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

Jan 1, 1947

By A. Sutherland Strachan

Before regulations governing the work on the mines, it was not uncommon in the Rand for a miner to die within a period of 2-3 years as the result of exposure to dust. This paper considers mine and tunnel conditions promoting silicosis and measures to avoid dust exposure in the Rand, South Africa.The relationship between blasting and lung lesions is explored. Evidence is presented that improved working conditions and lowered dust levels reduce the incidence of silicosis.

Jan 1, 1947

By H. L. Shergold, O. Mellgren

The conditions of amine concentration and pH necessary for the concentration of fine haematite particles at the iso-octane-water interface have been determined. Results obtained from the related studies on the effect of pH and dodecylamine concentration on the adsorption density, electrokinetic potential, contact angle and concentration of various amine species in the system are included. A good correlation was obtained between these different variables. Maximum concentration of haematite at the oil-water interface was obtained when the haematite zeta-potential was small or equal to zero

Dec 1, 1971

By Gibson J.

Written discussion contributions to the paper presented 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, comprise comments by Kilpatrick W.M., Routledge W.H., Watson J. and Smith W., along with the author's reply. Also briefly noted are the demonstration of two pieces of equipment, an incline chock and a cage arrestor

Dec 1, 1916

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 G Fakes

This paper describes the history of civil engineering tunnelling and developments in soft ground techniques during the 19th and 20th centuries, culminating in the design and use of high speed tunnelling machines for all types of ground conditions. Some of the problems encountered are outlined, and descriptions are given of some contemporary developments in rock tunnelling techniques, with comparisons of methods used in the mining industry.

Jan 5, 1996

By Williams J. A.

"Changes proposed in 1969 to modernize legislation governing the exploitation of mineral deposits in the United Kingdom serve as the basis for a discussion of what is considered to be a desirable framework for future legislative proposals.Proposals with regard to prospecting and exploration, evaluation, and acquisition and exploitation are considered, as are suggestions relating, inter alia, to aerial surveys and land restoration.It is concluded that without legislation along the lines proposed there can be no significant revival of metal mining in Britain."

Dec 30, 1971

By Ruddle R. W.

Solid mattes are generally held to be either (a) eutectiferous mixtures of the component sulphides Cu2S and FeS or (b) mixtures of complex sulphides. This chapter shows that liquid mattes consist essentially of a homogeneous phase in which iron, copper and sulphur are present. The amount of sulphur is generally less than that required to account for all the metals as stoichiometric sulphides; mattes cannot therefore be regarded as mixtures of FeS and Cu2S. Some iron oxide may be dissolved in the sulphide phase and magnetite is often present as a second phase. If the sulphur content of the matte is reduced the composition enters the miscibility gap in the ternary system and either an iron- or copper-rich solution (depending upon the composition of the matte) separates as a new phase. On solidification any one of four phases (iron, copper, Cu2S and FeS solid solutions) may crystallize as primaries. The remainder of the matte solidifies as a ternary eutectic. It is possible that iron oxides enter into this eutectic. Knowledge of the ternary Cu-Fe-S system is far from complete and nothing is known of the quaternary system Cu-Fe-S-O

Jan 1, 1953

By M. J. Russell, W. E. Stephens, D. B. Mohamad, A. B. MacKenzie

Redox front processes in rocks are important in the context of both radioactive waste disposal and the development of orebodies. Results are presented from a study of the distribution of uranium and thorium and the natural decay series equilibrium about redox fronts in a granite at the Criffel pluton and Craignair quarry, Dalbeattie in southwest Scotland. The results are considered in the context of large scale uranium aqueous transport in the region and compared with those from a previous study of highly developed redox fronts at Pocos de Caldas, Brazil. Results show that the Criffel pluton has experienced a recent and rapid removal of uranium from the uppermost section of the granite whereas thorium has remained relatively immobile. The radium and uranium distributions indicate that diffusion processes probably control the distribution of radionuclides about the front. These processes are similar to those observed at Pocos de Caldas. The trends of concentration and activity ratio about the Dalbeattie redox front are less pronounced than those at Pocos de Caldas owing to the shorter time available for the process and the lower intensity of weathering at Dalbeattie.

Jan 12, 1992

By P wade

This is the first Presidential Address given to the Nottinghamshire Branch of The Institution following the merger of the Nottinghamshire and North Derbyshire Branch of The Institution of Mining Engineers (IMinE) and the Midland Branch of The Institution of Mining Electrical and Mining Mechanical Engineers (IMEMME). I intend to review the formation of the individual institutions as well as what has been achieved by mining related institutions over the years and finally I intend to look to our future.

Jan 11, 1996

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 S. Vardy

The paper notes that the extraction of 22% of the remaining workable reserves in the north western area involves a risk of spontaneous combustion higher than is normal in Britain. Mining systems have been tailor made in order to minimize the risk of spontaneous heatings, and these systems are described. Well-proved methods of combating spontaneous combustion are referred to, as well as the limitations which now apply to them as the result of the introduction of modern mining techniques. A substantial part of the paper is devoted to the circumstances in which spontaneous combustion occurs underground in the north western area. Several actual incidents which have occurred in the last few years, along with the practical application of the lessons learned, are described. Of particular note are: a) the procedure adopted in the north western area to equalize pressure differences across stoppings using pressure chambers, and b) a retreat mining system, primarily designed to deal with high methane emission and steep gradients, which also affords some protection against spontaneous combustion.

May 23, 1905

By Evans E. C.

At first sight, the extinction of a mine fire by the action of some such gas as carbon dioxide would appear to be quite a simple and practicable operation. From a consideration of the theoretical aspects only of the question, it becomes evident that the matter is not so simple as it appears to be at first sight. The fire at the Senghenydd Colliery occurred as the result of the disastrous explosion of October 14th, 1913. This explosion was confined to the west side of the colliery; and as a result the timbers in the main intake on this side were set on fire; but these were soon buried beneath falls, and the tire continued under them. Attempts were made to extinguish it with water, with the aid of chemical extinguishers, and by digging it out; hut these had to he abandoned, and ultimately the fire-zone was sealed off by “ bashings” (stoppings). By December, progress in the decrease of combustion was so slow that it was decided to try the effect of inert gas. The installation, control and operation of the carbon dioxide plant and associated water-gauge are described in detail and conclusions drawn for the extinguishing of mine fires by CO2

Dec 1, 1916

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 D. R. Hudson, M. J. Donaldson

"Study of gravity concentrates from the gold-recovery circuit of the Kambalda nickel mill has enabled an assessment to be made of the nature, relative abundance and compositional variability of platinum group element (PGE) minerals and other associated heavy minerals that are present in the Kambalda nickel deposits. The major platinum minerals are sperrylite, PtAs2, and nioncheite, (Pt. Pd, Ni)(Te, Bi)2, and the major palladium minerals are sudburvite, (Pd, Pt, Ni)(Sb, Te, Bi), stibiopalladinite, Pd6Sb2, and palladoarsenide, Pd2 (As, Sb), together with a palladium antimonide and a palladium arsenide that have not been fully characterized. Palladian melonites, which contain up to 10 wt% Pd, and palladian nickeline are also important PGE hosts. Sperrylite and sudburyite are by far the most abundant discrete minerals in the gravity concentrates.Gold occurs as argentian, cuprian and nickeloan—cuprian gold, and as the tellurides calaverite, petzite and auriferous hessite. Silver is present in petzite, hessite and volynskite. Other rare phases contained in the gravity concentrates include native bismuth, altaite, frohbergite, breithauptite, gersdorffite, parkerite, scheelite, tantalite, cassiterite, rutile, bunsenite, gahnite, barite and uvarovite.Descriptions of in-situ occurrences of PGE minerals at Kambalda are rare. Michenerite, PdBiTe, and testibiopalladite, PdSbTe, have been described from a telluride-rich quartz-carbonate vein that intersects massive sulphide ore in Lunnon Shoot. Moncheite has been observed in chalcopyrite-rich stringers, and sudburyite occurs as inclusions in nickeline in a quartz- carbonate veinlet. No discrete PGE minerals have been found within the massive and matrix ore zones in the Kambalda ore- shoots, and the geochemical distribution of PGE suggests that the formation of discrete PGE phases may be related to post- magmatic processes—in particular, metamorphic segregation of sulphides, and the interaction of the ore sulphides, containing PGE in solid solution, with younger hydrothermal fluids. This has led to local redistribution of the PGE, with concentration in footwall stringers and veins, and in reaction zones."

Jan 1, 1984

By Y. L. Ding, N. A. Warner

Cylindrical pellets made from graphite and chromite mixtures were reduced in high-carbon ferrochromium melts at 1 600-1 695 degrees C, under an atmosphere of almost pure CO. The reduction rate, as measured by gas evolution, increased with increasing melt temperature and graphite addition and with decreasing pellet diameter or height, although reductant particle size had a very limited effect on kinetics. At a pellet size, heat and mass transfer were significant in controlling the early stages of reduction of large pellets while at chromite grain size, gas diffusion was probably a rate-controlling step. The time required for dissolution of unfluxed pellets into the melts was significantly longer than that for reduction. This indicates that pellet dissolution may be the limiting factor in determining the operating parameters for a proposed new process to produce high-carbon ferrochromium using melt circulation

Jun 19, 1905

By Fearnside W. G.

Further discussion at the Midland Institute of Mining, Civil, and Mechanical Engineers' general meeting held in Leeds, March 21st, 1916, with T. Beach, vice-president, in the chair, of a paper published in Trans. Inst. Min. Engrs., 1915, vol. L, p. 573 and discussion vol. L., p. 109 and 608, comprised a brief written contribution by Faulds A.

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 A. J. Naldrett

"Synorogenic mafic intrusions are a common feature of the northern Appalachians. Two sulphide-bearing intrusions in central Maine that have been investigated revealed a number of important features that illustrate sulphide-silicate interaction that relates to magmatic sulphides. The Moxie Pluton is a large mafic intrusion emplaced during the Devonian Acadian orogeny. The Katahdin gabbro is a small mafic body that is probably genetically and temporally related to the Moxie Pluton. Both intrusions were formed bv the intrusion of variably fractionated magmas into irregular chambers and feeder zones. The southern half of the Moxie Pluton contains three small sulphide accumulations, whereas the Katahdin gabbro hosts a large, predominantly massive, sulphide body. Textural evidence clearly documents the magmatic origin of these sulphides.The three Moxie Pluton sulphide bodies are located at or very close to the intersection between the intrusion and the sulphidebearing Hildreths Formation. Sulphur assimilation, suggested by this relationship, is supported by the isotopically light (634S = —8 to —25) and the selenium-poor (S/Se - 25 000-48 000) character of the Moxie sulphides and correlation with the Hildreths Formation sulphides (S34S = —25, S/Se = 25 000-48 000). Isotopically light sulphur (534S = —20 to —21) and high S/Se ratios indicate that the majority of sulphur in the Katahdin sulphide body was also derived from an unexposed country rock source. The volume of sulphide in this example illustrates the potential efficiency of the sulphur assimilation process—so efficient in this case that marked dilution of the economic chalcophile elements resulted from the addition of so much external sulphur.The three Moxie Pluton sulphide occurrences are all impoverished in Ni and Cu (1.87-0.44% Ni; 0.72—0.32% Cu in massive sulphide), but contain normal Co contents (0.22-0.13%) relative to typical magmatic sulphides. The Katahdin sulphides show a greater Ni and Cu impoverishment (0.2% Ni; 0.1% Cu in massive sulphide) with similar Co (0.17%). The Ni content of the Moxie Pluton olivines document the fractional removal of sulphides during crystallization of the host magma, which resulted in the progressive depletion of the chalcophile metals in this magma. Modelling that involved the fractional crystallization of the magma coupled with the fractional removal of a specified proportion of sulphide has successfully duplicated the Moxie Pluton sulphide compositions. A similar magmatic model has been postulated for the Katahdin sulphides with a greater degree of sulphide fractionation. This latter model is again supported by extremely low Ni/forsterite ratios in olivines, though the compositional range is insufficient to document fractionation. These magmatic models are not unique, but they provide a relatively constrained and consistent explanation for the sulphide compositions.The Ni contents of olivines are the most important indicator of sulphide-silicate interaction in mafic magmas and have exploration potential. They provide a means of assessing the timing and extent of sulphur saturation in an intrusion and are a guide to the Ni content of a sulphide accumulation in equilibrium with olivine. In the Maine examples they provide strong evidence of the magmatic origin of the sulphide accumulations and justification for magmatic modelling."

Jan 1, 1984

Discussion at the North of England Institute of Mining and Mechanical Engineers' general meeting held in Newcastle-upon-Tyne, 8th April 1916, on the paper published in Trans. I.Min.E., vol.LI, 1916, p.72-90, included written contributions on size and gauge standardisation by Lupton A., Peck W.R., Dean S., Mayer R.W. and Ashworth J., with the author's written response, and by Bulman H.F. and Brown M.

Dec 1, 1916