To provide a fine powder treatment method capable of keeping the addition amount of a sulfurizing agent for producing lead sulfide constantly at the optimum value and recovering Pb constantly at a high recovery ratio without measuring the content of Pb in a fine powder containing Ca and Pb.

The method involves steps of (A) obtaining a slurry containing lead sulfide by mixing a fine powder, water, and a sulfurizing agent; (B) obtaining a slurry containing the lead sulfide and calcium sulfate by adding sulfuric acid to the slurry and adjusting pH to be 1.5 to 7.5; (C) measuring the redox potential of the slurry obtained in the step (A) and detecting the existence or the concentration of hydrogen sulfide gas generated in the step (B) and adjusting the addition amount of the sulfurizing agent in the step (A) based on those results; (D) making the lead sulfide in the slurry hydrophobic by adding a trapping agent to the slurry obtained in the step (B); and (E) obtaining floating ore containing the lead sulfide and precipitating ore containing the calcium sulfate by carrying out flotation separation treatment of the slurry obtained in the step (D).

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