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The paper describes the design of the dilute medium and medium recovery circuits installed at the coal preparation plants at the Cornwall Coal Company's Fingal Mine, and the BP Coal Australia's Howick Mine. These circuits maximize the use of clarified water for rinsing to improve the mass transfer of adhering medium from the coal surface into the carrying liquid, and have been combined with the use of a two stage magnetic separator. The separator utilizes a conventional concurrent first stage and a counter-rotation second stage. This combination results in high medium recoveries during both normal operation, and start up and shut down phases when large quantities of medium can be lost from a conventional circuit. Overall losses using this circuit have been estimated to be, 200g/t, over a twelve month period. Further advantages in plant operation are also obtained, especially steady operating conditions in the centre-tube pump tank, lower slimes contamination of the product, and lower quantities of non magnetics trapped in the separator concentrates. The techniques are particularly suited to incorporation in circuits treating coals containing high percentages of sticky and difficult clays, as are found in the Walloon coal measures.

Jan 1, 1987

By Perring CS, Hill RE, Barnes SJ, Vallance SA

The Maggie Hays nickel sulphide deposit is located at latitude 32¦ 15 'S, longitude 120¦ 30' E on the Lake Johnston (SI 51-1) 1:250 000 map sheet. The deposit occurs in the Lake Johnston greenstone belt, in the Southern Cross Province of the Archaean Yilgarn Block, 500 kilometres east of Perth, Western Australia (Figure 1). The remoteness of the Lake Johnston greenstone belt and its poor access, restricted previous exploration activities and the full appreciation of the geology and its Ni-sulphide potential. It was not until 1991, when Forrestania Gold NL commenced exploration activities, that the geology of the ultramafic units and their potential to host significant concentrations of Ni sulphides were clearly established. This paper, which describes the geology and the characteristics of the Maggie Hays deposit, is based on the results of exploration by Forrestania Gold NL and a collaborative research agreement between CSIRO Division of Exploration and Mining and Forrestania Gold as reported by Perring, Barnes and Hill (1994), Perring and Hill (1995), Perring (1995 a and b) and Barnes, Perring and Reilly (1995). A comprehensive description of the geology, petrology and geochemistry of the deposit is being prepared for publication by CSIRO (Pemng, Hill and Barnes, in press).

Jan 1, 1996

By Fuller P. G, Dugan K. J

Artificial support can be used to improve wall stability in open pit mines. This is examined for a particular case where the factor of safety for a slope is kept constant by using artificial support as the slope angle is increased. It is demonstrated that the savings in excavation generally exceed the cost of support. However, in order to correctly judge the eco- nomic impact of artificial support on the project, all the elements relat- ing to the use of artificial support must be taken in account.

Jan 1, 1989

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

By K Muller, T Oosthuizen

Blast exclusion zones are instrumental in protecting equipment and personnel. When there is no constraint in footprint, the exclusion zone can be enormous, practically eliminating the hazard of flyrock. Unfortunately, this may not always be the case and in many circumstances the blast design needs to be altered to suite such scenarios. When a conservative design approach is taken, it could completely eliminate any form of ejection, whether it is from the free face or the bench itself. The degree to which typical flyrock models describe fragment motion through air with ballistic flight equations are not justified when such a high level of control is applied. This paper examines various methods of risk analysis and suggests an approach to be used for controlled blasting.The outcome of principles discussed in this paper can be seen in video form (Mavmedia, 2014).CITATION:Muller, K and Oosthuizen, T, 2015. Should the blast exclusion zone be based on a qualitative or quantitative analysis? A practical implementation conundrum, in Proceedings 11th International Symposium on Rock Fragmentation by Blasting, pp 425–428 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 24, 2015

By Sehic O. A

Geology can be the root of evil or a source of bliss; there is a choice; to ignore geology is at a mine's peril.Risk can be minimised and profitability maximised by the application of a detailed understanding of geology, alteration, structure, mineralogy, chemistry, fabric and texture.Geology is dynamic, not static.The impact of geology is pervasive.The integration of ore quality control with grade control is one strategy for improving the utilisation of both the mineable reserves and existing plant and equipment. Grade maintenance is but one constraint on the problem of how best to blend the ore. Other ore characteristics such as mineralogy, hardness for grinding, and pulp fluidity or density for slurry size classification can be included to explore alternative blending Strategies.

Jan 1, 1993

By Falconer A. J

Two magnetic parameters are proposed as a basis for the assessment of ironsands beneficiation. The parameters are deter- mined for raw sand prior to dredging and for magnetic separator head feed over a production period of five months. The relationships between these parameters and the performance of the magnetic separators are examined to establish the value of magnetic assessment compared with the traditional soluble iron assay method. The results illustrate that the first parameter, true magnetic fraction (TMF), has a value superior to that of soluble iron when relating raw sand grade calculated by tri- angulation to magnet performance. In terms of the relationship between magnet head feed grade and magnet performance, TMF and soluble iron perform equally as assessment parameters. For the ironsands mined during the five month period, the second magnetic assessment parameter, composite fraction (CR), is shown to merely reflect TMF and offers no additional information for assess- Ment. Conclusions are that true magnetic fraction has many advantages over soluble iron in terms of time and cost of determination and that it is a meaningful and reliable parameter upon which to base all calculations relating to the mining and beneficiation of ironsands.

Jan 1, 1980

This paper introduces a new, safer bulk emulsion loading system for underground mining operations. The features and benefits of the equipment, along with the use of Dyno Nobel Inc patented gassed emulsion technology, is summarised in the application of a stope blast with very difficult and complex ground conditions. The paper describes methods used to optimise the amount of energy required to break the ore while protecting the integrity of the surrounding backfilled pillar.

Jan 1, 2004

A novel fracture-plane control blasting technique with particular application in wall-control blasts in mines employing medium to large diameter boreholes is described. It consists of a string of nested holes, each nest consisting of a large diameter charge-hole flanked on either side by a small diameter satellite hole. Each nest is shown to be an analog of a pressurized hole with diametral notches along its length. This 'equivalent-notched' hole concept for generating controlled fractures along preferred directions has been successfully investigated in the laboratory and in the field. The technique has been used to generate controlled fractures on a quarry bench in highly jointed limestone. The resulting blasts with a 250 mm diameter central charge-hole and 50-75 mm satellite holes show that two nests of such holes almost 5 m apart could be joined by a single co-linear fracture. The design range of diameter ratio between charge-hole and satellite hole is 3 to 6 and spacing is 3 to 5 charge-hole radii. With careful matching of explosives and decoupling, and combination of diameter ratio and spacing, it would be possible to connect two nests of such holes more than 20 charge diameters apart by a single controlled fracture plane. The relative merits of the technique against existing wall-control blasts are discussed, and guidelines for practical fracture-plane control blast designs are discussed.

Jan 1, 1990

By J Harris, J Turner, P Kirsch

Coal mining is recognised globally as a hazardous activity, and as a result operates under high levels of regulatory and public scrutiny while managing a workforce operating in a high-risk environment. Mining companies have developed sophisticated risk assessment procedures, management systems and personnel competency requirements that facilitate the safety and health of employees, and Australia is a world leader in coal mining safety and health.RISKGATE is an Australian Coal Association Research Program funded online platform that delivers broad cross-industry knowledge about current practice in the identification, assessment and management of coal mining risk. Centennial Coal has engaged with the RISKGATE program, managed by the University of Queensland’s Minerals Industry Safety and Health Centre, since its inception in 2010, and contributed topic experts to many modules, including underground topics within the geological and geotechnical domain (strata underground, outburst, coal bumps and bursts, and inrush).In 2013, Centennial Coal experienced significant unexpected strata failure at the Mandalong mine without any personal injury or fatality. This paper presents a case study in the application of RISKGATE to management of this unwanted event, the steps that were implemented, the information that was sourced and the contribution that RISKGATE made to the final outcomes. The Australian coal industry is encouraged to embrace our knowledge platform, and to also openly share processes and practical outcomes that result from integration of RISKGATE in mining operations.CITATION:Harris, J, Turner, J and Kirsch, P, 2014. Case study – application of RISKGATE to managing strata failure in an Australian coalmine, in Proceedings AusRock 2014: Third Australasian Ground Control in Mining Conference , pp 55–60 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 5, 2014

By Sarracino R. S

A number of ideal detonation codes are used internationally for estimating the strength of explosives compositions. Important and far reaching decisions by explosives users are ofen based on the predictions of these codes, but since different codes can deliver very different answers for the same composition, there is a strong possibility of decision makers being misled. In order to both provide a sensible basis for comparing the theoretical energy from explosives from different manufacturers and to prevent the entire rating system from slipping into disrepute, it is in the interests of all to reach agreement on fundamental criteria used by detonation codes for detemtining strength. The problem is illustrated by a case history and basic conventions are proposed, specifically the adoption of energy of reaction as a fundamental and code independent indicator of explosive energy, and agreement on disclosure by suppliers of key non-proprietary information. These measures would assist explosives customers in assessing the true strengths of explosives from the strengths calculated by the different ideal Codes.

Jan 1, 1990

By Amanatidis A

In this paper, the kinetics of iron precipitation as sodium jarosite from aqueous solution is investigated. The determination of the reaction mechanism is attempted based on the experimental data of iron removal as a function of time, without using the characteristics of the precipitate.Experiments at the temperature range from 50° to 95°C were carried out with initial conditions of iron concentration IQ g/L, sodium sulphate concentration 25.44 g/L, sulphuric acid concentration 3.68 g/L, pH = 1.5 and agitation rate 600 rpm. Temperature greatly and positively influences iron precipitation from the solution and this is accompanied by pH decrease. The activation energy was determined using the maximum values of the precipitation rate, which were evaluated by polynomial fitting of the sigmoidal shape experimental curves, and it was found to be 44.37 kcallmole. The determination of the rate-controll ing mechanism was based on some criteria used for the discrimination among the three probable mechanisms of precipitation (diffusion, mononuclear nucleation, polynuclear nucleation). These criteria utilise various funetions of the recovery 'a' of iron precipitated versus time, the most important of which are the chronomals. The results of the kinetic analysis procedure showed that the polynuclear nucleation growth mechanism controls the precipitation of iron as sodium jarosite. This was confirmed by the high value of activation energy, excluding diffusion as the controlling mechanism.

Jan 1, 1993

Magnetic separation using particle rotation in a continuously rotating magnetic field offers very low to insignificant non-magnetic particle entrapment, and precise magnetic fractions. The precision of rotating magnetic field separations makes the method ideal for dry laboratory magnetic analysis work, where conventional laboratory magnetic separators can give misleading or uncertain data. The very low entrapment characteristics make the method ideal for entrapment-critical separations within the diamond exploration industry or in gold recovery. A single wet rotating magnetic field (RMF) unit is able to achieve a cleaner separation (at similar or better recovery rates) than a three-stage separation using conventional wet drum separators. The RMF separator is able to work effectively at particle sizes below 50 ¦m, and RMF separation could, at least in theory, be used down to single domain particle sizes. Rotating magnetic field (RMF) separation is carried out by magnetically spinning the particles at frequencies up to 300 Hz. The particle rotation itself may be used to roll the particles out of the separator. At angular velocities of 100 Hz, magnetic flocs are unable to form, and any entrapped particles are energetically expelled. In an RMF separator, the outer drum can be stationary while the inner magnet rotor rotates, allowing, for example, the injection of cleaning water underneath the separating magnetics to help remove small suspended non-magnetic particles.

Jan 1, 2000

By Scales PJ

Fatigue is the primary cause of failure of structural and mechanical components subject to dynamic loading. Recognition of this basic fact and the development of appropriate techniques and details are important in the design and repair of off highway trucks (OHTs). The frames and appendages of OHTs and other mobile plant used in the Pilbara are subject to tough operating conditions. Any fatigue-prone details quickly show up and become a maintenance liability of considerable concern. Much of this equipment is approaching the limit of its fatigue life and maintenance managers face decisions on whether to repair or replace. Even new equipment often contains some poor details which suffer distress soon after commissioning. In those cases a repair is required which will reinstate the detail to its original intended design life. Repair details must be practical and cost effective. They must also be tailored to the capability and expertise available in the field or in local manufacturers' establishments. This is particularly important where original equipment was manufactured overseas and long delivery times are involved. Lessons are drawn from components which have failed, using the evidence constructively, to provide an upgraded part or an improved substitute. With the experience now available it is relatively easy to extrapolate to cover new problem areas. This paper describes specialised techniques of mechanical fastening and detailing for low fatigue susceptibility, built up over many years of experience with OHTs and other mining plant and equipment in the Pilbara.

Jan 1, 1982

By Clift N

Lead concentrate from the Isa and Hilton lead-zinc concentrators of Mount lsa Mines Limited is smelted at Mount Isa to produce a lead-silver bullion. This bullion is cast into four tonne blocks and shipped to Britannia Refined Metals Co Ltd, NorthDeet, England and to plants in Asia for refining and marketing. The traditional treatment stages at Mount lsa are sintering, smelting, and drossing and casting, with some of the sinter plant feed being pre-treated through an Isasmelt plant.A commercial scale lsasmelt based lead smelter was commissioned in early 1991.

Jan 1, 1993

By T Leach, F Kaiqiang

The Jianchaling gold deposit is located about 1200 km south west of Beijing in central China. The deposit was discovered in 1988 by the Northwestern Geological Exploration Bureau (711 Exploration Team). Sino Gold Limited, an Australian based company, developed the mine in 1998 and is currently operating a 1000 t per day underground mine, producing about 80 000 ounces of gold per year. The pre-mine resource for Jianchaling was 1.6 million tonnes at 9.85 g/t gold. The deposit occurs within the east-west trending Mesozoic Qinling-Dabie orogenic belt formed during the Yanshanian Orogeny. In the Jianchaling region, gold mineralisation is primarily hosted by regional west-northwest to east-southeast striking faults, the most important of which, the reverse sinistral F145 fault, hosts the larger gold deposits including Jianchaling. At the mine scale, the most important zone of mineralisation is localised within a shallowly north dipping dilation on the F145 fault. Proterozoic dolomite forms the hangingwall and serpentinite and talc schist the footwall to the fault. Within the footwall, serpentinite is the most important host rock to mineralisation. Initial alteration involves replacement of serpentine to dolomite ¦ pyrite, talc to ankerite ¦ pyrite, and magnetite and chromite to pyrite, the latter locally through a transitional hematite phase. Proximal to feeder structures, the carbonate minerals have undergone partial dissolution and replacement to quartz. Gold is related to arsenean pyrite and marcasite rimming and replacement of early-formed pyrite, and associated with iron release during the processes of dolomitisation, silicification and carbonate dissolution.

Jan 1, 2004

By B Hayes

The Ambuklao and Binga Rehabilitation Project is a 175 MW hydro power project currently under construction across dual sites in the north region of Luzon Island, Philippines. When it was built in 1956, the Ambuklao Dam harnessed the second largest hydro-electric reservoir in Asia. However, due to landslide erosion and prolonged silt infiltration caused by an earthquake in 1990, the power plant has been rendered inoperable since 1999.To bring the power generating facility back to life, the project scope entails the rehabilitation and construction of civil structures, shafts and tunnels. A major component of these works is the decommissioning of a section of the seven metre diameter headrace tunnel by installing a concrete plug. The headrace tunnel is part of a closed waterway system that connects the dam via a shaft, exhibiting a hydrostatic pressure of 13 bar (1300 kPa) at the location of the new tunnel plug. In addition, the power station ball valves have seized ajar and the damaged intake riser is unsafe toaccess thereby requiring the plugging operation to be carried out under live flowing conditions.Working under hydrostatic pressure and live conditions, the headrace plug will be an underwater tremie pour operation that includes drilling and concrete injection through blow out preventer caissons installed in the floor of an underground chamber above the tunnel. The purpose of this paper is to describe the key engineering and planning components involved in this operation including pre- and post-grouting, chamber crane, sonar, local water compensation, jet flushing, drilling, caisson installation, and concrete design, production, delivery and placement. The success of this task rests on the strategic preparation and operational management of risk and safety in a challenging rural environment.

Mar 8, 2011

By Paine GG

The in-situ retorting of shallow oil shale deposits is an attractive alternative to the material handling problems of conventional open pit mining techniques, which involve removing overburden, fragmenting and transporting the shale to a fixed retort, and finally disposing of the hot spent shale.For in-situ retorting to be successful, the oil shale has to be fractured and the fragmented rock expanded into a void, to allow controlled propagation of a flame front through the in-situ retort. The principles of cratering with explosives have been used to develop a process for the in-situ fracturing of a thin oil shale deposit overlain by a formation of porous rock. The overlying porous rock formation is first compressed by explosive charges to create voids in the porous rock. The oil shale is then fragmented and pushed in to the voids with separate explosive charges. This paper discusses methods of creating voids in porous rocks with minimal surface disturbance, and then methods of obtaining the most uniform fragmentation of the shale. The whole process can be completed, in practice, in one blast. The results of an experimental blast are presented, and possible modifications are then discussed.

Jan 1, 1985

By Chaves AP

This paper describes an investigation on the surface properties and mechanisms involved in the agglomeration of iron ore. For this purpose, an organic binder (carboxyl-methyl-cellulose (CMC)) was used in substitution of bentonite, the classic binder in iron ore concentrate agglomeration. Recently, a renewed interest of the iron ore producers in Brazil to replace bentonite for an organic binder, because of the economy that can be achieved in the, blast furnace operation. These savings are mainly due to the lower aluminum silicate addition which decreases slag volume and the improved pellet metallurgical properties which have the potential for lowering hot-metal production costs. Also organic binders are effective at lower addition levels, which results in lower storage and transportation costs. It is very important in Brazil because of the vast geographical area since transportation is made mainly by truck. Another advantage of organic binders is that they have low ash contents, and therefore most of the binders bum. off during the pellet firing operation. Previous studies have demonstrated the possibilities of the use of CIVIC, but in addition to its high cost, the pellets presented improper behavior at high temperatures or when prepared with high moisture levels. In the investigation here described, these problems have been solved through the addition of other reagents to CMC.

Jan 1, 1993

This paper presents a resume of the likely profitable mining areas in New Zealand. It covers the main "minerals" - gold, coal, oil and gas, ironsands, silica sands, clays, lump silica, perlite, sulphur and limestone.The potential mining projects are depicted on a map of New Zealand together with the associated works involved in hydro-electric and geothermal power development requirement for industries such as aluminium, nickel ferro-silicon or silicon carbide production.The political need for mining development to relieve unemployment and reverse emigration is stressed. A case is made for exploration and development assistance by government in labour re-training, energy supply and transportation, if the tremendous losses through lack of use of human and industrial resources are to be rapidly reduced. These losses are currently estimated at $10,000,000,000 per year.The need for protection of the sanctity of contract and security of tenure of all mining operations is touched on briefly as is the need for a reasonably balanced view on conservation. However as both of these are more properly covered in papers on the legal and environmental aspects of the mining climate they are presented here only as they affect the economy of the mining operation.Finally there is a brief comment on the mining climate in New Zealand relative to Australia and South Pacific mining operations.

Jan 1, 1990