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By Mauk JL, McOnie A, Simmons SF

Three cross sections, 200 m apart, display the distribution of indicator hydrothermal minerals across the Empire zone of the Golden Cross epithermal Au-Ag deposit, Waihi, New Zealand. These minerals are used to interpret the temperature and composition of hydrothermal fluids. The distribution of interstratified illite-montmorillonite and illite indicate that temperatures ranged from 140 to >220¦C, with temperatures above 220¦C predominating. The mineral assemblage of quartz-adularia-chlorite-illite-calcite-pyrite envelops the Empire vein system and stockwork, and reflects formation from an alkali chloride water, whereas the mineral assemblage of replacement calcite-interstratified illite - montmorillonite- kaolinite forms a carapace and reflects formation from a C02-rich steam-heated water. Alkali chloride waters appear responsible for the epithermal Au-Ag mineralisation.

Jan 1, 1995

By Ito H, Noguchi F, Ueda Y

DTA curves of synthesis lead sulfide and commercial. lead concentrates during oxidation were measured to clarify the mechanism of ox- idation of lead sulfide. The oxidation reac tions could be divided to elementary reactions with production of basic lead sulfates such as 2PbO PbSO4. An existance of iron sulfide played an important role of the oxidation of lead concentrates. The oxidation rates of lead sulfide were measured in the wide range of oxygen potenti- als using IR type SO2 gas-meter. The oxidation rates under low Po 2 which corresponds to the direct oxidation smelting were much lower than those obtained under high Pot. The combustion temperatures of lead sulfide were also measured by hot thermocouple method. Those values were extremly low compar- ing the oxidation temperatures obtained by DTA.

Jan 1, 1987

Material hardness and environmental factors can limit or restrict conventional blasting techniques and this has led to advancements in the performance and efficiency of ripping. Not all materials can be ripped, however today's technology and experience can help make a reasonable prediction. A ripping versus blasting decision will depend on the total volume of material to be moved, the production capabilities and costs of the ripping tractor(s) and on the size and relative efficiency of drilling and Blasting.

Jan 1, 1995

By Bartrop S. B

Mount Isa mine has a long history of successful exploration since discovery 70 years ago. Remaining reserves, although substantial, exist in a scheduling framework which involves long-term production from new ore sources with attendant technical risk and major capital investment. Current exploration aims to incrementally increase reserve tonnage to maintain existing production levels as well as to provide a buffer for potential start-up delays from new ore sources. Exploration also aims to increase the net present value of the operation by discovering new major orebodies around the Mount Isa and Hilton mines.

Jan 1, 1993

Electron paramagnetic resonance provides a fast method to characterise quartz. Quartz from veins associated with the Cambrian massive sulphide deposits in the Mt Read Volcanics of western Tasmania and from Devonian reefs associated with gold mineralisa- tion at various localities in Tasmania exhibit specific EPR patterns, different from quartz from common veins. The intensity of the EPR spectra of the quartz can be used as a statistical guide to gold mineralisation at Beaconsfield.

Jan 1, 1987

Maintaining and improving the economics of open pit mining in the future requires understanding of the characteristics of open pit mining that are different to other mining or business activities, designing mines in the first place to be less susceptible to changes in these important characteristics, and adopting strategies which yield reliable returns despite unforeseen change. Planning and production personnel require guidelines and performance standards that are based on sound economics not solely on production criteria. The guidelines adopted for long-term implementation must assume a declining price for mineral products along with declining real costs, with research efforts directed at development of both evolutionary and revolutionary ideas aimed at implementation. Decision-making must focus on risk and probability criteria rather than just simple return-on-investment criteria, and the approach for management of personnel must support the higher level of communication essential for fast decision-making in the new environment of continual change.

Jan 1, 1992

The Mobile Miner MM130 was delivered to Broken Hill in February 1992. During March the machine was extensively trialled on the surface to test manoeuvrability, climbing ability and muck handling prior to being trammed underground in April. The first cutting test on 30 April 1992 provided promising results. The machine has undergone continual development since it arrived in Broken Hill with aims of ensuring reliability and achieving performance goals. The paper gives a detailed account of recent performance comparing this with the predicted Performance.

Jan 1, 1993

The central thickened discharge system of tailings disposal takes advantage of the natural beach slope formed by sub-aerially discharged tailings, and the non-segregating properties of thickened tailings, to create a homogeneous conical stack. The need for containing embankments can be largely avoided leading to capital and operating cost savings. Methods for estimating beach slopes and tailings density, essential parameters for the design of such a system, are described. Case histories from three mining operations are used to illustrate the application of the technique, There are also seen to be potential advantages in the areas of water management, seepage, and rehabilitation. Laboratory and in-situ testing enable parameters to be determined.

Jan 1, 1991

By Watson K, Pollard D. M

The electrolytic recovery of metals from solution requires an understanding of the characteristics of the particular system employed, and the current efficiency and morphology of the deposit are influenced by such factors as cell design, metal ion and supporting ion concentration, acid concentration, temperature, impurity levels and cell design. The electrolytic deposition of both cadmium and silver present individual difficulties, and special cell designs are used for each of these metals. It was found that cadmium deposition was plate-like at lower cadmium concentrations, and at higher current densities. The presence of zinc in the electrolyte promoted nodular growth. Current efficiency remained high even at 50C in contrast to published information. Silver deposition morphology was relatively unaffected by changes in silver concentration, pH and current density. Current efficiency was reduced as temperature was increased.

Jan 1, 1989

By Skinner J, Brackenbury K

The AuPlus" Systems have been applied in the gold mining industry to achieve improved gold recoveries, faster leach kinetics and reduced cyanide consumptions. Calcium or hydrogen peroxide, collectively known as peroxygens, can be used. The choice depending on plant design and the nature of the ore. Laboratory test work and plant trials are included in this paper to illustrate the benefits of peroxygen usage in extractive gold metal- lurgy.

Jan 1, 1991

By Chang JF

This paper describes the advance in shaft sinking technique in terms of a vast complex of equipment in the last decade, and mainly recommends some ad- vanced technology and a vast complex of equipment, such as smooth blasting, la- ser guiding, shot-crete lining and rock- bolting, hanging bracket ring for drills, large-capacity wall grab, tipping device, storage bunker, and automobile haulage et.al., finaly, author in detail repre- sents some successful applications of advanced shaft sinking technique in some mines as an example.

Jan 1, 1987

By Doig ID, Phillips HR

As a prelude to studying the sorption desorption and permeability behaviour of coal cores in a triaxial stressing rig using sorb- able gases, the air permeability of typical cores was measured. Lump coal samples were obtained from three gas-troubled collieries in Queensland and New South Wales. These were cored in the laboratory and a simple laboratory permeameter employed which accepted 38 x 40 mm cores in a thick rubber sheath. Air pressure of 500 kPa was applied outside the sheath to provide suitable sealing between the rubber and the coal. Differential driving pressures up to 100 kPa were employed and the air flow measured by displacement of water columns in inverted graduated cylinders. Flow measurements accurate to + 2% could thereby be achieved. Coal lumps were cored both parallel and perpen- dicular to the bedding plane, and were observed prior to measurement for any notable features, in particular for the presence of fissures. Between samples an overall variation of from 100 milliDarcy was found in Appin, Westcliff and Leichhardt coals. Significant variation was observed both from section to section of a core and between regions of a

Jan 1, 1982

By Reid T. W

This paper describes the results of investigations into the relationship between specific gravity and chemical composition in the Cockatoo Island orebody, In the early investigations the samples were classified into groups according to porosity. This resulted in high, medium and low porosity groups, the latter being further subdivided into ore and waste. Whole number tonnage factors were assigned to each group. In the later investigations the reciprocals of bulk specific gravity and true specific gravity were ex- pressed as linear combinations of iron, silica and alumina using stepwise regression. The efficiency of the models as predictors was tested by dividing the data into two sets; one of which was used to calculate the regression equation and the other to test the efficiency of the equation as

Jan 1, 1976

This paper discusses why Argyle Diamonds adopted thickened tailings disposal in 1985 and how the system was developed over the next seven years. A wide ranging review of the thickened tailings disposal system and the tailings deposit it was producing was carried out during 1992 and 1993. The results of that review led to the abandonment of thickened tailings disposal at Argyle because of serious concerns about the stability of the resultant tailings deposit. The exposure to the risk of liquefaction and an assessment of the consequences if this happened to the thickened tailings deposit are shown. The criteria for selecting the new tailings disposal strategy are then described. The final section of the paper discusses the management strategies that have been put in place. These are designed to: ò reduce the risk posed by the thickened tailings deposit to an acceptable level; ò safely store tailings to the end of mine life; ò produce a land form that can be decommissioned to the satisfaction of Government regulatory bodies.

Jan 1, 1996

By W L. Lane, T R. Yanske

The Doe Run Company and its predecessors have been mining for over 130 years utilising the room and pillar mining method. This method has left approximately 20 per cent of the orebody in the remaining pillars. The original design and planning for the mines did not include extensive pillar extraction. This paper summarises the introduction of the pillar extraction and backfill techniques which have been implemented since 1991. These techniques include the use of low cost fill walls up to 20 m in height and the use of slinger trucks for topping off the fill. In conjunction with these accomplishments, much experience and confidence has been gained in the use of numerical modelling as a method of predicting pillar stability as the mining of pillars progresses. These advances have led to pillar extraction becoming a major portion of the overall production and have added to the mine life of Doe RunÆs six operating mines.

Jan 1, 1998

By Warren L. J

In the mineral processing industry solid-liquid separation within a thickener usually requires the addition of a synthetic flocculant to enhance the settling rate of fine particles. The characteristics of the resulting flocculated suspensions may vary considerably depending upon the physical and chemical conditions which prevail during the flocculation process. For example, parameters such as flocculant type, dosage and solution concentration, surface chemical characteristics of particles and the suspension agitation conditions can influence the degree to which the particles aggregate. Aggregated suspensions exhibit various structures, and range from those composed of small, dense aggregates to those containing large, voluminous aggregates. The size distribution and structural type of the aggregates which form within the feed-well of a thickener can have a dramatic effect upon overall thickener performance. Thickener performance cannot be optimized without optimization of the aggregate structure produced in the feed by synthetic flocculant addition. This has required the development of new techniques to quantify the nature of aggregated suspensions, details of which are presented in this paper.

Jan 1, 1989

By OÆBrien D, Priddle D

In order to avoid costly moisture penalties on coal shipments and to minimise rail freight costs, screen bowl centrifuges were selected and installed in the Mount Thorley Coal Preparation Plant for dewatering fine coal product. The Mount Thorley fine coal circuit consists of desliming the -0.5 mm (ww) fine coal in two stages of classifying cyclones prior to recovery by froth flotation. Provision has been made to bypass the flotation circuit with the classified flotation feed reporting directly to product and the centrifuge dewatering circuit has been designed to handle either flotation feed or flotation product. Major mechanical failures of the gearboxes and the ceramic tiling occurred early in the operation life of the machines which led to design changes being made to achieve satisfactory operation. This paper discusses the operating experience at Mount Thorley with respect to both mechanical and metallurgical performance of the screen bowl centrifuges since their installation in 1985.

Jan 1, 1989

Difficult ground conditions in the area planned for placement of vent rises to the surface at the Porgera Goldmine led engineers directing the project to chose blind shaft boring methods of shaft construction from the available alternatives. Zeni Drilling Pty Ltd was first contracted in 1988 to install a group of three closely-spaced, steel lined shafts. The success of these led to an order for a fourth hole in the same group followed by two more, less than a kilometre. away, under a separate contract in 1992. All of the shafts were completed on.schedule to within one day. The only significant difficulty arose during commencement of the last shaft when the strata collapsed trapping the drilling tools and jeopardising the stability of the surface collar pad. The situation was corrected by innovative lining techniques and the project went on to finish on schedule. This paper discusses the application of various technologies associated with the project including aspects of geotechnical input, drilling fluid chemistry, mining engineering and logistics.

Jan 1, 1993

By Carter A. C

The increasing need for alternative energy sources as well as the less clearly perceived but equally increasing demand for non-fuel minerals has resulted in extensive exploitation of near surface deposits. Many such deposits have depleted reserves and mining corporations are increasingly turning their attention to deposits, with thicker overburden, less competent materials, steeper dips and more complex structure. These deposits pose mine layout, geotechnical and equipment problems as well as the need for large outputs to achieve economies of scale. The paper describes the major problems and operational solutions for such deposits using continuous excavation and transport equipment.

Jan 1, 1980

By Forster I, Thilo A, Dean AK

A prototype production tool capable of operation in the hole sizes (

Jan 1, 1988