高铁铝土矿直接还原回收粒铁和氧化铝

Direct reduction of high-iron bauxite for recovery of nuggets and Al_2O_3

采用煤基直接还原熔分技术和氧化铝溶出的方法,研究了直接还原工艺对粒铁尺寸和粒铁收得率的影响,以及钙铝比（w（Ca O）/w（Al2O3））对渣相组成和渣中氧化铝的溶出影响。结果表明,当（w（Ca O）/w（Al2O3））为1.7、w（C）/w（O）为1.4、还原熔分温度为1 450℃,还原熔分时间为20 min时,还原熔分过程中的粒铁尺寸最大,粒铁收得率也最高,粒铁尺寸和收得率分别为11.5 mm和93%。当（w（Ca O）/w（Al2O3））为1.0时,渣相组成主要以钙铝黄长石（Ca2Al（Al,Si）2O7）为主,当（w（Ca O）/w（Al2O3））为1.5时,渣相组成主要以钙铝黄长石（Ca2Al（Al,Si）2O7）、硅酸二钙（Ca2Si O4）和七铝十二钙（Ca12Al14O33）为主,当（w（Ca O）/w（Al2O3））为1.7-1.9时,渣相组成主要以七铝十二钙（Ca12Al14O33）和硅酸二钙（Ca2Si O4）为主。当（w（Ca O）/w（Al2O3））为1.7时,溶出时间为2.0 h时,氧化铝的溶出率最高,溶出率为87.5%,溶出率较0.5 h时提高了9.4%。因此,当渣系组成以七铝十二钙（Ca12Al14O33）和硅酸二钙（Ca2Si O4）为主时,更有利于氧化铝的溶出。

Effects of the direct reduction process on the nuggets size and recovery percent were investigated by coalbased direct reduction and leaching process, and the effects of （w（CaO）/w（Al2O3）） on the slag composition and leaching rate of alumina were investigated by the same way. The results show that when the （w（CaO）/w（Al2O3）） is 1.7, w（C）/w（O） is 1.4, reduction temperature is 1 450 ℃, and the reduction time is 20 min, the nuggets size is biggest and the nuggets recovery percent is highest, the nuggets size and recovery percent are 11.5 mm and 93%, respectively. When the （w（CaO）/w（Al2O3）） is 1.0, the furnace slag is mainly composed of gehlenite （Ca2Al（Al, Si）2O7）, when the （w（CaO）/ w（Al2O3）） is 1.5, the furnace slag is mainly composed of gehlenite （Ca2Al（Al, Si）2O7）, dicalcium silicate（Ca2SiO7） and mayenite（Ca12Al14O33）, when the w（CaO）/w（Al2O3） is 1.7-1.9, the furnace slag is mainly composed of dicalcium silicate （Ca2SiO4） and mayenite（Ca12Al14O33）. When the （w（CaO）/w（Al2O3）） is 1.7 and leaching time is 2.0 h, the leaching rate of alumina is highest which is 87.5%, the leaching rate is increased by 9.4% than that of 0.5 h leaching time. Therefore, when the furnace slag is mainly composed of dicalcium silicate（Ca2SiO4） and mayenite（Ca122Al14O33）, it is more conducive toleaching of alumina.