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The torsion test is considered as the best test used when the part is subjected to static or dynamic torque. Many published papers have investigated the torsion of non-heat treated metals. However, very few published papers dealt with the torsion behaviour of heat treated metals. The aim of this work was to study the effect of heat treatment on the torsion behaviour of steel alloy (AISI 01), which can be used for manufacturing small and medium drills, taps and reamers. The diameter of specimens used was 15 mm. The metal used was heat treated under different conditions, then torsionally tested. The results of torsion test were divided into two groups: results obtained during elastic limit from which the shear stress, shear strain and modulus of rigidity were calculated, while from the results obtained during plastic limit the plastic depth was calculated by applying derived equation when the angle of twist was more than yield value. The results obtained indicated that the value of hardness alone is not sufficient to establish heat treatment conditions. Rather, it was found that the determination of plastic depth together with hardness can help in the establishing of the optimum condition which was hardening temperature of 820¦C, hardening time 20 minutes and tempering temperature 220¦C. This condition produces hardness of 60 HRc and plastic depth of 2.5 mm.

Jan 1, 2003

By A Maurer, N Pereira

Low-density explosives have been developed with trials being conducted for over 20 years and yet have still only gained limited market acceptance despite producing some very promising results. The biggest concern with industry acceptance has been disbelief that a product with lower density than the ANFO benchmark could fragment anything but the weakest of strata. Trials have been carried out with products such as diluted ANFO, low-density ammonium nitrate (AN) and various other mixes, although it has been only recently that low-density explosives have been accepted as a serious alternative to traditional products such as ANFO and heavy ANFO. The recent uptake of low-density products has been the result of several key factors: the current resources boom forcing AN supply issues, the development of new handling techniques, and a far better understanding of the utilisation of such products. This paper highlights the benefits of low-density products available in the market and focuses on the situations where low-density explosives can provide the end user with benefits that would otherwise be achieved through more time consuming methods. Through correct implementation, low-density explosives can provide the blast designer with another option when looking at the optimum method of breaking the rock. This while still controlling the other limiting factors such as cost, environmental impacts (noise, vibration, dust and fumes), coal damage and safety (stable walls).

Jan 1, 2005

The problem of instantaneous outbursts remains unsolved after over a century of events and the investigation of the mechanism of the phenomenon and means of treating it. Outbursts have occurred of up to 5,000 tonnes with perhaps up to 500,000 m3 of accompanying gas, either methane (CH4) or carbon dioxide (C02) or mixtures. The low density of CH4 and the high density of CO2 give particular problems. Australia with both gases has experienced outbursts for 85 years with fatalities as recent as 1978. The Bulli Seam of the Illawarra area of the Sydney Basin is affected and outbursts with both CH4 and CO2 occur. The Northern and Central Bowen Basin also experiences outbursts with both gases. Proneness of affected mines is related to the high rank of the'coal and the proneness of the seams-is localised according to depth, gassiness, structure and development geometry. Proneness may be reduced by appropriate choice of mining methods. In addition to outbursting mines other mines have symptomatic phenomena. Traditional preventive methods have been used and control by induce- ment has been practised. A method of local prediction for widespread use has not been achieved although locally successful prediction 1Superintendent Rock Mechanics and Strata Control, The Broken Hill Proprietary Company Limited, Steel Division Collieries, Wollongong, N_RW

Jan 1, 1980

To follow the development of the central crushing plant it is necessary briefly to outline the history of the Lake View and Star Limited. This Company, when first constituted, took over the properties of the Lake View Consols, Hannan's Star, and Chaffers Gold Mines.The Company then treated the ore won from these leases at two dry crushing, all-roasting plants, situated adjacent to each other on the site of the present Chaffers Treatment Plant that handles all the ore won by the Lake View and Star Ltd.SUbsequent to the initial union of the three companies mentioned, the Ivanhoe Gold Corporation and the Golden Horse Shoe Ltd. were absorbed. Still later, and after the original crushing plant was erected, the Associated Gold Mines of Australia were purchased.A very extensive development policy was adopted by the Company's management in the late 1920's, and as the underground programme progressed, it became eVident that a large treatment plant would be required. Wet milling of the ore, followed by flotation, was considered desirable, and the necessity of a central crushing plant capable of producing a feed that could be handled by the wet ball mills attached to it was obvious.At this time, each of the properties absorbed had its own crushing station, situated adjacent to the respective...

Jan 1, 1948

By Donchak PJ, Lang SC, Hammond RL, Bultitude RJ

The Hodgkinson and Broken River Provinces form the northern part of the Tasman Orogen. They are separated by a broad belt of Late Palaeozoic igneous rocks, but were probably originally continuous. They are bounded to the west by a system of major faults (Fig. 1) which separate them from the Georgetown Province. Although largely Precambrian, the Georgetown Province includes probable Siluro- Devonian granitoids, and in the south adjacent to the Broken River Province, metamorphosed Early Palaeozoic(?) volcanics and sediments of the Greenvale Subprovince. South of the Broken River Province, the Lolworth-Ravenswood Province includes probable Precambrian rocks, Cambro-Ordovician volcanics and sediments, and voluminous Ordovician to Early Devonian granitoids. The first systematic studies of the provinces were the 1:250 000 scale mapping programs by the Bureau of Mineral Resources and Geological Survey of Queensland (White, 1965; de Keyser and Lucas, 1968). These and subsequent regional studies were reviewed by Arnold and Fawckner (1980). Remapping by the Geological Survey of Queensland since 1982, and a concurrent regional study of the deformation by Hammond (1986) have provided much new data. We acknowledge the contribution of other members of the GSQ field parties - L. Cranfield, J. Domagala, B.G. Fordham, P. Green, R. Halfpenny, R. Hegarty, L. Hutton, S. Law, D. Macansh, T. McLennan and M. Scott.

Jan 1, 1987

By Pyrih R, House A, Shangraw J, Silva AJ

Sunbeam Mining -Corporation has the inten mine with heap leach gold recovery, near spent ore indicated a relatively high ar topographical configuration, the spent across a small drainage and a lake. Du permit for spent ore disposal from th agencies, concerns about the potential contamination by the arsenic were expres conducted extensive studies to addre contamination. These studies consiste( geochemical and geotechnical parameters underlying the proposed disposal si geotechnical investigations were also hydrologic characteristics were include with the use of an IBM PC computer. :ion of opening an open pit gold Stanley, Idaho. Testing of the ?enic content. Due to the local ore was planned to be disposed :ing the process of obtaining a federal and state regulatory for surface and ground water .ed. Sunbeam Mining Corporation is the potential for arsenic of laboratory testing of both of the spent ore, and the soils te. Field hydrogeologic and -onducted. Local climatic and 1 in the analysis of these data Conclusions of studies indicated that although the seepage through the spent ore disposal would contain an elevated dissolved arsenic content, the hydrologic and geochemical characteristics of the site would prevent arsenic migration into the local ground water system. The attenuation of arsenic on soils with high clay content, and dilution after reaching the ground water table would lower the arsenic content to acceptable Concentrations.

Jan 1, 1988

Over the longer term, the adoption of new technology is an essential component in the endless tasks of reducing mining costs, improving safety and improving environmental standards. However the choice of which of the many available new technologies to adopt and which not to adopt is not easy and the price of mistakes can be very high. The most important issue for mine developers faced with making such choices is knowing whether or not a new technology has been developed to the stage where the timing is right for its adoption. A system for categorising new mining technologies is provided. It provides a basis for more easily reaching common understandings about various new technologies and the background information supplied provides an understanding of what it takes to get new technologies to the proven stage and the risks of never getting there. Wherever possible, new full-scale mine developments should not rely on unproven technologies. Approaches to handling situations where a proposed new mine development is not feasible on the basis of proven technologies are also provided. If any commitment to the use of unproven technologies is made, a guarantee of high quality development support from the supplier of that technology is essential. Several case studies of successful and unsuccessful new technology development programs at BHP are Provided.

Jan 1, 1997

By Grader F. E

A linear motor properly wound can serve as a mechanism for separating paramagnetic sulphide minerals, like pyrrhotite, from other sulphides and associated gangue minerals. The effective- ness of separation depends on the energising current of the separator, the frequency of the a.c. cycle, and the particle size of the minerals. The speed of travel of the minerals over the surface of the separator is also a function of particle size, and appears to be constant. The movement of pyrrhotite, magnetite and iron filings of comparable size fraction (150um +74pm) on the linear motor surface has been observed using a cine camera. An attempt has been made to give a theoretical basis for the movement of the particles by calculating the minimum electrical energy required to move them. Further, the rate of decay of magnetic moment of the particles has been estimated for magnetite and it has been found that sufficient residual magnetism existed in the particles after they had been exposed to the first half of an a.c. cycle for them to have like polarity with the second half of the cycle. The particles are therefore repelled from the motor surface every second half of the cycle. This repulsion due to remanent magnetism is the probable cause of particle movement over the linear meter surf, e.

Jan 1, 1980

A thick sequence of alkaline intrusions and volcanic rocks underlies a Quaternary caldera on Liliir Island. The sequence is host to a still active sub-aerial hydrothermal system and associated epithermal gold mineralisation. Sub-horizontal alteration horizons exhibit progressively increasing chondrite norma-lised (La/Lu) en and (La/Sm) cn ratios from unaltered shoshonites, to the potassic alteration zone, to the argillic altera-tion zone to the advanced argillic alte-ration zone. The increasing fractionation of HEE, and especially of LHEE, up the alteration sequence is the result of de-creasing pH, temperature and alkalinity of the hydrothermal fluids with increa-sing alteration intensity. HRE3 were especially mobile in argillic and advanced argillic alteration units characterised by acid fluid conditions and large fluid volumes. Abundant Cl, S and CO2 within the hydrothermal fluids and thus abundant REE complexing agents and large fluid volumes favoured the mobility of REE during hydro-thermal alteration of the volcanic rocks and intrusions. Steam escape, mixing of the gases with groundwater and a change from a magmatic neutral chloride hydro-thermal system to a meteoric acid sulphate system was accompanied by liquid/vapour ratio changes, pronounced alkalinity, pH and temperature decreases, and fluid/rock ratio increases. This caused the mobili-sation, fractionation and deposition of PF.F.

Jan 1, 1990

By T D. H McGrath, R Byleveld, W P. Staunton, J J. Eksteen

"The Gold Technology Group at Curtin University through the AMIRA P420 series of projects has recently developed the integrated liberation leach model (ILLM) for optimisation of gold plants. The model encompasses recovery by both gravity (batch centrifugal concentrators or BCCs) and leach adsorption (CIP/CIL) circuits. The ILLM essentially combines the Group’s well-known standalone models (ie gravity and SIMCIL) to create a robust simulation package.The ILLM process model provides a tool for sites to determine optimum set points for operations to optimise recovery (eg target grind size). It can also be used to predict the effect on gravity recovery, leach recovery and overall recovery when changes are made to circuit design, either temporarily (eg a leach tank taken off-line for maintenance) or as part of a circuit expansion (eg expanded gravity circuit capacity, or addition of leach tank capacity).This paper discusses the capability of the ILLM process model by highlighting a recent case study. The paper also addresses the test work and plant data required as model inputs, as well as limitations and the application of the ILLM to greenfield projects.Citation:McGrath, T D H, Staunton, W P, Eksteen, J J and Byleveld, R, 2016. Application of an Integrated Liberation Leach Model for Process Optimisation, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 173–178 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

A model has been developed for drum scrubbing which allows selection of geometry and power input. Specific aspects considered are: Calculation of total static and operating volumes. Total residence time based on total operating volume. Solids residence time based on solids operating volume. Selection of the aspect ratio. Alteration of operating fill to allow for smaller or larger feed openings. Selection of proportion of critical speed. Calculation of shell and motor power requirements. The model uses either solids or total residence time to calculate the required operating volume. The solids residence time is based on the proportion of coarse solids in the feed. Material finer than the reject size is considered as part of the slurry. The solids operating volume is the static volume plus the surcharge on the discharge weir required for flow of the solids from the unit. The total operating volume is the static volume plus the surcharge on the discharge weir for the total flow to exit the scrubber. The burden density is calculated from the coarse solids bulk density and the slurry density that includes all the fine solids. Power is calculated using the Liddell and Moys correlations for burden position and shape, and the operating rotational speed. Results from the model (especially power) have been verified from industrial installations of significant size. Predicted and observed power draws are within two per cent. A check against the JKMRC mill model shows power draw prediction agreement to within four per cent.

Jan 1, 2004

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

The equipment and general smelter layout for the Mount Isa Copper Smelter were designed by engineers associated with the American Smelting and Refining Company and by Mount Isa staff engineers. The final notice of site was dictated by the need for 'building the smelter near the existing Mount Isa power house to enable full use to be made of the steam from the waste heat boilers. Although much excavation work was necessary before concrete foundations could be poured, the location lends itself to further expansion should it become necessary. The plant is designed and constructed to involve straight line smelting operations which include the following major steps in the overall scheme.1. Charge make-up.2. Roasthig.3. Reverberatory smelting.4. Converting.5. Refining.6. Casting.CHARGE MAKE-UPA system of proportioning bins is provided for preparing the feed mixture for the roasters, Sulphide concentrate containing 24% copper wiil be delivered by belt conveyor from the filter plant to the smelter storage patio. This is a large roofed concrete floor that provides a maximum storage capacity of 8,000 tons of concentrate. Eight proportioning bins located below but adjacent to the south end of the patio will be used for actual charge make-up from which concentrate, ore and flux will be proportioned to the feed belt and conveyed to the roaster feed hoppers. Four of the proportioning bins, 80 tons capacity each, will receive...

Jan 1, 1953

At some time in the mining life of an open cut coal deposit, consideration is usually given to determine the point at which underground mining becomes an economic proposition or even necessary. This can occur anywhere from the pre-feasibility project stage to decades after commencement of mining. Options which can be considered include the extension of the life of the open cut by use of larger equipment, the utilisation of highwall mining techniques and the introduction of low capital start-up or full underground development. The primary focus is always the minimisation of the total unit cost (including capital )of clean product. The transition point at which an undergound mining operation becomes more economic than an open cut operation is not a simple evaluation and depends on many factors, particularly on the nature of the deposit itself. The main general determining factors of the transition point are related to the three factors of mining resource, the mining method that can be used and mining cost issues. Mining resource issues include geography, geotechnics, strip ratio, geology and the size of the deposit. Mining method issues include highwall mining, extending the life of an open cut, the environment, available roof support technology, product yields and the availability of appropriate workforces. The mining cost factors discussed include capital and operating costs and the impact of productivity and management. All these factors impact to a varying extent on the transition point.

Jan 1, 1997

By P J. A Lever

This paper presents details of CRC MiningÆs work with waterjet assisted blasthole drilling. The objective of this work was to investigate techniques that reduce the cost and increase the productivity of blasthole drilling. The focus is on a technology that uses a high pressure waterjet to assist the conventional rotary rock cutting action of a tricone drill bit. The potential benefits of this technique are increased productivity, reduced drill bit wear and reduced hole deviation and hence improved quality of drilling. This paper describes the results of a laboratory based experimental program comparing conventional tri-cone drilling performance to the proposed waterjet assisted approach. Additionally, work has been completed looking at the more practical issues around the collection and sampling of drill cuttings and water recovery (recycling) when drilling with a waterjet. These studies have demonstrated that waterjet assisted drilling can significantly increase the rate of penetration over conventional rotary drilling. For the best-case experimental result, the relative improvement was over 40 per cent. More importantly, it is a starting point for examining alternative uses of the additional drill productivity obtained from waterjet assisted drilling. For example, increased drill productivity could be used to improve rock fragmentation by drilling a tighter blasthole pattern in the same time period. an existing drill fleet, then the drill fleet size could be reduced, or improved rock fragmentation could be achieved by drilling a tighter blasthole pattern within the same time period.

Jan 1, 2004

By A Williamson

The New South Wales Department of Mineral Resources objective is to use data and information to undertake a detailed analysis of incidents and accidents to identify risks so that the predictable can be foreseen and avoided. The Department of Mineral Resources has established a computerised database called COMET (COmmon Mines EnvironmenT) to capture information on accidents incidents, inspections, audits and accreditation in improving safety and environment performance. This data together with data from Coal Mines Insurance and WorkCover NSW is being used to provide trend and comparison information. The NSW Injury Risk Management Research Centre at the University of NSW has been engaged by the Department to collate and prepare a detailed analysis of the data. Through this process, five areas have been identified for further research. These being: electrical energy, mechanical equipment, work environment, hours of work, and contractors involvement accident and incidents. The paper covers: the establishment of a mix of performance measures for the industry to indicate whether the safety performance is improving; the provision of data to provide useful comparisons and benchmarks against which companies can compare performance; the development of positive performance measures; the findings and outcomes of the detailed analysis of electrical energy; shocks; the provision of information to industry; an outline how the data is being used to determine departmental; operational priorities; and future plans to undertake research into the other areas identified.

Jan 1, 2003

Optimising drill performance has always been a primary goal of drilling and blasting managers. Improving drilling rates and utilisation will ultimately drive the cost per foot or metre downward. Additionally, more consistent production will ensure shovel or dragline performance goals are met and the chances of machine idle time is minimised. Over the past 20 years, many studies have examined rotary drilling factors and performance issues. In most cases a common theory points to energy input versus drilling output. Indexes such as specific energy and total work energy have been -developed to quantify the drilling process. As general engineering principles dictate, energy is required to drill rock by overcoming compressive and shear strengths. Concurrently, the greater the energy input, the faster the penetration output. Therefore, by examining the basic drilling energy parameters, optimisation is possible. The principles of rotary drilling are driven by five factors. When optimised individually and as a system, drill performance will improve. Most recent studies all agree that a performance relationship exists between bit load, bit rotation, and hole flushing. Additionally, proper bit selection and most of all, the operator, can have a tremendous effect on drill productivity. By analysing these factors and establishing the best case scenario, an overall drilling system can be engineered to match the mining characteristics. Furthermore, by balancing these factors, a lower cost will be achieved through increased production rates, maintenance costs, and effective drill utilisation.

Jan 1, 1995

By S D. Dessureault

In one of North AmericaÆs largest mines, which contains more than six active coal-producing faces, mine controllers must meet the complex challenge of adhering to the mine plan while also ensuring customer quality. Fleet management systems (FMS) provide many different avenues to control production flows, from the faces to the various pit crushers. Nonetheless, mine controllers must balance a variety of factors such as unplanned downs, differing customer demands, their own daily key performance indicators (KPIs) related to equipment utilisation, among others. Deviating from the short-term mine plan is the most common means of balancing the other factors, since adherence to the plan is traditionally only measured during the weekly variance meeting with engineering staff. However, such deviation may be one of the most costly responses, as long-term scheduling issues may arise such as multi-face dead-heading or insufficient stripping. This paper focuses on the development of a system for real-time adherence to mine plan within a control room environment. This system is part of a larger blending-focused, multi-million dollar project with elements of a centralised remote control room, developed at the University of ArizonaÆs Mining Information Systems and Operations Management (MISOM) Mine Control Center (MC2). The mine plan (MPL) component of the overall blending system integrates both historical and real-time FMS data with mine plan requirements directly sourced from original systems (no additional input required). The measures, displayed largely as graphs, have tools to help controllers manage the production to facilitate adherence to the plan. Some measures are designed to motivate crews to perform by inciting competition between crews, softened through a study of the controller culture. The MPL component was deployed at the mine, and the before and after deployment adherence was measured. This paper discusses the technical development of the new tool, its deployment, and an ethnography (study of culture) to understand controller motivation.

Sep 26, 2011

By J D. Lubben

Hibbing Taconite is a Lake Superior-type granular magnetite taconite deposit occurring within the Biwabik Iron Formation along Minnesota’s central Mesabi Iron Range. The deposit is situated on the northern margin of the Proterozoic Animikie Basin. The deposit strikes northeast, dips gently southeast, and occupies 10 km of strike length. Mining focuses on 50 m of granular cherty and laminated slaty taconite within the Lower Cherty member.Ores generally consist of a quartz, magnetite, siderite, ankerite, minnesotaite, stilpnomelane, and haematite mineral assemblage. Processing is optimised by exploiting the physical and chemical variations that exist between three major ore types. Taconite ore averages 20 per cent magnetic iron (MagFe), 27 per cent weight recovery (WtRec) and produces a final concentrate with 4.5 per cent silica (SiO2). Since 1976, production has totalled approximately 237 million long tons (Mlt) of pellets (8 Mlt per year rated capacity).Ore processing uses a simple fl ow sheet of autogenous grinding (<0.044 mm) followed by two phases of wet magnetic separation, fi ltering, limestone/bentonite addition, balling, and firing to create pellets averaging 66 per cent total iron. A Liberation Index (LIS) is used as a primary guide for ore grading and metallurgical control. Grind requirements, magnetite liberation and silica grade are closely monitored to ensure plant optimisation and product quality.A recent program of benefi ciation of low-grade ores by in-pit crushing and dry magnetic cobbing has demonstrated that low-grade ores (<17 per cent MagFe, <25 per cent WtRec) can achieve a signifi cant metallurgical upgrade (up to 25 per cent MagFe and 40 per cent WtRec). This operation recovers 60 per cent of the total crushed volume, and has a calculated effi ciency factor (magnetic iron recovery) of 79 per cent. This paper discusses the benefi ts of this upgrading and its effects on ore blending and processing.

Jul 11, 2011

By Y K. Leong

Iron ore tailings typically containing 40 to 50 per cent Fe can be beneficiated to iron ore products containing 54 to 60 per cent Fe. The impurities are comprised of clay, quartz, cristabolite and TiO2. Goethite and hematite are also present. At high concentrations of 55–60 wt% solids, the tailings displayed high yield stress and viscosity and cannot be pumped over long distances. Composite additives comprising of NaOH, phosphate-based additives and sodium metasilicate are found to reduce the viscosity and yield stress very significantly by a few orders of magnitude. The yield stress of 100 Pa can be reduced to almost zero. At this state, dilution of the tailings with its process water to 40 per cent solids causes the coarse and high-density iron ore particles to separate from the colloidal fractions located in the supernatant after a few minutes of sedimentation. Separation by decantation produces a sediment with an Fe content of 54 per cent from tailings with 47 per cent Fe. Another tailings sample with 48 per cent Fe was beneficiated to greater than 57 per cent Fe using NaOH-metasilicate-polyphosphate additives and employing an additional washing step. The use of other composite additives, NaOH and polyphosphates, increased beneficiated product Fe content to greater than 60 per cent from the same tailings. With the current iron ore spot price of more than US$180 per tonne, the cost of this treatment process even including a desalination step, if necessary, is relatively insignificant. This study has given tailings an economic value that should be exploited as soon as possible.

Nov 8, 2021