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By P. C. Kapur

Several empirical and semi-empirical laws of comminution, which describe the relationships between the cumulative grinding energy input and the degree of size reduction of brittle solids, have been rationally derived in the time-domain in a unified manner, starting with an integro-differential equation of grinding kinetics. The analysis leads to and provides explicit interrelationships between the energy-size reduction laws associated with Kick, Rittinger, Holmes, Bond, Charles and others, and gives useful estimates of their relative merits and validity. It is shown that Holmes' expression is, in fact, a solution to the grinding equation; consequently, this classical law is compatible with the modern theory of comminution based on population balance on particulate species

Dec 1, 1971

Paper presented at the Mining Institute of Scotland's annual general meeting held in Glasgow, 8th April 1916. Although there is nothing novel or difficult about the sinking described, circular shafts are not numerous in Scotland so the details connected with such a sinking may be of interest. The shaft was sunk at Dykehead Colliery, Larkhall, which has been worked for over 50 years from the upper seams. It became necessary to sink another shaft to serve as a replacement downcast, by which the output might be maintained and some of the lower seams won. As the sandy clays regularly caused bulging into the rectangular shaft and sinking of the surrounding ground it was decided to make the new shaft circular and to enclose its mouth in a foundation-block of concrete resting on the solid clay. Details are given of the sinking, brick seating and lining, kettle strike, water-rings and doorhead lintels as well as the permanent fittings, winding gear and the cages themselves

Dec 1, 1916

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 W. H. McAllister

The paper considers the geology and the coalfields that comprise the Scottish south area. It traces the history of known sources of spontaneous combustion and indicates the collieries concerned, with the position of the seams in the geological series where heatings have occurred. The methods of work over the years are described. It relates in detail the circumstances surrounding a fire at Bilston Glen Colliery in the Lothian Coalfield, and the heating at Killoch Colliery in the Ayrshire Coalfield, and the steps taken to deal with them. It also describes some of the difficulties in steep seam working. Methods adopted to prevent spontaneous combustion throughout the area are discussed, and some detail of the UNOR gas analyser is given. Finally, it comments on the present techniques in use in the area, particularly at Bilston Glen Colliery, to prevent spontaneous combustion.

May 23, 1905

By A. H. G. Mitchell

Gold-poor and gold-rich porphyry and epithermal gold-silver deposits of Caenozoic and Cretaceous age in the western Pacific and central and eastern Europe are confined to predominantly andesitic continental margins and island arcs. The arc volcanic rocks overlie a complex non-oceanic basement of stacked nappes, the uppermost of which is often ophiolitic. The emplacement of ophiolite triggered a reversal of tectonic polarity, subduction and arc magmatism. Andesitic volcanism and the formation of a strato-volcano were followed by the ascent of magma and porphyry copper mineralisation. Regional propylitic alteration came from convecting, predominantly meteoric fluids. Magmatic degassing caused advanced argillic alteration. This is commonly unmineralised in perched water tables, but may sometimes host high sulphidation gold or enargite gold at deeper levels within the propylitic zone. The onset of extensional stress after the andesitic volcanism allowed meteoric water to circulate to depths of 5 km or more, with consequent cooling of an ascending magma body at depth and the development of low sulphidation epithermal gold mineralisation near and immediately above the sub-volcanic basement surface. All andesitic arcs are mineralised. Regional controls on their ore potential include the level of erosion and geological features in the basement that focus the ascent of fluids. Differences between the mineralisation of the European and the western Pacific arcs may reflect the presence of older, more granitic basements in many of the European arcs.

Jan 12, 1992

By D. C. Yates, G. V. Jolliffe

In the five coalfields of Staffordshire, there have been some 43 incidents of spontaneous fires and heatings which have required special attention in the past ten years. This total excludes incidents in the Thick Coal Seam of South Staffordshire, which was worked until 1967, and which was subject to an almost continuous series of heatings. The incidents have been classified to show the sites of occurrence, the contributory factors which may have caused them and the treatments applied to them. The remedial techniques, as practised in Staffordshire, are dealt with in detail, with particular reference to standard methods of stopping-off. Precautionary measures taken are described, including a "liability to spontaneous combustion" classification of all seams, and the setting up of an emergency organization with emergency stocks of materials and equipment. The paper is concluded by a few words on the organization and control at the time of an incident.

May 23, 1905

By Tuncel M. Yegulalp, Selamet G. Ergelebi

A description is given of a method of analysing modern mining systems in terms of reliability and their effects on productivity. Non-exponential distributions, such as the Weibull and lognormal distributions, for failure and equipment repair times are also considered. The resulting non-homogeneous Markov process is solved by the method of stages. A longwall mining system is analysed as an example.

Jan 4, 1993

By Hickling G.

Discussion at the Manchester Geological and Mining Society's general meeting held in Manchester, February 8th 1916, with Mr. Leonard R. Fletcher, President, in the chair, of papers previously published in Trans. Inst. Min. Engrs.,1915, vol. L, p.322 and p.328. Included are a written contribution by Ollerenshaw W. and oral discussion by the author, Gerrard J., Paton J.D., Smith S.A., Stephenson H., Dixon H.O., Pickup W., Fletcher L.R. and Atherton H.S.

Dec 1, 1916

By F. Boudreault, M. J. Scobie, J. Szymanski, C. Hendricks

The development of new stoping methods and more effective control over dilution, recovery and fragmentation depends on improved accuracy in blasthole drilling. The mechanisms and factors which control accuracy are poorly understood. Canadian blasthole stoping and the practices adopted for monitoring and controlling drilling accuracy are reviewed. The techniques and problems associated with blashole set-up and trajectory surveying are discussed. Four new blasthole trajectory survey systems are evaluated on the basis of their performance in recent underground trials. Conclusions are drawn as to the technological developments required so that more precise control over drilling accuracy can be achieved.

Jan 12, 1992

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 C. J. V. Wheatley

Recent studies of the mineralisation at Avoca in southeast Ireland, Parys Mountain in Anglesey, and Coniston in the Lake District result in the proposal of a new metallogenetic model for mineral deposits in the Southern Caledonides. A regional pattern of metal zoning exists, an axial belt, including the major copper deposits, being bordered by areas with lead-zinc deposits. Conformable lenticular pyritic zones occur in the central belt, closely associated with acid volcanic sequences and, often, post-dating them. These zones are thought to have been formed in a marine environment, mineral growth taking place below the sediment-water interface, whereas magnetite-rich zones developed under different Eh and pH conditions. Stockworks containing appreciable copper and, in some cases, lead and zinc were developed at a later date, stratigraphically below the pyritic zones, by migrating hydrothermal chloride and metal-rich fluids. Complex lead-zinc-pyrite mineralisation resulted from the reaction between pyritic zones and the final fraction of the hydrothermal fluids. Crosscutting vein-type fissure infilling mineralisation occurs in every mineral field. These deposits apparently comprise a pulsatory metasomatic sequence, closely related to tectono-stratigraphic controls, ore localisation being influenced by the coincidence of suitable structures and pyritic shale horizons. The implications for mineral exploration are considered and it is concluded that the model offers an explanation for the existing pattern of metal zoning; and it may have wide applicability to mineral deposition in geosynclinal sequences.

Dec 1, 1971

By Z Hu

The technique of reclaiming disturbed land by use of a hydraulic dredge pump (HDP) (which is a set of hydraulic machines for earthwork), termed 'digging deep to fill shallow has been used in the reclamation of subsidence areas in Chinese coal mines. This paper discusses the operational principle of the technique and summarises its reclamation procedures, which are being used in current reclamation practice. The soil condition reclaimed by the HDP was studied. The results showed that the pioneer crops to be planted in the reclaimed soil should be the ‘pulse’ family crops, and that improvements to the reclaimed soil and the HDP technique itself are needed. Bused on the analysis of the previous technical processes, a new rational technical model for the HDP reclamation method is presented in this paper.

Jan 4, 1996

By J. Ostwald, L. T. Matthews, C. E. Loo

Australia has large reserves of pisolitic limonite. Mining recently commenced on the Yandicoogina deposit to produce a high-grade sintering ore. The ore contains about 10 wt% combined water and simulated sintering temperature profiles indicate that progressive dehydration of ore particles occurs in the temperature range 300-700 degrees C. Studies by optical microscopy show that although the dehyrdrated ore particles contain numerous cracks, there is no change in the microstructure of the ore because topotactic transformation to haematite results in the formation of compact masses of very fine-grained haematite microcrysts. When the ore is held at around 1 200 degrees C for 1 min significant recrystallisation of these microcrysts occurs, resulting in the formation of optically visible, micrometre sized haematite crystallites. Studies to simulate the behaviour of ore particles during sintering (as nuclear particles surrounded by a standard adhering fines mixture) show that the recrystallisation process occurs much earlier at temperatures of about 900 degrees C. Further studies indicate that CaO in the adhering fines mixture enhances the recrystallisation of the ore nuclei. The results of the investigation indicate that the pseudo-relict haematite in sinters produced from ore blends that contain significant levels of pisolitic limonite consists of dehydrated goethite that has undergone significant recrystallisation and grain growth, a phenomenon that is facilitated by the presence of lime derived from the sintering melt.

Jan 12, 1992

By M. L. Schmulian

"The Windarra nickel deposits display many of the characteristics that typify Archaean volcanic peridotite-associated nickel sulphide ores of Western Australia. The Fe-Ni-Cu sulphide mineralization, which comprises dominantly disseminated sulphides, occurs at the base of a differentiated ultramafic volcanic pile grading upwards from massive meta-peridotitic flows to thin, locally spinifex-textured meta-picritic units. The entire mafic-ultramafic belt has been subjected to mid-amphibolite- facies metamorphism. The ore-bearing ultramafic is immediately underlain by dominantly sulphide-facies banded iron formation (BIF), which commonly contains nickel sulphides adjacent to its contact with mineralized ultramafic. BIF-hosted ores are formed both by physical remobilization of ultramafic-hosted sulphides and by migration of Ni and Cu into pre-existing iron sulphides.At Mt. Windarra the mineralization comprises eight steeply dipping, steeply plunging elongate oreshoots, which display a marked parallelism with major and minor fold structures in the underlying BIF. Seven of the shoots occur at or close to the base of the ultramafic pile, and are hosted by at least three overlapping flows. The zone of overlap occurs at the northern end of each flow, where picritic ultramafic, representing a dominantly liquid portion of the flow, occupies the basal contact. A gross south- north ultramafic flow direction is inferred. The eighth shoot occurs in a stratigraphically higher position within the ultramafic sequence.At South Windarra at least two overlapping mineralized flows occupy the basal contact, the ore zone having a strike extent three to four times its downdip extent. There is no obvious structural control to the mineralization."

Jan 1, 1984

By F. Reich, S. L. Chryssoulis, K. G. Stowe

The surface chemistry of particulates from mineral processing streams can be determined by laser-probe microanalysis. The small area of analysis (2-30 micrometres) enables the surfaces of individual grains to be characterised. Conclusions are based on data acquired from a statistically significant number of grains of a given type. Maps showing the distribution of elements on the surface of mineral particulates can be obtained by time-of-flight secondary ion mass spectrometry. The importance of such analyses in understanding the response of minerals to beneficiation practices is discussed with reference to three examples. The first relates to the loss of selectivity in the differential flotation of a base-metal ore, the second to the different flotabilities of coarse- and fine-grained pentlandite from a Cu-Ni ore and the third concerns the preg-robbing effects of organic matter in a carbonaceous gold ore.

Jan 4, 1992

By R. W. Ruddle

The advent of new methods of roasting, “flash roasting and fluidisation”, which are now under development, combined with the use of oxygen-enriched air, may markedly increase the SO2 content of roaster smokes. Skogmo suggests that the production of smokes containing as much as 50 per cent SO2 should be feasible. The use of flash smelting processes may well enable a similar increase in the SO2 content of smelter smokes to be made. In this event the recovery of sulphur would be greatly cheapened and the process might well be much more economic, even if allowance is made for the cost of generating the oxygen

Jan 1, 1953

By Winmill T. F.

The previous papers have been concerned only with the atmospheric oxidation of coals from the Barnsley Seam, for which it has been shown that an adequate explanation of the origin and nature of gob-fires can be based on the reaction between the coal itself and the oxygen of the air without the intervention of any other substance. It becomes of importance, therefore, to ascertain how far a similar explanation will hold good for spontaneous heating in other seams, and with this object in view samples including anthracite and lignite have been taken from a considerable number of pits in different parts of the UK (south Wales, Northumberland and Durham, north Staffordshire, Portrush and Ayrshire), some liable to fire, others not. There is abundant evidence to support the commonly-accepted view that spontaneous heating is due to the heat evolved during the absorption of oxygen from the air by coal or pyrites. The quantity of heat produced by the reaction has been measured and it has been shown that the observed rate of heating of a sample of coal agrees with the rate calculated from the heat of reaction and the rate of absorption of oxygen

Dec 1, 1916

By Li Shibo, C. Halls

The compositions of olivine, pyroxene and chromite from the Proterozoic ultramafic complex are analagous to those of cumulate ultramafic rocks of tholeiitic origin, suggesting that the parent magma may have been tholeiitic rather than komatiitic. The complex contains economically significant Ni-Cu sulphide mineralisation. The high sulphide/silicate ratio is best explained in terms of the segregation of sulphides from a large volume of magma, of which all but the ultramafic cumulate fraction has since been eroded. Platinum-group minerals that have been identified include sperrylite, moncheite, native platinum, froodite, merenskyite, michenerite and Pd-rich pentlandite lamellae exsolved from pyrrhotite. They are characteristically found in close association with chalcopyrite, either along the contacts between hydrosilicate and sulphide grains or in cracks within pentlandite and chalcopyrite, which may also be intergrown with galena. Crystallisation from a Cu-rich residual magmatic liquid also enriched in Pt, Pd, As, Sb, Bi, Te, Zn and Pb is postulated.

Jan 12, 1993

"The Archaean komatiite-associated nickel sulphide deposits at Kambalda, Western Australia, exhibit a number of stratigraphic features that are indicative of a strong volcanic control on ore localization, including (1) a restriction to specific basal cumulate metakomatiite host units, (2) confinement within distinctive synvolcanic embayments in the footwall and (3) variations in the internal structure and composition of overlying and adjacent barren metakomatiite flow's and the distribution of interflow metasediments with proximity to the ore zones.The high magnesium content of the host units (up to 45% MgO volatile-free) in comparison with that of aphyric or spinifex- textured lavas (16-32% MgO) has been considered previously to indicate either magmas/lavas rich in intratelluric olivine or selective accumulation of olivine phenocrysts. The marked linear trend of the oreshoots, basal host units, footwall embayments and the volcanic stratigraphic relationships have been used as evidence for local linear feeding fissures. Rare relict igneous olivine in some host units is, however, demonstrably not intratelluric, and there is no direct or indirect evidence of a proximal eruptive site (e.g. footwall feeders, pyroclastic breccias, ultramafic intrusives) at Kambalda such as at some other deposits of this type. Kambalda is interpreted as a distal rather than proximal volcanic environment.Emplacement of the komatiite sequence at Kambalda was probably controlled by the locations of a few specific eruptive sites relative to regional topographic gradients and influenced by the topography of the pre-existing volcanic surface. Olivine enrichment in the basal host units occurred by in-situ fractionation and cumulus crystallization of olivine during longitudinal lava flow within linear lava conduits, possibly centralized on depressions between non-overlapping footwall basalt flows. The distinctive stratigraphic relationships are attributed to localization of lava conduits along the volcanic pitchline, flanked by more slowly moving parts of the flows. There are analogies with the physical volcanology of Modern basaltic and Proterozoic komatiitic lava flows.A corollary of this model is that the lava conduits thermally eroded and assimilated sulphidic sediments, contributing additional sulphur to sulphur-saturated komatiites or possibly inducing sulphide separation in originally sulphur-undersaturated komatiites. The latter would account for the restriction of ores to linear cumulate komatiite host units (thermally active lava conduits) and the locally mutually exclusive, but stratigraphically equivalent, relationship between the ores and sulphidic metasediments at Kambalda."

Jan 1, 1984

By D. G. Skinner, M. SC. Griffiths

"The natural difficulties associated with the size evaluation of dusts render absolute measurement difficult, or indeed, impossible. Assuming that the desirability of gravi­ metric sampling be conceded, it appears likely tha,t the most suitable means available for physical evaluation are the method of total turbidity measurement, to give a con­ ventional value for specific surface, together with microscopical examination, the great merit of the latter being that in the hands of an experienced operator, semi-quantitative discrimination between coal and other particles is possible.The pipette method, as modified by Fryer, probably-deserves more attention than it has received up to the present. Whatever method is used, it is recommended that in view of the lack of medical knowledge, as much information as possible should be obtained with reference to the total mass concentration, the surface area of the total dust,' and the mass and area of the particles below 5μ in size."

Jan 1, 1947