Copper electrowinning using spouted-bed electrodes: Part I. Experiments with oxygen evolution or matte oxidation at the anode

Shirvanian

et al. 2011

Ind. Eng. Chem. Res.

An investigation is presented of nickel electrodeposition from acidic solutions in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on nickel removal/recovery rate, current efficiency, and corrosion rate of deposited nickel on the cathodic particles were explored under galvanostatic operation. Nitrogen sparging was used to decrease the dissolved oxygen concentration in the electrolyte in order to reduce the nickel corrosion rate, thereby increasing the nickel electrowinning rate and current efficiency. A numerical model of electrodeposition, including corrosion and mass transfer in the particulate cathode moving bed, is presented that describes the behavior of the experimental net nickel electrodeposition data quite well.

“…17 In one series of investigations, copper 18,19,20,21 and zinc 22 electrowinning were investigated. A rectangular cell design with sidewall electrodes was employed in this work.…”

Section: Introductionmentioning

confidence: 99%

II. Electrodeposition/Removal of Nickel in a Spouted Electrochemical Reactor

Grimshaw

Shirvanian

et al. 2011

Ind. Eng. Chem. Res.

“…12,13,14,15 Nickel electrodeposition in the same experimental apparatus used here has also been investigated in our laboratory. 16 Here we present results on the co-electrodeposition of copper and nickel from mixtures in acidic solutions in a spouted electrochemical reactor.…”

Section: Introductionmentioning

confidence: 99%

III. Co-electrodeposition/Removal of Copper and Nickel in a Spouted Electrochemical Reactor

Grimshaw

Hradil

2011

Ind. Eng. Chem. Res.

Results are presented of an investigation of co-electrodeposition of copper and nickel from acidic solution mixtures in a cylindrical spouted electrochemical reactor. The effects of solution pH, temperature, and applied current on metal removal/recovery rate, current efficiency, and corrosion of the deposited metals from the cathodic particles were examined under galvanostatic operation. The quantitative and qualitative behavior of co-electrodeposition of the two metals from their mixtures differs significantly from that of the individual single metal solutions. This is primarily attributed to the metal displacement reaction between Ni0 and Cu2+. This reaction effectively reduces copper corrosion, and amplifies that for nickel (at least at high concentrations). It also amplifies the separation of the deposition regimes of the two metals in time, which indicates that the recovery of each metal as a relatively pure deposit from the mixture is possible. It was also shown that nitrogen sparging considerably increases the observed net electrodeposition rates for both metals – considerably more so than from solutions with just the single metals alone. A numerical model of co-electrodeposition, corrosion, metal displacement, and mass transfer in the cylindrical spouted electrochemical reactor is presented that describes the behavior of the experimental copper and nickel removal data quite well.

“…There are relatively few studies in the literature on similar devices. Copper electrowinning from acidic solutions was examined in small, related devices by Jiricny et al [6], Stankovic and Stankovic [7], Masterson and Evans [8], and Scott [9]. Also, Evans and coworkers reported on zinc electrowinning in a spouted bed electrode [10].…”

Section: Introductionmentioning

confidence: 99%

Copper recovery in a spouted vessel electrolytic reactor (SBER)

Shirvanian

2005

J Appl Electrochem

An investigation of copper recovery from acidic solutions in a particulate, cylindrical spouted vessel of conductive particles is presented. The effects of current, initial copper ion concentration, supporting electrolyte concentration, particle loading, liquid flow rate, solution pH, and temperature on copper recovery rate, current efficiency and energy efficiency of the electrolytic deposition process were investigated under galvanostatic conditions. Experiments were also conducted to investigate the effects of backdissolution or 'backstripping' of the deposited metal in the acidic solution. It is hypothesized that the latter occurs via both chemical and electrochemical anodic oxidation in the bed of conductive particles. It was found that sparging of the electrolyte solution with selected gases to remove dissolved oxygen increased the current efficiency by as much as 30% under certain conditions. Finally, a numerical kinetic model of electrochemical deposition and backstripping, coupled with mass transfer in the particulate cathode bed, is presented that describes the behaviour of the net copper recovery curves reasonably well. List of symbolsa electrode area per unit volume (m )1 ) C j concentration of species j (mol m )3 ) C js concentration of species j at electrode surface (mol m )3 ) C metal cation concentration in solution, initial (ppm or mol m )3 ) C O initial metal cation concentration in solution, initial (ppm or mol m )3 )backstripping rate constant pre-exponential factor (ppm min )1 )/(mol kg )1 bar )1 ) K B backdissolution rate (mol m )3 s )1 ) K H Henry's law constant for oxygen in water (mol oxygen (kg water) -1 (bar )1 ) n apparent reaction order n j number of electrons in rate j r b backstripping rate (ppm min )1 ) r j rate of reaction or mass transport (mol m )3 s )1 ) R gas constant (J K )1 mol )1 ) Re p particle Reynolds number (= u d p /m) ScSchmidt number (= m/D) Sh particle Sherwood number (= k L d p /D) t time (s) T temperature (K) DH Ã 0 heat of activation at equilibrium potential (kJ mol )1 ) a transfer coefficient (Equation 10) m kinematic viscosity (m 2 s )1 )