How to handle lead dust containing 35% arsenic?
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RT, how should lead oxide dust containing about 35% arsenic be treated? Pyroprocessing or hydrometallurgy? What is the general process?
Both pyrometallurgical and hydrometallurgical methods involve the issue of arsenic release into the environment; in pyrometallurgical processing, arsenic is dispersed in secondary dust, arsenic-containing matte, and crude lead, all of which constitute new hazardous waste； In the wet method, arsenic cannot be leached at 100%; the arsenic in the leachate needs to be solidified, and as for the arsenic in the leaching residue, it depends on whether wet or thermal methods will be used subsequently. If environmental concerns are ignored, this kind of ash can be processed in many small factories; but to truly meet environmental standards, a disposal method that finds a way to deal with arsenic is the only one that holds promise.
Environmental regulations are too strict these days; regarding arsenic, tests are required for both flue gas and industrial wastewater, as well as for the treatment of lead containing arsenic – it’s really a troublesome situation.
It is sold secretly; generally, it involves ordinary ingredients. By taking advantage of the differences in the amount of arsenic trioxide present in the flue gas at different temperatures, a bag filter is used to capture the arsenic, which is then packaged and sold.
The wet method is easier to handle; arsenic is oxidized and leached in a sulfuric acid system. By controlling the conditions properly, all of the arsenic can be leached out. The residue can be sold as lead sludge, while the liquid is treated with sulfur dioxide to reduce and precipitate arsenic trioxide – the concentration should be over 95% for it to be sellable, though the price will be low. The liquid is then reused in the leaching process with additional acid added. The process itself shouldn’t present any problems; it’s just that the equipment investment is high, and arsenic trioxide isn’t very valuable anyway! Oxygen pressure equipment requires an investment of at least tens of millions
It’s as if lead doesn’t evaporate!
The volatilization temperature varies; it is generally used in lead blast furnaces for mixing materials, with flue gas temperatures of 350°C, followed by rapid cooling to 100°C. Refer to \"Application Practices of Dry Process for Arsenic Recovery\"
Arsenic is a problem; even large companies like the Polish copper industry are troubled by it
Dealing with arsenic is indeed a difficult problem; without the proper qualifications, one cannot handle it oneself, nor can one sell it. If you handle it yourself, whether by wet or thermal methods, the solidified arsenic ultimately needs to be vitrified and sintered in an alkaline environment; otherwise, if there is indium present as well, it’s better to sell it to us so that we can handle it