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By A. C. de Araujo, M. G. Barbosa, R. Martino, S. Gaydardzhiev

The Iron Quadrangle district is a world-class iron ore mining district in the region of Belo Horizonte, capital of Minas Gerais state, in Brazil. Many mining companies have been mining high-grade hematite ores for decades throughout the region. The mines reserves often include itabirite ores which are available in high volumes, but have lower iron grades than hematite ores and require elaborated mineral processing to meet the requirements of downstream steelmaking. Itabirite ores have acquired importance, with the depletion of high-grade hematite reserves due to their intensive mining. The objective of this paper is to propose a geometallurgical model for the processing of itabirite ores from an Iron Quadrangle deposit, which will allow predicting the behaviour of ores throughout the deposit, according to their local variations. An initial step consists in characterizing representative samples of the different ores to acquire mineralogical and textural data. Then, itabirite ores of known characteristics are processed with different techniques, in order to extract the trends and key parameters upon which the geometallurgical model is developed. At first, the model takes into account the particle size distribution and its shift during mining and screening, as well as the chemistry and mineralogy of the material. Then, using the previously identified key parameters such as iron recovery, the model predicts the composition of the processing products. Finally, this data is used to model the mineralogy and mass recovery of the products. The geometallurgical model is of great importance, as it is able to model the processing of any sampled ore throughout the deposit. The incorporation of the results in a mining block model will assist mine planning and opens new opportunities for an optimized mining schedule.

Jan 1, 2016

By A. R. Farkoosh

Al-Si based alloys have been recently used by automotive industry for highly stressed engine applications. Due to severe working conditions of the engine parts, existing alloys hardly endure high pressures at high temperatures. This necessitates alloy modifications to enhance the elevated temperature performance. In this study, the effects of trace nickel additions on the microstructural and mechanical properties of A356+0.5Cu alloy have been investigated at different aging conditions. Electron probe microanalysis (EPMA), scanning electron microscopy (SEM) and X-ray diffraction (XRD) are used to study the microstructural changes. Aging curves have been obtained by hardness measurement. It was seen that the presence of additional nickel introduced many complex intermetallic phases within the microstructure which led to improved high temperature mechanical and aging response.

Jan 1, 2011

By C. S. Crocker

The Centennial orebody was discovered and named in 1970, Manitoba's centennial year. It is relatively small, about 2 million tons. Strike length varies from 400 to 600 feet and widths from 10 to 60 feet; dip is 75 degrees. Low grade and metal prices demanded low-cost mining, and the mine was developed for conventional sublevel stoping. As the ore lay entirely under a large lake, ground movement had to be avoided and the stopes were to be filled hydraulically. Late in 1973, vertical crater retreat mining was introduced at Inco Limited, Sudbury, to recover pillars between filled stopes. It proved satisfactory and the results were publicized by CIL, who developed the technique. The method seemed to offer some advantages and one stope at Centennial Mine was selected to be mined by VCR while production was maintained from blasthole stopes. The trial stope was safe and showed lower development costs, reduced drilling time, a favourable powder factor and good fragmentation. VCR mining is now an accepted method at HBM&S Co., Ltd., and its use is being extended.

Jan 1, 1979

By F. Calizaya, S. Bhattacharyya

"This study presents the results of a set of sound level measurements carried out in three underground mines where auxiliary fans are used regularly. Sound levels as high as 100 dB(A) by the workings and 115 dB(A) by the fans were measured in these mines. These levels are quite high even for intermittent noise. Ventilation layouts and best practices used to overcome potential problems related to overexposure to fan noise in underground hard-rock mines are presented here. Factors such as fan type, rotational speed, and silencer-duct arrangements and their effects on noise attenuation are discussed. INTRODUCTION Auxiliary fans are used in hard-rock mines extensively. They are used to ventilate development headings, crusher rooms, conveyor transfer points, and underground shops. They are also used in developing long tunnels and ramps. Depending on the flow requirements and space restrictions, single or double stage axial fans with rigid or flexible ducts are used. Usually, they are high pressure (3.75 kPa) fans with flow rates ranging from 7.1 m3/s to 30 m3/s. The input power varies from 15 kW to 113 kW (Mutama, 2004; O’Connor, 2008). Typically, a 113 kW fan can produce sound levels as high a 113 dB(A) (Howes, 2005). Silencers are often omitted for cost reduction purposes or when used, they are not well maintained. Furthermore, silencers provide limited attenuation depending on their length and type. Typically, the sound attenuation ranges from 10 dB(A) for a 1 × D silencer to 14 dB(A) for a 2 × D silencer, where D is the fan diameter. In a mine, the silencer is subject to wear and tear, especially when the silencer is used in harsh environments. The interior lining can get clogged and the acoustic fill can get covered by dust and diesel soot, thus reducing the silencer performance. Periodic cleaning of the interior casing can increase the attenuation capacity of a silencer by 6 to 9 dB(A) (Dabson & Acuña, 2017). However, this requires a special silencer design in which the inner cartridge can be removed, the sound absorbing material replaced, the inner casing cleaned and the whole set retrofitted. A number of techniques can be used to reduce auxiliary fan noise in underground mines. These range from selecting the right fan for the job to installing adequate silencers. The choice depends on the air quantity requirement at the working place, cross-sectional area of the opening, duct diameter, fan type (axial or centrifugal) and local restrictions. Auxiliary ventilation layouts and best practices used to overcome potential problems related to overexposure to fan noise in underground hard rock mines are presented here. Factors such as fan type, rotational speed, duct diameter, and silencer-duct arrangements and their effects on noise attenuation are discussed."

Jan 1, 2019

The steam-filtration process for dewatering solids involves the application of slightly superheated steam to a filter cake during filtration. The mechanism by which the technique promotes water removal has been deduced from bench-scale experiments on coal and on granular iron ore concentrates. The mechanism, along with some of the applications and limitations of the process, is presented. Introduction I N the steam-filtration process, slightly super-heated steam is applied to the filter cake during filtration to remove more water than can be extracted by conventional filtration. Although this process was developed by Burton for coal filtration (1), it should have far wider applicability; certainly, it could be used to treat any mineral product, because only low-temperature steam is needed and most conventional filtration equipment can be easily adapted to it. As few restrictions apply to this process, however, it is important that its more obvious advantages and disadvantages be appreciated and, especially, that the criteria on which economic evaluations can be based are understood.

Jan 1, 1965

By Michael Bauer

Increases in productivity and improvements in mining occupational safety and health are intrinsically linked. Over the past years, the German Hard Coal Mining Industry has been able to accomplish both: an increase in coal production and, at the same time, a significantly reduction of accidents. This success has been achieved by advances in technology, better organization and investment in people. Since 1990 productivity has more than doubled, while the total number of accidents has been reduced by more than 90%. Further development started initially with the mechanisation of the winning and drivage technology. Innovative technology and standardisation of the mining equipment were one reason for the increase in productivity and reduction of the accident rate. Therefore this technical development was not only one important pillar of the TOM model explicated later but also the requirement for the successful development of the other pillars. In addition to further developing this innovative technology it was possible to realise procedural and organisational improvements. As a result, the above achievement is based on implementing the three pillars of the so-called "TOM" model (technology, organization, ?Mensch? = human). To increase safety, improve performance, raise awareness and change of employees? attitude, the following technical and organizational requirements have been introduced: ??New innovative technology and procedures, standardized techniques and better equipment. ??Measures to revise or redefine the organizational structure, processes and systems of work, which were then integrated into the company policy and procedures as a company management tool. ??Personnel measures (investment in people). These include, improving motivation and behaviour, training, communication to raise and to change awareness of safety issues. Success in Occupational Health and Safety is not an automatic or self-regulating process. It needs hard work to make improvements and it must be treated as a recurring cyclic process. As a result of the above, occupational health and safety has become a natural part of daily work in the German Hard Coal Mining Industry. This could only be achieved by the unconditional "commitment" of all managers and employees to the issues, coupled with discipline and responsible action. Further improvements towards the ultimate aim of "zero" accidents are only possible by mutual involvement in implementing the ?TOM? (technology, organization and ?Mensch? human) model.

Aug 1, 2013

By T. Plikas, L. Gunnewiek

Computational fluid dynamics (CFD) modeling was used to evaluate the performance and optimize the design of a potroom ventilation system in an aluminium smelter facility. The ventilation system must ensure the inflow of fresh air to the workplace by natural draft and the removal of heat and hazardous emissions generated from the pot cell process. A full-scale, three dimensional CFD model of the potroom was developed to predict the air temperature distribution and contaminant concentrations throughout the potroom for the purpose of verifying that the industrial workplace hygiene standards will be met by the proposed ventilation system design. The modeling work was used to optimize the size of the floor gratings around the pot cell and roof ventilator, as well as determine damper settings in the roof ventilator. The effects of outside air temperature and external wind on the performance of the ventilation system was evaluated to ensure the design performs adequately in response to seasonal variations in climatological conditions.

Jan 1, 2006

By A. Taylor, E. Thorn Corthay, J. Farrell, L. A. Westfall, S. Borchardt

Mining and metallurgical industries need to minimize their greenhouse gas (GHG) emissions; Hatch specializes in conducting mining and metallurgical energy management assessments and optimizing productivity. Projects executed have demonstrated that there is a wealth of energy management, waste reduction, and process efficiency improvements that require no or low capital investment. Typical energy cost savings are on the order of 5% to 12%, with similar reductions in GHG emissions. Hatch generates Marginal Abatement Cost Curves to optimize the implementation pathway, maximizing carbon abatement and minimizing cost. The findings of a practical case study from Cameco are presented.

Jan 1, 2010

By T. H. Patching, M. W. Mikhail

"The gas sorption and emission characteristic of coals are important to the planning and conduct of mining operations. Methane drainage from coal strata can also provide a supply of fuel in certain circumstances. Gas emissions have also created hazards during the handling and transport of coals and the release of gas also appears to be related to the yield of fine sizes during mining and processing operations.This paper summarizes studies at the University of Alberta on the permeability and gas emission of certain bituminous coals. Permeability of 'solid' samples was found to be drastically reduced by confining pressure. An emission index, .P, which has been related to outbursting behaviour of coals, has also been related to the proportion of fine s in cleaning plants. Gas sorption isotherms are dependent on temperature, moisture content, the gas involved and the type of coal and can be approximately expressed by the Langmuir or the Freundlich equations. Sorption values in sections taken across a given seam were similar but considerable differences were found in . P indices in the different coal layers of a seam.IntroductionThe emission of gases, especially of methane, from coal has been a subject of great interest (and sometimes a matter of life and death), to those who dig and handle coal since it was first mined from underground pit s. Many studies and investigations have been carried out on gas occurrences and emissions but our knowledge of the precise mechanisms of gas sorption, desorption and flow from coal is still incomplete. It is the purpose of this paper to review the principal factors involved in these processes and to briefly rep ort some of the results that have been obtained by studies in the laboratories of the Department of Mineral Engineering, University of Alberta, and Coal Research Laboratory, Edmonton, CANMET"

Jan 1, 1986

By Aysan Molaei, Kristian E. Waters

"Solvent extraction is the one of the most common techniques for recovering metal ions from aqueous systems. However, it is not efficient in the extraction of low concentration metal ions from aqueous solutions. Predispersed solvent extraction (PDSE) is an alternative method for solvent extraction which implies colloidal liquid aphrons as extracting agents in order to reach higher interfacial area and lower reagent consumption. This work investigated important parameters in PDSE of nickel ions from dilute aqueous solutions by fractional factorial design of experiments. Four experimental parameters, the initial extractant concentration, initial surfactant concentration, equilibrium pH and phase volume ratio (organic to aqueous ratio) were investigated. The important parameters were determined as well as important interactions between these parameters. It was found that extractant concentration, phase volume ratio, and equilibrium pH are the most significant experimental parameters. However, the interaction between surfactant concentration and other parameters was determined as significant interactions.INTRODUCTIONNickel is one of the key components found in cars, mobile phones, rechargeable batteries, kitchen appliances, and steel industry (Anyadike, 2002). It is one of the most important metals produced by Canada which is in the five top nickel producers in the world. Despite a 24% decrease in the nickel prices from 2011 to 2014 the nickel global mine production increased by 36% between these years (U.S. Geological Survey, 2015; Nickel - Statista Dossier, 2015), which shows the increasing demand for nickel. This high demand leads producers to consider the production of nickel from low grade ores and other secondary sources such as process wastewaters. The removal of nickel ions from process wastewater is also important due to environmental considerations. Nickel is known to be a human carcinogen and it may cause serious lung and kidney problems, pulmonary fibrosis, gastrointestinal distress, and skin dermatitis if it exceeds the critical level (Borba et al., 2006; Fu & Wang, 2011)."

Jan 1, 2016

"In 1989, improved milling and recoveries resulted in a record production of 7 722 200 Ib Nb2P5 at the Niobec Mine. At the beginning of 1990, proven and probable reserves stood at 11 952 000 tons grading 0.65% Nb205. This year, the world steel market has slowed and as a result, niobium consumption is down. Consequently, production at the mine dropped 14% for the second quarter.IntroductionThe Niobec Mine is located approximately nine miles northwest of Chicoutimi, Quebec, (Fig. I). After ten years of production, the Niobec Mine is the only operating niobium mine in North America and the second largest producer of niobium in the world after Brazil.The Niobec Mine is a joint venture held equally by Teck Corporation and Carnbior. Teck Corporation operates the mine while Cambior is responsible for marketing and selling the niobium pentoxide concentrate (Nb2P5).The deposit was discovered in 1964 following an airborne radiometric survey in search of uranium. However, mining of the deposit did not begin until 1976. The initial production capacity of 1500 tons per day was increased several times to the present capacity of 2450 tons . The deposit is considered as an ample source of pyrochlore concentrate for at least 15 years at the present production rate.Niobium, also known as columbium, is a greyish-white metal used primarily as an alloy in various steels and other metals. The use of niobium in alloys heightens tensile strength and improves corrosion resistance while at the same time reducing the weight of the alloy. Niobium is also used in the fabrication of steel for the aerospace, automobile, and oil and gas pipeline industries. Although substitutes for niobium exist, their use often results in diminished performance and net cost increases."

Jan 1, 1990

By Jason Mewis

Jason Mewis is the founder and president of ENGCOMP, a consulting engineering firm in Saskatoon Saskatchewan focusing on the mining sector. He has over 17 years of experience working on projects for the heavy industrial market in Saskatchewan, as both a Senior Structural Engineer and Project Manager. Jason is an entrepreneur with experience in many areas including estimating, planning, facilitation, and Risk Analysis. He has presented at many seminars and conferences across North America on the subject of Project Risk and and has become recognized for his expertise in this area of project management.

May 1, 2013

By Carmen Mihaela Neculita

Sulfate-reducing passive bioreactors efficiently treat acid mine drainage (AMD) by increasing its pH and alkalinity and by removing metals as sulfide precipitates, in addition to hydroxides and carbonates. However, the new mining legislation sets discharge limits based on physicochemical parameters and on the non-toxicity of treated effluent as well. In this study, toxicity was assessed for effluent from 3.5 L column bioreactors filled with mixtures of natural organic carbon sources and operated at two different hydraulic retention times (HRTs) of 7.3 d and 10 d for the treatment of a highly contaminated AMD. Acute toxicity was observed for D. magna, and a toxicity identification evaluation (TIE) procedure was performed to identify potential toxicants. To help the interpretation of the toxicity results, metal partition in the effluent was also determined by filtration and ultrafiltration, while geochemical modeling was performed for metal speciation evaluation. The 10 d HRT effluent was nonacutely lethal for rainbow trout but acutely lethal for D. magna, whereas the 7.3 d HRT effluent was toxic for both organisms. The toxicity to D. magna was eliminated by 2 h of aeration for the 10 d HRT effluent, and the TIE procedure suggested iron as a cause of toxicity. However, the 2 h aeration eliminated the toxicity of the 7.3 d HRT effluent, only if performed after the pH rising to 9.3. Data regarding metal speciation indicated instability of both effluents during aeration and were consistent with the toxicity being caused by iron. The study indicates that design of passive treatment should include sufficient HRT and posttreatment aeration to meet acute toxicity requirements. Keywords: acid mine drainage, sulphate-reducing passive bioreactors, hydraulic retention time, effluent toxicity, metal speciation

Nov 1, 2008

By C. B. Ndimande, C. Ntsele, M. Lisso, L. Arlow

"In the processing of UG2 platinum ore, stirred milling technologies are dominating regrind applications that require grinding the particles to P80s’ in the region of 45 µm. For this application stirred mills are 30–40% more energy efficient and require a smaller foot print compared to traditional tumbling mills. In this work a study was carried out using a batch pin mill and three scales of Stirred Media Detritors. A laboratory scale pin mill, a pilot scale Stirred Media Detritor with an installed power of 18.5 KW and two industrial scale Stirred Media Detritors in continuous operation, with an installed power of 355 KW and 1,100 KW were used. The industrial scale SMDs were in the secondary grinding section of a mill floatmill float (MF2) UG2 processing plants. The tests were focused on assessing the effect of feed rate and percent solids on power consumption and product fineness at lab scale, floatation response of the SMD product at pilot scale and on an industrial scale, the effect of feed rate on energy consumption and product fineness. The measurements obtained were feed flow rates, mill power and from the samples cut, particle size distribution of both feed and product. Specific energy was observed to increase with increasing percent solids over the 30wt% to 80wt% studied. Floatation response tests of the pilot scale SMD products show improvement in grade. Specific energy and reduction rations are observed to decrease with an increase in feed rate.INTRODUCTIONThe purpose of comminution in most mineral processing applications is to liberate the valuable minerals from gangue so that they can be recovered in subsequent separation stages. Most precious and base metal plants treat low grade fine-grained ores which require a higher degree of size reduction to yield the necessary degree of liberation (Partyka & Yan, 2007). Many authors have shown that the relationship between product size and grinding energy consumption is exponential, the finer the product from the comminution device, the higher the energy consumption (Gao & Weller 1993; Napier-Munn, Morell, Morrison & Kojovic, 1996; Jankovic, Valery & La Rosa, 2003). The suggested reason for this kind of relationship is that smaller particles have fewer flaws and higher strength than larger particles. Particles with fewer flaws and higher strength require higher energy for breakage to occur. One of the challenges most plants face is that of efficient energy utilisation in the liberation of the mineral from these complex ores. Conventional tumbling mills are not energy efficient in fine and ultra-fine grinding applications because some of the energy is spent on moving the charge and does not go directly into breakage. Stirred mills have been found to be about 30% to 40% more efficient and require a smaller foot print compared to traditional tumbling mills for regrind applications that require product size with P80s’ in the sub 45 µm regions (Radziszewski & Allen, 2013). Stirred mills are able to produce fine product because they can achieve a high number of stress events per unit time and volume compared to tumbling mills (Kwade, 1999a). To minimise energy usage without compromising product quality, the mining industry has adopted stirred milling technologies for fine and ultra-fine grinding (Radziszewski & Allen 2014; Kwade, 1999b). The south Africa platinum group metal (PGM) industry alone had over 40 stirred media mills installed by 2011 (Rule, 2011). Of that 40, 13 were in the ultra-fine grinding (UFG) application and the rest in main stream inert grinding (MIG)."

Jan 1, 2016

By J. Qi

Based on the commercial steel 42CrMo (4140, SCM440), a new generation of CrMo steel was developed by increasing the content of Mo, adding the alloy element of V and Nb, and decreasing the content of P and S. This new CrMo steel has higher strength of 1500MPa and better delayed failure property. TEM and EDS were used to study the distribution and function of the alloying elements in this steel. A new EELS technique was developed to study the bonding strength of the grain boundary in the steel. The mechanism of strengthening of the new steel has been studied.

Jan 1, 2004

By T. R. Chari

The safe-level dilution of low-level radioactive wastes in large volumes of selected granular material is proposed as an alternative method of permanent waste disposal to current Canadian practice of concentration and encapsulation. Accepting the fact that a "background level" of radioactivity exists throughout the world, the authors feel that the concept of controlled dilution of radioactive wastes to a level in keeping with "background" is a plausible alternative to current thinking on the subject and is worthy of equal consideration.

Jan 1, 1979

By L. A. Forsyth

"SINCE I received and accepted your invitation to present to this meeting a paper on A Canadian Integrated Coal and Steel Industry, I have given the subject a great deal of intensive study.Two conclusions have emerged from my considerations: first, that the subject should be dealt with by a person having a firm grasp of its technical aspects; and second, that it is a subject which requires expert analysis of the complicated problems it presents in pure economics.A third conclusion inevitably results from the two just mentioned -namely, that the mantle of the prophet which has been draped up-on my shoulders is too large for me to wear, because I am neither a practical nor a theoretical coal and steel man; and I am not an economist.With the warning that I have discovered, and am keenly conscious of, the inadequacy of my background for the task, I shall attempt to place before you those aspects of my subject which appear to high-light it from a layman's point of view.In the first place, in .order to avoid confusion as between my audience and myself, some definition of terms may be required.As I interpret it I am discussing -a coal and steel industry, using the last word in the generic and not the unit sense, self-sufficient in the provision of all its needs from within the geographical limits of Canada.Now, I start with the proposition that, in the very broadest aspects of such a concept, the Corporation of which I happen to be the executive head meets my definition as a combination of operations resulting in one fully integrated unit of a coal and steel industry."

Jan 1, 1952

By F. S. Hoseinian, M. Irannajad, M. Safari

In this study, the effect of chemical interactions of materials used in ion flotation on the removal of Ni(II) ions from low concentration synthetic wastewater was studied. Sodium dodecyl sulfate (SDS) and ethylhexadecyldimethylammonium bromide (EHDABr) as collectors and methyl isobutyl carbonyl (MIBC) and Dowfroth250 as frothers were used. To investigate the effective parameters and interactions of them, 16 experiments including 6 level variables were performed by supporting DX7 software and on the bases of 2-level factorial method. In the first step, the tests were conducted in a Hallimond tube. The result showed that collector of SDS and frother of Dowfroth 250 had appropriate interaction with each other at pH = 3. In the second step, optimal results from the first step were evaluated in a mechanical flotation cell. The removal of Ni(II) ions increased by increasing the time of flotation and they have a direct relation with the water removal. The kinetics study shows that the order and the rate of removal of the reaction do not follow any of the zero-order, first-order and second-order equations. The flotation rate curve on the removal of Ni(II) ions will divide the separation process to two stages, a fast flotation rate at the first stage and a slow flotation rate at the second stage. Ni(II) ions removal was obtained 88% at the best condition.This study showed that the use of ion flotation was a very effective method for Ni(II) ion removal from industrial wastewaters.

Jan 1, 2016

By David Rahal, Saul Ortiz, Maria Escobedo

The general trend in the minerals industry is towards the processing of fine grained, disseminated mineral deposits. This has led to an increase in the number of fine/ultra-fine grinding installations using stirred media mills. The challenge is that both the equipment type and the mineralogy of the deposit have an effect on specific energy consumption. Fresnillo PLC recognized this issue and addressed it by providing samples for testing in a laboratory regrind system. The objective of the test program was to determine the specific energy required to achieve a product size of 10 µm (P80). A specific energy plot was generated for both a lead and zinc flotation concentrate. It indicated that 34 kWh/t and 51 kWh/t were required for the two samples (Pb and Zn respectively). This difference highlights the effect of mineralogy on the energy required for fine grinding. The regrind feed and products were submitted to a range of basic mineralogy tests to quantify the mineral differences that could have changed the specific energy requirements. These tests provided general mineralogy, documented optical textures, and provided particle size microscopy. The lead concentrate was found to contain significant amounts of silicates in addition to the dominant sulphide, pyrite. The zinc concentrate was determined to be mostly sphalerite with minor amounts of quartz, chalcopyrite, pyrite and galena. The material testing results illustrate the importance of basic mineralogy studies in conjunction with comminution testing to determine specific energy consumption.

Jan 1, 2016

By H. Deveci, E. Y. Yazici, A. D. Bas

The leach solutions of waste of printed circuit boards (WPCB) may contain a wide range of base and precious metals with different concentrations due to heterogeneity of these wastes in composition. Therefore, selection of a suitable metal recovery method is of practical importance for downstream processing of pregnant leach solutions of WPCB. Sulphuric acid leaching of WPCB in the presence of a suitable oxidant is capable of dissolving base metals as well as precious metals such as silver. In this study, cementation of silver from sulphuric acid leach solutions of WPCB using metallic copper, aluminum and zinc was studied. The WPCB sample was assayed to have a silver content of 694 g/t. A synthetic leach solution containing 20 mg/L Ag in sulphuric acid solution (0.51 M H2SO4) was prepared based on the silver concentration in pregnant leach solutions of oxidative sulphuric acid leaching tests. Total sulphate concentration ([SO4 2-]T) was kept constant using sodium sulphate at 1 M. Metallic powders of copper (-850 +600 µm), aluminum (-425 +45 µm) and zinc (-45 µm) were used in the cementation tests. The effects of metal type (Cu, Al or Zn), dosage of metal powders (above the stoichiometric ratio by up to 2000-fold) and temperature (20-80°C) on the rate and extent of silver extraction from the solution was investigated. The effect of presence of copper on the cementation performance was also tested. Under suitable conditions high silver recoveries (>90%) was achieved using metallic copper and zinc while aluminum yielded the lowest silver recovery (i.e. 40% Ag). The kinetics of cementation by zinc was comparatively higher than that of other metals. Increasing the temperature was observed to significantly enhance both the rate and extent of silver cementation. SEM-EDS studies were performed to characterise the metallic powders after cementation.

Jan 1, 2016