| 摘要 |
A process for making sodium bicarbonate from Nahcolite-rich solutions utilizes solubility suppression with addition of salt. Hot water pumped into a Nahcolite-rich formation, which may contain salt (NaCl) and other impurities in excess of 6% by weight, dissolves the Nahcolite (NaHCO3) and salt. The dissolved Nahcolite is brought to the surface as a pregnant brine liquor containing Nahcolite, salt, and other impurities, which is then de-gassed under pressure. The pregnant liquor is then mixed with a salt slurry and its temperature reduced to saturate it with salt and force precipitation of Nahcolite out of the pregnant liquor. Carbon dioxide (CO2) is injected while mixing the pregnant liquor with the salt to facilitate precipitation and conversion of any sodium carbonate (Na2C3) present into sodium bicarbonate (NaHCO3). The sodium bicarbonate (NaHCO3) is dewatered and filtered to form a sodium bicarbonate (NaHCO3) filter cake, which is washed with fresh cold water to remove salt (NaCl), sodium carbonate (Na2CO3), and other impurities as a salt-rich brine filtrate, and the filter cake is dried to produce a high grade of natural sodium bicarbonate (NaHCO3). The filtrate may be processed to produce hot water condensate which can then be used to dissolve the Nahcolite, and the salt slurry produced can be used to saturate the pregnant liquor and force Nahcolite precipitation, and a portion may be dried and used as a saleable by-product.
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