硫酸化焙烧-水浸处理废稀土荧光粉工艺

针对当前废稀土荧光粉综合回收利用率低、不当处理造成环境污染严重等问题，采用硫酸化焙烧?水浸法处理废稀土荧光粉，考察了焙烧温度对物料形态的影响及焙烧温度、浓硫酸添加量对稀土氧化物浸出效果的影响，并对该工艺进行了初步环保评估。结果表明，在焙烧温度300℃、时间120 min、浓硫酸与废粉质量比为1.85及浸出温度25℃、时间120 min、液固质量比2:1的条件下，4种稀土氧化物的回收率分别为Y2O3 98.82%, Eu2O3 97.39%, CeO2 96.58%和Tb4O7 98.77%。硫酸化焙烧可使稀土分解为可溶性的硫酸盐和磷酸盐，并保证渣为环保的低放渣。浓硫酸添加量对4种稀土氧化物浸出率影响较大，焙烧温度对CeO2和Tb4O7浸出效果影响显著，在浓硫酸与废粉质量比1.85、浸出温度25℃、时间均为120 min的条件下，CeO2和Tb4O7的浸出率分别由焙烧温度200℃时的40.18%和37.18%提高至300℃时的96.58%和98.77%。稀土荧光粉在300℃下焙烧不会产生SO2和SO3等有害气体，焙烧过程中放出的气体主要为水蒸气和挥发的硫酸，物料失重约为10%。该工艺避免了焙烧过程中产生大量含硫、含氟、强酸性废气及难溶解的焙烧废渣，同时减少了环境污染及部分稀土资源浪费，具有广阔的工业应用前景。

Treatment technology of waste phosphor by sulfation-roasting-leaching

At present, in view of the existing problems in waste phosphor, such as lower comprehensive utilization and serious environmental pollution caused by improper handling, the method of sulfation-roasting?leaching was used to pre-treatment waste phosphor according to its problems to explore the effect of roasting temperature on the form of materials, roasting temperature and concentrated sulfuric acid addition on rare earth leaching. A preliminary environmental assessment of the process was carried out. The results showed that with the optimum leaching conditions which were roasting temperature of 300℃, roasting time of 120 min, concentrated sulfuric acid?waste phosphor mass ratio of 1.85, leaching temperature of 25℃, leaching time of 120 min and liquid?solid mass ratio of 2:1, the sulfation-roasting?leaching rate of rare earth oxides were Y2O3 98.82%, Eu2O3 97.39%, CeO2 96.58% and Tb4O7 98.77%. The material after sulfation-roasting?leaching indicated that sulfation-roasting can decompose rare earth into soluble sulfate and phosphate, and ensure that the slag was environmentally friendly and low slag. Concentrated sulfuric acid addition gave greater impact on the leaching of four kinds of rare earth, while roasting temperature brought larger influence on the leaching of CeO2 and Tb4O7, leaching rates increased from 40.18% and 37.18% at 200℃ to 96.58% and 98.77% 300℃, respectively. Waste phosphor calcined at 300℃ will not produce harmful gases such as SO2 and SO3 through the discussion of the emission of gas during the roasting process, the main gases released during roasting were water vapor and volatile sulfuric acid, and the material loss was about 10%. This process avoided the production of a large amount of sulfur-containing, fluorine-containing, strongly acidic waste gas and refractory roasting waste residue in the roasting process, and reduced environmental pollution and waste of rare earth resource, the new process has good prospects for industrial applying.