Selection of Drilling Machines and Positioning Mechanisms for Newly Constructed Mines in Kuzbass

V. M. Zakhlebnyi

Reducing the labor costs of drilling and the time required for drilling the face depends to a considerable extent on the correct choice of the type of drilling machines and positioning mechanisms, on their most appropriate number in the face, and on the rational organization of work in drilling faces.

Until now, in driving horizontal workings through hard and medium-hard rocks under the conditions of newly constructed mines in Kuzbass, heavy hand-held drilling hammers of the OM-506 type have been used for drilling blastholes. Drilling was carried out mainly “by hand.” Pneumatic supports were used at the Tomusinskaya 5–6 mine, manipulators at the Berezovskaya-1 mine; drilling carriages were not used at all. Drilling with EBK-2m column drills was carried out from KEB-2 expansion columns.

The small number of types of drilling machines and positioning mechanisms used at newly constructed mines in Kuzbass naturally makes it difficult to provide recommendations on their selection. There are discrepancies in the recommendations given by some authors [1, 5, 7, 11, 12]. Some authors recommend the use of pneumatic supports, others drilling carriages, still others manipulators, and so on. There are no specific recommendations for newly constructed mines in Kuzbass.

In resolving the questions posed, domestic and foreign experience in driving mine workings was summarized from the literature. Particular attention was given to the organization of blasthole drilling at ore mines, where workings are driven in most cases through hard rocks, and where the rate of advance largely depends on the proper organization of drilling-and-blasting operations. Therefore, the organization of drilling-and-blasting operations at ore mines is at a higher level. At the same time, the mechanical transfer of the experience of ore mines to the specific conditions of newly constructed mines is unacceptable:

At present, domestic plants produce the following percussive-rotary drilling machines: OM-506l, OM-506m, PR-30k, PR-20, PR-25, PR-18l, PR-24l, KTsM-4. The following drilling hammers have been discontinued but remain in operation: RP-17, RPM-17, PA-23, PR-35. Pilot batches of drilling machines have been produced: PR-30lb, PRS-3, and PR-23. Drilling hammers have been manufactured as prototypes: PRT, PP-110.

The technical characteristics of the most widely used serially produced drilling machines and of the newest percussive-rotary drilling machines are given in Table 1.

Table 1

Note. The technical characteristics were obtained at a compressed-air pressure of 5 atm.

* According to data from Giprorudmash [9].

At present, column-mounted drills are produced: EBK-2m, EBK-3m, EBK-4, EKM-2, ESTP-3. A pilot batch of drills with hydraulic feed, PEB-2, has been manufactured.

Rotary-percussive machines are not produced by domestic plants.

In drilling blastholes, the following mounting mechanisms have found application: MBI-5u and MBM-2 manipulators, BK-2, BT-3, and BK-4 drilling carriages, and the drilling carriage of engineer Moiseev, KMR and KEB-2 bracing columns, KPR-3, PPK-21, P-1 pneumatic supports, etc. The principal factors which, in our opinion, influence the choice of drilling machines, drilling tools, and mounting mechanisms in driving horizontal workings are:

1. The physico-mechanical properties of the rocks intersected by the working: strength, viscosity, elasticity, fissuring, etc.

1. Dimensions of the working and the shape of its cross section.

2. Parameters of the set of blast holes: a) depth of the holes; b) diameter of the holes; c) arrangement and angle of inclination of the cut holes; d) number of holes in the set.

3. Number of simultaneously operating faces, their mutual arrangement, and the possibility of multi-face drilling.

4. Interdependence of drilling machines and positioning mechanisms.

5. Requirements of the dust-control regime and the availability of possible dust-suppression means.

6. Required rate of advance of the workings.

7. Type of energy and the possibility of its use from the standpoint of ensuring maximum safety in mining operations and maximum productivity of the drilling equipment.

8. Availability of drilling equipment and the possibility of acquiring it; reliability of drilling equipment in operation, i.e., quality of manufacture, simplicity of design, etc.

9. Availability of qualified drillers.

If several types of drilling equipment satisfy the above requirements, the final selection may be made by a method of economic comparison according to the following factors:

a) ensuring maximum productivity of the drillers and, for the face group as a whole, in terms of output;

b) obtaining minimum drilling costs per 1 linear m of hole, according to direct standardized costs;

c) ensuring the lowest cost of driving 1 linear m of working, taking all costs into account.

In what follows, the influence of some of the listed factors on the selection of drilling equipment for newly constructed mines in Kuzbass is considered.

In comparing drilling machines according to the above factors, we used materials from Giproshakhtostroymash on tests of the drilling hammers OM-506л, PR-30л, PP-110, PR-85 (25), RV-300, T-10, RH-754; materials from the Department of Mining Machines and Mine Transport of the TPI on tests, under Kuzbass conditions, of the drilling machines PM-508, KTsM-4, RH-754, T-10; and also studies of the operating modes of rotary electric drills EBK-2м, ESGP-3а, PEB-2, conducted by the Kuznetsk Scientific Research Coal Institute.

The tests were carried out in rocks of various hardness, as a result of which it is possible to make certain assumptions regarding the serviceability of new drilling machines under the conditions of newly constructed Kuzbass mines.

The hardness of the enclosing rocks of Kuzbass varies over wide limits: from 0.6–0.8 to 12–14 on the M. M. Protodyakonov scale. The rocks are represented by clay shales of the aleurolite and argillite type and by sandstones with clayey cement, which [[unclear: text continues on next page]]

are distinguished by slight elasticity and increased viscosity in comparison with very hard rocks. Workings often pass through fissured rocks. As an exception, hard sandstones are encountered.

Destruction of the bottom of the blasthole when rotary-percussive drilling machines are used occurs as a result of the dynamic indentation of the tool and the chipping off of a certain volume of rock enclosed between two adjacent indentations. Therefore, the drilling productivity of these machines depends mainly on the force of each blow and on their frequency. On the other hand, with a large force of each blow and a small torque in rocks of medium hardness that possess increased viscosity, an indentation may be produced without the rock being chipped off to its full depth [8]. In this case, with a small torque there may be significant resistance to rotation of the bit, or its jamming, as a result of which the drilling rate may decrease considerably, and the advantages of a heavy column-type machine over a light drilling machine with a small force but a high frequency of blows may be reduced to nothing.

In rotary-percussive drilling in rocks of medium hardness, a large quantity of drilling fines is formed, which, moving into the annular space between the walls of the blasthole and the bit, creates additional resistance to rotation of the bit. To overcome this resistance, a considerable torque is required.

As follows from the figure obtained as a result of tests of drilling machines by the Department of Mining Machines and Mine Transport of TPI, the drilling rate of the heavy column-type drilling machine KTsM-4 in very hard shales \((f = 14 \div 18)\) with a bit diameter of \(46\ \text{mm}\) at an air pressure of \(5\ \text{atm}\) amounted to 122% of the drilling rate with the PM-508 hammer, and with the T-10 hammer—130%. The drilling rate in sandstones of hardness \(f = 6 \div 8\) was, for the KTsM-4, 108%, and for the T-10 hammers—176% of the drilling rate with the PM-508 machine. Thus, use of the KTsM-4 hammer in terms of drilling rate in rocks of medium hardness is inadvisable. Drilling with the KTsM-4 hammer in rocks of medium hardness is also inadvisable in terms of compressed-air consumption [2].

As shown by tests carried out by Giproshakhtostroi, the PR-25 and PP-110 drilling machines, which have a comparatively small energy per individual blow but a large torque and a high frequency of blows, possess the greatest productivity in rocks of medium hardness. The PRT drilling hammer, which has a large energy per individual blow \((9.6\ \text{kgm})\), correspondingly has a large torque \((380\ \text{kgcm})\), as a result of which it showed the greatest productivity in rocks of medium hardness [9].

Consequently, when designing drilling machines or selecting them, taking into account the physico-mechanical properties of the enclosing rocks

in Kuzbass, special attention must be paid to the correspondence between impact force and torque. In drilling at newly constructed mines, drilling machines with a modest impact force, a high impact frequency, and a high torque will be productive. When drilling in rock under Kuzbass conditions, the most productive drilling hammers will be: PR-25, PR-24l, T-10, PP-110, and, for “hand-held” drilling, PM-508. Powerful column-mounted and hand-held drilling hammers manufactured for the ore-mining industry are apparently inadvisable for use under Kuzbass conditions.

Optimal feed forces of drilling hammers and the corresponding drilling speeds with a bit crown diameter of 46 mm.

According to the considerations set forth above, when drilling in rocks of medium strength, the PR-30lb drilling hammer, which has considerable energy per individual blow and a low torque, will not have substantial advantages in comparison with the OM-506 and PM-508 hammers. When drilling in rocks with a strength of \(f = 12 \div 14\), the advantage of the PR-30lb drilling hammer will be more significant. However, enclosing rocks with a strength of \(f = 12 \div 14\) on the M. M. Protodyakonov scale are not widespread under Kuzbass conditions.

Drilling in medium-strength rocks can be successfully carried out by rotary drilling machines. When drilling with rotary column drills EBK-2m, ESGP-3a, PEB-2, adjusted to optimum operating conditions, rates in terms of machine time in rocks of medium strength can be achieved that are 2–3 times higher than the drilling rates of percussive-rotary machines [3, 13]. At the same time, when drilling with these drills, the total time for auxiliary operations is approximately three times greater than the machine drilling time, as a result of which it becomes impossible for one worker to service two drilling machines. To sharply increase drilling productivity, it is advisable to create “long-stroke” column drills.

Consequently, in newly constructed mines both electric and pneumatic drilling machines can be successfully used.

The use of electric drills contributes to a lower cost of 1 running m of excavation in terms of energy expenditures. In turn, percussive-rotary drilling is more economical in terms of consumption of drilling tools. The difference in the cost of worn-out tools in rotary and percussive-rotary drilling in rocks of medium strength and fairly hard rocks ($f = 4 \div 10$) may be less than, equal to, or somewhat exceed the difference in the cost of the energy required by the drilling machines. This question must be studied more thoroughly in order to determine the appropriate field of application of percussive-rotary and rotary drilling machines as a function of rock strength.

As is known, the magnitude of the optimum feed force of the hammer on the face has a great influence on drilling speed; for PM-508 (OM-506) hammers it is 45–65 kg, and for high-frequency drilling hammers it is 70–128 kg and more [2]. The feed force developed by a driller, within the limits of 25–30 kg, is insufficient for the optimum drilling regime of any of the hammers; therefore, when drilling “by hand,” all drilling hammers show a significantly lower drilling speed than when working on a feed device. At small feed forces, high-frequency drilling hammers have a large recoil force, vibrate strongly, and therefore quickly fatigue the driller.

Consequently, there is no point in using high-frequency drilling hammers when drilling “by hand.” Drilling productivity is also adversely affected by the fact that, when drilling “by hand” upper and middle holes, two drillers are required for each drilling hammer.

A pneumatic support considerably eases the driller’s labor and helps increase labor productivity. Simplicity, small dimensions, and low weight of pneumatic supports give them one of their main advantages—high maneuverability. The small dimensions of pneumatic supports make it possible to increase to the maximum

Table 2

the number of drilling machines in the face of the working. When drilling “by hand,” the output per face ranges from 1.03 to 2.67 m³ per man-shift, averaging 1.4 m³ per man-shift (Table 2). Productivity when pneumatic supports are used ranges from 1.35 to 6.7 m³ per man-shift. If the data for the Czechoslovak drivages [7] are excluded, productivity will average 2.5–3.0 m³ per man-shift. Consequently, the productivity of one drivage worker when drilling with a pneumatic support is 1.5–2.0 times higher than when drilling “by hand,” and the time required for drilling the face is reduced by 40–50%.

In considering the high-speed drivages of extended workings given in Table 2, it turned out that pneumatic supports are used in most cases in workings of small cross sections, i.e., in workings with a cross-sectional area rarely exceeding 10–11 m²; moreover, the height of the working does not exceed 3 m. In workings of larger cross sections—

Table 2 (continued)

…tions and of great height, drilling of the upper blast holes can be carried out from special platforms or from the blasted rock. Drilling from the blasted rock precludes the use of a large number of drilling machines at the face and makes it necessary to organize the driving cycle only with the operations of drilling blast holes and loading rock combined. Drilling from platforms will require considerable time for their assembly and dismantling, as a result of which the overall drilling productivity will be significantly reduced. In workings of small cross sections and low height there is no need to construct platforms, and the blast holes can be drilled from the floor of the working at any point of the face without complicated devices. Consequently, pneumatic supports can be used in workings of any cross section, but their use is most expedient in workings of small cross sections and low height.

Pneumatic supports are unsuitable for mounting colum—

drilling hammers and column-mounted electric drills. For the use of long-stroke drilling machines, spreader columns, manipulators, or drill carriages are necessary.

The auxiliary time when drilling blast-holes with electric drills from manipulators is approximately half that required when drilling from mechanical spreader columns. At the same time, however, installing the removable parts of the manipulator on the loading machine requires expenditures of time and labor; as a rule, this operation is performed by two workers. Raising and lowering the boom is carried out by a worm-screw mechanism, which does not eliminate manual labor, and rotation in the horizontal plane is performed by hand.

The insufficient mechanization of the process of setting up the drilling machine for a blast-hole requires considerable time. When drilling the lower blast-holes, the bucket of the rock-loading machine must be shifted to the side opposite the working drilling machine, as a result of which the drilling machine installed on the other side of the loading machine cannot at that time drill the lower blast-holes. Therefore, when MBM-2 manipulators are used, there will be a double dependence: the dependence of the two drilling machines installed on one boom, and the mutual dependence of the drilling machines installed on the left and right sides of the loading machine.

If, when driving an excavation, rock loading is carried out by one loading machine alternately from two tracks, the effectiveness of drilling blast-holes from manipulators in this case is substantially reduced, since one of the manipulators cannot be swung out to its extreme position because of the proximity of the side wall of the excavation, while the other, even in its extreme position, will not ensure drilling of the blast-holes located near the opposite side wall. Therefore, it is advisable to use manipulators when loading from two tracks only if two loading machines are used at the face of the excavation.

In light of the foregoing, the following assumption may be made:

a) in single-track workings, two drilling machines mounted on MBI-5u manipulators will not reduce the time for drilling the face in comparison with 6–8 high-frequency drilling machines mounted on pneumatic supports;

b) in two-track workings of large cross section, four drilling machines mounted on MBM-2 manipulators are inferior in productivity to drilling machines mounted on a drill carriage;

c) the use of removable manipulators under the conditions of mine construction projects in Kuzbass is unlikely to prove expedient.

A drill carriage most fully meets all the conditions for the use of long-stroke machines. Drill carriages are widely used in

are used in driving workings in domestic and foreign practice (Table 2). Despite the widespread introduction of light drilling machines with pneumatic supports, in the USA drilling is most often carried out with heavy rock drills mounted on mechanized drilling carriages. In West Germany, drilling carriages made by American firms are also widely used. In Czechoslovakia, despite the widespread use of light high-frequency rock drills on pneumatic supports, in most cases drilling is performed with drilling carriages using drilling machines not heavier than 50 kg in combination with automatic feeders. At present, work on improving drilling carriages in Czechoslovakia is continuing [7].

In driving an adit in hard rocks at the Hajdarkhan mine of Glavolovo in January 1956, the average labor productivity in Comrade Esingov’s brigade was 5.76 m³ per man-shift [8]. During driving, a drilling carriage designed by engineer Moiseev was used. Labor productivity at other Glavolovo enterprises under similar conditions, when drilling with hand-held rock drills from pneumatic supports, does not exceed 3.5 m³ per man-shift. The drilling carriage, with two rock drills mounted on it, was operated by one worker. At Glavolovo enterprises there is an effort to equip with drilling carriages all workings driven through hard rocks.

Drilling of blastholes in driving crosscuts, drifts, and other workings at the mines of Gornaya Shoria is carried out: 1) with two KTsM-4 rock drills from BT-3 drilling carriages (Tashtagol and Odra-Bash mines); 2) with two PR-35 rock drills from pneumatic supports of local designs (Temir-Tau and Shalym mines) [4]. The drilling carriage is, as a rule, operated by one worker. As a result of the use of drilling carriages, the driller’s productivity is increased by more than two times in comparison with drilling from spreader columns and pneumatic supports.

After comparing the time spent on preparatory-final and auxiliary operations, it becomes obvious that the greatest productivity of the driller, with a simultaneous easing of his labor, can be ensured only by a drilling carriage with drilling machines mounted on it and equipped with automatic feeders. If, when drilling from pneumatic supports, productivity per advance per face averaged 2.5–3.0 m³ per man-shift, then when drilling with a drilling carriage the average productivity was 4.5–5.0 m³ per man-shift. The rates of advance of workings achieved in this way are not inferior to the rates achieved with the use of pneumatic supports, except for record drivages in Czechoslovakia.

It should be noted that drilling carriages have found the greatest use in world practice in the driving of mine workings—

flow in the period from 1940 to 1954. In recent years, in connection with the appearance of light, high-performance, high-frequency drilling hammers mounted on pneumatic supports, very high rates of driving workings have in some individual cases been achieved by saturating the faces with a large number of drilling machines (Czechoslovakia, England). In this connection, in some countries, for example in France, a transition is being contemplated from the use, in driving workings, of drill carriages with heavy drilling hammers to the use of light high-frequency drilling hammers on pneumatic supports [9].

However, the use of pneumatic supports rules out multi-hammer servicing and entails saturating the face with a large number of workers, as a result of which labor productivity is significantly reduced. In cases where the overall development of the work depends on the rate of driving the working—for example, in the construction and reconstruction of mines—and when the fastest possible driving of workings will reduce other expenditures, it is sometimes expedient, at the cost of a greater saturation of the face with workers and increased energy consumption, to achieve more rapid driving of such workings. But resolving the question of the fastest possible driving of workings at the expense of reducing labor productivity and increasing the cost according to direct normed expenditures is one-sided.

It is necessary that the cost of a unit length of a working should not increase with an increase in the rate of driving the working. This can be achieved by improving the organization of labor, making fuller use of equipment and mechanisms, and increasing labor productivity.

A drill carriage, while ensuring high labor productivity, also makes it possible, with proper organization, to provide high rates of driving workings (Table 2).

If at present light high-frequency drilling hammers on pneumatic supports are in some cases displacing heavy drilling machines mounted on drill carriages, then, when “long-stroke” high-frequency drilling machines are installed on drill carriages, this process in extended double-track workings may proceed in the opposite direction, since the latter will be considerably more productive than the former.

At present, the question has become ripe for considering the drill carriage not only as a mechanism for mounting heavy column-type drilling machines, but also as a special device for multi-hammer drilling by any drilling machines, including those of medium weight. The main shortcomings of drill carriages—namely the complexity and bulkiness of their design, as well as the difficulty of maneuvering them at the face of the working—must be overcome by creating new designs of drill carriages that meet modern requirements.

trolleys and to develop the most rational standard schemes for organizing work in their application.

The use of drilling trolleys and “long-stroke” drilling machines is especially advisable at newly constructed mines in Kuzbass, where there is a large volume of mining work for driving double-track workings. Thus, for example, at the “Egozovskaya-1” and “Chertinskaya-Zapadnaya” mines of the “Leninskshakhtostroi” trust, the volume of mining work at the time the mine is put into operation for driving double-track workings with a cross-section of 14–18.5 m² is 3–4 times greater than the volume of mining work for driving single-track workings.

CONCLUSIONS

On the basis of an analysis of the use of drilling machines and positioning mechanisms, the following may be recommended.

1. Drilling “by hand” should be eliminated whenever possible.

2. Expanding columns and removable manipulators cannot be recommended for use at newly constructed mines in Kuzbass.

3. When driving double-track workings in rocks of medium hardness ($f$ up to 4), it is recommended to use long-stroke column-mounted electric drills with flushing, installed on drilling trolleys.

4. When driving double-track workings in hard rocks ($f$ above 5–6), it is advisable to use “long-stroke” column-mounted drilling machines, which should be developed on the basis of high-frequency hammers T-10 and PP-110.

5. In single-track workings, chambers, shaft junctions with shaft stations, raises, and other similar workings, high-frequency drilling machines PR-25 and PR-24l with pneumatic supports should be used for drilling blast-holes.

6. It is necessary to develop a new drilling trolley applicable to the conditions of newly constructed mines in Kuzbass. This task can be solved by carrying out special research and design work.

7. Until drilling trolleys are introduced, it is advisable, when driving all workings, to use PR-25 and PR-24l drilling hammers with pneumatic supports.

8. When it is necessary to drill blast-holes “by hand,” it is advisable to use PM-508 drilling hammers.

9. It is necessary to conduct research on rotary-percussive drilling and to develop machines of this type for the conditions of Kuzbass.

LITERATURE

1. K. I. Aganbekov. Organization of work according to cyclicity schedules in driving development workings (from the experience of newly constructed mines in Kuzbass). Ugletekhizdat, 1955.

1. O. D. Alimov, I. G. Basov, P. A. Samoilov. Some results of investigations of the operating regimes of pneumatic drilling hammers. Izvestiya TPI, vol. 106, Drilling Machines. Metallurgizdat, 1958.

2. O. D. Alimov. On the creation of high-productivity machines for rotary drilling of blastholes in rocks of medium hardness. Ugol’, No. 8, 1958.

3. O. D. Alimov, P. A. Samoilov. On the expediency of using drilling carriages in the mines of Gornaya Shoriya. Gornyi Zhurnal, No. 8, [[unclear: year]].

4. Problems in driving mine workings. Ugletekhizdat, 1956.

5. K. I. Zhuravlev. MBI-5U manipulators for drilling mechanisms. Ugletekhizdat, 1952.

6. L. S. Krastoshevskii. Driving horizontal and inclined mine workings abroad. Ugletekhizdat, 1956.

7. R. Kaye. Investigation of the percussive drilling cycle. Ugletekhizdat, [[unclear: year]].

8. Engineers M. P. Lesik and A. N. Fedotov. The high-productivity PR-25 drilling hammer. Shakhtnoe Stroitel’stvo, No. 1, 1957.

9. Engineer D. I. Maliovanov. On the driving of horizontal workings in the Nord and Pas-de-Calais basin. Shakhtnoe Stroitel’stvo, No. 1, 1957.

10. A. I. Podkovyrin. A summary of experience in driving workings in mines of the tin industry. Gornyi Zhurnal, No. 1, 1957.

11. High-speed methods for driving mine workings. Metallurgizdat, 1956.

12. M. K. Tsekhin. Investigation of drilling-and-blasting operations and increasing their efficiency when driving horizontal workings in the rock at the mines of the Prokop’evsk mine. Candidate dissertation, Tomsk, TPI, 1955.