Method for preparing white clay calcium carbonate by performing low-temperature two-step causticization on non-wood pulp alkali recovery green liquid

[0015] The first step of causticization: Add the green liquor recovered from non-wood pulping alkali to the completely digested lime water to cause causticization reaction. The amount of lime is 5% of the total amount of causticized lime, and the green liquor addition rate per gram of quicklime is 0.02ml / min; the reaction temperature is 10°C, the stirring speed is 50rpm, and the reaction time is 100min. After the specified reaction time was reached, the precipitate was separated and removed by filtration.

[0016] The second step of causticization: adding the remaining 95% lime to the filtered filtrate to continue causticization, the reaction temperature is 60°C to increase the causticization reaction speed, continue to react for 30 minutes, or continue to react for 5 hours at the original temperature, filter and separate, wash , get white mud calcium carbonate with regular shape.

[0018] The first step of causticization: add the green liquor recovered from non-wood pulping alkali to the completely digested lime water to cause causticization reaction. The amount of lime used is 20% of the total amount of causticized lime, and the green liquor addition rate per gram of quicklime is 0.8ml / min; the reaction temperature is 5°C, the stirring speed is 2000rpm, and the reaction time is 5min. After the specified reaction time was reached, the precipitate was separated and removed by filtration.

[0019] The second step of causticization: adding the remaining 80% lime to the filtered filtrate to continue causticization, the reaction temperature is 80°C to increase the causticization reaction speed, continue to react for 86 minutes, or continue to react for 2 hours at the original temperature, filter and separate, wash , get white mud calcium carbonate with regular shape.

[0021] The first step of causticization: add the green liquor recovered from non-wood pulping alkali to the completely digested lime water to cause causticization reaction. The amount of lime is 40% of the total amount of causticized lime, and the green liquor addition rate per gram of quicklime is 1ml / min; the reaction temperature is 39° C., the stirring speed is 20 rpm, and the reaction time is 180 min. After the specified reaction time was reached, the precipitate was separated and removed by filtration.

[0022] The second step of causticization: adding the remaining 60% lime to the filtered filtrate to continue causticizing, the reaction temperature is 100°C to increase the causticizing reaction speed, continue to react for 120 minutes, or continue to react for 12 hours at the original temperature, filter and separate, wash , get white mud calcium carbonate with regular shape.