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By Kavetsy A

In surface mining operations, the ease with which a muckpile may be dug is a dominant factor in mining efficiency. Within broad limits this is largely independent of the fragment size dis- tribution, since the equipment used to move the broken rock is generally larger than in underground mines. In such cases, muck- pile shape and voids ratio within a muckpile heavily influence mine productivity. In a particular operation, the muckpile shape after blasting should be tailored to the digging equipment being used. A front- end loader is best suited to a low, flat-lying, loose muckpile, because of its fairly good mobility and small break-out force with its bucket. In contrast, a rope shovel lacks mobility, generates a much larger break-out force with its bucket, and fills its bucket in a vertical filling motion. Therefore, it is ideally suited to well fragmented, steep faces. In situations where a dragline is used, the requirement for a suitable muckpile depends on the operat- ing scheme of the dragline. For a conventional highwall key method the preferred work- ing level of the dragline is the same as the highwall, so that the dragline may sit over its key. In this situation, the ideal muck- pile shape involves relatively little displacement of the fragmented rock, with a minimal "power trough" at the back of the blast. In throw blasting, on the other hand, it is desirable to cast as much of the spoil as possible across the pit. It is then necessary to optimize the blast design by maximizing the throw percentage under any necessary constraints (e.g. damage, vibration, flyrock, explosive cost).

Jan 1, 1988

The difference between a hypothetical and a theoretical approach is considered and the advantages in using a hypothesis is discussed. Virgin horizontal stresses play an important role in stabilising strata which bridge across an excavation, and reduces the tensile stresses which develop in a beam subjected to bending. Simple formulae are deduced for the bridging of a thick massive stratum under such conditions. At shallow depths, tensile failure on the upper side of the beam is the most likely cause of fracture, but below a certain depth this gives place to compressive failure on the underside, with the possible incidence of rock bumps. The presence of strong massive beds delay the onset of subsidence and may restrict the width of the subsidence trough. If the material involved in the caving is strong, this will reduce the final subsidence, especially at shallow depths. The British regulations for the control of aquifers and their dependence on the strain developed at the seabed are discussed. As an alternative, the concept of a disturbance factor is introduced to permit the consider- ation of aquifers at depth, leading to an explanation of the make of water on the first faces to be mined in the Selby Coalfield. 'Elie paper closes with a brief consideration of the different roles played by longwall face supports in the control of readily cavable strata, and the control of strong beds which hold up in the waste.

Jan 1, 1986

By P Ireland, S Mitra, G Evans, A Wang, M M. Hoque

This work presents an experimental study of flow dynamics in a bubble column system (crosssection: 100 mm × 100 mm) using a non-intrusive optical technique with targeted application in a novel REFLUX™ Flotation Cell. The study had two aims – measurement of the bubble size distribution (BSD) and local energy dissipation rate in the system due to bubble motions over a low range of gas flux varied from 0.02 to 0.08 cm/s without impairing the visibility of the system. A central bubble plume was generated by injecting compressed air through a sintered glass distributor in quiescent liquid. Highspeed shadowgraphy imaging was performed to determine the BSD in the presence of surfactant (Sodium Dodecyl Sulfate (SDS) concentration ~ 10 ppm). The BSD exhibited a unimodal shape at different locations of the column for all gas flux cases. A non-intrusive particle image velocimetry (PIV) technique was used to quantify the flow field generated by the bubble motions, which was used to estimate the local energy dissipation rate. The local energy dissipation rate exhibited an increasing power-law dependency on the gas flux.

Aug 24, 2022

By T Klinge, P Field, N Sugden, D Trenberth

Mining remains one of the key industries in Australia and many other countries with mineral wealth. In Australia, mining contributes 8.8 per cent to the countryÆs gross domestic product (McKay et al, 2000). In Queensland alone, mineral and petroleum industries contribute approximately $9.4 billion to the StatesÆ gross state product (2001/02) (Young, 2003). Increasing pressure on mining companies to perform in a global marketing environment requires mine management to consider more innovative ways to manage their resources û human, plant and equipment û which includes the gathering and analysis of operations data and information for improved decision making. For any mining operation utilising rubber tyred equipment such as trucks, front-end loaders and ancillary equipment, annual expenditure on tyres and related items can be significant. Even a small reduction in tyre operating costs can have a real effect on the business bottom line performance in the short term. Tyre Application Risk Management (TYREARMÖ) can provide substantial benefits in the long term across a number of KPIs not just through reduction in direct tyre expenditure but through flow-on improvements in safety, productivity and reduced environmental impacts. Several accidents involving tyres have also highlighted an increased need to consider the hazards and resultant risks arising from operations of rubber tyred mining fleets (Torlach and Johnston, 1990). This paper presents the process and results of achieving sustained safety and business improvement through the strategic alliance between an earthmover tyre management service provider, Klinge and Co (Klinge) and a BHP Billiton coal mine. The accompanying case study demonstrates in some detail the overall methodology, and the tools and technologies used where active management of data, its analysis and decisions taken have resulted in a 43 per cent improvement in tyre cost performance and a corresponding reduction in tyre-related downtime since the beginning of the alliance.

Jan 1, 2003

By M Csar

The Nicolsons Find gold project is located 35 km southwest of Halls Creek in the east Kimberley. It was discovered in the late 1980s by John Nicolson and Stuart Skoglund, when high grade gold mineralisation within outcropping gossanous quartz reefs was found. The area has produced a modest 28 150 ounces of gold over two brief mining periods in 1996 and 2002 - 2003. Indicated and inferred resources as of September 2011 stand at 1 384 000 t at 5.58 g/t Au for 248 500 ounces of gold.The project is situated within the Halls Creek Orogen. Principal host units are metasediments and volcaniclastic sediments of the Koongie Park Formation. Minor mafic units are also recognised. Immediately east of these units, emplacement of the loadstone granite is believed to have provided the structural setting for the later gold mineralising event.Mineralisation is hosted within a broad, brittle-ductile arcuate shear zone about the western contact of the Loadstone granite. In the Nicolsons Find area, the shear zone strikes north-northeast and within the shear zone, gold is hosted in a series of narrow, quartz rich veins up to 200 m in strike length, plunging moderately to the north-northeast. To date, mineralisation has been drilled to a depth of 360 m below the surface. The veins are stepped or en-echelon in nature with low gold values towards the quartz vein limits where compression is inferred and higher grades present in the dilational body of the quartz veins. Gold is fine grained and can be present with or without associated sulfides. Sulfides are generally minor and consist mainly of arsenopyrite with traces of chalcopyrite, pyrite and sphalerite. Where present, sulfides are generally indicative of higher gold values.CITATION:Csar, M, 2012. NicolsonÆs Find gold project, East Kimberley, Western Australia, in Proceedings Narrow Vein Mining 2012 , pp 31-36 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Mar 26, 2012

By Meloy TP

Several important, fundamental aspects of the grinding behaviour of mineral systems are addressed. The Levenberg-Marquardt algorithm for systems of constrained non-linear equations was used to solve the steady-state and dynamic population balance model (PBM) grinding equations to obtain the mill matrices and grinding selection and breakage rate functions, respectively. The fact that the PBM model equation Inverse Problem is degenerate or underspecified is demonstrated. Multiple solutions to the same PBM equations are provided. It is shown that there is no unique solution to the Inverse Problem unless additional constraints are provided or assumptions are made such as the Arbiter-Bhrany normalisation assumption. The severity of the non-uniqueness problem for steady state grinding is demonstrated in several examples using typical feed distributions and mill matrices. In addition, it is also demonstrated that when higher than single powers are used in steady-state mill matrix expressions during simulation or calculation (or iterative procedures are used during numerical simulation) and four or more size intervals are used considerable amount of error is propagated throughout any calculation. Each solution to a PBM, while giving the same prediction during a single mill pass, gives different solutions or predictions for mill composition upon subsequent passes. In addition, it is shown that there is a problem with building up a grinding mill knowledge base with PBMs. A similar analysis was done for the dynamic or kinetic PBM equations. The fact that the dynamic PBM Problem is degenerate or underspecified is also demonstrated. Multiple solutions to the same dynamic PBM equations are provided. Again, it is shown that there is no unique solution to the Inverse Problem unless additional constraints are provided or assumptions are made such as the normalisation assumption. Each solution to a dynamic PBM, while giving the same prediction for a given grinding time interval, gives different solutions or predictions for mill composition for other grinding times. Actual experimental grinding data was assessed to determine the functionality of mill selection and breakage functions. The functionalities obtained through constraints were compared with those obtained with the normalisation assumption of Arbiter-Bhrany which relates breakage functions to particle size distribution. The capability of the population balance model to predict grinding behavior over time in various mineral grinding systems was assessed. The required functionality of selection and breakage functions for effective prediction of grinding behavior in mineral systems is discussed.

Jan 1, 1993

Krupp Polysius AG, FRG, in close cooperation with Prof. Dr. K. Schoenert, FRG have developed the principle of the high pressure grind- ing roll POLYCOM. The POLYCOM mill basically consists of two counter-rotating rolls of large diameter and relatively small width, one of which is fixed and the other moving in slide blocks. The pressure required for comminu- tion is applied via the sliding roll by a powerful hydraulic system. The comminution takes place between the rolls under high pressure in the bed of material by nipping and compacting. The top feed size-depending on the rolls diameter -may be as coarse as conventional secondary crusher feed and the product is a compacted cake containing a high amount of fines created by micro-cracking. The amount of fines depends on the pres- sure (grinding force) applied. Operating results show that even in wet griding circuits capacity increases at downstream connected grinding mills of up to 100010 can be accomplished with an interconnected POLYCOM machine and energy savings of up to 25070 may be achieved depending on application. POLYCOM can be used in existing grinding plants for low-cost upgrad- ing of capacities but also as an advanced alternative to conventional crush- ing and grinding equipment in open or closed circuit configuration. A single industrial size 2.8m roll diameter POLYCOM machine may be fed with top feed size of up to 200mm and produce a finish product as fine- grained as known from rod and ball mills but with less energy consumption. Meanwhile, the POLYCOM high pressure grinding roll has established itself world-wide in the cement industry and is now entering the mining industry. POLYCOM machines are currently designed in industrial standard sizes of 1.0m to 2.0m rolls diameter and drive units of up to 2400 kW. This paper includes: principles of high pressure grinding, main fea tures of the POLYCOM machine, results of tests on various materials including Australian gold and copper ores carried out at the POLYSIUS research centre in Germany. Some examples of industrial applications of high pressure grinding will also be presented.

Jan 1, 1988

By S Lowjun, I Verster, C A. Thomas, E Forbes, K Runge, G V. Franks

Fine (<20 µm) valuable mineral particles are difficult to recover in conventional flotation circuits. (Trahar and Warren, 1976; Jameson, Nguyen and Ata, 2007; Kohmuench et al, 2018). This leads to a loss of valuable fine mineral particles to tailings. Recovering these particles would be of economic benefit. Novel reagents, including temperature responsive polymers, for example, are being developed to improve recovery of fine valuable mineral particles by froth flotation (Ng et al, 2018a, 2018b). The approach involves selectively aggregating the valuable fine particles and making these aggregates hydrophobic, resulting in hydrophobic aggregates of appropriate size (in order of 100 microns) being amenable to recovery by froth flotation. The polymers developed have been produced at laboratory scale but not a full scale yet. The exact cost of producing such novel polymers is currently unknown, but they are likely to be more expensive than conventional reagents.

Aug 24, 2022

The electrochemical dissolution of gold and other noble metals in hydrochloric acid using alternating current has been investigated. The experimental results show that this technique is efficient for dissolving pure noble metals and offers prospects for their extraction from wastes and poor ores.

Jan 1, 1992

By P Scott

Kaltim Prima Coal, an open cut coal mine located in Sangatta, East Kalimantan, Indonesia, operates two deep pits and two shallow pits with a truck and shovel operation. KPC produced 17 Mt of coal in 2002 by removing 120 Mbcm overburden. Geochemical investigations have indicated 20 per cent of total waste rock is potentially acid forming; ie it has the potential to create acid mine drainage (AMD). In the early years of the KPC operation, the presence of AMD had been observed in the mined out areas and in the waste rock dumps as a result of sulfidic waste rock exposure. A strategy for management of AMD from waste rock was implemented involving: sampling, analysis, modelling, selective handling and validation of final dump covers. Samples of the waste rock lithologies are collected from exploration drill holes for geochemical analysis to determine their acid generating potential. The geochemical database is used to develop the waste rock model for the life of mine pit areas. The acid forming and non-acid forming waste rock is delineated for each mining bench area for selective handling and placement within the waste rock dump during the operational stage. Each mining bench is sampled and assessed to validate the model predictions. The final dump cover is sampled to meet strict Quality Assurance requirements to ensure non-acid forming waste material is used in the outer cover of the dump. The geochemical investigation of the waste rock is integrated with mine planning to design and construct the waste rock dump to minimise the risk of generating acid. This process links the exploration stage, operation stage, and rehabilitation stage for each Pit area. The paper briefly reports the waste rock characterisation, waste modelling and strategies used for management of acid drainage by KPC.

Jan 1, 2003

By Ritchie IC

Spiral separators have been used to treat heavy mineral sands in Australia for some thirty-five years. They were used as the primary treatment method until the advent of the Reichert cone, which largely replaced them, due to its compact design and relative ease of operation. Spirals continued-to be used as the final cleaning stage before dry separation of the heavy minerals as they remained the most efficient separator for this purpose.

Jan 1, 1986

By M A. Gontalves, A F. D C Varajpo

The Rio Capim kaolin district, located in the north-east of Parß State, Brazil, constitutes one of the worldÆs largest high-whiteness kaolin reserves for the paper coating industry. It contains, at the base of the main ore, a soft kaolin that gradually changes at the top into a ferruginous duricrust followed by a flint kaolin. The flint kaolin is completely discarded during the exploitation of the soft kaolin. With the view of a more complete beneficiation, aiming at a sustainable development of the minerals industry, the use of this residual flint kaolin has been considered for the manufacturing of zeolites. Zeolites were synthesised from the flint kaolin through a reaction between metakaolinite with soda at 80¦C, for durations of 24 to 144 hours. The transformation into metakaolinite was carried out at 800¦C and was not affected by the titanium oxides. For a synthesis time of only 24 hours, a zeolite 4A very close to its theoretical definition was obtained, whereas for synthesis times longer than 96 hours, a slight formation of hydro-sodalite was also observed. The synthesised zeolites were tested as cationic adsorbents on 0.5 molar solutions of Cu, Pb, Cd and Zn. The adsorption was measured for contact durations of one and three days. It was noted that the exchange kinetics were slow and that the retention was significantly greater after three days than after one day. The retention was greater than 50 per cent of the theoretical exchange capacity for Pb, Cd and Zn, which was different to Cu, where the retention exceeded its theoretical exchange capacity.

Jan 1, 2008

By King R. L

The Bureau of Mines has developed and deployed three expert systems to give advice on mining health and safety. These are: dust control for continuous miners, dust control for longwall shearers, and methane control. All three systems query about the nature and extent of the problem. Typical questions asked deal with observed methane levels, ventilation type and quantity, cutting sequence, and what control technology is employed. Advice given does not focus on a single issue, but may suggest a variety of approaches consistent with the ability of the operator to implement the Suggestions.

Jan 1, 1988

By Dickerson A. W

The most important mining problem facing many of the established surface coal mines in the Bowen Basin area of Queensland is the rising cost of overburden stripping associated with increasing depths to coal. The Dragline-Hopper-Truck Project is one of a number of responses to this problem, and involves the design and construction of an experimental hopper followed by field evaluation of a dragline-hopper-truck mining system.Such systems, if proven feasible, could be used for a range of applications, eg prestripping, extension of depths for single pass dragline operations and solution of geotechnical problems.

Jan 1, 1992

By Simpson D, Skopakow J

This paper is one of the series of papers relating to the Melbourne Underground Rail Loop and specifically describes the structural and architectural design of Museum Station. Structural arrangement, loads and design methods of the major temporary and permanent works are briefly described for the main station and entrance works. Planning of the station concourse area, booking halls and entrances are described together with the selection of finishes for all above and below ground areas.

Jan 1, 1981

The mining industry views with the utmost concern, legislative or administrative action that inherently reduces the scope for exploration activity. Is there any basis for this concern in relation to Victoria? This paper will outline the role of the Department of Minerals and Energy and the main features of legislative provisions affecting exploration effort. The practical difficulties that confront the Department and explorers alike will be examined. The importance of industry representation to influence the direction that policy and legislative review might take, will be highlighted. Above all, the paper will establish that one essential duty of government is to ensure the provision of appropriate mining titles and security of tenure.

Jan 1, 1982

Carbonation of reinforced concrete is a potential durability issue for vehicular tunnels. This is particularly the case where elevated carbon dioxide concentrations exist and when the design life is 100 years or more. The process of carbonation can result in loss of passive protection to embedded steel reinforcement and initiation of corrosion. Therefore, tunnel design needs to consider the potential for carbonation on internal surfaces and how design life can be achieved in severe environments. This paper examines methods for predicting carbonation and how deterioration can be mitigated through appropriate concrete mix design and construction practices.

Jan 1, 2008

The areas of impact when employing high productivity long wall systems are reviewed and the financial implications of the most significant areas highlighted. A distinction has been made between availability and utilization. The need for more efficient delay recording, together with increasing control and utilization of the systems has been identified and the measurability of the latter discussed. The increased use of electronic delay reporting direct from the operating unit as the basis for operational control and a pre-emptive maintenance philosophy is seen as an important area of achieving higher performances from existing long wall production systems and Configurations.

Jan 1, 1988

The economics of gold differs from that for base metals mainly because a large component of gold demand is investment or stock demand whereby the metal is purchased and stored for monetary or anxiety motives rather than fabricated into industrial products.The second major component of gold demand is fabrication, principally into jewellery but also, to some extent, into industrial products.Supply to the Western private- gold market comprises non-Communist mine production, Communist sales (chiefly from the USSR), and, finally, net sales by the Western Central Banks, which have total stocks of about 35,000 tonnes and which are sometimes net buyers as well as sellers.The different components of demand and supply fluctuate from year to year.

Jan 1, 1984

Exposure to respirable contaminants in mine atmospheres has long posed a serious hazard to miners. The control of these hazards, some of which can have sudden and catastrophic effects and some others, slow and long enduring consequences, has been a major concern for labor, management and government alike. This concern has manifested itself in four primary mechanisms of control -- (1) regulatory control through minimum standard setting by the passage of mine health and safety laws, (2) engineering control through design and operation of mines according to the best recommended practices, (3) medical control through periodic physical examinations, wearing personal protection devices, etc., and (4) legal and social control through workmen&apos;s compensation laws for occupation related health rleterinratinn_

Jan 1, 1988