氯化焙烧回收高铁硫酸烧渣中有价金属的实验研究

Experimental study on recovering valuable metals from pyrite cinder by chloridizing roast

从高铁硫酸渣本身的特点出发,选用氯化挥发法进行有色金属分离的实验。结果表明:氯化剂的含量、焙烧温度、焙烧时间均会对有价金属的挥发产生影响;随着氯化剂的含量的增加,金、银、铜、铅、锌挥发率均会提高,挥发率达到最大值后稳定;金、银达到最大挥发率所需氯化剂分别为4%、6%,而铜、锌需9%;高温会促进氯化剂的分解,最重要的是促进金属氯化物的挥发,从而提高挥发率,但是在高氯化剂含量(9%)的情况下,焙烧温度超过1150℃后,随着温度的升高铜、铅、锌的挥发率反而会降低;焙烧时金属氯化物挥发需20 min,而氯化剂完全分解需60 min。综合考虑后最终选择的条件是烧渣中加入9%CaCl_2在1100℃下焙烧,在此条件下焙烧后金、银品位及挥发率分别为:0.17g/t、91.26%、6.24g/t、80.05%,其它元素的含量也都达标。

Chloride volatization process is adopted to separate nonferrous metals according to the characteristics of pyrite cinder. The experimental results demonstrate that the calcium chloride content, roasting temperature and time all have effects on the process. With the rise of calcium chloride content, the volatile ratio of valuable metals such as gold, silver, copper, lead and zinc increases gradually, reaching the maximum and thereafter remains unchanged. When the calcium chloride contents reach to 4% and 6% respectively, the volatile ratio of gold and silver increases to their maximums, and 9% for copper and zinc both. High temperature has a good effect on the chloride volatization process because it promotes the decomposition of calcium chloride, and above all, the volatilization of metal chlorides. As high content as 9% calcium chloride added, if the temperature is too high （higher than 1150 ~C）, the volatile ratio descends instead. It takes 20 min for the volatilization, but 60 min is needed for the decomposition of calcium chloride. Gold and silver content and volatilization ratios of roasted pyrite under the optimum conditions of 9% calcium chloride content at 1100℃ for 60 min are 0.17 g/t, 91.26% and 6.24 g/t, 80.05% respectively. The content of other elements also conformed to the requirements.