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Because of the mineralogical complexity of nickeliferous laterites, most commercial and laboratory extractive processes require the ore to be blended to a feed of "constant" chemical composition. Even using the "constant" feed there are significant variations in processing behaviour within and between different feed lots. Chemical and mineralogical analyses of lumps of ore taken from the Yabulu stockpile of Queensland Nickel have highlighted the complex- ity of the ore making up the blended feed material. Each sample has been subjected to acid leaching and reduction/ammonia leaching tests and the results correlated with the mineralogical location of the nickel. The consequences of the variability in ease of leaching of the nickel are indicated.

Jan 1, 1978

By Thomson I. R R, Friday R. G, Palmer W. T

The paper introduces the problems encountered in designing open stopes and briefly examines the factors that determine the final stope dimensions achieved after mining is completed. A case study is presented where monitoring of a stope was considered necessary due to the expected formation of a highly stressed crown pillar above the stope. The influence, on the mining approach adopted, of a yielding crown pillar is discussed. Monitoring and numerical modelling were used to develop an understanding of the behaviour of the particular stope as mining progressed. A comparison between the measured displacements and the numerical predictions at an interim stage of mining was carried out to assist in choosing the final sequences involved in completing the stope.

Jan 1, 1981

The process of hydraulic transport through pipelines, world-wide well known for the trans- port of fine-grain solids is also being used to a greater extent in mining for the handling of 1rimarily coarse-grain solid - water mixtures r the removal of, for instance Coal and waste mixtures after coal winning rising hydraulic monitors, lings for backfilling underground and :her tailings and flotation waste to A large-scale test unit was taken into service at the Bergbauforschung GmbH (Mining P',search Company) in Essen-Kray, GFR, to ¦urther improve this technology. The unit was :fanned and built by Krupp Industrie- and +hibau of Duisburg in cooperation with i r

Jan 1, 1980

By Cocker A, Kavetsky A

A numerical model describing blast fragmentation and damage in three dimensions has been developed at the Julius Kruuschnitt Mineral Research Centre (JKMRC) and applied to numerous blasting operations in mines throughout Australia. The model combines the rock structure (summarised by block size distribution) with blast strain energy and uses comminution theory to calculate the resultant block size distribution. The model distinguishes between rock breakage and failure, the former being defined as size reduction and the latter as block dissassembly. The background and basis of the model are discussed in detail and three case studies presented describing the application of the model to explosive performance evaluation, explosive selection and drill selection in Australian mining operations.

Jan 1, 1990

The need to estimate the block size distribution of a jointed rock mass is of great importance in the design of blasting rounds to attain a pre- established fragmentation. Other Geomechanics topics, such as ,hydraulic behavior of rock-masses, as well as the determination of their strength properties, also require the accurate prediction of a rock-mass composition in terms of block size taking in due account the three dimensional interference of joints and other geologic discontinuities. In this paper, a method for computing the block size analysis of a jointed rock mass is described, using as input the common geologic data (dip and strike) of fracture planes existing in a rock bench prior to blasting.

Jan 1, 1977

By G W. Wilson

Rehabilitation of tailings impoundments is one of the most challenging aspects in mine closure, as not only does the potential for producing leachate pose a challenge to the rehabilitation designer, but also other aspects such as stability and settlement must be considered. The water balance of a tailings impoundment is unique in the sense that it usually hosts a pond that in turn causes a phreatic surface in the impoundment. The position of the phreatic surface defines the saturated and unsaturated zones in the impoundment, which of course varies spatially and temporally. Predictive modelling for this hydrologic system becomes difficult, as numerical models capable of analysing the combined saturated/unsaturated zones are not adequately refined to accurately solve the flux boundary problem for infiltration at the surface of the tailings. This paper describes the development of a flux boundary model that enabled accurate modelling of the unsaturated zone in the tailings impoundment at Kidston Gold Mine, Queensland, Australia. The technique made it possible to accurately predict the spatial variation of infiltration to the tailings as a result of the presence of the phreatic table. The conceptual model defines the boundaries for the Kidston tailings dam, based on a generalised cross-section through the dam. Firstly the shape of the top boundary is described as a function of the particle size of the tailings associated with particle segregation that occurs due to the hydraulic placement of tailings. This function was rigorously tested using in situ infiltration tests and laboratory materials testing. Defining the bottom boundary of the section, ie the phreatic level was done by physically monitoring the phreatic level with 42 piezometers strategically located on the tailings dam. Analysis of this data led to the fixing of this bottom boundary through the introduction of a function that mimicked the shape of the phreatic level. The material properties of the surface layer, specifically the saturated permeability that would govern the infiltration/exfiltration rates of moisture through the top boundary layer were defined on the basis of extensive field and laboratory material testing. A function for the saturated permeability was developed on the principles of particle segregation. Finally a procedure is described for the application of the new conceptual model for the evaluation of the spatial infiltration to a tailings surface using the rigorous one dimensional surface flux boundary code SoilCover. The solution of the calculation described above was then used as the top boundary condition in conventional three dimensional saturated/ unsaturated flow codes, and verified against measured seepage rates from the tailings impoundment under drains. It was concluded that the developed spatial flux function was in deed a most rigorous representation of reality. Although the methodology presented here was applied to the Kidston tailings impoundment only, the authors believe that the principles are directly transferable to any tailings impoundment that has a varying phreatic zone thickness due to the presence of a pond. The mathematical equations describing the typical cross-section would be site specific, but the approach and ultimate solution methodology would be directly transferable.

Jan 1, 2003

Structural assemblages of veins, shear zones, and wallrock alteration zones arising from fault-valve action on steep reverse fault systems are reviewed using observations from mesothermal gold-quartz lodes in the Archean Yellowknife, Abitibi, and Yilgarn greenstone belts of Canada and Western Australia, the Cretaceous Mother Lode system in the Foothills Metamorphic Belt of the western Sierra Nevada, California and the Victorian goldfield hosted in a folded quartz-turbidite succession of Paleozoic age in Australia. Despite differences in the host rock assemblages, the deposits have many structural characteristics in common. These form a useful exploration guide when re-evaluating comparable, but poorly described gold-quartz vein systems such as those in the Reefton area of New Zealand.

Jan 1, 1992

By Saghafi A

Spoil piles are produced routinely in open cut coal mines. Spoil piles may contain waste coal and other carbonaceous horizons. Coal and carbonaceous materials react with oxygen in the atmosphere, producing heat. If the rate at which heat is generated is greater than the rate at which heat can be dissipated, the temperature of the spoil pile rises. If the heating remains unchecked, spontaneous combustion can occur. Spontaneous combustion poses significant safety, environmental and economic problems if it should become established in spoil piles. Using the basic features of self heating in spoil, the use of model is directed toward developing quantitative prediction of spontaneous combustion in open cut coal mine spoil Piles.

Jan 1, 1998

By Beamish B. B

In this study, a systematic examination of the scale and variety of micro-structures in coal using Scanning Electron Microscopy (SEM) has been carried out, using coal samples of differing stages of coalification from the Bowen Basin and New Zealand. SEM provides detail of various micro-structural features and shows that a variety of micron-sized fractures and cavities are present in coals. These are differentiated into three pore types: fracture porosity, phyteral porosity and matrix porosity. Fracture porosity is generally associated with bright coals (although it has been shown that micro-fractures are present in maceral fragments from the dull coal layers). Characteristically the macro- and micro- fractures form a continuous structural fabric through the bright coal layers and thus make a significant contribution to overall permeability. The macro- and micro-fractures appear to have been formed during the process of coalification rather than being formed due to shrinkage during methane extraction, as most of them are infilled with secondary minerals. In contrast, phyteral and matrix porosity is associated with the dull coal layers that are composed of plant fragments or a heterogeneous mixture of macerals. Like the macro- and micro-fractures, the continuity of the observed cavities suggest that these too are a significant contribution to overall permeability, and therefore play a major role in the transmissibility of methane at a level between diffusion at the micropore level and laminar flow at the macro-fracture level. Due to different spacing, orientation and persistence of individual fractures and cavities, the rate of methane transmissibility through a coalseam will vary according to coal rank, coal type and the organic precursors from which the coal was derived. This is important as a knowledge of the micro-structure system and its relationship to coal type and coal rank, plays an important consideration in: a) gas drainage modelling, b) enhancing permeability by inducing fractures and c) predicting the occurrence of outbursts.

Jan 1, 1991

By G Partington

A regional scale prospectivity model was developed for Papua New Guinea (PNG) to identify areas of porphyry Cu-Au mineralisation. Weights of evidence modeling techniques were used to determine spatial correlations between porphyry Cu-Au mines and predictive maps created from available spatial data. These predictive maps were then combined into a final prospectivity map. Despite limited regional scale data the model has successfully identified areas of known porphyry mineralisation as prospective and has also identified areas where new mineralised systems may be discovered with further exploration. An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation.

Jan 1, 2008

With the use of 86 rock drills of the jackhammer type at the West Lyell Open Cuts of the Mt. Lyell Mining & Hailway Co., it is of importance to determine the economic as well as the physical life of these machines. With this purpose in mind records have been kept of the footage bored and the cost of new parts placed in each machine, and the following procedure adopted.A graph is plotted for each machine showing the footage bored as a horizontal line and at each 5,000 feet of boring the total cost of new parts noted on this line. (See l"ig. 1.) Thus at a glance it is possible to see... the amount of work done by each machine and the money spent on it in new parts. However, it is difficult to visualise from this graph the increase in the cost of new parts for each machine as its life advances. To obviate this difficulty a curve is plotted with the cost of new parts as the vertical component and the distance bored as the horizontal component. As before the cost of new parts are taken at each 5,000 feet bored. (See Fig. 2.) The curves so obtained are particularly interesting for two reasons:1. Each machine has its characteristic curve.2. The curve always steepens.Some machines are found to have relatively flat curves, others flat curves for approximately 15,000 feet of boring, and others steep gradients from the begining.This demonstrates that it is not always economic to discard a drill after it has been in service for a certain length of time or after it has bored a specified number of feet. Each drill has its own characteristics and so must not be regarded as one of a class, but considered on its own performance.The following use of these curve diagrams has been made to determine whether a machine has reached the end of its economic life. Figure 3 shows...

Jan 1, 1942

By K Osman, P Bennett

The mining of an underground orebody requires development both in waste and ore before stoping commences. Regardless of what metal is being extracted, the waste development is minimised to reduce the cost per unit of metal mined. At the Western Metals Zinc Kapok mine site, reducing the cost per tonne of lead and zinc mined is paramount. Decline waste development costs can be minimised by methods such as increased gradient or reduced drive size. Ore development will also involve some mining of waste. The degree to which waste mining can be minimised will depend on the thickness and dip of the orebody. The drive geometry will also determine the percentage of waste within the face. It is by mining methods such as resue mining that selective mining may be used to maximise the amount of metal mined and reduce waste dilution. Resue mining can be used around a set of selection criteria established by the mine site. These selection criteria will determine how resue mining can be applied to the mine site. Selection criteria include firing times, number of headings available, acceptance criteria for percentage lost metal, dilution and most importantly operator acceptance. The single pass or two pass resue mining method should be chosen depending on the site acceptance criteria and selection criteria. The Western Metals Zinc Kapok mine site has established a set of parameters which accept the two pass resue mining method for the mining of the ore drives. The blasting results from a single pass resue method were reviewed during more recent trials in a single heading. Through a comparison of results, the parameters allowed the decision to determine the applicability of resue mining and its current form to Kapok. This paper outlines the parameters set by the Kapok mine site, reviews these in relation to the two forms of resue mining and examines the criteria which make this mining method applicable for Western Metals Zinc.

Jan 1, 2002

Natural Gas has been available in New Zealand for twenty years. During that time the gas share of the energy market has grown and now natural gas forms a significant part of New Zealand's energy scene, helping consumers to achieve a higher standard of living, and reducing dependence upon imported oil.Natural gas is now used for petrochemical manufacture and power generation in addition to direct supply to consumers.As concern for the environment continues to build, natural gas will have an increasingly important role to fill in these markets. This paper sets out the background to the development of natural gas in New Zealand and identifies the current markets. It then looks at those matters which are likely to influence the role of natural gas in the 1990s.

Jan 1, 1990

Part of a four-year course in metallurgy, dealing with metallurgical process engineering, was designed for students to acquire knowledge and skill from physical science, metallurgy, process engineering, and social science. Principles of education, and guidelines obtained from a study of professional practice, indicated that students may learn effectively through a planned sequence of problem-solving exercises based on the diverse functions of metallurgists in industry. The more important characteristics of the curriculum and a few illustrations of the problems are included. An outline is given of the current procedures used to develop parts of the curriculum, and of the students' diffic- ulties and achievements.

Jan 1, 1984

By Spencer PA, Winborne DA

The Porgera mineral deposit in Papua-New Guinea contains gold as finely divided, probably submicroscopic (1 um) particles dispersed in a pyrite sulphide matrix. Only 25-30% of the gold in pyrite can be extracted by direct cyanide leaching and fine grinding the pyrite does not increase gold extraction significantly. This work is concerned with the application of alkaline leaching at atmospheric pressure to oxidise the pyrite prior to gold recovery by cyanidation. The paper presents and discusses results of a comprehensive set of testwork using sodium carbonate, sodium hydroxide and calcium hydroxide alkaline media. Best results, at 60-70% gold extraction, were obtained with sodium hydroxide systems.

Jan 1, 1984

By Dorricott M. G

Ballarat Goldfields NL is developing an exploration decline at Ballarat East using a Mitsui Miike S-125 roadheader. To-date, 530 in of advance has been achieved at an average rate of 16.1 m/week. Roadheader availability has averaged 94.3 per cent, and pick consumption has averaged 0.016 per m. Ground support has involved pattern rockbolting with split sets, 100 mm thick fibre reinforced shotcrete, and steel sets as required. The slower than expected advance rate has mainly been due to difficult ground conditions. It is expected that a further 970 in of decline will be mechanically excavated before a drill and blast system becomes more economical.

Jan 1, 1995

The rapid growth of world civilisation will have a significant impact on the way humans live in the future. As the global population increases and more countries demand a higher standard of living, the world must provide more food and greater energy and mineral resources to sustain this growth. The difficulty of doing this is compounded by three broad trends: the conversion of agricultural land to development uses; the increasing urbanisation of the world's population; and growing concern for the maintenance and improvement of the environment, especially regarding global warming and the impact of population growth. Underground space utilisation offers opportunities for helping address these trends.

Jan 1, 1993

AXTAT is a computerised system developed by the Western Australian Department of Minerals and Energy in conjunction with the local mining industry for recording and retrieving information about fatalities and work related injuries. Since its inception, the system has gained considerable recognition by consistently demonstrating its usefulness as a tool, not only to the Department, but for the entire industry nationwide. AXTAT has played an important role in the continuous improvement process in management of occupational health and safety in the Western Australian mining industry with gains in both human and financial terms, by regularly providing timely and accurate statistical feedback on fatalities and lost time injuries to industry.

Jan 1, 1996

By Hatherly P, Holt GE, McNally G

The current methodology for delineating and subsequently evaluating coal reserves is based on the use of vertical drill holes and surface based geophysics/geology. These techniques have three major problems, these being respectively:-a) Vertical drill holes can only provide a small sample of the coal seam and stratigraphy. Therefore the planar variation in coal reserve and environment parameters can only be approximated.b) Although surface based geophysics has had its fair share of success in recent years, there are still environments which have masked the finding of major structures.c) Access to drill sites is difficult at some locations due to mountaineous terrain, standing water and environmental impact.

Jan 1, 1985

A simple production technique has been initiated and implemented at Oaky Creek open cut coal mine to optimise recovery of coal from the relatively thin geological seams. The production technique is based upon minimising coal dilution through careful dragline operation and the selective use of mine mobile equipment to clean the top of coal. In addition, recovery of coal from the pits has been increased by refining blasting and dragline methods.The implementation of the recovery optimisation programme at Oaky Creek has provided significant economic benefits from increased yield through the preparation plant by the reduction in dilution, and from increased raw coal tonnage through improved pit recovery methods.

Jan 1, 1990