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By Dave M. Jakelski, Gerhard W. Heinrich, Peter F. Wells, Daniel F. Suarez, Jamie B. Beauchamp

"A need for increased copper concentrate production and for less nickel contamination in that concentrate at Falconbridge's Strathcona Concentrator during 1993 required the installation of a third flotation column and improvements in the operation of the existing circuit. Innovations in wash water distributor and launder design were fundamental in achieving objectives on a new 3 meter diameter column. Minnovex plug-type spargers were tested on a 2.1 meter diameter column in order to reduce maintenance requirements. The paper details the measures taken to enhance column flotation circuit performance and the results obtained.IntroductionFalconbridge's Strathcona Mill receives 10% of the ore feed from a rich copper zone in the Strathcona mine. This ore typically grades 7% copper and 1 % nickel and, because of its high copper content, it is processed in a separate circuit ('C' circuit) which consists of conventional grinding, rougher flotation with the concentrate being treated with lime to pH 12.3 and cyanide followed by column flotation. The columns are operated with mechanical flotation scavengers and the scavenger concentrate is returned to the column feed. Testwork conducted in 1991 showed that the original flotation column (Column 2) could only produce 5.5 mtph of concentrate with less than 0.5% nickel (Figure 1).Between 1991 and spring of 1993, production was increased at times by open circuiting the scavengers. Metallurgical improvements were obtained by improving the wash water distributor of Column 2 and by wash water sprays in conventional cells (1 ). However, the scavenger concentrate assayed 0. 7 -0.8% nickel and was not acceptable for long term operation. When Copper ore production targets were significantly increased for 1993, it became clear that an additional flotation column was required. The new flowsheet employs mechanical scavenger cells on the column tails as in Column 2 circuit (Figure 2). A -parallel configuration was chosen as pulp solids fraction has been shown to be a critical variable and the second column in series would receive a lower density feed."

Jan 1, 1994

The methods employed for the addition of uranium to steels and cast iron in the Physical Metallurgy Division are outlined. It has been found that the segregation of? uranium is a major problem in aluminum and/or silicon killed steels and that the cooling rate is important in al-lowing the segregate to settle to one area, which can subsequently be discarded. The unsegregated areas were found to be extremely low in total oxygen, acid insoluble aluminum (AizOg) and, in some cases, slightly lower in nitrogen. Uranium recoveries, based on analyses of the unsegregated areas, were quite constant, at about 45 per cent, regardless of the type of uranium master alloy used for the addition. No segregation of carbon, manganese, silicon, sulphur, phosphorous, chromium or copper was observed in these steels. In commercial heats, the recoveries ranged from 7 to? 29 per cent for ladle additions to oxygen converted steel. When the steel was fully deoxidized prior to the uranium addition, recoveries ranged from 49 to 66 per cent, regardless of the steelmaking process.

Jan 1, 1964

By Mehmet Guney

This article is based on a detailed heat investigation conducted at the Rokana Division of Nchanga Consolidated Copper Mines Limited while both authors were employed in Zambia. Mindola Mine is one of the three underground mines comprising the Rokana Division on the Copperbelt of Zambia, producing about 270,000 tons of ore per month at 1.9% Cu and 0.14% Co. The total volume of air being circulated by means of five primary fan installations slightly exceeds 1,000 m3/sec at standard density. Sectional bulk cooling is practised where air cooling coils are installed at primary splits some considerable distance from the stoping operations. Total capacity of the refrigeration complex is 10,500 kw (3,500 R. tons), of which about 7,000 kw is available as effective cooling power after losses, but the heat removed from the coifs is about 3,500 kw with 61% over-all plant performance. An extension program is planned for a further five production levels with the re-deepening of a sub-vertical shaft. Thermal heat will become a major problem at increased depth associated with higher rock temperature, higher thermal conductivity of the rock groups encountered and fissure water flowing into working areas through the strata with increased rock temperature. This paper describes the ventilation and refrigeration practices in Mindola Mine, with special reference to future thermal heat problems. These are discussed with a view to mining at depth.

Jan 1, 1979

By K. Buxmann

Climate change is a subject of growing concern. Based on the International Energy Agency, about 19% of man made greenhouse gas emissions globally are generated by the transport sector. This paper will focus on the environmental aspects of the light-weighting in transport and the resulting savings of fuel and electricity. Aluminium is an option for lightweight applications in transport, with very high benefits not only in the use stage, but also in the stage of vehicle recycling. Life cycle assessment is used to quantify the relative benefits of light-weighting specific components of cars, commercial road vehicles, buses, ships and trains. A vehicle consists of many components, which are produced by different processes and undergo different types of end-of-life operations. This document does not intend to compare a generic aluminium vehicle with a generic "heavy materials" vehicle. It rather tries to use a pragmatic approach based on specific examples of components where aluminium is used and can be used in the design of new vehicles, also taking into account future developments. The case studies in this paper are based on real cases where aluminium was used. For each component, sensitivity analyses are applied to see the impact of specific parameters such as the end-of-life recycling rate and the use stage driving distance. Significant greenhouse gas savings by the use of aluminium are demonstrated for cars and even higher ones for trucks, buses, trains and ships. In addition, the total potential benefits of light-weighting with aluminium are shown on the global level.

Jan 1, 2007

By H. J. McQueen

The irregular history of Mg wrought products is briefly described. The temperature and strain rate dependence of microstructural evolution, flow stress and ductility of Mg alloys in hot working, are described. The flow curves rose rapidly to a peak stress which was lower as temperature T rose and strain rate e declined and above 300°C the curves extended into plateaus until failure. Clearly grains not oriented for slip undergo mechanical twinning in the initial stages (a 0.15) at all temperatures. Basal slip proceeds in suitable grains and in the twins. The stress concentrations at grain and twin boundaries lead to slip on non-basal systems and to the formation of subgrains with greater dynamic recovery (DRV) at higher T or lower e. With increasing strain, misorientation builds up resulting in dynamic recrystallization (DRX) first at twin intersections and later at grain boundaries which have become quite serrated. Even after extensive straining at high temperatures, the new grains are found mainly along the boundaries of the original grains, leaving their centers with only basal slip except when nucleation at twins leads to completion of DRX throughout a grain. Despite similar shear modulus and melting point to Al, hot mechanical forming behavior of Mg alloys differ due to differences in crystal slip systems, twinning, and second phases. Moreover, the influences on forming of alloy additions (solutes, segregation in casting, dispersoids, precipitation) and impurities are not as well catalogued as for Al. Despite the benefits from dynamic recrystallization, varied grain orientation effects, heterogeneous substructures and the resulting stress concentrations result in considerably lower ductility for Mg alloys at the same stress level as for Al materials. Application of these theories to extrusion, rolling and forging and the effects on product properties are surveyed.

Jan 1, 2006

By L. P. Chrismas

"IN 1975, Nova Scotia produced 1.8 million tons of coal with a FOB mine value of $47.6 million. Of this total, about 30 per cent or 600,000 tons was coking coal and the remainder was steam and industrial-grade coal. The Nova Scotia Power Corporation consumed 630,000 tons in three generating stations and 570,000 tons were sold to Sydney Steel for making coke for its steel operations. Exports, principally to Great Britain, comprised 370,000 tons in 1975 in addition to the 300,- 000 tons shipped to other provinces for use by cement and pulp and paper companies. In 1975, just over 100,000 tons of coking coal were imported into the province from Alberta. Before 1975, low-volatile coking coal was traditionally obtained from the United States. In 1975, production came from seven individual mines and one project involving reclamation from mine dumps in Pictou County. Of the seven producers, four are owned by the Cape Breton Development Corporation, a federal Crown corporation; the remaining three are small independent mines, but, even though small, they are sizeable contributors to the economies of their local areas. After 101 years of continuous operation, Devco's Princess mine was closed in 1975. The Nova Scotia coal industry, in terms of value, accounted for about half of total mineral production in 1975. The industry provides jobs for 3,000 men and women. It is also significant that in 1975 Nova Scotia produced about 6.5 per cent of Canada's total coal production of 28.3 million tons. Detailed statistics on Nova Scotia's coal industry appear in the Appendix."

Jan 1, 1976

By H. Abdollahi

Cold rolling is one of the most important techniques in metal forming since the cold rolling products are almost finished product, The product quality of this process is widely influenced by friction in the roll gap; therefore, controlling the friction and other parameters affecting the cold rolling is very important in order to have a product with high quality, Among the cold rolling parameters, the pressure distribution or friction hill within the roll gap is known as the most significant one, In this study, a new software (Matroll), is introduced which can determine the coefficient of friction (COF) and plot the friction hills for an industrial mill, Besides, based on rolling equations, it offers about 25 rolling parameters as outputs. To verify the software operation, the real industrial rolling data was used as inputs, The results (outputs) are in good agreements with the findings of other researchers, The COF values are very reasonable, The friction hill shows that COF is not constant over the whole arc of contact.

Jan 1, 2005

By D. Ortiz, J. R. Frias, E. D. Mast, J. J. Fañas

Falconbridge Dominicana (Falcondo) has operated an integrated tpy nickel laterite mine and ferro-nickel processing plant since 1972 in the Dominican Republic. The operation includes mining, a processing plant, an oil refinery, and a power plant. Falcondo has improved process efficiency over the years via modernisation and better understanding of the process. The present business environment of high fuel prices and high nickel prices present a challenge and an opportunity to Falcondo's operation. This paper gives an update of Falcondo's process, improvements in energy consumption, factors affecting energy consumption and how Falcondo is facing up to the current business environment.

Jan 1, 2005

By \/eena Sahajwalla, Jonathan Dicker, Paul O'Kane, Cath Skidmore, James Dankwah, Magdalena Zaharia, Rita Khanna, David Knights, N Saha-Chaudhury, Somyote Kongkarat

Due to the inherent limitations of current methods of disposal of end of life polymeric materials, avenues are researched towards developing alternative, environmentally friendly and economic recycling processes. Different polymeric materials (i.e. rubber, high density polyethylene (HDPE) and polyethylene therephtalate (PET)), quite distinct in terms of chemical structure and composition, were considered in the present study as carbon resources in EAF steelmaking. Investigations were conducted in both laboratory and industrial scale steelmaking to assess the effectiveness of using these materials as carbon sources for slag foaming in EAF steelmaking. Slag foaming is important because it enhances furnace efficiency.

Jan 1, 2011

By J. E. Danoczi

ABSTRACT A diamond processing plant is being designed for the Star–Orion South diamond project in central Saskatchewan. Key to the plant is diamond liberation, which occurs in the comminution section and is the process of breaking up kimberlite rock as gently as possible to minimize diamond damage, particularly in larger, high-value diamonds. Kimberlite from the crater area of a volcanic pipe is generally softer than kimberlite from the diatreme zone. Softer kimberlite, comprising the majority of Star– Orion South deposits, can be readily broken up using abrasion and attrition by autogenous grinding mills, the preferred comminution method for minimizing diamond damage.

Jan 1, 2013

By B. I. Whittington

This paper examines the effect of cation type (i.e. NH4+, Na+ and K+) and anion type (i.e. SO42- and C1-) on the extraction of nickel during the pressure acid leaching of a Western Australian laterite ore. The results are compared with testwork conducted with other Western Australian nickel laterite ores and the possible process implications of adding an additive to a plant autoclave are considered. Addition of either (NH4)2SO4, Na2SO4 or K2SO4 increased both the nickel extraction and the acid consumption, provided that the level of additive was not too great. For example, the nickel extraction of 93% increased to above 96% in the presence of additives, but decreased to 94% when, for example, NH4 levels increased from 7 kg/t ore to 21 kg/t ore. The relative stability of the jarosite species formed when additives were present influenced the amount of jarosite in the residue and, hence, both the final free acidity and overall nickel extraction. The use of Cl- versus SO42- salts as additives had little effect on overall nickel extraction or overall free acid values, although the presence of SO42- additives appeared to enhance nickel extraction kinetics over the first 60 minutes of the reaction. In contrast, manganese extraction was enhanced by the presence of Cl- additives.

Jan 1, 2004

By D. Harrington

Ventilation of underground workings consists in establishment of such control of air currents that the underground workers may work in safety, with maximum comfort and efficiency, and without impairment of health; and requires that the mine openings may be made subject to such control of air flow as to remove from these workings at ordinary times harmful gases and dusts, and that, at time of emergency, such as fire or explosion, there may be maintained as much or as little air flow as may be desired covering portions of the mine or the mine in its entirety. Control of air flow is the keystone of any ventilating structure, and this very essential feature is obtainable only by the installation of mechanically-operated fans, together with other;. ventilating devices such as doors, over-casts, regulators, etc. Every mine, large or small, coal or metal, should from the outset be equipped with a fan. While much has been written about natural ventilation and many claims made that in specific mines there is sufficient natural air flow, there are few if any mines, coal or metal, where natural ventilation supplies anything like adequately safe or healthful conditions for underground workers even at ordinary times; and at a time of mine fire or explosion, mines depending upon natural ventilation are practically helpless, and certainly are decidedly dangerous to those unfortunates forced to be in them. While ventilation has practically always been deemed an integral part of coal mining, metal mines have rarely paid much, if any, attention to air circulation until forced to do so by occurrence of some untoward condition or accident. Yet metal mines actually have as great need of efficient circulation of air as have coal mines. The coal mine must remove the dangerous explosive gas, methane, also fumes from explosives and, in occasional places, other gases such as carbon dioxide or nitrogen.

Jan 1, 1933

By Raj Rajamani

In general, many past works examine mill load, mill power, shell lifter design etc with a view to improving the mill capacity. On the contrary, only a handful of papers have addressed the transport of fine slurry through the pulp lifters. We present the flow dynamics of pulp lifters via laboratory scale experiments, high speed photography and modeling with computational fluid dynamics. Next, the flow behaviour in ArcelorMittal?s Mont-Wright autogenous mill discharge flow is examined. In an effort to improve mill throughput, a comprehensive simulation and plant scale study of the mill was taken up with a focus on the shell and pulp lifter design. The shell lifter was found to be at its optimum limit for breakage of ore particles given the constraints of wear life and occupied volume. Next, the pulp lifter study was taken up with computational fluid flow code and discrete element code. The simulations directly showed that there was considerable carry-over of slurry. This effect was traced to the area restriction in the pulp lifter channels. Further, crash-stop studies confirmed slurry pooling within the mill. Thus it was readily apparent that mill throughput can be increased if the pulp-lifter could be redesigned. Consequently, the discharger section of the pulp-lifter was redesigned. First, this paper outlines the modeling in laboratory scale studies and plant scale studies leading up to the discharger design. Next, the discharge flow in seven different published mill surveys is predicted with computational fluid dynamics (CFD) methodology shown here. Finally, Mont-Wright mill circuit performance before and after the discharger redesign is described. The usefulness of fluid flow simulations in the design of pulp-lifters is emphasized.

Jan 1, 2012

By A. Allaire, J. Torrealba-Vargas, R. Welyhorsky

Early testwork was carried out to select the plant process design criteria and flowsheet selection. Additional testwork was carried out during the feasibility study to support the optimization of the plant design criteria. The test results showed that the recovery of gold was not very sensitive to grind size in the range of 75 to 105 microns. An additional result was that the presence of lead nitrate did not improve the kinetics of gold leaching. This conclusion was supported by the low content of sulphides in the ore. It was also found that the presence of lead nitrate increased copper dissolution, producing the potential for an increase of copper reporting to electrowinning, which is detrimental to the overall gold recovery process. The use of oxygen in leaching was investigated to increase leach kinetics. The results of leaching tests to compare using oxygen instead of air indicated that, due to the improved leach time, it was possible to reduce the number of leaching tanks from twenty four (24) to twenty (20).

Jan 1, 2011

By Frederic Benard

THE Ontario Refining Company, Limited, wholly-owned subsidiary of The International Nickel Company of Canada, refines the entire blister copper output of the latter's Copper Cliff smelter. Prior to 1936, the blister was cast in 460-lb. cakes at the smelter, loaded on open cars, and transported by rail to the refinery, a distance of approximately 1 1/4 miles. Here the cakes were transferred to the plant narrow-gauge system, charged to furnaces, and re-melted. This procedure necessitated the operation of holding furnaces and casting machines at the smelter -extensive re-handling-and melting down of a cold charge at the refinery. Transfer of the copper in molten form direct from converters to anode furnaces promised a considerable reduction in costs, and this possibility was investigated. As a result, a portable holding furnace, or hot-metal car, was designed and constructed. It was placed in operation in July, 1936, to be followed a year later by three additional units of slightly modified design. Figure 1 shows the original car, and Figure 2 the lacer type. With four cars in service, operations were placed on an all 'hot-metal' basis.

Jan 1, 1938

By A. N. May

"This paper describes the present approach of the Mines Branch to the problem of measuring the stress condition in the interior of rocks surrounding underground openings. An instrument, which will be referred to as a stressmeter, has been developed at the Mines Branch to measure un-directional stress changes in absolute units. There are two modes of operation of this stressmeter. It can be regarded as a fixed instrument, in which case it is installed at the end of a diamond drill hole and left in position to record any subsequent stress changes taking place. Alternatively, three of the stressmeters can be used in conjunction with a trepanning opera-tion to allow the existing stress condition to be determined. The initial laboratory work and subsequent experiences in the field with the stressmeter are described. All the field development work on the stressmeter was made possible through the co-operation of Canadian Refractories Limited, Kilmar, Quebec."

Jan 1, 1960

By J. Graham Eby

"This paper describes the development and some typical applications of Wemco's large-capacity flotation machines, the No. 120 and the No. 144, with volumes of 300 and 500 cubic feet, respectively. During the 1960's, it became obvious that low-grade orebodies would be mined at high tonnage rates - plants and grinding mills would be larger, which would create a demand for larger flotation equipment. To meet this demand, Wemco developed a single-mechanism, 300-cubicfoot cell, having five times the volume of the standard No. 66 cell. The average production rate of the No. 66 cell on porphyry copper ore was 100 tpd per cell; and it was our intention that the No. 120 (300-cu. ft) cell would handle 500 tpd per cell, with at least equal metallurgical results and power consumption per ton. The success and industry acceptance of the No. 120 cell has since led to the development of a larger cell, the No. 144, having a volume of 500 cubic feet."

Jan 1, 1972

By J. E. Dutrizac

Mercury balances have been obtained for the flotation circuits at Pamour Porcupine Mines, Timmins, Ontario, and at Brunswick Mining and Smelting Corporation, Bathurst, New Brunswick. The mineral form of mercury in both deposits has been ascertained. At Pamour Porcupine, the mercury is approximately evenly divided among sphalerite, native silverelectrum and tetrahedrite-tennantite; at Brunswick Mining, this element is contained mostly in the sphalerite, although tetrahedrite (and possibly pyrite) also contains minor quantities.

Jan 1, 1979

By T. A. Utigard

To improve recoveries of Ni, Cu and Co in the Inco flash furnace, a new operating concept was investigated. By adding sufficient coke to form a supernatant coke layer, a reducing barrier would form allowing for improved reduction of descending oxidized sulfide mineral particles formed in the flame. The objective of this investigation was to study the kinetic mechanism and efficiency of the coke layer to produce a sulfur deficient matte. The mechanism and rate of carbon reduction of each of the phases formed in the flash flame, i.e. sulfides and oxysulfides were investigated by means of X-ray visualization tests. Graphite-slag reduction was also conducted for comparison purposes. In the case of slag, poor wettability and the formation of a gas film on the surface of the carbon reductant are often blamed for limiting the reaction surface area that ultimately results in poor reaction kinetics. The X-ray visualization tests confirmed that matte and oxysulfide wet coke better than slag and that the rates of reduction of matte and oxysulfide are faster than that of slag.

Jan 1, 2005

By V. A. Preto

The Rexspar uranium deposit is located approximately 5 kilometres south of Birch Island, B.C. Three separate zones of commercial-grade uranium mineralization mineable by open pit have been outlined. Uranium and fluorite-celestite mineralization occur in a trachytic member of alkali-feldspar porphyry, lithic tuff, tuff breccias and pyritic schist conformably interlayered with a succession of strongly deformed greenschists and fragmental rocks that are, in large part at least, of volcanic origin. The age of these strata is not precisely known, but they are considered as part of the possibly Mississippian Eagle Bay Formation. Commercial-grade uranium mineralization is always associated with fluorphlogopite-pyrite replacement of the trachytic unit and is contiguous to, but separate from , a zone of ore-grade fluorite mineralization. In all zones, ore occurs in lenses of variable thickness and lateral extent, which lie parallel to the schistosity of the trachytic rocks and surrounding greenschists. The principal radioactive minerals at Rexspar have been identified by other workers as uraninite, uranothorite, bastnaesite, torbernite and metatorbernite. Considerable amounts of thorium oxide and widespread rare earths have been reported from all three radioactive zones. The geology of the deposit suggests that the trachytic rocks represent a highly differentiated intrusive-extrusive system in which fluorphlogopite, pyrite, fluorite and uranium-bearing minerals were deposited late in the evolution of the system by deuteric, volatile-rich fluids. The considerable amounts of thorium and widespread rare earths associated with the uranium tend to support the thesis that this element is of primary origin rather than secondary.

Jan 1, 1978