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By Hempenstall J, English W

Mine management has a responsibility under the various acts of state parliaments for the adequate ventilation of existing workings. It also has a need to plan adequately for the ventilation of proposed workings. Future workings alternatives have become progressively more complex and ventilation planning of the various possibilities must be undertaken within an atmosphere of rapidly changing market circumstances, etc. Any non-optimal solution will prove more expensive than necessary on both capital and cost bases. Clearly these increasing and alternative ventilation demands of coal mines in Australia have multiplied the work load of ventilation engineers. Management in general has for some time been aware of the advantages of using computers for commercial applications such as payroll and stores inventory. However, while the hand held calculator has replaced the traditional log tables and slide rules for smaller engineering calculations, the larger digital computer has not made the same

Jan 1, 1983

By Green S, McKernan, Skrypniuk

In November 1996, Boddington Gold Mine (BGM) began the implementation of an expert system. The objective of the expert system was to improve plant efficiency by developing an `operator best practice' control philosophy for the grinding circuit

Jan 1, 1997

By R Minnitt

Two methods of calibrating the parameters K and Alpha for use in Gy’s formula for the fundamental sampling error were investigated. Approximately 480 kg of broken ore from Harmony’s Target gold mine in South Africa was used to compile the replicate samples for two experiments. The duplicate series analysis (DSA) and segregation free analysis (SFA) methods differ in terms of their approach to recovering the sized materials required for the calibration procedure. In this experiment the DSA method split off six more-or-less equal masses of material from a 75 kg lot that was successively crushed to finer and finer fragment sizes. The sublots so formed were split into 32 samples and fire assayed for gold. The SFA method used approximately 250 kg of broken ore crushed to 95 per cent passing 2.50 cm, which was then passed through successively finer screens until a sublot of less than 0.0075 cm was obtained. Each of the 15 sublots obtained in this way were split using a riffle splitter into 32 samples that were fire assayed. A total of 672 fire assays were used in these experiments. The sampling parameters K and Alpha were used for the compilation of a nomogram and to calculate the gold liberation size of the ores. While there are no definitive results in terms of the actual gold grain sizes against which the calculated sizes can be compared, it appears that the DSA method produces more acceptable results.CITATION:Minnitt, R, 2014. A comparison of two methods for calculating the constants K and alpha in a broken ore, in Proceedings Sampling 2014 , pp 165–178 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By R Chinamatira

Several technical and economic factors have to be taken into consideration in developing an optimal mining method. This paper describes some of the important factors learnt during the evolution of the sublevel cave mining method at Trojan Nickel Mine, part of the Bindura Nickel Corporation (BNC) in Zimbabwe. Sublevel caving (SLC) has been successfully implemented at Trojan mine since its introduction in 1994. The method has evolved over the past six years into a system that has brought about improvements in efficiencies and productivity. Although the original design parameters used were sound and provided a solid foundation for the system, they needed to be optimised to get the best out of the mining method. Improvements and changes have been made in areas such as the drilling process, charging and blasting techniques, ring pattern design, development size and shape, and the draw control system. This has enabled the mine to develop an SLC operation that is efficient and innovative. Experience gained, together with the theory available has given us a much better understanding of the system. This knowledge will be used in the future to enhance the system further. Given the low grades of the BNC Mines, management recognises that only through technical excellence and efficient mining can the mines reduce mining costs and maintain profitability and competitiveness on the world market. In the Zimbabwe mining industry reaction to technological change, mechanisation and advancement have been relatively slow, due to isolation and economic constraints, compared to the rest of the world. Economic difficulties prevail, with high inflation levels, a poor exchange rate, lack of foreign currency and other associated problems. Despite these constraints, the bold steps taken have transformed Trojan mine into a more efficient and competitive operation, presenting itself as the leading mine in the BNC group. Appendices give data to illustrate the benefits obtained.

Jan 1, 2000

By Hall K

The Osborne copper gold mine, 100 per cent owned by Placer Pacific Limited, is situated 195 kilometres south east of Mount Isa. The orebody is broadly categorised into three main ore zones; oxide, transitional and sulphide copper. Copper oxide

Jan 1, 1997

In Australia a social impact assessment (SIA) is generally required prior to the approval of a mineral resource extraction or processing projects as a part of the Environmental Impact Assessment (EIA) process. In recent years there has been increased attention on the adequacy of the SIA process applied in major project assessment. Most applications have focused on the impact identification process with little attempt given to the community negotiating power over how impacts will be addressed. The impact assessment tends to occur at a single point in time, with no subsequent re-evaluation or ongoing social impact management and monitoring process. The assessments rarely specify how responsibilities for impacts on communities may be apportioned between project proponents and government, and have been inadequate in dealing with cumulative project impacts. In Queensland, concern about these shortfalls have led to the release of the Sustainable Resource Communities Policy 2008 and requirements for social impact management plans (SIMP) to be developed for each resource development in the State. In this paper a 'pressure-state-response' approach to impact assessment is used to develop an 'impact-response-monitoring-evaluation' (IRME) framework that can be applied to ongoing evaluation and monitoring of social impacts. The framework is applied to coal resource developments in the northern Bowen Basin in Queensland to identify core requirements in a SIMP. The IRME framework is flexible enough to be implemented at various spatial and time scales, for the wellbeing of the local and regional mining and non-mining communities in Australia. The framework can be further examined in other mine developments and could be integrated with the existing mining or environmental protection acts.

Jun 1, 2010

Coal has been mined in New South Wales for nearly 200 years and prior to 1970 the vast majority of this coal was mined from underground mines using bord and pillar or similar systems.Since 1970 there have been two notable changes in coal production trends in New South Wales as can be seen from Figure 1.1. The steady growth in coal mined by open cut methods. Open cut output grew from about seven per cent of the State's output in 1970/71 to 43 per cent in 1990/91.2. The steady growth in coal mined by the longwall method. longwall output grew from negligible amounts in 1970/71 to 48 per cent of underground production in 1990/91. mines operating longwall units produced 61 per cent of underground production in 1990/91.

Jan 1, 1992

Conveyor belt haulage offers the advan tages of continuity of operation, minimum labour requirements, and the ability to handle large volumes of material over extended periods. However, breakdown of critical con- veyors in the system can cause undue and substantial losses in production output at the working faces, unless adequate surge bin capacity is incorporated in the haulage system. A conveyor belt simulation programme, code name 'Beltsim' was developed by Bucklen et al (1968) at the Virginia Polytechnic Institute in the U.S.A. and provides a quantitative measure of the performance of a conveyor belt network design. A limitation still exists with the computer programme and involves the inability of the programme to predict the necessary surge bin capacity to overcome conveyor belt downtime. The computer programme was modified to overcome this limitation, to simulate a con- veyor belt breakdown, and to provide a quantitative prediction of the surge bin capacity necessary to permit a modern mining system to operate effectively and continuously.

Jan 1, 1977

This paper reviews factors involved in the feasibility stage of underground mine project development. Emphasis is placed on the need to first select the best method of extraction and make the most accurate assessment of the expected output even with the uncertainties which may exist in structural interpretation, ground stress, geotechnical factors, and industrial conditions. The subsequent engineering planning should be undertaken from the point of view of the face requirements and is subject to constraints imposed by the method of work and nature of the deposit and, in the case of access, to surface constraints and services.

Jan 1, 1983

By Murray G

This paper outlines the processes involved in acid generation from sulphides and the key factors in identifying and predicting time dependent changes in the nature of acid mine drainage (AMD). The initial characteristics of mine water; whether drainage from exposed mining faces, runoff and seepage from waste dumps or seepage from process tailings; do not necessarily reflect the long term potential for AMD. The ultimate quality of mine drainage is a function of the interaction of many chemical, physical, biological and engineering (operational) factors. Techniques are available that can predict the qualitative nature of acid generation and mine drainage quality but accurate quantitative predictions are essentially impossible at the present time. As more and more mining operations exploit sulphide ore, the AMD and acid waste issue will become a. far greater concern. The significance of time dependent factors in the production of acid mine drainage-.is not just restricted to particuL.ar mine sites but needs to be recognised by the mining industry as a whole.

Jan 1, 1988

Papua New Guinea is geologically prospective for large, medium and small mineral discoveries. All profitable developments to date have been very large mines but for every large mine there should be many small mines which could be developed under appropriate circumstances.The Papua New Guinea Government should, with appropriate changes to fiscal, legislative and policy regimes, create a favourable exploration envir-onment to encourage a major increase in exploration by small exploration companies and subsequent discoveries and mine development.

Jan 1, 1994

By Slattery T. E

Recent develognents in zinc flotation at the North Broken Hill Limited concentrator are discussed. An outline of the history of zinc flotation and a description of current practice is presented. Installation of on-stream X-ray analysis probes has resulted in inproved metallurgical performance and focussed attention on automatic control. Results are presented of investigations made over the past six years which have led to the formulation of experimental schemes for the automatic control of zinc flotation.

Jan 1, 1983

By M Magee, D Way

The Mount Isa Copper Concentrator was commissioned in 1973. In 1991, two autogenous grinding mills were installed replacing two stages of crushing, one stage of rod milling and one stage of primary ball milling. The cyclone overflow P80 of the secondary ball milling circuit was reduced to 120 microns due to the increased operating power in the AG/SAG mill circuits. A study of the mineralogy of the milled products and the plant flotation recovery indicated that the installed secondary grinding energy was more than what was required for adequate liberation of the chalcopyrite and half of it had potential for more effective use elsewhere. Halving the secondary grinding energy meant only one of the two secondary ball mills would be needed. The predicted saving in operating cost of one less ball mill was more than two million dollars per annum. This paper summarises various plant trials that were conducted in the Copper Concentrator to decommission one of the two secondary ball mills.

Jan 1, 2004

By F De Beurs, S Davies

With the emphasis on CO2 emission legislation and the increasing price of traditional fossil fuels like coal, oil and gas, the use of alternative fuels is becoming more and more attractive for the industry, particularly for the cement industry. The variety of materials burnt in the kiln is enormous and varies from tyres, to animal meal and other waste material or by-products that would otherwise end up in an incinerator or landfill facility. This wide variety in materials demands thorough analysis to determine what elements are present in the organic matrix. The elements present may have an influence on the process or the quality of the cement. Toxic or environmental unfriendly elements may be incorporated or dissolved in the clinker phases; whereas volatile components may be present in stack emission to the atmosphere. X-ray analysis is already the key to elemental analysis in cement production, and is used here to determine the composition of these alternative fuels. The XRF spectrometer configuration used in this study is designed to overcome the difficulties associated with the analysis of strongly varying light organic matrices containing heavier elements in minor and trace-level quantities. Heavy element specific excitation conditions and three-dimensional polarised optical geometry increased the signal to background ratio and improved detection limits compared to conventional XRF spectrometers.

Jan 1, 2008

In process industries, time-dependent random fluctuations of raw material characteristics and mass flow rates in bulk material or pulp flows cannot be always prevented for different reasons, eg because of the geological situation (no uniform formation of the deposit) or/and because of technological reasons (segregation in bunkers or on stockpiles). Since a long time, there has been practical experiences that such fluctuations can have negative consequences, eg: ò fluctuations of the final products characteristics, ò higher expenditure for process control, and ò worsening of technological characteristics (recovery, sharpness of separation etc). In the literature, there can be found a lot of details as to, eg the improvement of the sharpness of separation in a jig in dependence on the raw material blending (Kubitza, 1981; Gathen, 1983) or the decreasing flotation recovery with increasing raw material characteristics fluctuations in iron and potash ore processing plants (Bubnova, 1978). Up to now, however, these consequences of random fluctuations, eg on the separation efficiency were not predictable theoretically. It could be shown by means of the general model for mechanical macroprocesses (Graichen, 1989), that the reduction of input fluctuations passing a blending facility can be calculated in this way. In this example, the steady state of the process is the wanted one, but, in general, the model is able to describe also non-steady states of the process regarded. On the other hand, the general model of mechanical macroprocesses has been used successfully for modelling separation processes, eg cross-flow and air classification (Molerus, 1969; Neesse, 1991; Senden, 1979; Tichonov, 1973). That is why it was tried to model the influence of input fluctuations on the separation efficiency, that means, the impact of non-steady states - as a consequence of random fluctuations - on a separation process. The models discussed in the literature are related nearly exclusive to the steady state of the process. The reasons for that lie in the (relative) simplicity of the models and the fact that the steady state is aimed at by means of blending processes under practical conditions - because of the advantages mentioned above. These models cited have proved to be superior to other models, since the basic general model for mechanical macropocesses makes possible the consideration of turbulence acting in the process unit and influencing the separation process essentially. This is valid also for modelling the turbulent cross flow classification, applied to mechanical classifiers and hydrocyclones, where the correspondence between the separation characteristics (cut size, separation sharpness) calculated and determined experimentally is much better than for other models.

Jan 1, 1993

By A M. Robertson, R Lefebvre

Air movement and associated oxygen transport through waste rock dumps has the potential to significantly enhance the rate of oxidation of pyrite-bearing material. While this is a desired outcome for most heap leach operations, airflow in waste rock storage facilities can result in significant increases in generation and acceleration of acid rock drainage. Hence, a good understanding of internal airflow through waste rock dumps is required to control ARD and minimise any associated liability. The principal mechanisms contributing to airflow and oxygen transport in a waste rock pile include: diffusion; advection due to a thermal gradient (chimney effect) and/or wind pressure gradients; and advection due to barometric pumping. While diffusion is typically limited to a near-surface zone of a few meters depth, advection and barometric pumping have the potential to move air (and oxygen) to much greater depths into the pile. In general, the more permeable the waste rock material, and the greater the height-to-width ratio of the waste rock pile, the greater is the potential for advective air movement. The reactivity of the waste rock material as well as the coarseness (hence air permeability), and the spatial variability of these properties within a pile, have a strong influence on the magnitude of thermally induced advection. In contrast, air movement due to barometric pumping is controlled by the waste rock porosity, changes in ambient air pressure and the heterogeneity of air permeability of the waste rock dump. Results of field monitoring and numerical modelling using TOUGH AMD are presented to illustrate the concepts on air movement in waste rock piles discussed in this paper. During the design and construction phase, airflow can be controlled by judicious placement of reactive waste rock and use of selective placement techniques to control the internal structure of the waste rock facility (eg introduction of horizontal layering, prevention of inclined, high-permeability, channels (æchimneysÆ)). Several closure measures are available to minimise airflow including: placement of a low-permeability cover to reduce air entry; and placement of a non-reactive cover material to isolate reactive material from the zone of active airflow and/or regrading of the waste rock pile to obtain a geometry and internal structure less susceptible to advective airflow.

Jan 1, 2003

By Linkson PB

The presence of residual cyanide in mine tailings and fill sands may, under specific circumstances, lead to acute and/or chronic cyanide poisoning of the environment and individuals. In this paper, the nature of cyanide contained in mine tailings is discussed, along with the circumstances under which such cyanide would become a hazard. A number of methods for cyanide degradation are reviewed in the paper, with special emphasis being placed on biological degradation (due to its low costs and the non toxic nature of the degradation process itself). Recommendations are made as to the best methods of setting up a biological degradation system, for use in mining Situations.

Jan 1, 1987

This data is intended to provide a quantative cost comparison of one 40 800 kg. pull down rotary blast hole drill versus two smalter drills in the 18 100 kg. pull down class. While this cost analysis is affected by blast design, this paper is not intended to be a treatise on blasting theory and therefore places more emphasis on costs than on blast design. All costs, prices and production rates in this paper are estimates and should be used for comparison purposes only. The drills are sized in order to maintain a production rate sufficient to stay ahead of a dragline that is excavating in an average overburden (sandstone and shale). The large drill will use 270mm bit and penetrate at a rate of 0.012 m/s (scheduled basis). The small drill will use 170mm bit and penetrate at a rate of 0.010 m/s (scheduled basis).

Jan 1, 1986

By Dunne RC

The physical properties of an orebody require determination for virtually all mining projects, new and existing. The extent and regularity of such determinations being subject to the size and homogeneity of the orebody. Such properties have an impact at the design stage of new plants, with respect to equipment specification, and thus effects capital costs; and also impacts on the operating costs of new and existing plants, with respect to power consumption, production levels and part replacements. All of these can severely alter the bottom line and can be the determining factor in the economic viability of many projects.This paper examines some of the most common properties that are measured, the procedures utilised in determining these properties, and their variability under conditions of reproducibility, and to a lesser extent repeatability.

Jan 1, 1997

By Walraven F, Knott G. G

Using a typical small logging instrument (Neltronic KPD), a natural gamma reference section for part of the Brockman Iron Formation and part of the Mt. McRae Shale has been established in the Newman area. This is compared with the stratigraphic type section of Trendall and Blockley (1968). Folding and faulting are recognised using natural gamma logs. Because of the confidence with which stratigraphic horizons can be identified, less expenditure on diamond and percussion drilling is required to confirm stratigraphic position. Using natural gamma logs as stratigraphic control the apparent thinning of the Banded Iron Formation during iron enrichment is Demonstrated.

Jan 1, 1973