Abstract: A condenser for isolating solid substances from a vapor and gas mixture and pulps comprises a vertical cylindrical casing having a conical bottom and a vertical rotary drum accommodated in the casing and adjoining with its outer periphery to vertically extending internal protrusions of the casing walls in such a manner that the drum and the protrusions form a vertical transversal partition wall which is in a spaced relationship with respect to the casing bottom, and the interior of the casing represents a U-shaped space. Pipes for admission of a vapor and gas mixture and a pulp that does not contain rare-earth metals are provided in the upper portion of one inlet branch of the U-shaped space, and a pipe for discharge of the vapor and gas mixture cleaned from solid substances is provided in the upper portion of the other outlet branch of the U-shaped space. A pipe for removal of solid substances is provided in the lower portion of the conical bottom.