Abstract: Floating mineral substances such as oil or petroleum are separated from water by collecting the mixture in the inlet of a separator tank having a generally L-shaped baffle with surface irregularities formed on the vertical wall of the baffle and with the mixture flowing through the bottom wall into a pyramidal shaped storage section which by means of its shape causes the water to flow downwardly into the storage section and the oil to float on top into an oil chamber, with pumps being provided to remove the oil from the oil chamber and to maintain the water at the proper level in the storage section.