Dissolution behavior of steelmaking slag for Ca extraction toward CO2 sequestration

Assessment of Ammoniacal Leaching Agents for Metal Cation Extraction from Construction Wastes in Mineral Carbonation

“…After CaCO 3 production, the use of CO 2 can be used to protonate ammonia and shift the pH of the solution back to anywhere between 4 and 7 which can be used to solubilize additional Ca 2+ from waste HCP in subsequent process cycles. From a process standpoint, the most challenging step is likely to be the separation of sodium bicarbonate and ammonia chloride if excess bicarbonate is present in the solution. N a C l + normalN normalH 3 + normalC normalO 2 + H 2 normalO ↔ N a C l + normalN normalH 3 + H 2 normalC normalO 3 H 2 normalC normalO 3 ( p K normala 6.25 ) + normalN normalH 3 + N a C l ↔ normalN normala normalH normalC normalO 3 + normalN normalH 4 C l ( p K normala 9.25 ) The regeneration of ammonium sulfate salts in the carbonation of Mg-bearing minerals and Ca-rich steel slags have both been heavily studied by numerous research groups, especially Maroto-Valer and Zevenhoven. ,,,,,− Generally, these systems result in an effluent that is rich in ammonium sulfate (NH 4 ) 2 SO 4 . Degassing of ammonia can be facilitated through mild heat, regenerating ABS used in leaching, where...…”

“…After CaCO 3 production, the use of CO 2 can be used to protonate ammonia and shift the pH of the solution back to anywhere between 4 and 7 which can be used to solubilize additional Ca 2+ from waste HCP in subsequent process cycles. From a process standpoint, the most challenging step is likely to be the separation of sodium bicarbonate and ammonia chloride if excess bicarbonate is present in the solution. The regeneration of ammonium sulfate salts in the carbonation of Mg-bearing minerals and Ca-rich steel slags have both been heavily studied by numerous research groups, especially Maroto-Valer and Zevenhoven. ,,,,,− Generally, these systems result in an effluent that is rich in ammonium sulfate (NH 4 ) 2 SO 4 . Degassing of ammonia can be facilitated through mild heat, regenerating ABS used in leaching, whereas the gaseous ammonia can then be used as a base or to assist in CO 2 capture. , Unfortunately, the strength of strong acids, such as HCl, HNO 3 , and H 2 SO 4 , make them much more attractive due to superior extraction efficiencies in these processes .…”

“… The regeneration of ammonium sulfate salts in the carbonation of Mg-bearing minerals and Ca-rich steel slags have both been heavily studied by numerous research groups, especially Maroto-Valer and Zevenhoven. 5 , 44 , 55 , 56 , 76 , 78 − 81 Generally, these systems result in an effluent that is rich in ammonium sulfate (NH 4 ) 2 SO 4 . Degassing of ammonia can be facilitated through mild heat, regenerating ABS used in leaching, whereas the gaseous ammonia can then be used as a base or to assist in CO 2 capture.…”