Abstract:A novel process was developed for the selective leaching of non-sulfur-containing lead components from spent lead paste, utilizing a methanesulfonic acid-hydrogen peroxide leaching solution. The effects of stirring speed, leaching temperature, leaching time, hydrogen peroxide addition, liquid-to-solid ratio, and particle size on leaching of non-sulfur lead components in spent lead paste were studied. The optimal leaching conditions under the methanesulfonic acid-hydrogen peroxide solution were identified. Additionally, the form of silicon impurities present in the spent lead paste and the morphology and chemical composition of the leaching residue were explored. A process flow for the selective leaching of non-sulfur lead components from spent lead paste was proposed. The results indicate that employing a pre-adjusted slurrying process can enhance the leaching of lead and some lead dioxide from the spent lead paste through neutralization reactions, thereby reducing the amount of reducing agent hydrogen peroxide. The stirring speed, leaching temperature, and particle size of the spent lead paste have a relatively minor effect on the leaching process, while the addition of the reducing agent significantly influenced the leaching of lead dioxide. Under conditions of stirring speed of 400 r/min, leaching temperature of 25 ℃, liquid-to-solid ratio of 5 mL/g, and methanesulfonic acid concentration of 2.23 mol/L, the leaching rate of non-sulfur lead components from the spent lead paste can reach 99% within 90 minutes. The silicon impurities within the spent lead paste predominantly existes in a short-fiber form, while some lead-bearing substances is attached to the surfaces of the silicon impurities in the form of particles approximately 1 μm in size. The leaching residue mainly consists of lead sulfate and silicon fibers.