Corrosion of selected hard facing materials exposed to mine water.

Abstract

Corrosion damage can cause major failure of mining pumps which could lead to degradation of other mining equipment, as a result of leakage, thus leading to a high rate of replacement and maintenance of pumps and surrounding equipment. Hard facing materials are used to protect moving parts against mechanical and corrosion damage. The corrosion behavior of a corrosion resistant Hastelloy G30 and a hard facing material, a nickel-chromium-iron (Ni-Cr-Fe) alloy (both high chromium nickel-based alloys) exposed to synthetic and acidified mine water were studied using potentiodynamic polarisation. The results showed lower corrosion rates for Hastelloy G30 than for Ni-Cr-Fe. The corrosion rates at pH 6.8, at ambient temperature and 35 C were 0.00011 mm.y−1 and 0.00035 mm.y−1 for Hastelloy G30; 0.0016 mm.y−1 and 0.0017 mm.y−1 for INCONEL Alloy 600, and at pH 3, at ambient temperature and 35 C corrosion rates were 0.0003 mm.y−1 and 0.00083 mm.y−1 for Hastelloy G30; 0.1 mm.y−1 and 3.2 mm.y−1 for INCONEL Alloy 600. The microstructures of the alloys before and after corrosion tests were characterised using optical microscopy; X-ray diffraction (XRD), and microhardness measurements were also performed.