Content of Individual Sulfur Species in Coals from the Zabituy and Golovinsk Districts of the Irkutsk Basin
Abstract Generated abstract
This study examines the distribution of sulfur forms in caking coals from the Zabituy and Golovinsky districts of the Irkutsk Basin, including samples from the Vladimir mine area. Using proximate and ultimate analysis, the Powell-Parr method for mineral sulfur, ash sulfur determination, and Eschka analysis of crucible coke, the authors distinguish total, combustible, noncombustible, volatile, nonvolatile, mineral, and organic sulfur. The samples show substantial variation in total sulfur, from low-sulfur Golovinsky coals to high-sulfur Zabituy and Vladimir samples, while most coals display good caking behavior but low coke yield because of high volatile matter. The results indicate that mineral sulfur often predominates, although one Zabituy sample contains mainly organic sulfur, suggesting a practical limit to sulfur reduction by mechanical beneficiation.
Full Text
I. V. Gebler and A. I. Shustova.
Content of Individual Forms of Sulfur in Coals of the Zabituy and Golovinsky Districts of the Irkutsk Basin
The Zabituy district is situated west of Cheremkhovo, near the Zabituy railway station. This district has been very little studied with respect to the development of coal seams and the properties of the coals. Exploration in 1926 established here only the presence of three coal seams: an upper seam with a thickness of 3–3.5 m, a middle seam of 2 m, and a lower seam of 3.5–4 m1.
The Golovinsky district, to which the district of the Vladimir mine also belongs, is located adjacent to the Zabituy district and has been studied even less.
For the coals of all the districts indicated, it has been established only that they are caking coals, in which respect they differ from the coals of the working mines of the Irkutsk Basin, for which caking capacity is either entirely absent or expressed only weakly. In addition, a sometimes considerable sulfur content has been observed for the Zabituy and Golovinsky coals.
At the suggestion of the trust “Sibvostugol,” some Zabituy and Golovinsky coals were examined in the Coal-Chemical Laboratory of the Siberian Chemical-Technological Institute for the content of individual forms of sulfur. For this purpose, samples of run-of-mine coal from the middle and lower Zabituy seams and several seam samples of coals from the Golovinsky district, including from the district of the Vladimir mine, were delivered to the laboratory2.
All the coal samples are characterized as follows.
Zabituy coals
No. 1. Run-of-mine coal. Mixture of crushed coal of the class > 50 mm from the middle and lower seams.
No. 2. Run-of-mine coal. Middle seam. Fines, class 1–0 mm.
No. 3. Run-of-mine coal. Lower seam. Fines, class 1–0 mm.
Vladimir coals
No. 4. Vladimir deposit. Thickness 0.93 m. Along the adit, the distance from the daylight surface is 89 m.
No. 5. Vladimir deposit. Upper bench. Thickness 0.55 m. Average thickness 0.93 m.
Golovinsky coals
No. 6. Golovinsky deposit. Upper bench. Thickness 0.85 m. Distance from the daylight surface 413 m.
No. 7. Golovinsky deposit. Lower bench. Thickness 0.85 m. Distance from the daylight surface 413 m.
The results of the ultimate and proximate analysis are given in the following table:
| Sample No. | \(W_l\) | \(A_c\) | \(S^{c}_{\text{tot.}}\) | \(V^{?}\) | \(C^{?}\) | \(H^{?}\) | \(N^{?}\) | \(O^{?}\) | Character of the coke |
|---|---|---|---|---|---|---|---|---|---|
| 1. | 3,97 | 13,43 | 3,36 | 47,84 | 76,79 | 6,05 | 1,24 | 12,03 | Sintered, fused, dense. |
| 2. | 6,38 | 15,22 | 0,77 | 33,59 | 77,46 | 4,98 | 2,08 | 14,62 | Sintered. |
| 3. | 6,20 | 19,77 | 0,77 | 34,76 | 78,26 | 4,96 | 2,44 | 13,40 | Caked. |
| 4. | 5,98 | 7,24 | 3,63 | 47,31 | 77,14 | 5,4[[unclear: final digit]] | 1,60 | 11,45 | Sintered. |
| 5. | 9,22 | 8,26 | 1,19 | 40,49 | 76,94 | 5,60 | 1,59 | 14,05 | Sintered. |
| 6. | 10,31 | 8,09 | 0,66 | 42,48 | 76,44 | 5,18 | 1,02 | 16,05 | Sintered. |
| 7. | 10,82 | 12,30 | 0,66 | 42,39 | 77,52 | 5,37 | 1,70 | 14,64 | Sintered. |
Pyritic sulfur, together with sulfate sulfur, i.e., in total mineral sulfur, was determined by the Powell-Parr method1, which consists of the following. One gram of crushed coal is shaken for two hours at room temperature with 100 cu. cm of nitric acid (sp. gr. 1,12); the precipitate is filtered off and washed with water until the reaction for iron disappears. The solution is evaporated to dryness; the dry residue is dissolved in hydrochloric acid and filtered from the insoluble precipitate; iron is precipitated in the filtrate with ammonia. In the filtrate obtained after separation of the ferric oxide hydrate, acidified with hydrochloric acid, \(SO''_4\) is precipitated with barium chloride.
To determine sulfur in the ash, the latter was decomposed in an alkaline melt with the addition of \(KNO_3\); the melt was extracted with water, the precipitate was filtered off, and in the filtrate, acidified with hydrochloric acid, \(SO''_4\) was precipitated in the usual manner.
Ash sulfur, recalculated to dry coal, is shown as noncombustible sulfur.
In the coke, sulfur was determined by the Eschka method. The coke sample for sulfur determination was obtained by coking the coals in a platinum crucible under the conditions used for determining volatile matter. Coke sulfur, recalculated to dry coal, is shown as nonvolatile sulfur.
Combustible and volatile sulfur is given as the difference between total and noncombustible, respectively nonvolatile, sulfur; and organic sulfur—as the difference between total and mineral sulfur (pyritic and sulfate).
The results of the determinations are brought together in the following table, where the sulfur content is given relative to the dry substance:
| Sample No. | Total sulfur % | Sulfur in coal ash % | Combustible sulfur % | Noncombustible sulfur % | Sulfur in coke % | Volatile sulfur % | Nonvolatile sulfur % | Mineral sulfur % | Organic sulfur % |
|---|---|---|---|---|---|---|---|---|---|
| 1. | 3,36 | 0,66 | 3,27 | 0,09 | 2,55 | 1,86 | 1,50 | 1,19 | 2,17 |
| 2. | 0,77 | 1,55 | 0,54 | 0,23 | 0,72 | 0,37 | 0,40 | 0,58 | 0,19 |
| 3. | 0,77 | 1,19 | 0,54 | 0,23 | 0,73 | 0,40 | 0,37 | 0,59 | 0,18 |
| 4. | 3,63 | 1,36 | 3,53 | 0,10 | 3,77 | 1,28 | 2,35 | 2,29 | 1,34 |
| 5. | 1,19 | 1,26 | 1,08 | 0,11 | 1,06 | 0,42 | 0,77 | 0,75 | 0,44 |
| 6. | 0,66 | 2,40 | 0,47 | 0,19 | 0,53 | 0,28 | 0,38 | 0,38 | 0,28 |
| 7. | 0,66 | 0,07 | 0,65 | 0,01 | 0,54 | 0,26 | 0,40 | 0,38 | 0,28 |
All the coals investigated, with the exception of the fine screen-size classes 1–0 mm of the run-of-mine Zabituy coals (samples Nos. 2 and 3), showed good caking ability, and it is possible that they can yield a usable coke, as may be judged from the character of the beads obtained during coking in a crucible. At the same time, owing to the high content of volatile matter, the coke yield proves to be low, approximately from 50 to 60% for the various coals.
With respect to sulfur content, the coals, as can be seen, exhibit considerable diversity. Some of them are low-sulfur (Nos. 6 and 7), while in others the sulfur content is significant. The amount of noncombustible sulfur relative to the total in the various coals ranges approximately from 3 to 30%.
In the coke (in crucible coking), about 50% of all the sulfur remains for the Zabituy coals; for the Golovinsky coals—somewhat more; and in sample No. 4 the amount of nonvolatile sulfur amounted to 65% of the total sulfur.
The amount of organic sulfur is predominant only for coal sample No. 1, and in this case it constitutes the limit to which, with a known approximation, the sulfur content may be lowered by means of mechanical beneficiation.