| 摘要 |
<p>Spent digestion liquor of alkaline reaction, known as black liquor, resulting from the chemical digestion of fibrous materials is treated to precipitate the non-cellulosic organic material by addition of a neutralizing agent to produce a pH value between 8 and 9 without addition of other materials or substantial concentration. Neutralization is preferably effected by bubbling carbon dioxide into the liquor. The liquor is heated to 50--70 DEG C. during or after precipitation to coagulate the precipitate, and is cooled prior to filtration. The filtrate is treated for re-use as digestion liquor. The precipitate is washed and treated with dilute sulphuric or other acid to neutralize any alkali; it is again washed and dried and finally powdered. The material may be used as a binder for a moulding composition as described in Specification 460,939, [Group V]. The Specification as open to inspection under Sect. 91 also comprises the recovery of the non-cellulosic organic material by electrolysis at room temperature in a cell having a mercury cathode, the amalgam formed being treated for recovery of mercury and caustic soda is a separate cell. One form of cell comprises a bottom layer of mercury into which dip partitions dividing the cell into three compartments. The outer compartments containing the black liquor are provided with anodes and the inner one containing water or caustic soda solution with a cathode of iron or carbon, the mercury constituting an intermediate electrode. The mercury is transferred between the compartments by rocking. A shunt circuit containing a variable resistance may be connected between the mercury and the cathode. In a modification, a rotary anode provided with a scraper for removal of the deposit is employed; the anolyte is continuously circulated and filtered for removal of the deposit. This subject-matter does not appear in the Specification as accepted.ALSO:Spent digestion liquor of alkaline reaction, known as black liquor, resulting from the chemical digestion of fibrous materials is treated to recover the non-cellulosic organic material by addition of a neutralizing agent to produce a pH value between 8 and 9, without addition of other materials or substantial concentration. Neutralization is preferably effected by bubbling carbon dioxide into the liquor. The liquor is heated to 50--70 DEG C. during or after precipitation to coagulate the precipitate, and is cooled prior to filtration. The filtrate is treated for re-use as digestion liquor. The precipitate is washed and treated with dilute sulphuric or other acid to neutralize any alkali; it is again washed and dried and finally powdered. The material may be used as a binder for a moulding composition as described in Specification 460,939, [Group V].</p> |
