GB369975A - Lubricating oils and method of producing same - Google Patents

Abstract

A process for making paraffin-base lubricating oils of low cold test consists in distilling the crude oil without overheating, and treating the resulting distillate first with sulphuric acid to remove tarry and asphaltic materials, then with decolorizing clay, removing the clay, and chilling the oil to from -20 DEG to -60 DEG F. and separating the wax thus precipitated. Crude paraffin-base oils are slowly distilled under low pressure with a large volume of steam, whereby distillates are obtained which are free from crystalline wax. The distillate is stored, and after ageing is treated at 115 DEG to 125 DEG F. with concentrated sulphuric acid, at which temperature asphalt is not dissolved. The purified oil is separated from the sludge, and after standing is mixed and heated with decolorizing clay suspended in oil or water. When decolorization is effected the mixture is diluted with petroleum naphtha and passed through a pressure filter to remove the clay. The filtrate is further diluted with naphtha, and the solution is slowly chilled to 10 DEG F. Thereafter chilling is effected more rapidly, e.g. by the expansion of ammonia, to produce a temperature of from -20 DEG to -60 DEG F. The precipitated wax is removed by filtering or centrifuging. The solution of dewaxed oil is then treated with low pressure steam at a temperature not exceeding 500 DEG F. to remove the solvent, an oil having a cold test of from -5 DEG to 10 DEG F. remaining. Specification 259,553, [Class 91, Oils &c.], is referred to.