Process for reclaiming used oil coolants

The treatment of used coolants comprises the addition of an alkali or acid to the oil to give a pH ≤ 3 or ≥ 10. By means of two electrodes the solution is then electrolysed using a voltage of 10-20 V, a current of 15-25 A and a current density of 1-5 A/dm . The consumption (C) is 15-25 wh/l. The emulsion is destabilised and the separated oil can be withdrawn. 1-3 g/l of iron chloride (FeCl2) is added to the remaining liquid and the solution is electrolysed at 9-14 V and a current density ≥ 4 A/dm . The consumption is 60-100 wh/l and the final pH is ≤ 3 or ≥ 10. Alkali is then added to a pH of 8-9 and a muddy precipitate is obtained which is separated from a residual water effluent only slightly polluted by oil and organic compounds. Processus de traitement d'huiles usées de refroidissements, de celles contenant une émulsion eau-huile et une dissolution d'eau-composés organiques, qui se compose de trois phases consécutives : a) à l'huile de refroidissement on rajoute un alcali ou un acide jusqu'à obtenir un pH de : pH = 10, on électrolyse, l'émulsion devenant instable, ce qui permet que soit retirée l'huile flottante; b) en rajoutant au liquide restant, du chlorure de fer Cl2Fe en quantité de 1 ÷ 3 g/l et en électrolysant on obtient un pH final de pH = 10, pour procéder à, c) son alcalinisation pour arriver à un pH de 8