SU783657A1 - Method of determining portion of sorption porosity volume in total porosity of coal specimen - Google Patents

Description

I

The invention relates to a technique for studying physical properties, namely, the structure of porous samples, such as coal, can be used in the field of mining, which is significantly associated with the problem of the prediction of rock bursts and sudden emissions of coal and gas.

The known method of determining the fraction in the total porosity of the sorption pore volume by measuring and calculating the total porosity and the degree of water saturation corresponding to the maximum hygroscopic humidity 1. To do this, four characteristics are determined from rock samples 15: bulk density, density, initial moisture and maximum hygroscopic moisture.

The main disadvantage of the method lies in the fact that in many cases, especially during core drilling during geological exploration, in areas of geological disturbances and in outburst-hazardous areas of reservoirs often. 25 it is impossible to obtain complete samples weighing at least 50 g. Therefore, the determination of bulk density by the method of hydrostatic weighing is impossible, and therefore, it is difficult for ROS.

determination of total porosity and the proportion of sorption pore volume.

The closest to the proposed technical solution is the method for determining the sorption pore volume in the total porosity of a sample of coal determined by dependency.

ti

,, o.ib d-uvW V) /

max

id

where L 4; - increment of the moisture content of coal samples with a grain size of 2–5 mm in an environment with a relative air humidity of 95–98%, determined over a period of 5–6 h as the ratio of the sample mass increment to the mass of completely dry coal;

DUD / (11th most, for a sample of coal with a grain size less than 0.20, 25 mm. According to this method, two samples of the crushed sample are taken and placed in a sealed chamber with a known air humidity and the increment of humidity is measured separately for each sample 2j ,

The disadvantage of this method is that it cannot be used for express determination directly in mine conditions, since preliminary drying of the sample, weighing, and long-term saturation in a humid environment are required. The aim of the invention is to reduce the analysis time and simplify the process. The goal is achieved by determining the increment of the relative humidity of the air in the measuring hermetic chamber after 1–10 minutes, then placing samples of coal from a single sample of 5–50 samples and samples of 0.25–1 mm according to |:; sorption volume in the total porosity of the sample of coal; determined according to dependence. 4 lljjV t Л VV increment of relative humidity of air in the measuring chamber with a sample of 5-50 mm; iSiCj) - the same, for a sample of 0.25-1 mm. The essence of the method lies in barely giving. Coal samples collected from a specific area of interest. For example, when drilling holes or wells, coal is placed in a sealed chamber, in which changes in relative humidity of the air are recorded with hygrometers. On the basis of the initial moisture content of the coal (natural moisture), the air above its surface will dry out or increase until the dynamic balance between the humidity of the coal and the relative humidity of the air is reached. ; Example. The kinetics of determining the relative air humidity (cf) in a sealed chamber after placement was carried out. Coal samples of different sizes of coal seams with different portions of the sorption pore volume () were determined in it, which were also determined by the “BN-2 barothermigrometer” method. with a node of humidity. The principle of operation of which is based on the property of the kapron thread to change its length depending on the change in the relative humidity of the air. the instrument was individually calibrated for a certain temperature range and tuned in a narrow range of relative. Noah humidity. For example, for mine works in the range of relative humidity of air of 30-50%, 50-70 and 70-100%. An individual error was evaluated for each instrument. As studies have shown, in the normal temperature range of 1825 ° C, the device gave an acceptable resolution. In studies conducted to assess the proportion of the sorption pore volume (C), the chamber was sealed with polyethylene, and in order to reduce the inertia and improve the hygrothermodynamic characteristics of the measuring instrument. used the sensor of the BM-2 thermohygrometer without a housing. The initial relative humidity of the air in the chamber was 30-40. As an illustration on the league. 1-3 and in the table data for three characteristic cases are given. After the sample was placed, the coal in the chamber was periodically taken to read. FIG. 1-3 shows the characteristics of the kinetics of changes in relative humidity of air in a sealed chamber after placing into it samples of coal of different size and different disturbance of the pore space (1 with grain size less than 1 mm, 2 individual samples weighing 70-90 g). FIG. 1 dependences were obtained on coal beds, a coal seam, and the GPO, which is dangerous due to sudden coal and gas emissions (the mine named after Artyom, Ltremugol mountain, 860 m high, the east wing of the mine floor, an assembly furnace). FIG. Figure 2 shows the dependences obtained on samples of coal seam t, hazardous from sudden coal and gas emissions (mine named after Izotov Lrtemugol, mountain 630 m, east, lava 9 - ledge) ,. FIG. 3 - the same for reservoir IV, threatened by rock bursts (mine named after Ordzhonikidze, Gruzugol Combine, mountain 215 m, field D, east Shtrek).

Continued table.

Layer IV, hit by 0.9 rock bursts, mine them. Ordzhonikidze unification: Gruzugol It was revealed that, depending on the type of coal, its disturbance and strength, the kinetics of desorption of coal samples ;. different sizes vary significantly. In this case, the rate of moisture desorption of coal in the chamber space depends on the total surface of the pores and the burnt coal. This surface depends on the size of grinding and on the specific features of the pore space structure. When a network of large submacro and macropores is well developed in coal (value. I 0.25), then in this case the desorption of vaporous moisture practically does not depend on the grain size. The greater the proportion of the sorption pore volume in the total porosity and the smaller the fraction of submacro and macropores (.СГ1, the more significant is the dependence of the desorption rate of vaporous moisture from coal of different sizes (but of equal mass. As can be seen from the table, the resulting discrepancies are quite acceptable for evaluating the properties of coal. When creating special hygrometer sensors, these errors can be significantly reduced. Using the proposed method can significantly speed up (30-100 times) and simplify the determination of for prediction and control of 1 blows and sudden outbursts of the physical characteristics of coal, the proportion of the sorption pore volume, in terms of disturbance

-6,7

-0.06 -16.7 -0.15 -0.22

Claims (2)

1. Lomtadze V.D. Methods of laboratory research of physical and mechanical properties of rocks, l Nedra 1972. 2. USSR author's certificate 626397, cl. G 01 H 15/08, 1977 (prototype). 5 iO (15 min. Fig-5