麦草原料矿质元素在碱法制浆过程中的转移(Ⅱ)

用SEM-EDAX法、原子吸收光谱法探索了麦草原料矿质元素在碱法制浆及碱回收过程中的转移规律.结果表明,麦草原料的灰分含量高,经过碱法制浆及洗浆,原料中大量的矿质元素不同程度地转移到黑液中去;麦秆皮层及皮层的矿质元素较易溶解除去,但麦草浆Si的转移率仅为60%～70%.转移到黑液中的大量矿质元素将协同干扰碱回收过程及效果,是造成苛化工段白液澄清困难,白泥残碱量高、杂质含量高、无法进行白泥回收的根本原因.另外,黑液中的其他矿质元素还会造成设备腐蚀及操作障碍.

Removal Behavior of Mineral Elements of Wheat Straw Alkaline Pulping (Part Ⅱ)

The removal of the mineral elements in wheat straw during alkaline pulping and the effect of those mineral elements on the alkali recovery process were researched by means of SEM-EDXA and atomic absorption spectrometer. The results show that a large number of mineral elements in wheat straw, such as Si, Al, Mg, Fe and K will be removed and transferred to the black liquor to a great extent during pulping and washing, e.g. the transferring rate of Si element is 60% to 70%. As a result, the alkali recovery of black liquor will be interfered seriously. At causticizing stage, the existence of the above mineral elements will bring about a very high residue of soda in white mud and become impossible of mud recovery. On the other hand, a great quantity of K element in black liquor will always cause a grave scale on the water-cooling wall of the alkali recovery boiler. An enhanced pretreatment of straw material used, the development of new technologies and equipment, resulting in a substantial decrease of the mineral elements in material, will be of key importance for the improvement of alkali recovery rate of straw pulp black liquor and the realization of cleaner production of alkaline straw pulp.