A method for preparing high-purity selenium by a crude selenium wet method

Abstract

The invention discloses a method for preparing high-purity selenium through wet-process purification of crude selenium. The method comprises the following steps: a, slowly adding crude selenium into a sodium hydroxide solution at a uniform speed, wherein a liquid-solid mass ratio is 3-5: 1, reaction time is 1.5 to 2 h and complete dissolving and leaching of crude selenium are ensured; b, adjusting a pH value to 6.5 to 7.0 by using hydrochloric acid, adding sodium sulfide, then carrying out uniform mixing under stirring and carrying out standing to remove impurities; c, adjusting the pH value of an alkaline leaching solution obtained in the previous step to 1.0 to 1.5, carrying out ageing for 2.5 to 3 h and then carrying out solid-liquid separation after complete precipitation of selenium; d, oxidizing leached fine selenium by using a sodium sulfite solution, carrying out sufficient stirring and then successively carrying out standing and filtering so as to obtain a selenium-rich solution; and e, slowly adding sulfuric acid into the selenium-rich solution, and successively carrying out acidification and reduction, filtering, washing and drying so as to prepare high-purity selenium. The method provided by the invention realizes preparation of high-purity selenium through two-step leaching and wet-process purification of crude selenium, shortens the purification flow of selenium, improves recovery rate, reduces production cost and mitigates limitation of large-scale production.

Description

technical field

[0001] The invention relates to the field of high-purity rare metal preparation, in particular to a process for preparing high-purity selenium by wet purification of crude selenium. Background technique

[0002] At present, Germany, Chile, Japan, etc. mainly produce high-purity selenium in foreign countries, but the key technology of their purification process is strictly kept secret, and it is difficult to find relevant reports from published literature. Domestic selenium purification processes mainly include oxidation-adsorption precipitation method, neutralization-hydrolysis combined method, and ion exchange-extraction method. These methods have problems such as long process flow, high cost, serious pollution, and low recovery rate, making it difficult to produce on a large scale. Chinese patent application CN102627262 (application number 201210129139.7) "Method for extracting high-purity selenium from by-products of high-temperature scarlet production" di...

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