Method for removing thallium from a zinc-containing solution
View Patent ↗This invention relates to a method for removing thallium from a zinc-containing solution. In particular, the method relates to the purification with metallic zinc powder of a solution going to the electrolytic production of zinc. In this method, thallium is removed by means of a lead compound in the solution purification stage, either during the final purification stage or in a purification stage in which cadmium is precipitated.
1. A method for the removal of thallium from a zinc-containing solution in connection with the electrolytic production of zinc, comprising:
conducting the zinc-containing solution which additionally contains thallium and cadmium to a cadmium purification stage,
adding a soluble lead compound to the zinc-containing solution so that the amount of lead is adjusted to be at least equivalent to the amount of thallium, and
adding zinc powder to the zinc-containing solution to precipitate cadmium and thallium, thereby removing thallium from the zinc-containing solution.
2. A method according to claim 1 , wherein the soluble lead compound is lead acetate.
3. A method according to claim 1 , wherein the soluble lead compound is fed continuously.
4. A method according to claim 1 , wherein the zinc-containing solution is zinc sulphate solution.
5. A method according to claim 1 , wherein thallium removal takes place at a temperature between 50-100° C.
6. A method according to claim 1 , wherein thallium removal takes place at a temperature between 60-70° C.