As shown in the table, in the same distribution width cases, the grade of tailings is increased by the addition of pitch; distribution width is decreased by the addition of pitch.

The scavenging effect of 900mm pitch ball mill has the output of 3.42t/h, the productivity of 32.18%, grade of concentrate mineral 17.46%, recover rate 17.16%, and comprehensive efficiency of 27.74%. In summary, the 1500mm spiral gravity separator with 900mm pitch is suited for the scavenging task.

The concentrated mineral of ball mill then into the spiral gravity chutes of the ball mill process, it is required that the grade of tailings is 65-67%, the distribution width is about 170mm. Take the distribution width test firstly.

As shown in the above table, in the same distribution width, the grade of concentrate is increased by increasing pitch.

The result of that the 900mm spiral classifier has the best beneficiation effect that with high recovery rate and low losing rate in the cases of same grade concentrate ore.