Search Documents

By D Cohen, A Wurster

Many Southern African mining operations produce mine water which is beneficially and productively utilised on the mine sites and to support other water uses. Mine water treatment typically takes place within the context of integrated mine water management involving pollution prevention, waste minimisation, recycling and reuse as well as river discharges. Development of new and improved mine water treatment has focused on the neutralisation of metals removal, desalination of high sulfate waters and passive treatment. Mine water neutralisation processes now incorporate a combination of natural limestone and lime treatment, as well as features to maximise gypsum precipitation. The South African CSIR developed a suite of limestone-based neutralisation processes, which include reuse of CO2 and CaCO3 generated in the process. Desalination of high sulfate mine water is typically done using one of the following technologies:biological sulfate removal with different approaches to the handling of the sulfide generated in the process, and ultrafiltration (UF)/reverse osmosis (RO) treatment with different approaches to the handling and disposal of the brine. The current research and development focus is the separation and recovery of saleable products from the treatment residues and brine streams.

Jan 1, 2006

Recent data contributions to New Zealand Mesozoic terrane geology confirm the consensus interpretation that New Zealand grew by the progressive addition of material by plutonic and accretionary processes along the Gondwana margin. The data also (1) emphasise the discontinuous but inter-related nature of these processes of continental growth, (2) better establish a direct Gondwana correlation of the Western Province and probable Gondwana provenance of at least some of the Eastern Province, (3) suggest specific times and places when passive or strike-slip rather than subduction regimes are recorded along the south Gondwana margin, and (4) potentially lead to interpretations emphasising parautochthonous rather than far- travelled relationships between many New Zealand terranes.

Jan 1, 1995

Computational models are very useful for studying many of the physical mechanisms which can cause sample bias. Within such models we can predict the trajectories of all individual particles and thereby make observations which are not possible for physical systems. Physical mechanisms highlighted include congestion at the cutter aperture, particles bouncing over the cutter aperture, air drag on fine particles, waves of material being bulldozed off the belt by the upstream side of the body of square cutters, and particles being thrown by the leading edges of cross-belt cutter blades. Having identified relevant physical mechanisms for an existing cutter, we can estimate the extent to which they are likely to result in unequal representation of portions of a stream of material and thereby estimate the maximum likely sample bias.

Mar 1, 2010

By J M. F Clout

The low-grade clay-rich -1.0 mm fraction of fine iron ores have often proved difficult to upgrade and capital intensive to process when using traditional wet beneficiation technology including single or two stage hydrocyclone desliming, wet high intensity magnetic separation (WHIMS), spirals and final dewatering using fine screens. Very fine (<0.010 mm) clay-rich slimes simply follow the water split to the hydrocyclone underflow where it often impedes the subsequent processing performance of any downstream spirals and can result in troublesome direct dewatering of hydrocyclone underflow. The -1.0 mm fraction in goethitic iron ores is typically considered as waste. A new two-stage wet gravity separation flow sheet, referred to as the ædesandÆ process, has been designed to overcome these issues for the upgrading of low-grade clay-rich goethitic or hematite-quartz fine iron ores. The desand process is designed to treat the -1.0 mm range from -8.0 mm natural fines, to recover a -1.0 +0.038 mm higher-grade fraction by rejecting to tailings any low-grade clay-rich ultrafines and low density sand-size fine chert/quartz gangue and shale.The desand process consists of wet screens with a nominal 0.7-1.0 mm cut point which direct the undersize to hydrocyclones. The hydrocyclone underflow is then fed to upcurrent classifiers where the classifier middlings is sent to spirals and classifier and spirals concentrates are then dewatered using vacuum belt filters or fine screens. The three product upcurrent classifier is employed to further deslime the hydrocyclone underflow, producing firstly a coarse final concentrate, and then a deslimed middlings for feeding to spirals as well as a 0.100 mm clay and fine quartz or banded iron formation (BIF) sand in final overflow for feeding to the residue thickener. The upcurrent classifier middlings provides the spirals with a significantly cleaner feed material than traditional methods, with the end result that the spirals do not silt up with slimes and therefore can continue to run at their optimum. The upcurrent classifier and spirals form a complimentary pair, with the upcurrent classifier better able to send coarser, acceptable grade particles to concentrate and fine slimes to tailings whilst allowing the spiral to better reject coarser, subgrade low specific gravity particles. Test results for the Mayoko-Moussondji iron project, Republic of Congo, using upcurrent classifier-Wilfley Table (simulating spirals) gave acceptable mass recovery from run-of-mine (ROM) and Fe recovery from hydrocyclone underflow for HEMCOL (6.2 per cent mass recovery from ROM/43.1 per cent Fe recovery) and HEMBIF2 (5.1 per cent mass recovery from ROM/22.3 per cent Fe recovery) mineralisation types. The desand process also enables improved dewatering of -1.0 +0.038 mm product from a clay-rich plant feed.A number of new wet plants in the Pilbara use the desand flow sheet including FMGÆs Cloudbreak and their two Christmas Creek plants. Many potential new applications are being explored, with new iron ore plants in India as well as those being proposed for West Africa. Operational experience has highlighted the importance of providing clean process water to the upcurrent classifiers as well as ongoing design improvements including increased wear life, reduced maintenance and enabling a more steady feed rate to spirals.CITATION:Clout, J M F, 2013. Beneficiation of fine iron ores using the desand process, in Proceedings Iron Ore 2013 , pp 337-348 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 12, 2013

New Zealand is an exposed part of a sub- continent that was detached from Australia when the Tasman Sea opened in the Late Cretaceous. The pre-separation rocks occur in three main belts. A western belt or terrane was part of Antarctica, was continuous with southern Australian rocks, and was moved eastwards in the Mid Devonian. A central belt of Hokonui and Caples rocks can be correlated broadly with the Gympie Terrane of eastern Queensland. It was an island arc, fore-arc basin and accretionary wedge system, and it was accreted to eastern Australasia in the Mid Triassic. The third belt consists of Torlesse rocks and was possibly emplaced over the Caples rocks by at least three pulses of strike-slip, in the Triassic, the Jurassic and the Cretaceous. The three episodes of strike-slip can be correlated with regional events in eastern Australia. Pre-Cainozoic New Zealand was an amalgam of terranes that had moved eastwards from south of Australia and southwards from east of Australia.

Jan 1, 1987

By F Saloojee, F K. Crundwell

Refractory ores need to be pretreated prior to cyanide leaching for acceptable gold recovery. Pressure oxidation is one method of rendering the ores more suitable for cyanidation. The focus of this work is optimisation of autoclave configuration for pressure oxidation. An autoclave for the pressure oxidation of a feed containing pyrite and arsenopyrite was modelled, using the population balance framework. The autoclave model takes into account feed particle size, reaction kinetics and retention time. Mass balance calculations were incorporated into Cycad Process« software. This allowed for the investigation of different circuit configurations. The base case model consists of a single autoclave. The feed was then doubled and additional autoclaves were added to provide the same residence time as the base case. Four different configurations for the additional equipment were simulated. These were parallel, series, series with inter-stage thickening and parallel-series circuits. The options are compared in terms of extraction and productivity. The parallel circuit behaves similarly to the base case. The series and series-parallel circuits have higher recoveries and productivities than the base case. The series circuit with inter-stage thickening provides the highest extraction and productivity. This is because the thickening reduces the slurry volume and increases the residence time of the solids in the downstream autoclave.CITATION:Saloojee, F and Crundwell, F K, 2013. Optimisation of circuits for gold pressure oxidation, in Proceedings World Gold 2013 , pp 181-188 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Espi J

The Nena high sulphidation deposit, located in the Sandaun Province, PNG, contains a measured and indicated resource of 51 Mt of copper ore grading 0.5% Cu and 0.6 g/t Au at a 0.5% Cu cut-off. The copper orebody is overlain by an 18Mt oxide gold resource grading 0.1 % Cu and 1.4 g/t Au at a 0.6 g/t Au cut-off. The deposit is hosted in advanced argillic altered pyroclastics interstratified with lavas, volcanoclastics, epiclastics and sediments of the Debom Volcanics within the Frieda River Intrusive Complex. Foraminiferal sediments indicate the Debom Volcanics to be Early-Middle Miocene in age. Alteration is elongated along, and concentric about a northwest trending structure (Nena Structural Corridor) which is about 7km in length. The inner two alteration types, residual and massive silica-alunite are strongly brecciated and host the bulk of later hypogene Cu-Au mineralisation. Weakly mineralised weak silica- alunite and barren peripherally zoned clay alteration surround the inner mineralised alterations. The hypogene sulphide deposition was polyphasal, episodic and is zoned from north to south from covellite-enargite ¦ chalcocite (5600N to 5200N) to a mixed enargite-luzonite (5200N to 4700N) to luzonite-stibioluzonite (4700N to 4400N) in the south within a 1200m long by 300m diameter sub horizontal pipe like body. Paragenesis studies indicate that pyrite ¦ marcasite were introduced early with barite and black native sulphur before deposition of banded pyrite (melnicovite) with barite during a period of brecciation. Continued brecciation allowed bladed covellite ¦ chalcocite followed by enargite-luzonite-stibioluzonite ¦ pyrite (brassy) and minor acicular covellite deposition. Yellow native sulphur and trace amounts of galena were deposited in remaining pores. Pre-acid alteration intrusives domed the mainly volcanic stratigraphy in the southwest and post-mineralisation porphyries in the northeast truncate mineralisation. Supergene processes and erosion have modified the top of the deposit, creating a 45m thick goethitic-scoroditic-haematitic gold cap above a 40m thick (on average) chalcocite rich supergene blanket. Lesser amounts of digenite, covellite native copper and rarely seen malachite occur in the supergene copper zone.

Jan 1, 1997

Separating Particles by Horizontal Deflection in a Paramagnetic Fluid This paper describes the horizontal deflection behavior of particles in paramagnetic fluids under a high-gradient superconducting magnetic field. Movements of single particle were observed experimentally and indicated that they could be deflected to different positions. Based on these results, the behavior of groups of particles from ore samples was examined in the superconducting magnetic. It was found that these particles could be deflected and settled at a certain position due to the combination of gravity and magneto-Archimedes forces as well as a lateral buoyancy (displacement) force. Mineral particles with different susceptibilities and/or densities could be deflected to different positions, thus producing groupings of similar types of particles. The work described here, although in its infancy, could form the basis of new approach to separating particles based on a combination of susceptibility and density.  

Sep 13, 2010

The paper provides an overview of the development and content of APCOM symposia since their inception in 1961. This development is set within the context of the academic environment in which much of the research published at APCOM symposia is conducted. This environment includes rigorous external assessment of research quality at national levels and against international benchmarks, which carries significant consequences for funding and for the continued existence of the academic minerals industry disciplines. Adverse consequences that undermine the academic provision of mining and resource engineering will impact negatively on the minerals industry by reducing the level of research and education resources available to it.The traditional reductionist approach to research is contrasted with the inter-disciplinary approach that is required to address the complex systems problems that the minerals industry will have to address to ensure its technical, economical and environmental sustainability. Such an approach offers a means of raising research profiles, of establishing mutually beneficial academic-industry engagement and provides an opportunity for APCOM to take a lead role in identifying the research and development agenda for the future

Sep 26, 2011

Mount Isa Mines Limited has been mining silver-lead-zinc ore at Isa Mine for 60 years. Mining methods have evolved continuously, and current production rates of 4.7 Mt/yr are obtained from a combination of sublevel open stopping, cut and fill, and benching methods. In the near future, orebodies mineable by open stoping will be gradually depleted, and the relatively new benching method will be further refmed to replace cut and fill methods wherever possible.

Jan 1, 1993

By D C. Verdon-Kidd, G R. Hancock, M J. Saynor, J B. C Lowry, T J. Coulthard

Designing post-mining landscapes requires quantifying the short and long-term risks. In recent years, computer based landscape evolution models (LEMs) have been used to provide insight into both erosion rates and processes (i.e. sheetwash, rill, gully erosion). An important requirement of these models is high quality model input parameter data, which includes both the surface material (i.e. soil and waste rock) and climate information. However, in many cases such data is limited and in the case of climate information, the data is often short and incomplete. Here we develop climate scenarios and examine different surface material properties using a case study at the ERA Ranger mine located in the Northern Territory, Australia Firstly we develop scenarios that represent the range of future climates that may be experienced at the site. Secondly we develop a series of plausible particle size distributions based on a large sampling exercise of the waste rock material. We then test the sensitivity of different rainfall sequences and surface materials on sediment output using a well-tested landscape evolution and sediment transport model (Hancock et al., 2017). CITATION:Hancock, G R, Verdon-Kidd, D C, Coulthard, T J, Lowry, J B C and Saynor, M J, 2018. Quantifying the effect of climate and surface materials on post-mining landscape erosion – a risk approach using landscape evolution models, in Proceedings Life-of-Mine 2018, pp 122–124 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 25, 2018

By T D. H McGrath, O Baker, W P. Staunton, C Ypelaan

"The carbon-in-pulp process has been used extensively in the gold industry since the late 1970s to recovery leached gold from solution. Despite more than 30 years of experience in operating carbon circuits, average gold solution loss has remained at an average of 0.02–0.03 ppm (mg/L), higher than the ‘best practice’ target of 0.01 ppm.Process modelling, such as SIMCIL developed by the Curtin Gold Technology Group (GTG), can provide information on optimum set points; however, manual control of the circuit limits the potential benefits.An automated carbon measurement device, the Scout Carbon Meter, has been developed to allow for automation of carbon concentration measurement, and automated control of the carbon transfer pumps. This paper describes the results from the evaluation of the first two prototypes of the meter.Citation:Staunton, W P, McGrath, T D H, Ypelaan, C, Baker, O and Eksteen, J J, 2016. Optimising Carbon Management - Increasing Gold Recovery and Decreasing Costs with the Carbon Scout, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 225–228 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By Kennerley P

A significant part of the reserves of the Southern Coalfield lie beneath major water storages and their impounding dam structures. One of the functions of the NSW Government's Dams Safety Committee is to specify the particular mine layouts which can be used beneath the stored waters according to certain guidelines. A study was made of examples of the two different methods of extraction used under the stored waters as proposed by the mining company according to the guidelines and approved by the Dams Safety Committee. Using both pillar monitoring and mathematical modelling approaches it was shown that the recovery of coal from these layouts could be improved while still ensuring the long term stability of both the underground support pillars and the body of the strata. The integrity of the water storages and their impounding structures would therefore not be Affected.

Jan 1, 1986

By R Blin, R Walde, R Belli, D Inaudi

A fiber optic distributed sensing system allows the monitoring of parameters useful to determine the short- and long-term behaviour of the structure in response to the external actions, including, eg seismic activities as well as long-term phenomena such as seepage, tunneling, sinkholes, and other geo-structural movements. Monitoring of large retaining structures with such a system provides direct strain/deformation and temperature measurements on the broad interior area with an arrangement of several sensing cable lines, enabling early detection, localisation and sizing of subsurface damages. Measurements are provided every meter along the entire sensing cable, this is particularly important in such cases where the location of defects and damages cannot be predicted. Fiber optic distributed sensing cables are generally available for retrofit installation inside the dam structure using trenches on the downstream face or laid during construction below the geomembrane liner within the bedding sand layer. Mapping the cable route enables exact correlation between a linear coordinate on the cable length and a position in the dam. Cable installation is envisaged to be carried out during further raising of the embankment; additional cable sections are plugged to the previously installed cables and measured with the existing measurement system, requiring only an update of the mapping. The measurement system is placed remotely from the sensing area since a section of sensing cable can be used to link to the sensing area at the storage facility several kilometers away. The system is available for on-line, 24/7 real-time operational data management. Such fiber optic distributed sensing systems allow storage facilities to be monitored with long, accurate, continuous and precise data for geotechnical diagnostic purposes. This contribution will introduce the principles, benefits, and limitations of this technology.

Jul 1, 2021

By Tonks E. E

The earliest discovery and mining of coal in the northern area of the Greta Coal Measures at Anvil Creek in 1862 was by William Farthing, however, some official records attribute the discovery to Thomas Frost in 1864. Frost's discovery was examined by William Keen, government examiner of coalfields, and further prospecting was carried out. This was followed by the pioneering work of C S Wilkinson, government geologist in 1884. Subsequently in 1886 C S Wilkinson entrusted a detailed survey of the coalfield to the then geological surveyor, T W Edgeworth David.The outcrop of the Greta Coal Measures around the Lochinvar dome was mapped by Edgeworth David and as soon as he reported his discovery, the Department of Mines reserved in the interests of coal mining an area of 23700 acres, which extended between what became the South Greta and Abermain No I Collieries.

Jan 1, 1993

By S Nkwanyana, I Govender

Batch experiments in a 0.6 m diameter mill have shown that improvements of about 13 per cent in the efficiency of energy utilisation can be realised in ball mills by replacing 25 per cent of the ball charge by an equivalent volume of cost-free critical size pebbles from AG/SAG mills. For a mill of a given size, speed and charge filling, the rate of size reduction of ore particles depends on (i) the frequency of grinding media collisions (ii) the probability of capture of ore particles between the colliding grinding media (iii) the probability of fracture of the captured particles. The probability of fracture depends on the magnitude of collision energy. The distribution of collision energy into shear and impact events determines the relative strengths of attrition breakage and impact breakage. The efficiency of energy utilisation depends on which of the two mechanisms of breakage is more desirable in a particular milling stage. In this paper collision data from a series of DEM simulations of a mill charged with steel media and a mixture of steel media and pebbles is presented in energy spectra and spatial distribution maps. The data provides the necessary detail to elucidate the improvements in the efficiency of energy utilisation in ball mills when using a mixture of pebbles and steel media.

Aug 24, 2022

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

By Y Li, D J. Williams, E Topal

A mine waste rock dump does not have any intrinsic value, yet is an inevitable structure in surface mining operations. Since the purpose of mining is to maximise profit, possible expenditure reduction in hauling waste rock to the dump, which can represent up to 50 per cent of the total operating cost, is highly desirable. Apart from cost, potential acid mine drainage (AMD), due to seepage from surface waste rock dumps containing reactive waste rock, could threaten the ecological balance, drinking water supplies and irrigation systems downstream from a mine site. In order to minimise these potential risks, selective placement of benign and reactive waste rock, and the encapsulation of reactive waste rock by benign waste rock, need to be carried out during the construction of the rock dump.In this paper, a new methodology, based on mixed integer programming (MIP) is developed to manage waste rock dumping. The model aims to minimise waste rock haulage costs by locating the optimum destination(s) for each waste rock block, while at the same time controlling the placement of reactive waste rock to minimise the potential for AMD. Tests on small-scale virtual data demonstrated that the model is capable of dealing with selective placement of different waste rock types, encapsulating reactive, potentially acid forming (PAF) waste rock, and stockpiling benign waste rock for encapsulation and rehabilitation purposes. The solution time for the MIP model is far less than the traditional manual approach, and the resulting schedule is up to 46 per cent more cost effective.CITATION:Li, Y, Topal, E and Williams, D J, 2012. Mathematical approach for better mine waste rock dumping management, in Proceedings Life-of-Mine 2012 , pp 207-214 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

Coal slurry pumping was introduced into the U.K. in 1973. Gateside packs were prepared in areas of containment using R.O.M. coal and a special fast setting cement. The packs restricted roadway convergence and moderated spontaneous combustion risks, but costs were high and alternptives were sought. A similar system using OPC and an accelerator had limited success. Much more successful was the Aquapack process which used dilute slurries of a special OPC based cement and an accelerator based on sodium carbonate and bentonite pumped simultaneously into la fabric packbag. The Tekpak system using HAC and a much modified calcium sulphate mixture superceded Aquapack on the grounds of improved cement pumping life lower alkalinity and lower costs. A further modification of this system gave a cement with a 24 hour pumping life thus obviating flushing out pipe ranges except at the week-ends, improved packbags also increased the efficiency of the process. The hazard of spontaneous combustion can be inhibited if air supply channels across the waste can be located and plugged. Using gas samples from pack pipes to locate the heating and injecting a special grout, formulated from bentonite, sodium silicate and thixotroping agents. into the waste on the intake road has proved a successful method of controlling heatings. Mine' roadway and face cavities are being safely and successfully filled with cementitious foams produced in a novel placer machine. The foams are based on fast setting cements with specialised foaming agents. Up to 13 cu. metres per hour of fast setting thixotropic foams can be produced and their use is now widespread throughout U.K. coal mines.

Jan 1, 1986

By Riley S. J

The basic aim of mine planning is to design mine layouts and schedules that achieve optimisation of operations, minimum cost and maximum resource recovery. Successful accomplishment of this aim is facilitated by timely and comprehensive rehabilitation planning commencing at the pre-feasibility stage and continuing until the end of mining. Incorporation of a final landfomt design for waste rock dumps in a mine plan requires a prediction of surface stability, which may be achieved through erosion modelling. Erosion prediction models can be placed in two broad categories: soil loss prediction models eg USLE and CREAMS, and geomorphic models such as SIBERIA. A waste rock dump landform design based on selected slope form and grade and drainage systems should be developed as part of planning. A digital terrain model (DTM) of the landfonn should then be produced which can be modelled for long-term erosional stability using pre-determined parameter values. If acceptable standards of stability are not achieved, the landform should be redesigned and remodelled until the desired result is obtained. The planning process incorporating models requires knowledge of spoil or waste rock properties and model parameter values. This information is site specific and can be obtained from drill cores or costeans at the pre-mining stage and from spoil or waste rock during the mining stage. Realistic model parameter values are critical in post-mining landfonn design and can be obtained by several methods, including rainfall simulation, monitoring, geochemical analyses and grain size analysis.

Jan 1, 1994