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By R Wilson, S Luke, R Williams, B Freeburn

"In 2010, two McLanahan RSS14×50 scrubber screens were installed at Fortescue Metals Group’s (Fortescue) Christmas Creek site. By 2015, the trommel (screen) section had effectively reached the end of their serviceable life. This was determined by regular measurement of structural components over the previous 18 months that tracked wear life. At the same time, numerous trials and optimisations had taken place on screen panel design and material composition. During 2015, a new set of trommels were designed, manufactured and installed that incorporated many new features: increased open area to facilitate high throughput, improved wear protection for structural members, simplified trommel panels and realigned discharge ports to reduce wear on exit. Numerous other upgrades have taken place on the drive system, feed chutes, liner and weir configurations and park brake, to name a few. This paper will highlight how regular measurement drove design changes and how the site and the original equipment manufacturer (OEM) managed a replacement program that has delivered improved performance.Citation:Wilson, R, Luke, S, Freeburn, B and Williams, R, 2016. Regular Measurement Defines Upgrades on Scrubber Screens, in Proceedings 13th AusIMM Mill Operators’ Conference 2016, pp 285–290 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Oct 10, 2016

By McCarthy P. L

A distinctive feature of the goldfields of Victoria was the extrac- tion of gold from deep leads, that is the buried river beds of Vic- toria's ancient rivers and streams. It is estimated that about 265,000 kg of gold was produced from Victoria's deep lead mines which comprises about 11.5% of Victoria's total production of gold (Bowen, 1974). The significance of deep lead mining for Victoria, however, went far beyond its economic contribution to Victoria. If Profes- sor Blainey is correct it was the frustrations of mining gold from deep alluvial leads in Ballarat during 1854 which precipitated the Eureka Stockade (Blainey, 1963, 46-52). This event resulted in the implementation of a fair mining administration and was an emphatic statement of the rise of democratic movements in Australia. Much of the technology and skill for mining deep leads had to be developed locally because at that time no other major gold- field elsewhere in Australia or the world had gold deposits with comparable problems. Deep lead mining in Victoria was there- fore largely a home grown industry and the equipment for that industry was often designed and produced in Victoria.

Jan 1, 1988

The Ramu chromite deposit occurs in the Marum Ophiolite complex and is the most economically attractive chrom-ite deposit in Papua New Guinea. Its lateritic nickel, chromite and cobalt potential has attracted several compan-ies to prospect the deposit.In the present work, the compositions of chromite in the Ramu lateritic deposit and coexisting olivine-chromite pairs in Marum Ophiolite dunite were analysed with the electron microprobe for Fe, Mg, Cr and Al. The results were used to determine the relationship between the cations in the tetrahedral and octahedral structures of the chromite. In addition, the Fe, Mg, Cr and Al cations of the coexisting olivine-chromite pairs were used to calculate the equilibrated temperatures of crystallisation of the chromite. The variation of Fe", Mg and Cr cation values of the chromite in relation to the calculated temperatures was studied by regression analysis.

Jan 1, 1994

By Rankin W. J

Increasing concern with the emission of sulphur dioxide from smelters and roasters has caused renewed interest in processes which can use waste sulphur dioxide, such as the sulphation of nickel laterite ores. The process described here proposes to by-pass the production of sulphuric acid and react laterite directly with a sulphur dioxide containing atmosphere. A thermodynamic analysis identified operating windows in which nickel sulphate forms while iron oxide (the major impurity in most laterite ores) remains stable. The initial assumptions included unit activity of all species except nickel oxide. The lowest possible nickel oxide activity (while maintaining selectivity) increased with increasing temperature, indicating that selective sulphation is favoured by low temperatures. The temperature of interest was found to be between 500 and 800¦C. Calculations show that a feed gas containing ten per cent SO2, five per cent 02, balance N2 requires a temperature greater than 650¦C for selective sulphation of nickel. Laboratory experiments showed that the assumption of unit activity of ferric sulphate was unrealistic above about 680¦C due most likely to the formation of solid solutions which decreased the ferric sulphate activity. Results are presented which illustrate the limiting equilibrium sulphur trioxide partial pressures at 700 and 730¦C below which selective sulphation occurs. Cobalt extraction was usually between 80 and 95 per cent under conditions yielding selective sulphation, whilst nickel extraction was about 50 to 75 per cent depending on temperature and choice of upper limit of iron extraction. An operating diagram is presented for a limonite ore and shows that the optimum reaction conditions are 680¦C and an input gas containing 20 per cent SO2. Under these conditions nickel, cobalt and iron extractions are 73, 95 and two per cent respectively.

Jan 1, 1996

Comalco Limited has recently completed construction of a $50 million kaolin plant at the site of its bauxite mining and industrial minerals operations at Weipa. The plant will produce 100,000 tonnes per annum of coating grade kaolin for the paper industry.Comalco produced the first coating kaolin from the deposit in 1979 on a trial basis. Since then a variety of quality coating grades with specific particle ize distributions and brightness values have been prepared.Extensive drilling and bulk sampling of the deposit over eight years has shown that the orebody is large and of a high grade suitable for the production of premium quality coating kaolins.The processing plant technology was developed by Comalco in association with the European kaolin and equipment producer Amberger Kaolinwerke GmbH (AKW).The Weipa kaolin plant is the first of this size to be built in the Pacific Basin region and it will offer the region's paper-coating mills a stable and reliable source of high-quality kaolin, shipped from an established bulk loading port. The paper provides an overview of the development of the kaolin investment, the nature of the production process and details the project management procedure used for the design, construction and commissioning of the plant. Three areas of significant interest, the gas turbine fired pray dryer, the moving bridge shiploader and the use of aerobelt conveyors on the project are detailed.

Jan 1, 1988

By M Paakkunainen

Sampling is often the most critical part in process analysis. When the mean of a continuous lot, such as a process stream within a given time interval, is estimated by calculating the mean of several samples, the uncertainty of the estimated mean depends usually on the sampling strategy. Three different strategies can be used: systematic, stratified or random sample selection. The standard deviation of the lot mean is different for these methods so that systematic sampling usually gives the smallest and random sampling the largest standard deviation. Pierre Gy developed a method where the sampling errors of one-dimensional lots for these three strategies can be estimated from a variogram, which is calculated from a variographic experiment, ie from a set of one-dimensional time series measurements with fixed sampling interval. While variogram is an excellent tool for characterising and displaying the variability of autocorrelated processes as function of time, the sampling error estimation from it is quite laborious, however. In this work an alternative method for estimating the sampling errors was developed. The process is divided into strata of equal sizes, varying the length of strata similarly to variographic analysis. For stratified sampling the standard deviation estimates are obtained by analysis of variance and for systematic sampling by fitting a linear regression line to each stratum and calculating the residual variances. By pooling the individual variance estimates the variance estimates that are corrected for autocorrelation are obtained. The new method was tested with simulated and real data sets having periodic, random and/or drift fluctuations. For stationary processes the results agreed well with the results of the GyÆs variographic method. The method can probably be generalised to estimate the sampling variance of higher-dimensional lots.

Jan 1, 2005

By Kwitko G

Exploration for coal has been on-going in South Australia for the past 100 years. During this period substantial resources of low rank coal have been delineated throughout the State. These deposits are of variable quality often with high moisture, sodium, chlorine, sulphur and ash content and although generally regarded as suitable for use in conventional pulverised fuel boilers, many are difficult to utilise. The only operating coal mine in South Australia is at Leigh Creek where coal bearing shale was discovered by chance in 1888 during excavation of a railway dam near the township of Copley. Leigh Creek has had a very diverse mining history from the initial small scale underground mining through to open-cut mining utilising draglines and more recently large shovels and trucks.

Jan 1, 1992

By Barro L

There is currently a world wide interest in coal-oil technology as the search continues for alternative energy sources to reduce the consumption of petroleum crude. An important aspect of this coal-oil technology study is to obtain information on the flow properties of coal-oil slurries. While some work has been reported on the flow behaviour of black coal-oil suspensions, very little work on brown coal-oil suspensions has been reported. In this paper flow charac- teristics of brown coal-oil suspensions for various coal concentration and temperatures have been presented. A Capillary rheometer, designed to handle settling suspension, has been used for deter- mining rheological properties. Brown coal of 0 0725 mm average particle diameter has been used in this work. The oil was a coal derived product having a boiling point range of 234¦- 319¦C, Apparent viscosity of all suspensions was found to increase on storage due to ageing. Ageing might have occurred due to physico- chemical interactions between coal and oil. Flow behaviour of some suspensions changed from Newtonian to non-Newtonian on storage.

Jan 1, 1980

By Aspinall T. O, Just G. D

Computer software systems have been developed to assist in a wide range of specific mine planning and scheduling applications. In selecting appropriate systems for any mining operation it is apparent that certain features have particular advantages for each mine site. The ideal solution to this problem is to select a range of systems which best relate to sections of each mining operation. This approach raises potential data linking difficulties where output from one system is incompatible with input requirements for other systems. A study at the University of Queensland investigated the problems related to the integration of a number of mine planning and scheduling software systems. The project used data from large scale coal strip mining operations in Central Queensland. Two major computer packages used extensively in the study were the SURPAC mine planning and XPAC mine scheduling systems. Dragline and truck and shovel operations were analysed in the project. Results of the work have been directly applied at the mine site to assist current strip design by effectively automating the design procedure. This enabled sensitivity studies to determine the effects of changing dragline working levels and varying pit dimensions. Coal blending studies and procedures to optimise operations have been investigated using linear programming within a spreadsheet software application. Output from the SURPAC and XPAC programs was directly linked to the linear program for this analysis. The simulation program GPSS/PC was also used in a similar manner to assess optimisation parameters.

Jan 1, 1992

By Stump NW

Until a year ago all isotope on-stream analysis utilised flow cells similar to those designed for conventional X-ray on-stream analysis. These systems incorporated a fairly complex sampling system necessary to present a representa- tive air-free sample of the main process to the flow cell. Maintenance costs and capital costs associated with flow cells and sampling systems have been generally high. Costs can be greatly reduced and reliability greatly increased, by using isotopes incorporated in immersible on-stream analysis probes which actually dip into the main process stream eliminating the need for sampling. A bonus of other advantages associated with immersible probes includes temperature stability and ease of calibration. This paper discusses details and results of the probe systems, justifica- tion for installing on-stream analysis, comparison of conventional X-ray and isotope techniques, and a brief survey of methods of analysis using radio- isotopes in on-stream elemental determinations.

Jan 1, 1971

By Muller GP, van Deventer JSJ

A mineralogical analysis has shown that in the Hartebeesfontein ore studied, uranium is associated mainly with uraninite, sulphides such as pyrite and to a lesser degree carbonaceous material such as thucolite. Little could be learned from the literature regarding the mechanism of flotation of these uranium-bearing minerals. A wide variety of reagents were used so that conditions enhancing the flotation of either the sulphides, carbonaceous material, oxides like uraninite, or combinations thereof, were created. As could be expected, the xanthate based floats gave-better selective recovery of sulphides than oleic acid. A substantial fraction of the uranium is associated with pyrite, so that addition of oleic acid to a xanthate float did not enhance the recovery or grade of uranium. After a pre-leach with sulphuric acid in which the pH and Eh were controlled so as to destroy the uraninite, higher uranium recoveries were obtained for the combined float (xanthate, DTP and oleic) and the DTP float. This was most evident when iron was added before flotation. Roasting, which destroyed the sulphides and thucolite, caused a significant decrease in uranium recoveries. The uranium liberated in this way was obviously not flotable in the same way as the uranium liberated from uraninite. A small amount of iron (2 kg/t) added before milling resulted in slightly higher grades and recoveries of sulphur for xanthate based floats. Higher iron additions had a detrimental effect on sulphur recoveries. Even in the case of oleic acid the addition of small amounts of iron had a positive effect on the recovery of sulphur and uranium.

Jan 1, 1993

By Crawford G. R, Wold M. B

The application of the hydraulic fracturing technique to the measurement of in situ rock stress from underground excavation is discussed; including relevant theoretical considerations, equipmenl details, experimental technique and analysis procedures. Examples of the application of the technique at three Australian coal and metalliferous mining operations are given. The results obtained from these applications are compared with corresponding results obtained from overcoring tests conducted in close proximity at each site. Generally good correspondence in a wide variety of rock types is indicated. Experience gained with hydraulic fracturing at several underground mining sites has indicated it to be a quick, cost effective means of gaining an understanding of the in situ stress field in sufficient detail for many mine planning functions.

Jan 1, 1990

By Bothe C

Froth flotation processes use different surface properties of the minerals to be sorted. In an aqueous environment the hydrophobic mineral attaches selectively to air bubbles and is lifted to the surface of a separation vessel, while the tailings settle towards its bottom. Besides the surface properties, the hydrodynamic conditions play an important role. With respect to the hydrodynamics the flotation process can be divided, for simplicity, in two sub-processes. The attachment of hydrophobic particles to air bubbles, the so-called mineralisation, demands a large number of collisions and therefore high turbulences. The phase separation however needs a deterministic movement of both the particle-bubbles-aggregates and the tailings particles and therefore a quiescent flow field. The optimisation of the overall process requires a separation of both sub-processes, especially when fine particles have to be sorted. In conventional mechanically agitated flotation cells both sub-processes take place in the same turbulent volume. For this reason they suffer from a decreasing selectivity with decreasing particle size. In flotation columns the mineralisation of air bubbles and the phase separation are performed in a quiescent environment. This results in high concentrate grades and at the same time in a very slow attachment kinetics, which must, especially for fine particles, be counterbalanced by a long residence time of the slurry.

Jan 1, 1993

By P Breuer, A Simons

The sulfidisation, acidification, recycle and thickening (SART) process is currently being used at NewcrestÆs Telfer Gold Mine to recover cyanide and copper from the cyanidation tails of the pyrite concentrate carbon-in-leach (CIL) process. While the process has been effective at attaining high recoveries of cyanide and copper, the Telfer SART plant has experienced higher than expected sulfide additions to achieve these recoveries. This paper details the results of surveys on the Telfer SART plant, which show that residence time appears to be causing the high sulfide consumptions. The paper also details the results of laboratory scale experiments which confirm the observed residence time impact during the acidified stage of SART.CITATION:Simons, A and Breuer, P, 2013. The impact of residence time on copper recovery in Telfer Gold MineÆs cyanide recycling process, in Proceedings World Gold 2013 , pp 189-196 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Sep 26, 2013

By Qi P. H

Gold dissolution can be achieved with a number of complexing ligands, all with varying degrees of stability. Processes based on the use of halogens have been known for many years. Beside providing the necessary complex- ing role, the halogens under the appropriate conditions are very effective oxidants for gold. Of the halogens, the gold iodide complexes are the most stable in aqueous solution. Iodine can establish the desired oxidation poten- tial for oxidizing gold, and unlike chlorine and bromine, the oxidizing potential of iodine is mild enough to avoid the oxidation of impurity constituents like metal sulfides. A series of experiments to investigate the fundamental electrochemistry of gold in different halide solutions was performed. Cyclic voltammograms of gold in the presence of 10-2 M chloride, bromide and iodide, respectively show that for a given potential the rate of oxidation is much faster in iodide solution than in either chloride or bromide. An overlay of linear sweep voltammograms for the anodic oxidation of gold in iodide and the cathodic reduction of iodine species on gold provides an effective method for examining the dissolution of gold in iodideftodine solution. The dissolution rates obtained from both electrochemical and actual leaching results are compared. Optimum leaching conditions are analyzed in terms of the iodide/iodine concentrations. Conceptual processes for the recovery of gold and iodide and the regeneration of iodine are discussed.

Jan 1, 1991

A critical appraisal of the wide variety of processes used in the pyrometallurgical production of metals and non-metals shows that there is a strong physico-chemical and, in particular thermodynamic, basis for the variety. Based on this, a simple classif- ication scheme has been developed which makes it possible to understand the methods for extracting individual metals and non-metals pyrometallurgically and to assess which are the more attractive routes. The analysis presented shows why there are essentially two broad routes for pyrometallurgical production of metals and non-metals; viz., the reduce- refine and the refine-reduce routes. Halides have the role in pyrometall- urgical processing of producing pure compounds for subsequent reduction. The criteria which determine the selection of reduction method for oxide raw materials and intermediate halides (e.g., use of carbon, hydrogen, a more reactive metal or electrowinning) are examined critically in the paper. The treatment of sulfide raw materials is considered also, particularly the criterion for smelting sulfides directly to the metal.

Jan 1, 1987

By J S. J van Deventer, D C. Shallcross

New developments are taking place in the recovery of gold from leached pulps that are based upon the adsorption of the metal cyanide species onto ion exchange resins. Despite the success of several resin-in-pulp pilot plant operations in the Western World and large-scale plants in the former Soviet Union, the process is yet to gain recognition as a viable alternative to the carbon-in-pulp process. An experimental research program has investigated the use of a variety of different types of resins for the recovery of gold, but to-date no resin studied has the desired properties of high selective loading capacity for gold cyanide and a simple inexpensive elution procedure. In addition very little is known concerning the physical strength of resins and their ability to resist shattering due to osmotic shock during cycles of adsorption and elution. The ability of ion exchange resins to enhance the leaching of refractory and re-adsorbing ores has not been investigated. This paper highlights the necessary factors that need to be addressed before commercialisation of ion exchange technology for gold extraction is feasible.

Jan 1, 1998

By Blockley J. G, Laeter J. R

The history of the Ph-Cu-Zn mineralisation in the orthampton Block of Western Australia has been further investigated. It was hoped that (1) Rh-Sr studies on partially-remelled granulites, wall-rocks to the dolerite dykes, should date the dolerite intrusion, (2) Rh-Sr data on hydrothermally-altered dolerite should date the sulphide mineralisation, (3) Pb model ages on the galenas might provide an independent dating of the mineralisation, in addition to any geochemical information that might be derived. Only the second dating aim was fulfilled, but the Pb isotope data, when combined with the Rh-Sr data, have permitted deductions about U, Th and Pb abundance changes during the regional metamorphism, and about a possible source of the ore Pb. In detail the following has been found. (1) The partially-remelted granulitic wall rocks yield a scattered whole-rock Rh-Sr isochron which seems not to have been reset by the dyke intrusion (age 1037 ± 146 Ma, with initial Sr ratio 0.7171 ± 0·0054, MSWD = 111). This date agrees well with that reported previously for granulites from another locality; together theyestablish the time the metamorphic period closed. (2) The hydrothermally-altered dolerites yield a Rh-Sr whole-rock date 434 ± 16 Ma, with initial Sr ratio 0.7072 ± 0·0029 and MSWD = 31, taken as referring to the time of Ph-Zn mineralisation. This contrasts with a report of much older palaeomagnetic and K-Ar datings of the dolerite (not less than 550 Ma, possibly older) and suggests that neither the dolerites nor their heat have had any connection with the mobilisation of the Pbscavenging solutions. (3) The Pb isotope ratios of galenas from the ores yield a well-correlated regression which is not amenable to any of the model-age calculations. (4) The Pb-isotopic trends negate any genetic connection between dolerite and mineralisation, but the country-rock granulites could be the Pb source. (5) Combination of the Rh-Sr dates and the Pb data in a "simultaneous isochrons" construct permits the inference of major losses from the system during the regional metamorphism, in the order U>Pb>Th, with substantial homogenisation of the remaining Pb. This left a wide range in local UlPb and Th/U among the source rocks which eventually were scavenged by the mineralising solutions. (6) These geochemical deductions are shown to be compatible with previously-published information on the abundance ofU and Th in the Northampton Block granulites, which are thus seen to be credible as source rocks for the ore lead.

Jan 1, 1985

By S Nkwanyana, I Govender

Batch experiments in a 0.6 m diameter mill have shown that improvements of about 13 per cent in the efficiency of energy utilisation can be realised in ball mills by replacing 25 per cent of the ball charge by an equivalent volume of cost-free critical size pebbles from AG/SAG mills. For a mill of a given size, speed and charge filling, the rate of size reduction of ore particles depends on (i) the frequency of grinding media collisions (ii) the probability of capture of ore particles between the colliding grinding media (iii) the probability of fracture of the captured particles. The probability of fracture depends on the magnitude of collision energy. The distribution of collision energy into shear and impact events determines the relative strengths of attrition breakage and impact breakage. The efficiency of energy utilisation depends on which of the two mechanisms of breakage is more desirable in a particular milling stage. In this paper collision data from a series of DEM simulations of a mill charged with steel media and a mixture of steel media and pebbles is presented in energy spectra and spatial distribution maps. The data provides the necessary detail to elucidate the improvements in the efficiency of energy utilisation in ball mills when using a mixture of pebbles and steel media.

Aug 24, 2022

By Bunting HR

Developments since 1959 in major excavators to meet the high outputs of overburden and coal under the changing nature of the Morwell Coal Deposits of the Latrobe Valley are described. Particular reference is made to investigations of designs of the bucket wheel head configurations for the digging of flat batters on high faces, and examples are given of the wide use ofmodelsin these studies.An explanation is given of considerations leading to selection of the Long Boom or the Compact type of bucket wheel excavator for various applications. The past decade has seen increasing manufacture in Australia of components for excavators and similar machines. The measures undertaken to integrate these components with those from overseas (Germany) are described. A section of the paper deals with advances in Electrical Engineering for large excavators in Australia and its interdependenee with mechanical design and construction. Finally, as an example of the versatility of the bucket wheel excavator a description is given of a recent application for the mining of mineral sands in Northern N.S.W.

Jan 1, 1970