Process for removing soluble boron compounds from aqueous effluents

摘要

Disclosed is a process for removing boron compounds from aqueous effluents. The effluents are contacted, under stirring, with a divalent metal sulphate MeISO4 and a divalent metal hydroxyde MeII(OH)2, the sulphate-hydroxyde couple being selected from the group consisting of BeSO4-Ba(OH)2; BeSO4-Sr(OH)2; BeSO4-Ca(OH)2; MgSO4-Ba(OH)2; MgSO4-Sr(OH)2; MgSO4-Ca(OH)2; CaSO4-Ba(OH)2; CaSO4-Sr(OH)2; SrSO4-Ba(OH)2; ZnSO4-Ba(OH)2; ZnSO4-Sr(OH)2; ZnSO4-Ca(OH)2; CdSO4-Ba(OH)2; CdSO4-Sr(OH)2 and CdSO4-Ca(OH)2. The sulfate MeISO4 and the hydroxide MeII(OH)2, by reaction with each other, cause the sulphate MeIISO4 and the hydroxide MeI(OH)2 to precipitate. The amount of MeII(OH)2 is at least stoichiometric in respect of the amount of MeISO4 and the precipitation pH is within the range of 7 to 10 when MeISO4 is ZnSO4, and 10 to 13 in the other cases. At the end of the precipitation the mixture is subjected to decantation and to filtration or centrifugation, thus separating the boron-containing precipitate from the purified effluents.