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This paper explains why the valuation of mining assets is often a very different exercise from the valuation of the shares in the mining company which owns those assets. The fundamental reason for this is that mining assets, and the shares of the company which owns those assets have different risks. In order to properly value mining securities it is essential to: ò ensure all the different risks and other factors which impact on the value of the mining assets and the value of the shares are taken into account; and determine the extent to which the different risks and other factors are addressed in the value of the mining assets and the value of the shares so as to avoid double counting or not counting at all. If the alternative, but far from consensus, view is accepted that the correct valuation methodology to apply to shares in mining companies should be based on option pricing theory then conventional valuation practice of both mining assets and shares in mining companies will need to be fundamentally reassessed.

Jan 1, 1994

By J Walasiak

In the climate planning of mines and tunnelling with anticipated poor climatic conditions, and especially in case of longer working shifts, the main question is whether it can be reliably prevented that certain climatic limits laid down be exceeded. Working at high temperature and/or humidity can lead to reduced human working energy û a very important economic aspect û and to a risky lack of concentration on the part of the miners or to heat collapse and extremely dangerous heat stroke. With the Deutsche Montan Technologie GmbH (DMT) climate prediction programs, both the dry and the extremely significant humid heat transfer can be calculated. This is due to the high planning reliability involved. With the help of these climate prediction programs it is already possible to determine the anticipated climatic values for the operation phase as early as the planning stage of new ore or coal fields or of tunnel construction projects and to design the optimum air cooling system for every underground project with due regard to technical and economic aspects.

Jan 1, 2005

Authorisation No.66 (to Prospect) was allocated to R.W. Miller & Co. Pty. Ltd. on 1st November, 1976. Exploration has brought coal reserves to measured status in the Jerry's Plains sub-group which are about 550m. thick. The immediately lower Vane Sub-group, about 200m. thick, includes about 20 seams. The total measured and indicated reserves of the two sub-groups based on the criteria adopted by the company amount to 1362 million tonnes in situ. This very large resource is subject to very many mining constraints both physical and economic which limit the saleable reserves under present conditions to about 120 million tonnes. The results of the calculation of reserves after exploration is complete in a deep multiple seam situation is dependent upon the criteria used to include or exclude seams in the reserves. These criteria are state- ments of the miner's expectations of the market, mining and coal preparation technology, local and national politics and the law as it may be applied in the future.

Jan 1, 1979

The products required by customers today have become far more complex and consequently more demanding to handle. And thereÆs the dilemma. Nowadays, people tend to stick to a trade for just a few years instead of for a lifetime, and this means that the customerÆs employees cannot be expected to get more than general knowledge of how to handle modern mining and construction equipment. To meet this challenge, major steps are being taken by suppliers to make their æmusclesÆ more user-friendly. Also the supplier is assuming a larger share of responsibility for the product including operators training, supply maintenance services and, in many cases, performance guarantees. In other words, the supplier is today supplying a function or an activity rather than just muscles. Some of the new generation drill rigs have been on the market for a few years and reliable experience has been collected and is addressed in this paper. Some of the information is well supported by figures while others are just statements from users of the rigs.

Jan 1, 2005

By K Lee, K Fernando, S Rayner

Copper-gold ores have been technically difficult and uneconomical to process due to high consumptions of cyanide. Many copper oxide and sulphide minerals react with cyanide to form copper cyanide complexes, partly contributing to the high level of weak-acid dissociable cyanide in the tailings which is normally experienced during the processing of copper-gold ores. The cost for detoxification, if required for treating these tailings, would further inhibit the development of these copper-gold resources unless the cyanide used for leaching was recovered. Several technologies have been proposed to process copper-gold ores, aiming to recover copper as a co-product and cyanide for recycling in conjunction with the leaching process. A critical review of these processes reveals that a pre-concentration stage (solvent extraction or resin ion exchange) is required. Cyanide is recovered by the conventional Acidification-Volatilisation-Regeneration technique in most cases. A critical evaluation is also provided on technical aspects related to the use of Vitrokele Technology and a newly developed Elutech process in processing copper-gold ores, in particular with its application at May Day Mine.

Jan 1, 2000

By B Sno, P A. Cockburn, R C. West, C U. Jones

Clyde Materials Handling (CMH) and WorleyParsons have developed a concept for a flash furnace feed system using the specialist pneumatic conveying equipment expertise of CMH and the flash furnace process experience of WorleyParsons. CMH has developed a proprietary volumetric feeder (called a Rotofeed), which is extremely accurate and overcomes many of the problems inherent with loss-in-weight screw feeders and drag chain conveyors, previously regarded as state-of-the-art. Initial indications are that the Clyde-WorleyParsons feed system could deliver the following benefits to flash furnace operation: accurate pulseless delivery of feed material to the head of the burner leading to improved combustion performance and process stability; highly accurate split to the individual quadrants of a conventional burner tube, or provision of a smooth hollow curtain to a burner without guide vanes; decreased pressure pulsation in the furnace due to improved combustion control and performance; and decreased temperature fluctuations in the furnace due to improved combustion characteristics and hence reductions in refractory thermal stress and wear.

Jan 1, 2005

By Campain RA, Horner NJ, Limerick JM

The review covers the different concepts of automation which are appropriate to non-ferrous smelting and the degree to which the smelter, and the furnace in particular, is amenable to total automation. Due to the problems peculiar to a smelter, it is unlikely that a fully closed loop system could ever be achieved and that the smelter will continue to depend upon extended manual control supported by computer based information sorting and optimisation.Generally, loop control is performed using Taylor's Mod III process control system. For distinct plant systems involving a combination of process loops, sequencing, and data acquisition, the company has developed its own microprocessor based systems. Process optimisation using computer based analysis of operating data is well established. Utilising this data, computer modelling provides manual set point supervision for the furnace process control system.The impact of automation on the workforce and on operating costs is also examined. Predictions on future developments in the field of automation, optimisation and sequencing are propounded and related to the non-ferrous industry at large.

Jan 1, 1985

The nickel refinery at Yabulu consumes an average of 118,000 kg/h of low pressure steam in stripping operations to-recover ammonia and carbon dioxide from product liquor and ore tailings streams. The steam used in the stripping operations is produced from the 25 MW power generation plant at the refinery. The back pressure on the non condensing steam turbines is maintained at 60 kPa.Studies have been carried out to determine the optimum amount of steam required to be generated for stripping operations. When steam production is increased, the product liquor flow from thewashing thickeners can be increased. This results in improved washing efficiency of the thickeners and therefore improves the plant nickel recovery. A computer thickener wash model was used to predict nickel recoveries at varying steam consumption rates.The studies have shown that in most plant situations, it is not economical to-generate more steam than that already available from existing power production.The studies also highlighted the necessity to use all steam generated from power production at all times to maintain maximum nickel recovery.

Jan 1, 1985

By Johns D. R

The producers of mineral sands on the East Coast of Australia might be regarded as having a simple task of selling Rutile and Zircon. Such is not the case. Differing quality and grain size requirements plus the dramatic increase in the percentage of mineral sold in a processed form have meant a large increase in the number of different end products handled. The resulting sales control problems are compounded by the need to be able to deliver against a large number of separate contracts which may relate to spot or long term sales in small quantities or in bulk shipments. Methods of helping management control this situation have been devised and incorporated into a suite of computer programs. Experience with the approach has been very satisfactory. The effect of changes to shipping schedules, commitment to new or changed orders, or proposed changes to production can be evaluated as and when necessary with little bother. Confidence in decisions taken is high since the process of data collection has been designed to involve

Jan 1, 1977

By Frost M. T

Magnesium is the lightest metal used in structural applications but these are only a small part of magnesium usage, with the use in aluminium alloys consuming half the magnesium produced. Other applications include steel desulphurisation, nodular iron manufacture and metal reduction. Demand for magnesium is expected to increase towards the end of the decade because of a requirement to lighten the weight of automobiles. The current western world plant capacity and production rate is 250 000 tpa. The CIS and PRC also have production capacity but shipments from these countries have been limited in the last half of 1994. The price for magnesium has followed trends similar to aluminium with recent recovery from US$1500 per tonne in 1992 and 1993 to US$4000 per tonne in 1995. The major magnesium producers all use different production methods and the potential exists to establish a large-scale magnesium industry with operating and capital costs comparable to aluminium. The Australian Magnesium Research and Development Project has been established to develop a low cost method of production using the magnesite and infrastructure resources in Central Queensland.

Jan 1, 1995

German coal mining suffers from rock temperatures up to 600C which are the same as in South Africa at 3000 - 4000 m of depth. Therefore cooling plants have increased in the last decade and today a cooling power of nearly 200 MW is installed in the total Ruhr District. Cooling a mine is a little bit different from cooling a bottle of beer in a refrigerator in the kitchen because the heat taken from the bottle of beer is delivered to the kitchen some centimetres away; in mining the cooling-problem is more difficult: here the bottle of beer corresponds to the airflow at the coal face and the kitchen to the surface, So it is necessary to transport the heat or the "coldness" a long distance. In the address by Ieuan Morris some systems for transporting heat from the coalface to the evaporator of the cooling machine and further from the condenser of the machine to a return airflow were described. The following is a short idea of the way this problem is treated in Germany.

Jan 1, 1983

By Mckenzie CK

Delay scatter, although widely recognised, has rarely been studied with the aim of critically reviewing blast designs. With current trends towards increased deck charging, and the effect on the number of separate delays in blast designs, delay scatter is shown to have a rather profound influence on the control of initiation sequence and the ability to successfully con- duct pre-splitting and smooth blasting. Determination of realistic delay scatter distributions is the first step towards application to blast design. Delay scatter must be evaluated in terms of deviation from the nominal time, not in terms of deviation from the batch mean, since the latter is not usually known without specific testing, requiring accurate timing instrumentation. Computer programs using Monte Carlo simulation can then be developed to investigate the probabilities of out-of-sequence initi- ation or near-simultaneous initiation within any specified interval. The procedures have been applied to both production and development blast designs in Australia and Chile to improve initiation sequence control and to rationalise and simplify blast designs.

Jan 1, 1988

Western Mining Corporation (W.M.C.) operates a nickel refinery at Kwinana, 30 km south of Perth. The refinery commenced pro- duction in May 1970, with a rated capacity of 15 000 tpa of nickel metal. A hydrometallurgical route was chosen as the most expedient way to produce nickel metal at a time when world demand for nickel was outstripping the supply. Later events dictated that an increase in production from the refinery be achieved. To this end, matte produced from Kalgoorlie Nickel Smelter, which was commissioned in 1972, was used in varying proportions as a complement to the concentrate initially utilised as input to the refinery. The effect of matte addition was to increase the capacity to 30 000 tonnes of nickel per annum. This was accompanied by other benefits which were 1. reduction in energy consumption per unit of nickel produced, 2. improved metal extraction, 3. improved precious metal recovery, 4. reduced production of ammonium sulphate by-product. Refinery operating results for the years 1970 to 1983 show how matte feed has improved refinery performance in these areas.

Jan 1, 1984

By Unver B

Longwall advance mining is still the predaninant system of coal extraction in the U.K., contribiiting to sane 70 % of underground coal production. Gate roadways providing access to a longwall advancing coal face are maintained adjacent to a rib pillar under high strata abutment pressures and the caving rock mass. It is very difficult to realistically model such access roadways using mathematical or numerical techniques and hence, predict roadway closure. For the past 15 years, a research group in Nottingham University has been engaged in the study of longwall gate roadway stability using observation methods. Gate roadway deformations have been measured in 224 gate roadways and a comprehensive data base has been established. The paper describes the statistical analysis of this database and presents sane. predictive equations which will enable a forecast of the gate roadway closure to he made. Further field work to validate these equations. is described together with an error analysis. The results are very promising and indicate that it is possible to predict gate roadway closure in the U.K. within practical limits of Accuracy.

Jan 1, 1986

By A G. Thompson, E Villaescusa, D Howard

The Western Australian School of Mines (WASM) has developed a facility for the static testing of full-scale ground support elements (Morton et al, 2007). The test facility consists of several stiff steel frames used to support the sample and a screw feed jack is used to load the sample. A large-scale punch test method has been developed to load various shotcrete configurations. The shotcrete is sprayed on to a rock substrate containing a centrally located circular disc. The rock and shotcrete sample is placed on to the sample frame and restrained on all sides. The circular disc is displaced at a constant rate by the screw feed jack which in turn loads the sample. Instrumentation measures the displacement and the load being applied to the sample through the loading disc. The testing method is described in detail and the results from the testing program are presented. The results show that it is possible through laboratory testing to simulate some of the mechanisms of shotcrete support reactions better than conventional beam and panel tests.

Jan 1, 2008

In line with mining operations throughout Australia, Western Mining Corporation Limiter' is striving to increase productivity by intro-ducing mechanized mining techniques wherever possible. Kambalda Nickel Operations' (K.N.O.) largest operating nickel mine, Long Shaft, is currently introducing mechanized cut and fill methods which must provide flexibility to cater for an orebody that variesconsiderably in width, both along the strike and up dip.This has resulted in modifications to the previous approach to primary level develop-ment, and intermediate stope development, and in the type of development and production equipment being employed. Electric-hydraulic diesel jumbos and diesel loaders have now been mated with conventional rail equipment and production airtrack machines are being utilized.The transition to mechanized methods is in its preliminary phase and is being monitored closely to ensure any productivity gains are not offset by a substantial drop in mine grade. The precise method ofmechanized mining has not been finalized and selective methods will be used, according to the ore width and ground conditions, which vary throughout the mine.

Jan 1, 1985

Economic conditions dictated the lead time from concept to commissioning of the Kambalda C.I.P. Plant. The high gold price prevailing at the time the Victory ore-body was discovered provided the impetus to establish a treatment plant with the utmost haste. Consequently only limited metallurgical testing was possible. Fortunately the Kambalda Metallurgical Department had experienced gold metallurgists among its' staff. This enabled a rapid assessment to be made of the ore types to be treated. Flexibility was the keynote in the plant design. Overseas practice and experience was drawn upon extensively, but it was known that problems uniquE to the Kambalda Plant would be encountered due to the high nickel content of the C.I.P. Plant feed and the difficult clays in some of the areas. These fears were well founded and problems have been experienced. However the plant design has enabled these problems to be absorbed, if not overcome, and design production rates were achieved and maintained within three month; of start-up.

Jan 1, 1982

By Hendrix J. L, Nelson J. H

A study was conducted to examine how pretreatment of carbon-bearing gold ores with chlorine enhances gold recovery by cyanidation. It is hypothesized that metal species (including iron and copper) dissolved during chlorination adsorb on the carbon surface hindering the adsorption of dissolved gold. To test the hypothesis, samples of several sulfide minerals were subjected to reaction with sparged chlorine gas to determine which, if any, dissolve faster than gold under these conditions. Then, a synthetic carbonaceous refractory gold ore containing pyrite, chalcocite, activated carbon, and gold was subjected to gas sparging. The results of these experiments showed that chalcocite and arsenopyrite dissolve so that metal (copper and iron) is put into solution slightly faster than gold under the same chlorination conditions. Also, it was observed from the experiments that gold adsorbs on activated carbon during chlorination, but is replaced by copper and iron as the chlorination process dissolves more of the chalcocite and pyrite. The study concluded by investigating ferric chloride addition prior to chlorination to hinder gold adsorption on activated carbon.

Jan 1, 1991

By N Steenkamp, L Furstenberg, W Cele, M Richter

Managing productivity and improving efficiency for a healthy return on capital employed have become key mining industry strategies under prevailing tough global market conditions. However, achieving this in a multisystem environment such as a mining operation can be daunting. The field of discrete event simulation offers some relief, giving engineering teams insight into multivariable systems and stochastic processes. It allows for integrated system thinking and domain expertise to be woven into project thinking fibre. Directed system optimisation and therefore improved efficiency becomes possible. Furthermore, capital discipline accrues from optimal upgrade investments. This paper illustrates the practical application of this approach by reviewing a typical case study for a direct shipping iron ore operation. Dynamic simulation was used to establish maximum processing plant capacity under varying material characteristics and identify capital-efficient upgrades for increasing production.The study started with descriptive statistical analysis of existing data. Discrete equipment and system capacities were defined, followed by static plant mass balance calculations to establish bottlenecks and overall static capacity. Equipment ‘uptime’ and ‘downtime’ analyses established system and overall plant availability and utilisation. From this information, a dynamic simulation model could then be developed and initially calibrated against actual plant performance to verify its robustness. Once confirmed to accurately represent existing plant dynamics, system capacity response to variable changes could be tested to ultimately determine maximum plant capacity. Additionally, plant optimisation was incorporated to arrive at optimal upgrade points. Maximum capacity and necessary upgrades were established as a function primarily of feed size distribution. Additionally, the interfacing effects of rehandling feed material to the final product grade and potentially to life-of-mine were established as important outcomes. The results of the study illustrate the value of using dynamic simulation models to realistically and cost-effectively increase throughput.CITATION:Cele, W, Furstenberg, L, Richter, M and Steenkamp, N, 2015. Capacity evaluation of iron ore processing facilities utilising dynamic simulations, in Proceedings Iron Ore 2015, pp 597–604 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

By B P. Wrench, N R. Steward, C Wu

A gold mine in southern China has transitioned from an open pit operation to a fully underground mine. An overhand mining method is used which requires the mined stopes to be filled with backfill having an unconfined compressive strength of at least 0.35MPa. Tailings from the process plant is deposited into separate flotation and Carbon in Leach (CIL) tailings storage facilities. The tailings has a high fines content and the thickener on site could only produce a dilute flotation tailings at a solids content of about 30 wt%. This resulted in two undesirable outcomes: the density of flotation tailings in the Tailings Storage Facility (TSF) was significantly lower than planned so that the TSF could not store the life of mine tailings and that the backfill product had to include a high percentage of manufactured aggregate and increased cement content to achieve the required strength. This paper presents results of a tailings study which identified that the flotation TSF would be capable of storing the remaining life of mine tailings if an amended backfill product made up of 100% of flotation tailings could be introduced. A 100% tailings backfill with the addition of 8% cement was developed by classifying the tailings and using the coarser fraction in the backfill. This backfill allowed 60% of the flotation tailings to be placed underground and only the remaining 40% in the flotation TSF. A new thickener was designed and installed to thicken the tailings and rheological testing of the tailings, using a closed loop pilot plant, provided parameters to upgrade the underground reticulation system to deliver cemented backfill to stopes throughout the mine and to deliver thickened tailings to the TSF. The revised design was implemented and has resulted in considerable cost savings. CITATION:Steward, N R, Wrench, B P and Wu, C, 2018. Optimisation of surface tailings storage and tailings backfill – a case study, in Proceedings Mine Waste and Tailings Stewardship Conference 2018, pp 454–464 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 23, 2018