Isothermal hydrogen reduction of oxide scale on hot-rolled steel strip in 30 pct H2N2 atmosphere

Why Does Nitriding of Grain‐Oriented Silicon Steel Become Slower at Higher Temperature?

“…This is because the nitriding gas contains copious amounts of hydrogen, which is considered to be a favorable reduction gas for the hot‐rolled strip to remove the oxide scale. [ 19–21 ] However, unlike the reaction in which Fe 3 O 4 was reduced to Fe, hydrogen could reduce the lamellar oxides to the spherical ones in GOSS, and the reduction could be accelerated with the increase of temperature, as found in our previous research. [ 22 ] In addition, the N distributions in Figure 1e,j indicate that N atoms are not in the oxide particles but in the matrix; i.e., N atoms penetrate into the iron matrix by diffusion during nitriding.…”

Reduction–Magnetic Separation of Pickling Sludge by Biomass Pyrolysis Reducing Gas

“…According to the thermodynamic analysis ( Figure 8 ), the Gibbs free energy of the reaction of CO, H 2 , and CH 4 with Fe 2 O 3 decreases significantly with increasing temperature, which is conducive to the reduction of Fe 2 O 3 to Fe 3 O 4 . When the temperature exceeds 680 °C, on the one hand, too high a temperature causes SHPS to experience local sintering, and the reducing atmosphere cannot fully contact Fe 2 O 3 in SHPS, which reduces the reduction rate of SHPS; on the other hand, according to the thermodynamic analysis ( Figure 8 ), the Gibbs free energy of the reaction between CO, H 2 , and Fe 3 O 4 is less than 0 at 600 and 700 °C, indicating that the higher content of reducing gases such as CO and H 2 from corncob pyrolysis can deeply reduce part of the SHPS into weakly magnetic wustite (FeO), 32 reducing the Fe grade and recovery rate of SHPS. In addition, when the temperature is too high, Fe 2 O 3 may react with Na 2 O and CaO to form 2CaO·Fe 2 O 3 , and Na 2 O·Fe 2 O 3 , 33 which will also reduce the grade and recovery ratio of iron.…”

Clean production and utilisation of hydrogen in molten salts

“…Hydrogen is also considered as a green reducing agent for the sustainable production of a large variety of metals such as molybdenum, 12,13 nickel, 14 germanium, 15 tungsten, 16 and cobalt 17 as well as alloys such Fe-Mo. 18 On important possible application of hydrogen is the clean reduction of iron oxides either from oxidised alloys, 19 or iron ores [20][21][22] at 600-800 C. This application is particularly attractive due to the fact that the steel industry is at the heart of global development with a world production of over 1.8 billion tons, producing more than 3.2 billion tons of CO 2 every year. 23…”