Method for preparing aluminum-silicon-iron alloy by virtue of aluminum-ash pre-treatment carbothermic reduction

The invention provides a method for preparing an aluminum-silicon-iron alloy by virtue of aluminum-ash pre-treatment carbothermic reduction. The method comprises the following steps that secondary aluminum ash, waste cathode carbon blocks and paper pulp dry powder are uniformly mixed and are made into powder, then the mixture is pressed into pellets, and is subjected to high-temperature vacuum distillation, so that fluoride and chloride in the aluminum ash as well as fluoride and metal sodium in the waste cathode carbon blocks are volatilized and then are separated from the aluminum ash and the waste cathode carbon blocks respectively, and meanwhile, cyanide in the waste cathode carbon blocks is decomposed; then distillation residues are smashed, the smashed distillation residues are matched and mixed with fly ash, high-temperature reduction is conducted on a material mainly composed of aluminum oxide and silicon dioxide in an electric arc furnace by taking fixed carbon in the waste cathode carbon blocks as a