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By B R. Olsson, N Marinopoulos

To establish the design and the capacity of the Stanwell Magnesium Plant, Australian Magnesium Corporation Ltd (AMC) with Fluor Australia has modelled the operation of the magnesium plant using ARENA Simulation Modelling. The reliability model has been used to evaluate: surge capacities required between different sections of the plant; critical equipment requiring standby capacity; the number of trains required for different sections of the plant; and potential capital cost reduction options. The reliability model was established using the detailed Process Flow Diagrams, reliability information from literature and maintenance, operation and start-up experience from the Demonstration Plant. The model was run with different plant configurations to assist AMC in determining the most effective configuration to provide the production capacity at the lowest capital cost. The model was not only able to confirm the plant capacity to the independent technical expert but was able to minimise quantitative risk by minimising the quantities of hazardous materials on site. Fluor Australia provided the ARENA simulation expertise and has used this software for optimising new plant design and to establish improvements in operating plants. Reliability modelling is a normal feature of chemical plant design but is rarely used in the resource industry. The experience gained by AMC in the modelling system has indicated that metallurgical plant design can be improved by the application of reliability modelling.

Jan 1, 2002

By Nilsson C

Man has always been and will always be part of his environment, in ,a good, bad or indifferent manner. Until quite recently, this environment has been the atmospheric boundary layer above the land masses, and to a limited extent the air-sea interface of the oceans. Since the days when he lived in caves, he has built up a wealth of observations on these two environments,-with ever-increasing scientific precision which unfortunately until quite recently was completely insufficient for modern capabilities of data analysis. Consequently, in a sense, he has left in his wake thousands of years of missed, opportunities for making exact observations and increasing his understanding. The data of the past are lost and he has to be satisfied with what he can assemble from now on when his environ- ment, largely as a result of his actions, is exhibiting more and more rapid variations in time; in other words, time series of observations of phenomena are required, the length of which is critical for most purposes of analysis.

Jan 1, 1970

By R H. Eric

Surface wave formation induced by a high-strength submerged jet in a bottom blown metallurgical vessels has been studied experimentally by using one-seventh water model of CLU (Creusot-Loire Uddeholm) reactor with two different tuyere configurations. Experimental results have been discussed in terms of the wave period, wave frequency and wave amplitude with respect to air injection rate and tuyere configuration at a 0.23 m bath height. The results from high speed photography observations displayed the formation of rotating surface waves which circulates within the water model. It was found that the frequency and the amplitude increased with gas injection rate. The wave period for off-centre nozzle orientation was found to be lower than those of the centre configuration. The experimental results also showed that the frequency of a rotating wave increases when the tuyere orientation becomes off-centred . The predicted amplitudes were in very good agreement with the experimental values over a range of gas flowrates between 0.00599m 3/s to 0.01081 m 3/s.

Jan 1, 2000

Better quality at lower cost is today's formula for remaining competitive in a world market. For an integrated steel company, high quality low cost steel production must originate before the blast furnace. In 1979, when U.S. Steel initiated a Quality Management Program throughout its steelmaking operations, efforts began at the coal, ore and flux mines. The objective was to improve the quality and reduce the variability of the critical parameters for steelmaking raw materials, to get the blast furnaces, and subsequently the melt shops, under optimum control. The general details of U.S. Steel's Quality Management Program are discussed and how it was used to promote the desired improvements in steelmaking raw materials. Some of the outstanding results obtained by the cooperative efforts between the mines and the steel plants are reported. The lessons learned by U.S. Steel were through upgrading existing operations and facilities. These principles should now be applied to new projects and the benefits of good quality management should commence from the time new projects are Commissioned.

Jan 1, 1986

One of the strategies introduced within Pasminco Mining to survive low commodity prices is to formally implement a `Quality Education System'. The net result has been a consistent approach to quality within and across mine sites. This `quality system' has been adopted in the technical computing environment and the immediate benefits have been: ò A clearer understanding of the systems, processes and relationships that involve technical computing. ò A re-focussing on customer (user) requirements. ò Inclusion of managers as customers with their own requirements of performance and quality, in addition to access to Executive Information. ò New ways to measure the `performance' of a technical computing environment which includes using maintenance costs. Observations are that there is an overlap between `traditional' information technology (IT) methodologies and quality systems being put in place in the broader workplace. This overlap is most apparent in the area of analysing customer requirements. In the IT environment customers are viewed as users, and their requirements determined by undertaking a requirements analysis. A data flow diagram traditionally used in the IT environment and not as a tool in quality systems, has been used in a novel manner to help identify the customers of the technical computing department. It has also been useful in illustrating the work processes and relationships between the entities in this diagram and in directing the future initiatives needed to fulfil the customers' changing requirements.

Jan 1, 1995

By Manzoori AR

From a detailed combustion testing program and earlier experience with Leigh Creek coal, the Electricity Trust of South Australia (ETSA) gained a wide insight into the use of low rank coal fired boiler plant. This work is fundamental for the selection of boiler design parameters and other details which in turn determine the correct coal deposit selection for future power station development. In addition it gives boiler designers a good indication of the measures required to give reliable plant operation. Extrapolation from experience with existing plant, the designers main source of information, was not considered appropriate because of the lack of experience with similar coals. Brown coal beneficiation is also being assessed by ETSA in an attempt to improve the coal quality by the pretreatment of the raw coal prior to combustion in future coal.fired boilers. ETSA is also involved in the development of circulating fluid bed and gasification processes to determine whether these alternative processes are a more viable method of utilising the South Australian coals than pulverised fuel firing.

Jan 1, 1987

By Porter I, Singh RN

An advanced elasto-plastic finite element model adopting a modified Von Mises yielding criterion was used to simulate progressive failure of the rock strata surrounding a room and pillar mine structure. The model conformed to the strain-softening behaviour of rock and accounted for post-failure residual strength. The simulation was achieved in such a way that material values were updated after each FE run, according to the stress criterion until the solution reached the final equilibrium steady state of the mine structure. The suggested structural stability analysis approach accounted for the main features of the structure degradations produced during loading through changes in rock material stiffness and subsequent evolution of stresses. Comprehensive parametric analysis was performed and the inevitable effect of interaction of the roof, pillar and floor on the overall mine stability limit was investigated. The numerical results clearly showed that linear models could not realistically represent the true behaviour of the mine structure. The results obtained are in good agreement with that predicted in the field.

Jan 1, 1992

By Liu Z. C

Evans' theory for chisel shaped picks is well known in the field of rock cutting technology. It has been widely accepted as a good mathematical description of how coal and other rocks break under the action of a simple wedge or chisel. Subsequently, Evans proposed a corresponding theory for pointed shaped picks. Theory along with experimental evidence from the laboratory has consistently shown that chisel picks are more efficient than pointed picks. However despite such evidence, pointed picks continue to be the preferred shape in most practical cutting applications. Evans' theory for pointed picks was developed in an attempt to shed light on this apparent incongruity. The theory although predicting forces of the right order was found to be deficient in several respects. This paper examines Evans' theory for pointed picks and proposes changes to it, which brings the theory much more into line with measured data. The issue of the relative efficiencies of chisel and pointed shaped picks is also examined on a theoretical basis and the apparent incongruity is Resolved.

Jan 1, 1995

By S M. Mousavi

The issue of estimating evaporation in soils is central to the design of engineered soil caps for mine waste and landfill applications. In general, because evaporation from the soil is difficult to measure in the field, laboratory experiments and empirical methods have been used. Much of the earlier work has been conducted in soil science, although in recent years, geotechnical and geoenvironmental engineers have given great deal effort to this work. The result of this increased interest is the development of numerical models, such as UNSATH and SoilCover for estimating evaporation. In this study laboratory-measured evaporation from soil columns was compared with evaporation predicted using the computer program SoilCover, and the analytical method proposed by Gardner and Hillel. Good agreement among the results was observed. Also the sensitivity of the predicted evaporation to soil hydraulic and geotechnical properties, such as saturated hydraulic conductivity and coefficient of volume change was discussed and the practical implication of the sensitivity were highlighted. The work has application in the design and construction of soil covers over sulfide-bearing mine waste and landfills.

Jan 1, 2003

From the viewpoint of mechanical efficiency, charges should be fully coupled and, upon detonation, should just fail to break the rock in compression. But because mining thrives on its cost-effectiveness rather than its mechan- ical efficiency, the explosive which generates maximum energy per $ should generally be used, even though the mechanical efficiency of this explosive's detonation products may be sub- optimum. Wherever possible, each charge should have a length:diameter ratio of about 20 or more and should shoot to a concavely biplanar free face that is both parallel and reasonably close to the blasthole. Success in obtaining parallel effective faces often demands the drilling of angled blastholes and, hence, will require intensified research and development efforts by drilling manufacturers, especially where hard strong rocks are encountered. Blastholes should be drilled on equilateral triangular grids and fired in a Vl or shallower V-type sequence using inter-row delays which ensure that good pro- gressive relief of burden is achieved. The conventional method of calculating Se/Be values (on the basis of planar effective faces) is often invalid.

Jan 1, 1986

By S S. Kanchibotla, I Brunton

Most blast fragmentation models assume the rock mass properties, explosive properties and blast design variables to be constants and uniformly distributed within a blast. However, in reality all these input variables vary within a blast resulting in variation in the resulting fragmentation size distribution. A stochastic modelling approach is introduced in this paper to quantify this variation. This technique takes the input variables as statistical distributions rather than constants and through several thousand iterations, generates a statistical representation of the expected fragmentation resulting from a production blast. A case study of three production blasts from a large open pit mine are presented and the modelled fragmentation æenvelopeÆ shows good agreement with the fragmentation æenvelopeÆ estimated from Split image analysis. The various blast-related parameters influence different parts of the fragmentation distribution, eg rock strength and explosive velocity of detonation have most impact on the fines. The technique is used to identify the parameters that have the greatest influence on various size fractions. Such an analysis will be useful to direct resources to efficiently minimise the variation.

Jan 1, 2001

By Ohga K, Isobe T

Basing upon many and long practical experiences of gas drainage from coal seam and results investigations on the gas flow through in si-tu coal seam using tracer gases,it became clear that solid coal itself is hardly gas permeable or has extremely low gas permeability. Almost all of gas flows from a coal seam into boreholes through fracture net- works intersecting with them.Primary and secondary fractures in coal seams differ in their size and continuity from place to place according to differences of the coal strength and the stress conditions. A lot of gas can be drained through boreholes which intersect with many and/or wide fractures. A mathematical model for gas flow from a coal seam to a borehole through a discoidal fracture is proposed. From the numerical analyses,the apparent radius of the discoidal fracture in this model is shown to be a good indication of the gas drainage ratio. In addition to this,an atempt to make fractures around a borehole using high velocity water jet(ca.lmm dia.,300-700atm., 100-200 1/min.) is introduced.

Jan 1, 1982

The Highlands Region of Papua New Guinea has 3 major national highways. The locations of these national highways are shown in Figure 1. The Highlands Highway begins at Lae City on the coast and passes through the Highlands towns of Goroka, Kundiawa and Mt Hagen. It terminates at Togoba approximately 10km out of Mt Hagen town. The Enga Highway begins at Togoba and passes through the towns of Wapenamanda, Wabag and Laiagam. It terminates at the giant Porgera Gold Mine. The Southern Highlands Highway also begins at Togoba and passes through the major towns of Mendi, and Tari. It terminates at Koroba station, near the Hides Gas Field. Two separate Feeder roads intersecting the main highway service both the Kutubu Oil Project and the Hides Gas Field. These national Highways play a very important role in the development of Papua New Guinea. Goods and services are delivered to the bulk of the population of the Highlands Region using these highways. Heavy machinery and equipment for the mining and petroleum projects of Porgera, Hides and Kutubu are transported using these roads.

Jan 1, 1997

The equipment and general smelter layout for the Mount Isa Copper Smelter were designed by engineers associated with the American Smelting and Refining Company and by Mount Isa staff engineers. The final notice of site was dictated by the need for 'building the smelter near the existing Mount Isa power house to enable full use to be made of the steam from the waste heat boilers. Although much excavation work was necessary before concrete foundations could be poured, the location lends itself to further expansion should it become necessary. The plant is designed and constructed to involve straight line smelting operations which include the following major steps in the overall scheme.1. Charge make-up.2. Roasthig.3. Reverberatory smelting.4. Converting.5. Refining.6. Casting.CHARGE MAKE-UPA system of proportioning bins is provided for preparing the feed mixture for the roasters, Sulphide concentrate containing 24% copper wiil be delivered by belt conveyor from the filter plant to the smelter storage patio. This is a large roofed concrete floor that provides a maximum storage capacity of 8,000 tons of concentrate. Eight proportioning bins located below but adjacent to the south end of the patio will be used for actual charge make-up from which concentrate, ore and flux will be proportioned to the feed belt and conveyed to the roaster feed hoppers. Four of the proportioning bins, 80 tons capacity each, will receive...

Jan 1, 1953

The mining industry was one of the first industry groups to be confronted by and to respond to public and government pressure to improve its environmental management. Companies operating in New Zealand and the parts of Australia with firmer environmental and planning controls responded quickly with environmental staff appointments to their development and operating arms. Even in less demanding jurisdictions in Western Australia and Papua New Guinea environmental staff were added to the payrolls. The issues then and now were seen as pollution related with land and water housekeeping leading to progressive or eventual site rehabilitation. Increasingly, however, environmental issues are being recognised as being more complex. They are about equity and social justice. Pollution of water, air or land is seen by the public as a question of personal and public rights, more or less wherever the pollution takes place, on public or private land. Environmental issues in mining have become caught up in the global perspective and a more holistic approach to environmental management. Environmental issues touch every comer of the community and action is being demanded. Nowhere is this better illustrated than on Bougainville Island where increasingly militant demands by land- owners for redress for environmental degradation from the Panguna Mine, on close examination, revealed many years of disenchant- ment with the government and the mining company over a wide range of social, cultural and environmental issues. Failure to address this satisfactorily eventually led to a bloody rebellion and finally an act of secession.

Jan 1, 1991

By Oliveira JF

Thiourea is an alternative reagent for cyanide in gold leaching. The recovery of gold from acidic thiourea solutions by adsorption on activated carbon is based on methods similar to those applied for the extracting of gold from cyanide solutions, but the mechanism involved in the process is not completely understood. In the present work, studies were carried out to evaluate the adsorption of gold onto activated carbon. Experimental data showed good agreement with both the Freundlich and Langmuir isotherms. The adsorption of gold from acidic thiourea solutions proved to be an endothermic process, while the adsorption from cyanide is known to be exothermic. The isosteric heat of adsorption of -11.3 kcal/mol in the early stages of the adsorption is an indication of a process involving chemisorption. The effect of temperature was studied between 15¦C and 55¦C. An activation energy of 3.5 kcal/mol was determined by the Arrhenius plot, which indicates that the controlling step in the kinetics of adsorption is the diffusion onto the porous structure of the activated carbon.

Jan 1, 1993

One distinctive feature of the global mining industry approaching the twenty-first century is the worldwide commitment of mining houses to large-scale projects in developing countries. One good example is BHP's development of the Escondida copper project in Chile. The Escondida orebody was discovered in 1981 and construction began in July 1988. Mining began in December 1990 at a design capacity of 320 000 tonnes of copper contained in concentrate. Out put has grown significantly and shortly Escondida will become the largest single copper mine in the world producing copper at the rate of 800 000 tonnes per annum, including 80 000 tonnes of copper metal. Escondida provides a case study of the development and growth of a large-scale mining operation in a developing country. Key elements have been innovative financing, the management of country risk, the recruitment of an excellent workforce, the use of advanced technologies and best practice in environmental management and community relations. Escondida is one of the global mining industry's success stories in the 1990s.

Jan 1, 1996

Blasting effectiveness must be gauged by total production costs. ANFO charges made up in polythene "sausages" are not as profitable as is indicated by the price of ANFO. All-slurry charges are warranted only where blastholes cannot be dewatered effectively, or where drilling costs are very high. An increase in blasthole diameter leads to coarser fragmentation. This effect is most pronounced in tough and massive or blocky strata, or in ground which consists of unfissured boulders in a softer matrix. When ANFO and some slurry-type charges of small diameter are used in plastic-acting ground, charges may fail to detonate through precompression by charges fired on an earlier delay. The optimum blasthole length is rarely less than four times the burden distance. For best results, blastholes should be inclined to the vertical and parallel to the face. Nominal burdens and spacings are often altered radically by the initiation sequence. For best fragmentation, all blastholes must have good effective faces, and should be effectively stagg- ered with an actual spacing:burden ratio in the approximate range 2.0-5.0.

Jan 1, 1975

Infrastructure is defined as all those parts of a mining development which are not directly concerned with mining and mineral processing. Infrastructure is of significant and growing importance in the overall develop- ment of mines, and the costs could be critical in determining the viability of a project. Prior to_project authorisation, feasibility studies are required, often in considerable detail, to determine costs with adequate reliability. It is necessary that the Engineer should be adequately briefed for carrying out these studies and that good liaison and communication with the Owner be maintained. Methods, costs, order of accuracy, and some special requirements of these studies are discussed. After project authorisation, rapid im- plementation of the proposals is generally desired. A suggested organisation and method for this implementation is presented and dis- cussed. Comments on fees, and particular points in the relationship between Owner and Consulting Engineer are given. Particular reference is made to differences in conditions compared with public works projects. Realistic attitudes of mind towards environmental matters, industrial relations, and contractual relationships are advocated.

Jan 1, 1974

Nippon Telegraph and Telephone Corporation (NTT) developed a new construction method (the M-2 method) that could drive a long, curved small-diameter tunnel (4>1.2 m) without human labor. This method employs the cast-in-place lining system, using quick-hardening resin mortar, so that it can greatly increase the driving distance and execute both long distance driving (longer than 500 m) and curved driving with a radius of curvature of 200 m. Furthermore, the central control system with a mini-computer in a vertical shaft enables all work in a small-diameter tunnel, i.e., excavation, lining, and transportation of excavated soil and materials, without human labor. NTT conducted several field tests and a Practical Application Test (P.A.T.) under a public road bearing great traffic. Good results were obtained and the practicability of this method was demonstrated. Therefore, from now on, NTT will apply this ii-2 method to drive telecommunication cable tunnels in urban areas. This method will also be applicable to constructing public tunnel facilities, such as for water, sewage, electricity and gas.

Jan 1, 1987