Treatment of sulphide contg. effluent waters with carbon dioxide - to give prod. with high hydrogen sulphide concn. suitable for sulphur recovery

摘要

Sulphide-contg. effluent water is treated with CO2 in counterflow in a multi-stage process whereby in a first stage the effluent is contacted with CO2 from the subsequent stage at a pressure of 2-7 atmos., the pressure is reduced to 0.3-1.5 atmos. and in a second stage the effluent is treated with a virtually stoichiometric amt. of CO2 from the subsequent stage (measured on total sulphide sulphur in the effluent), after which excess CO2, contg. small amts. H2S, is drawn off and in a third stage the effluent is treated with 1.5-5 times the stoichiometric amt. of fresh CO2. Provides a relatively cheap treatment with reduced energy consumption. The sulphide is recovered as gaseous H2S in high concns. allowing further processing to sulphur in a Clause unit. The sulphide concn. of the treated water is so low that it can be used directly without further treatment.