Method for directly producing potassium nitrate end product from complex nitrate bittern

Abstract

The invention discloses a method for directly producing a potassium nitrate end product from complex nitrate bittern. The method comprises the following steps of 1, setting a mirabilite freezing tank, a primary sodium salt tank and a secondary sodium salt tank, feeding bittern into the mirabilite freezing tank, the primary sodium salt tank and the secondary sodium salt tank, and carrying out fractional crystallization and evaporation to obtain deposited halogens from a salt pan, 2, precipitating Ca<2+> and Mg<2+> impurities of the deposited halogens respectively through caustic soda and soda ash, 3, mixing the impurity-free deposited halogens and a salt which is discharged by an effect II evaporation unit and is obtained by a step 6, removing potassium of the removed salt, and carrying out centrifugal separation, 4, feeding washing liquid into a secondary reaction tank, and adding potassium chloride into the secondary reaction tank for a stirring reaction to obtain a transformed mother solution, 5, mixing the transformed mother solution and cold-separated liquid obtained by the step 8, 6, after halogen mixing, feeding the transformed mother solution mixture into a four-effect evaporation system, carrying out step-by-step evaporation precipitation to remove sodium salts, discharging the salt-free evaporated mother solution from an effect I evaporation unit, and the salt from the effect II evaporation unit, 7, after the salt-free evaporated mother solution discharged from the effect I evaporation unit enters into a three-level series vacuum cold separation system, and carrying out step-by-step crystallization salt precipitation, and 8, carrying out centrifugal separation of the cold-separated liquid, and carrying out solid washing and drying. The potassium nitrate end product prepared by the method has KNO3 content great than or equal to 98%.

Description

technical field [0001] The present invention relates to a kind of production method of industrial potassium nitrate, especially relate to a kind of using + 、Na + , Mg 2+ , Ca 2+ , SO 4 2- , Cl - , NO 3- A method for the direct production of potassium nitrate from complex nitrate-type brines by plasma. Background technique [0002] At present, the methods for industrial production of potassium nitrate mainly include the following categories: (1) ion exchange method, such as directly dissolving and recrystallizing the finished product sodium nitrate and potassium chloride; (2) double decomposition method: such as application number 200510094223 The Chinese patent of .X discloses a method for preparing potassium nitrate by double decomposition method. The raw material potassium chloride, ammonium nitrate and process water are mixed and cooled to obtain potassium nitrate, and the mother liquor is evaporated and concentrated, then cooled and crystallized to obtain ammoniu...

AI Technical Summary

Problems solved by technology

The combination of the two is theoretically feasible as a method for preparing finished product potassium nitrate from natural complex nitrate-type brine, but the route is too long, the loss of potassium is relatively large, and the semi-finished product needs to continue to dissolve before it can be mixed with potassium to produce potassium nitrate, and the water consumption is also relatively high. Big

Through literature research, no method has been found to directly extract high-quality potassium nitrate products from the liquid phase of salt lake brine