Search Documents

By G. W. Zhang, Changsha Research Institute of Mining and Metallurgy, X. Xiao, Y. Long, L. L. Huang

"The paper presents a scale-up and design method of vertical screw stirred mill, in which the closed circuit of mill and hydrocyclone was assumed as one factor, theoretically regardless the affects inside system of the mill and hydrocylone. The specific energy is chosen as a scale-up criterion, based on the premise that when fed the same feed material, mills of different sizes delivering the same specific energy will yield products.Batch grinding tests are conducted to determine the specific energy, and combined with industrial production data, scale-up and design of vertical screw stirred mill for industrial production are accomplished. Having developed this method for the vertical screw stirred mill used in regrinding duty of iron ore in Ma Steel, it has now been successfully applied in other installations.INTRODUCTIONThe Towermill was developed in Japan in the 1950s, by the Tower Mill Kubota Corporation, it was fine and ultra-fine grinding mill of the metallic ores and concentrates. Due to the rapid development of metal mining and useful minerals disseminated fine, fine grinding and ultrafine grinding equipment has also been more wide used in minerals processing industry. Typical fine and ultra-fine grinding mil are the Vertimill and Stirred Media Detritor (SMD) Mill of Metso, Eirich Towemill, Outotec HIGmill, FLSmidth VXPmill, Xstrata Isamill and the vertical screw stirred mill (JM) of CRIMM, etc.JM series of vertical screw stirred mill were invented by Changsha Research Institute of Mining and Metallurgy in the 1980s. Energy saving and consumption reducing have been achieved through the optimization and engineering practice. More than 500 units JM series of vertical screw stirred mill are used in the iron ore, copper ore, copper-molybdenum ore, molybdenum ore, Pb-Zn ore and Au ore."

Jan 1, 2016

By G. A. Gillett, C. F. Bonney

"The Davy McKee combined mixer-settler (CMS), is a liquid-liquid contactor, which has been commercially applied to the recovery of uranium from dilute sulphuric acid-bearing leach liquors. CMS differs from most other solvent extraction systems in that the mixing and separation of the phases is carried out in the same vessel.IntroductionTypical solvent extraction plants for the recovery of uranium operate at organic to aqueous feed flow ratios of 1 : 2 to 1 : 30. Because it is beneficial to mix the organic and aqueous phases at an organic/aqueous (O / A) ratio of between I : 2 and 2 : I there is incompatibility between the over-all and operating O /A ratios.Conventional mixer-settler designs require an external recycle of the minority flow which results in the possibility of over-mixing, increased settling requirements and entrainment losses. Other workers have approached this problem in terms o f enhanced sett ling and this has been partly successful.Davy McKee's approach involved a radical rethink of the principles of liquid-liquid contact and separation.Description of CMSThe CMS has the important advance that the required mixing O/A ratio can be achieved without external recycle and is not affected by the O /A ratio of the feeds. Three zones co-exist within the CMS unit-a central mixing zone and upper and lower separation zones. A pump impeller on a draught tube is installed within the mixing zone and baffles are installed above and below the mixing zone. Conventional mixer- settlers have several undesirable features which ca n largely be eliminated using the CMS system:"

Jan 1, 1983

By Mei-Yan Yang, Qiu-Ying Wang, Ltd. Yunnan Yuntong Zinc Co., Guo-Mu Chen, Meng-Yang Huang, Peng Zeng, Guo-Feng Li

"Historically, alot of jarosite was found in the leaching residue when leaching indium from secondary zinc oxide materials. The reasons for the formation of indium bearing jarosite were theoretically analyzed. The influence of controlling the acidity and the addition of reagents on the indium leaching yield during secondary zinc oxide processing was investigated. In order to increase the leaching yield of indium, a measure of controlling the creation and destruction of jarosite was proposed. The production data shows that the leaching yield of indium was increased from 60 to 96%, and the content of indium in leaching residue simultaneously decreased from 900g/t to 100–200g/t when implementing such controlling measures.INTRODUCTIONIndium does not occur as independent minerals in the earth’s crust and is mainly associated with complex sulphide minerals. Specifically some sphalerites can contain as much as 900g/t of indium. Most indium is recovered from by-products of copper, lead or zinc metallurgy. Therefore, the research on the recovery of by-products in non-ferrous metallurgy is important(Sinclair et al, 2006). The main technologies used for this objective in China include: •,pre-neutralization-reduction-precipitation indium process(Yu et al, 2008), •,countercurrent oxidizing acid leaching process and sulphation roasting-water leaching process(Cao, 2005), •,oxygen pressure acid leaching of zinc concentrate-P204 extraction process(Yang et al, 2006), •,doubleacid leaching-solvent extraction process on lead dross from a reverbatory furnace flue dust(Liu, 2003),•,an acid leaching-solvent extraction process on smelting ash(Zhouet al, 2005). Although high pressure and extreme conditions can be used to improve extraction from high iron bearing indium residues(autoclave processing), mild extraction with lower cost and lower environmental impact are preferred.This paper describes both how the indium extraction using mild conditions in a secondary zinc circuit was quite low and, how through XRD and chemical analysis jarosite formation was found as the main cause. The paper then proceeds to discuss a method for improving the leaching yield and the application of this method in industrial practice."

Jan 1, 2016

By Rolf Andreas Lauten, Guy Kluck

"Formation of scales may have important detrimental effects in many mineral processing applications. A well-known problem is the need for frequent maintenance to remove scale from processing equipment. Another challenge may relate to encapsulation of valuable minerals in precipitating scale. In this work, we explore the ability of some crystal growth inhibitors to prevent or lower the degree of scale precipitation. In many situations pregnant leach solutions contains substantial concentrations of calcium, magnesium, sulfate and carbonate in addition to dissolved valuable elements, e.g. gold, copper, zinc. Together with non-dissolved gangue minerals, some slurries may also contain particulate gold, copper etc. During normal processing of the pregnant leach solution it may be exposed to temperature gradients or similar promoting precipitation of various scales. Valuable minerals may become entrapped in precipitates and thus become inaccessible to the lixiviant. Use of a crystal growth inhibitor may lower the degree of encapsulation of valuable elements.Using a simple model system, supersaturated with respect to gypsum, the effect of some crystal growth inhibitors on the prevention of scale is evaluated in terms of amount precipitated gypsum, the particle size of the precipitated gypsum and the carbon gold loading capacity.INTRODUCTIONGold bearing sulfide ores are often roasted or pressure oxidised prior to leaching. The purpose of this unit operation is to prevent loading the leaching circuit with sulfides that consume cyanide. Pressure oxidation or roasting chemically converts the sulfides into sulfates and at the same time, the pH of the slurry ends up in the acidic range. Typically, lime addition is the preferred means to raise the pH to around 10 where gold leaching takes place. Combination of large amounts of calcium ions from the lime with sulfate ions from the ore induces precipitation of gypsum. Compounds like calcium carbonate may also precipitate if carbonate ions are present in the slurry. Depending upon the composition of the ore, compounds like calcium carbonate and other types of scale may also precipitate on gold surfaces on the slurry particles. A layer of scale on top of exposed gold surfaces will prevent dissolution in the cyanidation that takes place during leaching. Naturally, such a precipitation may lower the gold recovery."

Jan 1, 2016

By Hans D. Gougar

To meet an increasing demand for minerals, mining operations are moving to ever more remote regions. The lack of a local energy supply and infrastructure, coupled with social and regulatory demands for lowered environmental impact of mining operations, presents an opportunity for a seemingly unlikely competitor ? a nuclear power plant. The Modular Pebble Bed Reactor concept, currently in various stages of research and development around the world, offers a high degree of reliability and safety with minimal consequences for the local or global environment. The passive safety features of this design eliminate the need for the extensive active safety systems that add significantly to the cost of current water-cooled reactors. With the MPBR, as with all nuclear plants, there are no appreciable quantities of waste products released to the environment during normal operations. In contrast with conventional reactor designs, the MPBR would also remain radiologically safe even under the most severe abnormal circumstances. The key to the design is the fuel element. Enriched uranium microspheres are coated with various layers of pyrolytic carbons and silicon carbide to form a highly-temperature resistant particle that effectively retains all fission products. These particles are mixed with graphite and formed into 6 cm pebbles. A randomly packed vessel of such pebbles forms the reactor core through which helium is circulated as a coolant. Computer models and tests performed on actual pebble bed reactors confirm that fuel failure temperatures are not reached even during the most severe conceivable loss of coolant accident. The reactor drives a gas turbine cycle with resulting efficiencies as high as 48%, comparable to natural gas-fired units. The low price of uranium fuel and low maintenance requirements translates into competitive operating costs. However, high capital costs prevent the MPBR from competing with natural gas in most markets. In remote applications where no fossil supplies are readily available, the playing field is more level. This paper summarizes the features of two of the more promising candidates for remote applications and discusses the strengths of the MPBR from the perspectives of fuel supply and environmental impact.

May 1, 2002

By Q. Ricoux, F. Goettmann, A. Maihatchi

"Electrodeposition processes are widely used in the metallurgical industry to produce, extract and refine metals from various feed materials. However, raw materials used to provide non-ferrous metals often contain high amounts of iron. In the presence of iron, while metals are plated at the cathode, electrowinning processes produce corrosive and highly oxidative ferric ions at the anode that are harmful for the process sustainability. In fact, these ferric ions cause dramatic current efficiency loss, induce high maintenance expenditures to limit the corrosion of devices and it results in the formation of impure and dendritic deposits on the cathode. Consequently, the management of iron in electrodeposition process became a major issue in non-ferrous metals production. Actually, numerous methods have been developed to limit the ferric ion concentration in the electrolyte or, at least, to limit its harmful effect. Many methods aim to limit the iron(III) concentration in the electrolyte, generally by coupling electrowinning to extraction process such as solvent extraction (SX) (Bender & Emmerich, 2015), ion exchange (IX) (Gula, Dreisinger, & Horwitz, 1996) or cementation (Kust, 1979) processes to remove ferric ions. Other routes consist of (i) using the ferric ions oxidant properties to leach raw materials, either directly in the electrolytic cell (Fanta & Tributsch, 1975) or through a secondary circuit (Cain, 1950), or (ii) reducing ferric ions through periodic reversal of direct current to enhance the formation of Fe2+ (Loutfy & Bharucha, 1980). On the other side of the spectrum, papers discuss methods to valorize the iron from by-products of the non-ferrous metal industry, that generates vast quantities of iron containing wastes (A. Agrawal, Sahu, & Pandey, 2004). Many studies on iron electroplating and electrolytic iron production from ores have been carried out (Cain, 1950; Mostad, Rolseth, & Thonstad, 2008), but very few have been conducted on waste or by-products. Therefore, we propose to build on the previous literature review to develop a process for the production of electrolytic iron from by-products.INTRODUCTIONNon-ferrous metals and their alloys are used in a large variety of applications. Aluminum and titanium are used for their strength, light weight and corrosion resistant properties in structural applications. Copper has been used in various applications requiring high thermal and electrical conductivity, as kitchen products and electrical wires. Nickel and zinc are commonly used as plating materials; nickel offers a wide range of working temperature and zinc is used for steel plating. Gold, silver, and platinum group metals are used in electrical/electronic applications, jewelry and chemistry as catalysts."

Jan 1, 2016

By Ngonidzashe Chimwani, David Glasser, Diane Hildebrandt

"Milling circuits play an important role in achieving the desired product; tonnage, size distribution and properties, since they are directly linked to the comminution energy consumption for the whole process. A grinding model with a mathematical simulation was developed for an open milling circuit with a scalped feed from a hydro-cyclone. The circuit was optimized by determining the optimal conditions in terms of energy consumption which would produce a floatable product having a desired size range (i.e. -75 +9 µm) for a platinum-bearing ore. The simulation results showed an operating region comprising the best combination of the ball filling and mill speed to achieve the highest production of a floatable size class, with the minimum energy consumption.INTRODUCTIONBall milling is usually conducted in closed circuits in order to achieve a desired product size without material overgrinding. The technological importance of optimising milling circuits cannot be overemphasised (Toneva and Peukert, 2007). Previous work has brought significant insights into the benefits of modelling milling circuits (Austin et al., 1984; King, 2012; Toneva and Peukert, 2007). However, the ability to model these circuits is dependent on the performance of the classifiers and the fidelity of the grinding mill model used compared to the actual circuit (Toneva and Peukert, 2007). Austin et al. (1984) identified five types of milling circuits as shown in Figure 1 namely; the grinding circuits employing mill in an open circuit, normal closed circuit, reverse closed circuit, open circuit with scalped feed, and, the combined closed circuit. Depending on the presence of the first classifier, the second, or both as well as their corresponding loops (streams), the combined circuit (e) can reduce to; an open (d), a normal closed (b), an open circuit with scalped feed (c) or a reverse closed circuit (a). In the case of an open circuit, the mill is operated without being directly influenced by a classifier. The normal closed circuit does not have the first classifier and therefore the make-up feed is the actual feed stream. Conversely, the reverse closed circuit keeps only the first classifier. The open circuited with scalped feed has only the first classifier but does not have the second one. The overflow stream from the classifier is mixed with the mill product to form the final product for the downstream process."

Jan 1, 2016

By Feng Tianran, Lu Shijie, Shen Zhengchang, Han Zhibin, Tan Ming

"As a kind of non-metallic material, high-purify quartz sand has been widely used in many fields. Flotation is a popular way to process quartz sand. But it is in difficult position for flotation to get high-purify quartz product due to large amount of coarse particles contained in the feed. In this paper, a design principle of special flotation cell for high-purify quartz sand has been put forward base on ore property analysis and laboratory test, and the pilot scale special flotation cell has been developed to meet the requirement of the quartz sand flotation process. The special flotation cell for high-purify quartz sand is featured by middle positioned impeller, false bottom and draft tube, which could decrease the rising distance of mineralized bubble and strengthen the circulation capacity of the lower part of the flotation cell. Hydrodynamic study indicates that high air dispersion degree and strong lower slurry circulation could be produced by pilot scale special flotation cell, which is helpful to create a suitable hydrodynamic environment for quartz sand processing.INTRODUCTIONNatural quartz is a non-metallic mineral, which is widely used as raw material in multiple industry process (Shifu, 2006). High purity quartz, especially containing more than 99.9% silicon dioxide, is characterized by high temperature resistance, small thermal expansion coefficient, highly insulating and so on. The demand of high purity quartz has been rising along with social and economic development, now high purity quartz is widely used in the field of photovoltaic industry, electronic information, communications and aerospace industry.Quartz is a kind of main rocking-forming minerals in the nature. There are seven genetic types, such as natural crystal, quartz sandstone, quartzite, vein quartz, konilite, natural siliceous sand, granite quartz (Baolei, Shuilin, & Dianchao, 2012). The natural crystal is primarily used as raw material to refine high purity quartz, but it is not available for two reasons. On the one hand, the natural crystal is extremely expensive and poor in resources reserves, which can not satisfy the need of large-scale industrial production. On the other hand, the chemical component of natural crystal is instability, it may lead to low stable product performance in large industrial applications, and it is also difficult to achieve raw materials standardization. Therefore, there are a lot of studies to search for other technological methods to obtain high purity quartz from other genetic quartz types."

Jan 1, 2016

By René G. del Villar, Jules Thibault, René del Villar

"Some key control variables of industrial processes, associated with product quality, often cannot be measured directly or frequently enough to establish adequate control. In such cases, it is possible to use available measurements to provide a prediction for these process variables and use them in a control strategy, thereby giving rise to what is now commonly called a softsensor.In some industrial grinding circuits, the on-line particle size analyzer is shared between various sampling points. Therefore, for a given location, the actual measurement is only available every 10 to 20 minutes, a delay which is unacceptable for automatic control purposes. To alleviate this problem, a softsensor based on an artificial neural network has been investigated. First, the structure of the neural network and different schemes for the training process are analyzed. Then, the performance of the neural network softsensor is compared with other inferential methods such as ARMA models and Kalman filters.IntroductionGRAHM, French acronym of the Research Group on Computer Applications in the Mineral Industry at Laval University, began in 1990 a research project on Knowledge Based Automatic Control (KBAC). This project, sponsored by a consortium of eight mining companies and the federal and provincial governments, seeked to screen advanced (knowledge-based) methods for data processing (filtering, mass balancing, etc) and automatic control (model-based) for their use in the mineral processing operations and the transfer of the project results to the sponsor companies.In parallel to more academic research work, a number of case-studies have been undertaken with the cooperation of partner companies. Among such works, a very successful one has been the design and installation of a new control strategy for one of the Kidd Creek (Falconbridge Ltd.) grinding circuits. This project was related to the evaluation of a number of control strategies and the implementation of one of them, as selected by the plant management, in the concentrator.A total of sixteen control schemes were evaluated on one of the dynamic phenomenological simulators developed at GRAHM, a trademark of this research group [ l]. The calibration of the simulator models was done based on industrial data gathered by GRAHM and Kidd Creek personnel. Then, the simulator was used to test the performance of various PID-based control schemes, designed to achieve the control objectives set by the Kidd Creek personnel. The best scheme proposed called for controlling the cyclone overflow particle size by manipulating the water addition rate to the cyclone feed box and the circulating load by manipulating the circuit ore feed. The particle size analyzer (PSI-200) available for monitoring the product size, was unfortunately shared (multiplexed) among various streams of the plant, which meant a 14 min delay between two consecutive readings for any particular stream. This induced the plant personnel to choose an alternative control strategy, one which controlled the cyclone feed density instead of the cyclone overflow particle size."

Jan 1, 1996

By Mariam Melashvili, Chris Fleming, Rene Jackman

"A study was undertaken to develop a flowsheet for treating a high grade silver/gold ore body by cyanidation, CCD and Merrill Crowe precipitation, with tailings detoxification to meet stringent limits for cyanide and thiocyanate concentrations in the final discharge. In one of the flowsheets examined, free cyanide in the final leach liquor was recycled to the mill where it was hoped that it might react beneficially with fresh ore to reduce the cyanide makeup by an equivalent amount. However, laboratory results suggested that most of the cyanide recycled to the mill reacted with iron forming a soluble ferrocyanide complex. This would have had a negative impact on cost, not only because the cyanide recycled to the mill could not be claimed as a credit, but also because the presence of ferrocyanide in the final tailings meant copper sulphate had to be added to the SO2/air cyanide detoxification process to precipitate the iron cyanide. In an alternative flowsheet that was examined, recycling of cyanide to the mill was abandoned, and this allowed the milled slurry to be pre-aerated in a single mixing tank before cyanidation. During alkaline pre-aeration, any ferrous ions that are generated in the mill are oxidized to ferric ions, which, unlike ferrous ions, are inert in cyanide solution. This significantly reduced cyanide consumption and lowered costs in the detoxification of the tailings. In this paper, the cost implication of these two circuits is compared.INTRODUCTIONMost of the gold that is produced by hydrometallurgical processes is recovered by cyanide leaching. The reason for that lies in the superior thermodynamic stability of the gold cyanide complex and the favorable economics this confers on the process (Fleming, 2014). However, the gold in most of the gold-bearing ores processed is a very minor component, and therefore, the leaching response is often dominated by that of the host minerals.Many gold ores treated by the cyanidation process contain iron minerals. Cyanide reacts readily with some iron minerals forming ferrocyanide as one of the compounds. Ferrocyanide is stable when solutions are exposed to air and does not retard the dissolution of gold. In fact, it has been claimed that potassium ferrocyanide in the presence of oxygen is a weak solvent for gold (Hedley & Tabachnick, 1958). The main problem with the formation of this compound is the consumption of cyanide. Ferrocyanide contains six molecules of cyanide for each atom of iron {Fe(CN)64-} so the wasteful consumption of cyanide is greatly increased by its presence. Thiocyanate is also often produced during the reaction of certain iron sulphide minerals with cyanide, and contributes to the wasteful consumption of cyanide. In addition, environmental regulations in certain countries demand that thiocyanate be removed from the tailings, and this adds significantly to the cost of tailings treatment."

Jan 1, 2016

By Kazutoshi Haga, Batnasan Altansukh, Atsushi Shibayama, Ryuji Oinuma

"Recently, the arsenic grade in copper ores has been increasing year by year. Arsenic bearing minerals (enargite (Cu3AsS4) and tennantite (Cu12As4S13)) coexist with typical copper minerals such as chalcopyrite (CuFeS2). The removal of arsenic from copper ores that contain relatively high arsenic content is essential due to its adverse impact on the environment and the resulting economic consequences. In this study, arsenic removal and dissolution behaviour of Cu and As from enargite (Cu3AsS4) were investigated using ferric sulphate (Fe2(SO4)3) solutions containing sodium chloride under high pressure oxidation conditions. The effects of numerous parameters including the concentration of Fe2(SO4)3 and NaCl, temperature, total pressure, leaching time and particle size were studied while other variables such as pulp density and stirring speed were fixed at 100 g/L and 750 rpm. The results showed that more than 60% of the copper was dissolved in a 0.1 M ferric sulphate solution under the high pressure oxidative conditions, whereas the leaching rate of arsenic was less than 20%. SEM observation revealed that elemental sulphur was deposited on the surface of enargite forming a passivation layer and the residue was agglomerated. Those phenomena may cause a decrease in the copper leaching rate. It was found that more than 80% of copper was dissolved in the ferric sulphate solution in the presence of 0.34 M sodium chloride under the conditions optimized, whereas the dissolution of arsenic in the mixture did not exceed 2%. XRD analysis of the solid residues from the leaching experiments used ferric sulphate and mixtures of ferric sulphate and sodium chloride showed arsenic to be present as scorodite (FeAsO4).INTRODUCTION In recent years, there has been an increase of the arsenic (As) content of copper ores due to the gradual depletion of high grade copper ores. In some copper deposits, arsenic occurs in the form of minerals such as enargite and tennantite. The removal of arsenic in ores containing copper is critical to the production of pure copper and the management of the environmental challenges caused by the smelting process. Due to the environmental risk caused by arsenic emission and the deteriorated quality of the copper product, smelting of enargite concentrates is not an effective method for the extraction of copper (Padilla et al., 2010; Safarzadeh et al., 2014; Long et al., 2012). Therefore, a number of studies have been carried out to develop arsenic removal technologies from copper ores using various methods such as hydrometallurgy (Curreli et al., 2009; Tongamp et al. 2010), pyrometallurgy (Dalewski., 1999; Padilla. et al, 2012) and bio-oxidation (Ehrlich, 1964; Sasaki et al., 2010). Several hydrometallurgical leaching processes like sulphuric acid, alkaline sodium sulphide and sodium sulphate and ferric sulphate leaching have been developed to treat enargite ores and concentrates. The alkaline sodium sulphide leaching process has been developed for the removal of arsenic from enargite (Anderson, & Twidwell, 2008; Parada et al., 2014). The mechanism of the dissolution of arsenic from enargite in sodium sulphite solution is"

Jan 1, 2016

By M. Niinae, F. Nakahara, T. Kawamoto, T. Suzuki

"MgO was chosen as an As(V) immobilization agent and a series of immobilization experiments was performed to obtain insights into the behavior of As(V)and MgO during leaching tests. Our experimental and modeling results demonstrated that As(V) immobilization by MgO consists of the following steps: (i) an increase in soil pH, (ii) desorption of As(V) from the soil, and (iii) the re-immobilization of As(V) by MgO/Mg(OH)2particles. Regarding the behavior of MgO, the modeling results showed that when the MgO dosage was 25 mg MgO/4g-drysoilor less, the majority of MgO was used to increase pH, and less than 1% of MgO was used to sorb As(V), which was consistent with the result of leaching tests showing that a high level of As(V) was leached at the MgO dosages. On the other hand, when the MgO dosage was above 25 mg MgO/4g-drysoil, the percentage of MgO used for As(V) sorption increased up to 35%, and correspondingly, the As(V) leaching level decreased to below 0.01 mg/L As at an MgO dosage of 75 mg MgO/4g-drysoil.INTRODUCTIONOne of the major arsenictransport pathways causing groundwater contamination is the migration of arsenicfrom artificially or naturally contaminated surface soils. Therefore, in this study, the immobilization of arsenate (As(V)) in soils was investigated using commercial-grade magnesium oxide (MgO) as a potential cost-effective measurement to prevent the occurrence of groundwater contamination with As(V).With respect to the use of MgO for remediating As(V)-contaminated environmental media, MgO has been used in several studies to remove As(V)from water(Yu et al., 2011; Jia et al., 2013; Tresintsi et al., 2014). Although these studies demonstrated that MgO effectively removes As(V)from water in water-MgO systems, the behavior of As(V)in water-soil-MgO systems has not been evaluated in the literature, and several questions remain to be answered to comprehensively evaluate the use of MgO as an As(V)immobilization agent in soils. For instance, as is well-documented in the literature(Ford, 2002; Lenoble et al., 2002; Zeng et al., 2008), iron oxy-hydroxide (FeOOH) is one of the important adsorbents for As(V)in both natural and engineered systems. Therefore, it is anticipated that the presence of FeOOH in soils significantly influences the behavior of As(V)in water-soil-MgO systems and consequently, the immobilization performance by MgO. Another important question to be answered is the behavior of MgO during the immobilization treatment. In our previous studies (Suzuki et al., 2013a, 2013b), commercial-grade MgO was demonstrated to effectively immobilize lead and fluoride, and the immobilization effectiveness was indicated to last more than 100 years against the exposure to acid rain (pH 4.0). However, these studies focused on the behavior of contaminants. As a result, little is known about the behavior of MgO during the immobilization treatment. The lack of understanding of the behavior of MgO during immobilization treatment is one of the main concerns leading to relatively low public confidence in immobilization treatments."

Jan 1, 2016

Cambior has been involved in the Guiana Shield since 1990, first in Guyana and then in Suriname starting in 1994. This paper presents the history of Omai Gold Mines Limited in Guyana, where commercial production started in 1993 after an investment of US $150 million. In 1995, the mine was expanded in order to increase the milling capacity to 21,000 tonnes per day. After ten years of production, approximately 3 million ounces of gold have been produced. Building on this experience, Cambior became involved in Suriname with the Rosebel Project. A US $95 million pre-production program started in the fourth quarter of 2002, and the mine should be in commercial production early in 2004.

May 1, 2003

By Melissa Whellams

?? What is a social risk assessment (SRA)? ?? Why do a SRA? ?? When do you do a SRA? ?? How do you do a SRA? What is a social risk assessment? ?? SIA vs. SRA ? SIAs determine how a company?s project will affect social/cultural conditions in a region ? SRAs determine how social/cultural conditions will affect the risk profile of a company?s project Social risk context includes: ? review of human rights record ? analysis of conflict situation ? analysis of political climate ? stakeholder identification ? stakeholder concern/interest identification ? And so on?

May 1, 2008

By L. Freitag

"The Dollard oil field in southwestern Saskatchewan is a stratigraphic trap of irregular shaped perimeter. The reservoir is a low-angle monoclinal structure with a dip of approximately 100 feet in 5 miles from west to east across the long axis of the reservoir. Production of. 23° API gravity crude is obtained from a Jurassic sand referred to as the J-2-A, at an approximate depth of 4,500 feet. Reservoir studies and fluid analyses revealed that the crude is highly undersaturated, having a solution GOR of approximately 130 cubic feet of gas per barrel, that the reservoir has no definable water table, and that it appears to be of a closed-boundary type. Oil production was marked by a rapid pressure decline and it was soon evident that the greatest ultimate recovery would be best obtained if the natural driving energy of the reservoir were augmented by some artificial energy source. In support of a pressure maintenance programme, studies were conducted on flood-pot recoveries of large-diameter cores, and a potentiometric model study of the field was made. These studies indicated that a successful water flood would be obtained. The Dollard field was unitized in 1955 and pressure maintenance started in March 1956."

Jan 1, 1959

By Guy Brouillard

A bow-tie analysis is a safety review methodology that uses a structured approach that can be qualitative or quantitative to document the potential risk of safety incidents. The bowtie diagram itself provides a powerful graphical representation of the threats barriers, events, and recovery measures which are readily understood by the "non-specialist". This presentation will discuss how mining operations can use this valuable tool within their operations to understand the risks and apply the appropriate safeguards toward reducing these risks to acceptable levels.

Jan 1, 2014

By N. Plint, D. Philips, J. Sweet, B. Durant

A pilot scale AG milling campaign was conducted at the AngloAmerican Platinum pilot plant in South Africa. Different blends of hard: soft (silicate: chromite) and coarse: fine particles in the AG mill fresh feed were tested. The effects of multi-component feed on the pilot scale autogenous grinding are presented in this paper, and can be used as a guideline for multi-component feed blends for AG mil

Jan 1, 2012

By Lisa J. Renaud

For generations, the mining industry has been committed to work toward developing new technology that can improve safety and increase production. Now with a more environmentally conscious society and tighter environmental regulations, a natural progression for the industry is to develop and take-on ?green? or environmentally friendly technologies. Not only could this improve the sustainability of operations, but could also reduce the long-term environmental impact footprint that is left behind. Algae represent a new frontier in research and development. As discussed specifically in this paper, algae, specifically microalgae, can be used for the production of biodiesel and other green chemicals by exploiting carbon dioxide and waste heat contained within process off-gasses. The potential positive benefits of this approach in terms of contribution to community and the environment are significant, and the focus of our research and development on microalgae production technology.

Oct 1, 2010

By P. E. Georghiou, S. Shafiei Zadeh, H. Hassan Nejad

Data are presented on the extractant behaviour on toxic metal removal from spent hydroprocessing catalyst, produced at the North Atlantic Refinery plant in Newfoundland and Labrador. Aliquat 336 was selected due to its potential capabilities for the separation of cobalt, molybdenum and nickel from the leachate extractant produced by aqua regia. The solvent extraction process was statistically modeled using central composite design (CCD), and the numerical optimization was conducted to achieve the optimum point for toxic metal recovery for the extractant.

Jan 1, 2014

By J. W. Merks

"The accuracy of a measurement on minerals and ores can be assured by applying suitable and unbiased procedures but its precision is a function of the number of primary increments and their mass, the number of lots per consignment or samples per shift, and the number of measurements on analysis fine samples.Experimental data will be used to show how the variance components for sampling, sample preparation and analysis contribute to the total variance on which precision statements for the final measurement are based. This type of experiment should not only form part of quality control programs at mines and smelters, but also underly the criteria on which the design of manual sampling regimes and mechanical sampling systems for bulk solids and slurries should be based.Sampling systems and regimes can only be adjusted and optimized if the variance component for each step in a quality evaluation process is measured. Knowledge of precision characteristics lies at the core of effective loss prevention and control programs."

Jan 1, 1985