Search Documents

Adsorption isotherms, zeta potential and coagulation techniques have been used to exa- mine the mechanism of metal activation on SiO2 and ZnS surfaces. The importance of surface nucleation or precipitation of metal hydroxide coatings is'established and identified-by characteristic charge reversal patterns. The significance of surface coatings in sulphide and non-sulphide flotation is discussed.

Jan 1, 1973

In many mining operations, the truck and loader equipment represents the bulk of the invested capital and the majority of the mine operating cost. The profitability of these mines is therefore critically linked to the efficiency of the truck and loader operations. The various factors which affect the productivity of trucks and loaders are analysed by computer simulation, and the results presented in a form allowing assessment of the importance of each factor on overall productivity.

Jan 1, 1983

By Kruse JW, Kjar AR

Recently there has been increased recognition o'f the cost savings that can be achieved by the greater use of offsite preassembly for the construction of industrial plants. Preassembly is a method of construction which involves considerable offsite assembly of complete sections of an industrial plant in established fabrication shops. The preassemblies are transported to the plant site, often by large and oversize transport systems where they are set on prepared foundations, finished and interconnected to other sections of the plant as required. The concept of preassembly is not new, but widespread interest has been shown because site construction costs in all parts of the world have increased rapidly and often at a greater rate than in established fabrication areas. Particular interest has be focused on remote, isolated and inhospitable plant site locations. These areas require the import of skilled labour, the payment of high labour rate premiums and the development of infrastructure to support the workforce for the duration of the construction period.

Jan 1, 1983

One of the most difficult places to ventil ate in any mine is the working face area of an advancing mine heading. With an ever changing configuration, continual modification and extension to the ventilation system is necess- ary to maintain an adequate supply of fresh air and to control mixing and recirculation. Methane emissions and high dust levels as coal is broken and removed from the face area can produce unhealthy and dangerous conditions if ventilat- ion is not adequately monitored. An understanding of the air flow patterns which develop through use of different face ven- tilation systems can be reached by undertaking underground measurements or through observations using physical models. Tests undertaken by the author to determine the adequacy of different system-configurations are discussed together with approaches adopted by others working in the United States. Various new methods have been proposed for improving face ventilation beyond that sustained using conventional brattice curtain or tubing systems. The adequacy of some advances adopted by mining companies to improve ventilation while maintaining output efficiency is discussed.

Jan 1, 1983

ADDRESS BY THE PRESIDENT OF THE INSTITUTE (MR. C. H. MARTIN) IN PRESENTING THE CERTIF1CATE TO SIR GEORGE FISHER, C.M.G.Members of The Institute, distinguished guests, of which there are many, ladies and gentlemen, you are welcome.And might I add a special welcome to Lady Mawby and Lady Fisher and to Sir George's only son Peter, who with his wife, Betty and one of Sir George's three daughters, Helen, are present this evening, and also to Sir Maurice's son, Colin, and Colin's wife, Jay, also in our company.The family presence must surely be a great source of pleasure and satisfaction to all those so intimately concerned.It is hardly. necessary for me to state the sole and only rC'l.son for our presence here tonight, which is to conJer on Sir George Fisher and Sir Maurice Mawby Honorary Membership of The Australasian Institute of Mining and Metallurgy, and at the same time to acknowledge two people who have rendered great service to the mining industry albeit tinged with sadness to all of us in the knowledge that from now on their influence may diminish.

Jan 1, 1976

Zinc-bearing materials containing chlorides and fluorides of alkali metals, such as electric arc furnace dusts, Waelz oxides, galvanising ashes, brass foundry and converter fumes are marginally attractive, both technically and economically, for processing by the Imperial Smelting Process or in a conventional zinc sulphate electrolytic plant. The EZINEX« Process allows the recovery of high purity zinc in cathode form from these materials, together with regeneration of the leach liquor. The process is based on a new electrochemical system which depolarises the anode reaction with reduction of the cell voltage, compared with the traditional sulphate electrolysis method. The electrolyte, based on a chloroammino complex, permits the recovery of other valuable metals present in the zinc bearing materials such as lead, copper and silver. These are recovered as a metallic cement, consequently improving the economics of the process.

Jan 1, 1993

By Wright S

The feed to the Cockle Creek Imperial Smelting Furnace consists of mixed Pb/Zn con- centrates and lead sulphate-containing elec- trolytic zinc plant residues. Roasting was investigated as a means of desulphurizing the feed to less than 1%. Laboratory studies showed that two process streams were required in which concentrates containing 20% Pb were roasted separately from the leach residues. The residues along with fume from the roast- ing and a portion of concentrate were desul- phurized by means of the roast reduction reaction. Conditions were defined to give

Jan 1, 1986

The kinetics of desorption of nitrogen from molten iron were investigated using the electromagnetic levitation technique. The respective influences of gas flow rate and surface active element (S) were examined. A second order behaviour with respect to the nitrogen concentration in the melt prevailed at all experimental conditions. Sulphur had a marked inhibiting effect on the desorption rate. The experimental results on the rates of nitrogen desorption have been interpreted with the aid of a reaction mechanism consisting of a sequence of elementary steps.

Jan 1, 1991

The equity market is now very much within a global village environ- ment, with various exchanges acting as agencies for the big casino. In this predicament, mining companies, who provide the most extensive, but relevant risk assessment information, will be best placed for favoured treatment by potential international investors: But what risk assessment information in summary form can be provided to support a resource/reserve statement? Even more importantly, does "objective" data exist, whose trends will support a resource/reserve state- ment? A prime need of the informed mining investor is to determine whether or not the resource/reserve statement is believable? But more importantly will it be realised? While the implications within the text of the majority of reports on resource/reserves suggests that the estimates are conservative, the record indicates that very few estimates are. In fact, to date, reports claiming to be conservative in respect of the overall grade estimate at a specfic cutoff have not reflected the realised grade at the stated cutoff; it has been more common for the realised grade to be lower than implied by the resource/reserve statement. Further, it is not uncommon for penalty elements to be understated and these components are rarely incorporated within resource/reserve statements.

Jan 1, 1988

The Electricity Generating Authority of Thailand own and operate an opencut mine supplying coal to on-site power stations at Mae Moh, 600 km North of Bangkok. The mine is being expanded from an annual production of 1.5 million tonnes per year in 1982 to over 9.5 million tonnes per year by 1991. The mine will be amongst the largest open pit operations in the world. It is technically difficult to operate and plan due to complex geology, weak strata and surface constraints including reservoirs, forests and traditional villages. This paper presents a case study of mine planning for the above project including associated collection and processing of geological and geotechnical information. The existing operation is described, as well as the strategy adopted for the mine at expanded production. The planning covers various phases of mine planning including a Conceptual Study, a Definitive Study and detailed short term planning. Each stage incorporated new information and reflected a higher level of confidence in the data and resulting plan. Sophisticated computer techniques were required including geological modelling, calculation of volumes, geotechnical analysis, scheduling and costing. The planning was undertaken on site by a team of Australian and Thai Engineers as part of the Thailand-Australia Lignite Mines Development Project which is a four year programme of assistance funded by the Australian Government.

Jan 1, 1986

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

Mining is a necessary part of our modern lifestyle. However, mining can cause damage and pollution of the environment and therefore we must manage our resources wisely accounting for the physical, biological and social environments. Contrary to the view of some people not conversant with the facts mining has in many cases improved the environment. This paper described how two sand dune systems that were unstable prior to mining have been stabilised by revegetation after mining.

Jan 1, 1987

By Carter NB

A statistically-designed experimental program has been used to study compositional and processing variables which influence the development of strength and reducibility of iron ore pellets. The effects of chemical composition and processing variables were investigated by indurating laboratory-made green pellets, of known composition, under approximately isothermal conditions in a pot- grate simulator. Some findings from a six- variable study are summarized in the form of contour diagrams and emphasize the importance of interactions between the variables. Production of strong, highly reducible pellets is possible over a considerable range of combinations of temperature and firing time. Abrasion index (AI) and cold compression strength (CCS) improve as both these variables increase, but reducibility (R) declines, so a compromise is required. When the lime level is too low to form enough slag for bonding, the AI and CCS may be inadequate. Larger additions of lime tend to improve AI and CCS, with only slight effects on R. Finer grinding of the balling feed (i.e. higher Blaine index) tends to improve Al and CCS without

Jan 1, 1980

The Prospect to Pipehead Tunnel is a component of the Sydney Water Board's multi-million dollar Drinking Water Quality Program to improve the quality of Sydney's potable water supply to meet revised national health guidelines. The tunnel project involves the construction of seven kilometres of 3.9 metre diameter machine bored tunnel which is to be lined with a three-metre diameter steel liner. The paper describes the fully integrated planning and design approach and management technique used to enable this major project to proceed to meet the requirements of a tight construction program.

Jan 1, 1993

By Otuonye F

An outburst is the spontaneous ejection of pulverized coal and gas from the working face in an underground mine. It is caused by overstressing the rock, due predominantly to the influence of geological structures on in situ stresses, stress concentration from the excavation and overburden load on mine openings, and large volumes of gas sorbed in the rock. The spontaneous release of high pressure gas creates intense shock waves which may cause damage to the mine ven- tilation system and the pulverized rock/coal ejected may cause injury or death to miners. The gases emitted pollute the mine air and may also result in death to miners.

Jan 1, 1988

The Transportable Moisture Limits, as ,measured by the procedures laid down in The IMCO Code of Safe Practices for Bulk Cargoes, determine the target moisture contents for the concentrates produced at the West Coast Mines of Electrolytic Zinc Company of Australasia Limited at Rosebery. Filtration of these concentrates gives moisture contents considered to be low in comparison with those achieved for similar sulphide concentrates, but which are very close to these Transportable Moisture Limits. The filtering techniques used are outlined and the problems associated with-maintaining concentrate moistures below the required limits, together with the methods used to solve these problems are discussed.

Jan 1, 1978

By Burks WG, Hughes FE, Muceniekas E, Whitcher IG

The area containing the iron field, recognised by the writers, is part of an uplifted, portion of the 'Western Australian Plateau,' ranging in elevation from about 1,000 feet to about 3000 feet above sea level. The local rock succession is flat-lying or moderately-folded and belongs to the Nullagine Series of Upper (2). Precambrian age. This series forms the Hamersley Rangeland vast portions of the...

Jan 1, 1964

By Avraamides J, Ritchie I. M

Gold Tellurides are important sources of gold at Kalgoorlie, Western Australia, Cripple Creek, Colorado and Vatukoula, Fiji. Unlike free gold, the tellurides of gold are rather refractory and the usual treatment practice has been to oxidize the tellurides, either chemically or by roasting prior to cyanidation of the liberated free gold. There is a large measure of disagree- ment as to the actual cause of the refractory nature of gold tellurides. In order to investigate the leaching chemistry of gold telluride, a study was undertaken on the thermodynamics and kinetics of its dissolution using electrochemical methods. From this study suitable direct leaching condi- tions are suggested. In acidic chloride solutions gold telluride can be leached using iron(III) as the oxidant. At lower acid concentrations the reaction is controlled by the formation of a passivating film of H2TeO3. In alkaline solutions containing cyanide the rate of gold telluride dissolution increases with increasing pH and strength of oxidant. However, this can result in excessive consumption of cyanide in the presence of stronger oxidants.

Jan 1, 1991

By Okura T, Hino J

Coal utilization for copper flash smelting in Japan was initiated due to the sudden upheaval in the price of oil in the last ten years. A major portion of the heavy fuel oil has already been replaced by coal resulting in a corresponding decrease in energy costs. In addition to energy cost savings, an interesting metallurgical phenomenon was observed in flash smelting operations. Unlike oil combustion, coal is not burned completely in the shaft. A considerable fraction of coal particles remain on the surface of slag and are burned at the settler. Chemical investigation has shown that oxygen potentials at the settler have consequently decreased, bringing the slag and matte phases into reducing conditions, thus oxidation and reduction can coexist in one flash smelting unit. As a result, a decrease in magnetite and copper contents in the slag, elimination of furnace hearth build-up and dissolution of intermediate layer between matte and slag have been observed. In general, these led to improvements of furnace operations. However, thermodynamic investigations have shown that some minor elements such as As, Sb, Bi and Pb concentrate from slag to matte. Results evaluated on the basis of thermodynamic data relatively agree with practical observa- tions. Consequently, for coal utilization in flash smelting operations it will be necessary to control oxygen potentials from the stand- points of copper loss in slag and minor element Distributions.

Jan 1, 1987

The present geology of the northwest quadrant of the Circum-Pacific is the product of the interact-ions between plates or paleo-plates which have oc-curred since the earliest part of the earth's hist-ory. Almost every possible geologic structures are observable there; stable continents, collision belts, and subduction arcs as well as extensional basins. This suggests that almost all the possible tectonic processes occurred through geologic time and the present overall structure of the Quadrant is no more than a time section of the long lasting tectonic history which the region experienced.

Jan 1, 1990