Partially molten phase

The melting endotherm at a lower temperature of curve B is quite simihr to that of curve D of the sample cooled down to room tempoature after conq>lete noting. It has been confirmed that the endotherm at a lower temperature in tl% tearing curve of the sample annealed at 178 C is of the crystal framed from the partially molten phase. 

For straw ash/sand, the first occurrence of a melt phase appears in the sample heated at 725 for 6 hours. A transition from a partially molten to a fully molten ash phase occurs in the sample heated at 800 °C for 6 hours and all ash is also molten in the samples heated at 900 °C (see Figure 2). 

In addition, Brambilla has claimed that both iodine and ruthenium are volatilized when the molten nitrate reacts with the oxide fuel (9). In contrast to this volatilization, other literature claims that both iodine and ruthenium will be found in the molten phase (6, 13). Avogadro and Wurm state that most of the fission products, other than the noble metals, are either volatile or soluble in the nitrate melt, even without addition of nitric acid vapor (12). In a later paper, however, Avogadro reports that iodine is stable as iodide in molten nitrates, and that ruthenium is partially soluble in the molten phase, and partially volatilizes, while the majority remains with the... 

The measurement of partial pressures over a liquid or solid mixture of two metals is not as simple. Mostly, it is restricted to higher temperatures or even to the molten phase. The direct measurement can be done, for example, in high or ultra high vacuum, using a Knudsen cell and a mass spectrometer for selective pressure determination. Dynamic measurements were developed, e.g., transportation methods. A steady stream of a reactive gas is passed over the sample transporting the reactive component to a cooled region of the apparatus. From the measured mass of the transported metal and the flow rate the vapor pressure can be calculated. Kubaschewski et alP have given a detailed description of the experimental possibilities. 

Fly ash particles are typically spherical, as they are formed by solidification of droplets of a partially melted material, suspended in the flue gas, upon cooling. Particles that are formed at lower combustion temperatures may be irregular, owing to the reduced amount of melt present. Occasionally, tiny grains of volatile salts may be deposited on the ash particle surface. About 20% of fly ash particles are hollow, owing to an entrapment of gases by the molten phase in the course of burning. They are called cenospheres. Some of them, called plerospheres, may contain smaller particles inside. 

Isothermal decomposition at 549-569 °C proceeds in three stages in the initial stage decomposition occurs after partial melting at the unsteady site on the crystal surface in the intermediate stage, decomposition occurs in the molten phase after entire melting to liquid in the last stage, decomposition of liquid takes place at the surface of the new phase KCL The reaction proceeds as KCIO KCI + 2O2. 

The equilibrium conditions for each reaction may be expressed in terms of the partial pressure ratios of CO to CO2 and are illustrated in Eigure 5.1. As a simplification this assumes solid-gas reactions with unit activity of the solid oxide reactants. If in the molten phase, such as PbO dissolved in slag, the activity will be much lower and the eqnihbrinm ratios for COiCOj will be correspondingly higher. For partial pressure ratios of one or above, covering the bulk of the reactions zones of the shaft. Figure 5.1 indicates that PbO reduction should proceed readily, ZnO can be reduced to zinc vapour above 800°C, and iron oxides will be reduced primarily to FeO. In Figure 5.1 the ZnO reduction equilibrium is shown for a zinc vapour partial pressure of 0.01 atmospheres or one per cent in the gas stream. Zinc partial pressure will vary widely however, this serves only to illustrate that zinc vapour will be present at partial pressures of this order. 

Obtain an expression for the molten-phase impurity mass fraction distribution as a function of the molten-phase impurity mass fraction in the bulk melt, employing the partial mixing model in single pass zone melting. State your assumptions. 

Figure 9.1 Inverse partial melting problem in the three-dimensional space of elements 1, 2, 3 when the source is known. Projection of the source onto the sample subspace provides the mass-fraction of each phase of the molten source. If one phase is at the origin (sterile phase), every representative point can be shifted by a constant vector.

The Mg particles melt at the burning surface and are partially oxidized by the fluorine produced by thermal decomposition of the Tf particles. Meanwhile, the Tf particles decompose completely to produce fluorine and other gaseous fragments. During decomposition of the Tf particles, some of the Mg particles melt and form agglomerates on and above the burning surface, while others are ejected into the gas phase whereupon they are rapidly oxidized by the fluorine. The oxidation of each Mg particle occurs at the molten layer on its surface. 

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