Eskişehir - Beylikahır toryum cevherinin değerlendirilmesi

Abstract

Ill ÖZET Türkiye de Eskişehir - Beylikahır bölgesinde bulunan ve dün yadaki 'büyük rezervli -toryum yataklarından t)iri olarak kabul edilen bu cevher yatağının toryum bakımından değerlendirilmesine ışık tutmak ama cıyla bu çalışma yapılmıştır. Cevher yatağının ortalama toryum tenörü $ 0.2 olup düşük te- nörlü bir cevher olarak tanımlanmakta ise de bu cevher yatağı rezervi nin büyüklüğü, içerisinde bulunan Kadir Toprak Elementleri, Barit ve îluo- rit bakımından da ayrı bir önem taşımaktadır. Yatağın özellikleri göz önünde bulundurularak MTA Enstitüsü tarafından açılan yarmalardan % 0.6Ş Toryum tenörlü yaklaşık 1000 kg lık temsili bir numune alınmış ve de neysel çalışmalar bu numune üzerinde yürütülmüştür. Bu araştırmada öncelikle cevheri tanamak için mineralojik in celeme, ağır ortam ayırması manyetik ayırma ve ağır ortam + manyetik a- yırma* deneyleri yapılmış olup cevher hakkında gerekli bilgiler elde e- dildikten sonra bu bilgilerin ışığı altında cevheri zenginleştirme ça lışmaları yapılmıştır. Ayrıca bu çalışmalara sürat kazandırması açısın dan toryum için pratik ve güvenilir bir analiz yöntemi geliştirilmiştir. ün zenginleştirme çalışmalarında cevherin ve cevher içerisin de saptanan minerallerin özellikleri göz önünde bulundurularak sırasıyla boyut küçültme, sarsıntılı masa ile zenginleştirme, flotasyon ile zen ginleştirme, karıştırarak ve aktararak dağıtma ve boyuta göre sınıflan-IV dırma ile zenginleştirme deneyleri yapılmıştır. Toryum mineralinin cevher içerisinde çok ince tanecikler halin de dağılmış olması ve kil mineralleri ile Dirlikte kolaylıkla ince tane ye geçebilmesi dolayisıylaf dağıtma ve boyuta göre sınıflandırma deney leri sonunda iyi netice alınmış ve c/o 1.2 Toryum tenörlü, bir ön konsant re % 73.1 verimle elde edilmiştir. Bu ön konsantre sülfürik asit, nitrik asit, ve hidroklorik asit ile ayrı ayrı çözündürme işlemine tabi tutulmuş olup, çözündürme süresi, asit miktarı, sıcaklık ve pülp yoğunluğunun toryum çözünme verimine etki leri incelenmiştir. Her üç asitle de, gerekli miktar ve süre tesbit edi lerek $ 99 *. yakıa bir toryum çöfcünme verimi elde edilmiştir. Çözündürme işlemlerinde karşılaşılan en enteresan olay; ön konsantre içinde bulunan fluoritin çözünmesiyl^ açığa çıkan fluorür iyoan çözelti içindeki toryum iyonuyla birleşerek Toryum Tetra Florür( ThF ) halinde toryumu çökeltmektedir. Böylece toryum çözünme verimi f» 30 ci varına düşmektedir. Bu olay çözündürme süresini ayarlamakla bertaraf e- dilmiştir. Ayrıca orijinal toryum cevher numunesi de aynı asitlerle ve ay nı koşullarda çözündürme işlemine tabi tutulmuş olup, elde edilen sonuç lar, ön konsantreden elde edilen sonuçlarla karşılaştırılmıştır. Bu çalışma sonunda: - fo 1.2 Tb. tenörlü, $ 73.1 verimle bir ön konsantre elde edilmiştir. - Çözündürme işlemleri sırasında toryumun çökelme nedenleri saptanmış ve süre ayarlamasıyla giderilerek fo 99 luk bir toryum çözünme verimi sağ lanmıştır. - Toryum ön konsantresini çözündürme işlemlerinde kullanılan asit mik tarında, orijinal cevhere göre $> 30-40 oranında bir avantaj elde edil miştir.

SUMMARY Energy, has been one of the most important problems of thiB century in the world and in Turkey. As the energy demand in creases oonoerns for the exhaustion of fossil fuels, oil crisis, high fuel prices has proved that nuclear energy is the most attractive to conventional energy forms. In Turkey, all the research and prelimi nary studies in nuolear energy field has been accelerated since 1965 and has been directed towards the evaluation of our own uranium and thorium resources. This study is concerned with the evaluation of Eskişehir - Beylikahır Thorium deposit which is known as one of the world's lar gest thorium deposits» The experiments have been carried out by using a represen tative sample of 1000 Kg. of thorium ore with O.65 $ thorium content from Eskişehir - Beylikahır thorium deposit for ore dressing and leaching process. In this thorium deposit two. kinds of rocks were found. One was fissure vein group and the other one was teohtonio breccia which contains gang minerals and thorium. At the same time there were also four kinds of mineralized substance of Ilanf^inase oxides, Barite, Fluorite and Carbonates in that particular deposit.VI The thorium ore sample on which experiments are carried out was absolutely soil looking', very -brittle and did break up easily. Barite, Fluorite, Dolomite, Goethite, Limonite, Quartz, Kontmorillonr Orthoolase and Fyrolusite were found in the ore by mineralogio determ nation. The identification of thorium mineral in the ore wasn't posi- ble by using a microscope. However, certain results obtained by x-ray diffraction method were thought to indioate the existanoe of Bastne- asite mineral. Sink - Float seperation, magnetic separation and oontbinatio of these two techniques were applied on the ore sample in order to get more information about the structural characteristics of that particular ore. It has been observed that the thorium content has been increased in the heavy mineral concentrate and magnetic products obtained by these methods. Even a high value of 2.2 % Th has been obtained in a product. However, the recovery of thorium was about 24 and this value was too low to be optimistic. According to the results obtained for ore invest igation and the structural characteristics of the ore, it was necessary to search for the possible ways to have concentrates with higher thoriurr contents for the sample before the leaching1 process. For this purpose crushing and grinding, gravimetric seperation, flotation, scrubbing and tumbling experiments have been performed. The thorium oontents of the size fractions obtained by a series of screen analysis of the original raw ore sample and the sample crushed to -6 mm. and -1 mm. were determined. Closed circuit process was applied during the crushing experiments. It was found that the thorium content increased in a fine fraction of the ore. The concentration of thorium was too low when all experimental results were taken into consideration.VII By making use of the difference 'between the specific gravi ties of different minerals in the ore, the preconoentration process has been carried out on shaking tatile. Samples in three different parti cle size were prepared for the concentrating table experiments. Eesults obtained at the end of these experiments showed that it wasn't possi ble to collect any significant amount of thorium concentrate in a produot. The ore sample was ground and screened step by step to reach minus 0.15i mm. particle size for flotation experiment to float the barite and fluorite. Since there were too much slime in the ore, it had to he removed completely from the ore before flotation technique was used. The brittleness and easily grindable of the ore and the exi- stanoe of clay minerals had adverse effect on the flotation. Thus, it wasn't possible to collect thorium mineral in a particular produot by flotation. Utilizing the data ohtained hy the experiments used to identify the ore and the properties of ore structure.it was thought that the ore should be scrubbed and tumbled in a certain particle size in order to get better thorium concentrates. The scrubbing experiments have been performed for samples with three different particle size 6mm. 4mm. and 2mm. The re tention times were 10, 20 and 30 minutes respectively. At the end of these experiments, the product whioh has 79 f° Th-recovery, 1 f, Th-grade and minus 0.053 nun. particle size was obtained under the conditions of 6mm. particle size, 30 min. retention time and 60 % solid in pulp. The result show that thorium recovery was increasing as the particle size increased. Ftfom this point of view, the tumbling experiment has been done on the raw ore sample since it will be more economical' and give higher Th-recovery. Thus the obta ined Th-preconcentrate has 1.2 % Th-grade with the particle size -0.105 n``* and the Th-reoovery of 73*1 İ>. In this tumbling experiment pulp density was 65 f) solid. The analysis for the preconcentrate of the thoriumVIII ore showed that it had a poorer concentration of silica and rioher concentration of barite, fluorite and montmorillonite than the ori ginal ore. Acid leaohing was conducted on the original thorium ore and on the thorium preoonoentrate for thorium extraction. The aim of this pro cess was to prove and then to oompare thorium extraction recovery for both samples under same conditions and to find out that whether the preoonoentrate of thorium obtained via physical enrichment process has any use. Leach tests have been done with three different acids namely sulphuric acid, nitric acid and hydrochloric aoid. The effects of acid concentration and retention time on thorium extraction efficiency were examined for eaoh acids* In addition, the effects of temperature va riations and the effects of solid's ratio in pulp on extraction's ef ficiency was investigated. The samples, each one being 300 gr., were used in leach ing experiments. Because of the particle size was minus 0.105 mm. in preoonoentrate of thorium to establish the same conditions, the ori ginal thorium ore sample was ground to the particle size of minus 0.105 mm. Conditions of experiments: The particle size of sample : - 0.105 ram. Acids : H2SO4, HNO3 and HC1 The amount of aoid used : 100 - 800 Kg / tone Pulp density : 50 f° solid Time : 0 - 4 hours Temperature : Room temperature As a result of leach experiments performed with three diffe-IX rent acids under the conditions mentioned above, thorium extraction was obtained with a 99 1° recovery. However the amount of acid used for pre concent rat e of thorium was 30 - 35 % less than the amount of acid used for original thorium ore. It was observed ? that the recovery of thorium extraction for the original thorium ore has been increasing as the amount of acid and the retention time increased. This was valid for three kinds of acids used. However some difficulties have arised in the leaching expe riments performed with sulphuric acid sinoe very fine oaloium sulphate preoipitated very easily and it made mixing and filtering prooesses rather difficult. The experiment of the preconoentrate of thorium extraction had showed that the recovery of thorium extraction has been increasing as the amount of aoid and the retention time increases. But during the experiments performed with sulphuric aoid and nitric aoid, the recovery of thorium extraction has reached to its maximum value within half an hour. After half an hour, thorium was beginning to precipitate and thori-um extraction decreased to a minimum value at the end of the first hour. It was possible to say that the fluoride ion oaused to precipitate of thorium from the extracted thorium. After beginning to dissolve calcium fluorite ( 0a?2 ) whioh was much higher in the thorium preconoentrate, the fluoride ions were taken into the solution immediately and they formed a compound with thorium ions. Thus, thorium tetra fluoride( TW* ) preoipitated in the solution. Since thorium tetra fluoride is highly insoluble compound, it didn't dissolve during the leach experiment even though the retention time was increased. The precipitation event did not ocour in the process; of ori ginal thorium ore leaching as there were large amount of free SİO2 inthe original ore. The amount of free Si02 thorium preoonoentrate was very low. The fluorite ions which has started to' dissolve from the fluorite reacted with free SİO2 and forme silica gel. The reactions were as follows 2 CaP2 + Ei02 -t- 2 H2SO4*> SiF^ + 2 CaS04. 2 H20 3 SİF4 + 4 H201- SİO2. 2 H20 + 2 H2SiFg All the fluoride ions spend hy Si02 as there were large amount of si lica in solution and there were no more fluoride ions in media to pre cipitate thorium. Thus the preoipitation of thorium was impossible af ter spending all fluoride ions hy Si02 in solution. There wasn't any precipitation of thorium when leaching of thorium preoonoentrate with hydrochloric acid was performed. By using 200 Kg. hydrochloric acid per tone, thorium extraction with 99 % tho rium recovery was obtained within three hours. It could he said that the most effective acid was hydrochloric acid to dissolve the thorium from the preconcentrate as well as the original öre. During this project, a radiometric analysis method has also heen developed for thorium determination. This method is more prac tical for the analysis of thorium from solid sample and the accuracy of the method has heen justified by four different techniques.