3N碲还原熔炼-扒渣提纯法制备4N碲

A new technique of producing 4N Te from 3N Te by the deoxidizing melting and slagging-off purifying method

为了满足碲的高端应用,开展了以3N纯度(即质量分数为99.9%)粗碲为原料,制备4N碲的工艺条件和中试研究,并采用等离子光谱仪(ICP)对样品进行了测试分析,确定了一种3N碲还原熔炼-扒渣提纯法制备4N碲的工艺方法:将1%的还原剂与50目(300μm)3N粗碲混匀,在700℃下还原焙烧1h;加入0.4%的造渣剂,搅拌造渣15min;粗碲杂质元素与造渣剂结合形成上浮渣,多次刮除至再无浮渣产生;将除渣后的碲熔浆倾入石墨模中铸锭,得到碲锭产品。该产品碲的质量分数≥99.998%,杂质元素总的质量分数<15×10-6,每种杂质元素的质量分数<5×10-6,完全符合4N纯度精碲要求。中试结果表明,该工艺流程简单,工艺周期短,成本低廉,环境污染小,是一种可规模化生产4N碲的新工艺。

The study aims to figure out the parameters through a pilot research to purify tellurium from 3N（99.9%）into 4N（99.99%）to maintain the demand of high pure tellurium.With the sample analysis via ICP-AES,the process is set up through reduction,melting and slagging-off.The first step is to mix 1% reduction agent with 50 mesh（300 μm）99.9% tellurium and bake 1 hour under 700℃ to reduce Te.The second step is to add 0.4% slag-making agent and stir up 15 minutes to form slag.The impurity element will combine with the slag-making agent to form float slag which is removed out through scratching.The third step is to pour the tellurium slurry into a kind of graphite dye to form ingot.The tellurium content is above 99.998%.The mass fraction of the total impurity element is below 15×10^-6,and that of individual impurity element is below 5×10^-6.The finished tellurium is up to the 99.99% specification.The process is simple,short recycle time,low cost and little contamination.It is a new process to produce 4N of tellurium on a certain scale.