory ores. This is due to the need for an oxidative pretreatment to liberate the gold. Such pretreatments typically result in the production of an acidic residue. The application of novel thiourea leaching technologies to the extraction of gold from a bioleached pyrite concentrate was investigated. The interac- tion of leach variables with thiourea consumption and gold extraction was established. An economic assessment of thiourea leaching was compared with conventional cyanidation. The results indicated that gold leaching of the bioleached residue using thiourea compared very favourably with cyanidation.

Jan 1, 1991

By Coates D. F, Neil T. J, O&apos

A proper economic analysis of pit slope design must reflect the trade-off between the benefits and the increased risks of slope fail- ure inherent in steeper slope angles. However, no formal framework for a proper analysis existed to date. This paper describes the results of the past four years' effort in which a formal eco- nomic analysis framework was developed and tested through a case study. This framework, in essence, consists of the availability of tested procedures and com- puter programs. The procedures as well as the programs are divided into two broad functional categories; (1) the first category related to assessing the economic benefits and costs associated with various pit slope angles and (2) the second category that determines the overall financial impact which the assessed benefits and costs exert to the mine operator's overall economic stature.

Jan 1, 1977

The problem of comparison of island arc's andesites in terms of petrochemical data is exa- mined. It is definitely established that only two main factors exist controlling the petroche- mical variety of the Kurile arc's andesites.Ori final multivariate statistical technique and computer software are used to extract these fac- tors. It is shown as well that the chemical com- position of igneous rocks depends on the type and structure of the Earth's crust. The follo- ~cing interpretation is proposed for the two factors describing petrochemistry of andesites: the first one is the depth to the Benioff seis- mofocal zone and the second one is supposed to indicate the position of the peripheral magma chambers. The basic trends of variations in the chemical composition components depending on the changes in the controlling factors are de- Tcnnined.

Jan 1, 1987