Slag system

The observed metal phosphate phases agree with thermodynamic models of the ash system described here. These phases control leaching in pH-stat systems and are present after aggressive leaching designed to remove available or leachable fractions. These phases are also similar to ones observed in soil, sediment, smelter dust, industrial wastewater, and slag systems. 

Pyrometallurgy with the emphasis on the chemistry of slag systems. 

Summary of Alkali Vaporization Data for K-Containing Complex Oxide and Coal Slag Systems... 

Since the mole fraction of K2O can be defined at any stage of an experiment, it is>possible to convert K-partial pressures to K2O activity coefficients using equation [6]. By varying the amount of K2O present in the slag during a vaporization run, we were able to follow the dependence of the K2O "apparent" thermodynamic activity on temperature and composition. The term "apparent is used to emphasize that the slag system may not always be in a state of complete thermodynamic equilibrium. Typical data. 

A key factor for successful MHD operation is the degree of interaction between plasma potassium seed and the slag medium. Using slag activity data from the present studies, it is possible to predict conditions under which plasma seed will be continuously depleted by slag absorption of alkali. Plante et al. ( ) presented similar arguments earlier, based on their data for the binary oxide systems. A more definitive analysis can now be made from the present data on complex synthetic and actual slag systems. 

Synthetic Slag (K2)-H20 H2 System. In order to extend the vapor transport conditions in slag systems to a reducing hydrous environment similar to that present in coal gasification, a series of TMS and KMS measurements were made using H2 or H2O as the initial reactant gas. With the TMS system, compositions of H2-N2-H2O up to 10 vol % H2 were attained prior to hydrogen-induced corrosive loss of the transpiration reactor. 

Effect of H2 on K-Vaporization As H2 was introduced to the slag system, the O2 concentration decreased and K and H2O increased, as expected for the process,... 

On the basis of the aqueous coordination chemistry of the metal ions involved, the following order of affinity for acceptor hgands such as sulfide ions would be predicted, Cu > Ni > Co > Fe > Fe , and roughly the reverse order would be expected for ligands such as oxide or hydroxide. This order is retained to a large extent in matte-slag systems, as shown in Table 10, which summarizes some data" on the distribution coefficient A of species i between the sulfide and sihcate phases under oxidizing conditions, calculated on a mole fraction basis. 

Suzuki et al. [7] tested a number of different slag systems for the removal of B under varying temperatures and in different atmospheres. They found that optimal distribution coefficients (Lb) exist for various fluxes (Fig. 1.4 and Table 1.1). The maximum value obtained by Suzuki et al. was approximately 1.7 at 1,500°C. They operated with a initial B content of 30-90mass ppm and the experimental time varied between 1.8 and 10.8 ks. The activity of Si was set to be 1. The experiments were conducted under CO atmosphere at 1,500°C. Similar experiments were performed by Tanahashi [8]. Some of the results are given in Table 1.1. 

In order to provide a temperature coefficient, the temperature dependencies of the molar volumes (dV/dT) of many slag systems were examined and a mean value of 0.01% was adopted. 

Figure 1 The molar volume of binary slag systems as a function of composition showing the individual x.V. contributions.

Figure 4 The composition dependence of Y, qY, 2 2 binary slag systems with (a) non-surface-...

Table II. Breakdown of Lower Order Systems Comprising 7-Component Coal Slag System.

The silicate slag systems are involved in most pyro-metallurgical processes which result in the formation of a number of ferrous and non-ferrous metals (Cu, Ag, Zn, Cd Sn, Pb, Sb, Bi). These systems are oxide- and sulfide-oxide melts, and, therefore, the processes of their interaction with raw materials are dependent on the melt properties (oxidation ability, solubility of metals), and on their oxoacidic properties. Any metallurgical slag contains MgO, CaO, FeO and Si02 as one of main components. The oxidation ability of the slags increases with a rise of their basicity (increase of equilibrium O2-concentration), caused by the following electrochemical process ... 

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