Abstract:
Type of coal is ussually used for steamelectrical powergeneration and industries is a certain type. As asource of energy at electrical generation then the physical and chemical properties of coal should be considered carefully. One of its properties that should be paid attention is grinda bility property which is known as the value of GHI (Hardgrove Grindability Index). The value describes the easyness of coal to begrinded. The low value of HGI shows that the coalishard and dificult to be crushed. The HGI value of coal is needed for the equipment design of power generation because the capacity of
grinding unit relates to the amenity of coal reduction. This research on the effect of temperature to HGI value result sare:
> Heating was conducted at temperature of 50 with heating time variations of 30, 60, 90, and 120 minutes yielding the highest HGI value was 41 at 50 C and 120 minutes heating time.
> The experiment was continued at temperature of 50 C and the heating time up to 240 minutes then yield the GHI value of 50.
> The effects of heating on other properties of coal such as water content, ash content, fly ash content, solid carbon content and calory value induce significant alterations in which the water content of 4,68% became 0,80%, the solidcarbon content of 52,94 % became 54,37%; and the calory value of 7.912,4 cal/gram became 7857,1 cal/gram.
Heating temperature on HGI value does not require high temperature but requires a longerheating time in which the minimum heating time is 120 minutes.
