STUDY ON THE SEPARATION OF DISSOLVED IRON FROM LEACH SOLUTION OF HALMAHERA NCIKEL LATERITE ORE AND PRECIPITATION OF NICKEL HYDROXIDE

• Main Author: (NIM : 12506022), MUAMMAR
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/23146
• Institution: Institut Teknologi Bandung

One of the processing routes for low grade nickel laterite ore of limonite type is through leaching in sulhuric acid solution. During the leaching of the limonite ore in sulphuric acid at atmospheric presssure, the dissolution of nickel is followed by co-dissolution of impurity elements, which include iron, magnesium, aluminium and chromium. In order to recover nickel from the leach solution and produce a product with high grade nickel, the dissolved impurities, mainly iron must be <br /> <br /> <br /> <br /> removed. Series of experimental work have been carried out to separate iron selectively from the leach solution produced from the leaching of Halmahera ore. Iron-free solution from the leaching and that of artificial solution is then treated to produce nickel hydroxide precipitate as an intermediate product. The experimental work is initiated by by conducting leaching of nickel limonite at the temperature 95oC. The leach liquor is then purified with three different methods, which include the additions of Na2SO4 salt, H2O2 and aeration followed the addition of calcium hydroxide to reach pH level of 2. The filtrate which is separated from the iron precipitate is analyzed Atomic Absorption Spectroscopy (AAS) to determine the recidual concentration of dissolved iron and nickel and the percentage of iron precipitation and co-precipitation of nickel. AAS whereas the residue formed is analyzed by XRD for verifiying phase composition. Following the precipitation of iron, recovery of nickel as mixed nickel hydroxide precipitate are acrried out at temperature range of 30 to 60 0C and the pH levels of <br /> <br /> <br /> <br /> 7 until 9 from the purified leach solution and artificial solutions. The experiment result show that the precipitation of iron by adding sodium sulfate <br /> <br /> <br /> <br /> exhibit the best result in term of the percentage of iron precipitation compared to the addition of H2O2 and aeration. The addition of 8 gr/L of Na2SO4 salt at pH 2 to the leach solution results in the precipitation of iron of 96,98%, while coprecipitation of nickel is at the level of 21%. The result of X-Ray Diffraction XRD) analysis detecs Fe in the form of butlerite. The precipitation of nickel hydroxide at temperature of 60oC and pH level of 9 result in 99,99% precipitation rate. SEM and EDX analysis detected the presences of nickel, cobalt and iron at several spots on the surface of the precipitate. However, iron hydroxide can not identified by XRD analysis, where gypsum is detected as the major constitutent of the nickel precipitation product. In order to avoid gypsum co-precipitation that contaminate the precipitation product, pH adjuster reagents which have low solubility at sulphate soltuion, such as MgO and NaOH should be used.