ÖZET Etibank tarafından 1975 yılında işletmeye alınan Eskişehir-Kırka Tinkal Zenginleştirme Tesisi Kırka civarındaki ocaklardan üretilen % 26-27 B2O3 içerikli tinkal cevherinden % 34.5 B2O3 içerikli tinkal konsantresi üretmek üzere tasarlanmıştır. Ancak bu tesis, gerek verim gerekse üretilen konsantre niteliği bakımından istenilen değerlere ulaşamamıştır. Bor tuzu tesisine en az % 34.5 B2O3 içerikli konsantre yerine, % 32 B2O3 içerikli konsantre beslenmesi nedeniyle, artan suda çözünmeyen katı miktarı, proseste önemli problemler ortaya çıkarmış ve verimi tüvenan cevhere göre % 68-72 düzeyine indirmiştir. Bu araştırmada, cevher yatağının büyük bir bölümünü oluşturan Bantlı ve Breşik Tinkal cevherlerinin doğrudan çözündürülmesi ile zenginleştirildikten sonra çözündürülmesi koşullarının araştırılması ve sonuçların teknolojik, ekonomik yönden karşılaştırılması amaçlanmıştır. Bu araştırma dünyada ilk kez yapılmaktadır. Bantlı ve Breşik tinkal cevherleri içinde bulunan ve gerek zenginleştirme gerekse de bor tuzu üretiminde sorun yaratan suda çözünmeyen katıların özelliklerini tesbit etmek amacıyla; Kimyasal, EDS Kalitatif, DTA, X-Işınlan Difraksiyonu ve Boyut Analizleri yapılmıştır. Yapılan araştırmalar sonucunda, bantlı cevherdeki suda çözünmeyen katıların % 90'ının birkaç mikron boyutlu dolomit ve kalsit, breşik cevherdeki katıların ise % 90 oranında küçük boyutlu dolomitten oluştuğu, montmorillonit cinsi kil miktarının ise % 10 civarında olduğu saptanmıştır. Bor tuzu üretim işlemlerinde max. B2O3 kazanma verimi ile yüksek B2O3 konsantrasyonu! çözelti elde etmek için her iki tür cevherle ayrı ayrı çözündürme + filtrasyon ve çözündürme + flokülasyon + dekantasyon deneyleri yapılmış, sonuçta çözündürme + filtrasyon yönteminin daha uygun olduğu saptanmıştır. Ayrıca bor tuzu üretiminde kullanılacak olan cevherin optimum B2O3 içeriğinin tesbiti amacıyle % 24 ile % 35 arasında değişen B2O3 içerikli cevherlerle çözündürme + filtrasyon deneyleri yapılmış ve deneyler sonucunda % 35 B2O3 içerikli cevherin uygun olduğu tesbit edilmiştir. Çözündürme+filtrasyon deneylerinden elde edilen sonuçların ışığında, %35 B2O3 içerikli tinkal konsantresini üretmek için bantlı ve breşik cevherlerle fiziksel yöntemler kullanılarak zenginleştirme deneyleri yapılmış ve yüksek B2O3 içerikli konsantre üretim koşullan saptanmıştır. Bu tez kapsamında yapılan araştırmalar sonucunda mekanik karıştırma ve boyuta göre sınıflandırma yöntemleri kullanılarak % 35. B2O3 içerikli tinkal konsantresinin % 98 verimle kazanılabileceği ve bu konsantreden çözündürme + filtrasyon yöntemi ile tüvenan cevhere göre % 96 verimle boraks çözeltisinin üretilebileceği anlaşılmıştır. Aynca tinkal cevherinden, doğrudan veya ön zenginleştirme yapıldıktan sonra bor tuzu üretiminin, teknolojik ve ekonomik yönden karşılaştırılması yapılmış, zenginleştirme yapılarak B2O3 içeriği artırılmış cevherden, bor tuzu üretiminin yapılmasının daha uygun olacağı kanıtlanmıştır. SUMMARY RESEARCH ON THE NEW PROCESSING METHODS IN THE EVALUATION OF KIRKA TINCAL ORE In today's technolgy, natural borax compounds play a very large role. Altough, boron does not appear as pure element in the nature, boron minerals which are the oxidized boron compounds have been known and used since the ancient times. Borax is found as solution in salty lake waters or as a tincal mineral. In Asia and Far East, borax was used in welding of metals and in glazing potteries in the ancient times. In 13 th century, when Marco Polo brought borax crystals from Tibet to Europe so that a trade of boron compounds was started in Europe. In 1771, gassolite which is a form of boric acid was found in hot water springs in Tuscany-Italy, In 1 808, in the perrod where the discoveries took place extensively in the field of chemistry, two frenchmen GAY LUSSAC and LOUIS JACKQUES THENARD and an Englishman Sir HUMPHREY DAVY discovered the boron element by chance. Although boron occurs in a very small quantity (10 ppm) in the earth crust, some large deposits with high B2O3 content were found in some locations. Boron deposits in Turkey, USA and Argentine are concentrated in the lakes of draught areas dominated by the tertiary volcanism. The most common boron deposits on earth are layered evaporites which consist of sodium, calcium and magnesium borates. It is accepted by all investigators that deposits were formed as a result of evaporation of boron rich waters in lakes. The formation of evaporites follows the sequence of thermodynamic conditions. For example; carbonates which are the first precipitates are observed at the base and at the borders of precipitation area. While the evaporation carries on, since the lake area becomes smaller with the increasing salt concentration, sodium and potassium salts precipitating last are located in the middle. Searles Lake (USA) is an example of an evaporite system and has not completed its evolution yet. Its salty water which fills vacancies of the crystalized salts contains mostly boron. This proves that borax is the last crystalized salt, after the evaparation of salty lakes. VITurkey has the largest borax deposits forming 59 % of world reserves. Borax deposits in Turkey are located in Susurluk, Bigadiç, Mustafa Kemal Paşa, Emet and Kırka. `Pandermite` is the boron mineral in Susurluk deposit, on the other hand Bigadiç, Mustafa Kemal Paşa and Emet deposits contain `Colemanite` as the main boron mineral. Tincal mineral occurs only in Kırka deposit. Turkey and USA are the largest borax producers in the world, these two countries provide 93 % of the world borax production. 30-35 % of the world B2O3 production is consumed by USA, 40-50 % of world consumption by Western European countries and the rest by the others. While the consumptions of borax in USA and Japan, belong mostly to fiber glass and glass wool, whereas the largest use of borax in the West Europe is far the soap and detergent industries. In Turkey 590,000 tons of tincal concentrate, 307,000 tons of colemanite concentrate and 135,000 tons of Ulexite concentrate were produced in 1992. The production of Boron compounds in 1992 was; 13,100 tons of Borax Decahydrate, 23,200 tons of Boric Acid, 13,900 tons of Sodium Perborate, 160.900 tons of Borax Pentahydrate. Although Turkey has 59 % of the world borax reserves, the colemanite and tincal production from 1865 (the first mine was in operation) to 1979 were exported either directly (as mined) or after their B2O3 contents were increased by concentration. In 1979 after the state ownership started when licences of the private companies were transferred to Etibank. Then modern processing plants were established in Bigadiç, Emet, Mustafa Kemal Paşa, and Kırka Mines. In Bandırma, plants were founded to produce borax pentahydrate, borax decayhdrate, unhydrite borax and boric acid by processing enriched boron minerals. These borax compounds above mentioned are the intermediate products since they contain water in their structure. In Turkey nowadays, final boron products are not produced, both fiber glass and textile wools largely used in the USA and Japan. These products are produced by two private plants with very low capacities. Eskişehir-Kırka tincal processing plant was started to operate by Etibank in 1975. It was planned to produce tincal concentrates with 34.5 % B2O3 content. But, this plant could not reach the expected concentrate grade and recovery. 300,000 tons of concentrate with 32-33,5 % B2O3 content produced in this plant and used in the borax compound production plant located nearby. In this plant, borax pentahydrate is produced by the following procedures of dissolution + solid/liquid separation + crystallization + classification + drying. In 1984, when borax compound production plant started to treat tincal concentrate containing 32 % B2O3 with 12 % of undissolved solid in water instead of the concentrate containing 34.5 % B2O3 with 5.5 % of undissolved solid in water. Consequently the capacity of Vllfiltration unit for solid/liquid separation was not sufficent because of the increasing nondissolving material, so that the filtration unit was cancelled and a system containing two steps of flocculation + decantation process was introduced. Now the refining plant is working with 80 - 85 % efficiency and pentahydrate is produced from the tincal ore by this process with a low (68 - 72 %) efficiency. The aim and scope of this research were to investigate the leaching parameters of banded and breccia tincal (run -of- mine) ores forming the largest part of the deposits as well as tincal concentrate and then compare the results in both cases from the economical and technological view points. This research work was conducted first time in the world. Upon the research and exploration activities carried out in Kırka Mine, it has been determined that three different kind of ores exist, namely, the banded, breccia and glassy types. The banded ore exists at the upper part of the deposit, between clay and marl layers in a banded form with band thicknesses ranging from 1 to 10 centimeters. The breccia ore has been found at the lower levels of the deposit in particle sizes ranging from 1 to 10 centimeters. Small borax crystals and fîllfer materials made up of marn and clay are present in the breccia ores. The- glassy type of ore exists in small quantities in the deposit, while the banded and breccia ores form the large part of the deposit. The structural differences `observed during the macroscopic and microscopic examinations of the banded and breccia ores have shown that significant differences sould be necassary in the selection of the beneficiation and refining processes that are to be applied to these ores. Therefore, the seperate banded and breccia ore samples have been taken from the ore beds of 8 m. height by opening perpendicular channels with 20 meter intervals. Chemical, EDS Qualitative, Differential Thermic, X-Ray Difraction and Particle Size Analysis have been carried out in in order to determine the characteristics of the insoluble solids present in the banded and breccia tincal ores which cause some problems during both the beneficiation process and the borax compound production. As a result of the tests, it has been determined that 90 % of the insoluble solids present in the banded ore were dolomite or calcite of a couple of microns in size. While, 90 % of solids in the breccia ores is made of small sized dolomite. At the same time, the quantity of the montmorillonite type of clay was approximately 10 %. Since tincal is easily soluble and quite sensitive to temperature changes, thin sections couldn't be prepared satisfactorily. Therefore, mineralogical analyses of the banded and breccia tincal ores have been carried out by using the X-Ray Difractometer. In accordance with the mineralogical examinations, it has been found that; Vlll.Tincal, dolomite and montmorillonite existed in the banded ore..Tincal, uleksit, dolomite, calcite and montmorillonite existed in the breccia ore. Experiments have been executed in order to investigate the conditions of the solubility and solid/liquid separation of Kırka tincal ores. The existence of the 10 % clay in the insoluble solid fraction creates significant problems during the direct leaching, solid/liquid separation and B2O3 beneficiation process concerning the banded and breccia tincal ores. It will only be possible to beneficiate with a high B2O3 recovery, if the clay content present in the tincal ore can be kept to a minimum level. In other words, it will only be possible if the B2O3 content present in the tincal ore can be increased which will be subjected to the refining process. Starting from this point, it has been intended to obtain a high B2O3 recovery by leaching followed by solid/liquid seperation. Both literature and industrial applications indicate the use of flocculation + decantation or filtration for the solid/liquid separation which is carried out after the dissolution step. Several tests have been carried out in order to investigate the dissolution conditions of the Kırka tincal ore. In these tests, the effects of particle size, temperature, dissolution time, solid ratio of the pulp and agitation speed have been studied and the best results achieved are as follows; particle size -6 mm, dissolution temperature 98 °C, agitation speed 600 rev/min, solids content of 50 %. Dissolution + Filtration and Dissolution + Flocculation + Decantation tests have been carried out seperately in order to produce a solution containing high B2O3 with a maximum B2O3 recovery during the borax manufacturing processes. While obtaining a solution of 146 gr/lt. B2O3 with 75.43 % efficiency by application of Dissolution + Filtration methods to banded ores; a solution of 198 g/İt. B2O3 has been obtained with 91.69 % efficiency, with breccia ores. By Dissolution + Flocculation + Decantation experiments carried out with banded ore, two solutions of 146 g/lt and 59 g/lt concentrations have been obtained with 72.66 % total efficiency; while two solutions of 198 gr/lt and 54 g/lt concentrations have been produced with total efficiency of 89.83 % with breccia ore. At the end of Dissolution + Filtration and Dissolution + Flocculation +Decantration tests with banded and breccia ores, the best results yielding high B2O3 concentration with a high efficiency have been achieved by Dissolution +Filtration method. IXThe most significant problem which appeared during Dissolution +Filtration tests originated from the existence of insoluble solids and clay in the ore. In order to investigate the effects of impurities of the tincal ore on the refining processes, the ore blends with different B2O3 and reduced clay contents were tested in Dissolution +Filtration experiments. These tests proved that concerning the efficiency and B2O3 content of the solution, the ore containing 35 % B2O3 happens to be the most suitable one. In view of the results obtained from the Dissolution + Filtration tests, it has been determined that in order to produce a tincal concentrate with 35 % B2O3 content, beneficiation experiments have to be made with the banded and breccia ores by scrubbing. According to the experimental results, it was observed that there was no separation between the insoluble solids and the boron minerals, so that the scrubbing experiments were carried out where dinamic methods gave beter seperation than static ones applied by soaking the ore in water for 24 hours. In the scrubbing experiments with the banded and breccia tincal ores, the optimum parameters were determined as follows; agitation speed of 1000 rpm, 50 % of solid content, 20 minutes of scrubbing time and particle size of minus 6 mm. In addition 98,55 % efficiency was obtained with the banded concentrate having 34,56 % B2O3 and 99,76 % efficiency with breccia concentrate with 35,99 % B2O3 grade. It was found out from the experiments done with banded and breccia ores that the most important parameter affecting the efficiency and the B2O3 content is the particle size. The product above the size of 0.106 mm, when the particle size decreases the B2O3 content increases with decreasing efficiency. When the particle size is above 6 mm, the product obtained in the size range of +0.106 mm, with banded ores contains maximum 32.78 % B2O3 content and the decrease of efficiency. In this thesis, by using the methods of scrubbing and classification it was observed that a tincal concentrate containing 35 % of B2O3 could be obtained with 98 % efficiency and from this concentrate, by Dissolution + Filtration, a borax solution could be produced with the total efficiency of 96 % based on the ore. Also the productions of borax compound from tincal ore treated either directly or after concentration were compared from the technological and economical points. It was proved that the most suitable way to produce borax compound from the ore was the use of the concentrate containing high B2O3. 101