Method for cleanly and efficiently extracting rare earth elements from waste fluorescent powder
阅读说明：本技术 一种从废弃荧光粉中清洁高效提取稀土元素的方法 (Method for cleanly and efficiently extracting rare earth elements from waste fluorescent powder ) 是由 刘超 徐苏北 王学刚 李亚平 解原 柯平超 于 2020-05-16 设计创作，主要内容包括：本发明涉及一种从废弃荧光粉中清洁高效提取稀土元素的方法,属于废弃稀土荧光粉回收利用技术领域。将废弃荧光粉与碱按质量比为1：0.1~10混合均匀得到混合物；将得到的混合物在微波功率为1~5kW,升温至温度为300~800℃低温焙烧0.5~1h得到焙烧料；将焙烧料研磨成粉末然后按照液固比为1~6：1ml/g加入水溶液,在25~80℃水浸5~30min,固液分离后得到水浸渣和含铝水浸液,水浸渣重复水浸1~5次；将水浸渣按照液固比为5~10：1ml/g加入盐酸溶液,在温度为25~80℃下酸浸0.5~2h,固液分离后得到浸出渣和含稀土浸出液。本方法具有成本低、节能环保、稀土回收率高的优点。(The invention relates to a method for cleanly and efficiently extracting rare earth elements from waste fluorescent powder, and belongs to the technical field of recycling of waste rare earth fluorescent powder. Mixing waste fluorescent powder and alkali according to a mass ratio of 1: 0.1-10 to obtain a mixture; roasting the obtained mixture at a microwave power of 1-5 kW and a low temperature of 300-800 ℃ for 0.5-1 h to obtain a roasted material; grinding the roasting material into powder, and then mixing the powder with a solid-liquid ratio of 1-6: adding 1ml/g of water solution, soaking in water at 25-80 ℃ for 5-30 min, performing solid-liquid separation to obtain water leaching residues and an aluminum-containing water leaching solution, and repeatedly soaking the water leaching residues in water for 1-5 times; and (3) leaching the water leaching slag according to a liquid-solid ratio of 5-10: adding 1ml/g of hydrochloric acid solution, carrying out acid leaching at the temperature of 25-80 ℃ for 0.5-2 h, and carrying out solid-liquid separation to obtain leaching residue and leaching solution containing rare earth. The method has the advantages of low cost, energy conservation, environmental protection and high rare earth recovery rate.)
1. A method for cleanly and efficiently extracting rare earth elements from waste fluorescent powder is characterized by comprising the following steps:
first step, mixing alkali:
mixing waste fluorescent powder and alkali according to a mass ratio of 1: 0.1-10 to obtain a mixture;
step two, microwave low-temperature roasting:
roasting the mixture obtained in the first step at a low temperature of 300-800 ℃ for 0.5-1 h under the condition that the microwave power is 1-5 kW to obtain a roasted material;
step three, water leaching and impurity removal:
grinding the roasted material obtained in the second step into powder, and then mixing the powder with a solid-liquid ratio of 1-6: adding 1ml/g of water solution, soaking in water at 25-80 ℃ for 5-30 min, performing solid-liquid separation to obtain water leaching residues and an aluminum-containing water leaching solution, and repeatedly soaking the water leaching residues in water for 1-5 times;
step four, acid leaching and extracting rare earth elements:
and (3) carrying out leaching on the water leaching slag obtained in the third step according to a liquid-solid ratio of 5-10: adding 1ml/g of hydrochloric acid solution, carrying out acid leaching at the temperature of 25-80 ℃ for 0.5-2 h, and carrying out solid-liquid separation to obtain leaching residue and leaching solution containing rare earth.
2. The method for clean and efficient extraction of rare earth elements from waste fluorescent powder according to claim 1, wherein the method comprises the following steps: the waste fluorescent powder in the first step comprises green powder, blue powder or a mixture thereof.
3. The method for clean and efficient extraction of rare earth elements from waste fluorescent powder according to claim 1, wherein the method comprises the following steps: in the first step, the alkali is one or a mixture of several of sodium hydroxide, potassium hydroxide, sodium peroxide and sodium carbonate in any proportion.
4. The method for clean and efficient extraction of rare earth elements from waste fluorescent powder according to claim 1, wherein the method comprises the following steps: and in the fourth step, the concentration of the hydrochloric acid solution is 1-5 mol/L.
Technical Field
The invention relates to a method for cleanly and efficiently extracting rare earth elements from waste fluorescent powder, and belongs to the technical field of recycling of waste rare earth fluorescent powder.
Background
Rare earth fluorescent lamps have been widely used in lighting systems in most countries at home and abroad due to their energy saving and environmental protection advantages. At present, the output and the usage amount of the rare earth fluorescent lamp are at the top of the world in China. Meanwhile, a large amount of rare earth fluorescent lamps are abandoned in China every year, most of the abandoned fluorescent lamps enter a landfill site along with domestic garbage to be treated as solid garbage, and therefore mercury in the fluorescent lamps is released to pollute the environment, and the rare earth resources are greatly wasted. Rare earth is used as an important raw material of a new material in the century, and has been widely applied in the fields of pyrophoric alloys, permanent magnet materials, energy materials, superconducting materials, luminescent materials and the like. Although China is the most abundant world rare earth resource, rare earth is an extremely important strategic material and the occupied amount of people is small. Therefore, the recovery of rare earth elements from the secondary rare earth resource waste fluorescent powder has important strategic significance on the sustainable development of rare earth resources in China, energy conservation and environmental protection.
Patent 101985694A adopts selective oxidation-reduction method to recover yttrium and europium from rare earth phosphor waste. The process comprises the following steps: adding water into the rare earth fluorescent powder waste for pulping, then carrying out acid leaching, adjusting the pH value of filtrate by using ammonia water, then adding a small amount of ammonium sulfate, reduced zinc powder or barium chloride to precipitate europium preferentially, and extracting yttrium-rich filtrate to remove impurities such as iron, zinc and the like to obtain a fluorescent-grade yttrium chloride solution; dissolving europium slag in acid to obtain a europium-rich solution, adding zinc powder for full reaction, filtering, extracting the filtrate, washing and removing impurities to obtain a fluorescent-grade europium-containing feed liquid; finally, the yttrium and europium solution is converted into yttrium oxide and europium oxide after oxalic acid precipitation and low-temperature ignition. The selective oxidation-reduction method can obtain high-quality yttrium oxide and europium oxide products, but the production process is complicated and the recovery cost is high.
Although much research has been done on the aspect of recovering rare earth from waste fluorescent powder at home and abroad, the blue powder and the green powder in the fluorescent powder belong to a magnesium aluminate spinel structure, the structure of the fluorescent powder is difficult to destroy by adopting conventional acid leaching, and the blue powder and the green powder can be decomposed by alkaline roasting, but the fluorescent powder is usually roasted for a plurality of hours at a high temperature of more than 800 ℃, the decomposition of the fluorescent powder is still not thorough, and the leaching rates of the rare earth Tb and Ce are still low, so that the problems of high energy consumption, high cost, large alkali dosage and low comprehensive recovery rate of the rare earth exist in the conventional alkaline roasting process.
Disclosure of Invention
Aiming at the problems and the defects in the prior art, the invention provides a method for cleanly and efficiently extracting rare earth elements from waste fluorescent powder. The invention is realized by the following technical scheme.
A method for cleanly and efficiently extracting rare earth elements from waste fluorescent powder comprises the following steps:
first step, mixing alkali:
mixing waste fluorescent powder and alkali according to a mass ratio of 1: 0.1-10 to obtain a mixture;
step two, microwave low-temperature roasting:
roasting the mixture obtained in the first step at a low temperature of 300-800 ℃ for 0.5-1 h under the condition that the microwave power is 1-5 kW to obtain a roasted material;
step three, water leaching and impurity removal:
grinding the roasted material obtained in the second step into powder, and then mixing the powder with a solid-liquid ratio of 1-6: adding 1ml/g of water solution, soaking in water at 25-80 ℃ for 5-30 min, performing solid-liquid separation to obtain water leaching residues and an aluminum-containing water leaching solution, and repeatedly soaking the water leaching residues in water for 1-5 times;
step four, acid leaching and extracting rare earth elements:
and (3) carrying out leaching on the water leaching slag obtained in the third step according to a liquid-solid ratio of 5-10: adding 1ml/g of hydrochloric acid solution, carrying out acid leaching at the temperature of 25-80 ℃ for 0.5-2 h, and carrying out solid-liquid separation to obtain leaching residue and leaching solution containing rare earth.
The waste fluorescent powder in the first step comprises green powder, blue powder or a mixture thereof. The waste fluorescent powder mainly comprises the following rare earth element Eu2O30.1~4wt%，Tb4O71~8wt%，CeO21~10wt%。
In the first step, the alkali is one or a mixture of several of sodium hydroxide, potassium hydroxide, sodium peroxide and sodium carbonate in any proportion.
And in the fourth step, the concentration of the hydrochloric acid solution is 1-5 mol/L.
The invention has the beneficial effects that:
1. the invention adopts microwave heating to carry out alkaline roasting, can improve the treatment efficiency, promote the decomposition of the phase of the fluorescent powder, strengthen the reaction process and reduce the reaction activation energy, and compared with the conventional alkaline roasting method, the invention can reduce the reaction temperature, shorten the reaction time, reduce the alkali dosage in the roasting process and improve the leaching rate of the rare earth.
2. The invention can realize the high-efficiency separation of impurities such as aluminum and the like and rare earth elements through the processes of microwave low-temperature roasting, water leaching, acid leaching and the like, and obtain the rare earth leachate with low impurity content.
3. The method has the advantages of low cost, energy conservation, environmental protection and high rare earth recovery rate.
Drawings
FIG. 1 is a process flow diagram of the present invention.
Detailed Description
The invention is further described with reference to the following drawings and detailed description.