Search Documents

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 S. K. Chaulya, R. S. Singh, B. B. Dhar

Two prominent local species, Dendrocalmus strictus (bamboo) and Saccharum spontaneum (kashi), and two exotic species, Cymbopogon citratus (lemon grass) and Vetiveria zizanoides (vetiver), were selected for growth trials on dumps at Mandaman, Chora, Mudidih, South Balanda and Ghugus. The climate at these sites is dry tropical and the surface soil layer a slightly acid to neutral sandy to clayey loam 10-11 cm thick, impoverished in major plant nutrients. After two years bamboo had grown the most, up to 325 cm in height, and contributed the greatest biomass, 638 g/m2 of plant. The local kashi species had a very good regenerative capacity, which was lacking in the lemon grass and vetiver. The grasses had very good soil-binding capacity and could also provide income if used as cash crops

Jun 21, 1905

By G. Merrington, B. J. Alloway

Tailings from three historical mining areas in the UK were leached in columns under a simulated weathering programme which was chosen to represent periods of 1 and 2 years at 3 different ambient temperatures. The total concentrations of Cd, Cu, Pb and Zn in the primary ore minerals present in the tailings showed only a limited correlation with metal concentrations in the leachate. The leachate from columns of tailings that were maintained at a temperature of 25 (+/-3) degrees C contained, on average, 50% more Pb and 75% more Cu than leachate from tailings that were maintained at a temperature of 10 (+/-3) degrees C. The pH values of leachates from all three types of tailings at 25 (+/-3) degrees C were 0.2 units lower than those from columns maintained at 10 (+/-3) degrees C. The concentration of Cd and Zn in the tailings leachates showed no marked difference at the different temperatures. The composition of the leachate was found to be dependent on the type of gangue mineral, the presence of other sulphide minerals and the formation of secondary iron minerals. A comparison of the concentrations of heavy metals in the leachates produced in the laboratory with those in leachates that were collected in the field over a similar period of time from two of the mine sites showed that concentrations were of a similar order.

Jan 8, 1993

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 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 C. C. Harris

The two best known graphical methods for presenting and comparing comminution data are obtained by linearising the Gates-Gaudin-Schuhmann and the Rosin-Rammler size distribution equations. It is shown that the Gates-Gaudin-Schuhmann equation can cause excessive congestion in the 50 per cent oversize range and that, overall, the Rosin-Rammler is a better procedure. Examples are given

Dec 1, 1971

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. Baker

Vapour pressures of sulphur have been measured over the temperature range 340-1039°C by means of boiling-point measurements, an internally heated pressure vessel being employed with argon as the pressure medium. The results are expressed satisfactorily by a four-term pressure-temperature relation. At the cited critical temperature of 1040°C the calculated critical pressure is 204 atm. From the pressure-temperature relation and available thermal data for the vapour, the approximate composition of the saturated vapour in terms of the various molecular species has been derived for the critical point

Dec 1, 1971

By D. L. Buchanan, M. J. Jones

In May, 1982, the University of Western Australia in Perth hosted a three-day international conference on nickel sulphides, followed by a ten-day field excursion to the Western Australian nickel sulphide deposits. The conference was arranged by Professor D. I. Groves, C. M. Lesher and Dr. R. E. T. Hill under the auspices of the International Geological Correlation Programme's Projects 161 ("Sulphide deposits in mafic and ultramafic rocks") and 91 ("Metallogeny of the Pre- cambrian"). This volume contains a selection of the papers that were presented at the Perth conference. Most of the papers are related to the nickel sulphide deposits of Western Australia, but contributions with settings in North America, Finland, Vietnam and Southern Africa have also been included.

Jan 1, 1984

Discussion of the paper presented at the North Staffordshire Institute of Mining and Mechanical Engineers' general meeting held in Stoke-on-Trent, March 27th 1916, with Mr. John Gregory, President, in the chair, included contributions by Gregory J., Cadman J., Hartley J.W., Wain E.B. and Henshaw A.M., followed by the author's reply

Dec 1, 1916

By P. Rama Krishna, B. Narasimha Rao, P. Ali i Peera

Induced polarisation (IP) surveys are commonly used in uranium exploration programmes in India. The IP method is effective in detecting the disseminated metallic sulphides that are often associated with uranium minerals. However, conductive and polarisable host rock or overburden often introduces inductive or electromagnetic (EM) coupling into time domain IP measurements. This makes it difficult to distinguish between responses due to such coupling and those that might indicate economic mineralisation. Attempts must be made to remove the EM effects before the IP technique is used in drilling programmes. Transient decay curves which were recorded during field surveys at Pisnari were factorised using the Marquardt algorithm. Dispersion plots of the amplitudes and relaxation times of the composite exponential function enable a clear distinction to be made between the effects of EM coupling and those of mineralisation.

Jan 4, 1993

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 I S. Lowndes, K. Moloney

Diesel powered equipment is currently used extensively in mining and tunnelling operations around the world due to its mobility, flexibility and through selective application to enhance productivity. However, the increased use of diesel equipment has exacerbated the pollutant load (including heat, humidity, exhaust gases and particulates) placed upon the environmental systems of many underground operations. This expansion in the use of diesel equipment has prom pted researchers to evaluate m easure ment and control technology. This paper reviews the recent research conducted in various countries.

Jan 10, 1996

By A. D. Read

Selective flocculation was investigated as a possible method of recovering values from mineral slimes which are too finely divided to be treated by conventional mineral processing methods. It has proved possible to flocculate selectively either haematite or a silicate from a stably dispersed mixture by varying the anionic character of the high-molecular-weight, partially hydrolysed polyacrylamide employed. Different separation methods have been developed for hard and soft water media. Electrokinetic and infrared techniques have been employed to elucidate the mechanism whereby selectivity has been attained in the different cases. The following influences on the various selective flocculation parameters have been investigated: (a) the level of the different reagent additions and (b) the shear conditions during and after flocculant addition. A feature of the particular system studied was the high solids content at which it was possible to achieve good selectivity. Probable reasons for this are advanced, and the possibilities and potentialities of the process are discussed.

Dec 1, 1971

By Winmill T. F.

Among the various theories proposed to account for the spontaneous ignjtion of coal, one which has at times been very strongly held is that the initial heating is due to the oxidation of iron pyrites. From the results described in this paper, it is possible to calculate roughly the rate of spontaneous heating of a specimen of finely-divided pyrites, on the assumption that all the heat developed is used in raising the temperature of the pyrites, and that none is lost. It is clear that where finely-divided pyrites occurs in considerable proportion among coal, it may be the chief factor in originating combustion, but that pyrites can only be the cause of a heating when it is present in considerable proportion, and in a very finely-divided state

Dec 1, 1916

By G. Richards

Application of the Internet of Things (IoT) technologies - the interconnection of uniquely identifiable embedded computing devices within the existing internet infrastructure - to the mining industry is discussed. IoT technologies are aimed at making projects safer, better optimised and more economic and are applicable to current or new underground or open-pit mines, regardless of size. Two examples are presented of successful implementation of IoT technologies, the Chelopech gold, copper and silver mine in Bulgaria, where production has increased from 500 000 to 2 000 000 tonnes/y and communication costs have been reduced by US $2 500 000 over 2 y, and the Pilbara project in Western Australia, where remotely controlled wirelessly connected autonomous trucks have covered ca. 3 000 000 miles and hauled almost 250 000 000 t of ore since 2008

Apr 1, 2015

By D. W. Holliday

The major deposits of anhydrite and secondary gypsum in Jamaica occur discontinuously at a single horizon within the Lower Eocene succession of southeast Jamaica. They are not intruded from other horizons of different age, as has previously been supposed. The gypsum and anhydrite occur in a regressive sequence at the junction between marine (Richmond Formation, Halberstadt Volcanics, Halberstadt Limestone) and overlying non-marine (Wagwater Formation) sediments. They are thought to have been formed in an arid supratidal (sabkha) environment. A variety of 'nodular' structures occurs in the gypsum and anhydrite which can be related to early diagenetic processes and compaction effects. All gradations exist between single isolated anhydrite nodules and structureless anhydrite due to closer packing and coalescence of nodules. The structures and textures in the anhydrite are thought to be consistent with penecontemporaneous formation from gypsum crystals rarely more than 2 cm in diameter. Single anhydrite nodules are not usually larger than 2 cm; nodules of greater size are compound, due to the coalescence of several smaller nodules. Some large compound nodules may have developed from single sand crystals or rosettes. Compaction of anhydrite appears to have been largely mechanical, but some rocks have an aligned fabric, suggesting later flowage

Dec 1, 1971

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

Discussion of the paper presented at the Manchester Geological and Mining Society's general meeting held in Manchester, April 11th 1916, with Mr. Leonard R. Fletcher, President, in the chair, included questions asked and points for discussion raised by Bramall V., Paton J.D., Fletcher L.R., Siddall F.N., Stoker A. and Stone T., in particular on how to eliminate dust

Dec 1, 1916

By M. Riddell

This paper describes the incipient heatings that occurred below ground in the High Main and Main seams at the mine between the years 1963 and 1966. The possible causes, effects and activities associated with such heatings are discussed in an attempt to establish the precautions necessary to minimize such occurrences. The assessment of as many "norms" as possible is made to enable the earliest detection and level of activity to be determined.

May 23, 1905