Method for extracting high-purity uranium, thorium and mixed rare earths from excellent molten slag

Abstract

The invention discloses a method for extracting high-purity uranium, thorium and mixed rare earths from excellent molten slag, which comprises the following steps: acid pickling: adding urdite excellent molten slag into an acid solution, stirring at normal temperature for some time, clarifying, and carrying out siphoning on the supernate to obtain a solution containing uranium, thorium and rare earths; and (2) pressure filtration and water washing: adding the slurry subjected to supernate siphoning into a plate and frame filter press, carrying out pressure filtration until no solution flows out, merging the filtrate with the supernate in the step (1), washing the filter residue of the plate and frame filter press with water until the pH value of the filtrate is 2.0-3.0, and merging the water washing solution with the supernate in the step (1) to obtain a clarified water solution containing uranium, thorium and rare earths and a filter residue. The method is simple in technical process, only adopts liquid-liquid extraction and uses one organic extractant, and thus, can easily implement large-scale production. The chemical materials are common and are low in consumption. The method can effectively extract single uranium and thorium products and mixed rare earths from the urdite excellent molten slag, and the overall yield is up to 90% above. The method is environment-friendly, and has obvious social benefit and economic benefit.

Description

【Technical field】 [0001] The invention relates to the technical field of hydrometallurgy, in particular to the technical field of a method for extracting high-purity uranium, thorium and mixed rare earths from high-quality molten slag. 【Background technique】 [0002] Melting slag is the solid waste after the main rare earth elements are extracted from monazite. It is often piled up in the environment in the form of waste. Because it contains a large amount of uranium, thorium and other radioactive elements, it brings great harm to the human living environment. [0003] The main components of excellent molten slag are uranium, thorium, hydroxides of rare earths, a small amount of silicate and insoluble minerals. After leaching, separation and enrichment, uranium, thorium, titanium and mixed rare earths can be obtained. The extraction techniques currently adopted include: : (1) Acid leaching-liquid-liquid extraction technology, acid leaching systems include sulfuric acid solut...

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Problems solved by technology

For example, CN101012502A publicly reported the method of ultrasonic nitric acid solution leaching-TBP kerosene solution extraction method for separating and enriching uranium-thorium mixture and rare earth in excellent molten slag. Because of the ultrasonic leaching-extraction technology, the process flow was shortened and the leaching process was improved. and extraction speed and efficiency, but the final product is a mixture of uranium and thorium, which still needs further separation and purification, and has low industrial utilization value, and the acid consumption of nitric acid system leaching is large, the cost is high, and there is no market competitiveness; another example is the public report of CN104278165A A method for recovering thorium, uranium and rare earths from monazite smelting acid-insoluble slag, that is, sulfuric acid leaching, uranium extraction with tertiary amine extraction agent, thorium extraction with primary amine extraction agent, alkali precipitation to obtain rare earth mixture products

Although this method can simultaneously extract plutonium, uranium and rare earth mixture products from monazite smelting acid insoluble slag, the use of two organic extractants in the same process will make the solvent management system more complicated, affect the extraction effect, and produce amine extractants (such as primary amine N1923) manufacturers stop production, it is difficult to buy

(2) Acid leaching-ion exchange-liquid-liquid extraction technology, such as CN103014359A and CNCN103014333A publicly reported the method for separating and recovering uranium, thorium and rare earth from monazia slag, namely adopting low temperature, low acid leaching, ion exchange resin extraction Uranium, di(2-ethylhexylphosphoric acid) to extract thorium, and primary amine to extract rare earths. This method can also obtain uranium, thorium and mixed rare earths at the same time, but the process is complicated, and ion exchange and liquid-liquid extraction are used at the same time. Two different types of extraction solvents are used, and the solvent management system is more complicated

(2) Step-by-step leaching-precipitation technology, such as CN102154560A publicly reported a method for step-by-step leaching-precipitation separation and extraction of uranium and thorium, that is, alkaline leaching-precipitation to extract uranium, acid leaching and precipitation to extract thorium, the method Although uranium and thorium products can be obtained separately, the purity is not high, and products such as titanium and rare earth cannot be extracted at the same time

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