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By G. Zeng

Although the solubility of oxygen in zinc electrolyte is less than 9 mg/L, the effect on deposit stability and zinc-dust consumption can be significant. Sodium sulfite is used to deoxygenate the electrolyte. The effect of the sodium-sulfite concentration on cobalt removal is investigated. The results show the reduction of sulfite to elemental sulfur that adhered to the zinc dust surface forming a passivating layer, and small amounts of sodium sulfite have no effect on cobalt removal. The optimum amount of sodium sulfite is 100 mg/L. It is an important consideration in purification circuits to use sodium sulfite as an additive to cobalt cementation.

Jan 1, 2005

By L. Bichler

Utilizing thermal analysis techniques, pioneering research into the solidification mechanism of a popular magnesium alloy AZ91E cast by the Lost Foam Casting (LFC) process was carried out, Foam characteristics, section thickness and application of vacuum were seen to have profound effect on the cooling rate, thermal gradients and casting temperature profiles.

Jan 1, 2005

By Francis Chartrand

The Kwyjibo deposit is an iron oxide Cu-REE-F-Mo-Au mineralization of Mesoproterozoic age located in the Grenville Province approximately 120 km NE of Sept-Îles, Quebec (Figure 1). Occurring along the SE margin of the Canatiche granitic complex, the deposit is composed of several polymetallic showings that are related to different textural facies of magnetite. The mineralization process at Kwyjibo is complex, and is divided into Early Granitophile, Magnetite, Main Polymetallic and Specular Hematite stages (Cayer et al., submitted for publication). The Main Polymetallic stage, comprising chalcopyrite, pyrite, fluorite, molybdenite and REE-bearing minerals, is superimposed on pre-existing magnetiterich rocks. Discovered by SOQUEM Inc. in 1993, the Kwyjibo deposit shares many characteristics with other hydrothermal polymetallic iron oxide deposits around the world. Foose and McLelland (1995) suggested that this class of mineralization could occur in the Grenville Province. However, only a few polymetallic occurrences are known to be associated with low-Ti iron oxide deposits in the Grenville. Kwyjibo is one of the most significant examples of a polymetallic iron oxide deposit to have been found in the Grenville Province to-date.

May 1, 2003

By Ammar Henchiri, Godfrey McDonald

"Breakwater Tunisia S.A.’s Bougrine mine is located in a semi-arid region of Tunisia characterized with Triassic salt domes. Due to extensive agricultural land-use in the mine area, a zero-discharge tailings facility design and high water recycling rates to the concentrator were chosen to minimize the environmental impact to the surrounding area. The process water supply has an accumulation of naturally occurring salts due to high evaporation rates and the need to recycle 70% of the process water. The elevated salt content of the process water had an adverse effect on the efficiency of the flotation reagents, which led to the production of lower quality zinc concentrate.The impact of the water salinity on the zinc concentrate quality was documented by extensive laboratory testing. A feasibility study was prepared and a decision was made to install a reverse osmosis plant for desalination of the process water. A plant was constructed during 2000 which currently supplies up to 85 m3/hr of de-mineralized water, equal to approximately 45% of the total process water requirement. The salinity of the process water decreased from about ten to twelve grams per litre before installation to less than three grams per litre. Together with minor modifications to the concentrator circuit, Breakwater Tunisia has increased the zinc concentrate grade from 50% zinc to 55% zinc without compromising the zinc recovery rate of approximately 84%.This paper discusses the successful installation of a reverse osmosis desalination plant that allowed Breakwater Tunisia to improve the grade of the Bougrine mine zinc concentrate and thus increase the net smelter return.INTRODUCTIONBreakwater Resources Ltd., through a wholly owned subsidiary, Breakwater Tunisia S.A., acquired the Bougrine underground mine and related assets in September 1997. During the winter of 1997/1998, the company rehabilitated the mining equipment, modified the concentrator circuit, developed a new mine ventilation system and prepared a new mining production program. The mine was reopened on May 2, 1998 and was in commercial production as of June 1, 1998."

Jan 1, 2003

By Darryel Boucher, Thomas W. Leadbeater, Raymond Langlois, Joshua Sovechles, McGill University, Zhoutong Deng

"Spiral concentrators are used to upgrade ore based on the density difference between their component minerals. This simple flowing film gravity separator is of interest for the processing of large amounts of material, as found in the iron ore industry. Addition of wash water at different points on the trough of the spiral affects the grade and recovery of the valuable concentrate by affecting the flow of particles within the thin slurry film. This paper shows how radiolabelled hematite (-355+300 µm) and quartz (–1,180+1,000 µm) tracers were used to determine the particles’ behaviour within the slurry film with and without the addition of wash water. The results presented provide a detailed particle flow pattern around a wash water addition point and its effect on the trajectory and velocity of the particles. This information is of interest in building knowledge about spiral wash water injection parameters such as injection location, direction, flow rate and nozzle orifice type (affecting jet shape and velocity).INTRODUCTIONSpiral concentrators are density based separation devices. They are extensively used in the upgrading of iron ore, fine coal and minerals sands (sources of ilmenite, rutile, zircon and monazite) (Wills & Finch, 2016). A spiral unit is composed of a channel of specific profile formed as a helix of 3 to 7 turns around a central structural post. The feed pulp is composed of 15 to 45% solids with particle size from 75 µm to 3000 µm (Wills & Finch, 2016). Throughput of a single spiraling trough can be up to 8 ton per hour and multiple trough unit (up to four trough) can process up to 30 ton per hour for a footprint of around 0.7 m2 (Palmers & Vadeikis, 2010). They are low cost concentrators considering manufacturing of their trough via polymer reverse molding. The energy intensity of a spiral plan is notably small considering the throughput and is mostly related to pulp pumping and final concentrate dewatering."

Jan 1, 2016

The rate of liquid copper deoxidation during top blowing of reducing flames has been investigated using a high capacity thermogravimetric unit at 1200 °C. For 1 kg copper samples, it was observed that the rate of deoxidation was proportional to the flow rate of the reducing reagent (H2 or CO). Under similar experimental conditions, it was found that H2 is more effective than CO even though both have similar thermodynamic potential to deoxidize liquid copper. The rate of deoxidation of liquid copper with reducing 0 2/CH4 flames was measured for 0 2/CH4 molar ratios of 1.5 to 2. The deoxidation rate depends on the 0 2/CH4 ratio and decreases as it approaches the stoichiometric ratio (02/CH4 = 2). Estimation of the rate of deoxidation of liquid copper with top blowing flames based on the thermodynamic composition ofH2 and CO in the product gases, agrees well with measured values.

Jan 1, 2007

By A. R. Laplante

Gold recovery early in the flowsheet, typically from the primary grinding circuit, has seen significant advances in the past three years. Some of the advances achieved under the auspices of the AMIRA P420B Gold Processing Technology project are reviewed. The areas covered are gravity-recoverable gold (GRG) characterization, GRG behaviour in classification, gravity recovery simulation and the link between gravity recovery and cyanidation.

Jan 1, 2005

By 000-900-009-492

The flotation has been and is still the most widely used mineral concentration method. Because of its complexity, the flotation process required the development of robust control strategies which was facilitated by the introduction of on-line sensing instruments such as x-ray fluorescence (XRF) on stream analyzer (OSA), gamma density gauges and electromagnetic flowmeters. The interest in developing control strategies has persisted because the benefits to be gained in terms of improved metallurgical performance are substantial. As the flotation control becomes more and more difficult due to the emergence of low grade and complex ore cases, other control strategies have to be introduced. Froth based control is one of the emerging useful control strategy This paper will focus on the state of the art in the on-line froth characterization as obtained by numerical image analysis. The technology of machine vision provides a novel solution to several of the problems encountered in conventional flotation systems for monitoring and control, and constitutes a powerful tool for the investigation and interpretation of the effect of various flotation parameters as driven for the froth phases. Copyright @2001CIM

May 1, 2001

By R. Q. Honaker

It has been shown that naturally hydrophobic carbonaceous materials such as coal and graphite can be selectively coagulated and separated from hydrophilic impurities without using oily agglomerants, flocculants or electrolytes. The coagulation occurs at C-potentials significantly higher than those predicted by the classical DLVO theory, suggesting that it is driven by the hydrophobic interaction. In the present work, the energy barriers for the coagulation of a hydrophobic coal sample have been calculated using the extended DLVO theory which incorporates the hydrophobic interaction energy in addition to the dispersion and the electrostatic energies. For the coagulation of minerals present in the coal, the classical DLVO theory has been used for the energy barrier calculation. The results of these calculations provide an excellent correlation with the results of a series of Selective Hydrophobic Coagulation (SHC) tests conducted with run-of-mine coal and graphite samples.

Jan 1, 2004

By W. A. Lang

"IntroductionCARBONIZATION, gasification, and chemical utilization of coal are interrelated topics, which makes it difficult to review one without indicating its connection with the others. Hence, in Progress in Coal Technology, Series No. 5: Carbonization, reference was made to gaseous products recovered in the carbonization of coal, and .to a number of chemicals made from the tars, light oils, and ammoniacal liquors which are by-products of coal carbonization.In this, the sixth paper in the review series, prime consideration will be given to the complete gasification of coal to give a fuel for domestic industrial, or power purposes and a synthesis gas suitable for the manufacture of gasoline, Diesel oil, and chemicals. The hydrogenation of coal, an alternative source of liquid fuels and of chemicals, will be reviewed, as will be a number of processes for •the recovery of chemical products from coal by extraction and chemical treatment."

Jan 1, 1952

By E. Dernedde

A few studies have suggested that the rate of adsorption of hydrogen fluoride on smelter grade alumina is determined by kinetic factors. However, no performance equation for dry scrubbers has appeared in the literature so far. Experimental data from a pilot dry scrubber with co-current flow were compared with results of kinetic models of adsorption, film diffusion and pore diffusion. The pore diffusion model was deemed the most appropriate. It was transformed into a performance equation for steady-state operations of dry scrubbers by the inclusion of the alumina recirculation. Operating results of industrial dry scrubbers with co-current flow were successfully evaluated by means of the performance equation. The average fluoride content of the alumina was also estimated by using the pore diffusion model.

Jan 1, 2011

By William DeWit

When rivers are contaminated from industrial operations, as often occurs near repositories of spent mine tailings, decision-support tools can be critically important in evaluating the effectiveness of various engineering impact-management measures. Even where data describing river flows and quality are sparse, simple mixing-zone models can be constructed that can contribute greatly to understanding how impact-management measures can differentially affect existing river-chemistry regimes. There can be circumstances where accumulated surface waters near contaminated land can bear contaminant loadings that could be acceptable to river regimes if there were methods available to evaluate optional discharge rates and to predict post-mixing consequences on river chemistry. Nomographs can be constructed to evaluate discharge regimes that appear capable of releasing contaminated accumulated pond water without compromising water quality in a nearby river. River-mixing zone models also contribute to predicting rates of acceptable discharge and release to the receiving environment.

May 1, 2011

By Yongqiang Liu

Background For refractory gold ores with high carbonate contents ! Acid pressure oxidation ! High acid consumption (if low sulfur content) ! Low oxidation efficiency due to CO2 in autoclave ! Problems with slimy precipitates (gypsum, etc.) ! Alkaline pressure oxidation ! Difficulty in fixing arsenic ! Low gold dissolution due to iron hydroxides/oxides coating ! High reagent costs Summary ! Carbonate and sulfide minerals had similar floatability across the pH range tested (5 - 12) using sodium oleate as a collector; ! Thioglycollic acid or citric acid depressed the flotation of pyrite but could not depress chalcopyrite when used alone; ! Combination of thioglycollic acid and citric acid had a much stronger depressive effect, and the mixture depressed chalcopyrite as well as pyrite between pH 8 and 11 without affecting the flotation of calcite and dolomite; ! Calcite could be separated from chalcopyrite and pyrite; dolomite could be separated from pyrite but not from chalcopyrite under the tested conditions.

Apr 1, 2005

By H. Ito, T. Takasu

Effects of a mechnochemical treatment to oxide Ni ores have been investigated to enhance the extractive ratio of Ni from them in acid leaching process. High intensity grinding by a planetary boll mill showed strong effect to enhance the extractive ratio of Ni, for example , 10% of extractive ratio of Ni in sulfuric acid leaching(0.05mo1/1,at room temperature) increased to more than 90% with 60min. of planetary boll milling. Effects of additives(sulfur and some oxidants) on the mechnochemical treatment have also studied. Sulfur showed almost no effect to enhance the total Ni extractive ratio but increases the selectivity of Ni extraction. More than a half of Ni could be extracted by water when Ni ore was grinded at addition of Na2S207 in the milling treatment. Some effects of mechnocemical treatments to Ni ore are summarized in this paper.

Jan 1, 2005

By D. Bois, P. Keating, J. Lemieux, M. A. Vallée, M. Allard, R. S. Smith, L. Z. Cheng, M. Chouteau, D. K. Fountain

"Abstract -A test survey using the MEGATEMII airborne electromagnetic system was flown over the Iso and New Insco massive sulfide orebodies in the Rouyn-Noranda mining camp, Canada. The results were compared with data from historical systems (INPUT, DIGHEM) used to discover the deposits. The historical data show that the two deposits have comparable conductances. However, the modern MEGATEMII system reveals that the New Insco deposit has a much slower decay than the Iso deposit, and it is, therefore, interpreted to be more conductive. The MEGATEMII anomaly maps provide estimates of the location, depth, dip, and strike of the two deposits, information that was not available from the historical anomaly maps. The signal-to-noise ratio of the MEGATEMII data is greater than the historical data, yielding more sharply defined anomalies. The investigations also included a comparison between 90 Hz and 30 Hz MEGATEMII data. The 90 Hz data were found to be useful for mapping the less conductive parts of the Iso body, whereas the 30 Hz data demonstrated that the New Insco body is more conductive. Analysis of height attenuation data over the Iso body indicates that the body could be seen by the MEGATEMII system if it were buried an additional 230 m deeper (in highly resistive material). On the other hand, the INPUT system would detect the Iso body only if it were buried no deeper than an additional 60 m. Tests with the transmitter turned off showed that, for this flight, the MEGATEMII system noise levels on the processed data are about 300 pT/s. Sommaire - Dans le cadre d’un projet de recherche, un ensemble de levés d’essais électromagnétiques aéroportés employant le système de MEGATEMII a été effectué au dessus des dépôts d’Iso et de New Insco, Rouyn-Noranda, Canada. Les données ont été comparées avec les réponses des systèmes qui ont découvert ces deux dépôts (INPUT et DIGHEM). Les données antérieures montrent que le dépôt d’Iso a une conductance comparable à celle de New Insco. Cependant, les données de MEGATEMII démontrent que le dépôt de New Insco a une haute valeur de la constante de décroissance, ce qui reflète une plus forte conductivité. La carte d’anomalies de MEGATEMII indique la localisation, la profondeur, le pendage et l’orientation des deux dépôts, ce que la carte d’anomalies antérieure ne montrait pas. Le rapport de signal à bruit de MEGATEMII est plus grand que celui des données de INPUT et de DIGHEM; de plus, les pics sont mieux définis. Les tests ont également permis une comparaison entre les fréquences de base de 90 Hz et de 30 Hz. Les données de 90 Hz se sont montrées utiles pour cartographier la partie du dépôt Iso dont la conductivité est la plus faible, tandis que les données de 30 Hz montrent clairement que le dépôt de New Insco est plus conducteur. Les analyses de l’atténuation du signal avec la hauteur ont indiqué que le dépôt d’Iso pourrait être détecté par le système MEGATEMII s’il était enfoui à 230 m sous la surface (dans un milieu hautement résistant). D’autre part, le système INPUT pourrait seulement détecter le dépôt d’Iso s’l était situé à 60 m de profondeur. Les tests avec l’émetteur fermé démontrent que le niveau de bruit est des l’ordre de ±300 pT/s."

Jan 1, 2006

By P. Gautier

Current feedstock in the aluminum hot forging processes can be used in the cast or extruded forms. The microstructural variation between as-cast and extruded materials could result in different mechanical properties and corrosion resistance for hot-forged products. Corrosion performances were examined for forged parts produced by two AA6082 feedstocks at different conditions using the following corrosion tests: open circuit potential, anodic polarization, salt spray exposure and corrosion fatigue. With the help of optical and scanning electron microscopes, metallographical investigations were carried out on cast-forged and extruded-forged materials before and after corrosion. The corrosion behavior of both materials was compared in both as-forged and aged tempers. Results show that there is no significant difference in the corrosion performance for final cast-forged and extruded-forged products.

Jan 1, 2011

By Wencheng Gao

An attractive way to beneficiate magnesium chloride and aluminum chloride is to prepare Mg-Al spinel, an excellent refractory material. Mg4Al2(OH)14?3H2O, the precursor of spinel, can be prepared using a co-precipitate method from aqueous MgCl2-AlCl3 solutions. The co-precipitation process of magnesium-aluminum from acidified chloride solutions by using NaOH or NH4OH as base neutralization agent was studied. Co-precipitation was conducted from different mixed solutions ? at initial CAl=0.0625M and Mg/Al molar ratio from 0.5 to 10, the temperature range from 30 to 90 °C. The effect of other parameters, including base type, method of base addition, base addition rate, aging time, background electrolyte and concentration were also investigated. The co-precipitation process was monitored by potentionmetric(pH) measurements. The experimental pH curves were characterized by two platforms separated by a steep jump in pH at Mg/Al molar ratio 0.5~6. The first platform was centered at about a pH of 3.8 and the pH of second platform was varied with different conditions. When the Mg/Al molar ratio was up to 6~10, the first platform in pH was almost disappeared. Furthermore, the shapes of pH curves were also affected by base type, base addition rate and method of base addition. Experimental results showed that the first platform in pH was connected with Al precipitation, and the second platform was involved with Mg. The final co-precipitates were characterized by XRD, TGA-DTA, particle size analysis, SEM and TEM. We found both Mg/Al molar ratio and temperature proved to be the key parameters controlling the formation of Mg4Al2(OH)14?3H2O phase. At solution Mg/Al ratio=0.5~4, the main precipitate phase was Bayerite (Al(OH)3) admixed with Mg4Al2(OH)14?3H2O; at Mg/Al ratio=4~6, the main phase was Mg4Al2(OH)14?3H2O admixed with some Mg(OH)2; while from Mg/Al ratio=6~10, the systems were mixtures of Mg(OH)2 and Mg4Al2(OH)14?3H2O.

Oct 1, 2011

By M. Mahfoud

The effect of grain refinement on the tensile and fatigue crack propagation behavior of sand cast magnesium alloy AM60B has been investigated in the present study, C2Cl6 in the amount of 0,3% was used to grain refine the melt, The fracture toughness tests were conducted in laboratory air at room temperature (25°C) using a sine-wave cyclic frequency of 20Hz and a load ratio of R = 0,1, The response in the Paris's regime and the critical stress range were determined, Preliminary findings have shown that C2Cl6 has a significant effect on both the tensile properties and fatigue crack propagation of the alloy tested, Grain refinement increased both the yield and ultimate tensile strength by more than 46%, and decreased the crack growth rate from 2,7 to 1,4 MPa Vm , However, the grain size seems to have a smaller effect on threshold stress intensity factor range. The fracture surfaces of specimens were examined optically and under the scanning electron microscope (SEM) to determine the relationship between grain size and fatigue properties.

Jan 1, 2005

By H. Arima, Y. Kudo

In general, the iron content of zinc leach residue produced by sulphuric acid leaching from calcine is disposed as jarosite or goethite into a tailing dam. More recently, these iron residues have been treated pyrometallurgically to avoid waste disposal. The Iijima refinery selected a different zinc leach residue treatment process for iron control when it was established in 1971. The Iijima refinery is the only plant in the world that has processed a zinc leach residue by the combination of SO2 pressure leaching and O2 pressure hematite precipitation. The process enhances zinc recovery and recovers gold, silver, copper, lead and rare metals in saleable by-products. This paper focuses on the two stages of autoclave application in the zinc leach residue treatment process. The detailed flowsheet and recent advancements to improve the quality of by-products are discussed.

Jan 1, 2004

By H. J. McQueen

Large-scale industrial production of pipe began with longitudinal hot pressure welding of wrought iron by passage of skelp (narrow strip with beveled edges) through a die or bell that curled it about a longitudinal axis until the edges were forced together. Such small to medium tubes could be reduced by rolling or drawing; with threaded connections, they were excellent for distribution of clean water and of illuminating gas for street, home and industrial lighting. Although steel lacks the fluxing slag for pressure welding it has hot strength similar to iron; hot-pressure bell welding was advantageously transferred to steel in long coiled strip with 50% higher cold strength. For pipe without weld-line defects, hot cupping followed by Pilger mill rolling produced tubing that revolutionized bicycle quality and high-pressure service for boilers and chemical processing. Mannesman hot rotary piercing produced long thick walled tube that permitted reduction or expansion by rolling to provide pipe sections up to 60 cm diameter and 12 m long. During 1910 - 1940, oil and gas pipeline technologies, notably welding evolved markedly as they proliferated in the United States, in response to far-flung petroleum fields, expanding industry consumption and the automobile revolution. In the Second World War combat pipelines were laid rapidly, such as: the Canol line through the Yukon to Alaska, and fuel supply lines across the channel and through liberated France. Perfection of welding techniques for both longitudinal and spiral weld large diameter pipe in combination with controlled-rolling of micro-alloyed steels made possible reliable Arctic pipelines. The development of pipe production and utilization in Canada is recounted. The fabrication techniques and metallurgical controls are explained.

Jan 1, 2005