During the waste automotive lead battery recycling process, lead paste is abundant of lead sulfate whose recovery rate highly influences the profit of battery recycling and the capability of market competition. This study aims to improve the existing battery recycling technology for recovering lead in the waste automotive batteries in the project of last year, and conducted factory verification to obtain the best operating condition. This study applied ammonium bicarbonate (NH4HCO3) as a new desulfurization reagent, which can be produced by absorbing carbon dioxide in the flue gas with ammonia solution. This innovative technology can not only produce ammonium bicarbonate, but also reduce the emission of greenhouse gases from the stacks. The advantages of this innovative technology include high purity and value of lead products, high recycling efficiency of waste automotive lead battery, low emission of air pollutants, less corrosion of pipelines, low energy consumption, and less odorous problems. The results were obtained from the factory verification experiments. In the process of desulfurization stirring, the desulfurization efficiency of lead paste was 80.3%. The purity of the refined lead reached 99.97% that was slightly higher than the traditional lead production process, indicating that the desulfurization of lead paste is beneficial to enhance the purify the recycled lead. As high as 10% of lead recovery ratio can be reached for the desulfurization process compared to that without desulfurization, with a profit of approximately 5,000 NT/ton due to the improvement of lead recovery rate. But 1,035 NT/ton was required for the addition of NH4HCO3 as the desulfurization agent. By comparing the cost-benefit of all items during the lead recovery process with and without desulfurization, the unit profit with the desulfurization process was 4,253 NT/ton higher than that without desulfurization. During the continuous monitoring of CO2 absorbed by the ammonium solution, the adsorption efficiencies of CO2 ranged from 70.3% to 90.8% with an average of 82.0%. Additionally, the air quality of the manufactory zone was improved ( the reduction of SO2 concentration from 50 ppb to 30 ppb; the reduction of TVOC concentration from 289 ppb to 65 ppb; the reduction of TSP concentration from 295 μg/m3 to 269 μg/m3; and the reduction of CO2 concentration from 606 ppm to 594 ppm), particularly for the level of SO2 that was emitted from the reverberatory furnace due to the desulfurization prior to the reduction process. By the addition of Ca(OH)2 to the (NH4)2SO4 filtrate after desulfurization, NH3·H2O was recovered with the mass ratio of 9.7%, however, the separation of CaSO4 from Ca(OH)2 was somehow difficult. Further works focused on recycling the mixture of ammonium sulfate and ammonium bicarbonate solution is essential to promote the technological feasibility of the desulfurization process.

Waste lead battery, lead paste desulfurization, ammonium bicarbonate, recycling and reuse, pollution reduction