Kosaka Smelting and Refining Co., Ltd. is a copper and lead smelter in Japan. In 2008, the flash smelting furnace was replaced by the TSL furnace, and raw materials changed from ores to E-scraps. This change increased the amount of antimony sent to lead smelting division. Thus, it was necessary to improve lead smelting process and start up a new antimony recovery process to treat higher quantity of this element. The lead refining process was improved to solve anode hardening and increase caused by antimony. As a result, the limit of antimony concentration in anodes was raised from 2.0% to 4.2%. In the antimony recovery process, this element is leached by fluorine. Some fluorine is lost as wastewater and supplied by hydrofluoric acid. To improve the cost of hydrofluoric acid, we installed fluorine recovery process utilizing diatom earth. In this report, we introduce the antimony recovery process at the Kosaka smelting.