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By A. M. Cann, C. I. Godwin

"The Kemess porphyry copper-molybdenum deposit occurs in the Intermontane Belt of north-central British Columbia. The deposit is in andesitic to basaltic flows and tuffs which may be correlated with the Savage Mountain Formation of the Upper Triassic Takla Group. Most known chalcopyrite and molybdenite is associated closely with a 500-m-diameter zone of intense quartz-sericite-pyrite alteration. A zone of supergene enrichment, up to 30 m thick, underlies a leached capping about 20 m thick. The age of mineralization and the surrounding granodiorite and quartz monzonite pluton is Early Jurassic. K-Ar and Rb-Sr analyses indicate that the mineralization and alteration is slightly younger (l82±6 Ma) than the granitic intrusion (KAr: about 205±6 Ma; Rb-Sr: 190±4 Ma). The low 87Sr/J6Sr initial ratio for the granodiorite is typical of plutons in the Intermontane Belt.IntroductionKemess is a medium to small porphyry copper-molybdenum deposit with significant gold and silver values (Pilcher and McDougall, 1976). This paper describes the lithologies and alteration at this property; geochronology by Rb-Sr and K-Ar methods defines the ages of mineralization and surrounding plutons to be Early Jurassic.The property, located in the Thutade Lake area of northcentral British Columbia (NTS Map 94E; lat. 57°04'N; long. 126°44'W), is about 425 km northwest of Prince George (Fig. 1). Closest road access is 35 km southeast of Kemess. Final access must be by float plane or helicopter. The British Columbia Railway right of way passes 70 km to the southwest of theproperty.A prominent gossan zone at Kemess was staked in 1967 by Kennco Explorations (Western) Ltd. following detection of geochemical anomalies during stream sampling the previous year. During 1968, 1969and 1971, Kennco completed 232 m of X-ray diamond drilling, conducted geological mapping and carried out geochemical sampling of silts and soils (Stevenson, 1969; B.C. Ministry of Energy, Mines and Petroleum Resources, G.E .M., 1969 and 1971). Getty Mines Ltd. optioned Kemess in 1975and 1976. They remapped the area and diamond drilled 12 BQ and NQ holes, totalling 2065 m (B.C. Ministry of Energy, Mines and Petroleum Resources, Expl. B.C., 1975)."

Jan 1, 1980

By S. Ianos, C. Vibert

Type and shape of large dams founded on rock depend upon the expected deformation of their foundation. Their design consequently requires the assessment of the deformability of the rock mass at large scale. Seismic refraction, laboratory tests on rock samples and empirical formulas can provide an order of magnitude of the deformation modulus, with a limited degree of reliability. Direct in-situ measurement of the deformability of a volume of rock is therefore preferred, which integrate the effect of discontinuities, such as plate loading tests, dilatometric tests, etc. The authors have been compiling results obtained by in-situ deformability tests on a number of dam sites, including the Scarabée (“Petite Sismique”) method. This last method consists in thoroughly analysing the shape of seismic wave forms transmitted through the rock mass. It has been used since now more than 40 years over a large number of dam foundations, and has proved to provide a satisfactory assessment of the static deformation modulus. After comparing the results obtained from different methods on six dam sites, the Authors conclude that their reliability closely depends upon the size of the loading device in relation to the spacing of the discontinuities. Attempts to correlate results from different types of in-situ loading tests reveal difficult, because closely depending upon local geotechnical conditions at test location. Plate jacking tests appear to be the most reliable, because involving a relatively large volume of rock. On the other hand, the Scarabée method (“Petite Sismique”) allows a rapid assessment of the deformation characteristics of the rock mass at large scale, and has been found to provide values generally in agreement with those from plate loading tests, while dilatometric or flat-jack tests were found too dependent upon local conditions. The Authors conclude that preference should be given first to the Scarabée method, which uses light equipment and is quickly performed, together with an accurate geological and geotechnical assessment for interpretation. In a second stage, Scarabée shall be complemented by adequately performed plate jacking tests in selected locations, in order to cross-check results and refine the assessment. The general accordance between the results of the two methods, which both can integrate anisotropy of rock masses, justifies this statement.

Jan 1, 2015

By R. D. Brown

"Concerns over possible additional involvement of governments in Canada's mining industry and its adverse effects on the industry 's growth were a frequent topic of conversation at the recent Annual General Meeting of the CIM.Still painfully fresh in the minds of industry leaders are the disastrous results of the federal/provincial scramble over resource revenues which followed the relatively high metal prices witnessed in 1973/1974. At current metal prices, it is not surprising, then, that a nagging fear persists that these governments may once again restructure tax and other rules to the detriment of the industry and the country.This month, Tax Notes recalls some of the progress which the industry and governments have made in 1979 in the taxation of the resource sector, and urges that higher metal prices be viewed in light of the costly exploration, development and production efforts which will be required for the industry to continue to play its important role in our economy.IntroductionAt the Annual General Meeting of The Canadian Institute of Mining and Metallurgy, held in April, 1980, it was abundantly clear that there is widespread concern in Canada's mining industry that this country's tax regime may once again be blasted by ill winds of change.A stable and more favourable tax climate, as well as higher metal prices and profits, made 1979 almost a golden year for Canadian mining. However, from the tax viewpoint at least, there are some spots on the silver lining as apprehensions grow that the well-heralded battle between federal and provincial governments over oil and gas may spread to the mining sector, with serious damage to the industry and its newfound federal-provincial cooperation."

Jan 1, 1980

By R. Amata

"The Gakara Rare Earth deposit in Burundi (East Africa) is unique for its high grade (e.g., 54.3% TREO on average) and low uranium and thorium levels. The majority of the light rare earth (RE) elements in material from Gakara are contained within the familiar RE minerals bastnaesite and monazite. Extensive metallurgical test work was conducted by SGS Minerals Services on mineral samples collected from the Gakara deposit. Various whole ore hydrometallurgical processing routes were examined in a scoping level test program. Preliminary beneficiation testing was also conducted, though it was determined that only marginal upgrading would be achieved with significant RE losses. Thus a hydrometallurgical process on whole ore was developed to minimize the overall process complexity and achieve maximum RE recovery. Results from the test work will be presented, along with the selected base case flowsheet involving agitated atmospheric sulphation of the RE minerals, RE double sulphate precipitation, caustic conversion, redissolution, and carbonate precipitation. Following the base case flowsheet, a purified cerium free mixed RE carbonate with low levels of radioactive elements was produced.INTRODUCTIONRainbow Rare Earths Limited (Rainbow) is a mining company engaged in the exploration and development of the Gakara rare earth deposit in Burundi; Figure 1 shows the project location. The project is located in the Bujumbura Province and 45 km from the Burundi capital of Bujumbura. Notable for its exceedingly high in-situ grade – 54.3% on average total rare earth oxide (TREO), low uranium and thorium levels and familiar rare earth minerals, bastnaesite and monazite – Gakara is the world’s richest rare earth deposit. The project, a previously operating mine from 1948–1978, has a significant mineral inventory base, a long life of mine, well understood mineralogy, and robust economics. Rainbow is focused on bringing Gakara into production in the near term, ramping up to produce 5,000 t/y of a 54%+ TREO concentrate."

Jan 1, 2016

By T. Lamb

There are many honor stories about aluminum in the marine environment and many are not based on facts, so they are myths. Myths must be addressed before progress can be made. This paper attempts to dispel the myths and state the facts. A common perception is that aluminum ships cost significantly more than steel ships. This paper illustrates that even though the cost of the aluminum structure is over 50% more than the steel structure, an "equivalent" aluminum naval ship can be built within 7% of the acquisition price of a steel ship. This is possible because of the cascading benefits of the aluminum ship's significantly lighter weight. Aluminum ships also have a life-cycle cost advantage over steel ships because of reduced maintenance and fuel cost savings.

Jan 1, 2011

By R. J. Mitchell

"The use of hydraulically delivered classified tailings sands to provide ground support in large mining operations is still widespread despite recent developments of alternate backfilling methods and materials. The major disadvantages of the use of hydraulic fill are the costs and risks associated with slurry delivery. The main risk is that of bulkhead failure resulting from sand liquefaction due to insufficient operational control or due to dynamic loading from earthquake or rockburst. That risk may be eliminated by the pouring of a stiff cemented sand plug in the base of each stope prior to continuous fill pouring in that stope. An additional advantage of cemented plugs is that massive bulkheads are not needed. Instead, a temporary (removable and reusable) bulkhead can be used for plug forming.Physical model studies of fill pressures on a temporary bulkhead were carried out in a 3 m radius centrifuge facility. Fill pouring in-flight was carried out in order to model prototype stress paths. The results indicate that the average bulkhead pressure is likely to be less than 10 kPa under normal operating conditions and less than 20 kPa under the poorest anticipated operating conditions which include smooth walls, high slimes content and high water-content slurries. A portable bulkhead consisting of a central core and a surrounding sealing bladder was modelled and found to be effective. The use of different sizes of cores allowed the stress distribution adjacent to these bulkheads to be evaluated."

Jan 1, 1992

By John E. Callahan

"A stream sediment geochemical survey covering an area of 13.000 sq. km near Churchill Falls. Labrador. was conducted for Brinex (British Newfoundland Explorations Ltd.) prior to partial flooding by the Churchill Falls power project. Stream sediments (minus 80-mesh) were analyzed for Cu, Pb, Zn, Ni, Ag, Mo. U and Mn, and the heavy mineral, nonmagnetic fraction (minus 60-mesh) for Cu, Pb, Zn, Ni, Ag, Mo, Ba and Mn. A binocular examination of the concentrates for sulphides and pyrope garnet was done on the heavy mineral concentrates. The concentrates were also examined for fluorescent minerals.Two distinct areas with high trace-element values indicate the need for follow-up studies. The first is in an area of gabbro erratics containing massive and disseminated sulphides (pyrrhotite, pyrite and minor chalcopyrite) on the western edge of the survey area along the Esker Road. The second, largest area (several hundred square kilometres) is anomalous in U and Mo and associated with felsic intrusives (Red Wine Complex?), syenites. granite gneiss and sedimentary rocks (Seal Lake Group?).The binocular study showed that almost 15% of the heavy mineral concentrates contained pyrite and no other sulphides. This indicates that this technique may be worthwhile in determining the presence of sulphide minerals in stream sediments from glaciated environments. The only fluorescent mineral observed in the study was zircon."

Jan 1, 1981

By Hoeve. J.

"In the unconformity-type uranium deposit at Midwest Lake, mineralization is associated with extensive host rock alteration, which affects the metamorphic basement as well as the overlying Athabasca Group sandstones. Host rock alteration is manifested by (I) transformation of clay minerals [kaolinite into illite and chlorite (sudoile)]; (2) bleaching due to removal of hematite from the lateritic paleoweathering profile and the overlying red bed, Athabasca Group sandstones; (3) loss of coherence of the sandstone resulting from corrosion of quartz cement; and (4) in the immediate vicinity of high-grade ore, development of a clay envelope due to residual enrichment of clay minerals caused by massive dissolution of quartz. Clay mineral transformation and bleaching are the most prominent and the most widespread alteration effects, forming haloes that extend for several kilometres along the strike of the mineralized structure and also constitute distinct alteration pipes that rise f or several hundred metres above the unconformity to be truncated at the present top of the bedrock.Although the two haloes are largely congruent features, cross-culling relationship s indicate that clay mineral alteration represents an earlier phase in the history of the deposit than the large-scale bleaching that gave rise to the superimposed bleaching halo.Because clay mineral alteration and bleaching are intimately tied to the mineralization and extend well beyond the limits of the actual orebodies, host rock alteration may be used as an ore guide in exploration and drill-hole evaluation. In this application a third hydrothermal discharge centre was identified, as yet untested for are, which is located between the hydrothermal centres associated with the two known orebodies of the deposit.It is estimated that host rock alteration may enlarge a potential drill-target by a factor 10 - 20X. Information on the configuration of bleaching haloes can be obtained from systematic core logging, whereas diagnostic clay mineral alteration is readily identified by means of automated, quantitative XRD techniques."

Jan 1, 1984

By Q. G. Reynolds, R. T. Jones

The choice of furnace design parameters has a marked effect on the integrity of the furnace that is constructed. The design methodology for DC arc furnaces typically begins with the chemical reactions and feed materials that define the process. The specific energy requirement of the process, and the feedrates of the raw materials largely determine the power requirement for the furnace. A chosen value for the 'power intensity' sets the diameter of the furnace. Justification is provided for why this is a good choice of scale-up parameter. Equations are presented to quantify the resulting trade-off between thermal efficiency and the degree of error that can be tolerated in the balance between power and feedrate. This improved understanding should provide a better rationale for selecting an appropriate power intensity (or furnace diameter) for future furnaces.

Jan 1, 2015

By S. B. Kang

Magnesium has poor ductility at temperatures lower than 225°C and, as a result, Mg alloy sheets are produced via fairly complex thermomechanical processes consisting of numerous sequential steps of hot (warm) rolling with low reduction and intermediate recrystallization annealing operations. In context of the present study, a simple technology for the fabrication of magnesium sheets by hot (warm) rolling was applied to various magnesium alloys. The misch metal addition in those AZ alloys was done to evaluate the deformation behavior. Tensile tests were carried out for those AZ alloys after applying different heat treatments. The precipitation of ß phase (Mg17Al12 phase) induced different microstructures with various cooling method from solution treatment temperature, and also with various annealing treatment temperatures.

Jan 1, 2006

By Charles Camsell

THE Northwest Territories covers a very large area-more than one-third of all Canada-and its most northern point, Cape Columbia in Ellesmere island, is distant only 500 miles from the Pole. Our first knowledge of the Arctic Archipelago, of which Ellesmere island forms a part, resulted from a gold-mining venture in Queen Elizabeth's reign. The English navigators of that time were eager to find a north-westerly and shorter and Jess hazardous route to the riches of China and Japan than that which Magellan had discovered, but they were unaware that the continent then known to bar a direct route extended in great width far to the north. Frobisher was one of these navigators. He reached in 1576 the bay in Baffin island now named after him, convinced that he had found a passage connecting the Atlantic with Asiatic seas. Forced to re-turn after ordeals in which ice, wind, and Eskimos flayed formidable parts, he brought back, among other novelties, a piece o black stone which had been picked up casually by one of his officers, and gave a little of it to the wife of one of the venturers, or financial backers of the enterprise. To quote now from Hakluyt: ? 'She by chance threw and burned it in the fire so long that , at length being taken forth and quenched in a little vinegar, it glistered with a bright marquesset of gold. Whereupon the matter being called in sorne question, it was brought to certain goldminers in London to make assay thereof, who indeed found it to hold gold and that very richly for the quantity." On the strength of this, the venturers, anticipating much profit, launched a second expedition to secure more of this stone, and 143 persons, including 14 miners and finers, set forth in 1577 and returned the same year, with, however, 200 tons of another mineral. Influenced by glowing accounts of veritable mountains of this mineral and by assays made after "additaments"-that is how "salting" in those days was described-the venturers, including Elizabeth, supplied funds for erecting a smelter and refinery at Dartford and outfitting a stilllarger expedition. And so, in 1578, fifteen ships departed with the Queen's blessing, for the same remote shores. After many mishaps, they returned with over 1,000 tons of the mineral, but when it yielded very little of value at the works in Dartford, the? Company of Venturers was forced into liquidation. Though our first prospector and miner was rather inconsiderate of the investors, he proved the existence of an archipelago, hitherto unknown, and secured much information about the new land and its dwellers.

Jan 1, 1938

By V. G. Papangelakis, M. Cheung, M. Dry

The high pressure acid leaching of laterite was modelled and simulated using a combination of two commercially available software packages, namely Aspen Plus 11.1 and the OLI Stream Analyzer. New kinetic parameters for the acid-controlled metal dissolution and precipitation reactions at temperature were first determined from previous experimental data on the leaching of limonite. A grain model with cylindrical pellets was used to model the solid-liquid dissolution reactions. Precipitation reactions were modeled via aqueous equilibrium chemistry. A dedicated thermodynamic database previously developed at the University of Toronto was used in conjunction with the OLI software to model the solution chemistry and calculate the concentration of hydrogen ions in solution at the leaching temperature. Mass balances were handled by Aspen Plus. The simulation gave good predictions of nickel dissolution under industrial and laboratory conditions, for the dissolution of limonite and limonite/saprolite blends. Computational

Jan 1, 2005

By John A. Hudson, Xia-Ting Feng, Joseph S. Y. Wang

Evolution over decades and progress over last five years have been made in many topics of interests to rock mechanics, geosciences, physics, and multi-disciplinary interactions in underground research laboratories and development facilities, as well as in underground energy recoveries and environmental assessments. Rock mechanics and geotechnical engineering advances are associated with quantifications of disturbed/damaged zones and rock alternation and bursting processes and creation of underground spaces and accesses associated with deepening of shafts and lengthening of tunnels. Geophysics and earth sciences advances are associated with continuing collections of seismic, electromagnetic, and gravitational data and conducting various thermal, hydrological, mechanical, chemical, and biological investigations, both separately, simultaneously, and in different coupled ways. Astroparticle and underground physics advances are associated with many long term experiments to detect rare events and needs for increasing larger and deeper halls to accommodate next generation detectors, shielings, and isolations. There are also increasing interesting in underground settings to explore multidisciplinary and inter-disciplinary sciences and technologies. Energy and environmental sciences and assessments have evolved from traditional oil and gas focuses to recent activities associated with green resources and alternative recovery/disposal strategies. The evolution and progress of these interdependent and related fields are discussed in this quadrennial Congress.

Jan 1, 2015

By Bertrand Robinson

Great advances have been made in rubber-lined pumps for the pumping of mill pulps. The Canadian Allis Chalmers alone report ov.er 300 such pumps put into service during the past four years. Pumps in which both the casing and the impeller are rubber covered have proved most economical in handling the usual run of mill pulps, effecting large savings in power, maintenance, and shutdown costs. For the handling of pulps containing comparatively large, sharper edged /articles, rubber-lined casings with hard iron impellers have been developed by the pumping departments of Hollinger and Noranda. These rubber-iron combination pumps show an appreciable reduction in overall pumping costs as compared with the all-rubber and the all-iron pumps. The power efficiency is lower in rubber-iron than in all-rubber pumps but higher than in the all-iron pumps, with lower replacement costs due to the cheap iron impellers used. Where continuous operation is essential, however, and duplication of units to take care of shutdown time for replacement of parts is not within the expenditure budget of the company, all-rubber pumps are being used t0 a greater extent. As in all items pertaining to milling operations, the economics of the situation must be studied as closely as the technical details, to arrive at the most advisable practice.

Jan 1, 1939

By Jack A. Caldwell

"This paper describes the nature of stage curves and the ways in which they have been used to study the construction sequencing of tailings impoundments. They provide a simple graphical method of representing the main aspects of an impoundment, studying the effects of different impoundment geometries, and predicting and controlling impoundment operations.IntroductionThe designer o f a tailings impoundment must, at all stages of design, examine the relations hip between the volume o r tones of tailings that will be deposited at the impoundment, the height to which the tailings will rise in a given time and that rate at which the various parts of an impoundment will be constructed. The operator, if he is to keep proper control of this impoundment, must be able to examine the effect of different deposit ion rates at the impoundment, and the consequences of placing more or less tailings at different parts of the impoundment. The operator must be able to see at a glance just how much higher an impoundment will be at the end o f the following yea r of deposition, and this he must be able to do in order to formulate his annual construction and operating plans.Stage curves are the best way o f modeling an impoundment. The simple impoundment model represented by the stage curves enables the designer and operator visually to examine the relationships between the various factors, such as impoundment volume, deposition rat e and construction rate, that dictate the essential features o f impoundment design and operation.A design model for a tailings impoundment may be formulated as in Figure 1. This involves the site selection process, the definition o f a geotechnical model, a water balance model and a height-capacity-production model."

Jan 1, 1983

By S. F. Guo, B. W. Zheng, X. L. Huang, S. W. Qi

"The study of mechanical characteristics of rock discontinuities under different shear deformation velocities is an important premise of rock slope dynamic response analysis. According to disposing and calculating the experimental results of previous research about peak shear strength of rock discontinuities under different shear deformation velocity of constant normal loading, the law of influence of shear velocity on the total friction angle is studied. Based on the research results, it can be found that the total friction angle of rock joint specimens varies in the form of negative logarithm with the variation of shear deformation velocity. It’s also indicated that the total friction angle of rock joints decreases with the increase of shear deformation velocity for rock joints of relative strong homogeneity and isotropy. However, the total friction angle of rock joints increases with the increase of shear deformation velocity for rock joints of relative strong heterogeneity and anisotropy and the latter amplitude of increase is less than the former amplitude of decrease. The physical property and microscopic geometry of rock joints play an important effect on the increase or decrease tendency and amplitude variation of total friction angle with the increase of shear deformation velocity.INTRODUCTIONThe rock slope dynamic response is largely restricted by rock discontinuities. Hence the study of dynamic characteristics of rock discontinuities, especially the dynamic shear characteristics is an important premise of rock slope dynamic response analysis (Qi et al., 2007). Seismic load is both dynamic load and cyclic load (Liu et al., 2011). Under the dynamic and cyclic shearing actions of seismic load, the rock slope which is stable under the condition of static load may slide along the rock discontinuities whose shear strength reduce and then the earthquake landslides occur. The strength degradation and deformation mechanism of rock discontinuities under the dynamic and cyclic shearing actions is one of the key problems to be solved in the work of earthquake prevention and control of engineering slope. Based on the above understanding, predecessors conduct some researches which focus on the shear behavior mechanical characteristics of rock joints under cyclic shearing actions (Plesha, 1987; Hutson & Dowding, 1990; Jing et al., 1992, 1993; Huang et al., 1993; Qiu et al., 1993; Homand et al., 2001; Lee et al., 2001; Jafari et al., 2003; Liu et al., 2011, 2013). However, there are a few researches about the mechanical characteristics of rock joints under different shear deformation velocities because of the restriction of shear apparatus. Crawford and Curran (1981) conducted a series of one-way cyclic direct shear tests on four kinds of natural rock joints under different shear deformation velocities varying from 0 to 200 mm/s. The tests showed that at low normal stresses the peak shear strength of soft rock joints exhibited an increase up to a certain velocity, after which it remained essentially constant. For rock joints of intermediate hardness, the peak shear strength was essentially independent of shear deformation velocity; whereas for hard rock joints, the peak shear strength of which showed a significant variation with the shear deformation velocity. Jafari et al. (2003) carried out a series of conventional triaxial tests on artificial rock joints of regular saw-tooth shape with axial loading rate from 0.05 mm/s to 0.4 mm/s."

Jan 1, 2015

By P. K. Kaiser, C. D. Martin, F. Amann

"This article focuses on the uniaxial compressive strength (UCS) of homogeneous and heterogeneous rocks. Critical factors impacting the UCS of rocks are reviewed and then separate assessments of UCS data from homogeneous and heterogeneous rocks are presented. The variability (coefficient of variation) of UCS test results for homogeneous rocks is found to be generally <25% while for heterogeneous rocks the variability is >35%. Failure mode variation is found to be the cause of the variability of UCS test results in heterogeneous rocks. Empirical engineering design methods that use UCS as an input parameter are discussed and suggestions are provided for selecting appropriate UCS values.INTRODUCTIONThe UCS is one of the most commonly used rock engineering parameters whether for rock mass classification or for strength determination. The mean UCS and its variability are often assumed to represent a reliable rock material property. For the reasons discussed in this article, UCS is rarely representative of the intact rock UCS. The UCS test simply records the collapse load during uniaxial loading of a cylindrical specimen. As suggested by many, the UCS is an index rather than a unique engineering parameter. The UCS is thus a proxy for rock strength which depends on the loading rate (e.g., Bieniawski 1967), specimen geometry (e.g., Hudson et al., 1971), specimen size (e.g., Bieniawski 1968), and many other factors. Furthermore, the UCS is not the same as the Hoek-Brown strength criterion parameter sci.There are differences in opinion on what is commonly considered to be ‘intact rock’. When sampling ‘intact’ pieces of core from drillholes crossing blocks of rock bound by block forming discontinuities, samples will be ‘intact’ but some samples will be veined, others will be damaged, and others will be neither. According to Hoek (1983), intact rock pieces are “the unfractured blocks occurring between structural discontinuities in a typical rock mass” and the sci parameter for intact rock is determined using the fitting procedure proposed by Hoek and Brown (1997) based on the data requirements outlined by Hoek (1983). Studies (e.g., Bewick and Kaiser 2014; Kaiser and Kim 2014) have shown that independently determined UCS and sci values for the same rock type are not equivalent. Thus, UCS data cannot be used as a replacement for sci."

Jan 1, 2015

By L. Tafaghodi, S. Sarbishei

"Following the depletion of nickel sulfide ores, laterites are considered as one of the main sources for producing nickel and cobalt. One of the primary steps in pyrometallurgical extraction of nickel from laterites involves partial reduction of the ore at temperatures below 1000°C. Studying the kinetics of laterite reduction provides valuable information on reducibility of nickel laterites using coal as a reductant. The present study investigates the reduction behavior of a nickel laterite by thermal gravimetric analysis and differential scanning calorimetry. Non-isothermal reduction tests and X-ray diffraction analysis were performed to find the main reactions that occur during the process. The kinetic parameters were calculated by Coats-Redfern method. The general model of simple reaction f(a)=(1-a)n was used for calculating kinetic parameters.INTRODUCTION Nickel (Ni) naturally occurs in the form of sulfide and laterite ores. Laterite ores are mainly available in tropical regions. Weathering phenomena during millions of years has led to the formation of several layers with specific mineralogy (Butt & Cluzel, 2013). The three main layers downward are limonite, smectite, and saprolite (Crundwell et al., 2011). Although laterites are the most available nickel ore resource (70%), their share in the overall Ni production is limited to 40% (Crundwell et al., 2011). The main reasons for not materializing the full potential of laterites are as follows (Ray et al., 1985): •,Laterite ores contain high water content (free and combined) which in turn results in high energy consumption of the extraction process. •,As Ni is present in the form of solid solution in laterites, physical upgrading methods such as flotation are not effective in increasing the Ni content before the extraction process. •,Extracting Ni from sulfide ores involve exothermic reactions which are beneficial due to decreasing the overall energy requirement of the process, however there is not efficient release of energy in the process of extracting Ni from laterite ores."

Jan 1, 2017

By Niraj Bala

Boiler tubes of coal-fired boilers suffer severe erosion-corrosion (E-C). One method to counteract this problem is by the use of therma, spray protective coatings. Cold spray coating process was used to deposit Ni-20Cr powder on SA 516 (Grade 70) boiler steel. The bare as wel, as the coated steels were subjected to cyclic experimenta, studies, in the superheater zone of a coa, fired boiler. The weight change technique was used to establish kinetics of the erosion-corrosion. XRD, FE-SEM/EDS and X-ray mapping techniques were used to analyse the as-sprayed and corroded specimens.

Jan 1, 2010

By I. Imris

The chemical industries are using different type of catalysts, which after application usually produced many tons heap of residues. One of them is cupric oxide catalyst with high content of copper and silica. The recovery of copper from the waste has become major interest from a viewpoint of environmental protection and recycling of resources. The thermodynamic analysis and experimental results suggest that the copper from cupric oxide catalyst can be extracted by plasma reduction process. By plasma reduction process the inert slag and copper with following chemical composition: 99.04 % Cu, 0,042 % Fe could be obtained.

Jan 1, 2007