# Fileset

[REPM2025_P2-34_Kirillov.pdf](https://mdr.nims.go.jp/filesets/909dfebf-30be-4df1-8829-68c4171eaa20/download)

## Creator

Evgenii Kirillov, Sergey Kirillov, Grigory Bunkov, Denis Smyshlyaev, Aslanbek Taukin

## Rights

[Creative Commons BY Attribution 4.0 International](https://creativecommons.org/licenses/by/4.0/)

## Other metadata

[Nitric acid technology for processing magnetic production waste](https://mdr.nims.go.jp/datasets/c623a42e-bd84-490a-80df-76535be8562f)

## Fulltext

Презентация PowerPointEvgenii Kirillov1, Sergey Kirillov1, Grigory Bunkov1, Denis Smyshlyaev1, Aslanbek Taukin1At present, conventional methods for processing magnetic waste (both “dry” and water” technologies)are not always applicable under the conditions of industrial rare-earth element production. Our workproposes a novel approach to magnet recycling using nitric acid that can be implemented at existingindustrial sites.051015200 100 200 300 400 500 600n, molTemperature, ℃Fe(NO3)3(a) Nd(NO3)3(a) O2(g) NO2(g) Fe2O3(s)Nd2O3(s) H2O(a) H2O(g) HNO3(a)Fig.1. Computer simulation of the system1Department of Rare metals and Nanomaterials, Institute of Physics and Technology, Ural Federal University, Mira 21, 620062, Yekaterinburg, Russiae-mail:e.v.kirillov@urfu.ruNitric acid technology for processing magnetic production wasteFig.2. Thermal Decomposition of Iron Nitrate unit Fig.3. Nitric Acid Regeneration unitBased on the simulation data, it can beconcluded that as the temperatureincreases, the amount of Fe(NO₃)₃decreases, indicating itsdecomposition. At the same time, thequantities of gaseous oxygen (O₂) andnitrogen dioxide (NO₂) rise markedly,which is typical for the thermaldecomposition of nitrates. Theformation of iron oxide as Fe₂O₃ in the130 °C–180 °C range—and itsunchanged level above 180 °C—indicates that this is its final form underthe conditions studied.Following a series of laboratory investigations, baseline data were obtained for the design ofindustrial-scale installations for magnet recycling and nitric acid regeneration.4NO + 2O2 = 4NO2 (1)4NO2 + O2 + 2H2O = 4HNO3 (2)The nitric-acid dissolution unit forpermanent-magnet production waste operateson the principle of continuously and selectivelytransferring iron from the leach liquor into theoxide phase. To this end, the facility shown inFigure 2 is employed, fully meeting therequirements of the process.In order to minimize costs, a nitric acidregeneration unit, as shown in Figure 3, has beenproposed.In addition to regenerating nitric acid, the unitshown in Figure 2—whose operation is basedon Reactions 1 and 2also simultaneously produces technical-gradecrystalline boric acid with a yield of at 70 %.