9. Pollution and the environment

The major drawback of molybdenite metallurgy is the release of SO ₂ during roasting. This disadvantage is reduced when the gases are treated for rhenium extraction. The optimum conditions for recovering this element correspond to the optimum conditions for oxidizing MoS ₂ . The use of oxygen-enriched air ensures total oxidation, as well as a reduction in gas volume.

Consequently, in terms of environmental protection, the sensitive points of this metallurgy are as follows.

• The residual amount of SO ₂ in the gases leaving the treatment: these gases are wet, and treatment with lime milk is the most appropriate (semi-wet or wet processes). An SO ₂ ...