Contents Alumino-Silicate

The aluminium content is commonly used as an indicator of the granulometry of the sample, since most of it is involved in the alumino-silicates which are well known to be the most important part of the smaller fraction. A rather good correlation (Fig. 9) can be found between S.S.A. and A1 content. 

Van Vlack [42] observed that the bosh region contained alkalies in excess of the requirements of kaliophilite and nepheline. This excess did not result in the formation of alumino-silicate or silicate minerals of higher alkali content but was present as alkali carbonates. The carbonates formed toward the end of the furnace campaign from the free alkali deposited in the bosh lining. For the particular furnace examined, Van Vlack determined that alkali-bearing minerals were present only where porosity and proximity of the surface permitted expansion. Therefore, the presence of alkalies did not prove seriously detrimental in the bosh and... 

Highly crystalline microporous titano-alumino-silicate ETAS-10 materials with different framework aluminium contents (Al/Ti molar ratio 0.1-0.48) have been studied by Si MAS NMR. ... 

An approximate amount of potassium alumino-silicates in coal mineral matter can be obtained from the potassium oxide (K2O) content of ash. The amount of non-silicate potassium species is small in most coals and the silicate minerals contain on average 11 per cent K2O by weight (O. Thus the potassium alumino-silicate content of coal mineral matter (K l-SIl) 7 weight per cent is ... 

Table I gives the SiO2> Al20q and K2O contents of some US and British bituminous coal ashes (4,7) which were used to calculate the approximate amounts of quartz, potassium alumino-silicate and kaolinite species in the mineral matter.

Some potassium sulphate can also be formed via the two routes. Potassium is present in coal chiefly in the form of potassium alumino-silicates (Table I) and a large part of the alkali-metal will remain involatile in the flame heated silicate particles. Some 5 to 20 per cent of the potassium is released for sulphation (24) which takes place partly at the surface of the parent particles (25) and partly via the volatilization routes as described above. However, sodium sulphate content of fly ash heated in pulverized coal flame, and chimney solids is always higher than that of potassium sulphate. 

The characteristics of flame heated silicate 3) suggest that the vitrified potassium alumino-silicate particles and the below 5 pm diameter kaolin particles are first to sinter after deposition. The flame vitrified particles have a high glass content and their small size enhances sintering, as evident from Equation (7). It is therefore to be expected that the inherent, small-particle mineral matter (Figure lb) will enhance sintering. 

Stomach acid extraction, with metal concentrations reported on a dry weight basis. Total elemental contents in the dust sample were determined using strong acid digestion followed by induetively coupled plasma mass spectrometry (ICP-MS), as follows Ca 8.95 wt% Fe 0.79 wt% A1 1.16 wt% Mn 156 mg kg Ni 45.5 mg kg Cu 260 mg kg Zn 1,220 mg kg and Pb 1,670 mg kg . The bioaceessible eontent of Pb as determined by simulated stomach acid digestion was 1,586 mg kg . Bulk powdered XRD analysis identified the presence of calcite and various alumino-silicates. 

A rather complex mixture is that constituted by the Italian tuffs [8, 53, 54], which contain various hydrated phases, namely three zeolites (phillipsite, chabazite and analcime, Table 1), unreacted glass (pumice, glass fragments, scoriae), hydrated ferric oxides and an X ray amorphous gel-like alumino-silicate, in addition to some non-hydrated phases, such as sanidine and biotite crystals. The most concentrated phases are phillipsite and chabazite, the total content of which usually amounts to 50% or more. Since Italian tuffs, simply because of the elevated contents of the above zeolites, are gaining a pre-eminent position in many industrial, agricultural and environmental applications, it is of great interest to have a rapid and reliable method available for evaluating zeolite content in the rock. 

In the general formula of the alumino-silicates, MAlSia 02a +2 5 both the type of cations M and the parameter x can vary considerably. Furthermore, the Si02 content can be replaced by AIPO4 to some extent. Finally, limited substitution of A1 in the aluminate component MAIO2 by other small trivalent or even bivalent atoms has also been reported. 

The thermal conductivity trend of dense alumino-silicate and high-alumina refractory castables is similar to that of refractory brick and is easy to predict As alumina content and density increase, so does thermal conductivity. Figure 14 illustrates this for dense conventional castables. As with insulating... 

The use of charred coal or petroleum coke requires solutions to three significant problems (1) the extraction of the mineral material phase including metal oxides, pyrite, and alumino silicates (collectively called ash ), (2) management of the sulfur content, and (3) use of the kinetic heat of the fuel cell to complete thermal decomposition of the fuel (bake out). The latter, not required for cell operation, improves overall efficiency and makes use of the high thermal diffusivity and conductivity of elemental carbon. Finally, some strategy must be devised for recovery of most of the carbon dioxide evolved from the anode. 

---