Slagging influencing factors

Carbon Conversion. Carbon conversion on a once-through basis is a function of the coal composition and is strongly influenced by the oxygen/coal ratio. For some coals, the conversion pattern is also affected by the level of steam in the blast. Another factor is fly slag recycle, which raises the carbon conversion by recycling the unconverted carbon, most of which resides on the fly slag. This results in an overall carbon conversion greater than 99%. 

Many additional factors may influence the final design pressure drop (especially with small particle diameters) solids flow (for some feedstocks and at high specific capacities) cinder or slag formation entrainment of fine char particles heat recovery of the fuel gas, etc. 

Some compositional features also have a strong influence on the mechanical strength of the concrete, in particular the wjc ratio. However, in particular in chloride-contaminated environments, the cement type is even more important. In previous chapters, the microstructure of the cement paste and the beneficial role of blast furnace slag and pozzolana such as fly ash have been outlined. The other most important factor is of course the thickness of the concrete cover, which will be discussed in Section 11.4. 

The manner in which carbon is utilised for zinc production is affected by heat balance issues as well as chemical requirements for metal reduction. The heat balance is influenced by the amount of slag produced, the blast preheat and the preheat achieved in coke and sinter. Apart from the quantity of zinc oxide reduced, the chemical factors include the lead and iron contents of sinter and the moisture entering the furnace in blast air and in sinter or additives. Based on typical operating conditions as indicated above and a lead production of close to 50 per cent of the zinc production, the empirical formula used to relate carbon consumption to zinc production is given by Equation 6.1 ... 

Fig. 10.22 The influence of design factors on corrosion, (a) Storage tanks should be fabricated to allow complete drainage and access to outside surface for painting, (b) The insulation of cool pipe supports may prevent internal or external condensation of an electrolyte film. Insulation may prevent bimetallic corrosion tight insulation may prevent water ingress, (c) Full length, continuous welds are preferred to intermittent, tack ones. Slag and surface oxides must be removed prior to surface coating.

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