Murat Erdemoğlu

The leaching of SrS with water and the precipitation of SrCO3 from leach solution by different carbonating agents

Abstract The leaching of strontium sulfide (SrS) with water was investigated, and a comparison of Na 2 CO 3 with CO 2 as a carbonating agent for the precipitation of SrCO 3 from leach solution was done. The effects of variables for leaching—temperature, retention time and solid to liquid ratio, and the effects of variables for precipitation—carbonation time, temperature, amount of carbonating agent and addition of oxygen to carbon dioxide, were studied. It was concluded that leaching of strontium sulfide is mainly dependent on the solubility of strontium hydroxide; however, SrS decomposes easily in hot water to give the hydrosulfide and the hydroxide. As a carbonating agent, Na 2 CO 3 provides higher precipitation rates and higher strontium recovery but low SrCO 3 grade, whereas precipitation with CO 2 gives a high purity of product which is sufficient for most of the uses of SrCO 3 . It was also found that oxygen, when used together with carbon dioxide in the carbonation column, increases the strontium recovery and decreases the carbonation time.

Some Aspects of Magnetic Filtration Theory for Removal of Fine Particles from Aqueous Suspensions

The magnetic filtration theory was evaluated to intensify the filtration of industrial fluids by magnetic filters. Effects of filtration velocity and external magnetic field intensity on filter performance were investigated and the dependence of the logarithmic efficiency coefficient on filtration velocity was questioned. It was concluded that change in the magnetic susceptibility of the dispersion particles, caused by external magnetic field, and change in the flow rate properties of the liquid alongside the filter pores are the most essential factors to be considered in the design, development, and modeling of magnetic filtration systems in various industrial areas.

Leaching of Celestite with Sodium Sulfide

Leaching of celestite mineral, SrSO4, with sodium sulfide, Na2S, was investigated from the point of strontium carbonate, SrCO3, production. Experiments were carried out to explain the conversion mechanism of celestite to strontium disulfide, SrS2, in Na2S solution. Effects of stirring speed, particle size, and concentration of Na2S on conversion were studied at constant temperature and solid‐to‐liquid ratio. The results showed that the rate of conversion mainly depends on Na2S concentration. It was concluded that leaching of celestite in Na2S solution for conversion to SrS2 is possible but slow.

An Overview of Surface Analysis Techniques for Characterization of Mechanically Activated Minerals

Surface characteristics of particles; such as structure, morphology, and chemical composition of surface have a major effect on its response to metallurgical processing operations. In order to understand the characteristics and reactivity of the system, information on the physical topography, the chemical composition, the chemical structure, the atomic structure, the electronic state, and a detailed description of bonding of molecules at the surface are required. Most of the instrumental techniques used for identification of major/minor and bulk/surface characteristics of substances now can be easily utilized as well for the characterization of mechanically activated minerals. This article is concerned with several representative identification techniques which are currently used for characterization of the materials prepared by mechanochemical processes. Fundamental aspects of spectroscopic (Infrared, Raman, and X-ray photoelectron), electron microscopic (Scanning electron microscopy and Transmission electron microscopy), and probe microscopic (Scanning tunneling microscopy and Atomic force microscopy) techniques used for surface characterization of mechanically activated minerals are overviewed.

Zeta Potential of Pyrophyllite in Aqueous Solutions of Alkaline and Alkaline Earth Metal Cations and Low‐Molecular‐Weight Organic Anions

Electrokinetic behavior of pyrophyllite in aqueous solutions of K+, Na+, Mg2+, and Ca2+ ions and effect of low‐molecular‐weight organic anions like acetate (C2H3O2 −), oxalate (C2O4 2−), and citrate (C6H5O7 3−) on the zeta potential was investigated. Pyrophyllite has higher negative zeta potential values in the presence of alkaline metal cations than in water, and it comes close to positive values in the presence of alkaline earth metal cations at low pH values. Results revealed that presence of low‐molecular‐weight organic anions led to a decrease in the zeta potential in the order of acetate>citrate>oxalate.

Kil Minerallerinden Alümina Üretimi: Güncel Değerlendirmeler

Gunumuzde ustun fiziksel ve teknolojik ozelliklerinden dolayi cok onemli bir malzeme olan alumina (Al 2 O 3 ) endustride yaygin bir sekilde kullanilmaktadir ve alumina uretiminin neredeyse tamami hammadde kaynagi olarak boksitin kullanildigi Bayer prosesi ile karsilanmaya devam etmektedir. Ancak yuksek uretim miktarlarina bagli olarak Bayer prosesine beslenecek uygun kalitedeki boksit rezervlerinin hizla azalmasi, alumina uretim maliyetlerindeki artislar, bazi ulkelerin boksit rezervlerinin sinirli olmasi ya da hic bulunmamasi gibi teknik ve ekonomik gerekcelerden dolayi boksit disi kaynaklardan alumina uretimi konusu hem bilimsel arastirma hem de endustriyel uygulamalar acisindan oldukca onem tasimaktadir. Dogada bol ve yaygin yaygin bir sekilde bulunmalari, nispeten yuksek aluminyum tenorune sahip olmalari, madencilik yontemleriyle uretimlerinin kolay ve ucuz olmasi, diger kaynaklara gore daha basit hazirlama ve zenginlestirme islemleri gerektirmeleri gibi nedenlerden dolayi kil mineralleri alumina uretimine en elverisli boksit disi kaynak olarak gorulmektedir. Killerden alumina uretimi amaciyla gelistirilmis ve genel kabul gormus bazi surecler bulunmaktadir. Bunlar arasinda ozellikle “Asit Lic Sureci” daha fazla on plana ciktigi, bazi usunluklerinden dolayi alumina uretiminde daha etkin bir yontem olarak uygulanabilecegi konusunda bir fikir birligi olustugu gorulmektedir. Bununla birlikte surec kosullari ve surec islem kademeleri uzerinde birtakim degisikliklere gidildigi, bazi modifikasyonlarin denendigi guncel calismalara rastlanilmaktadir. Killerden alumina uretimi konusunda yapilmis olan calismalarin ve guncel arastirma bulgularinin derlenmesiyle hazirlanan bu calismanin amaci, basta alumina endustrisi ve paydaslari olmak uzere ilgili arastirmacilara bilgi vermek, bu alanda yapilan bilimsel calismalara katki sunmaktir.

Natural Pyrophyllite and M(OR)x Based MxOy Powders as New Adsorbents for Heavy Metal Adsorption

Heat treated hydrolysis-condensation products of aluminiumtri-sec-butoxide (Al(OBu s )3) and alcohol modified Al(OBu s )3 were synthesised by sol-gel process. These synthetic powders, natural pyrophyllite and their 3-mercaptoprophyltrimethoxysilane coated forms were utilised as adsorbents for the removal of Cu(II) ions from aqueous solutions. The adsorption increased when natural and synthetic powders coated with SH-Si were used. It was concluded that the dried powders obtained from the hydrolysis-condensation product of Al(OBu s )3 and its alcohol modified form, and coated pyrophyllite would substitute for Amberlite IR 120 Na form resin. Introduction The disposal of heavy metals by wastewaters has been considered as one of the most important environmental problem [1]. There are numerous examples of reports on water pollution and the majority agrees to adsorb the heavy metals on adsorbents to cope with this problem [2]. Clays are low cost adsorbents for organic molecules but they can not be used to adsorb toxic heavy metals without modification. On the other hand, when the clay surface is modified with organo-functional silanes, the surface gains perfect properties to remove toxic organic and heavy metals, depending on the type of functional silane [3]. Metal oxides obtained from the metal alkoxides by sol-gel process, and their forms coated with organo-functional silanes are also novel adsorbents for adsorption of toxic contaminants from aqueous solutions. Erdemoğlu et al. and Sayılkan et al. [4,5] synthesized new adsorbents by the hydrolysis-condensation reaction of titanium-n-propoxide, zirkonium-npropoxide and titanium etoxide and they coated the synthetic ZrO2 and TiO2 powders with amino-, mercaptoand epoxy functional silanes to prepare adsorbents for removal of Cu 2+ , Pb 2+ , Fe 3+ , aniline and phenol from aqueous solutions. In this study, it was aimed to develop novel and efficient adsorbent powders by using sol-gel process techniques and to utilise these powders as adsorbents for the removal of Cu(II) ions from aqueous solutions. The results of adsorption experiments were compared with Amberlite IR 120 Na form commercial resin (IR120). Materials and Methods Materials Pyrophyllite is a hydrous aluminium silicate mineral with the chemical formula of Al2Si4O10(OH)2. The pyrophyllite sample consisting of 28% Al2O3, 66.2% SiO2 and 4.27% loss on ignition at 1000°C was obtained from Malatya-Pütürge region of Turkey. Al(OBu s )3 was used as precursor to prepare synthetic powders. 3-mercaptoprophyltrimethoxysilane was used as coupling agent. 2Butoxyethanol (2-BuOEtOH) was used as modifier for Al(OBu s )3. Methyl iso-butyl keton (MIBK) and methanol used as solvents were stored over molecular sieve (Fluka, 3ÅXL8) for a day before use. Analytical grade Cu(NO3)2 were used to prepare Cu(II) solutions. Key Engineering Materials Online: 2004-05-15 ISSN: 1662-9795, Vols. 264-268, pp 2239-2242 doi:10.4028/www.scientific.net/KEM.264-268.2239