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By Haukka M. T

A new low-dilution fusion method which has been successfully used for accurate determination of the major oxide components of silicate rocks, is applicable to rapid, accurate determination of trace or minor eiements in mineral exploration samples. Limit of detection is in many cases less than 5 ppm. Either rapid, approximate measurement and calculation methods (suitable for geochemical exploration), or more accurate methods (applicable to orebody evaluation studies) may be used.Rapid methods are described for nickel in rocks and sulphides containing 10 ppm to >2 per cent Ni, and for gallium. The rarely-determined element gallium is an example of a constituent which may be easily investigatedby XRF using the LiB02 fusion disc, which is a permanent, easily-stored analytical sample available for later rapid or accurate analyses. The method is applicable to over 30 elements at levels encountered in mineral exploration.

Jan 1, 1978

By W Shamu

The mechanical properties of rock samples of identical lithologicalcomposition may vary significantly due to existence of materialdiscontinuities. Laboratory tests were carried out to determine the effect of material discontinuities on rock sample mechanical properties. The investigations consisted of detecting discontinuities, observing the failure mechanisms during uniaxial compressive strength tests, and analysing of the factors affecting the strength. A non-destructive testing method has been adopted to assist in thedetection of discontinuities. Laboratory testing proved that fractures leading to failures initiated on the detected discontinuities. The location, orientation, size, density and extent of the discontinuities contribute to different modes of failure and these affect the mechanical parameters of rock samples. Four modes of failure were distinguished for hard and brittlecylindrical rock samples. These modes were referred to as simple shear failure, multiple shear failure, multiple fracturing and vertical splitting. To evaluate the effect of discontinuities on mechanical parameters, the ratio of uniaxial compressive to tensile (Brazilian) strength was calculated and analysed for the different modes of failure. It was found that the value of the ratio depended on the mode of sample failure. The lowest value of the ratio was observed for shear mode of failure and the highest for vertical splitting mode of failure.

Jan 1, 1999

This method determines tellurium at concentrations down to 0·01 p.p.m., with geochemical accuracy. Tellurium is volatilized from the rock at 800°C in the presence of sulphur from decomposing pyrite, condensed, dissolved, and finally determined by atomic absorption in a long tube burner. The distribution of Te is shown near some gold lodes at Kalgoorlie. Lastly, a method of synthesizing Te-free pyrite from sulphur and ferrous sulphate is described.

Jan 1, 1969

By G D. Price

Scheelite mineralisation east of the main divide in' the Southern Alps of New Zealand was originally identified by Royden Thompson who is now a geologist with the NZ Geological Survey. This mineralisation was brought to the attention of CRA in 1978. Reconnaissance surveys were carried out in 1979 to delineate the extent of the mineralisation. This was undertaken using ultraviolet light examination of the sediments within the major drainages in the Southern Alps. This defined tentative zones of prospective mineralisation. As a result of this, preliminary reconnaissance, exploration licences were applied for -those areas in which indications of scheelite mineralisation were strongest. A total of 1737 km2 of ground was applied for within four exploration licences. These covered the main Southern Alps mountain chain between the Haast/Wanaka highway and the Mt Cook National Park.

Jan 1, 1983

Assessment of the Consistency Between Different Laboratory Froth Stability Measurements

Sep 13, 2010

Hatches Creek has been inactive since 1961, but with better metal prices, interest in the field is reviving.The mixed gravity concentrates which were unsalable in 1951 have been experimentally separated into salable wolfram, scheelite, and bismuth-gold concentrates, and a flow sheet incorporating magneticseparation and flotation has been developed.

Jan 1, 1965

Interest in industrial minerals in recent years has increased to such an extent that it has taken them into the mainstream of the Australian mineral industry. Notwithstanding that time series data on the values of production, exports, and imports show that industrial minerals are overshadowed by metals and energy minerals, their contribution to the national economy is important and more significant than would seem to be indicated by the statistics. Whereas the ex mine value of metals generally includes some processing (at least to a concentrate stage), most industrial minerals are valued at little more than their extraction cost, in addition to which such costs are generally low because most industrial minerals are exploited in low-cost surface operations. Consequently, values of mine production of metals and industrial minerals are not strictly comparable in that values of mine production of metals tend to be overstated Short term growth of the industrial minerals sector is assured because of several new projects already commissioned but not yet reflected in the statistics. Longer term growth is also assured, based on various other major projects that are likely to come on stream in the early to mid 1990s.

Jan 1, 1989

A consideration of mining ventures and the changes of an environmental nature that occur. The paper is introduced with a general statement claiming recognition that mining ventures are important to human well-being but that these need to be justified against the environmental changes that they bring about. The various factors that need to be considered are cited followed by an historical review of mining activities. The various environmental issues are discussed under three headings; socio-economic, physical and biological, prior to reviewing the world's demand for minerals including fossil fuels. In conclusion guidelines for appraising mining ventures relative to environmental changes that may occur, are given.

Jan 1, 1981

By V P. Elpatyevskaya, V S. Arzhanova

Main geochemical problems concerning the environment and mining industry interrelation are connected with the transformation of natural water chemistry by mining wastes. The investigation of many mines in Primorye, the southern part of the Russian Far East, showed that their mining waters have high concentrations of heavy metals and aluminium. Water acidity is primarily connected with the amount of acid-forming sulphide minerals in ores and also depends on the neutralising capacity of rocks. Considerable quantity of metals occur in the waters in dissolved form. Metal concentrations in mining waters exceeds the natural levels by two to five orders of magnitude and can't be reduced to the background levels even after multiple dilution. It is necessary to develop and put into practice new technologies so that to reduce the geochemical impact upon the environment.

Jan 1, 1995

A predicted increase in aluminium production and the possibility of a diminishing supply of petroleum coke for anode electrodes in alumina reduction cells makes it desirable to find alternative electrode materials. Browncoal char, with a lower ash content and with an elemental purity similar to petroleum coke, was produced by leaching in hydrochloric acid, washing with water, and charring at 1,150°C. The cost of processing is estimated tobe competitive with petroleum coke.Without further processing the bulk density and real density were undesirably low, but by briquetting the coal before charring and crushing, the bulk density was improved to 92 per cent of the petroleum coke value andthe particle density was improved to 92 per cent of the density of petroleum coke by water displacement or 75 per cent by mercury displacement.Pre-baked electrodes were prepared from the char alone, mixtures of petroleum coke and char, and from petroleum coke alone, all bonded with coal tar pitch.The electrodes were tested for the usual physical properties and were evaluated for performance in a laboratory size alumina reduction cell.Electrodes based on brown coal char alone were found to be inferior in physical properties and performance, but mixtures of the char and petroleum coke, despite poorer density, electrical resistivity, and carbon consumptionon a theoretical basis, in performance tests gave up to 17 per cent better carbon consumption per weight of aluminium produced and 21 per cent better electrical current efficiency than the electrodes based on petroleum,coke alone.It is suggested that larger scale tests are warranted.

Jan 1, 1971

By J M. Totterdell

The Permian-Triassic Bowen Basin and the Jurassic-Cretaceous Surat Basin evolved in a backarc tectonic setting behind an active convergent plate margin in eastern Gondwana. Several extensional (Early Permian; Eocene) and contractional (mid-Permian; Early Triassic; Middle-Late Triassic; early Late Cretaceous) intraplate deformational events are recognised in the basins. These can be correlated with similar events in the New England Orogen that was being deformed in the Late Permian-Late Triassic as a foreland thrust belt. The intraplate deformations were probably the consequence of plate interactions, including the accretion of terranes, at the ancient active plate margin, remnants of which now occur in New Zealand.

Jan 1, 1995

The lead concentration of flotation feed ore slurries is determined using two ?-ray absorption gauges mounted directly on a 6 in. diameter flotation feed pipeline. One gauge is a conventional "density" gauge using CS137. The other is a "lead-sensitive" gauge, which depends on the preferential absorption. by lead of 225 key y-rays resulting from Compton backscatter of CS137 y-rays.Gauge outputs are combined using an analogue computer the output signal of which is directly proportional to the lead concentration of the pulp. The accuracy of measurement of the pulp lead concentration is ± 3·6 per cent for ore slurries with lead concentrations in the range 0'07-0·16 g/c.c. and pulp densities 1.43-1.60 g/c.c.This paper sets out the development of the technique and details are given of the two experiments (1964, 1966) conducted in the plant at North Broken Hill Limited. The installation of the two-gauge system inthe plant during May 1968 is described. Details are given of the calibration technique used and the results obtained.

Jan 1, 1969

By Kennedy G. L

Experience is reporled in the operation of the pilot Lurgi carbonization plant at Morwell, afler it had been reconstructed to obtain better control of the heating of the briquettes in order to produce a strong char suitable for use as a metallurgical fuel. The theoretical Ideal Heating Cycle, which had been designed from earlier laboratory research, was closely approached in the carbonizer, and up to 97 per cent of the whole dried briquettes entering the carbonizer were recovered unbroken in the char.The strength of the char produced in the pilot plant was limited by the performance of the drier where the cracking and breakage of the briquettes was more severe. Theoretical studies have indicated that this limitation could be removed by using a hot briquette feed to the pilot plant. Experience indicates that with a hot briquette feed to the drier and with ideal heating in the carbonizer, hard char could be produced from Yallourn briquettes in continuous operation.The project has been terminated for economic reasons...

Jan 1, 1966

By J B. Gemmell, D R. Cooke

Recent mapping at the Kelian epithermal gold deposit in East Kalimantan, Indonesia has delineated intrusive and extrusive-phreatomagmatic breccias, their magmatic roots, and late-stage endogenous domes of a maar-diatreme complex. The Kelian epithermal system is characterised by a wide variety of mineralised and unmineralised breccias, which include tectonic, hydrothermal, phreatic and phreatomagmatic varieties. Phreatomagmatic breccias and associated igneous rocks post-date early stage alteration and mineralisation, and pre-date main stage precious and base-metal mineralisation. This study emphasises the spatial, temporal and genetic links that have been drawn between diatremes and both epithermal and porphyry systems in volcano-plutonic arcs.

Jan 1, 1999

By R R. Lovel, G J. Sparrow

Currently there are large reserves of good quality iron ore near to existing infrastructure that are not being developed because the phosphorous levels are above acceptable market specifications. Since the high phosphorous content is considered to be mainly associated with the goethite fractions of the ore, attempts were made to leach the phosphorous from the ore after a heat treatment to dehydroxylate the goethite. Heating the ore and leaching with 40 g/L NaOH lowered the phosphorous levels from 0.145 wt per cent P to 0.075 wt per cent P or lower, but a heating temperature over 800¦C was required to achieve this reduction in phosphorous levels. However, when sodium hydroxide was added to the iron ore before the heat treatment, similar phosphorous removal was achieved with a heating temperature of 300 - 350¦C. It was considered that dehydroxylation of the goethite in the presence of the hydroxide makes the phosphorous available for removal with a water leach. As well, 50 per cent of the silica and 60 per cent of the alumina in the ore were also removed in the leach, but some sodium remained in the leach product. Further work is required to remove the residual sodium to produce a marketable product.

Jan 1, 2009

By C Vejrazka

Northparkes is located 27 km north of the township of Parkes in central New South Wales, Australia. The operations consist of underground block cave mines and an ore processing plant that produces high-grade copper and gold concentrate. Production is currently sourced from the E48 Lift 1 block cave mine and open cut stockpiles. Mining commenced at Northparkes in 1994 as an open cut operation. Underground block cave mining began in 1997. Northparkes was the first mine in Australia to use the highly efficient block cave mining method, which relies on gravity and natural rock stresses to fragment the ore.The occurrence of air blasts is one of the principal mining hazards in block caving operations between the time of first undercutting and breakthrough of the cave to surface. As such, it needs to be managed continuously, and risk assessments need to be reviewed on a regular basis for applicability to changing conditions. Unfortunately, there is little literature on how to practically approach air blast risk assessments in a way that can be incorporated in the day-to-day operation of a mine. Previous methods of assessing air blast risk were tedious and results were often unrepeatable.With the extension of the E48 Lift 1 extraction level, it was necessary to assess the air blast risk for the extension drives and develop operational guidelines for production from the extension. A review of the methodology for assessing air blast risks revealed substantial improvement opportunities.This paper outlines the principles used for air blast risk assessments at Northparkes Mines and the methodology employed to achieve efficient, repeatable and auditable results.CITATION:Vejrazka, C, 2016. Northparkes Mines’ current air blast risk assessment practices for block caving operations, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 257–264 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By Grieveson P, Terry B. S

Carbothermic reduction of sulphide minerals for achieving a selective separation of metallic species from complex minerals has been discussed by considering the prevailing oxygen potential during the course of reaction. Construction of univariant plots for the reduction of sulphides with carbon monoxide gas or carbon and in the presence of either lime or anhydrous calcium sulphate is the key feature of this work. The theoretical calculations for univariants in the Cu-Fe-S-O system indicated a preferential separation of metallic copper and iron by imposing a chemical potential. This is evident from a logarithmic plot of sulphur dioxide partial pressure against reciprocal temperature. The results are compared with empirical data for the reduction equilibrium. The reduction behaviour of the constituent sulphides are also discussed together with the experimental results and theoretically predicted phase stability diagrams.

Jan 1, 1992

By N A. Sikwa, L M. van Niekerk, G N. Ndlovu

In June 2012, Lucara Diamond Corporation officially commissioned its Karowe Diamond Mine in Letlhakane, Botswana. The processing plant circuit incorporates variable speed autogeneous milling, a first for African diamond processing - only previously practiced in Russia. The paper discusses the basis for the selection of milling against the more traditional circuits incorporating crushing and scrubbing. It covers early commissioning challenges of operating a mill in an æalien environmentÆ with no immediate reference plant to look up to for bench-marking.The paper describes how these challenges were overcome and learnings quickly incorporated into the mill operating philosophy for maximum diamond liberation and minimum product damage. The plant was commissioned in three months and by August 2012 the production ramp up had reached name-plate capacity. The feed to the mill has varied from highly weathered material to extremely hard kimberlite and the operating philosophy had to be optimised for the full range of ore types. While more work is required to stretch the mill operating envelope coupled with other circuit additions to improve liberation of fine diamonds at minimum capital expenditure, the mill has, to date, performed to its billing.CITATION:van Niekerk, L M, Ndlovu, G N and Sikwa, N A, 2013. Commissioning and operating an autogeneous mill at Karowe Diamond Mine, in Proceedings MetPlant 2013 , pp 215-228 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 15, 2013

Sufficient time has elapsed since the enactment of the amendments to the mining legislation in 1981 to enable an examination to be made of the way in which the licensing system operates in practice. One of the most important decisions in resource management in New Zealand is whether or not rights of access to the resource should be conferred by the Crown upon an appropriate private sector participant. The licensing system is the means for allocating these rights of access. The manner in which the licensing system is administered, therefore, is crucial to natural resource management in New Zealand. What is the mining licensing system in New Zealand designed to achieve? This simple question admits of no easy answer. Is it the identification and development of the mineral resources of New Zealand? Are these objectives tempered by issues of resource conservation and environmental protection? Is a balance to be achieved among these competing factors? Does the legislation contain any priorities? Does the system respond in an ad hoc manner to particular facts and circumstances or does it operate within a more predictable framework? To what extent are decisions made on access to minerals with reference to the development or conservation of other resources? These questions may be summarised in the title to this paper which poses the question whether mining licences are instruments for resource management.

Jan 1, 1988

Mining is taking place at increasing depths of cover on the Southern Coalfield beneath predominantly massive sandstone strata. Within the next twenty years, there will be longwall mining at depths greater than 600 m. As the Sydney Metropolitan area continues to expand and as coal mining approaches these urban areas subsidence will continue to become an increasinglY important aspect of coal mining research. Investigations, commenced in the mid 1960's, allow prediction of subsidence in the Southern Coalheld with reasonable confidence. The work is showing that the characteristics of thc subsidence troughs over the deeper mining at Appin differ from the characteristics of mine subsidence at less cover.The longwall mining at Appin Colliery has resulted in a maximum measured subsidenee of 730 mm. The maximum strains were small because of the large radii of curvature of the subsidence profiles. There was no damage to any of the buildings in the township of Appin.

Jan 1, 1982