湖北某高钙低品位含钒石煤钠化焙烧研究

Sodium Roast and Extraction of Vanadium from Low Grade Stone Coal with High Calcium from Hubei

对湖北某高钙低品位含钒石煤进行了NaCl、Na2SO4和两者复配焙烧及水浸—稀酸浸试验。添加单一NaCl焙烧时,过多的游离氧化钙容易与钒结合生成不溶于水的钒酸钙,影响钒的水浸率;添加单一Na2SO4焙烧时,虽然可以固定钙离子,但Na2SO4用量过大,经济和环境成本较高;当NaCl和Na2SO4添加量分别为7%和16%,焙烧温度为850℃,焙烧时间为3 h,水浸率可提高到51.47%,总浸率可达79.81%。在复合添加剂用量较低情况下取得了较好的浸出效果,一方面源于Na2SO4对较高含量钙离子的固定作用,抑制了难溶性钒酸钙的形成;另一方面,NaCl焙烧生成了氧化性较强的气体HCl、Cl2,既有助于破坏云母晶格结构,又有助于钒的氧化转价。

Sodium roast using NaCl, Na2SO4 and compound of both as roasting additives was studied in vanadium extraction from low grade stone coal with high calcium from Hubei Province. On the condition of roasting with sodium chloride, the water leaching rate of vanadium was affected because of too much free calcium oxide in the raw ore, which inclines to combine with vanadium, producing water-insoluble calcium vanadate. On the condition of roasting with sodium sulfate, even though it can fix calcium, the dosage of sodium sulfate was too large, and economic costs and environmental costs were very high. When roasting with the mixture of 7% NaCl and 16% Na2SO4 at the conditions of roasting temperature of 850 ℃ and roasting time of 3 h, the water leaching rate increased to 51.47%, and the total leaching rate of vanadium could reach 79. 81%. The leaching results were good at small dosage of roasting compound additives. On one hand, roasting with Na2SO4 can fix calcium, so as to inhibit the formation of water-insoluble calcium vanadate. On the other hand, the strong oxidizing atmosphere of HCl and Cl2 produced by adding NaCl can strengthen the destruction of the crystal structure of mica and promote the oxidation of vanadium.