X射线衍射半定量法测定钒渣的钙化过程

Measurement of Calcification of Vanadium Slag by XRD Semi-quantitative Method

钙化焙烧钒渣工艺在中国目前还处在工业化试验阶段，钒渣中钒的回收率仅为69.7%，不清楚是钙化过程或是浸取过程导致回收率低。为此，采用X射线衍射半定量法对影响钙化率的因素进行了研究。试验结果表明，钒渣的钙化率随CaO和V2O5含量的增加而增大，随温度的升高而降低。太高的温度产生了Fe［III］V［V］O4,从而降低了产物中钒酸钙的含量。产物中最高的钒酸钙含量达到100%，其使用的原料中CaO含量为50%，V2O5含量为25%，Cr2O3、SiO2和Fe2O3含量之和为25%,是在790 ℃的温度下反应8 h得到的。SEM面扫结果表明，表面光滑的块状钒酸钙与铬酸钙、铬酸铁、钒酸铁、氧化铁和硅酸盐相混合。目前低的钒回收率是由于浸出率低而不是钙化率所致。X射线衍射半定量法对钙化率的研究为生产提供了新的认识。

Calcification roasting process of vanadium slag is just currently situated at pilot stage of indus- trialization in China, while the recovery ratio of vanadium from vanadium slag is only 69.7%. It is not clear so far whether the calcification or leaching process leads to the low recovery ratio. This paper studied the factors influencing calcification ratio directly by XRD （X-ray diffraction） semi-quantitative method. Experimental resuhs show that calcification ratio of vanadium slag increases with rise of CaO and V2 05 content while decreases with increase of temperature. Fe [III ] V [ V ] 04 can be formed at exorbitant tem- peratures leading to a decrease in calcium vanadate content of the product. A highest calcification ratio of 100% can be obtained at 790~C for 8 h with material containing 50% of CAO,25% of V205 ,total 25% of Cr2 03, SiO2, and Fe203. From SEM results, it indicates that block calcium vanadate possessing smooth surface is mixed with calcium chromate, ferric chromate, ferric vanadate, ferric oxide and silicates. The re- search proves that present low recovery ratio of vanadium is due to the low efficiency of leaching rather than calcination, which provides a new insight for the production.