| 摘要 |
The present invention relates to a method of decreasing the silicon, phosphor and/or aluminium contents of the cooking chemicals in the recovery of chemicals in an alkali delignification process of cellulose-containing material. Melt containing sodium carbonate, obtained from combustion of black liquor is treated so that the sodium carbonate is recovered in solid form, whereas the silicon, the phosphor and/or the aluminium is separated as a solution containing dissolved sodium silicates, sodium phosphates, and/or sodium aluminates. The melt may either be dissolved and this solution may be evaporated so as to crystallize the sodium carbonate, or the silicon, phosphor, and/or aluminium compounds may be dissolved by leaching melt, whereby the sodium carbonate is obtained in solid form. The solid sodium carbonate is further dissolved to form a solution having a low silicon, phosphor, and/or aluminium content. |
