Thermodynamics roasting

The hrst successful study which clarihed the mechanism of roasting, was a study of the oxidation of pyrite, FeSa, which is not a typical industrial process because of the availability of oxide iron ores. The experiment does, however, show die main features of roasting reactions in a simplihed way which is well supported by the necessaty thermodynamic data. The Gibbs energy data for the two sulphides of iron are,... 

In this study the physical parameters involved in interaction of a major class of meat flavorants, methyl pyrazines, with soy proteins were determined at meat roasting temperatures. Beef diffusate, the water soluble, low molecular weight fraction that constitutes about IX of beef, was shown to contain the necessary precursors to obtain a desirable, thermally generated meat aroma (8). Diffusate was heated under controlled conditions and generated volatiles were transferred to a gas chromatograph for separation and quantitation. Methyl pyrazines, either from heated diffusate or from standard solutions, were measured in the presence of purified soy proteins and the thermodynamics of binding were determined. 

Fluid-solid reactions include thermal decomposition of minerals, roasting (oxidation) of sulfide ores, reduction of metal oxides with hydrogen, nitridation of metals, and carburization of metals. Each t3 e of reaction will be discussed finm the thermodynamic point of view. Then reaction kinetics for all of the various rate determining steps in fluid-sohd reactions will be discussed for two general models shrinking core and shrinking particle. 

A -aryl Schiff s bases, 59-60, 60/ 61r Nd-Fe-B magnets separation fractional crystallization method, 170 hydrothermal method, 173 leaching process, 170-171 roasting-leaching, 171 selective leaching, 171-172 solvent extraction, 173-175 Nematic columnar phase, 12-13, I2f Nematic phase, 9-10 Neodymium (Nd) structural properties, 281-285 thermodynamic functions... 

Using thermodynamic data given in Appendix C, obtain AH° for the roasting of galena, PbS ... 

Based on elementary sulfur, three consecutive reactions are involved. First, sulfur is oxidized with air to SO2. Subsequently, SO2 is further oxidized catalytically to sulfur trioxide, and finally sulfuric acid is formed by absorption and reaction of SO3 in/with water. In contrast to sulfur oxidation to SO2, the oxidation to SO3 is limited by thermodynamic constraints, and is the crucial reaction step in H2SO4 production. Oxidation of sulfur in air is carried out in a refractory-lined furnace. Sulfur dioxide is also produced as a by-product of roasting of sulfide ores such as ZnS or FeS2. 

Thermodynamic Study of the Oolitic Hematite Magnetic Roasting... 

The research result of the thermodynamic study on the oolitic hematite magnetic roasting leads us to believe that the hematite is reacted as follows when the temperature is more than 570 C [7]. 

As shown in the Table 111, the Reaction equation 1 is easily react, even the equilibrium partial pressure 0(CO) is extremely small. Actually, it is a complete reaction irreversible chemical reaction, however, the equilibrium partial pressure 0(CO) of the reaction equation 2 and 3 are large under the condition of the temperature is 650°C-800°C. In order to guarantee the hematite not to over reduction to FeO, the CO concentration should be strictly controlled in the experimental process. The thermodynamic study of the oolitic hematite magnetic roasting indicates that the thermodynamic tendency is pretty dramatic if the hematite is reduced to the magnetite. 

The thermodynamics of zinc sulfide roasting have been studied by numerous investigators. The classical work on this subject is the paper by Ingraham and Kellogg [36]. Since iron tends to be present in the vast majority of naturally occurring zinc sulfide ores, the zinc-iron-oxygen-sulfur system is of considerable practical interest. This problem has been discussed extensively in Gray et al. [35] and some useful papers on this subject have been written by Kubaschewski [37] and Benner and Kenworthy [38]. Numerous kinetic studies have been made of oxidation of zinc sulfide the results of some... 

In the electrolytic processing of zinc it is desirable to convert the sulfide to a sulfate rather than to an oxide. The problem of zinc sulfate formation and the kinetic and thermodynamic criteria that would favor this process have also been extensively studied [46-51]. The study of zinc sulfide roasting in sinterbeds and in fluidized beds was investigated by Woods and Harris [51], Beveridge [52], and Kellogg [53]. 

T. R. Ingraham, Sulfate stability and thermodynamic phase diagrams with particular reference to roasting, Applications of Fundamental Thermodynamics to Metallurgical Processes, p. 187. Gordon and Breach, New York, 1967. 

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