Wezi Banda - Academia.edu (original) (raw)

Papers by Wezi Banda

Research paper thumbnail of High temperature phase equilibria in the Fe-Co-Cu-Si system pertinent to slag cleaning

In the smelting of copper waste slags to recover cobalt and copper, the prediction of the metal l... more In the smelting of copper waste slags to recover cobalt and copper, the prediction of the metal liquidus temperature and the associated superheat for liquid metal handling for subsequent treatments cannot be done with certainty, making the management of furnace ...

Research paper thumbnail of Pyrometallurgical recovery of cobalt from waste reverbaratory furnace slag by DC plasma-ARC furnace technology

Slag cleaning has become a common practice at many smelters in the nonferrous industry to maximiz... more Slag cleaning has become a common practice at many smelters in the nonferrous industry to maximize recovery of valuable metals. However, during the carbothermic reduction of nonferrous slag to recover cobalt, in particular, iron is recovered predominantly. High iron levels present a problem for the subsequent treatment of the alloy as it may increase the solids loading to the filter and lead to increased reagent consumption during leaching. Finding an appropriate slag modifier that would selectively improve the recovery of cobalt against that of iron to the metallic alloy can solve this problem. In the present study the effects of lime (CaO), rutile (Ti02), and fluorspar (CaF2) on the recovery of cobalt from waste nonferrous slag have been investigated under reducing conditions at 1500°C. The selective recovery of cobalt compared to the recovery of iron at different levels of flux additions is discussed in this study, to show the selectivity of these fluxes. It is also shown in the ...

Research paper thumbnail of Silicon activity in liquid Fe–Co–Cu–Si

Mineral Processing and Extractive Metallurgy, 2009

ABSTRACT

Research paper thumbnail of The role of slag modifiers on the selective recovery of cobalt and copper from waste smelter slag

Minerals Engineering, 2002

Slag cleaning is important from both an economical and environmental perspective. Dump slags from... more Slag cleaning is important from both an economical and environmental perspective. Dump slags from copper smelting prove to be a valuable source of base metals, but the abundance of iron in the slag leads to significant amounts of iron reporting to the alloy phase during carbothermic reduction, which poses a significant cost to remove in subsequent hydrometallurgical processes. A carbothermic reduction of nonferrous smelter slag was conducted under the influence of three different slag modifiers to investigate the recovery of cobalt (and copper) versus iron recovery. The test work was performed in two campaigns; one campaign was performed under a constant oxygen potential of 4:33 Â 10 À9 atm, while the other set of test work was performed using graphite under a pure argon atmosphere. It is shown in both cases that, out of these slag modifiers used, TiO 2 had a more selective recovery of cobalt compared to CaO and CaF 2. It appears that TiO 2 reduces the activity coefficient of the FeO in slag due to its strong affinity for FeO in the slag phase.

Research paper thumbnail of Determination of the Phase Transformation Temperatures of the Fe-Co-Cu-Si System in the Fe-Rich Corner by Thermal Analysis

Metallurgical and Materials Transactions B, 2008

Caottaua aa rararas et*t ft rracMsaqr mnt Identify by block number) Some of the more popular meth... more Caottaua aa rararas et*t ft rracMsaqr mnt Identify by block number) Some of the more popular methods used to determine phase transformations in metals are x-ray, dllatometry, and electrical resistivity. Data reported for the TIN! alloy using Differential Thermal Analysis (DTA) is quite sparse and It appears that little effort has been made to correlate these results with x-ray, dllatometry, or resistivity data. The purpose of this Investigation was to determine the M s and A s temperatures for several alloys having compositions (CONT'D ON REVERSE) DD , FORM JAM 73 1473 EDITION OF » MOV «5 IS OBSOLETE UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) SECURITY CLASSIFICATION OF THIS PAOEfOTi*" OmU Snfnd) 20. Abstract (Cont'd) near 50 atomic percent titanium. The DTA method was used. The results are compared with those reported by several investigators that used different techniques. The DTA data obtained shows excellent agreement with Kornilov's A £ temperatures,'-as a function of composition, obtained by dilatoraetry. A small variation was found between the results of this study and Wasilewski's x-ray data, 2 and Hanlon's resistivity measurements 3 for the M s temperatures. It is concluded from this investigation that DTA analysis is a credible method for determining phase transformation temperatures for the TiNi material. SECURITY CLASSIFICATION OF THIS PAGEfHTien Data Entarad

Research paper thumbnail of High temperature phase equilibria in the Fe-Co-Cu-Si system pertinent to slag cleaning

In the smelting of copper waste slags to recover cobalt and copper, the prediction of the metal l... more In the smelting of copper waste slags to recover cobalt and copper, the prediction of the metal liquidus temperature and the associated superheat for liquid metal handling for subsequent treatments cannot be done with certainty, making the management of furnace ...

Research paper thumbnail of Liquidus temperature determination of the Fe–Co–Cu system in the Fe-rich corner by thermal analysis

Journal of Alloys and Compounds, 2008

The liquidus temperature of the ternary Fe–Co–Cu alloy was investigated using differential therma... more The liquidus temperature of the ternary Fe–Co–Cu alloy was investigated using differential thermal analysis (DTA). The alloy composition was within the range of ferrocobalt produced from the smelting of copper waste slag to recover cobalt and copper. The general behaviour of the ternary alloy with respect to the liquidus temperatures is characterised by the ratio of iron to copper. It

Research paper thumbnail of High temperature phase equilibria in the Fe-Co-Cu-Si system pertinent to slag cleaning

In the smelting of copper waste slags to recover cobalt and copper, the prediction of the metal l... more In the smelting of copper waste slags to recover cobalt and copper, the prediction of the metal liquidus temperature and the associated superheat for liquid metal handling for subsequent treatments cannot be done with certainty, making the management of furnace ...

Research paper thumbnail of Pyrometallurgical recovery of cobalt from waste reverbaratory furnace slag by DC plasma-ARC furnace technology

Slag cleaning has become a common practice at many smelters in the nonferrous industry to maximiz... more Slag cleaning has become a common practice at many smelters in the nonferrous industry to maximize recovery of valuable metals. However, during the carbothermic reduction of nonferrous slag to recover cobalt, in particular, iron is recovered predominantly. High iron levels present a problem for the subsequent treatment of the alloy as it may increase the solids loading to the filter and lead to increased reagent consumption during leaching. Finding an appropriate slag modifier that would selectively improve the recovery of cobalt against that of iron to the metallic alloy can solve this problem. In the present study the effects of lime (CaO), rutile (Ti02), and fluorspar (CaF2) on the recovery of cobalt from waste nonferrous slag have been investigated under reducing conditions at 1500°C. The selective recovery of cobalt compared to the recovery of iron at different levels of flux additions is discussed in this study, to show the selectivity of these fluxes. It is also shown in the ...

Research paper thumbnail of Silicon activity in liquid Fe–Co–Cu–Si

Mineral Processing and Extractive Metallurgy, 2009

ABSTRACT

Research paper thumbnail of The role of slag modifiers on the selective recovery of cobalt and copper from waste smelter slag

Minerals Engineering, 2002

Slag cleaning is important from both an economical and environmental perspective. Dump slags from... more Slag cleaning is important from both an economical and environmental perspective. Dump slags from copper smelting prove to be a valuable source of base metals, but the abundance of iron in the slag leads to significant amounts of iron reporting to the alloy phase during carbothermic reduction, which poses a significant cost to remove in subsequent hydrometallurgical processes. A carbothermic reduction of nonferrous smelter slag was conducted under the influence of three different slag modifiers to investigate the recovery of cobalt (and copper) versus iron recovery. The test work was performed in two campaigns; one campaign was performed under a constant oxygen potential of 4:33 Â 10 À9 atm, while the other set of test work was performed using graphite under a pure argon atmosphere. It is shown in both cases that, out of these slag modifiers used, TiO 2 had a more selective recovery of cobalt compared to CaO and CaF 2. It appears that TiO 2 reduces the activity coefficient of the FeO in slag due to its strong affinity for FeO in the slag phase.

Research paper thumbnail of Determination of the Phase Transformation Temperatures of the Fe-Co-Cu-Si System in the Fe-Rich Corner by Thermal Analysis

Metallurgical and Materials Transactions B, 2008

Caottaua aa rararas et*t ft rracMsaqr mnt Identify by block number) Some of the more popular meth... more Caottaua aa rararas et*t ft rracMsaqr mnt Identify by block number) Some of the more popular methods used to determine phase transformations in metals are x-ray, dllatometry, and electrical resistivity. Data reported for the TIN! alloy using Differential Thermal Analysis (DTA) is quite sparse and It appears that little effort has been made to correlate these results with x-ray, dllatometry, or resistivity data. The purpose of this Investigation was to determine the M s and A s temperatures for several alloys having compositions (CONT'D ON REVERSE) DD , FORM JAM 73 1473 EDITION OF » MOV «5 IS OBSOLETE UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) SECURITY CLASSIFICATION OF THIS PAOEfOTi*" OmU Snfnd) 20. Abstract (Cont'd) near 50 atomic percent titanium. The DTA method was used. The results are compared with those reported by several investigators that used different techniques. The DTA data obtained shows excellent agreement with Kornilov's A £ temperatures,'-as a function of composition, obtained by dilatoraetry. A small variation was found between the results of this study and Wasilewski's x-ray data, 2 and Hanlon's resistivity measurements 3 for the M s temperatures. It is concluded from this investigation that DTA analysis is a credible method for determining phase transformation temperatures for the TiNi material. SECURITY CLASSIFICATION OF THIS PAGEfHTien Data Entarad

Research paper thumbnail of High temperature phase equilibria in the Fe-Co-Cu-Si system pertinent to slag cleaning

In the smelting of copper waste slags to recover cobalt and copper, the prediction of the metal l... more In the smelting of copper waste slags to recover cobalt and copper, the prediction of the metal liquidus temperature and the associated superheat for liquid metal handling for subsequent treatments cannot be done with certainty, making the management of furnace ...

Research paper thumbnail of Liquidus temperature determination of the Fe–Co–Cu system in the Fe-rich corner by thermal analysis

Journal of Alloys and Compounds, 2008

The liquidus temperature of the ternary Fe–Co–Cu alloy was investigated using differential therma... more The liquidus temperature of the ternary Fe–Co–Cu alloy was investigated using differential thermal analysis (DTA). The alloy composition was within the range of ferrocobalt produced from the smelting of copper waste slag to recover cobalt and copper. The general behaviour of the ternary alloy with respect to the liquidus temperatures is characterised by the ratio of iron to copper. It