低品质叶蜡石的煅烧-酸洗增白研究

Study on whitening of low quality pyrophyllite by calcination-pickling process

现有的低品质叶蜡石矿石中含有较大量的铁杂质,白度低,因此其应用受到了很大限制。常见的非金属矿的增白方法有物理磁选方法、酸洗法、煅烧法、还原法等,这些增白方法由于叶蜡石的特殊结构而对叶蜡石并不完全适用。针对叶蜡石的结构特点,研究在煅烧法和酸洗法的基础上,开发出了一种新的增白方法:煅烧-酸洗技术。利用这种方法对叶蜡石原矿进行除铁增白处理,成功地将白度为71%的叶蜡石原矿粉提高到90%以上,得到了高品质的叶蜡石粉。实验还进一步研究了煅烧温度、酸液质量分数和酸洗温度对叶蜡石白度的影响,得出了最佳工艺条件:煅烧时间为2h,煅烧温度为700℃,酸液质量分数为20%,酸洗时间为2h,酸洗温度为70～80℃。

The applications of the existing low - quality pyrophyllite ore have been largely limited by its poor whiteness due to the existence of large amount of iron impurities. The common whitening methods for nonmetal ores included physical magnetic method, pickling method, calcining method and reduction method etc. However, these method were not quite suitable for whitening pyrophyllite owing to its special structure. In allusion to the structural features of pyrophyllite, a new Calcination - pickling technique has been developed to remove iron impurities on the basis of the study of calcining and pickling methods. The whiteness of crude pyrophyllite ore powder could be successfully improved from 71% to above 90% with this method. In addition, the influence of the calcination temperature, acid concentration and pickling temperature on the whiteness of the samples has been further studied. Then the optimal technological conditions were obtained, as follows, calcination time ： 2 h ; calcination temperature ：700 ℃, mass fraction of acid ： 20% ; pickling time; 2 h ; and pickling temperature ： 70 - 80 ℃.