Oxide Ash

Alkali metal haHdes can be volatile at incineration temperatures. Rapid quenching of volatile salts results in the formation of a submicrometer aerosol which must be removed or else exhaust stack opacity is likely to exceed allowed limits. Sulfates have low volatiHty and should end up in the ash. Alkaline earths also form basic oxides. Calcium is the most common and sulfates are formed ahead of haHdes. Calcium carbonate is not stable at incineration temperatures (see Calcium compounds). Transition metals are more likely to form an oxide ash. Iron (qv), for example, forms ferric oxide in preference to haHdes, sulfates, or carbonates. SiHca and alumina form complexes with the basic oxides, eg, alkaH metals, alkaline earths, and some transition-metal oxidation states, in the ash. 

In addition to spectra of the reference minerals listed in Table II, the least-squares components in each iteration included 3 "spectra" representing 1) moisture in KBr blank (obtained by subtraction of 2 KBr blank spectra), 2) a constant baseline offset (1 abs from 4000 to 400 cm" ), and 3) a sloping linear baseline (line from 1 abs at 4000 cm" to 0 abs at 400 cm" ). The final mineral component concentrations were normalized to 100%, disregarding the contributions of the three artificial components. The normalized least-squares results for each sample were combined with the ash elemental composition of each reference mineral to calculate the elemental composition of the ASTM oxidized ash corresponding to each LTA. This was done by multiplying the concentration of each reference mineral in a sample by the concentration of each elemental oxide in the reference mineral, then summing over each oxide. 

The third method for assessing accuracy is to calculate an elemental composition for each LTA s corresponding oxidized ash, based on the reference mineral elemental compositions. Reasonably close agreement between the actual (obtained by ICP-AES) and calculated elemental compositions would substantiate (but not prove) the mineral analysis. The standard error of prediction (SEP) for... 

Figure 3. PCR Model Results for AI2O3 wt % of Oxidized Ash (Best Model of Ash Properties).

While biomass generally involves the burning of material it differs from fossil fuels in that no more heat or carbon dioxide is produced than would be produced by natural processes. As such, it is referred to as carbon neutral. However, it still produces CO2 and a range of other pollutants including nitrogen oxides, ash, but virtually no SO2. A further environmental benefit is that the combustion of landfill gas avoids accidental explosions and prevents the release of methane, which is more potent as a greenhouse gas. 

Three alternate techniques yielded quantitative recovery of cadmium from various matrices acid digestion (wet oxidation), ashing in the presence of sulfuric acid (wet ash), and a scaled down wet ashing procedure (mini-ash). The mini-ash technique is designed for small samples and is well suited for HVAA analysis. 

The mean relative particle masses (mean molecular weight) was measured using a vapor pressure osmometer (test in benzene at 38 °C). The contents of oxide ash were determined according to DIN 51 575. The results are presented in Table 4-9. 

Incineration destroys organic materials by thermal oxidation. Organie eompounds oxidize to form earbon dioxide, water, sulfur dioxide, nitrie oxide, ash, and/or produets of incomplete... 

The biilhance with which magnesium bums makes it ideal for use in flares and flashbulbs. Compare the mass of magnesium that bums with the mass of magnesium in the magnesium oxide ash that forms. Explain this in terms of atomic theory. 

The advantages of atomic absorption techniques as opposed to spectrophotometric analysis for the determination of metals are that the former are amenable to multielement analysis and can be automated. There is some evidence that ashing polymers in silica crucibles rather than platinum can lead to up to 10% losses of elements such as copper by adsorption within the silica matrix to produce a compound that is not extractible by subsequent acid leaching. This does not occur when ashing is carried out in platinum. If silica crucibles are used then a magnesium oxide ashing aid should be employed as is demonstrated in the method for determining down to 0.1 ppm of copper in polyolefins, (Method 72). 

Particles of low-grade lead sulfide are roasted to produce a porous lead oxide ash. At the center of the ore particles is a core of unreacted sulfide. The oxygen permeability in this core is much less than in the ash. Thus this reaction is best modeled as heterogeneous, occurring at the interface between ore and ash. 

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