Analysis of one-day forecasts of the maximum methane concentration in a tailgate of a longwall ventilated with U system - a case study

Methane that is released into the mine atmosphere poses a threat to the miners working there. Methane at concentrations of 5-15% by volume in air is an explosive gas. It has caused devastating explosions in mines all over the world. Therefore, in methane mines, concentration of methane in the face and in the entire mine is controlled through welldesigned ventilation system. This system controls concentration of methane in the mine atmosphere and in the rock mass as well as in the mine goafs. The article’s main objective includes a presentation of a forecast for maximal methane concentration in the determined time interval. Sensors were installed in the gate draining the air from longwall: up to 10 m in front of the longwall and at the roadway exit. Both forecasts were made using prognostic equations, using the measurement data in the ventilation roadway of one of the longwalls at the JSW S.A. mine

Forecast of methane concentration at the end of and in the ventilating roadway - a case study

Dotychczas stosowne jednodniowe prognozy średniego stężenia metanu dotyczące ścian odnosiły się przede wszystkim do wylotu z chodnika wentylacyjnego, gdyż na podstawie pomiarów w tym miejscu zostały opracowane. W przedstawionym artykule równania prognostyczne zostały zastosowane do prognozowania stężenia metanu na wylocie z chodnika wentylacyjnego, w chodniku wentylacyjnym w odległości do 10 m od czoła ściany oraz na wylocie ze ściany. Wyniki prognoz na wylocie z chodnika stanowiły materiał porównawczy w stosunku do wyników prognoz w pozostałych wymienionych miejscach. Uzyskane wyniki prognoz są bardzo zbliżone do wartości pomiarowych i zachęcają do przeprowadzenia dalszych prac sprawdzających ich praktyczna przydatność.Until now, the appropriate one-day forecasts of average methane concentration for walls were related primarily to the end of the ventilating roadway, as they were developed on the basis of the measurements made in that place. In the presented article, predictive equations were used to estimate the methane concentration at the end of the ventilating roadway, in a ventilating roadway at a distance of up to 10 m from the face of the wall, and at the wall end. The results of the forecasts at the end of the ventilating roadway were used as a reference material to compare to the results of forecasts in other, above-mentioned, places. The forecast results obtained are very similar to the measured values and encourage further work to be done in order to check their practical usefulness

Analysis of Methane Emissions From Air Shafts of the Jastrzębska Coal Mining Company in 2017-2019

The paper presents formation of the amount of methane released from a coal deposit during coal mining. The total amount of released methane is composed of the amount separated directly into the ventilation air in mines (ventilation methane) and included in the demethanation system, isolated from the ventilation air. Methane from the demethanation system is only partially utilized. The unused part of methane is discharged into the atmosphere. The paper presents how the amount of methane released in individual mines of Jastrzębska Spółka Węglowa S.A. was shaped, with a division into methane released to the ventilation system and included in the demethanation system, taking into account the part used for economic purposes and the part discharged to atmosphere. The research material covers the years 2017-2019

Analysis of forecasted methane concentration at the top gate of a wall ventilated by means of the “U” system. Case study

The release of methane into the mine atmosphere poses a threat to the miners. Methane is an explosive gas at concentrations of 5-15% in air by volume and throughout the history of coal mining has been the cause of devastating explosions in mines around the world. For these reasons, in methane coal mines, the concentration of methane emitted from the coal face and the entire mine is controlled by means of a well-designed ventilation system, a system controlling the concentration of methane in the mine atmosphere and a system for methane drainage of the rock mass and goafs. The presented article concerns the forecast of the average concentration of methane on a given day, in the places of sensors located in the longwall roadways of discharge air exhausted from the longwall: up to 10 m in front of the wall and at the outlet of the roadway. Both forecasts were made using the prognostic equations on the basis of measurement data concerning the ventilation roadways of one of the longwalls at JSW SA

Analysis of Exploitation Parameters in Drainage Boreholes of the Longwall Demethylation System. Case Study

In hard coal mines with methane, there is often a need to apply demethylation in order to keep the methane concentration not exceeding 2% in the ventilation air. The basic demethylation method in longwall areas is through drainage boreholes made in the roof rocks of the coal bed, from top gate, in front of the longwall. The drainage boreholes are usually made in bundles, in a fan-shaped arrangement, with several boreholes in each bundle. The paper presents the results of measurements and tests of the efficiency of a bundle of four drainage boreholes drilled approximately 100 m in front of the longwall face. The efficiency of individual boreholes was analyzed in time and depending on the distance of borehole outlets from the longwall face. It was found that there is a large variation in the extraction of air-methane mixture by individual drainage boreholes, as well as large differences in the efficiency of individual drainage boreholes during the longwall extraction process

Hazard of dusts harmful to health in the mechanized preliminary work

Zmechanizowane, prowadzone z użyciem nowoczesnych kombajnów chodnikowych roboty przygotowawcze są przyczyną wysokich stężeń pyłów szkodliwych dla zdrowia. W artykule przedstawione są wyniki pomiarów zapylenia powietrza w typowym wyrobisku przygotowawczym.Mechanized preliminary work carried out with the use of modern heading machines is the cause of high concentrations of harmful dust. The article presents the results of air dustiness measurements in a typical development working

Study of the Accuracy of Methane Concentration Forecasts in the Area of Longwall Outlet B-3 in Seam 407/1 in KWK “Borynia-Zofiówka” Ruch Zofiówka

In the presented publication, an ex post forecast of methane concentration at the airway outlet was carried out on the basis of equations previously developed and repeatedly tested by H. Badura and its errors were calculated. This forecast was considered as a reference level. Next, using the same forecast equations, the forecasting of methane concentration at the sensor location up to 10 m in front of the longwall face and at the longwall outlet was carried out, followed by the analysis of forecast errors. Since the measurement of methane concentrations in the locations under consideration differed, the results of forecasts also differed. Therefore, in order to assess the accuracy of forecasts, their absolute and relative errors were calculated and then compared with the forecast errors at the airway outlet. The analysis of errors showed that there are differences in forecast accuracy and it is advisable to develop new forecast equations mainly for the longwall outlet, but also for the location of methane concentration sensor installed in the airway up to 10 m in front of the longwall

One-Day Prognoses of Methane Concentrations for the 102 Longwall in the 325/1 Seam in the “W” Coal Mine Operating in a Continuous System

The first part of the paper concerns the natural deposition conditions of the 325/1 seam in the “W” coal mine, in the 102 longwall mining panel. It also presents the most important technical conditions regarding the exploitation at this longwall. To characterize the methane hazard in the longwall area, the parameters of ventilation and total methane concentrations as well as the volumetric flowrate of methane captured by the methane removal system, have been presented graphically. A significant part of the methane flow in the longwall area was released to the air flowing to the longwall. The most significant part of the article is the presentation and analysis of the results of prognoses of mean methane concentrations at the exhaust of the longwall area. The accuracy of the prognoses of methane concentration was verified using two methods: while not considering the release of methane to the air flowing to the longwall and while considering the total flowrate of methane to the ventilation air in the area of the 102 longwall. The method of forecast presented in the article has so far been checked for a 5-day and 6-day work day, as well as for walls operating in a non-regular mode. The article refers to the wall operating in a continuous mode, which required adaptation of the proposed method to this mode. The application of the one-day forecast proposed in the article allows for undertaking temporary methane prevention measures enabling safe use of the wall

Analysis of Methane Concentration Distribution at U-Ventilated Longwall Outlet – Case Study

The methane hazard concerns a growing number of longwalls in the Polish coal mining industry each year. Mitigating this hazard, both of work safety and economic reasons requires the application of preventive measures adequate to its level. Commonly threat level is estimated based on registered methane concentrations, which fluctuate and highly depends on the place of measurement. The article presents studies on the average and maximum methane concentrations at the longwall outlet, including analyses of the interdependence of methane concentration in methanometry sensors installation locations