Resources and Reserves

Coal resources is part of a coal deposit which is expected to be utilized. These coal resources are divided into classes based on the resources of geological confidence level determined by the qualitative geological conditions / level of complexity and quantitatively by the distance between point of information. This resource can be increased to reserve if after the feasibility study to be feasible.
Reserves of coal (Coal Reserves) is part of the coal resources that have been known dimensions, distribution of quantity, and quality, which at the time of the feasibility study to be feasible to be mined.
The classification of coal resources and reserves based on the level of geological confidence and feasibility studies. Grouping contains two aspects, namely geological and economic aspects.
Classroom Resources


1. Coal Resources hypothetical
Hypothetical coal resource is coal in the area of investigation or part of the investigation area, which is calculated based on the data that meets the requirements set for the investigation phase of the survey review.
A number of resource classes that have not found the same with the expected coal reserves may exist in the area or region of the same coal under geological conditions or expansion of inferred coal resource. In general, resources are in areas where the sampling points and measuring the thickness and fiber evidence for the existence of coal taken from Distant outcrops, mining, digging holes, and wells. If the exploration of the truth of the hypothesis states that resource and much of the information revealed enough about the quality, number and rank, then they will be classified again as the identified resource (Identified resources).
2. Inferred Coal Resources (inferred Coal Resource)
Inferred coal resource is the amount of coal in the area of investigation or part of the investigation area, which is calculated based on the data that meets the requirements set for the investigation phase of prospecting.
Observation point has a considerable distance so that the assessment of the resources are not reliable. Local resources were determined from the projected thickness and overburden, rank, and quality data from the point of measurement and sampling based on geological evidence in the region between 1.2 km - 4.8 km. including anthracite and bituminous with a thickness of 35 cm or more, sub-bituminous with a thickness of 75 cm or more, lignite with a thickness of 150 cm or more.
3. Designated Coal Resources
Coal resources of appointed is the amount of coal in the area of investigation or part of the investigation area, which was calculated based on the data that meets the requirements set for the preliminary exploration stage.
Density and quality sufficient to make an observation point relistik interpretation of the thickness, quality, depth, and the amount of coal in situ and with good reason that the resources will not be interpreted to have a fairly large variation if a more detailed exploration conducted. Local resources were determined from the projection of the thickness and overburden, rank, and data quality from the point of measurement and sampling based on the evidence gteologi in the region between 0.4 km - 1.2 km. including anthracite and bituminous with a thickness of 35 cm or more, sib bituminous with a thickness of 75 cm or more, lignite with a thickness of 150 cm.
4. Measured Coal Resources
Measured coal resource is the amount of coal in the area peyelidikan or part of the investigation area, which is calculated on the basis of data which meets the requirements set for the stage of detailed exploration.
Density and quality sufficient for reliable observations point to an interpretation of coal thickness, quality, depth, and the amount of coal in situ. Local resources were determined from the projected thickness and overburden, rank, and quality data from the point of measurement and sampling based on geological evidence within a radius of 0.4 km. Including anthracite and bituminous with a thickness of 35 cm or more, sub-bituminous with a thickness of 75 cm or more, lignite with a thickness of 150 cm.
Resource Calculations
There are several methods that can be used to calculate the coal resource in the study area. The use of methods adapted to data quality, the type of data obtained, and the field conditions and methods of mining (eg mining angle). Because the data used in the calculation only in the form of outcrop data, the method used to enumerate the resources area of research is a method of Circular (USGS) (Figure).
circular Method (USGS)
Counting Rules Circular Method of Coal Resources (USGS) (Wood et al., 1983)
Calculations by the USGS coal resource may be calculated
Tonnase coal = A x B x C, where
A = weight of an average coal thickness in inches, feet, centimeters or meters
B = weight of coal per stuan the appropriate volume or metric tons.
C = area in acres or hectares of coal
The slope of the coal layer in the calculation also gives the effect of coal resources. When the coal seam has a different slope, calculations were done separately.
1. The slope 00-100
Tonnage calculation is done directly by using the formula Tonnase = thickness of coal x coal density x area of coal
2. The slope 100-300
For the slope of 100-300, the coal tonnage should be divided by the cosine value of the slope of the coal seam.
3. Slope> 300
For slope> 300, tonnage of coal multiplied by the cosine value of the slope of the coal seam.