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A numerical model of the spontaneous combustion of coal has been developed and is being used to investigate the nature of self-heating in underground coal mines. Results to date confirm the complexity of the self-heating reaction in coal and illustrate the impact of the factors such as the coal reactivity, mass and airflow through the coal pile. Subtle differences in the chemical, physical and environmental conditions and make a significant difference in the development of a high temperature self-heating or a low temperature benign condition, the subtlety escaping normal underground observations. Additional work is planned to investigate the thresholds for such factors in the development of spontaneous combustion and it the implications for detection by gaseous Products.

Jan 1, 1998

At the LKAB, Iron Ore Mine, Kiruna, Sweden a preliminary investigation into the reliability characteristics of a fleet of load-haul-dump machines has shown that the hydraulic system is one of the most critical parts. Therefore, hydraulic system was selected for study and analysis through condition monitoring devices so that failure can be controlled or at least the failure consequences can be minimized.The hydraulic system has two different problems; one is that the contamination level is too high and the other is high temperature during operation. At high temperature, seals and tubes are a problem, because they stiffen due to carbonization, which leads to increasing leakage. The pumps and restrictions were responsible for the main temperature increase.

Jan 1, 1991

By Eyers G. C

Long Shaft was initially developed using a rail haulage system on every working level comprising battery electric locomotives and granby trucks loaded by rail mounted rocker shovels. Production was commenced using conventional hand held cut and fill mining methods. In an effort to improve productivity and reduce operating costs a mechanised cut and fill stoping method evolved to suit the wider sections of the orebody. To further improve productivity and reduce costs the mechanised levels of the mine are progressively being redeveloped to enable the use of trackless diesel haulage equipment. An added benefit of trackless haulage equipment will be the ability to place development mullock into stopes as Fill.

Jan 1, 1988

Good morning. I am very pleased to be invited to present the Opening Address to this inaugural New Zealand Minerals & Mining Conference. It is indeed a pleasure to see so many representatives of this industry, which is so important to New Zealand's economy, present here today.   I extend a warm welcome to all delegates, particularly those from outside New Zealand. To those of you who have travelled from offshore, please closely observe our industry, and do not hesitate to ask Crown Minerals staff here for any further information you may want. I trust you will soon come to the same conclusion that my two following speakers have; that New Zealand is a good investment destination, and further that many of you will decide to invest in New Zealand's minerals and mining industry.   In New Zealand the minerals industry - minerals, coal and petroleum - together constitute an approximate $2.5 billion per year business. In broad terms this is about 3% of our Gross Domestic Product.

Jan 1, 1997

By S F. Simmons, A McOnie, J L. Mauk

Three cross sections, 200 m apart, display the distribution of indicator hydrothermal minerals across the Empire zone of the Golden Cross epithermal Au-Ag deposit, Waihi, New Zealand. These minerals are used to interpret the temperature and composition of hydrothermal fluids. The distribution of interstratified illite-montmorillonite and illite indicate that temperatures ranged from 140 to >220¦C, with temperatures above 220¦C predominating. The mineral assemblage of quartz-adularia-chlorite-illite-calcite-pyrite envelops the Empire vein system and stockwork, and reflects formation from an alkali chloride water whereas the mineral assemblage of replacement calcite-interstratified illite û montmorillonite-kaolinite forms a carapace and reflects formation from a CO2-rich steam-heated water. Alkali chloride waters appear responsible for the epithermal Au-Ag mineralisation.

Jan 1, 1995

By Binns RA, Murao S

The PACMANUS and Jade deposits are two active hydrothermal fields that are forming massive sulfide deposits at the Pacific rim margin. Both are associated with felsic submarine volcanic rocks and both occur in back-arc settings. However, PACMANUS is associated with almost sediment-free dacites and lies on the crest of a volcanic ridge, whereas Jade occurs in a heavily-sedimented tectonic depression associated with a basement of pumiceous rhyolite. The PACMANUS deposit is richer in Cu and Au, and Jade in Pb. Zinc, Ag, As and Sb contents are similar. Sulfide textures at PACMANUS suggest formation of Cu and Zn sulfides by simultaneous double-diffusion involving inwards-moving seawater mixing with outwards-moving hydrothermal fluid. By contrast, at Jade there is a more complex history of formation where initial growth of barite on the sediment surface, probably associated with microbial activity, formed an impervious cap which trapped higher temperature hydrothermal solutions.

Jan 1, 1995

By Richardson F. A

Techniques for flotation optimisation were investigated at Cobar [lines Pty:Ltd., in anticipation of the proposed installation of a computer and on-stream analysis. Successful laboratory and pilot plant tests for flotation performance optimisation using the Simplex Evolutionary Operation Technique (Simplex) lead to a full scale plant test using this method. The index developed for" Simplex response evaluation of flotation performance was based on metallurgical and economic criteria. This index was further modified to minimise the effect of head grade fluctuations. The test program was carried out on one of two parallel copper flotation circuits to allow comparison with normal "manual" operating control, and was conducted for thirty eight shifts. Results from the test section operating under Simplex direction were superior to those obtained using normal "manual" operating techniques and demonstrated the use of the Simplex Evolutionary Operation Technique as a method of reducing reagent consumption in flotation but, at the same time, maintaining satisfactory metallurgical performance. Experience in the use of the technique indicated the need for modifications to the rules of Simplex operations. Modifications were proposed, tested and appeared satisfactory.

Jan 1, 1973

The future of the Tasmanian mineral industry can only be estimated from a knowledge of the past, and armed with this knowledge an orderly plan for the future can be developed. Brief mention is made of the major historical developments through to the present day, with past and future development areas clearly mapped. Areas of importance which have been discussed are divided into the mining of metals, fossil fuels and non-metals; and the process- ing and extractive industries. Discussion then follows on the current general non-insular pressures on the mining industry, the energy crisis, scrap, world shortages, new techniques, inflation, and the effects of exploration on the environment. This is then followed by a discussion of the advantages of Tasmania as a mining state and a cataloguing of the present exploration and some possible areas of future development. From this a suggested plan emerges for the future development of the Tasmanian mineral industry, to incorporate the latest technological advances and by planning to meet the challenge of survival and growth in a turbulent environment.

Jan 1, 1977

By T Baard, A Pieters

This paper deals with the design and implementation of a 17 MW (nominal) surface cooling installation at Impala Platinum No 14 shaft located in Rustenburg, North West Province, South Africa.The cooling requirements included the installation of a surface ammonia refrigeration plant complete with the storage of hot and cold mine service water for underground use. It was also necessary to install a surface bulk air-cooling facility, which cools 400 kg/s of ventilation air going to the underground workings. Primary cooling is to the surface bulk air cooler. The cooling duty of a surface bulk air cooler is heavily dependent on the ambient wet-bulb temperature. Because of the daily wet-bulb temperature variation in this part of the world, use was made of a cold thermal storage facility of four million litres. The excess chilled water is stored during the night, for use by the main drilling shift during the day. This keeps the refrigeration machines as close as possible to full load during the summer, thus maximising the use of the capital expenditure. This paper discusses the control philosophy used to maximise the cooling output, as well as the thermal process. The project consisted of two phases resulting from the underground development phases of the mine. The first phase started in January 1999 and was commissioned by the end of the same year in record time. The final commissioning of the second phase took place at the end of 2002. The most difficult part of the construction phase was the tunnelling of a subsurface air duct from the bulk air cooler to the operating vertical shaft. This was done without disruption to the hoisting of men, material and ore in the shaft. Owing to the size of the refrigeration machines, the ammonia quantities involved and the application on a mine (no ammonia can go underground, either in the service water or in the mine air) special precautions had to be taken. South Africa has developed high standards for ammonia refrigeration plants used on mines, which will be partially dealt with in this paper.

Jan 1, 2005

By R Hindstr÷m

The demand for iron ore has increased dramatically in the last years and is forecast to remain on a stable high production level for years to come. ItÆs expected that the world economy is facing a stable continuous growth of iron ore to two billion tonnes and more over the next decades (Beddows, 2007). Furthermore it is expected that the existing and known high-grade ore resources will decline, and the iron ore industry will be forced to implement more and more advanced beneficiation plants. As a consequence of the more complex beneficiation requirements, there will be a need for modern solutions for iron ore dewatering that are reliable mechanically as well as cost effective and with high capacity per unit at the same time. Conventional vacuum filtration methods have been the most prevalent in fine iron ore dewatering. Product quality needs, lower ore grades, complex mineralogy and energy costs have resulted in iron ore producers seeking better solutions for dewatering, in particular pelletising feed. New advanced filtration methods have been introduced to the market. This paper describes how these modern methods are answering the needs of the industry. Performance of advanced dewatering technologies (pressure filtration and ceramic capillary action filtration) for iron ore applications has been studied, and the findings are based on both industrial and pilot scale experiences on different materials. For example, the results show that the cake moisture content of iron ore pelletising feed can be optimised more effectively by using modern filtration technologies. By selecting the most suitable and adjustable equipment, the effects of variations of feed material on downstream processes can be minimised and the possibilities of processing more difficult raw materials to high-quality pellets are better. The Larox Corporation develops, designs and manufactures industrial filters and is a leading technology company in its field. Larox is a full service solution provider in filtration for separating solids from liquids. As such, this paper compares the new developments in this market area with the prevailing known vacuum filtration technology, but focuses on a comparison between capillary action filters and rotary vacuum disc filters (RVDF). The trade name CeramecG is used to differentiate the Larox filter from the generic term.

Jan 1, 2007

By Pollard D. M

In the batch phase disengagement test, an organic and an aqueous phase are mixed together for a known period to produce a dispersion which may be either organic continuous (aqueous phase droplets) or aqueous continuous (organic phase droplets). The continuity of the dis- persion will depend upon the method of init- iating the dispersion, the conditions under which the system is operating, such as temper- ature and impeller speed, and the properties of the liquids, such as viscosity, inter- facial tension and solute content. Once the dispersion has been agitated for the required period, the agitator is turned off and the position of the coalescence interface and the sedimentation interface recorded as a function of time. This will produce a plot similar to Figure 1, where the overall dir- ection of travel of the droplets of dispersed phase is away from the sedimentation inter- face and towards the coalescence interface where the droplets coalesce with the homophase.

Jan 1, 1987

By Meyer T

Sunburst PCF (Penetrating Cone Fracture) technology has recently undergone extensive underground field trials at Leinster Nickel Operations, Western Australia. Trials with the Sunburst machine started in September 1994 and continued through to December 1994 during which approximately 130 metres of tunnel were developed. The Sunburst technology was used to excavate sub-levels through ultramafic nickel ore for future sub-level caving operations at the Perseverance nickel mine. The Sunburst machine demonstrated reasonable instantaneous advance rates, however, there are still a number of future developments/design changes which need to be addressed prior to the PCF technology being trialed again in a production environment. This paper benchmarks conventional drill and blast at Leinster against the Sunburst Excavator machine performance within similar tunnel dimensions and rock conditions. In addition to productivity and cost information; environmental considerations, support and labour requirements are also discussed. Problems with the current machine design are highlighted and possible future design changes are suggested. The Sunburst machine could be a suitable technology for advancing development through weak to moderate rock conditions and may also reduce overall support costs. With the potential for automation and the ability to reduce rock damage into the development tunnel walls, it is proposed that the Sunburst machine warrants further consideration.

Jan 1, 1995

In the early ages man contented himself with the use of such tools and appliances as would assist him in the enlightenment of his labours. With the advancement of science, numerous motives, with modifications and adaptations, have been introduced to enlighten labours, and in many cases have taken the place of man, but it can hardly be said that this applies to shovels, although one of the oldest implements of labour; certainly, with the introduction of the steam shovel the labours of man have been considerably reduced, but the hand shovel of today is used similarly to that of years ago.If the principle of the hand shovel has not been improved upon, it must not be suggested that the manufacturers of this article are not endeavouring to improve its quality, and the main point with which the manufacturers have to contend is the production of an article which will give a maximum of durability combined with a minimum of lightness. In order to accomplish this they must select suitable material, and subject it to such heat treatment process that will produce a shovel having a maximum of hardness and toughness without being unduly brittle, and which will withstand the excessive wear to which it is subjected.In this article an endeavour will be made to explain (a) the manufacture of shovels; (b) the defects commonly met with-the cause of same and measures which are necessary to remedy them.Before doing so a brief description will be given of the class of steel used for shovels; this is an important factor, and a steel which is admirably suitable is a plain carbon one containing approximately 55 - 70% C., and closely resembles that used for the manufacture of railway rails. This plain carbon steel is very extensively used, although at present alloy steels are being utilised to a certain extent for shovel manufacture, and with suitable heat-treatment.

Jan 1, 1926

By A J. Moore

To control the airblast from blasting to regulatory limits at environmentally sensitive sites near the Collinsville Coal Mining Operations, it has been necessary for Thiess Mining to incorporate a wavefront reinforcement analysis model in the predictive environmental airblast design. Controlling airblast from cast blasting 70 m high faces with 2000-3000 kg of explosives per hole within 700 m of houses presents a considerable challenge to the blasting personnel. This paper describes the model used and summarises the results of an investigation designed to quantify the increase in airblast indicated by wavefront reinforcement diagrams to further calibrate the model for future prediction.

Jan 1, 2004

Although this is a symposium on "The Occurrence, Preparation and Use of Australian Black Coal", I do not think that, in these days, any of the main energy resources can be considered only in terms of country of origin or only by itself in isolation from other energy resources. Accordingly, I propose to comment on solid fuels generally in the world energy scene, and make some brief references to Australian solid fuels, and to some other matters in the latter part of this paper. In this address I am drawing heavily on the 1974 survey of energy resources published just recently by the World Energy Conference. I do this for a number of reasons. Firstly, the survey is the latest and most comprehensive publication of its kind; secondly, it is the result of several years' work by a panel of eminent people, from all the energy industries and from some 16 widely spread countries; thirdly, substantial assistance was given by the U.S. Atomic Energy Commission in its compilation; and, finally, to let all know of the existence of the book, as I believe it to be a source document for all those interested in world energy resources. The United Nations "J" series of statistical papers provide important information on the annual production and consumption of and trade in the various forms of energy. In their respective areas, these two publications are primary information sources. Our present sources of energy throughout the world are fossil fuel deposits (coal, oil, gas), nuclear materials, water, geothermal, solar and tidal - but we are at present heavily dependent upon the natural stores of non-renewable fossil energy resources. Fig. 1 shows the changing use of energy resources in the present century. A comparison between 1900 and 1973 shows clearly the shift which has taken place.

Jan 1, 1975

The far reaching consequences of designing pillars for coal mines, while retaining concern for safety and economics, are cause for the search for refinement of the existing engineering methods to continue. Coal pillars, while having various functions within the overall mine plan, are the basic structural elements that assure the stability of a mine. Reliable coal pillar design methods take into account criteria which the pillars should meet in specific applications. These applications include typical mining situations such as the partial extraction room and pillar method with and without subsidence considerations, high extraction rate room and pillar, longwall mining chain pillars, and barrier pillars. However coal pillars are onlyu one element of a three element roof-pillar-floor system, weakest element of which system usually determines the stability of the excavations; however, the mining engineer can ony change dimensions of a pillar, properties of the surrounding strata remain beyond his control. The state of the art approach in pillar design places emphasis on recent developments in research. A widely encountered problem in certain coal fields is where pillars are underlain by weak floor strata. The resultant pillar design constantly maintains the perspective of the reliability of the design.

Jan 1, 1991

By Fallins J

THE John Darling Colliery, owned by The Broken Hill Proprietary Company Limited, is situated 12 miles south of Neweastle, NSW and about 1 mile from the ocean. The area of the holding is approximately 10,000 acres, about half of which underlies the Pacific Ocean. The area was proved to be coal bearing by diamond drill boring: this method not only proved the coal to exist, but gave the depths from which could be calculated. It also proved the existence or otherwise of heavy faulting, which is a very important factor in the design of the underground lay-out of a mine. The location of shafts had to be carefuIly studied, and, before final selection, the following salient points had to be considered:Railway communications.Flood waters.Boiler feed water.Surface buildings.Probability of coal washing.Underground haulage arrangements.Lengths of roadways from a ventilating viewpoint.Before the shaft sites were finally selected, an underground design was prepared to determine the direction of the main drives in relation to the boundaries of the holding, and the of the coal seam: the latter, being an important factor in this particular locality, was ascertained by a geological survey of rock outcrops in the neighbourhood. Size of shafts was the next subject for consideration. This was determined by output, number of seams to be worked, amount of ventilation required, and, on...

Jan 1, 1930

By Tonegato S, Wood M

The lack of objective data on roof bolting machines, bits, rods and overall system has created the need for an objective assessment of roof bolting. This work outlines a test rig for such objective assessment of component parts of the roof bolting system.

Jan 1, 1986

By Gao K, Wu C, Langley J. M, Waugh B, Farrell K

The dissolution of carbon from carbonaceous materials into molten iron is a key step in various ironmaking operations. For example, in new direct smelting processes, carbon in the form of coal is injected into the molten iron bath, which leads to the dissolution of carbon. In foundry operations, typical recarburizer materials can range from high purity graphite to chars. The dissolution performance of these" materials is critical to the operation and could dictate the efficiency and economics of the process.Dissolution kinetics has been studied by various investigators to explain the influence of melt conditions and carbon type (Sahajwalla et al, 1994; Shigeno, Tokuda, and Ohtani, 1985; Orsten and Oeters; 1988; Ganguly and Reid, 1992; Wright and Taylor, 1993). The influence of melt sulphur content on the dissolution kinetics has been characterised (Sahajwalla et al, 1994), with sulphur retarding the rate of carbon dissolution. The carbon dissolution from different sources is seen to vary significantly even under similar melt conditions. This observation has been explained by investigators on the basis of the varying ash content present in the carbonaceous materials. However, ash content alone cannot account for the variability in dissolution kinetics reported in other studies. One such study is presented below.In a recent study (Sahajwalla et al, 1994), pulverised carbonaceous materials were injected into the molten iron bath and the" dissolution kinetics was established. The dissolution of graphite and glassy carbon, which contain almost 100 per cent carbon, was seen to be significantly different when the molten iron contained sulphur. The influence of melt sulphur content was explained on the basis of different wetting behaviour observed.Importantly, the study showed that even pure carbon sources dissolved at significantly different rates. Hence, their performance could not be explained on the basis of ash content.The key difference between graphite and glassy carbon is in their atomic structure. Graphite is highly ordered whereas glassy carbon has relatively poor ordering in its atomic structure. This study showed that the atomic structure in carbonaceous materials can have a significant effect on their dissolution performance.The focus of the present investigation which stems from the past study described above (Sahajwalla et al, 1994), is to investigate the influence of atomic structure of carbonaceous materials on their dissolution into Fe-C-S melts.The specific objective of this study is to determine the relationship between dissolution kinetics and crystallographic character of carbon sources. In order to accomplish this goal, a range of different materials representing a spectrum of carbon sources have been chosen for the investigation. These materials include brown coal char, two types of Auscarb (A and B), and commercial graphite. Auscarb is prepared by calcining Auscoal at 1000°C. Auscoal is made from chemically cleaned Australian coals (Bowling, Chandler and Waugh, 1990). Part 1 of this paper details the dissolution performance of the materials studied, while Part 11 describes the X-ray diffraction study. The relationship between the atomic structural dimension and dissolution rate constant is discussed in light of the results obtained.

Jan 1, 1996

By T Goswami, M Edmondson

Henry Walker Eltin (HWE) are the mining contractors for Gloucester Coal at Stratford mine, which is in an environmentally sensitive area in the Avon Valley, NSW, Australia. Normal blasting at Stratford is done in a æstand upÆ or æbox cutÆ mode to suit the truck and shovel operations. Recently an opportunity of doing a throw blast became available when part of a ramp had to be blasted to accommodate changes to the pit design while not damaging the remainder of the ramp. The objective was to maximise throw into the void in order to minimise excavation costs by reducing the amount of overburden to be moved by the excavation fleet. It was necessary that the best result be achieved while staying within the vibration and airblast limits at a neighbouring property and nearby township. Both objectives were achieved through the application of OricaÆs knowledge of blast design, modelling and i-konTM electronic detonators. The i-kon system was used because of its known benefits in cast blasting and environmental control. The i-kon system provides the blaster with much greater accuracy, control and the flexibility to tailor blast designs. It has been found previously to enhance blast throw and provide cleaner high walls (Brent, 2002). The blast was a success, producing a muckpile with a high degree of looseness and consistent fragmentation, with an average throw to final spoil position of 37.5 per cent. This was achieved without any environmental exceedance. In addition, high speed filming showed that the coal edge had remained largely in place, indicating minimal coal loss. The results exceeded the expectations of HWE Stratford and the overall cost savings to HWE Stratford from this blast were recognised to be substantial. Further throw blasting opportunities at Stratford have been followed using the i-kon system to maximise benefits.

Jan 1, 2003