Ferro Chrome Slag: An Alternative Mould Material in Ferrous and Non-ferrous Foundries

Abstract

Various efforts are being made to use industrial wastes as an alternate moulding material in the foundry industry. Ferrochrome (Fe–Cr) slag has many of the same attributes of sand. Hence, in this paper, investigations were carried out on the suitability of Fe–Cr slag as mould material for either full or partial replacement of existing silica sand in the foundry industry. Owing to the superiority, sodium silicate–CO2 process was adopted for evaluating the same. The process parameters considered for this investigation were percentage of sodium silicate and CO2 gassing time. A series of sand tests were carried out on silica sand, Fe–Cr slag individually and various combinations of these two. Three types of moulds were made with Fe–Cr slag, silica sand individually and combination of these two with 8 %sodium silicate and 15 S CO2 gassing time. Various ferrous and non-ferrous castings were performed on these newly developed slag moulds. Results reveal that mould permeability, compression and shear strength of Fe–Cr slag are suitable candidates for either partial or full replacement of moulding sand. During casting, no burning, dripping nor collapse of the mould walls was observed in slag moulds; this is true for both ferrous and non-ferrous castings. Castings with good surface finish, no surface defects and without porosity were made by slag moulds. Slag moulds show faster solidification rates than sand moulds. Faster heat transfer in slag moulds enables obtain castings with enhanced metallurgical and mechanical properties like, hardness, compression and tensile with improved elongation.