12 LIME, DOLOMITE AND MAGNESIA BUILDING CEMENTS FOR USE IN THE REFRACTORY LININGS OF INDUSTRIAL FURNACES; CALCINED MAGNESIA REFRACTORIES FOR USE AS MORTARS AND RAMMING MIXES IN METALLURGICAL FURNACES AND OTHER HIGH TEMPERATURE FURNACES REQUIRING REFRACTORY LININGS AND CHROME ORE FOR USE IN METALLURGICAL FURNACES