Froth handling pump

Abstract

A froth handling pump includes a pump casing, an impeller mounted within the casing, and a de-aeration chamber mounted to the rear side of the pump casing. The impeller comprises multiple pumping vanes, each of the vanes having an inlet angle and an outlet angle, wherein the outlet angle is greater than the inlet angle, the outlet angles terminating at a rear shroud. The rear shroud includes multiple vent holes for the passage of gases therethrough. The de-aeration chamber, which comprises an inner volume, includes an inlet formed on the inner side for receiving gases passing through the plurality of vent holes. At least one vent outlet is provided for the discharge of gases from the de-aeration chamber.

1 . A froth handling pump, comprising
 (a) a pump casing having an inlet side and a rear side;   (b) an impeller mounted within the casing, the impeller comprising:
 (i) a rear shroud, comprising:
 (A) an inner face and an outer face; 
 (B) a plurality of vent holes formed through the rear shroud for the passage of gases therethrough; 
 
 (ii) a plurality of pumping vanes, each of the pumping vanes comprising:
 (A) inlet ends affixed to the inner face of the rear shroud and extending radially inwardly from the rear shroud; 
 (B) an inlet angle and an outlet angle, wherein the outlet is angle is greater than the inlet angle, the outlet angles terminating at the rear shroud; 
 
   (c) a de-aeration chamber mounted to the rear side of the pump casing and comprising:
 (i) an inner volume; 
 (ii) an inner side mounted to the rear side of the pump casing; 
 (iii) an inlet formed on the inner side for receiving gases passing through the plurality of vent holes; and 
 (iv) at least one vent outlet for the discharge of gases therethrough. 
   
   
   
       2 . The pump of  claim 1 , wherein the plurality of pumping vanes extending radially inwardly from the rear shroud terminate at free ends. 
   
   
       3 . The pump of  claim 2 , wherein the space between the free ends of the pumping vanes and the inlet side of the pump casing being free of a front shroud; 
   
   
       4 . The pump of  claim 1 , wherein the outlet angles of the pumping vanes are between about 80 degrees and about 100 degrees. 
   
   
       5 . The pump of  claim 4 , wherein the outlet angles of the pumping vanes are about 90 degrees. 
   
   
       6 . The pump of  claim 1 , wherein the pumping vanes comprise full size main pumping vanes, and splitter vanes of a lesser radial dimension. 
   
   
       7 . The pump of  claim 6 , wherein the impeller comprises 12 pumping vanes comprising:
 (a) 6 main pumping vanes;   (b) 6 splitter vanes; and   
     wherein the pumping vanes and splitter vanes are arranged in an alternating configuration, having passages therebetween. 
   
   
       8 . The pump of  claim 1 , wherein the passage size between adjacent pumping vanes is at least about 2 inches. 
   
   
       9 . The pump of  claim 1 , further comprising a plurality of clearing vanes formed on the outer face of the rear shroud. 
   
   
       10 . The pump of  claim 9 , wherein the plurality of clearing vanes are configured to create a pressure on the outer face of the rear shroud less than the pressure created by the pumping vanes. 
   
   
       11 . The pump of  claim 10 , wherein the clearing vanes project outwardly from the outer face of the rear shroud at about a 90 degree angle. 
   
   
       12 . The pump of  claim 11 , wherein the rear shroud has a central hub and wherein the clearing vanes have differing lengths extending radially outwardly relative to the central hub. 
   
   
       13 . The pump of  claim 9 , wherein the clearing vanes are at least about 5 percent larger in diameter than the pumping vanes. 
   
   
       14 . The pump of  claim 1 , wherein the vent holes in the rear shroud each have a minimum area of at least about 3.14 square inches. 
   
   
       15 . The pump of  claim 1 , wherein the at least one vent outlet on the de-aeration chamber is positioned at an angle of less than about 45 degrees with respect to the vertical. 
   
   
       16 . The pump of  claim 15 , wherein the at least one vent outlet is positioned at an angle of about 22.5 degrees with respect to the vertical. 
   
   
       17 . The pump of  claim 1 , wherein the at least one vent outlet has an outlet diameter of at least about 3 inches. 
   
   
       18 . The pump of  claim 1 , where the de-aeration chamber further comprises a drain outlet. 
   
   
       19 . The pump of  claim 1 , further comprising an auxiliary impeller mounted to the outer face of the rear shroud. 
   
   
       20 . The pump of  claim 19 , wherein the auxiliary impeller has an outer radius that is greater than the maximum radial position of the plurality of vent holes. 
   
   
       21 . The pump of  claim 1 , wherein the impeller comprises a front shroud.