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Paper presented at the conference Risk assessment in the extractive industries, held in Exeter, 23-24 March 1994. Sensitivity analyses based on financial variables are now routinely applied to the forecast financial results of mining projects especially during the feasibility stage. Risk analysis is gaining acceptance but is still almost universally confined to the effects of variations in financial variables. The single most sensitive factor in almost all mining projects is the ore reserve, but it is either ignored or improperly used in sensitivity and risk analyses. Unlike financial variables, the components of the ore reserve (grades and tonnages of mining blocks) are a function of location within the orebody. Physical (mining) access to these components is therefore a function of time which has a crucial effect on forecast cash flows. It is critical that these fundamental concepts are included in risk analyses of mining projects. The effects are considered of the uncertainty of the ore reserve on feasibility studies and open-pit mine design for a small gold mining venture. Geostatistical simulation is used as a method of quantifying the risk in using grades and tonnages estimated from sparse data

Jun 16, 1905

By A. Hemami

In order to automate the operation of mechanical loaders it is essential to have a knowledge of the forces that act on the bucket and of the trajectory that the bucket should follow. A trajectory for the cutting edge of a bucket is derived from studies of the forces acting during the scooping phase. The proposed trajectory has a minimum energy consumption and is simple to automate. It is determined initially by setting to zero certain components of the resistive forces to the bucket motion which would otherwise result in unnecessary work and consequent energy wastage. The method for finding the appropriate trajectory is discussed on the basis of the properties of the material to be loaded and the loader size.

Jan 4, 1993

By Gibson J.

The writer hopes to prove that the economical tram is of even greater importance than, say, the economical engine, and as no difficult and involved calculations are required, and all the governing facts are simple and well known, the former is more easily attainable than the latter. In the first section of this paper the factors that determine the size and the construction of the tram are examined; whilst in the second section the road on which it runs is dealt with

Dec 1, 1916

For the convenience of those who are unfamilar with thermodynamics, the following brief description and explanation is given of the thermodynamical terms and methods used in this book. It must, however, be strongly emphasized that the account given below is not an introduction to chemical thermodynamics; its sole purpose is to give the reader a rough understanding of the methods used in the earlier chapters. For further information, reference must be made to the standard textbooks on chemical thermodynamics by Glasstone.

Jan 1, 1953

By A. B. Holland-Batt

Deposition velocities play an important role in many fields of engineering and an impressive range of measured data has accumulated in the literature. Numerous workers have addressed the problems that are associated with the prediction of deposition velocity because of its particular relevance to the design of pipelines and pumping stations. However, despite this extensive effort, the calculation of friction heads still requires reference to experimentally based graphs to determine Durand factors and there is still scope for improvement in the prediction of the deposition velocity at different solids concentrations. Equations to characterise the relationship between the Durand factor and the volume concentrations of solids in the slurry are presented. A correlation for the prediction of the deposition velocity is also developed and tested against some of the classical experimental data. The application of predicted values of deposition velocity in assessing the potential for the sanding-up of spiral separators is then described and a case study is presented.

Jan 12, 1992

By G. Mellgren, O. Mellgren

The conductivity of a solution is often used industrially to control the salt concentrations of reacting systems, normally using electrodes made of glass fitted with platinised platinum electrodes. When a standard platinum conductivity electrode was used to control the acid fed to the leaching circuit for an ilmenite flotation concentrate at Titania, Norway, a deposit of calcium sulphate (containing some calcium phosphate) covered both the platinum electrode and the external glass fitting, rendering the electrode inefficient in the course of a few minutes. A new electrode consisting of a casing, two measuring tubes and an electrode stem is described and illustrated. A significant advantage of its design is that the useful range of conductivity measurement can be adjusted by adjusting the concentration of the electrolyte in the electrode. It has been in use at Titania for about four years with an electrolyte consisting of 0-1 n HCI. It is robust and demands little maintenance.

Dec 1, 1971

By G. R. Doughty

It is shown that sodium can be removed very readily from molten aluminium by the use of a beta"-alumina, the more highly conducting form of beta-alumina, provided that the surface of the tube is wetted by a layer of salt. From current/time plots the theoretical amount of sodium removed has been calculated and excellent agreement obtained. The beta"-alumina tubes can be immersed directly in the Al without fracturing if they are pre-heated for a few minutes prior to immersion. According to its stability beta"-alumina should be attacked by molten Al at low Na contents, but in these experiments the salt acted as a protective layer. Magnesium chloride is a relatively cheap salt, whose Mg product can be used within a foundry. The only other product is NaCl, which can be used in-house as a flux or sent for disposal. No polluting gases are used or produced and no drosses created. The time for removal of sodium was quite short, comparable to that for chlorination

Jun 21, 1905

By D. J. Wall, T. D. Johnson, M. T. Parry, G. R. Heath

In coal-fired power stations coal is ground to a fine powder and then transported pneumatically at 25-30 m/s velocity to remote burners. Wear of the conveying pipework is a well recognised problem and traditional lining materials are Nihard and basalt. In many cases these are being replaced by alumina tiles in order to improve life and reduce the frequency of replacement. A programme of laboratory testing of candidate aluminas with AIO, contents between 85% and 99-5% has been undertaken and the results compared with field experience. This gives confidence in the erosion tests, which were designed to replicate most of the field conditions. However, it has not proved possible to draw correlations between the laboratory erosion rates and any of the materials’ bulk properties. SEM, TEM and microanalysis studies have therefore been made in order to look for microstructural aspects that could be influencing erosion rates and it has been shown that intercrystalline cohesion, the matrix phase and porosity appear to have most influence on wear performance. It is necessary to quantify these microstructural parameters if reliable erosion performance is to be obtained. This paper was read at the Institute of Ceramics Annual Convention at the University of Durham, April 1988.

Jun 12, 1905

By R. T. Grant, C. Bazin, D. Hodouin

It is shown that most of the variation in the results of semi-batch flotation tests is related to the unavoidably stochastic nature of the flotation process. The preparation and analysis of flotation samples and, to some extent, operator error in performing the flotation test procedure are responsible for a small proportion of the observed variability of the calculated flotation performance indices

Jun 17, 1905

By D. H. Watkinson

Paper presented at the IAGOD international symposium on mineralisation related to mafic and ultramafic rocks held in Orleans, France, 1-3 September 1993. Part of the contact of the 4b orebody with the enclosing Murray granite is characterised by the presence of recrystallised and biotitic Sudbury Breccia; in places the contact is faulted and sheared. In other areas of the contact partly silicified granite contains disseminated chalcopyrite and quartz-chalcopyrite veins with other minor minerals. Both ore and veins contain platinum group minerals (PGM); predominant PGM are michenerite, kotulskite, merenskyite and sperrylite with Au, galena and Bi-tellurides. At some silicified-granite contacts Mn-rich garnets, some containing inclusions of PGM and quartz, are associated with biotite + epidote + stilpnomelane + quartz. PGM and Au also occur within Cl-rich biotite and ferropyrosmalite in massive sulphide and in siliceous ore. Quartz, chalcopyrite and feldspar in the contact rocks and in veins contain abundant, highly saline fluid inclusions. Studies showed that the fluids were trapped at intermediate temperatures. The 4b orebody is surrounded by a sheath of brecciated granite but is close to the Contact Sublayer. During and after emplacement of sulphide magma, saline formational fluid that was resident in the breccia interacted with hot massive sulphides in and near the Sublayer and remobilised Cu, Au and PGE. This fluid reacted with cooler rocks and ore in footwall fractures, enriching the 4b protore and producing the adjacent Cu- and PGE-enriched quartz veins. Exploration for Cu and PGE enrichment in footwall rocks of the Sudbury South Range is warranted not only in zones of magmatic ore in the Contact Sublayer but also in fractures and permeable units within Sudbury Breccia

Jun 16, 1905

By G. I. D. Roach

The leaching, with hydrochloric, sulphuric and perchloric acids, of suspensions and massive specimens of different haematite and goethite samples has been studied. Both accelerating and constant types of leaching curves have been observed. It is concluded that the grain to particle size ratio of the oxide being leached determines which type of leaching curve is obtained, particles containing a large number of individual grains producing the accelerating type of curve

Dec 1, 1971

By P J. Borrington

Offering 1000 hour salt spray protection, the KEYCOAT 1000 coating presents no chipping, cracking or deformation when hammered or flexed through 90 degrees or more. This cost-effective metal protection system features lubrication performance equal to molybdenum disulphide and Poly Tetra Fluoro Ethylene (PTFE) grease providing complete anti-seize protection whilst aiding assembly and disassembly. In addition, the coating is impervious to acids, alkalis, solvents and attack by oils and all fuels. KEYCOAT 1000 has been exhaustively tested in three main industry sectors - automotive, heavy earthinoving vehicles and chemical - where it lias been proven to outperform conventional systems in all respects and as the film formed is less than one thousandth of an inch thick (typically 20 microns), it rarely presents the engineer with any tolerance difficulties. KEYCOAT 1000 is one of a w ide family of products which offer protection and lubrication to a wide industry base, from aerospace to food and with temperatures ranging from minus 190 C to plus 30 C.

Jan 4, 1997

By G. H. Blackwell

Sequences in open pit mining must be planned and regularly revised to incorporate changes in the variables which affect profitability. Interactive computer planning with colour graphic facilities is an effective tool for this purpose in the short and medium term. An interactive computer planning system for medium-size, low grade porphyry copper-molybdenum open pits is described. The planning system proved especially valuable during the critical stages of pushback mining when deep, inner pit ore was nearly depleted and the erratic grades of the next pushback provided ore and marginal material at a time of depressed metal prices.

Jan 8, 1993

By R. W. Ruddle

"Besides copper, iron, silicon, and oxygen, a large number of elements may be present in copper ores, the more important of which are zinc, lead, arsenic, antimony, bismuth, selenium, tellurium, nickel, cobalt and the precious metals; impurities of less importance are calcium, magnesium, aluminium, barium, sodium, potassium, manganese, lithium, fluorine, titanium, uranium, vanadium, tin and molybdenum. All of these elements are eliminated to some degree in the subsequent roasting, smelting and converting operations.Information on the elimination of impurities during the smelting of copper is surprisingly meagre, however, rather more information is available on impurity removal during the smelting of the ore in reverberatory or blast furnaces."

Jan 1, 1953

By H. B. Bell, L. C. Smith

Measurements have been made of the activity of 'FeO' in 'Fe0'-Mn0-Ti02 melts at 1475 degrees C. The results obtained are discussed in terms of ideal mixing of titanates and in terms of a regular solution model. On the basis of the regular solution model activities of Ti02 and MnO in the Fe0-Mn0-Ti02 and Mn0-Ti02 systems have been derived. The data have been shown to be consistent with the liquidus lines in the phase systems. Examples are given of the application of the data to slag-metal equilibria, being used to derive slag-metal data between liquid iron and Fe0-Mn0-Ti02 slags

Dec 1, 1971

By S A. M Crawshaw, J A. B Fortune

Trackless battery powered haulage vehicles have been in operation in British coal mines principally for longwall face transfer and personnel transportation. Changes within the industry have resulted in the introduction of room and pillar coal mining methods and the introduction of increasingly heavier longwall roof supports This has resulted in the introduction of: • Battery powered coal haulage machines, which, without the need for trailing cables, increase productivity within room and pillar mining. • Battery powered longwall shield haulers which are capable of carry ing the heaviest shield supports currently being utilised within the British coal mining industry. The conventional machines have been adapted from an American design to meet the requirem ents of European legalisation. This has seen the- emphasis being placed upon the supplier with the European M achinery Directive being introduced, necessitating the assigning of a 'C E ' m ark to each vehicle. Battery vehicle technology has advanced to meet the demands of the ever changing market and will no doubt he further adapted to meet the requirement of the British coal mining industry.

Jan 10, 1996

By P. A. Wright

The note describes the steps involved in the combination of results reported by Shiraishi and Bell in 1968 and 1970 and by Mills and Turkdogan in 1964. Shiraishi and Bell derived from their vapour-pressure measurements an expression for the activity coefficient of tin implying that the miscibility gap in the two-liquid region is symmetrical about the N = 0-5 axis. The limits of the miscibility gap were reported by Shiraishi and Bell and measurements were reported graphically by Mills and Turkdogan. Least-square parabolas are fitted to the transformed results of Shiraishi and Bell and of Mills and Turkdogan for the miscibility gap in the liquid tin-iron system. Back-transformation from these curves gives limits at 1438 K and equations are derived that appear to be a fair average of existing data, although a third term for the activity coefficient equation needs to be investigated

Dec 1, 1971

By P. K. Kaiser, R. K. Brummer

Paper presented at the conference Risk assessment in the extractive industries, held in Exeter, 23-24 March 1994. A risk-based decision-making procedure has been developed for selecting rockburst-resistant tunnel support in burst-prone mines. The method is based on a risk-cost-benefit analysis and uses support cost data, costs associated with the risk of support failure or excavation loss, costs associated with accidents, injuries and deaths, and the benefits achieved by installing rockburst-resistant support. It takes into account the risk of damage to the support systems due to rockbursts, potential loss of production and the need to rehabilitate in the event of a damaging rockburst. A practical example is provided to illustrate the principles involved in the decision process

Jun 17, 1905

Discussion of papers with authors' written replies and closing remarks.

Jan 1, 1947

By Le Thac Xinh, van Chu Nguyen

In northern Vietnam Ni-Cu sulphide deposits associated with ultramafic rocks are located in several continental rift zones of Permo-Triassic age. In recent years a number of ultramafic bodies have also been discovered in southern Vietnam, but detailed work on sulphide occurrences within these bodies has still to be undertaken. A brief description is given of some N i-C u sulphide deposits that are located in the northern part of the country. Of the depos­ its that have been examined in any detail, those in the Takhoa region are of the greatest economic interest. Ni and Ni-Cu sulphide bodies have, however, also been found in association with the ultramafic rocks.

Jan 1, 1984