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By Bourke J. H, Ashcroft T. B

Many changes have occurred in the world market for manganese over the last five years. Among these, the emergence of divided steel processes for the hot metal refining of pig iron is affecting the use of both ferruginous manganese ore and ferro manganese, at this stage particularly in the Japanese steel industry. Subsequent demand for higher quality manganese materials is promoting the use of thermally beneficiated products such as sinter. In addition, many processes are being developed for the direct smelting of fine manganese ores, of which plasma technology is the most advanced. Cost pressures and product quality requirements are encouraging pre- viously self sufficient countries such as The People's Republic of China and the USSR to import high grade manganese ores to supplement indigenous lower quality supplies. At the same time, Brazil has been provided with the impetus to convert its substantial reserves of ore to value added products.

Jan 1, 1988

The capacity of chlorine based solutions to rapidly and effectively dissolve coarse gold in oxide ores is well established. The inherent advantages of chlorine are high dissolution rates (10 - 100 times those of cyanide), and low cost. The high dissolution rates mean that coarse or poorly liberated gold may be dissolved over relatively short periods and hence ore particle size may cease to be such a critical factor. The cost of size reduction to allow adequate gold liberation in order to achieve an adequate gold recovery is less of a consideration when using chlorine than in traditional plant or heap leaching cyanide-based treatment systems.Because chlorine based solutions capable of dissolving gold evolve an unpleasant vapour phase with the potential for significant chlorine losses into the atmosphere, traditional heap leaching with active solutions being sprayed onto prepared heaps is not possible. The ore must be covered and the solution may be introduced beneath that cover through prepared injection `wells' and recovered through production 'wells'. The pit is flooded with active solution beneath an overburden or cover with the solution migrating from the injection 'wells' to the production 'wells' over a period of around five - ten days.

Jan 1, 1992

By Kuganathan V

The processing of black coal in Australia segregates waste in the form of coarse reject and fine tailings. The coarse reject is relatively easy to handle, while the tailings can be problematic. Conventionally, the two waste materials are disposed of separately, the coarse reject in dumps, and the tailings in man-made containments. Aqueous tailings slurry is pumped to a 'wet' tailings storage, where the fine particle size of the tailings limits dewatering. Their low bearing capacity and high compressibility result in tailings deposits being difficult to rehabilitate. Disposing of the waste streams separately moves away from the heterogeneous mixture in the undisturbed ground, and concentrates potential problems with each waste stream. The feasibility and desirability of the co-disposal of tailings and coarse reject by combined pumping is demonstrated. This technique is in operation at Jeebropilly Mine and is proposed for a number of other coal mines.

Jan 1, 1992

By Tagawa H

In Japan, geological condition do not only vary in a wide range of strata but are also extremely complex with the existence of faults and aquifers. With respect to rocks, in particular, it is very rare that homogeneous rocks are distributed uniformly. In general, geological conditions are distributed in a wide variety, ranging from earth, sand, soft and medium rocks to hard rocks. Under these geological conditions, when planning of the tunnel construction is to be made out, either blasting method or tunnel boring machines must be selected taking into consideration the geological structures along with the designed tunnel route,' possibility of encountering aquifers, hardness of rocks anticipated and also, the adjacent environ- mental conditions. In the process of select- ing an excavation method,, it is important to make a comparative investigation between the above two methods considering the advantages and disadvantages with regard to the respective operating efficiency, economical efficiency and the conditions and scope of application as well. Furthermore, in addition to these considerations, the recent environmental restriction, which does not allow the blasting in the surroundings of residential areas, must also be taken into account. Because of this, in some cases there is no alternative but to use a static excavation method or a tunneling machine even when these are less efficient than blasting.

Jan 1, 1987

By Gostylla W

The economic feasibility of controlled district cross-cut recirculation is examined in this paper with particular reference to the most important mine ventilation network parameters. An algorithm is developed to express the annual cost of recirculation which is then compared to the annual cost of conventional ventilation using the University of Queensland Experimental Mine as a case study. The concepts of resistance ratio and volumetric efficiency ratio are introduced and used to analyse the economic feasibility of controlled recirculation within a mine ventilation network.

Jan 1, 1988

The granulites and related "dry" igneous rocks tend to be passed over during exploration for metals. Preliminary data show that high trace concentrations of Cu, Ni and other metals of economic interest are common in orthopyroxene and some of the other granulite minerals. During retrograde metamorphism of granulites, pyroxenes are converted to amphiboles or phyllosilicates, and significant quantities of metals are released and become available for incorporat- ion into new mineral phases, or may be transported elsewhere. S--rich scapolite is the normal scapolite of granulites. Its retrogression to secondary plagioclase provides much S which scavenges Cu, Ni, etc., from pyroxenes undergoing retrogression, thus producing ore-fluids. A full analysis of a scapolite with 5.10 per cent S03 is given. Beryl is unstable in granulites but the rare Be mineral taaffeite (Al4Pf (Be,Fe)O3) with 5,50 per cent BeO occurs in central Australia as a pale green Tabular mineral easily confused for chloritoid in hand-specimen. Metamorphic differentiation and mobilization of primary ore concentrations are major factors controlling their post-granulite attitude and grade.

Jan 1, 1969

By D T. Feinstein, M B. Gotkowitz

In Wisconsin, state laws and regulations governing metallic mine permitting stipulate that protection of groundwater quality be assured indefinitely through all phases of the mining project, including development, active mining, reclamation, and long-term closure. By rule, the Wisconsin Department of Natural Resources (WDNR) requires that permit applicants use a numerical model to assist in the assessment of compliance with this requirement for all proposed mine-waste facilities. As a part of the compliance assessment, model calculations are used to predict groundwater solute concentrations through time at designated boundaries for comparison to current groundwater quality standards. In practice, this modelling requirement has involved the application of numerical solute-transport models. Our review of a solute-transport model submitted by the developers of a proposed mine near Crandon, Wisconsin, provides us with an opportunity to assess the usefulness of transport modelling as a permitting requirement. Recent evaluations of solute-transport models by other workers suggest limitations in predictive accuracy. Our review of the model submitted for this project also identified important limitations due primarily to uncertainty in calibration of model parameters at the undeveloped site. The utility of any model to predict project compliance or non-compliance with numerical standards is limited by the range of uncertainty of key model parameters, such as dispersivity and porosity. Uncertainty in the future behaviour of the solute source(s) also reduces the predictive power. Moreover, the site characterisation provided by the model may have limited power to describe the site condition post-development. Although these inherent shortcomings accompany the use of solute transport models at undeveloped sites, the requirement for model development and the ensuing technical review has substantially assisted in our evaluation of site conditions and project design. Through this process we have identified elements of the waste facility design that are crucial to the environmental viability of the project, resulting in modifications to original project proposals. While results from this model review will be used to evaluate compliance, additional benefits come from the identification of critical design features that enhance groundwater protection.

Jan 1, 2003

By N McIntyre, R Trancoso, N Bulovic

Mining is essential for facilitating human development particularly as demand for critical minerals grows. However, over the mine life cycle, the environment is permanently changed. Once mining ceases, mine-affected land can leave significant legacy issues on the surrounding environment if not managed. Therefore, mine closure planning is critical. Mine closure occurs over large scales often with the aim of recreating resilient ecosystems over mined landscapes with mitigated negative impacts. The natural state of the landscape and the environmental risks over planning time-scales are largely driven by climate. Climate change is expected to impact different parts of the post-mining landscape, from stable landform design (soil erosion mitigation) to revegetation efforts and pit lake management. Consequently, mine closure plans may need to account for a non-stationary and uncertain future climate, that may be both different to the current climate and evolve during the mine life and post-closure. Here a new data-based approach is presented for incorporating climate change projections in mine closure planning, based on the recently released Coupled Model Intercomparison Project phase 6 (CMIP6) climate data used in the latest Intergovernmental Panel on Climate Change (IPCC) assessment report. The approach: (i) characterises closure-related attributes of the future climate, and (ii) identifies the amount (and direction) of change expected to occur, and its uncertainty, focusing on five metrics for demonstrative purposes and initially describing changes in erosive potential below. This provides information on the type of future environment (ie the changing baseline) that mine closure should plan towards, and identifies rehabilitation options that may be susceptible to increased risks from climate change.

Aug 2, 2023

By Mitchell G. W, Purvis A. H

The Lady Loretta silver-lead-zinc deposit lies north of Mount Isa in folded and faulted Proterozoic carbonate sediments. The deposit was discovered in the late 1960's as a result of a soil geochemical survey. Subsequent surface drilling outlined mineralisation folded into a synclinal structure extending to a depth of 460 m and containing exceptionally high grades within the keel of the syncline. Pancontinental Mining Limited and Outokumpu Oy of Finland acquired the property in 1985.

Jan 1, 1988

There is no other effective way for study ing firedamp and coaldust explosions than to produce controlled explosions in a pre-monitor- ed environment - either mine openings kept for the purpose, or special surface galleries. Such explosion testing facilities have been employed historically at Buxton in U.K., with lesser known installations at Bruceton, U.S.A., Tremonia, West Germany, Katowice-Mikolow, Poland and elsewhere. Both firedamp and coal dust explosions are studied. Normally coal dust explosions are initiated by somewhat standardised methane air mixtures, by explosives, or purely by coal dust. Various structures and suppression installations are installed in roadways and galleries prior to explosion to simulate destruction and suppression, and the results of such tests form the basis of suppression installations, especially stone dust barriers and water barriers. Other data collected from these experiments include rev- ersals of explosion waves, pressures and temperatures and duration of explosion waves, analyses of aftergases etc. Other uses of explosion testing galleries include testing of explosives, electrical equipment and frictional . sparking.

Jan 1, 1981

By Yigit E, Royston D, Winborne DA

Semi-bulk concentrates of 45% zinc at 80% recovery have been produced from the McArthur River mineral deposit. Selective leaching of these concentrates to recover lead and a commercial grade zinc concentrate has the potential to increase significantly the recovery of zinc (as zinc concentrate) and lead (as lead metal) over conventional flotation methods producing lead and zinc concentrates.

Jan 1, 1986

By Tien J. C

Many factors (type of coal mined, water pump pressure, wetting agent concentration, etc) will affect the performance of a dust suppression system using a water spray in an underground coal mine. While a two-level factorial method is useful in

Jan 1, 1994

By Bogie I, White P. J

Active geothermal systems occur widely in Sumatra and in the Taupo Volcanic Zone (TVZ) of New Zealand. There are also many occurrences of epithermal gold mineralisation in Sumatra, some of which are economic. Minor sub-economic occurrences of gold have been reported in the TVZ but none have yet been mined. There are both similarities and differences in the nature of the active geothermal systems and mineral deposits in Sumatra and New Zealand, which can be systematically related to the tectonic setting. The thicker crust and consequent predominance of silicic volcanism in New Zealand leads to hydrothermal. systems which are little eroded and with limited lateral outflows. The systems in Sumatra are of mixed character, with some of the characteristics of those in andesitic island arcs such as Java or the Philippines, eg a higher proportion of systems with identifiable acid magmatic volatiles, a greater potential for deep erosion and lateral outflows than in New Zealand; but modified by the more oblique component of subduction and thickened crust so that some are localised in volcano-tectonic depressions and consequently have high piezometric levels of primary hydrothermal fluid. The unusual occurrence of calcic zeolites in veins associated with gold mineralisation in Sumatra is thought to be indicative of "satellite" boiling zones along de-gassed hydrothermal outflows.

Jan 1, 1995

It is very apparent that the hydrogeotogicat characteristics of mineral deposits in China be dominated by meteoric factors, terrain factors and the kind of karstic aquifers as a main source threatening the mining.The hydrogeotogicat characteristics of mineral deposits in dry areas are very different from that in non-dry areas.The rote of precipitation is very important to mine dewatering.The difference of water recharge condition of a mineral deposit located upper (or under) Local erosion basis is existing. There are more than two million square kilometers of carbonate in China.Many water-bearing deposits are distributed in it.According to the karst shapes the surrounding karstic aquifers of mines can be divided into three kinds including solution fissure aquifer,karstic cave aquifer and underground stream (karst stream) aquifer. Underlier invasion is a main feature of karst water-bearing coal mine and upper tier incoming is a main feature of skarn copper and ferro mine.Swatlor pillar and collapse is a special feature of karstic water-impregnated mine.

Jan 1, 1988

Evolutionary changes to the original sizer concept are mild when compared to those which have taken place in the engineering standards embodied in today's commercially available machines. This paper examines the principles of sizer operation and reviews the development trends in new applications for this unique screen type.

Jan 1, 1978

Conveyor belt haulage offers the advan tages of continuity of operation, minimum labour requirements, and the ability to handle large volumes of material over extended periods. However, breakdown of critical con- veyors in the system can cause undue and substantial losses in production output at the working faces, unless adequate surge bin capacity is incorporated in the haulage system. A conveyor belt simulation programme, code name 'Beltsim' was developed by Bucklen et al (1968) at the Virginia Polytechnic Institute in the U.S.A. and provides a quantitative measure of the performance of a conveyor belt network design. A limitation still exists with the computer programme and involves the inability of the programme to predict the necessary surge bin capacity to overcome conveyor belt downtime. The computer programme was modified to overcome this limitation, to simulate a con- veyor belt breakdown, and to provide a quantitative prediction of the surge bin capacity necessary to permit a modern mining system to operate effectively and continuously.

Jan 1, 1977

Trial ore production began at the Hilton Mine in 1987 with ore being trucked into Mount Isa for treatment at the Lead/zinc Concentrator. The expansion of output from the Hilton mine required additional concentrator capacity which led to the design and construction of the Hilton Concentrator. Systematic laboratory and Pilot Plant testwork dating back to 1968 to develop a flowsheet and reagent regime suited to the varied and generally complex mineralogy of the Hilton ore was successfully concluded with a Pilot Plant trial using a sulphoxy based sphalerite depression system in early 1988.In May 1988, a decision was made to build a 750 000 t/y concentrator with some novel technological and capital-efficient features. The Hilton Concentrator commenced operations in December 1989 reaching target grinding rates and metallurgical performance by mid-1990. Current ore treatment rate is 800 000 t/y.Lead concentrates assaying 43 - 48 per cent Pb are combined with the Lead/Zinc Concentrator lead concentrates and smelted at Mount Isa. Zinc and Low Grade Middlings (LGM) concentrates are filtered in the zinc filter plant at Isa with those from the Lead/Zinc Concentrator and then railed to Townsville for export or treatment in Australia.

Jan 1, 1993

By Badal R

Rock Discontinuities ("joints") affect blasting results. An investigation was carried out to understand if blast parameter such as spacing needs to be altered with the change in joint direction. Small scale laboratory studies in jointed limestone blocks have been carried out. It is shown that optimum spacing is variable with the "joint" orientations. Evidence is presented from field studies in four limestone quarries supporting laboratory studies. Reasons for success and failure of widespacing technique is also provided. Only with suitable orientations of "joints: widespacing is successful.

Jan 1, 1990

Blasting, particularly bench blasting, uses finite length cylinders of explosive close to two free faces. The rock to be blasted is usually intersected by a complex 3-D system of joints. To fully simulate a blast, a 3-D dynamic model is required. It is shown that the static stress distribution around a long cylinder can be reproduced by superposing the static stress distribution of a suitable chain of spheres. Thus, the dynamic results for individual spheres given by Favreau (1969) can now be substituted for the static results to give a dynamic model of the stress distribution around a long cylinder. Comparison of measured and computed waveforms show that the measured waveforms are much more attenuated and dispersed than expected. The consequences for explosive evaluation and design are Discussed.

Jan 1, 1990

By Savory P. J

Uranium mining operations commenced at Ranger mine site, Jabiru NT Australia in May 1980. The Ranger orebodies, totalling approximately 110 000 tonnes contained U305 had been indicated by airborne radiometric survey in 1969 and confirmed by drilling the following year. Both diamond and percussion drilling methods were used to define the mineralisation and samples were analysed using a combination of radiometric and neutron activation techniques. Ore reserve estimates were calculated from conventional and geostatistical methods, and following the mining of 15 million tonnes of ore, reconciliations with before mining estimates are well within acceptable industry standards. In-pit grade control employs radiometric techniques including a radiometric truck discriminator built in Australia to mine specification to meet production requirements and improve productivity. Environmental requirements associated with uranium mining are a daily consideration.

Jan 1, 1993