Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, -, Turkey
Approval Date: 2022
Thesis Language: Turkish
Student: HİLAL SEDA KUTLUATA
Supervisor: Özkan Murat Doğan
Abstract:
n the scope of this thesis, it is aimed to obtain nickel sulfate hexahydrate, which is an important cathode raw material in the battery industry, by developing a leaching process with phosphoric acid under atmospheric pressure as an alternative to the high pressure sulfuric acid leaching method of Gördes lateritic nickel ores. For this purpose, leaching of 70% limonite-30% nontronite ore with phosphoric acid under atmospheric conditions was carried out and compared with the leaching method for sulfuric acid both in atmospheric laboratory conditions and in high pressure conditions in the industry. Suitable leaching conditions were determined for obtaining phosphoric acid leaching and low iron-containing leaching solution after pre-heating of the ore. Studies have been carried out to determine the suitable ion exchange resin and operation conditions for nickel recovery from phosphate media, and innovations have been brought to the studies in which nickel is recovered from sulphate medias, with recovery studies made from phosphate media. Ion exchange studies were developed in terms of loading and desorbing, and the datas obtained from the shaking tests were studied in the column. Studies have been carried out to obtain nickel sulphate, which will serve the battery industry, by using the antisolvent crystallization method from the desorption solution, which has impurities such as cobalt, manganese, iron, aluminum and magnesium, as well as a nickel content of 4.5 g/L. Solubility values were determined separately for nickel, cobalt and iron sulfate, which are the main metals in the solution, in both acetone-water and isopropanol-water mixtures at different ratios. After it was decided to use acetone as an antisolvent due to its ease of recovery, precipitation efficiency and crystal morphology advantage, impurity control studies were carried out to increase the quality of the nickel sulfate crystal obtained from the desorption solution. NiSO4.6H2O crystals containing 22.3% Ni were obtained in 63.5% yield and 99.8% purity by adding the synthesized pure nickel sulfate core when pure acetone was added at 5 ml/min addition rate and reduced to 0.5 ml/min until O/S=2 ratio is obtained. Basic calculations of the energy required per kg nickel sulfate were made between the crystallization of the crystals obtained with the developed process by the classical evaporation-cooling method, and it was seen that crystals could be obtained with approximately 1.5 times less energy consumption with antisolvent crystallization. The leaching method followed in the thesis study was compared with the existing high pressure leaching method, and it was seen that the process designed in the thesis study is a safer and more economical process compared to the pressure leaching in technical and economic terms.
Key Words : Lateritic ore, atmospheric leach, ion exchange, antisolvent
crystallization, nickel sulphate hexahydrate