Search Documents

By K. Fagerlund, L. Rosenback, T. Mäkinen, Y. Anjala

This paper deals with the nickel smelter and refinery concepts Outokumpu has applied at Harjavalta and several other plants. Also other process routes and modifications developed and tested by Outokumpu during the recent years are highlighted. Outokumpu started nickel production in Harjavalta in 1959. Until 1995 the Flash Smelting - Peirce-Smith (PS) converting route was applied. High grade nickel matte from the converting step was further refined by means of leaching and electrowinning to produce cathode nickel. In 1995 the nickel production capacity was increased from 17 000 t/a to 52 000 t/a based on the Direct Outokumpu Nickel Smelting Process (DON). In the DON process PS converting is eliminated and high grade nickel matte with low Fe-content is directly produced in the flash smelting furnace (FSF). Metal values from the smelting slag are recovered in the electric furnace (EF) as iron containing Ni-matte. The DON process can be operated with either two matte concept, where high grade FSF matte and EF matte are produced, or a single matte concept, where EF matte is recycled to the smelting furnace and thus only one type of high grade matte is obtained. The additional refinery capacity at Harjavalta is based on hydrogen reduction producing.

Jan 1, 2005

By Robert Drummond

Away back in the eighties of the last century, when Sir Charles, then Doctor, Tupper, was not only a prominent but a dominant figure in the political life of Nova Scotia, his opponents brought the railing accusation against him that he was the foremost of egotists because of his frequent use of the personal pronoun. I heard Tupper speak and had no sympathy with the railers, because I could not well see how the pronoun could be dispensed with without laying himself open to a charge of affectation. I shall make reference in what follows to incidents in which I have taken part, and shall be at no pains to dispense with the pronoun, even though thereby I lay my-self open to the charge of being a pupil of the deceased states-man. EVENTS LEADING UP TO THE ORGANIZATION OF THE PROVINCIAL WORKMEN'S ASSOCIATION The Springhill Mining Company began development work at Springhill in the early seventies of last century. So vigorously was the work prosecuted that in 18 7 4 two slopes, the east and the west, were in active operation, with a considerable. output, the east slope on occasional days producing 800 tons. The President of the Company, the late Senator McFarlane, was a Nova Scotian, the other directors were mainly merchants from St. John, N.B. From the first the enterprise was an .astonishing success, due in the greatest part to its geographical position, and in large part to the untiring vigilance of the directors, a majority of whom visited the collieries at short intervals, thereby keeping the manager, much of the time, on tenter hooks.

Jan 1, 1924

By K. R. Brown, P. L. Krawchuk

In-situ recovery (ISR) is under increased investigation as a viable methodology for the extraction of minerals in ore bodies that may be uneconomic to mine by traditional methods or for resources situated in locations where underground and surface mining operations are not feasible. Although the concept of ISR is relatively new with respect to hard rock applications, it is not a new technology; it has been used successfully in potash and uranium mining and also in heavy oil extraction for years where it has been proven to be both technically and commercially viable. ISR allows for the extraction of metals and minerals without the need to mine large amounts of ore that need to be processed at surface. The ore stays in-situ and only the valuable metals and minerals are produced to surface in a process that produces very little to no waste rock or tailings. This paper aims to discuss the geological conditions that make ISR amenable to an ore body as well as the application of maturing technologies such as advanced directional drilling and the creation of artificial permeability that will help to access deep ore bodies and enhance or create favorable recovery conditions for ISR in the ore body. INTRODUCTION In-situ recovery (ISR), also referred to as in-situ leaching, is a potentially disruptive technology for the mining industry. ISR is under increased investigation as a viable methodology for the extraction of valuable minerals that may be uneconomic to mine by traditional methods or for deposits situated in locations where underground and surface mining operations are not feasible. Although the concept of ISR is relatively new with respect to hard rock applications, it is not a new technology; it has been used successfully in potash mining, uranium mining and also in heavy oil extraction for years where it has been proven to be both technically and commercially viable. Recently there has been increased interest in deploying ISR in hard rock applications due to a number of factors: the drive for environmental stewardship is stronger than ever, technological advances in drilling, blasting, and leaching are strengthening ISR economics, and a large inventory of ore bodies exists that are not feasible to mine or extract using conventional open pit or underground mining techniques. ISR allows for the extraction of valuable metals and minerals without the need to mine large amounts of ore that need to be processed at surface. The ore stays in-situ and only the valuable metals and minerals are produced to surface in solution via a recovery process that produces very little to no waste rock or tailings. Where the right conditions exist, the ISR process has a much smaller environmental footprint (Hiam-Galvez, 2018) and potentially much lower capital and operating costs than using conventional mining techniques.

Jan 1, 2019

By Peter A. Adcock, Rob Fraser

Interest in monitoring nucleation overpotential in electrometallurgical processes dates back some 40 years or more. Conversely, remarkable progress has been made in recent years on describing in detail the processes involved in the formation of thin films by electrodeposition. The newer body of work underscores a need for greater clarity in speaking about the role of nucleation and in the acquisition and interpretation of nucleation overpotential measurements – the aim of this paper. In electrometallurgy, it is generally desirable to form deposits that remain smooth, compact, and relatively fine-grained while the deposit grows to a thickness on the order of 5-10 mm, about 100 times thicker than technological thin films. Hence, we distinguish two kinds of nucleation that can result in formation of new grains:- (1) initial nucleation (onto the substrate surface) of islands that coalesce into growing deposit, and (2) ongoing nucleation of new grains on the deposit surface long after the substrate has been covered and ceases to have a direct influence. Nucleation overpotential of the first type should be measured on an electrode surface truly representative of a real industrial substrate. The second type requires judicious choice of electrode material – an “ideal foreign substrate”. In general neither the industrial substrate nor native metal to be deposited is suitable for measurement of the second type of nucleation overpotential, because of interference by other processes. For the future, clear terminology is needed to distinguish these two types of nucleation potential. The second is the one for which the type of plot dubbed by Moats and Derrick as an “Adcock plot” and by us as a “Kerby-Adcock plot” was first conceived and correlated with relatively thick zinc electrodeposits. The data of Moats and Derrick showing trends for copper electrodeposition on stainless steel and on copper electrodes are interpreted within this framework.

Jan 1, 2016

By R. Heikkilä

Today road construction sites utilize more and more information modeling in design phases as well as model based 3-D machine control systems in site operations. For main contractor, the management and control of all the site operations is a demanding task including also many challenges created by continuously developing new technology. In the paper, the main requirements for successful dynamic site management are introduced. The dynamic management means real-time possibilities for information acquiring, transfer and further utilization of the information in the management. An integration model to expand the current way of management and the utilization of present 3-D machine control systems is introduced. Different practical test results using two new different dynamic management systems are presented and evaluated. The first experiments and the results have been provided using the prototype system developed in a research project called DigiINFRA by the University of Oulu and Technical Research Center of Finland. Also, there have been tested a new commercial management system developed recently in Finland. In the conclusion, an expectation for the next generation for more dynamic road construction management methods is concluded.

Aug 1, 2013

By P. B. Demarsh

"Location: - Mine village of Perron, 11 miles east of Val d’Or in northwestern Quebec.Life; - Started production 1932, ceased 1951.Ore: - Flat lying quartz tourmaline veins within granodiorite. Gold values related to coarse segregations of pyrite. Specific gravity 2. 80.Capacity: - 30 tons 1932-35; 125 tons 1935-37; 350 tons 1937-51.Assay: - Heads 0.21 to 0.34 oz. per ton. Grade obtained by mining 600 tons daily, sorting belt reject 250 tons, balance to milling; tailings loss 0.003 to 0.005 oz. per ton; extraction 9 8. 5%.Grind: - 70% minus 200 mesh. Detention time 26 hours.Treatment: - Cyanidation process.Reagents: - Per ton, aero cyanide (NaCn) 0.36; unslaked lump lime 1.50; zinc 0. 03; lead acetate 0. 006; steel consumption 2. 50.Water: - Equal mixture of swamp creek water and underground seepage.Cost: - Per ton, sorting and crushing 0.21; grinding 0.31; cyanidation 0.11; filtration 0.05; precipitation 0.02; miscellaneous 0.22; total 0.92.Power: - Hydro-electric, 25 cycle, 12, 000 volts reduced to 550 volts.Labour: - 95% Maritime and European, balance Quebec and Ontario.Tailings: - Absorbed over large swampy area on barren mining claims.Personnel: - 1 7 men including supervision.Flow sheet: - Canadian Mining Manual 1947"

Jan 1, 1966

Once applied, EarthZyme reduces the tendency for a road to exhibit common maintenance issues: wash-boarding, rutting, heaving, potholing and dust.

Aug 1, 2013

By J. A. Russell

IT IS the purpose of this paper to show how the design of the larger slope hoists in use in the mines of the Dominion Steel and Coal Corporation has tended to evolve ta suit the particular conditions of operation. These hoists are all used for hauling coal in trains or trips of pit tubs up the mine slopes, which usually follow the dip of the seam . As the mine is developed to the dip and the slope grows in length, the length of the rope and the size of the hoist required to handle it rends to become extremely cumbersome. It has been found that the best economic conditions of hoisting are obtained when the length of the slope is limited to about seven or eight thousand feet. Beyond this length it is necessary to offset to one side of the line of slope and start a second or auxiliary slope, which will be served by its own hoist installed underground. With this hoisting distance as a basis, we find that we can economically hoist the outputs required, usually about 1,500 tans per eight hours per slope, by hoisting the coal in trips of about twenty boxes. This, on the grades obtaining, will require a rope of about l 1/4in. diameter, running at a speed of 1,200 ta 1,800 feet per minute, and requiring from 1,200 to 1,800 h.p. at the hoist shaft. The tendency is for the rope speeds of the surface hoists to be a little higher than the underground hoists which relay to them, so that the surface hoist has a small margin of time in hand. The oldest surface hoists were steam-driven, but, with few exceptions, these have given place to electric hoists. With the exception of one hoist, which was altered in design, the steam hoists have not had the opportunity of evolving in the same way as the electric hoists, and will not be mentioned any further.

Jan 1, 1944

By James Dickson

Brief History of Discovery and Early Development In the first half of the nineteenth century, the only authority on the Pacific coast between the Columbia river and Alaska was exercised by the Hudson's Bay Company, who had established a series of forts and trading stations on the coast from the Columbia north to Millbank sound. The Hudson's Bay Company were chiefly interested in the fur industry, and the large influx of settlers from the eastern United States into the territory now known as the States of Oregon and Washington, about 1840, not only interfered with the fur business but involved the question whether the territory should be under the British or the American flag. Anticipating the possibility, later realized, of losing control of this area, the Company, in 1845, established their main fort and trading centre on the southern end of Vancouver island under the name of Fort Camosun; shortly afterwards changing the name to Fort Victoria. Realizing that their former policy of discouraging all attempts to develop any other business than the fur industry had lost them several hundred thousand square miles, the Hudson's Bay Company now set about encouraging settlers in the vicinity of Fort Victoria by disposing of lands to suitable parties and also to those in the employ of the Company. The usual pioneering stage was passed through with the starting of small sawmills, grain mills, etc., and the incidental work accompanying such efforts. Any coal required for blacksmithing or other purposes was brought from England around Cape Horn by the few ships that visited the Pacific Coast. About 1849, an Indian who was having his gun repaired by a blacksmith in Fort Victoria asked about the "black stones" used in the fire and, on being told that the "black stones" had to be brought a great distance, he informed the blacksmith that there was plenty of the same stone where his people lived. This information was immediately given to an official of the Hudson's Bay Company who talked with the Indian and told him that if he would bring some of the "black stones" he would get his gun repaired free and a present of a bottle of rum. Nothing more was heard of this coal until April of the following year, when the Indian came into Fort Victoria with his canoe loaded with coal, which was tested and found to be of good quality. It is reported that the Indian got his bottle of rum.

Jan 1, 1935

By Ramsey Hart

MiningWatch Canada is the only national independent civil society organization with an exclusive focus on mining in Canada and Canadian mining companies operations internationally. In 2005, MiningWatch Canada collaborated with other NGOs to develop the Framework for Responsible Mining: A Guide to Evolving Standards. The project was the result of a perceived need by NGOs and retailers, particularly from the jewellery sector, for a framework that would set out environmental, social, and governance standards for the minerals sector ?providing recommendations for retailers and others seeking to source or invest responsibly, as well as regulate and encourage responsible mining practices?. This paper is a reflection on the Framework that examines key areas of concern and notes where the industry norms and expectations of civil society have evolved. The paper focuses on developments in social issues related to the UN Guiding Principles on Business and Human Rights, new initiatives associated with financial transparency, the UN Declaration on the Rights of Indigenous Peoples. The environmental components of the Framework that are revisited are waste management, biodiversity, energy and climate change, environmental assessment, mine closure, mercury and seabed mining.

Aug 1, 2013

By Nessetech Consulting, L. A. Cisternas, E. D. Galvez, S. H. Kuan, L. H. Saw

"In Malaysia, there were two rare earths processing plants namely Asian Rare Earth (ARE) and the Malaysian Rare Earth Corporation Plant (MAREC) in Perak, which were operated until 1992 and were subsequently closed due to problems pertaining to disposal of large amount of radioactive waste. Recently, Lynas Advanced Materials Plant (LAMP) has become one of the largest rare earths processing plant in the world producing rare earth elements (REE) in Gebeng, Pahang. The primary raw material is lanthanide concentrate (LC) which is imported from Mount Weld mine in Australia and shipped to Malaysia. LC is produced from lanthanide ore after mining and mineral processing. The ore has a lower impact than Bayan Obo, Mountain Pass and adsorbed clay deposits, given the small footprint of the mine itself and the remoteness of the location. The type of ore being mined (rare earth phosphates: carbonatite, monazite) may have higher thorium content than bastnasite ore from the Chinese or American mines but still far below radiation concerns. This paper was written to review the processing flowsheet at the Lynas Advanced Materials Plant (LAMP), the environmental impact associated with the processing of the said ores and the sustainability of the operation.INTRODUCTIONRare earth minerals are one of a set of 17 minerals or chemical elements which consists of yttrium and scandium, as well as the 15 lanthanide elements (lanthanum, cerium, praseodymium, neodymium, promethium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). Despite their importance, rare earth minerals rarely exist in economically viable concentrations and they are usually difficult to extract. Rare-earth minerals create strong magnets when added to magnetic elements such as iron, and are useful for the production of electronics systems as well as electric cars. They are also used extensively in automotive catalytic converters, fluid cracking catalysts in petroleum refining, wind turbines, phosphors in colour televisions and flat panel screens, displays for mobile phones and laptops, rechargeable batteries, and various medical devices. The elements are typically split into two subgroups: the cerium sub-group of ‘‘Light’’ rare earth elements (LREEs) which includes La to Eu and the yttrium sub-group of ‘‘Heavy’’ rare earth elements (HREEs) which include the remaining lanthanide elements, Gd to Lu, including yttrium (Gupta and Krishnamurthy, 1992; Jordens et al., 2013; Trifonov, 1963). Scandium, however, when it is classified as a rare earth element, is not included in either the LREE or HREE classifications (Gupta and Krishnamurthy, 1992; Jordens et al, 2013). Half of the world’s 110 million tons of reserves exist in China while other sizable deposits are found in Russia, United States, Brazil, India, Australia, Canada, and Greenland. The countries known to be actively mining REE are China, Russia, India, Brazil and Malaysia (Hao et al., 2015). Among these countries, China has the largest REE production, accounting for more than 93% of global supply (Yap, 2015). The critical metal report (Moss et al. 2011) listed 14 economically vital raw materials that are prone to supply disruption and concluded that supply disruption would threaten the goal for cleaner transport and sustainable energy since rare earth metals are used in products using green technology, such as hybrid/electric vehicles, carbon capture systems, wind power generation, low-energy lighting, and energy efficient flat-screen displays."

Jan 1, 2016

By K. H. Concannon, K. I. Hindle

"The use of simulation modeling in the primary metals industry (including mining, smelting, and metals processing) is expanding as significant cost-benefits can be realized by companies employing capital intensive processes. The economic scale and complexity of operations found in this industry is well-suited to applications using this ""what-if' computer modeling technique, ranging from proof-of-concept projects to testing facility design or configuration, and determining resource requirements. More recently this technique is being used to support on-going planning and scheduling for operations using the simulation as the engine to derive the best schedule. With increased computer processing capability, deterministic models are now being developed to capture the workings of a production system or conversion process, allowing real-time monitoring and scheduling of these operations. This paper presents a sample of some recent discrete-event simulation modeling applications that demonstrate the capability and benefits of this technique in the primary metals industry. These include the use of simulation to support the long-range planning of underground mining operations; the modeling of a metals supply chain network that employs a multi-modal distribution system; the scheduling of a metals coil finishing process using a deterministic simulation model; and a more detailed description of the use of simulation to model furnace and converter aisle activities within a smelter operation in Northern Canada."

Jan 1, 2007

By M. F. Goudge

Introduction It is only fitting on this occasion of the fiftieth anniversary of the incorporation of the Institute that we should indulge in a bit of retrospection and review the progress that has been made within this period in the various branches of the mining industry- progress that is so closely associated with the members of this Institute. Such a moment of retrospection will enable us better to appreciate the present status of the industry and to perceive more clearly the trends that should guide us in making sound plans for the future. The past half century has been a period of amazing industrial progress in Canada. In this period, the economy of our country has changed from one based chiefly on agriculture and the export of raw materials, to an economy based largely on a well integrated manufacturing industry. In all' o( these major developments, industrial minerals have played an important part and will play an increasingly, important part in the future. By ?industrial minerals? we mean the various non-metallic minerals (exclusive of fuels) as well as the rocks, sands, and clays used for industrial purposes. They are now used so widely and in such large quantities that modern industry could not function without them, and their continued availability at low cost is vital to the industrial future of Canada. The key position occupied by industrial minerals in modern Canadian industry was well illustrated two years ago when a strike occurred in the only Canadian plant producing soda-ash and calcium chloride at a time when those materials were already in short supply and unavailable from other sources. Within a short time of the shutdown of this plant, in which the two principal raw materials are limestone and salt, the great aluminium reduction plants on the Saguenay river were forced to curtail operations because of the lack of soda-ash, essential to the process of extracting aluminium from its ore. Automobile production, already harassed by a shortage of steel, was further hampered when glass for windshields and windows could not be supplied because the glass industry was slowed down almost to a standstill for want of soda-ash. Soap became almost unobtainable both to the housewife and to industrial users, because soda-ash is required in its manufacture. As a consequence of the soap shortage, the production o synthetic rubber at Sarnia was threatened because soap in large quantities is essential to the polymerization process. Motorists on gravelled highways all over Eastern Canada drove through clouds of dust because calcium chloride, used for dust laying, was not to be had. There were other cases of dislocation of industry related to the shutdown of this particular plant, but the above illustrates the wide ramifications of industrial minerals in modern industry. However, it is extremely doubtful if many Canadian citizens realized that these apparently unrelated happenings were connected in any way with limestone and salt.

Jan 1, 1948

By Henry F. Hebley

THE solid fuel industry, especially that branch represented by bituminous coal, is gradually becoming aware of its ? paramount importance in a world where there is an ever increasing demand for the products of a mechanical age. In practically every process of manufacture, the necessity for energy in some form is being multiplied. Some of that prime energy is derived from water power-hydro-electric schemes, flood control schemes, etc. - but often the electrical energy thus developed is generated at great distances from the load centres, requiring long transmission lines with consequent transformer and transmission losses. A few plants have harnessed the tidal power of the seas and one has harnessed the energy of the wind in a modern manner. All of these schemes are dependent on certain natural geographical, hydrographical, and physical advantages of terrain, as well as an adequate area of consumption of the energy developed. If flood control is the primary object, then power generation is a by-product; and the economics of large capital expenditure on power generating equipment must be considered in that light.

Jan 1, 1945

By R. Bainbridge

THE cinnabar deposits of the Consolidated Mining and Smelting Company's Pinchi Lake property, situated near Fort St. James, B.C., were discovered and reported on by a Dominion Government geological party in 1937. Claims were staked by a group of local prospectors and, later, the Consolidated Mining and Smelting Company of Canada, Limited, took an option on the property. By the fall of 1939, exploration work had indicated ore of commercial quantity and grade, and laboratory tests had shown that standard methods of reduction, namely, roasting of the ore, followed by condensation of the mercury vapour produced, would result in satisfactory recovery. In June, 1940, construction of a 50-ton unit arranged for wood firing was completed and operation commenced. The installation consisted of a 46 in. by 60 ft. rotary kiln (see Figure 1) followed by a 14-in. Sirocco cyclone, a cast-iron condenser unit, and a 1,700 c.f.m. fan, exhausting to a stack. Other equipment included a 9 in. by 18 in. Denver jaw crusher with the necessary bins and feeders. As the need for mercury was urgent, because of war requirements, construction of a duplicate unit was begun almost immediately. This first extension started operation in January, 1941, and the plant was then capable of treating about 150 tons of ore daily.

Jan 1, 1945

By I. M. M. W. R. Jones

"THE OBJECT of these notes is to initiate a discussion among the members of our Institution on the connotation of the term 'ore', and to arrive, if possible, at an acceptable definition of the term in the light of its current use by our leading mining engineers, metallurgists, •and geologists.The majority of •authors of well-known modern text-books on subjects dealing with mineral deposits define 'ore' in words which convey the meaning that it is an aggregate of minerals from which one or more metals can, under favourable conditions, be extracted profitably.Many eminent members of the Institution, and of mining and metallurgical institutions in other countries, consider that the term should not be restricted to metalliferous mineral •deposits but can also be applied correctly to certain non-metallic deposits. They believe that the growth, during the twentieth century, in the industrial importance of non-metallic minerals, and the progress made in the mining and the milling of deposits containing such minerals by methods similar to those used for metalliferous mineral deposits, no longer justify the academic restriction of the term to deposits worked for their metal content only."

Jan 1, 1954

By A. Karzhau, B. Aldamzharov, Y. Tussupbekov

"This case study produced for the metal mine operating in Kazakhstan, which has ventilation controlled manually and working continuously at maximum speed to keep air flowing through each part of the mine 24 hours a day. The mine auxiliary ventilation has been designed with the maximum length of ducting systems with extra air volumes to compensate for potential leakage. The mine provided auxiliary ventilation to all production stopes even to those, which for various operating reasons become temporarily inactive. However, mine safety has to consider risks associated with the deficit of fresh air for mine gases dilution and removal. The mine needs additional investments for re-designing ventilation network and therefore needs to estimate financial risks associated with it. The aim of this study is to conduct risk analysis for ventilation network optimisation processes at the operational metal mine in Kazakhstan. Mine ventilation surveys were undertaken for validation of the computerised ventilation model. The mine ventilation network modelling has been undertaken to be compliant with Kazakhstan mining regulations. Results of the mine ventilation optimisation processes were analysed in terms of financial risks for investments into reconstruction of the ventilation shafts, extension of the ventilation network, variable speed fans and automated regulators. Savings were resulted from improving ventilation system efficiency by reduce airflow in areas without mining activity and redistributing existing ventilation capacity. Based on savings derived from the optimised ventilation network an additional NPV has been received. Stochastic modelling use Monte Carlo simulation producing representation of possible outcomes for the additional NPV considering electricity pricing as a major variability. As result probability distribution for the optimised ventilation network demonstrates the additional NPV in a range of 1.6 - 2.2 million US$ in the corresponding defined value of 90%. Moreover, there is only 5% chance that the additional NPV to be less than 1.5 million US$. Conducted risk analysis for ventilation network optimisation processes gives considerations on volume of investments into the mine ventilation system.INTRODUCTIONCosts for mine ventilation are typically increasing when mines expand to deep levels. Some underground mines in Kazakhstan still use continuously operating fans at its maximum capacity. This is not helping to save energy and costs that are in many cases very significant. This case study produced for the metal mine operating in Kazakhstan, which has ventilation controlled manually and working continuously at maximum speed to keep air flowing through each part of a mine 24 hours a day. The mine auxiliary ventilation has been designed with maximum length of ducting systems and extra air volumes to compensate for potential leakage. The mine provided auxiliary ventilation to all production stopes even to those, which for various operating reasons become temporarily inactive. However, mine safety has to consider risks associated with the deficit of fresh air for mine gases dilution and removal from the mine workings (Sabanov, 2019). The mine needs additional investments for re-designing ventilation networks and therefore need to estimate financial risks associated with it. The aim of this study is to conduct risk analysis for ventilation networks optimisation processes at the operational mine in Kazakhstan. Mine ventilation surveys for validation of the computerised ventilation model have been undertaken"

Jan 1, 2019

By A. J. Paul Laprairie

The process for which it is to be used is too often the only consideration in the design of a vessel. A de-sign allowing for practical manufacture and erection, as well as for proper maintenance, can often give over-all economies. Most platework in-stalled today is of welded construction. Therefore, metallurgical control is important in its manufacture. Also, because many concentrating and re-fining processes tend to be corrosive, the subject of protective coatings as a part of the manufacturing process is extremely important. The plant de-signer should know how to evaluate and specify controls for the metallurgy and for the coatings. Mining operations are becoming more sophisticated in the field of mechanical engineering. More and more emphasis is being given to preventive maintenance. The first step in any maintenance program, however, is good inspection service. This paper will suggest methods for the inspection of platework, and outline methods for repair and replacement.

Jan 1, 1963

By Michael Harley, E. Guy Charleworth

"Bedding-parallel thrust-hosted gold veins are developed in the Sabie-Pilgrim's Rest goldfield, eastern Transvaal, South Africa. The reefs display a complex history characterized by temporally and spatially overlapping events of similar mineralization and deformation. Recognition of the episodic reactivation of these low angle (5° to 10°) thrust faults implicates high fluid pressures (equalling or exceeding lithostatic pressures). Geochemical constraints limit the amount of fluid-rock interaction and the occurrence of transgressive mineralization within the Archaean granitoid basement suggests that the high pressure fluids originated at depth beneath the Transvaal Basin.Similarities exist between gold deposits of Sabie-Pilgrim's Rest and Telfer, Western Australia as well as Passagem de Mariana, Minas Gerais, Brazil. All deposits are sub-parallel to the enclosing bedding which is shallowly inclined. Furthermore, they are also hosted by contractional deformational structures and are clearly epigenetic in origin."

Jan 1, 1994

By S. Makni, S. Koppalkar, A. Bouajila

ABSTRACT This paper briefly reviews the gravity recovery between conventional and centrifugal gravity separators. The advantages of semicontinuous gravity separators will be discussed, as will techniques for upgrading the gravity concentrates. The research efforts in optimizing semicontinuous gravity separators will be recalled. An innovative gravity circuit for eliminating or minimizing the use of complex processing schemes will be reviewed. Ongoing gold gravity research has revealed that gold particle shape transformation is one of the main factors explaining the lower recoveries of the plant units. Efforts to devise possible remedies for improving plant gravity recovery will be discussed.

Jan 1, 2013