High temperature roasting of sulphide concentrate and its effect on the type of precipitate formed
- Authors: Magagula, Fortunate
- Date: 2012-08-16
- Subjects: Metallurgy
- Type: Thesis
- Identifier: uj:9560 , http://hdl.handle.net/10210/5985
- Description: M.Tech. , The most commonly used route in the hydrometallurgical extraction of zinc and copper is the roast-leach-electrowin process. During the roasting process, the concentrate is subjected to either relatively low temperatures (partial roasting) or high temperatures (to achieve dead roasting) to produce a calcine that will be leacheable to extract zinc and copper. The resulting calcine contains zinc and copper in a form of oxides (ZnO, CuO), sulphates (ZnSO4, CuSO4) and ferrites ((Zn,Cu 1-x, Mx)0Fe203) or Zn,CuFe2O4) in the case of partial roasting. In the case of dead roasting, mostly the oxide forms are produced but in most cases ferrites will form as well. The means of avoiding the ferrites completely have not yet been achieved. Attempts in the past had only been focusing on either partial roasting or dead roasting without actually finding the optimum roasting conditions to minimise the ferrite formation. In this study the main objective was to identify optimised conditions for roasting, i.e. the possibility of producing these ferrites in minimum amounts as compared to the targeted zinc/copper oxides. Optimised roasting conditions were achieved in this study on a Zinc-copper ore from Maranda mine, where the sulphur removal test was used to ensure a dead roasting. This was done by analysing the amount of sulphur remaining after each roasting condition. Characterisation of the calcine has been done using the XRD and the Mossbauer spectroscopy. More zinc oxide than zinc ferrite was obtained at conditions of 800 °C for 3 hours as per the XRD analyses. The sulphur removal test however, showed a dead roasting at 900 °C (2% remaining sulphur) and this is attributed to the inadequate (not designed as in industry) supply of oxygen by the laboratory furnaces used. The precipitation of iron from the three acids (HCI, H2SO4 and HNO3) was done using NH4OH and NaOH. The Mossbauer and XRD characterisation techniques were used, where the XRD characterisation showed different spectra of the precipitate attributing to different compounds. The results of the precipitates from the optimised roasting conditions are those precipitates that are not commonly found in industry. The effect of the acids and the cations showed goethite to be formed from H2SO4 and HNO3, with NH4+ and Na+ respectively. The possibility of the selective leaching of the concentrate has been investigated. This eliminates the roasting process completely and thus provides a possibility of leaving the pyrite (FeS2) in the residue and thus minimising the amount of iron to be handled. Selective leaching has been done using Mn02 and Na2S208 in the presence of H2SO4. It was observed that starting with Mn02 as an oxidising agent does not achieve good selective leaching results between the sphalerite and the chalcopyrite. It was however possible to preferable leach sphalerite over chalcopyrite with the use of Na 2S2O8 as a starting oxidising agent. So the choice of the oxidising agent plays a role in selectively leaching different minerals. The optimised roasting conditions at high temperatures resulted in some type of precipitates, (mohrite, ferrihydrite and akaganeite) that are not commonly formed in industry. Jarosite, which is the most common precipitate formed in industry, could not be precipitated. Goethite was also fcund to be present.
- Full Text:
- Authors: Magagula, Fortunate
- Date: 2012-08-16
- Subjects: Metallurgy
- Type: Thesis
- Identifier: uj:9560 , http://hdl.handle.net/10210/5985
- Description: M.Tech. , The most commonly used route in the hydrometallurgical extraction of zinc and copper is the roast-leach-electrowin process. During the roasting process, the concentrate is subjected to either relatively low temperatures (partial roasting) or high temperatures (to achieve dead roasting) to produce a calcine that will be leacheable to extract zinc and copper. The resulting calcine contains zinc and copper in a form of oxides (ZnO, CuO), sulphates (ZnSO4, CuSO4) and ferrites ((Zn,Cu 1-x, Mx)0Fe203) or Zn,CuFe2O4) in the case of partial roasting. In the case of dead roasting, mostly the oxide forms are produced but in most cases ferrites will form as well. The means of avoiding the ferrites completely have not yet been achieved. Attempts in the past had only been focusing on either partial roasting or dead roasting without actually finding the optimum roasting conditions to minimise the ferrite formation. In this study the main objective was to identify optimised conditions for roasting, i.e. the possibility of producing these ferrites in minimum amounts as compared to the targeted zinc/copper oxides. Optimised roasting conditions were achieved in this study on a Zinc-copper ore from Maranda mine, where the sulphur removal test was used to ensure a dead roasting. This was done by analysing the amount of sulphur remaining after each roasting condition. Characterisation of the calcine has been done using the XRD and the Mossbauer spectroscopy. More zinc oxide than zinc ferrite was obtained at conditions of 800 °C for 3 hours as per the XRD analyses. The sulphur removal test however, showed a dead roasting at 900 °C (2% remaining sulphur) and this is attributed to the inadequate (not designed as in industry) supply of oxygen by the laboratory furnaces used. The precipitation of iron from the three acids (HCI, H2SO4 and HNO3) was done using NH4OH and NaOH. The Mossbauer and XRD characterisation techniques were used, where the XRD characterisation showed different spectra of the precipitate attributing to different compounds. The results of the precipitates from the optimised roasting conditions are those precipitates that are not commonly found in industry. The effect of the acids and the cations showed goethite to be formed from H2SO4 and HNO3, with NH4+ and Na+ respectively. The possibility of the selective leaching of the concentrate has been investigated. This eliminates the roasting process completely and thus provides a possibility of leaving the pyrite (FeS2) in the residue and thus minimising the amount of iron to be handled. Selective leaching has been done using Mn02 and Na2S208 in the presence of H2SO4. It was observed that starting with Mn02 as an oxidising agent does not achieve good selective leaching results between the sphalerite and the chalcopyrite. It was however possible to preferable leach sphalerite over chalcopyrite with the use of Na 2S2O8 as a starting oxidising agent. So the choice of the oxidising agent plays a role in selectively leaching different minerals. The optimised roasting conditions at high temperatures resulted in some type of precipitates, (mohrite, ferrihydrite and akaganeite) that are not commonly formed in industry. Jarosite, which is the most common precipitate formed in industry, could not be precipitated. Goethite was also fcund to be present.
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An investigation on the parameters affecting smelting process of a Cassiterite bearing Niobium and Tantalum ore
- Authors: Mutombo, David Ilunga
- Date: 2018
- Subjects: Smelting , Metallurgy , Niobium ores , Tantalum , Cassiterite
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/295026 , uj:32112
- Description:
Abstract: This thesis details results obtained from the smelting process of Cassiterite ore bearing Nb/Ta minerals. The Cassiterite ore, sourced from the Kibara belt in the Democratic Republic of Congo (DRC) was characterised using different analytical equipment such as XRF, XRD and SEM/EDS. It was then treated using a shaking table in order to concentrate it. The Cassiterite ore was then smelt in a tube furnace and the effect of basicity and smelting time was investigated. The chemical and mineralogical studies by XRF and XRD revealed that the Cassiterite ore sample contained Sn (76.01%), Nb2O5 (0.62%) and Ta2O5 (0.81%). It was mainly composed of Cassiterite (SnO2) as the major mineral phase with minor compounds of Sillimanite (Al2SiO5), Ferrotapiolite (Fe(Nb,Ta)2O6), Pyrochlore ((Na, Ca, U)2 (Nb,Ta)2 06) and Tapiolite minerals (FeTa2O6). These results were confirmed using SEM/EDX. It was further revealed that rich Nb and Ta minerals (Pyrochlore and/or Tapiolite and/or Ferrotapiolite) are trapped in sizes ranging from 1.98 to 3.43 μm in the Cassiterite mineral. The results from the gravity pre-concentration process using a shaking table revealed that the Sn grade improved from 76.01 up to 90.50%. However, the Sn recovery was 49.6%; 55.5%; 65.69% and 14.8% for sizes of x>212; 212
- Full Text:
- Authors: Mutombo, David Ilunga
- Date: 2018
- Subjects: Smelting , Metallurgy , Niobium ores , Tantalum , Cassiterite
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/295026 , uj:32112
- Description:
Abstract: This thesis details results obtained from the smelting process of Cassiterite ore bearing Nb/Ta minerals. The Cassiterite ore, sourced from the Kibara belt in the Democratic Republic of Congo (DRC) was characterised using different analytical equipment such as XRF, XRD and SEM/EDS. It was then treated using a shaking table in order to concentrate it. The Cassiterite ore was then smelt in a tube furnace and the effect of basicity and smelting time was investigated. The chemical and mineralogical studies by XRF and XRD revealed that the Cassiterite ore sample contained Sn (76.01%), Nb2O5 (0.62%) and Ta2O5 (0.81%). It was mainly composed of Cassiterite (SnO2) as the major mineral phase with minor compounds of Sillimanite (Al2SiO5), Ferrotapiolite (Fe(Nb,Ta)2O6), Pyrochlore ((Na, Ca, U)2 (Nb,Ta)2 06) and Tapiolite minerals (FeTa2O6). These results were confirmed using SEM/EDX. It was further revealed that rich Nb and Ta minerals (Pyrochlore and/or Tapiolite and/or Ferrotapiolite) are trapped in sizes ranging from 1.98 to 3.43 μm in the Cassiterite mineral. The results from the gravity pre-concentration process using a shaking table revealed that the Sn grade improved from 76.01 up to 90.50%. However, the Sn recovery was 49.6%; 55.5%; 65.69% and 14.8% for sizes of x>212; 212
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Bioleaching of chalcopyrite and pyritic chalcocite using indigenous mesophilic microorganisms
- Authors: Bampole, Lukumu David
- Date: 2018
- Subjects: Bacterial leaching , Chalcopyrite , Metallurgy
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/294962 , uj:32104
- Description: Abstract: This scientific endeavour is a comparative study of the copper (bio)leaching process from chalcopyrite and pyritic chalcocite and its application as an alternative route for the conventional treatment of copper from sulphide ores around the Lufilian Arc in the Katanga copper belt (case study of Kamoa deposit) in the Democratic Republic of the Congo (DRC). The first findings were linked to the characterisation of the two campaigns in the form of bulk core samples collected from the Kamoa ore body: ‘campaigns 1 and campaign 2’ (chalcopyrite and pyritic chalcocite). The chemical and mineralogical characterisations confirmed that assumption, which means that copper, is mainly bearing under the form of chalcopyrite for the first campaign and chalcocite enclosed in pyritic ore. The second result was related to the bacterial isolation, physicochemical control of bacterial activities and the bacterial identification and numeration by means of 16SrRNA sequencing analysis. The Biomolecular analysis confirmed the presence of five DNA classes identified which are Gammaproteobacteria, beta proteobacteria, Alphaproteobacteria, Bacilli, Acidobacteria that were highly identified and numbered from the designed synthetic sample, among them, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans species which are most known for their biotechnological interest. The third findings from correlating the comparative study of copper leaching in ferric sulphate and copper bioleaching from chalcopyrite and pyritic chalcocite. The tests were in atmospheric conditions and in autoclave for predicting the chemical solubilisation and mechanisms to be considered in this research during bioleaching. Regarding the conventional method (leaching in ferric sulphate) several variables were studied, and optimal conditions were retained with pH 1.5, a pulp density of 2% (w/v) with 4g/L at 70° C, a stirring speed of 150 rpm, and hydrogen peroxide of 1.5 M was also retained as a supplementary additive for both campaigns (78. 52% for chalcopyrite and 82. 5% for pyritic chalcocite). During the chemical leaching process, it was noted that stirring speed does not have a significant effect during the leaching process this why, the optimal condition was fixed at 150 (rpm), which can be predicted due to the high presence of silica, carbonated compound and iron by-product formed during the dissolution time. Concentration below 1.5 M has a significant influence on increasing the dissolution yield – but with a limitation due to the slight destruction of the jarosite formation. Thus, above this limit, the copper dissolution action emerges as too faulty and enriches the inhibited character over the grain surface. Furthermore, the positive effect related to the added catalyst on the pH was reported as conversely proportional to the concentration increase – thereby highlighting an optimal output with 86.60 % at pH level 1. 5, taking into consideration the acid consumption for chalcopyrite and 89.70% for pyritic chalcocite. The copper dissolution rates and iron were correlated in these leaching conditions. Refractory copper sulphide ores can be leached with mesophilic bacteria and took an average of 7 days... , M.Tech. (Extraction Metallurgy)
- Full Text:
- Authors: Bampole, Lukumu David
- Date: 2018
- Subjects: Bacterial leaching , Chalcopyrite , Metallurgy
- Language: English
- Type: Masters (Thesis)
- Identifier: http://hdl.handle.net/10210/294962 , uj:32104
- Description: Abstract: This scientific endeavour is a comparative study of the copper (bio)leaching process from chalcopyrite and pyritic chalcocite and its application as an alternative route for the conventional treatment of copper from sulphide ores around the Lufilian Arc in the Katanga copper belt (case study of Kamoa deposit) in the Democratic Republic of the Congo (DRC). The first findings were linked to the characterisation of the two campaigns in the form of bulk core samples collected from the Kamoa ore body: ‘campaigns 1 and campaign 2’ (chalcopyrite and pyritic chalcocite). The chemical and mineralogical characterisations confirmed that assumption, which means that copper, is mainly bearing under the form of chalcopyrite for the first campaign and chalcocite enclosed in pyritic ore. The second result was related to the bacterial isolation, physicochemical control of bacterial activities and the bacterial identification and numeration by means of 16SrRNA sequencing analysis. The Biomolecular analysis confirmed the presence of five DNA classes identified which are Gammaproteobacteria, beta proteobacteria, Alphaproteobacteria, Bacilli, Acidobacteria that were highly identified and numbered from the designed synthetic sample, among them, Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans species which are most known for their biotechnological interest. The third findings from correlating the comparative study of copper leaching in ferric sulphate and copper bioleaching from chalcopyrite and pyritic chalcocite. The tests were in atmospheric conditions and in autoclave for predicting the chemical solubilisation and mechanisms to be considered in this research during bioleaching. Regarding the conventional method (leaching in ferric sulphate) several variables were studied, and optimal conditions were retained with pH 1.5, a pulp density of 2% (w/v) with 4g/L at 70° C, a stirring speed of 150 rpm, and hydrogen peroxide of 1.5 M was also retained as a supplementary additive for both campaigns (78. 52% for chalcopyrite and 82. 5% for pyritic chalcocite). During the chemical leaching process, it was noted that stirring speed does not have a significant effect during the leaching process this why, the optimal condition was fixed at 150 (rpm), which can be predicted due to the high presence of silica, carbonated compound and iron by-product formed during the dissolution time. Concentration below 1.5 M has a significant influence on increasing the dissolution yield – but with a limitation due to the slight destruction of the jarosite formation. Thus, above this limit, the copper dissolution action emerges as too faulty and enriches the inhibited character over the grain surface. Furthermore, the positive effect related to the added catalyst on the pH was reported as conversely proportional to the concentration increase – thereby highlighting an optimal output with 86.60 % at pH level 1. 5, taking into consideration the acid consumption for chalcopyrite and 89.70% for pyritic chalcocite. The copper dissolution rates and iron were correlated in these leaching conditions. Refractory copper sulphide ores can be leached with mesophilic bacteria and took an average of 7 days... , M.Tech. (Extraction Metallurgy)
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The use of multi agent system for monitoring and control of the smelting process in the mining metallurgical sector
- Siti, M., Jordaan, J., Jimoh, A. A., Nicolae, Dan-Valentin
- Authors: Siti, M. , Jordaan, J. , Jimoh, A. A. , Nicolae, Dan-Valentin
- Date: 2005
- Subjects: Metallurgy , Power energy , Voltage detectors
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/22052 , uj:16160 , ISBN: 0780393279 , Citation: Siti, M. et al. 2005. The use of multi agent system for monitoring and control of the smelting process in the mining metallurgical sector. IEEE PES 2005 Inaugural Conference and Exposition in Africa, South Africa, 11-15 July, 2005:326-331.
- Description: Abstract: This paper is focusing on the development of intelligent agent technology and application of that technology to the mining and metallurgical sector.We have shown how networks of communicating and cooperating intelligent software agents can be used to implement complex distributed systems. in the mining and metallurgical industries there are processes which cannot tolerate interruption, such as some sequential line chemical processes.
- Full Text:
- Authors: Siti, M. , Jordaan, J. , Jimoh, A. A. , Nicolae, Dan-Valentin
- Date: 2005
- Subjects: Metallurgy , Power energy , Voltage detectors
- Language: English
- Type: Conference proceedings
- Identifier: http://hdl.handle.net/10210/22052 , uj:16160 , ISBN: 0780393279 , Citation: Siti, M. et al. 2005. The use of multi agent system for monitoring and control of the smelting process in the mining metallurgical sector. IEEE PES 2005 Inaugural Conference and Exposition in Africa, South Africa, 11-15 July, 2005:326-331.
- Description: Abstract: This paper is focusing on the development of intelligent agent technology and application of that technology to the mining and metallurgical sector.We have shown how networks of communicating and cooperating intelligent software agents can be used to implement complex distributed systems. in the mining and metallurgical industries there are processes which cannot tolerate interruption, such as some sequential line chemical processes.
- Full Text:
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