storing the eluent, temporarily storing the eluent in a high-level tank;
Adding alkali for blending, (1) separate blending method, measure the specific gravity of the eluent to 1.02, and put the eluent into the blending tank after the pH value is 8. After turning on the agitator in the blending tank, slowly add lye and measure its pH value from time to time. When the pH value reaches 10, feed it and turn on the liquid circulation pump in the tank until the liquid is uniform, and then measure the pH value of the blended liquid. The liquid with adjusted pH value is pumped into the sedimentation tank. When the liquid in the sedimentation tank reaches two-thirds of the tank body, record its specific gravity and pH value. (2) Mixing and blending method. When the color of the mother liquor separated from the recovered crystal is yellowish brown, the mixed and blending method is used; after quantitatively adding the eluent, slowly add the lye while stirring to make the pH value reach 10. The specific operation is the same as the separate blending . After pumping the mother liquor quantitatively, turn on the circulating pump until the liquid in the tank is mixed evenly. The specific gravity of the liquid after reconciliation should change accordingly with the change of room temperature. When the liquid in the sedimentation tank reaches the designated position, the specific gravity and PH value of the liquid in the tank should be measured and recorded (note: there is a liquid level indicator mark in each tank).
Precipitation and separation are carried out, the liquid is mixed with alkali and the pH value is adjusted, and the clarified blended liquid is extracted into the reaction kettle. Each tank of residual liquid and sediment is pumped from the bottom outlet of the tank into the designated temporary storage tank. When the sodium phytate liquid in the tank reaches three quarters of the temporary storage tank, the plate and frame filter is opened, and the filtrate at the plate and frame outlet is After clearing, the clear liquid enters the sedimentation tank, and the solid matter remaining in the plate frame is sent to the slag yard.
Carry out vacuum concentration, turn on the vacuum pump, and when the vacuum degree in the reactor reaches -0.6MPa, open the feed valve to suck the supernatant in the sedimentation tank that has been precipitated and clarified. When the liquid in the reaction kettle reaches the end of the indicating thermometer (the liquid in the kettle is about 0.4m3), stop adding clear night. If it is found that the vacuum degree of the system is not high, check the closing status of the valves in the reaction kettle and the system. If the piston of the hydraulic injection system is not well sealed due to long-term work, the gasket should be replaced. If the temperature in the kettle rises too fast due to unstable steam pressure, the inlet valve should be adjusted in time.
Carry out crystallization and centrifugation, and the liquid concentrated in place (specific gravity 1.4) is pumped into the crystallization tank through natural cooling or water cooling, and the volume, temperature and specific gravity of the liquid are recorded to allow it to crystallize naturally. After the crystallization is completed, the crystal liquid is put into the separation tube, and the separated mother liquid is pumped to the mother liquid storage tank. The crystals separated from the mother liquid are mixed with water in the bucket and then put into the centrifuge for centrifugal separation.
Carry out constant temperature drying and drying to obtain the final sodium phytate, and do a certain cleaning work on the drying tool to prevent impurities from being brought in and polluting the sodium phytate. The material (wet sodium phytate crystals) is evenly distributed on the tray and dried at a constant temperature. When the oven is started to work, the steam should be opened to flush the steam pipeline to ensure that the electronic valve can work normally. Before starting to dry the materials, the lower low limit and upper upper limit of the initial temperature should be properly adjusted according to the season. In principle, the temperature difference between the upper and lower limits should be controlled at 2~9°C, and the temperature should be gradually raised to 65°C and kept at this temperature for continuous drying. Each work (drying) is about 24 hours, and the exhaust port of the oven should be closed when the machine is shut down in the middle, so as to prevent the material from being poured into the box at night and cause the material to regain moisture. If the automatic alarm alarm occurs during the operation of the oven, the air intake should be stopped first, and the reasons should be checked after ventilation: 1) Whether the electronic valve is malfunctioning; 2) Whether the temperature control adjustment is placed in the normal position; 3) The amount of steam intake is too large. Samples should be tested after each batch of drying. The quality standards of the tested items are shown in Table 1. Products that pass the test are packed in 25kg barrels or as required by customers. The plastic bag lined with the packaging should meet the quality standards for food additives. After each bag is packed, it should be tied tightly with a plastic rope or sealed with a hot-rolled sealing machine to prevent the product from regaining moisture and agglomerating due to moisture absorption. Each batch of products should indicate the batch size and production date. If the customer has special requirements, it will be implemented according to the customer’s request. Particles in each bag that do not pass the sieve should be recovered, and this part should be re-dissolved, concentrated and recrystallized.