China Nonferrous Metallurgy

Pre-desulfurization of lead paste is the key process of clean production technology in recycled lead industry. Due to high price of raw material sodium carbonate and low price of the product sodium sulfate, the economic benefit of the existing sodium carbonate desulfurization of lead paste is poor, hindering the development of the clean process. For the problems of mass transfer hindrance and volume expansion of the reaction system, a new ammonium bicarbonate desulfurization device with liquid-gas separation and surface shell breaking has been designed and investigated based on the “storage and reaction separation”. The flow field of the slurry storage tank and the structure of forced desulfurization components were optimized, and the influence of reaction conditions on desulfurization efficiency was investigated. The results showed that the slurry volume expansion rate of the new device with flexible particle and “storage and reaction separation” was significantly reduced, and the mass transfer rate was greatly increased by comparing with the traditional device；the sulfur content of lead paste was kept to be lower than 0.5% after the reaction for 60 min under the high concentration of lead paste slurry (40%~60%), which could well meet the demand of industrial application of ammonium desulfurization of lead paste. Ammonium bicarbonate (NH4HCO3) is expected as a new desulfurizer to greatly improve the economic benefit of lead paste desulfurization.