Froth Flotation (Sulphide & Oxide)

Froth Flotation (Sulphide & Oxide)

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Why does the pH drop after collecting concentrates during the flotation of Nickel sulfide ore with P ... (1 reply)

12 months ago
khans318 12 months ago

I want to perform Ni sulfide flotation in a 1 L laboratory cell. But after adding the reagents, starting the reaction and collecting the concentrate the pH of the pulp decreases. So we have to add soda ash further to adjust the pH again to 10.1 which is the industry norm in Canada. But why does the pH decreases after collecting the concentrate?



12 months ago
Jorge 12 months ago

A similar situation is typical of copper, lead and zinc flotation. The pH decreases after removing the rougher or cleaner concentrate. The reason is the presence of sulphides and the galvanic interactions. During grinding, an intimate contact is established between minerals and grinding media and among the minerals themselves. When complex-sulfide ores are involved, bi- and multi-electrode galvanic cells develop as a consequence of these contacts. When there are more sulphides, the addition of soda ash or lime will be higher. These mineral-metal interactions became particularly significant in the case of pyrrhotite

Also, the reactins can promote the formation of elemental sulfur, which promotes natural floatability causing difficulties in selective flotation, while the formation of a coating by the precipitation of insoluble metal hydroxides on sulfide minerals may interfere with the collector adsorption, thus impairing the flotation recovery.

Other thing is to mention is the pH of the concentrate. Try to check it. Part of the alkalinity is loss with the concentrate.

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