粉煤灰是我国当前排量最大的工业废渣之一，年排渣量已达3亿t以上，大量堆积的粉煤灰会对自然生态环境造成严重的危害。综合利用粉煤灰，实现粉煤灰的资源化利用，对于治理粉煤灰的污染具有十分重要的意义。文章提出先采用碱液常压浸出粉煤灰，生产白炭黑，然后采用碱石灰烧结法生产氧化铝，可实现粉煤灰的经济综合利用。研究表明：用苛性碱液在常压（＜125 ℃）下浸取粉煤灰45 min，粉煤灰中硅的提取率达到72.5 %以上，而氧化铝的总溶出率＜1.2 %；碳分浸取得到的硅酸钠溶液，可以生产氧化硅含量＞99 %的优质白炭黑，溶液中氧化硅转化率＞98 %；浸取硅后的渣中氧化铝含量＞55 %，氧化硅含量＜20 %，铝硅比≥2.7，适宜采用碱石灰烧结法生产氧化铝。碱石灰烧结法适宜的配方为：碱比 0.95～1.0，钙比 1.8～2.0；烧结温度宜为1 200～1 250 ℃；熟料溶出温度75～85 ℃，时间10～20 min，氧化铝回收率＞86 %。综合利用粉煤灰生产白炭黑和氧化铝，经济效益和社会效益显著。

The fly ash, discharged up to 300 million t each year, is one of the largest industrial waste residues in China. The accumulation of large quantities of fly ash will cause serious problems in nature and ecological environment. So it's significant to comprehensively utilize fly ash. A new technology is proposed in this paper. The fly ash is leached with alkali solution at the atmospheric pressure to produce white carbon black, and then alumina is recovered by sodalime sinter process. The technology can realize the utilization of fly ash economically and comprehensively. Research results indicate that the extraction of silica in fly ash is up to 72.5 % and the total extraction of alumina is less than 1.2 % when the fly ash is leached with alkali solution at the atmospheric pressure(＜125 ℃）for 45 min. White carbon black with silica content of more than 99 % can be achieved from the sodium silicate solution by the carbonation process. During the production process of the white carbon black, the conversion rate of silica in the solution reaches 98 %. The residue after leaching silica, with alumina and silica content of up to 55 % and less than 20 % respectively and mass ratio of alumina to silica of about 2.7, is suitable for recovering alumina by sodalime sinter process. The optimum conditions of sodalime sinter process are as follows: molar ratio of sodium oxide to alumina being 0.95~1.0, molar ratio of calcium oxide to silica being 1.8~2.0, roasting temperature being 1 200~1 250 ℃, leaching temperature being 75~85 ℃ and leaching time being 10~20 min. Under the above optimum conditions, the recovery of alumina is more than 86 %. It has remarkable economic and social benefits in comprehensive utilization of fly ash to produce white carbon black and alumina.