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AssigneeOutokumpu Technology Oy
InventorsDag Berg, Jens Nyberg, Aija Rytioja, Helja Peltola, Pekka Taskinen
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This invention relates to a method for removing mercury from dilute sulphuric acid. According to the method sulphuric acid solution is scrubbed with an aqueous solution containing thiosulphate, which precipitates the mercury present in the sulphuric acid solution either as mercury sulphide or, in a chlorine-containing environment, as a mercury sulphide-mercury chloride double salt. The quantity of thiosulphate to be fed is adjusted so that it precipitates the mercury in the sulphuric acid solution, but still does not form elemental sulphur.
A method for the removal of mercury from a dilute aqueous solution of sulphuric acid, characterised in that an aqueous solution of thiosulphate alkali metal compound is fed into absolution of sulphuric acid with an acid content of 35-45 wt % and an Hg content of at least 1 g/l at a molar ratio corresponding to a maximum of one time the amount of mercury dissolved in the acid solution, so that the mercury reacts with the thiosulphate, precipitating the mercury that is in solution.
Dependencies are inferred from the claim text.