| 摘要 |
The invention relates to methods for preparation titanium dioxide from pulping residues which are produced as waste from a conventional sulfate pulping procedure for titanium dioxide preparation. The invention especially relates to methods for obtaining titanium dioxide from pulping residues produced by a conventional sulfate pulping procedure for titanium dioxide preparation. Said methods comprise the following steps: (a) the pulping residues are mixed with sulfuric acid and optionally other titanium-containing raw materials in such a way that between 60 and 100wt.% of the TiO2 used is in the form of pulping residues and between 0 and 40wt.% of the TiO2 used is in the form of standard raw materials; (b) the pulping reaction is started with fuming sulfuric acid or water or diluted sulfuric acid; (c) the obtained reaction product is dissolved; (d) the undissolved solid materials are separated from the liquid phase; and (e) titanium dioxide is obtained from the liquid phase.
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