Title:
METHOD FOR RECOVERING GYPSUM FROM WASTE GYPSUM BOARDS
Document Type and Number:
WIPO Patent Application WO/2023/032233
Kind Code:
A1
Abstract:
According to the present invention, waste gypsum boards are fractured or calcined so as to obtain hemihydrate gypsum and/or anhydrous type III gypsum, and the hemihydrate gypsum and/or the anhydrous type III gypsum is mixed with a gypsum slurry. The resulting gypsum slurry is subjected to solid-liquid separation by means of a filtration device, thereby obtaining gypsum particles and a filtrate that has passed through a filter cloth of the filtration device. In addition, the filtrate is refluxed into the gypsum slurry. The solid-liquid separation is carried out such that the concentration of suspended solids, which are composed of gypsum particles and inorganic impurities derived from the waste gypsum boards, the gypsum particles and inorganic impurities having been passed through the filter cloth, in the filtrate is 1,000 to 8,000 ppm by mass. Consequently, clogging of the filter cloth is able to be suppressed.
Inventors:
HIRANAKA SHINGO (JP)
Application Number:
PCT/JP2021/040097
Publication Date:
March 09, 2023
Filing Date:
October 29, 2021
Export Citation:
Assignee:
TOKUYAMA CORP (JP)
International Classes:
C01F11/46; B09B3/40; B09B5/00
Domestic Patent References:
| WO2012176688A1 | 2012-12-27 | |||
| WO2012176688A1 | 2012-12-27 |
Foreign References:
| JPH10128054A | 1998-05-19 | |||
| JPS4866073A | 1973-09-11 | |||
| JP2010013304A | 2010-01-21 | |||
| JP2010247113A | 2010-11-04 | |||
| JP2012131704A | 2012-07-12 | |||
| JP2016117617A | 2016-06-30 |
Attorney, Agent or Firm:
SHIOIRI Akira et al. (JP)
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