Abstract: The conventional medium adding mode suffers from the drawbacks of being long in delay time, low in efficiency and high in energy consumption. To tackle these problems, Daichiba Plant opts for the use of the equal-separating density gravity-flow medium adding method instead. With the use of the system, the medium suspension is prepared according to required separating density and the density of the medium suspension added is in consistent with that of the suspension circulating inside the system; the suspension can flow into the qualified medium tank by gravitational potential; and the preparation, mixing and discharge of medium suspension can be made on centralized control console with PLC to effect automatic adding of medium suspension. Practice shows that the use of the automatic medium adding system has led to higher stability of washing operations, a rise of yield of flotation concentrate by 0.75 percentage point, higher medium adding efficiency and both reduced energy consumption and operating cost.