Method for purifying potassium nitrate from waste potassium nitrate obtained from chemical toughened glass production

Abstract

The invention discloses a method for purifying potassium nitrate from waste potassium nitrate obtained by chemical toughened glass production. The method comprises the following steps: crushing waste potassium nitrate to obtain a raw material A; adding water into the raw material A, and stirring to obtain a potassium nitrate mixed solution B; repeatedly adding the raw material A into the potassium nitrate mixed solution B, stirring and filtering to obtain filtrate C and a semi-finished product potassium nitrate salt; heating the filtrate C, repeatedly adding the raw material A again, stirring and filtering to obtain filtrate D and a semi-finished product potassium nitrate salt; adding water into the filtrate D, cooling to normal temperature, stirring and filtering to obtain a semi-finished product potassium nitrate salt and filtrate E; and drying the obtained semi-finished product potassium nitrate salt, and removing ash in the semi-finished product potassium nitrate salt to obtain an industrial potassium nitrate product. The method can obtain a high-purity potassium nitrate product, and is high in potassium nitrate recovery rate, simple in process condition, energy-saving, environment-friendly and low in production cost.

Description

technical field [0001] The invention relates to a method for purifying potassium nitrate from waste potassium nitrate, in particular to a method for purifying potassium nitrate from waste potassium nitrate obtained from tempered glass production. Background technique [0002] The glass tempering process is to heat the glass plate to a temperature of 400°C to 420°C, and then soak the glass plate in potassium nitrate molten salt or mixed salt at 400-450°C for several hours. At this time, the glass containing sodium ions with small radius is submerged in the molten basin containing potassium ions. Driven by the concentration gradient, the sodium metal ions in the glass will exchange with the potassium ions with large radius in the molten salt, resulting in an interdiffusion process. Potassium ions occupy the positions of sodium ions to generate surface compressive stress. Chemically toughened glass is finally obtained after size ion exchange. After potassium nitrate has been ...

AI Technical Summary

Problems solved by technology

[0004] CN104310444A discloses a method for extracting potassium nitrate from waste potassium nitrate raw materials produced by chemically toughened glass, 1) placing waste potassium nitrate in a reaction device and heating to form a molten liquid; 2) adding purified potassium nitrate to the molten solution 3) Add water after cooling the clarified liquid, and then heat to fully dissolve it into a semi-finished solution; 4) Put the semi-finished solution in a cooling device for cooling crystallization, filtration, and recrystallization , to obtain potassium nitrate product by drying; the invention adopts the method of heating, cooling and recrystallization to purify potassium nitrate, which increases energy consumption and poor economic benefit

[0005] CN102515491A discloses a method for removing potassium nitrate impurity ions on-line in chemical tempering production. Add an appropriate amount of treatment agent (potassium pyroantimonate) to the potassium nitrate in the state of stopping the tempering operation, and stir it at the same time so that the reaction is uniform and sufficient; After the melt is fully clarified, the chemical toughening operation is restarted; this method uses a precipitant to purify potassium nitrate, and the process conditions are relatively high and the purification cost is high