【摘要】：草漿黑液堿回收產(chǎn)生的白泥硅含量較高,回收利用較難,目前主要是進行填埋處理,不僅占用土地,而且造成二次污染。因此,草漿堿回收白泥的高值資源化利用成為一個重要的研究方向。但其綠液中所含硅、硫等元素會對回收白泥品質(zhì)產(chǎn)生影響。本文針對草漿白泥制備輕質(zhì)碳酸鈣進行了研究,為草漿白泥資源化利用提供一個有效途徑。本文重點研究了綠液苛化反應(yīng)條件和綠液預(yù)處理條件對輕質(zhì)碳酸鈣質(zhì)量的影響,研究結(jié)果如下:(1)草漿堿回收制備輕質(zhì)碳酸鈣的最佳苛化反應(yīng)條件為:溫度110℃,時間120min,石灰用量為0.1g/ml。此條件下所得白泥白度為92.33%ISO,碳酸鈣含量95.82%,沉降體積2.8g.m L-1,105℃下?lián)]發(fā)物含量0.085%,鹽酸不溶物0.22%。(2)對苛化反應(yīng)的進一步研究表明,加入不同品質(zhì)的石灰、增加預(yù)苛化工段及苛化后通入二氧化碳或加入白度控制劑等都將對輕質(zhì)碳酸鈣的性能有一定影響。加入分析純生石灰所得白泥白度為91.07%ISO,如以石灰乳形式加入,白泥白度會進一步增加0.21%ISO而加入工業(yè)級生石灰所得白泥白度只有73.92%ISO,以石灰乳形式加入,白泥白度也能增加2.40%ISO;含預(yù)苛化的兩段苛化比一段苛化效果好,分析純級石灰的兩段苛化白泥白度和碳酸鈣含量分別增加了1.22%ISO和1.2%,而工業(yè)級石灰的兩段苛化所得白泥兩項指標分別增加了4.06%ISO和4.14%。在苛化反應(yīng)結(jié)束后通入二氧化碳,所得白泥白度和碳酸鈣含量都會有所增加,其中使用分析純級石灰時兩項指標分別提高0.85%ISO和1.4%,而使用工業(yè)級石灰時分別增加1.40%ISO和1.85%;對苛化反應(yīng)結(jié)束后未經(jīng)水洗的白泥加入白度控制劑,工業(yè)級石灰所得白泥白度可提高4.48%ISO,達到80.14%ISO。(3)綠液預(yù)處理條件對輕質(zhì)碳酸鈣質(zhì)量有一定的影響。分別向草漿綠液中加入硅酸鈣、偏鋁酸鈉、氧化鈣處理劑,均能有效的去除不容物,其中氧化鈣去除效果最好,可在20min實現(xiàn)綠液水不溶物的完全沉淀。(4)對綠液進行酸滴定,觀察絮凝物的變化情況。當綠液pH為12.76時,無絮凝物沉淀;當綠液p H降至10.42時,白色絮凝沉淀物出現(xiàn),隨著鹽酸的不斷加入絮凝物含量不斷增加。當p H降至1.16時,絮凝物基本消失。繼續(xù)加入鹽酸,當p H降至0.52時,絮凝物再次出現(xiàn),并不再消失。
[Abstract]:White mud produced by alkali recovery of straw pulp black liquor has a high content of silicon and is difficult to be recycled. At present, it is mainly landfill treatment, which not only occupies the land, but also causes secondary pollution. Therefore, it is an important research direction to recycle high value white mud from straw pulp. However, silicon, sulfur and other elements in the green liquor will affect the quality of white mud recovery. In this paper, the preparation of light calcium carbonate from straw pulp white mud was studied in order to provide an effective way for utilization of straw pulp white mud. In this paper, the effects of green liquor caustic reaction conditions and green liquor pretreatment conditions on the quality of light calcium carbonate are studied. The results are as follows: (1) the optimum caustic reaction conditions for the preparation of light calcium carbonate by alkali recovery from straw pulp are as follows: temperature 110 鈩，

本文編號：2196097