 Bismuth travels in crude lead bullion ( which can contain up to 10 % bismuth ) through several stages of refining , until it is removed by the Kroll @-@ Betterton process which separates the impurities as slag , or the electrolytic Betts process . Bismuth will behave similarly with another of its major metals , copper . The raw bismuth metal from both processes contains still considerable amounts of other metals , foremost lead . By reacting the molten mixture with chlorine gas the metals are converted to their chlorides while bismuth remains unchanged . Impurities can also be removed by various other methods for example with fluxes and treatments yielding high @-@ purity bismuth metal ( over 99 % Bi ) . World bismuth production from refineries is a more complete and reliable statistic . 
