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By P Craig, A Crosky, P C. Hagan, E Elias, B Hebblewhite, S Saydam, D Vandermaat

"Premature failure of rock bolts has been recorded at twelve underground coalmines over the past 15 years in Australia. Over the last four years, UNSW Australia has been conducting an Australian Research Council (ARC) and Industry funded linkage research project into premature failure of rock bolts. The extent of the problem was investigated by underground surveys of mines with known prematurely failed bolts using visual mapping, non-destructive load and ultrasound testing. A major component of this project was to define the environmental factors responsible for corrosion of rock bolts. The environment to which a rock bolt is exposed will include groundwater chemistry, the mineralogy of the strata, atmosphere within the drill hole and even microbial activity. This paper focuses on the groundwater survey and analysis findings to date along with in-hole bolt corrosion coupons installed into field sites. Corrosivity classification systems exist for general corrosion but do not apply to the rock bolt stress corrosion cracking (SCC) problem found in Australian underground coal. The method of in situ investigations is leading towards the building of a corrosivity classification model to assist mines in prediction of premature rock bolt failure. An ‘in-hole bolt corrosion coupon’ development by the project may have multiple benefits of: helping quantify any corrosivity classification system providing an in situ ground support corrosion monitoring tool for testing possible corrosion protection solutions.CITATION:Craig, P, Saydam, S, Hagan, P C, Hebblewhite, B, Vandermaat, D, Crosky, A and Elias, E, 2014. An investigation of the corrosive impact of groundwater on rock bolts in underground coalmines, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference, pp 277–286 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Nov 5, 2014

By P McCarthy

"This paper is based on 30 years of involvement in feasibility studies as a participant, study manager and the leader of a firm that provides study components and overall study management. The following topics are discussed:the purpose of feasibility studiesaligning the goals of the study team with those of the ownerthe difference between optimisation and designhow the types and levels of studies affect the organisation of the studythe relative merits of various management structures and contractual arrangementssetting scopes of work and tendering the work outthe selection of a study manager and the study management teamcommunications within the study team and externallythe project management trianglemanaging scope changes and maintaining flexibility to respond to study findingsprogress paymentsmanaging a study crisisinnovation, risk aversion and bankabilityreporting the resultsthe dangers and benefits of value engineering.CITATION:McCarthy, P, 2016. Making studies work – organisation, communication and management, in Proceedings Project Evaluation 2016, pp 20–30 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 8, 2016

By D Laurence

Australians are at the forefront of exporting their mining expertise in a number of areas. Minerals education is just one example. The growing economies of Southeast Asia host some of the most prospective mineral fields in the world. Laos for example, hosts the world class Sepon and Phu Kham copper-gold deposits. The Philippines has the fifth largest global mineral resource inventory. These and other countries in the region lack the mining engineers, geologists and metallurgists required by international mining companies to ensure their operations are sustainable. This paper describes the author’s experience in working with mining schools in Southeast Asia and specifically the Philippines, Cambodia, Laos, Thailand and Vietnam. Various strategies to ensure sustainability and lessons learnt are presented.

Nov 22, 2011

By H Hoogvliet

The Goondicum Crater industrial minerals deposit is located about 30 km east of Monto, Central Queensland, Australia. Early exploration programs in the 1990s found alluvial ilmenite along the banks of the Burnett River. This mineralisation was traced upstream to the Goondicum Crater. The Goondicum Crater is a topographic feature centred on a roughly circular 6 km diameter layered gabbro complex. Significant ilmenite, apatite, titano-magnetite and feldspar mineralisation are present in a weathered horizon up to 25 m thick. After several drilling campaigns in the Crater and subsequent feasibility studies, the project was developed by Monto Minerals Ltd, an ASX listed company, in 2007. However, the project never achieved production performance expectations and ran out of commissioning funds. The company subsequently went into voluntary administration in August 2008.In 2009, the RMM Capital group, of Brisbane, took control of Monto Resources Pty Ltd, and renamed the company Belridge Enterprises Pty Ltd (Belridge). Belridge commissioned a redevelopment study aimed at recommencing mining and processing operations. As part of the redevelopment study the authors planned a drilling campaign, managed a quality control program and developed a block model. This paper describes the drilling program, analytical procedures, quality control procedures and the preparation of the block model.The block model for the resource estimate was created using 1 m high blocks, wireframes defining the main material types, and 2.5 m thick horizontal search ellipsoids with a radial pattern. The deposit was ‘flattened’ prior to modelling. To assist with the economic evaluation of the project, each block in the model was assigned a net dollar value based on economic parameters provided by Belridge, including anticipated revenues and costs. This modelling technique allowed for efficient investigation of various scenarios and was used extensively in the development and optimisation of the project’s financial model. At a zero net value per block, comparable to a break-even cut-off grade of four per cent ilmenite equivalent, the Indicated plus Measured resource is estimated at 51 Mt, averaging 4.1 per cent ilmenite, 1.9 per cent apatite and 2.5 per cent titano-magnetite.

Oct 5, 2011

By R C. Cox

The Brukunga pyrite mine was operated from 1955 to 1972 to supply feedstock for sulfuric acid production in the South Australian fertilizer industry. Iron sulfide ore, mined by Nairne Pyrite Ltd, was finely crushed and concentrated onsite with the concentrates being sent by road and rail to Port Adelaide for roasting. Waste rock was dumped at two locations on the western side of Dawesley Creek and the tailings pumped to a valley-fill storage facility on the eastern side. Production of 1.5 Mt concentrate resulted in 3.5 Mt tailings and 8 Mt waste rock. The site has been administered by the South Australian Government since August 1977 and a lime treatment plant has been operated on the site since September 1980. Environmental issues arising from these operations included: diversion of Dawesley Creek to accommodate the waste rock dumps; dumping of low-grade sulfidic ore in waste rock dumps at the angle of repose immediately adjacent to Dawesley Creek; exposed fresh sulfide mineralisation in the quarry floor; tailings storage facility dam wall constructed by upstream up-lift using tailings and waste rock; an acid water pond sited on the tailings; and pollution of natural drainage. As a result, the minesite rapidly became a source of acid drainage and potential contaminants (sulfate, Al, Fe, Mn, Cd, Zn, and Ni). Various Government bodies have been responsible for considerable effort and expenditure in reducing the flow of acid seepage and contaminants into Dawesley Creek. Presently an estimated 60 per cent of seepage from the waste rock dumps, tailings storage facility and quarry is collected and neutralised prior to discharge into the creek. Tailings have been covered with waste rock, biosolids, neutralisation sludge and soil and planted with grasses, shrubs and trees to reduce rainfall infiltration. Monitoring of water flows, water quality and riparian ecosystems is on-going. Consultants have been engaged to develop cost-effective remediation techniques and a five-member Brukunga Mine Site Remediation Board was appointed to oversee remediation of the site and liaise with the community. Construction has commenced on the diversion of Dawesley Creek, and plans are being developed for the relocation of waste rock back to the quarry benches and upgrading of the neutralisation plant. The paper examines operations, environmental monitoring, remediation, research and community involvement with respect to current best practice.

Jan 1, 2003

By M Foster

The new environmental legislation of 1986 was left incomplete and to date remains so. The 'missing' process by which environmental consideration should be applied was never embodied in law and has predisposition to a wide interpretation. The Resource Statutes which govern land use and development place demands on the environmental process without that definition. The Resource Statutes are themselves under review by Government. There is a new Government Department of Conservation. It is still in its early days and facing a challenge to compose its role as a steward over large tracts of land holding significant marketable resources, animal, vegetable, mineral, and abstract. It has also taken over numerous consent and advocacy roles in legislation beyond its own empowering Act. Enter the mining company, anxious if not able to get an easy passage for consents to prospect and mine, then at least to have a clear path to tread to get there, within a fixed time period. Whichever options appear available to process environmental approvals, public participation is that being favoured most by the regulatory bodies. Where a public notification of consent applications is mandatory, public participation should lead to the fastest track available.

Jan 1, 1988

CHAPTER 1 - GENERALIn the introduction to this chapter a general account is given of the growth of the mining industry in Western Australia from J88G, when the output of gold for the whole State was only £1148, to 1908, when: the output had risen to £6,999,885. In 1903 the output reached £8,770,719.It is quite evident that the discovery of gold in Western Australia was the means of opening up the road to broader industrial expansion, and it is doubted if any other portion of the British Empire more clearly exemplifies the nation-building forces of metalliferous mining than this State.The chapter includes an account of the following situation and history of the field.CHAPTER 2 - GEOLOGYIn this chapter the classification of the rocks of Kalgoorlie, but particularly those on the Golden Mile, is considered. Each rock is described in detail, and microphotos are shown to indicate the most important features in each type. As far as the Golden Mile is concerned, it is held that, notwithstanding the general chemical and more or less dynamical metamorphism which the rocks have suffered, it is possible to divide them into six groups...

Jan 1, 1912

By J E. Wheeler, S B. Valine, L G. Albuquerque

It has long been known that closed circuit grinding with a classifier improves grinding efficiency, reduces unit specific power consumption, and reduces over grinding. The classification device removes material from the circuit that has reached the desired size and returns coarse material back to the mill for further grinding. The efficiency of the classifier is an important factor in the overall performance of a grinding circuit. The classifier affects the capacity of the grinding circuit and the metallurgical performance of downstream operations. A review of historical research and modern case studies is used to demonstrate the benefits of high frequency screens for classification in grinding circuits.CITATION:Valine, S B, Wheeler, J E and Albuquerque, L G, 2012. Applications of fine screens in grinding circuits, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 389-394 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

Past arguments advocating reverse circulation sampling against blasthole sampling are reviewed to present the debate under a different light. The advantages and disadvantages of each drilling method are compared, and the choice is presented as an informed trade-off between them.

Mar 1, 2010

By Morsky P, Kalapudas R, Natunen H, Virtanen M

The development of autogenous grinding modification in Outokumpu, known with the name 'Outogenius Comminution', was 'reversed'. At first the metallurgists studied and tested tens of years autogenous grinding in detail in full scale circuits at the concentrators of the company. After the final solution already had been found, also a pilot plant was built and now finally, research work is under way to develop a special laboratory method for testing the suitability of ores for 'Outogenius Comminution'.

Jan 1, 1993

By D Bertoldi, C Haines

"The Waihi Gold Mine (WGM) operated by OceanaGold New Zealand Limited is a wholly owned subsidiary of the OceanaGold Corporation of Australia. Traditionally WGM has stockpiled and processed separate campaigns of open pit and underground ore. The ore is processed via a conventional semi-autonomous grinding (SAG) / ball circuit (SABC). The low aspect SAG mill operates in a closed circuit with two 20" cyclones, whilst the ball mill is also a closed circuit with a 10" cyclone cluster. A major wall movement in April 2015 ceased open pit operations indefinitely, 18 months ahead of the mining plan. This immediately reduced the forecast mill tonnage leaving two options: begin campaign milling or change the operating strategy and target lower throughput. Additional cost pressures necessitated improved milling cost efficiency. The immediate ore restriction limited processing alternatives to within the existing major infrastructure. Available comminution circuit survey data laid the foundation for developing a comminution model using the JKSimMet™ software package (version 6, created by KJTech). A number of flow sheet variants were then evaluated based on predicted throughput and efficiency. The comminution models suggested opportunities for improved efficiency lay in reducing throughput and increasing utilisation rather than on/off campaign milling under the existing operating philosophy. A series of process alterations followed, delivering new cost efficiencies that maintained the current $/t processing cost. This paper aims to review the change in circuit performance and examine the decisions and challenges faced following the transition from a high tonnage SABC circuit to lower tonnage SABC circuit.Citation:Haines, C and Bertoldi, D, 2016. The Transition from Semi-autogenous to Autogenous Milling at Waihi Gold, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 303–312 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By S S. Kanchibotla, I Brunton

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

Jan 1, 2001

By P Williams

The Sunrise deposit is one of AustraliaÆs largest and most profitable gold deposits. It has consistently and spectacularly outperformed every resource model created. Currently over the life of the Sunrise pit there has been a 50 per cent under estimation of ounces mined. Without a solid basis for predicting the tonnes and grade or the spatial location of mineralisation, mine planning becomes problematic. Recently, through a better understanding of the mineralising processes the reconciliation of the resource model has improved to be in the order of ten per cent under on ounces mined. This paper will describe how the mine geologists at Placer Granny Smith have implemented the changes required to improve the resource model. Work began with the development of a three-dimensional lithological and structural model based on historical drilling and pit mapping. Continual updating of the geological model with grade control logging, assays and in pit face mapping, now allows for the on-going improvement of the resource model and the planning of mine development drilling.

Jan 1, 2000

By P Minkkinen, J Lohilahti, T Korpela, B McPherson

Concentrator plants intake the ore from the mine and produce concentrates by extracting valuable minerals in a succession of process steps. Controlling the extraction process and detecting changes in the process requires updated information on a minute basis. Moreover, due to economical reasons, one must also collect metallurgical samples on a daily basis for monthly reporting.In this paper, we present how slurry samplers were installed in a Cu-Ni flotation plant to accomplish the aforementioned tasks. An on-stream elemental analyser at the plant is used for flotation process control by taking samples from selected process streams. Two process streams, the flotation feed and tail, are also equipped with metallurgical samplers. The metallurgical samplers were designed to have low head loss, be robust and easy to maintain and to collect slurry samples in a reliable way for the metallurgical accounting.Samples were collected by different sampler types and we discuss the uncertainty arising from sampling in the assays. Variographic analysis was carried out on the process data in order to find periodic components in the process, and estimate the correct number of shift sample increments and measurement error components. The metallurgical samplers were proven to be reliable devices with zero downtime and no sanding issues in the main process flows. In addition, we show that the tail measurement is the most important one for the plant recovery calculation, which emphasises the importance of the sampling accuracy in the tail stream.CITATION:Lohilahti, J, Korpela, T, Minkkinen, P and McPherson, B, 2014. Analysis of slurry sampling arrangements at a froth flotation plant, in Proceedings Sampling 2014 , pp 91–98 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

The South American mining community leads the world in recognition and adoption of the latest grinding mill relining technologies. Clearly this region has recognised the benefits of improved relining performance as a defence against the Global Economic Crisis. Five of the six RUSSELL TWIN 8 Mill Relining Systems, ordered to date, are either operating or being manufactured for South American mine sites. The sixth is for Sino IronÆs Cape Preston Project in Western Australia. This paradigm shift, towards very short relining times, aims at displacing mill relining activities from the critical path of concentrator maintenance shutdown schedules. The first uses of the RUSSELL TWIN 8 Mill Relining System have seen some of the highest semi-autogenous grinding (SAG) mill new liner placement rates ever observed by Russell Mineral Equipment (RME), as would be expected with two, independent Machines working simultaneously in the one mill. The liner replacement rate, averaged over the whole reline is good (27 per cent improvement over single Machine System in the same mill) but short of full potential. This modest result can be attributed to reline crews unfamiliarity with RUSSELL TWIN 8 System operation. This paper compares a sample of conventional (single machine) RME Mill Relining System performance data with one ædouble headÆ mill liner handler by others. Early performance of EscondidaÆs new RUSSELL TWIN 8 System performance is then compared with recent single machine data from Escondida, immediately prior to RUSSELL TWIN 8 commissioning. RME and Escondida look to constantly improving RUSSELL TWIN 8 System performance as full operational familiarity is achieved. The preparation of this paper revealed a need to develop a global industry standard for mill relining data collection. A web based platform to develop data collection templates is also discussed in Appendix 1.

Jan 1, 2009

The Managalase area is remote and little visited by geologists or prospectors. Yet it holds the key to the tectonics and petrology of this part of Papua. The eastern Managalase plateau (M, Figure 1) lies between the Hydrographers andesite volcano (H) and Sesara shoshonite volcano (S) to the south of Popondetta on the Papua Peninsular. It contains over 30 small volcanic centres in an area of only 400 km2 . To the south and west lies the basic-utrabasic belt (B-UB) of the Morobe arc. This is the leading edge of oceanic plate obducted over the Owen Stanley Metamorphics during the lower Eocene time. To the east and southeast lies the Cape Vogel geosyncline where the western end of the Woodlark basin spreading centre enters mainland Papua. The extension of the spreading centre as a suture might pass as far as the southern margin of the Musa Coastal plain. A new pattern of plate tectonic motions has been determined by the global positioning system and the southern margin of the Woodlark plate has been redefined (Tregoning et al, 1998; Taylor, Goodliffe and Martinez, et al, 1999). The Managalase plateau is margined by two inferred faults. These outline a cusp protruding from the main basic-ultrabasic belt where these rocks are near the surface. The westerly arm of the cusp passes through the centres of the Hydrographers and Mount Lamington andesitic volcanoes. Mount Lamington overlies Quaternary alluvium and underlying Tertiary sediments (Arculus et al, 1983) but members of the basic-ultrabasic belt crop out on the southern flanks. The easterly arm of the cusp is an inferred shear zone (and ? fault) connecting up with the terminus of the suture on the Musa coastal plain. Movements on the two faults forming the cusp are thought to have produced the conjugate N-S, E-W faults on the plateau (Ruxton, 1966). To the east, and isolated, are the two large andesitic stratovolcanoes of Mounts Victory (V) and Trafalgar (T) which together form Cape Nelson. Mount Victory was last active in the 1890s. The Waiowa shoshonitic volcano explosion centres (W), last active in 1943 - 1944, lie near the suture adjacent to the actively rising Goropu mountains. Extension in these mountains is clearly demonstrated by the soil profiles being skeletal along a bounding fault and ageing uphill. The incision of small parallel ravines also dig deeper further upslope from the fault. To the south-east of Mount Suckling (K) the Dayman Dome is also an expanding mass. The Owen Stanley fault is parallel, and located to the south of the suture. The Mesozoic metamorphics form the backbone of the Papuan Peninsula. The intramontane Musa Trough is thought to date from the mid-Tertiary. At the eastern end of the trough Pleistocene and Recent ultrabasic breccias and alkali basalt crop out (Green, 1961).

Jan 1, 1999

By A Van Kersen, J Hodson

Waihi Gold Mining Co Ltd [WGM], operated by Normandy Mining, has been internationally recognised for its achievements in environmental management at the Martha Mine at Waihi. In a proactive approach to dealing with community concerns regarding blast vibrations on the North Wall cutback, trials were performed using the Cardox System [Cardox], to determine feasibility of achieving economic fragmentation of andesite overburden whilst bettering management levels of 5 mm/s peak particle velocity. Cardox is a non-explosive pressure breaking system which uses high pressure CO2, Results against conventional Ammonium Nitrate/Fuel Oil [ANFO] using a variety of delays showed that conventional blasting techniques could produce marginal fragmentation within the management levels with occasional excursions, whereas Cardox produced the required fragmentation while not registering on the vibration monitoring equipment. Fragmentation to enable normal excavation by a Hitachi EXII00 hydraulic excavator was achieved with a yield of 16m3 per round. The trails indicated that fragmentation with Cardox at the yields required of over 18m3 per round was possible with further product development. The trial demonstrated that non-explosive pressure breaking is feasible and its application warranted where environmental concerns affect the cost-benefit economics of production blasting in sensitive areas.

Jan 1, 2001

By B Ganesia, H Sahupala

PT Freeport Indonesia is a copper-gold mine operation located in West Papua, Indonesia about 3500 km east of Jakarta. Current ore production is about 270 000 tpd, of which 30 000 tpd comes from underground. In the future, the production from underground will be gradually increased to reach a maximum of 115 000 tpd, as the Grasberg open pit production decreases. The current and future challenge for PT Freeport Indonesia is to fill the quota of underground miners, as Indonesia does not have a long culture of underground work. At present, there are only three active underground mines in Indonesia. The lack of underground skilled labour incited the company to develop its own skilled workforce. In the mean time, to overcome the shortage of personnel, the underground management had to find a way to improve the productivity. Since 21 May 1998, PT Freeport Indonesia Underground Mine has operated with the new roster of two rotating shifts a day, 11 hours per shift. The previous schedule consisted of three nine-hour shifts per day, six days a week, for a total of 26 working days in a month. This change was intended to increase the productivity of the miners. With the previous roster, studies determined that the effective working time was only seven hours per shift. The new roster produces an improvement of effective working hours to about nine hours per shift. As a result, total production has increased by 33 per cent and the utilisation of production equipment has increased by 16.5 per cent. This paper describes the background of the decision to change the work schedule, the study carried out to evaluate the benefits and drawbacks of the new shift roster, the challenges, and then compares the results for various parameters between the old schedule and the new one.

Jan 1, 2002

By J Benn, V Kuznetsov, G Timms, A Spain

Earthen covers are now widely used in the mining industry to control the generation rate and/or release rate of low quality drainage from piles of sulfidic minewastes. Covers are usually designed to reduce the water infiltration rate and in some cases may also reduce the oxygen flux to the underlying sulfides. Engineered covers have only been used since the 1980s, however, and there is very little field data on their performance in the longer term. This lack of information has implications for the degree of confidence that can be placed on the predictions of the environmental impacts of sulfidic minewastes, for the acceptance of close-out criteria by regulatory authorities and for the financial liability of the mining industry. Covers were placed on sulfidic waste rock dumps at the abandoned Rum Jungle uranium mine during 1984 - 1985. These covers were designed to reduce the water infiltration to less than five per cent of incident rainfall by both water shedding and storage-release mechanisms. Regular monitoring by the Australian Nuclear Science and Technology Organisation (ANSTO) demonstrated that the covers performed better than the design criterion for around ten years, but infiltration rates have subsequently increased. There is a 66 per cent probability that the infiltration rate now exceeds five per cent of incident rainfall. The cover on the largest pile, WhiteÆs heap, was sampled in pits dug at eight locations. Sampling was carried out at the end of the monsoonal wet season and again at the end of the ædryÆ season. This, together with laboratory testing, enabled cover performance to be assessed against five criteria: design, construction, cover material characteristics, physico-chemical characteristics and biological characteristics. We are of the opinion that the design of the cover was suitable to achieve the objectives of stability, water shedding, storage-release, and provision of a substrate for vegetation growth. Over most of the surface of the heap, the construction of the covers, drains and erosion prevention structures was in accordance with design specifications. However, several small and localised bare patches on the upper surface of WhiteÆs heap coincide with a reduced cover thickness, which is likely to have been due to poor construction in those patches. The construction of covers on minewastes is dependent on an adequate source of material meeting design specifications. From our limited examination, it appears that there was shortage of material for each of the three zones û a lower impervious clay layer, the moisture storage-release layer and the upper erosion-resistant layer for vegetative growth. An indication of this was that the upper layers in some areas were observed to be thinner than specified. We are of the opinion that this shortage of suitable material has been responsible for some of the changes observed ten years after emplacement. Physical and geotechnical testing indicated that the cover materials no longer meet the original specifications. In particular, the permeability at the 8 locations was found to be greater than specified, by up to several orders of magnitude. The higher permeability may explain the higher observed rainfall infiltration and moisture content of the waste rock. This increased permeability appears to be due to a combination of biological and physical processes û galleries formed by termites and ants and an extensive system of shrinkage/desiccation cracks formed by the development of a polygonal blocky structure involving the entire lower clay layer. The desiccation cracks may fill with coarser illuviated materials and form a conduit through which roots access the underlying waste rock. Measurements were made of oxygen flux into the heap as cover layers were excavated in the pits. They indicated that the full cover currently reduces the oxygen flux to 20 - 23 per cent of that into bare waste and that this reduction seems to be proportional to the cover thickness. It was also found that the oxygen flux into the cover is about four times higher at the end of the dry season than at the end of the wet season and that the difference is due primarily to the difference in moisture content of the cover. Recommendations are made for the design and construction of covers.

Jan 1, 2003

By P Klaric

Drive stability is critical in block/panel cave mining. The production levels of these mines are required to remain operational for the entire life-of-mine which can be in excess of 30 years. It is therefore necessary to produce high-quality drives to ensure sustainable mine productivity. In order to improve the quality of drives and pillars, this gold mine instigated a project to optimise their development blasting. The initial aim was to reduce the level of overbreak in development mining, which was averaging approximately 18 per cent. The benefits of controlling overbreak not only included an increase in the integrity of the drives but also a decrease in load and haul and ground support costs. Through focusing on the optimal blasting of the perimeter holes, overbreak was reduced to 4.5 per cent. The project’s focus then moved to drill and charge designs for development faces. In optimising these designs, it was anticipated that improvements in the development mining cycle would be achievable.CITATION:Klaric, P, 2015. Improving drive stability through efficient development blasting design and practices, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 327–332 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015