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By Peddie F, Low K, Madgwick J, Rajoka M. I, Gutierrez N, Lim C

Percolation irrigation of low-grade quartz feldspar porphyry ore with pH 2.0 H2SO4 at 510 litres/m2/day using particle sizes 1.7 - 6.7 mm in columns measuring 5 cm dia × 126 cm long was used to study effects of interrupted irrigation ('rest' periods) on metal ion release and leaching bacteria. Copper tenors increased approximately 16 fold and bacterial iron oxidation activity three fold following a 14 day 'rest'. A linear relationship between copper tenor and bacterial activity demonstrated that this experimental system was effective for quantitative studies of bacterial leaching in ore colums.

Jan 1, 1981

A laminar-flow furnace technique was used to study the combustion of 37-53 µm size fraction of Woodlawn copper concentrate containing 7.4 per cent zinc, 5.0 per cent lead and 22.5 per cent copper. Factors studied included the effect of time, temperature and the distribution of volatile elements between the panicles and the fume. Air was used for most of the work but a few tests were carried out using 1 per cent oxygen in nitrogen. Chemical analysis, X-ray diffraction, and scanning electron and optical microscopy of polished sections were used to characterize the reaction products.When the concentrate was combusted at low temperatures (800-900°C), the fume was rich in lead. At higher temperatures, this was diluled by increasing amounts of zinc and copper. 70 per cent of the zinc, 60 per cent of the lead and 40 per cent of the copper were found in the fume after oxidation at 1400°C. Lead, zinc and copper were present in the fume as anglesite (PbSO4), zincite (ZnO) and cuprite (Cu2O) respectively. The major phases present in the panicles were magnetite (Fe3O4) and/or cuprospinel (CuFe2O4), with some zincite and cuprite.Elemental copper was found in the particles oxidized in 1 per cent oxygen. Possible vapour species responsible for the vaporization are discussed.

Jan 1, 1985

By S G. Hagemann, M E. Barley

The Mt Tom Price deposit is a world-class high-grade hematite deposit in the Hamersley Province of Western Australia with an original resource of 900 Mt of almost pure hematite, averaging 63.9 wt per cent Fe. Petrological and geochemical studies at both the Southern Ridge and the North deposit at Mt Tom Price have identified three hypogene alteration zones between unmineralised BIF and high-grade iron ore: distal magnetite-siderite-stilpnomelane; intermediate hematite-magnetite-ankerite-talc-chlorite; and proximal martite-microplaty hematite-magnetite-apatite alteration zones.Fluid inclusions trapped in siderite within the distal magnetite-siderite- stilpnomelane alteration zone at the North deposit revealed primary high salinity (25.5 eq wt per cent NaCl-CaCl2) inclusions that homogenised between 107¦ and 142¦C into liquid. Fluid inclusions trapped in ankerite within ankerite-microplaty hematite veins in the intermediate hematite-ankerite-magnetite-talc-chlorite alteration zone at the North deposit revealed mostly H2O-CaCl2 pseudosecondary and secondary inclusions with salinities of 22.4 - 25.4 eq wt per cent and 22.9 - 25.9 eq wt per cent CaCl2, respectively. Pseudosecondary inclusions homogenised between 153¦ and 449¦C and secondary inclusions homogenised between 103¦ and 157¦C. Fluid inclusions trapped in apatite within talc-microplaty hematite veins in the intermediate hematite-magnetite-talc-chlorite-apatite alteration zone at Southern Ridge revealed that primary, medium salinity (7.0 - 9.0 eq wt per cent NaCl) inclusions homogenised between 181¦ and 257¦C and primary high salinity (22.8 - 25.9 eq wt per cent CaCl2) fluid inclusions homogenised between 118¦ and 257¦C into liquid. Microthermometric analysis of quartz from quartz-hematite veins from the Southern Batter Fault, Southern Ridge show a complex fluid inclusion history. Primary fluid inclusions consist of: low- and high-salinity H2O-NaCI inclusions trapped at temperatures of approximately 140¦ to 230¦C; vapour-rich inclusions of unknown compositions; and æcomplexÆ salt-rich (Ca, Mg, K and Na inclusions).Secondary inclusions consist of medium-salinity fluid inclusions trapped at temperatures of about 140¦ to 280¦C.A two-stage hydrothermal model is proposed for the formation of both the Southern Ridge and North deposits. Early 1a hypogene alteration involved the release of hydrothermal NaCl-CaCl2-rich (25.5 eq wt per cent) basinal brines (110¦ - 150¦C) from the underlying Wittenoom Formation and directed upward along normal faults and focused within the silica-rich rocks of the Dales Gorge Member, by the shales of the underlying Mt McRae Shale Member and overlying Whaleback Formation. Within the Dales Gorge Member hydrothermal basinal brines migrated laterally within large-scale folds with permeability controlled by shale bands and the NW trending dolerite dyke sets. Fluid rock reactions transformed unmineralised BIF to magnetite-siderite-iron silicate BIF, with subsequent desilification of the chert bands. Stage 1b hypogene involved an increase in temperature of the hydrothermal, CaCl2-rich saline (24 eq wt per cent) basinal brines (250¦ - 300¦C) resulting in formation of hematite-ankerite-magnetite-talc-chlorite alteration and the crystallisation of microplaty hematite. Late stage 1c hypogene alteration involved the interaction of low-temperature (~120¦C) basinal brines with the hematite-ankerite-magnetite mineral assemblage. At the Southern Ridge deposit this process was very intense (ie high fluid flux), therefore resulting in the almost total removal of ankerite and resulting in the increased porosity of the ore. Stage 2 supergene enrichment in the Tertiary resulted in the removal of residual ankerite and apatite and the weathering of the shale bands to clay.

Jan 1, 2005

By C Philander

The West Coast of South Africa is well known for its placer gem quality diamond deposits and also associated with these hosts of Cenozoic unconsolidated marine and aeolian sand and gravel are significant concentrations of heavy minerals. Exploration for economic concentrations of zircon, ilmenite and rutile along the coast started in the mid-1980s. This resulted in the discovery of an inferred 1.6 billion tonne resource with a grade of ten per cent total heavy minerals (THM), which developed into the Namakwa Sands Mine, a world-class producer of heavy minerals. Several other resources, including satellite deposits proximal and distal to the mine area, extensive diamond mine dumps and present day beach placers, demonstrate the vast heavy mineral potential along the West Coast. The favourable gangue to economic mineral ratio, a higher zircon content compared to other similar deposits, relatively lower U+TH content of zircon, low slimes content and effectively pristine low chromium-manganese ilmenite of these deposits, render them attractive exploration targets. Negative factors that will affect conventional mineral beneficiation and liberation include secondary mineral coatings and the regional coastal development of several layers of superimposed duricrust. The economically attractive heavy mineral assemblage along the West Coast is the result of erosion of the proximal, gneissic Namaqualand Metamorphic Province and mature Table Mountain Group sandstone, concentration by marine and aeolian processes and preservation under arid climatological conditions over a period of more than 100 Ma.

Jan 1, 2008

By Alexander RB, Hollis AJ

The magnitude of the payloads carried by mine haul trucks can have a strong influence on the mine production rates and costs. Consequently control of truck payloads is highly desirable, but in many mines the unavailability of means for measuring payloads reliably, accurately and easily has resulted in a low level of control over truck payloads. Consideration is given to two techniques which are applicable to the measurement of payloads carried by mine haul trucks, namely truck weighing and direct measurement of payloads with truck based systems. Accuracy assessments for two types of truck weighing platforms and two prototype truck based direct payload measurement systems are provided. Results show that weighing platforms based on hydraulic components have proved inadequate, while strain gauge type weighing platforms can estimate payloads to within 2% of true payload when installed, maintained and used correctly. The assessment of the two prototype truck based direct payload measurement systems shows that a high proportion of payloads were estimated to within 5% of the payloads derived from accurate weighing platforms and that these systems appear to have the potential to provide convenient and accurate measurement of payloads. This should enable payloads to be much better controlled than has been possible to date. Predictions of the effect of payloads on production rates and some components of truck haulage costs are possible and some typical results are presented. Accurate prediction of the effect of payloads are not yet possible for some major components of truck haulage costs.

Jan 1, 1986

By A Cheatle

GoldcorpÆs Musselwhite mine in north-western Ontario, Canada has in recent years become a world-class deposit. Initially discovered in the early 1960s by Alan and Harold Musselwhite, the then marginal mine eventually started production in 1997 and has to date produced 2.6 Moz of gold. Two million ounces of gold are currently classified as Mineral Reserve and a further 1.2 Moz of gold are classified in the Mineral Resource category for a total gold inventory approaching 6 Moz. Growth of the mineral inventory has been achieved through the successful implementation of strategic planning that sought to extend the mine life through discovery of additional economic zones and increased mined tonnages. Accelerated exploration activity commenced in 2001, at a time when gold price was at its lowest in decades. Focus was placed on building, developing and retaining a highly skilled geological team, maintaining purpose, conducting external reviews and developing a new geological model through research partnerships. Ongoing collaborative research between Lakehead University and Musselwhite mine has seen the development of new structural and geological models through post-graduate and academic studies. Research has included lithogeochemical, stable isotope and structural and metamorphic studies and has led to the evolution of a new mineralisation model (for the mine) and the recognition of brittle and ductile deformation regimes within the mineralised horizons. Exploration drilling continues to provide support for the new geologic model. Gold discoveries have extended known mineralisation 2.3 km along strike from mineral reserves and laterally into parallel zones. The exploration potential to further increase production rates, Mineral Reserves and Resources remains very positive and increases in overall gold inventory are likely. Musselwhite mine has significantly exceeded initial projections for a ten year life-of-mine and a marginal existence.

Jan 1, 2009

By M I. Pownceby, N A. S Webster, J R. Manuel, J M. F Clout, E Donskoi, N A. Ware

The relative influences of sinter mineralogy, sintering temperature, solid and pore macro- and microstructure on iron ore sinter physical strength are not yet fully understood. Whilst a range of analysis techniques have been used by researchers to evaluate sinter physical properties and sinter mineralogy, none have been able to directly link sinter mineralogy and physical strength under controlled conditions. CSIRO has developed a unique laboratory method to study the fundamental melting properties of fine iron ores in a laboratory furnace under a controlled temperature and gas atmosphere environment designed to simulate the industrial sintering process. Compacted tablet samples for a 0.41 per cent and a 2.5 per cent Al2O3 series were fired in a tube furnace at various temperatures, cooled, then tumbled using a modified Bond abrasion test apparatus to determine a relative tumble index (TI) at each temperature. Quantitative XRD (QXRD) analysis was then carried out on the tumbled samples and optical image analysis (OIA) was conducted on polished sections of a separately fired compact in each case. The amount of total SFCA was found to decrease with increasing firing temperature for both alumina series with the total amount of SFCA higher in the 2.5 per cent Al2O3 series compared to 0.41 per cent Al2O3 series samples. The increase in the amount of magnetite and hematite with increasing firing temperature was largely at the expense of a decrease in total SFCA. Overall, there was good agreement between the quantitative mineralogy determined from QXRD versus OIA for SFCA, hematite and magnetite. Qualitative analysis of high magnification images of the sinter correlated with both the OIA and QXRD results.

Sep 18, 2023

Madison Enterprises Corp. and Matu Mining are currently ex- ploring the Mt. Kare property in Papua New Guinea. The Mt. Kare gold prospect has had a short but very active history, since the first discovery of gold in the area in 1986 the property has sccn: a 3 year gold rush during which 10,000 alluvial miners re

Jan 1, 1997

The T33-34 blast, the first major blast at Mount Isa Mines, broke 1,360,000 tonnes of copper ore using 349 tonnes of explosives. The original concept of firing T33, T34, T35 and U37 separately was changed during the life of the project due to adverse ground conditions. These conditions also caused the stoping method to be modified after the firing of the stopes had started. To stabilise the two stopes T33 and T34 where large fall off was occurring, rib pillars were left in the original slot. This caused the blast design to be more complex as these rib pillars had to "lead" the blast. The implication of such a large blast on the underground and surface environment was thoroughly investigated and precautions taken. The charging time of the blast was six weeks. Hook-up was started four days before the blast and continued until two hours prior to the blast. Detailed scheduling was carried out of other work that had to be done in the 24 hours before the blast to ensure that there were no delays in the firing.

Jan 1, 1977

By M F. Navarrete

During 2003, different plastic stemming plugs (Cats«, Stemtite«, and Taponex«) were tested in EscondidaÆs Mina Sur, to determine the effect on gas retention time when used in conjunction with drill cuttings in production shots with a blasthole diameter of 10 5/8ö. Longer retention times were expected to provide greater fragmentation and muckpile looseness. In order to determine which plug showed the greatest enhancement of stemming retention, 17 trials were carried out û in the first seven tests, only the Cats were used, in the following five tests, a combination of Cats, Taponex and Stemtite were used, and in the last three tests, only the Taponex plug was used. In the last two blasts, drill cuttings were used without stemming plugs as a benchmarking exercise. Blasts were filmed with a high-speed camera, which could record the detonation times of holes using rolls of shock tube tied to stakes at the hole collars, to act as flash indicators. The camera allowed measurement of the time between charge detonation and the commencement of stemming ejection. In order to obtain the statistical parameters of each one of the stemming plugs used in the 17 trials carried out, the Minitab software was used and a data base was created for it, corresponding to each stemming configuration with the retention time obtained from the filming. Once it was determined which stemming plug provided the greatest enhancement of stemming retention, the impact on the fragmentation was analysed using the WipFrag image analysis software to estimate the muckpile size distribution.

Jan 1, 2004

By D P. Telionis, P P. Vlachos, R-H Yoon

Industrial processes involving multi-phase flows such as flotation require understanding of the relationships between bubbles, solid particles and the flow. Modern experimental tools are employed in this effort to measure with great accuracy the basic features of the motion of all three phases in turbulent flow. We employed a unique digital particle image velocimeter (DPIV) that can record with great accuracy and kHz temporal resolution, velocity vectors of all three phases, namely the fluid, the solid particles and the air bubbles. The interaction of these three phases was studied in homogeneous isotropic turbulence generated by cylindrical grids. Particles and bubbles were released into the turbulence and the motions of the three phases were monitored. The experimental results obtained in the present work were compared with the predictions of the models published in the literature.

Jan 1, 2005

By Weining L

In-situ experiments were performed in a tunnel built in loess soil with the displace- ment components of the tunnel lining and the acceleration components of the tracks measured during the passing of trains. The measured parameters were then studied by the spectral method. As a result, the dynamic forces of trains was simulated numerically and a deter- ministic dynamic nonlinear analysis was carried out by means of finite element method. The results obtained by two different approaches were in fair coincidence. Results of the study indicate, that the low and medium frequency components of the dynamic train loading would be crucial for the dynamic responses of the tunnel lining and surrounding mass, and their effects would increase with the speed of passing trains within a certain range.

Jan 1, 1987

Early efforts to control the dust necessarily produced during dry crushing operations, took the form of venturis at loading chutes and other places where dust was most evident. These venturis discharged to the atmosphere and for obvious reasons were not very satisfactory.Attempts to collect the dust drawn off by the venturis, using dry cyclones, were not successful, the cyclones catching only the coarser particles. Further, no satisfactory method of continuously discharging the dust catchment was evolved. Water sprays were also used, and will be referred to later.In 1940, a single discharge fan of 3,000-4,000 cu. ft. per minute capacity, was installed to draw the dust-laden air from the Symons crushers and ·screening sections with their attendant conveyors. Suction was through two 15 in. ducts which branched off into 10 off-takes situated over the conveyers at points of discharge from crushers and screens.A dry cyclone was installed in front of the fan, which exhausted into a bag-house.The cyclone suffered from the defects of the smaller units mentioned earlier. When the collected dust reached a certain level in the cone, no more collection would take place until the cone was emptied. This objectionable feature was overcome by introducing a jet of water ahead of the cyclone. The water and dust collected overflowed a weir and were pumped to the mill.

Jan 1, 1948

By Miyatani J. Asaki Z, Kondo Y

The oxidation of sphalerite particles of 60 to 100 mesh size was studied in a fluidized bed of low 02 concentration at 900¦C. Par- tial pressure of 02 in the fluidizing 02-N2 gas mixture was chosen between 0.0009 and 0.02 atm. In the region of p02 between 0.008 and 0.02 atm, the oxidation rate was lowered with the decrease of p02, and the unreacted-core model was applied. At lower pbelow 0.008 atm, the reaction rate was enhanced as compared with the calcu- lated values from the unreacted-core model. From microscopic examination, it was found that ZnS was evaporated at the particle surface and the dissociated Zn vapor was oxidized in the gas phase. Initial reaction rate and the distance between the surface of inner sphaler- ite core and the oxide shell were studied based on the model of enhanced oxidation.

Jan 1, 1980

By J Szymanski, S Planeta

Extensive rockfill cylinder testing was performed to determine the effect that aggregate size, aggregate moisture, Portland cement, fly ash and cement dispersant addition has on compressive strength of a cemented backfill. In this paper ætwo-level factorialÆ and æcentral compositeÆ designs were used to determine the single and interaction effects that each factor have on the overall strength. The results from the designwork indicated that the per cent of aggregate fines had the greatest influence on the compressive strength of the rockfill cylinders. From the factorial design results, a compressive strength estimation equation was derived, which enables the strength to be estimated, given varying input values.

Jan 1, 1998

By Eddy B. W, Washusen J. A, Wulff R. T

The State Electricity Commission of Victoria (SECV) has been con- tinuously involved in the extraction of brown coal from open cut mines in Victoria's Latrobe Valley for over 60 years, but have not completed a major mine. Detailed consideration for rehabilitation at this stage has only been able to be given to overburden disposal areas. Increasing interest in rehabilitation in the 1980's led the SECV to review its existing policies and practices and to embark in 1985 on a public consultation process to establish an agreed and accepted policy. This was extended in 1986 to the consultation process for the rehabilitation planning for the Mor- well Open Cut External Overburden Dump. This paper covers the con- sultative process developed and the lessons learned by the participants.

Jan 1, 1989

By Segnit R. E

Two suites of dusts (waste-heat boiler and electrostatic precipitator) collected in 1976 and 1980 from the Kalgoorlie nickel smelter were subjected to chemical and XRD analysis and were examined by SEM and optical microscopy. The spherical to sub-spherical particles contained oxide and glassy phases with small amounts of sulfide. XRD showed that the major phase was a mixed Ni-Fe oxide spinel with some hematite. These phases compared well with those predicted by thermodynamics. The particle size distributions showed that in the 1976 and 1980 suites 20 per cent by weight was respectively coarser than 60 and 115/lm (boiler dusts) and 40 and 30/lm (precipitator dusts). Maximum particle sizes estimated from sedimentation chamber theory were found to be in reasonable agreement with the maximum sizes found in the dusts.

Jan 1, 1984

Study on Influence that Styrene-Phosphoric has on the Surface Property of Rutile Minerals

Sep 13, 2010

By Walsh V

The Australian economy has been adversely affected by the hesitation in developing countries to commit to the construction of .new coal-fired power stations. World coal trade which was expected to grow at an appreciable rate has stagnated, world export coal prices have plummetted, and facilities in place in Australia for the production and export of coal are being underutilized. While in some countries this hesitation has been caused by a reduction in electricity load growth, another cause has been the unduly long lead-time imposed on developing countries by the conventional "Banker's Approach" to the planning and initiation of commitments to finance and construct coal-fired power plants. In some countries electricity growth has been met by increased usage of indigenous energy resources, even though this involves costs in excess of imported coal-fired power generation. The avoidance of foreign exchange commitments in these cases can however be desirable. In many other developing countries however, fuel oil continues to be used for power generation at a cost in foreign exchange of up to 50% above the total cost of coal fuel plus capital to construct a new coal-fired power station. The conventional "Bankers Approach" to new power station planning imposes the need for successive feasibility studies to satisfy the normal processes of international development lending agencies. No feasibility study can however, show how keen vendor countries may be to win major power plant contracts; and no feasibility study can determine whether the power station eventually procured will be one of the more reliable, at better than 80% availability, or one of the more unreliable at worse than 60% Availability.

Jan 1, 1987

Australian continental crust has accreted and consolidated by thirds: 1/3 during Archean time, 1/3 during Early to mid-Proterozoic time, and 1/3 during latest Precambrian to mostly Paleozoic time. The progression of orogenic systems and the crustal consolidations they represent seem not fundamentally different in basic orogenic processes from better known Mesozoic-Cenozoic examples in that accretionary, continental margin, collisional, and intraplate intracratonic inverted and/or reactivated systems are all recognizable in the tectonic evolution ofAustralia.

Jan 1, 1995