Added Value of Limestone Batumilmil and Its Application in Industry

Abstract

This study explains the added value of the North Sumatra Langkat limestone and its derivative products. Limestone is classified as high calcium, characterized by its high calcium oxide (CaO) content of 38.39% -55.84%, its physical characteristics show dark gray color, dominant calcite, smooth, hard and fossilized texture. So far, the use is in the form of chunks, especially as a raw material for building which gives a low value to the limestone. The 3 limestone samples SK5, SK7 and SK8 were calcined to obtain quicklime and hydrated lime products with different temperatures of 900°C-1100°C. Limestone SK7 and SK8 CaO content increased 59.7% and 66.08% respectively and were light white compared to SK5 55.8% and colored brownish gray. To produce hydrated lime, it is done by adding / soaking with water (H2O) to the quicklime to produce a heat rate of hydration (slaked). SK8 limestone shows an optimum temperature increase of 74.6°C for 75 seconds compared to SK7 and SK5 limestone 50.2°C and 48°C respectively at 900°C combustion temperature. The heat transper occurs on the outer side of the limestone, then spreads to the limestone body. The difference in hydrated heat in the limestone is due to the presence of mineral impurities and non-uniform grain size so that the heat obtained is not perfectly distributed. The impurities such as SiO2, Fe2O3, Al2O3 and MgO contribute to the product quicklime and reactivity of these samples. Besides the quicklime and hydrated lime products, the added value of Batumilmil limestone is derived by making ground calcium carbonate (GCC). The GCC product is fine mesh size of 60 mesh - 400 mesh ultrafine, with high calcium quality and bright / bright color. The increase in added value added from limestone products contributes to the selling value and various applications in the industrial sector.