I. V. Gebler.

On the Characterization of Certain Siberian Brown Coals with Respect to Bitumen Content

The bitumens of brown coals, as is known, consist of resins and waxes. Brown-coal, or so-called “mineral wax,” finds considerable application in the manufacture of textile soaps, leather finishes, and is also used in certain branches of the small-scale chemical industry producing copying papers, typewriter ribbons, etc.

The value of brown-coal bitumen thus depends on the wax content, which usually predominates in the composition of the bitumen; nevertheless, its relative amount may vary very greatly. The total content of bitumen extracted with suitable solvents fluctuates within very wide limits—from 1–2% to 17–18% and more.

The amount of extractable bitumen and the wax content in it determine the value of brown coals for extraction production.

This type of industry is most highly developed in Central Germany. The bituminousness of the brown coals of the USSR has been studied by P. Ya. Samoilovich with respect to the Ukrainian coals of the Aleksandriya district, the Semenovskoye deposit¹); the same coals were later investigated by Prof. V. I. Kuznetsov, I. A. Kopelnovich, and others²).

These investigations established the suitability of brown coals from certain areas of the Aleksandriya district for obtaining mineral wax. The amount of extractable bitumen for various coals ranged from 8 to 20%, with the resin content in the crude bitumen from 6.74 to 40%. As the best solvent, alcohol-benzol was established in the ratio 1:1.

The brown coals of Siberia, deposits of which are known in many districts, have, generally speaking, been studied very little, and with respect to their bituminousness have not been investigated at all. In this connection it was of interest to subject certain brown coals to examination in the indicated respect.

It should be noted that, in the absence in most cases of developed mines at brown-coal deposits, obtaining systematic and fresh samples proved difficult; it was necessary to use collection samples from prospecting work from shafts and boreholes (cores), and even museum samples, which, of course, had the disadvantage of insufficient freshness of the samples.

As regards the method of investigation, it was adopted as the same as that indicated in the above-mentioned works on the investigation of Aleksandriya coals. Coals with the moisture content of the analytical sample, ground so as to pass through a sieve with openings of 1/4 mm, were subjected to exhaustive extraction in a Soxhlet extractor. After distilling off the solvent, its residue was removed in vacuum at the temperature of a water bath.

As the solvent, alcohol-benzol in the ratio 1:1 was always used.

¹) “Chemistry of Solid Fuel,” 1931, No. 9, p. 62.
²) Bull. Kharkov Scientific Research Coal-Chemical Institute “Coke,” 1935, No. 3, p. 48.

The determination of resin and wax in the extract obtained was carried out by the Graefe method.

The results of the determinations are given below with respect to the individual districts from which samples of brown coals were obtained.

Tomsk District. From this district the following brown coals were studied: Rezhetsky and from the deposit near the village of Yar. The first of these occurs near the village of Rezhnitsy, 12 kilometers from Tomsk. This deposit was first investigated by the geologist A. P. Smolin in 1920, on assignment from the Tomsk Provincial Economic Council. Three seams were found here, the thickness of the first being about 1.1 m, and of the second from 1.3 m to 3 m.

Rezhetsky brown coal should be classed as lignite; it is dark brown in color, with a clearly expressed wood structure. In low-temperature distillation, according to N. L. Chizhevsky,¹) it yields on average about 7.6% (on an anhydrous coal basis) of primary tar.

A sample of Rezhnitsy lignite, taken from the collection of the Petrographic Cabinet of the Tomsk Industrial Institute (which had lain there for a long time), was characterized by the following figures:

The yield of bitumen for this sample (on dry coal) was 2.3%, i.e. it proved so small that further investigation of the bitumen with respect to its content of resins and wax was of no interest.

The Yar deposit of brown coal was investigated in 1932.²) It is located on the Tom River, 40 km above Tomsk and 4 km above the village of Yar (at the confluence of the Boitsov brook with the Tom River). The brown-coal seams occur in Tertiary deposits of gray-white clays with plant remains. The main coal seam has an average thickness of 1.4 m and consists of two benches separated by a clay interbed averaging 0.07 m, which was exposed by means of an adit driven 10 m above the mouth of the brook. Reserves were not determined.

Coal samples were taken as channel samples from the above-mentioned exploratory adit, 13.65 m long: 1) from 0 to 5 m; 2) from 5 to 10 m; and 3) from 10 to 13.65 m. Analysis of these samples gave the following results:

As may be seen, for all samples the composition of the combustible matter proves to be close, and, consequently, the character of the seam is maintained along the entire length of the adit.

On the basis of these samples, Yar coal, as a brown coal, may be considered satisfactory in its qualities and suitable as a local fuel.

The indicated analyses were made in 1933, and the samples themselves were lost. It was not possible to obtain new samples because of a landslide that had filled the adit, and therefore, for the determination of bitumen in the Yar brown coal, it was necessary to take a sample of it from the Regional Museum.

¹) Bulletin of Siberian Engineers, vol. V (1923), No. 1, p. 30.
²) Bulletin of the West Siberian Geological-Prospecting Trust. 1933, issue 2–3, p. 57.

The results of the analysis of this sample are as follows:

It differs from the preceding ones by a very high ash content, and also by a large amount of volatiles. However, despite the very high ash content, the yield of bitumen for this coal proved to be large, namely 4.6% on dry coal, or 17.8% on combustible matter. The large amount of ash may be considered accidental, judging from the preceding samples; if one provisionally adopts the ash content with which ordinary coal can be issued as 20%, then the yield of crude bitumen will be 13.2%. The amount of wax in the crude bitumen was found to be 47.80%, and, consequently, the yield of wax from coal with 20% ash would be 6.3%, which, apparently, may already be considered sufficient for production purposes. Therefore the brown coal from the Yarsk deposit deserves further, more detailed study with regard to broader sampling, determination of reserves, and chemical investigation. In exploiting the deposit, its proximity to the Tom River makes it convenient and cheap to deliver the coal to Tomsk by water.

Chulym-Yenisei basin. From this basin, brown coals of the Achinsk and Sobolevsk districts were investigated; for this purpose samples were obtained from boreholes and prospecting adits from exploration parties, and only in one case from the operating adit of the Achinsk Construction Union, since only here was there a small production of brown coal for the needs of the city of Achinsk; in the rest of the basin it is not exploited. The results of analyses of the brown coals are given in the following table:

Thus, the bitumen yields for all coal samples proved insignificant.

Kansk Basin. This still little-studied basin, crossed in a west-to-east direction by the Tomsk Railway from Kamarчaga station to Taishet station, according to Prof. M. K. Korovin’s definition¹ is known mainly for its brown energy coals. Here the Balai deposit had already been worked for quite a long time, but only on a small scale; at present the Irsha mine near Zaozernaya station is being exploited, located 3 km south of the railway line; the coal extracted is used for firing locomotives of the Tomsk Railway. This coal is almost completely black in color, but must be assigned to brown coals on the basis of a number of characteristics, namely: with a solution of caustic potash it gives a considerable yield of humic acid; the alcohol-benzene extract shows no fluorescence; oxygen content up to 30%; and high initial moisture.

Commercial samples of Zaozerny coal were taken from the laboratory of the Tomsk Railway, where at that time² they were being subjected to systematic analysis as locomotive fuel.

For three ordinary samples, the results of the analysis (laboratory of the Tomsk Railway) are as follows:

For these coals the bitumen yields proved insignificant, namely:

Sample 1 . . . . . 2,4% (on dry coal)
” 2 . . . . . 2,8% ” ” ”
” 3 . . . . . 2,4% ” ” ”

Omsk district. In the autumn of 1935, samples of brown coals were obtained from the geological prospecting party working in the Tara okrug, Omsk district. The analyses of these coals are given below.

Thus, all the brown coals investigated, with the exception of the coal of the Yar deposit near Tomsk, when directly extracted with alcohol-benzene, give low yields of bitumen and therefore are of no interest from the standpoint of obtaining mineral wax from them.

¹ Coal-bearing regions of Siberia, 1933, p. 72.
² This refers to 1935.