SU1786265A1 - Method of artificial caving of hard-caving roof - Google Patents

Description

The invention relates to mining and can be used for forced collapse of a hard-to-break roof over a worked-out longwall space or over excavation workings of mines with a gentle and inclined bedding of coal seams without the use of blasting operations (torpedoing).

The known method of forced collapse of a difficult-to-break roof, including drilling wells, charging explosives in them, followed by torpedoing the roof for its artificial collapse.

The disadvantage of the known method of artificial landing of a hard-to-break roof is the real possibility of an exit by mine workings with a gentle and inclined bedding of coal seams without the use of blasting operations (torpedoing). The essence of the invention: in the presence of two planes of exposure in the console of a hard-to-break roof (sandstone, limestone), perforated copper tubes with a diameter smaller than the diameter of the wells are used as heat-conducting elements, which are filled with carbon dioxide granules and sent into the wells section by section before installing a hydraulic seal and filling the wells with water ... At the same time, there is a rapid expansion of ice formed from water, capable of creating an excess pressure of 113 MPa (1130 kgf / cm ² ) along the line of drilled wells at a temperature of minus 5-10 ° C, exceeding the tensile strength of the strongest sandstones and limestones, which leads to artificial collapse of the con, salt without torpedoing. 3 silt, flames from wells along natural roof cracks into a methane-gassed lava space, which leads to an explosion of methane-air mixture and coal dust (for example, an explosion at the Molodogvardeyskaya PO Krasnodonugol mine in 1981).

There is a known method of destroying monolithic objects (concrete, etc.) without the use of blasting operations by drilling holes, then filling them with a coolant (carbon dioxide granules) and heat-conducting long elements (metal shavings with water in order to accelerate the process of freezing water and

1786265 A1 of the subsequent destruction of the monolith along the line of holes drilled from top to bottom.

The disadvantage of this method is that this technical solution is not feasible in boreholes drilled from the bottom up with a hard-to-break roof. It is feasible only in holes drilled from top to bottom, allowing them to be filled with dry ice granules (solid carbon dioxide), a heat-removing element (half coil) at the mouth of the hole.

With the help of a semi-coil, it is also impossible to seal a borehole (well) drilled from the bottom up and fill the bore-hole (well) with water through one of the holes of the semi-coil to the base of the ribs of the semi-coil, thus excluding the outflow of water from the hole (well).

The purpose of the invention is to simplify the technology of artificial collapse of a difficult-to-break roof (sandstone, limestone, etc.) by eliminating the explosive effect (torpedoing), reducing energy consumption and increasing safety.

This goal is achieved by the fact that in the method of artificial collapse of a hard-to-break roof, including drilling inclined rising wells with a length exceeding the thickness of the collapsed roof, filling them with a heat-conducting element, installing hydraulic locks, filling the wells with refrigerant and water, copper perforated tubes with a diameter of a smaller diameter are used as heat-conducting elements wells, which are sent to the wells section by section before installing hydraulic locks and filling them with water.

Comparison of this solution with the prototype shows that this method differs from the known one in fundamentally new technical ways of achieving the goal, i.e. artificial collapse of a hard-to-break roof with two detection planes.

... In the proposed method, instead of metal shavings, perforated copper tubes are used, which provides a high degree of heat transfer while simultaneously obtaining an additional positive effect indicated for the purpose.

The softening and artificial collapse of the overhanging roof console in the presence of two outcropping planes in it is achieved by using the physical process of the rapid transformation of dry ice granules (solid carbon dioxide) into a gaseous state with a temperature of minus 55-56 °, accompanied by a sharp decrease in the water temperature in boreholes (wells) and its rapid transformation into ice.

At the same time, there is a rapid expansion of ice formed from water, capable of creating an excess pressure of 113 MPa (1130 kgf / cm ² ) at a temperature of minus 5-10 ° C, many times exceeding the tensile strength of the strongest sandstones and limestones.

When the ice temperature drops from minus 10 to minus 20 ° C, its excess pressure instantly increases to 197 MPa (1970 kgf / cm ² ), which contributes to the rapid softening and collapse of the hard-to-break roof console along the line of drilled holes (wells) in hard sandstone or limestone roof ... The presence of two planes of the roof exposure contributes to the collapse process.

Perforated copper pipes with a coolant (dry ice granules - solid carbon monoxide) are placed in boreholes or wells drilled obliquely from the bottom up along the line of the planned collapse of the hard-to-break roof parallel to the slitting furnace, excavation drifts or side walkways, the fastening of which is deformed under the pressure of the overhanging console of the hard-to-break roof ... This leads to sudden collapses of the roof in longwalls with severe consequences and forced re-reinforcement of excavation drifts or side passages as a result of deformation of the lining with a stop of mining operations.

FIG. 1 shows a cross-section of a haulage drift! attachment which is deformed by the pressure of impending k osoli 2 trudnoobrushaemogo sandstone power _Sc 3 above goaf coalbed the power.

FIG. 2 under pos. 3 shows boreholes or wells drilled obliquely from below upwards through the entire thickness t _n of the roof from the generation 1 in order to collapse the artificial hanging over the goaf 3 console proposed method. ' ^x

The number of boreholes (wells) 4 drilled simultaneously obliquely depends on the thickness of the overhanging roof console, the pressure and strength of its rocks. The boreholes (wells) 4 are drilled from the side of the working 1 obliquely upward to the entire thickness of the collapsing roof of the console with the distance between the boreholes (wells) equal to 2R (see Fig. 2), where R is the radius of the active zone of the borehole or well 4.

Artificial collapse of a cantilever of a hard-to-break roof having two exposed planes is carried out as follows.

Before water is injected into the wells (boreholes) 4, section-by-section perforated copper tubes 6 are sent, pre-filled with a refrigerant (solid carbon dioxide) (see Figs. 1 - 3). Solid carbon dioxide is obtained directly in the mine from 40-liter carbon dioxide cylinders delivered here, filled with liquefied carbon dioxide, 30-35 kg in one cylinder. With the help of a special device (conventionally not shown), liquefied carbon dioxide during adiabatic expansion turns into a solid phase (granules), which allows it to be immediately pressed into cylindrical blocks (conventionally not shown), which are filled with copper perforated tubes 6, which are sent in sections to boreholes or boreholes ( see Fig. 1 - 3). After that, a water seal 5 is installed at the mouth of each borehole (well) 4, which makes it possible to simultaneously pump water into them under pressure through a hose 8 with a special pump (not conventionally shown). The check valve 7 of the hydraulic seal excludes the reverse exit of water from the holes (wells) 4.

Copper perforated tubes 6, due to their high heat capacity, create a heat-dissipating circuit that makes it possible to accelerate the freezing of water in boreholes (wells) 4 and natural cracks in the radius R five times compared to a steel perforated tube. At the same time, an ice plug is quickly formed, increasing the lateral expansion forces, contributing to breaking of the overhanging roof console 2, deforming the support of excavation 1 along the line of drilled holes (wells) 4. The total volume of cracks in the roof rocks in radius R, where water penetrates under excessive pressure, is 811% of the volume 2 π R m _H N, where N - the number of boreholes or boreholes simultaneously participating in the artificial collapse of the rock roof console, which has two outcropping planes.

Solid carbon dioxide during adiabatic expansion rapidly turns into gaseous, which through perforated holes in the sections of copper pipes is in contact with water, absorbing its heat in the radius R.

In this case, a rapid decrease in the water temperature to minus 5-10 ° C occurs, and the expanding conditions of the formed ice reach an effort of 10-200 MPa, which leads to a rapid breaking off of the rock console along the line of drilled holes (wells), which prevents deformation of the lining of mine workings 1.

The table shows the results of mine tests of the rate of complete freezing in water wells in the presence of steel and copper perforated sections 80 mm in diameter with a total length of 2000 mm. The broken off console is made of hard sandstone with a strength coefficient j = 10 on the scale of prof. M.M. Protodyakonov. The diameter of two wells obliquely drilled upwards is 100 mm at an angle of 45 ° to the vertical for the thickness of sandstone, the length of the wells is 2500 mm, the temperature of the well walls is plus 28 ° C, the temperature of the water in the mine's irrigation pipeline is plus 15 ° C. In this case, the time of complete freezing of water in the wells according to the proposed method was:

It can be seen from the data in the table that perforated copper tubular sections accelerate the freezing of water in the well by five times compared to steel, which dramatically increases labor productivity. Rapid freezing of water in wells is also facilitated by the fact that ice does not have time to manifest the creep property, which increases its expanding efforts.

The amount of solid carbon dioxide, depending on the amount of water injected into the bore holes (wells), is determined by the following formula:

^m CO2 ⁼ t1 [C1 (T1 -To) + L + CA (T2-To)] _ y ^with CO ₂ (T2 - T3) + L with ₂ + C CO ₂ ( ^t 2 ~ ^t 3) where πίί is the mass water;

Ci - specific heat capacity of water; Τι - initial water temperature;

To is the temperature of ice formation;

T ₂ - ice temperature:

С с ₂ “specific heat of solid phase of carbon dioxide:

λ-specific heat of melting of ice;

SD - specific heat of ice;

Тz is the temperature of transition from the solid COg phase to the gaseous one;

L with ₂ “heat of transition of CO ₂ from the solid phase to the gaseous phase;

t

C with ₂ specific heat of carbon dioxide;

m _CO2 is the mass of carbon dioxide in the solid phase.

Following the movement of the lava in the above way, a sequential artificial collapse of the overhanging roof console is performed, which eliminates the deformation of the support, which causes repeated reinforcement of the section drifts and side walkways.

The use of the proposed method provides the following advantages in comparison with the known ones:

1) there is no need to use expensive machines and mechanisms;

2) the method is safe and easy to implement in the conditions of each mine, which has cylinders with liquefied carbon dioxide;

3) the volume of repeated reinforcement of section workings (drifts and sideways) caused by deformation of the support of section workings under the influence of the pressure of the overhanging console is sharply reduced;

4) can be easily implemented in boreholes (wells) drilled from the bottom up, and not from top to bottom, as in the prototype.

At the same time, the safety of work is increased due to the exclusion of operations associated with the re-strengthening of section workings for their reuse, which led to human casualties.

Claims (1)

Claim A method of artificial collapse of a difficult-to-collapse roof, including drilling inclined rising wells with a length exceeding the capacity of the collapsed roof, filling them with a heat-conducting element, installing hydraulic locks, filling the wells with coolant and water, characterized in that, in order to reduce energy costs and increase the safety of work in the presence of two planes exposure in the cantilever of the collapsing roof, as heat-conducting elements, copper perforated tubes with a diameter smaller than the diameter of the wells are used, which are sent section by section into the wells before installing hydraulic locks and filling them with water. Well filler Freezing time, min Water + Steel Perforated Tubes With Solid Carbon Dioxide fifteen Water + Copper Perforated Tubes with Solid Carbon Dioxide 3 Fig. 1 Bb I · .. ··. · \ 4_ FIG. 2 Compiled by V. Ovchinnikov Editor B. Fedotov Techred M. Morgenthal Proofreader S. Yusko Order 237 Draw Subscription VNIIPI of the State Committee for Inventions and Discoveries at the State Committee for Science and Technology of the USSR 113035, Moscow, Zh-35, Raushskaya nab., 4/5 Production and Publishing Plant Patent, Uzhgorod, Gagarin str., 101