Method for decomposing bastnaesite through calcification transformation-leaching

Abstract

The invention belongs to the technical field of rare earth metallurgy, and particularly relates to a method for decomposing bastnaesite through calcification transformation-leaching. The method comprises the following the steps of: carrying out activation pretreatment on rare earth ore concentrate, carrying out calcification transformation pretreatment on the activated ore, carrying out acid leaching on transformed slag, extracting rare earth chloride fine liquid to finally obtain a solution with thorium-iron slag and cerium chloride or lanthanum chloride or praseodymium chloride or neodymium trichloride, and efficiently separating valuable elements such as a rare earth element, a fluorine element and a thorium element. According to the method, energy consumption and fuel consumption are reduced, and when the low-temperature baking is carried out below 500 DEG C, only carbonates are decomposed, so that the reaction activity of the rare earth ore concentrate is supplied, and simultaneously the waste of fluorine resources and the emission pollution are avoided; and therefore, the method belongs to a green clean technology.

Description

[0001] technical field [0002] The invention belongs to the technical field of rare earth metallurgy, in particular to a method for decomposing bastnaesite by calcification transformation-leaching. Background technique [0003] Bastnaesite is an important rare earth resource in the world. The mineral is mainly produced in Sichuan and Shandong in China and Mountain Pass in the United States. Bastnaesite, which is rich in Sichuan, Shandong and other places, is the second largest rare earth resource in my country, and rare earths exist in the form of fluorocarbonates. After beneficiation, the concentrate grade can reach 50% to 70%, and the concentrate generally contains 8% to 9% fluorine. At present, the industrial processes for decomposing bastnaesite to extract rare earths include acid method and alkali method. [0004] Among them, the acid leaching method includes hydrochloric acid and sulfuric acid decomposition methods. In the 1990s, bastnaesite in Sichuan area of...

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Problems solved by technology

The above process has the advantages of short process flow, small investment, and low production cost of cerium products, but there are problems such as discontinuous process, low product purity, difficult recovery of thorium and fluorine dispersed in slag and waste water, and pollution to the environment.

For example, Chinese Patent (Application No.) 200410031180.6 discloses a method for decomposing bastnaesite with hydrochloric acid. In this method, after oxidizing and roasting bastnaesite, sodium hydroxide is used to remove fluoride, and hydrochloric acid is optimally soluble-completely soluble. In this method, hydrogen The consumption of sodium oxide is large, and a large amount of alkaline wastewater is produced at the same time

Chinese patents (application numbers) 2004100031179.3 and 200410070199.1 disclose a method for decomposing bastnaesite by sulfuric acid leaching. These methods all have defects such as high energy consumption, large amount of waste water and serious pollution, and serious waste of fluorine resources

The impurities in the concentrate will significantly affect the product quality and reduce the recovery rate of rare earths. Therefore, the concentrate must be removed by chemical beneficiation before decomposing impurity minerals such as fluorspar, but the rare earths will lose 2%-5% during the beneficiation process

The process of decomposing Baotou rare earth concentrate by sodium hydroxide method is relatively mature, but it is rarely used in domestic large-scale factories because of the disadvantages of high grade rare earth concentrate, impurity removal treatment before decomposition and low recovery rate of rare earth.

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