Studium petrologiczne twardego węgla brunatnego z Poręby koło Zawiercia

Ireneusz Kołcon, Marian Wagner

Abstract


Przedstawiono wyniki badań petrologicznych liasowego węgla brunatnego z rejonu Poręby kolo Zawiercia, czyli obszaru o przypuszczalnie najkorzystniejszych warunkach geologicznych i ekonomicznych. Pokład węgla jest dwuławicowy, zbudowany głównie z klarynu. Charakteryzuje się stopniem uwęglenia typowym dla odmiany błyszczącej twardego węgla brunatnego. Cechy technologiczno-chemiczne i optyczne węgla są bardzo zbliżone do cech energetycznego węgla kamiennego.

 

PETROLOGICAL STUDY ON HARD BROWN COAL FROM PORĘBA NEAR ZAWIERCIE

 

In southern part of the Silesian-Cracow Monocline, a layer of hard brown coal is known in the Lower Jurassic. The layer occurs in the claystone-sandstone Blanowice Beds (Upper Domerian) which are up to 30 m thick in the Zawiercie region (Fig. 1). The geological conditions of occurrence of that layer are most advantageous in the vicinities of Poręba, where it is found at 3 m depth and over 1 m thick.

This is the area where this layer was exploited from time to time.

The brown coal seam is actually formed of two layers: upper, 0.2 to 0.3 m thick, and lower, 0.9 to 1.1 m thick (Fig. 2), separated by 0.6 m intercalation of claystones. Coal of the seam is mainly built of clarain, the share of which is estimated at 59.5%. Vitrain and fusain represent subordinate petrographic components (7.6% and 0.3%, respectively – see Fig. 3).

Two varieties of clarain have been identified in the course of microscopic studies: one, predominating here (clarain I), mainly built of durain (which results in fairly high, 22.5–34.4% share of macerals of the exinite group, especially sporinite – see Table 1), and the other (clarain II), characterized by higher share of vitrain layers on the durain and, therefore, high, 62.5–64.5% share of macerals of the vitrinite group. Vitrain occurring in clarain as well as when forming separate layers is mainly built of telinite.

Mean reflectivity of collinite (Rom) from the Blanowice coal equals 0.61 and of telinite – 0.45. Such values are typical of luster variety of brown coal.

The elementary analysis and some technological tests (Table 1) gave support to the results of petrological studies. Content of carbon ranges here from 66.3 to 73.1 %, equalling 72% at the average, hydrogen – from 3.1 to 5.7%, and total sulfur – 7.2 to 9.4%. Coal forming upper layer of the seam displays some features of the weathered one.

The results of the analysis show the brown coal from Blanowice to be a good fuel. This is also indicated by low ash content (from about 7 to 10%) and high burning value (26–30 MJ/kg – Table 2). Some parts of the coal display features of boghead coals. Eventual use of the seam is markedly limited by high content of sulfur. This element occurs here mainly in the form of pyrite and marcasite.

Therefore, the Blanowice coal seam may be used as fuel for local purposes only.

 


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