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By De Broglio R

The Mae Moh coal deposit was discovered some 60 years ago by villagers who noticed spontaneous combustion of coal outcrops. The first production began in the 1950's to fuel a fertilizer plant and a 12.5MW power station. During the period 1976 to 1979, three 75MW power station units were constructed on site. These have a total daily coal consumption of some 5000 tonnes and are served by a stockyard of approximately 60 000 tonnes total capacity. Stacked coal is reclaimed by means of a front end loader onto reclaim conveyors. During the years 1983 to 1986 four 150MW power station units were constructed east of the eastern seam subcrop, sons 2 km from the original power station complex. These have a daily coal consumption of nearly 12000 tonnes and are served by a stockyard of total capacity 270000 tonnes, equipped with two stackers and two bucket-wheel reclaimers for a totally mechanised system.

Jan 1, 1986

By J Li

Cannington Mine has been developing through paste backfilled stopes since the year 2000. These paste drives have been used as either production drill accesses or long-term bypasses. Prior to this study, the ground support requirements for each paste development cut were: an initial 50 mm layer of fibrecrete, weld mesh bolted with 2.4 m split sets, followed by a second coat of 50 mm fibrecrete. Both layers of fibrecrete and the layer of mesh were to be installed before the next cut could be bored and fired. This support regime proved successful at Cannington, however, the total cycle time for each cut was lengthy due to the installation and curing times associated with each layer of surface support. In an effort to reduce the cycle time a study was carried out, with the aid of RocScience’s Phase2 numerical modelling software. The modelling reviewed all of the parameters controlling the stability of a newly excavated development cut. The parameters studied included the early strength of fibrecrete, the ground support load capacity, and the strength of the paste fill masses which varies depending on the cement content. As a result of the study, the ground support standard was revised. The revision has significantly decreased the cycle time as well as fibrecrete consumption, all the while maintaining the safety of personnel and equipment.

Mar 21, 2011

By T Smith

The evaluation of a new mineral resource and its economic viability is critically dependant on the quality of the assay data as it is this data that defines the grade of the resource. However, all too often the procedures of sampling and chemical analyses used to generate such data are neglected or given little consideration until final modelling and evaluation are under way. This approach frequently requires large reassay and/or re-sampling programs to be undertaken to validate or to improve the integrity of the data base. This paper outlines a step by step approach to ensure quality data is achieved and then maintained throughout the entire exploration and resource development program. This involves the use of correct field sampling methods, assay methods designed to give the required levels of accuracy and precision and quality procedures in place to monitor the effectiveness of the overall process. Thorough documentation is an overriding and necessary part of the entire process. Practical examples are given to demonstrate the use and value of these methods.

Jan 1, 1998

By S C. Dominy

A high nugget effect and the presence of coarse gold characterises many vein-gold deposits. The effective sampling of these deposits is often difficult because of the relatively low concentrations involved and erratic nature of the gold. Geological complexity often compounds this effect. Underground development, in-fill drilling and bulk sampling/trial mining are often required to delineate Ore Reserves. Winzing is an historical technique that was used to gather geological and sampling data during underground exploration. It permits access to the mineralised structure below the current datum to help determine viability. Winzing has always been considered an arduous and dangerous task. Modern technology has led to the development of the Mobile Supersucker, essentially a giant vacuum cleaner. This system permits safe and efficient winzing activities, and allows the collection of bulk samples for grade estimation. Bulk samples from horizontal development have long been collected to help define mineable grade. However, when defining blocks below current development, there has been over-reliance on ineffective æsmall sampleÆ drill data. The Mobile Supersucker permits safe and cost-effective development of winzes and off-winze sublevels.

Jan 1, 2003

Current NSW Government policy requires searching for more than just minerals during an exploration program - add endangered fauna and archaeological relics for a start.

Jan 1, 1995

By Forssberg E

This paper presents the experimental results on the effects of slurry Theology on ultra-fine grinding by a stirred ball mill. The amount of dispersant, slurry density and the particle size were selected as the parameters. The viscosity of dolomite-water slurry was measured by rotational viscometers. It was found that by adding enough dispersant, the effect of particle size from 1 to 10 pm on the slurry theology could be eliminated, but a strong effect of slurry density (tested for a range of 65 to 75 wt per cent) remained. The use of dispersant transformed the slurry from Bingham plastic flow to dilatant flow, which reduced the yield stress to zero, but increased the viscosity at higher shear rates. During the milling process, the viscosity was stable. The yield stress, however, increased suddenly from zero after a certain milling time. The mill operation stopped at the point where the yield stress increased due to poor slurry fluidity. The milling efficiency was found to be higher at a lower amount of dispersant addition or a lower slurry density within the experimental limits.

Jan 1, 1993

By G Partington

A regional scale prospectivity model was developed for Papua New Guinea (PNG) to identify areas of porphyry Cu-Au mineralisation. Weights of evidence modeling techniques were used to determine spatial correlations between porphyry Cu-Au mines and predictive maps created from available spatial data. These predictive maps were then combined into a final prospectivity map. Despite limited regional scale data the model has successfully identified areas of known porphyry mineralisation as prospective and has also identified areas where new mineralised systems may be discovered with further exploration. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

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

The title of this paper implies, and the text explicity states, that Sen and Spottiswood (1984) have found a new mineral species related to geocronite and jorganite. I believe that there is inadequate justification for this claim.The X-ray powder diffraction pattern reported by the authors exhibits a close similarity to that of geocronite, as stated by the authors, which suggests a close structural relationship at the very least. It is therefore reasonable to recalculate the results of the microprobe analysis reported by them to atomic proportions on the basis of the geocronite formula. This calculation, whether based on the formula used by Sen and Spottiswood (1984), or on one derived from a crystal-structure analysis (Birnie and Burnham, 1976), namely Pb18 (Sb, AS)11S46, with a total of 86 atoms, gives the results shown in Table 1.

Jan 1, 1985

Jan 1, 2004

Carbonate replacement tin deposits in the areas studiedhere are genetically related to biotite granites. Biotite in the granites is distinguished by distinctive compositional features. High MgO content is found in biotite in the Renison Bell granite; high MnO and A1203 contents in the Gejiu granite; and high FeO content in the Xinlu granite. The compositional features of biotite in the granites are reflected in skarn minerals formed around the granites.Granites associated with these tin deposits are characterized by different accessory minerals. Magnetite-bearing granite in the Xinlu deposit is related to the andraditic garnet (andradite 40-45 mole%)-hedenbergite skarn, with tin mineralization occurring in the contact skarn only. The sphene-bearing granite in the Gejiu deposit is related to the grossular garnet (grossular 50-60 mole%, almandine 20-30 mole%) -salite skarn, with tin mineralization occurring in the contact skarn, as well as stratabound replacement orebodies in the distal skarn. The ilmenite-bearing granite in the Dachang deposit and the Renison Bell deposit is related to the grossular-diopside skam, with tin mineralization occurring 500-1500 metres vertically and 1.5-3 km horizontally away from the granite contact.

Jan 1, 1990

A survey has been undertaken of the petrography of North Island greywackes with a particular focus on the occurrence in them of smectite (swelling clay) and chlorite, two minerals that are closely associated, chemically similar, and commonly interlayered with each other. Smectite is the mineral which is a major cause of greywacke aggregatesÆ poor performance. Smectite occurs in post-metamorphic shear zones and in surface weathering profiles over greywackes. This study focuses on the petrography of fresh greywacke rocks.   The occurrence and abundance of smectite and chlorite and their relationship in greywackes is largely a function of the chemistry of the sediment and the maximum temperature that the sediment has been subjected to during diagenesis and/or very low grade (anchizone) metamorphism. Rock chemistry, particularly total iron and MgO, determines the smectite and/or chlorite content in fine-grained greywackes (argillites and siltstones) but chemistry is less influential in sandstones, where at low grades of metamorphism much of the Fe and Mg of the rock is held in unreacted detrital minerals and the mineral constituents of lithic grains.   Four zones which represent different levels of diagenesis and very low grade metamorphism, based on the crystallinity of illite and chlorite in the greywackes, and the proportion of smectite interlayered with chlorite, have been mapped in the North Island. In the anchizone smectite does not appear as a discrete mineral, it is always interlayered with chlorite. In the upper anchizone chlorite contains approximately ten per cent of smectite interlayered with chlorite. In the lower anchizone about 30 per cent smectite can occur in chlorite.   In addition to the smectite and chlorite inherent in the greywackes as the result of the thermal overprint, smectite as a discrete mineral and smectite-chlorite interlayered minerals with high levels of smectite, occur in abundance on shear zone surfaces and in alteration zones adjacent to shear zones; these are the main contributers to the high levels of smectite recorded in many greywacke aggregates.

Jan 1, 2006

By T Baumgartl, D R. Mulligan, D Doley, A Schneider

In arid and semi-arid areas evapotranspiration (ET) cover systems are often used to mitigate contaminated seepage from hazardous mine waste into the adjacent environment. The theory of ET covers is based on the water balance equation with the aim of minimising seepage. While cover systems are commonly trialled, the influences of variability in climate and cover structure on water balance equation parameters are seldom investigated.Water balance equation parameters and their variability were analysed for two ET cover trials constructed from benign waste rock in semi-arid Australia. Seasonal and inter-annual variations in rainfall critically influence cover performance. For successful cover system operation, the average return periods for higher than average rainfall should be taken into account. In addition, failure of ET covers has a higher probability in areas with marked rainfall seasonality. Water holding capacity and plant available water content are low in covers constructed from waste rock. Changes in water holding capacity due to variation in particle size distribution are likely and critically influence cover performance. The application of topsoil can be beneficial for water ingress control through run-off, but a balance has to be struck between run-off, erosion and plant available water. Changes in vegetation composition only influence evapotranspiration water losses at plant coverage exceeding 50 per cent, which is unrealistic in semi-arid areas. This study showed that the capacity of ET cover systems to hold and dispose of received rainfall is often lower than assumed by industry practitioners. Furthermore, in order to improve reliability of long term cover performance, the variability of rainfall and water holding capacity of the cover has to be included in water balance models.CITATION:Schneider, A, Baumgartl, T, Doley, D and Mulligan, D R, 2012. Variability in parameters of the water balance equation and their influence on evapotranspiration cover performance, in Proceedings Life-of-Mine 2012 , pp 293-300 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 10, 2012

By L Lorenzen, H Muller, L Bernard

Australian companies and consultants are becoming ever more involved in projects in African, South American, East European and Middle Eastern countries. However, significant differences in culture and approach to projects sometimes make these projects challenging for reasons that are not purely technical. Often the challenges are rather related to how the project owner and local authorities perceive the reality. These perceptions and sometimes unrealistic expectations regarding project costs and potential outcomes need to be addressed by the æWesternÆ project developer and consultant.This paper will discuss the specific experience of Snowden in studies commissioned by companies from such countries for the development of very large, low-grade gold deposits in some of the most inhospitable areas in the world. The paper will further review similar projects undertaken in other ænew worldÆ countries and compare these to the initial Snowden experience.As the process operating costs of operations in many of these countries are extremely competitive when compared to the typical Australian operating costs, the paper will review the operating costs and the factors which may be pertinent to a large project of this nature, both in the Australian and the ænew worldÆ context. Will Australian-based operations be able to compete in the global gold market when the gold price softens again, as it will do at some stage in the possibly not-so-distant future?CITATION:Muller, H, Lorenzen, L and Bernard, L, 2013. Challenges of developing low-grade deposits in ænew worldÆ countries from a mining consultantÆs perspective, in Proceedings World Gold 2013 , pp 307-314 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

One of the strategies introduced within Pasminco Mining to survive low commodity prices is to formally implement a `Quality Education System'. The net result has been a consistent approach to quality within and across mine sites. This `quality system' has been adopted in the technical computing environment and the immediate benefits have been: ò A clearer understanding of the systems, processes and relationships that involve technical computing. ò A re-focussing on customer (user) requirements. ò Inclusion of managers as customers with their own requirements of performance and quality, in addition to access to Executive Information. ò New ways to measure the `performance' of a technical computing environment which includes using maintenance costs. Observations are that there is an overlap between `traditional' information technology (IT) methodologies and quality systems being put in place in the broader workplace. This overlap is most apparent in the area of analysing customer requirements. In the IT environment customers are viewed as users, and their requirements determined by undertaking a requirements analysis. A data flow diagram traditionally used in the IT environment and not as a tool in quality systems, has been used in a novel manner to help identify the customers of the technical computing department. It has also been useful in illustrating the work processes and relationships between the entities in this diagram and in directing the future initiatives needed to fulfil the customers' changing requirements.

Jan 1, 1995

By D A. Williams, P J. Chapman

Constructing upstream raises with tailings is an accepted and cost-effective practice in Western Australia, where the climatic conditions are favourable, desiccation (and hence overconsolidation) occurs rapidly due to air drying and there is a perceived low seismic risk. This is in contrast to many other settings, where there is either a positive water balance, high seismicity or a combination of both. In recent times, there has been an increased focus on seismicity in areas of Australia that have historically been considered to be of low seismic risk. The increased focus is driven by two recently published documents used by tailings practitioners and increased awareness from corporate entities, particularly those with mines in high-seismicity regions such as South-East Asia and South America (particularly Chile).The increased awareness has resulted in increased rigour being applied to seismic design of tailings storage facilities (TSFs) in general, and particularly upstream-raised TSFs. This paper compares the results of a seismic stability assessment for an upstream-raised TSF located in the Goldfields region of Western Australia, which has historically been considered a low seismic area, with a seismic stability assessment carried out for a crossvalley TSF containing similar tailings but located in a high-rainfall, high-seismic setting in South-East Asia. The influence of the adopted design earthquake values on the results of the assessments and the potential impact of the maximum design earthquake (MDE) on the design approach is presented for both cases. The results indicate that although the Western Australian site is located in an area thought to have low seismic risk, the screening level analyses suggest that the MDE could result in liquefaction of the tailings materials. Not surprisingly, liquefaction was also indicated for the South-East Asian site. The outcomes of the assessment are also presented.CITATION:Chapman, P J and Williams, D A, 2015. Seismic design of upstream-raised tailings storage facilities in a semi-arid, low-seismicity setting, in Proceedings Tailings and Mine Waste Management for the 21st Century, pp 157–162 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 27, 2015

By P Craig, A Crosky, H Ramandi, S Saydam, H Chen

Frequency of reports on premature failure of rock bolts and cable bolts have increased in past two decades. Such a failure threatens both the safety of underground mine workers and the economic viability of the operations. Herein, we report on analysis of rock bolts and cable bolts failed recently in three underground mines in Australia. Magnetic particle inspection (MPI) and scanning electron microscope (SEM) techniques were used to study the failed bolts. MPI showed a number of subcritical cracks on the surface of the bolts. The majority of the cracks in both cable bolts and rock bolts were initiated from the base of ribs (indentation) where the stress concentration was high. SEM examinations showed tearing topography surface (TTS) in all failed rock bolts and cable bolts. These indicated that the failure occurred through hydrogen assisted stress corrosion cracking (HISCC). The results of this study enhanced the understanding about the failure of rock bolts and cable bolts in underground mines. CITATION:Chen, H, Ramandi, H, Craig, P, Crosky, A and Saydam, S, 2018. Analysis of premature failure of rock bolts and cable bolts failed in underground coal mines, in Proceedings The Fourth Australasian Ground Control in Mining Conference (AusRock), pp 407–413 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 30, 2018

The sudden. explosion of relatively inexpensive digital process control computers has accelerated interest in the possibilities of economic savings by their use. In particular the metalliferous industries have shown that they are willing and capable 6f grasping this new technology and putting it to good use. These industries have a number of problems which need special attention. In many cases the process is difficult to measure and a reaction is often controlled by measuring a secondary effect, computing its relationship to the reaction and then applying the necessary corrective action. This creates problems in building the process model, designing the computer to process interface and in the subsequent system development. Environmentally the metalliferous industries create conditions which severely test sophisticated electronic equipment. Care taken in locating and housing this equipment is a major factor in ensuring reliability in Operation.

Jan 1, 1977

By Cullen JF

Australia has a large resource of manganese at BHP's Groote Eylandt mine which has been progressively developed over the last two decades. While much of the product is marketed internationally to the iron and steel industry, substantial quantities are processed in Australia at the Company's ferro alloy works in Tasmania. In addition, small but increasing quantities of ore are being consumed by the non-metallurgical industry. Fluctuating fortunes in the steel industry produce similar trends in the marketing of manganese. The increasing cost of freight and power together with strict environmental control is further affecting the market balance. Mine operators are expanding into the alloy making field. Reduction in usage in less developed countries is occurring.

Jan 1, 1982

A flow sheet has been developed to treat a high tonnage highly preg-robbing gold ore. The ore is low grade and fine grained with a high proportion of very fi ne free gold. The key components of the flow sheet include gravity, flotation, intensive cyanidation with direct electrowinning, and carbon-in-leach of the flotation concentrate. The circuit produces a low overall mass pull to concentrate allowing economic intensive treatment of large tonnage low-grade material. Efficient recovery of fine gravity gold using a Falcon concentrator in both the milling and flotation circuits, and subsequent intensive cyanidation in a Gekko InLine Leach Reactor (ILR) is critical to the process with over 70 per cent gold recovery expected in this circuit. Grind size control was also found to be important in controlling the activity of the preg-robbers in the carbon in leach circuit and also in the solid liquid separation performance. Tests at the large-scale demonstration plant have been conducted to demonstrate the effectiveness of this flow sheet. A large low-grade deposit is currently under development with the aim of developing a 10 Mt/a treatment plant with the subsequent addition of equivalent sized process lines in multiples of 10 Mt/a. The economic development of this orebody is critically dependant on understanding and exploiting the properties of the ore. In particular it is critical to minimise the effect of preg-robbers by recovering free gold with Falcon concentrators and InLine Leach Reactors. Recovery of the remaining gold by flotation into a small mass yield allows this fraction of gold to be treated by CIL leaching utilising high carbon levels. It is critical is to ensure operation at the optimal grind size to maximise liberation of the free gold and minimise pregrobber activity. The ore has been identified as preg-robbing with low recoveries obtained if treated using conventional cyanidation and carbon absorption. The mineralogy consists of predominantly fi ne grained free gold with minor sulfides including pyrite and arsenopyrite. With conventional cyanide leaching in the absence of carbon, gold recovery is less than 50 per cent. Direct cyanide leaching of the ore in the presence of activated carbon results in an improved but still uneconomic gold recovery. The gravity recoverable gold (GRG - as defined by Andre La Plante) content of the ore has been measured to be 70 per cent to 85 per cent in various tests with liberation grind size of approximately 106 ¦m. This indicates gold is predominantly free and suitable for recovery by batch centrifugal concentrators into a low mass yield. This property of the ore presents the opportunity to maximise the recovery of gold by separating it from the majority of the preg-robbers prior to leaching. Due to the very fine gold particle sizes and the necessity to maximise recovery of this fine fraction Falcon concentrators were selected for the duty, with their proven high recoveries at very fine gold sizes. The gravity recovery in the milling circuit is designed to be in the range 55 to 65 per cent. This has been achieved in the existing pilot plant using a Falcon operating on ball mill discharge within the mill recirculating load. Intensive leaching in an InLine Leach Reactor is essential to recover the gold from the gravity concentrates. Tabling is not a preferred option since recovery is lower than intensive cyanidation and any gold losses to table tails will report to CIL where recovery is reduced by the presence of preg-robbers. Furthermore, tabling recovery from the gravity concentrates is particularly poor due to the fine particle size of the free gold. ILR recoveries of 98 per cent were demonstrated in the pilot plant using an ILR100BA and leach conditions were investigated in the lab using pilot plant generated Falcon concentrate. Recovery of gold from the pregnant solution was achieved with direct electrowinning at pilot and efficiency and sizing parameters were determined at lab scale. To further increase free gold recovery Falcon concentrators will be installed in the flotation circuit. Location of the Falcons in the circuit is not finalised but installation on the rougher concentrate stream is favoured since it will allow multiple pass recovery. This is expected to recovery a further ten to 20 per cent of the gold, as indicated by lab tests on pilot plant generated material. The gravity concentrate from the flotation circuit will also be leached using InLine Leach Reactors. Initial intensive cyanidation tests carried out on lab generated flotation concentrates indicated higher recoveries than CIL can be obtained even though the concentrates contain significant levels of preg-robbing material. This can be explained by the high cyanide, high pH leaching conditions used in the ILR which alters the absorption equilibrium of the preg-robbers. Further optimisation of the leach conditions will be undertaken once more concentrate becomes available. Recovery of the remaining gold content is achieved by flotation into a small mass yield, however the preg-robbers are also recovered into this concentrate. Due to the presence of the preg-robbers gold leaching must be carried out in the presence of high levels of activated carbon in a CIL system. The recovery has been shown to be strongly dependant on the carbon loading and the concentrate particle size. The carbon competes against the preg-robbers for dissolved gold while excessive grinding increases the surface area and activity of the preg-robbers. This has been demonstrated in test work however the economic optimum leaching conditions and carbon loading have yet to be determined. The grind size is critical to the economics of the project, not only due to its effect on gold recovery but also due to its effect on the major operating and capital costs at both the front and back end of the process. It is critical to grind enough to obtain both gravity free gold and flotation liberation at low mass yields however over-grinding results in large increases in mill size and power at the front end and filtration or thickening costs at the tails. Because these unit operations treat essentially all the plant feed even small changes can result in major impacts on project economics. The viability of this project is greatly enhanced by the high recovery of gold into a small mass yield. In particular the production and intensive leaching of the free gold gravity concentrates will allow over 70 per cent of the gold to be recovered efficiently with minimal impact from preg-robbers. By using flotation the mass of the remaining fine preg-robber contaminated material, to be leached in CIL, is greatly reduced allowing this difficult material to be economically treated. This is an ABSTRACT ONLY. No paper was prepared for this presentation. 

Aug 1, 2010