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By B. Haugrud, E. McConaghy, M. Collins, G. Smith

"Laterite ore processed by the Ambatovy joint venture in Madagascar is primarily limonitic in nature, containing approximately 40–45 wt.% Fe and 1.1 wt.% Ni. The process selected for treatment of this ore considered the behaviour and deportment of iron in each step of the commercial flowsheet. Such considerations included nickel and cobalt recoveries, reagent consumptions, liquid-solid separation characteristics, and intermediate and final product purities. In this paper, the results for the first three years of commercial operation at Ambatovy are compared with the design parameters, with emphasis on the behaviour of iron.RÉSUMÉ Le minerai latéritique traité par l’entreprise commune Ambatovy au Madagascar contient principalement de la limonite, composée de 40–45 % en poids (wt%) de fer (Fe) et de 1,1 wt% de nickel (Ni). Le procédé choisi pour le traitement de ce minerai tenait compte du comportement et du maintien du fer à chaque étape du schéma de traitement commercial. Parmi les facteurs pris en compte figuraient les récupérations de nickel et de cobalt, les consommations d’agents réactifs, les caractéristiques de séparation des liquides-solides ainsi que la pureté des produits semi-fini et final. Cet article compare les résultats des trois premières années d’exploitation commerciale à Ambatovy aux paramètres d’étude, en insistant notamment sur le comportement du fer.INTRODUCTIONThe main component of nickeliferous laterite ore is iron, and the Ambatovy deposit in Madagascar is no exception. Ambatovy ore is primarily limonitic in nature, containing approximately 40–45 wt.% Fe and 1.1 wt.% Ni. The nickel content of the ore is approximately 1/40th that of the iron content by weight; therefore, successful recovery of nickel depends on close control of the behaviour of iron in the selected process.The Ambatovy area is located 80 km east of Antananarivo, the capital of Madagascar. Exploration dates back to 1960, when the Malagasy Service Géologique carried out a limited pitting and auger-drilling program. Phelps Dodge Corporation (now Freeport-McMoRan Copper & Gold, Inc.) was granted the mining rights to the property in 1995 and carried out significant resource definition, environmental assessment, and engineering studies between 1995 and 2001 (Chou, Rooke, Williams, & Hanks, 2000). In 2003, Dynatec Corporation, which was formed in 1997 by the merger of Dynatec International Ltd. and Sherritt International Consultants Inc., signed a joint venture agreement with subsidiaries of Phelps Dodge to evaluate the Ambatovy nickel project. Dynatec became extensively involved in the development of the project, including process selection and pilot plant testing in Fort Saskatchewan, Alberta (Collins et al., 2004, 2005; Collins & Vardill, 2005; Collins, Buban, Holloway, Masters, & Raudsepp, 2009). Dynatec acquired 100% of the project in 2005 and a joint venture between Dynatec, Sumitomo Corporation, Korea Resources Corporation (KORES), and SNC-Lavalin Inc. (SLI) was formed shortly thereafter to provide funding for further development. SLI was responsible for engineering, procurement, and construction management of the commercial facilities. Sherritt International Corporation reacquired Dynatec Corporation, including 40% ownership in the Ambatovy nickel project, in 2007. The current Ambatovy joint venture consists of an integrated nickel and cobalt mining, processing, refining, and marketing enterprise between subsidiaries of Sherritt (40% owner and mine and plant operator), Sumitomo Corporation (32.5% owner), and KORES (27.5% owner)."

Jan 1, 2017

By C. Allen

In 2004, Boliden Odda underwent an extensive modernisation project targeting mainly the leaching section of the plant. Direct leach technology was introduced as part of this project. The Direct Leach process, developed by Outokumpu, is an atmospheric oxidative leach of zinc sulphide concentrate. The effects of this new processing operation on behaviour of iron in the plant are discussed. As well, the filterability of the new residue on belt filters prior to its deposition in mountain caverns is also discussed. The solids from the direct leach process have been analysed by scanning electron microscopy, and the results of these analyses are presented.

Jan 1, 2006

By O A. Aladejebi, S Mitra, T Singh, D J. Pinson, S, S J. Chew, T Honey

Currently, many commercial sinter plants are exploring the potential addition of high-grade iron ore concentrates to improve the sinter grade. A better understanding of the ore blend, granule behaviour and green bed properties is critical to making this change and maintaining productivity in the sinter plant. This study compared the performance of a laboratory scale granulation drum to a commercial scale unit. The blend used was an Asia-Pacific style sinter blend containing iron ore concentrates. The operating conditions of the two granulation drums (laboratory and commercial scale) were fixed at the same Froude Number (0.00337), space factor (15 per cent) and residence time (4.5 mins). The granules were characterised by measuring their mean size, size distribution and green bed voidage. It was found that the laboratory scale granules were representative of commercial sinter plant granules at similar moisture content. When the moisture was fixed at ~6.9 per cent, granulation time had no significant effect. A further fundamental investigation was undertaken to measure the water holding capacity and intra-particle porosity of the individual ores used in this study. The kinetics of water absorption were measured which showed that water absorbs quickly into the ore particles within the first 60 seconds, slowing down until final saturation was attained after six hours. A linear relationship between the water holding capacity and intra-particle porosity was noted for different ore particle sizes. The results of this study provide a baseline understanding of the current commercial sinter blend and encourage exploring the specific effect of increasing the proportion of ultrafine concentrates in sintering in a future study.

Sep 18, 2023

By X. H. Zhang, J. G. Cai

This paper discusses the behaviour of large-span tunnels and caverns in hard rock in a major underground storage project. In-situ stresses were measured using hydraulic fracturing during site investigation and 3-D overcoring during construction, with both showing a horizontal stress ratio of 2-3 times the vertical stress. Rock reinforcement design was based on the Q-system combined with numerical modelling for special design cases. Tunnel design and performance were checked and monitored by in-situ instrumentation during rock excavation, including measurements of deformation, convergence, and load on rock bolts. Deformation measurements using borehole extensometers included one borehole drilled into the virgin rock before rock excavation, which provided a direct and very insightful comparison with the various deformation measurements made during rock excavation. These measurements coupled with numerical calculations have proven that the high horizontal stresses to be very favourable to the stability of the large openings.

Jan 1, 2003

By W. H. Craig

Techniques have been developed for installing model piles into beds of soil under high sustained acceleration levels aboard a centrifuge. These piles have been subjected to static and/or cyclic lateral loading in order to assess their performance and provide a data base for assessment of various design techniques for laterally-loaded single piles. From measured bending moment profiles the so-called 'p-y' curves have been deduced using fifth order splines for curve fitting, followed by subsequent differentiation and integration. The results show some divergence from the predictions of the semi-empirical designs, but these latter are generally found to be acceptable.

Jan 1, 2010

By M. R. MacIver, M. Pawlik, S. Finora, H. Alizadeh

The dispersion of mature fine oil sands tailings (MFT) by the addition of sodium lignosulfonate was studied using contact angle measurements, optical scattering, and particle size measurements. Lignosulfonate caused the release of residual bitumen to the slurry surface and settlement of fines. Dynamic contact angle by captive bubble measurements were carried out on bitumen to determine the effect of the dispersant on the wettability of bitumen. Lignosulfonate caused a change in the aggregation state of the MFT and increased sedimentation of particles, as indicated by optical scattering measurements. Zeta potential measurements indicate that this change was caused by an increase in adsorption of lignosulfonate onto particles, which caused improved settling of the colloid. Ultraviolet Visible (UV) spectrophotometry and organic carbon content measurements showed that only a small amount of the reagent remains in the aqueous phase of the tailings, which is critical for decontamination of recycled water. Keywords: Oil sands tailings, bitumen recovery, dewatering, dispersion, surface chemistry

Jan 1, 2020

By B. M. England, L. C. Mackey

Magnesia minerals are included in most iron ore sinter mixes to provide the MgO requirements of blast furnace slag. The properties of these minerals have an influence on the eventual sintering properties of the mixes. A detailed study was undertaken of serpentine and dolomite and the use of limestone, olivine and magnesite was also investigated. A consideration of particle properties indicated that as these materials calcine a reduction in size can occur together with cracking and changes in surface properties. These changes could affect the permeability of the sintering bed and sintering performance. Studies of sintering reactions showed that magnesium and calcium, formed from the calcination of dolomite, are extremely mobile before the formation of melt. Evidence suggests that the movement of these oxides into surrounding areas is via a solid-state diffusion process. The diffusion of Ca into the surrounding hematite particles is faster than that of Mg, resulting in the formation of dicalcium ferrite and magnetite or magnesioferrite, the last two subsequently being converted to dicalcium ferrite in the presence of Ca with removal of Mg from the structure as ferroan periclase. Studies of pilot-plant sinters indicated that reaction mechanisms formulated from the bench-scale studies were occurring in actual sintering processes. The differences in sintering reactions between dolomite and serpentine were considered to be the major cause of differences in the availability of lime for bonding phase formation. Pilot-scale studies indicated that the sintering properties of a mix containing dolomite could be improved by increasing the basicity of the sinter mix while keeping the MgO level constant

Jun 18, 1905

By M. Kreuh

Crystalline Mg(OH)Cl and amorphous Mg2(OH)3C1 were successfully isolated from a hydrolyzed molten salt electrolyte sample in this work, It was found that the chemical form and crystallinity of the hydroxylchloride were controlled by the cooling rate of the molten sample when it was taken. Crystalline Mg(OH)Cl could only be obtained by cooling the molten electrolyte sample at a rate not faster than 0.6 °C/min, Upon more rapid cooling, the hydroxylchloride species precipitated as Mg2(OH)3Cl, The behavior of these solid hydroxylchlorides when contacted with fresh and non-hydrolyzed molten electrolyte at 550°C was also examined, It was found that the Mg(OH)Cl rapidly dissolved in the hot electrolyte and did not decompose into MgO at that temperature as would be expected from the literature, The dissolution rate of solid Mg2(OH)3Cl was found to be so slow by comparison that it resulted in the complete decomposition into MgO which thereafter was incorporated into the electrolyte as a suspended solid phase rather than dissolution.

Jan 1, 2004

By Muto S, Okada S

At Tamano Smelter, part of the furnace settler is electrically heated by electrodes placed internally. This practice provides good control of the settler conditions. The authors have been investigating improvements in furnace operations, especially to decrease the copper content in the slag discarded from the settler. The important operational points on the control of magnetite in liquid matte and slag are discussed on the basis of the thermodynamic calculation method developed by Prof. S. Goto. The behaviour of magnetite in the practical furnace has been studied by using a torsion magnetometer and a solid electrolyte oxygen-sensing cell.

Jan 1, 1980

By Raymond E. Healy

Circuit samples from the HBMS concentrator were assayed for l5elements, and image analysis was done to determine the modal quantities, grain size distributions and liberations of the minerals. Material balancing was done on these data to determine distributions of the minerals in each concentrator stream. The ore was mined during the waning phase of mining and is diluted with backfilled copper smelter slag. The mill feed grades 1.0 wt% Cu and 1.8 wt% Zn. The slag silicate phases contain approximately 1.5 wt% Cu and 6.5 wt% Zn; therefore the Cu and Zn head grades due to chalcopyrite and sphalerite, are only 0.9 wt% Cu and 1.2 wt% Zn, respectively. The recovery of Cu in the Cu-concentrate (Cu-conc.) is only 77.5 %, whereas that of chalcopyrite is 89.2 %. Similarly, the recovery of Zn in the Zn-concentrate (Zn-conc.) is only 40.2 %, whereas that of sphalerite is 71.0 %. The slag accounts for approximately 60 % of the Cu, and 85 % of the Zn in the tailings. The main loss of chalcopyrite is as unliberated grains to the tailings, and the main loss of sphalerite is as free grains to the Cu-concentrate and as unliberated grains to the Cu-concentrate and tailings. Approximately 85 % of the chalcopyrite and sphalerite lost to the tailings. accounting for 8 % and 10 % of the respective minerals in the concentrator feed, occur as middling and sub-middling grains. Extremely fine regrinding would be required to liberate these minerals.

Jan 1, 1989

By Lassi Klemettinen, Ari Jokilaakso, Dmitry Sukhomlinov, Pekka Taskinen

The solubilities and distributions of molybdenum and iridium in iron silicate slag and copper-iron mattes were studied using an equilibration-quenching technique and subsequent direct phase composition analyses by EPMA (Electron Probe X-ray Microanalysis) and LA-ICP-MS (Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry). The equilibrations were carried out on a wide matte grade interval, ranging from 55 wt-% Cu to 75 wt-% Cu, in pSO2 = 0.1 atm at 1300°C. The results in equilibrium with a solid iridium-molybdenum alloy indicated an iridium solubility of 150–500 ppmw in the sulphide matte, depending on the matte grade, and a molybdenum solubility of 100–600 ppmw. Iridium was distributing predominantly in the sulphide matte with the distribution coefficient of 10+3 - +4 but molybdenum deported predominantly in the slag with Lm/s(Mo) = 0.02–0.1. The effects of alumina and lime additions in the smelting slag were also examined. INTRODUCTION Iridium is a highly siderophile element (HSE), which means that it is incompatible with the sulphide forming elements and possesses a small solubility in mattes, such as copper- and nickel-iron sulphide melts. Molybdenum behaves only modestly in that way (Walker & Li, 2008; Righter et al., 2017). They both are known to be trace elements accompanying copper and nickel sulphide ores. No solubility data, however, are available for them in copper-rich sulphide mattes. Geochemical data on the behaviour of Ir and Mo deal mostly with low-iron silicate systems, e.g. basaltic melts, and high-sulphur sulphide solutions and mattes (Ertel et al., 2008; Fonseca et al., 2007). They also indicate that Ir and Mo dissolve in silicate melts primarily as oxides and not as electrically neutral metal species. Most geological data of iridium focus on high-sulphur systems of the monosulphide composition and typically Fe-Ni mattes where copper is a trace element (Fleet et al., 1996; Sattari et al., 2002). Direct solubility measurements for mattes and iron-lean silicates have also been made using pure Ir or an Ir alloy as the saturation phase (Borisov & Palme, 2000; O’Neill & Eggins, 2002; Makovicky & Karup-Møller, 1999; Ertel et al., 2008; Mungall & Brenan, 2014). A recent summary about the solubilities of HSE’s in iron- and sulphur free silicates is available in Laurenz (2012). The thermodynamics of molybdenum partitioning between oxides and Fe-S-O melts was studied by Mengason et al. (2011). Their results indicate strong accumulation in the iron-rich sulphide in reducing conditions (pO2 = 10-9.6 atm in Ni-NiO equilibrium at 1050°C). Molybdenum dissolves in iron-lean silicate melts as MoO3 species in oxygen pressures above the Fe-FeO equilibrium and as MoO2 in more reducing conditions (Farges et al., 2006; Righter et al., 2017).

Jan 1, 2019

By A. Le Kouby

We present in this paper the results of a parametric study carried out in a calibration chamber on instrumented model piles. The aim is to point out group effect on piles within a group through their resulting shaft friction and tip resistance. The methodology relies on the study of the influence of adjacent piles on a "reference" pile. The soil used is a silica sand (Fontainebleau sand). The influence of parameters like pile spacing, number of piles and installation order are evaluated. The results show a positive effect on shaft friction of the group effect and a negative effect on tip resistance. Efficiency factors are defined in order to have a better view on the parameters influencing the response of the pile within a group.

Jan 1, 2006

By A. R. Sorta, D. C. Sego

ABSTRACT The settling, shear strength, and index properties of oil sands fines-sand mixture tailings (FSMT) for a wide range of solids and fines content are investigated. Results indicate that the liquid limit of FSMT obeys a linear mixture law. The fines-water ratio (FWR) governs the permeability of composite tailings (CT) and CT with comparable geotechnical behaviour can be produced from the same initial FWR mixtures. A phosphogypsum (PG) dosage > 900 mg/kg does not improve the dewatering behaviour of CT. The undrained shear strength of FSMT at the liquid limit is approximately 2.4 kPa, but is dependent on fines content at the plastic limit.

Jan 1, 2013

By J. Hadjigeorgiou, G. Knox

Since their introduction in 2010, paddled energy-absorbing rockbolts have been widely used in seismically active hard rock mines. This paper provides new data and reviews previous work to quantify the performance of paddled energy-absorbing rockbolts under controlled laboratory conditions. Of significance is the realization that the typical split location in impact tests, at the centre between two paddle anchor points can at best provide an upper limit value. This inherent variability in performance under different testing configurations should be acknowledged and taken into consideration in the design of ground support in seismic conditions. This paper discusses the reduction in capacity of paddled rockbolts as a function of loading angle from a maximum value during axial tests (0° loading angle) to the lowest value during pure shear (loading angle of 90°). A significant reduction in displacement capacity is observed as the loading angle changes between axial (0°) and 40°. Beyond a 40° loading angle up to shear (90°) loading the reduction in displacement capacity is less significant. Due to the variances in the capacity observed through the variance of the testing configuration: loading mechanism, direction of loading, location / presence of a discontinuity, it must be recognized that results from laboratory-based testing are not independent of the testing configuration. This should be acknowledged when extrapolating anticipated performance in the field.

Oct 9, 2024

By Yanagase T, Nakamura T, Ueda Y

The possibility of removing the phos phorus and sulphur contained in steelmaking slag has been studied by observing directly through the microscope melts heated on Pt- filaments. After a CaO crystal was placed in the molten slag, distributions of P, S and other elements formed around the CaO crystal were determined with the aid of EPMA. The results indicated that a layer of 2CaO SiO2 is formed on solid CaO in CaO-Si02 melts. Then between CaO and the newly formed compound the molten slag tends to migrate through cracks. For higher Fe 2 03 contents, the layers of the compounds 2CaO.Si02 and 3CaO SiO2 formed around the CaO crystal are not continuous but look more like particles, which promotes the dissolution of CaO. Phosphorus in slag was found to be enriched in the 2CaOòSi02 layer. Phosphorus in the 2CaO SiO2 phase is not related to the primary slag composition, being about 5-7% P205.. Sulphur in slag,as well as the phos- phorus,was concentrated in the 2CaO.Si02 phase. Disintegration due to weathering observed for slags produced in these investigations appeared to be due principally to hydration of lime.

Jan 1, 1980

By Abhirami B., V. Balakumar

Piled raft foundation system is an intelligent geotechnical concept, developed towards reducing the settlement of the raft and the footings by providing pile elements below the raft or footings, as the case maybe. Although a large volume of works has been done on the behaviour of piled rafts by observational studies, the effect of construction methodologies such as deep excavations, the installation methodologies used for piling etc appear to have not been covered adequately. This paper discusses the effect of deep excavations, pile installation techniques and the effect of adding structural elements, based on the data available from published literatures. Based on this study, the performance of the piled raft monitored by the author has been revisited and the results of such a study are discussed.

Nov 1, 2022

Fire-clay blocks lining the combustion chambers of zinc concentrate flash-roasting, furnaces operating at 1,000-1,200° C. have suffered moderately rapid deterioration due to slagging. The attack is accentuated by high temperatures, and is probably caused by lead oxide volatilized from the roasted concentrate.Resistance of refractories to attack increased with increasing alumina content from 30 to 45 per. cent but at 90 per cent alumina spalling was troublesome. Magnesite bricks were'subject to some spalling, but some types may lie satisfactory. Chrome and chrome-magnesite bricks spalled seriously.Material thought to be suitable for use as a monolithic lining slagged badly and an alternative may be tested.INTRODUCTIONThe Electrolytic Zinc Company of Australasia Ltd. uses two multi-hearth furnaces and four flash or suspension roasting furnaces for the roasting .of zinc concentrates at its Risdon Works. The hearth roasting plant has been described previously by Forster (1949).A brief descriptioI1 of the first three flash roasters was given by Gordon and Forster (1955). A fourth flash roasting furnace began operation early in 1957. This furnace is somewhat larger than the earlier furnaces, and the designed capacity is also higher, auxiliary equipment being altered to suit. An important structural difference between the older furnaces and the fourth flash roaster is that the walls of the combustion chamber of the new furnace are lined with high alumina fire-bricks instead of fire-clay blocks. Thischange was made because the fire-clay blocks in the older flash roasters had shown s-evere wastage due to slagging by lead derived from the concentrate.

Jan 1, 1959

By P. Chryssanthakis

"The aim of this study is to give a better understanding for the behaviour of the composite material RRS and the synergy effect of its components while an excavation face advances during tunneling. The lower part of the Q-system scale (i.e. Q-values of 0.4 or less for a tunnel span of 10 m) is commonly used for tunnel applications in softer rock formations. This is implied in the updated Q-chart, where the dimensioning of rock support by using Reinforced Ribs of Shotcrete (RRS) comprises the use of fiber reinforced shotcrete, S(fr), rock bolts and shotcreted beams reinforced with steel rebars. The newest part of the lower part of the Q-chart gives more information on required support compared to older Q-system versions. The RRS can be described as a three part composite material with the 3rd component being the reinforced concrete beam (with no fibers) and with steel rebars that are placed in groups and sprayed with pneumatically applied shotcrete in layers. The RRS usually have a total thickness varying between 0.20 and 0.50 m and a width between 0.25 and 0.60 m respectively. They are placed at different distances along the tunnel axis depending on the rock mass quality.In this study, an effort has been made to simulate RRS in a numerical code and to study its behaviour in a real case study. A double tube, triple lane tunnel in weathered tuff has been chosen as reference material for testing RRS under changing load. This was done by writing a FISH subroutine which is implemented in the discontinuous numerical code Universal Distinct Element Code (UDEC) that takes into account the characteristics of the reinforced beam (height, width, number of steel rebars, and spacing) in the calculation process. A rather extensive parametric study has been run by using the same key input rock mass parameters and in situ stresses (?H/?v = 0.5), and changing only the RRS key input parameters in order to simulate the changing loads during the face excavation process in tunneling. The critical part of this numerical modelling work that is under investigation in this study, is the period just after the excavation: i.e 4 hours; 16 hours after excavation; and finally after the complete curing (28 days) of the cement based components. The RRS are installed in three consecutive steps as follows: a) the application of S(fr) on the rock surface in order to even it up for the RRS application; b) radial bolting; and c) installation of the reinforcing steel rebars, that form the reinforced beam.The results show that: a) the S(fr) is almost overloaded in the first 4 hours after application in both tunnels; b) on the S(fr) and steel rebars, the stresses, axial and shear loads, as well as moments are decreasing after 16 hours and 28 days; and c) the bolts loads are increasing with time. The observed reduction in stresses and loads in both the S(fr) and reinforced beam is surprising. A possible explanation is that tunnel arches are self-supported to a lesser extent as time progresses due to redistribution of stresses in the nearby rock mass through the radial bolts. The loads in radial bolts are increasing by almost 25%. This can be seen from the overall results as we observe an increase in maximum principal stresses, displacements, shear displacements along joints and hydraulic apertures compared to tunnel baseline that has no support of any kind."

Jan 1, 2015

By Dennis Z. F. Mraz

"Because rock salt and pot ash formations contain particles capable of elastic deformation, the material has usually been compared with various rheological models containing elastic elements. Extensive laboratory testing of salt and potash samples resulted in various theoretical conclusions based on conditions quite different from those in a deep mine. It is felt that sufficient data have now been collected from underground measurements and observations to demonstrate the inelastic behaviour of salt masses in a deep mine. The conditions in deep salt strata can be defined as near hydrostatic, because the acting pressures are very high compared to the negligible elastic limit of the salt. The pressure field and creep around the single opening is a function of its shape, size and age. The same factors, together with extraction, determine the behaviour of the mining a rea. The application of the correct analytical method in mine design can significantly improve the excavation techniques and predetermine the long-term behaviour of openings."

Jan 1, 1973

By O. Benavente, M. C. Hernández

Selenium is obtained mainly from copper anode slimes, which is a by-product of the copper electrorefining process. Selenium is present in copper anode slimes as silver and copper selenides. Traditionally, selenium has been obtained by pyrometallurgical processes; however, hydrometallurgy has now been incorporated either full or partial to the conventional process. Some hydrometallurgical processes are been developed and used at laboratory level an industrial scale. This document describes theoretical background and results of characterization and dissolution of selenium from a decopperized anode slimes in an alkaline oxidizing system. The results have indicated that the oxidizing leaching process reaches a practically complete dissolution of selenium (up to 90 %); the undissolved portion is due to the generation of a AgCl around the particle surfaces that delays the progression of the reaction. The results indicated that 90% of selenium extraction can be obtained by dissolution under moderate conditions of pH, temperature and reagent concentration in oxidizing medium. INTRODUCTION Selenium is distributed in the earth's crust in most rocks and soils. Selenium is essential, as it has wide range of applications in the medical and food industries as well as, used in semiconductor, sensors and photochemical devices. Selenium is rarely found in the native state, 90% of selenium is obtained from copper anode slimes, which is a byproduct of the copper electrorefining process (Lu, Chang, Yang, & Xie, 2015; Xiao et al., 2017; Yang et al., 2018). In anode slimes, selenium is present as an intermetallic compound, as Ag-Cu selenides. Currently, selenium is recovered from the anode slimes via hydrometallurgical and pyrometallurgical processes (Lu et al., 2015). The traditional pyrometallurgical method recovers selenium effectively, but faces difficulty as a result of increased energy costs and strict environmental regulations associated with the process (Li, Yang, Jin, Chen, & Tong, 2017). Therefore, hydrometallurgical processes are proposed in oxidizing medium such as nitric acid, alkaline leaching with sodium nitrate, wet chlorination and pressure leaching, amongst others (Hait, Jana, & Sanyal, 2012; Kim & Wang, 2010; Xiao et al., 2017; Yang et al., 2018).

Jan 1, 2019