Systems and methods for recovering salts, aluminum, alumina and ammonia from salt slag waste generated in aluminum recycling

A system for recovering alumina from salt slag waste generated in aluminum recycling, the system comprising:

• a. a grizzly scalper for separating any dry particles of the salt slag above a first pre-determined size, the first pre-determined size being between 80 mm and 120 mm, wherein such particles above the first pre-determined size may be broken to a size below the first pre-determined size;
• b. a feed hopper for receiving and conveying the dry salt slag particles below the first pre-determined size to a sizing screen, the sizing screen separating the slag particles into two batches, the first batch being less than a second pre-determined size, the second batch being greater than the second pre-determined size, wherein the second pre-determined size is a value between 3 mm-5 mm;
• c. a hammer mill crusher for crushing the second batch of dry salt slag particles so that the non-metallic particles thereof are less than the second pre-determined size;
• d. an eddy current separator for removing metallic particles from the second batch of crushed dry salt slag particles;
• e. an attrition scrubber for scrubbing with water the first batch of dry salt slag particles and the crushed second batch of dry salt slag particles, with metals removed, to release the salt into the water and form a mixture of alumina particles and salt brine;
• f. a first sump and pump for collecting the mixture of alumina particles and salt brine and further diluting the mixture to a liquid to solid ratio of between 0.9 mL/g and 1.1 mL/g;
• and
• g. a vented alumina press for dewatering the mixture of alumina particles and salt brine, resulting in alumina cake and salt effluent, and wherein the pump of the first sump and pump conveys the diluted mixture of alumina particles and salt brine from the sump to the vented alumina press.