Preparation of Zinc Chemicals from the Minor Flow of a Process

Abstract

The invention is a novel process arrangement for producing pure zinc chemicals from the minor flow of a calcining-dissolving-electrolysis type of a preparation process of zinc. The invention is based on the fact that part of the production of the zinc sulphate-containing solution obtained from the dissolution of the calcining-dissolving-electrolysis plant is directed to the preparation of zinc chemicals. The actual recovery process of zinc, which is based on electrolysis, is not disturbed, as only part of the production of the zinc sulphate solution is directed to the preparation of zinc chemicals. The extraction process is based on the use of any organically substituted phosphoric acid or organically substituted thiophosphinic acid. The strong acid solution, which is generated as a by-product in the extraction process of zinc, is recycled back to the calcining-dissolving-electrolysis type of a preparation process of zinc.

1 . A process circuit for preparing pure zinc chemicals for a zinc sulphate-containing solution by means of an extraction method, wherein the raw material flow of the extraction is separated as a minor flow from the calcining-dissolving-electrolysis type of a process line of the zinc primary production after a neutral dissolution stage.  
   
   
       2 . A process arrangement according to  claim 1 , wherein a raffinate that is generated in the extraction is directed to be reused in the strong acid dissolution of the said calcining-dissolving-electrolysis type of a process.  
   
   
       3 . A process arrangement according to  claim 1 , wherein diethylhexylphosphoric acid (DEHPA) or di-2-ethylhexylphosphoric acid (D2EHPA) is exploited in the extraction.  
   
   
       4 . A process arrangement according to  claim 1 , wherein towards the end of the dissolving stage, the pH of the solution going to the extraction is raised to a level suitable for the extraction by means of a calcine.