The　copper　ore,　which　has　fine-grained　nature　and　differences　in　the　degree　of　mineral　dissemination,　is　a　kind　of　low　grade　sulfide　minerals.　Tests　indicate　that　not　only　the　grinding　fineness　but　also　the　combination　mode　of　depressants　is　one　of　the　most　important　factors　to　improve　the　concentrate　grade　index.　Additionally,　according　to　tests　conducted　with　dosage　of　lime,　the　rougher　flotation　should　be　operated　at　a　pH　of　11.　Furthermore,　all　the　depressants　used　were　effective　to　increase　the　concentrate　grade.　By　the　closed-circuit　micro-flotation　experiment,　satisfied　grade　index　(18.7%Cu　with　81%　recovery)　of　the　final　concentrate　was　achieved,　which　could　provide　reference　in　industrial　applications.　©　(2014)　Trans　Tech　Publications,　Switzerland.