Dependence and interaction between several operating conditions that affect the grinding process using a ball mill such as the number of balls, grinding duration, and rotational speed on particle size at 80% product mass (P80) and mineral liberation have been obtained in this study using a CCD (central composite design) of response surface method (RSM). The grinding process was carried out in a cylindrical ball mill with a diameter and length of 18.6 cm and 21.5 cm, respectively, as well as a steel ball with a diameter of 2.5 cm and a weight of 100 grams/ball. The optimum data for the grinding process was obtained with the smallest response value of P80. It was known that the number of balls and grinding duration have a significant effect on the reduction of the P80 value in the sample. The model that can describe the influence of process variables on the P80 value was obtained with good accuracy. The character of the mineral content of the sample was observed with the X-Ray Diffraction (XRD) pattern and the elemental concentration. Minerals that have a smaller hardness scale are easier to liberate and more exposed. The P80 value of the initial material was 1560.89 µm, while at the optimum condition the P80 grinding process was reduced to 513.29 µm.
Today, nickel plays a critical role in the industry. However, the presence of this metal in its primary source of sulfide minerals is decreasing. The focus of exploration has since turned to laterite ore, which contains up to 80% nickel metal. The purpose of this study is to optimize nickel leaching using sulfuric acid and to conduct kinetic analysis to discover the mechanism that best controls the leaching process. To optimize operating conditions, the response surface method (RSM) with box behnken design is used. The shrinking core model and the Zhuravlev, Leshokin, and Templeman (ZLT) model were used to assess the kinetics of the nickel leaching process. Mineral characterization was also performed to gain a better understanding of the sample's characteristics. At 2 M sulfuric acid, 10% S/L ratio, and 90 o C, the highest nickel recovery of 85% was observed. The obtained apparent activation energy is 32.78 kJ/mol.
Indonesia is well-known for its abundant coal reserves but is included in low-rank coal with a total moisture content of 40%. In the combustion process, this water content will reduce the calorific value so that the use of coal becomes inefficient and not environmentally friendly. The purpose of this study was to determine the effect of added additives to residual oil to improve the quality of sub-bituminous coal originating from Sangatta, East Kalimantan. Variations of additives used include NaOH, HCl, and Pertalite, mixed with residual oil. The results in this study indicate an increase in calorific value in each composition of mixed additives. The best results were obtained for residual oil mixtures with pertalite, which obtained coal with a calorific value of 7204 cal/g, moisture content 16.9%, ash content 3.5%, carbon content 40.7%, sulfur content 0.41%, and flying substance content 38.9%.
Today, nickel plays a critical role in the industry. However, the presence of this metal in its primary source of sulfide minerals is decreasing. The focus of exploration has since turned to laterite ore, which contains up to 80% nickel metal. The purpose of this study is to optimize nickel leaching using sulfuric acid and to conduct kinetic analysis to discover the mechanism that best controls the leaching process. To optimize operating conditions, the response surface method (RSM) with box behnken design is used. The shrinking core model and the Zhuravlev, Leshokin, and Templeman (ZLT) model were used to assess the kinetics of the nickel leaching process. Mineral characterization was also performed to gain a better understanding of the sample's characteristics. At 2 M sulfuric acid, 10% S/L ratio, and 90 oC, the highest nickel recovery of 85% was observed. The obtained apparent activation energy is 32.78 kJ/mol.
Nickel (Ni) deposits are depleting, while demand for the metal is increasing. To address this problem, valuable metals such as Ni and Fe can be extracted from secondary sources such as limonite-type laterite ores. The goal of this study was to investigate the influence of leaching temperature on Ni and Fe recovery, as well as the best kinetic model to represent the leaching process of these metals. Temperature has a considerable impact on the leaching process of Ni and Fe. Increasing the temperature from 30 to 90 oC can increase the recovery of Ni by 50% and Fe by 70 %. Ni and Fe recoveries were highest at 93.21 % and 95 %, respectively. Kinetic analysis of the two metals' leaching processes was also performed. It was discovered that the diffusion process controls Ni leaching, which can be represented using the Zhuravlev kinetic model, whereas chemical reactions on the surface of the unreacted core controls Fe leaching. The activation energies for leaching Ni and Fe are 36.53 and 40.32 kJ/mol, respectively. 1930 exp ((-36.53 kJ/mol)/(R.T))t=[(1-X)-1/3)-1]2 is the kinetic equation for Ni leaching. The kinetic equation for Fe leaching is 3903 exp ((- 40.32 kJ/mol)/(R.T)t=1-(1-X)1/3.
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