Methods and apparatus for metal recovery from slag

A method for separating a metal-rich fraction from a slag composition, the method comprising:

• (a) providing said slag composition in molten form, wherein the slag composition contains one or more metal values;
• (b) feeding the molten slag composition to an atomization chamber of a gas atomization apparatus;
• (c) feeding a stream of a gas into the atomization chamber through an atomization nozzle, wherein the gas contains oxygen;
• (d) atomizing the molten slag composition with the stream of gas in the atomization chamber to disperse and solidify the molten slag composition to form solid slag granules,
• wherein the gas contains oxygen in a sufficient concentration to convert at least a portion of the one or more metal values to one or more magnetic compounds during the atomizing of the molten slag composition;
• wherein the magnetic compounds comprise one or more spinel structures having the general formula AB2O4, wherein A is a divalent cation and B is a trivalent cation;
• wherein the presence of said magnetic compounds in sufficient concentrations in a first fraction of the solid slag granules renders the granules of the first fraction sufficiently magnetic to permit them to be separated from the remainder of the solid slag granules by magnetic means;
• (e) controlling the partial pressure of oxygen in the gas so that the molten slag composition has a composition which lies in thea spinel primary crystallization phase field;
• and
• (f) magnetically separating the first fraction from thea remainder of the solid slag granules.