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By Keyte SG

Gravity methods of recovering alluvial gold are not very efficient at particle sizes below about 0.1mm. Whereas such gold may not have been economic to recover in the past, the same may not be true today. Centrifugal concentrators, like the Knudsen and Knelson bowls, are showing promise after an inauspicious start, at least in New Zealand. The large proportion of heavy mineral in many auriferous beach sands and the natural hydrophobicity of fine gold should make flotation an attractive contender for its recovery. The conventional mechanical flotation cell is effective, but roughing, scavenging and cleaning are necessary to achieve both high recovery and low mass yield. More problematic is the difficulty of maintaining coarse and dense sands in suspension. The air sparged hydrocyclone is effective at recovering fine gold from a fine Colarado River sand, but is not effective for the coarse and dense beach sands of New Zealand. The flotation column shows much promise for these sands, when recoveries of over 80% and mass yields of less than 1% can be achieved in a single pass. The froth separator of the USSR and flash flotation could also be worthy contenders. It is felt that flotation could be limited to naturally and artificially de-slimed concentrates.

Jan 1, 1990

By Bromley JC

Eimco Great Britain, a division of Baker Mining Equipment Company, was contracted to develop a hardrock tunnelling machine in conjunction with British Coal. The objective: a machine to cut rock up to 170 MPa compressive strength yet retaining the flexibility of roadheader type machines. This flexibility to encompass mobility, wide range of excavation shapes and sizes, simplicity of design and use, compact size, and efficient cutting operation. Current roadheaders operating in hard material are characterized by: 1. Severe machine vibration 2. Bouncing of the boom away from the rock 3. Very high pick wear 4. Inability to sump head in bad floor conditions The reasons for this poor performance can be attributed in part to: 1. High speed of cutting head rotation 2. Inability to hold boom against rock while cutting variable hardness strata. To overcome the problems described, a new articulation method was developed utilizing four hydraulic rams to "lock" the boom in position on one axis and four hydraulic motors to rotate the boom for cutting via a turret arrangement. The slide mounted turret is hydraulically advanced for sumping into the face, independent of the machine base. To transfer cutting forces back to the rock, the machine base is held rigidly in the excavation by floor to roof or side to side rams. A cutting head mounted on the boom rotates at very low speed, but with very high torque.

Jan 1, 1987

With the sinking of the No. 3 Shaft and the erection of a changehouse nearby, a sub-brace level structure was provided incorporating a time office, underground foremenÆs office and lamp room, in conjunction with a covered walkway, ambulance room, fire station and waiting brace.

Jan 1, 1957

Studies of Theological effects in grinding hold promise for improving this energy-intensive process. Six surveys of the Hellyer ball mill were conducted. The stream and sizing data from these surveys were balanced by JKMbal to compare the mill

Jan 1, 1994

By Needham RS

Hydrothermal mineral deposits are the dominant mineral deposit type in the Cullen Mineral Field, and have been important sources of tin, tungsten gold, silver-lead, zinc and copper. The deposits are mostly in north to northwest-trend- ing shear zones, and are confined to Early Proterozoic contact metamorphosed metasediments or synorogenic to postorogenic granitoids. The distribution of the vein-type deposits with- in the contact aureole defines a district-scale metal zonation of uranium closest to granitoid, through tungsten, copper, tin, silver-lead to gold with increasing distance from granitoid contacts. This zonation probably reflects de- creasing temperatures within the contact aureole during granitoid emplacement, and at the time of generation of a variety of metal-bearing fluids. A magmatic source for some of the metals is indicated by the positive spatial relationship between uranium, tungsten, copper and silver-lead deposits and granitoids abundant in those metals. There is little evidence for any such relation- ship for tin and gold deposits, except for an association of some tin deposits with tin-enriched mafic rocks. Most of the granitoids with anomalous metal values are late stage highly fractionated leuco- granitic phases forming younger plutons peripheral to the main body of the Cullen Batholith, They probably form cusps connected to the main body at shallow depths.

Jan 1, 1984

The approach to this subject is a very general one, but an attempt has been made to cover briefly a very wide field in the nationally important job of manufacturing iron for the iron and steel industry.Some historical data concerning the development of the furnace itself from early days have been followed by the modern ideas on raw materials and their beneficiation. Recent furnace design and modern auxiliaries have been given attention with, finally, some developments in practical operation.HISTORICALWhen dealing with such large 'and costly operating units as blast furnaces, there is not the same opportunity for research in design as in most other metallurgical processes. Over past generations the development of furnace design, or "lines" as it is usually termed, as well as most radical operating changes, has been very gradual.However, there have been some periods of rapid progress due to revolutionary changes. One such was the adoption of the steam engine for blowing and charging operations, and also, during this same era, about 1750, coke was first used as fuel in place of charcoal. Another revolutionary change came some 100 years later, when heating the blast became usual practice.Since then there have been great improvements in mechanical equipment and in the preparation of raw .materials. These factors, together with a better understanding of what happens inside the furnace, have led to the development of those large mechanically operated structures which are the most modern in blast furnace design.For many, years America has led the world in pig iron production and in furnace development, so that American design and practice is now recognised almost as standard. This type of furnace replaced the older stacks in England, Russia, Germany, South Africa and India, as well as here in Australia.

Jan 1, 1947

Flotation science and technology are related to three major sub- processes which are organized in a hierarchical structure as shown in Fig. 1. The basic sub-process is the chemical process which affects the attachment of air bubbles to mineral particles. In particular, the chem- ical process is related with the adsorption of surface active sub- stances at the gas-liquid, liquid- solid, and gas-liquid-solid inter- faces. This field has been most intensively explored in flotation research. The second domain in flotation research is concerned with the mineral particle to air bubble attachment sub- process in the system. This sub- process represents the dynamics of particle and bubble encounter where the contact angle and the induction time, determined by the surface chem- istry of the system, are among the most significant parameters. This sub-process can be referred to as the micro-process as against the third sub-process, or the macro-process, which corresponds to the integral behaviour of the system. Two other sub-processes are integrated into the macro-process in which they may not reveal themselves explicitly in the details. The third sub-process does not entail surface-chemical or physi- cal events any more, but it represents them all inclusively. To represent this sub-process we use mathematical equations, called models. Only in some simple or simplified cases can the models be solved exactly to find out the behaviour of the flotation system in which we are interested. Digital

Jan 1, 1984

By Larsen D. F

Minor iron formation related base metal sulphide mineralization occurs in granulite facies metamorphic rocks of the early Proterozoic Willyama Complex. Rock sequences hosting three iron formation related Cu, Zn, Pb prospects from the Thackaringa Group (Suite 3) are described. A caparison of host rock sequences, style of mineralization and facies of iron formations suggests major differences in terms of the overall depositional environment. However, significant similarities are present with respect to the nature and distribution of iron formation facies and the occurrence of chlorite 'alteration' zones in close proximity to mineralization in all cases. The chlorite within these zones occurs in a number of diverse forms in a range of rock types. A comparison of the prospects shows that there is no evidence to indicate that the chlorite in the zones is a retrograde alteration product of former higher grade prograde mineralogies - the chlorite appears to have survived granulite facies metamorphism. The mode of occurence of the chlorite in the 'alteration' zones together with the fact that the association quartz + chlorite + magnetite + pyrite + base metals is cx rmn to all areas suggests that the chlorite is specifically related to the processes which deposited the stratiform iron formations and related sulphides. It is considered that the chlorite precursor was a prenetanorphic alteration product or chemical sediment closely related to submarine hot spring activity which was also the source for chemical sediment precursors of the iron formations, associated lode rocks and Sulphides.

Jan 1, 1983

By Azizan A

The paper presents the results of chlorination of beneficiated rutile and struverite (a tantalum-niobium bearing, rutile type mineral in alluvial tin deposits) by carbon tetrachloride in the range 623¦K to 773¦K. The chlorination of rutile could reach near completion at 773¦K in about an hour. The process was found to follow a modified pore-blocking law, with the basic reaction constant K varying inversely with the particle size, so that the basic process may be a reaction under interface control (chemical control) as modified by the pore blocking effect. The pore blocking factors for the various experimental conditions were evaluated and the predicted curves showed good agreement with the experimental data. In the case of Struverite, a similar kinetic behaviour was observed but the chlorination process was relatively slower than that in rutile. It was also observed that in struverite, niobium got chlorinated faster, followed by tantalum and titanium, indicating a good possibility of separation by chlorination using carbon tetrachloride.

Jan 1, 1996

By Nidagal V

This paper discusses the dewatering strategy adopted and the considerations and procedures required to incorporate a dewaterinq scheme into the Mt Whaleback mining operation. It concludes that in pit pre-dewaterinq has successfully allowed mining to progress below the standing water level with the minimum of disruption or radical change to the mining method. It is recognised however, that dewatering is not a static activity and there is a requirement for ongoing investigations and development. Pre-dewatering commenced in October, 1984. Purpose designed pumping trailers have been employed to minimise the loss of pump availability resulting from the frequent. need to remove and reinstall pumps when close vicinity blasts occur. To July, 1986, some 0.5 Mm' of groundwater had been pumped from the unconfined orebody aquifer. Mining has progressed to some 20 m below the standing water level without. any undue water associated problems. Ultimately, it is ,cheduled to extend some 300 in below the original water level in the West Pit. With the development of an increasing area of the mine below the standing water level, the influence of seasonal high intensity rainfall events, which had previously caused little concern, now need to be addressed. Pumping equipment has been designed to evacuate storm water at a rate consistent with mine production Considerations.

Jan 1, 1986

The main aim of the conference is to work towards improved useage of steelplant slags which have largely been considered waste mater- ials, This paper summarised investigations carried out on the suitability of air cooled blast furnace slag, blast furnace granulated slag and basic oxygen steelmaking slag as road base materials. All slag samples were obtained from the PortòKembla Works of Australian-Iron and Steel Pty Ltd. Since road making materials are increas- ingly being characterised by use of resilient moduli, the compressive strengths and resilient moduli were determined for road base of the following slags. 1 Air cooled crushed blast furnace slag 2 mixes of air cooled blast furnace slag, granulated slag, and lime 3 mixes of air cooled blast furnace slag,-granulated slag and basic oxygen steelmaking slag. Evaluation of a local dacite (dense medium grained igneous rock, classification rhyolite), generally considered an excellent road base course material, was carried out for use as a reference material.

Jan 1, 1979

By Shunli Z, Jin X, Guanzhou Q

Flotation behaviour can be controlled, due to diminishment of granula quality and extension of specific surface area, by adding coarse particles (high- grade concentrates) to condition pulp. It has been substantiated that coarse particles can intensify fine particle flotation and its mechanisms are effects of carrier, intermedium and assistant aggregation of coarse particles. Calculation and analysis of Reynolds numbers and their variation for different size particles, under specific turbulent dynamic conditions, reveal that agglomeration among granulae is subject to specific turbulent dynamic conditions. Furthermore, sizes and adhesion strength of flocculated particles are the function of specific physical and chemical factors. Based on this research an innovative ramification carrier flotation process has been developed, which has been applied to Fankou Lead- Zinc Mine, Guang Dong province, China, etc, with satisfactory results. These results shed light on distinction between conventional flotation and fine particle flotation, meanwhile, provide a basic approach for further solution of fine particle flotation problem.

Jan 1, 1993

By Burgess JM

Research on gas distribution in the iron- making blast furnace has been conducted in three separate areas. Firstly, experimental work has been conducted to determine the important parameters which dictate the pressure losses in homogeneous and heterogen- eous packed beds. Secondly, a theoretical analysis of gas flow through the furnace softening-melting zone has been undertaken to determine the effect of the shape of the zone on the distribution of gas flow towards the furnace walls. Thirdly, a theoretical programme has been undertaken to develop methods for the prediction of furnace soften- ing-melting zone shape from furnace tempera- ture and gas composition measurements.

Jan 1, 1980

The diverse nature of inadvertent mine fires does not lend them to general treatment. But evolving from the unfortunate fires over past years is a simple principle in dealing with all fires to bring combustion under control. Control, in brief, means that the products of combustion, themselves possibly still with fuel values, are not revitalised by addition of fresh air. There are problems with fire- fighting, especially with water, as this may lead to production of CO and H2. Panel ventilation upstream of the fire must be controlled to direct all air over the fire. Some advantages in fire fighting are found by the use of "sails". Early diagnosis of fires and early treatment are essential for safety of personnel and safeguarding and recovery of property. Preparedness extends to up to date documentation, but first hand knowledge also is invaluable to the diverse personnel gathered to fight a fire, and in the decision making Involved.

Jan 1, 1981

By Tapp B. A

The minerals industry in Australia is currently regarded as the country's economic saviour; the bastion of economic security. As Fitzgerald (1974) stated, 'Australia's natural endowments in minerals are the envy of most countries of the world'. As a result the proposed new mineral developments are on a scale that hitherto in the sixties would have been completely unenvisaged. It is reported that Australia is poised on the verge'of a sixteen billion dollar mining-based investment boom: a boom that will see Australia dominate the energy export field, the mineral processing field, and create the 'coal dollar'. This growth scenario has many inherent dangers, and it is the authors' contention that these should be carefully considered before further development proceeds. Two of the major problems related to the mineral industry growth scenario are the predictability of the future metal market, and the energy cost of mining. The latter problem is the one discussed here. The mining-mineral processing industries in Australia currently use about 36% of Australia's primary energy

Jan 1, 1980

By Porter I, Singh RN

An advanced elasto-plastic finite element model adopting a modified Von Mises yielding criterion was used to simulate progressive failure of the rock strata surrounding a room and pillar mine structure. The model conformed to the strain-softening behaviour of rock and accounted for post-failure residual strength. The simulation was achieved in such a way that material values were updated after each FE run, according to the stress criterion until the solution reached the final equilibrium steady state of the mine structure. The suggested structural stability analysis approach accounted for the main features of the structure degradations produced during loading through changes in rock material stiffness and subsequent evolution of stresses. Comprehensive parametric analysis was performed and the inevitable effect of interaction of the roof, pillar and floor on the overall mine stability limit was investigated. The numerical results clearly showed that linear models could not realistically represent the true behaviour of the mine structure. The results obtained are in good agreement with that predicted in the field.

Jan 1, 1992

By N Esmaeili, M Saghaeian, L Hosseini, V Sheikhzadeh, R Hejazi

Ore roasting has long been used for beneficiation and assay upgrading of different ores. In this process, which is mainly used for sulfide ores, the ore is heated to a high temperature. More specifically, it is a metallurgical process involving gas-solid reactions at elevated temperatures. Some types of Iron ore are weak in magnetic properties. Hematite, goethite and limonite are classified in this group. Unlike magnetite, which shows strong magnetic susceptibility, these ores are hard to beneficiate through magnetic separation route. Many researches have focused on gravity separation and flotation routes for upgrading these ores and these methods have also been utilised in the industry. One of the methods to whose industrial application less attention has been paid is magnetising roasting in which the non-magnetic iron ore is transformed to magnetite which is further beneficiated through magnetic separation. In this study, magnetising roasting tests have been performed on one goethite sample in order to check the feasibility of using this method for this specific ore in industrial scale. It is worth mentioning that high intensity magnetic separation have been performed on this sample before but the achieved results were not promising. Results have revealed that through magnetising roasting magnetite content of the ore could be increased from 1.7 per cent up to about 25 per cent. FeO content of the feed sample was increased from 1.03 per cent up to around 9.25 per cent. Also optimum size distribution for achieving the best results in magnetising roasting for this sample has been determined through this study. The best results were achieved when the ore size was 0–10 mm. The effect of coal ratio, time and temperature on the process have also be studied. A coal ratio of 5 per cent, time of 30 min and a temperature of 850°C were determined to be the optimum conditions. Finally, the technical feasibility of utilising magnetising roasting for this specific ore has been confirmed.

Aug 24, 2022

By Takasaki Y, Ohzeki S, Hotta H

TO measure high temperature properties of blast furnace burdens ( the change of gas permeability accompanied by contraction, soft- ening and melting ) which govern the gas flow and its distribution, a series of experiments were carried out under simulated blast furnace conditions, using sinter, acid pellets and self -fluxing pellets. 1) The high temperature properties are affected by the ore's reducibility ( up to 1000 -1200¦C ), and the composition, and volume of gangue before reduction. Generally, the burde- ns with high basicity ( Ca0/Si02 ), high reduc- ibility and low volume of gangue have good high temperature properties. Good high temperature properties are : a high temperature at which the gas permeability rapidly decreases, a high melting point and a low maximum pressure drop. 2) Using acid pellets, slow-down of red- uction rate occurs around 1000¦C because the pellet forms a dense metallic shell, while its slag core, resulting from a FeO, Si02 and A1203 reaction, has a lower melting point. 3) The addition of MgO sources improves high temperature properties both of sinter and Pellets.

Jan 1, 1980

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

By Sakai S, Suga S, Bisque RE

Soil gases were collected on activated charcoal, analyzed by computerized mass spectrometry and treated with multivariate statistical pattern recognition to determine the diagnostic geochemical signature associated with the Okuaizu Geothermal Field in Japan. From this a geothermal model was developed and compare to 175 "unknown" samples in a 250 m spaced grid over 30 1Qn2 mapping the areas with a matching geochemical character. Faults and fractures were generally located by the presence of high molecular weight components. Following the initial survey, the faults in two specific areas were precisely located by a second survey with samples at 10-30m spacing. Where earlier geochemical surveys had placed anomalies 1-2 Km northeast of the geothermal center, the fingerprint survey accurately mapped the system and detected several faulted zones. It was not misled by hot springs located away from the geothermal System.

Jan 1, 1987