高钙对含钒石煤钠化焙烧过程的影响

Effect of High Calcium on Roasting Process of Vanadium-Bearing Stone Coal with Sodium Salt

对湖北某高钙型含钒石煤进行钠化焙烧-水浸-稀酸浸提钒研究,当氯化钠添加量为10%,850℃下焙烧2 h,钒的水浸率很低,仅为14.28%,总浸率为69.14%。为提高水浸率,研究除钙和固钙后再焙烧提钒。将脱碳样先用5%(体积分数)的盐酸除钙和2%(体积分数)的硫酸固钙后,在相同的条件下进行钠化焙烧,水浸率分别达47.54%和35.01%,总浸率分别为66.16%和60.81%。XRD分析表明,盐酸除钙后的样品中石灰的衍射峰消失,从而使得水浸率得到明显的提高,并可降低最佳焙烧温度;硫酸固钙后的样品中石灰的衍射峰消失,同时半水石膏开始出现,CaSO4的生成可以抑制不溶于水的钒酸钙等物质的生成,从而可以小幅度提高水浸率,提高焙烧的烧结温度、减轻物料烧结,但会造成总浸率小幅度降低,且在加入一定量的氯化钠后CaSO4会发生分解,导致水浸率降低。在相同的焙烧条件下,采用盐酸除钙后焙烧比硫酸固钙后焙烧得到的钒的水浸率高。

The sodium salt roasting-water leaching-dilute acid leaching experiment was adopted to extract vanadium from high calcium vanadium-bearing stone coal from Hubei. When the stone coal was roasted with 10% sodium chloride, at 850 ℃ for 2 h, the water leaching rate of vanadium was only 14.28%, and the total leaching rate of vanadium was 69.14%. In order to improve the water leac- hing rate of vanadium, calcium removal and calcium stabilization before roasting were investigated. After calcium removal by 5% （ vol- ume fraction） of HC1 and calcium stabilization by 2% （volume fraction） of H2 SO4 separately, the decarbenized stone coal was roasted with sodium chloride under the same condition, as a result, the water leaching rate of vanadium reached 47.54% and 35.01%, and the total leaching rate of vanadium reached 66.16% and 60.81%, respectively. XRD results showed that the lime disappeared after calcium removal by HC1, therefore the water leaching rate of vanadium increased obviously and the optimal roasting temperature could be reduced. The results also showed that the lime disappeared after calcium stabilization by H2SO4, and the semi-hydrated gypsum started to emerge. The formation of CaSO4 could inhibit the formation of the water-insnluble substances, such as calcium vanadate, thus the water leaching rate of vanadium increased slightly, the sintering temperature could be raised and the sintering of roasting materials also could be lightened. However, the total leaching rate of vanadium decreased a little, and CaSO4 decomposed when adding a certain dos- age of sodium chloride, which resulted in the water leaching rate of vanadium dropping. Under the same masting conditions, the water leaching rate of vanadium of the calcium removal sample by HC1 was higher than that of the calcium stabilization sample by H2SO4.