Lead Refining by Wet Process
Lead refining by wet process is the process of refining raw lead by immersing it in acid solutions of 28–38% sulfuric acid. During the process, lead is transformed from the raw material into usable and marketable forms, such as unwrought lead, lead alloys, and granules.
This process is used in many facets of lead manufacturing and can be conducted at temperatures of 800–900°C (1,472–1,652°F). The process is typically broken down into five distinct stages, each designed to produce a specific product with a grade suitable for a particular purpose:
The first stage is oxidation. During this stage, raw lead is heated to the reaction temperature and then exposed to air or oxygen. This triggers an oxidation reaction that removes the impurities in the lead.
The second stage is reduction. The lead is again heated to the reaction temperature, but this time exposed to iron or sulphur which reduces the oxidation and removes more of the impurities.
The third stage is chloride treatment. In this stage, the lead is treated with chlorine gas or metal chlorides (such as sodium or potassium chloride), which further purifies the lead by removing heavy metals and other impurities.
The fourth stage is desilicization. This is the process of removing silica from the lead. The lead is treated with hydrogen fluoride which breaks down the silica and purifies the lead more.
The fifth and final stage is precipitation. This process further purifies the lead by removing any remaining impurities, such as sulfur and carbon. The lead is then cooled and solidified into the desired form.
Lead refining by wet process is an extensive and complex process and having a concise understanding of the entire process is key to producing the desired form of lead with the appropriate grade. In order to achieve the highest quality product and minimize waste, it is important to have a thorough understanding of lead refining by wet process and its constituent stages. This knowledge can help operators maximize lead purity and product quality.
