This invention relates broadly to the treatment of motor oils. In accordance with one aspect of the invention it relates to ammonium sulfate-bisulfate solutions used in the treatment of used motor oils. In another of its aspects, it relates to the treatment of ammonium sulfate-bisulfate solutions for the removal of metal and other contaminants which form ash. In yet another of its aspects, it relates to the recycling of ammonium sulfate-bisulfate solution in the reclaiming of used motor oils.
There is an ever increasing concern for the conservation of our petroleum reserves and the best use of products derived from them. The reclaiming of used motor oil has, therefore, become very important. Among the best processes for recovering used motor oil is the treatment set out in U.S. Pat. No. 3,930,988 using an aqueous solution of ammonium sulfate and/or ammonium bisulfate which produces a purified oil that can be used as a burning oil substantially free of the harmful lead and other additives of modern lubricating oils, that can be reprocessed by means of conventional hydrotreating processes to yield a high grade lubricating oil-base stock that can be recompounded to give high grade lubricating oil, or that can be used as a heating oil or road oil. The process is also designed to recirculate the process material and the processing material in such a way that compounds potentially hazardous to the environment are removed with no ecological problem being produced.
It has been discovered in this process, however, that in the recycling of the aqueous solution of ammonium sulfate and/or ammonium bisulfate used in the process that the recycled solution can become saturated with a solid material that is based on contamination of the solution with metal and other ash forming contaminants, for example contamination with zinc in which the contaminant has been described as having the probable formula (NH.sub.4).sub.2 Zn(SO.sub.4).sub.2.6H.sub.2 O. The recycle solution can become so heavily saturated with contaminant that the material can be deposited on the walls of reaction vessels and in the piping. Since deposition of the solid material is detrimental to the process, it is imperative that the zinc contaminant be minimized in the recycled solution.
It is therefore an object of this invention to provide a method for minimizing metal contaminant in a solution of ammonium sulfate and/or ammonium bisulfate. It is another object of this invention to provide an improved method for regenerating ammonium sulfate/ammonium bisulfate solution recycled in the treatment of used motor oil. It is still another object of this invention to provide an improved method for reclaiming used motor oil.
Other aspects, objects and the various advantages of this invention will become apparent upon reading this specification, studying the drawings, and the claims of this application.