Eskişehir Alpu Bölgesi altere manyezit (magnezyumlu kil) kaynağından magnezyum türevlerinin elde edilmesi
Obtaining magnesium derivatives from altere magnesite (magnesium clay) source in Eskişehir Alpu Region
Yazar: ÇİĞDEM ARAS
Danışman: PROF. DR. BİRSEN ÖZTÜRK
İstanbul Teknik Üniversitesi / Lisansüstü Eğitim Enstitüsü / Kimya Ana Bilim Dalı / Kimya Bilim Dalı
Derece: Doktora, 2022
Konu: Kimya = Chemistry

Özet:
Magnezyum, en bol bulunan altıncı elementtir ve yer kabuğunun toplam kütlesinin %2'sini oluşturur. Sadece kimyasal bileşiklerde bulunan ve genellikle karbonat ve oksit formlarında bulunan bir metaldir. En önemli mineral formları manyezit (MgCO3), dolomit (MgCO3.CaCO3) ve karnalittir (KCl.MgCl2∙6H2O). Farklı kaynaklardan çeşitli yöntemlerle elde edilen magnezyum metali endüstride önemli bir yere sahiptir. Türkiye'de yaklaşık 16 milyar ton dolomit ve 110 milyon ton manyezit rezervi bulunmaktadır. Bu çalışmanın amacı, Eskişehir'de atıl olarak bulunan  magnezyum kil hammaddesinin çeşitli magnezyum bileşikleri üretimi için kullanımını araştırmak ve böylece sanayiye ilgili hammadde için kimyasal bir proses önermektir. 

Magnezyum, alüminyum ve demirden sonra yaygın olarak kullanılan üçüncü yapısal metaldir. Günümüz teknolojisinde hem metal hem de bileşik olarak önemli bir yere sahiptir. Magnezyum metali, bolluğu, hafifliği ve alaşımlanması kolay olması nedeniyle otomotiv, havacılık ve askeri endüstrilerdeki bileşenler için büyük bir potansiyele sahiptir. Magnezyumun önemli mekanik özelliklerinden dolayı daha popüler olması beklenirken, elde edilmesindeki zorluklar nedeniyle geri planda kaldığı görülmektedir. Magnezyum üretimi için altı hammadde kaynağı vardır: manyezit, dolomit, bischofit, karnalit, serpantin ve deniz suyu. Bu kaynaklar magnezyum içeriği, üretim yöntemleri ve kökenleri bakımından farklılık gösterir. Bunlar arasında en yaygın olarak kullanılan Mg metal cevherleri dolomit ve manyezittir. Manyezit, dolomitten daha fazla Mg içeriğine sahiptir, ancak büyük manyezit yatakları coğrafi olarak sınırlıdır. Manyezit minerali teorik olarak %52.3 CO2 ve %47.7 MgO içerir ve magnezyum ve bileşiklerinin üretimi için birincil kaynaktır. Öte yandan, bu mineral, herhangi bir önemli tortuda doğrudan kullanılabilecek kadar saf halde neredeyse hiçbir zaman oluşmaz. Cevherleri, çoğunlukla diğer karbonatlar, silikatlar ve oksitler olmak üzere çeşitli gang mineralleri içerir. Dünya manyezit kaynaklarının 12 milyar tonun üzerinde olduğu tahmin edilmektedir ve esas olarak Çin, Rusya, Kuzey Kore, Avustralya, Slovakya, Brezilya, Türkiye, Hindistan ve Kanada'da bulunmaktadır. Önemli miktarda dolomit ve manyezit rezervi olmasına rağmen, Türkiye'de 2016 yılından önce magnezyum metali üretilmiyordu. Manyezit genellikle doğal hali yerine kalsine edilerek MgO'ya dönüştürülerek kullanılmaktadır. Manyezitin kalsinasyonu ve elde edilen ürünün reaktivite derecesi teknolojik açıdan önemlidir. Metalik magnezyum üretiminde kullanılacak manyezitin de kalsine edilerek saflaştırılması gerekir. Böylece malzeme magnezyum açısından zenginleştirilmiş olur. Manyezit, kalsinasyon işlemi sırasında CO2 ve H2O kaybettiği için gözenekli bir yapıya sahiptir ve kalsine manyezitin özgül ağırlığı 1,3 ile 1,9 g/cm3 arasındadır. Dünyadaki manyezit ve manyezit ürünleri kimyasal içerik, CaO/SiO2 oranı, kütle yoğunluğu, kristal yapısı açısından değerlendirilmekte ve fiyatlandırılmaktadır. Kalsine bazda %93,5'ten fazla MgO içeren cevherler değerli hammaddeler olarak kabul edilir.

Bu tez çalışmasında, Esan Eczacıbaşı Endüstriyel Hammaddeler San. Tic. A.Ş. Firması'nın Eskişehir ili Alpu ilçesi Ağapınar Köyü'nde atıl vaziyette bulunan magnezyumlu kil hammaddesinin magnezyum bileşikleri üretiminde kullanılmasının araştırılarak, ilgili hammaddenin sanayiye kazandırılması amaçlanmıştır. Temel amaç, bu bölgeden elde edilen magnezyumlu kil hammaddesinin, başta kalsinasyon olmak üzere farklı kimyasal yöntemler kullanılarak magnezyum kaynağı olarak kullanılıp kullanılamayacağının araştırılmasıdır.

Abstract:
Magnesium is the sixth most abundant element, constituting 2% of the total mass of the earth's crust. It is a metal that exists only in chemical compounds, and generally exits in carbonate and oxide forms. The most important mineral forms are magnesite (MgCO3), dolomite (MgCO3.CaCO3) and carnallite (KCl.MgCl2∙6H2O). Magnesium metal, which is obtained from different sources by various methods, has an important place in the industry. There are approximately 16 billion tons of dolomite and 110 million tons of magnesite reserves in Turkey. The aim of this study is to investigate the use of idle magnesium clay raw material (in Eskişehir) for the production of various magnesium compunds and thus to propose a chemical process for the relevant raw material to the industry.
Magnesium is the third commonly used structural metal after aluminum and iron. It has an important place in today's technology both as a metal and as a compound. Magnesium metal has great potential for components in the automotive, aerospace and military industries due to its abundance, light weight and easy alloying. While magnesium is expected to be more popular due to its important mechanical properties, it seems to be in the background due to the difficulties in obtaining it. There are six raw material sources for magnesium production: magnesite, dolomite, bischophyte, carnallite, serpentine, and seawater. These sources differ in their magnesium content, production methods, and origins. Among them, the most widely used Mg metal ores are dolomite and magnesite. Magnesite has a higher Mg content than dolomite, but large magnesite deposits are geographically limited. Magnesite mineral theoretically contains 52.3% CO2 and 47.7% MgO and is the primary source for the production of magnesium and its compounds. On the other hand, this mineral almost never occurs pure enough to be used directly in any significant deposit. Its ores contain various gangue minerals, mostly other carbonates, silicates, and oxides. World magnesite resources are estimated at over 12 billion tons and are mainly found in China, Russia, North Korea, Australia, Slovakia, Brazil, Turkey, India and Canada. Although there are significant reserves of dolomite and magnesite, magnesium metal was not produced in Turkey before 2016. Magnesite is generally used instead of its natural state by calcining and converting to MgO. The calcination of magnesite and the degree of reactivity of the obtained product are technologically important. Magnesite to be used in the production of metallic magnesium must also be calcined and purified. Thus, the material is enriched in magnesium. Magnesite has a porous structure as it loses CO2 and H2O during the calcination process and the specific gravity of calcined magnesite is between 1.3 and 1.9 g/cm3. Magnesite and magnesite products in the world are evaluated and priced in terms of chemical content, CaO/SiO2 ratio, bulk density and crystal structure. Ores containing more than 93.5% MgO on a calcined basis are considered valuable raw materials.
In this thesis, Esan Eczacıbaşı Industrial Raw Materials San. Trade Inc. The aim of this study was to investigate the use of magnesium clay raw material, which is inactive in Ağapınar Village of Alpu district of Eskişehir province, in the production of magnesium compounds, and to bring the relevant raw material to the industry. The main purpose is to investigate whether the magnesium clay raw material obtained from this region can be used as a magnesium source by using different chemical methods, especially calcination.
After determining the thesis topic, a literature study was conducted by reviewing the studies carried out so far on the thesis topic. In the same process, approximately 10 kg of samples were taken from the magnesite quarry of Esan Eczacıbaşı in Bozüyük for the supply of the sample to be used in the thesis study. First of all, identification processes of this sample were carried out. According to the information obtained from previous literature studies, the reaction rate increases as the particle size decreases. Based on this information, the entire 10 kg sample was ground to 75 micron size. Chemical analysis, XRD, DTA and particle size analyzes of the grinded sample were performed.
In the following stage, the raw material was subjected to various calcination processes. The identification processes of the products obtained as a result of these processes were carried out. Chemical analysis, XRD, DTA and grain size analyzes of the products obtained as a result of calcination were performed.
After the calcination processes, experiments to obtain magnesium chloride from raw magnesite and calcined magnesite and their identification studies were carried out. Then, studies were carried out to obtain Mg0 metal based on the MgCl2 compound. Subsequently, studies were carried out to obtain MgF2 to obtain different Mg compounds.
As a result of the studies carried out, the following findings were reached;
According to the results of the chemical analysis, there is 44.28% MgO in the raw material. According to the XRD analysis results, when the material was examined structurally, it was determined that the main structure was magnesite with MgCO3 structure, as well as some dolomite (MgCO3.CaCO3) and chlorite group minerals. The results obtained by DTA support the presence of chlorite and dolomite in the XRD analysis. In addition, the 45% reduction in thermal gravity coincides with the 44.9% value obtained as a result of the glow loss.
The raw material was calcined at different temperatures and times. Chemical analysis, XRD analysis and DTA analysis were applied to the calcined samples obtained at the end of different temperatures and times. The loss on ignition analysis gives us information about whether there is a volatile compound in the material. When the chemical analysis results were examined, it was determined that the calcination process performed at 900 °C for 3 hours (LOI: 0.90%) was not sufficient for the completion of the calcination. It was determined that the presence of volatile compounds (CO2 from MgCO3) still continued in the material and the calcination process was not completed. However, when the calcination study performed at 1000 °C for 3 hours and the others were examined, it was seen that there was no high difference between the chemical analyzes. In this case, 1000 °C temperature and 3 hours are considered to be suitable as the optimum calcination parameter. After the XRD analysis of these products, it was determined that the carbonate structures in the body were removed by the calcination process and various magnesium oxide derivatives were formed. It is observed that different phase formations begin to occur in samples where calcination conditions exceed 1000 °C and 3 hours. Phase formation causes the structure to become more stable and the chemical processes to be applied become more difficult. Therefore, phase formation is not desired in the structure. This again supported the optimum calcination condition of 1000 °C and 3 hours, which was determined as a result of chemical analysis. In parallel with chemical analysis and XRD analysis, DTA graphics of the sample calcined for 3 hours at 900 °C also shows that carbonate and other volatile structures are not left in the body and it becomes more stable in the products after 3 hours at 1000 °C. However, as determined in the XRD results, a phase formation around 1000 °C began to be observed in the DTA graphs of the samples after the sample calcined at 1100 °C for 3 hours. The % TG values seen in the graphs support the % glow loss values. From all these data, it was concluded that the optimum calcination condition for the raw material used is 1000 °C temperature and 3 hours.
When the studies on the production of magnesium chloride from raw magnesite are examined; the biscophyte (MgCl2.6H2O) peak observed in the XRD analysis of the materials obtained after the applied experiment showed that MgCl2 formation took place. When the XRD results were examined, it was determined that the entire structure formed was biscophyte. Although studies were carried out at different temperatures, the compound formed in all experiments is biscophyte.
Similarly, when the studies on the production of magnesium chloride from calcined magnesite by the reaction of  MgCl2, were examined, it was observed that the bischofite (MgCl2.6H2O) peak was seen in the XRD analysis of the products, so MgCl2 formation took place. Although the expected structure was MgCl2.2H2O, it was observed that the product formed did not lose its water and remained as bischofite. In this case, when the XRD results were examined, it was determined that biscofite, a magnesium compound, was obtained from calcined magnesite. However, sufficient data could not be obtained for the efficiency calculation.
In a different study, it is aimed to obtain Mg metal from the reaction of magnesium chloride with NH2OH.HCl (k). When the experiments were examined, metallic Mg formation was observed as a result of some reactions, in which the reagent concentration and the test temperature were increased. However, since the amount of Mg obtained is very low, an identification study could not be carried out on the material.
Later in the thesis, in an experiment set, it was aimed to obtain magnesium fluoride from raw magnesite by using hydrofluoric acid and NH4F solutions. According to the results of XRD analysis on the samples obtained, it was determined that 100% MgF2 (Sellaite) formation occurred using only concentrated HF. As a result of the experiments carried out with NH4F, it was determined that a high rate of MgF2 (Sellaite) formation did not occur, however, due to NH4F, there were impurities consisting of high levels of nitrogenous compounds in the structure.
After determining that MgF2 can be obtained from raw magnesite with HF with the previous set of experiments, raw magnesite and also calcined magnesite were reacted with HF to examine different parameters. Apart from the differentiation of the input material, another parameter was added in the experiment set by applying two different methods (drying and filtration) for the process of obtaining the material after the experiment. In the experiments in which raw magnesite was used as the input material, the presence of Sellaite (MgF2) was clearly detected in the XRD graphs. However, in experiments using calcined magnesite as the input material, it was determined that although the presence of Sellaite (MgF2) was observed, the pig intensities were low and the presence of unreacted Periclase (MgO) was also high. In XRD analysis, the purer the material, the higher the peak intensity of the mineral and the higher the peak sharpness. In this context, when the XRD analyzes of the products obtained as a result of the experiments were examined, two conclusions were reached;
1. The yields of the experiments using MgCO3 as the input material are higher than the experiments using MgO as the input material.
2. When the peak intensities obtained are examined, the intensity of the products obtained by the "Drying" method is higher than the intensity of the products obtained by the "Straining" method, when the input material is kept constant. In this case, the efficiency of the "Drying" method is higher than the efficiency of the "Straining" method.