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Jan 1, 1984

By S. Y. Ezz

Report of discussion at February, 1971, IMM general meeting (Chairman : M. J. Cahalan, President) of a paper published in Transactions/ Section C (Mineral Processing & Extractive Metallurgy), vol. 79, September, 1970, pp. C226-C233 with contributions by Wild R. and Astier J. on fluidised bed reduction of iron ore fines

Dec 1, 1971

By G. D. Nicholls

There have been very few attempts to isolate the various factors that contribute to the overall imprecision of geochemical analytical procedures, due in part to the difficulty of distinguishing between them. The technique of spark source mass spectrography permits a ready distinction between the contributions to overall precision from sampling error and instrumental and other errors. With conventional methods of sample preparation for this technique sampling difficulties are responsible for 80-90 per cent of the overall imprecision. Examination of the probable location of the major difficulties in sample preparation indicates that the preliminary stage of grinding, mixing and extraction of a first aliquot (about 1/100 of the original sample) is generally perfectly adequate. The difficulty lies in the subsequent stages of sample preparation. Dry mixing techniques are unlikely to give good precision if the sub-samples actually examined by the analytical technique are less than 10 mg in amount. Solution techniques are less prone to sampling difficulty. Fusion techniques, unless conducted with great care, can produce more difficulty than dry mixing. Sample preparation is critical to the success of many analytical procedures. Selection of appropriate sample preparation techniques requires just as much care as the selection of techniques for the actual analysis.

Dec 1, 1971

By W. R. Donaghue, R. L. Robinson, C. Scott

Whilst spontaneous combustion has never been considered a major problem in south Durham, certain collieries in the area have a history of heatings and precautions are essential. Three collieries are affected - Shotton, Vane Tempest and Seaham - and in the case of the last two, there are huge areas of high quality coal to work under conditions where spontaneous combustion is a real hazard. The seam being extracted has an immediate roof in goaf left by the incomplete extraction of a contiguous seam worked before the turn of the century. The presence of residual coal stocks and old roadways and cavities adds to the difficulty of preventing unwanted air movement. The main preventive measures adopted are the construction of airtight gateside packs and the use of sprayed surface coatings in the gate. Sampling systems and sampling points are described and, in particular the field of continuous monitoring from the surface is examined. The resulting possibility of a quantitative as well as qualitative assessment of the preventative measures required is discussed.

May 23, 1905

By G. J. Lyman

Mayer curves are used for process calculation in coal preparation. They can also be used to smooth washability data by fitting a hyperbola of particular properties to ash and yield, but to introduce the density variable an independent relationship with ash content must be adopted. When this ash-density relationship has a realistic form at low density, the implied form of the mass distribution function is unrealistic, suggesting that Mayer curves represented by a hyperbolic functional form are unsuited to coal washery calculations for low-density separations. Their use at higher densities is also uncertain. A similar conclusion can be anticipated when Mayer curves are used for other mineral systems.

Jan 8, 1992

By D. L. Buchanan, ed. sci.

The issue comprises 10 contributions on PGE mineralisation, of which 9 were presented at the symposium organised by the IAGOD Commission on Ore Deposits in Mafic and Ultramafic Rocks and the BRGM-CNRS University of Orleans research group. The editor's introduction and summary of the papers is presented together with the title page, contents list and cover photograph of a harzburgite ridge, dunite boundary and chromite quarry in the Shetland ophiolite on Unst

Apr 1, 1994

By L Casari

A study of samples from three sectors of the mine, which was worked from Roman times to 1991, revealed different textures, mineral associations and distributions of trace elements in the sulphides. In the last decade before closure, grades of sphalerite concentrate were in the range 51.67-53.30% Zn and 2.21-2.86% Pb and of galena concentrate 69.43-71.62% Pb and 4.70-8.36% Zn, while the estimated by-product germanium content of sphalerite concentrates sold was 300-400 g/t. Passing the different run-of-mine materials through the same concentrator flowsheet produced middlings and tailings during the preconcentration processing. Separate and alternative treatment of run-of-mine products would have yielded improved recoveries of sphalerite and galena and better values of by-product germanium and cadmium

Jun 18, 1905

By J. R. Budden, P. A. Spencer, J. Barrett

The initially produced arsenic (III) is very toxic to the unconditioned culture but the mixed culture has the capacity to oxidise it to arsenic (V) in the presence of iron (III). It was possible to build up the resistance of the culture through progressive sub-culturing on arseno-pyrite until it could tolerate steady-state concentrations of 30 mM arsenic (III) and 200 mM arsenic (V). With some samples tested in the continuous systems the final arsenic concentrations reached 330 mM. It proved possible to use the laboratory batch data to establish the optimum operating conditions for continuous test systems with capacities of up to 32 m3. Data on the residence time, oxygen uptake rates and gold extraction from the bio-oxidised residues could then be confirmed by continuous testing without the need first to use empirical means to determine optimum conditions for continuous bio-oxidation. The data on residence time, oxygen uptake rate, solids density and neutralisation could be used to estimate the capital and operating costs of treating any given tonnage of the concentrate of interest. It was established that the arsenopyrite concentrates can be suitably bio-oxidised to cause the liberation of at least 90% of the gold content. The method is simple to operate and is flexible over a wide range of external conditions

Apr 1, 1991

By A. J. Beer, A. Wetherelt

Paper presented at the UK minerals industry conference held in Leeds, UK, 3-5 April 1995. Camborne School of Mines has developed a simple, cost-effective light-sectioning method that has been used successfully in tunnels and small stopes. Light sectioning provides an almost visual examination of the stope's excavated profile. An illuminated section of walls, roof and floor is recorded photographically. Overbreak and underbreak can then be easily quantified by reference to the designed shape. The prototype rig is described. Use of a fish-eye lens to capture a greater field of view is discussed. Calibration was achieved by comparison with images made with a conventional wide-angle lens with nominal distortion. The system is reliable under a range of operating conditions including dust, heat and humidity. It is also simple and easy to use, does not require skilled personnel and is low cost

Jun 18, 1905

The probability of detachment of quartz particles from air bubbles during bubble oscillations was investigated by means of a vibration method. Theoretical calculations of the detachment force based on the work of Nutt and Schulze for a single spherical particle show a correlation with the experimental results described. However, the forces that were determined experimentally were considerably lower than the theoretically derived values. Some of the factors which were expected to affect the probability of detachment, such as particle size, bubble size, collector concentration and vibrational acceleration, were also investigated

Dec 1, 1991

By ed. comp., S. H. White, A. J. Naldrett, P. R. Simpson

Peter Simpson's introduction, Tony Naldrett's concluding remarks and discussion by Prof. White of D.M.A. Flight's report of the proceedings are presented from the conference held in Keyworth, UK, in April 1992

Apr 1, 1995

By S. V. Shiraishi, H. B. Bell

Report of discussion at February, 1971, IMM general meeting (Chairman: M. J. Cahalan, President) of a paper published in Transactions/Section C (Mineral Processing & Extractive Metallurgy), vol. 79, June, 1970, pp. C120-C127, with a contribution by Wright P.A. on the miscibility gap

Dec 1, 1971

By J. A. Saunders, E. L. Rowan

It is now widely accepted that the metal-rich waters found in the oil wells are possible present-day analogues of the mineralising solutions that formed the Mississippi Valley-type (MVT) deposits throughout mid-continental USA and elsewhere. A study characterising the trace-metal content provides additional circumstantial evidence for a genetic link between sediment-hosted mineral deposits and basin brines: Ag, Co, Ni, As and Mo, detected in the scale, are locally present in accessory minerals in MVT deposits and the levels of Ag found in the wells support the conclusion that sedimentary sources for silver should be considered in evaluating the origin of Pb-Zn-Ag deposits in sedimentary terrains

Jun 12, 1905

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 C. P. Summerhayes, J. W. G. Gilbey, S. Henley, G. P. Glasby, J. J. T. Harvey, J. Larsson, O. Akiman, A. G. Brown

Abstracts are presented from six University of London, one University of Nottingham and one University of Durham PhD theses

Dec 1, 1971

Two of the most important economies in coal-washing are in the actual washing of the coal and in a proper lay-out to reduce to a minimum the cost of labour for handling and washing. A guarantee is usually required for turning out a washed coal containing not more than 2% of free dirt and a resulting refuse with not more than 2% of free coal; any plant that gives results within such guarantees can he considered economical, provided that there are no other losses during the washing process. Various drainage arrangements and washery lay-outs are illustrated and discussed with respect to drainage, bunkers, sieves, settling tanks and conveyors and two further points considered: siding accommodation, which may become quite important with washeries of large capacity especially when the coal is brought in railway-wagons; and the irregularity with which the coal arrives. (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)

Dec 1, 1916

By Gibson J.

Further discussion at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 3rd June 1916, on the paper published in Trans. I.Min.E., vol.LI, 1916, p.72-84, included a written contribution by Parfitt I.C. and the author's written replies to this and previous discussion

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 R. Patel, J. Ephraim

The production of titanium dioxide (TiO2) from its minerals such as ilmenite is challenging, and subsequent isolation of titanium from TiO2 is even more difficult because of the metal-oxygen bond strength. Currently, titanium sponge is mainly produced via the Kroll process, which is energy intensive and generates large quantities of waste. A number of international research groups have come up with technologies for the production of titanium metal. However, none of them have been commercialised, because of engineering or economic issues. The team at Bradford have confirmed that ultra-pure titanium powders can be separated from TiO2 powder through metallothermic reduction and are working to scale up the process.

May 1, 2015

By K. M. Kinealy, A. R. Ramsden, D. H. French

A negative correlation exists between sphalerite composition and gold content when gold is transported as Au(HS)2(-); however, there are spatial and temporal differences within a single deposit. A previous model for the formation of volcanogenic massive-sulphide deposits within thermally intensifying and waning hydrothermal sytems in much the same way as is observed around modern sea-floor vents is supported. The results also emphasise that recognition of the mechanisms of gold transport in ancient deposits depends critically on an understanding of their mineralogy and stratigraphy

Jan 1, 1991