Lateritik nikel cevherinden nikel ve kobalt kazanım koşullarının geliştirilmesi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Bu çalışmada, Manisa-Çaldağ bölgesinden temin edilen limonitik tip laterit cevherinin atmosferik basınçta sülfürik asit liç koşullarının geliştirilmesine çalışılmıştır. Cevher karakterizasyonunu takiben, mekanik aktivasyon parametreleri olan bilya/numune oranı ve süre çalışılmış ve liç prosesinde kullanılmak üzere parametreler karakterizasyon işlemlerine göre sabitlenmiştir. Karakterizasyon çalışmalarında, XRF, XRD, SEM-elementel haritalama, FTIR, DTA-TGA metotları kullanılmıştır. Aktive olmamış cevherin liç çalışmalarında, sıvı/katı oranı, asit oranı, süre, sıcaklık, nitrik asit ilavesinin etkisi araştırılmıştır. Aktive olmuş cevherde ise sadece süre ve sıcaklık çalışmaları gerçekleştirilmiştir. Çözelti analizi, atomik absorbsiyon spektroskopisi ile gerçekleştirilmiştir. Aktive olmamış cevherde sıvı/katı oranının arttırılması ile önemli bir değişiklik tespit edilememiştir. 95°C'de 240 dk liç süresinde denenen asit konsantrasyonları olan %10 ve %20 birbirine yakın nikel ekstraksiyon sonuçları vermiştir. Süre ve sıcaklık deneylerinde ise sıcaklığın süreden daha etkili bir parametre olduğu tespit edilmiştir. Düşük sıcaklıklarda, uzun sürelerde elde edilen metal ekstraksiyonlarının, sıcaklık arttıkça daha kısa sürelerde elde edildiği tespit edilmiştir. Sülfürik asite nitrik asit ilavesinin, metal verimlerinin artışında çok fazla etkili olmadığı tespit edilmiştir. 15 ve 60 dk. aktive edilen cevherlerin liç verimleri aktive edilmemiş cevherin verimlerine göre, düşük sıcaklık ve sürelerde daha iyi sonuçlar sergilemişlerdir. Aktive olmuş cevherlerde 95°C'de 5 dk. liç süresinde %70'in üzerinde verim elde edilmiştir. 5 dk.'dan sonra ise giderek yavaşlayan bir şekilde verimler artmıştır. Yapılan kinetik çalışmada, mekanik aktive olmuş cevherlerde aktivasyon enerjisinin düştüğü tespit edilmiştir. Aktive olmamış ve mekanik aktive olan cevherden nikel, kobalt ve demir çözünürlüğünün difüzyon kontrollü olduğu fakat mekanizmasının farklı olduğu anlaşılmıştır. Liç sonrası yapılan katı atık karakterizasyonu da bu durumu doğrulamıştır. Mekanik aktive edilmiş cevherin atıklarında amorf silika oluşumu ve hematit pik şiddetinin artışı tespit edilmiştir. Sülfatlayıcı kavurmayı takiben yapılan su liçi sonucu, sülfatlamada kullanılan sülfürik asit miktarının arttırılması ile demir çözünürlüğünün de arttığı tespit edilmiştir. Kavurma sıcaklığının demir sülfatın parçalanıp demir okside dönüştüğü, nikel ve kobalt sülfatın parçalanmadan kaldığı sıcaklıklarda yapılması, çözeltiye demir geçişini engellemiştir. Mekanik aktivasyonun çözünmeyi oldukça hızlandırdığı, oldukça kısa sürelerde bile yüksek verim elde edilebileceği, sülfatlayıcı kavurmanın ise çözeltiye demir geçişini engelleyebileceği sonucuna varılmıştır.In this study, it was tried to develop atmospheric sulfuric acid leaching conditions of limonitic type laterite ore obtained from Manisa – Çaldağ region. Following the characterization of the ore, the ratio of the ball-to-mass ratio and duration which are parameters of mechanical activation were studied and the parameters for the leaching process are fixed according to the characterization process. XRF, XRD, SEM-elemental mapping, FTIR, DTA-TGA methods were used in the characterization studies. The effects of liquid / solid ratio, acid ratio, duration, temperature, nitric acid addition on the leaching of non-activated ore were investigated. Only time and temperature studies have been carried out on activated ore. Pregnant solution analysis was performed by atomic absorption spectroscopy. No significant change could be detected by increasing the liquid / solid ratio for non-activated ore. At 95°C, the acid concentrations of 10% and 20%, which were tested in the leaching for 240 min, yielded nickel extraction results close to each other. It has been determined that temperature is a more effective parameter than temperature in time and temperature experiments. It has been found that, at low temperatures, the metal extractions obtained over a long period of time are obtained in shorter times as the temperature increases. It has been found that the addition of nitric acid to sulfuric acid is not very effective in increasing metal yields. Leaching efficiencies of ore activated for 15 and 60 min exhibit better results at lower temperatures and times than those of non-activated ore. The activated ore has yields above 70% for 5 min leaching at 95°C. After 5 min, yields increased gradually. In the kinetic study, it was found that activation energy decreased in mechanically activated ores. It showed that the nickel, cobalt and iron solubility of the non-activated and mechanically active ores were diffusion controlled, but the mechanism was different. Solid waste characterization after leaching also confirms this. Amorphous silica formation and increase in hematite peak intensity in the mechanically activated ore waste were detected. It has been determined that increasing the amount of sulfuric acid used in the sulphating process increases the solubility of the iron in the water leach resulting from the sulphating roasting. Roasting at temperature which iron sulphate decomposes and turn into iron oxide, nickel and cobalt sulphate remain untouched, iron dissolution was prevented. It was concluded that mechanical activation accelerates the dissolution, achieving high efficiency even in a relatively short period of time, and sulphation roasting can prevent to iron dissolution

Zeolite usage as source of silica to produce cordierite in MgO-Al2O3-SiO2 system

In this study, natural zeolite was used as source of silica to produce cordierite. MgO and Al2O3 were added to zeolite to obtain the cordierite stoichiometry. Mixture of these raw materials was mechanically activated for different durations. The mechanically activated powder mixture was characterized using XRD, DSC, SEM, specific surface area, and particle size analyzer. The pycnometer method was used to measure the densities of mechanically activated powder mixtures. Mechanically activated for 60 min powder mixture was sintered at 1150-1350 degrees C for 1 h. The sintering behavior of the samples was determined by measuring the linear shrinkage, density, and apparent porosity. The phases in the sintered samples were identified by XRD. Cordierite and spinel phases were detected for sintered at a temperature higher than 1150 degrees C but corundum accompanied to cordierite and spinel at 1150 degrees C. The microstructure of the samples was examined using both SEM and AFM. The sintering behavior and microstructural properties of the samples changed with an increase in the sintering temperature. As the apparent porosity increased with increasing sintering temperature, linear shrinkage and density values decreased. Density values were determined as 2.31-2.69 g/cm(3) depending on the temperature. The grains coarsened at higher temperature and the average grain size depending on the temperature was 1.34-1.96 m. From the results optimum sintering temperature was determined as 1250 degrees C. Dense material was produced at a temperature as low as 1250 degrees C using zeolite as raw material

Effect of Sodium Sulfate Addition on the Production of Ferronickel from Lateritic Ore

Lateritic nickel ore from Manisa - Caldag region was roasted to form ferronickel at 1200 degrees C for 1 h with additions of metallurgical coke and sodium sulfate varying by weight 5-15% and 0-20%, respectively. Formed metallic part of roasted sample was separated from non-metallic part by magnet and examined by means of X-ray diffraction analysis and scanning electron microscopy. In spite of kamacite alpha-(Fe, Ni) formation, iron-rich silicate structure that causes iron losses was observed for samples roasted with only coke. Kamacite formation increased with increment of the coke percentage but iron-rich silicate structure remained almost same. With addition of sodium sulfate, elimination of iron-rich silicate phase was achieved and easily magnetizable metallic particles were obtained

EFFECT OF ACID CONCENTRATION ON THE EXTRACTION OF NICKEL FROM LATERITE

Nickel is essential metal due to usage area as stainless steel, non-ferrous alloy production, electroplating and chemical industry. Degradation of nickel sulphides leads to extraction of nickel from laterites. High cost equipment of high pressure acid leaching and since heap leaching needs longtime, atmospheric acid leaching of laterites becomes popular. Parameters of atmospheric leaching are important in terms of acid consumption, content of pregnant solution and residue. Therefore in this study, lateritic nickel ore from ManisaCaldag/Turkey was leached for determining acid concentration parameter, both sulfuric acid and nitric acid sulfuric acid mixture with varying percentage by volume. XRD analysis of lateritic nickel ore was showed that the ore mainly consist of quartz and goethite. Pregnant leach solutions were analyzed with atomic absorption and leach residues were characterized by X-ray diffraction and scanning electron microscopy. Increment of acid concentration caused increased nickel content in the solution but iron content increased as well

Effects of Sulfation Roasting and Sodium Sulfate Addition on Dissolution of Nickel and Cobalt from Laterite

In this study, lateritic nickel ore from Manisa-Caldag, Turkey was subjected to sulfation roasting. Experimental parameters were as follows, acid concentration (10-90 wt.%), roasting temperature (200-900 degrees C) and time (15-90 min). Effect of sodium sulfate addition (1-9 wt.%) on dissolutions of nickel and cobalt was also investigated. It was concluded that iron dissolution has increased with increased acid concentration. Dissolutions of nickel and cobalt increased with increasing roasting temperature and time below the decomposition temperature of related metal sulfates. It was concluded that addition of sodium sulfate in roasting stage has no significant effect on dissolutions of related metals

Low temperature formation of barium titanate in solid state reaction by mechanical activation of BaCO3 and TiO2

In this study, the effects of mechanical activation on BaTiO3 formation from BaCO3 and TiO2 powders were investigated. Differential thermal analysis (DTA), high-temperature x-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FT-IR) studies were performed following the mechanical activation of the powder mixture to reveal the phase formation and structural changes. In addition, the powder mixtures were sintered at 1350 degrees C for 3 h. Structural differences between the non-activated and activated samples were observed with scanning electron microscopy (SEM), and their electrical properties were measured to study the effects of mechanical activation. It was observed that mechanical activation increased the chemical reactivity of BaCO3 and TiO2 powders, causing amorphization and structural disorder in their structures. These were confirmed with XRD and FT-IR analysis. The 120-min activation of a mixture of barium carbonate and titania caused a decrease in the formation temperature of the Ba2TiO4 phase from 815 degrees C to 640 degrees C, while the formation temperature of the BaTiO3 phase decreased from 1095 degrees C to 890 degrees C. It was observed that the dielectric constants of the samples were increased by increasing the mechanical activation time

Formation of SrTiO3 in mechanically activated SrCO3-TiO2 system

In this study, mechanical activation process was used for intimate mixing as well as producing finely ground particles, increased surface area and improved chemical reactivity of milled materials for producing SrTiO3 from commercially pure strontium carbonate and TiO2 as a contributive process. Characterization of milled powder mixture by X-ray diffraction analysis showed that disappearing, decreasing and/or shifting of the patterns occurred with mechanical activation that means amorphization was taken place. Amorphization was also demonstrated by FT-IR analysis where shift of band centers as well as the decrement of transmittance related to CO3 was observed. Advantage of amorphization was established with high-temperature XRD analysis which showed 1300 A degrees C was not enough for non-activated mixture to form SrTiO3, whereas structure only composed of SrTiO3 at 1000 A degrees C for activated ones. The reason for this phenomenon was investigated by DTA-TG analysis, and it was based on energy accumulation originated from mechanical activation that corresponds to peak temperature shifting to the lower temperatures and CO2 liberation at mechanical activation step arising from local temperature rising at the vial during high-energy milling that was understood from peak temperature, and area decrement of endothermic peak corresponds to decomposition of SrCO3

Dehydroxylation of high-energy ball-milled diasporic bauxite

In this study, diasporic bauxite was mechanically activated for different durations (15, 30, 60, 90 and 120 min) by the planetary mono mill. The speed of the main disk and ball-to-mass ratio were kept constant at 600 rev min(-1) and 25, respectively. The chemical composition of the ore was determined via X-ray fluorescence. Structural changes and thermal behavior were examined by X-ray diffraction analysis (XRD), Scanning electron microscopy (SEM), differential thermal analysis-thermogravimetry (DTA-TG) and Fourier transform infrared spectroscopy (FTIR). Diaspore, hematite and anatase were detected at XRD analysis, and with an increment in activation time, the intensity of the peaks decreased, and position and width of the peaks changed as well. In DTA analysis, with mechanical activation, the temperature of the endothermic peak that corresponds to dehydroxylation of the aluminum hydroxide was lowered and area of the peak was decreased. These results mean that the structure was disordered with mechanical activation

Structural Alterations in Smithsonite during High-Energy Ball Milling

Smithsonite, ZnCO3, from Zamanti-Kayseri, Turkey, was subjected to high-energy milling. X-ray diffraction analysis was performed to study amorphisation in the structure and the alterations of bands in the structure were investigated by Fourier transform infrared spectroscopy. Characterization of milled smithsonite by X-ray diffraction analysis has shown that disappearance, decrease and/or shifting of the patterns occurred with mechanical activation, which means that amorphisation was taking place. Amorphisation was also demonstrated by Fourier transform infrared spectroscopy analysis, where shifting of band centers was observed

Springer Proceedings in Physics

Cordierite (2MgO. 2Al(2)O(3).5SiO(2)) that is known as a high technology ceramics was produced from mechanically activated powder mixture with the intention of increasing the reactivity of substance. The powder mixture consisted of zeolite that was used as a source of silica, pure MgO, Al2O3 and ZrO2. During powder preparation, mechanical activation duration, speed of main disc and ball to mass ratio was kept constant at 60 min, 600 rpm and 20: 1, respectively. After compacting of the mechanically activated powder mixture, the samples were sintered at 1250 degrees C for 1 h. The sintered samples were analyzed by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The sintering behavior of the samples was determined by measuring the linear shrinkage, water absorption, density and apparent porosity. The hardness measurements were performed by using a Vickers microhardness tester under the load of 500 gf for 10 s. The density of samples ranged between 2.554 and 2.777 g/cm(3) depending on ZrO2 additive. The hardness values of the undoped sample, the sample containing 10 % Zirconia and the sample containing 20 % Zirconia were found as 8.63, 9.60 and 11.9 GPa, respectively