METAL GRANULES

Metal beads, e.g., magnesium beads, or Mg alloy beads, having a high degree of rotundity, and having a thin coating of sludge or slag ingredients, are recovered from entrapment in a friable contiguous material of sludge or slag material by (a) a primary milling of the friable matrix in a hammer mill or impact mill, (b) screening the material to collect the desired particle sizes, (c) attriting the material in a secondary milling operation to further, and gently, grind sludge material from around the beads, and (d) separating the rotund beads from the pulverized matrix material by using a shape-classifier, such as a slanted shaker table. The material may be treated beforehand by melting the metal-containing sludge or slag, adding a flux or emulsifier material with stirring to cause dispersion of the metal into a relatively narrow particle size range and then freezing the molten mixture. The invention is especially useful in the case of Mg beads, since Mg beads are malleable and pyrophoric.