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By Tukkimies M

During the late-1980s crawler-mounted crusher units established their position in the aggregates industry. Between 1986 and 1994 about 700 units were delivered to customers all over the world for surface operations, mainly in Scandinavia and central Europe. The crawler-mounted units are popular among smaller crushing operators because they are versatile and easy to move between sites. In large quarries the greatest benefit is obtained by combining a primary crawler-mounted crusher unit with mobile belt conveyors which eliminates the need for costly haulage by dump truck. Savings of up to 40 per cent in production costs prior to secondary crushing have been achieved. Today the environmental aspect in quarrying is assuming ever greater importance. Besides being costly the dump trucks are also the major source of dust and exhaust fumes within a quarry. A complete face crushing system consisting of a crawler-mounted crusher unit and mobile belt conveyors can be electrically driven and can be equipped with dust encapsulation and dust collectors. A mobile crushing unit is not a new idea. From the mid-1950s onwards the mobile and self-propelled units have been built equipped with crawlers, tyres or walking mechanisms, with weights usually of 500-1000 t. Due to their massive size these unit are not mobile in the same way as the today's mobile units. It is not feasible to move them more than a few times a year unlike today's fully mobile units which are often relocated once an hour. This means that the massive units can not continuously follow the production face and their loading always requires a certain amount of haulage. Today the mining industry is facing new challenges. With low mineral prices and high labour costs, increasing productivity is essential for survival. New standards are also being set for the labour safety and the environment. Large research programs have been launched to meet these challenges. However, technology which can partly solve these problems already exist and is only waiting to be introduced into underground applications as well - the mobile crushing unit followed by belt conveying. As in surface operations the elimination of truck haulage also brings considerable savings in operating costs in underground mines and reduces the amount of dust and exhaust gases generated. An additional benefit especially in underground applications is improved safety. In an underground mine most accidents are caused by moving vehicles.

Jan 1, 1995

By P Benjamin, H Bohannan, C Farr

Geoffrey Blainey's historical account of the mining activity on the west coast of Tasmania, æThe Peaks of LyellÆ documents the changes over 130 years of activity in the region. Commissioned by the Mount Lyell Mining and Railway Company, emphasis is placed upon the development of the Mount Lyell Mine in Queenstown. Chapter 19 æWidening HorizonsÆ details the review the Mount Lyell Company undertook in 1904/05 to ensure the future of the operation, following the pessimistic outlook regarding diminishing reserves and poor grade ore. The analogies documented between the Mount Lyell Company at that time, and Gold Mines of Australia 90 years on are remarkable, with both companies demonstrating a commitment to the Mount Lyell area through active exploration, the proactive search for alternative technology and the recognition of the valuable human resource. As Blainey writes (Blainey, 1993), æwith its expanding chemical works, its huge Tasmanian mines, its railways and smelter, its coke works and its mine crusade, Mount Lyell was probably one of the nation's five great industrial companies in 1906 or 1907. This brief phase of industrial and mining expansion had its seed in the threat of extinction . . .Æ After a number of reprieves, the Mount Lyell mine did stop production in 1994, but that only provided an impetus for a review and rebirth.

Jan 1, 1998

Gravity concentration of tin at Renison Limited uses tables and spirals to treat the various coarser fractions produced from sulphide flotation tailing. An acceptable final tailing cannot be made from one pass over the tables and spirals and therefore the tailing from these separators is reground and combined with the sulphide flotation tailing as the feed to the classification section. The gravity section became increasingly overloaded in the years preceding 1976 due to efforts to maximize tin recovery to the gravity concentrate. In April, 1976, two 2DSV Reichert cone concentrators in series were installed to treat the table and spiral tail- ing stream, prior to regrind, to scavenge a small tonnage of hard, coarse low tin grade material for rejection to final tailing. Gravity section loadings were decreased markedly, allowing operator attention to be directed more to table performance than to spillage collection. An increase in mill throughput of approximately 15% was possible following the commissioning of the Reichert cones. The cones are currently operated to make the minimum tonnage of tailing consistent with reasonable- gravity section loadings.

Jan 1, 1978

By Smith P

The past 20 years have seen the replacement of hydraulic control of longwall mining systems by the neater. smaller and better controlled electronic units.Early problems of moisture and other effects on reliability were overcome to see electronically controlled supports chosen for Corrimal Colliery ten years ago. Lessons from Corrimal and elsewhere, with following improvements and sophistication led to wider use as exemplified by Meco and other electronically controlled supports used in more recent installations in New South Wales, Queensland, USA and Czechoslovakia of the total of over 80 electronically controlled support installations worldwide in the past decade. Present work is toward a fully "integrated face" of British Coal by 1993, incorporating the Meco automatic face straightening system already due for practical use in the UK later this year. However the manless face still appears to be some way off although the present minimum crews and close monitoring, including early warning, are promising stages.

Jan 1, 1991

By Allnutt S. L, Radojkovic A. M

Century, a major shale hosted zinc deposit in the Riversleigh Fold Zone of northwest Queensland's Mount Isa Basin, was discovered by CRA Exploration in 1989. A total of 322 drill holes, completed by the end of 1992, define a resource of 118 Mt of mineralisation averaging 10.2 per cent zinc, 1.5 per cent lead and 36 grams per tonne silver. Mineralisation is developed in the upper portion of Lawn Hill Formation Unit 4 (Pmh4). The intersection of the Termite Range and Little Range Faults, major regional structures, may have been important in controlling mineralisation development. Three listric normal faults, and an unconformity between Proterozoic rocks hosting mineralisation and overlying Cambrian carbonates, divide the deposit into three distinct blocks. The deposit is essentially blind, outcropping in only two places. The deposit is characterised by an extremely simple sulphide mineral assemblage, sphalerite being the most common sulphide phase. Pyrite, the most common phase in many other shale-hosted zinc-lead deposits, accounts for only five per cent of all sulphides present. Siderite is the principal non-sulphide phase present. Both sphalerite and galena have near stoichiometric compositions. Sulphides are confined to carbonaceous shale horizons. Intervening siltstones are essentially barren. Shale and siltstone beds forming the mineralised sequence can be correlated across the entire deposit area. Systematic grade variation occurs within each mineralised shale bed. Although sulphide laminae parallel primary lithologic layering, the point of most intense mineralisation development transgresses stratigraphy. Bituminous material is intimately associated with sulphide mineralisation.

Jan 1, 1993

By McConachy G. W, Wright J. V

During the 110 years since the discovery of the Broken Hill PbZnAg deposit six major mining companies have mined the ore body and explored the ore environment. Despite this activity, no new orebodies have been found at Broken Hill. The failure to discover large new resources cannot be attributed to a lack of activity because major companies have maintained substantial exploration commitments over many decades. This suggests that not only was a unique coincidence of conditions required to form the deposit but also that full recognition and definition of the critical parameters may not yet have been recognised. In an attempt to illuminate some of the more unusual and poorly studied characteristics of the ore environment some new areas of investigation are presented here which may contribute to understanding the ore deposit setting and focus exploration towards different and perhaps more productive targets. Sedimentological characteristics of the host succession of the Broken Hill deposit are apparently unique along the line of lode. An upward-coarsening megasequence reflected in the development of clastic psammites stratigraphically below the ore deposit is one important ingredient which has received little exploration focus. These psammites also host mineralisation and form part of a spectrum of quart-zrich rocks collectively referred to as gametiferous psammites, garnet quartzites and blue quartz lodes. Sedimentological data interpreted from outcrop, drill core and downhole geophysical well logs support a elastic origin for some of these rocks; an interpretation which is at variance with traditional interpretations favouring an exhalative origin. A clastic origin for many of the footwall psammites, and their close spatial association with the orebodies suggests their role in ore formation was important. It is interpreted as a critical part of the fluid flow architecture within the sedimentary basin, which focussed ore forming fluids into an unique environment favourable for trapping mineralisation. Detailed stratigraphic correlation near the deposit has also highlighted that quartzofeldspathic rocks (Potosi gneisses and lode pegmatites) have complex relationships with ore. Suites of stratabound quartzofeldspathic pegmatites have received limited study, but their distribution and voluminous development suggests they may be as important to ore formation as the psammitic lode rocks which host the orebodies. These associations are not in conflict with some recent ore forming models invoking deposition in a shallow water environments of deposition. The geochemistry of parts of the host sequence has been studied extensively in the past but this has not been merged with current stratigraphic subdivisions. A large drillhole data base now permits the geochemistry to be related to the sedimentary succession and reveals that a signature involving stratigraphic vectors best illustrated by changes in MnO, Na2O, Pb and Zn can be detected. This is interpreted to reflect sedimentary basin processes as opposed to a classical volcanic hydrothermal alteration pipe associated with seafloor venting. The stratigraphic setting together with characteristics of some of these poorly understood areas is discussed to emphasise that construction of sound models for exploration requires the total ore environment to be studied with attention directed to the geometry and setting of the full range of host rocks. Control of the greater portion of the line of lode by a single company, Pasminco Australia Limited, now permits disparate datasets and observations to be merged and presents new opportunities and encouragement for model refinement and exploration success.

Jan 1, 1993

By Noakes MJ, Willsteed TV

In the past few years an elevated gold price has resulted in the evaluation of many small scale surface gold deposits in Australia typically containing about 2-3 g/t Au. Operators have tended to assume that at the lower end of the grade spectrum only heap leaching is economically possible whereas above some assumed "cut-off" grade, carbon-in-pulp or similar techniques can be considered to have economic advantages.Studies made on a number of these prospects has indicated that this rather arbitary choice of treatment method can be mis-leading.A case study has been prepared assuming a "typical" situation and is presented. The deposit contains three million tonnes of ore assaying 3 g/t Au and is amenable to open pit mining methods. The mine site is remote but accessable and existing infrastructure is minimal. There are no unusual environmental constraints.

Jan 1, 1984

By Andrews S. J

Century is a shale hosted zinc, lead, silver deposit developed within gently folded, Proterozoic Lawn Hill Formation shales and siltstones, approximately 250 kilometres north-northwest of Mount Isa, comprising 118 million tonnes of stratiform mineralisation, averaging 10.2 per cent ,,inc, 1.5 per cent lead and 36 grams per tonne silver. The deposit is largely overlain by Cambrian limestone and younger Proterozoic sedimentary rocks, outcropping at only two places. Small discordant lode lead-silver deposits formed the basis of relatively small scale mining activity in the area for almost 100 years, exploration tenement covering the deposit being granted to CRAE exactly 100 years after the first mining leases were pegged in the area in 1887.Stratiform mineralisation occurs within three distinct blocks, bounded by normal faults and the unconformity between Lawn Hill Formation and overlying Cambrian limestones. The Termite Range Fault, a major northwest trending, regional scale fault system occurs adjacent to the northeast deposit boundary, while the Magazine Hill Fault, possibly a component of the east trending Little Range Fault system, forms the southern boundary of the deposit.

Jan 1, 1993

Krupp Polysius AG, FRG, in close cooperation with Prof. Dr. K. Schoenert, FRG have developed the principle of the high pressure grind- ing roll POLYCOM. The POLYCOM mill basically consists of two counter-rotating rolls of large diameter and relatively small width, one of which is fixed and the other moving in slide blocks. The pressure required for comminu- tion is applied via the sliding roll by a powerful hydraulic system. The comminution takes place between the rolls under high pressure in the bed of material by nipping and compacting. The top feed size-depending on the rolls diameter -may be as coarse as conventional secondary crusher feed and the product is a compacted cake containing a high amount of fines created by micro-cracking. The amount of fines depends on the pres- sure (grinding force) applied. Operating results show that even in wet griding circuits capacity increases at downstream connected grinding mills of up to 100010 can be accomplished with an interconnected POLYCOM machine and energy savings of up to 25070 may be achieved depending on application. POLYCOM can be used in existing grinding plants for low-cost upgrad- ing of capacities but also as an advanced alternative to conventional crush- ing and grinding equipment in open or closed circuit configuration. A single industrial size 2.8m roll diameter POLYCOM machine may be fed with top feed size of up to 200mm and produce a finish product as fine- grained as known from rod and ball mills but with less energy consumption. Meanwhile, the POLYCOM high pressure grinding roll has established itself world-wide in the cement industry and is now entering the mining industry. POLYCOM machines are currently designed in industrial standard sizes of 1.0m to 2.0m rolls diameter and drive units of up to 2400 kW. This paper includes: principles of high pressure grinding, main fea tures of the POLYCOM machine, results of tests on various materials including Australian gold and copper ores carried out at the POLYSIUS research centre in Germany. Some examples of industrial applications of high pressure grinding will also be presented.

Jan 1, 1988

This paper reviews the use of MTU diesel engines in uses such as Off-Highway Vehicles, Rail traction, Generating Sets, Marine Propulsion and Defence Applications, and focuses on a central theme of maximum power in the minimum of space.

Jan 1, 1986

By Misra A

The development of roadways in underground mines in Autralia is by conventional continuous miner technology. The rate of development achieved using this technology is improved by modifications to this technology using additional equipment such as surge cars or decreasing roof bolting time.Development rates achieved with this technology compare with developing technologies such as high capacity continuous miners, continuous transportation and simultaneous cutting and bolting systems such as the Kemcol Beaver. Pillar dimensions have an effect on the rate of development.'

Jan 1, 1991

To counter depressed world nickel prices, a continuing effort is being made at Kalgoorlie Nickel Smelter to reduce unit production costs. One major area in which production costs can be reduced is the substitution of coal for fuel oil. Two areas where this has been achieved to bring about a saving are, the addition of coal to flash furnace flux to reduce supplementary fuel oil requirements in flash smelting and the replacement of two oil-fired air preheaters with a coal-fired unit. These actions have resulted in coal replacing 67% of the current fuel oil requirement in flash smelting at the Kalgoorlie .Lckel Smelter.

Jan 1, 1987

By D Giles

We present plate tectonic reconstructions, showing that porphyry-type ore deposits are spatially and temporally linked to ridge subduction. A reconstruction of the Peruvian subduction system reveals an immediate metallogenic response to the arrival of the Nazca Ridge at the subduction trench, followed by southward migration of the zone of metallogenic activity due to the lateral migration of the zone of ridge subduction. A similar pattern is recognised in central Chile , where the spatio-temporal distribution of giant ore deposits coincides with the arrival of the Juan Fernandez hotspot chain at the subduction zone. We conclude that there is a spatial and temporal link between ridge subduction and ore deposit formation, with high metal fluxes concentrated in zones of ridge subduction. Thus, the recognition of tectonic patterns associated with ridge subduction can provide insights into predictive mineral discovery by enhancing our ability to predict the position of large mineral deposits in other modern and ancient orogens. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

By Distin P. A

The extraction of platinum and rhodium from scrapped honeycomb autocatalyst into hydrochloric acid/aluminum chloride/nitric acid solutions is described. Results are given for the effects of leachant composition, temperature and catalyst pre-reduction using hydrogen. Data are also presented for the recovery, by hydrogen reduction, of platinum and rhodium dissolved in the leach solution. Parameters studied include solution composition and temperature, hydrogen pressure, and platinum seed addition.

Jan 1, 1992

By Hyde L. J

Blasting is one of the available technologies to be employed in underground excavation systems. In many instances it can be the only technology which is suitable. The recent moves towards more mechanised working systems is resulting in a reduced awareness of new blasting practices and technologies on the part of many excavation engineers. Recent developments in blasting systems can be utilised to significantly improve operating efficiency, reduce total cycle times, better comply with regional environmental constraints and reduce the total cost of underground excavation. Blasting is and will remain, a very adaptable and exciting alternative which is far from boring.

Jan 1, 1987

By Paine GG

The in-situ retorting of shallow oil shale deposits is an attractive alternative to the material handling problems of conventional open pit mining techniques, which involve removing overburden, fragmenting and transporting the shale to a fixed retort, and finally disposing of the hot spent shale.For in-situ retorting to be successful, the oil shale has to be fractured and the fragmented rock expanded into a void, to allow controlled propagation of a flame front through the in-situ retort. The principles of cratering with explosives have been used to develop a process for the in-situ fracturing of a thin oil shale deposit overlain by a formation of porous rock. The overlying porous rock formation is first compressed by explosive charges to create voids in the porous rock. The oil shale is then fragmented and pushed in to the voids with separate explosive charges. This paper discusses methods of creating voids in porous rocks with minimal surface disturbance, and then methods of obtaining the most uniform fragmentation of the shale. The whole process can be completed, in practice, in one blast. The results of an experimental blast are presented, and possible modifications are then discussed.

Jan 1, 1985

Drum winders have now been built to attain depths of 3000 m and more in a single lift in accordance with the South African Code of Practice SABS 0294, which was introduced at the time of the last hoisting conference in 2000. Since then, this code has not only been followed for several winders in South Africa but was also followed in deep mines in Canada. Design of winders and their braking systems are described in the paper. Koepe winders are in use for high payloads of up to 50 t and to hoisting depths of around 2100 m. As known, the stress range of the hoisting ropes is the key parameter for rope fatigue. However, as per the SABS Code of Practice 0294, relying on static design is not the answer to the question of where the limits are for Koepe installation. The paper describes factors that are recognised to have influence in rope life and suggests definition of new design criteria for friction winders in order to get viable solutions for high-capacity hoisting from deep mines similar to drum hoisting.

Jan 1, 2005

Don Hausen was a pioneer in the field of quantitative mineralogy. Methodology that he developed at Newmont almost 40 years ago is still employed today, only the technology has advanced. Petrographic methods were stressed with an emphasis on alteration, mineralisation and paragenesis. Methodologies employed by Don on the Carlin deposit were applied to developing the Carlin Trend by helping to work out lithology and structure, which ultimately led to the discovery of deep high-grade deposits. Quantitative methods used by Don on San Manuel, Copper Creek and Superior, Arizona were applied to the development of the Batu Hijau Deposit in Indonesia. Advancements in technology since DonÆs time have made the mineralogist much more efficient. Manual measurement of peak heights off of strip charts for semiquantitative XRD has been replaced by software that does Rietveld refinement and whole pattern fitting. Hand contouring of XRD data has been replaced by digitised data incorporated into geologic models. Optical point counting, which would take a dayÆs work to process 1000 points, has been replaced by automated SEM methods where 20 000 points are possible in an hour. The use of the optical microscope remains relatively unchanged, and still remains as Don emphasised the æeyesÆ of mineral exploration. However, the information can be relayed much more quickly with digital image capture and electronic data transfer. Don insisted on becoming involved in projects at the grassroots level and supporting the project through mine closure. This made the mineralogist a liaison between exploration geologists, mine geologists, metallurgists and mine engineers. The methodology that Don helped develop continues to provide invaluable support to Newmont geologists and metallurgists worldwide today.

Jan 1, 2008

A large scale distributed process con-trol system has been successfully applied to the automatic control of aluminium reduction cells at Boyne Smelters. A three stage hierarchy of minicomputers and microcomputers is used to continuously monitor and control conditions in each cell and to manage the data generated during the process.The automation hardware was purchased on the basis of low cost, high reliability, prior use in the aluminium industry and a high level of backup under failure conditions. The hardware has met performance criteria to date.The process control strategies have continually been updated to minimise the energy and raw material consumptions in each cell. A major change to systems software has recently been made to decrease the development time for-future changes. Various low energy potline retrofit alterations are currently being investigated requiring significant changes to the process control strategies.

Jan 1, 1985

Most of the gold reef mined today in South Africa is approximately 1 m in width with slopes about 30 m long. To prevent production interruptions it is essential that the stopes should not be blasted in sections. The shortage of experienced labour and arduous working conditions at the face dictate the need for simple blasting techniques.Hence, a pyrotechnic blasting system of sequential firing is in use at present, although research work to improve this technique is in progress.

Jan 1, 1985