Search Documents

For the last decade Australia has been the leading exporter of both steam and coking coal. In the ten-year period 1989 - 1998 steam coal exports increased by 93 per cent and metallurgical coal exports increased by 50 per cent. However, profitability of the steam coal sector has been disappointing. The coking coal sector, especially the hard coking coal segment, has fared better but its profitability was more because of its ability to maintain relatively high prices rather than its inherent productivity. Until quite recently the Australian coking coal sector was widely expected to be able to maintain this comfortable state without undue effort for the three major æpartnersÆ; the companies, the State Government and the unions. But coking coal could now be heading down the path followed by steam coal that ends with long-term over-supply and, despite steady improvements in productivity, poor profitability. Steam coal entered the ænewÆ era of long-term over-supply some years ago. Over-supply was due to the rapid increase in production in Indonesia, often from new mines and Australia. AustraliaÆs production rise was underlain by the apparent belief that the best way to lower costs was to increase production. In the first couple of years costs didnÆt fall much but the additional tonnage was sold at lower and lower prices into the spot market. By mid-1998 the difference between the contract price set with Japanese utilities and spot sales was often in excess of $US12 per tonne. Japanese contract prices and tonnages have since fallen significantly. Steam coal has moved from being a product to being a commodity. Any profits are due more to the low Australian dollar rather than inherent mine productivity. Seaborne coking coal trade has been dominated by Australia, Canada and the USA, with the USA becoming less competitive. Unfortunately, when the Queensland capacity expansion was well down the pipeline, the Asian financial crisis occurred and the Japanese economy entered what appears to be a long-term recession. Contract prices fell 18 per cent, tonnages decreased and some mines have been reclassified as supplying lower priced coking coal. The paper analyses past and expected future trends in labour and mine productivity, rail freight and FOB export port cash and total costs of the Australian steam coal and coking coal sectors and discusses the market outlook for Australia. The future economic viability of the industry is analysed and discussed in the light of the rapidly changing global environment.

Jan 1, 2000

By J P. Moodie

Recent trends in flotation technology are briefly reviewed. These show that considerable development has been made as the operators, suppliers and technologists have responded to the challenges of the industry. Most of these advances have been based on empirical and phenomenological methods. There is a considerable opportunity to make further advances through a more fundamental, scientific approach. Some of this work is discussed and, although progress is being made on this front, industrial uptake has been somewhat slow. A number of specific issues facing the industry are discussed.

Jan 1, 2005

The New South Wales Department of Mineral Resources has, since 1974, administered the Derelict Mines Rehabilitation Program (DMRP) to reduce the environmental impacts of abandoned and orphan mine sites. The application of the DMRP is presented in case studies of sites from the South Maitland Coalfield featuring residual drainage of acidic and saline water in a semi urban and rural community setting. The acidity here is typically derived from iron oxidation in shallow underground coal mine workings and in surface emplacements of coal washery reject materials. This paper presents summary information on AMD investigation, monitoring and rehabilitation. The experiences of community expectation, stakeholder consultation and peer review are discussed.

Jan 1, 2003

By Callcott R

Prediction of raw coal size distributions and those generated by processing are examined using spreadsheets and the matrix analysis of breakage processes. Run of mine coal size distributions are predicted from the lithotype properties using a

Jan 1, 1998

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 Proffett JM

Batu Hijau is a calc-alkaline, island arc porphyry copper-gold deposit located in the southwest corner of Sumbawa Island in the Banda archipelago of southern Indonesia. Proven and probable reserves are 913 million tonnes at an average grade of 0.53 per cent copper (10.631 billion pounds Cu) and 0.41 g/t gold (389 tonnes Au). Construction of the deposit infrastructure began in October 1996, and formal approval for the project mobilisation was granted by the Indonesian government in May 1997. Preoperational testing and start-up of the first grinding line is scheduled for mid-year 1999.Copper and gold mineralisation are genetically related to at least three tonalite porphyry dykes and small plugs which intrude a quartz diorite stock that was emplaced into andesitic to dacitic pyroclastic rocks and lava flows. Faults are uncommon, and where they occur they do not significantly displace hydrothermal alteration and mineralisation zones.

Jan 1, 1997

By P H. Warton

It is proposed to construct a gold extraction plant at Matatoki, near Thanes. Ore to be processed at the mill will come from reopened and enlarged underground mines north of Thanes. The project has been described in some detail in environmental impact reports (Worley Consultants Ltd 1984, 1987), and is now at an advanced stage in terms of obtaining the required statutory approvals.

Jan 1, 1987

The collapse of the I.T.C., the subsequent fall in the price of Tin, and the lifting of quotas saw the Renison concentrator resuming full seven- day operations at maximum capacity in 1985/86. Performance was sus- tained in terms of grade and recovery, and in some areas improved, over this period. A further challenge was declining head grades, and the need to treat higher proportions of less amenable ore types. The complexity of the flowsheet and the method of mining and ore handling predisposes the process to unstable operation, and solving this problem comprises a major component of the current development effort. The concentrator has an imbalance of capacity between processes, and excess in some areas is being adapted to enhance the capacity of others. Magnetic susceptibility of various minerals is being exploited to greater effect. Significant performance gains are achievable by improving exist- ing unit process efficiency, particularly in grinding, gravity processes and Cassiterite Flotation. This paper reviews the metallurgical developments, both recently implemented and planned for this year, which have contributed to main- taining Renison Limited in a competitive position in the post I.T.C. Tin industry.

Jan 1, 1988

By P M. Downes

Porphyry-related skarns are common around thePacific Rim. Examples include Cadia and Goonumbla (Australia) Ok Tedi (PNG) and Ertsberg and Grasberg (Indonesia). Although usually treated as separate to the adjacent porphyry copper-gold (Cu-Au) deposit, skarns near porphyry deposits are commonly inextricably part of the larger Cu-Au system(s). Using Cadia as the primary example, we demonstrate that large, zoned, calc-silicate skarns necessitate very large porphyry systems. The Big Cadia and Little Cadia Fe-Cu-Au skarns are associated with the Late Ordovician to Early Silurian high-K calc-alkaline to shoshonitic Cadia Intrusive Complex (CIC). Together, these skarns total ~40 Mt of Cu-Au ore but are much smaller than the adjacent Cadia EastûFar East, Cadia Hill, and Ridgeway porphyry-related Cu-Au deposits. Historically these skarns were large, economically significant and highly controversial deposits. Porphyry-related skarns typically have well-developed calc-silicate and ore zonation. At Cadia, classic skarn zonation has been mapped between Cadia Quarry (proximal) and Big Cadia (distal). Over this 800 minterval, mineralogy trends from: proximal garnet > pyroxene, grading to; fe-oxide-rich skarn; and distal haematite-epidote-rich skarn. At Little Cadia, analogous but symmetrical alteration zonation is present. Big Cadia formed from fluids that migrated laterally within calcareous units and were sourced from strongly altered quartz monzonite phases of the CIC at Cadia Quarry. Isotope studies and mass-balance calculations suggest that prograde and retrograde skarn alteration was caused by magmatic dominated fluids. They also indicate that the mapped alteration system at Cadia Quarry is insufficient to account for the total volume of Fe present at Big Cadia. Despite the typically oxidised nature of many porphyry systems, not all skarns in the porphyry environment are oxidised. Assimilation of carbonaceous sediment by hydrous, alkaline intrusions could lead to reduced Au skarns rather than porphyry deposits. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

The Yabulu refinery of Queensland Nickel Pty Ltd located near Townsville now imports more than three million wet tonnes per year of nickel laterite ore from New Caledonia and Indonesia, making it the largest importer of any commodity in Australia. The project has illustrated that importing untreated bulk ore and re-exporting high value products makes good economic sense for the company and the nation. The economics of this exercise have been considerably enhanced in the past year by changing the project's principal product from nickel oxide sinter to refined high purity nickel metal. It is one of the few operations in the world where nickel ore is transformed to nickel metal at a single site. Several novel technological processes were developed at Yabulu and incorporated into the refinery to allow this product transition to occur. By utilising internally developed technology the new processes were installed at a capital cost of less than $10 million. It is unique for a large nickel producer to completely change the quality of its entire product range many years after the plant was constructed and considerable attention to marketing the new products has been required.

Jan 1, 1995

By P Dean, M Elmouttie, Y Duan, X Luo

Slope instability is one of the major concerns in open pit mining operations. A significant collapse of the pit wall can result in injuries, damage to machinery and interruptions to production. A broadband microseismic monitoring technique has been developed for diagnosing the healthy condition of a target slope area. This technique has been successfully applied to an open pit mine in Chile. Our research has found that this microseismic monitoring technique can be used in open pits for tracking and locating a falling rock that is rolling on a slope, if a dedicated seismic sensor network has been established. In collaboration with other monitoring techniques (radar, laser scan, aerial photography), more accurate determination of rock rolling trajectories can be obtained. In this paper, an example of using the CSIRO microseismic monitoring technique at an open pit mine is presented. Results from an experiment where we used the microseismic technique for determination of the trajectory of a rockfalling on a slope are also presented.

Nov 8, 2021

The kinetics of desorption of nitrogen from molten iron were investigated using the electromagnetic levitation technique. The respective influences of gas flow rate and surface active element (S) were examined. A second order behaviour with respect to the nitrogen concentration in the melt prevailed at all experimental conditions. Sulphur had a marked inhibiting effect on the desorption rate. The experimental results on the rates of nitrogen desorption have been interpreted with the aid of a reaction mechanism consisting of a sequence of elementary steps.

Jan 1, 1991

By Fee BS

This paper describes four new families of collector products which are currently being introduced at the industrial level. A brief summary of the chemical basis behind each product family will be given. This is then followed by a selection of flotation examples which illustrate the more important use characteristics that have been observed to date. It is becoming more apparent with further testing that these four new product families can offer both technical and economic advantages to the industrial flotation process operator.

Jan 1, 1993

After the minim operation, most raw materials that occur in the earth's crust require some form of processing or refining before they can be converted into a final end product. In the mineral industry these remarks apply to materials such as iron ore, bauxite, limestone, copper ore and many others that are found in Australia in large quantities. Processing plants for these raw materials operate more efficiently, however, if the feed to them is consistent in both physical and chemical characteristics. Such uniformity rarely occurs in nature so that some form of homogenisation, or blending, is required ahead of the processing plant. Bending also assists the mining operation itself by reducing; the need for selective mining and, by combining high and low grade materials, a more uniformly graded, commercially acceptable product can be obtained, thereby increasing the commercial life of a mine or quarry. Bed blending is the most efficient of the processes available, and following its development in the United States in 1905, over 100 plants have been installed, or are under construction, all over the world. The original process, the Robins--Nessiter system, has been the subject of continued improvements and refinements, so that economical capacities are possible from less than 100 l.t.p.h. up to 10,000 l.t.p,h. and beyond.

Jan 1, 1969

By B B. Beamish, M S. Kizil

The processes that take place during the development of a heating are difficult to visualise. Bulk coal self-heating tests at The University of Queensland (UQ) using a two-metre column are providing graphic evidence of the stages that occur during a heating. Data obtained from these tests, both temperature and corresponding off-gas evolution can be transformed into what is effectively a video-replay of the heating event. This is achieved by loading both sets of data into a newly developed animation package called Hotspot. The resulting animation is ideal for spontaneous combustion training purposes as the viewer can readily identify the different hot spot stages and corresponding off-gas signatures. Colour coding of the coal temperature, as the hot spot forms, highlights its location in the coal pile and shows its ability to migrate upwind. An added benefit of the package is that once a mine has been tested in the UQ two-metre column, there is a permanent record of that particular coals performance for mine personnel to view.

Jan 1, 2005

By H Rose, T J. Sheer, M Dumka

Whenever rock is tipped from above, severe eruptions of airborne dust occur into the airways connected to tipping stations of rock passes (ore and waste) on the lower levels of a gold mine in the North West Province of South Africa. An investigation was undertaken to understand the nature of the physical phenomenon, in order to propose possible solutions. Accordingly, measurements were taken underground, involving the simultaneous logging at two levels of the transient pressures produced in the orepass by tipping from various levels. Two portable data loggers with associated transducers were custom-built for this purpose. Measurements were taken during a tipping program in which rock quantities and levels were controlled. Pressure pulses that are generated by the falling rock drive the airborne-dust eruptions. When tipping from a specified level, recorded pressure pulse waveforms were found to be repeatable on any given level, irrespective of the amount of rock falling, but measurements were conspicuously different on different levels. It was recognised that a pressure pulse is generated as the falling rock passes through the constricted region û a relatively narrow neck û at each tipping station. In passing through the constricted areas the mass of falling rock acts as a æleaky piston in a cylinderÆ and compresses the length of the air column in the orepass below that level. Once the rock has passed through the constriction, the pressure is released and this behaviour causes a regular train of pressure pulses that are separated by the time taken for the rock to move from one level to the next. Based on this physical understanding of the dust eruptions, a computational model has been developed that can reproduce all the main features of the measured phenomena. The model has been verified adequately against the measurements and can now form the basis for simulating a range of possible engineering solutions.

Jan 1, 2005

By S P. Suthers, J M. F Clout, J J. Campbe

An advanced technique for modelling hydrocyclone separation performance has been developed. This technique is based on the combined modelling of hydrocycloning parameters and ævirtualÆ iron ore feed. The virtual feed modelling was performed using a novel (in-house) software package called æRecognitionÆ, which uses data from optical image analysis to classify the particles in certain size fractions according to total iron content and calculates data for every grade class. These data include the average mineral composition and density of every liberation class in every size fraction. This information about every size fraction, representing the ævirtual feedÆ, was input to the mineral processing modelling package USIM PAC. The hydrocycloning process was then modelled for this virtual feed using the Plitt hydrocyclone model. Empirical calibration coefficients for the hydrocyclone model were calculated using an optimisation procedure in Excel. Pilot-scale hydrocyclone beneficiation experiments were performed on an iron ore blend, using different hydrocyclone pressures and per cent solids in the feed pulp. These experiments were modelled and the modelling results were compared with the experimental results. The new modelling approach enables prediction of the recovery of each mineral in the products, calculation of the total iron grade and recovery, and optimisation of iron ore beneficiation using hydrocyclones.

Jan 1, 2005

The Burragorang Valley lies approx. 95 km by road south west of Sydney and some 35 km west of Camden. It is over 80 km in length and varies in width from 3 km to over 16 km. Geologically, the history of the Burragorang Valley is of interest. It was referred to by early geographers and N.R.M.A. booklets as the largest sunken valley in Australia. This description is incorrect as it is a water worn valley formed by the dissection of an uplift in the south western portion of the large Sydney Sedimentary Basin. Ages2 ago there extended right across the Blue Mountains, a continuous tableland into which the Nattai, Wollondilly and Cox's Rivers have carved out the formation of the Burragorang. This dissection together with other valleys such as the Megalong, Jamieson and Grose, formed part of the eastward drainage pattern of the uplifting tableland into the Pacific ocean. The lapse of time since the streams in the Burragorang began their work of erosion can

Jan 1, 1976

By A G. L Pratt, G F. Dunstan, A Leonforte

The selection of the material sizing and mine dewatering systems are important elements in the development of a large-scale, high tonnage (greater than 4 Mt/a) underground hard rock mine. The sizing system will influence the size and type of the ore haulage system and therefore how the underground project is developed. With more underground developments considering or implementing caving methods of mining, the selection of the material sizing systems is also influenced by the caving fragmentation. Traditionally, crusher systems are used for material sizing in large hard rock mines, with the crusher installation and its ancillary equipment representing a substantial capital investment. Underground cave mining type operations generally express themselves with large surface subsidence areas, which can lead to large inflows of water from major rain events or purging underground aquifer systems. To minimise disruption to mine production, the dewatering system needs to be sized, with consideration to both storage and pumping capacities. The balance between storage and pumping capacity is assessed to provide the optimal economic solution with the appropriate risk measures. This paper outlines a process for the selection of material sizing and dewatering systems for large-scale caving operations. This process is illustrated with information drawn from NewcrestÆs Ridgeway Deeps Block Cave project. The Ridgeway Deeps Block Cave is located directly beneath the existing Ridgeway Sublevel Cave Mine.

Jan 1, 2008

Roller seed screens were installed at The Broken Hill Proprietary Company Limited (B.H.P.) Whyalla pellet plant to replace vibrating screens on the green ball circuits. The installation of roller screens was justified by improving the sizing of the green balls. This improved sizing increased the yield of fired pellets produced from green balls thus decreasing the fuel consumption. The fired pellet sizing was improved also. This paper discusses the configuration of the roller screens installed at Whyalla, quality of green balls produced, advantages of roller screens compared with vibrating screens and future development of roller Screens.

Jan 1, 1984