A method for producing pharmaceutical grade potassium chloride with sea salt Repone K, the steps are as follows:
(1) after the sea salt Muriate Potash is broken to loose, it is continuously and stably added to the crystallizer in proportion with the circulating mother liquor and the secondary washing liquid, and the stirring speed of the crystallizer is controlled to make the material in the crystallizer reaction zone in a fully mixed flow state; Reaction The residence time of the material in the crystallizer is 0.1 hour; the weight ratio of sea salt potassium chloride, circulating mother liquor and secondary washing liquid is 1:2:0.2;
(2) Under the premise of ensuring the stability of the system, continuous or intermittent and stable discharge of the crystallizer underflow; the weight concentration of the crystallizer underflow is 5%; The settler performs sedimentation; the overflow of the crystallizer enters the settler for sedimentation; the bottom flow of the settler is centrifuged to obtain the by-product overflow crystal and sedimentation filtrate, and the sedimentation filtrate and the primary filtrate are returned to the settler for secondary sedimentation; the overflow of the settler is the circulating mother liquor, and part of The circulating mother liquor is recycled in step (1), and the excess circulating mother liquor is discharged from the reaction system; the weight concentration of the crystallizer overflow is 0.05%;
(3) The primary product, the Muriate Potash saturated solution and the secondary washing solution are added to the stirring tank in proportion to carry out slurry mixing and washing. After stirring, the secondary product and the secondary washing solution are obtained by centrifugation, and the secondary washing solution enters the first washing solution. Washing liquid storage tank, part is recycled in this step (3), and part enters the crystallizer of step (1) to react; the weight ratio of primary product, potassium chloride saturated solution, secondary washing solution is 1: 0.5: 0.1;
(4) adding the secondary product, Muriate Potash saturated solution and deionized water in proportion to the stirring tank to carry out slurry mixing and washing, after stirring, the tertiary product and the potassium chloride saturated solution are obtained by centrifugation, and the potassium chloride saturated solution enters the first The second washing liquid storage tank, part of which is recycled in this step (4), and part of which enters the sizing and washing process of step (3); the weight ratio of the secondary product, potassium chloride saturated solution and deionized water is 1:0.5 : 0.1; the third product is pharmaceutical grade potassium chloride.
A method for producing food-grade potassium chloride by continuous crystallization of multi-stage flash evaporation and cooling, the following steps are carried out successively:
1), put 6170 kilograms of potassium chloride with a content of 96.5% into 11m3 of tap water to prepare a potassium chloride supersaturated solution, heat it to 110°C (inject steam into the jacket under stirring), and after the potassium chloride crystals dissolve Obtain potassium chloride saturated solution I, and the potassium chloride saturated solution I of gained contains 5950kg of potassium chloride in total;
2), add 48 kilograms of potassium hydroxide first to all the Muriate Potash saturated solution I (about 14.4m3) obtained in the above step 1), thereby adjusting the pH value of the potassium chloride saturated solution I to reach 12, then add 6.2 kilograms of calcium oxide Stir and dissolve, then add 11 kilograms of ammonium chloride and 30 kilograms of potassium dihydrogen phosphate respectively, and after stirring 30min, carry out thermal insulation sedimentation at 100-110 ℃ temperature, thermal insulation sedimentation time is 2 hours; , get the supernatant;
3) At 100-110 °C, filter the supernatant obtained in step 2) through a security filter with a pore size of 5 microns with thermal insulation properties, and remove the Muriate Potash saturated solution after insoluble substances (that is, the filtrate obtained by filtering ) with hydrochloric acid to neutralize to obtain potassium chloride saturated solution II (suspended solids less than 0.5mg/l, potassium chloride concentration 35.6%, Ca2+: 0.0001%, Mg2+: 0.0001%, Fe≤0.00005%, heavy metals≤ 0.00005%).
4), the potassium chloride saturated solution II with a temperature of 100-110 ℃ is transported to a DTB type I-effect flash crystallizer through a feed pump at a flow rate of 14m3 per hour for flash cooling and concentration. The temperature of the material in the Ⅰ effect flash crystallizer is controlled at 76-80℃, and the vacuum degree is controlled at -0.080Mpa～-0.086Mpa (the steam pressure 1.0Mpa steam jet compression pump is used when vacuuming, and the generated mixed steam is used as step 7 ) The preheating of the remaining potassium chloride mother liquor I, the tail gas is cooled by the vertical condenser and then pumped away by the water circulation vacuum pump), and the circulating flow of the material is the potassium chloride slurry in the crystallizer (that is, the I effect flash crystallization). 1 times the volume/hour of the volume of the equipment), until the potassium chloride slurry I obtained contains potassium chloride crystals that account for 4.2% of the total weight of the potassium chloride slurry I;
5) Muriate Potash slurry I is transported to the DTB type II-effect flash crystallizer through a slurry-type forced circulation pump for flash concentration and cooling; the material temperature in the II-effect flash crystallizer is controlled at 48-52 °C, and the vacuum degree is controlled at -0.094Mpa～-0.096Mpa (vapor pressure 1.0Mpa steam jet compression pump is used when vacuuming, and the generated mixed steam is used for the preheating of the remaining potassium chloride mother liquor I in step 7), and the tail gas passes through the vertical condenser After cooling, it will be pumped away by the water circulating vacuum pump), and the circulating flow of the material is 1 times the volume/hour of the potassium chloride slurry in the crystallizer (that is, the material amount of the II-effect flash crystallizer), until the obtained potassium chloride slurry II contains The potassium chloride crystals accounted for 10.3% of the total weight of the potassium chloride slurry II.
6) Muriate Potash slurry II is transported to the DTB type III effect flash crystallizer through a slurry forced circulation pump for flash cooling and crystallization. The temperature of the material in the III effect flash crystallizer is controlled at 18-22 °C, and the vacuum degree is controlled at -0.098Mpa～-0.099Mpa (vapor pressure 1.0Mpa steam jet compression pump is used for vacuum pumping, and the tail gas is cooled by the vertical tube condenser and then pumped away by the water circulation vacuum pump), the circulating flow of the material is the potassium chloride slurry in the crystallizer 1 times the volume/hour of the feed (that is, the feed rate of the III-effect flash crystallizer), until the potassium chloride slurry III obtained contains 15.8% potassium chloride crystals based on the total weight of the potassium chloride slurry III.
7), Muriate Potash slurry III is centrifuged (centrifugation speed is 1200 rpm, time is 10 minutes) to obtain 2770 kg of potassium chloride wet product with a water content of 2.8% and a potassium chloride mother liquor with a temperature of 20 ° C Ⅰ is 11m3 in total, of which 10% (11m3*10%=1.1m3) of potassium chloride mother liquor Ⅰ is removed from the production line of food-grade potassium chloride crystallization system, and the remaining 90% (11m3*90.0%≈9.9m3) of potassium chloride mother liquor Ⅰ is in turn Use the secondary steam generated by the II-effect flash crystallizer and the I-effect flash crystallizer for preheating, the temperature rises from 20°C to 50°C, and returns to step (1) to dissolve the raw material potassium chloride (which can be used as a solution).
8), 2770 kg of Muriate Potash wet product with a water content of 2.8% obtained by centrifugation is dried by a vibrating fluidized bed (the temperature during the drying of the vibrating fluidized bed is 125°C), and passed through a 40-mesh screen to obtain 2688 kg of food grade The potassium chloride product has a potassium chloride content of 99.7%, a sodium chloride content of 0.22%, calcium and magnesium less than 0.0001%, heavy metals and arsenic less than 1ppm, a water content of 0.1%, and an average particle size of 0.9mm.
In the present embodiment, the dissolving heat preservation process consumes 1980 kilograms of steam in total, the flash cooling crystallization process consumes 2320 kilograms of steam, the drying process consumes 820 kilograms of steam, and the steam consumption per unit is 1905 kilograms/ton potassium chloride.
