【作者】 马玉天；

【导师】 龚竹青； 武浚；

【作者基本信息】 中南大学 ， 冶金物理化学， 2006， 博士

【摘要】 我国大多数铜冶炼企业从处理铜阳极泥的副产品—铅碲渣中提取碲通常采用碱浸-硫化钠除杂-中和-电解工艺，该工艺的缺点是流程冗长、碲回收率低、产品质量不稳定和对原料的适应能力不强。本课题研究的目的是研究确定一条对原料成分的变化适应性强、工艺流程短、操作简单、碲回收率高和产品质量稳定的新工艺流程。本文在总结前人研究成果的基础上，通过热力学计算和试验研究确定了硫酸浸出-亚硫酸钠（或二氧化硫）还原碲-粗碲亚硫酸钠脱硒-盐酸除杂-碲粉的新工艺，并在生产现场进行了扩大试验，验证了工艺流程合理可行，工艺条件适当。试验确定的最佳浸出条件为：H₂SO₄浓度5 mol／L，时间240min，温度80℃，液固比6∶1，铅碲渣粒度≤0.124mm（-120目）；亚硫酸钠还原碲的最佳条件是：质量比Na₂SO₃／Te＝10，NaCl／Te＝4，温度80℃，时间60min；或二氧化硫还原碲最佳条件是：SO₂／Te＝5，NaCl／Te＝6，温度80℃，时间40min。粗碲粉亚硫酸钠除硒的适宜条件为：液固比10∶1，Na₂SO₃浓度1 mol·L^-1，温度≥95℃，反应时间60min。该工艺碲的总回收率＞90％，所得碲粉含碲99.669％，达到商品级碲粉要求。该工艺从高铅碲渣中提取碲，具有流程短，对原料的适应性强，工艺条件易于控制，生产成本低，碲产品质量稳定的优点。通过热力学计算，确定了化学除杂制取高纯碲是可行的，在此基础上以所得商品级碲粉为原料，通过研究确定了碲粉-HNO₃氧化除杂-NaOH溶解-Na₂S除杂-SO₂还原除硒-SO₂还原制取99.99～99.999％高纯碲的全化学法工艺流程，试验确定的最佳工艺条件：HNO₃氧化碲粉的用量系数为1.05；硫化钠除杂pH＝11，硫化钠用量系数1.05，反应温度90℃；SO₂还原除硒盐酸浓度6mol／L，还原温度85℃；SO₂还原碲盐酸浓度1.5mol／L，还原温度85℃。在上述最佳条件下制取得到含碲≥99.9992％，杂质含量≤0.0008％的高纯碲，该法碲的回收率＞90％。以上述全化学法工艺制取的高纯碲为原料，用自制设备采用化学气相沉积法（CVD）在聚乙烯箔上沉积得到光谱选择性碲膜。采用X-射线衍射（XRD）、扫描电子显微镜（SEM）、能量弥散X-射线仪（EDX）、紫外／可见／近红外分光光度计（UV-Vis-NIR）和傅立叶红外光谱（FTIR）等物理化学表征手段研究了碲膜的结构、形貌和光学性能，研究发现聚乙烯箔（polyethylene）基体高锰酸钾改性前后，沉积碲膜的速率以及所得碲膜的结构和光学性能完全不同：改性后聚乙烯箔由疏水性变为亲水性，形核率提高，成核密度增加，膜的附着力提高，碲膜沉积速度加快，碲膜由形成（100）织构倾向转变为（011）、（102）和（003）织构，但在UV／VIS／NIR光谱范围的反射率和8-13μm光谱范围的透过率降低。碲膜的制取研究表明改性聚乙烯箔基体温度越高，碲膜沉积速度越快，碲膜晶体粒度越大，膜的附着力降低，基体温度不能超过60℃；沉积时间越长、碲膜越厚，膜的表面越粗糙，从而降低碲膜在UV／VIS／NIR区间的反射率和UV／VIS／NIR、IR波长区间的透射率；沉积气体中H₂Te浓度越高，沉积速率越大，形核密度越高，碲膜越致密，表面越光滑，显著提高碲膜在UV／VIS／NIR区间的反射率，降低在该区间的吸收率。采用SEM和EDX对化学气相沉积法在聚乙烯箔上沉积制取碲膜的成核和生长过程进行了研究，从热力学和动力学角度分析了这一过程，结果表明：碲在裸聚乙烯基体上形核为自发形核，在高锰酸钾改性聚乙烯基体上形核为非自发形核；在改性聚乙烯基体上碲膜以岛状模式形核，当岛达到临界状态后发生相变形成固体碲膜，在固体碲膜吞并岛后，碲膜进入层状生长期。更多还原

【Abstract】 Many copper smelting enterprises in China usually use alkaline leaching-removing impurities by sodium sulfide-neutralization-electrolysis process to recover tellurium from the lead tellurium slag resulting from the treatment of copper anodes slime. This process has drawbacks such as long flowsheet, the tellurium recovery yield being low, the product quality being unstable and less flexibility to raw material. The research goal of the dissertation is to find a new process with many advantages including adaption to chemical composition change of the slag, short process, simpley operation, high tellurium recovery ratio and stable product quality.In this study, on the basis of the summarizesing of predecessor’s research results, a new process for the recovery of tellurium from lead tellurium slag was developed through thermodynamic computation and the experimental study. The new process is consist of sulfuric acid leaching--reduction of Te by sodium sulfite（or sulfur dioxide）-Se removing from raw tellurium by sodium sulfite-purification of Te by hydrochloric acid-powdered tellurium. Large-scale experiment was conducted in a factory. The experiment result has confirmed the technical process is feasible, technological conditions are suitable. The experiment showed the optimum process parameters of sulfuric acid leaching were as follows: H₂SO₄ concentration 5 mol/L, reaction time 240min, reaction temperature 80℃, liquid-to-solid rato 6 : 1, particle size of lead tellurium slag≤0.124mm （-120 mesh） The optimum process parameters of reduction of Te by sodium sulfite in sulfuric acid solution were as follows: mass ratio Na₂SO₃/Te=10, NaCl/Te=4, reaction temperature 80℃, reaction time 60min. The optimum process parameters of reduction of Te by SO₂ in sulfuric acid solution were SO₂/Te=5, NaCl/Te=6, reaction temperature 80℃, reaction time 40min. The suitable condition for removing of Se from raw powdered tellurium by sodium sulfite were liquid-to-solid 10 : 1, Na₂SO₃ concentration 1 mol·L-1, reaction temperature≥95℃, reaction time 60min. A total tellurium recovery ratio of higher than 90% and commercial grade tellurium powder with purity 99.669% was obtained from the new process. Our process extraction of Te from lead-rich tellurium sediment has many advantages such as applicabiling to stag chemical composition change, short process, easy control, low production cost and stable product quality.The feasibility of preparing high-purity tellurium by chemical of impurity was confirmed through thermodynamic computation. The entire chemical process of preparing high-purity tellurium containing 99.99～99.999% Te with commercial grade tellurium powder has confirmed through the study. The process consists of tellurium powder-eliminating impurity by HNO3 oxidation-NaOH dissolving-eliminating impurity by Na2S-removing of Se by SO2 reduction-high purity tellurium obtained by reduction with SO2. The experiment showed the optimum process parameters of prepared high purity tellurium were as follows: HNO₃ excess coefficient 1.05, pH=11 for eliminating impurity by Na₂S, Na₂S excess coefficient 1.05 at reaction temperature 90℃, removing of Se by SO2 reduction at HCt concentration 6mol/L and reaction temperature 85℃, high purity tellurium preparing by reduction with SO₂ at HCl concentration 1.5mol/L and reaction temperature 85℃. Under above condition, high purity tellurium with purity of high than 99.9992% and impurity of low than 0.0008% was directly obtained from our process. The recovery yield of tellurium obtained from entire chemical process is higher than 90%.In this paper, spectral selectivity tellurium films was deposited onto polyethylene foil by chemical vapor deposition （CVD） method with self-made equipment and the feed of high pure tellurium came from the above entire chemical process. The structure, surface morphology and optical properties of the tellurium films were investigated with powder X-ray diffraction （XRD）, scanning electronic microscopy （SEM）, energy dispersive X-ray （EDX）, ultraviolet-visible-near infrared ray Spectrophotometer （UV-Vis-NIR） and FT-infrared ray spectrophotometer （FTIR）. The result showed the tellurium films deposited onto polyethylene foil and permanganate （KMnO₄） surface-treated polyethylene foil had completely different deposition speed, structure and optical properties. After the treatment the polyethylene foil becomes hydrophilic. Higher nucleation rate and density, better adhesion and high deposition speed of the tellurium films are obtained by permanganate （KMnO₄） surface treatment of polyethylene. The tellurium films texture change from （100） texture to （011）, （102） and （003） texture, but the reflectance of tellurium film in the UV/Vis/NIR region and the transmission of tellurium film in the 8-13μm region are decreased. The result also showed deposition speed and crystallite size of the tellurium film rise with the increasing temperature of substrate, but the adhesion decrease with the increasing temperature, so the deposition temperature of substrate can not exceed 60℃. The thickness and the surface roughness of Te film increases with the increasing deposition time, which leads to decrease of the reflectance and the transmission of tellurium film in the UV/Vis/NIR and IR region, respectively. The deposition speed, surface evenness, nucleation rate and density of tellurium film rise with the increasing concentration of H2Te in the mixture gas, which leads to increase in the reflectance and decrease in the absorption of tellurium film in the UV/Vis/NIR region, respectively. The progresses of nucleation and growth of tellurium thin film are studied by SEM and EDX, and also discussed from the point of view of kinetics and thermodynamics. The result indicated that spontaneous nucleation of tellurium occurs on the bare polyethylene substrate and non-spontaneous nucleation on treated polyethylene substrate. The nucleation occurs in the island growth mode on the treated polyethylene substrate. When the critical state of the island is reached the phase transformation occurs, and solid tellurium film forms. After the solid tellurium film swallows up the island, the tellurium film enters the layer-by-layer growth period.更多还原