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By Savidis G

The characteristics of 'Z' (Back-over run) and 'R' (Reverse) ventilation systems are dis- cussed in relation to their suitability for longwall mining. Experience in European mines has been described as a basis for comparison with Australian conditions. In assessing the merits of each ventilat- ion system, such factors as longwall layout (pillar design, number of headings and gateroad stability), the need for gas drainage and bleed- er systems, as well as the influence of seam dip have been considered relevant. The R system is generally applicable for single and two heading development in seams where gas emission is a less serious problem. In contrast, the lower extraction to development ratio of the Z system (which arises from using three or more heading layouts) is considered more favourable where high gas emission occurs. The Z system provides greater flexibility with respect to the provision of refreshing air at the tailgate end, access of men and materials, installation and retrieval of gas drainage systems and the ability to interchange main- gate and tailgate roadways in cases where roof strata loads are difficult to control, or where cpam in hac an influrnra

Jan 1, 1983

Coal Mining machinery has undergone enormous changes in design and complexity of controls in the past 10 years. Specialised, high productivity equipment has been manufactured in Australia, in sufficient volume, to satisfy the local mullet needs.Local manufacturers face greater challenges from overseas competition, as well as increased customer demands to improve machine performance, productivity, quality, reliability and safety. In order to meet these demands now and in the future, it will be necessary to review work practises, and restructure production and quality systems to incorporate the latest principles and philosophies.

Jan 1, 1991

The number and severity of sulphide dust explosions in underground metalliferous mines have increased in recent years, despite various methods used to prevent or inhibit them. A dust explosion occurs when a cloud of combust- ible dust in an oxidizing atmosphere is exposed to an ignition source with sufficient energy to ignite the dust. A computer blast simulator model was used to investigate the movement of the fractured rock, temperatures and volumes of the explosion gases in a 70 m high, 24 m wide open stope.

Jan 1, 1988

By Van Weert G

Ferrous chloride solution pyrohydrolysis is a successful IICI regeneration process which is carried out in either a spray roaster or a fluid bed. Pyrohydrolysis is not restricted to ferrous chloride only, every metal chloride can theoretically be hydrolysed. In practice, however, the conditions for ferrous chloride pyrohydrolysis differ from those of many non-ferrous metal chlorides eg zinc, lead and cadmium. Hence, a pyrohydrolyser could function as a ferrous/non-ferrous separator, eg an iron oxide and zinc chloride separator. Most pyrohydrolysers operate on solutions, in which case more than 50 per cent of the process energy is needed for heating and evaporating water. However, this disadvantage would be diminished by feeding a slurry to the reactor. Against this background it was decided to investigate the chloridisation of zinc ferrite which is an iron bearing solid with a non-ferrous impurity, and subject to processing and disposal problems. Synthetic zinc ferrite was chloridised in a tube furnace. The gas atmosphere in the tube furnace resembled that of a fluid bed pyrohydrolyser and consisted of HCI, 1120 and nitrogen. Gas composition, temperature, residence time and sample mass were varied. The experiments showed that complete (99.6 per cent) zinc extraction from synthetic zinc ferrite was possible in a simplified pyrohydrolyser atmosphere at 1100 K in four hours. The zinc ferrite was converted into gaseous zinc chloride, and hematite and magnetite solids. It was also found that zinc removal from the zinc ferrite lattice caused not only rccrystallisation of the zinc ferrite into hematite, but also hematite crystal

Jan 1, 1993

By Kohra A, Shoji S

The amount of copper production by flash smelting process occupies about 17% (equivalent to 1.4 million t/year) of total free world production. In Japan, 650,000 tons of copper is produced annually by flash smelting. This is 65% of the gross copper production of Japan. To reinforce pollution control, promote energy saving, and enhance production efficiency by increasing the size of furnaces, conventional blast furnaces and reverberatory furnaces are being replaced with the flash smelters worldwide. The Ashio Smelter started copper production in 1884 and developed in association with the Ashio mine. In those days, the Ashio smelter produced copper by using the blast furnace process designed for the high-grade ore from the copper mine. At that time, this process was specialized in Japan. In 1956, for the first time in Japan, the Ashio Smelter introduced the flash smelting process developed by Outokumpu Oy of Finland (it is suitable for treating the copper concentrate, producing sulfuric acid and improving production efficiency). The flash furnace in Ashio, the first ever in Japan, had a capacity of 230 t/day for copper concentrate and was operated up to 1962. During this period, various operational troubles were solved, and further improvements were made; and, in 1962, a Furukawa-type flash smelting furnace was completed in Ashio. This improved version of a flash furnace had a capacity of 450 t/day. There was one flash furnace and one waste heat boiler, which were arranged in a unique pattern for that time. This furnace may be said to be the prototype of the present flash smelting process in the world.

Jan 1, 1987

By E E. Hall, S, E D. Thimons, R J. Timko

The heart of mine ventilation science and technology is the protection of the life and health of the miner. Lung diseases that result from overexposure to various mine aerosols can largely be prevented by maintaining concentrations below prescribed limits. Maintaining safe aerosol concentrations depends, in part, on our ability to know what mine aerosol concentrations are in a timely and accurate way. The Centers for Disease Control and Prevention (CDC), National Institute for Occupational Safety and Health (NIOSH) has been developing several new tools to help miners monitor respirable coal dust, silica and diesel particulate matter. This paper will discuss three main topics. First, the latest results of the person wearable dust monitor (PDM), developed by Rupprecht and Patashnick under CDC contract. The PDM was tested side-by-side with conventional samplers at a number of US coal mines and results indicated that the PDM was comparable to conventional samplers. Second, improvements to the dust dosimeter monitoring technique that includes a new pump with built-in pressure transducer and algorithm to convert differential pressure to dust concentration have shown good precision. Third, advances in the use of the detector tube technique to monitor tailpipe diesel emissions and ambient diesel particulate matter show that strong correlations exist between differential pressure measurement and elemental carbon in the samples.

Jan 1, 2005

By Alder KF

Nuclear power stations to be installed in Australia will be fuelled from Australian resources of raw materials. This will require the establishment of new manufacturing industries and the eventual expansion of established activities, especially in uranium mining and the preparation of precision metal products. This paper presents some predictions of the possible growth of nuclear power installations in Australia. These might amount to 4000 MWE by 1985 and 11,500 MWE by 1990 and towards the end of the century, about 50% of new generating plant might be nuclear. Predictions are given of the demands for materials (uranium and zirconium) and fuel manufacturing services for four reactor systems which might be considered in the programme. - The availability of raw materials and technical capability place Australia in a particularly good position to undertake the manufacture of nuclear fuel'; in addition to satisfying the domestic demand we should actively seek export markets for these products.

Jan 1, 1970

By Unver B

Longwall advance mining is still the predaninant system of coal extraction in the U.K., contribiiting to sane 70 % of underground coal production. Gate roadways providing access to a longwall advancing coal face are maintained adjacent to a rib pillar under high strata abutment pressures and the caving rock mass. It is very difficult to realistically model such access roadways using mathematical or numerical techniques and hence, predict roadway closure. For the past 15 years, a research group in Nottingham University has been engaged in the study of longwall gate roadway stability using observation methods. Gate roadway deformations have been measured in 224 gate roadways and a comprehensive data base has been established. The paper describes the statistical analysis of this database and presents sane. predictive equations which will enable a forecast of the gate roadway closure to he made. Further field work to validate these equations. is described together with an error analysis. The results are very promising and indicate that it is possible to predict gate roadway closure in the U.K. within practical limits of Accuracy.

Jan 1, 1986

By E Kunz

Decreasing the gas content in the worked seam by degassing before the start of winning has proven its worth in some areas of German hard coal mines. On the one hand, it removes the risk of gas/coal outbursts and on the other hand it reduces the gas inflow into the longwall. The underground experiences of the last 30 years have led to a æhit listÆ of coal seams with respect to their suitability to predegassing. Trials in the DMT laboratory and also results gained in the deposit show that the suitability of a seam for predegassing depends on its rank. In seams with volatile matter of 20 - 30 per cent, high efficiency ratings are achieved as a rule, with lower ratings both in seams with lower and with higher content of volatile matter.If the rock pressure is unusually high, the efficiency rating of the predegassing is lower, even in seams which would normally be suitable for this process. Under unfavourable conditions, for example below or above residual pillars, in-seam boreholes cannot be drilled successfully and the method is not practical. But if the worked seam was already stress relieved, the predegassing has an optimal efficiency. Latest investigations show that the distance between the in-seam boreholes can be extended. But in that case, the time necessary to reach the same reduction of the gas content increases considerably.

Jan 1, 2005

The art of flotation may be divided into two distinct branches, namely:-1. Collective flotation.2. Selective flotation.(1) Collective flotation is applied when all the valuable minerals in an ore are required in one concentrate, leaving ,only gangue minerals in the tailing. The method is applicable, for instance, to such ores as auriferous copper sulphides associated with gangue minerals only, or to silver lead ores low enough in zinc and other valuable minerals.(2) Selective flotation is applied when there are present in an ore two or more valuable sulphides, which cannot be subsequently efficiently treated unless they are separated from one another as well as from the gangue. For example, a silver-Iead-zinc ore, or a copper-gold-iron ore; where the iron is not required with the copper gold concentrate.In order to make these operations practicable chemical reagents have been developed, having power to exert definite actions on the various minerals when brought into contact with them in a water pulp.COLLECTIVE FLOTATION.In order to bring about collective flotation it is generally necessary to add to the pulp a frothing agent and an activator or activators for all the minerals which it is desired to float.SELECTIVE FLOTATION.The object of selective flotation is to activate the mineral which is to be floated, and at the same time to prevent all other minerals from floating.

Jan 1, 1936

Traditionally, the predominant drilling method in open pit mining has been large hole rotary drilling using cumbersome, inflexible equipment offering merely limited scope for improvements in pit design and overall costs. By contrast, the recent development of comparatively light high-pressure down-the-hole hammer crawlers has paved the way for new ideas and trends. High penetration rates coupled with superior mobility and fast set-ups contributing to substantial productivity gains have resulted in a renascence for this drilling method in open pits. The ability to cover a wide range of hole diameters and angles gives designers unique drill pattern possibilities especially when establishing steep and stable pit slopes. As pre-split holes, buffer holes and production holes all can be drilled by using the same equipment, there are, there are obvious advantages in production scheduling as well as in materials handling and service. This paper presents some case stories, which will demonstrate the benefits and improvements that the introduction of new drilling methods and equipment has brought to open pit mining operations.

Jan 1, 2003

The complexities of mining in current economic conditions, where ore extraction schedules are varied on a weekly basis so as to ensure constant supply to the process plant, can result in a number of scenarios that pose geotechnical challenges. This paper presents a case study where alterations in the mining schedule of a particular mine resulted in the necessity to mine under a large uncompacted embankment, ie integrated tailings and mine waste land form. To effectively ensure that ore recovery was maximised, a well-designed slope monitoring system to evaluate design performance and to provide timely warning of impending failures was imperative. In order for an appropriate slope monitoring strategy to be developed, a thorough understanding of the potential slope failure mechanisms, capabilities and limitations of available monitoring techniques is required. Communication of the monitoring results and response strategy to alarms generated by monitoring systems must also be carefully considered to maximise effectiveness. The results of preliminary stability modelling can be used to guide the design of a monitoring system, which in turn can then generate data which can be used to iteratively refine the geotechnical model. This paper illustrates the development and implementation of a slope monitoring system and associated communication system, using the Daydream embankment at Fortescue Metals Group's (FMG's) Cloudbreak Operations as a case study.

May 1, 2010

By Chang TS, Suzuki K, Go H, Nakamura S, Kuwano Y

In 1979, a test operation of an experimental blast furnace was carried out to investigate the behavior of a sort of formed coke, which was used safely by 30% of total coke charge in No.2 B.F., Sakai works, NSC, in 1975". The Mashec-type formed coke of 60 x 60 x 40 mm in dimension was crushed and screened so that it had the same size range (1011,20 mm) as ordinary coke used in the base operation. Preceding to the operation, some experiments on the properties of the formed coke and the effects of crushing on them were performed.

Jan 1, 1981

The world is getting flatter through internet, mobile phone technology, relatively low cost travel, massive outsourcing of manufacturing to China and the transfer of company backroom operations to India. In the iron and steel industry, however, things will remain relatively the same with slow gradual improvements in technology; only the geographic location of plants may change over time. Or will it? The blast furnace smelting process has remained largely unchanged since 1828 when James Neilson came up with the idea of preheated air being delivered to the tuyeres. Likewise, oxygen steelmaking that takes molten iron from such blast furnaces has remained conceptually unchanged since Sir Henry Bessemer invented an air-based system in 1856. These two processes are the core of integrated steel mills that we know today. Typically such mills consist of coke ovens, sinter plant, blast furnace, oxygen steelmaking, continuous caster, rolling mills and metal coating lines. In the intervening 150 years the only real disruptive technology to the integrated steel mill has been the minimill. Based on the use of the electric arc furnace (EAF), in conjunction with a continuous caster and rolling mill, the term minimill is used because steel products are produced at down to one-tenth the scale required for economic operation of an integrated mill, with the EAF producing molten steel using largely scrap steel as its feed, as against transforming coal to coke (coke ovens), iron ore, coke and limestone into molten iron (blast furnace) and molten iron to steel (oxygen steelmaking). There are, however, a number of technologies in development that may cause a paradigm shift in the way steel products are produced and perhaps push the evolution of the minimill as a disruptive technology. Two examples are direct iron smelting, where iron is produced in a matter of seconds by injection of ironmaking feed materials into a molten bath, and thin strip casting, where molten steel is cast into 2 mm strip or less, in similar time. Both have Australian connections. A leading iron smelting technology is the HIsmelt« process, which has its first commercial application at Kwinana, Western Australia, where a joint venture of international parties, consisting of Rio Tinto and the Nucor, Mitsubishi and Shougang corporations, are in the stage of ramping up commercial production. The leading strip casting technology is the Castrip« process that arose from development work done by then BHP Steel, with IHI of Japan, at Port Kembla, New South Wales in the 1990s. Nucor followed this work up, building the first commercial plant for the technology at its Crawfordsville site in Indiana in 2001 and has recently announced an intention to build a second plant in the USA. While both technologies are only into the early stages of commercialisation they are likely to change the face of iron and steelmaking as we know it over the next 20 years. This paper elaborates on the technology of the two processes, why they could change the face of the iron and steel industry forever, what might drive the rapid change and what the changes may look like.

Jan 1, 2006

I In an optical microscope, mild attack by cyanide solutions on various minerals can be observed by means of colour changes as well as etching patterns. However, the mineral may not be identifiable due to the coloured film. In some cases, a transfer algorithm between mechanical stages enables the surface-altered mineral to be identified in the SEM. A more severe attack may not be so informative, as it is not known whether the mineral attacked has been completely dissolved away. The leaching behaviour of some common minerals is described.

Jan 1, 1991

By Y Gu

Based on the mode of occurrence, gold is classified into three categories: microscopic gold, submicroscopic gold and surface-bound gold. Microscopic gold, or visible gold, refers to gold minerals in which Au occurs in a substantial amount, such as native gold and electrum. Submicroscopic gold, ie invisible gold, refers to gold contained in the structure of other minerals (mainly sulfides) in minor to trace amounts. Surface gold is the gold that was adsorbed onto the surface of other minerals during mineralisation and subsequent oxidation or metallurgical processing. Gold mineralogy has a significant impact on its extractive metallurgy. Gold process mineralogy helps address problems related to gold ore processing. It is widely used as a predictive and troubleshooting tool in gold ore processing, and provides useful information on process selection, flow sheet development, recovery improvement and reagent consumption optimisation. This paper will begin with the classification of gold ores, and will focus on gold mineralogy and how it impacts extractive metallurgy through case studies.

Jan 1, 2008

By Smith IEM

Some samples from arc-type volcanic suites collected in northern New Zealand and southeastern Papua New Guinea show rare earth element (REE) and Y abundances which are enriched relative to the those typical of their respective associations. This enrichment appears to be the result of an alteration process which selectively mobilises the REE and re-precipitates them as REE-bearing minerals in veins and interstitial patches. The alteration is on a micron scale and is not detected in routine petrographic examination. The spectre of REE mobility in young apparently fresh rocks is important to igneous geochemists who use REE abundances to constrain petrogenetic models and may also be important because it indicates the operation of a natural REE enrichment process which could operate in the formation of economic REE deposits.

Jan 1, 1990

Laboratory scale simulation experiments show that the adsorption capacity of Au(CN)Z- on activated carbon in the presence of organic plant contaminants is dependent on the particle size of the carbon. This observation suggests that fine carbon in a CIP contactor can protect coarse CIP carbon from fouling in a dirty CIP plant. A preliminary test of this concept was made using fine lignite coal as the organic scavenger in the presence of the CIP carbon Calgon GRC22 in an alkaline cyanide solution containing Teric 401, sodium ethyl xanthate and kerosene.

Jan 1, 1991

The principles and practical applications of the Mogensen Sizer are examined, with particular reference to the experiences at Coal Cliff Mine, New South Wales. The Mogensen Sizer has proven to be a worthwhile alternative to conventional screening. It has the flexibility and capacity to offer a useful sizing tool, particularly in areas of confined space. It is simile in design and 1 in construction.

Jan 1, 1984

By Krzystanek Z, Wasilewski S

The problem of automatic control of a coal mine ventilation network is discussed. It is found that the structure of the control sys-tem should have two levels, i.e. local regulation of ventilation para-meters (air flows) in faces to eliminate the effect of quick disturba-noes, and supervisory control of the whole ventilation process by pe-riodical modifications to the working characteristics of the main fans. Practical and theoretical problems connected with implementation of the system in Polish mining are listed and discussed. To solve these prob-lems a series of experiments with air flow control in three different coal faces were carried-out with the aim of checking the measuring and control equipment in a real mine conditions as well as investigatingthe gasodynamics of the ventilation process. The results of the experi-ments are analysdd, and used to verify the mathematical model of the gasodynamics of a longwall face.

Jan 1, 1985