Treatment methods for thiourea waste residues

Check out this patent: Application number CN91107122.9. Date of patent application: 1991.01.25. Title: Method for the recovery and utilization of thiourea waste residues. Publication (announcement) number: CN1054231; Date of publication (announcement): 1991.09.04. Category: Chemistry； Metallurgy. Date of grant; Priority date for application (patent rights). Jiangyou Chuabei Northwest Mining Area Labor Service Company. Address: 621709, Jiangyou City, Sichuan Province, Jiangyou Chuabei Northwest Mining Area Labor Service Company. Inventor: Huang Cheng. International applications; International publication; Date of entry into force. Patent agency; Agent. Abstract: This invention discloses a method for the recovery and utilization of thiourea waste residues. By using this method, it is possible to completely process and utilize such residues, thereby reducing the cost of thiourea products and eliminating the environmental pollution caused by these residues. 　 A method for the recovery and utilization of thiourea waste, characterized in that hydrogen sulfide gas is introduced into the fresh waste slurry, causing calcium hydroxide present in the waste to react with hydrogen sulfide to form calcium hydrosulfide; after filtration, a calcium hydrosulfide solution is obtained, while the remaining waste from the reaction is mixed with carbon in a weight ratio of 10–30% to be used as fuel.