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By B Cooper

During the design of a new production facility for a greenfields or significant brownfields expansion many design decisions are made driven by an unquestioning objective to achieve 'lowest cash-cost' production costs. In many cases this translates to a design and operating philosophy based on largest-available, single-line equipment. Although acknowledged as an approach that is efficient from an operating cost perspective does this approach always maximise shareholder value? There is an increasing awareness in the mining industry of the value of project flexibility, robustness and value options. The design of a new production facility creates a window of opportunity which should be structured to ensure that project value options and robustness are understood and exploited. This requires the use of emerging valuation methodologies, such as Value-at-Risk and Real Options, as well as tried and trusted NPV/IRR approaches. The paper provides an overview of the basis and application of these less well known techniques in the context of metallurgical plant design. Design guidelines that demonstrate how value options and flexibility can be quantified from both a risk and value perspective are presented. Issues such as use of single versus multiple line equipment, optimum cut-off grade and improved exploitation of the inherent variability of the orebody are also examined. Finally the management issues and approaches to achieving this will be briefly discussed; for example it is common during project development to drive towards increasing certainty as rapidly as possible to facilitate 'accurate' estimation of costs. Understanding and exploiting value options requires a project culture that tolerates, and revels in, ambiguity and uncertainty û something that would make many project teams uncomfortable!

Jan 1, 2008

Timestudy analysis of mining operations at North Broken Hill Limited has been carried out by dissecting operations into small elemental components, and accurately timing these elements. Over a wide range of observations, this has enabled standard time values to be calculated for all underground work.The application of the standard values is in calculating performances as a measure of work output and Performance Controls are kept on approximately two-thirds of underground employees. Through the Controls it has been possible to stimulate supervisory action to improve low performance, and to reduce delays and lost time.The values are used to calculate contract" prices, and anomalies in previous prices have been adjusted on work values and not on arbitrary standards. In out-of-the-ordinary circumstances, the request for a timestudy investigation has been made by both operatives and foremen, and the contract set following the timestudy analysis has been to the satisfaction of both parties.The range of values enables contracts to be applied to work which was previously performed on a day basis, resulting in improved performance.A natural corollary of timestudy is the analysis of methods, and in some cases method improvements have been introduced.It is anticipated that further investigations will be made on methods.INTRODUCTIONIn 1953, a Timestudy analysis of mining operations at North Broken Hill Limited was commenced under the guidance of management consultants. Its aim was, to determine standard time values for specific operations, which would provide management with a measure of productivity beyond the existing measures of tons or feet of advance, and also to determine whether increased output was available under existing operating conditions.

Jan 1, 1956

By Y Peng, D J. Bradshaw, X Chen

At NewcrestÆs Telfer gold mine, a strategy of regrinding pyrite rougher flotation concentrates has been proposed to increase gold recovery and reduce cyanide consumption in the CIL circuit. The regrinding will be followed by an additional copper/gold flotation stage, where copper minerals need to be separated from pyrite. However, although the minerals are well liberated, the separation of chalcopyrite from pyrite in the cleaner stage is not always straightforward. The surfaces of the fine particles, produced during regrinding, are more easily oxidised and contaminated than coarse particles, directly influencing the particle floatability. The depression of pyrite is difficult in the cleaner stage as well due to copper activation, a process which is also highly dependent on the grinding environment. In this study, different grinding media, including mild steel and stainless steel, was used in the regrinding to produce different regrinding chemistry, such as, pH, Eh, and iron hydroxide contamination. The effects of regrinding conditions on chalcopyrite flotation and its separation from pyrite were studied. It was found that the stainless steel grinding media, which produced an oxidising environment, was more beneficial for the separation of chalcopyrite from pyrite after regrinding. The mild steel grinding media had a detrimental effect on both chalcopyrite and pyrite flotation. This study addresses the importance of choosing suitable regrinding conditions in the pyrite and copper flotation circuit.CITATION:Chen, X, Peng, Y and Bradshaw, D J, 2012. Effect of regrinding conditions on the flotation of chalcopyrite and its separation from pyrite in the cleaner stage, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 279-286 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By Kohra A, Shoji S

The amount of copper production by flash smelting process occupies about 17% (equivalent to 1.4 million t/year) of total free world production. In Japan, 650,000 tons of copper is produced annually by flash smelting. This is 65% of the gross copper production of Japan. To reinforce pollution control, promote energy saving, and enhance production efficiency by increasing the size of furnaces, conventional blast furnaces and reverberatory furnaces are being replaced with the flash smelters worldwide. The Ashio Smelter started copper production in 1884 and developed in association with the Ashio mine. In those days, the Ashio smelter produced copper by using the blast furnace process designed for the high-grade ore from the copper mine. At that time, this process was specialized in Japan. In 1956, for the first time in Japan, the Ashio Smelter introduced the flash smelting process developed by Outokumpu Oy of Finland (it is suitable for treating the copper concentrate, producing sulfuric acid and improving production efficiency). The flash furnace in Ashio, the first ever in Japan, had a capacity of 230 t/day for copper concentrate and was operated up to 1962. During this period, various operational troubles were solved, and further improvements were made; and, in 1962, a Furukawa-type flash smelting furnace was completed in Ashio. This improved version of a flash furnace had a capacity of 450 t/day. There was one flash furnace and one waste heat boiler, which were arranged in a unique pattern for that time. This furnace may be said to be the prototype of the present flash smelting process in the world.

Jan 1, 1987

By D Macklin, R Hammond, T G. Blenkinsop

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Base metal sulfides at the Currawong volcanic-hosted massive sulfide deposit in the Lachlan fold belt of Victoria, south-east Australia, were formed in the late Silurian, but D2 deformation of the deposit in the Devonian Bindian orogeny was responsible for structural repetition that created the resource. The primary sulfide lenses were stacked by reverse-sense shear zones within a volcano-sedimentary sequence dominated by dacitic intrusions and turbidites. Shear zones were localised along lithological contacts, including the margins of the sulfide lenses. The competent dacitic intrusions did not fold during D2; folding was restricted to the packages of metasedimentary rocks. Overturning occurs within, but not between, the metasedimentary packages. The overall geometry of the deposit is that of a duplex, but the detailed shape does not conform to idealised duplex types, probably because of post-D2 deformation. A significant complicating factor for understanding the deposit, and for resource evaluation, is the dramatic variation in deposit geometry along strike, which may also be due to post-D2 deformation. The present day configuration of the deposit results from constructive thrust repetition of what may have been a single ore lens and destructive along-strike disruption controlled by rheology.CITATION:Blenkinsop, T G, Macklin, D and Hammond, R, 2015. Rheological controls on the geometry of the Currawong volcanic-hosted massive sulfide deposit, Lachlan fold belt, Victoria, south-east Australia, in Proceedings PACRIM 2015 Congress, pp 469–474 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By L C. Thompson

A new understanding of the formation of black organic shales in the Illinois Basin has contributed to insights on how to produce methane from these complex reservoirs. These shales are far from simple shallow derived sediments but are in fact the result of a complex series of events which include the intermixing of volcanic detritus and the marine organic material, onlap successions and low energy turbiditic intraformational activity. This has led to a review of the commercial significance of the mid Devonian shales in the sedimentary basins of the eastern half of the USA. These shale sequences are also characterised by very little contribution from the underlying Lower Palaeozoic carbonate formations. The later diagenetic influences and the interaction of sea floor bacteria especially since the mid Devonian have lead to the creation of a major source of energy in the form of methane. Vast areas measured in 1000s of square kilometres are known to contain biogenically derived natural gas as methane. However, this vast resource produces very little gas due to abundance of illite which acts as a major adsorption mineral and creates a refractory situation where though there is abundant gas present the rate of release is clearly subeconomic. This paper will present the results of recent laboratory trials which have indicated that it is possible to create microfracturing using bacteria within the gas bearing shale sequence and also restart the methanogenesis process. As most coal bed methane environments have similar organically derived shales in direct relationship to the coal beds themselves then this paper has ramifications for this industry as well.

Jan 1, 2004

By Fulton B, Stewart R, Leach T

Gold mineralisation at Porgera is inferred to have been derived from a deep differentiated magmatic source which is capped by a series of (now tilted) inward dipping sills and stocks, which comprise the Porgera Intrusive Complex. An arc normal transfer structure provides a conduit, at the intersection with an arc parallel structure, into which basic magma derived from the deep melting of mantle material has been emplaced. Two phases of mineralisation display an association with late stage feldspar porphyry intrusives. Stage I carbonate-base metal-style gold mineralisation occurs as early quartz-sericite, then massive sulphide and late zoned Mn-Fe-Mg-Ca carbonate vein/breccias. Magmatic fluids derived from the deep magma source, are interpreted to have migrated along the margin of a feeder stock to the sills, and south to Waruwari. Stage II epithermal Au-Ag quartz-style gold mineralisation occurs as early fluidised breccias and carbonate veining, followed by zoned quartz-roscoelite-carbonate-gold vein/breccias, and late carbonate and/or sulphate open space infill. Magmatic fluids are interpreted to have utilised the same plumbing system as the late stage feldspar porphyry intrusive, and then migrated into the Roamane Fault which was dilated by; dextral rotation on elements of the transfer structure, normal faulting, and refraction around the competent footwall hornblende diorite. Bonanza gold is localised in a jog in the Roamane Fault, hangingwall splits and at intersections with cross structures. Bulk low grade Stage I gold has been deposited by the mixing of magmatic fluids with cool gas condensate waters, whereas high grade Stage II gold mineralisation resulted from the rapid quenching of mineralised magmatic fluids by oxygenated groundwaters.

Jan 1, 1995

By P Pelletier, J Tessier, C Duchesne

This paper summarises research into the study of the control of flotation processes based on froth images. A review of the froth flotation operation background and the relevance and role of the froth phase are presented. The use of numerical image analysis techniques for the extraction of significant patterns from industrial flotation froths is discussed. First, the froth was analysed by the use of the multivariate image analysis (MIA) method to extract the spectral variation contained in a RBG image. The partial least squares (PLS) method was applied to develop an empirical model for the prediction of froth grade. The results of this application are illustrated using an industrial case study. Second, the froth was also analysed by grey-level co-occurrence matrix (GLCM) and wavelet transform analysis (WTA) to extract features related more to morphological aspects. Since there is useful information hidden in froth texture, these methods are used as texture descriptor to classify different types of froths. They also provide qualitative information on the changes in the visual appearance of the froth. The pros and the cons of those methods are highlighted. Third, a control strategy based on a froth structure indicator was developed and implemented on an industrial zinc flotation circuit. The feedback controller uses the reagent flow-rate in order to maintain the froth structure at its set point. Process improvements obtained from the implemented control strategy are highlighted. Finally, the feasibility of implementing a hybrid control strategy consisting in a froth structure supervision controller based on the froth concentrate grade estimated by MIA and recovery inferred by image analysis is discussed.

Jan 1, 2005

By N Davies, M J. Coward, P L. Hissey

Mount Isa Mines has four mining operations in Mt Isa with the X41 and Enterprise Mines producing copper and the Lead Mine and George Fisher producing lead zinc and silver. Each stream contributes ore to their respective concentrator at a feed rate and therefore metal ratio set out by the monthly schedule. Mine Planning and scheduling lead to a sales and operating plan (S&OP) and revenue projections which ultimately derives actual revenue /tonne and therefore cost/tonne. At Mount Isa, both the copper and lead/zinc streams produce ore from relatively new operations to be blended with material from more mature operations. It is critical to accurately predict the metal contribution from each operation in order to gauge the relative performance of each mine. Development mining ore contributions are estimated and reconciled, as are stope and bench sources. Performance is continually measured and assessed during extraction and grade adjustments are made to account for underbreak, overbreak and design modifications. It is critical to not understate or overstate the contribution from one operation relative to the other as this can produce a false picture of operational performance. Identifying process improvements are key to improving the business overall. Ore from the lead stream passes 17 measurement stations and two midstream reconciliation points before delivery to the heavy media plant (HMP), where the metallurgical circuit begins. From this point two concentrates are produced. A zinc concentrate for treatment off site and a lead concentrate for further on site processing. The lead smelter takes 100 per cent of Isa concentrates as well as a contribution from BHP-BillitonÆs Cannington Mine.

Jan 1, 2002

At the Nikkel og Olivin nickel mine near Narvik, Norway, Outokumpu has been the operator since 1993. The mine was opened in 1989 and in 1992 Outokumpu commenced operations to secure concentrate deliveries to Harjavalta's nickel smelter in Finland. Annual production is about 740 000 tonnes of nickel ore grading 0.5 per cent Ni, about 25 000 tonnes of nickel concentrate and about 2800 tonnes of nickel metal. All production comes from underground operations which makes Nikkel og Olivin AS perhaps the lowest grade underground nickel mine in the world today. Production is currently from one of two orebodies, which is known as the Western orebody. The Eastern orebody was worked out by 1995. During Outokumpu's operational period the Western orebody has been delineated and taken to production. The underground exploration and definition drilling involved about 15 000 in of diamond drilling, which was carried out during a nine-month period. Following this a feasibility study was undertaken and production commenced. Improvements were made to the mining methods. Previously the mine utilised open pit equipment underground and this resulted in an enormous amount of additional tunnelling. Grade control and ore delineation were previously based on sparse diamond drilling and all geological information was processed manually. The improvements included the use of underground sludge drilling to increase the amount of geological information, the of a new computer system for grade control and mine planning, new automated underground longhole drilling equipment and the of underground mining equipment which reduced the size of the drives. These changes produced a marked increase in the efficiency of the underground Mine.

Jan 1, 1996

By A Suokas

Boliden Tara Mines Ltd, located in County Meath Ireland, produce in excess of 2.5 million tonnes per annum of ore from the underground resource located 40 miles north west of Dublin. The zinc-lead ore is mined using long hole open stoping techniques, with ore treated on site. The operation is continually searching for new ways to improve productivities at the mine, and have employed a detailed data acquisition and reporting system on site to provide feedback around performance. One area where both Boliden Tara Mines Ltd and Orica Mining Services believed improvements could be made was in the application of bulk emulsion technology through an Orica supplied but Tara operated Maxipump Delivery System for all production and development blasting at the mine. Both parties committed to the evaluation of this technology at the mine, however the capital cost and technical and economic changes meant the project needed to be diligently investigated and any improvements documented. The first stage of this project was for Orica Mining Services personnel to visit the operation, and conduct a detailed analysis of the operationÆs performance over the past 12 months. The next step in moving forward was then to commission and utilise the customer operated emulsion system at the mine. This was then followed with the collation and analysis of data from the demonstration period to examine and document the benefits of the system. This paper is a summary of the observations made during the site inspection and the data analysed to date, and has been used in determining operational and financial improvements in the comparison between a Maxipump Emulsion Service and the current ANFO loading systems.

Jan 1, 2005

The development of Mount Isa Mines Limited power supply is traced through the history of the mine operations. As would be expected, growth of the power supply system follows closely the increase in mine output, although it will be seen that total kWh. produced per ton milled shows a considerable reduction in later years when the mine output showed a more rapid rate of increase. That this reduction is not more marked is possibly due to the increased community and Shire Council power usage per head of population.INTRODUCTIONThe geographical position of Mount lsa, far from any large regional power supply Authority, dictated the policy that the Company be responsible for the production and suppiy of all power required for the plant operation. The Company also, in November 1937, accepted responsibility for the supply of a part of the power requirements of the township of Mount Isa. The history of power supply to the Mine may be divided into several phases.1. The supply Of lighting and power during the first plant construction period 1929-1931.2. The construction of the first section of the Mines Power Station, comprising Nos. 1 and 2 turbo alternators and boilers.3. The addition of No. 3 turbo alternator and boiler.4. The addition of No. 4 turbo alternator and boiler.5. The addition of No. 5 boiler.6. The addition of a. 2 turbo blowers for air supply to the Copper Smelter converters; b. 1 turbo blower for air supply to the L.ead Smelter; c. 2 turbo compressors for compressed air supply to the Mine and surface plant.

Jan 1, 1961

A new lead refinery with a. capacity of 230,000 tons per year com-menced operation at*Port'Plsie in October, 1959. This plant' superseded the refinery which had operated from 1933 with the advent of thecontinuous lead refining process. The incorporation of new equipment following local metallurgical developments, together with the overseas demand for lead of extremely low antimony content, created difficulties in operating the original plant. The new refinery project was under-taken to cover this disability and to gain the full advantage of the new processes.Desilverising and softening are carried out in units identical in size to those used previously. Metallic'zinc is now recovered from the entire output of desilverised bullion by vacuum distillation. Final refining is then carried out by batch'treatinent with caustic soda yield-ing lead of purity previously unattainable at Port Pirie.These two processes have replaced continuous dezincing by oxidation, a high temperature process which caused large quantities of lead and antimony to be recirculated. As the final stage is a .batch process the product composition can be.checked before casting. Individual batches can be adjusted to produce special alloys to,consumer's specification.Improved casting equipment has allowed the quantity production of pigs of good physical characteristics either as 56 lb bars or 2000 lb pigs. This, together with the high purity of the lead, has assured the B.H.A.S. position in world markets.Automatic control systems have been extensively employed particularly on the vacuum dezincing unit.The anticipated financial benefits have been achieved mainly by a reduction in the tonnage of recirculated materials, a smaller labour force, and reduced maintenance requirements.

Jan 1, 1963

By A McRae

Much of western New South Wales is characterised by an extensive regolith formed during more than 60 million years of exposure, weathering and erosion. This cover includes intensely weathered in situ regolith and superimposed transported materials of variable thickness, commonly in complex palaeochannel systems. Mineral exploration in this region has been considerably hampered by the cover, which can complicate or maskgeochemical anomalies and also obscure geophysical signatures. A detailed multi-disciplinary study of part of this region, centred on the Cobar-Girilambone area has demonstrated a methodology for exploring through this regolith. The approach involves regolith-landform mapping to establish the main landscape and palaeolandscape elements and to determine the nature and spatial occurrence of different regolith materials. By combining knowledge of the surface distribution of different regolith-landform units with available 3D information on the regolith and geophysical data it is possible to construct simplified derivative maps or exploration ægoÆ maps, which can be used to advise appropriate exploration strategies or help interpret acquired exploration data. This study has also established the major regolith controls on geochemical dispersion and determined key background element associations. These regolith-related element associations can result in highly variable background levels for many trace elements and need to be understood and factored into the analysis of geochemical data for different regolith sampling media. With better knowledge of the regolith it is possible to select the most appropriate exploration techniques and sampling media for a given area, as well as apply appropriate normalisation procedures to the acquired data. Exploration success can be greatly improved by using many existing techniques in æregolith smartÆways.

Jan 1, 2004

By Lawrence L. J

The Australian Broken Hill Consols Mine, situated some 600 yd east of the main Broken Hill line of lode, is noted for its rich ores of silver. In contrast to the vast conformable orebodies of the Broken Hill field, the Consols lode occupies a narrow fissure dipping to the south west at angles increasing from 240 through to vertical and transgressing the strike of the metamorphosed country rock at an oblique angle. This feature, together with the abundance of calcite and siderite and the virtual absence of silicate minerals in the gangue, has led to its classification as an orebody of the Thackeringa type (King, 1953). Recorded production during the period 1890 to 1903 is given as 845,000 oz of silver and 20 tons of lead.The unusually rich silver values of the Consols lode were concentrated at the intersection of the fissure with beds of amphibolite, whereas in the adjacent schists and gneisses the lode became markedly impoverished. From the surface to a depth of some 120 ft extensive surface oxidation had occurred, resulting in the breakdown of siderite and its replacement by limonite and associated manganese oxides.Silver halides, dyscrasite, acanthite and partly oxidised tetrahedrite were the main silver minerals in this zone. With increasing depth the lode material gradually reverted to minerals representative of the hypogene zone.The only previous work specifically on the mineralogy of the Consols lode is that by Smith (1922), one time manager of the mine. His zeal as a mineral collector resulted in much valuable information being available on the distribution of the minerals. More recently, Garretty (1943) noted the...

Jan 1, 1962

The role of the mine geologist and the exploration geologist have diverged considerably in the last two decades. The principal focus of the mine geologist now is on ore resource management rather than ore resource discovery.

Jan 1, 1997

By Griffin P

The project is the result of a European Commission supported collaboration between Surpac Software International, the Technical University of Berlin, and the industrial partners Exploration and Bergbau GmbH (E+B) and Taylor Woodrow. The object

Jan 1, 1998

By Hongzhen Yu, Xiaoping Ma, Jiansheng Qian

The paper introduces the design of an Intelligent Managerial Attendance Machine (IMAM) for coal mines. In the system, data communication is carried by Optical fiber communication, including industrial control computer on the ground and the car

Jan 1, 1998

By Bhattacharyya A. K

A strata parameter is introduced to include the deformation characteristics of the undermined strata in the prediction of subsidence movement. By using the strata parameter and mining factors as parameters, a nomogram for predicting the maximu

Jan 1, 1994

By Peng SS

This paper presents a number of mathematical models for predicting the different phases of the complete surface subsidence process associated with underground longwall mining. A computer program developed based on the mathematical models is briefly introduced.

Jan 1, 1992