Permeability Number for Various Grain Size of Tin Mine Tailing Sand for Greensand Casting Mould

Abstract

Tin tailing sand is one of the residues from tin extraction. Tailing sand for sampling was taken from Batu Gajah, which was one of the active locations in tin mining in Malaysia. The silica content of tailing sand from Batu Gajah is between 95.9 to 98.9%. This research is to determine the effect of grain size by the increasing of water content on the permeability number. Grain size is a major determinant of mould and core permeability and surface finish of the casting. In this research involved the process of conducting the mechanical sieve grading to identify the grain size for this research. Sample was graded into 425 μm, 297 μm and 149 μm. Experiments were conducted according to American Foundrymen Society (AFS) standard of procedures. Cylindrical test pieces dimensioning of Ø50 mm×50 mm in height from various grain sand sizewater ratios bonded with 5wt% clay, were compacted by applying three ramming blows of 6666 g each using Ridsdale-Dietert metric standard rammer. The test pieces were tested for permeability number with Ridsdale-Dietert permeability meter. Grain sand size of 297 μm was discovered has appropriate permeability number with the water content of 4% which is within the requirement as moulding sand.