Search Documents

By Aylmore M. G

Samples have been taken from a two-stage industrial gold roaster treating a pyrite/pyrrhotite/arsenopyrite concentrate, in order to describe the mineralogy, composition and surface area of the calcines. Sulphides oxidised to produce a porous magnetite in the first stage and a porous hematite in the second; pyrite predominantly roasted via a pyrrhotite intermediate. Sulphur was eliminated in both the first and second stages whereas arsenic was eliminated in the first but retained in the second, partly as rims on hematite particles. The finer sized particles from the cyclones and electrostatic precipitator, while having the greatest surface area, were the most refractory with respect to gold solubilisation, probably as a result of incomplete decomposition (through short-circuiting) in the first stage, and through a combination of factors such as overheating and entrapment of sub-microscopic gold in the second stage.

Jan 1, 1992

A continuous casting machine, of the Concast curved mould design casting billets in four strands, was commissioned at the Newcastle Works of The Broken Hill Proprietary Co. Ltd., in November, 1967. Quality assessment of early casts from this plant indicated that steel cleanliness was sometimes inferior to that of equival- ent ingot cast steel. Extensive trials to develop a modified deoxidation technique were not successful in improving clean- liness to the desired level. A "contra-flow" gas shroud, to cover the steel stream between the tundish and the mould, was developed, and proved successful in achieving the required levels of product cleanliness. The inclusion content of six grades of steel ranging in carbon content from 0.10 to 0.70 per cent is examined, and an attempt is made to explain theoretically some of the results obtained.

Jan 1, 1972

IT is most remarkable and valuable property of mediurn and high carbon steels that they should be so susceptible to heat treatment, the wide range of variability in tenacity, ductility, etc, due to the normal influence of the carbon in the untreated material being enormously inereased thereby.The physical properties of steel and other metals are much more closely related to their structure than to their ultimate analysis.For instance, we may by chemical analysis determine the carbon content of a steel to be 0.5% ; but this information alone is insufficient to enable us to say what are the physical properties of the metal.Such a steel may possess 11 tensile strength of anything from 35 tons per sq. in., with much ductility, up to 80 tons per sq. in., with practically no ductility, according to its heat treatment. A microscopie examination, on the other hand, would show the structural composition of the steel, from which its physical properties could be approximately deduced. From this it will readily be understood that the microscope has played an important part in the development of modern rnetallurgy, and to-day it is in daily use for the examination of metals and alloys in the laboratories of most works dealing with the rnanufaeture and working of metals.THE IRON-IRON CARBIDE EQUILIBRIUMTo understand fully the mode of occurrcnce of the different constituents of a knowledge of the Iron-Iron Carbide equilibrium diagram (Fig. I) is essential to heat-treat steel successfully and to interpret microstructures correctly such a knowledge isabsolutely indispensable.A portion of the Iron-Iron Carbide Diagram, dealing with steels below 1000 and containing up to 1 carbon is given below.It should be noted that the diagram deals entirely with pure carbon steels, and does not indicate the influence of the usual so-ealled "impurities" present in all commereial carbon steels...

Jan 1, 1926

By A Hewitt

Portland cement is the chief binding ingredient in mine backfill. In the presence of water, the chemical compounds within portland cement hydrate causing hardening and strength gain. During hydration, heat is generated. In certain cases, hydration heat may be produced significantly faster than it can be dissipated, which can create high temperatures in the underground environment. This paper presents the results of a series of investigations aimed at quantifying the heat generated by cemented backfill during hydration. Scaled stope models, instrumented with thermistors, were used in the investigation. Heat transfer to the hanging wall, orebody, footwall and cross-cut and production drifts was assessed during the backfill curing process and relationships between cement content, cure time, and heat generation were developed. The results of this work will assist mine operators in predicting the heat generated by cemented backfill and provide the necessary information to implement effective engineering control of heat in the underground environment.

Jan 1, 2005

The emergence of a new range of database communication standards and software has provided the impetus for the development of a new approach to exploration and mining data management. The acQuire software produced by acQuire Software Pty

Jan 1, 1998

By M Tessier, M Pahkala, L Sletmoe

The Red Lake mine is one of the richest gold mines in the world. The primary mining methods are overhand and underhand cut and fill. Starting in 2003, Goldcorp initiated an expansion program at the mine. The expansion includes a new 6.55 m diameter hoisting shaft currently under construction. The shaft will be driven to a length of over 2180 m. The shaft will be used as a primary ventilation intake to the mine. In addition to the new hoisting shaft, a return air raise is being driven approximately 1690 m from surface. This raise will be a parallel return to the existing mine infrastructure. This paper describes the ventilation and climatic analyses performed in support of the expansion project. The study included a full mine ventilation survey, in situ rock mass measurements, analysing options related to mine layout, airway sizing calculations, air heating options, and climatic simulations. Specifications were prepared for an air heating system and main and booster fans. Analyses were also performed related to heat in the stoping areas namely caused by auxiliary fans and backfill with high cement content.

Jan 1, 2005

Kidston Gold Mines Limited (70 per cent Placer Pacific and 30 per cent Public Shareholders) has been mining the Wises Hill Pit since late-1984. The Wises Hill Deposit is a large low grade gold deposit and as such is highly sensitive to economic parameters. The uniformity of the orebody has allowed a bulk mining method to be used, with minimal dilution. Total reserves defined to-date are 64 160 OOOT at a grade of 1.60 g/t gold. Mineable reserves remaining as of January 1992 are 36 357 OOOT at a grade of 1.28 g/t gold.Mining investigations to reduce the impact of lower gold prices, the effect of decreasing headgrade and increasing mining costs have focused on wall steepening.

Jan 1, 1992

Small mines exist because of a restricted deposit or a small market. With the right management at the present time the small mine can have lower total costs than larger mines. Charbon is an example of a small mine with a restricted deposit and a specialised product. The development which incorporates a unique rail loading facility and flexible coal preparation plant was achieved with a modest capital outlay and in record time. To remain competitive in future with large scale mines who seek increased production the small mine must achieve increased productivity through automation, higher speed equipment and a multiskilled workforce. Deregulation of the industry, scrapping the Coal Industry Tribunal and the Joint Coal Board would benefit small mines greatly. Management of a small operation also requires multiskills which need to be supported by outside help in the form of consultants and temporary staff. In the 21st century small mines will continue to provide a service to the market.

Jan 1, 1988

By Leigh J. H

A history is given of the dust control techniques developed and applied by the mining companies at Broken Hill. A history of the regeneration works undertaken since 1936 is out- lined. Particular emphasis is placed on the stabilization of mine residue dumps which are located throughout a belt of mining leases in the middle of the city and which began in 1937. The establishment of vegetation for dust control techniques is discussed in detail and a case study is given of the successful revegetation of the sides of a 650 metre long, 350 metre wide and 35 metre high residue dump.

Jan 1, 1976

By Cutler JL

At the present stage of the Rundle oil shale project planning, with depressed world oil prices, early development of the resource is unlikely. However, this postponement is being used to carry out technical studies required to evaluate alternative rehabilitation strategies and establish a sound environmental planning basis. Major technical data from the following studies are reviewed: Resource: - mine planning; material characterisation; retorting; geology; Environmental: - meteorology; surface water management; laboratory and field leachates; revegetation; waste characterisation; hydraulic and chemical modelling; dust suppression; plant/water interactions; and impact evaluation. These studies have shown that topsoil replacement, seeding mixtures, fertilizer application rates, subsoil quality and handling, waste pile slope and most importantly soil water storage are key factors in successful rehabilitation.

Jan 1, 1987

IA )W cli',hla cn1cnt fault 7011(-s 0 11Cn cOrnprise a nrc,II of inrcIIinkc(I faults, cvtcnqonal shear and In]rck cxtcnsir>nal vein- fractures. Hydrothermal mineralisation localised around such structures testifies to their importance as conduits for fluid flow. Mesh structures are most commonly developed in situations approximating bulk pure shear but predominantly simple shear meshes also occur. They appear to develop through the infiltration of pressurised fluids into a heterogeneous rock mass with varying material properties. In some circumstances, mesh formation appears to be a precursor to the development of major throughgoing faults. Mesh formation generally involves hydrofracturing (Pf> a3, at least locally) and the condition Pf - 63 to be maintained for the mesh to remain a high permeability conduit, requiring fluid overpressuring at other than shallow depths in extensional-transtensional regimes. The volumetric character of earthquake swarm activity appears to result from the passage of hydrothermal fluids through mesh structures, representing a form of distributed fault-valve action along suprahydrostatic hydraulic gradients arising from magmatic intrusion, compaction overpressuring, metamorphic dewatering, etc.

Jan 1, 1995

By M Grinceri

The New MetroRail City Project was completed in 2007 in Perth, Western Australia. The project included construction of two underground stations, twin bored rail tunnels of 1.4 km combined length and cut-and- cover tunnels and dive structures of about 1 km total length. It is the first major underground construction project within the Perth central business district (CBD). This paper provides an introduction to the project and describes the geology and hydrogeology of the area. Ground conditions varied significantly along the alignment from soft estuarine muds in an area of reclamation to very dense cemented sands and very stiff to hard clays. Deep foundations for the project extend down into the bedrock below the CBD, a Tertiary siltstone/sandstone. Key geotechnical hazards encountered during the project are discussed. The building protection methodology on the project is described, including damage assessment, condition surveys, monitoring and protection of key structures.

Jan 1, 2008

By Whiten WJ

A method that allows data to be mass balanced and screen models to be fitted in a single step is described. The inclusion of several variables to describe the feed data in the fitting procedure allows a mass balance to be conducted at the same time as the fitting of the screen model. Analysis of Groote Eylandt Mining Company screening data has demonstrated that this method is ideally suited to applications where complete stream data are not available. Also, certain random fluctuations in screen model parameters arising from the fitting of consecutive mass balances and screening models are significantly reduced. A cubic spline function with fixed knot positions corresponding to particle sizes and variable (fitted) cumulative percent passing values is used to describe the feed size distribution. When the spline function is interpolated at the experimental feed particle sizes a fitted feed size distribution is obtained. This feed size distribution is then used as input to the screen model calculations from which product size distributions are generated. Since both feed and product size distribution data are used to minimise the residual errors between the observed and fitted stream size distributions, a mass balance is Conducted simultaneously with the screen model parameter fitting.

Jan 1, 1984

By Richardson G. W, Yap L. C

Friction rock stabilisers (FRS) are steel-based, thin-walled tubular ground reinforcement widely used in underground mines in Western Australia. Following installation these stabilisers are subject to corrosion which may reduce the load carrying capacity and lead to unexpected ground falls. Although corrosion has been recognised as a common occurrence, particularly under aggressive mine water and mineral conditions present in underground mines, the knowledge of the effects of corrosion on the mechanical behaviour of FRS is limited. The Department of Minerals and Energy of Western Australia has conducted a laboratory based program of studies to investigate the effect of corrosion on the mechanical properties of FRS. The studies have focused on the effect of corrosion on tensile strength of FRS and frictional resistance along the interface between FRS and the drillhole wall. The results indicate that under certain conditions corrosion damage can significantly reduce the effectiveness of FRS.

Jan 1, 1996

By Matsuhisa Y, Sakurai W, Shimazaki H, Peiming H, Fukahori Y

Oxygen and carbon isotope mapping of hydrothermally altered wall rocks was applied to the blind ore prospecting of skam Pb-Zn deposits in the Kamioka mining district, central Japan, where the wall rocks consist of heterogeneous rock units. The results (8180sMow of -1.1 to +17.3%o and 613CPDB of -5.0 to +4.8%o for limestones, and 8180SMOW of -0.8 to +12.5%c for silicate rocks) show isotope zonations of the wall rocks with depletions in heavy isotopes (180 and 13C) toward the center of mineralization. The isotope zonations likely formed by interaction of migrating thermal waters with the wall rocks during the mineralization. The heavy-isotope depleted zone, which indicates higher temperature or higher water-to- rock ratio of the system, occurs in the footwall of a fault, indicating that the fault played the role of main conduit of the ore-forming fluids. A heavy-isotope depleted zone was also found in an area, where significant mineralization had yet to be identified. Recent drilling in this area has intercepted a zone with a grade of 16.0% Zn, 0.8% Pb, and 35g Ag per metric tonne at a depth of about 360m.

Jan 1, 1995

By Carlson BL, Overton DD

This paper compares the designs of heap leach facilities for four precious metal mining projects in the southwestern United States. These four proposed projects are of small-to medium-size relative to other operating mines in the United States, and are either permitted or in the final stages of permitting. The differences and similarities in the heap leach facility designs are compared with respect to site conditions, operating conditions and regulatory requirements. This comparison provides a summary of the state-of-practice for heap leach facility design in the southwestern United States and identifies current issues in project development and process material containment.

Jan 1, 1997

It is now 32 years since Walsh's classic publication (1) heralded the beginning of atomic absorption spectrophotometry (AA) as we know it today. During this time, AA has developed into the most widely used analytical techniques for the determination of the metallic elements. The years have seen progressive changes in instrumentation so that today it is a highly sophisticated technique. One area of development in AA that is experiencing renewed attention is in the area of electrothermal excitation. In this technique a flame is not used by the analyte solution is atomised by an electrically heated graphite furnace. For a large number of elements the graphite furnace atomic absorption spectrophotometer (GFAA) is considerably more sensitive than flame work. It is common to be able to detect concentrations one hundred times smaller than those possible by flame. Today's geochemists are finding that they can gain valuable information out of very low limits of detection. Electrothermal atomic absorption spectrophotometry (or GFAA) allows for low limits of detection and can be seen to be a valuable aid to geochemical prospecting Analysis.

Jan 1, 1987

By McKew M, OÆRegan

Rapid access longwall mining' or 'longwail punch mining' is a proposed extraction method whereby longwall gate roads are driven into a seam directly from an opencut highwall. The longwall panel thus formed is retreated back to within 40 m of the highwall providing an extremely simple, reliable and therefore highly productive longwall mining system. The concept is of particular benefit for the recovery of isolated pockets of coal (adjacent to a highwall) not easily accessible from a conventional underground mine. As panel gate roads are driven directly from the open strip, minimal delays are incurred between the end of open cut and start of underground production, allowing the method to bridge the gap between open cut mining and a total underground commitment. The study was specific to the Bowen Basin, and given the likely conditions, no significant operational or geotechnical hinderances to the concept could be identified. It was therefore concluded that longwall punch mining would not expose the operator to any additional risks above that normally associated with the introduction of longwall mining. Thus, longwall punch mining is an attractive option, both operationally and financially, for open cut mines reaching their maximum economic Death.

Jan 1, 1988

By Eggins SM, Crawford AJ, Maillet P

The Fiji Islands are remnants of a once continuous Solomon-Vanuatu-Fiji-Tonga volcanic arc (the Vitiaz arc), located at the boundary between the Indian-Australian and Pacific plates. They record a history of (i) arc volcanism the late Eocene to late Miocene, (ii) an extensive magmatic response to arc rifting (5.5-3.OMa) during which volcanism was dominated by shoshonitic to tholeiitic basalts, and as rifting continued, (iii) a transition from arc to intraplate volcanism. The Hunter Ridge-Hunter Fracture Zone separates the inactive South Fiji Basin from the actively spreading North Fiji Basin, and has been considered to be a transform zone, almost parallel to the motion vector of the Australian plate. However rocks dredged during the 1993 `Alize' cruise, from along the northern part of the Hunter Ridge are typical arc tholeiites, and therefore demand that subduction has occurred beneath the Hunter Ridge sometime during the last û 5Ma.

Jan 1, 1995

This paper reviews the geochemistry of weathered nickeliferous sulphidic and lateritic profiles, the supergene behaviour of nickel and ore-associated elements, and their implications for exploration in an attempt to distinguish between barren and mineralised nickeliferous profiles. Nickel is an abundant accessory element in ultramafic rocks with background concentrations in some units up to 0.25 weight per cent. Ore-grades in fresh rock are mostly associated with massive and disseminated sulphide zones within magnesium-rich layered ultramafic sequences. In lateritic weathered terrain, nickel is also concentrated in the regolith profile. This process not only upgrades nickel in the gossanous weathered product of sulphidic deposits, but for sub-economic sulphide zones and some ultramafic rocks, is sufficient to result in a supergene resource. Ore-grade accumulations of nickel in regolith after sulphide-poor ultramafic rocks are referred to as lateritic deposits. Nickel sulphide zones and their ferruginous weathering products are collectively referred to as sulphidic deposits and are the major source of nickel in Western Australia. Mineral exploration in the Yilgam Block is hampered by deep lateritic weathered profiles (eg Butt and Sheppy, 1975; Smith, 1977; 1982). During the nickel boom of 1967 - 1972, most discoveries resulted from the location of outcropping nickeliferous gossan and ironstone. Exposed ultramafic terrain with nickel sulphide potential were explored intensively, mostly by gossan and soil sampling. However, up to 85 per cent of the area of the Yilgarn Block is buried by transported regolith. In these covered areas, barren and mineralised rock responses at the surface are similar and soil sampling produced unreliable results due to many false anomalies. A statistical, multi-element approach to regional geochemical exploration has evolved. Potential trace element indicators investigated, include Co, Cr, Cu, Ir, Mn, Pb, Pd, Pt, Sc, Se, and Zn. In recent years, trace element ratios have also been tested with varying degrees of Success.

Jan 1, 1996