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By Restarick C. J & Stewart P S B, Kelsall D. P

Over a four-hour period of steady plant operation samples were taken at regular intervals from points within the grinding and flotation circuits. Size fractions of each composite sample were analysed for lead and zinc values and a comparison made of the behaviour of the lead, zinc and gangue minerals, size by size throughout the whole circuit. Analysis of the breakage behaviour using dynamic mathematical models gave the rates of breakage of each size fraction of each main component. Simulated grinding experiments showed that the main grinding circuit had sane reserve capacity. In the lead flotation circuit all lead values between 150 mesh (Tyler) and 5 microns had excellent flotation characteristics, and a major proportion had a high rate of flotation which was practically the same for all sizes. Increase in overall lead recovery would require improvement of the flotation behaviour of ultra-fine lead minerals. These were slow floating and were responsible for approximately half the lead losses in the final zinc concentrate and one third of the lead losses in the final tails.

Jan 1, 1980

By Mousset-Jones P, McPherson M. J

Underground airways are characterized by irregular shape and uneven surfaces including large-scale natural roughness, fractures, and a super-imposed sand roughness. Swirls in the grooves of the wall and separation because of the periodic variation of the open cross sec- tion, due to the blasting patterns, make it almost impossible to calculate average con- vective heat transfer computationally on the bases of the geometrical description of the surface. However, dimensionless friction factors can be used to characterize the surface effect of an airway and an analogy between heat and momentum transfer can be applied to calcu- late an average convective heat transfer Coefficient.

Jan 1, 1988

The Newmont Waihi Operations are centred on the Martha mine at Waihi, New Zealand. The mine has produced over 6.6 million ounces of gold from both openpit and underground sources since operations began in 1878. The current open pit operations commenced in 1988 and in the year to 30 June 2002 produced 129,790 ounces of gold at a cash cost of USD122 per ounce. This paper provides an overview of current operations and future directions.

Jan 1, 2002

By Wood CJ, Davis JJ, Askew H

A dynamic model of a dense medium circuit has been developed and tested against plant data. The model shows the response of the circuit to both controlled (changes in specific gravity set point or changes in circuit coal feed rate) and uncontrolled changes (changes in raw coal moisture, loss of raw coal feed) in operating conditions. The model is built up from dynamic models of the individual sumps, pumps, pipes, splitters, magnetic separators and automatic controllers in the circuit. The model can be used for design of automatic control loops and for investigation of possible process modifications such as changes in water addition points. This paper describes the model construction, the testing of the model against actual plant data and gives some examples of its use in investigating plant response to changes in operating conditions.

Jan 1, 1978

Mineral exploration is the business of finding and defining ore deposits. Ore bodies are developed into mines and mines supply every mineral and metal upon which our society is built. Whether it be steel for our bridges, cement and aggregate for our concrete, coal for our power stations, copper for our wire, phosphate for our fertiliser or gold for our jewellery it first must he found, then mined and processed before we can use it. There is no other way.

Jan 1, 1993

By Moore A. J

This paper describes the use of a wavefront reinforcement model which has been developed to supplement established charge mass scaling methods. The model allows for the time taken for blast vibration wavefronts to travel from each blasthole, and has been successfully used to explain the reason for directional increases in both air and ground vibration in certain situations. The model has been used to identify wavefront reinforcement due to the propagation of air vibration and ground vibrations in certain situations. The paper includes a throw (or cast) blasting case history which provides multi-station evidence of the strong directional nature of wavefront reinforcement.

Jan 1, 1995

In the first half of 1987 two four metre diameter raise bore holes were drilled at the Olympic Dam Project for ventilation purposes. The first hole, 476 m x 4.0 m diameter was completed in 96 days, 35 days longer than scheduled. The second hole, 407 m x 4.0 m diameter was completed in 39 days, 2 days ahead of schedule. Both holes were drilled with a Robbins 121R rig using a Wirth head that consisted of 23 face cutters and 5 side cutters, supplied by a contractor. After the sites were located a grouting program was carried out to help seal off an aquifer between 160 and 180 m below the surface. Cavities discovered in the Andamooka Limestone were filled with concrete. Because of the overlying dune sands and clay both sites were pre-sunk to the competent Andamooka Limestone.

Jan 1, 1988

By Horrocks KRS, Smitham JB, Ellison JF

This paper describes the development and installation of equipment for continuously measuring separating density in the dense medium cyclone circuits of the four million tpa Port Kembla B/C plant coal washeries. Monitoring equipment consisting of magnetic coils and differential pressure cells were installed in U-tubes taking the full flow of magnetite from the drain sections of the product drain and rinse screens. The monitoring equipment measures overflow magnetics concentration and overflow density continuously and has operated since 1989. From these measurements and calibration trials, the separating density of operating cyclone modules can be inferred reliably. Variographic analyses of the data show that medium density control to +/- 0.002 RD units and separation density control to +/- 0.007 RD units are achievable. Either method for measuring separation density can be used with approximately the same accuracy, although the overflow density measurement technique suffers from the need to have regular flushing of the Dp cells which complicates the signal analysis. Data from the plant shows that separation density can be controlled by regulating medium density, but the assumption of a constant offset between medium density and separation density is erroneous.

Jan 1, 1993

The standard charge weight scaling laws imply that only one particular delay (that possessing the maximum instantaneous charge) contributes to the ppv. However, the present analysis clearly demonstrates that a varying number of blastholes contributes to the ppv. This number also increases with distance, x, between the blast source and the detector, and is caused by waveform broadening due to attenuation. Thus the operative charge weight, itself, is also a function of the distance, and so makes the standard charge weight laws difficult to implement. If the delay time scatter is neglected, then, under certain conditions, relatively simple expressions can be derived for the ppv magnification, FN, as a function of the number, N, of blastholes. When the influence of delay scatter and random fluctuations in each blasthole vibration is included using Monte Carlo simulations, then, to a first approximation, the condition FN=KNx applies, where KN is a constant dependent upon N. Unfortunately, however, for any particular blast this condition cannot be distinguished from the standard charge weight scaling law. The dependence of ppv on N would only be apparent if blasts of differing N were to be compared in an otherwise identical environment. Since this situation is very difficult (if not impossible) to realise, then the influence due to N, although significant, goes largely undetected. Another problem associated with standard charge weight scaling laws is the difficulty of accurately assessing the appropriate charge weight, even if attenuation broadening is neglected. For example, if a number of blastholes are very close, then they experience a vibration interaction which is non-linear. However, if the same blastholes were to be widely spaced, then the separate vibration signatures add linearly. The standard charge weight scaling law fails to distinguish between such linear and non-linear regimes. Unfortunately, in many production blasts, both regimes exist throughout various portions of the blast spatial pattern and so makes it difficult to determine the operative charge weight. The solution to the combined influence of waveform broadening and linear/non-linear interactions will obviously require substantial future research. A possible solution may be found in the use of numerical dynamic codes.

Jan 1, 1990

By Morris B. J

Soil air samples taken from the top one metre of the soil profile, were measured for C02 and 02 using portable field analysers at a number of sites of known sulphide mineralisation in South Australia. Carbon dioxide anomalies were detected over actively oxidising sulphides during autumn and winter following recent rainfall. Anomalies were not detected where no oxidation was occurring, where seasonal conditions had been very dry, or where the sulphur content of the ore was low (

Jan 1, 1993

By Coppock BW

Sintering of lead and zinc concentrates is practised by Sulphide Corporation Pty. Limited to provide both desuiphurised lump sinter feed, for simultaneous reduction to zinc and lead in the Imperial Smelting Process blast furnace, and sulphur dioxide gas for sulphuric acid manufacture. From November, 1969 a 20 percent increase in production rate has been obtained through improvements in operating technique. A gradual increase in bed permeability was achieved by modifications to the feed mix conditioning equipment and by improving moisture control. However advantage could not be taken of the higher permeability to increase sulphur elimination because the hardness of the lump sinter decreased. Higher throughput, better quality sinter and more stable sintering conditions were however made possible by simultaneously: 1. reducing segregation and compaction in the sinter bed, by narrowing the discharge opening of the main layer feed hopper, 2. reducing the sizing of sinter returns to give a closer size spectrum of particles in the feed mix, and 3. increasing the sulphide sulphur content of the feed mix to give higher bed Temperatures.

Jan 1, 1972

Lightweight polymer grids have recently been introduced to the mining industry. They are currently being used for roof and rib control, longwall shield recovery, safety guarding or barricade, highwall screening, internal reinforcement of gunnite/shotcrete applications, sub-base reinforcement, construction of steepened slopes, retaining walls, mine reclamation (i.e. erosion control, turf reinforcement), and in numerous mining waste related projects. These polymer mining grids utilize a strong, lightweight polymer, usually special grades of polypropylene or polyethylene. High tensile strengths are achieved by molecular orientation of these polymers in the manufacturing process. The first step in the manufacturing process is to extrude the polymers into thick continuous sheets. These sheets are then punched, and drawn into open grid structures. Aperture size and configuration are controlled by the geometry of the punched hole and the degree to which the grids are stretched. The drawing process is the key to the molecular orientation required for the tensile strengths. These long chain polymer molecules in their natural state have a random orientation. When stretched, the molecules are pulled into a parallel alignment, thus creating a lightweight product with tensile strength comparable to Steel.

Jan 1, 1992

By Mutton B. K

Hilton Mine is being developed as an integrated component of the Mount Isa operation, to achieve continuity of silver/lead/zinc production well into the next century. The mine has a chequered history from its discovery in 1947 through several periods of intense development activity, each of which has been curtailed due to the further development of the Isa Mine operation. This era has now passed; to sustain increased production rates at Mount Isa, there is a requirement for Hilton ore in 1989. The decision was made in 1983 to accelerate the programme of Hilton development by installing skip hoisting facilities in the main service shaft (P49), to facilitate the development of the mine to pre-production status. The Hilton development plan provides for the mining of selected orebodies, a broadening of the underground exploration drilling programme, and the establishment of significant mine infrastructure. Several technical challenges have been identified as important. The Hilton orebodies, although occurring in the same rock type as Isa Mine, are more faulted, jointed and intersected by intrusive dykes. The ore is more variable in terms of ore continuity, boundaries, grade and metal distribution and the mineralogy more complex. As a consequence the development of this project consists of a co-ordinated programme of mine exploration and development, rock mechanics investigations and metallurgical research and development work. Production will commence in 1986 at a rate of 1000 t/day using mechanized cut and fill techniques. It is planned to introduce sublevel open stoping and by 1996/97 the production rate will be 2.5 million t/yr.

Jan 1, 1986

Rheology is the science which deals with the deformation and flow of matter. Thus rheology is concerned with the flow of any material. The mining industry is concerned with digging things out of the ground, extracting the good stuff and throwing away the bad stuff. In the upgrading processes associated with mining, ie mineral processing, wet techniques are used where the primary material being handled is a particulate fluid, ie a suspension. After the processing operation, with the concentrates extracted, what is left behind generally is a wet material in suspension form, which may or may not contain reagents harmful to the environment. The amount of waste generated in any of the mining processes is large, in fact, the mining industry is the largest generator of solid waste in Australia. In order to minimise the waste generated within the industry it has become of interest to handle the particulate fluid wastes, or suspensions, at high concentrations, thus removing water and some of the reagents which may be harmful to the environment. The resultant highly concentrated suspension is a non-Newtonian fluid. Rheology deals with the flow of non-Newtonian fluids; therefore a combination of rheological understanding of high density suspensions, in conjunction with an understanding of the environmental problems being faced by the mining industry, can and has led to improved methods of waste disposal in the industry, ie waste minimisation. This paper describes the progress that has been made in the development of dry disposal technology in the mining and minerals industry in Australia.

Jan 1, 1998

At the Highway gold deposit, 37 kilometres south of Charters Towers, gold mineralisation occurs in several stratiform layers and is enriched near the surface by lateritic weathering. The host rocks of the mineralisation are ferruginous and baritic, intensely sericitised, kaolinised and silicified rhyolitic tuffs and pyroclastics of the Cambrian-Ordovician Mount Windsor Volcanics. The geology of the deposit is illustrated in Figures 1 and 2.Forty-six reverse circulation percussion drill holes were completed by North-Queensland Resources N.L. for a total of 2,093 metres of drilling to further outline and test the open pit resource. The drilling indicated a resource of 171,000 tonnes averaging 4.4 grams per tonne gold and 5.0 grams per tonne silver.A shallow initial pit, approximately 30 metres deep, has been designed to mine the high grade upper portion of the western stratiform layer and part of the eastern layer. This initial pit is designed to mine 45,400 tonnes of western mineralisation at an average grade of 7.84 grams per tonne gold and 22,200 tonnes of eastern mineralisation at an average grade of 1.42 grams per tonne gold. Waste is estimated at 110,900 tonnes.

Jan 1, 1986

High sulphur volcanic-hosted hydrothermal environments are favourable geological environments for gold mineralisation. Numerous world-class gold deposits including Pueblo Viejo (Dominican Republic), Goldfield (Nevada), EI Indio (Chile), and Wa

Jan 1, 1994

By Roe P, Lowell A

This paper outlines software development and design work carried out by Mincom Pty Ltd in collaboration with Capricorn Coal Management (CAPCOAL) for computer based design of rehabilitated strip mine landforms at German Creek Mine. Current developments and future application areas for this software are also discussed in relation to other mines in Central Queensland. The development program was initiated in response to statutory requirements placed on mining companies in 1990 to produce a five year Plan of Operations which was to include a contour plan of the final rehabilitated mine landform at the end of the five year planning period. This plan was to be submitted to the Department of Resource Industries (DRI) by 1 December 1990. Due to the limited time given to prepare the plan, a work program was formulated in collaboration with Mincom Pty Ltd to develop suitable software to carry out the design work and provide the required plans and quantities. The software had to include computer based methods to allow design of the proposed landform in line with the rehabilitation strategy adopted by CAPCOAL at the time.

Jan 1, 1991

The paper, one of two papers on the Queensland Railways Brunswick Street tunnels presented at the VIII Australian Tunnelling conference, describes documentation, tendering and construction aspects.Tender documents were written to reduce the risk taken by the contractor. Details of tenders received are analysed and the changing industrial situation at that time described.Construction aspects covered include mobilisation, major equipment, tunnelling equipment and manning. Program and progress are reported including industrial relations and advance rates for Mitsui-Miike S-200 and S-65 roadheaders. Cycle times and performance in terms of cutting rate and pick wear are provided for the roadheaders.

Jan 1, 1993

By Trois P

A fully instrumented and bench-mounted diamond drilling machine, purpose designed and built, has been used for investigating the effect of aqueous solutions of various chemical compounds when used as drilling fluids. The rocks investigated were andesite, basalt and granite, the chemical compounds were alkylamines, with various hydrocarbon chain lengths, aluminium chloride and dioxane. Rotation speed seems to be one of the major factors affecting the emergence of mechanochemical effects as the results obtained with aluminium chloride clearly indicate. Penetration rate is either unaf- fected or enhanced by the presence of certain compounds, such as aluminium chloride. On the other hand, penetration rate diminishes when the drilling fluid contains dioxane and exhibits an apparently unpredictable behaviour with alkylamine solutions, although it appears that an increase in hydrocarbon chain length usually equates to an increase in penetration 1. Full Professor, Mining and Mineral Dressing Department University of Cagliari - Italy 2. Associate Professor, Mining and Mineral Ikea- sing Department University of Cagliari û Italy rate. Rock texture seems to have a pronounced effect on test repeatability. With hexadecy- lamine acetate solutions in concentrations ranging from 10-5 to 5 .10-4 molò dm 3 and 41.88 radòs-1 rotation speed, 46 % increments in penetration rate of andesite were observed, with respect to water, whereas penetration rate decreased in basalt by as much as 60¦%o when a dioxane solution was used as drilling fluid. An interpretation of the observed effects is proposed in the light of current knowledge of solid state physics and physical Chemistry.

Jan 1, 1992

By Bratt G. C, Horsham T. R, Langlois D. R

Mercury is precipitated from weakly acidic sulphuric acid plant waste liquor at the Risdon Works of the Electrolytic Zinc Company of Australasia Limited. Factors determining the choice of process and reagent, as well as details of process development including scale- up, and the time scale of implementation are outlined. The plant is designed for a maximum flow of 120 m3/h.of liquor containing mercury and saturated with sulphur dioxide. Mercury is precipitated by fluidised beds of aluminium pellets contained in lead columns. Liquor is then clarified with plate and frame presses. Experimental work on the mercury precip- itation reaction was conducted in three phases involving a scale-up of 100 times in equipment size. Extensive pilot filtration work was carried out on a 1 m2 press. Scale-up of 120 times was required for specification of plant filters. The basis of scale-up is outlined.

Jan 1, 1977