A Slovak foundry is interested in exchanging experience in the field of circular economy. Do you have any examples or ideas how other Danube region countries treat following waste code?: 100903 (furnace slag), 100906 (casting cores and moulds which have not undergone pouring other than those mentioned in 10 09 05), 100908 (casting cores and moulds which have undergone pouring other than those mentioned in 10 09 07), 100910 (flue-gas dust other than those mentioned in 10 09 09), 110502 (zinc ash).