Search Documents

By G Cormack

By designing comminution circuits for mineral liberation rather than the final recovery process and by using high mass pull gravity recovery, the concept of underground processing has become a reality. Gekko has found that many ores respond favourably to fine crushing with either high pressure grinding rolls or vertical shaft impactors which when combined with the InLine Pressure Jig gravity separator and coarse flotation results in a narrow, low-head, compact processing plant that can be sensibly fitted in existing underground openings. The focus on fine crushing reduces the power requirements of the plant to approximately 5 kWh/t for a capacity of up to 20 t/h run of mine ore feed. The use of water recycle systems places no extra load on the mineÆs normal water handling system. GekkoÆs underground processing plant, the æPythonÆ, has been designed to be towed down the decline or lowered down a shaft and is capable of being installed in sloping, non-linear drives for placement close to the working face. The overall benefit to mining companies of this concept has been estimated to be a significant operating cost-saving, lower cut-off grade and a significantly smaller environmental footprint.

Jan 1, 2008

By T Klinge, P Field, N Sugden, D Trenberth

Mining remains one of the key industries in Australia and many other countries with mineral wealth. In Australia, mining contributes 8.8 per cent to the countryÆs gross domestic product (McKay et al, 2000). In Queensland alone, mineral and petroleum industries contribute approximately $9.4 billion to the StatesÆ gross state product (2001/02) (Young, 2003). Increasing pressure on mining companies to perform in a global marketing environment requires mine management to consider more innovative ways to manage their resources û human, plant and equipment û which includes the gathering and analysis of operations data and information for improved decision making. For any mining operation utilising rubber tyred equipment such as trucks, front-end loaders and ancillary equipment, annual expenditure on tyres and related items can be significant. Even a small reduction in tyre operating costs can have a real effect on the business bottom line performance in the short term. Tyre Application Risk Management (TYREARMÖ) can provide substantial benefits in the long term across a number of KPIs not just through reduction in direct tyre expenditure but through flow-on improvements in safety, productivity and reduced environmental impacts. Several accidents involving tyres have also highlighted an increased need to consider the hazards and resultant risks arising from operations of rubber tyred mining fleets (Torlach and Johnston, 1990). This paper presents the process and results of achieving sustained safety and business improvement through the strategic alliance between an earthmover tyre management service provider, Klinge and Co (Klinge) and a BHP Billiton coal mine. The accompanying case study demonstrates in some detail the overall methodology, and the tools and technologies used where active management of data, its analysis and decisions taken have resulted in a 43 per cent improvement in tyre cost performance and a corresponding reduction in tyre-related downtime since the beginning of the alliance.

Jan 1, 2003

The Kanowna Belle deposit was discovered in 1990 following encouraging assays from soil sampling and RAB drilling. At the end of September 1993, diamond drilling had been completed to a vertical depth of 1,000 metres and a resource of 22 million tonnes grading 5.73 grams of gold per tonne containing a million ounces of gold had been defined. The deposit remains open at depth. Pre-production mining for the open pit began in November 1992, construction of the oxide treatment plant began in January 1993 and the first gold was poured in September 1993. Sulphide ore roasting commenced in December 1994 and the underground mine development commenced in July 1995. The Kanowna Belle project is owned by the Golden Valley Joint Venture (GVJV), an unincorporated joint venture with equal shareholdings between North Gold (W.A.) Ltd and Delta Gold N.L. North Gold are the managers of the development and operations and Delta Gold are the managers of exploration throughout the GVJV tenements.

Jan 1, 1990

The key elements required to maintain final wall integrity and hence slope reliability are discussed. Failure modes and mechanisms in highly structured rock slopes are then reviewed. The impact of blast disturbance on rock masses in general is discussed and the relationships between the slope failure mode and blast disturbance is then explored. The question of how designers can incorporate such impacts into the slope design process is then addressed. This necessarily involves rock mass strength consideration and two case studies are used to demonstrate a recent dilemma in this regard. Some progress regarding this dilemma has also been reported for the second case study. The major conclusions are that: Slope reliability can be severely compromised if the slopes are damaged by blasting and this impact is not often incorporated into the slope design process. The location and extent of the blast damage will impact some slope failure geometries and failure mechanisms more than others. The concept of failure mechanism specific vulnerability needs to be further developed. The evidence indicates that this aspect is even more extreme for weak ground conditions. The quantification of the reduction in rock mass strength due to blast damage is not well understood and limitations exist with some recent guidelines. The use of the Hoek-Brown criterion for slopes in blocky rock masses requires considerable judgement. Further applied developments in this regard would be very beneficial to the industry. Some promising methods to incorporate blast damage estimates into the slope design process are emerging. It is good business to minimise final wall blast damage otherwise a whole range of issues relating to reduced slope reliability emerge.

Jan 1, 1999

By C F. Prins, C LantuTjoul

Mineralisation in alluvial diamond or vein gold deposits is often hosted in trapping mechanisms. For instance, diamonds are nested in bedrock depressions such as gullies and potholes which were carved out by the sea long before the diamond deposition took place. Similarly, gold mineralisation can precipitate in the necks of a boudinage structure. In such deposits, the spatial distribution of the mineralisation is governed by the mutual arrangement of the trapsites and by the grade variations within each trapsite. Reliable estimates can be obtained only if they rest on a proper knowledge of both degrees of variability. This creates a challenging sampling problem, as during the exploration phase it is important to have a good global mean estimate to enable decision making towards the future. A similar problem occurs for local estimates at a later stage of development. To understand and manage the sampling for global means, specific sampling procedures are required based on an appropriate choice of sample support size and spacing. Estimates from such sampling campaigns should be unbiased, and the less variability they display, the better the sampling parameters. The performance and impact of sampling parameters are tested and compared on different simulated deposits.

Jan 1, 2005

By Nowell SB, Cottrill DA

Host-rock - wallrock major and trace element geochemistry associated with epithermal gold mineralisation in the Hauraki Goldfield of New Zealand is poorly documented, even though rock geochemistry is a recognised tool in exploration. Such responses assist in recognition of the regional scale imprint of fossil hydrothermal activity, and indicate targets for detailed evaluation within these alteration zones.Recent investigation of gold deposits in the Waihi (Gladstone), Golden Cross (Empire), Thames (Waiotahi) and Coromandel (Tokatea) areas indicate enrichments of Au, As and Sb in the andesitic wallrocks hosting mineralisation. Of the other elements examined, Si, K and Rb are enriched, and Na, Ca, and Sr are depleted at all deposits. These trends are best developed in the vicinity of veining. In deposits with clay alteration dominating (Waiotahi and Tokatea) there is also depletion of Mg, Mn, Zn and Cu. Ba and Cr are variably enriched or depleted within different styles of alteration. Base-metal enrichment in the wallrocks is not a feature of Hauraki deposits.

Jan 1, 1990

In the early ages man contented himself with the use of such tools and appliances as would assist him in the enlightenment of his labours. With the advancement of science, numerous motives, with modifications and adaptations, have been introduced to enlighten labours, and in many cases have taken the place of man, but it can hardly be said that this applies to shovels, although one of the oldest implements of labour; certainly, with the introduction of the steam shovel the labours of man have been considerably reduced, but the hand shovel of today is used similarly to that of years ago.If the principle of the hand shovel has not been improved upon, it must not be suggested that the manufacturers of this article are not endeavouring to improve its quality, and the main point with which the manufacturers have to contend is the production of an article which will give a maximum of durability combined with a minimum of lightness. In order to accomplish this they must select suitable material, and subject it to such heat treatment process that will produce a shovel having a maximum of hardness and toughness without being unduly brittle, and which will withstand the excessive wear to which it is subjected.In this article an endeavour will be made to explain (a) the manufacture of shovels; (b) the defects commonly met with-the cause of same and measures which are necessary to remedy them.Before doing so a brief description will be given of the class of steel used for shovels; this is an important factor, and a steel which is admirably suitable is a plain carbon one containing approximately 55 - 70% C., and closely resembles that used for the manufacture of railway rails. This plain carbon steel is very extensively used, although at present alloy steels are being utilised to a certain extent for shovel manufacture, and with suitable heat-treatment.

Jan 1, 1926

By W J. Shaw

Geometallurgical modelling is now a hot topic in deposit evaluation and in optimising mine performance; however, its history is long and varied. Historically metallurgical sampling has frequently suffered from a lack of data due to the cost of producing representative bulk samples. In the early 1990s geometallurgical modelling similarly suffered from a lack of data due to complex, time consuming and expensive sampling techniques. More recently, simple and relatively cheap tests for geometallurgical variables such as hardness, grindability, throughput, SAG power index, bond work index, crushing index, mineral recovery and concentrate grade have become widespread. The cheaper sampling has resulted in relatively large geometallurgical databases. However, most of the geometallurgical variables sampled are implicitly (and incorrectly) assumed to be additive when modelled by traditional geostatistical techniques, often leading to ill-informed and costly decisions. Geometallurgical variables are mostly non-additive so the current geostatistical challenge is to develop new approaches to dealing with this type of data. This paper briefly describes a historical case study of geometallurgical modelling of the George Fisher Pb-Zn mine completed in the mid 1990s, then outlines some of the current misconceptions of geometallurgical data and modelling techniques regularly applied to it, and finally discusses some recent developments in geometallurgical modelling, with examples from a number of current clients indicating the direction forward.

Jan 1, 2009

By P R. G Milne

A risk-based approach to optimising pit wall slope angles was trialled in the design of a 60m deep open pit in extremely weathered and distinctly weathered materials in the Kalgoorlie area. The pit used for this approach was Stage 1 of a three-stage open pit project. The Stage 3 pit will require long term stability, as it will contain the portal for a long life underground project. Information from failures induced by steeper wall angles used in the Stage 1 pit would be valuable in predicting and preventing long-term stability issues in Stage 3. In this approach, the pit wall slopes are based not on the normal factors of safety, but on the assessment of the probability of failure and the direct and indirect costs of dealing with the failure when it occurs. In this example, the benefits and risks of adopting steeper wall angles were compared in a series of graphs. These charted the increasing probability of failure and simultaneous decreasing factors of safety with increasing pit wall slope, and the range in the possible volumes of circular failures for increasing wall angles. These were brought together in a graph showing the potential excavation savings (in BCM) and the probable cost of a failure (probability of failure times the probable volume of the failure). The resulting pit design was based on the project Mining EngineerÆs semi-quantitative assessment of where and when a higher risk of failure was acceptable and where it was not acceptable as it may have unduly affected the integrity of haul roads or production. The design incorporated wider than normal berm widths to accommodate anticipated failures and to enable modification of the wall configuration if required. Several re-designs were required during the life of the project in response to aggressively induced failures. It is considered that this risk-based approach provides a practical route to optimal pit design and operation but it requires an experienced, dedicated and efficient mining team for it to be implemented with benefit.

Jan 1, 2003

By Gregory O, Winters BI, Garlick C, Rogers H, Ye ZC

BHP New Zealand Steel produces iron from titaniferous ironsand by a direct reduction process comprising multi- hearth furnaces/rotary kilns/electric iron melters. The electric iron melter is a six-in-line rectangular submerged-arc furnace which takes the partially reduced ironsand (80% metallization) from the rotary kiln and completes the reduction process to produce iron of nominally 3% carbon. As the melter operates at around 1500 ¦C and under very hostile conditions, it is near-impossible to obtain any basic operating parameters such as the velocity and temperature distribution in the slag and in the molten iron. As a first attempt to understand the operating conditions inside the melter, a scaled room-temperature model using wax and water to represent the slag and iron, was constructed. This paper will report on some of the preliminary model results on the temperature distribution.

Jan 1, 1995

By Gregg PEH, Stewart RB

Reclamation field trials commenced in 1985, two years before the granting of the Mining Licence. The level of pasture production on varying soil depths (0 cm, 5 cm, 15 cm and 25 cm) overlying both tailings and oxidised waste overburden was assessed. After seven years, the rate of increase of N, C, P and S, losses of S and P and pH changes were investigated on the plots where grass seed was sown into bare tailings. It was determined that on these plots it would take approximately 24 years to reach the original carbon and nitrogen levels at the mine site.

Jan 1, 1995

Surface subsidence caused by coal mining operations was the subject of a very successful symposium organised by the Illawarra Branch of the Australas- ian Institute of Mining and Metallurgy in February, 1973. This symposium dealt with the principles of subsidence and overseas experiences arising out of underground mining. Since that time the i eew South Wales Department of Mineral Resources and Development (formerly the Depart- ment of Mines) has incorporated in the approval for pillar extraction certain conditions related to the monitoring of surface movement. Surveys and plans are required to be kept at mines where total or partial extraction of coal takes place. This paper traces the monitoring of surface movement in the Northern Coalfields of New South Wales over the past ten years. Reference is made to the National Coal Board's Subsidence Engineers' Handbook (1975) and how the guidelines expressed therein have been Beneficial.

Jan 1, 1980

The care necessary to ensure a reliable estimate of average value from the individual values of a series of bore holes sunk in any alluvial deposit containing coarse gold was well exemplified in checking over the mining returns from a previously bored deposit in Central Otago, N.Z. While the working returns are always liable to vary considerably from bore values in any particular sub-section of an area, still, over any considerable area, the two must check within small limits, if profits are to be calculated and capital raised on the average value given by boring.The present figures have probably more value than those from, dredge returns since accurate measurements are difficult to obtain in irregular water-filled dredge paddocks, whereas in the case under review the paddock walls stood almost perpendicular, and, as the measurements were taken and checked in the empty rectangular excavation, the yardage estimate may be taken as substantially exact.NATURE OF DEPOSITThe area consists of a narrow valley deposit of fluvio-glacial origin, the original deposit having been eroded and the gold reconcentrated by post glacial rivers. The wash is between 80 and 90 ft. deep, and is formed in two distinct layers:(i.) The top layer from surface to 70 ft. or 80 ft. consists of about equal quantities of gravel mixed with glacial drift, and a small amount of clay. The gravel is typical discoid glacial stone of a maximum size of about 4 in. diam. by 1 in. thick, and consists of soft micaceous schist and laminated slate. This upper layer of wash contains no coarse gold whatever, and very little fine; indeed, in mining, the top 30 ft. is discarded without being passed over the boxes.(ii.) The lower layer of wash to bedrock is similar to the upper, except iihat it contains about 10% of larger discoid stone up to 12 in. diam. by It in. thick; 90% of the gold is concentrated in this bottom layer.

Jan 1, 1929

By J MacDiarmid

Atlas Copco is a leading provider of industrial productivity solutions (Atlas Copco, 2007) and one of the worldÆs largest suppliers of rock drilling equipment. The business division of Atlas Copco Construction and Mining Technique is based in +rebro, Sweden with the majority of their equipment produced in a number of facilities within the area. As part of the 2006 AusIMM/Atlas Copco Scholarship I was fortunate enough to visit these facilities to experience first hand this truly unique global company. Through numerous presentations on the various divisions and products manufactured by the company, I saw the broad range of products and services offered by the company and came to realise it is much more than just selling drills. Other highlights included a brief love affair, a tour of EuropeÆs largest underground mine (or factory depending who you ask), a drink at the ice bar at the ice hotel in JukkasjSrvi, and a number of dinners of reindeer. Overall this it was a truly amazing experience with all involved with the program going out of their way to ensure I got the most out of the trip. More importantly, through no effort at all, everyone naturally conveyed their passion for the industry and the company which is a great credit to the æAtlas Copco WayÆ thereby creating a company æcommitted to your superior productivity through interaction and innovationÆ.

Jan 1, 2007

By R M. Tosdal

The Manantial Espejo district (Argentina) hosts a low-sulfidation epithermal Ag (-Au) deposit with a proven and probable reserve of 38 Moz Ag and 0.55 Moz Au. The district lies along the southern rim of the Deseado Massif in the Middle to Late Jurassic Chon Aike Province, a large bimodal igneous province dominated by silicic volcanic rocks that were formed during the initial extension leading to the opening of the South Atlantic Ocean. The district stratigraphy consists of 162 to 161 Ma old rhyodacitic to rhyolitic volcaniclastic rocks of the Chon Aike and La Matilde Formations, followed by 160 to 157 Ma old andesites and dacites of the informally called intermediate formation. The main stage of normal faulting post-dates the volcanic activity and coincides with the formation of the precious metal veins that were dated by 40Ar/39Ar on hydrothermal adularia with ages between 152.8 ¦ 0.8 Ma and 156.6 ¦ 0.8 Ma. Economically important hydrothermal veins show characteristic features of a low-sulfidation epithermal deposit with crustiform and colloform banding, bladed calcite replaced by quartz and abundant adularia. In the Maria Vein, the major orebody of the district, six hydrothermal stages are identified, but only stages one and four contributed metal. Lead isotope ratios in hydrothermal sulfides show a close relationship to ratios in feldspars from the district Chon Aike Formation, suggesting a common source for the Pb and possibly the precious metals in both the magmatic and hydrothermal products, or that the Pb in the hydrothermal veins was derived from the volcanic rocks. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

The products of the steel tube industry play an important part in the production,' transrzission and refining of oil. Steel tube manufacturing is already well established in Australia and supplies the petroleum industry with its requirements" within the .present limitations of the various tube plants., With the discovery of oil in commercial quantities in this country, the steel tube industry could be expected to extend its scope to cover a much wider range; of oil country tubular goods, line pipe and refinery. Tubing.

Jan 1, 1962

By M F. Navarrete

During 2003, different plastic stemming plugs (Cats«, Stemtite«, and Taponex«) were tested in EscondidaÆs Mina Sur, to determine the effect on gas retention time when used in conjunction with drill cuttings in production shots with a blasthole diameter of 10 5/8ö. Longer retention times were expected to provide greater fragmentation and muckpile looseness. In order to determine which plug showed the greatest enhancement of stemming retention, 17 trials were carried out û in the first seven tests, only the Cats were used, in the following five tests, a combination of Cats, Taponex and Stemtite were used, and in the last three tests, only the Taponex plug was used. In the last two blasts, drill cuttings were used without stemming plugs as a benchmarking exercise. Blasts were filmed with a high-speed camera, which could record the detonation times of holes using rolls of shock tube tied to stakes at the hole collars, to act as flash indicators. The camera allowed measurement of the time between charge detonation and the commencement of stemming ejection. In order to obtain the statistical parameters of each one of the stemming plugs used in the 17 trials carried out, the Minitab software was used and a data base was created for it, corresponding to each stemming configuration with the retention time obtained from the filming. Once it was determined which stemming plug provided the greatest enhancement of stemming retention, the impact on the fragmentation was analysed using the WipFrag image analysis software to estimate the muckpile size distribution.

Jan 1, 2004

IA )W cli',hla cn1cnt fault 7011(-s 0 11Cn cOrnprise a nrc,II of inrcIIinkc(I faults, cvtcnqonal shear and In]rck cxtcnsir>nal vein- fractures. Hydrothermal mineralisation localised around such structures testifies to their importance as conduits for fluid flow. Mesh structures are most commonly developed in situations approximating bulk pure shear but predominantly simple shear meshes also occur. They appear to develop through the infiltration of pressurised fluids into a heterogeneous rock mass with varying material properties. In some circumstances, mesh formation appears to be a precursor to the development of major throughgoing faults. Mesh formation generally involves hydrofracturing (Pf> a3, at least locally) and the condition Pf - 63 to be maintained for the mesh to remain a high permeability conduit, requiring fluid overpressuring at other than shallow depths in extensional-transtensional regimes. The volumetric character of earthquake swarm activity appears to result from the passage of hydrothermal fluids through mesh structures, representing a form of distributed fault-valve action along suprahydrostatic hydraulic gradients arising from magmatic intrusion, compaction overpressuring, metamorphic dewatering, etc.

Jan 1, 1995

By Warner R. E

Present capacity for molten iron production at Port Kembla is an average of 13 000 t/day from five blast furnaces. The most recently installed blast furnace, No.5, was commissioned in March 1972 with a design capacity of 4 500 t/day. For the first reline currently scheduled for 1977, plans are being finalized.for significant modifications and uprating of capacity. Achievement of the initial design capacity from No.5 blast furnace on a sustained basis was not realised until the third year of operation. Although the furnace is only 42% larger than No.4 blast furnace on an inner volume basis, the more stringent raw materials, operation and maintenance requirements of the larger furnace and more complex equipment have been found to be much more critical than anticipated in the planning stages. These problems have also been experienced by many other companies who have recently installed large new blast furnaces. Some of the principal problem areas are described together with measures taken to over- come the difficulties. The problem areas include the failure of'the shower cooled bosh, failure of the upper shaft brickwork, sludge

Jan 1, 1976

Any project carries a number of challenges and risks. Inappropriate design, poor project management, time, industrial disputation and capital over runs are all areas which can impact on a project cash flows and return on investment. In the resource Industry you have the added complexity and risk of geology which is difficult to predict and sometimes unforgiving. The Dartbrook Mine was designed and constructed as a high output longwall mine and has overcome a number of hurdles to produce over 2.3 million tonnes for the first year of operation. A number of problems were encountered during construction which resulted in the inseam development being delayed for six months. Dartbrook people have demonstrated they can manage adversity and produce world class results. The mine has been through a very steep learning curve during 1997 and with this experience behind the mine is now producing at an annualised rate of 3.4 MTPA.

Jan 1, 1998