Patent Number: 
Section: claims

1. A loop dissolution system comprising:an upper material feed dissolution plate into which a material to be dissolved is fed;a lower mixing and dissolution ring;a drop pipe system connecting and establishing fluid communication between the upper material feed dissolution plate and the lower mixing and dissolution ring; anda pump having an intake from the lower mixing and dissolution ring and an outlet that directs a first portion of a fluid employed to dissolve the material, to the upper material feed dissolution plate and a second portion of the fluid back into the lower mixing and dissolution ring to circulate the material suspended in the fluid within the lower mixing and dissolution ring to promote turbulence to facilitate dissolution. 2. The loop dissolution system of claim 1 wherein the second portion of the fluid is directed back into the lower mixing and dissolution ring through an acceleration jet. 3. The loop dissolution system of claim 2 wherein the second portion of the fluid is directed back into the lower mixing and dissolution ring through a plurality of spaced inlets around the mixing and dissolution ring. 4. The loop dissolution system of claim 1 wherein the pump has a first inlet from an underside of the lower mixing and dissolution ring and a second inlet from an upper side of the lower mixing and dissolution ring with each of the first and second inlets respectively having a cutoff valve so the pump can draw the fluid alternately from the first inlet or the second inlet. 5. The loop dissolution system of claim 4 wherein the first inlet has a vortex separation chamber in series with the pump. 6. The loop dissolution system of claim 1 wherein the drop pipe system comprises a plurality of pipes respectively spaced around the upper material feed dissolution plate and respectively connected to spaced inlets around the lower mixing and dissolution ring. 7. The loop dissolution system of claim 1 wherein the first portion of the fluid is directed to the upper material feed dissolution plate through a valved manifold compatible with different fluid distribution arrangements. 8. The loop dissolution system of claim 1 including an active level trip system for determining the level of fluid in the upper material feed dissolution plate and shutting off the first portion of the fluid from entering the upper material feed dissolution plate if the level exceeds a preselected value. 9. The loop dissolution system of claim 8 wherein shutting off the first portion of fluid from entering the upper material feed dissolution plate lets the fluid in the upper material feed dissolution plate drain into the drop pipe system. 10. The loop dissolution system of claim 1 wherein the upper material feed dissolution plate is enclosed within a fume extraction chamber with an air inlet and vacuum extraction outlet. 11. The loop dissolution system of claim 10 including a flow meter in the air inlet that is responsive to a preselected decrease in flow to cease dissolution operations. 12. The loop dissolution system of claim 1 wherein the drop pipe system includes a compressed air inlet to aid mixing and the transfer of solids into the lower mixing and dissolution ring. 13. The loop dissolution system of claim 12 wherein the compressed air inlet is adjacent a juncture of the drop pipe system and the lower mixing and dissolution ring. 14. The loop dissolution system of claim 1 including a temperature controller for maintaining the temperature of the fluid within a selected range before the fluid is fed to the material feed dissolution plate.