Research and development of technology and equipment for electrodialysis of solutions of tungstate and sodium sulfate with alkali and acid regeneration

Relevance

Kazakhstan has a number of tungsten deposits, which, when used, make it one of the three world leaders in the production of this metal. Tungsten production technologies are accompanied by the formation of a large volume of sodium tungstate solutions containing a number of impurities. Purification of solutions from impurities requires neutralization with inorganic acids, accompanied by the formation of a large amount of chloride and sulfate effluents sent to the dump.

The use of membrane electrodialysis technologies proposed in the project will reduce the amount of wastewater discharged, extract tungstic acid from a solution of sodium tungstate, followed by the production of tungsten oxide. Also, electrodialysis of sodium sulfate solutions formed in a number of non-ferrous metal raw materials processing processes will allow to regenerate alkali, as well as extract sulfur from raw materials in the form of commercial sulfuric acid, which is in constant demand in a number of industries.

Purpose

Research and development of electrodialysis technology and equipment:

– solutions of sodium tungstate with alkali regeneration and reduction of the consumption of inorganic acids and the amount of sulfate-chloride effluents;

– solutions of sodium sulfate with the regeneration of alkali and sulfuric acid, which reduces the cost of processing sulfide concentrates of non-ferrous metals and increases the extraction of sulfur into commercial acid.

Expected and achieved results

In 2023: Sketches of electrodialysts and installation diagrams, test results. Indicators of electrodialysis processes of solutions of sodium sulfate and sodium tungstate according to the results of laboratory studies.

Sketches of electrodialysts and installation diagrams were made. According to the experimental plan, experiments were conducted in a 3-section laboratory apparatus with a stainless steel cathode and a platinized anode with dimensions 50*100*1 , with MK-40 and MA-40 membranes. The Na2SO4 solution was prepared from a reagent of the brand C.D.a,, and a volume of 250 ml was poured into the middle compartment of the dialyzer between the anion exchange and cation exchange membranes. 150 ml of distilled water was poured into the anode and cathode spaces with the addition of 1 ml of sulfuric acid or NaOH solutions with a concentration of 100 g/l. According to the results of the experiments, the current output dependences were obtained: for NaOH y = -1,9695x2 + 13.119x + 74.047 with an approximation coefficient R2 = 0.9402; for H2SO4 y = -1,7652x2 + 12.453x + 71.973 with an approximation coefficient R2 = 0.9597.

The Excel application has developed a program for the primary processing of experimental data on electrodialysis of sulfate and tungstate solutions. A series of experiments was carried out using the method of planning experiments with Na₂SO₄ solutions of various concentrations, the methodology was worked out, the dependences of electrodialysis parameters in stationary mode without circulation of solutions were obtained, which allows predicting the duration of the process until the complete conversion of the initial solutions and calculating the number of stages of electrodialysis in flow mode. It was revealed that the main indicator of the electrodialysis process of sodium sulfate solutions, determined by the density of solutions and controlled by Faraday's law, is the degree of Na2SO4 conversion as the ratio of the amount of salt in the initial solution entering the electrodialyzer to the amount of salt in the final solution. The dependences of the degree of conversion of sodium sulfate on the initial concentration of the solution, the current density during electrodialysis and the duration of the process are described by polynomials of the second degree. A series of experiments on the electrodialysis of sodium tungstate solutions to obtain yellow tungstic acid and tungsten trioxide was carried out.

In 2024: Indicators of electrodialysis processes of sodium sulfate and sodium tungstate solutions based on the results of large-scale laboratory studies.

In 2025: Technological regulations for processing sodium sulfate and tungstate solutions, hardware and technological scheme

Research team members with their identifiers (Scopus Author ID, Researcher ID, ORCID, if available) and links to relevant profiles

1. Baimbetov B.S. – Scopus Author ID: 57144547400, Researcher ID: AAA-3483-2020, ORCID: 0000-0003-4442-5038;

2. Moldabaeva G.Zh. – Scopus Author ID: 57215536255, Researcher ID: AAG-8592-2019, ORCID: 0000-0002-3716-213X;

3. Vasin K.A.– Scopus Author ID: 57204209616, ORCID: 0000-0002-4257-2061;

4. Tazhiev E.B.– Researcher ID: AAA-3431-2020, Scopus Author ID: 56982938300, ORCID: 0000-0003-1955-8584;

5. Taimasova A.N.. – ScopusAuthor ID: 56178144700, Researcher ID: DXX-3245-2022, ORCID: 0000-0002-1351-5068;

6. Dzhumankulova S.K.– Scopus Author ID:2922b0898454, Researcher ID: ААА-3426-2020, ORCID: 0000-0001-5379-0526;

7. Adilzhan Zh. – Researcher ID: ABC-8483-2021, ORCID: 0000-0003-0125-0098;

8. Dauletbakova A.A.– ORCID: 0000-0001-6220-6387;

9. Baisultanov R.M.– ORCID ID 0009-0008-7966-6177

List of publications with links to them

1 article has been published.  (https://www.mdpi.com/2227-9717/12/1/77 )