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Magmatism and mineralization are features of the New England Orogen in late Palaeozoic- Mesozoic time. Voluminous silicic and mafic magmatism, both orogenic and post-orogenic in association, was accompanied by abundant mineralization in the earlier phases. Later activity passed transitionally into less vol- uminous felsic to mafic intraplate basaltic volcanism, with possible migratory hot spot activity through the flanking Oxley and Sydney Basins. Only minor mineralization took place at this stage. A new inerpretation links these magmatic and mineralizing events to a major thermal cycle. A New England hot spot(?) complex evolved in latest Carboniferous/early Permian time. Its activity was partly obscured by orogenic magmatism as Australia moved slowly over magma sources in the deep lithosphere. In Triassic time Australia's movement changed direction and faster drift over the waning hot spot complex produced multiple migratory intraplateòactivity. The volume of magma and hence abundance of ancillary mineralization was related to age of the hot spot, speed of the continental movement over thermal sources and extent of accompanying orogenic activity. The New Eng- land Orogen hot spot(?) possibly existed for 165 Ma, with mineralization changing over this Period.

Jan 1, 1987

By D Henderson, K Howie

In 2005, Glass Earth Limited (GEL) commissioned two large area detailed airborne geophysical programmes in the Taupo Volcanic Zone (TVZ). In the first survey Bell Geospace Ltd of Scotland conducted an Air-FTG« (airborne Full Tensor Gravity Gradiometry) survey covering 2338km2 at 300m line spacing. The second survey by UTS Geophysics, Australia included detailed airborne magnetic, radiometric and digital terrain data capture covering 5341km2 at 150m line spacing.   From the detailed geophysical data collected it is possible to identify major deeply penetrative crustal structures within the TVZ, as well as define subsurface geological features, such as intrusive bodies and alteration zones. These major deep crustal structures are thought to have a controlling influence on the distribution of epithermal gold mineralising systems, and along the corridors defined by these deep crustal zones, the chances of discovery of an economic epithermal gold discovery are greatly increased.   In this paper GEL gives some examples of the application of its integrated data driven approach to exploration in the TVZ at both regional and project scale. The paper focuses on how GEL identifies regional scale highly prospective deep crustal structures. Then, using the Horohoro epithermal gold system as an example, we show how GEL applies innovative geological and geophysical data processing to model and understand detailed subsurface geology, focusing subsequent exploration to ensure the best opportunity for a new economic epithermal gold discovery.

Jan 1, 2007

By Egan J. R

Changes have recently been applied to the Sullivan Concentrator lead and zinc circuits to treat fine-grained ores which make-up the majority of ore reserves in the mine. Pilot plant testwork conducted in 1990 - 91 indicated that concentrate grades would be substantially improved by reducing the particle size (Pao) of the lead from 38 to 15 ¦m and the zinc from 45 to 24 ¦m. Circuit revisions involved installation of major new equipment including: two 600-kilowatt Vertimills for regrinding, a four metre diametre column flotation cell and a four metre diameter hyperbaric pressure filter for dewatering. Duties of the existing regrind mills were Reassigned.

Jan 1, 1993

Rare-earth permanent magnetic roll separators, pioneered by our group a few years ago, have distinctly different operation characteristics compared to prior art electromagnetic separators of various types. Many new applications for dry high-intensity (or better: high-force) magnetic separation have been developed in a short time period. It has also been found that the new generation of separators generally are more efficient with regards to removal of weakly magnetic contaminants in glass and ceramic raw materials with minimum loss of valuable product compared to induced magnetic roll (IMR) separators.The latest development is in the area of production of clean magnetic concentrates at high recoveries. It is likely that the PERMROLLR magnetic separator will replace cross-belt and lift-type magnetic separators as a result of this most recent advance.The paper will review the features of the PERMROLLR magnetic separator in comparison with other types of magnetic separators on the market and give examples on applications.

Jan 1, 1990

By M Spleit

A long-term production schedule for the LabMag iron ore deposit in northern Quebec, Canada is derived using stochastic integer programming. The optimisation formulation maximises the schedule’s net present value while simultaneously managing the risk of deviations in production tonnages and qualities by considering stochastic simulations of the orebody instead of a single deterministic model. The formulation also smooths and minimises haul truck requirements and ensures that as mining progresses, space is created within the mined out pit for the return of waste material.CITATION:Spleit, M, 2014. Production schedule optimisation – meeting targets by hedging against geological risk while addressing environmental and equipment concerns, in Proceedings Orebody Modelling and Strategic Mine Planning Symposium 2014, pp 397–404 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 24, 2014

By P Myers, T Elkington, S Wonday

Sierra Rutile LimitedÆs (SRL) heavy mineral sand mining operation in Sierra Leone, West Africa, is embarking on a new phase of its life. After confronting many challenges during the 1990s and 2000s, SRL is embarking on a strategy of growth to recover maximum value from the mine over the rest of its life. Sophisticated linear programming techniques have been used to develop an optimum strategy for extracting SRLÆs many known deposits of economic grade, while considering options for expansion and for a variety of mining and processing methods and combinations. CITATION:Myers, P, Elkington, T and Wonday, S, 2012. Strategic optimisation at Sierra Rutile - A case study in maximising project value, in Proceedings Project Evaluation 2012 , pp 59-66 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 24, 2012

The Bradford Process, Australian Patent No. 11253, has had considerable application in the treatment plants of Broken Hill mining companies, and is at present being used by the North Broken Hill Limited for the treatment of weathered slime accumulations.The "Mining and Scientific Press," of 28th September, 1918, describes the Bradford Process at Broken Hill, specially featuring its application to slime material at the Proprietary mine-the home of the process.The points then stressed for galena flotation were acidulated slime pulp (0.025 to 0.030% H2S04) at temperature 85° to 90° F. and suitable time contact, with 1.5 to 2 lb. of sodium hyposulphite (per ton on slime) to permit the released S02 to "wet" or depressthe blende mineral. Also 1.0 to 1.3 lb. of crude sulphur (per ton on slime) was burnt, to supply S02 for keeping the lead concentrate clean during flotation. Pulp density varied from 23 to 26% solids. Since 1918 the process has been simplified in its application.Acidity of circuit, temperature, and sodium hyposulphite have been dispensed with, and now the S02 is practically all obtained by burning crude sulphur. I The plant units now employed for control and absorption of S02 gas constitute the main advance made in process, and these, with other details, are fully explained in this paper.APPLICATION AT BROKEN HILL NORTHThe existing North Broken Hill Limited gravity mill commenced operations on 9th September, 1909.

Jan 1, 1929

The weathering profile, in arid terrains, is commonly capped by different kinds of hardened crust, whose formation is related to recent or former climates. One may distinguish silcretes, calcretes and the ferruginous (or ferro-aluminous) laterites. the present keynote address mostly deals with the lateritic regolith and, moreover, the influence it has on mineral exploration. The lateritic regolith, also called "cuirasse", is a result of a massive accumulation of Fe (and/or Al) oxides on top of weathering profiles developed during former, probably seasonal humid, climatic episodes, and whose preservation depends on the characteristics of later climates. The total thickness of such weathering profiles commonly exceeds 50 m, with an almost complete substitution of the rock forming minerals by secondary minerals as kaolinite and Fe-Al oxi- hydroxides (hematite, goethite, boehmite, gibbsite). Such an alteration of the primary minerals assemblage is of course accompanied by significant changes of the chemical composition, as concerns major and trace elements. The latter are distributed amongst the main secondary mineral phases or trapped in some primary resistant minerals, but may also be leached, totally or partially. Gold is also affected by lateritic weathering, as shown for instance by morphoscopic and geochemical studies of gold grains collected in the different horizons of the profile, which indicates some dissolution followed by reprecipitation.

Jan 1, 1988

By Smith N. S, Rholl S. A, Otterness R. E

The Bureau of Mines is conducting research to develop blast designs for the control of fragmentation and rock displacement and the reduction of overall mining costs. This Bureau experiment, a program of 25 reduced-scale blasts conducted at the University of Missouri-Rolla's experimental quarry, determined the effects on fragmentation of changes in burden, spacing, explosive diameter, and stemming-explosive length. Combined with previous work at this experimental quarry examining air gap, delay, and decoupling effects, this experiment provided a data base of over 50 shots. The fragmented rock, 1000 to 3000 kg from each 3- to 4-hole blast in the 1 m bench of massive dolomite, was completely screened to assess fragmentation. The explosive used for all the tests was extra dynamite initiated by seismic caps fired from a sequential blasting machine with delays of 5.2- to 13-ms/m of burden. Empirical equations were developed which predicted the effect of shot design parameters on the fragmentation. These formulas predicted the average fragment size of each of the 25-shots to within 13 percent. For spacing to burden ratios of 1, 1.4 and 2, there were optimum burden to explosive diameter ratios (B/de) of 30, 26 and 20, respectively. Decreasing the B/d. ratio beyond these levels resulted in little or no reduction in the average size. For B/de ratios above these levels the average size increased but, at least a 15 percent reduction in the average size results when the shot design parameters are optimized.

Jan 1, 1990

By J Seppelt

The Kanmantoo Copper Project is owned and operated by Hillgrove Resources Limited and is situated in the Adelaide Hills region in South Australia. Mining in the area has taken place off and on over the last 140 years to recover metal from both copper and lead-zinc ores. This paper focuses on the commissioning, ramp up and future outlook for the copper concentrator at the Kanmantoo Copper Project with major focus on issues encountered and operating performance achieved to date.CITATION:Seppelt, J, 2012. Commissioning of the Kanmantoo Copper Concentrator, in Proceedings 11th AusIMM Mill OperatorsÆ Conference, pp 127-136 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Oct 29, 2012

By T Kojovic

"The index A*b, determined from the Julius Kruttschnitt Mineral Research Centre (JKMRC) drop weight tester (DWT) results, has become well-known in the mining industry as a reliable measure of ore hardness in impact or crushing, having the inferred units of t/kWh. This index evolved from a long history of comminution studies at the JKMRC, including the development of the now superseded JKTech twin-pendulum, the industry standard JK Drop Weight Tester (JKDWT) and the faster alterative JKMRC rotary breakage tester (JKRBT). A reduced version of the DWT, the semi-autogenous grinding mill comminution test (SMC test®), also provides estimates of the A*b though the testing of only one particle size at five specific energies. Experimental determination of A*b using the above devices/tests requires samples, with sufficient mass, to be sent to designated laboratories, registered to conduct such tests. This protocol is fine for bankable and commercial testing, where material characterisation data is used in conjunction with machine specific data in modelling and simulation, and power based calculations. However, for comparative testing, where results are required at the time of sampling (eg for plant troubleshooting or spot-surveys), or for rapid ranking of geometallurgical samples, these existing tests simply do not provide a timely, viable and cost-effective solution. In order to address this critical void in the realm of comparative testing, a new device has been developed, exploiting a central feature of single particle impact testing – that the A*b can be reliably estimated using one precise low energy test. This device, for which a patent is currently pending, called the HIT (Hardness Index Tester), has been precision engineered to allow users to break narrowly sized fragments at a set specific energy, in a safe and easy manner. The manufacturing materials have been chosen carefully to ensure compatibility with the intended use and portability to any site, whilst minimising cost. The device is supplied with a novel quality assurance / quality control (QA/QC) feature, to ensure that the targeted potential energy is consistently delivered. The product from the HIT breakage test can be quickly sized using a single screen to determine the mass per cent undersize, from which the A*b index is calculated directly at site – eliminating the need to send the raw data off-site for analysis. On presized fragments, a single test using 20 fragments takes less than five minutes to complete, and the results are immediately available. The HIT is currently being tested at a major mining laboratory in the US and the results to date have proved it can deliver on all fronts. This paper describes the new prototype device, which offers users a low cost in-house mechanism for estimating the A*b at any mine site, with potential applications on fragments up to 25 mm from drill core, blast chip rejects or the grinding circuit feed. It also outlines the results of field tests carried out by an objective third party mining group and compares the results with those from current industry standard tests conducted on the same material.Citation:Kojovic, T, 2016. HIT - a Portable Field Device for Rapid Testing at Site, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 9–16 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By A Takahashi, Y Uchisawa, M Hayashi, T Watanabe, M Susa

Owing to the deterioration of iron ore, the Al2O3 concentration in iron ore increases, and thus it is important to investigate the effect of increment in Al2O3 concentration on the microstructures of iron ore sinters. During the sintering process, a melt is present in the sinter for only a few minutes, and therefore the microstructure of the sinter doesn’t reach thermodynamic equilibrium. Nevertheless, the formation process of the microstructures can be interpreted and predicted to some extent from the equilibrium phase diagram. This study investigated the liquidus isotherm in the CaO-SiO2-Fe2O3- 5 mass% Al2O3 system at 1240°C in air and the phase equilibria of silico-ferrite of calcium and aluminium (denoted by SFCA) and SFCA-I by XRD (X-ray diffraction analysis) and electron probe micro analyzer (EPMA). The following results were obtained: 1. The ferrite melt region with a high Fe2O3 concentration shifts to the lower Fe2O3 side than the liquidus isotherm in the CaO-SiO2-Fe2O3 system. 2. The compositional region of SFCA extends in the CaOꞏ3Fe2O3-4CaOꞏ3SiO2 direction than the silico-ferrite of calcium (denoted by SFC) composition region with a 0 mass% Al2O3. 3. SFCA-I is observed in the present system, which suggests that the increment in the Al2O3 concentration contributes to the stability of SFCA-I. These results imply that an increment in Al2O3 concentration in iron ore leads to a decrement in the volume fraction of the bonding phase and that the fraction of the SFCA phase increases, and those of 2CaOꞏSiO2 and slag phases decrease in the bonging phase. The SFCA-I phase is also precipitated from the slag with an Al2O3 concentration around 5 mass%.

Jun 19, 2024

By Wong KY, Woodcock JT

Previous results have shown how con- trolled-potential sulphidization (CPS) can give improved metallurgy during rougher flo- tation of mixed oxide-sulphide copper ores. Results in this paper, using different samples and different equipment, confirm the previous results and extend the application of CPS to cleaner flotation. By using CPS, faster flotation of copper minerals (chalcocite and malachite) from clay was obtained in roughing and cleaning, and improved concentrate grades and recoveries were achieved over those by conventional manual control. The optimum sulphidizing potential (i.e. the potential of a sulphide ion-selective electrode versus a saturated calomel electrode) was -500 mV, and could be controlled to ¦5 mV, during four rougher- scavenger and three cleaner-re cleaner stages. This optimum gives the best balance between copper recovery, concentrate grade, and sodium sulphide consumption. Five cleaning circuits and five ore com- posites of different composition (0.55-1.50 per cent Cu) were examined as well as the effect of feed size and pulp density. Better results were obtained at 20 per cent solids in a Denver cell than at 33 per cent solids in an Agitair cell; this may have been related to the high clay content of the ore. Commercial equipment for pilot plant or full-scale plant application of CPS is cur- rently being developed.

Jan 1, 1986

By Rokot M

In a little over three years, Chevron Niugini has built up a team of relatively young, hard working men and women, mostly Papua New Guineans, who spend most of their working days out among people in the Southern Highlands and Gulf Provinces who are directly affected by the Kutubu Petroleum Development Project. These are Land and Community Relations officers, or LACROs. They take on a huge responsibility, not only representing Chevron but also being friend, advisor and negotiator, frequently dispensers of medicines, and agricultural advice and more. When things go well, others get the praise, when things go wrong, LACROs are the martyrs. Just as the geologists who locate the oil, the drillers who find it, the engineers who design the facilities, the construction gangs who build them, the landowners who claim it, and the Government who monitor it, so are the LACROs part of a team.

Jan 1, 1991

Legislation introduced for Queensland and New South Wales Coal mines provides different levels of prescription regarding specification of mine seals û generally in relation to capacity to withstand overpressure. In Queensland, the Coal Mining Safety and Health Regulation (2001), Section 341 (d) places a further onus on the statutory ventilation officer to æensure all ventilation control devices at the mine are properly constructed and maintainedÆ and that the ventilation officer æmust ensure a ventilation control device mentioned in the regulation à and installed at the mine meets the design criteria statedÆ for the ætype of deviceÆ. Based on the experience of the author, it appears that risk management and life cycle approach to seals has not been adopted to the same extent as for other aspects of operations. Further, because of the number of disciplines and personnel involved that may influence various factors affecting seal integrity, the opportunity for oversight or unclear allocation of responsibility is considerable. While suppliers can provide explosion or design rated seals, this should only be a starting point for application of the product in a coal mine. Application is often considered by mine planning staff (taking into consideration mine environment parameters such as water, control of gas, spontaneous combustion risk, etc) in conjunction with the colliery ventilation officer, and then construction completed by contractors under supervision of operational staff. After construction, seals often are managed by operational personnel with input from the ventilation officer. Input of the geotechnical engineer into pillar design, roadway opening size, ground support specification and most stable seal location is also required. The need for a customised design approach for each seal site is proposed in order to take into account the many and variable factors that may influence a site so that improved seal performance reliability and predictability can be developed. A program of quantitative as well as qualitative monitoring of performance and triggers for rectification or maintenance action is required, and would provide support to the aforementioned proposal. Many mines rely on visual/audible inspection and periodic bag sampling as the primary means of assessment. Other significant factors such as seal material properties, rib degradation, convergence, floor heave, effects of water on both structural integrity of the seal as well as the air tightness of the seal do not generally receive the same level of attention. Based on the above observations, the author has compiled a reference checklist in regard to the above matters, including aspects of and approaches to mine and pillar design, geotechnical modelling and data collection, civil engineering design, site evaluation and practical options available.

Jan 1, 2005

By Keyte SG

Gravity methods of recovering alluvial gold are not very efficient at particle sizes below about 0.1mm. Whereas such gold may not have been economic to recover in the past, the same may not be true today. Centrifugal concentrators, like the Knudsen and Knelson bowls, are showing promise after an inauspicious start, at least in New Zealand. The large proportion of heavy mineral in many auriferous beach sands and the natural hydrophobicity of fine gold should make flotation an attractive contender for its recovery. The conventional mechanical flotation cell is effective, but roughing, scavenging and cleaning are necessary to achieve both high recovery and low mass yield. More problematic is the difficulty of maintaining coarse and dense sands in suspension. The air sparged hydrocyclone is effective at recovering fine gold from a fine Colarado River sand, but is not effective for the coarse and dense beach sands of New Zealand. The flotation column shows much promise for these sands, when recoveries of over 80% and mass yields of less than 1% can be achieved in a single pass. The froth separator of the USSR and flash flotation could also be worthy contenders. It is felt that flotation could be limited to naturally and artificially de-slimed concentrates.

Jan 1, 1990

By D J. Brake

The risk from fire remains one of the most serious of underground mine disaster scenarios. The impacts of mine fires on the underground ventilation system and the production of toxic gases have been difficult to model and therefore assessments have relied largely on empirical data, historical precedent and subjective opinions. Underground fire modelling software has had limited availability and been technically challenging and time consuming to use especially for routine mine investigations. There has also been no well-accepted set of assumptions for fire modelling in mines, which has resulted in a lack of confidence in adopting its use more widely. This paper describes modelling of three critical fire scenarios in underground hard rock mines: a fire (LHD) in an underground diesel refuelling facility, a fire in an underground explosives magazine and a fire on an underground ore transport conveyor. Modelling was undertaken using VentsimÆs VentFIREÖ fire simulation module. It describes the basis of design, the key assumptions, the methodology used and provides examples of the outputs, conclusions and recommendations. It reviews the impacts of these fires on egress and entrapment strategies in the mine. Some general principles regarding improvements to ventilation circuit design based on this analysis are also recommended. Whilst the fire scenarios were based on actual case studies, they have been disguised for this paper.CITATION:Brake, D J, 2013. Fire modelling in underground mines using Ventsim Visual VentFIRE software, in Proceedings The Australian Mine Ventilation Conference , pp 265-276 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 1, 2013

By D Tucker, K Harney

Hatch forecasts that an increasing share of seaborne traded iron ore will be ultrafine, being either concentrate or pellet feed. This provides several challenges for the iron and steel industries, but the principal concern is: how much ultrafine iron ore can be consumed on sinter strands and with a minimal effect on productivity?This paper will identify new supply by project through 2020. Demand will be estimated for sinter production and practical steps will be identified to increase ultrafine consumption in sinter strands. The long-term iron ore price will be forecast to balance supply and demand. The paper will conclude by assessing how the pricing of ultrafine ore will develop relative to the Chinese iron ore indices.CITATION:Tucker, D and Harney, K, 2015. Iron ore ultrafines challenges and opportunities, in Proceedings Iron Ore 2015, pp 501–504 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 13, 2015

The Australian coal industry has undergone sevenfold growth over the last 30 years and since 1985 has been the world's largest coal exporter. Three quarters of Australia's coal production is exported so its future is dependent on it remaining internationally competitive with other energy sources and other coal exporting countries. Coal is likely to increase its share of the energy market during the nine- ties as oil prices increase, new coal-fired capacity is commissioned and some form of nuclear energy is developed which is of acceptable safety standards to the community for use in the 21st century. Gas may take a part of coal's anticipated market share by the Year 2000. While coal exports will increase from China, Colombia, Indonesia and Venezuela and satisfy some of this additional coal demand Australia will also expand its export production, due to its existing advantages. The United States, Canada, South Africa, Poland and USSR seem unlikely to enjoy the same degrees of expansion and some, particularly Poland and USSR, will decline. Australia will always find it difficult to compete in the more distant markets due to levels of ocean freight, although its high quality coals will tend to partly offset such disadvantage.

Jan 1, 1988

By J T. Carswell, N A. Schofield

Fluctuations in periodic reconciliations between the mine and the mill are an expected and common experience in mining and processing operations. These fluctuations are caused in part by errors in the estimates of tonnage and grade of the mined material as well as errors in the millÆs assessment of the material processed. Keeping these errors small and unbiased is an important aspect of an efficient operation whose primary goal is to derive maximum benefit from the exploitation of the mineral resource.These fluctuations in periodic reconciliations can also mask subtle but economically important problems which may take years to identify and resolve. Such problems can result from a poorly-conceived model of the mineralisation which affects both the spatial distribution of the ore as well as the tonnage - grade distribution over the range of cut-off grades. Poorly conceived models of the mineral resources and ore distribution can arise as a result of insufficient and inadequate?drilling and sampling of the mineralisation, inappropriate?application of geological?constraints in the estimation process and the use of inappropriate methods to estimate the block grade distribution. This paper presents three case studies from gold and copper mining operations, two of which experienced significant problems with their mine to mill reconciliations over extended periods of time. For the gold mine in case study 1, sampling problems were ultimately considered to be the main cause of the poor reconciliations between grade control predictions and the mill which persisted over a period of 18 months. In addition, incorrect application of resource modelling methods contributed significantly to a mismatching of the mill capacity with the mine at the beginning of operations. For the underground copper mine in case study 2, a change in the approach taken to resource modelling brought marked improvements in ore definition and more accurate predictions of ore grade and better production forecasts.The third case study describes the background to the expansion of production to exploit a large tonnage of lower-grade stockwork mineralisation in an open pit gold mine. Several years of favourable Mine to Mill reconciliation data from the mining and processing of higher grade and lower grade stockwork styles of gold mineralisation provided the confidence in the approach to grade control to support the expansion plans during a period of low gold prices.The paper is intended to complement the discussion of mineral resource estimation methods and risks in Section 6.1.3 of the Mine ManagersÆ Handbook to be published by the Australasian Institute of Mining and Metallurgy (Schofield, 2012).CITATION:Schofield, N A, Moore, J and Carswell, J T, 2012. Mine to mill reconciliation - Three case studies, in Proceedings International Mine Management 2012, pp 161-172 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 20, 2012