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Government established and financed the NZ Steel Investigating Co in 1960. Its investigations showed that a steel industry was feasible and desirable based uponNorth Island titanomagnetite ironsands, and charted a route for its establishment. The initial processing used post-1945 preheating and prereduction developments, but later innovative improvements created what was essentially a new New Zealand technology. Of the North Island titanomagnetite deposits: the small ones at Waipipi were best made available for export; those at Kawhia and Taharoa were too remote for the economic siting of a mill; that at Raglan proved too small; while at Waikato North Head three times the requirement of 50 million tons of concentrate were located in two sand areas averaging 18 per cent titanomagnetite. Economic studies showed that a South Auckland site would be ideal, close to New Zealand's biggest market. The mill site, on a basalt flow at Glenbrook, was located by a half-day's fieldwork - near both the Waikato North Head deposit, and a railhead for bringing in Waikato coal, etc, and taking out steel products.   This development was one of several since World War II which altered significantly the lives and homes of New Zealanders (others were natural gas, oil, geothermal power, epithermal gold, aluminium, opencastable lignite, etc). All had the essential ingredients of the highest government backing, direct or indirect government finance, and first-class New Zealand scientific and engineering skills (eg to create new technologies). Not one such project failed.

Jan 1, 1993

East Nelson and Marlborough, in the northeast of the South Island, contain a wide variety of metallic minerals, including gold, silver, copper, chromite, antimony and scheelite, but no sustained metallic mining industry has evolved. Gold was the most sought-after mineral during the first century of European settlement and numerous discoveries were made but these failed to live up to expectations. While traces of gold are widespread in east Nelson, including in quartz veins in Nelson City, no payable deposits were found. In Marlborough the probability of a gold discovery had initially seemed remote but all this changed with the finding of rich deposits in the bed of the Wakamarina River in 1864, which provided a much-needed boost to the provincial economy. However, the decline of gold mining in Marlborough began virtually as soon as it had commenced. Extensive floods in 1865 hastened the exodus of miners to the profitable new fields of the West Coast.

Jan 1, 1993

This paper has been prepared to challenge the thinking of new leaders entering the mining industry in two areas. First, what is the worldÆs perception of mining and what does this mean to those entering the industry? Second, what is the future of learning in the mining industry and how can the industry attract and retain the best people?Then in closing, how can mining companies turn these challenges into opportunities and specifically how is BHP Billiton meeting these challenges.

Jan 1, 2004

By Moxon N. T

A series of low shock energy water resistant emlulsion based explosives have been developed by combining inert materials, such as Perlite P500, into the formulation. The material handling, water resistance and explosive properties of these mixtures were determined as a function of inert additive type, density, charge diameter and emulsion base. Of the emulsion bases tested Emulite produced the best and most stable low density mixtures ranging in density from 0.8 to 1.35 g/cm3 producing velocity of detonations (unconfined) ranging from 3000 to 5500 nits. The mixtures could be detonated successfully at these densities at diameters as low as 25mm. Low shock mixtures formed by combining Emulite with Perlite P500 were successfully trailed at the Cadjebut zinc mine in Western Australia. The performance of the explosive, at three densities, was monitored using both continuous and point to point VOD techniques. The fragmentation produced by the blasts were compared by photographic analysis. During this trial the low shock emulsion mixtures were shown to be as effective as the currently used explosives (packaged emulsion) at a significantly reduced cost.

Jan 1, 1990

By C Simpson

In 2011 the forecasted world demand for iron ore continues to grow, and during this time Australia is looked upon as a reliable supplier of high quality ore. The expansion of the current Australian mines is unlikely to meet the forecast demand. New mines are therefore being actively explored for and when discovered, are quickly being developed into mines in order to meet the world’s hunger for steel.The Solomon Project area is a large new iron ore discovery, located in the central Hamersley Ranges of the Pilbara province in Western Australia. The first Fortescue exploration drill holes commenced on the project in 2007 and to date three billion tonnes (Bt) of iron ore have been defi ned within the project area. Fortescue is fast-tracking the development of the ‘Solomon Stage 1’ project, with rail and mine construction commencing during 2011, and ore to be railed to Fortescue’s existing shipping operations at Port Hedland commencing in 2012. At a designed production rate of 60 Mt/a, the Solomon operation will be one of the biggest production centres of iron ore in the Pilbara.Deposit types include the three dominant mineralisation styles of the Pilbara province, being bedded iron deposits (BID), Channel iron deposits (CID) and detrital iron deposits (DID). All these mineralisation styles are present in large concentrations within the Solomon project area, and when mined will produce two product streams. These are a single product of CID, and a combined product from a blend of BID and DID material.This paper defines the geological characteristics of the Solomon iron deposits as recognised through the exploration and development of this vast resource over the three years since exploration commenced on the project.

Jul 11, 2011

By J A. de la Torre, I R. Cerna, G K. Karadjian

The La Colorada underground mine in Zacatecas, Mexico is a mechanised cut-and-fill silver mine with a capacity of 1250 t/d. The project focused on training the mine’s experienced operators for a fleet of underground trucks, through the use of a training simulator. The project was run by the simulator vendor, in collaboration with the mine’s maintenance, safety and production management.A training program was created targeting maintenance reduction, productivity improvement and increased utilisation and availability. Operators were first acclimatised to the simulated environment, had their current performance baselined, then received targeted coaching, with the process repeated to reinforce learnings. Concurrently, production, maintenance, and safety data was being measured in the real world to measure skills transfer. Due to limited telemetry available from the equipment, many of the data points for the project were sourced from maintenance logs, and accounting data.Equipment failure data measured from unscheduled maintenance records showed an overall 6.5 per cent decrease in unscheduled maintenance following the implementation of the training program. This rate of reduction correlated with the significant decrease in equipment abuse behaviours measured within the simulator during this period. Additionally, overall maintenance activities showed a significant decrease, confirming that reductions in unscheduled maintenance were not achieved through increases in scheduled maintenance. The reduction in equipment damage also increased availability and utilisation of the truck fleet. This highlights that the maintenance improvements not only reduced maintenance costs, but made the fleet available for more production. Moreover, the variability of the operator performance was decreased by 86 per cent, and the difference between their best operator and the worst is less than the baseline; this showed a gap where machine abuse, productivity and cost are impacted directly.This project illustrated that even small-scale mining operations with an experienced operator workforce can achieve positive return on investment (ROI) from simulation-based training. It also highlights that in the absence of equipment telemetry, alternative data sources such as accounting data and maintenance logs can be used to quantify ROI from training.CITATION:Karadjian, G K, de la Torre, J A and Cerna, I R, 2017. Innovations in underground hard rock operator efficiency – through simulation-based training technologies and processes, in Proceedings 13th AusIMM Underground Operators’ Conference 2017, pp 53–58 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 16, 2017

By Y K. Leong

Iron ore tailings typically containing 40 to 50 per cent Fe can be beneficiated to iron ore products containing 54 to 60 per cent Fe. The impurities are comprised of clay, quartz, cristabolite and TiO2. Goethite and hematite are also present. At high concentrations of 55–60 wt% solids, the tailings displayed high yield stress and viscosity and cannot be pumped over long distances. Composite additives comprising of NaOH, phosphate-based additives and sodium metasilicate are found to reduce the viscosity and yield stress very significantly by a few orders of magnitude. The yield stress of 100 Pa can be reduced to almost zero. At this state, dilution of the tailings with its process water to 40 per cent solids causes the coarse and high-density iron ore particles to separate from the colloidal fractions located in the supernatant after a few minutes of sedimentation. Separation by decantation produces a sediment with an Fe content of 54 per cent from tailings with 47 per cent Fe. Another tailings sample with 48 per cent Fe was beneficiated to greater than 57 per cent Fe using NaOH-metasilicate-polyphosphate additives and employing an additional washing step. The use of other composite additives, NaOH and polyphosphates, increased beneficiated product Fe content to greater than 60 per cent from the same tailings. With the current iron ore spot price of more than US$180 per tonne, the cost of this treatment process even including a desalination step, if necessary, is relatively insignificant. This study has given tailings an economic value that should be exploited as soon as possible.

Nov 8, 2021

By P Dean, M Elmouttie

Radar monitors are now widely used in surface mining for monitoring slope deformations and predicting failure events. Their introduction has facilitated better management of risk associated with slope failure during mining and therefore protection of personnel and equipment. However, a wellrecognised problem is that radar monitors only measure deformation directed towards the detector (line-of-sight bias). This bias can lead to misinterpretation of deformation size, rate and failure mechanism, and therefore miscalculation of failure volume, which can significantly impact safety and productivity. This paper presents recently completed research and field trials into the feasibility of using low cost vision systems to mitigate this issue. It has been demonstrated that by integrating a computer vision system with an existing slope monitor, high precision tracking of features in the field of view can be performed. Combined with assumptions on the deformation characteristics, the true 3D deformation vector can be estimated. The applicability of using this technique for monitoring iron ore mine slopes is discussed.

Nov 8, 2021

By J Li, A McFarlane, J Yu, L L. Kuhar, R Meakin, N Chapman

"Column leach tests are used frequently to predict recoveries and reagent consumption for nickel laterite heap leaches. These column leaches often run for more than 100 days and therefore require long-term monitoring and data analysis to achieve the desired information. To minimise the cost and time required to obtain relevant information for nickel laterite heap leaching, we have developed a small-scale hydrogeometallurgical laboratory test to serve as a proxy to column, and by inference, heap leaching. In excess of 50 leach tests were conducted using four different small-scale proxy and column leach tests to compare predicted nickel recoveries, acid consumption and leach kinetics and to determine whether insight into potential scale-up effects can be obtained. The most promising proxy test was identified and we achieved a statistically significant recovery and acid consumption correlations between this test and the column leach tests. The accuracy of the small-scale tests was confirmed by column tests run on new laterite ores. This geometallurgical proxy could be of use for the population of block models and process selection during the mine planning phase or for optimisation and control during processing.CITATION:Li, J, Kuhar, L L, Meakin, R, Chapman, N, McFarlane, A and Yu, J, 2016. A Geometallurgical Proxy for Nickel Laterite Heap Leaching, in Proceedings The Third AusIMM International Geometallurgy Conference (GeoMet) 2016, pp 335–340 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Jun 15, 2016

By G Harbort, D Zoetbrood

"The Phu Kham copper-gold operation in the Laos People’s Democratic Republic (PDR) is owned and operated by Phu Bia Mining Limited. PanAust Limited holds a 90 per cent interest in Phu Bia Mining Limited, with the remaining ten per cent held by the Laos PDR Government.The original 12 Mt/a copper-gold concentrator at Phu Kham commenced production in April 2008. An incremental improvement program resulted in a number of circuit changes being incorporated by 2011, including conversion of conditioning tanks to flotation cells and the installation of a Jameson Cell cleaner scalper. In 2012 the Phu Kham Upgrade Project was commissioned to increase throughput to 18 Mt/a. In April, 2013 the Phu Kham Increased Recovery Project was commissioned to maximise performance by debottlenecking the plant IsaMill™ regrind and cleaning capacity.With the variable mineralogy of Phu Kham ore, control of the c concentrate regrind circuit is essential in terms of achieving effective liberation to maintain concentrator performance. On a routine basis laboratory regrind signature plot data is compared with daily surveys of the operational IsaMills™. More extensive surveys are also conducted to determine size distribution on a mineralogical basis and the effect of fine regrinding on pulp electrochemistry and flotation performance. This paper provides a review of the operating performance of the Phu Kham IsaMills™ with regard to power draw, feed and product size distribution, feed per cent solids, mineralogy and pulp electrochemistry. Operating performance is compared with the IsaMill™ signature plot test for predicting performance.Citation:Harbort, G, Zoetbrood, D and McNab, B, 2016. Operating Performance of the Phu Kham IsaMill™, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 39–50 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By T A. Helms, P Gottlieb, S E, R Bateman

In response to the ever-increasing challenges facing the modern gold mining industry and the need for improved gold recoveries within all processing streams, CSIRO has upgraded its latest automated mineralogical analysis system, QemSCAN (formerly QEM*SEM), with special purpose hardware that speeds up the location and measurement of precious metal-bearing phases. By rapidly scanning the surface of polished blocks, and accepting only fields that contain the minerals of interest, QemSCAN is able to find, map, and quantify target minerals in extreme detail. Phase identification and quantification is achieved by placing a grid of points over the target particle and collecting X-ray information at each analysis point. The resulting mineral maps provide the metallurgist with a complete textural description of all gold-bearing phases within the product measured, together with quantification of the gold phases in terms of their modal abundance, particle size, mineral associations, relative contributions to gold deportment and liberation characteristics. Examples are presented which illustrate how QemSCAN is able to find and quantify gold-bearing phases within low-grade ores from the Super Pit, Kalgoorlie. This work is the result of a collaborative project between Kalgoorlie Consolidated Gold Mines (KCGM), CSIRO Minerals, and the University of Queensland, and is on-going.

Jan 1, 2000

The Pasminco mine at Rosebery in north western Tasmania is a medium sized underground base and precious metals mine. In April 1992 a major wedge failure of approximately 5000 t occurred in the backs of a main access drive to the 18 level H Lens orebody. This collapse prevented access to 190 000 t of ore which had been scheduled for production in July - August 1992. At the time of the collapse, the mine was in a transition period between mining small pillar remnants of several other orebodies and developing to the new deeper J Lens orebody.The development at this orebody was behind schedule and it was necessary to find a cost-effective and timely alternative to a 75 m bypass drive around the fall area.A Lysaght- Fletcher multiplate steel arch was available on-site from a deferred surface road project and it was decided to use this arch to regain access through the fall area. Due to the danger of continued minor falls, the entire 18 m long, 3.95 m high x 4.5 m wide tunnel had to be assembled in the 4.7 m wide x 5 m high accesss drive and pushed into the fall area as a single unit.

Jan 1, 1993

By L Basnayaka, N Subasinghe, B Albijanic

"It has been recognised that the presence of clay minerals in ores adversely affect flotation performance. In this study, changes in rheological properties of the flotation pulps under normal operating conditions were studied with additions of bentonite and kaolinite clays at various concentrations. Zeta potential measurements were also carried out to determine the changes in surface charge due to adsorption of clay particles. The results showed that bentonite clay adversely affects floatability of pyrite while kaolinite clay had a lesser influence on flotation of pyrite. The addition of Ca2+ ions to the pulp containing bentonite modified the rheological characteristics and in turn improved the pyrite flotation. It was also observed Ca2+ ions suppressed the swelling properties of bentonite and altered surface charge properties of bentonite clay particles. It has been shown that the flow index affected the ultimate recovery and it may provide a means to monitor flotation performance in routine plant operations.Citation:Basnayaka, L, Subasinghe, N and Albijanic, B, 2016. Effect of Clay Rheology on Flotation of a Refractory Gold Ore, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 77–84 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By D Andrew, G Stanway, P Mahoney, C Griebel

The iron ore mining industry is currently going through an adjustment from high to more moderate growth as China’s economy transitions from capital-intensive investment to a more services-oriented economy. We are now witnessing a renewed focus on productivity improvements and cost savings as planned expansions are completed. Despite the scale and importance that the mining industry plays in the global economy, innovation literature is generally more targeted at faster-moving industries with shorter innovation timeframes and lower capital requirements. To fill this gap, VCI set out to understand the state of innovation in the mining industry in 2014. This State of Play report aims to give an objective appraisal of the strengths and weaknesses of innovation in mining. The report has three sections covering both the structure and delivery of innovation in mining:Ecosystem – focused on understanding how the iron ore mining innovation ecosystem system works, including the roles of large and small miners, service companies, researchers and governments. Our recommendations focus on what is required for the system to work well and improve the level and quality of innovation in the industry.Strategy – how do companies define their innovation strategy in relation to their corporate strategy? How are these related to prevailing global and industry trends? How do they communicate this with their business? How successful are they? These are among the questions that this section attempts to answer. Our recommendations are pitched at the executive leadership of iron ore mining and service companies.Delivery – focused on how companies develop and deliver innovation, looking at the success of different structural options, leadership and culture, partnerships and the best approaches to change. Recommendations are aimed at improving outcomes within the iron ore mining value chain, including the role that suppliers play.CITATION:Stanway, G, Mahoney, P, Andrew, D and Griebel, C, 2015. Understanding the state of innovation in the iron ore industry, in Proceedings Iron Ore 2015, pp 631–646 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

Throughout the Kalgoorlie Field the dominant factors influencing all planned exploratory work are: firstly, the general geology of the district, and, secondly, the lode fracture pattern. Superimposed on these, there are innumerable faulting problems which tend to complicate the search for ore.In this paper it is proposed to deal primarily with the lode fracture pattern and to touch on the general geology only insofar as it affects ore distribution. So much has been written on Kalgoorlie geology that it would be impossible to review the literature adequately in a brief paper such as this. The basic facts of rock types and rock distribution are well established and the broad structure of the field is known in the central portion, though it is less well established towards the northern and southern ends.The latest descriptions of the general geology are those of Stillwell (1), and Gustafson (2), -and these represent the basis of current knowledge.GENERAL GEOLOGY.The field is six miles long and about one mile wide, the long axis trending north-west. The "Golden Mile," or heart of the mining 'area, covers a length of three miles in the southern section, and consists of a central core of quartz dolerite greenstone which merges into uralitic quartz 'dolerite on its western margin. The uralitic quartz dolerite is derived from an original quartz dolerite by a low grade...

Jan 1, 1948

All companies and individuals who embark on a business venture incur costs. For the most part these costs can be conveniently categorised, firstly into capital and operating costs and then into the various elements of these major cost centres. Although the nature of expenditure naturally differs as between industries certain broad cost types are characteristic of all heavy industries. The capital costs of gaining access to an orebody, equipping a new mine, building a treatment plant and perhaps refining and smelting facilities are likened to capital expenditure by a manufacturer on new plant and equipment required for an expansion or new product innovation. Similarly the day to day costs of labour and materials employed in the running of a mining operation can be likened to similar costs in other heavy industry. There is another group of costs that are not so easily categorised. Most industries incur unavoidable costs that do not form part of the direct or capital costs of physical production. These costs include taxes and other payments to government and research expenditure. The mining industry has a particularly heavy burden of non-production costs and it is the objective here to highlight and analyse a few of them. These costs are exploration expenditure, infrastructure expenditure, royalties and income tax. This is not to suggest that these are the only major non-production costs that the mining industry needs to bear. The industry may incur significant costs for environment protection, land tenure maintenance and on liaising with Government on a wide variety of matters. It is for reasons of subject manageability that the list is confined to the four costs mentioned. For the mining industry, exploration and infrastructure expenditure, royalties and income tax have several distinguishing features. Firstly, they are generally proportionately large costs. Exploration and infrastructure expenditure for example, could well exceed mine development costs. Depending on how royalties are levied, they may be very high in relation to profits earned and many in fact exceed profits. Secondly, except for income tax, they are costs that are generally not payable by other industries. Exploration expenditure is in some respects comparable with industrial research and development. However, because mines are wasting assets exploration is necessary for survival, and it is likely to form a larger part of costs per dollar of profits or sales than R&D. It can therefore be said that exploration is of far more significance to the miner than R&D is to the typical industrial company. Furthermore, unlike exploration expenditure, R&D results are transportable and patents permitting, transferable. The infrastructure burden that miners must carry is unique to the industry. Whereas urbanised industry is not usually liable for the capital cost of power, water, transport, townships and community facilities, the miner must finance these projects himself. Neither the payment of royalties, nor of course, income tax are unique to the mining industry. Royalties are more properly described as a unique charge on some primary industries but however described, they are a charge that manufacturing and service industries do not have to pay. Whilst we all pay income tax, the mining industry's uniqueness derives from the special problem that the industry has in arriving at annual net income in view of the capital intensity of the industry, partly due to expenditure on infrastructure, the indefinite life of capital equipment and its unpredictable residual value, funds expended on exploration and long lead times associated with a mine development. The third distinguishing feature of these costs is that, with the possible exception of exploration expenditure, they are heavily influenced by the policies and actions of Government. As such the industry has a responsibility to promote the industry by emphasising its potential to improve national product including exports and by requesting that the Government provide for the industry in its long term planning and seek its co-operation to prevent the industry incurring inequitable penalties relative to other industries.Finally, exploration and infrastructure expenditure are significant because they are front-end charges on a project. When due allowance is given the time value of money and the deferment of income from a mining development to which they relate, exploration and infrastructure expenditure assume greater importance than the raw money expenditure suggests. For all these reasons, exploration and infrastructure expenditure, mining royalties and mining income tax are worthy of detailed study. This is the purpose of this paper. The objective is to examine the determinants that give rise to them and provide some thoughts on their impact on on-going and potential mining developments and, where relevant, to make some suggestions as to how they may be minimised.

Jan 1, 1977

By K Baker, J Purtill

One of the key challenges for the mining industry globally is the rehabilitation of mine waste, and Queensland is no exception. Out of pit waste structures including waste rock dumps and tailings storage facilities, create novel landforms which require ongoing maintenance and pose risks to the environment and sometimes to communities. Where multiple mines co-exist, such as parts of Queensland’s Bowen Basin, individual mines can often be constrained by adjoining operations. This presents opportunities for broader rehabilitation strategies to be considered, more than the current single mine focus, that may provide better environmental outcomes for a region. Given recent global disasters involving tailings storage facilities, and our team’s endeavours to drive Queensland to achieve leading practice in mined land rehabilitation, we are exploring the potential to maximise in-pit tailings disposal opportunities for coalmines through shared waste management strategies. A shared waste management strategy is where two (or more) mines, owned by different companies and operated under different environmental permits, transport tailings from one mine to the other in close proximity, for disposal in a disused pit. This would reduce the number of waste structures to be built, operated, rehabilitated, and managed in perpetuity. Our objectives are to identify and remove barriers to tailings transfers between sites to:  minimise environmental risk  minimise long-term liability of managing mining waste and associated structures  support improved outcomes for the local community. To determine the scale of coal waste disposal practices in Queensland, internal data and publicly available imagery was analysed by the Department of Environment and Science in 2022. Approximately 6500 ha of land in Queensland is utilised for coalmine tailings storage facilities or codisposal areas, with ≈ 3700 ha of this being out of pit.

Aug 2, 2023

Drilling has disclosed a sequence of Cainozoic sediments immediately to the west of the Ediacara mineral field containing little or no dolomitic debris in the lower and middle sections, but with gravel beds of dolomite derived from local rocks in the upper part. It is suggested that the lower and middle sequence of Cainozoic strata was deposited over the area of the Ediacara Range, and that this range was uplifted, probably as a horst block, during Quaternary times and was first exposed to subaerial erosion during the upper Pleistocene epoch.Lower Cambrian dolomites with associated stratiform lead mineralization, which formed the target of drilling on the western downthrown block of the Ediacara Fault, were eroded before deposition of Cainozoic sediments.Intense leaching of basal Cambrian dolomites around the periphery of the Ediacara Basin took place during Mesozoic and Tertiary times. This leaching process has resulted in enrichment of copper and lead mineralization in a thick marginal zone of residual clayey material overlain by dolomitic collapse breccia. These zones of leaching and enrichment were preserved under Cainozoic sediments which have subsequently been eroded. The Ediacara Fault appears to have been a major conduit for mineralizing fluids and is the main lineament of the Torrens Hinge Zone. Contemporaneous movements on this fault have controlled rates of depositionand thickness of sediments across the fault during Adelaidean and Cainozoic times. Though latest movements of this fault have been west block down, the predominant movement has been east block down with associated thickening of sediments to the east in the Adelaide Geosync1ine.

Jan 1, 1972

The central thickened discharge system of tailings disposal takes advantage of the natural beach slope formed by sub-aerially discharged tailings, and the non-segregating properties of thickened tailings, to create a homogeneous conical stack. The need for containing embankments can be largely avoided leading to capital and operating cost savings. Methods for estimating beach slopes and tailings density, essential parameters for the design of such a system, are described. Case histories from three mining operations are used to illustrate the application of the technique, There are also seen to be potential advantages in the areas of water management, seepage, and rehabilitation. Laboratory and in-situ testing enable parameters to be determined.

Jan 1, 1991

By D Smith

The Broken Hill deposit is located in Australia in the far western region of New South Wales. The deposit was found in 1883 and has been mined continuously since its discovery. It is considered the largest lead, zinc, silver deposit that has been discovered in the world and originally contained around 340 Mt of ore at a grade of around 12 per cent lead, ten per cent zinc and 150 g/t silver. The material remaining in the deposit represents only a fraction (perhaps ten per cent) of the original resource. Several of the world’s largest mining companies can trace their origins to the Broken Hill Field. The remaining resources on the CML7 consist of two large lower grade resource lodes that have not been subject to mining, some scattered areas of zinc lode material and the pillars and remnants of the main lead lodes.The deposit occurs in metamorphic rocks of the Broken Hill Group a division of the Willyama Super Group contained within the Curnamona Craton. The Broken Hill Group rocks have undergone multiple phases of deformation. Metamorphism is granulite grade with major shears cutting through the deposit having been retrogressed to mica schists. The deposit lies in an antiform associated with the second phase of deformation.The resultant proposed mine is situated on Consolidated Mining Lease 7 (CML 7) which occupies a strike length of 3.6 km in the central part of the 7.8 km long footprint of the orebody. Underground mining on CML7 ceased in 1975 with surface mining of silver chlorides in the weathered zone continuing until 1991. CBH Resources has been continually working to define and evaluate the remaining resource since 2002. This work has included four surface drilling programs, two underground drilling programs, an exploration decline, enormous amounts of compilation of historical data and detailed three- dimensional (3D) modelling of historical mining and the resource lodes. It is currently planned to commence production at the Rasp Mine in late 2011. The operations will produce from previously unmined lodes and from remnants and pillars.This paper primarily aims to encapsulate the processes involved from information acquisition through to resource estimation and also to highlight some of the challenges encountered and the specific techniques and practices used to overcome them. Many of the experiences at Broken Hill are applicable to all brown field sites.

Aug 22, 2011