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By J Liu

In situ coal gasification is a method of extracting a high proportion of the energy value from coal without the need for mining. In situ conversion of coal to combustible gases is achieved by drilling wells into the seam, injecting gasification agents and initiating combustion. The product gases are then extracted to surface using production wells. These gases are clean energy sources for power generation, heating or synthetic fuel production. In situ coal gasification is of particular interest with respect to its lower environmental impact, potential application to otherwise inaccessible energy resources (ie offshore, deep deposits or beneath protected lands) and low capital intensity. Practical application of this clean technology is restricted primarily by lack of satisfactory quantitative descriptions of the processes involved, in particular the hydromechanical processes.In this study, three characteristic physical zones of an in situ gasifier are identified as the rubble zone, combustion front and virgin coal zone. Coupled mechanical processes of coal consumption and overburden collapse are used to describe the permeability profile in the rubble zone. Additionally, the redistribution of overburden load associated with coal consumption is accounted for with the formulation of a stress (compressive) dependent permeability profile, which is applied to the virgin coal zone. The model was implemented into and solved by FEMLAB, an advanced computer simulation tool. The flow process, according to DarcyÆs Law, is subsequently described in terms of permeability dependent injectivity. Injectivity is an indicator of flow velocity, which has been identified as a crucial factor in determining the commercial value of product gases from in situ coal gasification. The stress alteration to coal permeability was found to have a dominating influence on the flow process. This finding implies that a greater understanding of the in situ coal burning induced deformation of surrounding rocks would be of significant value in assessing the economic viability of applying this clean technology to potential sites.

Jan 1, 2004

The smelting operation associated with the production of aluminium has a voracious appetite for high grade carbon materials. Within the technical parameters of the Hall-Heroult process, the reduction of alumina to one tonne of aluminium results in the consumption of nearly 0.5 tonne of carbon at the anode of an electrolytic cell. This paper reviews the role of carbon and the basic quality requirements of carbon products in the production of aluminium, discusses the effects of certain physical and chemical specifications on smelting and related operations, and examines recent trends in the quality of these raw materials.

Jan 1, 1977

Many of the large refrigeration plants used in, the cooling systems on deep South African gold mines are situated on surface where they are exposed to seasonally and diurnally varying climatic conditions, and to a diurnally varying demand for cooling made by the mine. It has been traditional to accommodate the seasonal variation in climate by manual control applied to the plants at appropriate times of the year, and the plants have normally been specified to conform passively to the diurnal variations. This paper introduces new strategies for the active automatic control of the plants on a diurnal cycle, and shows that attractive benefits in energy and chilled water resource management can be accrued through the use of these strategies. The results have been derived through the modelling and simulation of a representative refrigeration plant.

Jan 1, 1985

By Harbort G. J

Jameson cell pilot plant trials were conducted in a number of areas in the Red Dome gold/copper flotation plant during 1991. The aim of testwork was to reduce the amount of cyanide soluble copper reporting in tailing to the gold leach plant, and hence reduce cyanide consumption. A number of these tests were conducted in parallel with conventional flotation columns. Laboratory tests were conducted to simulate the performance of the existing plant when compared with the addition of the Jameson cell allowing an extra sulphidising phase. This paper reviews the comparison of the Jameson cell and conventional columns in recovering cyanide soluble copper, while maximising copper concentrate grade. Key parameters that are investigated are residence times, air/pulp ratios, superficial gas recoveries and size by size recoveries. A brief comparison of performance of the Jameson cell and column in the controlled potential sulphidisation process is also presented. An estimation of the reduction in cyanide consumption is given.

Jan 1, 1992

By Segnit ER, Jensen G

The decoppering of soft and hard leads was investigated by stirring in an open pot, using sulfur or sulfur plus pyrites, or sulfur plus pyrrhotite, as reagents. Lead samples taken during the process were analysed for copper. Dross samples were examined by optical micro- scope, SEM and XRD. Soft lead containing silver can be decoppered satisfactorily by stirring with 0.1% S at low temperatures - close to 330¦C. Soft lead, whether containing silver or not, can be decoppered satisfactorily at higher temperatures by stirring with 0.1% S plus 0.4% pyrites. Then CuFeS2, Cu5FeS4 and PbS are formed, instead of Cu2S, CuS and PbS when using S alone. Hard lead containing tin can be decoppered satisfactorily by stirring with 0.1% S at temperatures from 320-400¦C. When stirring with 0.1% S plus 0.4% pyrites, reversion of copper from dross to lead on prolonged stirring does not occur. Hard lead without tin can be decoppered with S plus pyrites better than with S alone, but the presence of antimony hinders the decoppering, which is less effective on lead with 5.5% Sb than with 2.3% Sb.

Jan 1, 1980

By Hodges D. A

The manufacture of steel from raw materials which have to be mined, transported and processed must affect the environment. Steelmaking, like almost every other stage of manufacture involves the unwanted production of dust and fume; thus a major part of the steel industry's effort to minimize changes to the environment is the collection, treatment and recycling of dust and fume to avoid pollution of the atmosphere and waterways. The paper describes how this achieved in the various steelmaking processes and shows the diversity of problems-and their solutions in this context. Particular emphasis is, given to basic oxygen steelmaking.

Jan 1, 1976

Ridgeway Gold Mine (Ridgeway) has a clear mission to maximise its cash flows in order to deliver shareholder value and is developing strategies to achieve this. Business process management using leading measures is core to this approach. Leading measures indicate potential outcomes ahead of time, allowing time to adapt and improve. Ridgeway is making strategy a central organisational agenda, creating a focus to æput first things firstÆ by controlling æleadingÆ activities and mobilising employees to act. Feedback using specific, leading measures gives employees the opportunity to proactively adapt their behaviour in order to deliver internal business outcomes that generate cash flows and shareholder value. This paper will outline RidgewayÆs business approach to track and control processes from resource to revenue, with a focus on delivering cash flows and shareholder value. Ridgeway is implementing a Balanced Scorecard approach (Kaplan and Norton, 1996). A total business focus is taken and leading measures are identified. Specific measures are used to score our success from the perspectives of learning and growth, internal business processes, customer and stakeholders, and finance. These measures and improvement plans are targeted at strategies to maintain our ælicence to operateÆ with our community stakeholders, produce accurate plans and forecasts, improve our operational effectiveness and grow our business.

Jan 1, 2002

Curragh Queensland Mining Limited, a co-venture of Australian and overseas interests, operates a large multi-seam strip coal mine in Central Queensland. Coal uncovery is by four large walking draglines.Mine planning is an essential and strong component of the Curragh operations so that informed short- and long-term management and operational decisions are made.

Jan 1, 1992

By Hayes P. C, Matthew S. P

The product morphologies formed on the reduction of dense wustite crystals are classified into three types, A) porous iron, B) porous wustite covered with dense iron, and C) dense wustite covered with dense iron. The mechanisms of formation of these structures and the effects of impurity elements on the product morphologies are discussed.

Jan 1, 1985

Kalgoorlie Consolidated Gold Mines Pty Ltd is currently developing the 'Super Pit' gold mine in the mining area known as the Golden Mile adjacent to the city of KalgoorlieBoulder, Western Australia. The presence of numerous abandoned mine workings and complex structural geology has required considerable geotechnical input into the determination of the optimum pit slope geometries for both interim and ultimate pit slopes. Slope design is based on detailed site investigation and stability analysis which is balanced with historical operational experience. This paper discusses the process of determining the optimum pit slope angles for each of the stages of the west wall of the 'Super Pit'. The risks associated with slope instability are discussed for each stage.

Jan 1, 1994

By Grace NC, Lightfoot BW

Small scale trials of the smelting of a copper concentrate in the Sirosmelt submerged lance reactor are described. Pellets of concentrate were dropped into the reactor while injecting air-rich mixtures of oil and air through a lance into a bath of matte overlain by slag. This produced a discardable slag and a matte which was converted in sequential stages in the same reactor to white metal and blister copper. Difficulties were encountered in determining the end points of the converting stages but control techniques were developed to allow successful operations producing blister copper. Deportments of minor constituents of the concentrate to slag, matte,metal and fume for the three stages are reported and possible applications are Discussed.

Jan 1, 1980

By Ueki S

Underground coal gasification (UCG) is a promising process for obtai- ning energy from coal, which is either unmineable with current mining techno- logy or uneconomic to recover, using conventional methods, in the present energy market situation. There are several coal fields, which could become new coal reserves, if the UCG process were successfully applied. In the 1960's Japanese researchers made a number of basic studies and field tests into UCG, although not all of them produced favourable results. This paper reviews Japanese research on UCG. This includs basic studies into coal gasification using a small, tube reactor fed by air and oxygen, and also large scale model stu- dies(reactor size of 8.Om x 2.4m x 1.5 m). Field test results from Akabira colliery in Hokkaido and a feasibility study of power generation using UCG from a coal field in Hokkaido are also Presented.

Jan 1, 1987

By Parker RJ, Swindells CF

The authors have used the geotechnical study for design of the South Wall of Mt. Newman Mining's Mt. Whaleback Mine to illustrate how geotechnical studies can be economically justified. This is achieved by relating the savings resulting from increased ore recovery and prevention of failure to the cost of the study. An outline of the geotechnical study is provided in the paper, including a brief description of the innovative methods used to investigate geological structure of the mine and descriptions of the methods of slope reinforcement adopted.

Jan 1, 1986

By D Ziaja, W Jaspers

A brief history of the development of pneumatic flotation cells from early in the 20th century to the present day and a comparison to conventional cells demonstrates the efficiency and simplicity of design and operation of the ænew generationÆ of pneumatic cells. Recent successful testwork on phosphate minerals in the USA and a variety of coal types in Australia confirm the utility and efficiency of the design. The key aspects of this technology are improved recovery and selectivity with lower capital expenditure and operating costs.

Jan 1, 2005

By Mazandarani M, Chabot L, Vichion K

Pitch-steering models have been developed for discretely advanced mining machines (such as heading machines and coal shearers) using small-angle geometry and there are illustrative examples of simulator predicted performance. Although simple linear models result from the analysis of open-based machines, sledge mounted machines require execution of a Linear Programming energy minimisation to determine the attitude of the machine base at each advance over the previously cut floor steps. An analytical approach is based on elastic beam concepts developed for such applications as longwall face conveyors, caterpillar tracked machines such as continuous miners and longhole drills. Simulation results for longhole drills show the expected performance of an automatic guidance system and the destabilizing effects of sensing deviation too far behind the drill bit. Certain drill bit boundary conditions are expected to assist TBM. steering studies in three dimensions.There is a real role in mining machine steering for the mathematical models used in flight simulators.

Jan 1, 1991

By Davey P. T, Tsambourakis G

Mineralogical analysis of supergene sulphide ore recovered from areas close to the underground workings at the abandoned Mutooroo (South Australia) mine shows that the original sulphide minerals have undergone substantial alteration. The cause of this alteration is believed to be contact with the highly saline, acidic mine water. The copper is now present as a sulphide that can best be described as a copper- and iron-delicient chalcopyrite, CuxFeyS2, where in most cases x < y. The values of x and y vary from point-to-point within each grain.Leach tests under a variety of conditions show that dissolution of the copper from the supergene sulphide ore can be readily achieved, particularly when compared with the behaviour of Mt Isa chalcopyrite concentrate. For the supergene sulphide ore, an increase in the acidity and the iron(lll) concentration of the leachant re ults in an increase in the rate of copper dissolution.The results are briefly discussed in terms of the experimental in-situ leaching operation at Mutooroo, South Australia.

Jan 1, 1986

By Payne P, Beirne W, Geldard D, O&apos

Whim Creek Consolidated N.L. has operated openpit mines at Meekatharra since 1980. Mining operations commenced with the Haveluck openpit and the Phar Lap openpit was started in 1 984. Grade control in the Haveluck mine was simple because the orebody showed good continuity along strike and down dip and had an easily recognisable hanging wall contact. Problems were encountered once mining corn menced at Phar Lap because of the complex lithologies, alteration and faulting involved. Simple grade control techniques developed for Haveluck failed and were not solved until an understanding of the ore bodies was achieved.The integration of all geological data into the interpretation of the developmentdrilling results has proved essential to achieve effective grade control atreasonable cost.

Jan 1, 1986

In coal room and pillar, and pillar extraction panels, the sidewall conditions were investigated based on underground measurements and numerical simulations. Three-dimensional linear elastic models provided a useful and quick prediction of the amount of sidewall spalling. However, more complex constitutive models were required to simulate more accurately the extent of fracturing and its effect on the stress re-distribution. The input parameters of a Mohr-Coulomb model were determined by back-analysis of underground measurements, and the effect of the depth of the workings and the time dependent occcurrence of coal pillar fracturing were analyzed.

Jan 1, 1992

By R Lurf, C Weber

In the frame of this paper a holistic dynamic process model approach is presented in order to introduce operational and technical excellence in drilling and blasting. Both on a macro and micro level the single process parts of drilling and blasting are outlined and their interaction is explained. The use of this approach for closing the gap between process planning and process implementation is explained and an example of the value generated is given.

Jan 1, 2007

The rapid growth of world civilisation will have a significant impact on the way humans live in the future. As the global population increases and more countries demand a higher standard of living, the world must provide more food and greater energy and mineral resources to sustain this growth. The difficulty of doing this is compounded by three broad trends: the conversion of agricultural land to development uses; the increasing urbanisation of the world's population; and growing concern for the maintenance and improvement of the environment, especially regarding global warming and the impact of population growth. Underground space utilisation offers opportunities for helping address these trends.

Jan 1, 1993