Rational Technological Schemes for Driving Mine Workings by the Hydraulic Method

V. G. Lukyanov, A. D. Gromov, N. A. Loskutnikov, V. N. Potseluev

(Presented by the scientific seminar of the Department of Geodesy, Mining, and Construction)

The most important task facing the mining industry is a significant improvement in technical and economic indicators. In driving mine workings, first and foremost, an increase in labor productivity and a reduction in the cost of driving workings must be achieved.

The technological schemes have been developed by the authors with due regard for the experience of domestic practice in the rapid driving of workings. The technology and organization of work will be designed for the mechanized driving of horizontal workings in the mines of the specialized trust “Kuzbassgidrougol.” The technological schemes provide for ensuring the rapid driving of typical, repeatedly recurring workings. The album of technological schemes offers ready-made rational solutions for the organization and technology of driving operations, contributing to reduced labor intensity, improved quality, and lower cost. The technological cards are intended for trusts and mines developing work-production designs for the driving of workings, as a guide for work supervisors, shift engineers (mining foremen), and work crews in organizing production and labor during driving operations.

With the conventional technology of driving mine workings, the process of excavating rock is divided into separate labor-intensive operations. When workings are driven by the hydraulic method, the number of labor-intensive operations is reduced owing to a higher degree of mechanization and the low-operational nature of the work. In driving workings by the hydraulic method, the rock is broken by a jet of water discharged from a hydraulic monitor installed at some distance from the face, or by drilling-and-blasting methods, or with the aid of heading machines and mechanohydraulic machines. All subsequent operations (transporting the rock mass to the shaft and hoisting it to the surface) are carried out with the aid of water. The advantages of hydraulic driving are: low operational complexity, simplicity, continuity and uniformity of the process, higher labor productivity, smaller capital expenditures in mine construction, and the possibility of full automation of production processes. The hydraulic method of driving workings contributes to a significant improvement in labor safety compared with conventional technology. Workings in hydraulic mines, compared with analogous workings in mines using conventional technology, are characterized by the following distinguishing features.

They have a smaller cross-sectional area, which is seـ

is selected on the basis of the conditions for providing normal ventilation. The use of hydraulic transport of rock from the faces to hoisting installations makes it possible, in most cases, to dispense with the use in underground workings of various types and devices of mechanical transport (rail tracks, rolling stock, conveyors, etc.). The delivery of support and other materials to the face is carried out by monorail transport, hydraulic hoists, hydraulic traction units, or by means of cableways. Rock is discharged from the face in an open flow along chutes; accordingly, mine workings are driven with a gradient of 0.05–0.07 in the direction of transport.

At present, the driving of mine workings by the hydraulic method is carried out as follows:

1. By hydraulic breaking of the rock mass with a jet from a hydraulic monitor, followed by hydraulic transport.
2. By hydraulic breaking with preliminary weakening of the massif by the drilling-and-blasting method and hydraulic transport of the rock mass.
3. By blasting breakage followed by hydraulic washing and hydraulic transport.
4. By driving with the aid of mechanohydraulic machines and hydraulic transport of the rock.
5. By driving with roadheaders of the PK, PKG, and ShBM types, followed by hydraulic transport.
6. By driving with heading units of the AP-1 type.
7. By breaking the rock mass with a hydraulic-monitor jet, with loading and haulage of the rock mass by the conventional method.

The effectiveness of one or another method of driving workings depends on the mining-and-geological conditions of the rocks being driven and on the degree of mastery of the existing technical means.

At present, in the USSR and abroad, there are several technological schemes for hydraulic driving of mine workings and hydraulic coal extraction. The following schemes are the most widespread.

Scheme 1. A hydraulic monitor is installed at the face; water is supplied to it through a pipeline from a pump operating on the surface. The rock broken in the face by the water jet of the hydraulic monitor is carried away by the same water along chutes to a crusher and, after crushing, is delivered together with the water to the surface by coal pumps through a slurry pipeline. On the surface, the water is clarified and returns again to the pump for reuse. The loss of part of the circulating water due to evaporation and leakage is compensated by the inflow of underground waters, usually pumped out by coal pumps together with the slurry, or by adding water from nearby water sources on the surface.

Scheme 2. It differs from Scheme 1 only in that hydraulic hoisting delivers to the surface only part of the rock, usually of small size (up to 25 mm). The coarser rock is dewatered on a screen and delivered to the surface by mechanical hoisting.

Scheme 3. It has a closed water circulation loop in the area of the isolated hydraulic-breaking section, where underground dewatering is also carried out. This scheme is used in mines when the hydraulic section is considerably distant from the underground shafts.

These three variants are the basis of the technological schemes for hydraulic driving of mine workings. Depending on the mining-engineering conditions and the organization of the work, combinations of these schemes are encountered in practice.

One of the most important processes in hydraulic driving is the direct destruction of the rock massif. Thus, a purely hydraulic method of driving is limited as the strength of the rocks increases. It is rational to apply hydraulic breaking in rocks with a coefficient

strength according to Prof. M. M. Protodyakonov’s scale not higher than 3–4, with the existing equipment and water heads up to 300–400 atm.

Very promising at present is the introduction into practice of breaking means using jets of ultrahigh pressure. The effectiveness of the action of ultrahigh-pressure jets is so great that it becomes possible to use them also for hydraulic breaking of rocks of medium strength and even hard rocks. In this connection, investigations are now being carried out to create devices that automatically form intermittent jets with pressures of 1000 atm and more.

When the rock-strength coefficient is up to 6, the driving of workings can be carried out with the aid of mechanohydraulic machines or heading combines. Driving in rocks with a strength coefficient above 6 is carried out by a hydraulic monitor with preliminary weakening of the mass by blasting or by breaking the rock by the drilling-and-blasting method, followed by hydraulic washing and hydraulic transport.

At present there are the following technological schemes for driving workings by the hydraulic method, which are based on serially produced equipment.

1. Driving drifts with a narrow face, with gravity transport of coal and rock in seams up to 1.8 m thick. This is used at hydraulic mines where there are means for separating the rock before its hoisting, or a preparation plant on the surface. Depending on its strength, the coal may be extracted by the hydraulic or blasting-and-hydraulic method, while the rock only by the latter.

In seams more than 1.8 m thick with side rocks having a strength coefficient of 5 according to Prof. M. M. Protodyakonov’s scale, heading combines of the PK, PKG type and mechanohydraulic machines with hydraulic transport of the rock mass are used.

1. Driving drifts with a wide face and top benching. The rational field of application of this technological scheme covers systems that do not provide for the extraction of coal by autonomous machines (of the KG combine type) directly from the accumulating drifts, as well as hydraulic mines that do not have means for separating the rock (before hoisting it to the surface) and preparation plants. As means of hydraulic stowing, the DGZU hydraulic-stowing installation is used. The use of a light belt conveyor to feed rock into the bench is expedient when the angle of dip of the seam is up to 18° and the bench length is more than 7 m. In the general case, the cited means of stowing rock into the bench should be used until the start of serial production of AP-1 heading units, which comprehensively mechanize all operations of the heading cycle.

2. Driving drifts with a wide face and bottom benching. This is used in preparing extraction panels on inclined and steep seams, since under these conditions the broken rock can be washed into the bench by a hydraulic-monitor jet.

To ensure effective washing-in, the rock face of the drift must advance the bench face by 3–6 m.

1. Driving crosscuts provides, in most cases, for the drilling-and-blasting method of rock excavation, followed by hydraulic washing into chutes and transport to the hydraulic-hoisting chamber or to the hydraulic-stowing installation located in the area of the mined-out space.

The support is of the same type for many workings: in drifts KMP-2 support, arched AP-1-600 support, or timber support may be used; split furnaces may be supported by anchor or timber support, and sublevel drifts by timber support; in accumulating

In ventilation crosscuts it is advisable to use metal or timber supports.

Common to the driving of workings, including crosscuts, are the delivery systems, for which 8MKDTs monorail tracks are used; in cut workings (furnace drifts and sublevel drifts), the use of maneuvering winches and DK-1 roller tracks is provided.