Membrane filter process and apparatus for the purification and/or treatment of suspensions of precio

The invention relates to a process for the purification and/or treatment of suspensions, which include at least one or more precious metals and/or rare earths or other elements in the form of a precipitate or solid and/or also in dissolved form, which includes the following steps : concentrating or thickening the precipitate or solid in the suspension by removal of the liquid phase by means of a membrane filter apparatus, whereby dissolved impurities and/or precious materials are discharged with filtrate; washing of the concentrated or thickened suspension by addition of a wash liquid and removal of filtrate by means of the membrane filter apparatus, whereby the concentration or thickening of the solids in the suspension does not or changes only slightly during washing and the concentration or thickening of the dissolved impurities and/or precious materials still present in the suspension are reduced to a pre-determined value; and complete drainage of the membrane filter apparatus to provide, in purified form, solid and/or purified precipitates of the precious metal(s) and /or rare earths or other elements remaining in residual suspension for further treatment and/or further application.