RU155251U1 - DEVICE FOR PREVENTION OF FREEZING - Google Patents

Abstract

A device for preventing freezing, including a hollow cylinder made of cardboard, with an airtight shell with a filler placed inside it, characterized in that the filler is an HCl solution in a concentration of 15-75%.

Description

The utility model relates to the mining industry and can be used in open pit mining of permafrost zones with preliminary explosive preparation of rocks for excavation.

A feature of mining operations in the conditions of cryolithozone deposits is the mandatory drilling and blasting of the massif, while the subsequent excavation of blasted rocks is complicated by their repeated freezing, which complicates their further development by mining equipment and reduces the efficiency of field development.

A known design of a blast hole in the dust suppression method during blasting in quarries, including explosive charges (BB) and stemming in the wellhead of which there is an airtight shell with a filler placed in a hollow cylinder. Moreover, the cylinder diameter is commensurate with the diameter of the well, and the height is selected depending on the required volume of the hermetic shell [1] (prototype).

At the time of the explosion, the expanding gases at an upward flow from the explosive chamber meet on the way a cylinder with a sealed shell filled with water. Since the cylinder diameter is commensurate with the diameter of the blast hole, the entire volume of water contained in the sealed shell will be sprayed with expanding explosion products, which will make it possible to fully use water as a coagulant, while eliminating undesirable distraction of the materials used.

The disadvantage of the analogue in the conditions of cryolithozone is that the water in the sealed shell, after a mass explosion, contributes to the repeated freezing of the destroyed rock. This process occurs due to the fact that in the bulk formed in the voids between the frozen pieces whose surface has already been thawed by the action of gaseous detonation products of explosives, additional moisture penetrates from the outside in the form of water or steam, which freezes due to the cold accumulated in pieces of the broken rock, transforming thus, the broken rock mass into a frozen monolith.

The technical task of this utility model was to develop a device for preventing freezing of exploded permafrost rocks.

The specified technical result is achieved by the fact that a device is installed over the mouth of the blast hole to prevent freezing, including a hollow cylinder made of cardboard, with an airtight shell with a filler placed inside it, characterized in that the filler is an HCl solution in a concentration of 15-75%.

The essence of the utility model is illustrated by the drawing, where in FIG. 1 depicts a device to prevent freezing located above the mouth of a blast hole 1. The device to prevent freezing includes a hollow cylinder made of cardboard 2. Inside the hollow cylinder there is an airtight shell 3 with filler 4 inside it — an HCl solution in a concentration of 15-75%.

Implementation of the proposed technical solution is as follows.

When drilling and blasting the permafrost mass, blast holes are drilled and charged with explosive charge. Then, a device for preventing freezing is installed over the mouth of the blast hole 1, including a hollow cylinder 2 made of cardboard, in which an airtight shell 3 is placed, with filler 4 a HCl solution in a concentration of 15-75%.

An important condition providing a positive effect of the proposed technical solution (utility model) is the permeability of rocks. According to the degree of water permeability, blasted rocks can be divided into 3 groups or categories (Table 1).

The proposed utility model of a device for preventing freezing is recommended for use in well-permeable and permeable rocks (Table 1).

The water permeability of rocks is related to porosity by a complex dependence and is determined not so much by the total porosity as by the average pore sizes and their diameters. The pore sizes in the case of blasted rocks depend on the particle size distribution - the larger the grain, the easier the rock is permeable to gravitational water. There are methods for calculating water permeability according to particle size analysis.

The permeability coefficient of the HCL solution (m ² ) for incoherent soil is calculated by the formula [2]:

where m ₀ is the void ratio; d is the equivalent diameter of the ball, m; α is the shape coefficient of grains (blocks).

The value of d is determined from the relation [3]: 1

where P _i is the relative mass content of various fractions with the size of grains (blocks) d _i .

Shape factor α = 1 for perfectly round balls. With small sizes of grain fractions and good roundness α = 1.22 ÷ 1.38. With an increase in the size of fractions and in the presence of a significant polygonality of their shape, the value of α increases and can take the values α = 4.5 [2].

The filtration coefficient K _f (m / s) is calculated by the formula [3]:

where ρ is the density of the liquid or gas, kg / m ³ ; g is the acceleration of gravity, m / s ² ; µ is the dynamic viscosity of a liquid or gas, N · s / m ² .

For example, for the conditions of the Kangalassky section of the Yakutugol HC, the granulometric composition of the blasted mass in the collapse is presented in Table. 2.

Then, according to formulas (1) - (3), the filtration coefficient of the HCl solution into the blasted massif K _f = 8.5 · 10 ^-5 m / s or K _f = 7.3 m / day.

Those. after the explosive destruction of the rock mass, a HCl solution placed in a sealed shell above the wellhead in a hollow cylinder, the diameter of which is comparable to the diameter of the well, and whose height ensures the placement of a sealed shell of the required volume, is guaranteed to penetrate the blasted mass to a depth of not less than 7.3 meters per day and thereby prevent its re-freezing, keep the blasted mass in a loose state and facilitate its further development by mining equipment.

Studies performed at the IHDS of the Siberian Branch of the Russian Academy of Sciences showed that the strength of secondary freezing decreases when the freezing surface is treated with an HCl solution [4].

The freezing strength of rock samples in their natural state (without the use of hydrochloric acid solution) has a linear dependence and increases by a factor of 2.8 with decreasing temperature from -5 ° С to -20 ° С (Fig. 1).

When applied to frozen surfaces of HCl solution in concentrations from 15% to 75%, the freezing strength of the samples decreases due to the interaction of the hydrochloric acid solution with the total moisture volume of the thawed rock layer.

Studies have established that a 1.7-fold decrease in freezing strength occurs already when 15% (2.1% -fact.) HCl solution is applied to the frozen surfaces of samples at a temperature of -5 ° C, and with a decrease to -20 ° C in 1 ,4 times. At 25% (3.2% -fact.) Mineralization of the solution and a temperature of -5 ° C, the strength decreases by 2.6 times. The most significant decrease in strength (up to a thawed state) by 13-20 times at -5-10 ° C occurs when mineralization is 50% -75% (6.1% -10.3% -act.) With HCl solution.

In the table. Figure 3 shows the actual mineralization of the freezing planes from the initial concentration, taking into account the depth of the thawed layer and the amount of moisture contained in it.

In the temperature range of the massif -5 ÷ -7 ° С at a concentration of 25% to 50% HCl solution deposited on the frozen surfaces of rock samples, the freezing strength decreases by 2.6 and 13 times, respectively. The use of a solution of 75% concentration for rocks with temperatures from -20 ° C to -10 ° C leads to a decrease in strength by 10 or more times, and at a temperature of -5 ° C, rock samples do not freeze.

A change in the mineralization of rocks with a solution of hydrochloric acid of 3 percent concentration leads to a decrease in the freezing strength of 2.6-2.8 times for sandy rocks having a temperature in the massif of -5-7 ° C.

The advantage of the proposed utility model in comparison with the prototype are:

- Prevention of repeated freezing of exploded permafrost rocks;

- more stable operation of mining equipment in the development of a weakened blasted massif;

- an increase in the actual volume of the blasted block under the condition of rock freezing.

Information sources

1. Pat. 2513731 Russian Federation IPC E21F 5/02. Dust suppression method during blasting in quarries [Text] / Fedotenko B.C., Fedotenko S.M., applicant and patent holder Fedotenko B.C. Claim 12/19/2012. Publ. 04.24.2014, Bull. No. 11. - 04.24.14.

2. Khamyalyaynen V.A., Ponasenko L.P., Burkov Yu.V., Frankevich G.S., Stallions V.A. Grouting of collapsed rocks. - Kemerovo: Kuzbass. state tech. Univ., 2000 .-- 107 s.

3. Basniev KS, Kochina NI, Maksimov MV Underground hydromechanics: a textbook for universities. - M .: Nedra, 1993 .-- 416 p.

4. Vinokurov, A.P. Experimental studies of the secondary freezing of rocks under conditions of mineralization of pore moisture / A.P. Vinokurov // Gorn. inform.analysis. newsletter. - 2008. - Dep. issue 2: Yakutia - 1. - S. 188-193.

Claims (1)

A device for preventing freezing, including a hollow cylinder made of cardboard, with an airtight shell with a filler placed inside it, characterized in that the filler is an HCl solution in a concentration of 15-75%.

Images