I. V. Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials of the Russian Academy of Sciences Kola Science Center (ICTREMRM KSC RAS)

L. G. Gerasimova, Divisional Manager, e-mail: gerasimova@chemy.kolasc.net.ru

A. I. Nikolaev, Deputy Director

Manufacturing of permanent magnets involves wasting metals in the form of powder and platelets contaminated by organic compounds. Much of the scarce REM is lost with the wastes. The magnet-process waste investigated in this work was a powder consisting for the part of neodymium and iron and much less of samarium and cobalt. The waste composition has been examined to develop a regime of their dissolution in 34–36% H₂SO₄. The resulting precipitate consisted of a sulphate rare-earth concentrate and an ironcontaining solution. The dissolution kinetic has been studied and optimal conditions of components separation have been determined. The solid phase was washed on a filter with hot water and the rinsing water was joined to the liquid phase. The washed-out precipitate was a crystal salt of neodymium(III) sulphate Nd₂(SO₄)₃·8H₂O admixed with samarium(III) and iron(II) sulphates. The sulphuric acid solution mostly contained iron(II) with trace amounts of cobalt and REM. Goethite was extracted from ironcontaining sulphuric acid solutions by using hydrolysis; next it was calcined to obtain iron oxide pigments and welding components. To improve separation of the main components, the processes of waste dissolution and iron vitriol crystallization were conducted in one stage, without intermediate separating of the REM sulphate precipitate. The resulting sulphate mixture was dissolved in water. The solution was subjected to hydrolysis to extract iron(III) as a hydroxide precipitate. The lanthanides remained in solution from which they can be isolated using precipitation. Efficient methods for converting REM sulphates to fluoride compounds or hydroxides are proposed.

1. Gerasimova L. G., Nikolaev A. I., Shevyreva E. V., Okhrimenko R. F. Otkhody proizvodstva spetsialnykh magnitov — istochnik polucheniya soedineniy RZM. Dokl. mezhdunar. simpoziuma. Strategiya ispolzovaniya i razvitiya syrevoy bazy redkikh metallov Rossii v 21 veke (Special magnets` production waste — the source of obtaining the rare earth metals compounds. Report of an International Symposium. Strategy of using and development of Russian raw material base of rare metals in the ХХI century). Moscow : VIMS, 2000. Vol. 2. pp. 87–89.

2. Gerasimova L. G., Nikolaev A. I., Maslova M. V. et al. Otkhody proizvodstva postoyannykh magnitov — syre dlya polucheniya soedineniy RZE. Tez. dokl. XIV Mezhdunarodnaya konferentsiya po postoyannym magnitam (Constant magnets` production waste — the raw materials for obtaining the rare earth elements compounds. Thesis of a report from XIV International Conference on constant magnets). Moscow, 2003. pp. 198–199.

3. Bolshakov K. A. Khimiya i tekhnologiya redkikh i rasseyannykh elementov (Chemistry and technology of rare and scattered elements). Moscow, Vysshaya shkola, 1978. Vol. 3. 360 p.

4. Lidin R. A., Andreeva L. L., Molochko V. A. Spravochnik po neorganicheskoy khimii (Reference book of the inorganic chemistry). Moscow : Khimiya, 1987. 318 p.

5. Belenkiy E. F., Riskin I. V. Khimiya i tekhnologiya pigmentov (Chemistry and technology of pigments). Moscow, Khimiya, 1974. 656 p.

6. Evdokimov A. V., Bykov E. A., Kleshchev D. G. Lakokrasochnye materialy i ikh primenenie – Russian Coatings Journal. 1994. No. 4. pp. 31–32.

7. Agafonov G. I., Kleshchev D. G., Tolchev V. Yu. et al. Lakokrasochnye materialy i ikh primenenie – Russian Coatings Journal. 1999. No. 7/8. pp. 41–43.

8. Mukhlenov I. P. Tekhnologiya katalizatorov (Technology of catalysts). Leningrad, Khimiya, 1979. 324 p.

9. Stepanov E. G. Dezintegratornaya tekhnologiya v proizvodstve svezhikh i pererabotke dezaktivirovannykh katalizatorov neftekhimicheskikh protsessov : dis. … dokt. tekhn. nauk (Disintegrator technology in the production of fresh catalysts and processing of deactivated catalysts of petrochemical processes : Thesis of inauguration dissertation of Doctor of Engineering Sciences). Ivanovo : IGKhTU, 2005. 38 p.

10. Gerasimova L. G. Pigmenty i napolniteli iz prirodnogo titansoderzhashchego syrya i tekhnogennykh otkhodov (Pigments and loadings from the natural titaniferous raw materials and anthropogenic wastes). Apatity : KSC RAS, 2001. 100 p.

11. Larionov V. P., Zorin E. E. Svarochnoe proizvodstvo – Welding Industry. 2003. No. 10. pp. 42–44.