The principle of the invention is the method of pressure filtration and washing of solid suspensions in liquid.

Pressure dewatering and washing of solid suspensions in liquids is the best known and most common method assumed in industrial practice of solid and liquid separation. Amongst many pressure methods, the most common is pressure filtration and washing in automatic pressure filters with horizontal filtration plates or filtration presses with vertical filtration plates equipped with pressing membranes.

Frequent inconvenience of applied methods arises from impossibility of achieving required, so called filtration cake's final moisture, and/or gaming required cake's purity i.e. filtration cake's quality.

The principle of solution according to invention is, that during solid and liquid phase separation is introduced the aid medium consisting of overheated, saturated, depressurized water steam, of pressure 1.5-16 bar, or mixture of air of pressure 1.0-16.0 bar and temperature 0 to 80°C and the mentioned steam, whilst the mentioned medium affects the solid and liquid phase in separation process either directly or indirectly through filtration media. The solid and liquid phase, upon the medium's activity occur thickenned, as so called filtration cake of weight content of solid from 25-95%, and respectively liquid phase from 75- 5 . The medium affecting the filtration cake is proportioned so, that during its contact with the cake only partial meαium's condensation occurs, and the initial parameters of pressure and temperature are only partially preserved,

whereas the pressure should amount from 1.1 up to 12 bar, most preferably 2-8 bar m the space of the medium and filtration cake contact. Provided medium, under its own pressure penetrating filtration cake, rises its temperature until it is equal to the medium's temperature, however most preferably to 30-90°C, whereas the effectiveness of the medium's influence on the cake is determined by the medium condensation's intensity in the cake, and fades away at the moment of appearance of medium as a gas at the outlet from filtration cake. Washing of filtration cake occurs upon the medium's affecting on the cake, by slight and exact exchange of mother liquid laying in the cake for clear water from condensatmg medium. After the medium's affecting the filtration cake is either blown through with compressed air, or pressed with membrane and blown through with compressed air, until the cake's temperature reaches from 30-70°C, and the temperature of air used for blowing at the outlet from filtration cake amounts from 20-70°C.

The method according to the invention is presenteα by the below example, in which the suspension of sulphide copper concentrate in water solution containing amongst sodium, potassium, manganese chlorides, calcium and manganese sulphates and other soluble salts, for eg. fluorides, is pressure filtrated and washed in automatic pressure filter of horizontal filtration chamber. The solid's content by weight in suspension amounts abt. 60%, and the suspension's temperature is close to that of its surroundings. The example is illustrated by schematic drawing Fig. 1, which shows the suspension's pumping into filtration chamber under tne pressure of 6.0 bar, where under the pressure generated by the pump, filtration cake forms on filtration cloth, and separated mother liquid (i.e. filtrate) flowing through the clotn is gravitationally flown outside filtration chamber.

The suspension remaining in filtration chamber becomes thickenned further up to the solid content by weight of 70- 75% in formed filtration cake.

Fig. 2 shows pressing with flexible membrane situated in the upper part of the chamber. The pressure generated in membrane amounts 14.0 bar and the membrane pressing the cake against filtration cloth causes further, deeper separation of solid and liquid, and simultanously tough compression of filtration case up to the solid content of abt. 83.0% by weight and respectively liquid content of abt. 17%. Fig. 3 shows introduction of aid medium, i.e. saturated, depressurized steam into the space between compressed filtration cake and the membrane, with such intenseness, that the pressure in the space of the filtration cake and medium's contact keeps up between 2.0-5.0 bar. The aid medium's reaction on filtration cake maintains until the medium as a gas appears at the outlet from filtration cake, i.e. filtrate chamber. Fig. 4 shows repeated membrane pressing, due to which the remaining condenseted water as well as mother liquid that has not yet been disposed of are squeezed out from filtration cake. Fig. 5 shows the final cake drying, when after the inside of membrane is depressurized, compressed air of the ambient temperature and the pressure 8.0 bar is forced into the space between membrane and filtration cake. The filtration cake blowing with compressed air is maintained until its temperature at the outlet from the cake is abt. 45 ^C C and the cake is cooled down to abt. 55°C.

The air flowing through the cake removes mechanically the remains of liquid phase laying in the cake, simultanously saturating itself with the moisture.

Fig. 6 shows discharge of filtration cake of temperature abt. 50°C, in which the solid phase amounts by weight 91.3% and liquid phase respectively 8.7%, and contamination analysis proved the cake only contains very slight traces of contamination, for instance the content of Cl ions amounts 0.05%.