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SULFUR GAS SUPPRESSION TECHOLOGY WITH USING PHYSICS-CHEMICAL METHODS IN COAL BASINS
Toleubekova Zh.
Candidate of Technical Science, Senior Lecturer
Bolatova A. Talgatuly E. Atamuratova A. Kassen T.
Master students of Karaganda State Technical University,
Karaganda
ABSTRACT
The article describes the parameters of sulfur gases suppression using physic-chemical methods on bad gases during underground mining. Technology's parameters and usage areas are defined.
Keywords: sulfur gases, hydrogen sulfid, sulfur dioxide, technology, foulness, gassing, solution.
In coal mines the main harmful impurities the air are methane, a poisonous and explosive gases (carbon monoxide, hydrogen sulfide, sulfur dioxide, gases, explosives, etc.).
In the Karaganda basin, the separation of sulfur-containing gases were observed in the mines "Mo-lodezhnaya", "Kazakhstan", named after V. I. Lenin, "Shakhtinskaya", "Tentekskaya", "Abayskaya", named after T. Kuzembayev, etc.. Currently in the basin marked by the so-called hydrogen sulphide zone, is confined to the seam D6 of Dolinskaya Suite and to the layers of K16, K12, K10 Karaganda Suite. Simultaneously with the hydrogen sulfide fixed allocation of sulfur dioxide [1].
It is known that when the concentration of hydrogen sulfide more 0,0071% by volume, i.e. when 10-fold excess of admissible norms, at the same time can be released sulfur dioxide. At simultaneous presence in the air of hydrogen sulfide and sulfur dioxide toxicity of hydrogen sulfide in the mixture is much higher than in pure form. To get used to the effects of hydrogen sulphide body cannot, on the contrary, its sensitivity after undergoing lung poisoning is increased, even at low concentrations, the faster poisoning occurs.
Usually sulfur gases occur in the reservoir in the form of "clusters" with dimensions in the plane of the stratum from 150 to 600 m.
Without the use of special measures against gas emission toxic gas levels during the mining of coal deposits may exceed allowable PB concentration is ten times or more, which has acute toxic effects on the human body, reduces productivity, impairs the safety of mining operations, causing in some cases, the need to stop coal mining.
The technology parameters of the suppression of sulfur-containing gases in the working areas of the cutting and transportation of coal are the performance of irrigation systems, the consumption of reagents and solution, etc., significantly affect the efficiency of neutralization of hydrogen sulfide and sulfur dioxide. The performance of the combine in the hydrogen sulfide zone is determined by the feed rate and reliability of technological processes.
Pre-located air flow Q for ventilation of bottom-hole space for the case when the load on the lava is limited by the gas factor (methane):
Qv = 60dmaxS0.z, m3/min, (1)
where Umax - for PB the maximum speed of the lava, equal to 4 m/s [2];
So.z. - the cross section of the excavation; for complex MK-75 at mpL = 2.2 m; So.z = 3.9 m2.
Therefore, Qv = 60 . 4 . 3,9 = 936 m3/min.
As the mine "Kazakhstan" metrobility constrain the load on the lava, air flow is also defined for the minimum on dust factor air speed (Umm = 0,9 m/sec):
Qv = 60 0,9 . 3,9 = 210 m3/min.
When the optimum speed of the jet (Uopt = 1.6 m/s) airflow will be: Qv = 60 1,6 . 3,9 = 375 m3/min.
For cleaning faces of the mine "Kazakhstan" characterized by minimal air flow rates (Qv = 210 m3/min), however, further calculations for the choice of alternative ways of reducing the concentration of hydrogen sulfide and increasing the load on the bottom will take into account all three values.
In the hydrogen sulfide zone, the limiting factor is not the methane, and the concentration of hydrogen sulfide. The release of hydrogen sulfide required amount of air can be found by the formula
Qv = m3/min (2)
where I - is the maximum (absolute) hydrogen sulfide release from bottom-hole space, m3/min; C — maximum permissible concentration (MPC) in the outgoing air stream, C = 0,00066 % by volume; the C0 -concentration of the gas in the incoming stream, C0 = 0.
Unlike methane, hydrogen sulphide in the mine occurs not spontaneously, but under the excavation and grinding of coal, i.e. in a specific period of time related to the work cleaning the machine or conveyor. But since the main volume of H2S allocated when operating mining machines, the concentration of hydrogen sulfide in the working area of the processor and determines the amount of air required for diluting it up to health standards. Therefore, the formula (2) can be represented in the form
Q
theor
V
С
100
m3/min,
(3)
where qo.z. - relative profusion of gas (H2S) excavation, m3/t;
Qtheor - theoretical performance combine in this formation, t/min;
C - the sanitary norm (MPC = 0,00066 % ) for hydrogen sulfide, %.
With known values of air flow Q of formula (3) to find the allowable hydrogen sulfide performance of the harvester in the lava and, accordingly, the permissible feed speed of the machine:
(4)
Qtheor = - QVC , t/min.
100 q0.z.
In the formula (4) is known to challenge the establishment of the value qo.z in H2S. In the work of I. P. Sklyarenko, published in 1958 and is a more or less systematic work on the sulfide, the maximum gas content of coal in the sample heated to 100 °C, amounted to 5 -6 cm3 per 100 g of coal, i.e. 0,05 - 0,06 m3/t [3]. The maximum gas content of coal in Karaganda basin fixed on mine, "Kazakhstan" on the upper layer of seam D6 (0,36 - 0,41 m3/t, heated sample) and on mine. V. I.
Lenin on the bottom layer of seam D6 (0,20 - 0,23 m3/t, is also heated) [4, 5, 6]. Note that without heating the sample to set the gas content of coal H2S impossible. This hydrogen sulfide content in coal should be considered abnormally high. However, the average value of the gas content of 70 samples of 5 mines amounted to 0,07 m3/t heated 0,00062 m3/t — without heating. Thus, in the excavation without heating of coal produces a small part of the sulfide component in the average of 70 samples of 0.88 % of the total gas content in H2S. Therefore, as a first approximation for mines in the Karaganda basin can be taken qo.z = 0,00062m3/t.
But we should not ignore the fact that the D6 reservoir in the Eastern wing of the mine "Kazakhstan" and mine of a name of Lenin manifests itself as a unique object with abnormally high content of hydrogen sulfide. Therefore, for these mines it is advisable to install "their" values qo.z. The average value of gas content for 16 samples of the mine "Kazakhstan" amounted to 0,1845 m3/t, the average gas (without heating) amounted to 0,00147 m3/t, i.e. 0,80 % of the total gas content. Therefore, on average, qo.z = 0,00147 m3/t (for H2S), whereas the maximum of qo.z = 0,011 m3/t. Thus, it is possible to expect an eightfold excess emissions of hydrogen sulfide on the face of the mean value qo.z.
The mine named after v. I. Lenin, the average value of gas content for 35 samples is equal to 0,0428 m3/t, the average gas (natural, without a (heated) — 0,000486 m3/t (1,14 %), then, on average, qo.z = 0,000472 m3/t (for H2S), whereas the maximum of qo.s =0,0053 m3/t. so, we can expect twelve-excess levels of hydrogen sulfide release the lava of the mean value qo.z.
The average for the group of mines outgassing (H2S) from the stope is qo.z = 0,00062 m3/t, or 0.88 % of the gas. Substituting in the formula (5) the numerical values of qo.z and C as well as the expected range of theoretical values combine performance Qtheor have
Qtheor = 000062(1+8) • 100 = 846
C 0.00066
m3/min. (5)
Analysis of the ratio of the quantities in the formula (5), leads to important conclusions:
1. With a fixed amount of air flow to ventilate the stope (Qo.z = const) the level of gas in the lava for hydrogen sulfide depends on 50% of the relative profusion of gas qo.s in H2S and 50 % of min of performance combine working Qtheor. The parameters qo.z. and Qtheor can be called modal, as they allow you to adjust the mode of extraction of coal in the hydrogen sulfide zone and sanitary-hygienic working conditions.
2. The average for the group of mines profusion of gas qo.z = 0,00062 m3/min and the minimum air flow Qv = 210 m3/min performance combine to 1.98 t/min ensures proper sanitary conditions in the lava for hydrogen sulfide (1 norm).
3. The average for the mine "Kazakhstan" profusion of gas for H2S equal to 0,00147 m3/t at reservoir D6, and the minimum value Qv = 210 m3/min sanitary norm but H2S is provided at the harvester performance not more than 0,94 t/min.
According to the "Guidance for dust control in coal mines", the number of nozzles in the irrigation system must be such that their total capacity when the
required water pressure was equal to the estimated water consumption determined from the expression
Q = Aq, l/min, (6)
where Q is the calculated water flow rate, l/min; And — performance mining machine, t/min; q — specific consumption of water l/t (irrigation during the work of excavation and tunneling q = 30 - 40 l/t).
Nozzles should be located so that the liquid chemical substance mainly went to the places of destruction of the mountain range (in the cut, the cutters of the harvester).
The technology of preparation of liquid chemicals is as follows: a certain amount of sorbent reagent (glyc-erol, triethylene glycol), carefully diluted with water in a water tank 1,5 - 2,0 m3 installed in the pump to supply water to the nozzles of the harvester, i.e. use the lava typical irrigation system.
During operation of the harvester, the prepared solution is fed to the nozzle installed on the harvester. When spraying the solution in the atmosphere of the production, and especially in the work area of the cutting of the combine harvester, along with the suppression of coal dust occurs contacting a sulfur-containing gas with a sorbent solution, the result of which is a complete adsorption of sulfur-containing gases.
The suppression of sulfur-containing gases on the basis of the glycerin amount of the solution taken from the calculation of 88 ml (y = 1,261 g/cm3) of the reagent in 1 l of water. At this ratio of glycerin and water is obtained 10% solution of glycerol. To prepare the 5% solution is taken 44 ml (y= 1.01 g/cm3) of glycerin to 1 liter of water.
For a more complete absorption of gases 5% solution of glycerin is used in cases if the concentration of sulfur-containing gases in the underground air below 50 norms, i.e. below 500 mg/m3 with a 10 % solution when the content is higher than 50 standards.
The composition with the lower limit of glycerin (0.5 %) and the alkali metal hydroxide (0,1 %) is recommended when the concentration of sulfur-containing gases in the underground air up to 100 of the sanitary code, with an average limit C3H8O3 (1.5%), and NaOH or KOH (0,2 %) — with the sulfur-containing gases in the underground air from 100 to 150 rules, with the upper limit of glycerol (3.0%) and alkali metal hydroxide (0.2%) — when cleaning mine atmosphere with an initial concentration of sulfur-containing gases 150 standards and more.
In the case of suppression technology of harmful gases with the help of a hydroxide-glycerin composition use lava TOS. The amount of solution taken from the calculation of 4.2 g glycerol, 1.0 g of potassium hydroxide or of sodium to 1 liter of water. At this ratio, glycerin, potassium hydroxide or of sodium and water get 0,5 % C3H8O3; 0,1 % KOH or NaOH. To make 1% C3H8O3 take of 8.8 g of glycerol; 0,2 % KOH or NaOH 2 g of potassium hydroxide or sodium per 1 liter of solution. Similarly prepared solution of 0.3% glycerin and 0.2% potassium hydroxide or sodium.
In operation, the harvester hydroxide-glycerin solution is supplied to the injector. Atomization of the so-
lution in the work area combine to suppress sulfur-containing gases. In the presence of glycerin a small amount of potassium hydroxide or sodium shows no irritating action on the human body.
The flow rate of the solution depends on the concentration and quantity of sulfur gases released into the atmosphere mining. The composition can be used for pre-processing of coal massif in the zones of manifestation of sulfur-containing gas by drilling deep wells and pumping them in the proposed composition.
Comparative analysis of hydroxide-glycerol and hydroxyl-triethylene glycol technology gives an indication of quite high efficiency of neutralization of sulfur-containing gases. However, their application differs and depends on the intensity of gas release. As in glyc-erol, and in triethylene glycol composition (according to mine and laboratory tests) and the concentration of hydrogen sulphide of up to 1000 mg/m3 absorption capacity of the solutions is high. At 0.5 % glycerol and the same concentration of triethylene glycol sulfide is sorbed almost completely. The absorption capacity to compare different solutions in the neutralization of hydrogen sulfide with concentration above 1000 mg/m3. Changes in the composition of glycerol, from 0.1 to 0.5% and the concentration of hydrogen sulphide in the mine atmosphere of a 1000 - 1500 mg/m3 gas content reduced from 10 mg/m3 to 0. At the same gas concentration and the content of the triethylene glycol is 0.5 -10 % is almost completely absorbed hydrogen sulfide. Similarly, when the concentration of H2S in excess of 1,500 mg/m3 [1].
Glycerin and triethylene glycol composition can be used for pre-treatment gas-bearing rocks that contain sulfide, by drilling deep wells and pumping them in the proposed composition.
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