STUDY OF NICKEL POWDER SYNTHESIS BY REDUCTION OF NICKEL ION IN NICKEL SULFATE SOLUTION USING HYDRAZINE HYDRATE AS A REDUCTANT

• Main Author: Sofyan, Shania
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/76036
• Institution: Institut Teknologi Bandung

The increasing demand for nickel and its derivatives provides an opportunity for Indonesia, as the world's largest nickel producer, to take advantage of it. After processing only high-grade nickel ore for a long time to produce ferronickel (FeNi), nickel pig iron (NPI), and nickel matte, now the domestic nickel ore processing industry has processed low-grade nickel ore and producing products such as mixed hydroxide precipitate and nickel sulfate. One of the other nickel derivative products that has good market potential is pure nickel powder. An effective nickel powder synthesis method that can produce products with certain characteristics is still being studied by many researchers. In this Final Project research, the process of synthesis of nickel powder from nickel sulfate solution by reduction method using hydrazine hydrate as a reductant was studied. A series of experiments on the synthesis of nickel powder by reduction of nickel sulfate solution using hydrazine reductants have been carried out to study the effect of the molar ratio of hydrazine to nickel ions ([N2H4]/[Ni2+]), the molar ratio of hydroxyl ions to nickel ions ([OH-]/[Ni2+]), system temperature, and reaction time on purity, particle size and morphology of synthesized nickel powder. The first stage of the experiment was carried out based on the experimental design with the Taguchi method using the L9 orthogonal matrix. After going through the process of solution preparation, reduction, precipitation, and product handling, the synthesized nickel powder were characterized by X-Ray Diffraction (XRD). From the results of the XRD analysis, the weight percent the phase was determined based on the Reference Intensity Ratio (RIR) method, and the data were processed to determine the “Larger the Better” Signal to Noise Ratios (S/N Ratio) and Analysis of Variance (ANOVA) parameters. Optimum conditions and the significant influence of the experimental variables in producing pure nickel powder obtained from data processing were used as the basis for the second stage of the experiment. The second-stage experiments aims to determine the effect of [OH-]/[Ni2+] ratio on the particle size, morphology, and purity of the synthesized nickel powder. The optimum condition that produced the highest nickel content of 91.95% was obtained from experiments with [N2H4]/[Ni2+] = 5, [OH-]/[Ni2+] = 15, temperature = 60 °C, and reaction time = 30 minutes. The contribution percentage of each factor in determining the product purity are [OH-]/[Ni2+] = 84.44%; reaction time = 9.65%; system temperature = 5.07%; and [N2H4]/[Ni2+] = 0.84%. Higher hydroxyl concentrations result in finer particle sizes. The morphology of the nickel particle is in correlation with its purity, in which spherical morphology can be achieved when the ratio [OH-]/[Ni2+] = 12,5 and the ratio [OH-]/[Ni2+] = 15.