Yerli olivin cevherinden refrakter malzemeye uygun hammadde üretimi
Production of raw materials for refractory material from domestic ores
Yazar: ÖZGÜN KÜÇÜKOĞLU
Danışman: PROF. DR. ONURALP YÜCEL
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Metalurji ve Malzeme Mühendisliği Ana Bilim Dalı / Üretim Metalurjisi ve Teknolojileri Mühendisliği Bilim Dalı
Derece: Yüksek Lisans, 2016
Konu: Metalurji Mühendisliği = Metallurgical Engineering ; Seramik Mühendisliği = Ceramic Engineering
Dizin: Olivin = Olivine ; Refrakter = Refractory

Özet:
Olivin, yer kabuğunda en fazla bulunan minerallerden biridir. Yer kabuğunda bu kadar fazla bulunmasına rağmen, olivin cevheri içerisindeki demir miktarı nedeni ile refrakter üretiminde hammadde olarak kullanılması tercih edilmez. Önceki çalışmalarda, hammadde olarak MgO ilavesinin, olivinin içerisindeki demirin magnezyoferrit olarak elde edilebilineceği gösterilmiştir. Bu çalışmada ilk olarak, refrakter malzemelerin tanımı yapıldıktan sonra, refrakter malzemelerin genel özellikleri ve sınıflandırılması açıklanmıştır. Daha sonra da refrakter malzemelerin üretim aşamaları anlatılmıştır. Bir sonraki bölümde, olivin cevherinin tanımı yapıldıktan sonra, olivinin kullanım alanları anlatılmıştır. Bölümün sonunda ise olivinden üretilen refrakter malzemelerin özellikleri belirtilmiştir. Dördüncü bölümde olivin cevherinin refrakter malzeme olarak kullanımı için yapılan deneyler açıklanmış ve sonuçlar gösterilmiştir. Son bölümde ise yapılan deneysel çalışmaların sonuçları irdelenmiş ve öneriler sunulmuştur.

Abstract:
Olivine is one of the most abounded mineral of the world. In spite of its massive quantity, refractory materials from olive are rarely produced because of its iron content. Early studies show that, iron in olivine can be transformed to magnesioferrite by adding MgO. In this study, Egirdir/Isparta donuts were used as raw materials for refractory products. Formation of magnesioferrite phase was investigated according to percentage of MgO (%10-40) and sintering temperature (1300 0C – 1400 0C). Modules of rupture test was actualized with regard to ASTM C-133 Standard. XRD and AAS were used for chemical analysis. Refractory materilas are non-metalic materials which aresupposed to be resistant to heat, mechananical stress and strain and corrosion from solids, liquids and gases at furnace conditions. As an another description, refractory materials are shaped and unshaped materilas which are durable at high temperatures and corrosive environment. Refractories are divided into two categories which are, shaped (bricks and cast shapes) and unshaped (monolithic) refractories. There are two kinds of shaped refractories—the primary kind is like brick or similar shapes and the other kind is the shapes made from monolithic refractories, where they are dictated by the properties of the monolithic refractories. For shaped refractories (like brick making), attaining maximum density after the shapes are formed is the goal of the processes. Because of the superior thermal stability of refractories, they are use in kilns, furnaces, boilers, incinerators and other applications in iron and steel, non-ferrius metals, cement, glass, ceramics and chemichal industries which hight temperatures are used for processes. Because of many applications are qite varius, there are different kind of refractory materials are avaible for use. It is obvious that the property requirements of refractories vary significantly according to the application and use in different processes. Hence, individual refractories need to be designed with characteristic properties for specific systems since the requirements vary with different high-temperature processes.
Forsterite refractories are one of the refractory material which finds place in refractory industry for several application. Forsterite refractories are magnesium-slicate products, in which MgO and SiO2 are main ingredients. The main raw materials are magnesium-slicate ores, that contain htdated or unhydrated mineral phases. Most abundant phase of unhydrated mineral of magnesium-slicate is olivine which is a solid solution af magnesium-slicate and iron-slicate. hydrated phese of olivine minerals called serpantine. Both minerals can be used as raw material for forsterite refractory production. If serpantine is used as raw material, it is necessary to do pre-calcination for remove crystallization water.
Production of forsterite refractory materials are similar to production of traditional refractory production procces. According to that, first of all, raw materials are crushed and grinden to reduce particular size. After that grinded particules are classified according their particle size. Grinded raw materials are calsineted to remove water or corbondioxide if necessary. After that, grinded materials are mixed with additeves and binders homogeniously. Then, mixture is presses under high pressure to give refractory form to materials. Formed materials are fired at sintering tempereture to produce dense product. After sinering proceces, refractory materils became ready to use for refractory application.
Refractories with olivine or serpantine as main raw materials lack of refractirinnes, corrosion resistance and high temperature strenght. In general MgO is added to strengthen the matrix. The bricks are formed under high pressure, and than sintered. These refractories have been used in the roof of furnaces for cupper and lead refining, in thr working lining of low frequency induction furnaces for melting non-ferrius metals, and rotary kilns for sintering cement and dolomite. There are two major difficuluties of forsterite refractory production from olivine raw materials. One of them is iron content of raw matarials. Iron is found as fayalite phase which is iron-slicate in olivine minerals. Fayalite has relatively low melting temperature which effects negatively to properties of refractory product. The main aim of this study is decomposing fayalite phase and converting the fayalite to magnesiferrite phase which has higher melting temperature. The second difficulity of forsterite refractory production occurs duruing firing procces. Enstatite phase which is also magnesium-slicate phase as forsterite can be occured. Although enstatite is magnesium-slicate mineral like forsterite, it has low melting temperature which is undesirable property. The secondary aim of this study is prevening the formation of enstatite phase during firing procces.
After introduction part of this study, refractory materials were described in the second chapter. After definition of refractory materials, history of refractory materials and usage of refractory materials in Turkey was explained. Then, properties of refractory materials were described as physical, thermal and chemical properties. There are various refractory products in the market. Because of the fact that, selection of correct refractory product for high temperature processes is becoming important. For this reason, classification of refractory products was described for selection of refractories. The classification of refractories was discribed as usage temperature, production method, chemical composition and chemical properties. At the end of the second chapter, manufacturing of refractory materials were described. In the third chapter, olivine ores were investigated as raw materials for refractory products. Firstly, olivine was introduced as mining, extraction and usage area. After that, studies of forsterite refractories which are produced from olivine raw material, were investigated at the end of the third chapter. Experimental studies were explained in the fourth chapter of this study. Firstly, purpose of the study was explained. Then the procedure of experiments which are, preparation of raw materials, calcination, preparation of mixtures, pressing and drying and sintering process were described. At the end of the study, results and discussions were explained according to 3 point bending tests, x-ray diffraction analysis, porosity and cold crushing strenght of refractory products.