Sumitomo Metal Mining Company, Ltd.

Sho Shirai

Osamu Nakai

Takashi Sakamoto

Hideaki Sato

Hiroyuki Mitsui

Keisuke Shibayama

Masayuki Oku

The present invention provides a chromium-containing water treatment method that allows treatment of water that contains chromium (chromium-containing water) at low cost. A chromium-containing water treatment method according to the present invention comprises: a reduction step in which chromium-containing waterand a liquidcontaining 5-50 ppm of hydrogen sulfide are mixed, and the mixture is adjusted to pH 3.5 or lower and ORP 200-400 mV by adding an acidthereto, so as to reduce chromium contained in the water; and a precipitation separation step in which a neutralizing agent is added to a solutionobtained via the reduction step so as to adjust the solutionto pH 8-9, thereby precipitating and separating, as a hydroxide, the reduced chromium contained in the solution.

Chromium-containing water treatment method

Provided are a sulfuric acid adding facility and an operation method therefor which enable an increase in the maximum capacity and the operation rate of a sulfuric acid supply pump provided in the sulfuric acid adding facility. In a sulfuric acid adding facility, sulfuric acid is added to an autoclave used in a leaching step of a high pressure acid leaching method for a nickel oxide ore. The sulfuric acid adding facility is provided with the same number (n+1) (n is an integer, at least 1) of each of the following: a plurality of sulfuric acid adding pipes for adding sulfuric acid into the autoclave; and a plurality of sulfuric acid supply pumps for supplying sulfuric acid to the sulfuric acid adding pipes. Each of the first through n+1th sulfuric acid supply pumps includes at least three diaphragms and discharge ports of the same number as that of the diaphragms.

Sulfuric acid adding facility and operation method therefor

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Tokyo, Japan

Sho Shirai