Patent ID: 8956424
Filing Date: 2015-02-17
Classification: C01D

Abstract:
1. A purification method for recovering potassium nitrate from a solid waste that is produced by a glass-strengthening process and contains potassium nitrate and sodium nitrate, the purification method comprising the steps of: (a) heating the solid waste to a melting temperature to melt the solid waste into a liquid waste in a first purifying tank; (b) cooling the liquid waste from the melting temperature to a first temperature for facilitating the potassium nitrate contained in the liquid waste to be crystallized as potassium nitrate crystal attached to a sidewall of the first purifying tank at a first rate; (c) cooling the liquid waste from the first temperature to a second temperature that is substantially close to the freezing point of the potassium nitrate at a second rate that is slower than the first rate; and (d) collecting the potassium nitrate crystal.