Process for the treatment of high sulphate waters

A process for the treatment of sulphate-containing water, the process including:

• a first reaction stage within which ettringite is used to precipitate precipitated solids from the sulphate-containing water, the precipitated solids being selected from the group consisting of metal compounds, phosphate compounds, sulphate compounds and combinations thereof;
• a suspended solids removal stage for removal of the precipitated solids produced by the first reaction stage;
• a further reaction stage including ettringite production from partially-treated sulphate-containing water from the first reaction stage and the addition of an aluminum containing reagent;
• a suspended solids removal stage for removal of precipitated solids produced by the further reaction stage;
• a particle separation stage within which some or all of the precipitated solids that are removed within the suspended solids removal stage are separated into an aluminum hydroxide-rich product and a product containing a remainder of the precipitated solids removed by the suspend solids removal stage;
• and
• recovery to the further reaction stage of a portion or all of the aluminum hydroxide-rich product as at least a portion of the aluminum containing reagent;
• and
• recovery of the ettringite produced by the further reaction stage for use in the first reaction stage.