Dependence of the Quality and Technological Characteristics of Coals from the Irsha-Borodino Deposit of the Kansk-Achinsk Basin on Their Petrographic Composition
Abstract Generated abstract
This paper examines how the quality and technological characteristics of coals from the Irsha-Borodino deposit, particularly the Borodino seam, relate to their petrographic composition. Using previously obtained proximate, ultimate, ash-chemistry, and petrographic data, the study compares coal types and applies graphical analysis and least-squares fitting to identify correlations among ash content, volatile matter, calorific value, elemental composition, and maceral assemblages. The results indicate that sapropelite-humite coals, especially algal clarens and related types rich in liptinite elements, show the highest calorific values and volatile yields, while claren and durene-claren varieties occupy lower ranges. The author argues that these correlations may support approximate petrographic interpretation from chemical and technological analyses, and conversely help predict technological properties from petrographic mapping.
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PROCEEDINGS
OF THE TOMSK POLYTECHNIC INSTITUTE
AWARDED THE ORDER OF THE OCTOBER REVOLUTION
AND THE ORDER OF THE RED BANNER OF LABOR
named after S. M. Kirov
Vol. 177 1971
DEPENDENCE OF THE QUALITATIVE AND TECHNOLOGICAL CHARACTERISTICS OF COALS FROM THE IRSHA-BORODINO DEPOSIT OF THE KANSK-ACHINSK BASIN ON THEIR PETROGRAPHIC COMPOSITION
V. L. Kokunov
(Presented by Professor A. V. Aksarin)
The quality of the coals of the Irsha-Borodino deposit began to be studied in detail as early as the time when exploration work was being carried out in the 1st and 2nd areas, i.e., beginning in 1940. In each exploratory borehole, bed samples were taken and subjected to proximate and, in part, ultimate analysis. The total number of samples tested is a four-digit figure. Suffice it to say that during the exploration of the Borodino 1–2 field alone, 778 samples were subjected to proximate analysis, and there are more than one and a half dozen such fields in the deposit. Thus, the ultimate composition of the organic mass of the coals of the deposit and their technological properties have by now been studied in sufficient detail, although the material composition of the coal ash and its temperature and viscosity characteristics have almost not been studied at all, which is very important to know when selecting the type and operation of boiler units, in particular, combustion devices.
Table 1
| Name of seams | No. of samples | W | Ac | V | Q | S | C | H | N+O | Tar yield, % |
|---|---|---|---|---|---|---|---|---|---|---|
| Upper | 2 | 13,0 | 31,0 | 42,0 | — | — | — | — | — | 9,7 |
| Sovkhozny | 2 | 30,0 | 24,0 | 34,0 | — | — | — | — | — | 11,5 |
| Profilny | 2 | 14,0 | 13,0 | 44,0 | — | — | — | — | — | — |
| Rybinsky | 101 | 18,3 | 12,5 | 39,5 | 5945 | 0,63 | 73,8 | 4,2 | 24,5 | 5,8 |
| Gusevsky | 89 | 20,1 | 19,2 | 39,8 | 5940 | 0,60 | 69,2 | 5,4 | 23,1 | 1,4—9,4 |
| Borodinsky | 1123 | 20,4 | 13,1 | 41,8 | 6481 | 0,50 | 72,5 | 5,1 | 22,5 | 1,8—24,3 |
| Podborodinsky | 33 | 21,9 | 13,3 | 41,3 | 5083 | 0,72 | 74,5 | 4,1 | 21,4 | — |
| Novy | 91 | 16,0 | 19,6 | 42,3 | 4764 | 0,30 | 73,0 | 3,5 | 24,5 | 12,0 |
| Irshinsky | 46 | 15,9 | 18,6 | 43,9 | 5090 | — | — | — | — | — |
Averaged results of investigations of the ultimate composition and proximate analysis of the coals of the Borodino suite, according to geological exploration work for 1940–1948, are given in Table 1 and provide exhaustive—
…forming an idea of coal quality. A sufficiently detailed petrographic description of the Borodino coals was carried out by us by order of the Krasnoyarsk Geological Administration (1964) and is not given here.
The most highly qualified determinations of the quality of the Borodino coals carried out recently were the studies performed in order to determine rational methods for burning them in large boiler units by specialists of the Department of Boiler Construction and Boiler Installations of the Tomsk Polytechnic Institute, I. K. Lebedev and N. V. Trikashin (1964), on assignment from “Krasnoyarskenergo.”
According to the conclusion of I. K. Lebedev and N. V. Trikashin, the coals of the Borodino seam are characterized by averaged data from proximate and ultimate analyses, summarized in Tables 2 and 3; moreover, averaging of the thermotechnical characteristics of the coals was carried out by fitting an equation for the dependence of the determined quantity on the ash content of the dry mass by the method of least squares.
Table 2
| Determined characteristic | C^r | C^p | H^r | H^p | N^r | N^p | S^r | S^p_r | O^r | O^p |
|---|---|---|---|---|---|---|---|---|---|---|
| Method of determination | GOST 20408-49 | GOST 20408-49 | GOST 20408-49 | GOST 20408-49 | GOST 2408-49 | GOST 2408-49 | — | — | GOST 20408-49 | GOST 20408-49 |
| Value determined | 74.4 | 44.5 | 4.8 | 3.0 | 1.0 | 0.6 | 0.1 | 0.1 | 22.7 | 14.1 |
Table 3
| Determined characteristic | W^r_n | W_max | W^p | A^c | A^p | V^r | Q^r_b | Q^r_n | Q^p_n |
|---|---|---|---|---|---|---|---|---|---|
| Method of determination | GOST 8719-58 | GOST 8858-58 | — | GOST 6383-52 | GOST 6383-52 | GOST 6382-52 | GOST 147-51 | GOST 147-51 | GOST 147-51 |
| Value determined | 12.5 | 32.3 | 30.0 | 11.0 | 7.7 | 46.6 | 6890 | 6610 | 39.0 |
Mathematical processing of the analytical data made it possible for them to give a linear dependence of all the main indices of ultimate and proximate analyses on the ash content of the dry mass, as follows:
\[ C^c = 71.36 - 0.712\, A^c \% \]
\[ H^c = 4.79 - 0.048\, A^c \% \]
\[ N^c = 1.03 - 0.01\, A^c \% \]
\[ S^c = 0.13 - 0.001\, A^c \% \]
\[ O^c = 22.75 - 0.23\, A^c \% \]
\[ V^c = 46.6 - 0.47\, A^c \% \]
\[ Q^c_b = 6886 - 0.069\, A^c \ \text{kcal/kg} \]
The results of the study of the chemical composition of the ash showed that, in all samples with an ash content of 4.5–5%, the predominant component of the ash…
is calcium oxide (40–50%) with a relatively low content of silica and aluminum oxides. When the ash content of the coal increases to 10–11%, the calcium oxide content in the ash drops sharply to 20–25%, while the silica content rises even more sharply, reaching 50–60% of the total ash mass. The content of aluminum oxides increases only slightly, and the content of other ash components also decreases. This very important fact indicates that an ash content of 4.5–5% is due to the presence of inorganic compounds in the original coal-forming plants, and it confirmed our assumptions regarding the magnitude of the “internal” ash content of the Borodino coals. Table 4 presents the most typical results of determining the chemical composition of the ash of Borodino coals.
Table 4
| Sample number | Ash content | Chemical composition of ash, % | Chemical composition of ash, % | Chemical composition of ash, % | Chemical composition of ash, % | Chemical composition of ash, % | Chemical composition of ash, % | Chemical composition of ash, % |
|---|---|---|---|---|---|---|---|---|
| Sample number | Ash content | SiO₂ | TiO₂ | Al₂O₃ | Fe₂O₃ | CaO | MgO | SO₃ |
| 11-p | 5.3 | 16.14 | 0.35 | 6.32 | 18.19 | 43.89 | 6.71 | 8.56 |
| 4-p | 14.18 | 51.36 | 3.52 | 19.53 | 4.63 | 14.25 | 2.71 | 4.29 |
To carry out the above-mentioned technical and ultimate analyses, bed-industrial samples of coals from the Borodino seam were taken by I. K. Lebedev and N. V. Trikashin from the same points in trench No. 1 of the open-pit coal mine where we carried out the macroscopic description of the coals and took samples for preparing polished sections and their subsequent petrographic processing. Thus, it became possible to compare the results of the technical and ultimate analyses with the results of the petrographic analysis of the coals.
As this comparison showed, there is no strict linear dependence between the technological properties and the petrographic composition of the coals of the Borodino seam, but a definite correlative dependence is clearly present.
To find this dependence, we constructed graphs (Figs. 1, 2), which showed that the calorific value and the yield of volatile matter in Borodino coals depend on their petrographic composition.
This dependence consists in the fact that, as can be seen from the graph (Fig. 1), the highest values of calorific value and yield of volatile substances correspond to sapropelite-humite coals, namely: algal clarens, algal claren-durens, and coals of the kasyanite type. These are followed by claren-durene and durene-claren types of coals, and then by coals of the claren type. From the above follows the very interesting conclusion about the practical significance of the content of liptinite elements in assessing the quality of Borodino coals.
Mathematical processing of the graphical plots by the least-squares method gives an equation for the dependence of the technological properties of Borodino coals on their petrographic composition, which may be expressed as follows:
$$ Q_{\mathrm{b}}^{\mathrm{a}} = 107.4 \cdot V^{\mathrm{a}} + 1450, $$
up to 34.5 \(V^{\mathrm{a}}\)% — claren type of coal,
34.5–36.7 \(V^{\mathrm{a}}\)% — durene-claren and claren-durene types of coal,
36.7–40.00 \(V^{\mathrm{a}}\)% — humite-sapropelites and sapropelite-humites.
Fig. 1. Dependence of the calorific value and yield of volatile substances on the petrographic composition of coal. Conventional designations: 1 — clarain type coal; 2 — clarain and dureno-clarain types of coal; 3 — sapropelite-humic type of coal.
Fig. 2. Elemental composition of coals as a function of their petrographic composition. The symbols are the same.
Visible axis labels: \(O^{a}, \%\); \(C^{a}, \%\).
Visible curve and point labels include: \(13\text{-}n\), \(30\text{-}n\), \(14\text{-}n\), \(18\), \(29\text{-}n\), \(26\), \(14\), \(31\text{-}n\), \(11\text{-}n\), \(10\text{-}n\), \(28\), \(20\text{-}n\), \(25\), \(12\text{-}n\), \(24\text{-}n\), \(15\text{-}n\), \(8\), \(25\text{-}n\).
From the equation, with known \(Q_b^a\) and \(V^a\), one can obtain information on the petrographic (certainly approximate) composition of the coals of the Borodino seam.
As the results of the comparison showed, a similar dependence on petrographic composition is also exhibited by the elemental composition of the Borodino coals, which is clearly reflected in the graph of the dependence of the carbon and oxygen content in the coals on their petrographic composition. As can be seen from the graph, the highest carbon and oxygen content in the Borodino coals corresponds to sapropelite–humite coals, followed by clareno-durene and dureno-clarene types of coal, and after them coals of the clarene type.
In conclusion, it should be noted that the analogy established when comparing three types of analysis that are entirely different in character and methodology—elemental, proximate, and petrographic—makes it possible to hope for a sufficiently reliable interrelation of their results. This opens up the possibility of using the results of proximate and elemental analyses for constructing coal-petrographic maps and, conversely, of using petrographic studies for predicting the (quantitative) technological properties of Borodino (and possibly not only Borodino) coals, since study of the petrographic composition of coals from the Aban, Nazarovo, and Berezovo deposits of the same basin has shown great similarity to the petrographic composition of the coals of the Irsha-Borodino deposit.
REFERENCES
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V. L. Kokunov. Petrographic characterization of the Borodino seam of the Irsha-Borodino deposit of the Kansk brown-coal basin. Izv. TPI, vol. 127, issue 1. Publishing House of TSU, 1964.
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I. K. Lebedev, N. V. Trikashnyi, A. A. Torlopov. On certain properties of the ash of coals from the Irsha-Borodino and Nazarovo deposits of the Kansk-Achinsk Basin. Teploenergetika, No. 11, 1964.