Ore and non-ore mineralization in cracks filled with hydrocarbons in the dark grey Upper-Devonian limestone has been found in the Józefka quarry of Upper Devonian limestone and dolomite near the Górno village near Kielce at Holy Cross Mts. Poland. Hydrocarbons in the liquid form and iron and copper sulphides appears hear in the fault zone as joints filling. The wall rocks are impregnated by hydrocarbons giving them black color. Hydrocarbon impregnations appears also following the bedding planes The coexistence of ore mineralization and hydrocarbon suggests their common origin and migration from deep-seated sources, that may be the Silurian Ordovician or Lower to Middle Devonian black shales. The metallic-hydrocarbon compounds were suggested as metals carrier.

Ore and non-ore mineralization in cracks filled with hydrocarbons in the dark grey Upper-Devonian limestone has been found in the Józefka quarry of Upper Devonian limestone and dolomite near the Górno village near Kielce at Holy Cross Mts. Poland. Hydrocarbons in the liquid form and iron and copper sulphides appears hear in the fault zone as joints filling. The wall rocks are spotty impregnated by hydrocarbons giving them black color. Hydrocarbon impregnations appears also following the bedding planes The coexistence of ore mineralization and hydrocarbon suggests their common origin and migration from deep-seated sources, that may be the Silurian Ordovician or Lower to Middle Devonian black shales. The metallic-hydrocarbon compounds were suggested as metals carrier.

The contradiction between the restriction of grating manufacturing technology and high-resolution measurement requirements has been the focus of attention. The precision requirement of angle calculation during the digital subdivision processing of a Moiré signal is focused on, the causes of errors in the solution of arcsine function are analysed, and an improved coordinate rotation digital computer (CORDIC)with double-rotation iteration is proposed by discussing the principle of the conventional CORDIC in detail herein. Because the iterative number and data width of the improved CORDIC are limited by the finite digital circuit resources and thus determine the calculation accuracy directly, subsequently the overall quantization error (OQE) of the improved CORDIC is analysed. The approximate error and rounding error of the algorithm are deduced, and the error models of iterative number and data width are established. The validity and application value of the improved CORDIC are proved through simulations and experiments involving a subdividing circuit. The corresponding relation between the approximate error, rounding error and iteration number, as well as the bit width are proved by quantization. The error of subdivision with the improved CORDIC, obtained through a calibration experiment, is within ±0.5′′ and the mean variance is 0.2′′. The results of the research can be applied directly to a digital subdivision system to guide the parameter setting in the iterative process, which is of crucial importance in the quantitative analysis of error separation and error synthesis.

The paper presents selected issues related to the development of international coal markets. World consumption of coal dropped for the second year in a row in 2016, primarily due to lower demand from China and the U S. The share of coal in global primary energy consumption decreased to 28%. World coal production accounted to 3.66 billion toe and it was lower by 6.2% when compared to the previous year. More than 60% of this decline took place in China. The decline in global production was more than four times higher than the decrease in consumption. The sufficiency of world resources of coal are estimated at 153 years – that is three times more than the sufficiency of oil and gas resources. After several years of decline, coal prices increased by 77% in 2016. The current spot prices are at the level of $80/t and are close to the 2014 prices. In the European market, after the first half of the year, coal prices reached the level of around 66% higher than in the same period of the last year. The average price in the first half amounted to PLN 12.6/GJ, which is close to the 2012 prices. The share of spot trade in the total purchase amount accounted to approx. 20%. Prices in futures contracts can be estimated on the basis of the Japan-Australia contracts prices and prices in supplies to power plants located in Germany. On average, the prices in supplies to these power plants were higher by approximately 9% in the years 2010–2016 and prices in Australia – Japan contracts were 12% higher than CIF ARA prices in 2017. Global energy coal trade reached about 1.012 billion tonnes in 2016. In 2019, a decline by 4.8% is expected primarily due to the expected reduction in the demand in major importing countries in Asia.

In Poland, the economic use of methane from coal seams has been recognized as one of the objectives of the „Energy Policy of Poland until 2030“. In Poland at the Upper Silesian Coal Basin, reconnaissance operations were initiated to collect methane from coal seams using drilling wells and hydraulic fracturing operations.

During these operations, noise emission can have a significant impact on the environment. In order to limit the negative impact of noise, well pads are usually located in undeveloped areas. However, in the European Union, the majority of hard coal deposits from which methane can be extracted are located in areas with a high population density.

This article presents the results of noise measurements carried out during hydraulic fracturing operations of coal seams and the results of calculations of the equivalent sound level during the daytime. Based on the analysis of noise emission, some recommendations are given regarding the location of planned new well pads in highly urbanized areas in order to meet the applicable standards of noise protection.