针对包头混合稀土精矿钠碱焙烧分解产物中氟、磷洗涤率低的问题,研究了水洗温度以及高压分解对焙烧矿中氟、磷洗涤率的影响。结果表明:常压下,水洗温度80℃,氟的洗涤率为75.65%,磷的洗涤率为40.87%;高压条件下,反应温度240℃,氟的洗涤率可达到95.11%,磷的洗涤率可达到62.85%。运用XRD,SEM-EDS分析发现:混合稀土精矿钠碱焙烧分解生成的Na_3PO_4,NaF易与Ca(OH)_2形成低熔点共熔体,胶结于稀土氧化物的边缘或者充填于其孔洞、裂隙内,是氟、磷洗涤率低的主要原因。高压反应对于稀土和氟、磷的分离具有强化作用,提高氟、磷的洗涤率。
The effect of washing temperature and decomposition under high-pressure on the washing rate of fluorine and phosphorus in roasted ore was examined aiming at low washing rate of fluorine and phosphorus of Baotou mixed rare earth concentrate roasted with Na_2CO_3-NaOH. The results indicated that the washing rate of fluorine was 75. 65% and phosphorus was 40. 87% when water temperature was 80 ℃ under normal pressure,and while washing under high-pressure and the temperature was 240 ℃,the washing rate of fluorine and phosphorus could reach 95. 11% and 62. 85% respectively. The results of XRD,SEM-EDS analysis showed that Na_3PO_4,NaF and Ca(OH)_2 was the decomposition product of mixed rare earth concentrate roasting with Na_2CO_3-NaOH. They could easily form low melting point eutectic that cemented on the edge of rare earth oxides and filling holes or cracks,which was the main reason of the low washing rate. The reaction under high-pressure could strengthen separation of rare earth from fluorine and phosphorus,and increase washing rate of fluorine and phosphorus.