Abstract: A ceramic article is made by shaping, drying and firing a body shaped from a mixture of clay and an organic fraction. The organic fraction is derived from domestic waste by separation of metal parts, coarse material and material in sheet form. The proportion of clay in the mixture is 40 to 65% by weight and the clay contains more than 10% by weight of particles of size greater than 2.mu..

Abstract: A method of heat exchange in a heat exchanger which has a plurality of upwardly extending pipes for upward flow of a primary liquid medium and around which in operation a secondary medium flows, a lower chamber at the lower ends of the pipes from which the primary liquid enters the pipes and which contains a distribution system adapted to distribute flow across the cross-section of the lower chamber, and an upper chamber at the upper ends of the pipes into which the fluid passes from the pipes, the pipes and the upper and lower chambers containing fluidizable particulate material, in which method the flow-rate of the primary liquid medium is selected so that the particulate material is fluidized within the pipes and within the upper and lower chambers without mechanical stirring, the distribution system causes the primary liquid medium to be admitted to the pipes substantially uniformly across the transverse cross-section of the lower chamber and the pressure drop (.DELTA.P.sub.