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By Lownds C. M

Several classes of commercial explosives and blasting agents behave non-ideally, especially in diameters near their critical diameter. A direct and convenient measure of non-ideal behavior is the detonation velocity (VOD); if the VOD is less than the ideal value, usually obtained by calculation, then the explosive is detonating in the non-ideal mode. Such lowering of the VOD is usually due to both lateral loss of energy and post-CJ release of energy. The second of these factors, namely slow release of chemical energy, is of most interest in blasting. While the observation of a low VOD clearly suggests slow reaction of part of the explosive composition, it does not necessarily mean that the energy is lost to the overall rock-breaking process. The partition of the energy of the explosive into various useful and wasteful categories is considered. Simple models of energy partition in blasting, and of explosive reaction kinetics, are presented. The models consider the effect of explosive type and rock type, the explosive being described in terms of the most common phases namely liquid, air bubbles, porous ammonium nitrate, dense or crystalline ammonium nitrate, and aluminum. Over a range of combinations of the above phases, the model predicts reasonable critical diameters and VOD's. Results are presented which show the effects of non-ideal detonation on fragmentation and heave in different rock types. Conclusions are drawn about those blasting conditions in which ideal behavior is beneficial, or Disadvantageous.

Jan 1, 1990

By S Holmes

Solid Energy New Zealand operates the Stockton Opencast Coal Mine, a unique deposit consisting of high quality hard coking and thermal coals. Stockton's uniqueness includes high variability of the shipment specifications, strict quality constraints, minimal stockpiling capacity in the coal transport chain and the variability of coal quality both vertically within the seam and laterally across the deposit. The process of resource proving and modelling results in a high level of understanding of the deposit to allow detailed planning to be undertaken. The use of computer aided mine planning tools is an important component of the mine planning at Stockton. Detailed planning is implemented in the field through selective mining practices and monitoring to minimise dilution and maximise recovery of the coal resource. The quality variability in the coal, the æjust in timeÆ approach of the coal transport chain and markedly varying quality specifications from shipment to shipment requires a large coal inventory and the mine to be driven by quality constraints rather than material movement capacities.

Jan 1, 2003

By M Olsson, I Bergqvist

A Swedish table of blast damage depths has, in one form or other, been in use since the late-1970s. Its history and the underlying theory are described. New experimental and theoretical findings that point out a number of shortcomings in the table and the underlying theory are presented and discussed. A revised version of the blast damage table was recently introduced in conjunction with new but incomplete recommendations for cautious perimeter blasting. The new table leaves the difficult task of taking into account factors like decoupling, water in the borehole, the rock properties, type of initiation, charge length and the actual bit diameter to the user. This paper discusses different ways of doing this, based on the experimental findings and a recent formula for the prediction of the lengths of radial cracks behind the half-casts. The material presented in this paper is meant to supplement and extend the new Swedish recommendations for cautious perimeter blasting of tunnels, shafts, pits and road cuts.

Jan 1, 2001

Elimination of zinc by the reduction of iron works dusts is examined. The process consists of blending, filtration, drying, balling, preheating and reduction in the rotary kiln. Dust slurries and dry dusts are mixed and stored in slurry basins and the blended slurry is filtered. In the balling process it is important to make green pellets which will withstand Thermal shock in the preheater and rotary kiln. Preheating to about 2000C is preferred to ensure effective use of coke fines in the blast furnace dust. The coke retained in the pellets accelerates the reduction rate. However, at the initial stage of the reduction the pellets become weakened and have to be heated slowly to prevent ring formation. In order to ensure zinc vaporization, pellets should be heated to a temperature of 1100-11500C in the kiln with injection of l ignite fines from the discharge end. Pellets having a degree of metallization of more than 90% and containing less than 0. 1% zinc have been obtained using a test kiln. The final pellet product is intended for use as blast furnace feed. A new plant with a capacity of 20, 000 tonne of dust per month is now under construct- ion and will be in operation next year.

Jan 1, 1974

Natural leaching of minerals has been recorded for some two millenia but surprisingly only in recent years has enough been known of the process for any serious design to be made. Copper has been recovered from natural mine waters since about the 17th century but again little progress was made in de- sign procedures until recently. Natural or dump leaching was started as a recovery process late in the 19th century and in the years up to the classic study of Taylor and Whelan in 1943 a series of impirical optimis- ations made it a valuable process for treating low grade or waste material. The biological nature of Sulphide leaching was proven by Colmer and Hinkle in 1947 and since then a large mass of data has accumulated on the microbiology, biochemistry, and response of ores to this form of attack. In spite of this knowledge and the vast amount of pract- ical experience available there are few recorded attempts to present methods of calculation or design procedures that can be used for setting up a leaching process. A framework is given here on which such procedures can be based and indications given of the inherent advantages and limitations of the process,

Jan 1, 1969

By C M. Hill

This paper aims to provide a brief overview of the Australian Coal Bed Methane (CBM) industry and more importantly the challenges to sustainable management of the industryÆs by-product, groundwater. In a country where water is scarce and having gone through one of the worst recorded droughts it is vital that this important industry be seen to be managing water in a responsible manner with the greatest environmental and social benefit. Benefits of the water from CBM wells can be enhanced through treatment to produce potable water for domestic or stock purposes, water for irrigation or aquaculture or lower quality or untreated water for industrial or mining purposes. Other options are re-injection of raw water or waste from the treatment processes or discharge to surface waterways. The critical change and difference between CBM projects and traditional oil and gas operations should be that where possible water is no longer disposed of via evaporation ponds with the dual legacy of waste of the water resource and an environmental contamination problem with the remaining salt and brine product.

Jan 1, 2003

Large scale open pit mining at Ok Tedi and Misima are described in this paper. The paper also presents the socio-political problems encountered in the construction, operation and waste disposal of high technology, high output gold and copper mines in very remote and rugged terrains. Despite these handicaps, mining companies from all over the world have established top class mining facilities including huge open pits, underground mines and mineral processing plants to extract rich mineral deposits of gold, silver and copper.Papua New Guinea is the sixth largest gold and copper producer in the world. New projects likely to come on stream before the end of this century would make it the world's third largest gold producer. The mining industry is the largest organised industry in the country employing over 10 000 persons and investing over US $1000 million on these mega projects per year.

Jan 1, 1992

This paper outlines the aims, objectives and means by which a life of mine land use plan was established for Comalco's bauxite mine at Weipa. Comalco realises the need to strategically plan for future mining activities and still minimise the impact of operations on the natural resources of the region. With this realisation long-term forward planning has been implemented to improve the Company's ability to select future sites for mining, industrial use, agriculture, town expansion and conservation purposes.The knowledge of mineral, water, soil and animal resources has expanded dramatically in the past decade. During 1990 Cornalco purchased Geographic Information System technology which has allowed previously collected resource data to be presented in map form. These maps as part of the Life of Mine Land Use Plan are both information based and strategic which can be efficiently updated. The maps allow a broad audience from engineers, geologists, environmental scientists and site managers to government officers and the general public to comprehensively view and scrutinise the operations.

Jan 1, 1992

Material hardness and environmental factors can limit or restrict conventional blasting techniques and this has led to advancements in the performance and efficiency of ripping. Not all materials can be ripped, however today's technology and experience can help make a reasonable prediction. A ripping versus blasting decision will depend on the total volume of material to be moved, the production capabilities and costs of the ripping tractor(s) and on the size and relative efficiency of drilling and Blasting.

Jan 1, 1995

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

An investigation was performed to determine the sequence of events which caused the 1987 surface subsidence and related damage to several homes in Walker County, Alabama, USA (see Figure 1). Surface affects compared to mine maps indicated the subsidence to be mine related. However, two coal seams had been worked under this area. The upper seam, the American seam ranged from 250 to 280 feet beneath the surface in the area in question. It was mined-out before 1955 by room-and-pillar method leaving in place narrow-long pillars to support the overburden strata, and abandoned in 1955. The lower seam, the Mary Lee seam, ranged from 650 to 700 feet beneath the surface. The Mary Lee seam had been abandoned in 1966 and subsequently became flooded. The dewatering of the Mary Lee seam workings in 1986 caused the submerged pillars to be exposed to the atmosphere. Due to multiple seam mining and the fact that workings had been inundated then dewatered, a subsurface investigation ensued to determine the sequence and ultimate cause of surface subsidence. Core sample tests with fracture analysis in conjunction with "down-the-hole" TV camera inspections provided necessary information to determine that the subsidence started in the lower seam and progressed through the upper coal seam to the surface. Evidence from the investigation program established that dewatering of the lower seam workings caused the marginally stable support pillars and the roof to collapse. This failure triggered additional subsidence in the upper seam which broadened the area of the influence at the surface.

Jan 1, 1992

Blasting is known to be both an important and an easily quantified cost factor in rock breaking operations. However, the indirect costs and benefits of the blasting operation are not easily determined due to the irreversibility of the mechanisms involved and the multiplicity of influencing factors. A general conceptual model showing the relationship between blasting and mining costs is well known, but serious attempts to address the critical real relationships have all floundered on the fact that not enough is yet known about either detonation physics or blasting effects. This can only be remedied to the extent that blasting instrumentation enables researchers to pin down not only the relationship between the detonation process and its impact on a particular environment, but also the downhill costs of handling the rock, repairing any damage and building in "Safety Factors" to provide for imponderables. It is vital to standaraize on specifications for instrumentation and measurement techniques and there is a need to review what has been achieved in blasting expertise so as to focus on the most fruitful paths for future work.

Jan 1, 1990

By D Craw

Interactions between structure and lithology in the Hyde-Macraes Shear Zone controlled the style of gold mineralisation at the Macraes mine. Large volumes of rock in some mine pits have most gold disseminated in hydrothermally altered schist, rather than in quartz veins. Mineralisation was initiated in the latter stages of metamorphism. Pods of massive schist rich in quartz and feldspar are surrounded by more fissile schist consisting of interlayered micaceous and quartzofeldspathic schist. Later shears have been partly controlled by the micaceous schist, and anastomose around pods of more massive schist. Micaceous schist was replaced by pyrite and arsenopyrite, accompanied by recrystallisation of phengitic muscovite under lower greenschist facies conditions. Gold occurs in sulfides and with microcrystalline quartz formed during minor silicification. Massive schist is locally mineralised along sulfidic microshears which have phengitic muscovite largely illitised under sub-greenschist facies conditions. Mineralised massive and micaceous schists were overprinted by cataclastic shears, with addition of graphite and more sulfides. Mineralisation occurred during a transition from ductile to brittle deformation regimes as the schist was uplifted in the late Jurassic.

Jan 1, 2004

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 Werner, J J. Donovan, A J. Morris

Coal mining in the Pittsburgh coal seam, in the eastern United States, began in the late-1700s. Since that time numerous mining technologies have been used throughout the basin. Environmental concerns, particularly mine discharge quality, have only been considered since the early-1970s. During the last 20 years, many of the larger underground mines have closed and are now either flooding or already flooded. In order to understand the consequences and potential future effects of this flooding, mine mapping of the basin has been compiled utilising a geographic information system (GIS) with an emphasis on locating barrier pillars between mines. Mine flooding has been monitored at numerous sites utilising pressure transducers and data loggers. These data have been combined with historical data from mining companies and structure contour maps to yield chronological flooding maps of the basin from 1980 to present. Utilising these maps and the indicated flooding rates, future discharge locations have been identified along with estimates of when these discharges are likely to occur. Related work has identified barrier pillar hydraulic conductivities and vertical infiltration rates as a function of overburden thickness. All of this information has been integrated into a groundwater flow model that simulates mine flooding. This model is useful in defining mine to mine interactions as the various mines fill with water, and the testing of various flooding scenarios. The model will be used in evaluating mine discharge rates and evaluating the options for regional mine drainage treatment.

Jan 1, 2003

By J Vann, S Jackson, O Bertoli

Ordinary kriging and non-linear geostatistical estimators are now well accepted methods in mining grade control and mine resource estimation. Kriging is also a necessary step in the most commonly used methods of conditional simulation used in the mining industry. In both kriging and conditional simulation, the search volume or ækriging neighbourhoodÆ is defined by the user. The definition of this search can have a very significant impact on the outcome of the kriging estimate or the quality of the conditioning of a simulation. In particular, a neighbourhood that is too restrictive can result in serious conditional biases. The methodology for quantitatively assessing the suitability of a kriging neighbourhood involves some simple tests (which we call æQuantified Kriging Neighbourhood AnalysisÆ or QKNA) that are well established in the geostatistical literature. The authors argue that QKNA is a mandatory step in setting up any kriging estimate, including one used for conditioning a simulation. Kriging is commonly described as a æminimum variance estimatorÆ but this is only true when the neighbourhood is properly defined. Arbitrary decisions about searches are highly risky, because the kriging weights are directly related to the variogram model, data geometry and block/sample support involved in the kriging. The criteria to look at when evaluating a particular kriging neighbourhood are the following: the slope of the regression of the ætrueÆ block grade on the æestimatedÆ block grade; the weight of the mean for a simple kriging; the distribution of kriging weights themselves (including the proportion of negative weights); and the kriging variance. Outside of the technical geostatistical literature, there is little in the published domain to describe the nature of QKNA and no practical presentation of case examples. In this paper we attempt to redress this by setting out the calculations required for QKNA and defining some approaches to interpreting the results. Several practical worked mining case examples are also given. Finally some comments are made on using the results of QKNA to assist with block size selection, choice of discretisation and mineral resource classification decisions.

Jan 1, 2003

By Murray G

This paper outlines the processes involved in acid generation from sulphides and the key factors in identifying and predicting time dependent changes in the nature of acid mine drainage (AMD). The initial characteristics of mine water; whether drainage from exposed mining faces, runoff and seepage from waste dumps or seepage from process tailings; do not necessarily reflect the long term potential for AMD. The ultimate quality of mine drainage is a function of the interaction of many chemical, physical, biological and engineering (operational) factors. Techniques are available that can predict the qualitative nature of acid generation and mine drainage quality but accurate quantitative predictions are essentially impossible at the present time. As more and more mining operations exploit sulphide ore, the AMD and acid waste issue will become a. far greater concern. The significance of time dependent factors in the production of acid mine drainage-.is not just restricted to particuL.ar mine sites but needs to be recognised by the mining industry as a whole.

Jan 1, 1988

By Deutsch G. P

The output of an underground mine often depends entirely on the mine winding system. -Decisions made--at the design stage affect the economy and operation'of the mine'.througb -its entire life. A modern mine winding installation is an integrated system and its design requires a multidisciplinary approach including expertise in the-materials handling, mining, mechanical, civil, structural, electrical and control engineering fields. The paper-sets out the elements of typical mine wind- ing systems-and describes some of the more important decisions which must be made during the planning and design process, It is no longer.adequate to. base the choice of a system on the pre- ferences and experiences of individuals. Major Australian winding install- ations are usually designed on the basis of overseas experience and some of the detail design is often carried, out overseas. Differences in basic design criteria occur from country to

Jan 1, 1973

The patented "Epytensic" pump of Minnovation Ltd, a multiple piston pump, is used widely on shearer loaders and by partial high pressure watcr jet cutting strategically in relation to cutter picks not only improves cutting rates, but saves power and increases the life of gearboxes and picks, as well as improving dust suppression. The "Face Side Pump", also a piston pump, located on the ranging arm gearhead has advantages over gateroad pumps and shearer body pumps. The "Extraction Drum", hydraulic air mover system, linked with the above innovations and high pressure water, have further advantages in methane and dust removal. Some modifications providing these systems need workshop applications but most are possible underground with minimal changes to shearer profiles and advantages of minimising hosing, along with the other advantages stated.

Jan 1, 1991

By Naik J. S G

The plant practice plays an important role in production and productivity. Men, material and machinery have to be judicially utilised to achieve maximum output with minimum cost. Improvements in technology should be incorporated at an appropriate time and place. The personnel concerned should be properly trained and motivated to receive the changes in machinery and technology. Strict adherence to prescribed parameters, optimum utilisation of man, machinery and operating supplies help in the smooth functioning of the plant and in achieving maximum gains.

Jan 1, 1992