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1

Sonochemical-assisted magnesium borate synthesis from different boron sources

Yildirim M., Kipcak A. S., Derun E. M.

Polish Journal of Chemical Technology

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2017

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Vol. 19, nr 1

81--88

EN

In this study, sonochemical-assisted magnesium borate synthesis is studied from different boron sources. Various reaction parameters are successfully applied by a simple and green method. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and Raman spectroscopies are used to characterize the synthesized magnesium borates on the other hand surface morphologies are investigated by using scanning electron microscope (SEM). The XRD analyses showed that the products were admontite [MgO(B2O3)3 · 7(H2O)] with JCPDS (Joint Committee on Powder Diffraction Standards) no. of 01-076-0540 and mcallisterite [Mg2(B6O7(OH)6)2 · 9(H2O)] with JCPDS no. of 01-070-1902. The results that found in the spectroscopic studies were in a good agreement with characteristic magnesium borate bands in both regions of infra-red and visible. According to SEM results, obtained borates were in micro and sub-micro scales. By the use of ultrasonication, reaction yields were found between 84.2 and 97.9%. As a result, it is concluded that the sonochemical approach is a practicable synthesis method to get high efficiency and high crystallinity in the synthesis magnesium borate compounds.

2

Preparation of synthetic carnallite and amorphous silica from chromite beneficiation plant tailings

Top S., Yildirim M.

Gospodarka Surowcami Mineralnymi

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2017

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T. 33, z. 2

5--23

EN

In this paper, synthetic carnallite (MgCl2 ∙ KCl ∙ 6H2O) and amorphous silica (SiO2) preparation possibilities were investigated by utilizing chromite beneficiation plant tailings which contain 3.44% chromite (Cr2O3) and 30.55% magnesium oxide (MgO) by weight. Firstly, laboratory scale high intensity wet magnetic separator was applied for removing the magnetic materials such as chromite, iron (II ) and manganese (II ) minerals in the tailings. About 85.75% of chromite, 91.22% of MnO and 64.71% of Fe2O3 were removed by single stage magnetic separation. After the magnetic separation, hydrometallurgical recovery was initiated by leaching of the tailings with hydrochloric acid (HCl). Amorphous silica particles and the other solids were separated from the leach solution by filtration. Impurities were precipitated from the leach solution by elevating the solution pH via magnesiumhydroxide (Mg(OH )2) adding. The purified magnesium chloride (MgCl2) solution was mixed with potassium hydroxide (KOH ) at stoichiometric ratio. According to the XRD and chemical analysis, the synthetic carnallite was synthesized by controlled heating of this solution at 90–100°C. Also, the amorphous silica with 96.5% SiO2 content and 84.38% recovery yield was obtained by additional magnetic separation treatment.

PL

W artykule przedstawiono badania możliwości wytwarzania karnalitu (MgCl2 • KCl• 6H2O) i bezpostaciowej krzemionki (SiO2) z odpadów z zakładów procesu wzbogacania chromitów, które zawierają 3,44% wag. chromitu (Cr2O3) i 30,55% wag. tlenku magnezu (MgO). W skali laboratoryjnej do usuwania materiałów magnetycznych, takich jak: chromit, żelazo (II) i minerały manganowe (II) zastosowano wzbogacanie mokre w separatorach magnetycznych o wysokiej intensywności. Około 85,75% chromitu, 91,22% MnO i 64,71% Fe2O3 usunięto metodą jednoetapowej separacji magnetycznej. Po wzbogacaniu magnetycznym odzysk hydrometalurgiczny został zainicjowany przez ługowanie odpadów kwasem chlorowodorowym (HCl). Amorficzne cząstki krzemionki i inne substancje stałe oddzielono od roztworu ługującego przez filtrację. Z roztworu ługowanego wytrąciły się zanieczyszczenia przez wzrost pH dzięki zawartemu wodorotlenkowi magnezu (Mg(OH)2). Oczyszczony roztwór chlorku magnezu (MgCl2) zmieszano z wodorotlenkiem potasu (KOH ) w stosunku stechiometrycznym. Zgodnie z XRD i analizą chemiczną, syntetyczny karnalit syntetyzowano przez kontrolowane ogrzewanie tego roztworu w temperaturze 90–100°C. Również odzysk 84,38% amorficznej krzemionki o zawartości 96,5% SiO2 uzyskano przez dodatkowe magnetyczne wzbogacanie.

3

Leaching of mersin/aydincik dolomite ore in hydrochloric acid. Dissolution rates

Altiner M., Yildirim M., Yilmaz T.

Physicochemical Problems of Mineral Processing

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2016

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Vol. 52, iss. 2

536--550

EN

In this paper dissolution of dolomite ore, collected from Mersin/Aydincik in Turkey, was investigated under various experimental conditions in the presence of HCl acid. Particle size, acid/dolomite ratio, solid/liquid ratio, stirring speed, reaction time and temperature were also conducted to the determin the optimum experimental conditions. During the experiment, CO2 amount released from the dolomite was measured through the experimental apparatus to determine reaction orders and rate constants of the sample at the different temperatures by using the fractional life approach method. It was found that, reaction orders and rate constants, based on temperatures, changed from 1.505 to 1.339 and between 3.17 and 10.49 10–2 mol dm–3 sec–1 respectively. In addition, differences in reaction rate constants were examined with the Arrhenius equation and activation energy of the dissolution process was calculated as 16.69 kJ mol–1, which was consistent with the activation energies determined in literature.

4

On some new sequence spaces and statistical convergence methods for double sequences

Belen C., Yildirim M.

Demonstratio Mathematica

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2014

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Vol. 47, nr 3

627--637

EN

In this paper, we introduce some new double sequence spaces with respect to an Orlicz function and define two new convergence methods related to the concepts of statistical convergence and lacunary statistical convergence for double sequences. We also present some inclusion theorems for our newly defined sequence spaces and statistical convergence methods.

5

Statistical approximation in multivariate modular function spaces

Belen C., Yildirim M.

Commentationes Mathematicae

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2011

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Vol. 51, [Z] 1

39-53

EN

In this paper, using the concept of A-statistical convergence we prove a Korovkin type approximation theorem in multivariate modular function spaces. Furthermore, giving an example via bivariate operators of Kantorovich type, it is shown that our theorem is stronger than its classical case.

6

Preparation of magnesium oxide (MgO) from dolomite by leach-precipitation-pyrohydrolysis process

Yildirim M., Akarsu H.

Physicochemical Problems of Mineral Processing

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2010

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Vol. 44

257-272

EN

Magnesium oxide suitable for the use in basic refractories was prepared from dolomite (CaMg(CO3)2) by hydrochloric acid leaching, precipitation with CO2 and thermal hydrolysis. Leaching of the dolomite ore in aqueous hydrochloric acid solution was investigated with respect to the effects of time on dissolution of the dolomite sample. The dependence of the observed dissolution rate on pH was established. In the carbonation experiments changes in pH, Ca2+ and Mg2+ concentrations versus time in the effluent solution were determined. Effects of the temperature on the precipitation rate of Ca2+ ions as solid CaCO3 were studied. Experiments were conducted to determine the kinetics of thermal decomposition of MgCl2.6H2O during pyrohydrolysis process. From high purity magnesium chloride brine magnesium oxide containing 98.86 % MgO was obtained with the thermal decomposition recovery of 98.10 %.

PL

Z dolomitu otrzymano tlenek magnezu przydatny do produkcji zasadowych materiałów ognioodpornych. Otrzymano go za pomocą ługowania kwasem solnym i wytrącania z użyciem CO2 oraz stosując termiczną hydrolizę. Badano ługowanie dolomitu w roztworze kwasu solnego w odniesieniu do czasu rozpuszczania. Ustalono zależności szybkości rozpuszczania od pH. Określono zmiany pH oraz stężeń Ca2+ i Mg2+ od czasu w roztworze podczas karbonatyzacji. Badano wpływ temperatury na szybkość precypitacji jonów Ca2+ w postaci stałego CaCO3. Przeprowadzono eksperymenty dla określenia kinetyki termicznego rozkładu MgCl2ź6H2O podczas pirolizy. Otrzymano wysokiej czystości tlenek magnezu o zawartości 98.86% MgO z solanki zawierającej chlorek magnezu, przy sprawności termicznej dekompozycji wynoszącej 98.10%.

7

Leaching and cementation of the sulphating roasted low grade ergani copper ore.

Yildirim M.

Physicochemical Problems of Mineral Processing

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2000

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Vol. 34

133-140

EN

Leach-cementation operations were applied to produce impure copper from the sulphating roasted ore. Effect of acid concentration and temperature on the extraction of copper from the ore into the leaching solution were studied. The cementation tests were conducted with two different stirring devices. On, mild steel disc and the second a propeller. The mild steel disc was used to provide a uniformly accessible suface for the kinetic study of cementation of copper with iron in sulphate solution.

PL

Zastosowano ługowanie i cementacje do otrzymywania miedzi po prażeniu siarczanizującym rudy. Badano wpływ stężenia kwasu i temperatury na proces ekstrakcji. Cementację przeprowadzono w dwóch różnych urządzeniach mieszających tj. stalowym mieszadłem dyskowym oraz śmigłowym. Zastosowane mieszadło dyskowe zapewniło jednorodną powierzchnię do badania kinetyki cementcji Cu za pomocą Fe w roztworach siarczanowych.