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My Library Account Login Researching From Home? EZproxy Login Need Citation Management? UBC Theses and Dissertations. ANALYSIS OF T H E FIRST-STAGE L E A C H PROCESS A T INCO LTD. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the head of my department or by his or her representatives. It is understood that copying or publication of this thesis for financial gain shall not be allowed without my written permission.
Department of M e t a l s and M a t e r i a l s The University of British Columbia Vancouver, B. Copper Refinery Electrowinning Department CRED in Copper Cliff, Ontario, processes a Cu, Ni, Co, Fe, As, S and precious metals containing residue produced by the INCO Pressure Carbonyl IPC plant. This residue is treated batchwise in two successive leaching stages. The non-oxidative First-Stage Leach FSL process extracts the vast majority of the Ni, Co, Fe and As values.
The Second-Stage Leach SSL process comprises the aqueous pressure oxidation of a predominantly Cu S feed under acid-deficient conditions. The present study is part of a joint INCO-UBC research effort aiming at the optimization of both leaching stages. The purpose of this project is to provide a better understanding of the first-stage chemistry in general and of the behavior of arsenic in particular, since elevated concentrations of this element are detrimental to the efficiency of the second-stage system.
The test work shows that the FSL process is insensitive to physicomechanical parameters such as agitation rate and pulp density, as long as the "solids off-bottom condition" is satisfied. In contrast, the effect of temperature and reactor residence time on impurity extraction is pronounced, especially in the case of arsenic. On the basis of thermodynamics and experimental observations made in the course of the investigations, a tentative reaction model is proposed to explain reprecipitation of this element and nickel under copper-depleted first-stage conditions.
The presence of organic electrowinning additives in solution does not influence the Ni, Co, Fe and As recoveries achieved in the first stage. The iron and, to a lesser extent, nickel extraction depend on the availability of acid in solution, whereas cobalt is leached principally by metathesis reactions. Two scenarios for the leaching of arsenic are postulated, yet neither one can be confirmed; the concentration of arsenic is either below the detection limit of the equipment XRD or is obscured by the presence of other elements SEM.
Arsenic redissolution from a copper-depleted FSL batch cannot be accomplished by the introduction of pregnant copper electrolyte to the first-stage flash tank under the conditions of the laboratory simulation. In order to mitigate arsenic related second-stage leaching difficulties it is recommended that a potential probe be installed between the pressure let-down vessel and the filter feed tank. The on-line potential readings would allow timely changes in the make-up to avoid copper depletion of subsequent batches.
Abstract c date library pori Simplified calculations have shown that the use of compressed air instead of "push steam" for discharging of first-stage reactors leads to an unacceptable increase in the copper level in solution. S tot ratio 68 Effect of Electrolyte Composition 69 5. Schematic flowsheet of the Falconbridge Matte Leach FML process 6 Figure Schematic flowsheet of the Falconbridge Chlorine Leach FCL process 9 Figure Simplified flowsheet of the proposed and piloted SLN Refinery process 12 Figure Simplified flowsheet of AMAX's Port Nickel Refinery 14 Figure Simplified flowsheet of iNCO's CRED plant 17 Figure Schematic flowsheet of Outokumpu's Harjavalta Works 21 Simplified flowsheet of the Impala Platinum nickel-copper refinery 26 Figure Simplified flowsheet of the Rustenburg Base Metal Refiners RBMR process 29 Figure Conceptual flowsheet of the Western, Barplats and Northam Platinum nickel-copper refineries Figure Sample taking from the sample point of the IPC thickener underflow line 45 Figure Autoclave set-up for the leaching program at U B C 50 Figure Vacuum desiccator set-up for the leaching program at U B C 51 Figure Variability in the grades of the principal impurity elements in IPC residue samples of May59 C date library pori Effect of c date library pori rate on the extraction of cobalt, nickel, iron and arsenic 60 Figure S E M photograph showing "honeycomb" structures of different porosity 61 Figure Effect of pulp density on the extraction of cobalt, nickel, iron and arsenic 62 Figure Fraction of metal extracted from IPC residues with an average Cu: Stacked X R D patterns showing mineralogical changes in the leach residue over Fraction of metal extracted from IPC residue with a C date library pori S function of leaching time Figure Extraction of cobalt, nickel and iron achievd in the arsenic series, as a function of leaching time 75 Figure Summary of First-Stage Leach FSL parameters investigated in the leaching program Table Minimum, maximum and average grades of the main constituents of IPC residue samples taken from May 9 to 24, Table
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