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By Moxon NT

The detonation pressure of ANFO can be significantly reduced by the addition of low density materials such as polystyrene, bagasse, sawdust or perlite. Laboratory and field test results have shown that homogene- ous mixtures of these low density explosives can be produced in a bowl truck and loaded into a blast hole without segregation. The detonation pressure of the mixture can be tailored to suit the material to be blasted by varying the quantity of low density additive incorporated into the mix- ture. Results obtained in the field indicate that these low density explo- sives can lead to significant cost savings without compromising fragmentation or production.

Jan 1, 1988

In a coal mine there are many substances capable of ignition under certain circumstances, which can be placed in the following groups: ordinary combustible solids, dusts, liquids and vapours, gases, metals and plastics. There are many factors influencing ignition, including temperature, minimum ignition energy, particle size, explosion pressure level, rate of pressure rise, specific energy content and also explosive limit. Not all are applicable in every case. Frictional ignition of methane is an accident statistic of increasing concern and is considered in some detail. Practical measures that can be taken to reduce the incidence of frictional ignitions are considered, and also possible ways of ignition suppression.

Jan 1, 1981

Commercial pelletizing commenced in 1955 to agglomerate very fine concen- trates which could not be fed directly to the blast furnace. Extensive develop- ment has taken place and is continuing. There are now three main heat hardening processes in use. Plants are operating, or under construction, throughout the world capable of producing in excess of 125 million tons per year of pellets from concentrates or direct mined orefines. The Whyalla Pellet Plant, which commenced production in May 1968, is examined in detail to illustrate the general principles of pelletizing. This plant converts high grade iron ore fines into high quality pellets at a rate in excess of 2 million tons per year.

Jan 1, 1971

By S Arya, A Bhandari

Dust emissions by blasting are of concern to both mine operators and surrounding communities. The quantity of dust produced, and the effects of its dispersal depend substantially on geological, blasting and meteorological conditions. This paper provides details of methods used to quantify the amount of dust produced after collecting samples using high volume dust samplers, and the difficulties encountered in satisfactory dust sampling and quantification. Also described are practical dust reduction methods by using water filled ampoules and water filled balls.

Jan 1, 2004

The economic viability of base metal and gold production projects at Chillagoe, North Queensland has been elusive or difficult to achieve. Because of isolation and low grades metallurgical efficiency has always been essential. This paper, concentrates on the Chillagoe Railway and Mines Company's operations from 1898 to 1914 and Elders Resources Limited's current developmental operations at Red Dome. The technological methods of concentrating, smelting and refining the copper, silver, lead and zinc by the Chillagoe Company will be outlined as well as their understanding of the geological aspects of the ore bodies and the stock market speculation. The Chillagoe Company failed in its economic management but developed the region. Elders Resources have successfully redeveloped the region including fostering the tourist potential of the area through their expert financial, engineering and metallurgical strategies within the external economic parameters of the Pacific Region.

Jan 1, 1987

By Ciminelli VST

Thiourea leaching has been applied to a refractory gold concentrate previously treated by bacterial oxidation. Following the bio-oxidation, gold has been leached in acidic thiourea solutions, under different pH(1 - 2.4), thiourea concentrations (2 - 15 g/1), ferric ion concentrations (0.04 - 3 g/1) and temperatures (298 - 333 K). Through this procedure, it was possible to increase gold extraction from 40 to 77 per cent. The increase in temperature raised gold extraction and reduced reagent consumption. Sodium sulphite addition was also very effective in lowering thiourea consumption. Staged leaching operations with interstage acid washing and carbon-in-leach experiments were tested, in an attempt to increase gold extraction. The results of thiourea leaching were compared with those obtained with cyanidation.

Jan 1, 1993

Trade unions are people. As organisations they exist to represent the needs and interests of their members; that is the workforce. Thus one of the underlying objectives of the trade union movement has been and will continue to be: achieving from management recog- nition that the labour input to the production process - whether that be in the factory, office or service context - is made up of individual people who can not be treated as just another factor of production. The essential difference between labour input and other factors of production such as capital and raw material is the "humanness" of the individual entities which make up a firm, company or industry's labour supply. Recognition of the "people" input to the production process has essentially two aspects: humanisation of the workplace and the treatment of labour as human beings who have a role to play both within the workplace and within broader society.

Jan 1, 1982

By Tonkin D. A

Poor performance in the several stages of the magnetite recovery circuit, coupled with poor desliming through inefficient and over- loaded desliming screens, led to excessive magnetite consumption. An accurate and reliable sampling programme was established covering all outlets of the plant. Emphasis was placed on frequency of increments in an endeavour to detect extreme conditions of short duration. Systematic checking of the entry points to these outlets than identified those sections of the recovery circuit at fault, namely magnetite recovery separators and the heavy media cyclone product rinsing screens. More product rinsing water was provided, and modifications to the rinsing screens improved the efficiency of these units. Consistency of operation through automatic control of level eliminated the sudden massive losses in the magnetic separators. Load on the recovery circuit was then reduced by improvements to the raw coal desliming screens. A 50 per cent reduction in magnetite consumption was achieved.

Jan 1, 1974

By J L. Bos, D J. Readett

As mining progressed through the Girilambone oxide orebodies, down to the primary sulphide zones, each successive stratiform layer yielded copper bearing ores of changing mineralogy and grade. Constant changes, innovations and optimisation were required to be applied to the heap leach, solvent extraction and electrowinning operations, to efficiently produce LME Grade A quality copper cathodes from this ore. The changing ore types required various crushing, stacking and heap leach irrigation methods to ensure that optimum recovery from the predominantly low-grade copper ores was efficiently achieved. Subsequently, innovations such as heap aeration and heap rejuvenation techniques were implemented. The constant selective removal of copper from the maturing heap leach liquors, coupled with an increase in iron(III) concentration, required solvent extraction optimisation. Changes to the original solvent extraction circuit configuration, combined with changes in operating parameters and procedures, allowed effective processing with changing heap liquor compositions. The electrowinning tankhouse was also upgraded and optimised through continued testwork and monitoring, to maximise cathode production and quality

Jan 1, 2000

Australasian mining companies expect a high standard of professionalism from their metals exploration teams. They also have, increasingly, a global perspective, employing explorationists of diverse cultural backgrounds and operating in diverse environments. Human resource development (HRD) of these professional explorationists needs to address all personal facets of functioning independently and interdependently in a modem working culture, as well as the needed technical competency. Creation of a learning organisation to promote this development is critical. Organisational consultants can support managers and supervisors as mentors facing the wide spectrum of development required by the explorationists; mentorship and guidance counselling can then complement training in the maturing of professionals from technical competence to professional independence and interdependence. Empowerment and clearly stated expectations are keys by which professionals can learn efficiently and effectively.

Jan 1, 1996

By Sandy W

This paper examines the effects of a significant number of plant alterations and modifications to the lead flotation circuit during the past five years. Metallurgical effort is directed largely at the flotation performance of middling streams and current strategies are discussed. The automatic control of cell destination and collector additions are outlined in the latter section of the paper, along with a description of control hardware in current use.

Jan 1, 1983

By Liu H, Chen S

Natroalunite is one of colouring minerals in kaolin. In this investigation, natroalunite, on which Ca(II) was adsorbed, was flocculated by HPAM and kaolin was depressed in suspension. The adsorption of Ca(II) on the natroalunite surface was studied by zeta-potential measurement and Auger Electron Spectroscopy analysis. Ca(II) was adsorbed more on the natroalunite surface than on the kaolin surface. The mechanism of Ca(II) adsorption was considered to be chemical adsorption on natroalunite and to be physical adsorption on kaolin. It has been found that Na6P6O18 and Na2Si04 can strongly affect Ca(II) adsorption on the surface of kaolin, but weakly on the surface of natroalunite. The effects of degree of hydrolysis and the molecular weight of HPAM, the effect of pH and the effect of Ca(II) have been studied. The kaolin ore, containing SO3 1.05 per cent has been processed with this method. The products only containing S03 0.36 per cent and the weight ratio of concentrate 52.27 per cent were Obtained.

Jan 1, 1993

The underwater test is now being used routinely to characterise explosives and initiators. However, several outstanding issues regarding the role of confinement and the usefulness of the test results in predicting expected blasting performance require further elucidation. This paper reviews the underlying principles governing the test, and highlights its relative advantages and disadvantages in product development and applications. It deals with topics of energy release, energy partitioning, confinement and efficiency, supported by illustrative examples from tests with various products and geometries. The results are analysed in terms of both the detonation parameters measured and their extension to predicting blasting performance in the field. It is emphasised, that just as with other performance tests, the results and conclusions are only valid under the particular test conditions employed, and over-generalisation of these results can lead to erroneous conclusions.

Jan 1, 1999

By R Nakia, R Livingstone

Historically the Goldfields of Victoria produced large volumes of gold. Interest in these historical Goldfields has grown over recent years with a view to restarting production of gold. A notable example of this is the Bendigo Goldfield. There is also interest in the Ballarat Goldfield and Ballarat Goldfields Ballarat East Project is a particular example of this. The aim of this paper is to describe the ventilation aspects of the potential Ballarat East project. The mine is proposed as a decline access. The paper gives an overview of the project and in particular the ventilation planning associated with a number of possible equipment scenarios. The paper also analyses the main ventilation pollutants that are likely within the proposed mine as it develops to increasing depth. An attempt is also made to determine the depth at which mine climate will become the dominant pollutant rather than diesel exhaust pollutants.

Jan 1, 2003

By Williams DJ

Preliminary calculations suggest that spoil piles in the Bowen Basin will undergo approximately 4 m settlement as the ground water table recovers after mining is abandoned. Approximately 1 m of differential settlement is possible. Superimposed on this will be a long term creep settlement of 1-3 m/log cycle of time. Depending on the nature of the spoil material, partially submerged spoil piles could be sufficiently stable although to ensure stability during long term creep it may be necessary to flatten the final spoil pile face to approximately 25¦.

Jan 1, 1987

In the last few years a number of mineral laboratories were established in Indonesia coinciding with the increase in gold exploration in the region. Prior to this, much of the analytical work was sent outside the country,however this is no longer neccessary.

Jan 1, 1990

Cut and fillstoping using hydraulically placed mill tailings has become an essential feature of stoping operations in Kalgoorlie. ' Approximately 30 per cent of the total production is currently mined by this method. Fill is prepared by thickening or cycloning and is gravitated or pumped underground. The average pulp density is 70 per cent solids by weight, Recent cost reducing innovations are the use of steel passes, corrugated iron manways, polythene film sealing, and the replacing of vertical cement lined pipes with boreholes. TTTTTI rvr T Trim r l1TT

Jan 1, 1964

By Toomey P. T

In many open cut coal mines, rivers and large creeks can cause planning and operating difficulties, both in the terms of the more obvious location of the current watercourse, but, and sometimes more importantly, past meandering of the watercourse. Prevent and past flow regimes may have deposited large alluvial sequences within the current mining areas. The presence of groundwater within the alluvium further complicates the planning and operating practices.A situation exists at Saraji Mine in which alluvial sediments overlie a massive sandstone sequence which in turn lies at about one metre above the coal seam. The problems encountered include high levels of groundwater ingress to the pit, highwall instability, and an unacceptably high rate of blast hole collapse (prior to charging with explosives). Other aspects of the dragline stripping operation were also affected.

Jan 1, 1992

By Whitworth NR, Fox MJ, Henley RG

The coal mass flow monitor was developed to measure the instantaneous mass flow rate of pulverised coal to the copper reverberatory furnace at Mount Isa. The instrument was calibrated with an isokinetic coal sampler which was installed immediately downstream from the coal mass flow monitor. Readings from the coal mass flow monitor were used to control the feedrate of coal to the furnace and this helped to stabilise the furnace operation.Coal samples obtained from the isokinetic coal sampler were also sized using a Leeds and Northrup Microtrac analyser. The coal size was critical to reverberatory furnace performance. These developments significantly improved the overall combustion control of the furnace and gains of ten percent were made in the furnace thermal efficiency. Testwork on an auxiliary arch coal burner is also reported.

Jan 1, 1985

DR. WARK, said: I have not come to Broken Hill to tell you how to conduct flotation operations; indeed, during my short stay here I have already learned much concerning the process, of the many difficulties which have been overcome, and of those still awaiting solution. My purpose to-night is rather different. All who have been concerned with the operation...

Jan 1, 1933