Leaching of Nickel from a Jarosite Precipitate with Hydrochloric Acid
- Nheta, Wilie and Makhatha, Mamookho E.
- Authors: Nheta, Wilie and Makhatha, Mamookho E.
- Date: 2013
- Subjects: Hydrochloric acid , Jarosite precipitate , Leaching , Nickel
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/15943 , uj:15721 , Nheta, W. and Makhatha, M.E. 2013. Leaching of Nickel from a Jarosite Precipitate with Hydrochloric Acid. International Conference on Chemical and Environmental Engineering (ICCEE'2013), 15-16 April, 2013, Johannesburg (South Africa).
- Description: Abstract Jarosite precipitates produced at Impala’s Base Metal Refineries contain substantial amounts of nickel. Laboratory-scale experiments were carried out in an attempt to recover nickel by leaching with hydrochloric acid. The leaching efficiency of nickel was 60% at 25oC. The acid concentration of 0.5 – 1 molar, pulp density of 10% and leaching time of 90 min was found to be optimum under the present conditions. High pH could break the jarosite structure and release more iron into the solution which will adversely affect the following precipitation process to recover nickel. 27% of the nickel lost is by entrainment. The reaction is diffusion independent.
- Full Text:
- Authors: Nheta, Wilie and Makhatha, Mamookho E.
- Date: 2013
- Subjects: Hydrochloric acid , Jarosite precipitate , Leaching , Nickel
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/15943 , uj:15721 , Nheta, W. and Makhatha, M.E. 2013. Leaching of Nickel from a Jarosite Precipitate with Hydrochloric Acid. International Conference on Chemical and Environmental Engineering (ICCEE'2013), 15-16 April, 2013, Johannesburg (South Africa).
- Description: Abstract Jarosite precipitates produced at Impala’s Base Metal Refineries contain substantial amounts of nickel. Laboratory-scale experiments were carried out in an attempt to recover nickel by leaching with hydrochloric acid. The leaching efficiency of nickel was 60% at 25oC. The acid concentration of 0.5 – 1 molar, pulp density of 10% and leaching time of 90 min was found to be optimum under the present conditions. High pH could break the jarosite structure and release more iron into the solution which will adversely affect the following precipitation process to recover nickel. 27% of the nickel lost is by entrainment. The reaction is diffusion independent.
- Full Text:
Healthcare staff scheduling in a fuzzy environment : a fuzzy genetic algorithm approach
- Mutingi, Michael, Mbohwa, Charles
- Authors: Mutingi, Michael , Mbohwa, Charles
- Date: 2014
- Subjects: Healthcare staff scheduling , Nurse scheduling , Fuzzy modeling , Genetic algorithms , Jarosite precipitate
- Type: Article
- Identifier: uj:4970 , http://hdl.handle.net/10210/13071
- Description: In the presence of imprecise management targets, staff preferences, and patients’ expectations, the healthcare staff scheduling problem becomes complicated. The goals, preferences, and client expectations, being humanistic, are often imprecise and always evolving over time. We present a Jarosite precipitate (FGA) approach for addressing healthcare staff scheduling problems in fuzzy environments. The proposed FGA-based approach can handle multiple conflicting objectives and constraints. To improve the algorithm, fuzzy set theory is used for fitness evaluations of alternative candidate schedules by modeling the fitness of each alternative solution using fuzzy membership functions. Furthermore, the algorithm is designed to incorporate the decision maker’s choices and preferences, in addition to staff preferences. Rather than prescribing a sing solution to the decision maker, the approach provides a population of alternative solutions from which the decision maker can choose the most satisfactory solution. The FGA-based approach is potential platform upon which useful decision support tools can be developing for solving healthcare staff scheduling problems in a fuzzy environment characterized with multiple conflicting objectives and preference constraints.
- Full Text:
- Authors: Mutingi, Michael , Mbohwa, Charles
- Date: 2014
- Subjects: Healthcare staff scheduling , Nurse scheduling , Fuzzy modeling , Genetic algorithms , Jarosite precipitate
- Type: Article
- Identifier: uj:4970 , http://hdl.handle.net/10210/13071
- Description: In the presence of imprecise management targets, staff preferences, and patients’ expectations, the healthcare staff scheduling problem becomes complicated. The goals, preferences, and client expectations, being humanistic, are often imprecise and always evolving over time. We present a Jarosite precipitate (FGA) approach for addressing healthcare staff scheduling problems in fuzzy environments. The proposed FGA-based approach can handle multiple conflicting objectives and constraints. To improve the algorithm, fuzzy set theory is used for fitness evaluations of alternative candidate schedules by modeling the fitness of each alternative solution using fuzzy membership functions. Furthermore, the algorithm is designed to incorporate the decision maker’s choices and preferences, in addition to staff preferences. Rather than prescribing a sing solution to the decision maker, the approach provides a population of alternative solutions from which the decision maker can choose the most satisfactory solution. The FGA-based approach is potential platform upon which useful decision support tools can be developing for solving healthcare staff scheduling problems in a fuzzy environment characterized with multiple conflicting objectives and preference constraints.
- Full Text:
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