Patent Number: 6,168,721

Title: Process for the treatment of arsenic-containing sludge

Abstract: The present invention relates to a process for the treatment of arsenic-containing sludge obtained by adjusting arsenic-containing waste water to a PH of 12 or greater by the addition of a calcium compound and subjecting the waste water to solid-liquid separation, the process comprising the steps of adding a calcium compound to the arsenic-containing sludge slurry obtained by the solid-liquid separation, dewatering the resulting sludge, drying the dewatered sludge, and calcining the dried sludge. According to the present invention, arsenic-containing sludge obtained by treating waste water to precipitate arsenic present therein can be calcined to yield a calcined product which involves no risk of arsenic redissolution when it is dumped. Moreover, there is no possibility that arsenic compounds may be volatilized during calcination.

Inventors: Sugita; Satoru (Tokyo, JP), Shimizu; Taku (Tokyo, JP), Iwashita; Koichiro (Tokyo, JP), Baba; Hiroshi (Kobe, JP), Kamiyoshi; Hideki (Kobe, JP), Nishida; Morikata (Kobe, JP)

Assignee: Mitsubishi Heavy Industries, Ltd.

International Classification: C02F 9/00 (20060101); C02F 1/52 (20060101); C02F 11/06 (20060101); C02F 11/14 (20060101); C02F 1/66 (20060101); C02F 001/62 ()

Expiration Date: 01/02/2018