Method of reducing lead and acid waste contamination in battery plant operation
AssigneeGlobe-Union Inc.
InventorWilliam Arthur Blann
Life of this patent
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Abstract
A method of reducing the sulfate ion and sulfuric acid contamination of waste water in lead-acid battery manufacturing operations and recovery of the lead in salvageable form is provided which comprises neutralizing aqueous sulfuric acid wastes by treatment with waste battery paste containing lead oxide under controlled pH conditions.
Claims9
A process for treatment of aqueous sulfuric acid waste water in a lead-acid battery manufacturing plant to neutralize the sulfuric acid and reduce the sulfate ion content thereof to produce a waste sewage water effluent with a pH between about 5.5 and 8.5 and which has a sulfate ion content less than about 600 ppm., which consists essentially of:
- a. forming a reaction mixture slurry by combining a waste water stream of sulfuric acid waste with a stream of an aqueous slurry of waste battery paste containing lead oxide through a turbulent in-flow reactor and mixing zone providing turbulent flow mixing conditions, said waste battery paste being essentially the sole neutralizing agent for the sulfuric acid present, to form a slurry reaction mixture;
- b. concomitantly adjusting the proportion of waste battery paste added to said slurry to neutralize the sulfuric acid component and concomitantly adjust the pH of the reaction slurry to between about 5.5 and 8.5, forming essentially an insoluble solid sulfate precipitate predominately of lead sulfate which displays minimal solubility within said pH range;
- c. passing the effluent from said reactor zone to a further zoned reactor and separator which comprises a primary and secondary agitated reaction zone;
- d. passing the effluent slurry from the primary and secondary agitated reaction zone to a settling and precipitation zone wherein lead sulfate and other solids are separated from the aqueous portion of the slurry by gravity;
- e. recovering the neutralized aqueous liquid component of the slurry as an effluent having a pH of from 5.5 to 8.5 from the solid lead sulfate precipitate and other solid materials;
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- f. recovering the lead sulfate solids for conversion to lead and lead oxide and recycle and reuse as battery paste in the manufacture of batteries.
In a lead-acid battery manufacturing operation producing waste streams of water contaminated with sulfuric acid and waste battery paste containing lead oxide, lead sulfate and lead, the process for reducing the environmental contaminating effect of aqueous sulfuric acid, soluble sulfate ion and lead solubles in effluent waste water from said process and solid wastes from said process containing lead values which consists essentially of the steps of:
- a. contacting a waste water stream containing sulfuric acid from a lead-acid battery manufacturing operation with an aqueous stream of waste battery paste in pumpable slurry form having a solids content of at least 20% and containing lead oxide as a principal component, in a confined stream and under turbulent flow mixing and reacting conditions to produce a slurry reaction mixture;
- b. concomitantly adjusting the proportion of said lead oxide containing battery paste waste to substantially neutralize the sulfuric acid to produce a water component in the reaction slurry having a pH between about 5.5 and 8.5 and concomitantly form a precipitate of lead sulfate whereby the solubility of the lead sulfate precipitate formed is at a minimum and substantially all of the lead and sulfate ion components of the reaction slurry are in an insoluble lead sulfate form;
- c. passing the effluent reaction slurry from the turbulent flow reaction zone to an agitated primary and secondary reaction and settling zone;
- d. passing the effluent slurry from the secondary reaction zone to a settling and precipitating zone and gravitationally separating under non-turbulent conditions and recovering the precipitated lead sulfate solids from the neutralized water component of the waste stream slurry when precipitation is complete, for conversion of the lead sulfate to lead and lead oxide and recycle and reuse as battery paste in the manufacture of batteries;
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- e. recovering a neutralized water component from the separating zone as a stream having a pH of between about 5.5 and 8.5 and a sulfate ion content of less than about 600 ppm.
Dependencies are inferred from the claim text.