Granted Patent B2

US 8,419,897 · App. 13/302,471 · Granted Apr 16, 2013

Abstract

Claims (21)

1. A method for producing crude tall oil from black liquor soap while removing calcium and lignates, comprising:

(a) combining a black liquor soap comprising tall oil soap, lignates. and inorganic solids comprising calcium carbonate, with an alkaline wash medium, wherein the alkaline wash medium has a pH from 10 to 14 and a lower concentration of lignates and inorganic solids than the black liquor soap, at a temperature within the range of 25° C. to 100° C. to produce a mixture comprising washed tall oil soap, fortified brine, lignates, and calcium carbonate; wherein the alkaline wash medium has a lignate content <1.0 wt. % and a filterable inorganic solids content <200 ppm:

(b) separating the mixture by centrifugation, decantation, filtration, settling, or a combination of these techniques to provide, in addition to the washed tall oil soap:

(i) a solid phase comprising calcium carbonate, and a liquid phase comprising fortified brine; or

(ii) an unclarified, fortified brine phase;

(c) acidifying the washed tall oil soap isolated in step (b) to give crude tall oil and a spent acid mixture; and

(d) isolating the crude tall oil.

2. The method of claim 1 further comprising

(e) adjusting the pH of the spent acid mixture to be within the range of pH =10 to 14 and returning at least a portion of it to step (a) as alkaline wash medium.

3. The method of claim 1 further comprising transferring the fortified brine to a weak black liquor storage unit.

4. The method of claim 1 further comprising washing the solid phase with water to give calcium carbonate and an aqueous lignate phase.

5. The method of claim 4 further comprising converting the calcium carbonate to lime for use in a Kraft process.

6. The method of claim 4 further comprising recovering lignates from the aqueous lignate phase for use as a biofuel component.

7. The method of claim 1 wherein the unclarified, fortified brine phase is sent to a transfer point in a Kraft plant that is downstream from a multi-effect evaporator system and upstream from a recovery boiler in the plant's liquor system.

8. The method of claim 7 wherein the transfer point is upstream from or directly into either a liquor concentrator or a direct contact evaporator and is upstream from the recovery boiler.

9. The method of claim 1 wherein the unclarified, fortified brine phase is clarified by centrifugation, decantation, filtration, settling, or a combination of these techniques to remove calcium carbonate and recover a clarified, fortified brine.

10. The method of claim 9 wherein the clarified, fortified brine is sent to a transfer point in a Kraft plant that is downstream from a multi-effect evaporator system and upstream from a recovery boiler in the plant's liquor system.

11. The method of claim 1 wherein the amount of alkaline wash medium is within the range of 1 to 60 wt. % based on the combined amounts of black liquor soap and alkaline wash medium.

12. The method of claim 1 wherein the alkaline wash medium has a lignate content within the range of 0.01 to 0.9 wt. % and a filterable inorganic solids content within the range of 10 to 175 ppm.

13. The method of claim 1 wherein step (a) is performed at a temperature within the range of 55° C. to 95° C.

14. The method of claim 1 wherein the alkaline wash medium has a pH within the range of 10.0 to 11.5.

Assignments (16)