| 英文摘要 |
Lead-acid battery are widely used in everywhere, such as for storage in backup power supplies, because they are very inexpensive compared to newer technologies. Lead-acid battery are made up of Lead, plastic case and 35% sulfuric acid electrolyte solution. Most of Lead and the plastic could be reused as a secondary raw material, but the electrolyte solution are not recycled in the present processes in Taiwan. Therefore, it is necessary to find a suitable recovery procedure for these electrolyte solution in the lead-acid battery recycling plants.
In last year, we investigated the characteristics of these waste electrolyte solution. According to the results, the sulfuric acid concentration of the waste electrolyte solution was 4.3 – 20.3 % and the higher metal ions were Fe and Pb. The Pb concentrations were 1,670 – 7,020μg/L and the Fe concentrations were 13,700 – 402,000μg/L. Because lead is the main composition in lead-acid battery, Pb concentrations were higher than others metal ions in the waste electrolyte solution. And the Fe ions was from the waste lead-acid battery dismantling process, the sulfuric acid could corrode the dismantling tools and these tools were made of steel. For recycling sulfuric acid from the waste electrolyte solution, the metal ions had to be separated from sulfuric acid.
According to the references, several processes were developed for recycling sulfuric acid in foreign waste lead-acid battery recycling plants. The diffusion film process and adsorption resin process were selected for recycling sulfuric acid from the waste electrolyte solution in this study. An experimental scale of the diffusion film process and adsorption resin process were used to evaluate the feasibility. The experimental results show that the recovery rate of the sulfuric acid from the waste electrolyte solution was more than 80%. The removal rate of the Pb ion and Fe ion were more than 80%, respectively. These two system have the same efficiency for recycling sulfuric acid, but the reactor volume of the adsorption resin process was only 20% of the diffusion film process. Therefore, the adsorption resin process was selected as the pilot plant in next stage.
The experiment results of the 200L scale pilot plant of the adsorption resin process show that the recovery rate of the sulfuric acid from the waste electrolyte solution was more than 80% and the average concentration of recovery concentration was lower about 2% than the concentration of the waste electrolyte solution. Therefore, the feasibility of this process had been validated in this study.
On the other hand, if the factor uses of adsorption resin process, the amount of NaOH for neutralization could be reduced to 66% and the amount of sludge for waste electrolyte solution treatment also could be reduce 40% than without it. This result shows the sulfuric acid recovery system could saves operating costs and reduce environmental impact.
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