Search Documents

By M Noppe, I Glacken

There are many critical nodes along the mine value chain, from orebody to mineral product, and inter-disciplinary input is required to analyse the variability and uncertainty at each node in order to identify and mitigate areas of risk. Mining differs from many other industries in that the variability in the product is dictated largely by the inherent nature of the input material (the orebody). The true characteristics, including the variability of the orebody, are never known exactly and are instead based on estimates derived from sample data. A further difference is that bottom-line gains are largely controlled by world commodity prices, which can vary with time, rather than by local supply and demand issues. Methods for identifying, reporting and responding to this inherently variable raw material are discussed. These include analytical and reporting methods, equipment and software, risk analysis and reality checks (eg reconciliation). Sampling results, mineral resource and ore reserve estimates and economic assumptions are a function of the variability of the orebody. Risk quantification should be expressed as a level of confidence, which takes into account the scale or period over which the risk is being assessed (life-of-mine, annual or shorter production periods) and should convey the likelihood, severity and consequence of occurrence of a given event. The future generation of mining specialists needs to understand the entire mine value chain to better manage risks and maximise mine dollar-value.

Jan 1, 2002

Prior to 1980 the thought of the occurrence of high-level epithermal gold mineralisation occurring in eastern Queensland would have been more of a dream than a reality. In a world-wide sense the understanding of the processes and tectonic settings for epithermal gold were only beginning to be developed. Although epithermal gold deposits had been mined in the past in Queensland the significance of these deposits in a regional sense had not been appreciated. A number of companies had made cursory examinations of epithermal regions in the Mt Coolon and Cracow regions. Since the mid 1980's the search for epithermal gold mineralization in Queensland was truly on and over 30 tonnes of gold from this style of deposit has been discovered.

Jan 1, 1989

By K E. Barns, P J. Sharman, S A. Thomas and

This paper presents the development of a regrind facility design at BHP BillitonÆs Leinster Nickel Operations (LNO) in Western Australia. The recovery opportunity was identified from an analysis of plant operating data together with scanning electron microscope (SEM) measurements on relevant tailings streams from LNO. A laboratory procedure was developed to determine the potential recovery improvement of installing a regrind facility at LNO. The last step in formulating the process flow sheet and defining the process design criteria was to construct and operate a pilot plant, which incorporated four banks of flotation cells and an Xstrata M20 Isa Mill. Pilot plant on/off trials were used to define the expected metallurgical benefit. A prefeasibility engineering design and cost estimate was completed. Following a successful internal business evaluation, a feasibility study is currently underway.

Jan 1, 2007

A Study on Process Mineralogy and Mineral Processing of Complex Carbon-Bearing Cu-Pb-Co-Ni Multi-Metal Sulfide Ore by Bulk Flotation

Sep 13, 2010

Radioisotope X-ray and neutron techniques of analysis can be used for the determination of a wide range of elements in minerals. The most important applications of these techniques to the mineral industry are for on-stream analysis of slurries and solids, and for geological assay. The radioisotope X-ray techniques are the more developed ones and two installations for on-stream analysis are in routine use in mineral processing plants in Australia. Neutron techniques are being developed, and should prove valuable for geological assay of large numbers of mineral samples, for borehole logging, and for specific on-stream analysis when the cost of the equipment is warranted.

Jan 1, 1969

Gallium occurs at above background levels in most samples collected from 11 of the major geothermal areas in the Taupo Volcanic Zone. Concentrations of Ga in the 48 samples ranged from 8 to 144 mg kg-1 and varies widely from place to place within each geothermal area. Gallium is contained within the alumino-silicate structure of clay in the mud, having substituted mainly for Al. Suggested deposition mechanisms for Ga also involve co-precipitation with Sb, As, and SiO2 colloids. Digestion trials, carried out to determine extraction conditions for possible commercial exploitation, showed that heating the mud to 500 - 600¦C for 1 hour followed by acid/alkali treatment gave complete recoveries.

Jan 1, 1995

Aspects of the formation, decomposition and acid solubility of zinc ferrite were examined to find potential ways of increasing the recovery of zinc from a calcination process of mineral concentrates. Ferrite can begin to form within 2 hours at 450¦C. while complete reaction can occur after 35 minutes at 700¦C. The nature of the starting materials has a pronounced effect on the rate of formation and below 700¦C. ZnSO4 and Fe2O3 proved to be the least reactive of the materials investigated. It is possible that iron in a mineral admixed h sphalerite can be converted to a relatively inactive form, however, it does not seem possible to prevent zince f formation when iron is in the sphalerite lattice. At the two temperatures examined, 650¦C. and 700¦C, the presence of SO2 in the atmosphere accelerate .e formation of ferrite. Prolonged exposure to such atmospheres, however, caused the ferrite to decompose to ZnSO4 and Fe203. The optimum temperature for decomposition was 650¦C. and it was virtually complete within 2 hours in an atmosphere of 10% SO2 in air. Zinc ferrite was also decomposed by CO at low concentrations, and by heating with limestone at 1000¦C. for at least 2 hours. The solubility of zinc ferrite in acid was influenced by the starting materials used. As both the reaction temperature and the time at temperature increased the acid solubility decreased. The acid solubility was a minimum when the ___i_.. n - I -r~...................c -..... F, fe..i+e --A frn... A01- +^ Z(lo/

Jan 1, 1970

By McKee DJ

Future mineral processing developments will be of two types. There will be a continuation of the advances of the last 20 years including major increases in equipment capacities, the development of reliable on-line instrumenta- tion, the use of digital computers for automatic control, and the greatly expanded use of in-situ leaching techniques. However, there will also be a need for innovations as the industry faces a different set of problems to those involved in cost and extraction efficiency considerations. These new problems include those relating to energy usage, environmental pressures, and the further development of large low grade deposits and small, high grade metallurgic- ally complex deposits. Present technology does not appear adequate to solve many of these new demands. New treat- ment concepts will be required, and the immediate outlook in this regard is not encouraging. A major research and development task in mineral processing over the next 20 years will be to seek out new ideas and develop them, and this must be pursued with imagination and determination. Both the continuation of the present research pro- grammes and the development of new methods will require a steady supply of highly qualified technical personnel. These people are not being produced in the numbers required, and this situation must be urgently rectified.

Jan 1, 1981

By Chen J, Zhu D

A detailed study on oil agglomeration of fine metal oxide particles is presented in this paper. The major content embraces several aspects which may possibly reflect the current trends in oil agglomeration such as the effect of chemical and physical parameters, the activation of target minerals and the deactivation of gangue particles, the mechanisim of bridging liquid and the kinetics of oil agglomeration process. Systems of ilmenite-feldspar, manganese dioxide - quartz were seperated successfully through oil agglomeration followed by decantation or flotation technique respectively. A triple mixture of vandium-bearing titanomagnetite ilmenite and feldspar was processed satisfactorily using a composite technology: oil agglomeration-decantation-magnetic concentration.

Jan 1, 1993

By Komosa T

The increase in the proportion of sulphide ore treated by the gold mining industry has led to generally higher oxygen requirements. Additions of pure oxygen, hydrogen peroxide and in some cases calcium peroxide, have been proposed as a means of satisfying the oxygen demand and overcoming the problems from reactive sulphides in the ore. Current oxidant addition options and practice are reviewed.Laboratory oxygen demand tests are reported for a suite of ores to show some of the effects of pH and preaeration.Laboratory leach tests at high and low dissolved oxygen levels are reported on two of the ores with higher oxygen demands, and the results are assessed in terms of gold leaching kinetics, ultimate gold extraction, and cyanide requirements.

Jan 1, 1992

By Singer RP

The Latrobe Valley brown coal deposits are one of Australia's major energy resources with measured and indicated reserves amounting to some 162 billion tonnes. Economically recoverable reserves are estimated at some 65 billion tonnes, 47 billion tonnes of which are classified as available for mining (VBCC (1983)). These deposits contain one of the lowest grade fuels used anywhere in the world. Typical Net Wet Specific Energy values range from 6 to 9 MJ/kg. Despite the low energy value of the raw coal, the Latrobe Valley deposits represent approximately 90% of Victoria's indigenous non-renewable energy resources. Utilisation of this vast primary energy resource has been a key factor in the economic development of Victoria.

Jan 1, 1990

By M Thomas, S Lambert

The Tugun Bypass Tunnel in Gold Coast, Australia was constructed using diaphragm walls with the top-down cut-and-cover method to allow simultaneous construction of an airport runway extension above the tunnel, whilst excavation of the tunnel continued underneath. The tunnel was built in an environment of high groundwater table and deep deposits of alluvial and estuarine soils with the toes of the walls founded in soil deposits. There was a potential risk for differential settlements to occur between the diaphragm wall panels, caused by the runway fill placed over the tunnel roof during excavation. Dewatering within the diaphragm walls was required to facilitate the construction of the tunnel. The tunnel was also built in an area where environmental considerations were of great importance. Three-dimensional numerical modelling was undertaken to predict the differential settlements of the tunnel with considerations of varying subsurface profile, staged excavation and dewatering, non- uniform surface loading and complex soil-structure interaction. Field instrumentation and monitoring was implemented to confirm numerical predictions.  

Jan 1, 2008

By M B. McKevitt, W J. Shaw

The main task of grade control on a daily basis is to define the material that should be mined to a destination under various categories. This can be determined by grade, lithology, quality and blending criteria. In the case of multi-element deposits or deposits with various blending or other processing criteria the optimum selection of ore block boundaries can be quite complex. In every case the balance between ore loss and dilution must be considered when designing the ore block boundaries and this becomes a risk-based decision when using the conditional simulation model. The use of such systems allows grade control to meet specific targets, such as budget tonnages and grades and blended product specifications. Two case studies are presented: the Prominent Hill copper/gold mine and the Rapu Rapu zinc/copper mine. Mining is based on a rational grade control strategy involving a number of factors, including strong geological control, advanced geostatistical approaches, such as conditional simulation, and optimisation of the ore blocking to meet production requirements. This provides an objective, transparent and repeatable grade control strategy.

Jan 1, 2009

The factors affecting performance of base and precious metal smelting and converting processes are considered in relation to reactor characteristics. The chemical differences between processes are related to these factors for different reactor systems. The complete smelting and converting flowsheet involves a number of operations. The process selected for a particular feed and product requirement should be one which optimises the efficiency of the process, the cost of building and operating the technology and the long-term maintenance and productivity of the units.Ausmelt's approach to achieving an efficient process using its technology is described in relation to the smelting of copper concentrates for production-of blister copper.

Jan 1, 1992

By R McConnochie, J V. Rowland, J L. Mauk

The Sovereign prospect in the lower Waitekauri Valley of the southern Hauraki Goldfield occurs in daciterhyolite flows and volcanic breccias of the Waipupu Formation. The lower Waitekauri Valley contains a series of NE to NNE-trending normal faults, and the Sovereign prospect lies in a NW-striking graben. The structure of the Sovereign prospect is complex. NE to NNE-trending veins and normal faults dominate the area, however WWNW and N to S-trending structures occur locally. Kinematic analysis of these structures indicates predominantly dip-slip movement, with a local strike-slip component. At least two sets of veins occur in the area: 1.        steeply dipping veins; and 2.       low angle veins, which cross-cut and locally offset the steeper dipping        vein set. Mineralization appears to have formed during normal faulting in an extensional regime.

Jan 1, 2007

By K-S Kim, C-Y Kim, D-G Kim

In tunnel construction or other underground construction, a detailed knowledge of the rock mass ahead of the face is essential for both safety and efficiency of work. Many tunnel collapses have been reported to occur because of lack of appropriate information, such as the geological conditions ahead of the tunnel face. One of the methods which can identify rock mass conditions is the application of drill monitoring data obtained from blasting drill holes, which can detect abrupt and unexpected changes in ground conditions, geological structure and the mechanical and physical properties of rock mass. This paper presents a new approach to how drill performance parameters can be used for prediction of geological conditions ahead of tunnel face. The predictions are based on monitoring the drill parameters of instantaneous advance speed, torque and tool pressure. In order to assess conditions ahead of tunnel face, tunnel seismic profiling (TSP) and a horizontal boring investigation were undertaken and the obtained data compared to the drilling data. The predicted results using drilling performance parameters correlated well with geological conditions ahead of tunnel face.

Jan 1, 2008

By Reichman J, Chapman G

The features of seam gas drainage from the point of view of mathematical modelling are outlined and discussed: 1. The use of conventional single phase gas reservoir simulator for very simplified modelling. 2 Alteration of a conventional petroleum reservoir simulator into a specialised simulator for seam gas drainage. 3. Application. of a conventional petroleum reservoir simulator for modelling of seam gas drainage by the way of pseudo-functions and sacrifying one dimension.

Jan 1, 1982

By Amelunxen R, Finch JA

Flotation columns represent an important addition to flotation practice. Columns have largely replaced. conventional machines in molybdenum cleaning in Canada. Columns have been successfully tested on bulk copper/molybdenum cleaning at Gibraltar Mines Ltd. A rougher cleaner/scavenger cleanercombination was shown to be capable of giving higher grades and recoveries compared with three stages of conventional cleaning. A control strategy for the columns has been developed. An interaction between gas hgldup and wash water rate has been exploited to control performance.

Jan 1, 1985

Violarite, (Ni,Fe) 3+x S4, is a ubiquitous secondary mineral in the supergene alteration zones of massive nickel sulphide deposits in Western Australia. It is formed by the pseudo- morphous replacement of pentlandite, pyrrhotite and/or millerite, and retains the textures typical of these precursors. Although the composition of the first-formed violarite is related to that of its precursor, supergene enrichment results in an increasing nickel:iron ratio toward the top of the supergene profile. In pentlandite-pyrrhotite ore, the replacement of pentlandite by violarite releases some nickel, which is consumed by the partial conversion of the pyrrhotite to iron-rich violarite. In pentlandite-millerite ore, on the other hand, the pentlandite, on conversion to violarite, appears to release excess iron that participates in the partial conversion of millerite to nickel- rich violarite. The characteristic textures exhibited by the secondary violarite and its replacement products in supergene and gossanitic deposits overlying massive nickel sulphide ores generally enable the original mineralogical compositions of the primary ores to be inferred.

Jan 1, 1973

A portable surface impedance meter has been tested extensively over a wide variety of geological formations both in Australia and elsewhere. It has proved a useful geophysical too] for relatively shallow mapping (i.e less than 100 metres depth) of faults, intrusions, dykes and conductive ore veins and can be used as a depth probe for overburden and glacial ice. Case studies involving coal seam mapping at Collide (Qld. Australia), galena ore vein location at Zeehan (Tas. Australia) and glacial ice probing on the Brewster Glacier (South Island, New Zealand) are detailed. The first results of a similar unit using a lower frequency with consequential increase in depth of penetration will be presented. The application of VLF measurements to monitor blasting in mines and in the location of earthquake epicentres will also he introduced.

Jan 1, 1987