摘要 |
<p>Deinked paper pulp (12) is subjected to bleaching with sulfite or bisulfite ions and a reducing agent, preferably sodium bisulfite and sodium borohydride in aqueous alkaline solution. To assist the removal of ink particles, steam (16) is bubbled through the pulp causing the ink particles to rise to the surface as a black foam (20) which can be continuously removed. <IMAGE></p> |