Method of processing natural uranium chemical concentrate

FIELD: process engineering.

SUBSTANCE: invention relates to processing natural uranium chemical concentrate. Proposed method comprises concentrate leaching by nitric acid solution to obtain suspension, adding coagulant into suspension and suspension separation. Clarified solution is separated from residue and directed to extraction. Note here that polyacrylamide-based anion coagulant is used and suspension with said coagulant is subjected to permanent magnetic field effects. Coagulant concentration and duration of magnetic field effects are selected to ensure concentration of insoluble residue now exceeding 100 mg/l in clarified solution. In extraction from clarified solution, no antifloating emulsions are observed.

EFFECT: solution suitable for further extraction.

3 cl, 2 tbl

 

The invention relates to methods for processing chemical concentrates of uranium, which include the separation of the insoluble residue from solutions of uranyl nitrate (separation of suspensions) refining and extraction using tributyl phosphate (TBP) in a hydrocarbon diluent.

At dissolution (leaching) of chemical concentrates, natural uranium (NUC) formed in solutions of uranyl nitrate are insoluble residues (BUT), composed of hydrated oxides of iron, aluminum and other metals. In the process of extraction refining of uranyl nitrate BUT contribute to the formation of nerasseivayushchee emulsions (jellyfish) of the aqueous phase with the extractant - 30%TBP in a hydrocarbon diluent, which leads to disruption of the extraction process.

If extraction production is focused on the processing of solutions that do not contain a solid phase, insoluble residues should be removed from solutions. But often the leaching NUC form of a suspension, in which the insoluble residues form truefilter suspension, such suspension is difficult to divide into clarified water and residue.

In the method of processing of concentrated natural uranium oxides (RF Patent No. 2323883, IPC 01G 43/01(2006/01), publ. 10.05.2008) insoluble residues is separated from the solution of uranium filter the Oia or centrifugation after leaching in several stages, comprising preparing a concentrated solution of uranium (≈700 g/l) and dilute it in hot (which is unsafe) a weak solution of nitric acid.

A method of refining NUC leaching solution of nitric acid and separating the resulting slurry into solid and liquid components [Kozyrev, A.S., Sikerei YEAR, Ryabov A.S., Shamin, V.I., Mikhailov, N.A., Skuratov MV intensification of the processes of separation of highly concentrated solutions of uranyl and fine suspended solids. Bulletin of the Tomsk Polytechnic University. - 2007. - T. No. 3. - Page 16-19]. The method includes the introduction in the nitric acid solution of uranyl nitrate with a concentration of uranium 300-450 g/l of nitric acid 0.7 to 3.0 mol/l of coagulant cationic type brand FLOQULAT FL 45 in the amount of 100-200 mg/L. Then, the suspension is injected cationic flocculant brand FO 4140 in the amount of 1-10 mg/l After injection of coagulant and flocculant insoluble residues were separated from solution by filtration, got transparent solutions of uranyl nitrate, suitable for the extraction process. The method chosen for the prototype.

Continued research on the selection of coagulants and other methods of separation of suspensions, obtained by leaching NUC. Studies have shown that the content of the suspensions BUT in the uranyl nitrate solution should not exceed 100 mg/l - maximum is the amount of content, wherein in the extraction step is not observed education nerasseivayushchee emulsions.

The objective of the invention is the provision of separation of uranyl nitrate solution from the insoluble residue NUC with obtaining solution suitable for extraction.

The set task is solved by the fact that in the method for processing chemical concentrate of natural uranium, including the leaching solution of nitric acid to obtain a suspension, an introduction to the suspension of the coagulant, the separation of the suspension, separating the clarified solution from the residue and the direction of the solution on the extraction, the suspension is injected anionic coagulant based on polyacrylamide and suspension with coagulant effect of constant magnetic field, the concentration of coagulant and duration of the magnetic field is chosen from the condition of security in the clarified solution concentration of insoluble residues of not more than 100 mg/L.

The coagulant, which represents an anionic copolymer of acrylamide and sodium acrylate with a molecular mass of 12·106injected into the suspension to a concentration of 20-100 mg/L.

Suspension create a constant magnetic field with a strength of not less than 730 kA/m

The method is as follows.

In the method used anionic coagulant based on polyacrylamide coagulant (flocculant) FLOPAM brand'AN 923 PWG, p is establishe an anionic copolymer of acrylamide and sodium acrylate with a molecular mass of 12·10 6.

The suspension obtained from dissolution NUC in a solution of nitric acid, BUT contains - compounds of iron, aluminum and other metals. The suspension is injected anionic coagulant in a specified amount and affect the suspension with coagulant permanent magnetic field. Non-ionic and cationic coagulants have been ineffective (increase efficiency from combining the action of the coagulant and the magnet has not occurred).

Processed NUC with high content of iron and aluminium, close to the limit values given in ASTM C 967-02 for uranium ore concentrate. The initial suspension of uranyl nitrate was prepared by dissolving NUC in a solution of nitric acid. The concentration of uranyl nitrate in the resulting suspensions in terms of uranium ranged (203,1-KZT 205.7) g/l, the concentration of free nitric acid in the interval (104,1-112,5) g/l, iron 30-33 g/l, aluminum 15-16 g/L. HO was about 0.5% of the solution volume.

Conducted two series of experiments:

in the first series of the influence on the clarification of the suspension of the coagulant and the magnet and the length of their impact on the suspension;

in the second series selected the optimum concentration of coagulant.

Held the first of a series of 4 experiments.

In experiment 1 investigated the separation of suspensions in the process of its sludge. Immediately after the dissolution NUC received the ing the suspension was divided into six equal portions of 50 ml each. Then immediately after separation (i.e., without exposure of the suspension) and at set time intervals (5, 10, 15, 20 and 25 minutes of exposure) of each glass were selected from the top 25 ml of suspension, the sample was mixed and measured the optical density of the sample fotoelektrokalorimetry.

In experiment 2 investigated the separation of the suspension after injecting coagulant. Received from dissolution NUC suspension, divided into six portions, added an anionic coagulant type brand AN-923 to its concentration in suspension 40 mg/L. Then spent measuring the optical density of six samples obtained slurry immediately after the introduction of the coagulant and at set time intervals (5, 10, 15, 20 and 25 minutes), selecting from each glass on top of 25 ml of suspension, mixing it and measuring the optical density of the sample fotoelektrokalorimetry.

In experiment 3 investigated the separation of suspensions under the influence of a permanent magnet. Six servings suspension was affected by high-energy permanent magnets Nd-Fe-B, creating a magnetic field in a suspension of not less than 730 kA/m (magnets were installed under the bottom of the glass jars, which were portions of the suspension). At set time intervals (5, 10, 15, 20 and 25 minutes) from each glass top samples were taken suspension and measured their optical density.

In experiment 4 investigated the separation of suspensions under the jurisdiction of coagulant and the impact of a permanent magnet. To do this in six servings of suspension introduced the anionic coagulant type brand AN-923 to its concentration in suspension 40 mg/l and then conducted operations as in experiment 3.

Table 1 shows the results of measuring the optical density of the samples to characterize the degree of clarification of the suspension, depending on the time of exposure to the coagulant and the magnet on the suspension (on the duration of exposure of the suspension to the measurements).

Table 1
The sample numberThe duration of exposure of the suspension, minThe optical density of the sample
Experience 1Experience 2Experience 3Experience 4
100,870,860,890,87
250,850,830,710,49
3100,83070 0,560,22
4150,800,590,430,15
5200,740,480,340,13
6250,720,350,280,11

As can be seen from table 1, when exposed to a suspension of coagulant and magnet depending on the time of exposure to the clarification of the suspension occurs in 2-4 times more efficiently compared with the impact of only one of the coagulant and 1.5-3 times in comparison with the impact of only one magnet.

In the second series of experiments after complete dissolution NUC obtained suspension was divided into several equal portions, in which the coagulant is introduced to concentrations respectively 20, 40, 60, 100, 200, 500 mg/l At all the portions affected by the magnet, as in experiments 3 and 4 of the first series.

The results of the experiments of the second series are shown in table 2.

The concentration of insoluble residue 100 mg/sootwetstwuet optical density clarified solution of 0.18.

As can be seen from table 2, specification clarification suspension (optical density of 0.18, corresponding acceptable for extraction concentration BUT equal to 100 mg/l) when introduced into the suspension of the coagulant and the impact on the suspension of the permanent magnet Nd-Fe-B, creating a magnetic field 730 kA/m, occurs when the concentration of the coagulant 20 mg/l and reaction time 25 min Increase in the concentration of coagulant to 100 mg/l reduces the duration of clarification of the suspension to a predetermined value to 7.5 minutes. Further increase in the concentration of the coagulant suspension does not lead to a significant acceleration of clarification suspension.

After separation of the suspension into clarified water and a residue, the residue was separated from the solution by filtration. The solution is sent to extraction. When the extraction was not observed education nerasseivayushchee emulsions.

1. Method for processing chemical concentrate of natural uranium, including the leaching solution of nitric acid to obtain a suspension, an introduction to the suspension of the coagulant, the separation of the suspension, separating the clarified solution from the residue and the direction of the solution on the extraction, characterized in that the suspension is injected anionic coagulant based on polyacrylamide and suspension with coagulant effect of constant magnetic field, when this end is the filtration coagulant and duration of the magnetic field is chosen from the condition of security in the clarified solution concentration of insoluble residues of not more than 100 mg/L.

2. The method according to claim 1, characterized in that the coagulant, which represents an anionic copolymer of acrylamide and sodium acrylate with a molecular mass of 12·106injected into the suspension to a concentration of 20-100 mg/L.

3. The method according to claim 1, characterized in that the suspension creates a magnetic field of not less than 730 kA/m



 

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