Method and apparatus for controlling specific gravity in a heavy medium process

Claim 1

IN A HEAVY MEDIUM MINERALS SEPARATION PROCESS IN WHICH MINERAL PARTICLES ARE INTRODUCED TO A WATER SUSPENSION OF MAGNETIC PARTICLES, HEAVIER MINERAL PARTICLES SINK IN THE SUSPENSION WHILE LIGHTER MINERAL PARTICLES FLOAT, THE RESULTING SINK AND FLOAT PRODUCTS ARE SUCCESSIVELY DRAINED OF SUSPENSION AND WASHED WITH WATER, BOTH THE WASH WATER AND A VARIABLE FRACTION OF THE DRAINED SUSPENSION ARE TREATED IN A MAGNETIC SEPARATOR AND A DENSIFIER TO REMOVE NONMAGNETIC CONTAMINANTS AND WATER AND THEREBY PRODUCE A DENSIFIED SUSPENSION, SAID DENSIFIED PENSION TOGETHER WITH THE REMAINDER OF THE DRAINED SUSPENSION IS TRANSFERRED FROM THE DENSIFIER TO A PUMP BOX, AND THE SUSPENSION FEEDS FROM THE PUMP BOX TO A VESSEL WHERE THE MINERAL PARTICLES ARE INTRODUCED, THE COMBINATION THEREWITH OF A METHOD OF CONTROLLING THE SPECIFIC GRAVITY OF THE SUSPENSION IN THE VESSEL TO A SET VALUE COMPRISING MEASURING A SPECIFIC GRAVITY REPRESENTATIVE OF THE SUSPENSION IN THE VESSEL, SPLITTING THE FLOW OF SAID DENSIFIED SUSPENSION FROM THE DENSIFIER TO TRANSFER ONLY A VARIABLE FRACTION THEREOF TO THE PUMP BOX AND RETURN THE REMAINDER TO THE DENSIFIER, ADJUSTING THE MAGNITUDE OF THE FRACTION TRANSFERRED TO THE PUMP BOX IN RESPONSE TO THE SPECIFIC GRAVITY MEASUREMENT TO TRANSFER MORE AND RAISE THE LEVEL IN THE PUMP BOX WHEN THE SPECIFIC GRAVITY GOES DOWN FROM SAID SET VALUE AND TRANSFER LESS AND LOWER THE LEVEL IN THE PUMP BOX WHEN THE SPECIFIC GRAVITY GOES UP, MEASURING CHANGES IN THE LEVEL OF SUSPENSION IN THE PUMP BOX FROM A SET LEVEL, AND ADJUSTING THE MAGNITUDE OF SAID FRACTION OF DRAINED SUSPENSION TREATED IN THE MAGNETIC SEPARATOR AND DENSIFIER TO INCREASE THE FRACTION AS THE LEVEL RISES AND DECREASE THE FRACTION AS THE LEVEL FALLS AND THEREBY RESTORE THE LEVEL IN THE PUMP BOX TO SAID SET LEVEL.