Slagging index

A slagging index developed by the coal industry has been used to rate solid fuels for fouling. This index corresponds to the mass of alkali metal as oxides (K2O -I- Na O) per energy unit in the fuel and is useful for rating biomass feedstocks too. The calculation is made by... 

Gray and Moore [1974] proposed an empirical formula for the so-called Slagging Index (FS) considered to be a measure of the slagging propensity of the coal. It is based on the initial deformation temperature (IDT) and the hemisphere temperature HT. Jones [1978] demonstrated that the Slagging Index is a useful measure of slagging potential in boiler equipment. For lignitic ash the index is given by ... 

Ash fusion characteristics are important in ash deposition in boilers. Ash deposition occurring on the furnace walls is termed slagging, whereas accumulation on the superheater and other tubes is termed fouling. A variety of empirical indexes have been developed (60,61) to relate fouling and slagging to the ash chemical composition through parameters such as acidic and basic oxides content, sodium, calcium and magnesium, and sulfur. 

Figure 5. Prerequisite study - Comparison of the waste PEEP index values calculated for a municipal solid waste incinerator bottom ash (BA) and a slag from a second smelting of lead (2SL) as a function of each experimental liquid-to-solid ratios (L/S). Each waste PEEP index value was calculated using ecotoxicological results presented in Table 5 (see Section 5.6 for details of calculations).

The element calcium shows a spatial distribution similar to that of lead (Fig. 9-22 d). The locations of the concentration maxima are the same a small maximum has also arisen from the cement and slag mill in the north of the area investigated. There is no index value for calcium because calcium does not rank among the toxic elements. 

FIGURE 7.29 Spectral refractive index data for three different molten slags at 1600°C [249],... 

Microscopical examination should start in the quarry where samples of each of the varieties of limestone, sandstone, shale, etc., are collected, layer by layer, by a geologist or someone with an adequate knowledge of the quarry. An assumption of the mineralogy of most quarried materials, as well as many of the industrial byproducts, is commonly questionable. Representative portions of each rock variety are sent off, if necessary, for thin sectioning (see partial list of professional companies in Table 11-3). Some of these companies will also stain the thin sections as directed. Another portion of the rock is crushed in the plant laboratory with a mortar and pestle or other suitable crushing device, and sieved to produce a 45- to 75- im fraction for examination in a powder mount, using, at first, a liquid with a refractive index of approximately 1.542. Samples of nondeposit materials, such as slag, fly ash, bottom ash, rice husk ash, clay catalyst, etc., are examined similarly. 

Plagioclase feldspar (Na-Ca aluminosilicate), other than albite, stains red potash feldspar (microcline or orthoclase) stains yellow, and quartz and glassy slag are unstained. Calcite takes on various shades of pink and dolomite may be deep red. The particles are normally examined in immersion mounts, utilizing liquids of known index of refraction and a cover glass. 

For optimum reactivity with Portland cement it is important that the slag has the right chemical composition and a high glass content (>85%). The hydraulic index (eqn [1]) should be >1.0, preferably >1.5, where... 

Most simply, basicity can be expressed as the Ca0 Si02 ratio or by the more complete basicity index as shown in Table 5.2. The fluidity index also shown in Table 5.2 is clearly a closely related empirical guide, demonstrating that viscosity is influenced by basicity. A more basic slag will have a higher fluidity or lower viscosity. 

A series of studies using juvenile swine administered soils, slags, etc. from 17 U.S. mining, milling, smelting sites Relative bioavailability (versus soluble acetate) ranges from 19% to 100% using PbB Uptake indexed by Pb in blood, liver, kidney, femur Casteel et al. (2006)... 

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