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FeCl₃ leache-iron substitution method ^[1]

The method can be divided into three main steps: ferric chloride, hydrochloric acid leaching, iron powder replacement and sponge bismuth smelting

Fig.1 figure for the process flow of FeCl₃ leache-iron substitution method

Bismuth sulfide was leached with a mixture of ferric chloride and hydrochloric acid. Bi2S3 in the ore was dissolved by FeCl3 to form soluble bismuth trichloride:

At the same time, a small amount of natural bismuth mixed in the ore is dissolved:

The bismuth oxide in the ore was dissolved by hydrochloric acid:

Iron powder replacement

The bismuth in the ore is all transferred into the solution after leaching, and the sponge bismuth can be replaced by adding iron powder:

Bismuth sponge refining

Substitution of sponge bismuth need to be melting to cast into bismuth ingot, but direct melt will cause the happen of severe oxidation reaction. so the melting process in the industry is in the molten sodium hydroxide (melting temperature 318.4 ℃, density 2.13 g/cm3), which not only prevents the oxidation of bismuth, but also facilitates the aggregation of the molten bismuth (melting point 271 0C, isothermal liquid density 10.064g/cm3). In addition the bismuth oxides and certain impurities are asorbed by NaOH.

Advantages of this method

High extraction rate of bismuth (94% ~ 94.5%)
Less environmental pollution

Disadvantages of this method

High material consumption: Bismuth sponge consumes 1.5 ~ 1.8t hydrochloric acid, 0.4 ~ 0.5t chlorine gas and 0.5 ~ 0.6t iron powder per ton.
The filtration and washing of slag are difficult

Relevant Links

Relevant Links

Processing of Bismuth

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