A process for washing a particulate substance comprising: (i) combining a particulate substance and a first washing medium in a first vessel to form a slurry and washing the particulate substance with said washing medium; (ii) transferring the slurry to a hydrocyclone; (iii) removing a first by-product stream depleted in particulate substance and a first product stream enriched in particulate substance from the hydrocyclone; (iv) transferring the first product stream to a second vessel and in the presence of a second washing medium forming a slurry and washing the particulate substance with said second washing medium e.g. by agitation thereof; (v) transferring the slurry to a hydrocyclone; (vi) removing a second by-product stream depleted in particulate substance and a second product stream enriched in particulate substance from the hydrocyclone.