Method for implementing trapping and separation of CO2 in flue gas by adopting magnesium-based absorbent

The invention discloses a method for implementing trapping and separation of CO2 in flue gas by adopting a magnesium-based absorbent and relates to a CO2 trapping and separation technology. According to the invention, Mg(OH)2 suspension is used as the absorbent for CO2 in the flue gas; compared with the existing CO2 trapping capacity, the CO2 trapping capacity of the method is finally greatly improved by controlling conditions of a suitable solid-to-liquid ratio of the suspension, a ratio of the absorbent to the flue gas and the like; and a food-grade CO2 product with high purity is also obtained. The method disclosed by the invention has strong CO2 trapping capacity, simple process, low trapping agent regeneration cost and strong technical applicability.