My assignment question says:
Describe in a paragraph the process of purification to obtain the pure element from its natural source as a mineral or mixture. This process may involve mining, crushing and other processes for physical or chemical separation.
Please help! I can't find this anywhere!
Describe in a paragraph the process of purification to obtain the pure element from its natural source as a mineral or mixture. This process may involve mining, crushing and other processes for physical or chemical separation.
Please help! I can't find this anywhere!
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1) Mining and grinding
Ore containing sphalerite is mined, then grinded into a powder to increase surface area.
2) Froth flotation
The powdered ore is then mixed with a little bit of SEX (sodium ethyl xanthate), which binds with the sphalerite particles, and floats them to the top of a tank, where they form a froth. The collected froth contains fewer impurities than the ore started with, and is about 82% zinc sulfide (ZnS).
3) Roasting
The collected froth is then treated with very hot air. Zinc sulfide reacts with the oxygen in the air to form zinc oxide (ZnO). From this step on, there are two different refining processes, pyrometallurgy or electrowinning.
4A) Pyrometallurgy (more common in the past)
Sometimes, the zinc oxide is reduced with very hot carbon or carbon monoxide to form zinc vapor. This can be done in a retort, an electric arc furnace, or a blast furnace. The zinc vapor leaves the impurities behind and is collected in a condenser.
4B) Electrowinning (more common today)
Or, the zinc oxide is instead leached (dissolved) away from the impurities with sulfuric acid, to form a solution of zinc sulfate (ZnSO₄). The zinc sulfate solution undergoes electroplating, which reduces the zinc ions to form zinc metal, deposited on the cathode.
Ore containing sphalerite is mined, then grinded into a powder to increase surface area.
2) Froth flotation
The powdered ore is then mixed with a little bit of SEX (sodium ethyl xanthate), which binds with the sphalerite particles, and floats them to the top of a tank, where they form a froth. The collected froth contains fewer impurities than the ore started with, and is about 82% zinc sulfide (ZnS).
3) Roasting
The collected froth is then treated with very hot air. Zinc sulfide reacts with the oxygen in the air to form zinc oxide (ZnO). From this step on, there are two different refining processes, pyrometallurgy or electrowinning.
4A) Pyrometallurgy (more common in the past)
Sometimes, the zinc oxide is reduced with very hot carbon or carbon monoxide to form zinc vapor. This can be done in a retort, an electric arc furnace, or a blast furnace. The zinc vapor leaves the impurities behind and is collected in a condenser.
4B) Electrowinning (more common today)
Or, the zinc oxide is instead leached (dissolved) away from the impurities with sulfuric acid, to form a solution of zinc sulfate (ZnSO₄). The zinc sulfate solution undergoes electroplating, which reduces the zinc ions to form zinc metal, deposited on the cathode.