Eskişehir-beylikahır Kompleks Cevheri Lantanit Grubu Elementlerin Toryum Ve Uranyumdan Metalurjik Proseslerle Ekstraksiyonu

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Tarih
2015-03-09
Yazarlar
Berke, Mahmut Sefa
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Özet
Eskişehir-Beylikahır bölgesinde konumlanmış, fluorit-barit-bastnazit minerallerinden oluşan kompleks cevherin içeridiği lantanit grubu elementlerin, metalurjik üretim prosesleri kullanılarak, üretimi araştırılmıştır. Cevher içerisinde lantanit grubu elementlere eşlik eden toryum ve uranyumun lantanit grubundan üretim sırasında ekstraksiyonu, çalışmanın ana konusunu oluşturmuştur. Eskişehir-Beylikahır kompleks cevherinin nadir toprak elementi oksitleri içeriği; toplam cevher rezervinin %3,14’ünü teşkil etmektedir ve bu değer, 953 milyon tona tekabül etmektedir. Nadir toprak elementi rezerv büyüklüğü bakımından; Eskişehir-Beylikahır maden yatağı, dünya sıralamasında Çin, ABD, Avustralya ve Hindistan’dan sonra beşinci sırada gelmektedir. Bölge kompleks cevherinde nadir toprak elementleri bastnazit mineralleri yapısında bulunmaktadır. Diğer yandan cevher yapısında toryum ve uranyum elementi de mevcuttur. Cevherde bulunan diğer ana mineraller barit ve fluorittir. Cevher içerisindeki barit ve fluorit oranları sırasıyla %31,04 ve %37,44 dir.  Endüstriyel üretimde, nadir toprak elementi içeren kompleks cevherler fiziksel cevher zenginleştirme prosesleriyle konsantre edilirler. Konsantrelerin üretimi, kimyasal kompozisyonlarına ve cevher orijinlerine göre; çözümlendirme ve ardından solvent ekstraksiyon prosesleriyle üretilirler. Solvent ekstraksiyon uygulaması sonucunda nadir toprak elementleri, saf oksit veya karışık saf oksit formlarında ekstrakte edilirler. Kullanım alanlarında ihtiyaç duyulan, yüksek kimyasal safiyet değerleri için, lantanit grubu metal oksitlerin üretiminde rafinasyon kademesi olan solvent ekstraksiyon prosesi büyük önem taşımaktadır. Toryum içeren nadir toprak elementi cevherlerinin işlenmesinde toryumun yüksek safiyette üretilebilmesi amacıyla solvent ekstraksiyon proses adımları çok sayıda tekrarlanır. Diğer yandan toryum içermeyen cevherlerde fiziksel zenginleştirmenin ardından gerçekleşen solvent ekstraksiyon daha az tekrar sayılarıyla gerçekleştirilmekte, dolayısıyla üretim; hızlı ve düşük maliyetli şekilde sonuçlanmaktadır. Çalışma kapsamında, Eskişehir-Beylikahır kompleks cevheri için üretim prosesi tasarlanmıştır.  Tasarlanan proses; cevher hazırlama işlemleriyle boyutlandırılan ham cevherin, herhangi bir zenginleştirme sistematiği uygulanmadan proses hammadde girdisi olarak sırasıyla;  asidik termo-kimyasal ayrıştırma, kalsinasyon ve su liçi proses adımlarından oluşmaktadır. Sonuç ürün hedefi olan, lantanit grubu elementlerin; cevherden kazanım verimleri ve üretim sürecinde toryum ve uranyum elementlerinin ana akımdan seperasyonlarının, mümkün olup olmadığı araştırılmıştır. Gerçekleştirilen deneysel çalışmalar sonucunda; Eskişehir-Beylikahır kopmleks cevheri için tasarlanan üretim prosesinde Th ve U elementlerinin lantanit grubu elementlerden ayrıştırılma veriminin %75 mertebelerinde olduğu, lantanit gurubu elementlerin cevher üzerinden kazanım veriminin ise %80 ve üzerinde başarı ile sağlandığı görülmüştür.
"Rare earth elements" nomenclature refers to scandium and yttrium together with lanthanide group elements (lanthanides), which are chemically similar metallic elements. Lanthanides are elements with atomic numbers from 57 to 71. Rare earth elements are defined by IUPAC (The International Union of Pure and Applied Chemistry) in 1968. Due to the similarity in the chemical properties of thorium is generally considered as rare earth element.  Chemically similar to each other rare earth elements are always found together in minerals. In addition, rare earths shows characterized in that a single chemical structure. This similarity is caused to characterization studies on rare earth elements proceed for 160 years. On the other hand, chemically similarity of rare earths caused to different technical and financial problems on industrial production. The lanthanide elements are subdivided into two main group; cerium group and yttrium group. The cerium (or light) group includes La, Ce, Pr, Nd, Pm, Sm and Eu elements. The yttrium (or heavy) group includes Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and Y elements.  The lanthanide group metals are generally silvery-white, but some of them are pale yellow. They have faced centered cubic or close-packed hexagonal crystal lattice, with exception of Sm and Eu.  Rare earths are characterized by high density, high melting point, high thermal conductance and high electrical conductivity. Depending on the evolving technology rare earth elements and their compounds can be produced with high purity. Due to the high purity, the rare earth elements usage increase on the advanced technology application. Examples thereof include; coloring, illumination, electromagnetic radiation, laser, catalytic, ceramic, electronics and magnet technologies can be listed. The natural resources of lanthanide group elements are relatively large. Lanthanide’s total content in the Earth's crust is 0.0015%, for example same as the content of copper. Presently, more than 250 lanthanide containing minerals are known. Of these 60-65 are lanthanide minerals, in example; minerals in which the total concentration of the lanthanide elements is higher than 5%. These minerals consist of silicates, phosphates, fluorides or fluorocarbonates etc. Some of the important rare earth elements containing minerals are; Bastnasite, Monazite, Xenotime, Euxenite, Apatite, Gadolinite, Loparite, Uranitite, Brannerite, Doverite and Allanite. The most commercially important rare earths minerals are Bastnasite, Monazite and Xenotime.  The world’s largest deposit of rare earth elements is found at Bayan Obo in China where monazite and bastnasite concomitance as associated minerals in iron ore. The main minerals are iron, rare earths, niobium and fluorite. Bayan Obo contains 36 million tons of rare earth oxide. Second largest deposit of rare earths is found at Mountain Pass in USA. The main mineral is bastnasite in the Mountain Pass and the mineral content is 3.6 million tons of rare earth oxide.  Commercial mining of rare earth elemants reserves began about a hundred years ago. Monazite was the main rare earths source from the beginning of the industry until 1965. Everafter bastnasite production equaled or exceeded monazite production. At present, bastnasite is the world’s major source of rare earth and constitutes 62% of world output of rare earth minerals. Industrial production began from the Mountain Pass deposit in the 1950s and this has remained the only source of bastnasite for over decades. Production of rare earths began in China in the 1980s. In China, bastnasite is produced as a by-product of iron ore mining in Bayan Obo. The major amount of monazite is obtained as by-product from the extraction of rutile, ilmenite or zircon in Australia, Brazil, India. The rare earth elements ore deposit in Turkey is located Eskisehir-Sivrihisar-Kızılcaoren. This location is called Beylikahır. Beylikahır mining geology studies were made by MTA. Production of complex ore located in Eskisehir-Beylikahır; has the formation of minerals, fluorite-barite-bastnaesite and contain the lanthanide group elements, has been investigated using metallurgical production processes. Seperation of thorium and uranium, accompanying the lanthanide group elements, during production of the lanthanide group of extract is the main subject of the study. Rare earth oxide content of the Eskişehir-Beylikahır complex ore; represents 3.14% of the total ore reserves, and this value corresponds to 953 million tons. In terms of the size of reserves of rare earth elements; Eskişehir-Beylikahır mineral deposits takes the fifth place in the world ranking list in which China is the leader, US, Australia and India are in order. Rare earth elements are located in complex ore as bastnaesite mineral structure. On the other hand, thorium and uranium elements are available in the complex ore structure. Other main minerals in the ore are; barite and fluorite rated as 31.04% and 37.44%, respectively. Industrial production of complex ores containing rare earth elements, are concentrated by physical ore beneficiation process. The production of concentrates, differs according to their chemical composition and mineral origin; leaching and solvent extraction processes are the main steps. Rare earth elements are extracted by solvent extraction process as; single metal oxides or mixed oxides form, as a result of the application area needs. Solvent extraction step has a big importane in production of high chemical purity products because it is the refining stage of the lanthanide group metal production. Processing of rare earths ore containing thorium, solvent extraction process steps are repeated in huge numbers in order to produce high purity thorium. On the other hand, ores without thorium content, solvent extraction is carried out with less number of repetitions, so production; results as quickly and inexpensively. In this study, production process for the Eskişehir-Beylikahır complex ore is designed. Designed process; mineral processing process of resized raw ore, raw materials of any enrichment as an input to the process of implementing systematic respectively; acidic thermo-chemical decomposition, calcination and water leaching process steps. The lanthanide group elements as final product; recovery efficiency of elements from ore and correspondence of thorium and uranium separation from lanthanides investigated.  Results of experimental studies performed indicate that; the manufacturing process is designed for Eskişehir-Beylikahır complex ores; degradation efficency of Th and U  elements from lanthanum group  is 75% and the recovery efficiency of the lanthanide group elements through ore has been successfully over 80%.
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015
Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2015
Anahtar kelimeler
Lantanitler, Nadir Toprak Elementleri, Bastnazit, Lanthanides, Rare Earth Elements, Bastaesite
Alıntı