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By R A. Eggleton and, P de Caritat, K M. Scott

The Portia Au and North Portia Cu-Au-Mo prospects are located on a magnetic structure called the Benagerie Ridge Magnetic Complex, comprising varying pyrite-bearing Proterozoic albitite, phyllite and carbonaceous phyllite. The prospects are covered by up to 75 m of Cainozoic sediments, which comprise from top down, surface soils, Quaternary sediments, the Miocene Namba Formation and the (Late-Oligocene?) Portia Unit.The Portia Unit is dominantly clay-rich with local sand-rich base and it fills palaeo-topographic lows and a palaeo-valley that incised into the weathered basement rock (saprolite). This sedimentary unit hosts the majority of the Au grains found at Portia, with additional Au grains also present in the underlying saprolite. The North Portia prospect comprises saprolite hosted Cu-Au-Mo, with elevated concentrations of As-Pb-V present in the northern part of the prospect. These two groups of elements are delineated using factor analysis, and are regarded as the pathfinder elements for the North Portia mineralisation.Secondary Cu minerals including covellite and native Cu are present in the lower saprolite, and are stable under reducing conditions in the saturated zone.In the upper saprolite (unsaturated), Cu, Au, As, Mo and Pb are associated with Fe-oxides, mainly goethite and hematite. Saprolite leached of Fe generally contains low pathfinder elements concentrations.

Jan 1, 2004

By D S. Nicholson, T Marshall

Reserves of high-grade quartz gravel, lignite and timber suitable for the production of silicon metal and ferrosilicon on large scale occur within 40 miles of Bluff Harbour. Undeveloped hydroelectric power resources on the Clutha River are located within 50 miles of the most promising quartz gravel deposits while opencastable lignite, potentially suitable for electric power production, occurs in the same locality as the quartz gravels. A preliminary study of production economics indicates that the commercial feasibility of silicon/ferro-silicon production would depend mainly on the cost of electric power, total capital cost of plant, and the market value of the products. The proximity of Bluff Harbour is advantageous for the export of products.

Jan 1, 1971

Since the 1950's drilling has been rapidly mechanised. First from hand held drills with air legs to pneumatic jumbos, then to more effective hydraulic jumbos. Development of underground drilling equipment naturally could not have stopped here. Hydraulic drilling saw an improvement in drilling capacity and efficiency after the introduction of second generation drifters in the early 1980's. Also in the early 1980's a few equipment suppliers started to study how to improve the efficiency in operating the rigs. The first computerised rigs for tunnelling were delivered to work sites in mid 1980's. At the same time a few computerised longhole drills started drilling in mines.

Jan 1, 1988

The U.S. Bureau of Mines has developed a prototype cross well acoustic logging system and complementary tomogr`aphic image reconstruction software for the detection and delineation of abandoned underground mines and associated subsidence failure in relatively shallow environments. The logging system uses a piezoelectric, cylindrical bender as an acoustic source. A triaxial accelerometer assembly, designed to be rigidly locked in the borehole, is the receiver portion of the logging system. Both the source and receiver probes operate at high frequencies, thus providing short wavelengths capable of resolving small features in most rock types. A modified van with a dual-drum wireline winch, 4-channel data acquisition system, power amplifiers, and waveform generator supports field operation of the logging system. A field study was conducted at a test site in San Antonio, Texas, to demonstrate the cross well acoustic logging system. The underlying rock at the test site is similar to stratified sediments in coal measures. First- arrival travel times were interpreted by tomographic reconstruction of the velocity field in the two-dimensional cross section between the source and receiver boreholes. The resulting image correlates well with geological borehole logging data for the test site.

Jan 1, 1992

By Kerr I. D, Kennedy M

Flash X-radiographs were obtained of commercial electric No 6 and No 8* strength aluminium tube detonators in small-diameter cartridges of emulsion explosive at various times after fusehead operation. The trigger system for the radiography was based on the detection of light following fusehead firing via optical fibres inserted into the fusehead cavity during detonator assembly. These experiments were simulated using a finite element hydrocode with realistic treatment of the non-ideal reaction kinetics. Excellent agreement was demonstrated for the shape and position of the shock waves. In both cases, initiation of the emulsion was predominantly forward from the detonator. For the No 8* strength detonator, this initiation resulted from the shockwave delivered through the sides of the detonator, while for the No 6 strength detonator, initiation was the result of a complex interaction between shockwaves originating both from the sides and from the endcap. In the reverse direction (towards the crimped end of the detonators), initiation was only weakly dependent on detonator strength, being controlled mainly by the competing processes of rarefaction from the cartridge boundaries and comer turning of the detonation wave from the forward initiation. The consequences for field performance of small-diameter emulsions will be discussed.

Jan 1, 1990

Every text book for blasting in Japan says that Hauser's law can be applied for practice. But recently it came true that there was no historical record about him and no actual datum of his own or other's to testify. According to his theory, the funnel ratio N = r/W in crater test is inversely proportional to the rock strength and proportional to the explosive amount: where r is the radius of crater and W is the burden. But experiment showed the opposite result, and revealed new information. Two kinds of experiment, crater test and boulder blasting of mortar, were carried out to investigate the effects of rock properties on blasting. The material used for test 1 and test 2 was a mortar block (60cm)3 cube, 4 vertical faces of which were used for crater test. The results from Test 1 and test 2 were summarized as follows. The funnel ratio ranges between 2.5 to 4.5 in proportion to rock strength and burden. The standard ratio of 1, reported by Hauser, was not observed in any instances. It was also noted that the funnel ratio is independent of the explosive amount. The material used for boulder blasting, test 3, was a mortar block (40cm)3 cube, in the middle of which was located a vertical borehole for the explosive charge. The results of test 3 were as follows. The necessary explosive amount for boulder blasting is in inverse proportion to the mortar strength. Fragmentation and throw are proportional to the mortar strength.

Jan 1, 1990

By R E. Conder

A major initial and ongoing cost component in many mining operations is that of transporting mined materials and processed ore from the point of extraction or processing to the next operation. For various reasons the transport distance can be significant or in some cases the route may be particularly challenging. The trend to higher production rates to gain economy of scale benefits and capitalise on sales opportunities means that optimisation of transport can play a significant part in profitability. Apart from the cost criteria, increasingly there are other criteria such as environmental restraints, land ownership and security of supply that can have a significant impact on determination of the optimum route and transport vehicle. The paper aims to briefly highlight the important selection criteria and the benefits and disadvantages of the most commonly utilised transport vehicles. It then moves on to looking in more depth at belt conveying, highlighting the unique capabilities of the Metso MRC Cable Belt Conveyor system.

Jan 1, 2004

By R Lastra, Y Choi, C Hamilton, P Kondos

Hydroseparation (http://www.cnt-mc.com) was used to concentrate sized fractions (from <38 ¦m to 150 ¦m) of various ore products ahead of carbon-in-pulp (CIP)-treatment. The resulting size-by-size concentrates were mounted as monolayer polished sections and subjected to automated unattended precious metal searches by image analysis (see Lastra, Wilson and Cabri, 1999). Systematic variations in Au-deportment permit quantification of Au reporting as discrete grains from fresh-feed through to pressure oxidation (POX)- and CIP-feed. Application of hydroseparation, image analysis and assays to characterising tailings (from <10 ¦m to 106 ¦m) from four mine sites is also described. Results are encouraging enough to predict that the combination of hydroseparation (HS) and automated image analysis could become a standard methodology for study of precious metal ores and metallurgical products.

Jan 1, 2008

By Weller K. R, Stewart P. S B, Restarick C. J

The performance of the Renison tin concentrator was assessed in detail for two arrangements of the three available ball mills. With two mills used for primary grinding and the third for regrinding table tailing, the concentrator recovered 65.3 per cent of tin in the three tin concentrates produced by tabling, vanning and flotation at a calculated overall grade of 37.5 per cent tin prior to batch dressing. In the second arrangement one mill was used for primary grinding and two mills for separate regrinding of table tailing and sulphide concentrate. The metallurgical effective- ness of the change was somewhat obscured by unintended changes,i.e. an increase in the assay of the fresh feed from 1.38 per cent to 1.1+6 per cent tin and unresolved changes in the sulphide rougher flotation and tabling. However, using the results from a detailed size by size analysis of the behaviour of ore components in appropriate parts of the plant, it proved possible to show that, had the two unintended changes not occurred, up to 5 per cent

Jan 1, 1977

Traditionally, the development of a mineral resource project goes through a fairly set pattern of decisions from what commodities to search for; where to look; how to locate; what are the reserves; how can they be exploited with optimum returns for all stakeholders; where are the markets and what will be the price received; what financing arrangments? However, due to the unique nature of most mineral resource properties, the relative significance of individual parameters on the ultimate development decision will vary from project to project. Sensitivity analysis in its formal sense is most frequently related to the economic analysis of a project particularly in conjunction with the ultimate development decision making process, and acknowledges the uncertainty of the actual values with their impact on the corporate decision making yardsticks. In many cases, this analysis merely adds more values to confuse the decision makers who may well opt for some subjective rationale to overcome the numeric confusion. However, sensitivity analysis should be used more frequently to exploit the development dollar to its maximum, THROUGHOUT the phases leading to the development decision. It is essential to identify the critical inputs to the various decision tiers in a project as early as possible and direct the funds to ensure that these parameters are determined as accurately as possible. Examples are used to illustrate the need for an even-handed quantification of the parameters which affect the outcome of decisions en route to the final one while minimising the risk in making an optimum assessment in relation to development funds Available.

Jan 1, 1983

By W J

Al ores arriving at the works which contain more than 3% sulphur, together with all sands and other fine residues, are delivered to the roasting department. Those that are in a coarse condition are first sent to the crushing plant, consisting of 15 in. x 9 in. jaw crushers and two No. 5 Krupp mills. The ore is here crushed through a quarter mesh screen. Any pyritic concentrates high in sulphur are given a preliminary roasting, to bring the sulphur contents down to about 12 % and the roasted material is delivered to the H. H. charge-making bins. Here the various ores, sands, residues, roasted pyrites, together with about 12 % of limestone, are made up into I-ton charges in hopper trucks with bottom discharge. The trucks are elevated by hydraulic lifts to a tramway running over the roasting furnaces, and the contents are dropped into hoppers over each furnace, from whence the mixture is fed into the centre of each furnace by means of a Challenge ore-feeder.

Jan 1, 1918

By Schoning W. L

Ore deposit models form the basis for numerous other economic decisions in the mining process. The success of these economic decisions therefore depend directly on the accuracy of the ore evaluation process. The Geology Department at the Sishen Iron Ore Mine is responsible for the generation of a reliable geological computer model of the rock material with predicted grades. This information is then utilised for further ore reserve calculations, mine planning, production scheduling and grade control. Owing to a very complex geological orebody, grades and beneficiation characteristics differ significantly from sample to sample. This means that ore evaluation is a difficult process and great reliance is placed on computer techniques. In 1993, preparation for the ISO 9002 quality certification of the mine motivated the Geology Department to hold formal `problem solving' sessions in order to identify and revise problem areas in operating

Jan 1, 1995

The changing characteristics of raw materials has highlighted the limitations that conventional vibrating screens have in the handling of fine wet sticky materials. These' limitations have led to the development of a totally new concept of screening, the Rotating Probability Screen. In order to illustrate the practical benefits to be gained by the extraction of fine materials ahead of subse quent processes particularly in the coal industry, the experiences gained in Ro-Pro installations in America, Australia, Europe and Britain are drawn upon.

Jan 1, 1984

Results from current NERDDC funded research into the geotechnology of highwall trench mining methods have clear implications for mine planners in the areas of blast design, trench shape, location of the surcharge spoil and remnant coal pillar design.Adoption of successful smooth wall blasting techniques not only removes safety hazards from the trench face, but limits development of bedding partings at the seam contacts that interrupt the smooth transition of stress across the coal seam.

Jan 1, 1992

By G W. Wilson, P Ritchie, N A. Currey

The design and rehabilitation of potentially acid forming (PAF) waste rock dumps is site specific, being a function, among other factors, of the rock types, the dumping and storage method employed, and the climatic setting. The æstore and releaseÆ cover system developed to manage acid rock drainage (ARD) from mineralised waste rock dumps at Kidston Gold MinesÆ open pit operations in the semi-arid climate of North Queensland, Australia, has been monitored for seven years. The paper describes the philosophy behind the design of the PAF dump and æstore and releaseÆ cover system and the adaptation of the cover system over time to suit KidstonÆs conditions. The results of monitoring over the seven years since the first cover was constructed are presented, and the approach being taken at Kidston to ensure that the risk of impacts from any residual ARD is accommodated and to facilitate lease surrender are described. The Kidston story is a valuable case study of a successful approach to remediating an identified source of ARD in a semi-arid climate, which has actively engaged all Stakeholders.

Jan 1, 2003

By Townsend MG, Evans RB

In Northland, New Zealand, localised large deposits of halloysite clay have been produced by in-situ alteration of rhyolite volcanics of Pliocene or Pleistocene age, which were erupted through pre- Pliocene sedimentary strata and locally through Pleistocene basalt; and which were subsequently onlapped by further basalt flows. Alteration to clay has been a result of both hydrothermal and of meteoric processes, and decreases in intensity of alteration with increasing depth.The raw material is crushed and fractionated to produce a product of less than 2 micron particle size, which is of exceptional whiteness and brightness. The unique properties of the clays render them highly desirable for specialised ceramic purposes.

Jan 1, 1990

I am very grateful to have the honor of delivering this Key- note Speech to all of you here today, to the Chairman Mr Cope- man, and to all the organisers. As you heard, I was mainly involved for a very long time in the purchase of iron and steel raw materials for Nippon Steel Corporation. Today, however, I would like to talk to you about a much wider issue, namely, how the Japanese steel industry is going to change towards the 21st Century, and what will be the main technical innovations and trends behind those changes. I will also mention the effect that the changes are likely to have on the procurement of raw Materials.

Jan 1, 1988

By Schofield N. A

The cross-sectional method of stope grade estimation at Cobar Mines has consistently had several shoneomings, me most imponant of which being mat stope grade is significantly overestimated in the high grade lenses.The use of mree-dimensional ore lens modelling improved the grade estimation and ore waste definition but significant overestimation still occurred in me high grade stopes, particularly those wim extremely variable grade distribution. The implementation of an indicalor kriging based method for mapping of me high grade copper mineralization has significantly improved the quality of copper grade estimates and provides a mineralisation geometry similar to that generated manually by me mine geologists. This paper presents the results of a test case study in the application of indicator kriging to the mapping of the copper grade in two stopes in the QTS North mineralisation. The results are encouraging in that they prov ide coofi rmation of the geometrical model developed by the geologists and much improved estimates of the grades of me stopes whencompared to me grade reponed from mining these stopes.

Jan 1, 1993

By Moort van J C

A new low-intensity magnetic separator which operates by spinning particles in a continuously rotating magnetic field is able to reduce particle entrapment of non-magnetics to an almost insignificant level. In such separators the removal of ma

Jan 1, 1997

By G J. Lyman

The theory of sampling has progressed slowly over the last century. The concepts of correct sampling were known to mining engineers such as D W Brunton in the 19th century. It was recognised early in the 20th century that the Poisson distribution of particles carrying the target analyte was the key to the uncertainties between samples of a given mass. However, no efforts were made until the 1980s to determine the entire sampling distribution as a function of sample mass. The variance of sampling was made clear by Gy and others, but none attempted to determine the entire sample assay density function until J H Venter in South Africa applied the method of characteristic functions to the problem.Venter applied the method to a specific case of very low analyte concentrations in samples of very fine particle size where his assumption of constant sample mass was justified. When his general methodology is applied to the more general problem, it can be shown that the assumption of constant sample mass is no longer justified and leads to some anomalous results for sampling variance. Venter’s method can be expanded to allow for a statistically variable sample mass and to take into account the size distribution of particles that carry no analyte.This paper presents the basis of Venter’s work and shows how the approach can be easily modified to yield results for the variance that are consistent, for example, with the work of Gy. It is also demonstrated that the entire sampling distribution can be determined without undue computational burden when sufficient information on the material heterogeneity has been collected.CITATION:Lyman, G J, 2014. Determination of the complete sampling distribution for a particulate material, in Proceedings Sampling 2014 , pp 17–24 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014