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By R. T. Grant, C. Bazin, D. Hodouin

It is shown that most of the variation in the results of semi-batch flotation tests is related to the unavoidably stochastic nature of the flotation process. The preparation and analysis of flotation samples and, to some extent, operator error in performing the flotation test procedure are responsible for a small proportion of the observed variability of the calculated flotation performance indices

Jun 17, 1905

By G. E. Pearse, comp.

Questions from the conference delegates and replies by the papers' authors are summarised for sessions on hydropower, metro/rail and water/waste tunnels, tunnel-boring machines, environmental issues, research and case histories, design, and tunnel machinery, with reference to papers on tunnels in Lesotho, Nova Scotia, Italy, UK, Sweden, Kenya, Massachusetts, Germany, Norway, Taiwan, Switzerland, Greece, Malaysia, Australia and Texas.

Dec 1, 1994

By V. Distler, E. F. Stumpfl

Paper presented at the IAGOD international symposium on mineralisation related to mafic and ultramafic rocks held in Orleans, France, 1-3 September 1993. The massif contains large chromite bodies of "Alpine-type", ophiolitic affinity. Orebodies reach thicknesses of 150 m and sizes of more than 150 000 000 t chromite ore with average grades of 55-60 wt% Cr2O3. Chromites in the Main ore field are low-Al, high-Cr spinels which exhibit some variation in their Mg-Fe distribution. This differs markedly from high-Al spinels in peridotite host rocks and in narrow chromite pods which occur in the western and northern parts of the massif. Chromites carry silicate inclusions, often hydrous silicates such as amphibole. Chromites in massive chromitites contain micron size inclusions of platinum group minerals (PGM). Composite grains containing two PGM and, occasionally, a hydrous silicate are common. Os-Ir alloys rimmed by PGM sulpharsenides occur in narrow serpentine veinlets that cut chromite and are evidence for the reconcentration of PGE concomitant with introduction of As, probably during serpentinisation. Whole-rock PGE contents are highest in massive chromitites of Diamond Pearl mine (totals of 500 ppb). Chondrite-normalised PGE patterns of chromitites show negative slopes which are typical for ophiolitic, podiform chromitites in mantle sequences. The PGE patterns of host rocks are flat and rather depleted compared with those of chondrites and chromitites. Petrological data from unaltered host peridotites suggest a high temperature overprint leading to sub-solidus re-equilibration of olivine and spinel and to the growth of pargasitic and edenitic amphiboles

Jun 16, 1905

By L. D. Smith

Paper presented at the conference: Risk assessment in the extractive industries, held in Exeter, UK, 23-24 March 1994, and first published London: IMM, 1994, preprint volume. 22pp., 15 refs. The concept of risk is well established in the mining industry but it is difficult to provide a quantitative assessment of risk. A discussion is presented of the significant sources of risk in a mineral project and how they are addressed. The discount rate is examined as a fundamental means of reflecting risk in discounted cash flow evaluations. Current industry practice is discussed and a methodology for the analysis of risk levels is proposed which assesses the constituent components of the discount rate (real interest, mineral project risks and country risk)

Dec 1, 1994

Paper presented at the conference Risk assessment in the extractive industries, held in Exeter, 23-24 March 1994. Sensitivity analyses based on financial variables are now routinely applied to the forecast financial results of mining projects especially during the feasibility stage. Risk analysis is gaining acceptance but is still almost universally confined to the effects of variations in financial variables. The single most sensitive factor in almost all mining projects is the ore reserve, but it is either ignored or improperly used in sensitivity and risk analyses. Unlike financial variables, the components of the ore reserve (grades and tonnages of mining blocks) are a function of location within the orebody. Physical (mining) access to these components is therefore a function of time which has a crucial effect on forecast cash flows. It is critical that these fundamental concepts are included in risk analyses of mining projects. The effects are considered of the uncertainty of the ore reserve on feasibility studies and open-pit mine design for a small gold mining venture. Geostatistical simulation is used as a method of quantifying the risk in using grades and tonnages estimated from sparse data

Jun 16, 1905

By Thomas D. E.

Discussion at the Manchester Geological and Mining Society' general meeting held in Manchester, March 14th , 1916, with Leonard R. Fletcher, President, in the Chair, of a paper published in Trans. Instn. Min. Engrs., 1916, vol. L., page 482, comprised the author's written response to suggestions made in previous discussion

Dec 1, 1916

Jan 1, 1947

By Hickling G.

Discussion at the Manchester Geological and Mining Society' general meeting held in Manchester, March 14th , 1916, with Leonard R. Fletcher, President, in the Chair, of a paper published in Trans. Inst. M. E., 1915, vol. L., p.328 and 1916, vol. LI., p.91 comprised a written contribution by Faulds A.

Dec 1, 1916

Jan 1, 1947

Jan 1, 1947

By D. H. Watkinson

Paper presented at the IAGOD international symposium on mineralisation related to mafic and ultramafic rocks held in Orleans, France, 1-3 September 1993. Part of the contact of the 4b orebody with the enclosing Murray granite is characterised by the presence of recrystallised and biotitic Sudbury Breccia; in places the contact is faulted and sheared. In other areas of the contact partly silicified granite contains disseminated chalcopyrite and quartz-chalcopyrite veins with other minor minerals. Both ore and veins contain platinum group minerals (PGM); predominant PGM are michenerite, kotulskite, merenskyite and sperrylite with Au, galena and Bi-tellurides. At some silicified-granite contacts Mn-rich garnets, some containing inclusions of PGM and quartz, are associated with biotite + epidote + stilpnomelane + quartz. PGM and Au also occur within Cl-rich biotite and ferropyrosmalite in massive sulphide and in siliceous ore. Quartz, chalcopyrite and feldspar in the contact rocks and in veins contain abundant, highly saline fluid inclusions. Studies showed that the fluids were trapped at intermediate temperatures. The 4b orebody is surrounded by a sheath of brecciated granite but is close to the Contact Sublayer. During and after emplacement of sulphide magma, saline formational fluid that was resident in the breccia interacted with hot massive sulphides in and near the Sublayer and remobilised Cu, Au and PGE. This fluid reacted with cooler rocks and ore in footwall fractures, enriching the 4b protore and producing the adjacent Cu- and PGE-enriched quartz veins. Exploration for Cu and PGE enrichment in footwall rocks of the Sudbury South Range is warranted not only in zones of magmatic ore in the Contact Sublayer but also in fractures and permeable units within Sudbury Breccia

Jun 16, 1905

By Dean S.

Further discussion at the The Midland Counties Institution of Engineers' general meeting held in Nottingham on 6th May 1916, of the paper published in Trans. I.Min.E., vol.L, 1915, p.179, included brief oral contributions by Bragge G.S., Lewis W.H. and Hepplewhite W.H.

Dec 1, 1916

By Le Thac Xinh, van Chu Nguyen

In northern Vietnam Ni-Cu sulphide deposits associated with ultramafic rocks are located in several continental rift zones of Permo-Triassic age. In recent years a number of ultramafic bodies have also been discovered in southern Vietnam, but detailed work on sulphide occurrences within these bodies has still to be undertaken. A brief description is given of some N i-C u sulphide deposits that are located in the northern part of the country. Of the depos­ its that have been examined in any detail, those in the Takhoa region are of the greatest economic interest. Ni and Ni-Cu sulphide bodies have, however, also been found in association with the ultramafic rocks.

Jan 1, 1984

It was intended to show a film on Dust Suppression in the South Wales Coal-mines. Unfortunately, owing to a breakdown, only a small portion of the film was shown.

Jan 1, 1947