Coal is a non-renewable energy source and has a role that almost competes with petroleum. In this connection, it is necessary to explore and inventory coal resources. One of the exploration stages is drilling where data from drilling results can be used for coal resources and reserves estimation. PT Kideco Jaya Agung is one of the biggest coal mining companies in Indonesia, located in Paser District, East Kalimantan Province. In carrying out its drilling, PT Kideco uses the open hole, touch coring, and full coring drilling methods then compares it with the results of geophysical logging to obtain accurate coal thickness and depth data. Drilling data was obtained in the form of rock samples. The logging process is carried out after the drilling stage is complete. Logging methods used are gamma-ray logs, density logs, HRD logs, and BRD logs. Lithology interpretation is done by comparing rock sample data and log curves. The results of the interpretation of coal seams in drill hole ZA04 were found at a depth of 102.5 – 128.5 m with a true thickness of 10.78 m and in drill hole ZA05 coal was found at a depth of 106.2 – 121.7 m with a true thickness of 3.63 m.

Laterite nickel deposits are formed from the intense weathering of ultramafic igneous rocks. The distribution of Ni content in an area does not always have a stationary data. One method of resource estimation and precise geological modeling is the Empirical Bayesian Kriging (EBK) method which is known to be able to perform precise estimates for stationary and non-stationary data. The results of this study were found that thickness of the limonite layer will increase as the slope decreases, while in the saprolite zone the thickness will increase with increasing the degree of slope up to the limit of 16°-25° then the thickness will decrease when crossing that limit. In the limonite zone, the concentration of Ni is maximally concentrated at a high degree of slope (>16°), while in the saprolite zone, Ni content is maximally concentrated on a slope of 16°-25° and then decreases in Ni content when passing through a slope of 25°. Validation of the estimation results and geological modeling using RMSE, MAE, MAPE, and linear regression in the limonite and saprolite zones indicate that the EBK method is a precise method for resource estimation and geological modeling.

South and West Sulawesi has coal resources of about 117 million tons or about 0.35% of the total resources nationally. Bulupoddo coal located in Sinjai Regency is a type of coal that is categorized as low rank coal. This study was conducted to identify the minerals contained in coal and its flanking rock (roof and floor) and determine the rank and quality of coal. The methods used are mineralogy and coal quality analysis methods. Field observations shows a type of coal that is about 50 cm thin and flanked by clay and sandstone. The results of microscope and XRD analysis (X-Ray Diffraction) showed minerals contained in Bulupoddo coal, namely in BP-01B (coal) and BP-01E (coal) samples containing kaolinite, illite, pyrite and quartz minerals. In the flanking rock samples, the samples of BP-01A (clay) and BP-01D (clay) contain the minerals kaolinite, illite, pyrite, quartz and chlorite. In the BP-01C (sand) sample indicated as sandstone contains feldspar, quartz and kaolinite minerals. The results of the coal quality analysis that have been carried out on the two coal samples, namely BP-01B and BP-01E, show that the BP-01B sample has a moisture content of 7.74%, an ash content of 54.23%, volatile matter is 23.35%, fixed carbon 14.68%, and total sulfur content by 0.37%. While the sample BP-01E has a moisture content of 9.2%, ash content of 67.76%, volatile matter 18.23%, fixed carbon 4.81% and sulfur content is 0.49%. The calorific value of the test results shows that the coal sample BP-01B has a calorific value of 1953 kcal/gr and BP-01E has a calorific value of 853 kcal/gr. The calorific value of Bulupoddo coal is categorized as lignite B type coal according to coal classification based on ASTM (American Society of Testing Materials).

Indonesia is a country with a tropical climate that allows for high levels of weathering. Bauxite is the result of weathering rocks that have high aluminum content, low iron content, and little quartz content. The formation of bauxite deposits is controlled by source rock which is rich in Al element, tropical climatic conditions, and geomorphological conditions that allow the formation of the accumulation of weathered source rock products. The altered silicate minerals due to weathering result in the silica element being released from the crystal bonds and some iron are released so that the aluminum element is concentrated as a residual precipitate. X-ray diffraction (XRD) analysis on 16 bauxite samples which are estimated to represent the overburden horizon, bauxite ore horizon, clay horizon, and source rock to establish the mineral composition of bauxite. Mineral groups in the overburden horizon, bauxite ore horizon, and clay horizon are alumina, iron, titanium, silicates, carbonates, sulfides, and sulfates, while mineral groups in source rock are iron, titanium, silicate, sulfide, and sulfate. The type of bauxite in the study area is gibbsite bauxite based on the dominant appearance frequency of gibbsite compared to mineral corundum as an alumina group.

Low rank coal is still less attractive to consumers because it is difficult to market and exploits. One of the parameters used for coal export or trading is calorific value. The disadvantage of low rank coal is the high moisture content. The high moisture content will cause problems in the process, especially if it is used as direct fuel and of course affects lower calorific value. The study aims to determine the characteristics of the coal samples used in the study, and to analyze the effect of mixing ratio and temperature on the quality of coal after being mixed with waste cooking oil. Further aim is to analyze the changing process of coal quality after the upgrading process. The study was conducted by mixing coal with waste cooking oil using the ratio of mixture ratio, temperature, and time. The comparison of coal before and after being mixed is seen from the results of proximate and calorific value analysis. The calorific value of the initial coal sample is 5,296.19 calories/gram and waste cooking oil is 7,080.33 calories/gram. The results showed that the mixing ratio (coal: waste cooking oil) 1:1, 1:1.5, and 1:2 using a temperature of 150°C obtained a calorific value of 6,733.02 calories/gram, 5,694.59 calories/gram, 5,295.45 calories/gram. The calorific value of a 1:1 ratio using temperatures of 175°C and 200°C is 6,965.51 calories/gram and 6,493.59 calories/gram. These results indicate that a 1:1 ratio with a temperature of 175°C is the most optimal condition for mixing coal with waste cooking oil.

Bulupodo coal has a fairly high ash content and low total sulphur. The main objective of this research is to reduce the ash content in Bulupodo coal. The methods used was chemical washing of coal using hydrogen peroxide (H 2 O 2 ) with washing variables such as time (30 minutes, 60 minutes, 120 minutes, and 180 minutes), H 2 O 2 concentration (5%, 10%, 15%, and 20%), temperature (45°C, 60°C, and 80°C) and particle sizes (16 mesh, 40 mesh, and 70 mesh). The results of the quality analysis show that Bulupodo coal has a moisture of 6.37%; ash 53.3%; volatile matter 26.79%; fixed carbon 14.45%; and a total sulfur of 0.53%. Hence, mineral matter analysis using microscopic and XRD (X-Ray Diffraction) show that Bulupodo coal contains kaolinite, illite, quartz, and pyrite minerals. As a result washing with the highest reduction time variable of ash content at 180 minutes was 21.63%; the concentration variable of the highest ash content reduction solution was at a concentration of 20% of 14.78%; the temperature variable for the reduction of the highest ash content at 60°C was 13.45%; and the particle size variable for the reduction of the highest ash content was at a particle size of 40 mesh of 7.32%.