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By Black J.

Further discussion at the The Midland Counties Institution of Engineers' general meeting held in Nottingham on 6th May 1916, on the paper published in Trans. I.Min.E., vol.L, 1915, p.449, included brief oral contributions by Bragge G.S., Hepplewhite W.H. and Binns G.J.

Dec 1, 1916

By Briggs H.

The illustrated device uses the principle that the lamp can burn with a smaller inlet passage if the air is rich in O2 and that the size of the inlet can be made a measure of O2 percentage. The appliance consists of an adjustable cut-off applied to the inlet of a safety lamp of the improved Gray pattern. Precision is assessed from tables of calibration tests in air contaminated with blackdamp of CO2:N2 composiiton 1:5.67 at temperatures of 40-70 degrees F. Results are presented of tests at St. Germain's colliery, of tests in air contaminated with pure CO2 and of air contaminated with both blackdamp and inflammable gas; published ranges in mine-air blackdamp compositions are tabulated as ranging from 90.06% N2 to 43.90% CO2. When firedamp is present at 1.25-2.5%, its content must first be estimated by means of the cap and a fifth of its value then deducted from the lamp reading for O2

Dec 1, 1916

By Fearnsides W. G.

The map shows the sites of collieries and important boreholes in the district, with approximate underground contours of the pre-Permian surface of the Coal-Measures and of the Barnsley Bed

Dec 1, 1916

By Dean S.

Further discussion at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 12th February 1916, with Mr. T.Y. Greener, President, in the chair, of the paper published in Trans. I.Min.E. vol.L, 1915, p.179 and 388. Written contributions to discussion included Mr. Dean's reply to earlier discussion (p.35-44), further written contributions by Tate S. (p.44-54) and Brown E.O.F. (p.54-56), and oral comments by Hare S., Merivale J.H., Greener T.Y. and Tate S. Particularly debated were the causes of the difference in output between American and British coal miners

Dec 1, 1916

1994 estimates for Porgera are probable and proven reserves of 58 200 000 t of ore grading 5 g/t Au. Gold mineralisation is related to an intrusive complex emplaced at shallow levels in poorly consolidated sedimentary rocks. The complex is located in a zone of fold-and-thrust deformation, whose formation may have been initiated shortly before emplacement and continues locally today. Abundant primary magnetite in the complex gives an intense, 5 km wide aeromagnetic anomaly. The deposit formed during two main stages of mineralisation, the first related to early magmatic-hydrothermal activity and the second representing later epithermal overprinting centred on the Roamane fault. Hydrothermal alteration followed closely on emplacement indicating a close genetic relationship between magmatism and mineralisation. Both stages of hydrothermal activity post-date and overprint early propylitic alteration. Several factors have acted in unison or sequentially to concentrate metals at the deposit, including an extensional or trans-tensional tectonic setting within an arc or collisional environment, the exsolution of a magmatic hydrothermal fluid prior to sulphur saturation in the melt, the development of the hydrothermal system into one favourable for transporting gold, the action of late-stage faulting in focusing epithermal fluid flow, and the role of dissolved gases in promoting fluid phase separation and high-grade ore deposition

Jun 19, 1905

By D. V. Venugopal, W. W. Gardiner

Spessartine-quartz rocks are manganiferous sedimentary rocks rich in spessartine and quartz which occur in north-central New Brunswick. They represent a recrystallised manganiferous siltstone/chert that is contained in or associated with red manganiferous siltstone (RMS) units. The spessartine-quartz rocks and RMS form part of an Ordovician volcanic and sedimentary succession within the Appalachian-Caledonian orogen which hosts numerous massive sulphides and polymetallic vein deposits. The New Brunswick spessartine-quartz rocks are spatially and temporally associated with stratiform base-metal, precious metal and hydrothermal tin-tungsten deposits. This suggests that spessartine-bearing lithologies and zones can be useful in predictive metallogeny and for the understanding of the stratigraphy and palaeographic setting of the early Palaeozoic rocks of the Appalachian-Caledonian orogen.

Jan 12, 1992

A study of the thermodynamic properties of magnesium chloride ammines was carried out with the ultimate objective that the thermal decomposition of the hexammine MgCl2.6NH3 may prove successful on a commercial scale for the manufacture of anhydrous magnesium chloride, which is required for the efficient electrolytic production of magnesium. The experimental data are presented in the form of an equilibrium diagram that aids the understanding of the conditions associated with the thermal decomposition of ammines

Jun 13, 1905

By Dickinson C.

Discussion at the The Midland Counties Institution of Engineers' general meeting held in Nottingham on 6th May 1916, on the paper published in Trans. I.Min.E., vol.XLVIII, 1914, p.400, included brief oral contributions by Bragge G.S. and Hepplewhite W.H. with the author's responses regarding leakage and boring of cement into the coal

Dec 1, 1916

The following procedure was used to determine cut-off grades: define the orebody profile; plan the stope layout and quantify the work involved; formulate equipment-performance norms; calculate unit costs; input process recoveries and metal prices; and calculate the cut-off grade. Use of the method is illustrated using data from a copper mining complex in India. Results from the study led to the following conclusions for underground mines in general. Cut-off dependent costs vary significantly with the stoping method employed, orebody thickness, the degree of mechanisation and the working efficiencies of the workforce and equipment. This applies even within the same deposit. Sub-level stoping and its variants can be operated at a lower cut-off grade than cut-and-fill and its variants. Thinner orebodies affect cut-off grades adversely, but with thinner orebodies very little further reduction in cut-off grade can be achieved once a certain minimum width has been exceeded. For the same stoping method and in the same mine the cut-off grade varies with the degree of mechanisation. Labour-intensive methods require higher cut-off grades. An allowance for working efficiency should be made when calculating cut-off grades. Higher process recoveries allow a significant lowering of cut-off grades

Jul 1, 1996

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

The paper, presented at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 8th April 1916, presents experimental work undertaken to observe the quenching effect of different substances, to find the most efficient of these substances, and to arrive at a possible explanation of their preventive action. The coal-dusts experimented with were such as passed through a 100-mesh sieve (10,000 holes to the square inch), and were obtained by grinding the coals. The quenching substances, used in as fine a state of division as possible, included gypsum, dried Chance mud, quicklime, magnesia, magnesia alba (levis), anhydrous sodium carbonate, sodium bicarbonate, soda-crystals, Glauber salts, ground shale and boiler-ashes

Dec 1, 1916

By J. C. Loretto

The philosophy and detail of mill design in developing countries, where it is frequently difficult to obtain experienced, qualified supervision to operate the plant, are discussed. The resulting design suggests the desirability of simple units, with maximum visibility of equipment operation and material movement, which allow the minimal technical supervision to see the plant conditions prevailing. Information on plant conditions during periods of lesser supervision can be provided by the use of simple, low-maintenance recorders. Where the mill is intended for operation in a developing country, it is insufficient for the flowsheets and plant layouts merely to be drawn: the process metallurgist must pay meticulous attention to details that could ordinarily be left to the design detailing group. The design of this type of mill requires a knowledge of human engineering—of the type of individual who will operate and supervise the plant; probable changes in personnel should be taken into account. Details are suggested for coarse-ore handling, screens, feeders, secondary and tertiary crushers, conveyors, dust collecting, fine-ore feeding, grinding mills, conditioners, flotation, thickeners, filters, reagent systems, sand pumping, sampling, instrumentation, safety and construction

Dec 1, 1971

By T Atkinson, A Cobb, R AJIington

Risk management is concerned with the whole spectrum of financial, geological, engineering, legal, governmental, social and occasionally ethnic issues, concerned with mining projects. The inherent risks in mining operations are well publicised, but new issues and hazards arrive on the scene and lake precedence, but the older risks still remain, while insurance cover may not he ‘full cover’ in the future. It has long been recognised that quantitative approaches to risk analysis can play a major role, but although these methods are capable of considerable theoretical precision, the lack of sound risk input data and experienced personnel limits the usefulness of theoretical analysis. It can, however, greatly assist in comparing cases, in identifying areas of risk and help in the investment decision process. Its major contribution to a mining project is that it imposes an investigative discipline that also assists in improving the quantitative approach to risk analysis and hence risk management. Risk analysis and risk management also requires sound common sense and major inputs from experienced geologists, mining, mechanical, electrical and mineral processing engineers. The Engineering Council, in 1992, issued a ten point code of professional practice entitled ‘Engineers and Risk Issues’ (The Engineering Council. 1992), covering our professional responsibilities, the law, our conduct, the need for a systematic approach to risk issues, the use of professional judgement, communications, risk management, evaluation of risk, our professional development in this field and the encouragement of public awareness of risk issues. This is a specific area of training perhaps long neglected by our industry and academic institutions (Atkinson. 1983).

Jan 5, 1996

By M. C. Amiri

The plant produces 130 kg slag per tonne of crude steel, to add to the basic oxygen steel-making converter slag stockpile of around 2 500 000 t. The slags contain 1.81% V2O5, which can be rendered water-soluble by salt roasting with NaCl and an alkali such as Na2CO3. Preliminary tests gave less than 3% V recovery from slag under optimum roasting conditions when NaCl, NaCO3 or Na2SO4 was used, but showed that sodium phosphate could make all the V water-soluble when roasted with slag in a ratio of 3:1 at 1 100-1 200 degrees C. Almost complete leaching was obtained within 2 h with water at boiling point. Sodium vanadate was precipitated by acidifying the leach liquor with HCl to a pH of about 2.2

Jun 21, 1905

By J. Ivon Graham, T. D. Jones

This paper presents methods in use in British coal-mines for the suppression of dust. While the effect of present-day treatment will not be apparent for several years, in pits in South Wales, concentrations as high as 50 gm./1,000 cu. ft. were some years ago fairly common in various operations at or near the coal-face, with an average concentration of 20 gm./1,000 cu. ft. Now the average concentration in what were previously dusty pits is probably not greater than 3 gm./1,000 cu. ft.Nevertheless, every effort must be made to improve conditions still further. In South Wales it is claimed that 99% of the coal-faces requiring treatment have been dealt with either by wet cutting, infusion, or hand-spraying. The extent of the treatment by these methods can be gauged by the fact that the total length of coal-faces now being treated by water infusion in Cardiff and Swansea areas is about 33,000 yds., by wet cutting 25,000 yds., and by hand-spraying nearly 14,000 yds. The influence of methods of mining upon dust production is only mentioned very briefly in this review, and there is no doubt that much more is to be learned concerning this aspect. It can be stated, however, that good mining practice is essential to prevent unnecessary dust production, and the problem of dust in mines will be solved only by the closest co-operation between mine managers, workmen, and scientists.

Jan 1, 1947

By W. Petruk, M. J. Matos

An aplite ore from Guarda in northern Portugal, containing albite, microcline and quartz and muscovite gangue was studied to identify conditions for extracting the feldspar minerals. The large amounts of quantitative mineralogical data needed to evaluate grinding behaviour were provided by automated image analysis. The images were acquired on polished surfaces by measuring back-scattered electron signals produced with a microprobe. Minerals were identified from X-ray spectra and discriminated by grey level and element-characteristic X-rays. The quantities and size distributions of the minerals were determined by measuring thin sections of unbroken ore to predict the grind required to liberate the feldspars. The ore was then ground to -1.7 mm, polished sections were prepared from sieved fractions and the quantities of mineral species and apparent total liberation were determined by analysis. The predicted and measured liberations were compared and the grinding behaviour of the ore interpreted. In an appended correction, the correct version of Equation 1 is represented and Tables 3 and 6 are revised to consider all size fractions, including those coarser than 300 micrometres, in calculating the total liberation from King's fractional liberation

Jun 18, 1905

By K. C. Misra, W. Wrightson Jr.

The Lick Fork prospect shows appreciable nickel sulphide mineralization in a narrow, steeply dipping, layered sequence of metamorphosed hornblende peridotite, gahhro and hornblende gahhro, intrusive into the Pedlar Formation (charnockitic pyroxene granulite) of the Virginia Blue Ridge Complex (Precambrian). Rocks of the intrusion have equilibrated to granulite- facies metamorphism, as indicated by pervasive polygonal texture of silicate aggregates, development of biotite- and hornblende-preferred orientation, compositional equilibration of the silicate minerals, the Mg-Fe2+ (orthopyroxene-dino- pvroxene) distribution coefficients (average 0.57), (MgO + FeO + Fe20 3)/Al20 3ratios in orthopyroxenes, and Ti contents and AI(i\)/A I(\i) ratios of hornblendes. The sulphides, consisting of pyrrhotite-pentlandite (with up to 4 wt% Co)-chalcopyrite-pyrite-marcasite-violarite- bornite—mackinawite, are virtually restricted to the ultramafic unit of the intrusion and constitute 20-30% of the samples of hornblende peridotite studied. Although the basal accumulation of the sulphides may suggest magmatic segregation, sulphide- silicate textures typical of sulphide liquid immiscibilitv are not present, even in the sparsely mineralized gahbro units. On the other hand, the transgressive and relict textures are strongly suggestive of replacement of the silicate minerals by sulphides. These include chaleopyrite ± pyrrhotite ± pentlandite (violarite) ± pyrite ±magnetite veins crosscutting silicates, sulphide penetration into silicates at silicate-sulphide contact zones, rounding of silicate grains against sulphide matrix, and islands of silicate minerals (olivine, hornblende, pyroxene, biotite) in sulphide masses. Metamorphic mobilization of pre-existing sul­ phides is a possibility, but involvement of post-metamorphic, hydrothermal fluids is suggested by the following features: paucity of annealing and deformation textures in the sulphides, replacement of metamorphic and deformed silicates, lack of differential sulphide mobilization and the common occurrence of sulphides along grain boundaries and triple junctions of poly gonal silicate aggregates. The consistent association between sulphides and hydrothermal alteration products of silicates suggests that they are cogenetic. The hydrothermal fluids may have merely mobilized and concentrated the pre-existing, disseminated, magmatic sulphides, or there may have been significant addition of sulphides during this process. This question cannot be resolved unequivocally with the existing data.

Jan 1, 1984

By G. E. Pearse

Reports, discussions, a written contribution and two written replies are presented from 11 sessions on: Safety and compressed air; Ground movements; Geotechnical; Channel Tunnel (2 sessions); Machines; Case histories; Transport tunnels; Case studies; Site investigation; and Undersea tunnels

Jun 13, 1905

By P Shead, M A. Tuck

Both climate and methane control have been a prime concern in the development of the workings within the Deep Soft seam at Harworth Colliery. This paper describes the numerous methods employed over the past 15 years to effect control over these two major environmental pollutants at Harworth and describes a future method of working which will enable the output levels required to be achieved, whilst effecting the required level of both climatic and methane control. Firstly, the paper gives a broad historical overview of the steps taken since 1981, when production started in the Deep Soft seam at Harworth Colliery, to effect control over the main environmental pollutants in the seam. Secondly, the paper details the results of planning exercises undertaken to assess the various options with respect to panel layout, to achieve environmental control in future production districts. Finally, the recommended method of panel design to achieve the levels of production required is detailed.

Jan 7, 1997

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