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By J Koppe, J F. Costa

A fundamental error of sampling occurs when a sample is extracted from a larger mass of ore or lot. The act of sampling requires that all particles belonging to the lot have an equal chance of being extracted. This type of sampling is called unbiased sampling. The sampling equipment (herein referred to as the sampler) should be constructed with some additional mechanical characteristics to guarantee that the samples will be unbiased. Samplers, extracting increments from a continuous flow, such as a conveyor belt, collect aliquots at regular time intervals. These time intervals relate to the number of aliquots extracted from a given mass of lot, whilst passing through the continuous flow. The frequency of extractions will influence the precision or the error of the sample (integration error). Further, the ore variability influences the amount collected from the continuous flow. Normally, the sampling protocol utilised is designed for the extractions obtained from the conveyor belt, omitting any error committed during this operation, ie the error of extracting from the continuous flow. This study aims to analyse the error of sampling a continuous flow by using a variogram with added on auxiliary functions. Each different piece of material passing through the flow will exhibit a distinct temporal variogram, which should influence the frequency of the samples being extracted for each chosen sampling error. The methodology used is presented in the form of a case study from a coal processing plant.

Jan 1, 2005

THIS instrument, depends on the principle that, over a short period, the surfaee of a porous substance from which a liquid is evaporating receives the same amount of heat by conduction, convection, and radiation as it loses in the latent heat of the evaporating liquid. If, then, the amount of heat being received by a surface can be measured, the rate of evaporation can also be obtained. The Kata thermometer is also based on this principle differently applied.The instrument, as shown in Fig. 1, consists essentially of a thermometer with a sliding which is divided by three pointers into two equal parts which may be spaced so as to cover a distance of, for example, 5° of the thermometer scale. The instrument is calibrated so that the amount of heat required per unit area of the bulb to raise the menissus is known. The method of using the instrument is as follows:The slide is first set so that thc central pointer is at the temperature of the evaporating surface.The thermometer is cooled by any convenient means so that the meniscus is several below the lowest pointer. The thermometer is then placed near the evaporating surface, when the Ineniscus begins to rise and the time taken for it to rise from the lowest to the top pointer is measured. From this and the calibration results the amount of heat retained per unit area of the bulb at the mean temperature...

Jan 1, 1928

The Australian Mineral Industry has to compete on world markets, so its mineral research has to be aware of overseas developments, it must be of world class, and it must utilise as many ideas as possible in order to solve those problems that uniquely affect Australian minerals processing. North American mineral and resource research may be taken as a guide to world government, industrial, contract, and entrepreneurial research trends and ideas. A number of interesting findings are noted that may guide Australian developments and strategies for the future, in minerals research and exploitation.

Jan 1, 1986

Several years and millions of dollars later, the mining and extractive industries have now started to receive and implement industry based standards aimed at achieving better performance and output from the employee. IFAP in conjunction with the mining and quarrying industry has developed a range of training courses aimed at achieving the benefits that can be gleaned from application of these standards. The establishment of a career path and appropriate training packages for personnel involved in the handling and use of explosives provides industry with a training system that previously did not exist. The opportunity to receive quality training based on industry standards and aimed at achieving industry goals will now enable the industry to optimise itÆs explosives applications.

Jan 1, 1999

By O K. Paki

A 14/12 millMAXTM pump was installed in the SAG1 grinding circuit as a trial replacement for the existing 12/10 Warman for performance comparison and in an attempt to overcome process difficulties. Krebs Engineers have developed the millMAXTM pump wet end to adapt to a variety of power frames. This system has been developed specifically for coarse material contained in mill discharge. SAG1 discharge screen undersize with a top size of 10 mm is collected in a flat bottom sump. Two 12/10 Warman pumps located on the same side of the sump, pump the screen undersize at 50 to 65 per cent solids to a distributor box which splits into two separate ball mill circuit sumps. One pump is installed towards the screen feed, while the other is towards the screen oversize discharge. The pump located towards the screen oversize discharge is prone to continual operating problems including pump bogging, high impeller and casing wear, and has consequently restricted SAG mill throughput. To rectify this pumping problem, it was decided to change-out the wet end of this pump with a millMAXTM. The design of the new pump enabled the wet end only to be retrofitted to the existing Warman pump frame, thus reducing change-over time. This was undertaken in the workshop under the supervision of a company representative where the pump, complete with bearing frame, new wet end, motor and base frame, was assembled. After installation of the millMAXTM pump during a SAG mill shutdown, performance indicators including motor power draw, sump level, and pump discharge pressure have been monitored. The trends indicate an increase in discharge pressure, low sump level, and low motor power draw. With the improved pumping efficiency there has been minimal pump bogging and no consequent SAG mill throughput restrictions. Pump wear rate has also decreased.

Jan 1, 2000

By Fuller P. G

The purpose and current practice of cable trusses in underground coal mines is briefly outlined and details of various cable truss designs are presented. The main part of the paper describes the in-situ performance of cable trusses installed as secondary supports in gateroads and recovery roads of longwall coalfaces. The performance analysis is based on the results of in-situ monitoring carried out at a number of sites at two underground coal mines within Australia. Truss performance has been assessed as load developed in relation to roof convergence, face position and time. Additionally, the influence of strata conditions, installation pattern/density, roadway layout and geometry have been taken into account. An analytical model has been developed to predict truss loads. The principal variables are listed and the basis of the model is described. Based upon behaviour observed in the field the model has been progressively upgraded and validated against measured performance. Guidelines on truss performance and factors which influence it are presented and the implications of these to the use of cable trusses is discussed. Possible methods for improving truss performance in certain strata conditions are outlined and some comments are made on the value of cable trussing compared to cable bolting in these Situations.

Jan 1, 1992

Having worked as a consultant for most of his 40-year working life, mostly as a mineral property valuer, the author has seen many poor valuations. Most were valuations of exploration tenements where the selection of the rather subjective, but necessary, geological inputs raised the main concerns. Those valuations involving iron ore prospects raise particular problems due to the special characteristics of such deposits. Iron ore is more like an industrial mineral rather than precious or base metals and Reserves are determined not by a traditional cut-off grade but by customer specifications. This is intended to be an overview/keynote paper on the current state of the growing (yet consolidating) Australian Iron Ore industry. It has now moved beyond Western AustraliaÆs æPilbara Big TwoÆ of Rio/BHPB (with the emergence of the irrepressible FMG and Hancock Prospecting) to include the YilgarnÆs æMidwest ManyÆ (including US re-entrant Cleveland Cliffs through Portman) and projects in other States. Ore types have moved from haematite Brockman to martite-goethite Marra Mamba (including the RobeÆs mesas and below water table Yandicoogina CIDs) and magnetite ore types. There are DSOs and secondary process feed. Mineral valuers have to reflect today upon these and many other determinants of value when choosing the most appropriate methodologies to adopt when technically assessing and valuing exploration tenements containing iron ore. Set against a frame work of the JORC Code (2004) and VALMIN Code (2005), the general valuation issues involved in using the cost methods (eg multiple of exploration expenditure), market methods (eg comparable sales, rules-of-thumb and joint venture terms) and income methods (eg synthetic discounted cash flow (DCF)/net present value (NPV) modelling) are discussed. Relevant factors when valuing iron ore properties are discussed, eg ore type, lump/fines ratio, stripping ratio, water table, impurities and grade, particularly the JORC confidence category of the identified mineralisation. Remoteness and access to existing rail infrastructure is a key consideration.

Jan 1, 2007

By Brown D. N, Troth D. A

Large blast furnaces demand high standards of preparation of feed materials which must meet tight specifications of chemical and physical quality. Measurement of these factors must be expeditious but the nature of the coke, sinter, ores and fluxes and the large tonnages involved requires substantial mechanical sampling plant. The equipment, its operations, and its problems, associated with the 5000 t.p.d. No.5 blast furnace at Australian Iron and Steel Pty. Ltd., Port Kembla, are described and the efficacy of chemical blending achieved in the ore blending yards and sintering operation, is reported.

Jan 1, 1976

Uniaxial compressive strength and Young's modulus values measured in the laboratory on NX diamond drill cores were examined statistically to bring out any significant differences between different locations in the mine which might require special treatment in subsequent photoelastic analyses of the mine layout. Correlations were sought between the strength and modulus and various other features of the rock. The estimated mineral content of the core correlated with the modulus of the core, but the range of modulus values was too limited to show any strong correlation with compressive strength.Strength in the vertical direction was found to be significantly higher than in the horizontal direction and the same pattern was followed by the moduli, but was less pronounced. It was concluded that, whilst the modulus variations were significant, they would not invalidate any photoelastic studies.

Jan 1, 1969

In-stope long hole drilling (face parallel drilling) is a new technology currently being applied to shallow dipping (

Jan 1, 2003

PAPERS : 1 COMPUTER AIDED DESIGN OF MINE WATER MANAGEMENT - Z KESSERU 2 THE HYDROGEOLOGICAL PROBLEMS OF GROUNDWATER PROTECTION IN MINING REGIONS - V A MIRONENKO 3 WATER MANAGEMENT OF THE MAE MOH PROJECT -òò SIRI CHITCHOB 4 WATER MANAGEMENT AND WATER TREATMENT AT GOLDPN CROSS - M P A WILLIAMS

Jan 1, 1988

AustraliaÆs success as a mineral producer and exporter rests heavily on its technological competence. That competence is based not just on adopting internationally-developed technology but also on ground breaking research conducted at Australian research institutions, many of which have global reputations. A number of forces are now operating to speed the introduction of advanced technology to mining and processing operations around the globe and this will create pressure on the Australian industryÆs ability to retain its competitive edge. Examining the foundations of that national research base and the associated culture of innovation may provide some guide to the dynamics that will be required to maintain technical competitiveness in the future.

Jan 1, 2008

By Adranyl W. W

Sub-level caving with bottom ore drawing has gained wide acceptance in rich, soft, low magnetic iron ores because it provides moderate ore dilution and ore losses. The main problem here is the high rock pressure exerted on sub-level drives situated in the sub-level sill pillars. To reduce this effect, the ore block is divided into panels. This paper illustraes the method of determining the maximum panel width providing low maintenance cost of sub-level drives.

Jan 1, 1995

By P Lilly

Blasting is the primary comminution process in most mining operations. This process involves the highly complex and dynamic interaction between two main components. The first is the detonating explosive and the second is the rock mass into which the explosive is loaded. The mechanical properties of the rock material (such as dynamic strength, tensile strength, dynamic modulus and fracture toughness) are important considerations in understanding the blasting process. However, it is the characteristics of the geological defects (joints, foliation planes, bedding planes) within the rock mass that ultimately determine how effectively a blast performs in terms of fragmentation, all else being equal. The defect characteristics include, but are not limited to, their orientation, spacing, and mechanical properties. During the blasting process, some of the geotechnical characteristics of the rock mass are substantially changed. From the blasting outcome point of view, the most notable and important is the change in fragment size distribution that the rock mass undergoes. The pre-blast in situ defect-bounded block size distribution is transformed into the post-blast muckpile fragment size distribution. Consequently, it is fundamental to our understanding of and ability to predict the blasting process that both the blastability of a rock mass and its transformation into the fragment size distribution can be appropriately quantified.

Jan 1, 2001

The Malvern Hills coal project is now in an advanced stage of development with the stripping of overburden from above former underground workings in which a 3 m seam of subbituminous C coal with very low ash and sulphur was previously mined. The main seam dips at 45¦ to the south-east, along with other adjacent potentially recoverable thinner seams, and the strike extent of past coal mining in the Malvern Hills approaches 10 km with most extraction by underground methods. Overburden and interburden is predominantly weak mudstone, with only very minor sandstone, whilst a 1 - 2 m thick veneer of Last Glaciation loess covers the area. The coal product from the present mine site will supply the local industrial market, with production planned to peak at about 20 000 tpa. Settling pond design has been based on several different approaches, including an estimate of likely inflows from the contributing catchment of about 5 ha under predicted storms having a ten year recurrence interval. A pond of about 1000 m2 in area has been constructed with its invert in mudstone bedrock, and soil slopes have been lined with lime-stabilised clayey loess silt incorporating a gravel armour layer. The pond outflow takes place via a 2 m high 1.8 m diameter concrete dewatering tower, with a skimmer arrangement to lower the pond by approximately 500 mm between storm events. The overflow water discharges to the main stream above a natural wetland, which will act as a secondary polishing pond, and this is to be enhanced in conjunction with the neighbouring forestry company. Discharge consents specify turbidity and pH as the controlling criteria, and both will be monitored at the settling pond discharge point as well as at the entry to the main stream. Investigations to date indicate that the pH of water exiting from previous underground workings is in the range 6.8 to 7.2, and that acidic drainage will not be an issue with this mine site. No dispersive clays have been identified in assessing the overburden and batter materials, although erosion during storm events is expected and all drains will ultimately be routed through the main settling pond to ensure adequate control of runoff-generated sediment. Reestablishment of vegetation on cut and fill batters remains a priority, and ongoing monitoring will ensure satisfactory long-term performance of the pond system.

Jan 1, 2003

By Chen J, Sun ZY

The present paper gives the design of a new HGMS for magnetic separation of sulphides. The main characteristics of this HGMS are using iron-cladding saddle-shaped magnetic coil for instead of the ordinary magnet, and combining reciprocal-linear motion with vibration to actuate the separation box, and the magnetic field intensity is high up to 2T as well. For improving the magnet system design, a modified finite element method is used to calculate the distribution of magnetic field intensity of separation space of the magnetic coil, and accordingly the calculation results the magnetic leakage coefficient can be determined easily, thus designers apart from the empirical way. KEYWORDS: HGMS, reciprocal motion and vibration, finte element method, saddle-shaped coil.

Jan 1, 1993

By Mosusu N

Geothermal anomalies of different types occur within distinct geological/structural settings in Papua New Guinea. According to R.F. Herring, geothermal occurrences in Papua New Guinea can be classified into two types, those related to vulcanism (Lihir, Rabaul and other series of islands along the volcanic arc) and those resulting from a regional heat flow probably caused by radiogenic sources, for instance those in the Wau/Bulolo area. The manifestation of this potential source of energy generally coincides with either converging or diverging tectonic plate boundaries. Previous inventories on thermal waters were carried out by vulcanologists from the Rabaul Observatory in the early 1960s. However, these studies rarely included chemical analyses of water and gas emissions and the investigations were carried out in an ad hoc manner, generally as a secondary activity. The most recent investigation on thermal waters was conducted on Lihir Island in connection with the development of the open pit gold mine. These studies included detailed exploratory drilling to a maximum depth of 730 m, and a water chemistry isotopic sampling and analysis programme. The hydrothermal waters were not considered as an energy source but as a hazard during the development stage of the mine. Nevertheless, the geothermal anomaly observed at Lihir includes hot springs emerging along the coastal zones with temperatures that approach 100¦C, steam, and thermal borehole waters with temperatures that exceed 200¦C. Chemical analysis results of thermal fluids from Rabaul, Talasea and other areas in Papua New Guinea generally show high total dissolved solids and low pH. In contrast, recent results from the deepest and hottest thermal source at Lihir shows a neutral pH, a Na-CI-SO4 composition and temperatures above 200¦C. Despite the concentration of chloride being similar to that of sea water, other chemical results and stable hydrogen and oxygen isotopic compositions of thermal fluids imply the source to be mixture of local meteoric water and deep thermal water rather than sea water. Results of geothermal modelling suggests that the total geothermal uptlow is equivalent to 54 MW.

Jan 1, 1997

By N Vagias, R Shaw, M Coghill, W Easman

Rio Tinto Technology and the Rio Tinto Foundation for a Sustainable Minerals Industry have funded the development of a practical floating module that can reduce water losses through evaporation from water dams at mining and mineral processing facilities by about 75 per cent. The modules, which are also suitable for use by farmers and communities, were designed for easy deployment, to allow the water to æbreatheÆ, harvest rainfall and resist wind speeds of more than 100 km/h. A large-scale demonstration trial will be conducted at the Northparkes Mine, located near Parkes (New South Wales, Australia). The objective of the trial is to demonstrate to Rio Tinto business units, community, farming and government groups the moduleÆs operating costs and water saving potential.

Jan 1, 2006

By Cecala AB

For 20 years the US Bureau of Mines has been researching strategies for improving the physical, social, and psychological work environment of the miner. The products of this program have shown that a consistent link exists between safety and productivity, and the key to this link is the use of effective human factors and management practices. There are specific research findings from the research projects of the Bureau on ergonomic design of mining equipment, redesign of tasks (especially materials handling) to minimize back injuries, human resource management techniques for increasing safety and productivity, and improved shift rotation schedules. Current research is continuing these themes with new applications to high technology mining systems, including computer assisted extraction devices and mine monitoring.

Jan 1, 1991

Key incompatible element ratios for metabasalts from the Early Permian Croisilles and Patuki Volcanics, South Island, New Zealand, provide constraints on the tectonic environment in which their precursor ophiolitic protolith formed. Two geochemically distinct metabasalt suites are recognised among both the Croisilles and Patuki rocks. Metabasalts from one suite exhibit the geochemical signatures of depleted tholeiites from oceanic spreading ridges (N-type MORB) or spreading centres in evolved back-arc basins. These N-type tholeiites show high Zr/Nb ratios (Zr/Nb = 37-62) and are depleted in light rare earth elements (LREE)((La/Y)N

Jan 1, 1987