The Refining Process of Lead

After lead has gone through the molten process it comes from the blast furnace around ninety five to ninety nine percent in purity. This is better known as base bullion. However, in order for it to be commercial lead it is required to be refined further in order to get rid of the impurities. Base bullion is refined by maintaining it in the kettle at a temperature that is just above its melting point. When it is at this temperature, if there is any copper left in it, it will cause it to go up to the top of the kettle and will form a foam that is then skimmed off. Silver and gold can also be removed from the bullion by putting a little bit of zinc in it. After the refining process of the lead has been concluded, it is then cooled and cast into big size blocks; some can weigh up to one ton once the process is completed. 

Byproducts and waste of lead
There are several byproducts that come about from the refining of lead. The waste rock, which is more commonly known as gangue, builds up as the ore becomes concentrated. Almost all of the minerals have been taken from the rock; therefore this waste is no looked on by the industry as something that is hazardous to the environment. This waste can be disposed of in a pond, which resembles a natural lake by using a pump. Sulfuric acid is the leading byproduct of the process of smelting, however, sulphur dioxide becomes free when the ore is being roasted at a sinter plant, therefore, in order to safeguard the environment, the smoke and the fumes are captured and the air that is let out by the plant has been previously cleaned from impurities and contamination. Then the sulphur dioxide is collected at a different acid plant and there it is turned into a sulphuric acid which can then be sold along with the main product being lead in this case. One other problem that can come about from the processing of lead is air pollution as well and because of this the smelter needs to have a separate area to be able to vacuum and filter the fumes in order to prevent the lead from being let out into the atmosphere, it is nonetheless almost impossible to avoid the lead particles from going out into the atmosphere and there are certain laws and regulations in different countries as to how much is let out into the atmosphere. Almost all of the solid waste product that is produced due to the smelting process is a glassy looking and dense substance that is known as slag which also has teensy amounts of zinc and copper in it. The slag is more toxic than the gangue though and it needs to be stored in a very safe way and kept an eye on so that it does not escape out into the environment.