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By Susanto A

As part of the current NERDDC funded project studying Dragline/Hopper/ Crusher/Conveyor systems for overburden removal, an investigation was carried out to assess the feasibility of automating the swing-to-dump phase of the dragline digging cycle in order to main- tain consistent performance of spotting the bucket above the hopper prior to dumping. The study involved design of automatic position controls for the hoist, drag and swing drives and simulation of detailed mathe- matical models of the three electromechanical systems and their associated electrical control schemes. The design of the hoist and drag systems to position the bucket in the boom plane is relatively straightforward. Simulation results show fast and accurate performance, with no evidence of interaction between the two drive systems through the ropes. The design of the swing position control system involves special strate- gies to cater for variable inertia and to damp the pendulum oscillations of the bucket. The use of a bucket pendulum model and variable dynamic compensation embedded within the feedback control loop, along with optimal speed/angle slowdown trajectories, has yielded fast and damped positioning responses under simulation.

Jan 1, 1989

By Hagan T. N

Quite apart from economic considerations, the following performance parameters must be considered when selecting an explosive for a particular blasting operation. 1. total energy yield/kg, and more particularly, strain energy/kg and bubble energy/kg of charge 2. charge weight/m of blasthole 3. sensitivity of the charge 4. water resistance of the charge The effective division of an explosive's total energy into strain energy (SE) and bubble energy (BE) is explained as is the influence of each energy component on blast results. Because some rocks require a high strain energy for effective breakage, while others are most satisfactorily fragmented by bubble energy, values of SE and BE are more meaningful than those of total energy. Unfortunately, our extensive knowledge of the effects of certain variables on total energy has not yet been completely supplanted by the influence of these variables on SE and BE values. Relative SE/kg and BE/kg values are presented for a range of explosives. The 'charge density of ammonium nitrate/ fuel oil (ANFO)-type explosives is essentially constant throughout the length of the charge; because of their compressibility, slurry

Jan 1, 1974

By Skaviniak M

Some better perspectives applying to the exploitation and dressing of polymetallic ores in the Banskfa. gtiavnica-Hod- rusea Ore District are supposed to be achieved after a suc- cessful investigation and proving there the existence of deep-seated mineralization as well as due to increasing de- mand for non-ferrous metals and consequently to higher mar- ket prices of those recently noticed. With respect to the present situation in mining and to the further technical development as well, a several times higher exploitation may be in this region expected, especially in the deeper .eated parts of the deposit. When solving the tasks of a complex economic exploitation over the whole region, consi- derable attention is paid to regional relations and impact studies (due to expected exploitation and ore dressing but also to very difficult problems of dewatering (drainage pro- blems-). It will be first of all necessary to find there an equilibrium between the consequences resulting from the re- naissance of mining industry and environmental requests un- dispensable for the city of Banska 9tiavnica and the other neighbouring towns in the vicinity of mining plants.

Jan 1, 1988

Results of investigations on adsorption and desorption of CO M CH and a mixture of the two gases are described.4 Results showed that even when the equilibrium conditions contains 50% Co and 50% CH4, the gas emission in the initia' stages will contain as much as 80% CH . 4 The temperature has a small effect and so also particle size for 1.4-11.2mm. The ratio of CO2/CH gases adsorbed in coal samples depends upon t4he equilibrium pressure and this ratio decreases with pressure. Results of field tests support laboratory studies.

Jan 1, 1988

By Cocker J, Urosevic M

Seismic methods have become common for the detection of low-throw faults ahead of underground coal mining. Surface seismic methods cannot theoretically be used where dykes occur, because seismic waves transmit from the surface down to the seams, and reflect back to the surface. Consequently, where sub-vertical structure such as dykes occurs, the surface seismic method fails.The ability of seismic methods to image dykes depends on the geometry used, the dyke thickness and the seismic wave propagation mode in relation to dyke composition and internal structure. Surface seismic methods find it difficult to distinguish between faults/fractures and very thin dykes (1-2m in thickness) when the dyke's thickness is less than the seismic wavelength. Consequently, borehole seismic methods have to be used to detect the presence of such thin dykes.

Jan 1, 1998

By Cunningham J. C

JUST prior to the war the Broken Hill South Ltd: raised, on the average, 6628 tons of ore per week, all of which was crushed and treated in the 4-section gravity mill and the slime flotation plant, for the recovery of lead concentrate carrying silver. The sandy residues from that treatment were railed to the treatment plant of the Amalgamated Zinc (De Bavay's) Ltd. for the recovery of zinc concentrate by flotation, on the joint account of both companies. Subsequent to that-since 1916-approximately 1000 tons of old dump slime were also treated weekly for the recovery of lead and silver as slime-lead concentrate.PLANT CAPACITYUnder this programme the Babcock and Wilcox boiler plant of 8 boilers was taxed to such an extent as to call for the installation of two additional boilers, each of 2690 sq. ft. of heating surface and 55 sq. ft. chain-grade area.The electric generators and the air compressors of the old powerplant were also loaded to their maximum capacity. In view of the fact that the old power-plant had been added to from time to time since 1901, and that further extension was notpossible, and as it was not, moreover, an economical arrangement, the whole question of power generation was reconsidered. The considerations that determined the installation of entirely new plant were as follows:(1) The need for more compressed air for underground work and more electric current for the extension of the slime-flotation plant for the recovery of zinc, as well as lead, as slime concentrates. Provision of additional power was also deemed advisable for the...

Jan 1, 1921

By S KandT

The FalTmT iron ore deposits are located in the so-called æBirrimianÆ volcano-sedimentary complex that extends in a general NE-SW direction across eastern Senegal and part of Mali and Guinea. The rocks underwent folding and greenschist facies metamorphism, as well as various events of granitoid emplacement. The deposits form part of the DialT-DalTma Series of the Birrimian Supergroup and were subjected to contact metamorphism. The Fe-mineralisation occurs as primary magnetite within the metamorphic aureole. Supergene oxidation (martitisation) of this mineralisation produced the hematite-rich iron deposits that can be seen as prominent hills across the plains of this south-eastern corner of Senegal. BRGM of France and Miferso (SociTtT des Mines de Fer du STnTgal-Oriental) have conducted several phases of prospecting since 1957. Their aim was to delineate the hematite deposits and to assess the grade, beneficiation characteristics and marketability of the iron ore. A feasibility study by Fluor Daniel was completed in 1992. Results indicated that, at the time, the resource could not compete in the international arena in terms of size and accessibility. The growing iron ore market and additional available resources in the area now challenge the 1992 feasibility study results and put the old kid back on the iron ore block. The project faces some mining challenges, such as the amount of magnetite in the hematite product that will be acceptable to the market. Previous project evaluations only considered the secondary hematite deposits as economically viable. It is therefore important to accurately delineate the magnetite/hematite contact zone to optimise the resource tonnage. Project logistic constraints also exist in terms of railway access and harbour facilities. The resource is, however, well situated for the European iron ore market and aims to find a place in the rapidly expanding iron ore seaborne trade.

Jan 1, 2005

Over the 20 years to 1990 the Australian mining industry, presently worth some $A60 billion, generated a negative real rate of return (McDonald, 1992); not surprisingly under-performing the returns from bonds and industrial equities. Over this same period more than $A70 billion was invested in expanding the Australian mineral industry.

Jan 1, 1993

By Ritchie I

Copper minerals are often associated with gold ores. These create processing problems since cyanide solutions are not selective for gold alone. Copper minerals are also leached by cyanide, and typically each one per cent of `reactive' copper in the ore consumes about 30 kg t 1 cyanide. Once in solution, copper cyanide species create further processing problems as they adsorb onto carbon along with the dicyanoaurate ion. These problems make conventional cyanidation of gold ore uneconomic if the ore contains too much copper. As a result, methods of economically processing gold-copper ores are becoming of increasing importance.One of the more promising methods of treating these ores is by selective leaching of the gold by an ammoniacal cyanide solution, a method first described by Hunt in 1901. This method is already in commercial use in Mauritania, treating copper/gold tailings. In general terms, the addition of I - 2 g U1 ammonia to a standard cyanide leach solution causes a significant increase in gold extraction and decrease in copper extraction. However, early testwork on this system has concluded that the optimal leach conditions are critically dependent on ore composition, and the mechanism is not well understood, making predictions of best conditions impossible.

Jan 1, 1997

By M Warren

The professional geologist or engineer on a mining operation has a particular view of their operation. This is based on the factors of the operation that have a direct impact on the daily work program of the professional, such as production rates and grades. The view that would be taken by a financier who is called upon to support the project may be somewhat different. The value of the operation to the financier is in its ability to generate surplus cash for its owners and thus repay the debts to the financiers, with as low risks profile as possible. A number of tools are used to test the sensitivity of the project to variations in the key cost/revenue drivers. The Financier may call on a team of technical specialists to assist with the assessment of the cash flow and risk profile and to monitor the development of the project. The ability to offset this risk, as all projects have some degree of risk, may be a key factor in determining the level of financial support to be offered.

Jan 1, 2002

By M Binks

This paper presents a case study that describes the selection, development, engineering and construction of a process plant for the biological oxidative pre-treatment of a refractory pyrite-arsenopyrite gold ore flotation concentrate. Prefeasibility and feasibility study resource modeling, metallurgical testwork, and environmental and engineering studies are outlined. Options considered for oxidation of the ore, which examine cost, risk, operability, recovery, engineering and environmental aspects are compared, with particular reference to pressure and biological oxidation. The BIOX« biological oxidation process was selected as the preferred oxidation process and the flow sheet for this process is presented. Selection of the BOIX« process resulted in special requirements for the feed preparation circuit, residue treatment and disposal, materials of construction and engineering. Use of a biological process in ore treatment also introduces particular process and engineering risks the management of which are discussed.

Jan 1, 2004

By Granholm S

The current emphasis within the mining industry to reduce the cost of production has stimulated interest in the field of maintenance and operational reliability of capital intensive mining equipuent. The failure consequences of these machines have major safety and economic implications for a mine operator. The reliability centered maintenance (RCM) approach has been found cost effective for equipment maintenance and for achieving high level system perform- ance by many organizations such as airline, military, chemical, process and manufac- turing industries. In this paper an attempt has been made to describe in brief the basic concepts of a RCM approach, the methods of RCM analysis and its cost effectiveness for maintenance of equipment. Since this approach is comparatively new for the mining industry, suitable examples are given to illustrate the case.

Jan 1, 1988

The Project Financing Industry is currently being expanded en- compassing greater competition due to the improved worldwide economy. This has meant that money is in greater supply than demand for both loan and equity investment and is available for larger and higher risk ventures. The consequence of this is that the Project Financing Industry should be better able to provide more innovative forms of financing to meet the needs of mining and petroleum companies, regardless of size. Large mining and petroleum companies in Papua New Guinea should therefore be looking for ways to raise equity funds for exploration in greenfield areas, diversifying their risks through acquisition, and seeking to reduce their costs of borrowings. The small to medium sized mining sector should be looking to raise equity for increased ex- ploration on tenements and, where possible, to raise borrowings to fund expansion and further development of their projects. In summary, it is a period during which companies should take ad- vantage of available funding to augment their strategic plans and increase their long term returns to shareholders.

Jan 1, 1997

Lithocaps are potentially voluminous zones of advanced argillic and associated argillic alteration located above the subvolcanic intrusive environment. They constitute exploration objectives for epithermal and porphyry-type deposits. High-sulphidation epithermal deposits may be sought within lithocaps, whereas low-sulphidation deposits may exist on their edges. Porphyry Cu-Au/Au deposits may be accessible beneath lithocaps if systems are telescoped sufficiently. Oxidation of the basal, pyritic parts of lithocaps may promote supergene sulphide enrichment under appropriate tectonic and climatic conditions.

Jan 1, 1995

Acid rock drainage (ARD) derived from sulphide oxidation and the associated metal leaching is the most significant environmental issue facing the mining industry today. Under given hydrological and biogeochemical conditions, the local geology and mineralogy largely control the formation of ARD. The involvement of a geologist is therefore essential in minesite ARD assessment and prevention. The relevant tasks that a mine geologist may undertake at three major phases of a mining project are briefly described. Additional knowledge that a mine geologist should acquire in order to achieve proficiency in ARD assessment is also suggested.

Jan 1, 1993

By Dendyuk TV

The possible use of combined (flotation/magnetic separation and magnetic separation/flotation) technologies involving the new flotation reagent systems for upgrading the iron ore concentrates, low grade manganese products and beneficiation of graphite-bearing dusts from integrated iron-and-steel works has been shown. It has been found that the absence of magnetic flocculation phenomenon worsens the reverse cationic flotation of oxidised iron ore concentrates and direct flotation of low-grade manganese products which require the use of modifiers possessing the flocculating properties. The synergetic mixtures of polymers have been proposed to be used as modifiers, ie polyacrylamide (PAA) with carboxymethyl cellulose (CMC) and polyacrylamide with industrial lignosulphonates (LST)

Jan 1, 1993

The outlook for suppliers of energy to the expanding economies of the Pacific Basin region is essentially positive, but particularly for exporters of high quality steam coal. This paper argues that economic growth in the Pacific Basin region has exceeded world economic growth for some years and that this will continue to be the case for the next decade at least. It looks briefly at the link between economic growth and energy demand and at the relationship between energy demand and the demand for electricity.Changing preferences in fuel mix for electrical generation in the region are noted and tentative forecasts made about variations in this mix. The pros and cons of various forms of fuel used to generate electricity are considered from the point of view of the consumer.

Jan 1, 1990

By King MN, Travis IC

PISCES - the Planning and Information System for Coal Export Services has been developed by Port Waratah Coal Services (PWCS) to ensure the efficient and economic operation of the Hunter Valley Coal Chain. PISCES is a computer based integrated information and management system to coordinate operations commencing at minesites through the coal chain to shiploading at the Port. The PISCES system comprises a central database around which a number of planning modules interact. These include interactive programs for train planning and timetabling, stockpile management, berthing analysis and a coal shippers enquiry system. PWCS has previously developed - number of computer based systems for planning, controlling and monitoring complex coal handling operations and the extension of the PISCES system to the Hunter Valley Coal Chain is another initiative to assist the Hunter Valley Coal Export Industry in looking confidently towards the Future.

Jan 1, 1987

By P Kumar, J Safarian

Understanding how ore interacts with flux particles at elevated temperatures to create molten slag is crucial since it governs the dynamics of a chemical reaction. This study explores the smelting behaviour of pre-reduced Nchwaning manganese ore when combined with lime, with the objective of examining the evolving interaction between pre-reduced ore particles and lime over time. The research sheds light on the interaction between solid and liquid and the phases that emerge during this process. To achieve this, a sessile drop furnace was employed to rapidly heat the materials positioned adjacent to each other on an alumina substrate and to observe the smelting process as it unfolded over time. This method allowed for the direct observation of the melting temperatures and the flux-ore reaction progression rate, and the potential disruptive events that might occur. By comparing the molten interfaces of the fluxed materials at various time intervals, this study provides insights into the relative rate of slag formation from the two materials. The results indicate that the main slag formation initiated at approximately 1400°C and continued to advance with time, with complete mixing occurring around 1500°C. The possible phases formed were identified using Scanning Electron Microscopy and modelled using Fact Sage thermodynamic software. In addition, the iron particles in the pre-reduced Mn ore were separated and settled from a rich MnO-containing slag. It was found that the separation of molten iron droplets from the slag depends on the rate of solid MnO particles dissolution into the adjacent slag phase.

Jun 19, 2024

By T Smith

The evaluation of a new mineral resource and its economic viability is critically dependant on the quality of the assay data as it is this data that defines the grade of the resource. However, all too often the procedures of sampling and chemical analyses used to generate such data are neglected or given little consideration until final modelling and evaluation are under way. This approach frequently requires large reassay and/or re-sampling programs to be undertaken to validate or to improve the integrity of the data base. This paper outlines a step by step approach to ensure quality data is achieved and then maintained throughout the entire exploration and resource development program. This involves the use of correct field sampling methods, assay methods designed to give the required levels of accuracy and precision and quality procedures in place to monitor the effectiveness of the overall process. Thorough documentation is an overriding and necessary part of the entire process. Practical examples are given to demonstrate the use and value of these methods.

Jan 1, 1998