Factors Determining the Selection of Rational Ventilation Schemes for Kuzbass Coal Mines

A. F. Karataev

General Remarks

The selection of a rational ventilation scheme for the coal mines of Kuzbass is an exceptionally important and, at the same time, complex and difficult task, because the correct solution of this question depends on a number of geological and mining-engineering factors, on the physicochemical properties of the coal and of the enclosing rocks.

The basis for selecting a rational ventilation scheme for the coal mines of Kuzbass must be a comprehensive consideration of the conduct of all mining operations and ventilation.

The coal deposits of Kuzbass are represented by suites of seams containing a large number of predominantly thick seams of inclined and steep dip. Individual seams within suites are close together. All thick seams, and some seams of medium thickness as well, are prone to spontaneous combustion. Almost all coal seams are gas-bearing and dangerous with respect to dust. Therefore, a rational ventilation scheme can be selected only through a comprehensive resolution of the following questions: opening and development of the mine field, the mining system, and mine ventilation. These questions mutually influence one another.

A rational ventilation scheme must, above all, be as safe and reliable as possible, but at the same time economical.

The exceptional complexity of the conditions under which the coal deposits of Kuzbass are worked may sometimes compel one to abandon economy in the expenditure of funds for ventilating mine workings. For example, in cases when it is impossible to ensure reliable ventilation and to achieve conditions that preclude the occurrence of gas explosions and fires, or at least reduce their number.

For gassy mines, the selection of a rational ventilation scheme is impossible without knowledge of the gas inflow of individual workings, sections, and the entire mine, because the gas inflow determines the quantity of air supplied to the mine and its distribution among the workings. Thus, for example, at Mine No. 1 of the Kuibyshevugol Trust, with the existing method of opening the mine field and the location of the shafts, the central ventilation scheme proved irrational (Fig. 1). The approach of the mining operations to the closed part of the seams, where gas emission is at its maximum, led to a sharp increase in the quantity of air required for ventilating the mine, while the paths of air movement to this area proved to be the longest. With the small cross-section of the workings and their convergence, the mine depression also increased considerably. Consequently, the required power of the ventilation installation also increased. The designed ventilation installation had proceeded from the assumption that the mine would be of the second category with respect to gas, whereas in fact it proved to be—

...proved to be super-category, was unable to ensure the delivery of the required quantity of air into the mine under conditions that had not been taken into account in due time. As a result of the shortage of air, the working face was often gas-polluted, and the mine operated intermittently. The adoption of a flank (diagonal) ventilation scheme and a certain reconstruction of the ventilation installation ensured normal operation of the mine.

This example indicates that, in a mine with a high gas-bearing capacity of the seams and with its uneven distribution among the seams and within seams inside the mine field, the gas-bearing capacity of the seams is the decisive factor in the choice of a rational ventilation scheme. In addition, this example underscores the mutual influence between the method of opening up and the ventilation scheme.

Fig. No. 1. Gas map of Mine No. 1, horizon +85 m.

If the main crosscut had been located along the line of maximum concentration of gas emission, even with the adopted ventilation scheme this would have substantially improved ventilation, because, given great lengths of workings, mining operations would have been carried out in areas with reduced gas emission. This emphasizes the influence of the gas-bearing capacity of seams on the method of opening up the mine field.

When mining coal seams prone to spontaneous combustion, hazardous in terms of dust, and gas-bearing, the interdependence between the method of opening up, the mining system, and the ventilation scheme proves still stronger.

In order properly to take into account the influence of coal’s tendency to spontaneous combustion on the choice of a mine ventilation scheme, it is necessary to have a clear understanding of the causes and, especially, of the conditions favorable to the occurrence of endogenous fires. Knowing the causes and conditions that contribute to the occurrence of endogenous fires, one can select a mine ventilation scheme that eliminates the influence of the principal factors leading to the outbreak of endogenous fires. At present it may be considered established that the main cause of spontaneous combustion of coal is the oxidative process of coal with atmospheric oxygen. Under the action of rock pressure, coal is crushed. This crushing increases the area of contact between the coal and the oxygen of the air, which, in spontaneously combustible coals, leads to intensification of the oxidative process. Oxidation of coal by the oxygen of the air is accompanied by the release of heat. If air also reaches the crushed or fissured coal, and the heat formed as a result of oxidation is not removed, then after a certain time...

self-heating is observed, which may pass into the combustion of coal. For the process of self-heating of coal to pass into spontaneous combustion, a certain interval of time is required, which depends on the properties of the coal and on the surrounding conditions. If measures are not taken to stop the process of self-heating, an endogenous fire may arise.

It follows from the foregoing that three conditions are necessary for an endogenous fire to occur:

1. The presence of a substance capable of spontaneous combustion, i.e., self-igniting coal, mainly crushed and fissured.
2. The presence of a source of oxygen, i.e., an air current.
3. Time sufficient for the process of self-heating to take place and pass into spontaneous combustion.

The intensity of spontaneous combustion of coal, and, consequently, the fire hazard, depend on the totality of the physicochemical and petrographic properties of the coal, the geological conditions of occurrence, and mining-engineering factors. These factors, apart from the mining-engineering ones, cannot be changed, because they are inherent in the nature of the coal and the deposit. The practice of mining operations shows that by a certain combination of mining-engineering factors, i.e., the method of opening, the systems of mining, the ventilation regime, and the intensive and correct development of extraction and preparatory work, it is possible to avoid, or at least reduce, the number of cases of endogenous fires.

The principal mining-engineering conditions promoting the occurrence of endogenous fires in the mines of Kuzbass when working seams of coal prone to spontaneous combustion are:

1. Incorrect organization of mining operations, i.e., the use of irrational caving mining systems, which lead to large or concentrated losses of coal and to the creation of favorable conditions for air leakage through the worked-out space—the extraction of panels by direct advance.
2. An incorrect ventilation regime, i.e., a disturbance of the normal movement of air as a result of imperfect isolation of the worked-out space, large depressions, and incorrect distribution of air and depressions among the workings, which leads to large air leakage through the worked-out space and protective pillars.
3. Tectonic disturbances.

With an irrational mining system and an incorrect ventilation regime, in the presence of tectonic disturbances, endogenous fires may arise, and do arise, even in seams little prone to spontaneous combustion; and, conversely, with a rational mining system and a correct ventilation regime they do not arise even in seams whose coals have a high propensity for spontaneous combustion.

It follows from the foregoing that a rational ventilation scheme can be selected only through a comprehensive solution of the following questions:

1) opening and preparation of the mine field for longwall extraction;
2) the order of extraction of panels;
3) selection of the mining system;
4) the ventilation regime of the mine.

Opening and Preparation of Mine Fields in Kuzbass for Longwall Extraction

The method of opening and preparation (the order of working) of a mine field largely predetermines the ventilation scheme. Therefore, before proceeding to an analysis of existing mine ventilation schemes, it is necessary—

It is necessary to make a brief review and analysis of the methods used for opening and preparing the mine fields of the coal mines of Kuzbass.

Under Kuzbass conditions, the opening of the mine fields of coal mines is usually carried out by two centrally paired shafts with level crosscuts every 80–100 m vertically, regardless of the conditions of seam occurrence. In this way the mine fields have been opened at Mine No. 2, which works a series of steeply dipping seams; Mine No. 1, which works series of steeply dipping and inclined seams; Mine No. 3 (in Leninsk-Kuznetsk), which works a series of gently occurring, slightly dipping seams; and Mines No. 4 and No. 5 in Anzhero-Sudzhensk, which work series of highly disturbed seams of various thicknesses and angles of dip.

This vertical scheme of opening provides the greatest convenience and reliability in the movement of loads, equipment, and air for ventilating mine workings under any conditions.

Kuzbass practice confirms these advantages of opening mine fields by shafts with level crosscuts. The centrally paired arrangement of shafts within mine fields, however, dictated by the convenience of locating surface structures and by attaining the minimum dimensions of safety pillars, contradicts favorable ventilation conditions. This arrangement of shafts makes it necessary to use a central ventilation scheme, which under Kuzbass conditions is unacceptable because of significant gas emission and the difficulty of maintaining workings in serviceable condition owing to high rock pressure. In Kuzbass the flank (diagonal) ventilation scheme and its variants have become widely adopted. Therefore, as a rule, at all the above-mentioned mines one of the centrally paired shafts is neutral in the ventilation scheme, while special ventilation workings (shafts, winzes, furnaces) are driven on the flanks.

The horizontal scheme of opening mine fields under Kuzbass conditions is most often carried out by means of concentration or group, and more rarely panel, drifts and district (intermediate) crosscuts. Concentration or group drifts are driven from the main crosscut along the lower seam of the series or, on the footwall side of the series of seams being worked, through rock.

From the group drift to the upper seam of the series, district crosscuts are driven at distances of 150–200 m from one another in one-sided extraction and 300–400 m in two-sided extraction. Such an opening scheme makes it possible to work extraction districts in any direction—from the mine shaft and toward the mine shaft—and to isolate a district easily in the event of endogenous fires. Between extraction districts, coal pillars 10 m wide are left for the full height of the level. Cutting through them with workings is prohibited. For ventilation of an extraction district of the lower horizon, at a distance of 4–5 m below the haulage (level) drift of the ventilation horizon, a so-called lower drift is driven. The remaining solid pillar reliably isolates the extraction district from old workings of the ventilation horizon, thereby eliminating the need to preserve the haulage drift after extraction of the district for purposes of ventilation when working the next lower horizon. This makes it possible to carry out complete extraction of all over-drift pillars.

The horizontal scheme of opening described above corresponds to the particular features of the Kuzbass deposits, the conditions of seam occurrence, the tendency of its coals to spontaneous combustion, and the gas and dust content of the seams; therefore it is entirely rational.

Order of extraction of panels

Extraction of the mineral within extraction panels may be carried out in the advancing or retreating direction. From the standpoint of ventilation, in all cases when working with caving, retreating extraction is the most rational; and in seams prone to spontaneous combustion it is the only permissible method and the one that ensures the reliability of ventilation. In this case the main entry, which throughout the entire period of extraction remains in a mass of coal untouched by stoping operations, is well preserved when the coal is stable; whereas the ventilation entry, which on one side has a protective pillar and not a mass of coal, is in somewhat worse conditions than the main—lower-level—entry. Finally, during the entire period of extraction of the panel, between the main entry and the ventilation entry there is a mass of untouched coal, which prevents leakage of air as it moves into the longwall. The number of entry-side pillars is smaller with retreating extraction, and their service life is shorter; therefore coal losses here are also smaller. The reduction of coal losses undoubtedly lowers the possibility of the occurrence of endogenous fires. Retreating extraction of mine fields contributes to successful and, moreover, more rapid localization of fires that have arisen, since in this case insulating stoppings can be erected as close as possible to the seat of the fire in the main and ventilation entries, thereby reducing the volume of the isolated area and the losses of coal. After the stoppings have been erected and a cut-off furnace has been driven at some distance from them, extraction can again be carried out. The advantages of retreating extraction are increased when minus entries are driven. In this case, throughout the entire period of working the panel, the minus entries are in more favorable conditions, because they are separated from the goaf not by small, crushed pillars but by a continuous strip of uncrushed coal. These strips prevent leakage when the air current moves along the ventilation (minus) entries, and the absence of cracks in these strips reduces the possibility of endogenous fires. Retreating extraction in working panels finally makes it possible to carry out reliable and timely preventive stowing of the worked-out space.

The exact opposite is observed with advancing extraction. In this case the main (level) entry is subjected to considerable pressure, because the mass of untouched coal is located only on one side, while on the other side there is worked-out space, from which the entry is separated by small pillars. The ventilation entry, however, is located in the worked-out space and is separated from it only by small pillars. It is difficult to preserve it in thick seams, and with steep dip it is even impossible. As extraction of panels approaches the boundary, the entries become substantially flattened as a result of rock pressure, which leads to an increase in the depression required to move the necessary quantity of air. The pillars near the entries and the stoppings between them are crushed; this disrupts the isolation of the worked-out space and increases air leakage into it. To achieve satisfactory isolation of the worked-out space under these conditions, especially in the development of thick steeply dipping seams, is impossible.

The increase in depression and leakage in the panel, the presence of crushed coal in the worked-out space, and the cracking and crushing of pillars cause endogenous fires to arise, while the use of an effective method of prevention—stowing—before completion of extraction of the entire panel is impossible. The occurrence of a fire leads to the cessation of extraction work in the panel. To the preceding it must also be added that advancing extraction, regardless of the development system, when working with caving—

…may thus in itself cause the outbreak of endogenous fires.

Consequently, when mining coal seams prone to spontaneous combustion, it is advisable to use the retreating method of extraction in mines.

Mining system

All mining systems used in the coal mines of Kuzbass, according to the method of roof control, may be divided into two groups:

1. Mining systems with caving of the roof.
2. Mining systems with stowing of the worked-out space.

Most coal seams in Kuzbass are prone to spontaneous combustion; therefore we shall compare these two groups of mining systems in terms of fire hazard. The first group—mining systems with caving—has in recent years, especially during the years of the Great Patriotic War, become almost exclusively widespread in Kuzbass. These systems provide the main output.

According to data, the majority of fires in Kuzbass (up to 80–90%) arise from spontaneous combustion. The greatest number of fires is produced by mining systems with caving, which lead to large coal losses of the order of 40–50%, and in individual cases 70%. Fires occurring under mining systems with stowing were caused by accidents.

The occurrence of fires with their distribution by seams is presented in Table 1.

Table 1

Underground fires that occurred in the mines of the “Kuzbassugol” combine during the period 1941–1947 (inclusive) from spontaneous combustion

From this table it is evident that the greatest number of fires occurs in seams more than 5 m thick (Moshchnyi, Gorelyi, and IV Internal …).

solutions). This is explained not only by their great thickness and the spontaneous-combustibility of their coals, but also by the use of irrational mining systems.

The dependence of the occurrence of endogenous fires on the time elapsed after mining of sections is presented in Table 2.

Table 2

Dependence of the occurrence of endogenous fires in Kuzbass on the time elapsed from the beginning of section mining

From the data in this table it is evident that the first year after mining gives the greatest number of fires and is the most dangerous with respect to their occurrence. The probability of fires appearing after two years is negligible. The occurrence of fires after this period is observed when upper horizons are undermined and is explained by disruption of the regime established there. The largest number of fires occurs after 4–6 months. This interval of time should be considered the most dangerous.

From the foregoing it follows that, in order to exclude the possibility of endogenous fires occurring in seams with coal prone to spontaneous combustion, it is necessary to carry out complete and rapid extraction of the mineral.

With mining systems using caving, it is impossible to carry out complete extraction of the mineral and to ensure good isolation of the worked-out space; therefore all mining systems with caving are fire-hazardous. In mining seams with coals prone to spontaneous combustion, with caving, isolation of the worked-out space acquires exceptionally great importance. It substantially influences the ventilation regime of the mining system, and in some cases even determines the ventilation regime of the mining system. Achieving perfect isolation of the worked-out space when working with caving is very difficult.

but this difficulty increases, all other conditions being different, as the seam thickness increases.

The perfection of isolation of the worked-out space depends on the properties of the rocks enclosing the seam, the thickness of the seam and its dip angle, the depth of occurrence of the seam, the method of roof control, the order of extraction of the district, the magnitude of the depression required for ventilating the extraction district and its distribution among the workings, and the magnitude of the natural draft. The roof and floor of a thin, gently dipping seam, consisting of viscous clay shales, especially when the floor is prone to “heaving,” provide the best isolation of the worked-out space from the surface. A roof consisting of viscous clay shales has the ability to subside smoothly without a break in continuity during extraction of the seam. The tendency of the floor to “heave” reduces the already insignificant height of the worked-out space, which further promotes subsidence of the roof without breaks in continuity. Such a character of roof settlement does not cause the formation of cracks above the worked-out space, which ensures good isolation of the worked-out space. With a considerable increase in seam thickness, the roof rocks lose the ability to subside smoothly without a break in continuity. Owing to the greater displacement of the roof rocks, cracks are formed, sometimes reaching the surface when the seams occur at shallow depth, which leads to deterioration in the isolation of the worked-out space. A roof consisting of sandstones, even with a small seam thickness, after extraction subsides with the formation of cracks reaching the surface. Sandstones also have a lesser tendency to cake together with time.

If, with gentle dip, only the roof is set in motion during caving, then with steep dip the floor also slips. In this case, when the seam is thick, cracks arise which not only reach the surface at a shallow working depth, but also collapses are formed that disturb the integrity of the surface. For a visual assessment of the influence of the dip angle on the displacement of rocks, we construct the lines of the planes of rock displacement for a longwall 100 m long (Fig. 2). The numerical values of the displacement angles are taken from Tables 2 and 4 of the “Rules for the Protection of Structures from the Harmful Effects of Mining Workings in the Kuznetsk Coal Basin” [2, 6].

The main mass of the Kuzbass rocks enclosing coal seams consists of sandstones. The presence of a considerable amount of sandstone, steep dip, and great seam thickness create the most unfavorable conditions for isolation of the worked-out space. This has a substantial effect on the increase in the number of endogenous fires in seams of steep dip and thickness of more than 5 m, taking into account that, under the existing mining systems, coal losses increase with increasing seam thickness. Increasing the depth of mining in all cases favors isolation of the worked-out space.

Roof control when working with caving is carried out by systematic caving of the roof beyond the working space. This reduces the pressure on the supports of the working space, and they stand better.

Under Kuzbass conditions, in mining systems with long pillars along the strike, with inclined slices, and with horizontal slices, roof control consists in installing special supports at a prescribed spacing and in carrying out caving of the worked-out space behind the special support. The caving spacing—the distance over which roof caving is carried out—is determined by the properties of the roof and floor rocks.

In accordance with the instruction on the application of mining systems at the mines of the Kuzbassugol Combine [3, 6], the following standard types of special support have been established for work with caving:

a) breaker-line support—single-row and double-row;
b) “legs”—coal pillars 2–4 m wide along the entire length of the longwall.

Breaker-line support is used in mining with caving of seams up to 3–3.5 m thick.

In the figure: hard-coal seam boundary;
\(\alpha = 0–25^\circ\), \(\beta = 50–52–53^\circ\), \(\gamma = 65–70–75^\circ\);
\(\alpha = 25–45^\circ\), \(\beta = 39–48–49^\circ\), \(\gamma = 65–70–75^\circ\);
\(\alpha = 45–90^\circ\), \(\beta = 30–34–39^\circ\), \(\gamma = 65–70–75^\circ\).

Fig. 1. Influence of the dip angle on the displacement of rocks

a) single-row breaker-line support is used in seams 2 to 3 m thick when the immediate roof caves readily;
b) double-row support is used when the immediate roof is of medium stability and the seam thickness is 3 m or more.

“Legs” are used:

a) when seam thickness is from 3.5 to 4 m and the roof is weak, not ensuring the preservation of the breaker-line support;
b) when the main roof is of considerable thickness and caves only over large exposures;
c) when the thickness is over 3.5 m and the immediate roof is strong.

Roof control during work with caving in seams with coals prone to spontaneous combustion, by means of breaker-line support, is more rational than control by means of “legs.” The use of single-row breaker-line support in seams no more than 3 m thick and with rocks that cave readily ensures subsidence, which leads to good isolation of the goaf. Mechanical subsidence of the roof increases the advantages of this method of roof control. By destroying all the support—

… behind the ripping-out organ, leads to the complete and rapid caving of the roof over the worked-out space, considerably shortens the time of seating of the faces, and favors preservation of the working space and better isolation of the worked-out space. With machine seating it is possible, though not always, to carry out partial extraction of the props up to 25%, thereby reducing the amount of timber left in the gob. Two-row ripping, in view of its use with a more stable roof, has fewer advantages than single-row ripping. Rocks of medium stability, when caving, form cracks and cavities and settle with greater difficulty, and therefore isolate the worked-out space worse than readily caving rocks.

Control of the roof by means of “knives” is exceptionally unfavorable from the standpoint of preventing the possibility of spontaneous fires. If, with a weak roof, some isolation of the coal left in the “knives” may still be obtained, then with a main roof of considerable thickness, caving only at large exposures, and with a strong immediate roof, this will not be achieved. This method of roof control creates especially favorable conditions for the occurrence of spontaneous fires (where coal losses are concentrated). In the worked-out space a large number of channels for air movement is formed, and the crushed “knives” produce a considerable quantity of coal fines. As the dip angle of the seams being worked increases, the indicated shortcomings appear still more strongly.

Thus we establish that all systems of mining with caving, when extracting seams with self-igniting coals, may lead to the occurrence of spontaneous fires. The fire hazard of these mining systems increases with an increase in the thickness of the seams being worked and with an increase in the dip angle. Finally, if the special rules for conducting mining operations in seams with self-igniting coals, especially those more than 5 m thick, are not observed, and if preventive measures are not applied, the occurrence of spontaneous fires is all the more inevitable.

The situation is different when systems of mining with stowing are used. These mining systems under Kuzbass conditions (with insignificant specific weight) gave rise to fires mainly in cases of accidents. Under the system of long pillars with stowing there were no spontaneous fires. Systems of mining with stowing are the best for extracting seams with coals prone to spontaneous ignition and with a thickness of more than 5 m. Under these systems of mining the worked-out space is filled with stowing, which eliminates caving and the occurrence of cracks in the roof, often reaching the surface. The necessity of leaving protective coal pillars disappears, and the possibility of complete extraction of the coal is ensured. Pressure on the supports is reduced and ventilation is improved. Despite the obvious advantages of mining systems with stowing in extracting coal seams prone to spontaneous ignition, in Kuzbass it has not become widespread, since until very recently a well-organized stowing operation had not been established. The considerable damage caused by the use of mining systems with caving in extracting thick, steeply dipping seams of coal prone to spontaneous ignition urgently requires, under Kuzbass conditions, the application of mining systems with stowing.

Ventilation Regime

The ventilation regime of mines working coal seams prone to spontaneous ignition, especially when working with caving, is one of the most important factors in the occurrence and development of spontaneous fires.

fires. A proper ventilation regime prevents the occurrence of endogenous fires, while an improper one accelerates it. The practice of mining coal seams prone to spontaneous combustion indicates that a change in the established regime, i.e., in the magnitude of the depression and in the direction and velocity of air movement (the quantity of air supplied), can lead to the occurrence of endogenous fires. Therefore, in mines with gas-bearing seams of self-igniting coals, ventilation is permitted only with the aid of fans, and ventilation by natural draft is prohibited, since natural draft varies, depending on the season, both in magnitude and in direction.

Air leakage through the goaf and pillars increases as the depression increases. This requires reducing the depression developed by the fan, but an excessive reduction of the depression may lead to a substantial influence on the operation of the natural-draft fan. In mines working seams of coal prone to spontaneous combustion, Academician A. A. Skochinsky recommends maintaining an artificial depression of no more than 100–150 mm water column [4, 155]. Of exceptionally great importance is the magnitude of the depression at the places where air leakage may occur—mainly the pressure difference between the given working and the surface caused by this depression. The magnitude of air leakage through the goaf and pillars is affected by ventilation structures (stoppings, ventilation doors, crossings, etc.) and by the correctness of the choice of the fan installation site.

All ventilation structures must be installed and constructed in such places in the workings that have no cracks, and in such a way that their installation does not increase the amount of air leakage through the goaf and nearby cracks. When ventilation structures must be installed in fissured rocks, the latter must be cemented. In addition, the ventilation structures themselves, intended for isolation, must be air-impermeable. Ventilation structures must be installed with account taken of their effect on the thermal depression arising in cracks and in the goaf as a result of air leakage, leading to spontaneous combustion of coal. The proper installation of both main and district fans has a substantial influence on the possibility of an endogenous fire occurring.

Near a fan there is usually the maximum depression, which, if the installation site is chosen incorrectly, leads to maximum leakage; therefore the pillars near fans must be of such dimensions as to preclude the possibility of leakage, and, in addition, district fans must always be installed ahead of the working face. Lagging of the fan behind the working face is associated with a sharp increase in air leakage through the goaf. The greater the lag, the greater the leakage will be, and the greater the possibility and danger of an endogenous fire occurring.

The ventilation scheme for ventilating mine workings in seams with coals prone to spontaneous combustion must ensure the possibility of cutting off the ventilation stream in which a fire has arisen without disrupting ventilation in other sections. The ventilation scheme must also be prepared with consideration of the special danger, in terms of spontaneous combustion and a sharp increase in gas emission (by 3–4 times), of individual sections as compared with ordinary sections in gas mines, in disturbed parts of the deposit with crushed coal and in the closed-off parts of seams.

Only the fulfillment of all the above requirements ensures a proper ventilation regime, eliminating the possibility of endogenous fires.

Conclusion

From the foregoing it follows that the selection of rational ventilation schemes for the coal mines of Kuzbass is possible only through a comprehensive consideration of the following questions: the opening and preparation of the mine field for longwall extraction, the sequence of extracting sections, the choice of the mining system, and the mine ventilation regime.

References

1. P. A. Manukyan. Underground Fires in Coal Mines, 1947.
2. Rules for Protecting Structures from the Harmful Influence of Mining Operations in the Kuznetsk Basin, 1940.
3. Instruction on the Application of Mining Systems and Preventive Fire-Control Measures at the Mines of the Kuzbassugol Combine, 1944.
4. A. A. Skochinsky and V. M. Ognevskii. Mine Fires, 1940.
5. I. M. Pechuk. Ventilation and Gas Control in the Mines of Kuzbass, 1946.
6. Ventilation Designs for Kuzbass Mines.