FINES REMOVAL FROM MOULDING SANDS.

Silica sand approaching the original concentrated-fraction structure can be produced by heating the molding sand for 2 h at 700 degree C or by allowing 3 separation cycles in the unit. The 0315, 020 and 016 sieves retain 89. 10 percent of the major size fractions. The fines content of the regenerated silica sand remains higher than originally, 1. 68 compared with 1. 42 percent. The recovered fines contain more than 80 percent of alumina cement and can be used to replace a similar amount of fresh alumina cement in subsequent mixings.