No abstract

This study aims to determine the type of mineral and geochemical character of low rank coal. The coal samples were located at Indominco Mandiri Coal Mine KW 01PB0435 in East Kutai District, East Kalimantan. This area of research is entered into the Lower Kutai Basin, where in this basin there are two formations containing coal, namely Pulaubalang and Balikpapan Formation. The methods used are X-Ray Diffraction (XRD), proximate, and ultimate coal analysis. The results of this study based on X-Ray Diffraction (XRD) analysis of coal contents are clays minerals (kaolinite, illite), quartz, carbonates (calcite and dolomite), sulphides (pyrite and chalcopyrite) and oxides (rutile and goethite). While geochemically coal has a calorific value of 6052.6 cal./gr. (Subbitumionus A Coal), moisture 13.3% (adb), ash 4.0% (adb), volatile matter 41.5% (adb), fixed carbon 41.2% (adb), and sulfur content 1.77% (adb).

Scale effect testing on rocks is carried out with the aim of knowing the strength of a rock based on different dimensions. This test was carried out using a uniaxial compressive strength test and also testing the physical properties of rocks. In the rock compressive strength test used 5 dimensions of rock samples with a H/W ratio of which are 4.5/3, 6/3, 7.5/3 for dimensions of 3 cm, 5.25/3.5, 7 /3.5, 8.75/3.5 for dimensions 3.5 cm, 6/4, 8/4, 10/4, for dimensions 4 cm, 6.75/4.5, 9/4.5, 11.25/4,5 cm for the 4.5 cm dimension and for the 5 cm dimension, namely 7.5/5, 10/5 and 12.5/5. Physical properties testing is carried out to determine the porosity value in the test rock samples, which will then be compared between the porosity values ​​and the results of the compressive strength test of rock samples. Physical properties testing carried out obtained the average value of rock porosity, namely 22.562%, 22.122%, 20.454%, 21.227%, and 22.413%. In the scale effect test, it is known that the higher the rock sample, the smaller the value of the rock strength can be seen based on the R2 value obtained in the Balikpapan Formation, which is 0.0548.