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Advanced sulphide and hydroxide precipitation pilot

Responsible partner: Skyscape

Location of pilot: Finland (remote)

TRL: 5-6


The advanced sulphide and hydroxide precipitation pilot utilises ammonia as alkali, which is an alternative method to sodium hydroxide. The benefit is that no gypsum is produced. The solution is treated in multiple hydroxide precipitation steps. In each step there is a mixer, reactor, thickener and seed crystal feeding. The effluent of each step is analysed in real-time. The precipitate of each step is treated with centrifuge, separator or other method and eventually removed from the process. The hydroxide precipitation step is  divided into two main phases: (1) Aluminium group (Al, Ti, Cr, V, Sc, U, Si), pH 3.5-5.5 and (2) Iron group (Fe, Mn), pH 5.5-9.5. The remaining solution comprises of a few sulphates, e.g. Mg. Mg is precipitated, crystallised or recovered with different methods. Finally the solution is purified and water is recycled. Size of the reactors is 5L and feed 15L/h. Operation is automatic and remote controlled. Reactors are located in van, which allows operation at existing mining sites.


        Picture: Impression of the pilot built inside a mini-van



Responsible contact: jari.kunnila@gmail.com