Perpustakaan Digital ITB

Indonesia is one of the largest producers of laterite nickel ore in the world. The processing of nickel from this ore is generally carried out using the Rotary Kiln – Electric Arc Furnace route. This process involves high melting temperatures up to 1600 oC. The reactor is equipped with a heat-resistant protective lining, also known as a refractory, which separates the melt from the steel shell of the furnace. The interaction of refractories and melts for a long time can increase the risk of failure. Therefore, a water-cooled copper cooling system is often installed along the walls of the furnace to lower the average temperature of the refractories. This also allows the formation of a frozen slag lining so that heat transfer to the environment can be inhibited. Heat transfer that occurs along the refractory layer can be modeled with numerical simulations hence it can help in the process of designing electric furnaces. However, studies on refractories and copper coolers are limited. Thus, deeper investigations are needed to evaluate the copper cooler design and its effect to the temperature profile along the electric arc furnace lining as presented on this research. Series of simulations were carried out with the ANSYS Simulation Pack. Threedimensional geometries of the electric furnace had a height of 7 meters, excluding the supporting structure, with the smallest and largest internal diameters were 17.66 meters and 18 meters respectively. The geometries were composed of magnesia blocks, alumina blocks, fireclay, copper coolers, monel pipes, steel shell, and water. The boundary condition of constant temperature was applied to the inner surfaces of the furnace while heat transfer by convection and radiation to 25 oC was applied to the external surfaces. The simulation results showed that different circuit designs affect the performance of the copper cooler. The addition of a water circuit can reduce the average temperature of the copper cooler. The variations of the copper cooler arrangements produced different temperature profiles along the refractory lining. The maximum external temperature of the lining was reduced by 8.8 oC with the addition of a single line of copper cooler. Each of copper block has a length (inner - outer), width, and height of (798 - 849) millimeters, 580 millimeters, and 140 millimeters respectively. In contrast, the reduction of one line of waffle coolers with dimensions of length (inner - outer), width and height of (798 - 829) millimeters, 430 millimeters, and 360 millimeters resulted in an increase of about 10 oC of the copper coolers temperature as well as the hot area at the bottom of the furnace was getting wider.