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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 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

Summary of the morning's events with a Written Contribution to Paper No. 4 and author responses

Jan 1, 1947

By Schwartz M.

The current status of the heavy and light rare-earth elements outside China is reviewed. New suppliers of the light rare-earth elements are Lynas (Australia/Malaysia) and Molycorp (USA), which are anticipated to process 11 000 and up to 10 000 t/y, respectively, and the most advanced heavy rare-earth elements project is Avalon's Nechalacho project at Thor Lake, Northwest Territories, Canada. U3O8 Corp has potential rare-earth elements production, e.g. ytrrium and neodymium, from its Berlin deposit in Colombia and Namibia Rare Earth's Lofdal project (Area 4) has potential to produce an average of 1 500 t/y of separated rare-earth oxides. With regard to the three historical producers, India has some small-scale production, Brazil has been a small-volume producer and has potential for new heavy rare-earth elements production, while South Africa has no current production

Feb 1, 2015

By J. A. Franklin, E. Broch, G. Walton

To make the best use of rock core, the mechanical character of the rock should be evaluated concurrently with conventional geological observations. The advent of simple techniques, such as the point load 'nutcracker' test, makes field logging of mechanical properties competitive with sampling and testing in the laboratory

Dec 1, 1971

By Mowat D. M., Louis H., Smith W. Mackey W. M., Dron R. W., Ellison C. C., Winmill T. F., Kerr G. L., Haldane J. S., Ashworth J., Garforth W., O'Shea L. T.

Discussion of Winmill's paper, including various anecdotal examples, is presented together with the author's response; topics included: the need to distinguish cubic pyrites from the rapidly decomposing rhombic form known as marcasite; the effects of moisture content in the coal and air; the possible effect of pressure; the heat insulation resulting from heap/stack size; and the means of determining pyrite and moisture contents

Dec 1, 1916

By B. W. Hester

Report of discussion at January, 1971, general meeting (Chairman: M. J. Cahalan, President) of the paper published in Transactions/Section B (Applied Earth Science), vol. 79, May, 1970, pp. B60-B67, and contributed remarks. Comments were made by Taylor J.T.M., James C.H., Lethbridge R.F. and Heath K.C.G.

Dec 1, 1971

By A. Z. Lang, D. A. Hall

After a brief description of the causes of spontaneous heating and of general preventative methods, a detailed account is given of occurrences of spontaneous heating in the Main Seam (locally known as the 5/4 Seam) at Westoe Colliery. This seam is about 12 feet thick consisting of hands of coal and shale, but only 4 feet 6 inches is worked because of the thickness os strata in water-bearing rocks and the worked section is selected on quality considerations. An advancing longwall face in this seam (2nd South) began to heat after working for six months and ultimately had to be abandoned. By adopting retreating methods and mining narrow panels it has been possible to extract this coal at an excellent rate of productivity. The system of goaf ventilation is important, because the use of a bleed road would have given rise to dangerous conditions in a goaf which of necessity would have contained fallen coal. Preparatory seals were prepared at selected sites so that, if necessary, a panel could be sealed off quickly; these seals are completed as soon as possible (within three weeks) of finishing a panel. A gas sampling system has been instituted which includes daily sampling on the face and in the goaf, and weekly sampling at the stoppings of all completed panels. The coal has now been extracted from this seam for three years without any further difficulties from spontaneous heating.

May 23, 1905

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 J. R. Hammond, I. C. Herbert

Report of discussion at October, 1970, IMM general meeting (Chairman: M. J. Cahalan, President) and contributed remarks on the paper published in Transactions/Section C (Mineral Processing & Extractive Metallurgy), vol. 79, June, 1970, pp. C128-36 and introduced by I.C. Herbert. Contributors were von Struve G., on the application of balling discs and the use of basic additives; Young P.A., asking for details of the drying, grinding, balling, induration and specification testing equipment and processes; Davison J. on pellet swelling properties and Carter G.C. on disc operation, refractories and green ball properties.

Dec 1, 1971

By NA NA

Reports of discussion at sessions held in Keyworth, UK, on 22-23 April 1992.

Jan 12, 1992

The report of the Annual General Meeting of the Institution of Mining and Metallurgy held on Thursday, 20 May, 1971, in the rooms of the Geological Society of London, Burlington House, Piccadilly, London, W.1, at 4 p.m. (Chairman : M. J. Cahalan, President) includes details of awards and prizes presented to William Justin Kroll, Sir Gordon Colvin Lindesay Clark, John Convey, Evert Hoek, Peter Reginald Dawson and Christopher Michael St. John

Dec 1, 1971

By D. J. Allan, W. R. Wilson

For conventional aerospace aluminium alloys of the 2000 (copper) and 7000 (zinc, magnesium) series the recycling of process scrap from both metal suppliers and aircraft manufacturers is a well-established, worldwide industry. The recent introduction of a new family of alloys that incorporates lithium has posed a new challenge to the recycling industry owing to the high cost of lithium, its high reactivity to the atmosphere and to refractories and its absence from the specifications of all other registered alloys. Various process options for recycling have been identified, but vacuum distillation has been selected as the most cost-effective and technically feasible solution. Experimental work established that the separation of Li from AI-Li scrap is feasible and an industrial process has been designed. The economics of Li recovery are very sensitive to the AI-Li content of the feed material. Owing to the design of aerospace vehicle manufacturing plants it is expected that the swarf will be mixed with other alloys. A method of enriching this feed has been developed that is based on the control of swarf morphology by thermal and mechanical treatments as a precursor to eddy-current separation. After eddy-current separation and vacuum distillation small proportions of Li are retained in the AI residue. The effects of this on the properties of conventional AI-Si shape-casting alloys were investigated and safe threshold levels have been established.

Jan 4, 1993

By R. M. Honey

An attempt is made to summarise the mining law of England, Wales and Scotland. Attention is also drawn to the recent privatisation of the electric power and gas industries and the intention of the present Government to follow suit as regards coal mining. The subject of mining law is discussed under the headings: minerals or rights that have been nationalised or are vested in the Crown; ownership (of land and mineral rights); special customs; tracing of owners; right of support (arising from mining); ancillary rights and easements; obtaining prospecting and mining rights; planning permission; statutory aids to obtaining rights; notes on the history, law and practices of petroleum (onshore and offshore), gas, coal, prescribed substances, gold and silver; electricity; safety, health and welfare; and technical information and boreholes. A correction in the subsequent issue amends errors on p.A75 and A82 and regrets the publication of misinformation on the availability of grants

May 1, 1991

By A. Ludkin

The paper presents the history of the occurrence of spontaneous combustion in the north area, together with the associated problems. These are examined and a description is given of the methods used to combat the danger, including the use of modern scientific instrumentation. Detailed reference is made to the underground trials with pack injection and sealant coatings which were carried out at Seafield Colliery following the formation of a working group to assess the performance, in the same underground conditions, of (1) sandbagging, (2) pack injection, (3) surface coating. Based on these trials, an improved and more economical method of prevention has been established. There is, however, still scope for further improvement in techniques which would take into account the problems of gradient, transport, manpower and cost.

May 23, 1905

By R. I. Jeffery, J. W. Summers

An account is given of the verification and calibration of a numerical modelling technique that has been developed for the prediction of subsurface strata deformation following the extraction of coal by longwall mining methods.

Jan 4, 1992

By W. R. Chambers

A wide variety of mining conditions exists within the South Midlands Area and across this range of conditions more than one half of the mines are highly susceptible to spontaneous combustion. Two thick seams in which the greatest risk exists are described and illustrated. The different heatings which take place are categorized by the locations at which they occur in the mines: additional special cases not easily categorized by location are discussed separately. The discussion for each category of heating follows the pattern of: (i) the reasons why it occurs; (ii) when it arises the means by which it is fought, and (iii) the preventive measures taken in an attempt to avoid its occurrence. Relatively new factors which may affect the incidence of heatings are highlighted and suggestions are made which may assist in reducing the number of incidents in the Area. A new method of continuous sampling, analysis and recording is described and mention made of an original method of interpreting carbon monoxide results with the aid of the computer. The first results from this work show that an early warning is given of an adverse change in trend several weeks earlier than with the present methods. Lastly, suggestions are made about the direction in which research might proceed to assist in reducing the special hazards created by several features inherent in the present methods of mining.

May 23, 1905

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 J A. Hacked

This paper explores the potential to exploit controls over the outputs of the primary blasting operation, arising from the performance consistency benefits gained in using modern bulk emulsion explosives technology. The former, allied with the latest powerful blast predictive software and measuring tools, offers the user the opportunity to apply control over both cost and performance, which has not been possible in the past.

Jan 12, 1997

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