Method for extracting aluminum, silicon oxide and rare earth from waste rare earth polishing powder

Abstract

The invention discloses a method for extracting aluminum, silicon oxide and rare earth from waste rare earth polishing powder. The method comprises the following steps that (1) strong acid is added into the pretreated waste rare earth polishing powder, the aluminum and the rare earth are dissolved, and silicon oxide powder is left in leaching residues; (2) the leaching residues containing the silicon oxide powder are washed and purified so as to obtain the silicon oxide powder; (3) a precipitant is added into a leachate so as to precipitate the rare earth, and filtering is carried out so as toobtain a rare earth salt and an aluminum salt solution; (4) after the aluminum salt solution is neutralized, standing and settling are carried out for 2-12 hours so as to obtain an aluminum-containing product; and (5) the rare-earth salt is subjected to fluorination and is burnt so as to prepare rare earth polishing powder. According to the method, silicon, aluminum and the rare earth in the waste rare earth polishing powder are comprehensively recovered to form the superfine silicon oxide powder, the aluminum salt and the rare earth polishing powder, no solid waste is generated, and all valuable elements are utilized.

Description

technical field [0001] The invention belongs to the technical field of solid waste recycling, and in particular relates to a method for extracting aluminum, silicon oxide and rare earth from waste rare earth polishing powder. Background technique [0002] In recent years, with the rapid popularization and replacement of mobile phones and the widespread use of flat screens and automotive central control screens, more than 100,000 tons of waste rare earth polishing powder solid waste is produced every year. From the perspective of chemical composition, waste rare earth polishing powder The content of alumina in rare earth polishing powder is generally 15-25%, the content of silicon oxide is 30-60%, and the content of rare earth oxide is 15-50%. The polishing process is a process with a high degree of cleanliness. The rare earth polishing powder and optical glass used at the same time are all high-purity raw materials and components. The waste rare earth polishing powder produc...

AI Technical Summary

Problems solved by technology

[0004] At present, there are related patents on the recycling of waste rare earth polishing powder, such as the Chinese patent "Method for Extracting Rare Earth Oxides from Polishing Powder Waste" (publication number: 108531735A), which discloses the preparation of rare earth salts by acid leaching-extraction back-extraction-precipitation - The process of preparing rare earth oxides by burning rare earth salts, in the first step of acid leaching, due to the subsequent extraction, the acidity at the end of the leaching is low, which will lead to a low leaching rate of rare earths

At the same time, during acid leaching, after aluminum ions and rare earth ions enter the solution, because these two ions will be extracted at the same time during the extraction process, multi-stage extraction and separation are required, and the cost is high. At the same time, aluminum ions are likely to cause poisoning of the extractant, making the price The performance of the expensive extractant gradually declines until it fails, and the extractant needs to be saponified and consumes a large amount of sodium hydroxide, resulting in a high cost of the entire process. In actual production, it is difficult to realize industrial production due to cost problems; Chinese patent "A method for preparing lanthanum cerium oxalate from waste rare earth polishing powder" (publication number: 102659559B) discloses that lanthanum cerium oxalate is obtained by sulfuric acid leaching and oxalic acid precipitation, but the aluminum in waste rare earth polishing powder is neutralized Mixed with gypsum, aluminum resources are not fully utilized; the Chinese patent "A Method for Clear and Segmented Recovery of Rare Earth Elements from Rare Earth Polishing Powder Waste Slag" (publication number: 104060111A) discloses a method for segmental recovery of rare earth elements In the second stage of recovery, concentrated sulfuric acid is used for leaching to produce ceric sulfate, but in the first stage, lanthanum and praseodymium are preferentially dissolved with low-concentration hydrochloric acid, and about 30% of cerium will enter the leach solution. There are lanthanum ions, cerium ions, aluminum ions in the solution. Ions and praseodymium ions have complex components, and it is difficult to separate lanthanum and cerium. Concentrated sulfuric acid is used for further dissolution to produce ceric sulfate, which is reprecipitated and burned to obtain cerium oxide. However, in practice, the leachate is a mixture of lanthanum sulfate and cerium sulfate, and the separation cost High, does not meet the conditions for industrialization

[0005] The existing technology lacks the overall idea of ​​completely separating silicon oxide, aluminum and rare earth in the waste rare earth polishing powder and transforming them into three products. Therefore, the production cost cannot be covered due to lack of full utilization of resources in process design and product design. , resulting in the inability to industrialize production, and can only stay in the laboratory stage. For example, when acid is used in the first stage, due to concerns about the cost of subsequent wastewater treatment, the amount of acid (sulfuric acid, hydrochloric acid, or nitric acid, etc.) cannot be excessively large, resulting in the first step The leaching rate of rare earth and aluminum is low and requires repeated leaching, the process route is long, the cost is high, and the additional impact caused by the insufficient amount of acid is that the content of rare earth in the leaching slag is too high, which not only causes waste of rare earth resources, but also causes leaching. The aluminum content in the slag is also too high, resulting in low silicon oxide content in the leached slag, which cannot be used and forms new solid waste