Process and apparatus for separating mixtures of solids in a liquid medium

Claim 1

A CONTINUOUS METHOD FOR SEPARATING IN A LIQUID MEDIUM A MIXTURE OF SOLIDS HAVING DIFFERENT SETTLING RATES IN THAT LIQUID INTO AT LEAST AN UNDERFLOW COMPRISING SOLIDS OF HIGHER SETTLING RATES AND AN OVERFLOW COMPRISING SOLIDS OF LOWER SETTLING RATES WHICH COMPRISES ESTABLISHING AND MAINTAINING A VERTICALLY RADIALLY SYMMETRICAL, FREE WHIRLING, BODY OF THE LIQUID, THAT HAS A VERTICAL AXIS OF REVOLUTION AND AT LEAST AT THE BOTTOM PORTION THEREOF HAVING A GRADUALLY DECREASING RADIUS OF REVOLUTION; CONTINUOUSLY INTRODUCING TOGETHER THE LIQUID AND THE MIXTURE OF SOLIDS TANGENTIALLY TO THE RADIALLY SYMMETRICAL PERIPHERY INTO THE BODY NEAR THE TOP SURFACE THEREOF AT A PRESSURE SUFFICIENT TO WHIRL THE BODY AS A FREE VORTEX TO THEREBY CREATE CENTRIFUGAL FORCES FOR SETTLING SOLIDS OF HIGHER SETTLING RATES, AND AT RATES OF FLOW SUFFICIENT TO ALWAYS MAINTAIN THE TOP SURFACE OF THE BODY ABOVE THE POINT OF INTRODUCTION: WITHDRAWING LIQUID AS VORTEX OVERFLOW FROM A REGION BELOW THE TOP SURFACE OF THE BODY ABOUT THE AXIS OF REVOLUTION SUBSTANTIALLY OPPOSITE THE POINT OF INTRODUCTION AT A RATE LOWER THAN THE RATE OF INTRODUCTION BUT SUFFICIENT TO CREATE LIQUID DRAG FORCES TO OPPOSE SETTLING FORCES IN THE BODY WHEREBY SOLIDS OF LOWER SETTLING RATES ARE SEGREGATED AND WITHDRAWN IN THE VORTEX OVERFLOW SETTLING BY CENTRIFUGAL FORCES AND THE FORCE OF GRAVITY THE SOLIDS OF HIGHER SETTLING RATES. WITHDRAWING AS UNDERFLOW LIQUID AND THE SETTLED SOLIDS OF HIGHER SETTLING RATES FROM THE BOTTOM OF THE BODY AT THE POINT OF MINIMUM RADIUS AT A RATE LESS THAN THE SAID RATE OF INTRODUCTION BUT GREATER THAN THE RATE OF WITHDRAWAL AT WHICH SOLIDS OF HIGHER SETTLING RATES ACCUMULATE FASTER AT THE POINT OF WITHDRAWAL THAN THEY ARE REMOVED; AND, DURING NORMAL OPERATIVE FLUCTUATIONS IN THE RATE OF INTRODUCTION, MAINTAINING SUBSTANTIALLY THE SAME POINT OF SEPARATION AND THE SHARPNESS OF SEPARATION OVER THE RANGE OF UNDERFLOW WITHDRAWAL RATES FROM THE MAXIMUM RATE TO THE RATE AT WHICH THE UNDERFLOW BECOMES OVERLOADED AND OVER THE RANGE OF UNDERFLOW WITHDRAWAL RATES FROM THAT AT WHICH THE UNDERFLOW BECOMES OVERLOADED TO THAT AT WHICH THE SOLIDS OF HIGHER SETTLING RATES ACCUMULATE FASTER THAN THEY ARE WITHDRAWN, BY VARYING THE AVERAGE LEVEL OF AT LEAST A PORTION OF THE TOP SURFACE OF THE BODY, WHICH IS UNOBSTRUCTEDLY IN CONTACT WITH THE ATMOSPHERE, IN DIRECT PROPORTION TO THE SAID FLUCTUATIONS.