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By Liane J. Terrill

Rockbolt failures at the Waste Isolation Pilot Plant have been recorded since 1990 and are categorized in terms of mode of failure. The failures are evaluated in terms of physical location of installation within the mine, local excavation geometry and stratigraphy, proximity to other excavations or shafts, and excavation age. The database of failures has revealed discrete areas of the mine containing relatively large numbers of failures. The results of metallurgical analyses and standard rockbolt load testing have generally been in agreement with the in situ evaluations.

Jan 1, 1995

By Kristiansen J

A series of laboratory blasting and ball mill grinding tests have been done on four different types of hard and competent rocks. The results show that exposing these rock types to a higher level of explosive energy will enhance their grindability. True blasting optimisation should therefore look at the whole comminution process from solid rock to a marketable product.

Jan 1, 1995

By A. M. Edwards

In many ways a government could be regarded as a macro business enterprise. Its shareholders are its peoples, the productivity of the nation depends on them, and, indeed, the profits or losses of a nation's balance sheet can be linked to the surplus or deficit in its balance of payments. International loans need to be repaid, and in most developing nations the noose is tied so tightly that one wonders if such debts will ever be repaid. In their endeavour to meet such obligations, their currencies may be devalued [sometimes in frightening proportions], in the hope of boosting the export potential. However, this is a vicious circle, since exports will not be achievable unless sufficient technical expertise and infrastructure exist to address the opportunities which may have been created through devaluation. Many of the poorer countries have exportable resources of minerals, which are supplied on the international market. This may be the good news, but, unhappily, steps were seldom taken to enhance the value of the mineral products through further beneficiation and the production of high-value sophisticated products. That is where the vicious circle comes in: inadequate infrastructure is created, competent and well-trained manpower is not generated, and the result has inevitably been that the GDP slips backwards, and the nation becomes progressively impoverished. To exacerbate the problem, it is unfortunate that the more impoverished a nation becomes, the greater is its birthrate, and hence the greater the need to create wealth at the very time that the nation is becoming poorer and poorer. Within this scenario, one may well reflect that this is exactly what nations on the African Continent are experiencing, namely exploding populations, although most of the poorest nations in the world are found on this continent. Yet they often possess a superior mineral production potential. Africa still suffers from what may be called the colonial influence, in that the developed world has regarded this continent as a source of raw materials to feed its own factories. The colonial powers gave only secondary attention to developing the nation's peoples and its infrastructure, such as railways, roads, harbours, and other services. These problems all naturally fall within the ambit of government interest, and it is therefore obvious that the state should play a dominant role in addressing them. The reasons for governmental involvement in mineral-related research and development differ considerably, depending on the state of industrial development of that country. Thus, in the highly industrialised world, government's interest will lie mostly in the fields of strategic minerals, which may not be economically exploitable. An example would be the exploitation of American low-grade chromites during the Second World War, or minerals which need to be imported from unfriendly or unreliable sources, such that disruption would not be in the national interest. Colonial powers like the United Kingdom and France established R&D facilities to assist, inter alia, in the exploitation of mineral resources in their colonies. The approach of developing countries would differ from that of the industrialised nations, in that their primary quest would be to promote, support and encourage the development of infrastructure, and the establishment of major industries in order to create and provide employment opportunities, as well as to support small operators who cannot afford to undertake their own research and development. On the debit side, it is a sad fact that, however good their intentions may be, underdeveloped countries are invariably unable to provide the requisite financial support to sustain their own research-and-development laboratories. In a high-tech world, the cost of sophisticated equipment is steep and cannot be afforded. Again, the proverbial vicious circle comes into play. The competent researchers find themselves without rewarding employment and would therefore shun such institutions. Recent trends in the developed world have been to privatise research-and-development institutions, the argument being that they should draw closer to the industry they serve, and that the provision of taxpayers' money for strategic purposes is no longer as important as it may have been once. Complete state withdrawal has had its negative effect in that long-range, high-calibre research has tended to be replaced by short-term problem-solving projects. Industries engaged in the minerals business differ somewhat from major ones, like motor, computer or pharmaceutical industries, which are large enough to support their own internal research and development, and whose work is highly confidential, so that any leakage could have disastrous consequences. Furthermore, private companies are answerable to their shareholders and costly long-range, 'blue-sky' research would be difficult to justify. Since mineral research has become of lesser importance in the sophisticated First World, this trend has persisted. On the positive side, R&D institutions which are totally financed by government, suffer because they tend to forget the reason for their existence. They have often become a form of auxiliary to an academic institution where higher degrees are collected by scientific boffins who, in their quest for academic excellence, tend to disregard the benefits that industry may ultimately gain from this research endeavour. The trend in recent years - and South Africa is no exception - has been for the state to progressively reduce its subsidy, whilst at the same time encouraging research organisations [for their ongoing survival] to interact closely with industry, and to conduct work directly for them on a contract basis. Organisations such as CSIRO in Australia, CANMET in Canada, the USBM in the United States and Mintek in South Africa all generate income from the private sector. However, the critical fact is that the State should never withdraw

Jan 1, 1995

By D. A. Payne

Large excavations, such as Iongwall panels, result in extensive vertical stress redistribution in the surrounding strata. The large abutment stresses developed may produce damage to pre-existing or planned excavations in the same seam or in seams above and below the workings. Knowledge of the magnitude and location of these stresses is therefore important in the design of mine openings; pillar sizes for panel and pillar layouts, roof supports in longwall gateroads and workings over or above pre-existing or planned extraction in adjacent seams. In an attempt to reduce costs, the Cape Breton Development Corporation (CBDC), a Federal Crown Corporation responsible for operating two retreat longwall coal mines, examined the potential for either interpanel barrier pillar width reduction or entire pillar elimination by the adoption of dual life gateroads for the longwall panels. In order to assess the potential for reduced interpanel barrier widths or total elimination, an investigation of the redistribution of vertical stresses around longwall panels in the Sydney Coalfield was established. The study was conducted jointly by the Cape Breton Coal Research Laboratory (CBCRL), of CANMET (a division of Natural Resources Canada) and the Denver Research Center (DRC) of the United States Bureau of Mines. The program included monitoring of vertical stress changes around longwall panels and gateroad behaviour in two seams. USBM-style hydraulic borehole pressure cells connected to chart recorders for continuous monitoring were deployed at four sites, two at Lingan Colliery and two at Phalen Colliery. This report describes the investigations conducted at Phalen Colliery. Contoured plots of stress redistribution around two sites are presented.

Jan 1, 1995

By W. Zhao

Several years ago, Reddy and Blander presented upriori model for calculating the sulfide capacity of binary silicate melts. It is modified now to apply to CaO-AlO 1.5 melts at different temperatures and compositions. Our predictions are in very good agreement with the available experimental data. From a comparison of binary calcium aluminate and calcium silicate systems, higher sulfide capacities are obtained in aluminate systems. The sulfur can be removed from hot metal more effectively by adding aluminate melts.

Jan 1, 1995

IA )W cli',hla cn1cnt fault 7011(-s 0 11Cn cOrnprise a nrc,II of inrcIIinkc(I faults, cvtcnqonal shear and In]rck cxtcnsir>nal vein- fractures. Hydrothermal mineralisation localised around such structures testifies to their importance as conduits for fluid flow. Mesh structures are most commonly developed in situations approximating bulk pure shear but predominantly simple shear meshes also occur. They appear to develop through the infiltration of pressurised fluids into a heterogeneous rock mass with varying material properties. In some circumstances, mesh formation appears to be a precursor to the development of major throughgoing faults. Mesh formation generally involves hydrofracturing (Pf> a3, at least locally) and the condition Pf - 63 to be maintained for the mesh to remain a high permeability conduit, requiring fluid overpressuring at other than shallow depths in extensional-transtensional regimes. The volumetric character of earthquake swarm activity appears to result from the passage of hydrothermal fluids through mesh structures, representing a form of distributed fault-valve action along suprahydrostatic hydraulic gradients arising from magmatic intrusion, compaction overpressuring, metamorphic dewatering, etc.

Jan 1, 1995

By Jim Breedlove, Stephen P. Case

When a major ground subsidence occurred in the AKZO Salt mine at Retsof New York, the company was forced to pick up their production from a lower mine level. Before full production on the lower level was possible, an escapeway and ventilation shaft would have to be constructed. Construction of a shaft under emergency conditions required some special techniques. Dynatec Mine Construction, Inc. of Lakewood Colorado was awarded a contract for the project.

Jan 1, 1995

By Marc Verhaege

The effluent under investigation results from a catalic oxidation unit in which paraxylene is oxydised to terephtalic acid. The solution contains cobalt and manganese as their acetates in a concentration range of 0,4 - 1,2 g/I of cobalt and 0,8 - 2,4 g/l of manganese. Before being fed into the main waste stream treatment unit of the plant it is advisable to apply a petreatment step in which both metals are eliminated to a great extent from this effluent. Conventional treatment is done by precipitation of both metals either through pH increment with a base or by adding a suitable reagent producing insoluble species. The aim of this study was to look for a treatment (elimination of both metal species) in which no sludge or precipitate is formed.

Jan 1, 1995

By W. J. Wolfe

"Quartz Hill is a large, low- to moderate-grade quartz vein stockwork porphyry molybdenum deposit, discovered in 1974 during a regional stream sediment geochemical reconnaissance survey of southeast Alaska conducted by United States Borax and Chemical Corporation. Mineralization is localized in the upper parts of an Upper Oligocene (30 Ma) composite quartz monzonite stock which is emplaced discordantly into older Cretaceous to Early Tertiary terrain of the Coast Range igneous metamorphic complex of the northwest North American Cordillera. Subsequent fault-controlled, complex multi-stage intrusion, concentrated in the core of the Quartz Hill stock, produced successive pulses of hydrothermal alteration and molybdenum mineralization at about 27 Ma. Overall, the deposit is tabular and flat-lying and well suited to open pit mining. The 0.05% MoS2 grade limit covers an area of approximately 1500 m by 2750 m and extends to a maximum depth of 520 m below surface. Details of grade distribution show two separate lobes of higher grade material within the larger low-grade deposit.A ten year program of exploration drilling, underground development, sampling and metallurgical testwork led to a 1983 feasibility study based on a resource of 1600 million tonnes grading 0.127% MoS2 at a 0.08% MoS2 cutoff The large size of the deposit and its homogeneous grade distribution, typically showing gradual outward decrease of grade, makes in pit grade selection practical at several cutoff levels. Cominco Ltd. now reports a Probable Resource of 210 million tonnes averaging 0.22% MoS2 with a further Possible Resource of 1100 million tonnes averaging 0.12% MoS:z. At low molybdenum metal prices which have persisted for 10 years since the molybdenum price spike of the late 1970s and early 1980s, the Quartz Hill deposit is sub-economic."

Jan 1, 1995

By G. Schmelzer

The disposal and reintroduction into recycling of residues produced by today's industrial society is not only a problem of much public debate in the countries concerned but also an increasingly prominent topic in science and research. In the treatment of most types of waste, ecological as well as economic considerations are important factors. In view of this, not only will future expenditures for treatment and processing become more significant but also, on the other hand, the savings and profits resulting from recycling. The situation described above reflects the inherent problems in the treatment of solid residues produced by waste incineration plants. The incineration of municipal waste produced approx. 2.7 - 2.8 million tonnes of solid residues in 1993 in the Federal Republic of Germany, which in part included still considerable amounts of organic and inorganic pollutants that could potentially be released into the environment. The most significant of these in terms of volume is incinerator ash at approx. 2.4 million tonnes. Through the use of innovative processing techniques, attempts are being made to convert the residues into a form that remains environmentally neutral over the longest period of time possible. One such group of techniques includes smelting technologies. After it has undergone specialised treatment, mineral incinerator ash is converted into environmentally neutral and reusable glass (vitrification) since, besides a reduction in the volume of the residues by approx. 90%, the main goal is a complete immobilisation and destruction of inorganic and organic pollutants respectively. These glasses, after they have been reshaped, are resold as commercial products such as damming or form glass.

Jan 1, 1995

Workplace Centred Learning, (WCL), is a learning strategy which helps organisations cope with the constant change in skill requirements that is part of business today. WCL focusses on the specific needs of the workplace and provides the structure and sets the standard whereby the required competencies can be transferred between individuals. Learning is considered part of the job and ownership is achieved by involving individuals in all aspects of the learning system. Each individual in a WCL system is considered both a learner and a teacher. A significant advantage of WCL over conventional training systems is that it responds quickly to changing requirements, and once in place, becomes self-sustaining. That is, once implemented, the system provides mechanisms to detect and respond to changes in skill requirements as they arise. WCL is a competency-based system with multiple levels of validation. It provides a flexible approach to skills development that recognises both the needs of the workplace and the needs of the individual. WCL was developed in collaboration with ALCAN Aust Ltd and is currently being implemented by companies within Australia and overseas.

Jan 1, 1995

The direct removal of lead ions from D2EHPA-kerosene using metallic zinc as the reducing agent was evaluated. The electrochemical process, called galvanic stripping, is a potential alternative stripping technique when standard chemical methods are not adequate. Four parameters found to be important in the rate of lead removal were studied in a factorially designed experiment. The variable evaluated included D2EHPA concentration, temperature, zinc surface area and solution agitation. Temperature and surface area were found to be the most significant, while agitation and D2EHPA concentration had less influence on the reaction. An activation energy of 22.5 Kcal/mole was calculated indicating a chemically-controlled process. The reaction was also sensitive to the concentration of oxygen in the system. The zinc required was considerably in excess of stoichiometry, possibly due to the dissolution and redeposition of lead: In general, the results were encouraging and demonstrated that lead impurities could be removed from D2EHPA using cementation type reactions.

Jan 1, 1995

By Byron T. Darnton

Gravity concentration at the Pegasus Gold/Montana Tunnels Mine, near Helena, MT, began in June 1991 when a coarse-gold-scalping circuit was commissioned. It processes a small portion of the ball-mill circulating load to reduce the risk of gold particles that are too coarse to float from advancing to flotation. The circuit also cost-effectively enhances overall gold recovery and payable gold ounces. This gravity circuit has been a major success. Since the circuit was commissioned, throughput has increased 30%. Several modifications and improvements were made during the last three years that allowed the gravity circuit to keep pace with the higher tonnage. The overall approach to gravity concentration at Montana Tunnels has always been to optimize production rather than maximize the gold ounces produced. This philosophy has now yielded a circuit expansion and relocation project. It will allow for an estimated 50% increase in gravity gold production, while significantly reducing the unit costs of production.

Jan 1, 1995

By X. Xie

The dissolution behavior of palladium powder in thiourea solutions has been studied. The variables studied included temperature, stirring speed, and concentrations of thiourea, acid and ferric ion. Palladium was found to be soluble in thiourea solutions in the presence of an oxidant such as ferric ion. The dissolution of palladium in thiourea solutions was found to be chemical reaction controlled with an apparent activation energy of about 2S.3 kJ/mol.

Jan 1, 1995

A short overview of the research program of SveBeFo, Swedish Rock Engineering Research, which was founded in 1993 is first given. Then four recent and ongoing projects in rock blasting and explosives engineering are presented in greater detail: 1. Burn Equations for Commercial Explosives. 2. Blast Damage in Contour Blasting. 3. The Role of Gas Pressure in Pit Wall Damage. 4. Fragmentation of Aggregate Rock. The goal of the bum equation project is to be able to control the energy release from explosive charges to the desired part of the expansion curve of the reaction products under various rock conditions. SveBeFo's work has reached the stage where a burn equation for a lab emulsion has been established which can model the influence of charge diameter on the VOD and detonation front curvature in a cylindrical charge quite well. This work now continues with other emulsion recipes. In the blast damage project the goal is to develop techniques and recommendations on how to minimise the blast damage in construction blasting. The project has gained extensive practical knowledge from the blasting of more than 200 holes in a granite quarry under controlled conditions. The cracks in the rock surrounding the contour holes have been cut open and measured. The influence of factors like charge concentration, decoupling ratio, hole and charge size, VOD and time delay in initiation have been investigated. A simultaneous initiation of a group of contour holes with EDD detonators is quite superior to single hole blasts, even when they are timed as closely as 1 ms.

Jan 1, 1995

By H. L. Gibson, T. N. Setterfield, J. J. Watkins, R. W. Hodder

"The McDougall-Despina fault set in the Noranda district of northwestern Quebec defines the eastern margin of the Despina cauldron, nested within the district-scale Noranda cauldron. The faults are stratabound in that they displace stratigraphy of the cauldron fill, but do not off-set the cauldron cover. The faults are occupied by dikes that acted as eruptive centers to volcanic members of the cauldron-filling sequence. Measurable displacement across the McDougall-Despina fault set is greater than 750 m, and coincident with post-cauldron volcanism. Feeder dikes cross-cut each other and are typically depleted in Na2O and CaO, and enriched in MgO, K2O, Fe2O3and MnO relative to fresh flows. Economic and subeconomic massive sulfide deposits occur adjacent to the McDougall-Despina fault set at different levels over a stratigraphic thickness of 3000 m. These include the Corbet deposit, the subeconomic D-68 Zone deposits, and the subeconomic stringer zones of South Rusty Hill and Bedford Hill. Numerous copper occurrences and abundant hydrothermal alteration occur in and immediately adjacent to the fault set.The McDougall, Despina, and adjacent, parallel, ancillary faults define a synvolcanic fault set which controlled the location of magmatism, hydrothermal alteration and mineral deposition during the early evolution of the Noranda cauldron. Significant sulfide mineral deposition commonly occurred in proximity to the intersection of the McDougall-Despina fault set with northeast-trending synvolcanic faults. Recognition of synvolcanic faults is therefore a major objective of exploration programs for volcanic-associated massive sulfide deposits."

Jan 1, 1995

By Thomas P. Mucho

To document the performance of mine roof and roof support systems the U.S. Bureau of Mines (IJSBM) has been installing instrumentation at selected sites in U.S. coal mines. Much of this support and roof instrumentation has been installed in high stress conditions to maximize differences in performance. Summarized in this paper are the results of four such site investigations. The roof geology at the four sites is quite different and is quantified using the USBM's Coal Mine &f Rating (CMRR). The studies included detailed measurements of roof movement using multi-point extensometers, as well as measurements and monitoring of bolt loading. The investigations include developmental loading and abutment loading from longwall and room-and-pillar mining operations. Some of the issues examined are the effect of the horizontal stress field, the effect of installed tension (torque-tension versus resin bolts), the effect of reduced annulus bolt holes, and the differences between similar bolts supplied by different manufacturers.

Jan 1, 1995

By J Aitchison, G Clarke

A reappraisal of the stratigraphy, new regional kinematic analysis and thermobarometric data allow a new interpretation of the metamorphic zoning and tectonic structure of the Upper Eocene high-pressure metamorphic core complex of northernNew Caledonia allow a three steps evolution to be proposed: 1. subduction and understacking of previously thinned continental crust elements; 2. subduction blocking due to the crustal thickening; and 3. crustal thinning and extensional detachment during the diapir-like uplift and unroofing of the eclogitic core. Steps 2 and 3 may be partly contemporaneous. Such a model accounts for the thermobarometric and radiochronologic data, and also for the weakness of substratum deformation during the emplacement of the ophiolitic nappe

Jan 1, 1995

By Seedsman R. W

Good roads are essential in moving men and materials to and from the underground workplace. Coffey Partners International Pty Ltd (Coffey) has recently completed a underground coal industry funded project on underground mine road construction and maintenance. This paper discusses practical approaches to construction and maintenance of underground mine roads using transferrable civil technologies and innovative techniques. Mine pavements are generally low-cost (relative to civil roads), constructed to varying standards using locally available materials to best meet the mobility needs of the mine. Performance of pavements is thus largely dependent on the environmental conditions, quality of the available road making materials, maintenance policies and available resources. The paper will detail `what causes bad roads?' in various underground environments, available management strategies, construction and water control techniques, road maintenance and vehicle considerations.

Jan 1, 1995

By J E. Nethery

At the Red Dome and Mungana deposits in north Queensland, Australia, it is proposed that mineralisation and alteration developed as a 'telescoped' overprinting continuum, ranging in style from hypothermal to epithermal, reflecting the major changes that developed in the regional setting over the period circa 325 - 290 Ma. Regional assessment suggests that this also applies to many other precious and base metal deposits within a 40 km length of the host Siluro-Devonian Chillagoe Formation.   A ten stage paragenetic sequence of structural preparation, multi phase intrusion and associated mineralisation, alteration and brecciation is postulated for the Chillagoe district.

Jan 1, 1995