Method for the removal of mercury from sulphuric acid with thiosulphate precipitation
AssigneeOutotec Oyj
InventorsDag Berg, Jens Nyberg, Aija Rytioja, Heljä Peltola, Pekka Taskinen
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Abstract
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.
Claims11
A method for the removal of mercury from a dilute aqueous solution of sulphuric acid, comprising:
- feeding an aqueous solution of thiosulphate alkali metal compound into an aqueous solution of sulphuric acid with an acid content of 35-45 wt % and an Hg content of at least 1 g/l, wherein the molar ratio of added thiosulphate to the amount of mercury dissolved in the acid solution is, at maximum, 1.0,
- reacting at least some of the mercury dissolved in the acid solution with the thiosulphate, and
- precipitating reacted mercury from the acid solution.
Dependencies are inferred from the claim text.