Early-strength fluoride-free alkali-free liquid accelerator and preparation method thereof

The invention discloses an early-strength fluorine-free alkali-free liquid accelerator and a preparation method thereof, and the accelerator is prepared from the following components in percentage by weight: 40-52% of polyaluminum sulfate, 3-8% of magnesium sulfate, 5-10% of lithium sulfate, 6-12% of diethanol amine, 1-3% of ethylene glycol, 5-12% of modified nano metakaolin, 1-3% of a suspending agent, 1-3% of oxalic acid and the balance of water, totaling 100%. The preparation method of the accelerator comprises the following steps: dissolving polyaluminum sulfate, magnesium sulfate and lithium sulfate in water, and stirring for 1-2 hours; the temperature and the stirring speed are kept unchanged, diethanol amine and ethylene glycol are slowly dropwise added, and dropwise adding is completed within 0.5-1 h; adding the modified nano metakaolin and the suspending agent, and stirring for 0.5-1 hour; the temperature and the stirring speed are kept unchanged, oxalic acid is added, the pH value of the solution is