Method for utilizing combined reagents to improve copper concentrate grade of carbonic copper oxide ores

The invention relates to a method for utilizing combined reagents to improve the copper concentrate grade of carbonic copper oxide ores. The method includes the steps that nigrosine and sodium sulphide combined reagents are added into the raw ores in an ore mill, and then O-isopropyl-N-ethyl thio-carbamate and sec-octyl xanthate are adopted to carry out floatation to obtain an enriched oxidized copper sulphide mixed rough concentrate; the nigrosine and sodium sulphide combined reagents are added into the enriched oxidized copper sulphide mixed rough concentrate, floatation operation is carried out when the enriched oxidized copper sulphide mixed rough concentrate is ground to the grinding fineness required by separation of copper ores and carbonic matters, collecting agents, namely, the O-isopropyl-N-ethyl thio-carbamate and the sec-octyl xanthate are added to the enriched oxidized copper sulphide mixed rough concentrate, the enriched oxidized copper sulphide mixed rough concentrate is selected to obtain fina