Katsumi Mori

Simultaneous Desulfurization and Dephosphorization Reactions of Molten Iron by Soda Ash Treatment

Desulfurization and dephosphorization reactions of molten iron by soda ash has been studied on laboratory heats of Fe-C, Fe-C-S, Fe-C-P, and Fe-C-S-P alloys at 1573 and 1623 K. The alloys were melted in helium gas flow and preheated soda ash was added; metal samples were taken at certain time intervals and analyzed for sulfur, phosphorus, and carbon. Evolved gas samples were also taken at certain time intervals and analyzed. The phosphorus and sulfur contents in metals decreased rapidly, reaching the lowest values two to four minutes after the soda ash addition. The degree of desulfurization was generally greater than that of dephosphorization, and both degrees were higher at lower reaction temperature. The major component of evolved gas was CO with small amounts of CO2. Phosphorus appeared to form a stable phosphate compound with Na2O, possibly 3Na2O-P2O5, in the slag phase. Soda ash reacts with carbon resulting in decarburization of molten iron and vaporization of sodium; this reaction may cause the fading of soda ash and can be expressed as: Na2CO3(1) + (1 +x)C = (1 -xNa2O(1) + 2xNa(g_ + (2 +xCO(g). For the phosphorus containing melt, the reaction can be expressed as: Na2CO3(l) +yC + 2x/3P =x(Na2O · 1/3P2O5)(1) + (2 −y − 8x/3)Na2O(l) + 2(−l + y + 5x/3)Na(g) + (1 +y)CO(g) and for the sulfur containing melt: Na2O(l) +C +S = Na2S(l) + CO(g).

Reduction rate of SiO2 in slag by carbon- saturated iron

The reduction rate of SiO2 from CaO-SiO2-Al2O3 and CaO-SiO2-Al2O3-TiO2 slags by carbon-saturated iron melts was investigated over the temperature range 1350 °C to 1600 °C under an argon atmosphere. It was found that the reduction rate of silicon increased with in-creasing temperature and decreased with increasing ratio of CaO/SiO2 in these slags. A kinetic analysis of the experimental results developed on the basis of the two film theory showed that the silicon transport rate from slag to metal phase was controlled by the rate of chemical reaction at the slag-metal interface. The rate constants obtained for the reaction were 10 g m-2 s-1 at 1550 °C. The apparent activation energy was 238.0 kJ mol-1.

Carbon solution in liquid iron and iron alloys

The dissolution of carbon into liquid iron and iron alloys was investigated using four independent experimental approaches, i.e., immersion of a graphite cylinder in a melt bath using an electric resistance furnace, immersion of a coke particle in a melt bath using an induction furnace, a molten droplet on a graphite plate using an induction furnace and sliding a metal droplet down a graphite spiral in a resistance furnace. The dissolution rate was analysed by assuming that this reaction is governed by the diffusion of carbon from the carbon-metal interface to the bulk liquid metal through a boundary layer. The experimental results for each case were well interpreted by both concentration and activity driven models. The variation in the carbon dissolution rate with the experimental method was explained by the Olsson relation or the penetration theory. An increase in carbon dissolution rate with temperature was observed. The carbon dissolution rate into liquid Fe-C alloy was not changed by addition of 1.9 wt% silicon to the melt, while a decrease in the dissolution rate of carbon was observed by adding 1 wt% sulfur to the melt.

Effect of additive oxides on the viscosities of CaO-SiO2-Al2O3 and CaO-Fe2O3 melts

The effects of MgO, TiO 2 or Fe 2 O 3 on the viscosity of 40CaO-40SiO 2 -20Al 2 O 3 /mass% slags have been measured by a rotating crucible viscometer. The viscosity of these quaternary slags decreased with increasing the content of additive oxide. At the same content of additive oxide, the viscosity decreases from MgO, TiO 2 to Fe 2 O 3 . In addition, the effects of SiO 2 , Al 2 O 3 or MgO on the viscosity of 26.1CaO-73.9Fe 2 O 3 / mass% (CF) and 14.9CaO-85.1Fe 2 O 3 / mass% (CF 2 ) slags have been measured. Viscosity of calcium ferrite slags increased with increasing SiO 2 , Al 2 O 3 or MgO content. Al 2 O 3 was found to be more effective for increasing the viscosity at the same content of additive oxide.

Wettability of Cu-Based Alloys on Alumina and Joining of Alumina with Microdesigned Nickel-Chromium Alloy Interlayer

Monolithic ceramic materials are being widely developed for a variety of applications ranging from use as structural components to high-performance electronic substrates. Recently, however, major efforts have been made to use ceramics in structural applications under severe operating conditions. Joining of ceramics to ceramics and to metals is considered one of the key technologies that will either expand or restrict the potential use of ceramic materials in a wide range of applications, such as heat engines, heat exchangers and recuperators.

Rate of Oxidation of Pb, Ni in Liquid Copper by Molten Slags

Removal behavior of Pb, Ni from liquid copper by Cu2O-Fe2O3 based slag with one or two additive oxides among CaO, B2O3, SiO2, P2O5 and TiO2 was investigated in the temperature range from 1,200 to 1,300 °C. The results obtained are as follows,1) The Pb removal was largely increased by the addition of acidic oxide, but the Ni removal was at most 50 % for all slag compositions investigated.2) The addition of P2O5 and TiO2 was obtained nearly same good results as the addition of B2O3. Thus, P2O5 and TiO2 was found to be practically used as a substitute for B2O3.3) The Ni removal was enhanced by increasing temperature, which could be explained to the decrease of activity coefficient of NiO. However, The Pb removal was retarded by increasing temperature.4) The kinetic behavior of Pb and Ni removal by oxidizing slags could be well simulated by the reaction model based on the two film theory.

Melting Treatment of Incineration Ashes and Viscosity of Molten Slags

The melting treatment of the incineration residuals (bottom and fly ashes) is an effective method to stabilize the toxic substances (heavy metal, DXN etc.) and to reduce the volume and weight of them for landfill. The ashes had been melted at 1873K. As a result, the bottom ash was separated into slag and metal phases. As for the fly ashes, only slag phase was generated. It was shown that these slags consisted of many kinds of components. Among them, CaO, SiO2, and Al2O3 were major components. As the first step to control the melting treatment processes, the viscosities of slags generated by melting treatment and the effects of basicity on viscosities of synthesis CaO-SiO2-Al2O3 (Al2O3=20mass%) melts had been studied by a crucible-rotating method. The higher basicities of the slags were, the lower the viscosities of them were. The effects of additives on viscosities of synthesis CaO-SiO2 (CaO/SiO2=l) and CaO-SiO2-A12O3 (CaO/SiO2=l) melts also have been studied. The addition of Al2O3 lead to increase the viscosities of CaO-SiO2 (CaO/SiO2=l) melts, and the viscosities of the melts decreased with the addition of the other elements. The addition of fourth component (MgO, TiO2 and Fe2O3) lead to decrease the viscosities of CaO-SiO2-Al2O3 (CaO/SiO2=l) melts. More systematic studies about the effects of fourth component on viscosities of CaO-SiO2-Al2O3 melts of constant Al2O3 content will be desired.