A system for cooling and recuperative heating of a slurry in a metallurgical process which includes heat exchangers, pumps and autoclaves is described herein. The heat exchangers use a non-scaling common liquid heat transfer medium. Preferably, the heat exchangers are tube-in-tube heat exchangers with 3 to 7 slurry tubes in each heat exchanger. An advantage of this system is that it does not use flash tanks. To minimize abrasive wear on impinged surfaces, the velocity of the slurry is not more than 5 meters per second. The slurry comprises a solids concentration of 25% to 50%. Preferably, the pumps in the system are float-type pumps in which the driven liquid from the discharge pumps is also used as the drive liquid for the feed pumps.