铜阳极泥O_(2)-SO_(2)焙烧定向转化碲物相强化碲浸出

Phase-directed transformation of telluride from copper anode slime for enhancement of tellurium leaching by O_(2)-SO_(2)roasting

碲是国家战略准金属,全球90%碲产于铜阳极泥,而硫酸化焙烧-碱浸法是我国从铜阳极泥中提取碲的常用工艺,但存在碲浸出率偏低问题。为此,本研究提出采用O_(2)-SO_(2)焙烧法处理铜阳极泥,通过调节O_(2)、SO_(2)分压,精准控制焙烧过程中的氧势和硫势,将铜阳极泥中碲化物高效定向转化为TeO_(2)。首先,对O_(2)-SO_(2)焙烧铜阳极泥的工艺参数进行优化,然后焙砂采用水浸分离铜、再用NaOH(100 g/L)浸出碲;最后,用碲化亚铜代替铜阳极泥对焙烧过程的碲物相转变机制进行研究。结果表明:在O_(2)-SO_(2)气氛中(体积比为7∶3),温度为600℃的条件下焙烧铜阳极泥3 h后,硒挥发率为98.04%,经水浸-碱浸后,碲浸出率为83.69%,实现了硒高效挥发及碲的高效浸出;在焙烧过程中,碲化亚铜先被氧化分解成Cu_(2.86)Te_(2)和CuO,随着温度的升高,Cu_(2.86)Te_(2)继续被氧化分解成CuTe和CuO,最后CuTe被氧化为TeO_(2)和CuO,同时,CuO进一步与SO_(3)反应生成CuSO_(4)。

Tellurium is an important strategic metalloid,and about 90%of the world’s tellurium is produced from copper anode slime.At present,the sulfatizing roasting-alkaine leaching method is commonly used to extract tellurium from copper anode slime in China,but the leaching rate of tellurium is low in this process.In order to sharply improve the leaching rate of tellurium by alkaline leaching from copper anode slime at atmospheric pressure,the O_(2)-SO_(2)roasting method was proposed to treat copper anode slime.The oxygen potential and sulfur potential in the roasting process were precisely controlled by regulating the partial pressures of O_(2)and SO_(2),and telluride was efficiently and directionally converted to TeO_(2)in copper anode slime.Firstly,the process parameters of copper anode slime by O_(2)-SO_(2)roasting were optimized.The results show that the selenium evaporation rate reaches 98.04%after roasting 3 h under the conditions of O_(2)-SO_(2)volume ratio of 7∶3 and temperature of 600℃,and the tellurium leaching rate reaches 83.69%after by water leaching followed NaOH(100 g/L)leaching.As a result,the efficient separation of selenium and extraction of tellurium are achieved.Secondly,the phase transformation mechanism of cuprous telluride under O_(2)-SO_(2)roasting process is revealed.The results show that cuprous telluride is decomposed into Cu_(2.86)Te_(2)and CuO after oxidation,and then the Cu_(2.86)Te_(2)is further resolved into CuTe and CuO with the temperature increases,and finally CuTe is oxidized into TeO_(2)and CuO.At the same time,the CuO reacts with SO_(3)to form CuSO_(4).