Dynamic Behavior of continuous flow stirred slurry reactors in boric acid production

Yücel Çakal, Gaye Ö
One of the most important boron minerals, colemanite is reacted with sulfuric acid to produce boric acid. During this reaction, gypsum (calcium sulfate dihydrate) is formed as a byproduct. In this study, the boric acid production was handled both in a batch and four continuously stirred slurry reactors (4-CFSSR̕s) in series system. In this reaction system there are at least three phases, one liquid and two solid phases (colemanite and gypsum). In a batch reactor all the phases have the same operating time (residence time), whereas in a continuous reactor all the phases may have different residence time distributions. The residence time of both the reactant and the product solids are very important because they affect the dissolution conversion of colemanite and the growth of gypsum crystals. The main aim of this study was to investigate the dynamic behavior of continuous flow stirred slurry reactors. By obtaining the residence time distribution of the solid and liquid components, the non-idealities in the reactors can be found. The experiments performed in the continuous flow stirred slurry reactors showed that the reactors to be used during the boric acid production experiments approached an ideal CSTR in the range of the stirring rate (500-750 rpm) studied. The steady state performance of the continuous flow stirred slurry reactors (CFSSR̕s) in series was also studied. During the studies, two colemanites having the same origin but different compositions and particle sizes were used. The boric acid production reaction consists of two simultaneous reactions, dissolution of colemanite and crystallization of gypsum. The dissolution of colemanite and the gypsum formation was followed from the boric acid and calcium ion concentrations, respectively. The effect of initial CaO/ SO42- molar ratio (1.00, 1.37 and 2.17) on the boric acid and calcium ion concentrations were


Dissolution of colemanite and crystallization of gypsum during boric acid production in a batch reactor
Erdoğdu, Anıl; Eroğlu, İnci; Department of Chemical Engineering (2004)
One of the most commonly used boron compounds, boric acid, is produced by dissolving colemanite (2CaO₉3B2O3₉5H2O) in aqueous sulfuric acid whereby gypsum (CaSO4₉2H2O) is formed as a byproduct and must be separated from the main product. This process consists of two steps, dissolution of colemanite and formation of gypsum. The amount of boric acid formed depends on the first step, dissolution of colemanite. In the latter step, gypsum crystals are formed and stay in the reaction mixture to grow up to a size l...
Inferential control of boric acid production system
Dervişoğlu, Özgecan; Özgen, Canan; Department of Chemical Engineering (2007)
Inferential control of boric acid production system using the reaction of colemanite with sulfuric acid in four continuously stirred tank reactors (CSTR) connected in series is aimed. In this control scheme, pH of the product is measured on-line instead of boric acid concentration for control purposes. An empirical correlation between pH and boric acid concentration is developed using the collected data in a batch reacting system in laboratory-scale and this correlation is utilized in the control system for...
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ÖZÜN, Savaş; Atalay, M. Umit; Demirci, Şahinde (Informa UK Limited, 2019-05-19)
The long-chain alkyl amines and petroleum sulfonates are mostly used to remove unwanted minerals from feldspar ores in acidic pHs. In this study, their adsorption characteristics on pure albite and quartz were investigated by electrokinetic potential measurements, microflotation tests, Fourier transform infrared spectroscopy, and atomic force microscopy studies. According to the results, amine had strong influence on zeta potentials of both albite and quartz turning them positive and resulting over 90% flot...
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Karaman, Mustafa; Özbelge, Önder; Department of Chemical Engineering (2007)
Boron carbide was produced on tungsten substrate in a dual impinging-jet CVD reactor from a gas mixture of BCl3, CH4, and H2. The experimental setup was designed to minimise the effect of mass transfer on reaction kinetics, which, together with the on-line analysis of the reactor effluent by FTIR, allowed a detailed kinetic investigation possible. The phase and morphology studies of the products were made by XPS, XRD,micro hardness and SEM methods. XPS analysis showed the existence of chemical states attrib...
Surfactant modified zinc borate synthesis and its effect on the properties of PET
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Zinc borate was prepared from the reaction of zinc oxide and boric acid in the absence or presence of cumene terminated poly(styrene-co-maleic anhydride), PSMA, added as a surfactant at varying concentrations (0.1-1 wt.% of water) to the reaction medium to investigate its effect on the growth and agglomeration of particles during reaction. Synthesized zinc borates were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) in comparison to unmodifie...
Citation Formats
G. Ö. Yücel Çakal, “Dynamic Behavior of continuous flow stirred slurry reactors in boric acid production,” Ph.D. - Doctoral Program, Middle East Technical University, 2004.