Search Documents

By I. R. Hanby

A simple but comprehensive method has been developed for the simulation of a mechanical-drive dump truck that enables various parameters to be predicted as a function of time throughout its whole cycle. Uses of the simulation results are indicated with specific attention to environmental and operational or economic planning. The output of a sample run is presented. The method can be easily adapted for the investigation of a wide variety of mobile plants.

Jan 4, 1992

By A. J. Naldrett

"Synorogenic mafic intrusions are a common feature of the northern Appalachians. Two sulphide-bearing intrusions in central Maine that have been investigated revealed a number of important features that illustrate sulphide-silicate interaction that relates to magmatic sulphides. The Moxie Pluton is a large mafic intrusion emplaced during the Devonian Acadian orogeny. The Katahdin gabbro is a small mafic body that is probably genetically and temporally related to the Moxie Pluton. Both intrusions were formed bv the intrusion of variably fractionated magmas into irregular chambers and feeder zones. The southern half of the Moxie Pluton contains three small sulphide accumulations, whereas the Katahdin gabbro hosts a large, predominantly massive, sulphide body. Textural evidence clearly documents the magmatic origin of these sulphides.The three Moxie Pluton sulphide bodies are located at or very close to the intersection between the intrusion and the sulphidebearing Hildreths Formation. Sulphur assimilation, suggested by this relationship, is supported by the isotopically light (634S = —8 to —25) and the selenium-poor (S/Se - 25 000-48 000) character of the Moxie sulphides and correlation with the Hildreths Formation sulphides (S34S = —25, S/Se = 25 000-48 000). Isotopically light sulphur (534S = —20 to —21) and high S/Se ratios indicate that the majority of sulphur in the Katahdin sulphide body was also derived from an unexposed country rock source. The volume of sulphide in this example illustrates the potential efficiency of the sulphur assimilation process—so efficient in this case that marked dilution of the economic chalcophile elements resulted from the addition of so much external sulphur.The three Moxie Pluton sulphide occurrences are all impoverished in Ni and Cu (1.87-0.44% Ni; 0.72—0.32% Cu in massive sulphide), but contain normal Co contents (0.22-0.13%) relative to typical magmatic sulphides. The Katahdin sulphides show a greater Ni and Cu impoverishment (0.2% Ni; 0.1% Cu in massive sulphide) with similar Co (0.17%). The Ni content of the Moxie Pluton olivines document the fractional removal of sulphides during crystallization of the host magma, which resulted in the progressive depletion of the chalcophile metals in this magma. Modelling that involved the fractional crystallization of the magma coupled with the fractional removal of a specified proportion of sulphide has successfully duplicated the Moxie Pluton sulphide compositions. A similar magmatic model has been postulated for the Katahdin sulphides with a greater degree of sulphide fractionation. This latter model is again supported by extremely low Ni/forsterite ratios in olivines, though the compositional range is insufficient to document fractionation. These magmatic models are not unique, but they provide a relatively constrained and consistent explanation for the sulphide compositions.The Ni contents of olivines are the most important indicator of sulphide-silicate interaction in mafic magmas and have exploration potential. They provide a means of assessing the timing and extent of sulphur saturation in an intrusion and are a guide to the Ni content of a sulphide accumulation in equilibrium with olivine. In the Maine examples they provide strong evidence of the magmatic origin of the sulphide accumulations and justification for magmatic modelling."

Jan 1, 1984

By Ruddle R. W.

Magnetite occurs in the reverberatory furnaces, blast furnace and converter (a) as the result of its presence in the materials charged, and (b) as the result of oxidation of the FeS in the charge in the absence of sufficient SiO2 to slag the FeO as it is produced and thus prevent its subsequent further oxidation. Magnetite is reduced by FeS according to FeS+3Fe3O4=10FeO+SO2 and similar reactions. This reaction is markedly affected by temperature and does not proceed to any important extent below about 1200°C. To ensure comparative freedom from magnetite it is therefore necessary to raise the temperature of the furnace to the highest practicable figure and to use plenty of siliceous flux. Since the maximum operating temperature is likely to be limited by the resistance of the refractories to attack by the slag, investigation of the factors affecting this attack should be helpful. It is reasonable to suppose that the formation of magnetite might be minimized by ensuring intimate admixture of matte and slag during conversion so that silica is readily available for combination with ferrous oxide as the latter is formed. The literature gives no clue to the importance of this factor and some experimental work on this aspect might be fruitful

Jan 1, 1953

By R. J. Pine

Procedures are described for the application of risk analysis or probabilistic methods to mining geomechanics. The methods are widely applicable to existing mine design models. Detailed examples are given of plane slope failure and of pillar design based on displacement-discontinuity stress modelling and empirical strength assessment. The modelling techniques assessed are the Latin hypercube sampling method, incorporated in a spreadsheet environment, and the general point estimate method (GPEM), programmed in TurboBasic. An example GPEM program listing is included. Both methods are very convenient to use. Probabilistic acceptance criteria for slope stability after Priest and Brown are examined and alternatives are proposed where output distributions of factor of safety are approximately normal or lognormal and output distributions of safety margin are normal. The reliability index is included as a useful measure of variability with proposed acceptance criteria.

Jan 12, 1992

By Haldane J. S.

(Paper presented at the Institution of Mining Engineers' general meeting held in London on 8th June 1916.) It was shown in the last Supplement to the Registrar-General's Reports, in connection with the census of 1901, that the general death-rate among colliers was considerably lower than in the great majority of occupations but that there is an exception to this in the case of colliers above the age of 55. Examination of the statistics finds that the excessive death-rate among old colliers is to a large extent only apparent, and that the real excess of bronchitis from which they have suffered has greatly diminished. It is concluded: (1) that good ventilation is of considerable importance to the health and continued working efficiency of miners, as well as to their safety from accidents; and (2) that there is no real statistical evidence of harm resulting from the inhalation of coal-dust or shale-dust in the quantities ordinarily breathed by miners, and a strong presumption that the dust they breathe protects them against serious dangers from bacilli that are removed from the lungs by the dust-clearing cell mechanisms

Dec 1, 1916

By L. G. Billington

"The Agnew nickel deposit occurs in a major linear greenstone belt in the Archaean Eastern Goldfields Province of Western Australia, and has been subjected to mid-amphibolite facies nietamorphism of dynamic style. The largest dunitic ultramafic body in the Perseverance Block is host to the bulk of the nickel mineralization. The Perseverance Ultramafic is mineralogically zoned and has an embayed western margin against a mixed metasedimentarv-metavolcanic wallrock sequence.Three categories of nickel sulphide mineralization are concentrated on this western margin at the thickest part of the ultramafic exposure. Massive sulphides characteristically occur as contact mineralization, internal mineralization and as remobilized concentrations in vein form structures. Disseminated ore constitutes the largest volume of mineralized materials in the deposit and occurs in three separate shoots in en-echelon relation. Weakly mineralized 'cloud sulphide' zones surround and envelop the shoots and persist much further along strike. In the upper mine levels the shoots are truncated by a shear or crush zone, which inhibits geological knowledge to the south but marks a major fundamental structural break.Most of the ore types have suffered supergene alteration and there is a complex variable distribution of the mineralogical facies. The ore types have been metamorphically retextured, but the oreshoots can be characterized by their Ni tenor and some chemical ratios. S/Se values, PGF. and precious metal values are distinctly different from those of other nickel sulphide ores extracted.Despite intense structural and metamorphic modification of the mineralizations, some features support an original magmatic derivation for the sulphides. These include the localization of massive sulphide ore types on one marginal contact within an emhayment structure, the general distribution of disseminated mineralizations located immediately above the massive sulphides and the Ni/Cu, Ni/Co, Fe/Ni ratios of the oreshoots being similar to those of deposits that typify the intrusive dunite- associated class of nickel sulphide deposit. Varying S/Ni ratios between different shoots suggest a revision of the single magmatic intrusion model in favour of a changing composition between successive magmatic episodes."

Jan 1, 1984

By E. H. W. Hornbrook, P. W. B. Friske

Paper presented at the 28th International Geological Congress, Washington DC, July 1989 (International geochemical mapping sessions). The objective of the programme is to establish and maintain a nationally consistent geochemical drainage database. Towards this end systematic surveys have been conducted since 1973. To date more than 200 surveys have been completed to the required standards, representing 180 000 sites and covering about 2 100 000 km2 throughout Canada

Jun 13, 1905

By Ruddle R. W.

An outline account is given of the smelting of copper and the chemistry of the process. A table provides compositions of the more important minerals from which copper is won by smelting. Roasting is discussed as is smelting using reverberatory furnaces, blast furnaces and flash smelting. A brief discussion of converting covers the upright (Great Falls) converter and the horizontal (Peirce-Smith) converter.

Jan 1, 1953

By R. W. Schultz

Mineral exploration carried out in Ireland since the mid-1950s has resulted in the discovery of ore deposits that are now in production atTynagh (Pb-Zn-Cu-Ag), Silvermines (Zn-Pb) and nearby Ballynoe (barite), and Gortdrum (Cu-Ag-Hg); a major Zn-Pb deposit at Navan that is now being drilled prior to development; potentially productive deposits at Keel (Zn-Cd-Pb), Ballinalack (Zn-Pb) and Aherlow (Cu-Ag); and a number of interesting prospects, including one of spodumene. Underground exploration of a formerly extensively mined copper deposit at Allihies has outlined new, albeit currently uneconomic, reserves at depth. The copper and pyrite deposits at Avoca have in recent years been re-explored and are now again being worked. Most Irish ore deposits are in the lower half of the Lower Carboniferous succession of limestones and subordinate shales and sandstones, and this stratigraphic zone is being most intensively explored at present. Other geological units under active exploration are Ordovician sediments-volcanics belts, Caledonian granites, and parts of the Old Red Sandstone and Dalradian series. Surface prospecting is made difficult in many places by glacial and other superficial deposits, including peat and alluvium. Geochemical prospecting methods have been outstandingly successful and primarily responsible for most new discoveries. Boulder hunting and outcrop prospecting have proved effective in detailed investigations of geochemically anomalous areas. Some parts of the country have been covered by three separate airborne geophysical surveys, albeit without success so far. The induced polarisation technique, the most widely used ground geophysical method, has contributed to several discoveries. The scope of application of electromagnetic surveys is more restricted than that of induced polarisation, but the method has been effective in a few cases and has contributed to the Tynagh discovery. To date, the resistivity and self-potential methods have found little application. Magnetic surveys are not applicable directly in the search for ore deposits of the various known types, but can be helpful in outlining geological structures in some areas. The gravity method has been used successfully in a survey over the Zn—Pb deposit at Navan ; it has also proved effective in trials over a blind sulphide deposit at Tynagh that cannot be detected with geoelectrical methods. An appendix lists summary descriptions of 15 Irish deposits and occurrences

Dec 1, 1971

By E. C. I. Hammerbeck

"Geological controls and constraints in space and time define the milieu of the nickel deposits of Southern Africa. Primary, magmatic deposits are of two types, e.g. synvolcanic or syntectonic deposits confined to certain orogenic domains, and those related to intracratonic, post-orogenic magmatism, e.g. the Great Dyke, the Bushveld Complex and the Insizwa intrusion. Epigenetic and supergene deposits form a separate, unrelated group and are of minor economic importance.The metallogenic evolution of syntectonic nickel deposits is particularly well illustrated in the Zimbabwean Province, where the relationships between Archaean greenstone development and nickel mineralization are best illustrated. Volumetrically subordinate, nickel-poor greenstones in the 3500 m.y. old Sebakwian Group are followed by more common komatiite development in the Lower Greenstones (3000 m.y.), and, finally, by very significant komatiites with important nickel mineralization in the 2700 m.y. old Upper Greenstones of the Bulawayan Group. Comparable nickel mineralization is not known in the Raapvaal Province, in spite of ubiquitous komatiitic magmatism of the Onverwacht Group (3500 m.y.) and other greenstone sequences. No komatiitic rocks younger than about 3200 m.y. are known in this region, orogenic activity in the Kaapvaal tectonic province having ceased at about 3100 m.y., whereas the Zimbabwe Province remained tectonically active until at least 2600 m.y.The tectonic environment, host-rock petrology and mode of emplacement, as well as some details of the nickel mineralization, are the parameters employed to classify the Southern African magmatic nickel deposits. A rating of the deposits is introduced that reflects the original resources of the deposit, its average nickel content, its mining history and potential to facilitate ready comparison with and assessment of the nickel deposits listed in the classification, as well as some important nickel deposits worldwide."

Jan 1, 1984

By N. T. Moxon, D. Mead, S. B. Richardson

A laboratory and theoretical study of air decks was carried out to assess the effects of the size and location of air-decks on fragmentation. The degree of fragmentation was found to depend on both factors. As the size of the air-deck increases the degree of fragmentation is reduced relative to a full column charge. However, the reduction is relatively small until a critical size is exceeded. The critical size depends on the strength and structure of the surrounding material. A critical air-deck length of 30-35% of the original explosive column was determined for the model materials used in the study. A theoretical explanation of the results was derived based on pressure decay rate relationships. The location of the air-deck also influences fragmentation. The interaction and oscillation of the two shock fronts from the top and bottom charges mean that mid-column air-decks produce better fragmentation for the same air-deck length and explosive loading as top-column or bottom-column air-decks.

Jan 4, 1993

By Evans E. C.

Discussion of the paper presented at the Manchester Geological and Mining Society' general meeting held in Manchester, March 14th , 1916, with Leonard R. Fletcher, President, in the Chair included contributions by Fletcher L.R., Paton J.D., Orchard A.J.A., Ross A., Gerrard J. and Stephenson H., with the author's responses

Dec 1, 1916

By A. Paulin, A. W. D. Hills

The work has shown that packed-bed behaviour can be predicted from the results of single-particle experiments, total reaction times being predicted somewhat more accurately than gas and solid temperatures and gas compositions. A small laboratory packed-bed reactor was built and used to study the decomposition of beds of specially prepared CaCO3 spheres, steps being taken to minimise the effects exerted by the walls of the bed on processes occurring within the bed. Gas and solid temperatures and gas compositions were measured at various points in the bed and compared with theoretical predictions based on kinetic data determined in previous single-particle experiments. The measured solid temperatures and total reaction times agreed remarkably well with the values predicted theoretically. Gas and solid temperatures measured after the reaction had finished at any point in the bed did not agree with the theory. This was because solid temperatures in the bed rose very rapidly once the reaction was completed and the walls of the bed could not be heated at a sufficient rate for their temperatures to rise as rapidly; thus some loss of heat from the bed to the walls was inevitable, and this could not be accounted for in the theory. In addition, the theory did not allow for the conduction of heat within the bed, and this resulted in some further slight discrepancy between the measured and predicted values, particularly after the reaction was completed. Gas compositions measured in the bed were rather scattered, but, even so, they agreed moderately well with the predictions of the theory.

Dec 1, 1971

By D. J. Buchanan

British Coal's mining research programme is directed towards the strategic objectives of reducing production costs, improving product quality and resolving health, safety and environmental issues. The strategy for R&D is described and selected parts of the programme are reviewed. Two major initiatives are directed towards reducing production costs: geotechnics and automation. Integrated exploration techniques are used to delineate geological structures as an aid to mine planning. Rockbolting is being rapidly introduced and the in situ stress field has been found to be of significant influence. Automation is the subject of a major programme. A strategy for coal quality has been devised. The health, safety and environmental programme concentrates on the traditional hazards together with surface environmental problems.

Jan 12, 1992

By J. Plant

Stream-sediment sampling undertaken to define the regional geochemistry of northern Scotland is described with particular reference to the errors involved. The region is underlain essentially by Moine schists, Caledonian granites and Old Red Sandstone sediments, which are generally characterized by low geochemical relief. Factors in the secondary environment obscure the relationship between trace-metal concentrations in stream sediments and bedrock geology. Investigation of sampling and sample preparation methods indicates that the -100-mesh material is the optimum size fraction for the regional survey of this area: it provides adequate geochemical contrast: it reduced the incidence of spurious high values in the samples investigated and it is available in amounts which are adequate for all the analyses required. Grinding samples improves precision and reduces the preferential volatilisation of metals coprecipitated with hydrous manganese and iron oxides for the optical emission spectroscopic method used initially. A study of the dispersion of metals in the drainage system of an area of Pb-Ba-Mo mineralisation and an area of U-Pb mineralisation, respectively, indicates that a sampling interval of 1 per 2 km2 based on second- or third-order streams is adequate to define anomalous metal concentrations. Regional variation can also be represented on the same interval. Modifications to the sampling procedure to reduce the effects of the secondary environment are complicated by the primary association of Mn and Fe with mineralisation in the area. The ratio of analytical and sampling error to regional variance shows that procedural precision is adequate to prepare regional geochemical maps of northern Scotland, with the exception of Cr, Cu at low concentrations and Pb.

Dec 1, 1971

By D. Newman

Mineral production in the Highlands and Islands of Scotland during the last ten years has been confined to the sporadic production of industrial minerals—for example marble, anorthosite, limestone, talc and silica. From 1962 onwards there has been an upsurge in mineral exploration in the Highlands, increasing in tempo from 1966 onwards due to the efforts of the Institute of Geological Sciences, the Highlands and Islands Development Board, and private and public companies. Geological, chemical and economic aspects of some of the more interesting mineral prospects are discussed: these include anorthosite, feldspar, magnetite, quartzite and brucite marble. Reference is made to a geochemical survey undertaken in the Rosehall district of Sutherland, the results obtained being summarised. Problems that affect the future of mineral exploration in the Highlands are stated.

Dec 1, 1971

By E. J. Bolitho

"The paper covers the activities of the Government Miners' Training-Schools. It argues that its success is proved by the steady demand for miners trained at the Schools; by the large numbers of ex-apprentices who hold responsible official positions in the industry; and bv the probable expansion of the organization in the near future to meet the never-ending call for trained personnel."

Jan 1, 1947

By M. A. Bussell, G. S. Camm

The study included lode zones at Wheal Pendarves, South Crofty and Rosevale tin mines. Fluid inclusion-containing microfractures are a common feature of the granites and typically show a preferred orientation over quite a large area. The close proximity of a dominant vein or fault controls their density and orientation. They are important pathways for fluids and provide a marker for palaeo-fluid flow. Overprinting provides a reliable representation of the evolution of the hydrothermal fluids in a vein system from early magmatic fluids to late-stage meteoric and basinal brine input. Measurement of microfracture orientation allows estimation of the regional stress regime during a specific hydrothermal event. Since micro- and macro-structures can generally be reliably correlated, these studies assist in modelling the detailed development of complex vein systems. Microfracture density is a good measure of palaeo-permeability, with implications for control of wallrock alteration. The determination of the location and density of microfractures can assist the mine geologist in identifying the location of potentially economic vein structures where macroscopic markers are absent

Aug 1, 1996

By D. J. Allan, W. R. Wilson

For conventional aerospace aluminium alloys of the 2000 (copper) and 7000 (zinc, magnesium) series the recycling of process scrap from both metal suppliers and aircraft manufacturers is a well-established, worldwide industry. The recent introduction of a new family of alloys that incorporates lithium has posed a new challenge to the recycling industry owing to the high cost of lithium, its high reactivity to the atmosphere and to refractories and its absence from the specifications of all other registered alloys. Various process options for recycling have been identified, but vacuum distillation has been selected as the most cost-effective and technically feasible solution. Experimental work established that the separation of Li from AI-Li scrap is feasible and an industrial process has been designed. The economics of Li recovery are very sensitive to the AI-Li content of the feed material. Owing to the design of aerospace vehicle manufacturing plants it is expected that the swarf will be mixed with other alloys. A method of enriching this feed has been developed that is based on the control of swarf morphology by thermal and mechanical treatments as a precursor to eddy-current separation. After eddy-current separation and vacuum distillation small proportions of Li are retained in the AI residue. The effects of this on the properties of conventional AI-Si shape-casting alloys were investigated and safe threshold levels have been established.

Jan 4, 1993

By Q. H. Liao, B. G. Monaghan

The options for designing slopes in complex geological conditions are reviewed. It is shown that modelling, especially numerical modelling, allows a degree of analysis that cannot otherwise be achieved. Examples are presented of how numerical modelling can be used to investigate fundamental aspects of rock mass behaviour. It is demonstrated that an important consequence of change in scale is that the mechanisms of failure also change. The complex failure of the footwall slope at Aznalcollar, a large open-pit mine in southern Spain, is discussed. Numerical modelling with UDEC (universal distinct-element code) has allowed the realistic simulation of displacements measured in the field

Jun 18, 1905