INVESTIGATION OF ELECTROKINETIC AND ELECTROCHEMICAL PHENOMENA IN PHOSPHOGYPSUM IN SOLVING GEOECOLOGICAL PROBLEMS   

V. Yu. Shigaev^1,*, D. A. Shelepov^1,**,  A. E. Khokhlov^1,***,  I. A.Merenov^2,****

¹ Chernyshevsky Saratov National Research State University,
ul. Astrakhanskaya, 83, Saratov, 410012 Russia
²Vavilov Saratov State Agricultural University, Teatral'naya pl., 1, Saratov, 410012 Russia

^*Email: vital1969_08@mail.ru,
^**Email:shelepov@renet.ru 
^****Email:profsnab_hae@mail.ru,
^****Email: ivan_merenov@mail.ru

Large-capacity phosphogypsum dumps stored in the open air exert an extremely negative impact on ecosystems and human health. Therefore, their disposal or reuse is an important and urgent task. Currently, there are many studies (both Russian and foreign) dedicated to phosphogypsum processing by a direct current (DC) electric field, but many issues related to such process are not covered widely enough. Thus, the purpose of this paper is to study the electrokinetic and electrochemical processes developing in phosphogypsum after its exposure to a DC electric field. The paper discusses various options of initial sample saturation with distilled water and their subsequent electrical processing in a geoelectrochemical device developed at the Department of Geophysics, Chernyshevsky Saratov State University (Russian Federation patent no. 47365,  August 27, 2005). The device consists of a cylindrical plastic case with access holes for monitoring physical and chemical properties. Inert graphite electrodes are embedded at the ends of the housing and are supplied with a direct electric current. We determined the sequence and volume of liquids released at the cathode and anode depending on the direct current transmission time, redox reactions occurring at the electrodes, mineralization of the electrolyte that fills the pores, as well as the method of dissolving the samples. Abnormally high contents of Ce (2.5 times greater than its initial concentration), Nd (9.2 times), Y (5.3 times), and Fe (6.6 times) were recorded in the cathode section of the device. Mineral and petrographic, chemical, X-ray and other studies also have recorded changes in the composition and structure of the samples under study. It is important to take these data into account when choosing the method of electrical treatment used to extract various metals from waste. Electrical surface processes (electric osmosis, electrophoresis etc.) in the studied samples are proposed to be used in solving a number of applied geoecological problems, particularly, the selection of coagulating substances introduced as additives for obtaining phosphogypsum-based composite materials.

Keywords: phosphogypsum, constant electric current, current transmission time, electrokinetic and electrochemical phenomena, changes in the structure and composition of samples

REFERENCES

1. Belobrov, V.P., Grebennikov, A.M., Kulenkamp, A. Yu., Ryashko, A.I., Torochkov, E.L. Osobennosti biologicheskoi rekul'tivatsii otvala fosfogipsa Balakovskogo filiala AO “Apatit” [Features of biological reclamation of the phosphogypsum dump at the Balakovo branch of JSC “Apatit”]. Ekologicheskii vestnik Severnogo Kavkaza, 2015, no 1, pp. 20-25. (in Russian).
2. Bolshakov, V.D. Teoriya oshibok nablyudenii [Theory of observation errors]. Moscow, Nedra Publ., 1983, 223 p. (in Russian)
3. Vodyanitskii, Yu.N., Mineev, V.G. Razlichie v znacheniyakh pH gidromorfnykh pochv pri polevom i laboratornom analizakh [Difference in pH values of hydromorphic soils in field and laboratory analyses]. Vestnik Moskovskogo universiteta. Seriya 17: Pochvovedenie, 2016, no 1, pp. 3-9. (in Russian).
4. Goncharova, L.V. Osnovy iskusstvennogo uluchsheniya gruntov [Fundamentals of artificial soil improvement]. Moscow, MGU Publ., 1973, 376 p. (in Russian)
5. Dir, U.A., Howie, A.R., Zusman, J. Porodoobrazuyushchie mineraly [Rock-forming minerals]. Vol. 1. Orthosilicates and ring silicates. Moscow, Mir Publ., 1965, 404 p. (in Russian)
6. Korolev, V.A. Teoriya elektropoverkhnostnykh yavlenii v gruntakh i ikh primenenie [Theory of electrosurface phenomena in soils and their application]. Moscow, Sam polygraphist Publ., 2015, 468 p. (in Russian)
7. Ivanitskii, V.V., Klassen, P.V., Novikov, A.A., Stonis, S.N., Evenchik, S.D., Yakovleva, M.E. Fosfogips i ego ispol'zovanie [Phosphogypsum and its use]. Moscow, Khimiya Publ., 1990, 224 p. (in Russian)
8. Merenov, I.A., Shigaev, V.Yu., Khokhlov, A.E. Issledovanie okislitel'no-vosstanovitel'nykh svoistv fosfogipsa pri vzaimodeistvii s polem postoyannogo elektricheskogo toka [Investigation of redox properties of phosphogypsum in interaction with a direct electric current field]. Proc. VI Intern. Sci. Conference, Yekaterinburg, L-Zhurnal Publ., 2017, pp. 52-55. (in Russian)
9. Nikitina, N.G., Grebenkova, V.I. Obshchaya i neorganicheskaya khimiya [General and inorganic chemistry]. Part 1. Theoretical fundamentals. Moscow, Yurait Publ., 2018, 211 p. (in Russian)
10. Okorokov, V.V. Vliyanie fosfogipsa na povedenie strontsiya i drugikh tyazhelykh metallov pri melioratsii solontsov [Influence of phosphogypsum on the behavior of strontium and other heavy metals in land reclamation of solonetzes]. Proc. V International Scientific Ecological Conference, Krasnodar, Kuban State Agricultural Univ., 2017, pp. 107-116. (in Russian)
11. Osipov, V.I. Vnutrikristallicheskoe razbukhanie glinistykh mineralov [Intraclastic swelling of clay minerals]. Geoekologiya, 2011, no. 5, pp. 387-398. (in Russian)
12. Plekhanova, I.O., Aimaletdinov, R.A. Vliyanie otkhodov proizvodstva fosfornykh udobrenii na ekologicheskoe sostoyanie blizlezhashchikh territorii [Impact of wastes from the production of phosphorus fertilizers on the ecological state of nearby territories]. Problemy agrokhimii i ekologii, 2014, no 1, pp 50-54. (in Russian)
13. Prostov, S.M., Pokatilov, A.V., Rudkovsky, D.I. Elektrokhimicheskoe zakreplenie gruntov [Electrochemical stabilization of soils]. Tomsk, Tomsk University Publ., 2011, 294 p. (in Russian)
14. Putikov, O.F. Osnovy teorii nelineynykh geoelektrokhimicheskikh metodov poiskov i razvedki [Fundamentals of the theory of nonlinear geoelectrochemical methods of prospecting]. St. Petersburg, Plekhanov SPGGI Publ., 2008, 534 p. (in Russian)
15. Samonov, A.E., Borisovskii, S.E. Netraditsionnaya bezotkhodnaya pererabotka apatitovogo kontsentrata i fosfogipsa [Non-traditional waste-free processing of apatite concentrate and phosphogypsum]. Ekologiya i promyshlennost' Rossii, 2005, no 7, pp. 8-11.  (in Russian)
16. Samonov, A.E., Melent'ev, G.B., Van'shin, Yu.V. Ekologicheskoe vozdeistvie khranilishch fosfogipsa i piritnykh ogarkov na sredu obitaniya i perspektivy ikh kompleksnoi pererabotki s polucheniem vysokolikvidnoi tovarnoi produktsii [Environmental impact of phosphogypsum and pyrite cinder storage facilities on the environment and prospects for their complex processing to obtain highly liquid marketable products]. Ekologiya promyshlennogo proizvodstva, 2008, no 2, pp. 65-76. (in Russian)
17. Semenov, A.A. Tekhnologiya razdeleniya redkozemel'nogo kontsentrata, vydelennogo iz fosfogipsa s polucheniem dioksida tseriya i oksida neodima [Technology of separation of rare earth concentrate extracted from phosphogypsum  to produce cerium dioxide and neodymium oxide. Cand. Sci. (Technical) Disseration. Moscow, 2016, 126 p. (in Russian)
18. Soldatkin, S.I., Khokhlov, A.E. Problemy ispol'zovaniya fosfogipsa v dorozhnom stroitel'stve [Problems of using phosphogypsum in road construction]. Nedra Povolzh'ya i Prikaspiya, 2019, no. 97, pp. 58-61. (in Russian)
19. Shigaev, V.Yu. Geoelektrokhimicheskie issledovaniya geologicheskoi sredy [Geoelectrochemical studies of the geological environment]. Saratov, Chernyshevsky State University Publ., 2012, 184 p. (in Russian)
20. Shigaev, V.Yu., Shelepov, D.A., Merenov, I.A. Izmenenie porovogo prostranstva otkhodov pererabotki fosforsoderzhashchego syr'ya v fosfornuyu kisloty pri ikh elektroobrabotke [Changing the pore space of waste from processing of phosphorous-containing raw materials into phosphoric acid during their electrical processing]. Nedropol'zovanie XXI vek, 2019, no. 2, pp. 154-159. Available at: http://naen.ru/journal_nedropolzovanie_xxi/arkhiv-zhurnala/2019/2_90_let_geologicheskikh_pobed/ (accessed 03.08.2020) (in Russian)
21. Ablyeva, I.Yu., Plyatsuk, L.D., Kotsyuba, I.G. Features of the process of processing sludge by chemical method using phosphogypsum. Bulletin of Zhytomyr State Technological University. Series: Technical Sciences, 2013, no. 4(67), pp. 84-88.
22. Pikarenya, D.S., Orlinskaya, O.V., Chushkina, I.V., Gapich, G.V., Isaenko, R.V. New ways of processing phosphogypsum as environmentally hazardous raw materials. Construction. Materials science. Engineering. Series: Life Safety, 2013, no. 71(1), pp. 179-186.
23. Rabah, M.A., Nassif, N., Abdul Azim, A.A. Electrochemical wear of graphite anodes during electrolysis of brine. Carbon, 1991, no. 29(2), pp. 165-171.
24. Schaad, W. Praktische Anwendungen der Electro-Osmose im Gebiete des Grundbaues. Die Bautechnik, 1958, no. 35(6), pp. 210-215.
25. Walawalkar, М. Extraction of rare earth elements from phosphogypsum (fertilizer production by-product:) dis. master of applied science. Toronto, 2016.
26. Wang, M., Tang, Y., Anderson, W.N.C., Jeyakumar, P., Yang, J. [Effect of simulated acid rain on fluorine mobility and the bacterial community of phosphogypsum]. Environmental Science and Pollution Research, 2018, vol. 25, pp. 15336–15348. Available at: https://pubmed.ncbi.nlm.nih.gov/29564699/ (accessed 03.08.2020)