Search

The benefits of the short bed ion exchange process are discussed and case studies are presented of the applications of the technology. The resin beads employed have much smaller diameters than in conventional ion exchange systems, resulting in improved exchange kinetics, and the process reduces the depths of inactive, exhausted regions of the resin and makes more effective use of the remaining resin. Countercurrent regeneration introduces the regenerant into the resin bed in a direction opposite to the feed solution, helping to reduce the amount of regenerant required and maximising the concentration of recovered metal or acid, and the short bed vessel is completely packed with resin which eliminates dilution. Discard electrolyte solution from the tank house at the El Paso Cu refinery in the USA was previously treated for Ni recovery using vacuum evaporation for the crystallisation of NiSO4. The existing evaporator/crystalliser system was subsequently replaced by an acid purification unit based on short bed ion exchange to de-acidify the liberator electrolyte bleed solution in order to recycle the recovered sulphuric acid, followed by two-stage precipitation to obtain a purified saleable Ni carbonate product. Two other applications are described, the separation of Cu and Zn in the form of chloro-anionic species from HCl and the recovery of acid from ion exchange regenerant., The benefits of the short bed ion exchange process are discussed and case studies are presented of the applications of the technology. The resin beads employed have much smaller diameters than in conventional ion exchange systems, resulting in improved exchange kinetics, and the process reduces the depths of inactive, exhausted regions of the resin and makes more effective use of the remaining resin. Countercurrent regeneration introduces the regenerant into the resin bed in a direction opposite to the feed solution, helping to reduce the amount of regenerant required and maximising the concentration of recovered metal or acid, and the short bed vessel is completely packed with resin which eliminates dilution. Discard electrolyte solution from the tank house at the El Paso Cu refinery in the USA was previously treated for Ni recovery using vacuum evaporation for the crystallisation of NiSO4. The existing evaporator/crystalliser system was subsequently replaced by an acid purification unit based on short bed ion exchange to de-acidify the liberator electrolyte bleed solution in order to recycle the recovered sulphuric acid, followed by two-stage precipitation to obtain a purified saleable Ni carbonate product. Two other applications are described, the separation of Cu and Zn in the form of chloro-anionic species from HCl and the recovery of acid from ion exchange regenerant.

Recoflo ion exchange technology uses fine mesh resin beads, a fully packed resin bed and countercurrent regeneration. These features help to improve exchange kinetics, reduce regenerant consumption and increase the concentration of strip solutions. Recoflo systems are used to recover Ni and Co from ammonium sulphate byproduct streams, to treat a Cu refinery bleed stream at Falconbridge's Kidd Creek plant in Ontario, to remove Ni from Co electrowinning electrolyte at the Port Colborne refinery (also in Ontario), to recover Cu from dilute leach liquors, to separate acids from dissolved metal salts and for acid removal from the bleed streams at the zinc plant at Valleyfield, Quebec., Recoflo ion exchange technology uses fine mesh resin beads, a fully packed resin bed and countercurrent regeneration. These features help to improve exchange kinetics, reduce regenerant consumption and increase the concentration of strip solutions. Recoflo systems are used to recover Ni and Co from ammonium sulphate byproduct streams, to treat a Cu refinery bleed stream at Falconbridge's Kidd Creek plant in Ontario, to remove Ni from Co electrowinning electrolyte at the Port Colborne refinery (also in Ontario), to recover Cu from dilute leach liquors, to separate acids from dissolved metal salts and for acid removal from the bleed streams at the zinc plant at Valleyfield, Quebec.

Recoflo utilises fine mesh resin beads, a fully packed resin bed and countercurrent regeneration to improve exchange kinetics, reduce regenerant consumption and increase the concentration of strip solutions. The technology, used in metal finishing since the mid 1970s, has recently been used for the recovery and separation of Ni from Co using the XFS 4195 chelating resin. Laboratory tests were conducted using Co electrolyte containing 93.3 g/l Co and 1.44 g/l Ni. A typical run resulted in a purified electrolyte with 84.8 g/l Co and 0.4 g/l Ni and a Ni bleed and rinse stream with 7.0 g/l Co and 2.9 g/l Ni. Compared with conventional ion exchange equipment, the Recoflo system uses 30% less acid and water and has a reduction in resin volume of more than 90%. Case studies are presented of full scale systems treating a Ni- and Co-bearing ammonium sulphate effluent stream and rinse-water from a Zn-Ni electrogalvanising plant and a duplex Ni plating operation., Recoflo utilises fine mesh resin beads, a fully packed resin bed and countercurrent regeneration to improve exchange kinetics, reduce regenerant consumption and increase the concentration of strip solutions. The technology, used in metal finishing since the mid 1970s, has recently been used for the recovery and separation of Ni from Co using the XFS 4195 chelating resin. Laboratory tests were conducted using Co electrolyte containing 93.3 g/l Co and 1.44 g/l Ni. A typical run resulted in a purified electrolyte with 84.8 g/l Co and 0.4 g/l Ni and a Ni bleed and rinse stream with 7.0 g/l Co and 2.9 g/l Ni. Compared with conventional ion exchange equipment, the Recoflo system uses 30% less acid and water and has a reduction in resin volume of more than 90%. Case studies are presented of full scale systems treating a Ni- and Co-bearing ammonium sulphate effluent stream and rinse-water from a Zn-Ni electrogalvanising plant and a duplex Ni plating operation.

The APU (acid purification unit) is a resin-based acid sorption system that can be used for the separation of strong mineral acids from dissolved metal salts. It uses the principles of reciprocating flow ion exchange (Recoflo) and the recovered acid is suitable for re-use in the electrolyte circuit. The APU is ideally suited for treating electrowinning and electrorefining bleed streams. The system has been in use at the Kidd Creek Ni and Cu plant in Ontario for more than a year, and pilot scale tests are under way at the Cyprus Miami copper electrowinning plant in Arizona and in the zinc plant in Valleyfield, Quebec., The APU (acid purification unit) is a resin-based acid sorption system that can be used for the separation of strong mineral acids from dissolved metal salts. It uses the principles of reciprocating flow ion exchange (Recoflo) and the recovered acid is suitable for re-use in the electrolyte circuit. The APU is ideally suited for treating electrowinning and electrorefining bleed streams. The system has been in use at the Kidd Creek Ni and Cu plant in Ontario for more than a year, and pilot scale tests are under way at the Cyprus Miami copper electrowinning plant in Arizona and in the zinc plant in Valleyfield, Quebec.

The Recoflo system uses resin beads with much smaller diameters than conventional ion exchangers, greatly improving the process kinetics. Its fine-mesh resins, short, fully packed ion exchange columns and countercurrent regeneration offer considerable advantages despite possible problems with fouling and entrainment. It is particularly suited for hydrometallurgical applications, due to its ability to process more concentrated feed solutions, its recovery of concentrated metal product streams and its much smaller resin volume requirement. Strong mineral acids can be separated from dissolved metal salts in an acid purification unit. Recoflo systems have been tested or are in use to remove As, Bi and Sb at Bingham Canyon, Utah, Ni and Cu sulphates at Kidd Creek, Ontario, Mg and Mn from zinc electrolyte at Valleyfield, Quebec, Ni from cobalt electrolyte at Port Colborne, Ontario, and Ni and Co from ammonium sulphate by-product streams., The Recoflo system uses resin beads with much smaller diameters than conventional ion exchangers, greatly improving the process kinetics. Its fine-mesh resins, short, fully packed ion exchange columns and countercurrent regeneration offer considerable advantages despite possible problems with fouling and entrainment. It is particularly suited for hydrometallurgical applications, due to its ability to process more concentrated feed solutions, its recovery of concentrated metal product streams and its much smaller resin volume requirement. Strong mineral acids can be separated from dissolved metal salts in an acid purification unit. Recoflo systems have been tested or are in use to remove As, Bi and Sb at Bingham Canyon, Utah, Ni and Cu sulphates at Kidd Creek, Ontario, Mg and Mn from zinc electrolyte at Valleyfield, Quebec, Ni from cobalt electrolyte at Port Colborne, Ontario, and Ni and Co from ammonium sulphate by-product streams.