Invention Grant
- Patent Title: Precipitated calcium carbonate from pulp mill waste having an improved brightness, method for the production and use thereof
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Application No.: US15133492Application Date: 2016-04-20
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Publication No.: US09944535B2Publication Date: 2018-04-17
- Inventor: Michael Pohl , Thomas Schmölzer
- Applicant: Omya International AG
- Applicant Address: CH Oftringen
- Assignee: Omya International AG
- Current Assignee: Omya International AG
- Current Assignee Address: CH Oftringen
- Agency: Amster, Rothstein & Ebenstein LLP
- Priority: EP11166216 20110516
- Main IPC: C01F11/18
- IPC: C01F11/18 ; B82Y30/00 ; C01F5/24 ; C09C1/02 ; C01B32/60 ; C08K3/26

Abstract:
The present invention relates to a process for the production of a precipitated divalent metal ion carbonate product from a divalent metal ion carbonate which was recovered from waste, the precipitated divalent metal ion carbonate product having an improved brightness, the process comprising the steps of: providing a low-purity divalent metal ion carbonate material, the divalent metal ion carbonate material being recovered from waste; calcining the divalent metal ion carbonate material in order to obtain a divalent metal ion oxide; slaking the divalent metal ion oxide in order to obtain an aqueous suspension of a divalent metal ion hydroxide; carbonating the aqueous suspension of the divalent metal ion hydroxide with a carbon dioxide containing compound in order to obtain fine precipitated divalent metal ion carbonate particles; post-treating the fine precipitated divalent metal ion carbonate particles to obtain fine discrete precipitated divalent metal ion carbonate particles; adding the fine discrete precipitated divalent metal ion carbonate particles to an aqueous suspension of divalent metal ion hydroxide that was obtained by slaking high-purity divalent metal ion hydroxide in order to obtain a resulting reaction mixture; and carbonating the resulting reaction mixture in order to obtain the precipitated divalent metal ion carbonate product having an improved brightness.
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