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Natural Gas has been available in New Zealand for twenty years. During that time the gas share of the energy market has grown and now natural gas forms a significant part of New Zealand's energy scene, helping consumers to achieve a higher standard of living, and reducing dependence upon imported oil. Natural gas is now used for petrochemical manufacture and power generation in addition to direct supply to consumers. As concern for the environment continues to build, natural gas will have an increasingly important role to fill in these markets. This paper sets out the background to the development of natural gas in New Zealand and identifies the current markets. It then looks at those matters which are likely to influence the role of natural gas in the 1990s.

Jan 1, 1990

Plant-Based Trials of Monitoring of Coal Flotation Systems Using Electrical Impedance Spectrum Technique

Sep 13, 2010

Market forces, particularly iron ore prices, demand that plant operators achieve higher throughput in the worldÆs iron ore beneficiation plants without compromising yields or efficiency. This means that production cost per ton is of paramount importance and that all major pieces of Processing Equipment have come under close scrutiny to improve throughput at their most efficient performance levels and for the longest possible continuous running time. Without doubt the use of modern engineering standards and materials of construction has contributed to matching these throughput, efficiency and availability demands. However, often not enough attention is paid to the so called æinsignificant elementsÆ connecting this metallurgical equipment, such as chutes, pipes or other conveying systems, and particularly to the sufficient protection of their wearing surfaces. The result can be an unplanned and expensive outage caused by the wear related failure of such components. This paper will discuss:the theory of wear and the multiple factors of material and design that contribute to a reduction in wear; and the combinations of modern wear resistant materials available to todayÆs engineer and how, by intelligent selection and correct application, plant availability can be optimised. Examples outlining how these principles have been applied in South Africa showing some improvements leading to increased plant availability.

Jan 1, 2002

Development of Process for Beneficiation of Low-Grade Iron Ore Samples from Orissa, India The paper deals with the results of characterisation and beneficiations studies undertaken on two low-grade Indian iron ore samples (IO-1 and IO-2) with a view to develop process for beneficiation of composite of the two samples to a high-grade concentrate, suitable for iron making through pelletisation. Indian iron ores contain relatively high iron but cost effective reduction of alumina within the specified limits has been a challenging task. Characterisation of the samples revealed the ore to be laminated and fine grained with hematite as the major mineral. Clay is the dominating gangue in most of the ore pieces followed by silica. Occasionally goethite and quartz/jasper were recorded. Clay occurs either as patches within the hematite mass or as cavity/fracture fillings. Liberation studies on the representative samples crushed to 2 mm indicated that around 95 per cent of the grains are liberated below 105 micron. Beneficiation of the two individual samples and their composite based on gravity and magnetic separation techniques resulted in products with varying yield and grade of the products. The effects of various process parameters were studied. Granulometry of the feed was observed to be important for improving quality of concentrate. The results of bench-scale studies were validated through pilot-scale continuous trials. Based on the studies undertaken a suitable process was developed for beneficiation of the composite sample, comprising 60 per cent IO-1 and 40 per cent IO-2, to a high-grade product assaying over 65 per cent Fe and material balance was computed. A commercial plant for beneficiation of low-grade iron ore to produce DRI pellet grade concentrate is proposed to be installed.

Sep 13, 2010

The results of precious metal exploration carried out by Amoco Minerals New Zealand Limited over EL 33-137 in the Longwood Range, Southland, are described. Widespread gold and platinum in alluvial deposits on the perimeter of the range and anomalous gold in stream sediments on its southern and south western flanks indicates that the precious metals were probably derived from erosion of the mafic rocks of the Longwood Complex.

Jan 1, 1983

By Moresby J. F

Segregation roasting was used to recover more than 85 per cent of copper from crushed, minus 14 mesh refractory furnace-lining bricks. A plus 14 mesh fraction: which was high in copper, could be recycled directly to the smelter, giving an overall recovery of approximately 90 per cent. An oxidation roast at about 700°C was necessary, before segregation roasting, to convert copper sulphides and copper metal to sulphates and oxides. Withsegregatron temperatures in the range 600°-650°C the quantities of solid carbon and NaCI required are 2-5 per cent and 1 per cent respectively. P.V.C. coating from scrap copper wire can be used instead of NaCl as asource of hydrogen chloride for the segregation reaction.

Jan 1, 1978

On the Hauraki goldfields, within the limits of Cape Colville Peninsula, the Paheozoic rocks are confined to the district north of a line drawn from Mercury Bay on the east coast to Rocky Point on the shore of the Frith of Thames. South of Kennedy's Bay they are developed on the east coast only at Kuaotunu, at which place gold mining is carried on in sandstones and slates of this age. Between Tapu Creek and Coromandel there is, along and adjacent to the shore of the gulf, a very considerable development of PaJreozoic and in part of Trias rocks, and between the Tiki Stream and the northern end of Tokatea Hill, along the western slope of the main range, lies the special area of the Palreozoic or carboniferous rocks that have more particularly to be dealt with in this paper. The same formation has a large devolpment between Cabbage Bay and the northern slopes of Moehau, and appears to the water marge on both sides of this part of the peninsula.In this part they are of special interest as having, on the west spur of Moehau, a considerable variety of dyke rocks intruded into the sedimentaries, the interest in which is increased by the fact that these dykes theIllselves are of Palreozoic age and correspond to the dykes that are so' abundant in the Tokatea-Tiki area. It is this Tokatea-Tiki area as a goldfield, and its rocks as distinguished from later volcanic' products' on other parts 'of the peninsula...

Jan 1, 1903

An account is given of experimental apparatus for generating a short duration high velocity water jet and the effect of its impingement on various rock samples under air or water cover. The penetration was found to be highly dependent upon the rock structure; in general material with closely interlocking grains was resistant.The damage sustained by a stationary sample held close to the jet did not vary greatly whether the sample was in air or confined under a water layer; but when the sample was translated under the jet there was a marked increase in the damage sustained.Some consideration was given to the possible practical application of a water jet for deep hole drilling and an estimate made of the power requirements and transmission losses for such a system.

Jan 1, 1969

By K Niyomjinda, B Etschmann

Chatree Gold Mine is currently the only modern day gold mine operating in Thailand, and is situated approximately equidistant from Chiang Mai in the north and Bangkok in the south. Environmental guidelines set by the Thai authorities require Chatree Gold Mine to achieve a Total Cyanide level of 20 ppm or less in the process plant discharge slurry stream prior to release into the tailings storage facility. This paper describes both the initial difficulties faced in achieving compliance on this limit utilising the conventional INCO SO2/Air cyanide destruction system and the subsequent process improvements initiated to both the leaching process and the standard INCO process to achieve the current compliance levels of approximately 99/100 shifts. Improvements were focussed on the dual aspects of reducing the formation of WAD cyanide and ferrocyanide species in the leaching circuit coupled with process changes to improve removal of the ferrocyanide species from solution during the cyanide reduction stage.

Jan 1, 2004

The recovery by flotation of some complex uranium minerals such as brannerite and davidite is described. Anionic reagents used for flotation of iron and titanium oxides' are suitable. If care is taken, to emulsify the reagents the slime fractions may be satisfactorilytreated.INTRODUCTIONUranium ores are usually treated by direct leaching with acid or alkali according to the nature of the gangue materials. Concentration of the uranium minerals prior to leaching is not commonly practised because of the earthy nature of most uranium minerals and the difficult mineral dressing problem they pose. Some of the harder complex oxides such as davidite and brannerite are amenable to flotation. This is fortunate since they usually require an expensive, strong acid treat~ent to dissolve the uranium. Flotation tests were commenced in 1949 by officers of the South Australian Department of Mines stationed at Adelaide, first in the School of Mines, then in the University of Adelaide and finally in Departmental mineral dressing laboratories at Thebarton. Separation of daviditefrom Radium Hill and Mount Victoria ores, brannerite from Crocker's Well ore, and secondary uranium minerals from Myponga ore was attempted.The development of the flotation reagents to separate the oxides from silica and the silicates is first described, then some of the results obtained are presented as tables.DEVELOPMENT OF FLOTATION REAGENTSThe davidite at Radium Hill is associated with iron and titanium oxides, qu;a,rtz and biotite as replacement deposits in shears. The davidite, rutile,' ilmenite and hematite usually occur in segregations from nut size to masses of several pounds. They are associated as a complexity of...

Jan 1, 1955

Several factors contributing to the loss of fibre during treatment are a function of the paragenesis of the veins. The occurrence, of magnetite from the cap rock within the veins prevents complete fiberization. There is a marked similarity between these veins and those in the Koegas-Westerberg area of South Africa.INTRODUCTIONAn investigation of the mineralogy of the Wittenoom Gorge crocidolite veins was undertaken in the latter part of 1962 at the request of the Colonial Sugar Refining Co. Ltd. It was anticipated that such a study might reveal the cause or causes of the lack of recovery of some asbestos during beneficiation. Some interesting features of the mineralogy and paragenesis of the crocidolite veins become apparent, but it is emphasized that the investigation is far from complete, as the study did not extend to the field occurrence.The samples examined were selected from the mill and from the untreated ore.GEOLOGICAL SETTINGWittenoom Gorge is situated on the Fortescue River in the Hammersley Ranges of Western Australia and is one of several gorges in these ranges, on the sides of which 'crocidoIite asbestos is known to occur. The Hammersley, Ranges consist essentially of a series of quartzites, shales, ferruginous quartzites and dolomites. These' rocks are part of the Nullagine Formation (Proterozoic) and are usually either horizontal or gently folded. In some 'areas small beds of riebeckite as well as crocidolite are known to occur interbedded in the sequence.Riebeckite is a monoclinic amphibole, the formula of which may be stated as Na2Fe2"Fe2" (OH) 2Si8O22, and crocidolite is a fibrous variety of this mineral. This formula...

Jan 1, 1963

By J L. Merritt

Effective minesite water management requires that this issue be treated as a risk management exercise. The management process is generally far from simple and by necessity must involve a range of personnel covering a siteÆs commercial, operational and environmental interests and responsibilities. The challenge to be collectively faced by these stakeholders is to strike the correct balance between risk and cost. On the other hand, the challenge to be faced by technical services support personnel is to provide stakeholders with information in a format that they can use with confidence. This paper presents the application of continuous operational simulation (OPSIM) modelling techniques to establish appropriate risk profiles for minesite operations. It is necessary that the format of these risk profiles be generic and equally applicable for defining the risk of occurrence for a relatively comprehensive range of activities û eg from of a non-compliant discharge, to the risk of failure to meet production targets. What is more, the profiles need to be quantitatively based and capable of reflecting change in system response to varied operational or management strategies. The techniques presented in this paper are based around a key assumption that long-term records of the climate contain within them sets of sequences that are representative of what can be expected in the future û that is, the droughts, floods, cyclones, good years and bad, long or short, and everything in between. Therefore, if these historical records are run through an OPSIM model for a particular site, then the simulated operational characteristics can be taken as being representative of what can be expected in the future, in the long-term. This lends itself to statistical analysis and translation into the required risk based format. Water Solutions Pty Ltd have been working with Capricorn Coal Management to develop a relatively comprehensive OPSIM model of their operations at German Creek Mine, Central Queensland. Outcomes from the modelling have been used in recent times to provide mine management with risk-based guidelines for both securing and containing mine water inventories. One of the more interesting tasks has been to establish risk based inventory levels that, if reached, would trigger the immediate implementation of a contract for the desalination and re-use of mine water, at predefined rates. Also, lead-time warning of the occurrence of a possible trigger is of importance to operational and commercial planning. To service this requirement the OPSIM model is regularly used to produce lead-time estimates to defined levels of confidence. Case studies of these, and other, applications of the OPSIM model at German Creek Mine are presented in this paper and serve to demonstrate an effective methodology for practical risked based water management.

Jan 1, 2003

By J A. Rumball

Measuring cyanide in the leach liquors associated with high copper and/or sulfide ores is a non-trivial exercise. It is well known that copper complexes with cyanide and reduces the amount of cyanide available for gold leaching. What is not so well known is that the rhodanine end point overestimates the amount of cyanide available for leaching in the presence of copper. Sulfide ions also interfere with a rhodanine end point titration, although this is less of a problem as the black silver sulfide precipitate formed clearly indicates to the operator that something is wrong. Thiosulfate, which forms readily from the alkaline oxidation of sulfides, causes an overestimation of the cyanide available for leaching due to the formation of Ag(S2O3)-. The net result of these observations is that rhodanine is rarely of value as an end point indicator in complex solutions. It generally overestimates the amount of cyanide available, providing plant metallurgists with a false sense of security. Potentiometric titrations are generally much more capable of accurately measuring cyanide in complex solutions. The interfering effect of copper can be resolved and it is even possible to estimate the copper concentration using the inflexions associated with the titration of CN- + Cu(CN)43- versus Cu(CN)32-. Using the potentiometric method sulfide ions can be determined before the cyanide measurement is made due to the formation of AgS2, although the electrode will foul with repeated measurements. Thiosulfate can also be distinguished from cyanide with a potentiometric titration. Rhodanine and potentiometric titrations are both affected by the pH of the liquor. At pH 9.2 half the cyanide will be present as CN- and half as HCN(aq) with only the CN- being titratable. This does not hold in the presence of a buffer active around pH 9. In the presence of sufficient buffer, both the CN- and HCN(aq) are titrated. Ca(OH)+ may buffer the pH when large amounts of lime have been added.

Jan 1, 2007

By J H. Park, M J. Lee

Because the environmental problems are occurred by greenhouse gases such as CO2, the industries have tried to increase electric motor efficiency to reduce CO2 emissions. A core material of electric motor is high-silicon electrical steel. The ferrosilicon (FeSi) alloy, a raw material for the production of electrical steel, affects the electric properties of silicon steel. The main impurities such as Ca, Al and Ti make inclusions or precipitates that causes core loss. The slag treatment has been widely used to remove impurity elements. Thermodynamic principles for the refining of several impurities, specifically Ca and Al, have been investigated, whereas thermodynamic behaviour of Ti has not been fully understood yet. Therefore, in the present study, the titanium distribution ratio () between ferrosilicon and CaO-SiO2-Al2O3 slag system at 1773 K was investigated. The results show that is influenced by both the basicity and stability of titanium ion in the slag. Specifically, exhibits a minimum value at about C/S=0.7 indicating a shift in the titanate structure unit from [TiO5]-square pyramid to [TiO4]-tetrahedron because of lack of Ca2+ ions in a C/S<0.8 region, contributing to an increase in titanate capacity and .

Jun 19, 2024

The discussion which followed the publication of my paper by the formert has, I think, enhanced its value. It may therefore be of interest to members of our Australasian Institute, who are not members of the Institution of Mining and Metallurgy, if I give a synopsis of the discussion.My attention was drawn to the fact that my paper did not make clear the extent of the improvement in furnace operations, which followed the use of coke of high quality; this comment applied more particularly to the lead content of slag. My failure to supply comparative figures in regard to the lead content of slag was governed by a condition which, I think, is of interest to metallurgists. As a result of industrial...

Jan 1, 1932

By Hayward P. G

Complex ores, characterised by intimate intergrowths between minerals, have previously been treated by flotation with limited success. The most common problem has been that the liberation size is often finer than the lower size limit for selection flotation. A technique has been developed in which the problem is overcome by the use of a selective agglomeration procedure in which the values are coalesced with oil to a size suitable for flotation prior to introduction into the flotation machine. A complex lead ore was characterised by QEM*SEM mineralogy as having a mean galena liberation size of 15 ¦m. The best recovery of lead at 50 per cent Pb grade by standard flotation was 53 per cent. After application of the procedure, 86 per cent recovery was obtained after a single cleaner step. The oil functions as a bridging liquid in the presence of conventional collectors which render the mineral oleophillic.

Jan 1, 1991

By O Tiili, A Dixon

Many minerals processing plants need to have greater efficiency in current times and optimise their process performance in order to maintain high profitability. This is even more so in the current economic climate. In the case of large flotation cells, such as TankCell«-300 with over 300 m3 active capacity, ensuring consistent operation and optimal flotation conditions is particularly critical, given the high impact on overall process and throughput of such cells. As there are fewer cells to control and monitor, there is also a lower initial capital cost for instrumentation - the requirements, however, are higher. Despite such compelling reasons, instrumentation and basic control in flotation cells has not changed much in recent years. The standard is still to use traditional feedback (PI algorithm) controls for slurry level and flotation air. A new advanced instrumentation and control package for large flotation cells has recently been developed by Outotec and has been installed at Macraes.In addition to the standard basic instrumentation and control, the new system at Macraes consists of a froth image analysis system, a froth velocity control, and a level control system which utilises adaptive feedforward compensation. There are three TankCell«-300 cells in operation at Macraes since November 2007 and the new control system was commissioned in December 2007.The paper will include comparative data from pre- and postsystem installation and discusses benefits including optimised recovery, improved performance, as well as ease of operation.

Jan 1, 2009

The criterion for assessing the accuracy of coal reserve estimates proposed by Philip and Watson (1982) is criticized.Following Royle (1977), it is suggested that the global estimation variance found by geostatistical methods is more appropriate.This method is applied to coal data from the Bowen Basin. This shows that two factors (the inherent variability of the variable under study and the total number of drill holes) have more influence over the accuracy of the reserve estimate than the form of the drilling pattern. Comparisons between the relative errors for different sized regions demonstrate that the spacing between drill holes is of secondary importance. The dominant factor is the total number of holes.Comparisons between the relative errors show that some variables such as sulphur need a much denser sampling than the others to obtain the same level of precision.

Jan 1, 1983

The Nena high sulphidation-type copper-gold deposit is composed of andesitic pyroclastic units with minor interstratified lava flows. Epiclastic sandstone and conglomerate, and siliciclastic rocks consisting of mudstone, shale, lithic and bioclastic sandstone and conglomerate are locally present. Pre-mineral diorite intruded and domed the volcano-siliciclastic sequence. Economic copper-gold is hosted by vuggy quartz altered lapilli tuff and tuff breccia. The early hydrothermal alteration stage involved deposition of epithermal banded quartz and chalcedonic silica in localised environments. This alteration stage was locally superimposed by a hydrothermal breccia event. Following the breccia event, magmatically-derived volatiles were channelled through a NW striking dilational fault zone and generated the high sulphidation alteration. The high sulphidation alteration is zoned from a vuggy quartz core with local massive replacement silica through a broad pyritic quartz-alunite halo and finally to a thin illite-smectite zone. This is surrounded by regional chlorite-epidote-smectite alteration. A gangue mineral phase consisting of quartz, alunite and baryte overprinted the zoned high sulphidation alteration and preceded the main copper-gold-arsenic mineralisation. Early sulphide deposition is characterised by marcasite, arsenical pyrite and melnicovenite. Main-stage copper-gold mineralisation involved sequential deposition of hypogene bladed covellite+chalcocite, enargite-luzonite and luzonite+stibioluzonite respectively. The copper sulphides are zoned from bladed covellite-chalcocite in the north (cross-sections 5000 - 5600 N) through enargite-luzonite (cross-sections 4700 - 5000 N) and to luzonite????stibioluzonite in the south (cross-sections 4400 - 4700 N). A late phase of minor acicular covellite and enargite+luzonite overprinted the zoned copper sulphides and associated gold mineralisation. Gold mineralisation commenced at the transition from enargite to luzonite, and continued through the deposition of luzonite-stibioluzonite in both stages. Most gold was deposited during the main-stage mineralisation. Yellow native sulphur was deposited in the remaining vugs and defines the waning stage of the hydrothermal system. Post-mineral dioritic intrusives and feldspar porphyries intruded the volcano-siliciclastic sequence. Finally, supergene chemical processes with associated erosion and uplift generated a 40 - 50 m thick oxide-hosted gold cap. The oxide gold cap is underlain by a 35 - 45 m thick blanket of supergene chalcocite+covellite mineralisation which overlies and occurs throughout the main hypogene copper-gold zone. Supergene gold is related to the distribution of primary gold-bearing sulphides. Therefore, remobilisation and redeposition of gold are considered to be insignificant and very localised.

Jan 1, 1999

By S H. Hyun, J W. Cho

Jun 19, 2024