Salt recovery from aluminum black dross

A process for recovering salt from a brine, comprising:

• tumbling a bed of salt crystals within a heated environment to maintain a heated, exposed, upper bed surface by confining the bed in a cylinder and rotating the bed about a horizontal axis of the cylinder;
• heating the environment with a source of heat kept separated from the bed so that the environment exposed to the bed is not contaminated by the source of heat;
• measuring the temperature of the bed directly from within the bed;
• spraying the brine onto the exposed upper bed surface to form new crystals as the sole source of replenishment of the bed while spraying;
• controlling the quantity of spray onto the bed surface in response to the temperature sensed in the bed so as to maintain the upper surface of the bed at a temperature high enough to evaporate all of the liquid in the brine without liquid penetrating deeply into the bed and at a temperature low enough to substantially eliminate entrainment of salt in the evaporated liquid;
• and
• wherein the tumbling forms a crescent-shaped bed, as viewed from an end of the cylinder, the temperature of the bed is measured near the surface of the bed near the lower end of the crescent, the bottom surface of the crescent-shaped bed is in contact with the heated cylinder, the top surface of the crescent forms a chord in the cylinder, with the bed crystals cascading from the high side of the top surface to the low side of the top surface, the spray impinges upon the top surface of the crescent at the high side near the beginning of the cascade, and the evaporation is completed before the cascading bed crystals reach the wall of the cylinder at the low side of the top surface.