Flotation reagent for gold-containing thiocyanic castaway slag

The invention discloses a flotation reagent for gold-containing thiocyanic castaway slag. The flotation reagent is composed of, by weight, 200-320 parts of sodium hexametaphosphate, 1500-2500 parts of sodium silicate, 40-60 parts of ethionine ester, 30-55 parts of copper sulfate, 66-110 parts of butyl xanthate, 133-220 parts of sodium isoamylxanthate and 50-110 parts of oil No.2. The sodium hexametaphosphate is adopted for inhibiting gangue; the sodium silicate is adopted for inhibiting iron minerals; the ethionine ester Z-200 serves as a collecting agent of copper sulphide; the copper sulfate serves as an activating agent; the butyl xanthate and the sodium isoamylxanthate serve as collecting agents; the oil No.2 serves as a foaming agent. When the flotation reagent is adopted for flotation of enriched concentrate fines, the grade is greatly increased; the metal content of flotation slag is low; the recovery rate is up to 80%; the gold-containing grade of enriched concentrate is increased to 20g/t, the silver