Pressure leaching of Çaldağ lateritic nickel ore

Önal, Mehmet Ali Recai
The purpose of this study was to investigate the process optimization of combined high pressure acid leaching (HPAL) and mixed hydroxide precipitation (MHP) route for the extraction of nickel and cobalt from Çaldağ lateritic nickel ore. In order to extract nickel and cobalt values into pregnant leach solution (PLS), several process parameters of HPAL including acid load, temperature, leaching duration and particle size were investigated in comparative manner at constant solid concentration and agitation speed. After HPAL trials, it has been found that more than one combination of parameters offered higher than 90% extraction efficiencies for both nickel and cobalt. Among them, 0.325 kg/kg acid load, 250°C, 1 hour duration and 100% -1 mm particle size was selected as the optimum conditions with 94.1% Ni and 94.0% Co extractions. A stock of PLS was prepared under the stated conditions that was treated by downstream operations in order to obtain MHP. Initially by two-stage iron removal of downstream operations major impurities iron, chromium and aluminum were nearly completely removed with acceptable nickel and cobalt losses from PLS. Then, the nickel and cobalt were precipitated by two-stage mixed hydroxide precipitation. In the first step of MHP, the optimum conditions were chosen as pH=7.10, 60°C and 1 hour duration. The intermediate product obtained at these conditions contained 44.3% Ni, 3.01% Co with 3.06% Mn contamination. In summary, it was found that Çaldağ nickel laterite ore was readily leachable under HPAL conditions and PLS obtained was easily treatable in order to produce saleable MHP.


Pressure leaching of Sivrihisar-Yunus Emre nickel laterites
Seçen, Berk; Topkaya, Yavuz Ali; Department of Metallurgical and Materials Engineering (2011)
The aim of this thesis study was to extract nickel and cobalt from Sivrihisar limonitic nickel laterite ore by high pressure acid leaching (HPAL) method under most economical operating parameters. Optimizing the conditions to yield a saleable quality mixed hydroxide product from the pregnant leach solution (PLS) was also investigated. To extract high amounts of nickel and cobalt from the laterite matrix; leaching duration, leaching temperature and sulfuric acid/ore ratio were studied at fixed conditions of ...
Pressure acid leaching of Caldag lateritic nickel ore: An alternative to heap leaching
Onal, Mehmet Ali Recai; Topkaya, Yavuz Ali (Elsevier BV, 2014-02-01)
In this study, the leachability of Caldag lateritic nickel ore under high pressure acid leaching (HPAL) conditions was investigated. Several HPAL parameters were tested in a comparative manner since in many cases, the extraction efficiencies of Caldag ore sample were more than 90% for nickel and cobalt. After the optimization of the process parameters, it was found that 94.1% nickel and 94.0% cobalt could be extracted under the conditions of 325 kg sulfuric acid/tonne of dry ore, 250 degrees C leaching temp...
High pressure acid leaching of a refractory lateritic nickel ore
MUTLU KAYA, SEVCAN; Topkaya, Yavuz Ali (2011-09-01)
This paper describes the experimental findings of the extraction of nickel and cobalt by high pressure acid leaching (HPAL) of a refractory limonitic nickel laterite ore from the Gordes region of Manisa in Turkey. By optimizing the basic HPAL process parameters: leaching at 255 degrees C with 0.30 sulfuric acid to ore weight ratio with a particle size of 100%-850 mu for 1 h of leaching, it was found that 87.3% of nickel and 88.8% of cobalt present in the ore could be extracted into the pregnant leach soluti...
Comparative study of high pressure and atmospheric acid leaching for the extraction of nickel and cobalt from refractory nickel laterite ores
Korkmaz, Kıvanç; Topkaya, Yavuz Ali; Department of Metallurgical and Materials Engineering (2014)
In this MSc thesis, the refractory minerals that may be present in limonitic nickel laterite ores will be tried to be leached under the optimum conditions of high pressure and atmospheric acid leaching. The results of the different methods of leaching to be obtained will be compared in terms of the Ni and Co extractions.
Partial oxidation of methane on the SiO2 surface - A quantum chemical study
Ozturk, S; Onal, I; Senkan, S (2000-02-01)
Reaction pathways for methane partial oxidation (MPO) on silica were theoretically investigated using the semiempirical MOPAC-PM3 molecular orbital method. The surface of SiO2 was modeled by a helical Si6O18H12 molecular cluster that also exhibits a strained siloxane bridge defect. First, a bond energy analysis was performed on the silica cluster with isolated 3- and 4-coordinated Si surface atoms. Calculated bond dissociation energies for Si-H, SiO-H, and SI-OH were comparable to H-CH3, H-OH, and O-O. In t...
Citation Formats
M. A. R. Önal, “Pressure leaching of Çaldağ lateritic nickel ore,” M.S. - Master of Science, Middle East Technical University, 2013.