Magnesium tailing admixture as well as preparation method and application thereof

The invention relates to the technical field of building materials and the technical field of comprehensive utilization of solid waste resources, in particular to a magnesium tailing admixture as well as a preparation method and application thereof. The preparation method of the magnesium tailing admixture comprises the following steps: 1) uniformly mixing magnesium tailing powder with borax to obtain a mixture, heating the mixture to 850-950 DEG C, and then carrying out heat preservation treatment; after heat preservation is finished, coal gangue powder is added into the mixture, the mixture is stirred to be uniform and cooled, and a product A is obtained; and 2) adding zeolite powder, sodium silicate, a grinding aid and xanthan gum into the product A, uniformly mixing, and grinding to obtain the magnesium tailing admixture. The prepared magnesium tailing admixture can be used as a cementing material to be added into concrete, so that high-doping-amount use of the dolomite magnesium tailings in cement concre