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By D. D. Lei, H. Sevim

Long-term production planning in open-pit mines requires the determination of cut-off grade, mining and milling production rates, a mining sequence, mine life and ultimate pit limits. Since these variables interact in a circular fashion, a genuine solution to the problem necessitates their simultaneous determination. A methodology with this capability is described. This comprises a group of heuristic algorithms and an unconventional dynamic programming algorithm. The method is demonstrated using data for a gold deposit in the western USA

Jul 1, 1996

By A. W. Fletcher

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, December, 1970, pp. C247-52, and contributed remarks. Contributions are included from: Cahalan M.J., giving figures related to leaching Cu from pyrite at Rio Tinto 1880-1910; Noakes F.D.L.; Embling P.M.K.; Bradshaw A.V.; Le Roux N.W.; Kelly D.P.; and Tuovinen O.H. Questions were raised regarding impurity removal, effects of light and ultraviolet light on the bacteria, the economics of solvent extraction and the possibilities for other organisms or other metals

Dec 1, 1971

By T. Sharma, T. C. Rao

Laboratory studies have been carried out on acid leaching as a possible route for the extraction of potassium from glauconitic sandstone. Leaching efficiencies with sulphuric, hydrochloric and nitric acids were investigated. The effects on potassium dissolution of temperature, concentration and type of acid, stirring speed and leaching time were also studied. The results show that it is possible to recover 87.5, 93 and 85% potassium with 5 M H2SO4, HCl and HNO3, respectively. During the initial stages of the sulphuric acid leaching process the chemical reaction at the mineral surface is the rate determining step, whereas during the later stages diffusion through the product layer is rate-controlling. Overall, the process follows a mixed-control model that includes both chemical reaction and diffusion. The activation energy for the dissolution of K was found to be in the range 25.79-106 kJ/mol.

Jan 12, 1992

By I. R. Stevenson, J. G. Dunn, T. N. Smith, L. C. Mackey

An experimental flash reactor has been developed to simulate the operation of an industrial flash-smelter reaction shaft. Four concentrate materials of differing mineralogical compositions were characterised and then oxidised in the reaction shaft. The products were examined by chemical analysis to determine the extent of oxidation and by electron-probe microanalysis to determine the fate of individual particles. This programme of work enabled the influence of mineralogical composition and particle size on the extent of oxidation to be assessed

Jul 1, 1991

By Evans E. C.

Discussion of the paper presented at the Manchester Geological and Mining Society' general meeting held in Manchester, March 14th , 1916, with Leonard R. Fletcher, President, in the Chair included contributions by Fletcher L.R., Paton J.D., Orchard A.J.A., Ross A., Gerrard J. and Stephenson H., with the author's responses

Dec 1, 1916

By R. R. Tatiya

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 E. H. W. Hornbrook, P. W. B. Friske

Paper presented at the 28th International Geological Congress, Washington DC, July 1989 (International geochemical mapping sessions). The objective of the programme is to establish and maintain a nationally consistent geochemical drainage database. Towards this end systematic surveys have been conducted since 1973. To date more than 200 surveys have been completed to the required standards, representing 180 000 sites and covering about 2 100 000 km2 throughout Canada

Jun 13, 1905

By Jones R. G.

Dr Pat Foster, Senior Lecturer in Mining Engineering at the UK's Camborne School of Mines, talks to Rhiannon Garth Jones about mining safety around the world, education and the future of the industry

Feb 1, 2015

By D. J. Esdale, D. F. Pridmore, F. W. Lindman, J. H. Coggon

Almost all the presently viable nickel reserves in the Yilgarn Block contain nickel in a sulphide phase. Both volcanic peridotite- associated (VPA) deposits and intrusive dunite-associated (IDA) deposits are characterized by massive, matrix and disseminated sulphides (typically, pyrrhotite, pentlandite, pyrite, chalcopyrite, magnetite and other spinels), though in the IDA deposits the volume of disseminated sulphides is far greater than that in the VPA deposits. Potentially all geophysical techniques have application in the direct detection of these deposits'gravity for the detection of the dense massive and matrix ore; magnetics for the detection of magnetite and pyrrhotite in the ores; electromagnetics for the detection of the massive and matrix ore; and induced polarization for the detection of disseminated and to some extent matrix and massive ore. In practice the application of geophysical techniques is limited to a varying extent by (1) the relatively small size of an economic accumulation of sulphides, particularly the VPA deposits, (2) the extreme depth of weathering and lack of outcrop on the Yilgarn Block and (3) the abundance of geological noise or anomalous responses caused by sources other than economic mineralization.

Jan 1, 1984

By F. Reich, S. L. Chryssoulis, K. G. Stowe

The surface chemistry of particulates from mineral processing streams can be determined by laser-probe microanalysis. The small area of analysis (2-30 micrometres) enables the surfaces of individual grains to be characterised. Conclusions are based on data acquired from a statistically significant number of grains of a given type. Maps showing the distribution of elements on the surface of mineral particulates can be obtained by time-of-flight secondary ion mass spectrometry. The importance of such analyses in understanding the response of minerals to beneficiation practices is discussed with reference to three examples. The first relates to the loss of selectivity in the differential flotation of a base-metal ore, the second to the different flotabilities of coarse- and fine-grained pentlandite from a Cu-Ni ore and the third concerns the preg-robbing effects of organic matter in a carbonaceous gold ore.

Jan 4, 1992

By A Misra

In pursuit of solving the development rate problem the coal industry has investigated various development systems. While all the systems may improve the development rate they may not necessarily he cost effective. This paper carries out an economic analysis by developing cost models for present and future development systems for retreating longwall faces with particular reference to Australian longwalls. A critical cost analysis of various development systems is presented by taking into consideration all the costs associated with development systems. The costs have been divided into equipment, face and panel services, belt and structure, wages, roof and rib support, ventilation, consumables, power and maintenance. The annualised cost of various equipment has been obtained on the basis of depreciation rates prescribed by the Australian Taxation Office.

Jan 11, 1996

By Winmill T. F.

(Paper presented at the Institution of Mining Engineers' general meeting held in London on 8th June 1916.) The conclusions reached in this paper may be summarized briefly as follows: (1) The method of estimating moisture in coal by determining the loss in weight of a sample heated to 105°-110° Cent, in an air-bath for an hour is untrustworthy, the results so obtained being too low. (2) Dried coal has a very considerable power of absorbing moisture, and a sample, after being dried, must be protected instantly if it is to remain free from moisture. (3) A fairly accurate estimation may be made by heating the coal in a current of dry air at 105° to 110° Cent., and collecting the moisture evolved. (4) In cases in which it is proposed to use the dried coal for any further experiments, the drying must be done in the absence of oxygen, and this can be done simply and quickly by the vacuum method now described

Dec 1, 1916

By R. N. Pryor, S. H. Shaw, D. L. Dowie, S. H. U. Bowie, M. J. Cahalan, S. F. Gandar

It is concluded that land-based mineral resources will be adequate for most minerals in the immediate future, but in the long term more minerals will come from offshore locations. Because the oceans are international and can transport pollution, international control of offshore workings will be necessary. In the UK and similarly highly developed areas, the working of low-value bulk minerals will create increasing problems in urban development and countryside preservation. Much more information should be published on standards to be adopted and their costs, if emotional social pressures founded on ignorance are to be avoided. The Town and Country Planning Acts have greatly improved the environmental quality in Britain in relation to mineral working. In the long term conservation of some minerals in short supply may be necessary on a national or international basis. Much research is required for the determination of adequate criteria and standards for the preservation of environmental quality in the mineral industry. New local, national and international legislation will be required and the adoption of voluntary standards by trade associations should be encouraged wherever appropriate

Dec 1, 1971

By M. A. Bussell, G. S. Camm

The study included lode zones at Wheal Pendarves, South Crofty and Rosevale tin mines. Fluid inclusion-containing microfractures are a common feature of the granites and typically show a preferred orientation over quite a large area. The close proximity of a dominant vein or fault controls their density and orientation. They are important pathways for fluids and provide a marker for palaeo-fluid flow. Overprinting provides a reliable representation of the evolution of the hydrothermal fluids in a vein system from early magmatic fluids to late-stage meteoric and basinal brine input. Measurement of microfracture orientation allows estimation of the regional stress regime during a specific hydrothermal event. Since micro- and macro-structures can generally be reliably correlated, these studies assist in modelling the detailed development of complex vein systems. Microfracture density is a good measure of palaeo-permeability, with implications for control of wallrock alteration. The determination of the location and density of microfractures can assist the mine geologist in identifying the location of potentially economic vein structures where macroscopic markers are absent

Aug 1, 1996

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 C. Chope

The Minister for Roads and Traffic's opening speech highlights some of the topics to be covered in the conference with particular reference to the Channel Tunnel, the recent breakthrough of whose service tunnel marked a historic moment three and a half years after passing of the Channel Tunnel Act and which was the first example in recent years of a major transport project entirely privately funded. The Minister also mentioned the building of UK road tunnels, research and development, and the role of UK consultants in the single European market

Jun 13, 1905

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 C. C. Harris

The use of Alyavdin's equation Y(x,t) = 1-e(-bt) for describing the effect of grinding time on size distribution is discussed. The equation transforms into linear form by expressing it as log-log reciprocal (1 - Y) versus log t. For plotting, specially divided grids are available; Rosin-Rammler or Weibull charts may be used. The data of Herbst and Fuerstenau are especially useful for illustrating the Alyavdin-Weibull chart in two applications: (1) presenting data (which are relatively unaffected by experimental scatter) and comparing them with theoretical predictions, and (2) as a test for the zero-order kinetics production hypothesis. The chart based on the Alyavdin-Weibull equation is suggested as a useful aid in the analysis of kinetic data (/ versus f), though not as a procedure in its own right. Proposed applications are (1) displaying data with excellent clarity, since it avoids the kind of congestion inherent in some other plotting methods, and (2) as a test for assumed kinetic relationships. Sometimes, equation 1 describes the data quite closely, and in these cases the parameter values appear to be related to certain operating conditions.

Dec 1, 1971

By I. Garba

The Bin Yauri deposit in the Zuru schist belt of northwestern Nigeria is a vein-type quartz-sulphide-carbonate gold mineralisation hosted by a brittle fault zone. The occurrence of the mineralisation in a contact zone of a Pan-African granitoid was believed to be sufficient evidence of deposition from magmatic fluids. However, studies may now indicate a metamorphic source for the mineralising fluids. A study of rare earth element geochemsitry was used to investigate the nature of the fluid-rock processes involved and identify the sources of the auriferous mineralising fluids.

Jan 12, 1992

By R. G. Jones

Chris Hinde talks us through his career from BSc in Mining Engineering to roles with Golder Associates, Schroder Securities, Mining Journal and SNL. He discusses the issues facing the mining industry.

May 1, 2015