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By D. A. Livingstone

"INTRODUCTORY REMARKS BY PANEL CHAIRMAN - D. A. LIVINGSTONEThe mining industry has progressed significantly from the dusty mines and mills of decades past to the modern processing complexes of today, and improved technology has made great strides in eliminating debilitating lung discuss. More recently, the public's environmental awareness is also working to enforce more stringent regulations and controls in tl1e matter of dust in working places.There are numerous excellent texts and handbooks outlining the principles of collection of dust produced in the various unit operations entailed in the crushing, screening and the transport of ore. However, it is painfully obvious that dust emanating from belt return idlers and scrapers, take-up pulleys, skirting, larger and deeper chutes, clean-up operations, etc., which I choose to refer to as fugitive dust, presents some seemingly unmanageable difficulties, or at least difficulties inordinately costly to correct. Possibly static electricity is adding to the difficulties. In my view, these problems are magnified in many of our B. C. operations where ore from open pit mines in cold climates is frequently crushed in unheated buildings, thereby precluding the simple and obvious use of water sprays for dust suppression.It is hoped that the presentations and discussion which follow will emphasize some of these unusual problerr.s and suggest corrective measures, either tried or planned."

Jan 1, 1976

By George P. Demopoulos

In a departure from the traditional domain of hydrometallurgical extraction processes we consider new R&D opportunities for innovative application of solution processing into the advanced green energy and clean technology fields. It would not be an exaggeration if we state that protection of the environment via advancement of clean technologies on the one hand, and harvesting and utilizing renewable energy in a sustainable and cost-effective way on the other hand are clearly among the top pressing global priorities. When hydrometallurgy is approached on the basis of its aqueous chemistry and reactive processing fundamentals, it can indeed provide a highly fertile ground for innovation outside the "box". In this context therefore we will present highlights from our recent research that is directed towards the development of new generation HCl recycling, environmental, and solar energy conversion/storage technologies. In all systems the research is approached via the innovative integration of aqueous process engineering and material chemistry principles. The presentation will include discussion of (i) the development of crystallization-based HCl regeneration technologies; (ii) the supersaturation-controlled production and encapsulation of scorodite that was recently commercialized; (iii) the aqueous synthesis of nano-TiO2 and its electrophoretic deposition into solar cell electrodes; and (iv) the hydrothermal synthesis of nanostructured lithium titanate and lithium iron phosphate materials to make lithium-ion batteries destined for electric cars.

Jan 1, 2014

By Alex MacEachern

Air is the gaseous substance that envelopes the earth and forms its atmosphere. It is remarkable in the constancy of its composition; for while this is being continually changed as the result of the respiration of men and animals, and by addition of gases arising from organic changes and the products of combustion, it is ever being brought back to normal and the proper balance restored by the processes of plant and vegetable life. Nature sees to it that the air in which we live and breathe is kept purified. This does not apply to the air in a coal mine, where there are no natural forces to change and make use of the different gases formed or evolved, and where mechanical ventilation is the only effective means of keeping the air pure. The atmosphere consists of oxygen and nitrogen, not in the combined state but merely mixed. By volume, the composition is: oxygen, 21 percent, nitrogen, 79 percent, there being included with the latter small quantities of such substances as water vapour, carbon dioxide, nitric acid, ammonia, ozone, argon, neon, and organic gases. Of the two principal gases which form air, oxygen alone supports life. When air is inhaled into the lungs the oxygen is absorbed by the blood, which carries it through the body to nourish and energize it. Exhaled air consists of water vapour and about 4 per cent carbon dioxide, with from 16 1/2 to 17 per cent oxygen and 79 per cent nitrogen; the oxygen alone having been drawn on to any considerable extent.

Jan 1, 1930

By Y. X. Li, L. R. Xiao, S. Gong, S. S. He

Porous copper and porous copper based alloys with controllable pore structure have been manufactured successfully by sintering evaporation process. This process consisted of mixing copper or copper based alloys with NaCl powders, hot pressing and final high-temperature sintering to evaporate the filler material of NaCl powders. NaCl was eliminated completely during vacuum sintering, and strong metallurgical bonding in the walls was achieved. The pores’ structural parameter (pore size, shape, and direction) and porosity can be controlled effectively. These porous copper and porous copper based alloys with controllable pore structure have great potential in many fields. Including heat dissipating materials, heat absorbing materials, chemical catalyst carriers, electromagnetic shielding materials, filtering materials, damping materials, silencing materials, battery electrode materials. INTRODUCTION The development of porous materials began in the 1960s. The research of activated carbon with high specific surface area made porous materials enter the stage of material research (Belyakov et al., 2008; Ferey et al., 2008). With the rapid development of science and technology, porous materials play an important role in material research, and gradually become an indispensable part of the material research field (Wu et al., 2012). The research of porous materials has gradually extended to metal, ceramics, plastics and glass and other fields. It has been successfully applied in many fields, such as functional materials, industrial production, aviation, medical materials, biochemistry and electronics, which fully shows that porous materials have considerable development prospects. Porous silicon, plastic porous materials and glass porous materials are the most widely used in the field of non-metallic porous materials (Capelle et al., 2012). Compared with non-metallic porous materials, metal porous materials have developed rapidly in the late 1980s and become new materials with good mechanical properties and excellent physical properties. Porous metal materials have many advantages, such as large specific surface, small specific gravity, good silencing effect, high stiffness, high electromagnetic shielding performance, good shock absorption performance, etc (Li et al., 1999; Ferey et al., 2008). Among its many applications, metal porous materials can be used as both functional materials and structural materials. In some cases, metal porous materials have dual functions and structures. It is a multi-purpose engineering material with excellent performance. At present, porous copper, porous aluminium and porous nickel are the most concerned materials (Chen et al., 2002; Yang et al., 2017; Liu et al., 2018). The preparation methods of porous copper and copper-based alloys mainly include self-propagating high temperature synthesis (SHS), capsule-free hot isostatic pressing (CF-HIP), spark plasma sintering (SPS) (Kvanin et al., 2008; Takahashi et al., 2008; Zhang et al., 2014). However, these methods can not accurately control pore structure parameters (including pore size, shape, orientation, distribution, etc.). In porous materials, pore structure plays an important role in the overall performance of materials. In order to control pore structure parameters accurately and optimize material performance, it is necessary to explore and develop new preparation technology. In this paper, the sintering evaporation process (SEP) was introduced for the preparation of porous copper and copper-based alloys. The core process of the preparation method is hot pressing and evaporative desalination. Hot pressing can make the pore orientation consistent. Evaporative desalination can ensure the complete removal of NaCl in the form of vapor in a short time, thus eliminating the corrosion of residual NaCl on the matrix metal (Gong et al., 2011).

Jan 1, 2019

By D. Perednis

Fuel cells with thin samaria-doped ceria (SDC) electrolyte films deposited onto an anode support using spray pyrolysis were fabricated. The SDC films were deposited onto porous NiO-YSZ substrates at deposition temperatures between 400°C and 450°C. The influence of process parameters such as deposition temperature, flow rate, type of salt and salt concentration on the quality of the film was studied. A smooth dense film was successfully deposited using the precursor cerium ammonium nitrate and samarium nitrate dissolved in butyl carbitol (33.3 vol.%), 2-methoxy-l-propanol (33.3 vol.%), and ethanol (33.3 vol.%) solvent mixture. A deposition rate of 125 nm/h was achieved.

Jan 1, 2005

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 R. Bruce Ferguson

"The Kettle River Operation of Echo Bay Minerals Company is located about thirty kilometers north of the town of Republic in northeastern Washington State. In tum, Republic is about a hundred and seventy kilometers north and a little west of the city of Spokane, Washington. It is also about fifty kilometers south of the town of Grand Forks, BC, Canada. At this time it is the only gold mining and milling operation in the State.Tailings are stored in a double lined, zero discharge facility. It became evident in mid 1996 that the rate of free water accumulation in the tailings pond was going to result in the level in the pond reaching its permitted freeboard elevation long before the solids plus pore water capacity was reached.We then embarked on a mission to manage tailings pond water on several fronts: reduce fresh water usage in the process, divert spring seeps and surface runoff and install a system to enhance evaporation.IntroductionThe Republic area is an historic gold mining district. Hecla operated its Republic unit from 1892 until closure in 1994. The Kettle River Operation processing plant is located in the San Poi! river valley at an elevation of just under a thousand meters. The facility consists of a ninety thousand ton ore storage pad as the mines are remote and truck haulage is subject to interruption due to weather and road restrictions, jaw and cone crushing with screening, rod and ball milling to an eighty percent passing size of seventy five microns. This is followed by preaeration with high purity oxygen supplied by a vacuum pressure swing adsorption plant plus lead nitrate addition to achieve passivation of the sulfide mineralization such as chalcopyrite, pyrite and pyrrhotite. Conventional cyanide leaching and carbon in pulp adsorption completes the loop. Tailings are treated with air/S02 to achieve cyanide destruction. Plant capacity is 1,815 tons per day. Our license requires that there be no detectable free cyanide in the tailings pond water and a maximum of forty parts per million weak acid dissociable cyanide. The operation started in 1989 with production from the Overlook Mine located about five kilometers further up the same valley at an elevation of twelve hundred meters, hence the location of the mill. Current mine production comes from Lamefoot in the Curlew Lake valley, about ten kilometers distant, and K2 in the Kettle River valley about fifty kilometers away. Both are at an elevation of about 800 meters. Lamefoot produces 1,360 tons per day and K2, 455. Both are underground operations."

Jan 1, 1998

By M. Tanaka, H. Narita, T. Fuchikami, K. Morisaku, K. Nagao, T. Yoshida, K. Kuroda

The effect of various N-substituents on the performance of amide-containing tertiary amine compounds in the extraction of Rh(III) from HCl solutions was investigated to optimize the structure of these compounds for industrial use. It was found that N-2-ethylhexyl-bis(N-di-2-ethylhexyl-ethylamide)amine and tris(N-di-2-ethylhexyl-ethylamide)amine, which have long, branched alkyl chains, were suitable for Rh extraction, because they were soluble in a practical diluent (80 vol% n-dodecane?20 vol% 2-ethylhexanol) and stable against highly concentrated HCl/Rh solutions, and showed high selectivity for Rh(III) over Pd(II) and Pt(IV).

Jan 1, 2014

By Rachel S. Prudhomme, Michael L. Jeremic

"The consolidation of mine backfill by free zing is a concept which has been under study in the mining engineering laboratories at Laurentian University during the past three years. The proposed underground application of freezing involves the artificial freezing of in-situ backfill by means of a refrigerated brine solution which would be circulated through a circuit off freeze pipes. The most interesting findings to date are: (I) The uniaxial compressive strength off frozen fill is considerably higher than that of cemented fill in a ratio of 20:1 (aggregate to cement), and (2) load deformation characteristics of the frozen fill suggest that a higher ice content results in more brittle failure and that samples which have initially failed can still support up 10 one-half the ultimate load without additional failure.Although at this early stage a derailed economic analysis of the procedure has not been possible, a general evaluation of the costs involved suggests that the method could be competitive with the hydraulic placement of cemented backfill. Results obtained from laboratory investigations indicate that the freezing of backfill is a structurally feasible option .IntroductionGround consolidation by freezing is based on the principle of transformation o f water contained in an aggregate-slurry into ice, which act s as a binding agent between the bulk particles, and which results in the transformation of a granular soil into a ""rock -type"" material. The abrasive nature of the particles enhance s the strength o f the ice by providing internal friction. As a result of this internal friction, the chances of plastic flow of the frozen mass when in a loaded condition are reduced(1). T he strength of a frozen aggregate is al so dependent on the grain shape of the aggregate particles which may or may not promote particle interlocking(2) and on the temperature since, below the freezing point of the water/aggregate mixture, the strength of the frozen mass increase s with decreasing temperatures.In the shaft sinking industry, artificial freezing of loose , unconsolidated soils has been in practice for several decades. Shafts for Saskatchewan 's potash industry have been sun k to depths of 3000 feet by employing artificial freezing to stabilize the Blairmore Formation(3). The common procedure for freezing ground for shaft sinking is summarized as follows(4,5): I) 150 mm diameter bore holes spaced on 1.5 m centres are drilled in a circular pattern with a radius of 1.5 m outside the periphery of the proposed shaft."

Jan 1, 1985

By Chas. L. Emery

"The laws of rock mechanics apply equally well to all rock structures, and open pits are not exceptions. The concepts and some arguments about the emphasis to be placed on various aspects of open-pit design are discussed in this article.RocksROCK can be described as a granular material consisting of grains and glue. The grains may be fragments of other rocks or polycrystalline aggregates. The glue may be ferruginous, calcareous, argillaceous, siliceous or other material connecting the grains. In a crystal intergrowth, the outer layers of the crystals in contact with each other may be considered to act as a glue. Water may be a glue in clay or a grain in a crystal structure. Air and other fluids or gases are grains if they occupy spaces in a granular mass. Such grains are functional either chemically or mechanically or both."

Jan 1, 1966

By Steve Simard

Suite aux excellents résultats, obtenus avec la technologie des détonateurs électroniques dans des chantiers longs trous de grandes dimensions, nous avons décidé d?étendre cette technologie dans les ouvertures, dans le dynamitage de piliers et dans différents chantiers complexes. Cette technologie nous a permis d?effectuer l?abatage de chantiers avec un très grand nombre de trous sans détériorer le terrain. L?équation est bien simple avec les détonateurs électroniques, plus gros sont les dynamitages moins de fois les épontes se font ébranler, moins de blocs d?effondrement se retrouvent dans les points de soutirages entre les dynamitages et plus la fragmentation est meilleure. La flexibilité d?opération que nous avons obtenu avec les détonateurs électroniques est difficilement quantifiable, mais elle nous a permis de maintenir notre rythme de production mensuelle même avec certains chantiers complexes. Il est bien certain que l?utilisation des détonateurs conventionnels a encore sa place dans une mine conventionnelle comme Beaufor, mais l?utilisation des détonateurs électroniques a aussi sa place dans certaines situations spéciales. Pour terminer, bien que la technologie des détonateurs électroniques soit encore dispendieuse, nous pensons encore l?utiliser pour optimiser certains dynamitages et ainsi maintenir notre flexibilité d?opération.

Oct 1, 2004

By D. B. Johnson

Acidic, metal-rich waters generated at working metal mines and abandoned mine sites are generally considered to be major pollutants of the environment. However, the metals they contain often have significant value of their own, or as sources of useful mineral products. We have developed novel bioreactor systems that facilitate the selective recovery of various transition metals (e.g. copper, zinc and iron) as defined minerals that can be recovered and recycled. The bioreactors use novel species of acidophilic bacteria. Ferrous iron is oxidised by Ferrovum myxofaciens, a specialist bacterium that forms large amounts of exopolymers and grows as filamentous streamers in flowing mine waters, and the ferric iron generated is precipitated as the mineral schwertmannite, a small proportion of which is used to remove any arsenic present in mine water. Copper and zinc are precipitated as sulphides using H2S generated by consortia of acidophilic and acid-tolerant sulphate-reducing bacteria in a continuous flow, on-line low pH bioreactor. Transition metal sulfides can be segregated by precipitating them, either on-line or off-line, at different pH values. The modular units that have been developed can be configured to treat mine waters of different chemistries. A hypothetical acidic (pH 2.5) mine water stream containing 500 mg/L iron, 100 mg/L of copper and zinc, 50 mg/L of aluminum and manganese, 2 mg/L of arsenate, and discharged at a rate of 10 L/s, is used as an example of the potential application of the mineral-generating bioreactors. The environmental benefits and economic implications of considering mine waters as resources rather than wastes are discussed.

Aug 1, 2013

By Joseph Bradley

THROUGHOUT this article, minerals used in the paint industry are designated 'pigments'. They may be classified in two groups: (1) Pigments which are used in the state in which they occur in nature, requiring only mechanical preparation. (2) Pigments which require heating or chemical treatment before use, in order to obtain from them a product of the desired quality or shade of colour. They may be further classified according to colour, as follows: White Pigments .-These include calcium carbonate (chalk, marble), gypsum and alabaster, kaolin-or china-clay, and magnesia. However, the white pigments most extensively used are compounds prepared chemically from minerals containing lead, zinc, titanium, and antimony. The white pigments are of particular importance because, not only are they used by themselves, but they also serve as adjuncts to other colours for the production of special shades. Yellow Pigments.-These are mainly naturally occurring ferric hydroxides, as limonite and bog iron ore, or similar. compounds prepared artificially. Brown Pigments .-Pigments of this group are distinguished for their beauty and depth of colour, and many of them are used in the finest of paintings. Familiar names are sienna, umber, and Vandyke brown. They are for the most part ferric hydroxides, containing varying amounts of water; but the group also includes a manganese brown, which consists chiefly of a mixture of oxide and hydroxide of manganese. Red Pigments.-Chief among this group is ferric oxide, known under various trade-names, such as Canadian red, Persian red, etc., and also the much prized and somewhat rare vermilion. The pigment used is either naturally occurring hematite, de-hydrated limonite, or artificially produced red ferric oxide.

Jan 1, 1937

By W. G. Deeks

CANADIANS are world leaders in marketing metal and mineral products. Noranda Sales Corporation Ltd. is an international metal and mineral product marketing company operating from Toronto and London, England, where it operates a wholly owned sales subsidiary and is a 50% partner in Rudolf Wolff and Company Ltd., a charter member and the largest metal broker on the London Metal Exchange. Noranda Sales employs 97 people, of whom 52 are university trained and professionally competent in international resource product marketing. We market for 19 companies or divisions in the Noranda Group and 39 companies for whom we act as agent, consultant and purchaser of resource production. Our business in 1976 was 1.5 billion dollars carried out in 45 countries and covering 24 products and materials. Today, ownership of most of the mining industry in Canada has transferred back to Canadians, and this is said with the knowledge that a significant part of the Canadian industry has been Canadian owned and managed from its very early days. Noranda Mines Limited is such an example. It was born in 1922 as the result of a copper-gold showing at Noranda, Quebec, discovered by Ed Horne, a prospector, financed with a grubstake by a syndicate mainly composed of New York businessmen. Shortly after the discovery, when the shares of the company had risen, the syndicate was sold to Canadian interests and, since that time, Noranda has been dominantly Canadian owned and certainly Canadian managed. Today, over 90% of Noranda's shareholders are Canadian, who hold an equivalent percentage of the stock.

Jan 1, 1977

By T. R. Kostecki, K. V. Jessu

"Roof bolts are subjected to axial stresses, shear stresses, or both. Axial and shear stresses were compared between roof bolts machined with two and three slots. Shear stresses perpendicular to and at an angle to the shear planes were evaluated by analyzing a three-slot instrumented roof bolt, performing laboratory tests on two- and three-slot roof bolts, and conducting in-situ test analyses. Threeslot bolts appear to provide a complete bending strain profile, requiring no prior knowledge of the estimated shear-plane orientation. Minimum displacements occur in roof bolts installed perpendicular to rather than at an angle to the shear planes.RÉSUMÉ Les boulons d’ancrage dans le toit d’une mine sont sujets à des contraintes axiales, des contraintes de cisaillement ou les deux. On a comparé les contraintes axiales et de cisaillement de boulons d’ancrage usinés avec deux ou trois fentes. Les contraintes de cisaillement perpendiculaires et à angle aux plans de cisaillement ont été évaluées en analysant un boulon d’ancrage de toit à trois fentes, en effectuant des essais en laboratoire sur des boulons d’ancrage de toit à deux et à trois fentes et en effectuant des analyses de tests in situ. Les boulons à trois fentes semblent fournir un profil complet de résistance aux contraintes de flexion, sans avoir besoin de connaître l’orientation estimée du plan de cisaillement. Des déplacements minimums ont lieu dans les boulons d’ancrage de toit installés perpendiculairement, plutôt qu’à un angle, aux plans de cisaillement."

Jan 1, 2016

By Tsuyoshi Adachi

Photovoltaic (PV) system is especially taken notice as one of important renewable energy resources, because PV has potential to provide a certain amount of energy supply as well as without greenhouse gases emission. Considering recent rapid increasing demand for PV system, more expansion of PV system is expected in the future. However, some precious metals and minor metals such as silver, indium and others are used as component materials of solar cell in PV system. Even if energy supply would become renewable, strict limitation of these metals still remain because amount of natural resources and recycling of metals has restrictions intrinsically. The aim of this study is to reveal the possibility of materials supply restrictions for Photovoltaic system quantitatively and to propose several measurements to assess supply risks for materials. Especially, silver supply potential which is used as wire line in PV system as well as PV demand forecast to estimate material use in the future are focused on. We divide underlying supply risk into 5 measurements and analyze them by time series, i.e. price volatility, resource potential, recycling ratio, production type and supply concentration are investigated. Comparing these factors of silver with other metals, the potential of silver supply for PV is presented. In addition to it, we propose another method to quantify country risk applied an insurance pricing model in finance pricing theory and combine it with the supply concentration measurement. As a result, supply risk of silver will increase gradually in the near future because of its resource constraints and supply-demand balances although silver market is sufficiency competitive one. From the country risk analysis, Peru is not only a significant supply country but also has the highest country risk. Some higher risk countries will increase the level of supply risk even if the concentration ratio of supply indicates moderate level.

Aug 1, 2013

By Muhammad Tawalbeh

The calculated temperature history of a single particle of MgCl2 hydrates when it came in contact with fused salt electrolyte at 650 °C was determined using the measured heat transfer coefficient for the molten salt bath at 650 °C. The calculations revealed that the entire interior of the particle reached the temperature required for the formation of MgOHCI from hydrated MgCl2 in less than 2 seconds. This was much less than the time required for dissolution of the prills as observed in experiments. It is very likely that the formation of MgOHCI during prill dehydration and dissolution is a result of hydrolysis in the interior of the prills.

Jan 1, 2004

By Melanie Grob

Two commonly estimated fractal dimensions, called b and D values, represent statistical characteristics in the distribution of magnitude sizes (b) and spatial hypocenter locations (D) of microseismic events, respectively. We postulate that the values of b and D are related to specific stress regimes. Through different case studies of fluid injection into an oil/gas reservoir or geothermal field, we infer that the measured temporal variation in fractal dimension b is most likely due to significant changes in the local stress regime. The fracture dimension D indicates the spatial clustering of events. The distribution of these events can vary with time because of stress perturbations that (re)activate fractures whose direction favours their movement under a specific stress regime. Thus a combined statistical study of these two dimensions can help infer the variations of local stresses in a reservoir.

Jun 1, 2012

By Wei Zhang, Jinhong Zhang

"The adsorption of ethyl xanthate on copper sulfides, i.e., chalcopyrite, chalcocite and bornite, has been studied in situ in aqueous solutions by applying an atomic force microscopy (AFM). AFM images show that xanthate, such as potassium ethyl xanthate (KEX), adsorbs strongly on chalcocite and bornite mainly in the form of insoluble metal xanthate, which binds strongly with the mineral surface without being removed by flushing with ethanol alcohol. This adsorption mechanism is totally different from the one obtained with chalcopyrite/xanthate system, during which oily dixanthogen is the main adsorption product on chalcopyrite surface. The findings obtained from the present AFM study suggest that an AFM image analysis is a powerful tool for the study of the collector’s adsorption on mineral surface and as well the development of novel collector for copper sulfide flotation.INTRODUCTIONIn mining industry, copper sulfide minerals, i.e., chalcopyrite, chalcocite and bornite, are usually separated selectively from non-valuable gangue by froth flotation, which treats the highest throughput and produces the maximum economic outcome of any surface chemistry process. In flotation, collectors are added into the pulp (mixture of water and fine-grained minerals) to selectively adsorb onto the target mineral and render its surface with high hydrophobicity, which is generally beneficial for a strong mineralbubble attachment and thus a high flotation recovery.The adsorption of collector on mineral surface, therefore, is vital for a successful flotation process and it has been studied by applying various surface analysis techniques, such as IR (Infrared Spectroscopy), CV (Cyclic Voltammetry) and XPS (X-ray Photoelectron Spectroscopy). (Poling, 1963; Allison et al., 1972; Mielczarski et al., 1984; Leppinen et al., 1989; Kartio et al., 1996) These studies have revealed a lot of information, such as the reaction, product and mechanism, of the adsorption of chemicals on mineral surface. It is also of great interest to directly get the image of adsorbed collectors on mineral surface changing with pulp chemistry, such as pH, redox potential, ionic strength and chemical’s dosage."

Jan 1, 2016

By A. L. Mackie

Arsenic is a highly toxic element and a known human carcinogen. It is often a contaminant in mine water discharges, particularly from gold mining and roasting operations, and has been found at concentrations as high as 4 g/L. Increasingly stringent controls on the concentration of arsenic allowed to be discharged into the environment cannot always be met by current treatment processes and thus enhanced technologies are required to achieve low treated effluent concentrations at reasonable costs. A novel two-step physicochemical treatment process was developed and tested at the bench-scale using synthetic mine water solutions (SMWs) in order to reduce arsenic concentrations in treated effluent to exceed current discharge regulations. The process includes chemical coagulation with ferric sulphate and ballasted flocculation for enhanced solid-liquid separation. The SMW contained 59 ± 2 mg/L arsenic with a slightly alkaline pH. The effect of arsenic speciation on the process was tested by using either arsenite, As(III), or arsenate, As(V), in the SMW solutions. Tests were performed at cold temperature (3 ± 1 °C) to ensure the process? efficacy year-round in northern climates. Arsenic in As(V) SMW solutions was removed to a final total concentration of 0.0054 ± 0.002 mg/L, almost half the current recommended allowable drinking water concentration of 0.010 mg/L. As(III) was removed to a concentration below the Metal Mining Effluent Regulations? (MMER) current limit of 0.50 mg/L, to 0.32 ± 0.06 mg/L, with double the coagulant dose used in Stage 1 for As(V) removal. Oxidant addition at a concentration of 5 mg KMnO4/L in Stage 2 resulted in final total arsenic concentrations of 0.017 ± 0.002 mg/L and pH adjustment with lime in Stage 2 resulted in 0.0415 ± 0.0007 mg As/L in treated As(III) SMW. Both of these modifications to the process reduced arsenic concentrations to below proposed new MMER limits (i.e., 0.10 mg/L). This two-stage treatment process was shown to reduce arsenic concentrations to well below current treatment guidelines while reducing or eliminating chemical oxidant demand.

Aug 1, 2013