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By T. Senga, T. Namihira, S. Terada, S. Owada

"Electrical disintegration (ED) has been well known as a good comminution method to improve liberation of compositional phases because it was reported that electron avalanche could occur preferentially at phase boundary. But the detailed mechanism of the ED has been still not known. This paper describes the results of ED experiments using synthetic binary sample, copper/resin, under the conditions of various distance between electrodes, and discusses the energy distribution in the three kinds of phenomena in the ED process, which are(1) streamer progression in water, (2) electron avalanche in water, and (3) electron avalanche in solid sample, by measuring current and voltage with elapsed time. Then, it has been found that the energy distribution in the phenomenon (1) is quite low and that the distribution in the phenomenon(2) had a considerably large compared with that in the(3), which indicates that the shockwave generated in water could contribute much to the sample breakage.INTRODUCTIONElectrical disintegration (ED) has been well known as a specific comminution technology which enhanced selective breakage at phase boundary and lead to a good liberation among compositional phases1-6),but the detailed mechanism has not been clarified yet. This study describes energy distribution among the phenomena in the ED process by using a synthetic binary sample, copper/resin, the phenomena of which are (1) streamer progression in water, (2) electron avalanche and shockwave generation in water and (3) electron avalanche in solid sample usually at phase boundary. The energy distribution could be calculated from ED experiments and from voltage-current changes between electrodes as a function of elapsed time.SAMPLE AND EXPERIMENTALSampleThe sample used in this paper was a synthetic binary solid of copper/resin as shown in Figure1.Cut and polished pure copper lump was put into silicone mold and melted epoxy resin was poured into it and cooled, then, finally the binary sample was polished and molded in the form of 10 mm * 10 mm * 10 mm."

Jan 1, 2017

By T. C. Chudy, C. C. Hamilton, G. R. Lane

The selection and provision of mineralogical services to assist in developing a GeoMetallurgical program for a Cu Porphyry Mine in South America is covered in this paper and presentation. The objectives of the study were to provide a rapid mineralogical scoping protocol to support and confirm results of sequential Cu leach data and to provide detailed mineralogical analysis of four composites and products on which locked cycle test-work were performed. Results showed good reconciliation was achieved between measured chalcopyrite and secondary Cu mineral contents with leach data using a linear intercept mineralogical procedure by TIMA (Tescan Integrated Mineral Analyser), as well as a generally positive correlation between pyrite and Cu-sulphide grain size. Size-by-size analysis of Composite feeds and test products was used to outline comparisons between feeds on a mineralogical basis and provide liberation and association data with which to diagnose and better explain performance. Identifying key mineralogical drivers to Cu recovery and concentrate grades using these results, a greater understanding of the role of chalcocite and pyrite on metallurgical performance was established. INTRODUCTION As a global supply of copper, porphyry copper deposits are typically very large, often in excess of a billion tons of ore (Keeney, Walters, & Kojovic, 2011; McMillan & Panteleyev, 1980) with grades typically between 0.2 and 1.2% Cu, and up to 2% Cu in places. They are also a source of gold. The complexity of copper porphyries arises from their classically zoned nature, the type of host rock, as well as whether or not they have been overprinted by oxidation, weathering and supergene enrichment (Sillitoe, 2011). Zones of alteration and other geological attributes give rise to varied mineralogy, ore mineral textures and material properties, all of which result in different processing characteristics. Due to the interdependencies of geological and processing characteristics, it is vital to study links between the geology at the macro-scale and mineralogical features down to millimeter and micrometer scale (mineral content and texture) and their influences on mineral processing behaviour (Cropp, Goodall, & Bradshaw, 2013). The growing field of GeoMetallurgy aims to provide an Orebody Knowledge framework by which to gather such information as it pertains to: (1) Understanding and predicting likely flotation response; (2) Guiding relevant test work to investigate and validate links, interdependencies, theories and data interpretation/evaluation; (3) Populate a block model with relevant information and; (4) Implement and refine the model for ongoing optimization and control. Specific questions addressed by using mineralogy often include flotation diagnostics as aids to interpretation, causes of dilution and losses to tailings, as well as guidance to sampling for test work (Cropp et al., 2013).

Jan 1, 2019

By Xiaoxing Hu, Guibing Zheng, Yangge Zhu, Xingrong Zhang

"In China, more than 90 percent of titanium resources are reserved in vanadic titano-magnetite deposits. In this type of ore, the same elements such as Ti, Fe, Ca, Mg exist on surface of both ilmenite and titanaugite (the gangue mineral) because of isomorphism, which makes selective flotation difficult. Therefore, how to enlarge the floatability difference between these two minerals has always been a research emphasis and still needs to be studied further. In this paper, the pre-treatment methods using ultrasonic wave were proposed. The results indicate that ultrasonic treatment shows beneficial effect to enlarge the floatability difference, and the effect will be strengthened by extending the ultrasonic treatment time or increasing the ultrasonic power. The mechanism was investigated through infrared spectroscopic (FT-IR) analysis. Collector interacts with Ca and Mg which results in titanaugite flotation, after ultrasonic treatment, the dissolution of Ca and Mg is intensified, which leads to the lack of active points on mineral surface, so the floatability of titanaugite is depressed. Meanwhile, collector mainly interacts with Fe which results in ilmenite flotation, and the present of ultrasonic might promote its oxidation (Fe2+ to Fe3+), so the floatability of ilmenite after sonication is increased.INTRODUCTIONUltrasonic is the sound wave with frequency of 2 × 10-4 Hz~2 × 10-9Hz. Since the first International Symposium of Sonochemistry in 1986, the application of ultrasonic wave is more and more extensive. In researches about mining and metallurgy, various investigators have shown that intensive acoustic fields can modify the state of a mineral, leading to chemical or dispersive effects. Generally, the effect of ultrasonic vibration depends upon the nature of the mineral and also the way ultrasonic wave is applied (Celik, 1989; Ozkan, 2002). In addition, ultrasonic treatment usually plays roles of removal of reagents adsorbed layer from minerals and emulsification of flotation reagents when it is used in flotation (Nicol, Engel, & Teh, 1986; Slaczka, 1987; Djendova & Mehandj, 1992; Farmer, Collings, & Jameson, 2000; Gurpinar, Sonmez, & Bozkurt, 2004)."

Jan 1, 2016

By Tatyana Alexandrova

The problem of processing refractory (rebellious) gold ores is important for all the countries involved in recovering precious metals from ores. Technological aspects of processing precious metal ores are examined in two respects: enhancing gold recovery from double refractory ores; and using carbonaceous ores on a production scale. The dispersed carbonaceous matter (DCM) present in concentrates causes the adsorption of [Au(CN)2]- complex on their surface during cyanidation process. Depending on the degree of graphitization and the organic carbon content in DCM (including kerogens and bitumen), the technology used to recover precious metals varies considerably. The problem of processing refractory (rebellious) gold ores is important for all the countries involved in recovering precious metals from ores. Depending on the degree of graphitization and the organic carbon content in DCM (including kerogens and bitumen), the technology used to recover precious metals varies considerably. The possibility of rare metals recovery, including rhenium, from black-shale rocks, has been examined. Comparative assessment of analytical methods of rare metals detecting has been carried out. It has been proved that neutron activation analysis is a promising technique. It has been shown that colloid-salt fraction (nanofraction) with particle size less than 1000 nm makes up to 3 wt% of black shale samples and is extracted by water under special conditions. The use of water instead of chemically active reagents provides insolubility of the mineral matrix and fully reflects the colloid-salt element of the samples. To sum up, the justification of the choice of technology for processing of carbon-bearing ores is based on examining the type of carbonaceous matter and its adsorption behavior. When the content of carbon of high degree of metamorphism is considerable, it is possible to recover platinum group elements and rare elements from this type of ores. The obtained results predetermine the general guidelines for creating new methods and techniques of processing carbonaceous material for integral development of solid minerals in the mining and oilfield areas of Russia.

Jan 1, 2016

By F. Cheuk, E. Krause, V. G. Papangelakis, G. A. Moldoveanu, S. Abendschein

Systematic studies have been conducted at the University of Toronto in order to evaluate lanthanide extraction from clay minerals from different geographical regions. It was found that rare earth elements (REE) are easily recovered into an aqueous solution via an ion exchange mechanism by leaching with electrolyte solutions containing monovalent cations under ambient conditions. In this study we assessed extraction levels of individual REEs as a function of initial clay composition and leaching conditions. It was found that, in spite of variations in clay origin, all clays consistently reached peak REE extraction levels with fast kinetics. However, terminal extractions were clay-specific. The feasibility of using seawater as a leaching solution and potential synergies with ammonium sulphate as a lixiviant was also investigated. Seawater was found to be inferior to using ammonium sulphate, and provided no observable synergy in leaching performance when used together. The aqueous phase trapped in leached clays was shown to contain significant amounts of REE, as demonstrated in clay washing tests. Techniques to improve the REE concentration in leachate through process variations were investigated. However, it was found that most techniques capable of increasing REE concentrations in the resultant leachate also resulted in reduced REE extraction.

Jan 1, 2014

By D. Gagnon, B. Dubreuil, J. -M. Lalancette, D. Lemieux

"The pilot scale extraction of gold with a brine of sodium chloride and bromide at 30 ºC, in an atmosphere of halogens at atmospheric pressure, leads to gold chloride with 95% gold recovery. The use of dilute hypohalites (1 – 3%) instead of free halogens, which is strong enough to oxidize hypobromite into bromine, simplifies the recycling of halogens by electrolysis. With the recycling of water and brine, the regeneration of hypohalites and with a barren solid that is inert and stable. The Nichromet Extraction technology is a green process where the protection of the environment does not preclude profitability.INTRODUCTIONThe use of chlorides for the extraction of gold predates the discovery of chlorine by Scheele in 1774. In the Plattner chlorination process (Christy, 1888) sodium chloride and copper salt were used to promote gold recovery by amalgamation with variable results. The introduction of the cyanide technology in 1889 has led to a general use of this method for gold recovery. In the last decades, a return to chlorine in extractive processes has been noted (Ferron, Fleming, O’Kane and Dreisinger, 2002), mostly because of environmental pressure for non-cyanide technologies.This paper describes a closed circuit proprietary approach (Lalancette, 2009) developed and piloted by Nichromet Extraction Inc. for the extraction of precious metals with recycled mixed halogens; chlorine and bromine from hypohalites. DESCRIPTION OF THE PROCESSThe attack of gold by halogens can vary significantly. The rate of reaction is substantially higher with bromine (Br2) than with chlorine (Cl2), by a factor of more than five, although the oxidation potential of Cl2 is higher than Br2, as shown in Equation 1a and Equation 1b (Latimer, 1952)."

Jan 1, 2012

By L. Mercier, R. Narendrula, F. Desmarais, L. Amaratunga, A. Aledresse

Thiosulfate is recognized as a promising alternative lixiviant to cyanide for the extraction of gold from ore bodies. Gold thiosulfate ([Au(S2O3)2]2), however, is not well-adsorbed by activated charcoal, making industrial scale use of thiosulfate for gold leaching impractical at present. Because of their high specific surface areas (500-1000 m2g-1) and uniform open-framework nanoporosity (pore channel diameters in the range 3-10 nm), functionalized mesoporous silicas are widely recognized as highly effective materials for the selective, rapid and high capacity uptake of mercury, gold and platinum group ions. In the present work, the efficient and rapid adsorption of gold thiosulfate by thiol-functionalized mesoporous silica (hereafter designated MP-HMS) is demonstrated, whereby the thiol groups in the materials bind with the gold complexes by ligand displacement. The adsorbed gold could be leached out using cyanide, regenerating the adsorbent for further uptake cycles. Functionalized mesoporous silica is thus a promising candidate for the preconcentration of gold from thiosulfate leachate solutions.

Jan 1, 2011

By C. Kim

The integration of three-dimensional (3D) data with infrared thermography has received much attention for its potential use as input data for building energy simulations. Therefore, researchers have proposed methods to integrate 3D data with infrared thermography obtained by different sensors. These studies show the potential of the integration of 3D data and infrared thermography using various systems. However, these studies have ignored property aspects of infrared thermography, such as the low resolution of infrared thermography and external environmental influences. Thus, their proposed methods to integrate 3D data and infrared thermography are inadequate because these problems can affect the resulting building energy simulation. This research proposes a framework that integrates infrared thermography and 3D data while accounting for the resolution and shadow effect of infrared thermography. The proposed framework consists of three steps. In the resolution enhancement step, bi-cubic interpolation is proposed. In thermal data correction from the shadow effect, the shadow area is detected from the visible image, and then the shadow effect is removed from the registered infrared thermography. Finally, enhanced infrared thermography is mapped to the 3D data obtained by a laser scanner. The performance of the proposed framework was evaluated using test images obtained from a building in operation. The experimental results show that the proposed framework provides a 3D thermal model that is useful and accurate in simulating building energy. It is expected that the 3D thermal model can be used for accurate energy simulation of existing buildings. In addition, the proposed framework can be applied in defect detection for buildings. Furthermore, this novel approach enhances infrared thermography using visible images.

Aug 1, 2013

By Z. Zhao, B. Li

"Fractures are the key channels for fluid flow and mass transport in fractured rocks of low/negligible matrix permeability. In single rock fractures, surface roughness causes fluid flow in tortuous paths, and reduces the overall fracture conductance. A number of empirical models have been proposed to relate the reduced hydraulic aperture to the mechanical aperture due to surface roughness, which were revisited and compared. Using two of those relationships between hydraulic apertures and mechanical apertures, we studied the influences of local surface roughness of fractures on fluid flow and solute transport processes at the macroscopic scales of fracture networks. The results show that fracture roughness can affect the flow rates and residence time to varying extent, mainly depending on the empirical models between hydraulic apertures and mechanical apertures. However, fracture roughness has negligible influences on the general patterns of fluid flow (channeling) and solute migration (e.g., travel paths and shape of breakthrough curves). This is because the connectivity of a fracture network is mainly determined by other geometrical parameters (fracture positions, orientations, and lengths), rather than roughness or apertures. INTRODUCTIONIn fractured crystalline rocks of low or negligible matrix permeability, fluid flow and contaminant migration mainly occur within the connected fractures. An understanding of fluid flow and contaminant migration in fractured rocks is a crucial issue in many deep underground projects, e.g. underground repositories for radioactive waste, CO2 sequestration, enhanced geothermal systems, oil and gas production, etc. Rock fractures are typically rough-walled, and surface roughness appears to have first order control on the mechanical and hydraulic behavior of single rock fractures (Boutt et al., 2006).It is well known that the mechanical aperture of a rock fracture is usually larger than its hydraulic aperture, due to fracture surface roughness (Tsang and Witherspoon, 1983). However, for naturally fractured rocks including numerous discontinuities, the effects of this reduced hydraulic aperture in local fractures on macroscopic fluid flow and solute transport in complex fracture systems still remain unclear. Many previous studies assumed identical hydraulic and mechanical apertures in discrete fracture network models for simplicity (Min et al., 2004; Zhao et al., 2011). Therefore, the main objective of this study is to evaluate the influences of local surface roughness of fractures on fluid flow and solute transport processes at the macroscopic scales of fracture networks, by employing the empirical models that relate the hydraulic aperture to the mechanical aperture."

Jan 1, 2015

By G. F. Vander Voort

Over the past twenty years, steelmakers have introduced improved practices for reducing the inclusion content of steels. The success of these practice changes can be monitored in a variety of ways. Chemical analysis of the bulk sulphur and oxygen contents provides a relatively simple means to assess the impact of these changes. However, microscopical test methods are still needed to assess the nature of the inclusions present. Traditional chartbased measurement methods have wide acceptability, and their data are well understood by both purchaser and producer for heat acceptance purposes. However, these methods do have inherent weaknesses which limit their usefulness for quality control, SPC, and database applications. Image analysis-based chart measurements are an improvement over manually generated chart ratings, but the data still do not lend themselves to databases and statistical comparisons. ASTM Committee E-4 on Metallography has developed a stereologicallybased image analysis standard test method, E 1245, which provides the necessary data in a form which is easily databased and analyzed statistically. This paper describes E 1245 and shows how data from different heats and melting practices can be compared statistically to ascertain valid test differences.

Jan 1, 1998

By F. E. P. PEARSON

Sandstone quarried from an island in Lake Winnipeg is barged 130 km to a processing plant at Selkirk on the Red River. The stone is white, poorly consolidated, and consists of rounded quartz grains of high natural purity. It is an important supplier of silica in Western Canada for glass, fiberglass, foundry and other industrial uses.

Jan 1, 1984

By P. Coulombe, J-F. Riverin, A. Gaboury

Cavity cleaning during anode change generates a material that consists of anode cover material and cryolite melts. This material is scooped and placed in bins for transport and further processing and recycling as fresh anode cover material. Typical processing methods in use involve cooling of the hot cavity bath in bins, with or without emission treatment systems, until it is adequate to be processed and grinded to the required particle size distribution. Handling of the hot and cooled cavity bath material can be labour intensive. It also generates significant air emissions which contain particulate and gaseous fluorides. With the advent of the Aluminerie Alouette smelter Phase II expansion, the hot cavity bath tonnage to be processed increased to 700 t/day and maintaining existing practices was not satisfactory. This article presents a novel process implemented at the Alouette smelter where cavity bath is processed as a hot material directly from the potlines ( 600-800°C range), sized, cooled and then processed in the existing cold bath treatment plant. The system is designed to process 36 t/h, is fully automated and requires limited monitoring from operations. Implementing this new system in a Browrifield environment imposed numerous constraints for space, interfaces with existing operations, commissioning and ramp-up. It is presently operating at approximately 80% availability and is easily meeting the requirements of the potlines. This system has significantly improved the workplace environment in the bath treatment area and reduced the overall particulate and gaseous fluorides emissions at Alouette. Aluminium 2006 45th Annual Conference of Metallurgists ofCIM Montreal, Quebec, Canada Edited by

Jan 1, 2006

By R. A. Hemstock

AREAS in which the surface de-posits consist of organic material -known in some parts of Canada as muskeg and in Europe, more generally, as peat lands -have long been some of the least rewarding of lands of the north temperature zone. Even in such countries as Great Britain, Holland, and Denmark where a good deal of incentive exists to develop all available land, the use of peat land has been negligible except as a source of fuel. Only recently have efforts shown promise in re-claiming these lands for farming or for forestry. Russia has large areas of peat and use is made of it for power generation. The Russian people have also ?developed a variety of machines for handling peat, which would indicate that they are well ahead of the Wes tern World in their technical and physical ability to solve some of the problems. Certainly in Canada, where there are over 500,000 square miles of muskeg, the economic aspects of this problem are important. This is especially true in considering the shifting emphasis to northern development. Not only is muskeg in possession of great stretches of terrain, thereby rendering it useless for agricultural purposes, but it is apparently moving into forested areas and reducing their productivity. In addition, it lies as a great barrier to movement in the search for and development of such natural resources as petroleum, natural gas and minerals generally. This situation has long been recognized in Canada but only recently have organized efforts been made to study the problems and search out ways of overcoming them.

Jan 1, 1958

By A. Poor Zaeif Doost

With columns being installed in rougher section at Miduk Copper Complex, the rougher feed mainly reports to rougher-scavenger cells. To evaluate the efficiency of regrinding circuit, we conducted flotation experiments on samples of the feed and the products of the regrinding circuit. The grade difference of these products at 85% recovery was considered as the efficiency index. Results show that, with weight recovery of the rougher-scavengers the efficiency of the circuit increases. Exclusion of the rougher-scavenger concentrate from the feed to the regrinding circuit, resulted in an increase in the efficiency index from 10.12 to 17.6%.

Jan 1, 2012

By J. Arzúa, L. R. Alejano, P. Rodríguez

"After six years of successful excavation with a support pattern, some roof failures have happened in a room-and-pillar underground mine excavated in a stratified rock mass. In this paper the authors give explanation to the failure mechanisms and redesign the support in order to solve the recent problems of roof collapse.The mine magnesite bed is approximately 14 m thick, and runs in the E-W direction with an average dip of 18º. Due to mine constraints and the inexpensiveness of the ore, the excavation is performed in the mineral itself, avoiding the need for mining dumps and waste excavation. Rooms and drifts are oriented in the mineral bed to form an angle of 19º to the direction of the strata, reducing the roadway gradients to less than 10%. Rooms are 11 m wide and pillars are 7 m wide. They are designed to leave a 1 meter thick magnesite bed in the roof of the rooms to act as a supporting beam. More often than not there is a layer of very poor quality marly shale up to 1 m thick resting on this magnesite beam. Overlying the poor quality marly shale there is a better quality, self-supporting sandy shale.First, a characterization of the involved rock masses (magnesite, marly shale and sandy shale) is performed, collecting the geotechnical data from previous studies and performing new in situ geotechnical surveys to check the soundness of the previous data. A distinction is made between different quality zones inside the mine by means of the RMR classification, associated to the occurrence of faults.Back-analysis of some of the failed rooms and data from exploration boreholes were used to determine the failure mechanisms (associated to Voussoir type failure or occurrence of sub-horizontal joints crossing the magnesite beam). Based on an understanding of these mechanisms, the method used to design the support and to analyse the stability of the different possible thicknesses of the magnesite beams of the rooms and drifts of the mine were improved.Numerical models of the most relevant conditions found in the mine were performed in order to better understand the behaviour of the roofs and to simulate the supporting solution obtained in the previous analyses.The most relevant conclusions with regard to the main elements causing the instability of the roof include the appearance of sub-horizontal discontinuities crossing the magnesite bed, which causes total instability of the roof and usually leads to collapse; excessive thinness of the magnesite beam in the problematic rooms; and the relaxation of the deepest (around 270 m in depth) zone of the mine because of existing faults."

Jan 1, 2015

By J. Zachwieja

As part of a general review on study of surfactant blinding agents to improve gold recovery during cyanide leaching of carbonaceous gold ores, processes of CIL and RIL leaching using surfactants were investigated. When refractory ores were treated by surfactants, CIL and RIL leaching processes yielded significant improvement on gold recovery. This paper will discuss and compare the laboratory results from two different leaching processes on preg-robbing ores, as well as, illustrate the difference of potential fouling of the blinding agents on activated carbon and resins.

Jan 1, 2015

By F. Rivard, M. G. Drouet, W. S. Ruff, P. Carabin

"In both the hot rotary-salt-furnace (RSF) treatment of aluminum dross and the cold ball-millsieving (BMS) treatment of zinc dross, enormous amounts of energy and recoverable metal are wasted and large amounts of greenhouse gas are produced. Such wastes and the environment pollution could be avoided by using the DROSRITE PLUS™ technology. Economic and GHG production comparisons between the presently used industrial treatment processes and DROSRITE PLUS™, supported by over one hundred tests conducted in Canada, the US and Europe, are presented. The savings, with DROSRITE PLUS™, would be about $191 and $418 per MT of aluminum and zinc dross, respectively.INTRODUCTIONDross is a material, which forms on the surface of molten non-ferrous metal, such as aluminum or zinc, during melting, metal holding and handling operations when the molten metal is in contact with a reactive atmosphere. Dross normally consists of metal oxides entraining a considerable quantity of molten free (unreacted) metal, and for economic reasons it is desirable to extract the free metal before discarding the residue. In the case of aluminum dross, recovery of the metal is usually carried out by treating the dross in a furnace at a high temperature (Peterson et al., 2002). By contrast, cold zinc dross is crushed in a ball mill followed by sieving to separate the coarse metal portion from the fine oxide residue.The conventional aluminum dross treatment process, using gas or oil-heated rotary salt furnaces (RSF), is thermally inefficient and environmentally unacceptable because of the salt slag and CO2 produced from the combustion of fossil fuels. In the past several years, a number of salt-free processes have been developed and some of these have found limited commercial use (Gripenberg et al., 1994; Lavoie et al., 1990). In all these dross treatment processes, heating of the cold dross in a rotary furnace requires an external energy input that varies between 375 and 2,500 kWh per (metric) tonne of dross. Molten metal separated during processing of the heated dross is tapped, and the remaining solid residue is discharged from the furnace."

Jan 1, 2012

By N. H. J. Freire, D. Majuste

In this paper, the effects of some organic compounds on the current efficiency, cell voltage and specific energy consumption during nickel electrowinning, and on the deposit features (morphology, crystallographic orientation and nanohardness) were described. The organics tested here (extractant, diluent, flocculant, lubricating oil and acid mist suppressant) are currently used in industrial plants. The results indicated that only the flocculant and acid mist suppressant exhibit relevant negative impacts on the current efficiency and energy consumption. The current efficiency dropped from 93.6 % (organic-free solutions) to 86.0 % and to 92.8% in electrolytes containing 100 mg.L-1 of acid mist suppressant and flocculant, respectively. At this concentration, their addition to the electrolyte led to increases of the specific energy consumption in the order of 18 % (acid mist supressant) and 2 % (flocculant). Cyclic voltammetry showed that Ni nucleation occurs at more negative potentials at 50 and 100 mg.L-1 of these organics in the electrolyte, thus indicating an inhibition of the deposition process. The deposit quality decreased at the higher concentration of all organics, when more hydrogen pitting was observed. The acid mist suppressant caused delamination of the Ni deposit at 50 and 100 mg.L-1. The addition of 100 mg.L-1 of flocculant and acid mist suppressant to the electrolyte increased the nanohardness of the deposit around 31 and 72%, respectively. The increase in Ni deposit hardness may lead to a decrease in the material ductility, thereby affecting the stripping and cutting of Ni sheets. Our findings may be helpful since strong adverse effect of some organics that may be present in the electrolyte were identified, thus the industry can control and optimize the organic´s dosage in the corresponding operations.

Jan 1, 2016

By M. Pawlik, E. Arinaitwe, V. Ferrera

A series of flocculation tests were performed on dilute quartz suspensions with the use of five polyacrylamide-based flocculants of similar molecular weights but of different degrees of anionicity. The tests were performed as a function of ionic strength and pH. The macromolecular conformation of flocculants in solution was assessed through intrinsic viscosity measurements under the same physicochemical conditions as those of the flocculation tests. It was generally found that the flocculating efficiency of the polyacrylamides correlated with their ability to coil or stretch in solution. Polyacrylamides with the degrees of anionicity on the order of 10-18% showed the highest flocculating efficiency in terms of the settling rates of the flocculated solids and the residual turbidity of the resulting supernatant. At the same time, these most effective flocculants were also found to exhibit the greatest tendency to coil and stretch in solution. This result suggests that the flocculating power of a flocculant is determined not only by its ability to adsorb onto (and bridge) fine particles but also on its ability to conform to the size of the resulting floes.

Jan 1, 2009

By BARRY BANNATYNE

Non-swelling bentonite has been quarried in Manitoba by Pembina Mountain Clays Limited since 1941. It occurs in several thin layers near the base of the Pembina Member of the Upper Cretaceous Vermilion River Formation, and is quarried from the narrow outcrop belt along the slope of the Manitoba Escarpment. It is marketed both as natural and activated bentonite for a variety of specialized uses. Percolation of acidic water through bentonite has produced a naturally activated bentonite with good absorbent properties; these properties are enhanced by treatment with sulphuric acid to produce an activated bentonitefor decolourizing petroleum and vegetable oil.

Jan 1, 1984