Manufacture of refractory products

This class includes: manufacture of intermediate products from mined or quarried non-metallic minerals e.g. gravel, stone or clay - manufacture of refractory mortars, concretes etc. - manufacture of refractory ceramic goods e.g. • heat-insulating ceramic goods of siliceous fossil meals • refractory bricks, blocks and tiles etc. • retorts, crucibles, muffles, nozzles, tubes, pipes etc. This class also includes: - manufacture of refractory articles containing magnesium oxide, calcium magnesium oxide or chromite