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By Schonert K

The throughput of a HP-roller mill is determined by the acceleration of the feed material within acceleration zone and introduction into the compression zone. Both processes depend on the internal friction and the friction of the material on the roller surface which is influenced by the surface structure and adhering of material. The particle motion in the acceleration zone has been investigated with high speed videos showing the effect of the centrifugal force and the slip on the roller surface. The throughput is discussed in the term of the specific throughput which can be approximated by a linear function characterised by the throughput number and the throughput elasticity. The throughput number is a helpful measure for investigating the influence of the feed material and the surface structure. The experimental results give some guidance for chosing an optimum corrugation profile.

Jan 1, 1993

By Lama R. D

The Australian underground coal mining industry is undergoing major changes. This paper analyses the technologies presently being researched in mines, and discusses their utilisation as major contributors in the underground mining of coal in Australia over the next 20 years. It describes the problems that underground mining of the year 2000 will face and the possible solutions to those problems based upon results of present day research. Methods, equipment and organisational requirements are outlined. Developments in micro-electronics, computerisation and monitoring will require a new look into human resource development, education and training, and organisation to meet the challenges of the 21st century. The mining system's philosophies of the future are Outlined.

Jan 1, 1986

The nickel operations at Kambalda consist of mining thin massive to disseminated Ni sulphide orebodies from 10 individual mines of variable grade.Daily sampling involves visual estimation of the grade of working faces based on geological parameters. This system of grade estimation is used as a guide for daily grade control only.Nickel metal allocation is based on an external sampling system. As all ore sources are blended at the primary crusher, only one calculated mill head grade is available. Therefore all sources are sampled prior to crushing. This system historically consisted of mechanically grab sampling ore from trucks as they passed over a weighbridge on arrival at the concentrator. Currently the system involves diverting one out of every ten trucks to its mine sample stockpile, which is crushed through the primary, secondary and tertiary crushing system fortnightly. The individual mine grades are re-combined to create a total sample grade. This is reconciled against the calculated mill head grade. The reconciliation factor is applied uniformly to all individual mine sample grades to calculate mill reconciled mine grades.

Jan 1, 1990

By P Dare-Bryan

Many mines have an interest in improving fragmentation at their sublevel caving operations in order to produce better ore recovery, lower dilution and less overbreak. The primary requirement for the extraction phase is to understand and optimise the flow of the fragmented rock in the rings including interactions with the caved material. Rock fragment formation is critically controlled by the blasting phase and can potentially be improved by optimising the dynamic energy distribution throughout the ring through the crafting of explosive charging, priming position and initiation timing. The modelling of fragmentation and damage due to explosive loading of complete rings is inherently and irrevocably a three dimensional problem that is difficult to address. We have therefore initially utilised an analytical code to predict vector peak particle velocities and energies that are restricted to the plane of a ring. Dynamic energy distributions based on common timing and priming practice have been compared with other possibilities using conventional pyrotechnic detonators as well as initiation designs based on accurate electronic detonators. The energy distribution can be quite subtly tailored to increase energy in appropriate regions or to decrease energy in the brow region for example to potentially reduce instability and the probability of misfires. We have also recently developed the capability to efficiently model particle flow using four-sided polygonal elements. Despite the 2D limitations of such a model this results in more realistic fragment interaction and stacking than can be achieved using conventional rigid circular elements. Modelling of a typical sublevel caving ring utilising these elements activated by the correct dynamics offers considerable potential for understanding the influence of the blasting energetics and timing on the complex flow and extraction process.

Jan 1, 2005

IT is intended in this paper to present in broad outline to the members of the Institute a short account of the conditions and operations that constitute what is, variously known as Subterranean Warfare, Military Mining, or Tunnelling. Realizing ,the magnitude of the operations, and the varied and minute details met with in them on,the Western Front, it is the writer's intention to confine these notes to operations carried out by the First Australian Tunnelling Company. In so doing there is no wish to detract from the very fine records of the Second and Third companies it is to be hoped that members of the Institute (or others) who were with these companies will write accounts of their doings-the former in the water-logged areas to the south of Armentieres, and later in the sand-dunes at Lombardzee, and the latter in the chalk area of the Lens coal...

Jan 1, 1920

By Budden J. R, Rhodes M. K

Bacterial oxidation technology was successfully applied in a mine site pilot plant for the treatment of refractory gold concentrates. The bacterial culture was proven capable of selectively breaking down the refractory sulphide minerals to release the gold. Gold extractions greater than 90 per cent were possible when oxidised concentrate was leached with cyanide solution. The pilot plant was designed using data scaled up from laboratory testing and sized for transport by standard vehicles. The bacterial culture used to break down the refractory gold-bearing mineral was a natural mixed culture able to withstand temperatures up to 55¦C, thus making the technology particularly suitable for use in Australian and in some North American gold mining regions. The pilot plant was operated at the mine site over a six month period. Performance of the bacterial oxidation technology under site conditions was as predicted from the laboratory testing. It was demonstrated that the culture was robust under normal site condi- tions and that the culture could withstand wide variations in the feed and the operating conditions, while still achieving satisfactory oxidation levels. The technology was able to be utilised by site operators and supervisors with minimum intervention. Design data for a commercial facility was collected for a number of different concentrate samples and a feasibility study completed. Estimated capital and operating cost have been obtained.

Jan 1, 1991

A combination of new radiometric age dates, local field relationships and the regional tectonic history indicate that the low sulphidation, fault breccia-hosted, epithermal gold-silver mineralisation at Umuna is related to continental rifting processes rather than subduction induced deformation and magmatism. K-Ar and Ar-Ar age dating of secondary sericite associated with the gold-silver mineralisation indicates that the alteration crystallised between 4.0 and 3.2 Ma, whereas relative age relationships and SHRIMP II U-Pb dating of the abundant Boiou porphyry intrusions on Misima confirm that the calc-alkaline plutonism is significantly older (8.1 f 0.4 Ma) and related to a different tectonothermal event. The Woodlark Basin sea floor spreading centre occurs to the north of Misima and has continued to propagate westwards, into the continental basement of the Papuan Peninsular, since the end of the Miocene. The westernmost tip of sea floor spreading centre is presently to the east of the D'Entrecasteaux Islands but would have been to the east of Misima roughly 4 Ma. Many of the young tectonothermal features in the D'Entrecasteaux Islands (hydrothermal activity and associated epithermal mineralisation, metamorphic core complex exhumation, detachment faulting, peralkaline volcanism, half graben type basin formation) can be attributed to major extensional deformation ahead of the propagating rift system. Similar tectonothermal features on Misima are temporally associated with the epithermal gold-silver mineralisation at Umuna, suggesting that the D'Entrecasteaux Islands are a modern day tectonic analogue for Misima at the time of precious metal mobility and deposition. The rapid exhumation of high grade metamorphic rocks and localised

Jan 1, 1997

By Lu T. K

A new type of rockbolting system, the self drilling rockbolt, has been studied to develop a 'single pass' bolt for use in rockbolt installation in underground engineering. This single pass bolt forms the basis of a Rapid Face Bolting system which will reduce the amount of time spent in securing a roof during the operation of a continuous miner in the development of a panel.The installation efficiency and anchorage tests were performed in the laboratory on the self drilling bolt and the traditional resin anchorage. bolt. The results of both bolts are cmmnared.

Jan 1, 1993

By Ward C. W

Conventional polygonal and block modelling techniques inadequately represent the grade-thickness distribution of some narrow shear and stratabound gold deposits. The polygonal influence of high-grade drill intercepts can result in overestimates of resource tonnages at high-grade cut-offs. Although block modelling methods provide grade smoothing and a better representation of structural continuity, the technique can lack precise definition of ore width. An alternative method known as Spatial Object Modelling (SOM) has been developed on MineMap software to overcome some of these modelling issues. This method does not rely on a uniform cell size and allows grade smoothing between resource intercepts in three-dimensional space. The SOM technique creates grade-thickness bars on regular, user-defined spacings which allow easy visual comparison of raw intercept data to the interpolated model. Model cell values are readily transformed into isopachs, isopleths and resource perimeters for reporting and mine planning purposes.

Jan 1, 1997

With mining development on hold and other underground works in a slowdown, the develop- ment of nuclear waste repositories takes center stage on the American rock engineering scene. Three repositories for commercial spent fuel -- in salt, tuff, and basalt -- are in the phase of site characterization and conceptual design, and one pilot project for defense high-level waste in salt is under construction. A repository design for crystal line rock has recently been postponed. Because of strict quality assurance requirements throughout design and construc- tion, and because of the need to predict and ascertain in advance the satisfactory perfor- mance of the underground openings, much intellectual energy has been expended to analyze underground openings in the unusual circumstances of the repository environment. In the long term, these efforts will lead to an improved understanding of rock behavior and improved methods of underground analysis and design. For the shorter term, a formalized ground control plan was developed, the princi- ples of which may be applied to other types of projects. This paper summarizes the status of underground design and construction for nuclear waste repositories and presents some details of the ground control plan and its individual elements.

Jan 1, 1987

By D Moy, T Carter

This paper outlines the feasibility assessment conducted to explore the possibility of constructing two submarine water supply pipelines beneath the Ma Wan Channel in Hong Kong using either horizontal directional drilling or tunnelling. The Ma Wan Channel is a major shipping channel in the Northwest New Territories, which separates Ma Wan Island from the mainland. The challenges faced by the projectÆs designers included space limitations on either side of the channel, marine department restrictions on construction activity within the channel and selection of a suitable crossing alignment and profile given the channelÆs depth, irregular sea floor topography and complex geology. The existing geological information indicated the proposed alignment would cross granitic and volcanic formations, which would likely be faulted. The primary concerns with horizontal directional drilling were:the length, diameter and depth of the crossing were at the limit of precedent experience in rock; the lack of available space at both the entry and exit sites; and whether the technique would be flexible enough to cope with the anticipated range of ground conditions. The primary concerns for tunnelling were: the possibility of encountering large inflows of high pressure groundwater; andthe possibility of encountering disturbed ground within the fault zones which could flow if not properly treated. As a means to evaluate and mitigate these technical risks for both construction options, a directionally drilled pilot hole was used to investigate the ground conditions along the proposed pipeline alignment. The pilot hole results indicated that either directional drilling or a closed face TBM drive were technically feasible crossing options at a crossing depth of 80 m. The results also indicated that either an open face TBM or a drill blast drive would need to be constructed at much greater depth because of the presence of highly permeable, disturbed ground in mid-channel at this crossing elevation.

Jan 1, 1999

By McGuckin P. H

The Cadjebut orebody is a MississippiValleyType (MVT) zinc-lead deposit, and is located approximately 80 km southeast of Fitzroy Crossing in the Kimberley region of Western Australia. It is one of five zinc rich orebodies discovered by BHP Minerals in the region.The participation in the Cadjebut Joint Venture is BHP Minerals limited (Manager), 58 per cent and Billiton Australia Limited, 42 per cent.The mineralisation is contained in gently dipping dolomitised limestone sediments (part of the Lennard Shelf carbonate sequence) with an orebody width of between 60 and 120 m and a strike length of approximately 3 km. The deposit consists of two thin, stratabound shallow dipping orebodies, one overlying the other, to provide discrete but not independent mining areas. The orebody contains approximately 2.1 million tonnes of recoverable ore at an approximate grade of 12 per cent zinc and four per cent Lead.

Jan 1, 1992

The 1980's have produced an outstanding revival of the Australian gold industry. In contrast to some previous mining booms, the economic aspects of the growth in gold production are soundly based. In general the new developments have been highly profitable and this is beneficial to all parties- whether they be government, shareholders employees or suppliers. Mining companies are showing a large commitment to gold exploration with approximately 50% of Australian exploration budgets now being directed towards gold. An increasing proportion of this expenditure is being channelled towards the eastern States with Queensland 'being the major centre of interest. Further strong growth in production is expected with some 50 projects likely to come on stream before 1990. A very significant aspect of the foundation for this growth is a continuation of the existing tax status of the industry.

Jan 1, 1987

By Hanaoka K, Ikeda K

Kakogawa Works, Kobe Steel, Ltd. has two pelletizing plants and one sintering plant, and the blast furnaces have been operated with 30 - 50% pellets. At Kakogawa Works, various improvements in pellet quality have been carried out since the beginning of operation of the pelletizing plant. Especially, dolomite-fluxed pellets developed in 1975, have superior high temperature properties. The fuel rate of the large blast furnaces at Kakogawa Works has been reduced to 450 kg/t- hn by using a high percentage of dolomite-flux ed pellets.

Jan 1, 1980

By Cleghorn JH

Underground mining operations on Kalgoorlie's Golden Mile were suspended in 1976, suffering the combined effects of low gold prices and grades. A subsequent substantial increase in the gold price led to the decision by Kalgoorlie Mining Associates to reopen their mines in 1979. The two shafts selected for access required excessive maintenance. The geological assessment and development parameters prescribed have been successfully used to establish reserves to maintain production at a 390 000 tonnes per annum rate. While ore reserve grade is being maintained from primary stoping sources, supplementary lower grade ore is drawn from remnant pillars and stopes at lower cost.Performance by the workforce has reached levels previously attained and a record tonnage was hoisted in the fourth year after recommencement.Keywords : Golden Mile lodes, geological research, payruns, cut and fill, mill holes, gold price, ore grade, amalgamation.

Jan 1, 1984

By Else D

While the underground mining work environment may have processes and equipment considered unique, most of the broad issues likely to affect the occupational health and safety of employees are not. One such occupational health and safety issue that is common to the mining sector and most other industries is noise. Noise as an occupational health and safety issue is of national significance. Presently noise induced hearing loss costs Australia around $35 million per year on compensation claims experience alone. Noisy equipment and work environments are still being tolerated in parts of the mining industry as `part of the job'. Where work has been undertaken in noise management, considerable emphasis has been placed on either industrial hygiene monitoring programs or the provision of hearing protectors to miners working on or around noisy equipment.Opportunities for more cost-effective and long term methods for controlling noise exist. Ready to apply solutions to noise problems in the mining industry are available, but for many mining operators this information is often difficult to obtain. To overcome this problem, the SHARE program collects and distributes solutions to occupational health and safety problems. The program aims to help organisations to close the gap between what is known about solving health and safety problems and what is actually being applied at the shop floor level: Recent developments have incorporated the SHARE program concept into worksite hazard management projects that involve the participation of employee representatives, front line supervisors and engineering personnel. Besides providing workforce members with an increased understanding of hazard management skills, the SHARE in-house program results in the implementation and sharing of solutions to health and safety problems by the program participants.

Jan 1, 1992

By Demin SS

Slow seismotectonic movements along the in-clined deep fault zone under the compressional horizontal stresses are supposed to be the prin-cipal mechanism controlling the structure and processes in the active ocean margins. Within the scope of the plane strain problem a simple 2-D geomechanical model for the evolution of an island arc system is investigated. We consider a homogeneous elastic half-plane with a shea-ring surface crack. The key element of the model is viscous interaction between the crack sides, the viscisity varying with depth. The model dif-fers from the classical steady-state mode of subduction by nonstationary creep processes on deep faults and by possibly cyclical development of the transition zone.A numerical modeling of the stress-strain state within the island arc system through time was carried out using a semianalytical approach. The results of simulation are in good agreement with geological, geophysical, and seismological data.

Jan 1, 1990

By Sjaw WJ

Conditional simulation is a set of geostatistical tools that is becoming popular as powerful personal computers make the use of these tools less costly. The more familiar set of tools for spatial estimation has a number of varieties (eg Ordinary Kriging, Simple Kriging, Multiple Indicator Kriging, etc) each suited to particular solutions of the problem of estimation, for example predicting the average grades of blocks in a region from more or less sparse data. Similarly, conditional simulation has a number of varieties, discussed in this paper, which in various ways address the problem of characterising the variability of a deposit between the known data locations.Conditional simulation can provide a number of equiprobable images of a deposit, at a finer resolution than would be economic or practical to sample, and that can be constrained by various criteria (which may be geological, statistical and geostatistical), to ensure that the images reasonably represent the deposit. These images can then be used to assess the risk involved in various practical mining decisions. Examples are provided where conditional simulation has been used for validating resource estimate parameters, optimising grade control sampling grids, and for ore block optimisation for mining grade control.

Jan 1, 1997

By Horrocks KRS, Smitham JB, Ellison JF

This paper describes the development and installation of equipment for continuously measuring separating density in the dense medium cyclone circuits of the four million tpa Port Kembla B/C plant coal washeries. Monitoring equipment consisting of magnetic coils and differential pressure cells were installed in U-tubes taking the full flow of magnetite from the drain sections of the product drain and rinse screens. The monitoring equipment measures overflow magnetics concentration and overflow density continuously and has operated since 1989. From these measurements and calibration trials, the separating density of operating cyclone modules can be inferred reliably. Variographic analyses of the data show that medium density control to +/- 0.002 RD units and separation density control to +/- 0.007 RD units are achievable. Either method for measuring separation density can be used with approximately the same accuracy, although the overflow density measurement technique suffers from the need to have regular flushing of the Dp cells which complicates the signal analysis. Data from the plant shows that separation density can be controlled by regulating medium density, but the assumption of a constant offset between medium density and separation density is erroneous.

Jan 1, 1993

By de Vries D, Wilson EG, Henderson GAM, Carter EK

Canberra is a planned city in which the natural environment, rather than existing development and land tenure, has until recent times at least, imposed the major constraints to development. Even redevelopment poses fewer problems than for most cities. Geological conditions have, therefore, played a significant role in determining its shape and layout. The Canberra experience has relevance for major new mining and engineering projects. The role of engineering geologists and geophysicists in Canberra's development is described, and the problems arising from the geological environment are illustrated by several case histories. Four aspects are addressed: pre-development urban geology; major engineering projects; resources evaluation, including groundwater; and post-development problem-solving. The Australian Capital Territory lies within the Palaeozoic Lachlan Fold Belt. Within the ACT the belt is composed of folded and faulted metasiltstones, metasandstones and acid volcanics, intruded by a major granitic pluton. Some limestone lenses occur. The region has been part of a land mass since Late Devonian times and landscape evolution has been very complex. Geological features of special geotechnical significance include deep but variable weathering, with slight to moderate weathering along faults to at least 70 metres depth in places, and consequential foundation problems; close jointing; weathered limestone lenses with solution cavities containing clay and water; confined aquifers containing artesian water in scree deposits flanking hills; the presence of pyrite; and poor quality and low volumes of groundwater.

Jan 1, 1986