(under the class definition) Processes which include the treatment of a sludge obtained in the refining of mineral oils to recover additional mineral oil values therefrom.
(1) Note. This subclass contains, for example patents dealing with the treatment of the sludges obtained as a result of the sulfuric acid or aluminum chloride refining of mineral oils.
(2) Note. When the recovery of the inorganic compound (e.g., sulfuric acid) is specifically claimed the patent will be classified in Classes 23, Chemistry: Physical Processes and 423, Chemistry of Inorganic Compounds, whether or not mineral oil is also recovered. Processes wherein an organic compound such as an organic sulfonic acid or sulfonate is recovered in addition to a mineral oil are classified in this subclass and cross referenced to Class 260, Chemistry of Carbon Compounds, when desirable. Class 260 provides for such organic compound recovery processes when no mineral oil is recovered.
SEE OR SEARCH THIS CLASS, SUBCLASS:
266+, for the sulfuric acid refining of mineral oils.
SEE OR SEARCH CLASS 423, Chemistry of Inorganic Compounds,
522+, for the manufacture of sulfuric acid by a chemical reaction.
585, Chemistry of Hydrocarbon Compounds,
240+, for the production of a hydrocarbon mixture from nonmineral oil "waste" products.
588, Hazardous or Toxic Waste Destruction or Containment, appropriate subclasses for the destruction of hazardous or toxic waste refining sludge.
