PREPARATION OF HIGH PURITY MAGNESIUM OXIDE FROM SEA BITTERN RESIDUAL FROM NaCl PRODUCTION IN Al-BASRAH SALTERN, SOUTH IRAQ
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In this study, light and dead-burned magnesia (MgO) were prepared from the sea-bittern residual from the production of NaCl; extracted from sea water (Arabian Gulf) in Al-Basrah saltern in the south of Iraq. Dead burned magnesia of pure and dense form assaying 96.8% MgO, with a bulk density of 3.7 gm/cm was prepared at optimum conditions, including pretreatment of the sea bittern of 26 Baume with calcium chloride at a ratio of 1.05:1.00 (CaCl2:MgSO4) to remove calcium sulfate, addition of precipitant (dolime) at a molar ratio of 1:1 (CaO.MgO:MgCl2), and precipitation temperature of about 70 °C for 60 minutes. The precipitated Mg(OH)2 was subjected to calcination at 1000 °C for 60 minutes, whereby a milky soft powder of light-burned (active) magnesia was produced. Dead-burned (inactive) magnesia was then obtained by burning the light-burned magnesia at 1650 °C for 60 minutes. This study provides further benefit, of producing a high purity calcium sulfate (≥ 98%) as a byproduct of the MgO production. ريضحت ديسكوأ نع فلختملا رملا لولحملا نم ةواقنلا يلاع مويسينغملا جاتنإ حلملا ةرصبلا ةحلمم يف قارعلا بونج ، ىفطصم ليلخ دمحم ءلاع و الله دبع ديشر ديلو لختسملا ص ةسارد ثحبلا اذه يف مت إ ايسينغملا ةدام جاتن ةفيفخلا و ،قرحلا ةقلطم اب للاغتس رملا لولحملا فلختملا نع ةيلمع إ ماعطلا حلم جاتن جرختسملا رحبلا هايم نم ) )يبرعلا جيلخلا قارعلا بونج ،ةرصبلا ةحلمم يف ، ثيح أ ريضحت نكم ةدام أ نغملا ديسكو ي مويس و قرحلا ةقلطم لاع ( ةواقنلا ةي 96.8 % MgO ةيلتك ةفاثكبو ) 7 3. مس/مغ 3 ، تيبثت دعب فورظلا ةيلمعل ىلثملا ريضحتلا ةلماعم :تنمضت يتلاو ل ةيلوأ ةفاثك( رملا لولحمل 26 ب )هيموب ةدام ةبسنبو مويسلاكلا ديرولك 1.00 : 1.05 ( 4 MgSO : 2 CaCl ) ةلحرملل رملا لولحملا ةئيهتلو مويسلاكلا تاتيربك نم صلختلل ا .ةيلاتل ةلحرملا تنمضت ةيناثلا إ ةفاض ةبسرملا ةداملا ةبسنبو رملا لولحملا ىلا )ميلاودلا( ةيلوم 1 : 1 ( 2 CaO.MgO:MgCl بيسرتل ) ياه د مويسينغملا ديسكور ، متو ةرارح ةجردب لعافتلا 70 ةيوئم ةجرد .ةلماك ةعاس ةدمل مت ياه قرح د مويسينغملا ديسكور بيسرتلا ةيلمع نم جتانلا ةجردب ةرارح 1000 ةيوئم ةجرد ةدام ىلع لوصحلل ةعاس ةدمل أ ئطاو مويسينغملا ديسكو وأ طشنلا( قرحلا ةرارح ةجردب قرحلل ةريخلأا عاضخإبو )لاعفلا 1650 ،ةيوئم ةجرد ايسينغملا ةدام ىلع لوصحلا مت )ةلاعفلا ريغ( قرحلا ةيلاع . ةيقنلا مويسلاكلا تاتيربك جاتنإ ةيناكمإ ثحبلا رفوي امك ( ≥ 98 جاتنلإ يضرع جتنمك )% .مويسينغملا ديسكوأ _____________________________________________________________________________ 1 Assistant Chief Chemist, Iraq Geological Survey, P.O. Box 986, Baghdad, Iraq INTRODUCTION Preparation of High Purity Magnesium Oxide from Sea Bittern Residual from Nacl Production in Al-Basrah Saltern Alaa M. Kh. Mustafa and Waleed R. Abdullah 130 Iraq is one of the prosperous countries in the field of industrial ores and minerals. In spite of this fact, there is a lack in some important ore minerals for certain industries. One of these ores is Magnesite (MgCO3), which is considered the primary source for magnesia (MgO) production. Magnesia (MgO) is one of the several materials that are vital for refractories industry; it is classified under the so called "basic refractories" that are stable to alkaline slugs, dust and fumes at elevated temperatures. These refractories are of considerable importance for furnaces lining, where the environment is alkaline (Bathia, 2011). These characteristics; together with its ubiquitousness, and moderate coast, makes magnesium oxide the right choice for heat intensive metallurgical processes, such as the production of metals, cements, and glasses (Landy, 2004). Magnesium oxide, however, can be synthesized from some natural sources. The first source is magnesite. Other sources come from sea water, inland brines, salt lakes, which contain soluble magnesium chloride (MgCl2). Production of synthetic magnesium oxide from sea-bitterns has been practiced worldwide for decades, with some plants operating continuously since 1930. The largest sea water magnesia production plants are found in Japan, Great Britain, United States, and Ireland (Landy, 2004). Bittern is the dense residual liquor with specific gravity ≥ 1.28 obtained after precipitation and harvesting of NaCl salt from the sea water. The sea water bittern usually contain some sodium chloride, magnesium sulfate, potassium chloride and magnesium chloride, with small amounts of bromine, boron as well as some other trace metals that are occasionally present (Aral et al., 2004). The objective of this study is the production of pure magnesium oxide compatible to the Iraqi Standards for refractory magnesia brick no. 1977 of the year 1995 (Table 1) by utilizing the residual bittern resulted from the production of NaCl from seawater in Al-Basrah Saltern. Table 1: Characteristics of magnesia brick (Iraqi Standard no.1977, 1995) Grade Characteristic Grade 1 (Burned) Grade 2 (Unburned) Class-1 Class-2 Class-3 Class-1 Class-2 Class-3 MgO Wt.% (Min.) 85 92 95 85 89 93 Apparent porosity % (Max.) 26 23 20 – – – Bulk specific gravity (Min.) 2.70 2.75 2.80 2.75 2.80 2.80 Compressive strength (MPa) (Min.) 29.4 34.3 39.2 39.4 39.4 39.4 Resistance to heat under load (°C) (Min.) 145
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