Molibden konsantrelerinin değerlendirilmesi
Evaluation of molybdenum concentrates
- Tez No: 439630
- Danışmanlar: PROF. DR. ONURALP YÜCEL
- Tez Türü: Yüksek Lisans
- Konular: Metalurji Mühendisliği, Metallurgical Engineering
- Anahtar Kelimeler: Hidrometalurji, Pirometalurji, Üretim metalurjisi, Hydrometallurgy, Pyrometallurgy, Production metallurgy
- Yıl: 2016
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Metalurji ve Malzeme Mühendisliği Ana Bilim Dalı
- Bilim Dalı: Üretim Metalurjisi ve Teknolojileri Mühendisliği Bilim Dalı
- Sayfa Sayısı: Belirtilmemiş.
Özet
Bu tez çalışmasının amacı, yerli molibdenit (MoS2) konsantresinden hareketle, çeşitli molibden ürünleri üretiminde başlangıç malzemesi olabilecek kalitede molibden trioksit üretilmesidir. Çalışma konusu kapsamında, total oksitleyici kavurma yöntemiyle molibdenit konsantresinden molibden trioksit (MoO3) eldesi ve saflaştırma işlemleri yapılmıştır. Saflaştırma işlemi mevcut bakırı uzaklaştırmak için hidrometalurjik yöntemle gerçekleştirilmiştir. Ayrıca, WindowsTM tabanlı termokimyasal bir bilgisayar programı olan FactSage ile termodinamik hesaplamalar yapılmış ve ürünlerin karakterizasyon çalışmaları tamamlanmıştır. Deneysel çalışmalarda Özdoğu İnş. ve Tic. Ltd. Şti.. iştiraki Kuzey Ege Bakır İşletmeleri tarafından gönderilen MoS2 konsantresi kullanılmıştır. Özdoğu İnş. ve Tic. Ltd. Şti., ağ.% 0,40 Cu ve ağ.% 0,05 Mo içeriğine sahip tüvenan cevheri flotasyon ile zenginleştirerek ağ.% 27 Cu ve ağ.% 52 Mo içeriğine sahip iki ayrı konsantre elde etmektedir. Deneysel çalışmaların birinci aşamasında MoS2 konsantresine total oksitleyici kavurma deneyleri uygulanmıştır. Deneyler kamaralı tip fırında yapılmış olup, farklı sıcaklıklarda ve sürelerde kavurma işlemi uygulanarak, kavurma sıcaklığı ve süresinin, MoS2'nin MoO3'e dönüşüm hızı ve bileşimine etkisi incelenmiştir. Deneyler sonucunda farklı kalitelerde MoO3 ürünleri elde edilmiştir. Deney sonuçları incelenerek teknik kalite MoO3 standartlarına en uygun MoO3 üretimini sağlayan sıcaklık ve süre parametreleri saptanmıştır. Artan sıcaklık ve sürenin, ürünlerdeki kükürt miktarına azaltıcı bir etki yaptığı gözlemlenmiştir. Başlangıçta ağ.% 39,19 kükürt içeriğine sahip MoS2 konsantersinin kavrulması sonucunda elde edilen MoO3 ürünlerinin kükürt içeriği % 1,05'e kadar düşürülmüştür. Deneysel çalışmaların ikinci kısmını oluşturan hidrometalurjik saflaştırma deneylerinde, teknik kalite MoO3 standartlarına en uygun ürünleri veren kavurma parametreleriyle üretilen MoO3 numuneleri liç işlemine tabi tutulmuştur. Sülfürik asit çözeltisi ile yapılan liç deneylerinde, çözelti konsantresi ve katı-sıvı oranının, metal kazanımına etkisi incelenmiştir. Deneyler sonucunda MoO3 ürünlerinin bakır içeriği ağ.% 0,13'e kadar düşürülmüştür. Molaritenin artması ve katı sıvı oranının azalması metal kazanım verimini arttırmıştır. Karakterizasyon çalışmaları kapsamında elde edilen ürünlere kimyasal analiz, XRD ve AAS teknikleri uygulanmıştır.
Özet (Çeviri)
The aim of this study is processing of local molybdenum concentrate to produce quality molybdenum trioxide may be the starting material for the production of various molybdenum products. Generally molybdenum metal is produced from its high grade sulphide ore through oxidizing roasting of molybdenite (MoS2) in order to obtain molybdenum trioxide (MoO3), purification of molybdenum trioxide and hydrogen reduction of molybdenum trioxide. Molybdenum concentrates which contain about 90 wt.% MoS2, along with up to 10 wt.% silicious material as well as traces of iron, copper and lead minerals, are the main mineral of the molybdenum industry for the production of technical grade molybdenum trioxide, which is further used to produce molybdenum, ferromolybdenum alloys, molybdenum dioxide and other pure molybdenum compounds such as ammonium dimolybdate, sodium and calcium molybdate. The usual practice is to roast the concentrates with sufficiently low copper and lead levels to produce a calcine that is essentially MoO3 containing low sulphur. Such calcines can be used directly in steelmaking, because liquid iron will reduce MoO3 to metal in high yield. Molybdenum is widely used for the production of ferromolybdenum, which is required for the production of alloyed steel. Almost 80 % of molybdenum, produced from molybdenum trioxide, is used for steel making in industries. Technical-grade MoO3 is produced by roasting molybdenite in air atmosphere in a multiple-hearth furnace. The roasted MoO3 product usually has <0.1% sulfur content. The multiple-hearth furnace is used because the hearths can be segmented to accomplish specific and different conversion operations within a single unit. In the upper hearths of the furnace, flotation oils are burnt off and water is evaporated. This part of the process is usually augmented by burning fossil fuels to ensure consistent temperature control and uniform roasting throughout the remainder of the unit. Upper hearth temperatures are between 600 and 700 ºC. The majority of the sulfur is removed by oxidation in the intermediate hearths. Since the sulfur oxidation reactions are highly exothermic, additional heating is not needed in this part. The hearth temperatures are controlled between 600 and 650 ºC by the addition of excess air and water spray cooling. As sulfur burning is about to completed, the composition of the roaster hearth is mostly MoO2 with <20 wt.% MoO3 and MoS2 contents. The reaction of MoO3 with MoS2 which forms MoO2, is driven by the strong oxidizing power of MoO3, so that the production of MoO3 is limited until most of the MoS2 is gone. Once the availability of MoS2 is less than the availability of MoO3, MoO2 is quickly converted to MoO3. Despite this reaction is exothermic, it is not sufficient to maintain the temperatures above 525 ºC which are required to complete sulfur removal and conversion to MoO3. So that additional heating is required in these lower hearths. The oxide product is discharged from the roaster, cooled, and milled to form technical grade MoO3. Technical-grade MoO3 typically contains 85–90 wt.% MoO3, the balance being silica with some Fe2O3 and Al2O3. In some cases, additional hydrometallurgical processing is needed to produce technical-grade MoO3. In steel making, using molybdenum trioxide with high copper content has some harmful effects on the mechanical properties of the alloyed steel produced. Therefore, the up-gradation of molybdenum trioxide is required in steel industry. The up-graded molybdenum trioxide must have less than 0.5 wt.% Cu content for ferromolybdenum production. Before the experiments, some thermodynamic simulations were made to determine the optimum parameters for roasting and hydrometallurgical purification, with a WindowsTM based thermochemical simulation program named FactSage. FactSage allows us to make some complex process system simulations. And according to databases of the program (Fact, FS, SGTE etc.), it is possible to simulate a large number of compounds, alloys, molten systems and aqueous solution systems. In FactSage, chemical reactions, pressure-temperature diagrams, Eh-pH diagrams of the desired systems can be simulated. Also the phase diagram calculations of oxides and alloys can be done and the results can be given as tables or graphics. FactSage is a beneficial program in the areas of metallurgy and materials engineering, chemical engineering, organic chemistry and environmental engineering. In this study, molybdenum trioxide was obtained from local molibdenite concentrate with the total oxidizing roasting method, the main impurity metal copper was leached out from the obtained molybdenum trioxide with hydrometallurgical purification process, thermodynamic calculations were made by a WindowsTM based thermochemical simulation program named FactSage and characterization of the products were completed. The raw material which was used in total oxidizing roasting experiments, is local molybdenite concentrate sent by Özdoğu İnş. Tic. Ltd. Şti. According to Özdoğu İnş. Tic. plant production chief, the ore which has 0.40 wt.% Cu and 0.05 wt.% Mo content, is subjected to a flotation process in order to obtain enriched two different concentrates which have 27 wt.% Cu and 52 wt.% Mo contents. The chemical analysis of the molybdenite concentrate matches with the company's analysis results with 52 wt.% Mo content. In this study, it was aimed to determine the optimum parameters for the total oxidizing roasting process of molybdenite concentrate to produce MoO3 and purify the MoO3 product by removing the copper content. Present study was conducted in two main stages: First, MoS2 was roasted by controlling parameters such as reaction temperature and duration in a chamber type furnace. Before the roasting experiments, 20 grams of 18 samples were prepared and put in a stove in order to dry the samples. To make a homogeneous roasting, alumina boats which have large surface area, were used. The samples were put in the alumina boats as thin layers. Before the experiments, samples were weighted with the alumina boats in order to calculate the weight losses. Samples were roasted at 600 ºC, 625 ºC, 650 ºC with 15, 30, 45, 60, 90 and 120 minutes. The six samples which are in the same temperature set, were put in the furnace. After starting the roasting process, samples were taken individually from the furnace after respectively 15, 30, 45, 60, 90 and 120 minutes. Then the samples were put in the desiccators for cooling. The highest Mo concentration rate was obtained as 56.6 wt.% of MoO3 at 650 °C for the roasting duration of 45 minutes. In the second experimental sets, roasted product was leached by H2SO4 to remove copper. Leaching conditions were optimized by investigating the effects of different H2SO4 concentrations and S/L ratio. Leaching experiments were done with Merck quality 95-98 % H2SO4 with the duration of 15 minutes, at room temperature and 400 rpm mixing rate. All the samples were 10 grams. During the leaching, acidic solution and powder samples were mixed with a magnetic mixer. Leaching temperature was controlled by a contact thermometer. After leaching, solid-liquid separation was done by a blue banded filter. The solids were dried in a stove at 105 ºC for 12 hours. In order to investigate the effects of different H2SO4 concentrations and S/L ratios , 10 grams of samples were leached with 0.2 M, 0.4 M, 0.6 M acid concentrations with 1/5, 1/2 and 1/1 solid-liquid ratios. 97.7 wt.% of copper was removed by using 0.6 M H2SO4 at 0.2 solid/liquid ratio. The raw materials and the products were characterized by using AAS (atomic absorption spectrometry) and XRD (X-Ray Diffraction) techniques.
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SELÇUK KAN
Yüksek Lisans
Türkçe
2017
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