Abstract: A device for cleaning caustic liquor mixtures containing lime, comprising a closed chamber 7 for the caustic liquor mixture to be cleaned with an upper horizontal wall 5, to which a number of hollow filter elements 8 are attached. The filter elements extend downwardly in the chamber and communicate with the latter via a great number of filtrate holes 9 in the filter elements. Each filter element is provided with a filter material 10, which covers the filtrate holes. According to the invention, the filtrate holes 9 are arranged below a horizontal plane P, which is situated below and at a distance from the horizontal wall 5 such that during operation gas is enclosed between the wall and the uncleaned caustic liquor mixture. As a result the caustic liquor mixture in the chamber is prevented from contacting the wall 5, which counteracts the formation of permanent tight layers of lime on the filter material.