A manganese-vanadium concentrate precipitate containing V2O5 and MnO2 is formed on the stage of wastewater ozone treatment in sodium technology of vanadium-containing converter metallurgical slag processing. Vanadium content of the slag changes between 4 and 15 % wt and manganese content changes between 62 and 75,5 % wt. The article examines influence of concentrate with 14,33 % wt V2O5 and 65,44 MnO2 % addition in slag-with-soda furnace feed to determine positive effect on the result of roasting. Vanadium content of the slag is 22,34 % wt expressed as V2O5. Roasting temperature is 850 °C, Na2O/V2O5 molar ratio is 0,5:1, the concentrate is added as 0,25; 0,5; 1,0 mass ratio on the content of soda in starting furnace feed. Degree of vanadium conversion in water- and acid-soluble compounds is increased. The most effect is provided on the process of interaction between vanadium oxides and spinels with sodium compounds with formation of water-soluble vanadium forms. The optimal addition of concentrate is 0,25-0,5 mass ratio on the content of soda. Increasing of concentrate content is not effective. Both manganese and vanadium contained in concentrate give positive effect. Concentrate addition can be recommended for existing industry regardless of type of alkali addition on the stage of roasting.

Keywords: vanadium-containing slag, oxidating roasting with sodium, manganese-vanadium concentrate, increasing of vanadium yield, soluble compounds of vanadium and manganese

In the article obtaining of cathodic coating MnO2 on condenser porous tantalum anode was researched. It was ascertained that formation of crystalline defects from hydrated MnO2 on MnO2 coating obtaining by known technology is possible. Such formations disturb tantalum capacitor cathode integrity. To determine the reasons of the crystal defects formation conveyed simultaneous thermal analysis of Mn(NO3)2x4H2O and Mn(NO3)2x6H2O with an analysis of the flue gases by FTIR spectroscopy. Based on the analysis results a mechanism of manganese nitrate thermolysis was suggested and the cause of the crystal defects on the surface after the coating of manganese dioxide removed from the furnace was ascertained. It was established that the thermolysis process is followed by the formation of such manganese nitrate intermediates as manganese hydroxynitrate, manganese oxyhydroxide and its further oxidation to manganese dioxide. Because of secondary processes leaking on the MnO­2 cover manganese oxyhydroxide residual can react with water vapor and oxygen, that leads to the formation of crystalline defects. Such phenomenon has a negative impact on the chemical composition and integrity of the coating on the surface of the porous MnO2 tantalum capacitor anode. Also it has been found experimentally that manganese hydroxynitrate is formed from manganese nitrate in the form of microtubules on the porous tantalum vehicle surface.

Keywords: manganese dioxide, coating, manganese nitrate, thermolysis, crystalline defects, microtubules