Browsing by Author "Bouchekrit, Chafia"

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Production of Alpha-Alumina from Black Aluminum Dross Using NaOH Leaching Followed by Calcination
(SPRINGER, ONE NEW YORK PLAZA, SUITE 4600, NEW YORK, NY, UNITED STATES, 2020) Turk, Murat; Altiner, Mahmut; Top, Soner; Karaca, Serkan; Bouchekrit, Chafia; 0000-0003-3486-4184; 0000-0002-7428-5999; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü
The aim of this work is to produce alpha-alumina particles from aluminum (Al) dross via leaching-precipitation-calcination processes. In the leaching test, the effects of parameters such as the temperature, NaOH concentration, and time were investigated based on the Taguchi approach. In addition, the effect of the particle size on the Al extraction rate was determined. The Al extraction rate ranged from 78.64% to 93.11% and from 78.35% to 91.99% for ground dross and as-received dross, respectively. In the precipitation test, the pH of the leachate solution was decreased using HCl to remove Al ions as Al hydroxide precipitate. The precipitate was calcined at 1000 degrees C to 1200 degrees C for 270 min. The morphological and polymorphic properties of the products were characterized by scanning electron microscopy, atomic force microscopy, and x-ray diffraction analysis. The experimental findings indicated that the calcination temperature and stabilization time were critical for producing alpha-alumina particles rather than other polymorphs.
Production of Mn3O4 nanoparticles from a manganiferous iron ore via reductive leaching, precipitation, and calcination
(ELSEVIER, 2022) Altiner, Mahmut; Bouchekrit, Chafia; Top, Soner; Kursunoglu, Sait; 0000-0003-3486-4184; 0000-0002-1680-5482; AGÜ, Mühendislik Fakültesi, Malzeme Bilimi ve Nanoteknoloji Mühendisliği Bölümü; Top, Soner; Kursunoglu, Sait
The synthesis of Mn3O4 nanoparticles from a manganiferous iron ore through reductive leaching, precipitation, and calcination was investigated. The reductive leaching results showed that Mn (99.9%) was almost completely extracted into the leaching solution along with a substantial amount of Mg (99.9%), Al (99.5%), Ca (80%), and Fe (22.9%) under the following conditions: 30 g/L tartaric acid as a reducing agent, 1 M HCl solution, leaching temperature of 90 ◦C, and leaching duration of 3 h. In the first precipitation step, Fe and Al were expelled from the pregnant leach solution by the addition of NaOH prior to conducting the precipitation experiments for the production of manganese carbonate (MnCO3) particles from the purified solution. In the second precipitation step, MnCO3 particles were produced using sodium carbonate (Na2CO3) as the precipitating agent. The effects of parameters such as reaction temperature, Na2CO3 concentration, and experimental duration were investigated using the Taguchi approach. Manganse(II) was precipitated in the form of MnCO3 particles (97.4%) under the following conditions: a temperature of 30 ◦C, Na2CO3 concentration of 0.014 mol/L, and duration of 30 min. The precipitate was observed to have a structure similar to that of rhodochrosite (MnCO3). Thermogravimetric/ differential thermal analyses were subsequently performed in three different atmospheres (air, oxygen, and nitrogen) to select a suitable atmosphere for calcination. The experimental results indicated the formation of hausmannite (Mn3O4) with a purity of 97.5% Mn3O4, 0.42% MgO, 1.66% CaO, and 0.34% FeO. The specific surface area, particle size, Curie temperature, magnetisation, coercivity, and remanence ratio of the final product obtained via 3 h of calcination at 350 ◦C were estimated to be 133.3 m2 /g, <142.2 nm, 56 K, 10.10 Am2 /kg, 0.35 T, and 0.19, respectively. The characterisation results revealed the excellent low-temperature ferromagnetic properties of the produced Mn3O4 nanoparticles.