Activation of slags

According to Solacolu [40], the effect of MnO on the hydraulic activity of slag depends on its alkalinity. In the case of basic slags MnO has a negative impact, while in the case of acid ones MnO affects advantageously the hydraulic activity. 

Ghosh, S.N. et al. (1997) Studies on activation of slag cements, in Proceedings 10th ICCC, Goteborg, paper 3ii092. 

Slags can be activated by calcium sulfate and other compounds such as NaOH, lime, water glass, phosphogypsum, etc. When calcium sulfate is added, the precipitation of ettringite provides a sink for Ca " and A1(0H)4 ions released from the slag. The nature ofproducts resulting from the activation of slags is similar to that in normal portland cement pastes (Table 5).[ l... 

At die slag-matte interface, the activity of FeO can be 0.3 as a maximum before Si02 saturation sets in. The activity of FeS can be assumed to vary over die activity range aFeS = 0.5-10 during the process, and so the oxygen... 

The losses of lead as litharge (PbO) can be minimized if the impurity elements could be oxidized at an oxygen potential lower than that which causes the oxidation of lead. This can be achieved if the activities of the oxides of the impurity elements in the slag are decreased, for example, by the addition of an oxide which reacts very much more strongly with the oxides of the impurities than it does with lead oxide. Sodium hydroxide is a useful reagent for this purpose and sodium nitrate can be used as the source of oxygen. The reaction involved in this process, known as the Harris process, can be formally written as... 

More efficient coal utilization can be realized with combined power plant cycles. For instance, the post combustion gases of a conventional combustor or an advanced MHD system can be further utilized to drive a gas or steam turbine. However, the sustained durability of downstream turbine or heat exchanger components requires minimal transport of corrosive fuel impurities. Control of mineral-derived impurities is also required for environmental protection. For the special case of open cycle-coal fired MHD systems, the thermodynamic activity of potassium is much higher in the seeded combustion gas (plasma) than in common coal minerals and slags. This results in the loss of plasma seed by slag absorption and is of critical concern to the economic feasibility of MHD. 

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. 

Hydraulic activity of municipal solid waste incinerator fly-ash-slag-blended eco-cement has been investigated using X-ray diffraction and Si MAS NMR. ... 

A second model due to Gaye 2. would appear to offer more promise it is based on the Kapoor-Frohberg model for the estimation of activities and assumes that both acidic and basic oxides are made up of symmetrical cells and these interact to form assym-metrical cells. The activities of the various oxides calculated for quaternary slags with this model are in excellent agreement with those determined experimentally. Values of for a given com-... 

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