Balıkesir Düvertepe kaolenlerinin kağıt endüstrisinde kullanım olanaklarının araştırılması

Abstract

Dünyada, her yıl üretilen toplam kaolen miktarının yarısı kağıt sanayiinde tüketilmektedir. Kağıt sanayiinde dolgu ya da kaplama pigmenti olarak kullanılan kaolenlerin en önemli özelliği suda dağılması için süzülebilirlik özelliğidir. Bu özellikteki kaolenler suda ayrışarak içindeki silis ayrılır ve ortamdan uzaklaştırılır. Bu işlem kaolenin aşındırıcı özelliğini azaltırken alümina içeriğini yükseltir. Kağıt sektöründe tüketilen kaolenler tesis çıkışı pazara arz edilir. Türkiye kağıt sektörü kaolen ihtiyacını ithalat yolu ile karşılamaktadır. Bunun birinci nedeni yıkanıp süzülebilir yumuşak kaolen yataklarımızın çok az oluşudur. Dünyada bu tür kaolenlerin ya granit gibi derinlik kayaçlarının veya feldspatça zengin arkoz tipi sedimanter kayaçların bozuşmasından oluştuğu bilinmektedir. Türkiye'nin kaolin yatakları ise genellikle hidrotermal eriyikler veya solfatarlarla altere olmuş volkanitlere bağlıdır. Bu tür kaolenler sert olup çok ince silis ihtiva etmekte ve yıkama ile zenginleştirmeye imkan vermemektedir. Bu çalışmada Balıkesir - Düvertepe bölgesinde Söğüt Madencilik A. Ş. ruhsat sınırları içinde yer alan ocaklardan 10 adet kaolen numunesi alınmıştır. Numune alınan ocaklarda rezerv etüdü yapıldıktan sonra, numunelerin minerolojik ve kimyasal özellikleri tesbit edilmiştir. Elde edilen veriler ışığında kimyasal özelliklerin yanısıra, kağıt sektöründe kaliteyi belirleyen diğer bir unsur olan tane boyutu dağılımının mevcut standartlara uygun hale getirilebilmesi için cevher hazırlama işlemlerine gereksinim duyulmuştur. Bu aşamada rezerv potansiyeli çok olan sınırlı sayıda numune kullanarak zenginleştirmeden ziyade, boyuta göre sınıflandırma yapılmıştır.

The mineral kaolinite is öne of the commonest minerals in the upermost 10 metres of the continental crust ranking in abundance alongside minerals like quartz, mica, feldspar and calcite. Only very exceptionally does it possess ali the necessary properties needed to make it worth commercially exploiting. Kaolinite is the minerological name for a white hydrated aluminium silicate clay mineral, and the term "kaolin" is applied to a product principally composed of kaolinite (ör in some cases halloysite), which is produced from a mineral deposit containing significant quantities of kaolinite. Kaolinite is always fine grained and normally occurs as crystals ranging in size from a fraction of a micron up to several hundred microns across. The structure of kaolinite shows it to be composed of a tetrahedral sheet (Sikici) linked to an octahedral sheet (A^O^OHJg) to form a single layer. The relatively weak bonding between the layers gives the mineral a platey character when wiewed under the scanning electron microscope. The SEM also shows that kaolinite occurs in a variety of forms ranging from small pseudo-hexagonal plates randomly oriented, through small stacks of plates, to large curled stacks of plates with individual plates having an Irregular outline. Within the crystal lattice there may be a degree of disorder, notably in the b-axis direction. Generally speaking, fine grained kaolinites formed under low temperature diagenetic conditions tend to be disordered and kaolinites found in massive hydrothermal deposits tend to be well ordered. The partide size distribution and partide shape are two of the most xı important characteristics which control the rheological properties of clay/water mixtures, interlaying of other clay minerals such as illite in the kaolinite crystal can also affect these properties. The presence of iron, either in the kaolinite lattice, ör as an oxide coating on the kaolinite, is a bad feature, because of its effect on brightness, both raw and fired. The overall composition of kaolinite is expressed as oxides, it is SİÛ2 46,5 %, A12Û3 39,5 % and H2Û 14 %. The crystal structure is generally resistant to attack by most corrosive fluds, so that kaolinite can be regarded as an inert white powder which will not react with most mediums in which it is placed. Kaolin deposits are located by core drilling in geologically favoroble areas. When the deposit is scheduled for mining, the land is cleared of timber and huge draglines ör motorized scrapers are used to remove the overburden exposing the kaolin seam. Additional closespaced drilling proxides a detailed evaluation of the uniformity and quality of the deposits. This information is plotted on topographic maps so that the mining operations can be properly controlled. The most important use for kaolin in terms of value is in the paper industry. Kaolin is used in large quantities an a.coating and filling pigment for paper and board. Many grades of paper contain about 30 wt % mineral pigment of which large proportion is often kaolin. The demand for kaolins for paper is stili increasing although recent years have seen a rapid growth in use of alternative pigments such as calcium carbonate. Pigments are used as fillers in papers to improve optical properties sucsh as birghtness and opacity and to reduce costs by replacing expensive chemically refined pulp. Fillers are relatively cheap and must have aeceptable abrasion and consistent optical properties. Coating prigments are used to achieve a smooth, glossy surface for printing. The requirements of gloss and certain specific properties to improve printed paper quality, and the rheological conditions involved in the modern, high speed paper coating process ali place strong demands on pigment properties. Meanwhile kaolin also get many desirable physical and chemical properties including X2.1 white color, fine partide size, platelet partide structure, low abrasiveness and chemical inertness. in this thesis, it has been researched to obtain kaolin of the suitable quality in paper industry. Kaolin samples are taken from Balıkesir-Düvertepe kaolin pits of Söğüt Mining Co.. Clay mineral identifications of representative samples were based upon X-ray powder diffraction patterns. The main minerologic component in the representative samples is kaolinite. The numbere of l, 2 and 3 samples are characterized by comperatively high quartz content. Dark spot is also commonly observd on the surface of kaolinitic clay. This spot derives from pyrite. The uppermost part of the sequence is hard and compact, and contains smectite as well as some kaolinite. The numbere of 5 sample is characterized by well-ordlered kaolinite. Meanwhile the numbere of 4, 6, 7 and 8 samples which are identified by high alümina contents a long with high alunite coexistence. The number of 9 and 10 samples are identified by mixture of kaolinite and dickite is accomponied of mid-level alunite content. Ali of the collected samples were examined with XRD which is RIGAKU Geigerflex D/max-Theta/Theta VC Model. According to the results of X-ray analysis, some typical samples were selected för TG-DTA analysis. RIGAKU TAS-100 System was used for the study. 20 mg same powder samples used for the XRD anlysis were heated up to 1100°C with a fixed rate of 10°C/min. in the TG-DTA analysis, a comment on the temperature of endothermic peaks is necessary. As it is well known, and important endothermic peak of kaolinite is reportedly to appear at 550 to 650°C (Mackenzie, 1957). The peak showing the transformation of low quartz to high quartz at 573°C without exception. DTA of the numbere 2 kaolin sample is showed thatkaolinite and high content of quartz accomponied smectite. Kaolinite showed 72.8°C and 516.3°C endothermics and 972.4°C exothermic. The endothermic peaks of kaolinite are appeared almost trough - shaped. This might be the influence of smectite. (The numbere of 7 kaolin sample is having an interesting DTA). Kaolinite showed 39.5°C and 554.7°C and also 787.7°C endothermics and 991.7°C exothermic. The uncommon endhotermic peak appeares at 787,7°C are due to alunite bering. The numbere of 5 kaolin sample DTA showed well-ordered XIII kaolinite and quartz. The endo thermic peaks of kaolinite are almost symmetrical at 519. 5°C. Exothermic peak appeared at 985. 1°C. The numbere of 8 kaoline sample have characteristic DTA. Kaolinite showed 580. 3°C endothermic and 984. 8°C exothermic. Model ABT-60 of TOPCON was used for the SEM observation. The gold coated fragmental samples were observed at various magnifications. A total of 13 selected SEM photos were showed same significant features of the component minerals. Chemical analysies of representative kaolin samples are made by MTA and SSS. labrotories. The minerological and chemical researches of Balikesir- Düvertepe kaolins are given chapter 5 by figures. At the light of these datas about kaolin samples need to recover physical properties for using a raw material in paper industry. The aim of this experimental study to recover coating and filling quality kaolen concentrate with 17-41 % Aİ2O3 content and maximum 1.0-5.0 % SO3 by the use of hydrocyclone where the effect of pulp density, feed pressure, pulp viscosity and discharge opening diameter were studied. Two inches diameter Mozley C-124 polyuretane hydrocyclone were used by varying discharge opening between 3.2-4.5 mm; feed pressure between 10-30 psi. The pulp feed to the cyclone had solid contents of 10, 20 and 30 % respectively. Without any additives, the optimum seperation results were obtained 20 % solid content, 4.5 mm. discharge opening at 20 psi feed pressure where overflow was 84.3 % of feed weight with 15.46 % AI2O3 and 0.12 % SO3 of Çaltılıtaban kaolins. The result of this experiment showed that Çaltılıtaban kaolins have got more silicas and kaolin - quartz seperation is not achieved by hydrocylone. Therefore Çaltılıtaban kaoline can be used as a substituted material with having high alumina and alunite content of kaolins. The aim of this usage might be decreased SO3 content to obtain desired constitutions. The representative kaolin samples were tried different mixtures to obtain which might be substituted material as a pigment coating or filling agent in paper industry. XIV At the end of this research, Balikesir-Dtlvertepe kaolins would be used in paper industry as a coating or filling agent, after ore classification process was inmplemented.