Recovery of high purity lead oxide from lead acid battery paste
View Patent ↗The invention relates to the low temperature recovery of lead oxide (PbO) from lead acid battery paste through the preparation of lead carboxylate from the battery paste and the conversion of the lead carboxylate to PbO.
1. A low temperature process for recovering high purity lead oxide (PbO) from a lead acid battery paste which comprises the steps of:
A) reacting lead acid battery paste with an alkali hydroxide to remove any sulfates and to form Pb 3 O 4 ;
B) reacting the Pb 3 O 4 with a carboxylic acid having 1 to 3 carbon atoms and a reducing agent to form lead carboxylate; and
C) reacting the lead carboxylate under an inert atmosphere at an elevated temperature with concentrated alkali hydroxide to form PbO.
2. The process of claim 1 wherein the alkali hydroxide used in step A) is selected from the group consisting of sodium hydroxide and potassium hydroxide.
3. The process of claim 1 wherein the carboxylic acid is acetic acid and the lead carboxylate is lead acetate.
4. The process of claim 1 wherein the carboxylic is formic acid and the lead carboxylate is lead formate.
5. The process of claim 1 wherein the reducing agent is selected from the group consisting of sorbitol, soluble cellulosic material, starch and glyoxal.
6. The process of claim 1 wherein reacting the lead carboxylate under an inert atmosphere at an elevated temperature with concentrated alkali hydroxide to form PbO is carried out at a pH of about 12.
7. A process for recovery of high purity lead oxide (PbO) from lead acid battery paste which comprises the steps of:
a) reacting lead acid battery paste with sodium hydroxide at a temperature of about 60-70° C. at a pH greater than 10 to form a first slurry;
b) filtering the first slurry to form a filter cake;
c) reacting the filter cake with acetic acid to form a first solution;
d) treating the first solution with glyoxal to form a second slurry;
e) filtering the second slurry to obtain a filtrate containing lead acetate; and then
f) treating the filtrate with sodium hydroxide under a nitrogen atmosphere at a pH of about 12 to form a third slurry, and then
g) filtering the third slurry to recover litharge PbO.
8. The process of claim 7 wherein the pH in step a) is at least 13.
9. The process of claim 7 wherein the second slurry of step d) is heated to about 40-60° C. during forming.
10. The process of claim 7 wherein the temperature in step f) is maintained below 105° C.