Precipitation of nickel and cobalt sulphides using different reactor configurations

The nickel reduction process produces a stream containing unreacted dissolved nickel and cobalt. Removal of these metals to optimum levels is desired, however, the product should also be easy to handle and the process easy to incorporate into the current system. There are various precipitation agent...

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Main Author: Swartbooi, Ashton Mark
Format: Dissertation
Language:English
Published: University of Cape Town 2014
Subjects:
Online Access:http://hdl.handle.net/11427/6696
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spelling ndltd-netd.ac.za-oai-union.ndltd.org-uct-oai-localhost-11427-66962020-12-10T05:11:12Z Precipitation of nickel and cobalt sulphides using different reactor configurations Swartbooi, Ashton Mark Chemical Engineering The nickel reduction process produces a stream containing unreacted dissolved nickel and cobalt. Removal of these metals to optimum levels is desired, however, the product should also be easy to handle and the process easy to incorporate into the current system. There are various precipitation agents that can be used to remove metals from solution, these being hydroxide, carbonates or sulphides. Sulphide precipitation has been gaining increased attention because of the advantages it holds above the other methods. These include: - attainment of high degree of metal removal over a broad pH range; - effective removal of metals such as As, eu and Hg even at low pH; - low retention time required in the reaction tank because of high reactivity; - feasibility of selective metal recovery There are various methods of introducing the sulphide into the system as well, with a soluble sulphide source most commonly used. The problem with this, and coupled to the high reactivity of the sulphide ion, is the creation of high local supersaturation. The supersaturation governs all precipitation and crystallisation processes in the way that it features in nucleation and growth rates. In crystallisation processes, the supersaturation can easily be controlled by thermal methods of evaporation or cooling. However, in precipitation, the creation of supersaturation is by a reaction, which commonly leads to high supersaturation. Thus, to obtain a product that has good filterability and settling ability, methods for controlling the supersaturation in precipitation reactions needs to be investigated. 2014-08-28T09:15:58Z 2014-08-28T09:15:58Z 2005 Master Thesis Masters MSc http://hdl.handle.net/11427/6696 eng application/pdf University of Cape Town Faculty of Engineering and the Built Environment Department of Chemical Engineering
collection NDLTD
language English
format Dissertation
sources NDLTD
topic Chemical Engineering
spellingShingle Chemical Engineering
Swartbooi, Ashton Mark
Precipitation of nickel and cobalt sulphides using different reactor configurations
description The nickel reduction process produces a stream containing unreacted dissolved nickel and cobalt. Removal of these metals to optimum levels is desired, however, the product should also be easy to handle and the process easy to incorporate into the current system. There are various precipitation agents that can be used to remove metals from solution, these being hydroxide, carbonates or sulphides. Sulphide precipitation has been gaining increased attention because of the advantages it holds above the other methods. These include: - attainment of high degree of metal removal over a broad pH range; - effective removal of metals such as As, eu and Hg even at low pH; - low retention time required in the reaction tank because of high reactivity; - feasibility of selective metal recovery There are various methods of introducing the sulphide into the system as well, with a soluble sulphide source most commonly used. The problem with this, and coupled to the high reactivity of the sulphide ion, is the creation of high local supersaturation. The supersaturation governs all precipitation and crystallisation processes in the way that it features in nucleation and growth rates. In crystallisation processes, the supersaturation can easily be controlled by thermal methods of evaporation or cooling. However, in precipitation, the creation of supersaturation is by a reaction, which commonly leads to high supersaturation. Thus, to obtain a product that has good filterability and settling ability, methods for controlling the supersaturation in precipitation reactions needs to be investigated.
author Swartbooi, Ashton Mark
author_facet Swartbooi, Ashton Mark
author_sort Swartbooi, Ashton Mark
title Precipitation of nickel and cobalt sulphides using different reactor configurations
title_short Precipitation of nickel and cobalt sulphides using different reactor configurations
title_full Precipitation of nickel and cobalt sulphides using different reactor configurations
title_fullStr Precipitation of nickel and cobalt sulphides using different reactor configurations
title_full_unstemmed Precipitation of nickel and cobalt sulphides using different reactor configurations
title_sort precipitation of nickel and cobalt sulphides using different reactor configurations
publisher University of Cape Town
publishDate 2014
url http://hdl.handle.net/11427/6696
work_keys_str_mv AT swartbooiashtonmark precipitationofnickelandcobaltsulphidesusingdifferentreactorconfigurations
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