Prof. I. V. Gebler

Sobolev Brown Coals and Sapropelites of the Chulym-Yenisei Coal-Bearing Region

The Chulym-Yenisei brown-coal basin includes the following principal coal-bearing districts: 1) Uryupo-Kiya, 2) Chulym-Serezh, 3) Achinsk, 4) Sobolevsky (or Sobolevsky-Balakhtinsky), 5) Kizikulsky, 6) Krasnoyarsk, and 7) Yenisei-side.

The first 5 districts are sometimes grouped under the name of the Chulym basin proper. This basin has so far been investigated very little and, with respect to exploitation, is almost untouched. Here there are only rare and insignificant workings of purely local importance.

The productive coal-bearing strata of the basin belong to the Jurassic system and, in part, in the west, to the Cretaceous. The entire basin as a whole is characterized as a brown-coal basin, and for a number of deposits the presence of beds of sapropelites and bituminous shales within the brown-coal seams has been established.

In the latter respect, the most interesting is the Sobolevsky deposit, situated near the village of Sobolevka in the Kozyulsky district, 7 km from the Shushkovsky siding and 15 km to the southwest of Kozyulka station of the Tomsk Railway. From the town of Achinsk this deposit is at a distance of about 40–45 km, and it should not be identified with the Achinsk deposit proper, situated directly at the town of Achinsk, between the town and the railway station Achinsk II.

In this deposit, prospecting in 1931–32 established the presence of lignite seams in the upper beds and typical brown coal in deeper horizons (down to a depth of 220 m); sapropelites, however, have not yet been discovered. Therefore the sapropelites of the Sobolevsky deposit should not be called “Achinsk,” as is often done; it is better to retain for them, for more precise coordination of the district and to avoid confusion, the former name, i.e., “Sobolevsky sapropelites.”

The Sobolevsky deposit is at present also the most thoroughly explored in the Chulym basin. Here, in a Jurassic sequence more than 350 m thick, three coal-bearing horizons have been discovered, with brown-coal seam thicknesses from 1 to 12 m.

The sapropelites occur in the upper horizon and form part of a complex brown-coal seam with a total thickness from 5–7 to 8.2 m.¹ Two beds of sapropelites have a thickness of 0.47–0.48 m, which persists over the entire explored area of 20–30 km.

According to the calculations of geologist P. I. Dorofeev,¹ the reserves of sapropelite in this area, taking the thickness of the sapropelites as 1 m, should amount to a figure on the order of 50 million tons; he also notes the convenience of exploiting the deposit, bearing in mind the comparatively shallow occurrence (down to 160 m), the gentle dip of the seams (up to 5°), and the proximity of the main line of the Tomsk Railway.

A chemical investigation of two samples of Sobolevsky sapropelites was carried out by K. Kuryndin in 1932 at the Siberian Scientific-Research Institute of Artificial—

... of Liquid Fuel and Gas. The following data are given for them^2): moisture content was 14 and 24%; ash, 24.3 and 24.7%; sulfur, 0.7%. Combustible mass: carbon, 68 and 69%; hydrogen, 7.8 and 7.9%; oxygen, 21.8 and 19.7%; volatile matter, 70.1 and 71.2%. Distillation in the laboratory (500°) yielded:

At the same time the following distinctive features were noted: non-caking semicoke, a low content of acidic substances in the tar (3.3%), a considerable content of paraffin in it (5.4%), and a very large amount of carbon dioxide in the carbonization gas (35%).

In terms of the yield of primary tar with a low content of acidic substances, the sapropelite samples investigated by K. Kuryndin are not inferior to the Barzas samples, while surpassing them with respect to non-caking character. This determines the great value of the Sobolev sapropelites and the need for their further detailed investigation.

As for the brown coals of the Sobolev deposit, among which sapropelite seams occur, no data of any kind are available on them. Meanwhile, their investigation is absolutely necessary, bearing in mind that, when the deposit is worked for the extraction of sapropelites, brown coals—which constitute the principal coal material of the deposit—will also be mined together with them, and in one way or another will have to be utilized.

In the coal-chemical laboratory of the Tomsk Industrial Institute, a number of samples of brown coals and sapropelites from the Sobolev deposit were investigated. The results of this investigation are presented below.

For a more complete characterization of the deposit, samples were taken from various boreholes (cores) of the recent exploration. Analyses of these samples were made in the laboratory of the W.-S. Geological-Prospecting Trust and were supplemented by certain determinations. Table 1 gives the results of the determinations.

The overwhelming majority of the coals sampled from the borehole data are typical brown coals, among the seams of which, at times very thick ones, beds of sapropelites and bituminous shales have been recorded at certain points, sometimes up to 1.55 m thick (borehole No. 109).

The brown coals, with respect to combustible mass, are characterized by figures lying within the following limits:

\[ \begin{aligned} C^{r} &: 62.79—71.63\% \\ H^{r} &: \phantom{6}4.56—\phantom{5}6.89\% \\ V^{r} &: 36.40—56.37\% \end{aligned} \]

The moisture in the air-dry mass (\(W^a\)) ranges from 9.29 to 25.89%. It must be said, however, that in determining moisture under ordinary conditions (drying at 105° to constant weight), it is possible that not all the moisture could have been removed; this circumstance may be connected with the very large amount of “pyrogenetic water” obtained in some cases during distillation in a Fischer retort.

The amount of ash in the brown-coal samples ranges from 8.24 to 56.79%. It should be noted, however, that the high ash content in a significant—

^2) “Coal of the East,” 1932, No. 10, p. 31.

Table 1.

Table 1. Continued.

degree depends on the taking of the sample during drilling and, perhaps, is not characteristic of the coal seams.

For some coals from boreholes Nos. 104, 105, 107 and adit No. 1, an ash analysis was made; its results are given in Table 2, where the sample numbers correspond to the serial numbers of Table 1.

Table 2.

The composition of the ash is thus very varied. Owing to the low content of clay matter and the large amount of fluxes (Fe₂O₃, CaO, MgO), the ash should be readily fusible.

For an approximate characterization of the fusibility of the ash, one may use calculation by the method of E. Prost, according to the formula:

\[ M=\frac{A^2}{B.S} \]

where: A is the amount of oxygen in the alumina of the ash, S is the amount of oxygen in the silica, and B is the amount of oxygen in the fluxes, i.e. in the oxides Fe₂O₃, CaO and MgO (not including the alkalis in the calculation, because of their low content).

If \(M > 2.25\), and the Fe₂O₃ content in the ash does not exceed 7%, the ash may be considered refractory, with a melting point above 1500°. If \(M\) lies between 1.6 and 2.25, and the Fe₂O₃ content is more than 7%, the ash may be considered of medium fusibility, with a melting point between 1350 and 1500°. Finally, when \(M < 1.6\), the ash should be considered readily fusible, with a melting point below 1350°.

For all the analyzed ash samples, the value of \(M\) proves to be considerably less than 1.6, and, consequently, the ash must be recognized as readily fusible.

It should be noted that hydraulic properties may be ascertained for the ash of coal No. 7, since the hydraulic modulus in this case will be:

\[ \frac{\mathrm{CaO}+\mathrm{MgO}+\mathrm{K_2O}}{\mathrm{SiO_2}+\mathrm{Al_2O_3}+\mathrm{Fe_2O_3}} = \frac{51.92}{25.82} = 2.01. \]

In low-temperature distillation, the greatest yield of primary tar was 13.8% relative to dry coal (sample No. 5); for the most part it was much less.

As a result, the data on the studied samples allow these brown coals to be regarded as a fuel of low grade, of local significance. In this respect they are partly being used in the city of Achinsk¹).

¹) In 1931, the Trade Union opened an operating adit near the city of Achinsk,

Sapropelites occurring in brown-coal seams in bands from 0.1 to 1.55 m in thickness are, in some samples, characterized by a high ash content—more than 48%—and in this case, given their density, may be assigned to bituminous shales. The yields of primary tar for the various samples vary over wide limits; the highest yield is 18.4% on dry coal for sample No. 31, for which the amount of ash is the lowest.

The semicoke obtained from all sapropelite samples is non-caking.

Sapropelite formations are most developed in the area of the village of Staraya Sobolevka, where, in the drift named after the First of May, two bands of sapropelite with a total thickness of about 1 m occur in the brown-coal seam. From these bands, samples of brown coal and sapropelites were taken in large quantities for more detailed study.

Brown coal. Drift named after the First of May, from the face 40 m from the mouth of the drift; thickness 1.2 m. The sample was taken on 22.I.35.

Analysis: given in Table 3.

Table 3.

During distillation in a Fischer retort the following was obtained (on dry coal):

Thus, this brown coal is close in its properties to the other brown coals of the region and, being only slightly bituminous, apparently does not represent any significant value from a technological standpoint.

Sapropelite. Drift named after the First of May. Sample No. 1. Lower band from the face 40 m from the mouth of the drift. The sample was taken on 22.I.35. The sapropelite, received with a working moisture of 24.7%, consists of dense pieces of dark-brown color with clearly expressed stratification. Layers of sapropelite from 2 to 5 mm thick are separated by interlayers of rock. On the surfaces of contact between the layers, remnants of plant material in the form of flat carbonized ribbons have been preserved in considerable quantity. As the sapropelite dries, its marginal parts, which dry faster, warp and separate from the rock interlayers. Along the rock interlayers the sapropelite splits easily; in a direction perpendicular to the layers, its crushing is extremely difficult, since, despite its considerable hardness, it is not brittle.

Technical and ultimate analyses of the sapropelite gave the results presented in Table 4.

Table 4.

Crucible coke in the form of a powder.

Compared with the Barzas sapropelite of deposit III, the present sapropelite has a lower ash content and an increased content of volatile matter, oxygen, and free hydrogen (the latter—5.64% instead of 3.86% in the Barzas sapropelite).

A very valuable property of the Sobolev sapropelite should be considered its complete non-sintering during semicoking.

To determine the tar yield, 25 g of coal were distilled from a Fischer aluminum retort. The result (on dry coal) is given in Table 5.

Table 5.

The tar is a mobile liquid of dark-brown color. In contrast to the tar of the Barzas and Kansk sapropelites, the tar under study has a considerably less pungent odor. The tar separates from water at room temperature very slowly. The semicoke obtained is a black powder.

Sapropelite. Sample No. 2. Upper seam. The sample was taken on 22.I.35, 40 meters from the mouth of the adit.

The proximate analysis is given in Table 6.

Table 6.

Crucible coke—powdery.

Consequently, the upper seam of sapropelite contains more volatile matter.

Semicoking of 25 g of sapropelite (sample No. 2) gave the results (on dry coal) presented in Table 7.

Table 7.

For a more detailed study of the primary tar and the products of its distillation, several kg of sapropelite (sample No. 2) were subjected to semicoking. Semicoking was carried out in a cylindrical horizontal retort heated by a gas burner. The sapropelite for distillation was ground to pass through a sieve with openings of 0.5 mm.

The retort was charged with 2 kg of ground sapropelite. Distillation was conducted at such a slow rate that its total duration was about 7 hours. The yields of distillation products (on dry coal) are shown in Table 8.

Table 8.

Figures 1, 2, and 3 give, for different periods of distillation, the yields of gas (Fig. 1), the content of CO₂ and CₙHₘ in the gas, and the dynamics of the change in the calorific value of the gas, the determination of which was carried out in a Junkers calorimeter.

A very characteristic feature is the high content of CO₂ in the gas, which reaches 50% in the third hour.

In distillations of 2 kg of sapropelite, the yield of tar was lower than in the Fischer retort by 2½–3%. The semicoke remains unsintered.

Fig. 1.

The average sample of semicoke from all the distillations was subjected to analysis. The results are given in Table 9.

Table 9

Condensate water. The freshly separated water has a light-yellow color, which on standing changes to orange and then to brown. The reaction of the water is alkaline; the odor is sharp and unpleasant. Specific gravity at 15°C: 1.0068. Ammonia content: 8.2 g/l; content of bases: 5.12 g/l; phenol-cresol content: 4.1 g/l.

Primary tar. Moisture, 2.5%. \(d_{30}^{0}\)—0.8811. Viscosities at

1. Izvestiya TII, vol. 57, issue 2.

Fig. 2.

Fig. 3.

20° by Engler: 1.825; at 50°—1.333. Flash point in the Abel-Pensky apparatus: 26°. Ultimate composition:

\[ \mathrm{C}—83.71\%,\quad \mathrm{H}—10.79\%,\quad \mathrm{O}+\mathrm{N}+\mathrm{S}—5.50\%. \]

Dust and carbides . . . 0.07%
Asphaltenes . . . . . . 0.52%
Carboxylic acids . . . 0.59%

Phenols . . . . . . . . 8.31%
Bases . . . . . . . . . 2.88%
Paraffin . . . . . . . . 9.21%

Engler distillation of 100 cubic cm of dry tar is presented in Fig. 4. Three kg of raw tar were distilled from an iron cube. The following fractions were collected¹: up to 200°—crude gasoline; from 200–300°—crude heavy kerosene.

Fig. 4.

The yield of the gasoline fraction was 15.15%, its specific gravity 0.788. The yield of the kerosene fraction was 12.69%, sp. gr. 0.873; residue—51%. Water—20.9. Losses—0.26%.

The considerable percentage of water is explained by the above-mentioned property of the tar—its poor separation from water. The yield of gasoline calculated on dry tar was 19.18%, and that of kerosene 16.0%.

To remove phenols and bases, the fractions were washed successively with solutions of alkali and sulfuric acid, distilled by Engler, and their ultimate composition was determined. The distillation data are given in Fig. 5 (gasoline) and Fig. 6 (kerosene).

The ultimate composition of the gasoline is as follows: H—13.15%, C: 84.45%, O + N—2.45%.

The same for kerosene: H—12.77%, C: 85.07%, O + N—2.16%.

In order to characterize the unsaturation of the gasoline and kerosene fractions, their iodine numbers were determined by the Margosches method. For the gasoline fraction the following were obtained: 1) 119.1; 2) 120.6. Similarly, for the kerosene fraction—1) 97.1; 2) 92.9.

Subsequently, the gasoline and kerosene fractions were carefully distilled into narrower fractions, which were then treated successively with 80 and 90% sulfuric acid to remove unsaturated compounds. The results are given in Table 10.

Table 10.

Fig. 5.

Fig. 6.

After the aniline points had been determined in the individual fractions, the fractions were then treated with 99% sulfuric acid until the change in volume ceased, and the aniline points were determined again in the fractions. Then the content of aromatic, naphthenic, and paraffinic hydrocarbons was calculated¹. The results are given in Table 11.

Table 11.

Group composition by hydrocarbons of the various fractions.

The bases and phenols separated during washing were subjected to investigation insofar as the available amount of phenols and bases permitted.²)

After purification of the phenols, their steam distillation, extraction with ether, and removal of the ether, 47.6 g of phenols were obtained. The phenols were separated into fractions:

I—up to 205,

II from 205—225 (at residual vacuum 155—175°),

III “ 225—250 ( “ “ “ 175—195°),

IV “ 250—465 ( “ “ “ 195—230°)

and a residue.

The distillation data are given in Table 12.

Table 12.

The bases, after separation from the sulfuric-acid aqueous solution (previously extracted with benzine), subsequent dissolution in 20% sulfuric acid, treatment with steam, isolation and distillation from a Wurtz flask (in all, 14 g were obtained in this way), are a somewhat viscous liquid of light-yellowish color, with a specific gravity at 15°C of 0.950.

Conclusions.

1. The sapropelite of the Sobolev deposit, with a seam thickness of 1.1 m and reserves of not less than 50 million tons, with shallow occurrence (150 meters), the location of the deposit near the Tomsk railway, and the revealed distinctive feature that it does not cake at all during semicoking, must be recognized as a valuable raw material for obtaining liquid fuel.

2. The industrial yields of tar may apparently be estimated at not less than 18—20% on the working raw material.

¹) Because of the small amount of the fraction up to 95°, only the unsaturated hydrocarbons were determined in it.
²) The investigation was carried out by former student, now engineer B. N. Peshkova.

1. A considerable percentage of unsaturated compounds, especially in the gasoline fraction, on the one hand, and the relatively small yield of the gasoline fraction, on the other hand, indicate that the most expedient technical process for processing the sapropelite of the Sobolev deposit is semicoking followed by hydrogenation of the primary tar.

2. The brown coals of the region should be regarded as an energy raw material, to be used above all as a local fuel.

LITERATURE

1. Korovin M. K. The Chulym–Yenisei coal-bearing basin. Bulletin of the West Siberian Geological Exploration Administration, 1931, issue 3.

2. Korovin M. K. The Achinsk sapropelite district according to new data of 1933. Bulletin of the West Siberian Geological Exploration Trust, 1933, issue 5.

3. Dorofeev P. Barzas or Achinsk? For Coal of the East, 1932, No. 21–22.

4. Kuryndin K. The Achinsk sapropelites should be investigated. For Coal of the East, 1932, No. 10.

5. K. S. Kuryndin and S. G. Kastelyanskaya. Chemical composition of shale gasoline and tar of the Achinsk sapropelites. Kh. Tv. T., vol. 7, issue 9, 1935.

1. Transactions of Grozneft, 1931, pp. 77 and 125. ↩↩↩↩