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By Gallet M, Watsford R. M S

The 1989 feasibility study of the chessy, france, copper, zinc, pyrite and barite orebody was based upon a classical flowsheet. The flowsheet included, three stages of crushing, conventional rod and ball mill grinding in series, and sequential flotation of four products utilising conventional mechanical flotation cells. To improve the profitability of the project the partners commenced a search for ways to reduce the projected capital and operating costs of the proposed development. This paper presents the improvements in the projected capital and operating costs as a result of design and concept changes. The major changes included: ò the simplification of the crushing section with the adoption of semi autogenous grinding (SAG) milling of primary crushed ore. ò the deferral of pyrite and barite flotation circuits until market conditions were positive. ò the simplification of the flotation circuit by the use of column flotation cells for combined rougher/cleaner duty. ò the purchase of second hand equipment. The result of these changes was to reduce the capital cost estimate of the plant from US$ 21 million to US$ 11 million and operating cost estimates from US$ 18.90 to US$ 13.60 per tonne of ore for a decrease of approximately ten per cent in potential revenues.

Jan 1, 1991

By Bevan JE

The US Bureau of Mines is conducting research to improve the health and safety for underground coal miners, and the efficiency of the mining systems that are used. In 1986, the Bureau began a major research effort on the technology for computer-assisted mining systems for underground coal mines. The initial target was technology for continuous mining machines that would allow them to extract coal by computer-assisted operation. Technology areas being investigated include guidance systems, machine condition systems, computer systems, machine control, human-machine interfaces and planning. In each of these areas, individual system development has progressed to where underground testing of these systems will begin in 1991.In addition to coal extraction, the Bureau has also begun research for the development of technology for computer-assisted roof bolting. The Bureau is developing technology for a "smart" roof bolter that would be able to sense and analyze strata conditions to determine the requirements to provide a competent roof. The system would determine the location of the hole, drill the hole to length, and select and install the appropriate bolt.

Jan 1, 1991

By J Andrina, D Richards

The Grasberg is a large copper and gold open pit mine operated by PT Freeport Indonesia and located in the high equatorial mountains of Papua Province, Indonesia. The climate is alpine/sub-alpine with little seasonal variation in temperature and rainfall. The annual precipitation varies from about 3000 to 5000 mm over short distances around the Grasberg, but in general, an average daily precipitation of 10 mm per day applies and leaching of the overburden is continuous throughout the year. Mining commenced in 1988, and almost all of the overburden mined up to 2003 was potentially acid forming. The current acid drainage from this overburden is being collected and treated. From 2004 to the end of the Grasberg pit operation in 2014, approximately 70 per cent of the overburden will be potentially acid forming and 30 per cent limestone. A program of laboratory leach columns, field test pads and an instrumented full-scale dump was developed with the objective of defining scale up factors to quantify the acid and metal leaching rates and to evaluate the stockpile geochemistry and control options. The results of an ongoing seven year program have demonstrated feasible scale up between laboratory columns, field test pads and the trial dump in relation to material geochemistry and ARD evolution trends at Grasberg. The potentially acid forming waste types are highly reactive and maximum acid generation rate occurs within two to three years and that maximum copper release occurs within one to two years of exposure. The results also show that the net acid generation (NAG) test provides a good estimate for the potential acid load from overburden types. The chemistry, temperature and oxygen data from the trial dump suggest that oxidation and acid generation is occurring throughout the dump but at a decreasing mass rate with increasing distance from the toe of the dump. It is apparent that convection and/or advection are important mechanisms for the transport of oxygen into and within the dump. Key results and findings of the investigations carried out are presented and the implications of the findings for long-term ARD management at the Grasberg mine are outlined.

Jan 1, 2003

By H Zahiri

Utilisation of the InSAR technique for monitoring of subsidence in mining areas, employing open pit and underground mining methods, has large potential due to sensitivity and safety issues associated with usage of the classical surveying techniques. InSAR can also be very competitive concerning the cost of provided results. However, there are a few issues that may significantly limit InSAR applicability for subsidence monitoring in mining areas. The altered terrain topography, involving steep slopes and deep pits, may lead to the layover of radar signal for specific satellite and pit geometry. Also, the highly dynamic character of subsidence induced by mining, especially using mass mining methods, may lead to issues such as apparent heave and ambiguous results. In this paper the authors analyse the above-mentioned issues and demonstrate how InSAR technology was applied, as a supporting system, to monitor large scale and highly dynamic subsidence for a real case study in Western Australia.

Jan 1, 2008

By Iley J. D

The production of zinc from low grade concentrates, particularly those high in iron, has a poor economic return due to a combination of higher concentrate transport costs, increased processing costs and an increased cost for disposal of iron residues. The production of iron-bearing residues from the electrolytic zinc process is also seen as undesirable for both cost and environmental reasons. This paper details the pilot plant testwork conducted at the Pasminco Research Centre in conjunction with Minproc for the production of zinc oxide fume from a high-iron zinc sulphide concentrate from Colquiri in Bolivia. The concentrate is derived from a tailings retreatment operation and has a high iron content (40 - 45 per cent Zn, 14 - 17 per cent Fe) due to the presence of marmatite. Pilot plant trials were conducted using the slag bath reactor at Pasminco Research Centre at rates up to 500 kg/h of pelletised zinc concentrate, using a natural gas/oxygen-enriched air lance. The fume produced averaged 76 per cent Zn at recoveries up to 96 per cent and was recovered in a baghouse after gas cooling. The iron was oxidised into a fayalitic slag that passed the TCLP test (toxicity characteristic leaching procedure) and the sulphur was oxidised to produce a high SO2 gas which would be suitable for sulphuric acid production. The process produces a zinc oxide fume that can replace calcine as a feed for electrolytic zinc plants. The iron reports to a stable slag for disposal, thus eliminating the need for its disposal as jarosite from the leach plant. Only a simple leaching operation on the fume is required as there is no zinc ferrite present.

Jan 1, 1993

By L Soares, W T. Hennies, F Fujimur

Barra Bonita reservoir, located in the Sao Paulo State, Brazil, has been mainly used for local navigation and electricity generation to supply a prosper region in the country. Sand mining activities in that area have an important social and economic meaning for the local community. In this reservoir there are several sand mines that produce around 45 000 m3 of sand a month. These deposits were rich in material used as concrete aggregate in the civil construction. However, nowadays a significant increase in the demand of gravel can be observed, representing a serious productive problem. This material hasnÆt been well accepted by the market and, through the years, it was disposed at open sky in piles as waste deposits. This deposits have caused environmental problems like visual impact, reduction of free spaces outside and inside the mine, source of material to erosion and sedimentation processes in lower areas, flooding as a result of the filling up process in the drainage system, among others. For a lack of an appropriate technological characterisation, this material have been mainly used to pavement internal and external areas in the mine, with lower cost associated. With the purpose of evaluate the usefulness of this material in the conventional concrete, there were conducted several tests in the disposed residue including petrographical, physical, and chemical characterisation. The petrographical analysis and the preliminary results of the study showed that the material reacts with the alkalis that are present in the conventional cement (CP-II-E-32). In order to make the application technical and economically possible a research was developed seeking forms to correct this characteristic by adding special cements with high pozzolana content. The results of the technological, physical and chemical characterisation of the products indicated the technical viability of the use of that material. The study also allowed projecting environmental improvements resulting in the elimination of the waste piles.

Jan 1, 2003

For several decades miners have been obliged to maintain a vast supply of sharp steels at the working face to meet the hungry needs of rock-drills. In medium and large size mines this has meant the setting up of an organisation to store steels, to make and sharpen bits with all the complication and skill of forging, hot milling and heat treatment, and to transport sharp and dulled steels to and from the working face with all its labour, wastage, and inconvenience to other mining operations.In a mine with 250 rock-drills in use, a flow of more than 60,000 sharpened steels each month has to be maintained to keep the machines fully employed, so some idea of the magnitude of this problem may be grasped.For a long time it has been apparent that it is mainly the bit itself that wears, and many attempts have been made to reduce the enormity of the problem by providing detachable steel bits which could either be used once and rejected, or sharpened three or four times before rejection.At the same time metallurgists have striven to 'improve the quality of the steel and the heat treatment afforded it so that a bit, readily workable In a normal mine drill-shop, could be produced having a high resistance to wear and fatigue; but, although various alloy steels have been marketed, it is still usual to find many mines relying on a "straight" carbon (0.6 - 0.9% C.) steel for their drill steels.Since 1915 increasing use has been made of tungstencarbide as a cutting implement in the engineering industry. Where, on account of its great hardness and long life, it...

Jan 1, 1948

This paper examines the various stages of development and design work which were necessary to develop the cemented rock fill system for copper mining at Mount Isa. The reason for a cemented sand fill development program together with details of the test work undertaken are briefly outlined. The testwork associated with the selection of a suitable local rock to supple- ment the cemented hydraulic fill is discussed, as is the method for underground placement and mixing of the graded rock with the cemented hydraulic fill. The design features of the final system which incorporates a graded rock handling system and a cemented hydraulic fill reticula- tion system is outlined.

Jan 1, 1973

The products from beneficiation present themselves at opposite ends of the spectrum, and yet numerous synergies exist in the preparation of coking coal and hematite iron ore products for their common export markets. Returning to the coal side of the business with Anglo Coal following a five-year sojourn in WA with Hamersley Iron, has provided the opportunity for comparing and contrasting some of the key synergies of the supply chains of both bulk commodities.Comparisons include consideration of things like: resource evaluation (especially quality aspects), run-of-mine handling and preparation, beneficiation, product handling and transportation, quality assurance and customer awareness, value-in-use and impacts on iron and steelmaking, and supply chain environmental aspects.Inherent within these are several other notable contrasts including: æseamsÆ and æorebodiesÆ, rocks and minerals, rejects and tailings, oxidation and weathering, suppliers and users, and marketing and purchasing, to name but a few.This paper covers some of the more interesting of these synergies and raises some potential opportunities for sharing knowledge and innovation between the two areas of activity in the future.

Jan 1, 2005

By A D. Paktunc

The surface reactivity of underwater deposited, high-sulfide copper mine tailings was evaluated under fresh and saline water cover conditions by measuring the surface and pore water quality as a function of time. The experiments were conducted in aquarium type lysimeters having a shallow, well-aerated water cover up to approximately 0.25 m over the tailings. Natural lake water was used for the fresh water cover and seawater for the saline water cover scenarios. The tailings showed significant surface reactivity and oxidation under both fresh and saline water cover conditions. The surface water quickly became moderately to highly acidic, and surface oxidation of the tailings resulted in increased dissolution and release of sulfates, iron (total), calcium, magnesium, aluminium, manganese, copper, nickel, zinc, lead, cobalt and silicon to the water covers. A moderate to slightly increased loss of total sulfides, including pyrite, chalcopyrite and sphalerite, occurred in the tailings surface layer to a very shallow depth. In comparison to the fresh water cover, the complete acidification of the saline water cover was delayed by approximately 30 - 40 days because of its additional available alkalinity. Whereas the rate of surface water acidification and release of aluminium and silicon were moderately reduced under saline water cover conditions in comparison to those for the fresh water cover, the release of calcium, magnesium, iron (total), copper, nickel, lead, zinc, sodium and potassium were enhanced. The mass transfer fluxes for dissolved copper, nickel lead, zinc and iron (total) from the tailings substrate to the surface water cover following surface water acidification were higher by 50 per cent or more in the saline water cover than those in the fresh water cover. This release was also reflected in moderate loss of pyrite, chalcopyrite and sphalerite in the very shallow upper surface layer of the tailings at the tailings-water interface, although the loss of pyrite in the surface layer was less pronounced. In both cases, the dissolution of aluminosilicate minerals moderated, to a certain extent, pH and acidity in the water cover.

Jan 1, 2003

By D Reid

Many of the relevant engineering behaviours of tailings are controlled to a large degree by the density of the material. For example, loose tailings are prone to brittle strength loss, while dense tailings are dilative (i.e. gain strength) at large shear strains. The critical state framework has been successfully developed over the past few decades to assess whether in situ conditions are contractive or dilative, and estimate relevant engineering parameters on that basis. Tailings comprising primarily silt-sized particles, when subaqueously deposited, often form a particularly loose state compared to subaerially deposited material of similar index properties. Such subaqueous deposition occurs in the decant pond area, where the tailings typically pluviate in quiescent conditions within a pond of standing water. Silt tailings deposited in such a manner have been observed to be extremely loose in a number of TSF investigations. Of particular concern, the deposited material in such cases appear to be significantly looser than can be reproduced in the laboratory - even using moist tamping, the sample preparation method which can usually produce the loosest samples possible in laboratory conditions. While the loose density of subaqueously deposited silt tailings is clear, in a well-managed upstream-raised TSF the decant pond is usually small and far from the perimeter embankments, however there are a number of examples where the engineering performance of such materials becomes relevant – for example, when historical deposition practices were poor, resulting in subaqueous deposition near the perimeter embankment. This paper outlines the geotechnical characterisation of a number of such subaqueously-deposited zones, compares the in situ state to that achievable in the laboratory, and discusses options for assessing the expected engineering performance of such materials when comparable laboratory tests are unavailable.

Jul 1, 2021

One of the responsibilities of the Melbourne and Metropolitan Board of Works is to provide a sewerage system for the metropolis of Melbourne which now contains over 2.5 million people. In providing this sewerage system it was necessary for the Board to embark on a large tunnelling programme some 20 years ago. As a result of this extensive tunnel construction programme, tunnel boring machines and shaft sinking methods have been developed to cope with the soft ground and soft to medium rock found in the southern and eastern areas of Melbourne where the majority of the recent tunnelling has been carried out. While in the last few years radical changes in construction methods have not been made, development has continued and improvements have been made, which have enabled the Board to extend the limits of the ground conditions in which it can efficiently construct shafts and also tunnels with boring Machines.

Jan 1, 1976

By Wetzeil N

High ambient temperatures combined with high surface humidity in the north of Australia and, in particular, the northern areas of the Northern Territory can make underground workplaces relatively inhospitable at certain times of the year. . Woodcutters' silver/lead/zinc mine, situated some 80 km south of Darwin, would be the most northerly underground operation of any significance in Australia. As such, during the build up to the wet season, it has a particular problem of ventilating a deep underground mine with already high dry and wet bulb temperatures at the surface. The Mine Management Act and Regulations mention only that workplaces shall be 'in a fit state for a person to work in or occupy'. Woodcutters therefore set in progress a Heat Stress Program to endeavour to set standards which would be more measurable and justifiable. The aim of the program was to compile a record of ambient atmospheric conditions in the working areas such that areas and/or work activities generating high ambient temperatures and humidities could be identified, quantified and qualified. Once the analysis stage of this program was completed, Woodcutters compiled a set of recommendations for the continued monitoring for, and control of, heat stress conditions to ensure that no underground employee was placed at risk from 'heat stress'. These recommendations are discussed in this paper.

Jan 1, 1994

The current drill-and-blast method of tunnelling is cyclic and, for this reason above all others, has a future application potential which is lower than that of continuous methods. There is scope for progress in several facets of today's drill-and-blast tunnelling. But even if each of its unit operations and the synthesis of these were to be optimised, this conventional method will, in the long term, fail to be a serious competitor for tunnelboring machines (TBMs), roadheaders and the like. If its role in tunnelling is not to decline at an increasing rate, drill-and-blast will need to be transformed into a continuous system. Boring and cutting machines consume considerable energy (and expenditure) in creating rock fragments which are smaller than those required by muck-handling equipment. In this respect, blasting is more efficient. Mechanical methods are also less versatile and flexible and, when planning proceeds on a basis of meagre or inadequate geological data, cannot be costed as accurately. Currently, research gains for TBMs and roadheaders are greater than those for conventional tunnelling. If (as is likely) the disadvantages of mechanical methods continue to be reduced at a greater rate, the swing away from drilling and blasting will gain momentum.

Jan 1, 1987

By R Farnf, M Pegden, S Hosein, T White

A number of theoretical papers have been published outlining the use of electronic detonators to limit peak particle vibrations levels, but few empirical studies have been undertaken and even fewer examples have been published of the use of such technology in the aggregates industry. This paper gives a summary of the research work carried out at two limestone quarries in the North of England, where a series of blasts were used to compare and contrast the use of electronic and non-electric detonators. The majority of blasts were carried out using the same burden, spacing and decked charge weight loadings. A methodology was established that could be used to reduce the peak particle velocities (PPVs) at two or more specific locations by using single-hole blast vibration signatures in conjunction with specific electronic detonator timing intervals. The initial study concluded that this was only possible if single-hole signature blasts were periodically recorded to establish the shape of the correct vibration envelopes as properties were approached. These wave envelopes could then be used as the basis for choosing the specific electronic detonator timing intervals to give the lowest PPV for the properties or locations concerned. This methodology was then used in the second study to access a large volume of aggregates adjacent to a working railway tunnel. The financial benefit for the company was to convert these additional tonnages of rock from being a resource to an exploitable reserve. The project involved careful blast design and the instrumentation of a number of boreholes to enable the results of blast monitoring exercises to be compared with predicted PPV results. The iterative process involved the vibration results being uploaded into æBlast LogÆ (an expert blasting database system developed by the Blasting and Environmental Research Group at the University of Leeds) and analysed to produce predictions ready for the next blast.

Jan 1, 2007

Mathematical economic models for assess ment of technological progress in the mining industry in the USSR are discussed. The models are based on a simple index, TT which approxi- mates the rate of growth of the people's living standards. However, for application in the mining industry it is necessary to incorporate various parameters to account for the dynamic charges in the geological, mining and other technological conditions. Derivations of the models are shown and examples of results are Included.

Jan 1, 1977

Blasting in Norwegian mines is often carried out by contractors who tend to look for the cheapest solution, without concern about fragment quality. The requirementsfor a contractor are usually only related to the maximum size of boulders and the quantity per month. Even when the owners of the mine are responsible for blasting, very little effort is made to optimise the blasting process. This paper presents test methods which were used and results from small-scale and full-scale blasting tests. In the small-scale tests, cubes 500 x 500 x 500 mm of four different rock types were blasted in a chamber, using two types of dynamite explosive. The velocity of detonation (VOD) for the dynamite explosives was 3000 m/s and 6000 m/s respectively. Three cubes of each rock type were blasted with each type of explosive, and a total of six cubes of each rock type was used. The entire muckpile (approximately 350 kg) was- sieved and weighed after each blast and fragments between 8-16 mm were tested for impact values and flakiness. The results of these tests clearly showed improvement in fragmentation the closer the acoustic impedance ratio of the explosive (VOD x density) over the rock (Cp density) was equal to one. The results also showed that the quality of the fragments (in terms of impact values) tends to be better when the cubes are blasted with the high velocity dynamite.

Jan 1, 1995

By Zamel G. I, Zenari L. P

Technological developments in modem Tunnel Boring Machines (TBMs) and associated back-up equipment are offering significant alternatives for mining operators to consider, in the selection of equipment for coal mine development drifts, roadways, longwall gate roads as well as metalliferous mining declines and development drives.Greater flexibility in handling variable ground conditions, muck disposal and radius of turn as well as advance rates, are just some of the areas where modem TBMs can accomplish the flexibility that mine operators require to achieve cost-effective developments.Compact TBMs are achieving this acceptance because of the fundamental design of a shielded machine containing electrics and hydraulics within the forward shell, ability to achieve tight radius of curvature and grades, and ability to provide highly flexible support systems to meet all possible ground conditions.However, a single TBM design will not suit all mine developments, as each development method - while having common goals with all mine developments - will also require certain unique criteria to be fulfilled.

Jan 1, 1993

By Millett R

In January 1989, Western Mining Corporation (WMC) acquired the Perseverance and Rocky's Reward orebodies and associated infrastructure from the Agnew Mining Company (AMC). AMC had closed the operation in August 1986 and it had been on care and maintenance since that time. To return the operation to full production as quickly as possible it was planned to mine the Rocky's Reward orebody by opencut mining and treat this ore whilst the underground Perseverance workings were rehabilitated. Removal of overburden from Rocky's Reward thus commenced immediately with a target of April 1989 for delivery of the first ore to the concentrator. Extensive rehabilitation and upgrading of the concentrator commenced in late January, and continued in stages for an 18 month period. The first stage consisted of overhauling all existing equipment and completing a crusher upgrade commenced by AMC prior to the mine closure. During this period, it was necessary to recruit a workforce and re-establish all the required support structure. In late April the plant commenced commissioning trials on mullock. The first ore was crushed on the 11th May 1989 and concentrate produced the following day. From May 1989 to June 1990 the plant was producing nickel concentrate whilst further upgrading continued. During this period, the flotation capacity was tripled by installation of a bank of eight Wemco 144L flotation cells in rougher-scavenger duties and two 12 metre by 2 metre diameter columns in cleaning duties. The existing vacuum drum filters were replaced by two Larox PF32 pressure filters, eliminating the need for solar drying and allowing the flash drier to be fed direct from the filters. These, along with a major borefield expansion and further work to the crusher increased the nominal plant capacity from 600,000 to 1,000,000 t/yr. The plant achieved the 1,000,000 t/yr rate in April 1990.

Jan 1, 1991

By S M. Arndt, D Tyler, F Reusch

Although significant advances have been made in understanding the mechanics of pit slopes, numerical modelling hasnÆt significantly impacted on the reliability of the design process. It is well known that legacy modelling approaches donÆt simulate large slopes well. In recent times, the emergence of very large finite element (FE) models with more than ten million degrees of freedom and the ability to simulate a large number of discrete structures, has allowed a step change in the simulation precision for slopes. The model size allows global and local effects to be realistically simulated in one model for the first time and the process can be better integrated into normal open pit slope engineering processes. Some examples of simulation of very large open pits are shown that demonstrate the challenges and some recent advances in modelling large slope behaviour. Significant limitations in the current measurement and observation regimes of open pits have been identified.

Jan 1, 2007