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By E M. Rykaart

The design of soil covers as part of the remediation initiatives for mine waste facilities is common practice and more and more engineers are faced with designing these facilities. The design issues associated with these soil covers are complex and requires a good understanding of unsaturated flow. More engineers are making use of numerical models to predict how cover designs would perform, and this has been necessitated by the high non-linearity associated with solving unsaturated flow problems. There are numerous numerical models available to the prospective users and they are all simplifications of reality using different assumptions. The users of these models often do not understand the limitations of the models but rather select a model based on ease of use, and that lends to increasingly erroneous designs being proposed for construction. This paper describes a comparative evaluation of a cover design using four different codes available today; SoilCover, SWIM, HYDRUS-2D and HELP. The paper does not propose to measure these codes up against each other and make statements about which is better than the other but rather illustrates how the assumptions in each code affect the outcome. The data set used for the comparative study is a well calibrated data set that that has been collected over a long period in time and that has been collected according to strict controls. The authors present the pitfalls of numerical modelling of the surface flux boundary conditions, as well as present guidelines towards appropriate use of these modelling tools.

Jan 1, 2003

By Smith E. L

The Ore Reserve/Exploration System implemented at Mount Isa for M.I.M. Holdings Limited is a comprehensive computer system designed to process assay, geological, structural and survey data input via special purpose logging sheets from daily activities at Isa Mine, Hilton Mine and various Carpentaria Exploration Company prospects. The system performs two basic functions; (1) data acquisition, validation and file maintenance to prepare the data for retrieval, and (2) generation of routine and optional reports. The types of reports available range from masterfile detail printouts and retrieval of data by key items to survey computations, structural analyses, cutoff calculations, statistical analyses and ore reserve calculations by the polygonal, inverse square or moving average techniques. The use of various optional reports available through the system is illustrated by several examples, and planned future development is discussed.

Jan 1, 1973

By Waijun Cheng, Guilin Xie

A microcomputer control system prototype of a Switched Reluctance drive for storage battery electric vehicle in coal mines is developed. The paper introduces the hardware components, the control strategy and the software unit. It is shown that

Jan 1, 1998

By Zhang P, Wang T, Duan X, Sheng T, Kong L, Wang Y

This paper puts forward an artificial neural network (ANN) for the forecast of deformation of the surrounding rock deformation. On the basis of this, this paper gives some examples of its application. The results show that the ANN model has a high forecast accuracy.

Jan 1, 1995

By G W. Wilson, C Panidis

Potentially acid forming (PAF) waste rock contained in dumps formed as a result of open cut mining of metalliferous orebodies are conventionally sealed or covered using a near-saturated, low permeability compacted clay layer, protected with a mulch layer and/or vegetated growth medium. The purpose of the compacted clay layer is to limit oxygen diffusion and the infiltration of rainfall into the dump. Where the aerial extent of the PAF waste rock dump is large, or where suitable clayey material is in short supply, it may be difficult to source sufficient suitable clayey material to form the cover. The paper describes a laboratory-based investigation of combining inert waste rock and tailings to form an alternative seal or cover material. The inert waste rock was sourced from the trafficked surface of a non-acid forming (NAF) waste rock dump, with a maximum particle size of about 100 mm. This was combined with NAF thickener underflow tailings slurry in various mass ratios, and the resulting mixtures tested for their particle size distribution, compaction characteristics, soil water characteristics (relationship between suction and volumetric moisture content), and saturated hydraulic conductivity. The mixtures tested ranged in consistency from those dry enough to be compactable, to those with the consistency of wet concrete that lend themselves to placement without the need for compaction. The laboratory test results showed that the suitability of the mixtures as seal or cover materials is very dependent on the particle size distribution of the mixture, with well-graded mixtures having substantial fines performing best.

Jan 1, 2003

During Gepp's lifetime, Australia was in the forefront of science and art in metallurgical practice. This did not come easily for although blessed with a unique mineral deposit at Broken Hill large in size and rich in values much courage and daring was needed in the development of processes whereby they could yield the best results.The resultant development of the flotation processes at Broken Hill is one of the most important inventions of the 20th century.

Jan 1, 1993

By Chugh Y. P

A simplified, three-dimensional, time-dependent, mechanistic model of the overburden-coal seam-floor interaction has been developed and validated at two Illinois coal mines. The model based on the thin plate theory can involve any complex layout of mine workings, time-dependent sequence of extraction and, rheological properties of immediate floor strata. The model output data consist of spatially distributed surface subsidence and its slope and curvature, as well as load acting on pillars in one or more panels. A comparison of calculated and monitored surface subsidence or in- mine convergence measurements has proven the model's effectiveness for surface subsidence and load transfer Prediction.

Jan 1, 1992

By Johnson M, Wooltorton B

A programme of hydraulic fracture stress measurements conducted in surface drill holes along the alignment of the King River Power Tunnel has provided information of importance to the assessment of the extent of steel lining requirements for the tunnel. A significant horizontal stress field has been detected at a location remote from the power station site, with a corresponding absolute minimum stress magnitude approximating the overburden pressure based on depth of cover. Measurements made closer to the power station site (located toward the bottom of a valley) have revealed an apparently relatively destressed region with minimum stress magnitude less than overburden pressure. The implications of these results are discussed.

Jan 1, 1987

Samples weighing 0·5 g are fused with sodium hydrogen sulphate, leached with 5 ml. of 4 M nitric acid and diluted to 10 ml. with water. An aliquot of the clear solution is boiled with concentrated nitric acid and then 2 ml. of a phosphotungstate solution are added. After dilution to 10 ml. with water, the solution is heated in a boiling water-bath for not less than 10 min. When cold, the solution is extracted with 2 ml. of iso-amyl alcohol and the yellow phosphotungstovanadate complex is compared with a standard series. Concentrations down to 4 p.p.m. may be analysed at a rate of 100 samples per man-day of 8 hr.

Jan 1, 1971

Three methods of gold analysis are briefly described highlighting some of the problems and advantages of each. The variation of results between samples and splits and due to method preparation are illustrated. The mean percent difference of the fire assay values from the means of sample split values for three cases is 15%. Finally, a comparison of the aqua regia atomic absorption spectroscopy and fire assay fusion AAS techniques is made. This shows that the mean precision, the ability to obtain the same value, of the methods at 98% confidence are +30% and +15% respectively. The fire assay fusion atomic absorption spectroscopy method is relatively more accurate than the aqua regia method.

Jan 1, 1982

By Smith KS

Mineral-deposit geology, geochemical processes, and biogeochemical processes are fundamental controls on the environmental conditions that exist naturally in mineralized areas prior to mining, and that result from mining and mineral processing. Input from economic geologists and geochemists is therefore crucial to effectively predict, assess, mitigate, and remediate the environmental effects of mineral-resource development. Recent open pit gold mining at Summitville, Colorado, has received intense public scrutiny for a variety of environmental problems, most important of which has been extreme acid drainage. Now a Superfund environmental cleanup site, Summitville exemplifies how economic geology and geochemistry principles (1) could have been better utilized to first predict and minimize the environmental problems, and (2) can now be used to optimize the environmental cleanup.

Jan 1, 1995

The authors are looking at the behaviour of the mineral processing circuits by means of the simulators operating under random disturbance. The present paper deals with the fuzzy control systems in comparison with PID controllers. A series of tests are conducted on simplified prototype processes with (1) dead time plus first-order lag model and (2) diffusive model. In the next series of tests the self-sustained process model was introduced to improve control against dead time. In both cases fuzzy and PID controllers are optimised by EVOP method. Particular attention is paid to the effect of observation noise to analyse for the problems which can be fatal to practical applications in mineral processing. Finally the methods developed are applied to a closed-circuit wet grinding system simulator operating under random disturbance.

Jan 1, 1993

The Yilgarn Block of Western Australia presents (figure 1) a number of problems for conventional diamond exploration based on heavy indicator mineral sampling. These problems are due to the geology and unique geomorphological development of the Yilgarn Block.Essentially the Yilgarn Block is a pene- plain developed on a craton composed of Archaean intrusive granitoid rocks with meta- morphosed greenstone; which, apart from regional uplift, has not been tectonically disturbed since planation by glaciation in the Permian. Therefore since the early Plesozoic the Yilgarn Block has been subjected to terres- trial weathering conditions. Bettany et al., (1984) identify two phases of particular importance in the development of the present landforms: 1. Periods of lateritization during the Tertiary which result in the ~lassi~al laterite profile (figure 2). Duricrust indurated : Fe and Al oxides Mottled zone : Clay and Fe oxides Saprolite or pallid zone : leached clay grading into fresh rock. 2. Subsequent periods of aridity and semi- aridity during which laterite development was truncated and reworking of laterite Occurred.

Jan 1, 1988

By B Ekberg, R Salmimies, T Kinnarinen, A HSkkinen

The regeneration of the ceramic filter medium used in iron ore dewatering is often done by combining backwashing, ultrasonic cleaning and chemical regeneration. Of these three, the first two are applied more frequently, whereas chemical regeneration is done only when needed, eg once a day. Chemical regeneration of the ceramic filter medium in iron ore processing can involve the use of oxalic acid to dissolve the iron oxide particles. Even while performing simple chemical regeneration, meaning no ultrasound to assist the cleaning, the changes in the performance and in the structure of the filter medium could not be explained solely based on the dissolution or the removal of particles from the surface. Good regeneration results were obtained at 35 and 50¦C, meaning that the final permeability of the filter medium corresponded to that of unused filter medium. Permeability of the medium after regeneration at 15¦C was also good after 12 h, but did fall short of those regenerated at higher temperatures. Changing the acid concentration did not seem to have a significant effect on the regeneration.CITATION:Salmimies, R, Kinnarinen, T, Ekberg, B and HSkkinen, A, 2013. Particle dissolution in the chemical regeneration of the ceramic filter medium used for magnetite dewatering, in Proceedings Iron Ore 2013 , pp 473-478 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

By Coppock BW, Scott TC, Firkin GR

The pollution control measures taken on the Imperial Smelting Process (ISP) operated at Cockle Creek are described together with environmental monitoring strategy and the statutory restraints applied in New South Wales. An outline of developments in the gaseous, liquid and noise control areas is given.

Jan 1, 1975

Misima Mines Pty Ltd (MMPL) operates a large open cut gold mine on Misima Island in the Louisiade Archipelago in Papua New Guinea. Misima Island lies approximately 600 km east-south-east of Port Moresby. The island is 40 km long by 10 km

Jan 1, 1994

By K McNabb, M H. Turner, P A. Jenkin

Mining of the Agnew nickel deposit commenced in 1970 using a variety of underground mining methods, though with mixed success due to the difficult ground conditions. WMC Resources Ltd acquired the operation in 1989, and commenced nickel production with an open pit. In 1995 all production reverted to the rejuvenated underground mine, using exclusively SLC (sublevel caving) methods. Currently the mine produces 1.4 Mt per annum, at an average grade of 1.74 per cent Ni. Underground mining of the Perseverance orebody has always presented significant challenges due to the difficult ground conditions in the weak and altered ultramafic rocks. The range of problems include areas of swelling minerals, intense and extremely weak shear zones, relatively high in situ stress, and in other areas very brittle rocks. Under these conditions rock mechanics input has been and remains a critical element of the mining strategy. Severe ground behaviour difficulties down to a depth of 500 m below surface prompted a review of the mining strategy for the large disseminated nickel orebody, including evaluation of alternative mining methods. However, sublevel caving was ultimately selected as the preferred method, and a re-design of the SLC cross-cut layout followed. A selection of rock mechanics investigations of interest are described, including complex virgin stress measurements, detailed ground behaviour monitoring, and the use of non-linear stress analyses to re-design the mine layout. Subsequent ground behaviour, support design and production scheduling are also described.

Jan 1, 2000

By P Waters, S Miller

BHPBilliton operates the Mt Whaleback Mine located in the semi-arid Pilbara Region of Western Australia. Approximately 200 Mt of net acid generating (NAG) material still remains to be mined. Acid Rock Drainage (ARD) was first identified at the site in 1995 following cyclonic storms. This resulted in the development of strategies that have allowed the mine to successfully manage ARD whilst continuing to operate. BHPBilliton Iron Ore is working toward prevention of ARD in its operations, however, historical practices have left residual areas that must be considered. Three significant sources of ARD have been identified that must be managed: stormwater run-off from exposed pyritic shales in pit surfaces; basal flows beneath overburden storage areas following rainfall events; and contaminated water from pit dewatering. The mine contains all ARD water onsite. This is achieved by: storage of all affected water in the ARD dam; evaporation of affected water from the ARD dam and the adjacent evaporation ponds; pumping from upstream dams to prevent stormwater from being affected; and emergency storage and treatment in-pit as a contingency. The site ARD management strategy is approved by senior management and endorsed by State Government regulatory authorities and relevant external stakeholders. Additional strategies are also under evaluation to effect long-term closure of the operation. Record rainfalls from 1998 - 2001 have tested the capabilities of the ARD strategy and management plan. Learnings from these events, coupled with recommendations from an extensive technical audit in 2000, have been incorporated into the strategy for ARD management. This paper presents the strategy and an overview of the ARD management plan that can be considered and applied by other affected sites in the management of ARD.

Jan 1, 2003

A Master of Applied Science degree course in Mining Geomechanics commenced in 1983 at The University of New South Wales, taught by extern- al (correspondence) studies. The course is aimed at graduates employed in the mining indust- ry, and especially people involved in geomechan- ics projects on a routine basis in remote locations. This kind of course is unique in Australia and is one of only two correspondence programmes available at this University. The author designed the course and nursed it through the early years, and was Director until 1986. The paper describes the teaching and assess- ment methods and also discusses aspects of admin- istration and coordination of such a course. It is concluded that an important need of the mining industry is being catered for and it appears that similar correspondence course for- mats would also be useful in other areas of the minerals industry.

Jan 1, 1986

By Terrill JE, Fergusson LJ

In the last decade of precious metal exploration, several important gold discoveries have conclusively demonstrated that epithermal gold deposits formed in what were once active geothermal areas. A significant deposit in this category is the Lihir Island discovery in the Tabar-Ferri volcanic island arc off the coast of New Ireland, Papua New Guinea. Within that arc are the Feni Islands where exploration by Esso PNG Inc. and City Resources Ltd. has been carried out since early 1984. On Ambitle Island in the Feni Group, an epithermal gold prospect located within a young caldera has been tested by diamond drilling. The drillholes intersected a boiling zone at depth beneath acid altered 'cap' rocks. The zone is 30-60 metres thick and comprises hydraulically fractured and mineralised lavas with gold grades of 1-7 g/t. The prospect is still an active geothermal area with current boiling in the zone tested. As on Lihir, the recent epithermal alteration and mineralisation overprints a relict prophyry system. On Ambitle and the adjacent Babase Island several other, cooler exciting gold prospects are currently being tested.

Jan 1, 1987