Patent ID: 7077968

Claim:
A method of continuously processing raw brine with a solids content to obtain a substantially solids-free pure brine (E) for use in chlor-alkali electrolysis, said method comprising the steps of: a) supplying the raw brine (A) with the solids content to a decanter ( 1 ); b) separating the raw brine (A) into a clear brine (B) with a lower solids content than said solids content of the raw brine and an underflow (C) with a higher solids content than said solids content of the raw brine by means of the decanter ( 1 ); c) supplying a metered fraction of the underflow (C) with the higher solids content as a filtering aid and all of the clear brine (B) to a pressure filter; d) during the supplying of step c), controlling the metered fraction and the clear brine (B) during the supplying so that a solids concentration at an inlet to said pressure filter is 5 to 10 times that of a solids concentration in said clear brine (B); and e) filtering with the pressure filter to obtain the substantially solids-free pure brine (E) for chlor-alkali electrolysis and a thickened slurry (F); whereby clogging of the pressure filter is reduced and increased output of said pure brine (E) is possible.