A grinding circuit includes ore and fluid feed lines, a grinding mill connected to the feed lines, a grinding chamber to produce a crushed resultant fluid having ground fines and large particulate therein, a cyclone for receiving crushed resultant fluid having ground fines and large particulate and for expelling at least part of the fluid and the ground fines and dispelling a remainder of the fluid, large particulate and another part of fine grounds gravity flow, a pump to cause the first crushed resultant to flow into the cyclone, a second fluid feed line. A density separator receives the remainder and additional fluid to cause upflow current therethrough such that a part of mixed fluids and the large particulate gravity flow to the grinding mill and at least part of the mixed fluids and another part of the ground fines are circulated back to the cyclone.