Treatment of cold rolling coolant for steel by HGMS

The usual cold rolling coolant of steel sheets deteriorates due to accumulation of iron fines. Removal of iron fines and decrease of accompanied effective oil were studied by using high gradient magnetic separation (HGMS). It was revealed through analysis of experimental results that oil removed together with iron fines depends upon the captured iron fines amount on matrix and that oil/iron ratio in the mixture loaded on matrix can be decreased by control of captured iron fines amount; For example, the ratio can be decreased to about 1.5 when flow rate at matrix is 0.11m/s and the captured iron fines on wires is 0.4kg-iron/kg-wire. A production-scale HGMS device installed at a cold rolling plant shows high iron removal efficiency and low oil removal ratio. Moreover, the device is working well with no maintenance for 2 to 6 months by adoption of a new flushing system of matrix using steam, hot water and compressed air.