Curing agent for curing soil polluted by heavy metal cadmium as well as preparation method and application of curing agent

The invention discloses a curing agent for curing heavy metal cadmium polluted soil, the curing agent comprises slag, red mud, carbide slag and phosphogypsum, the mass ratio of the red mud to the slag is 1: (0.5-2), and the doping amount of the carbide slag and the phosphogypsum is 10%-20% of the total mass of the red mud and the slag. The red mud can be used as an auxiliary cementing material of the slag, and the carbide slag and the ardealite can effectively stimulate the activity of the red mud and the slag, so that the curing effect can be better achieved. The preparation method is simple and convenient, low in cost and good in performance, the prepared environment-friendly curing agent belongs to a full-solid-waste-based curing agent and is different from existing cement-based and lime-based curing agents, the environment-friendly curing agent can replace traditional curing agents such as cement and lime, and the problems of production cost, production energy consumption, carbon emission and the like are