Proximate fixed carbon

The proximate analysis of charcoal is 20-25% volatile matter, 70—75% fixed carbon, and 5% ash. Charcoal briquets have lower heating values than charcoal lumps, because of additives in the briquets. The higher heating value of lump charcoal is - 28 kJ/kg (12,000 Btu/lb). The higher heating value of briquets is 23 to 25 kj/kg ( -- 9,900-10,800 Btu/lb). 

Graphite is frequently, although incorrectly, analyzed by the proximate method used for coal in which the volatile material is deterrnined by strongly beating the sample in a covered or luted cmcible. Some oxidation of the graphite always occurs so that the value obtained for volatile matter is high and thus the "fixed carbon" is too low. The method lacks both accuracy and precision. 

Analysis. The proximate analysis is based on determinations of volatile matter, moisture, and ash for a coal sample. Fixed carbon is then calculated by difference. Volatile matter is determined empirically by measuring the weight loss when coal is heated in a covered cmcible at either 950°C (ASTM D3175 or D5142) or 900°C (BS). 

Fixed carbon, the residue left after the volatile matter is driven off, is calculated by subtrac ting from 100 the percentages of moisture, volatile matter, and ash of the proximate analysis. In addition to carbon, it may contain several tenths of a percent of hydrogen and oxygen, 0.4 to 1.0 percent nitrogen, and about half of the sulfur that was in the coal. 

Proximate analysis - a relatively low-cost analysis in which moisture content, volatile combustible matter, fixed carbon, and ash are determined. The fuel value of the sludge is calculated as the weighted average of the fuel values of its individual components. 

The composition of coal is conveyed by representing its proximate and ultimate analysis. The former implies determination of contents of moisture, volatile matter, fixed carbon, and ash, while the latter implies total carbon, hydrogen, oxygen, nitrogen, sulfur and ash. Here, an account will be provided of the constituents of coal, moisture, volatile matter, ash, fixed carbon, and some miscellaneous components. 

Table 6.12 shows the proximate analysis data and higher heating values (HHV) of samples. The HHV (MJ/kg) of the moss and alga samples as a function of fixed carbon (FC), wt.% can be calculated from ... 

Figure 2. Comparison of fixed carbon (dry, mineral free) with relative stratigraphic position on Mt. Schopf and Mt. Glossopteris. Results of proximate analyses of three measured sections (Long (23)) are plotted in each group...

Proximate Analysis. This includes (he determination of total moisture, volatile matter, and ash and the calculation of fixed carbon for coals and cokes. The term Proximate" should not be confused with Ihe word approximate." since all Proximate Analysis tests are performed according lo rigid specifications and tolerances. Proximate Analysis results may be used lo establish the rank of coals to show the ratio of combuslible lo incombustible constituents, lo provide the basis for buying and selling coal, and to evaluate for beneliciation, or other purposes. 

Coal, Analytical Procedures. The most frequently made analysis of coal is the proximate analysis. This includes detns of moisture, volatile matter, fixed carbon and ash. Sometimes it is combined with detn of sulfur and phosphorus, which really belongs to the ultimate analysis, and includes also detn of carbon, hydrogen, nitrogen and sulfur. In most cases, the heating value of coal expressed in BTU/lb is also detd,... 

Proximate analysis Determination of the approximate overall composition (i.e., moisture, volatile matter, ash, and fixed carbon content)... 

Many of the test methods applied to coal analysis are empirical in nature, and strict adherence to the procedural guidelines is necessary to obtain repeatable and reproducible results. The type of analysis normally requested by the coal industry may be a proximate analysis (moisture, ash, volatile matter, and fixed carbon) or an ultimate analysis (carbon, hydrogen, sulfur, nitrogen, oxygen, and ash). 

Thus, to classify coal, the calorific value and a proximate analysis (moisture, ash, volatile matter, and fixed carbon by difference) are needed. For lower-rank coals, the equilibrium moisture must also be determined. To calculate these values to a mineral-matter-free basis, the Parr formulas are used (ASTM D-388). 

The standard test method for proximate analysis (ASTM D-3172) covers the methods of analysis associated with the proximate analysis of coal and coke and is, in fact, a combination of the determination of each of three of the properties and calculation of a fourth. Moisture, volatile matter, and ash are all determined by subjecting the coal to prescribed temperature levels for prescribed time intervals. The losses of weight are, by stipulation, due to loss of moisture and, at the higher temperature, loss of volatile matter. The residue remaining after ignition at the final temperature is called ash. Fixed carbon is the difference of these three values summed and subtracted from 100. In low-volatile materials such as coke and anthracite coal, the fixed-carbon value equates approximately to the elemental carbon content of the sample. 

Although in many laboratories the methods described above remain the methods of choice for determining the proximate analysis of coal, there is also a test method for the proximate analysis of coal by instrumental procedures, assuming that calibration is an integral part of the procedure (ASTM D-5142). This method covers the determination of moisture, volatile matter, and ash and the calculation of fixed carbon in the analysis of coal and coke samples prepared in accordance with standard protocols (ASTM D-2013). The results may require a correction for bias or be corrected for instrument calibration using samples of known proximate... 

Proximate analysis determination, by prescribed methods, of moisture, volatile matter, fixed carbon (by difference), and ash. 

Correlate premaceral contents with corresponding proximate (fixed carbon, moisture, ash, volatile matter), ultimate (C, H, 0, N, S) and heating value (3TU) analyses. 

We calculated the specific surfaces shown in Table 1 by an improvement of the procedure described in Reference 7. In our more recent studies of coals, rather than using the mass absorption coefficient of carbon, we have computed the mass absorption coefficient of each coal from the elemental composition given by the ultimate analysis. These mass absorption coefficients, which depend quite strongly on the composition and concentration of minerals in the coals, varied from about 7 to 12 cm /gm. We also have taken the values of the coal densities from Fig. 2 of Reference (17). This plot shows the coal density as a function of fixed carbon content and thus provides more reliable densities than the approximation we used in Reference (7). The quantity I A was calculated from the scattering data for colloidal silica samples by the procedure outlined in Reference 7. The proximate and ultimate analyses of... 

Taking into account the proximate analysis of the input material (water content W, volatile matter VM and ashes content A ), it is possible to estimate the fixed carbon Cf ... 

Proximate analysis Moisture Volatile matter Fixed carbon Ash... 

The material was a crushed using a forage harvester-crusher machine, and was then reduction by using a hammer mill. The following analytical tests were made for poplar characterization proximate analysis (Fixed carbon, volatile matter, ash content), ultimate analysis (C, H, N, S, O2, Cl), and heating value. 

Fig. 4 Proximate composition (volatile and fixed carbon contents) of waste wood and...

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