Method for replacement dissolution of bastnaesite (bastnasite)

Abstract

The invention belongs to separation of nonferrous metals and rare earth, and particularly relates to a method for replacement dissolution of rare earth bastnaesite and bastnasite. The technical scheme is that the method comprises the following steps of: performing low-temperature roasting on the bastnaesite and bastnasite at 400 to 500 DEG C; adding chlorhydric acid into the materials after the low-temperature roasting to dissolve out rare earth, and adding non-rare-earth substances which can be combined with fluorine (F) into the mixtures to combine with the F so as to obtain a rare earth chloride solution and solid fluoride, and performing solid-liquid separation; adding sulfuric acid into the obtained solid fluoride to roast and recover hydrofluoric acid; and performing water immersion on rare earth sulfate contained in dry residues after the recovery of the hydrofluoric acid to obtain a rare earth sulfate solution. According to the method, the fluorine ions which are dissolved out when the bastnaesite is dissolved with the chlorhydric acid are not combined with the rare earth, but are combined with other non-rare-earth substances, so that the fluorine cannot be formed into rare earth fluoride to influence the dissolution rate of the rare earth. By adopting the method, a process for defluorination and a process for directed complexation of cerium are not required, the aim of completely dissolving the bastnaesite as much as possible through one step by using the chlorhydric acid is fulfilled, the fluorine is changed into other high-added-value chemical raw materials and the rare earth can be recovered through one step, so that the rare earth recovery rate and the value of rare earth elements are high.

Description

Technical field: [0001] The invention belongs to the separation of rare earths of nonferrous metals, in particular to a method for replacing and dissolving bastnaesite and bastnaesite. Background technique: [0002] ①At present, the method steps of bastnaesite widely used in the industry to separate bastnaesite are: oxidation roasting, first-time optimal dissolution, filtration, filter residue alkali transfer, 10-12 times of water washing, filtration, second-time optimal dissolution, filtration, three-time optimization Dissolve and filter. The current process has the following problems and deficiencies: the roasted ore has undergone many times of optimal dissolution, alkali conversion, water washing, and filtration, and the process is long: due to the long process and repeated handling of materials, the labor intensity is high; the filter residue needs to be washed after alkali conversion. A large amount of fluorine-containing subtractive wastewater is produced, which serio...

AI Technical Summary

Problems solved by technology

The current process has the following problems and deficiencies: the roasted ore has undergone many times of optimal dissolution, alkali conversion, water washing, and filtration, and the process is long: due to the long process and repeated handling of materials, the labor intensity is high; the filter residue needs to be washed after alkali conversion. A large amount of fluorine-containing subtractive wastewater is produced, which seriously pollutes the environment, and the treatment cost is high and difficult; the current process has low utilization efficiency of equipment; alkali conversion needs to consume 0.28 tons of sodium hydroxide per ton ore, alkali The conversion cycle is 8-12 hours, and the alkali conversion equipment has been running for 24 hours to maintain a temperature of 100-120 degrees, which consumes a lot of electricity and steam. The alkali cake after alkali conversion needs a lot of water and flocculant to wash the alkali cake, which is costly and original Direct emission of fluorine to generate cerium fluoride is a product demanded by the market

The latest technology has the following problems and deficiencies: due to the combination of other impurities in the ore and cerium fluoride, the purity of cerium fluoride is not high and can only be used for smelting rare earth ferrosilicon and as a primary polishing powder raw material

The value of cerium fluoride is not high, and the market capacity is limited

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