Tane pürüzlülüğü ve yuvarlaklığının flotasyona etkisi
Effect of particle roughness and roundness on flotation
- Tez No: 467301
- Danışmanlar: DOÇ. DR. FIRAT KARAKAŞ
- Tez Türü: Yüksek Lisans
- Konular: Maden Mühendisliği ve Madencilik, Mining Engineering and Mining
- Anahtar Kelimeler: Belirtilmemiş.
- Yıl: 2017
- Dil: Türkçe
- Üniversite: İstanbul Teknik Üniversitesi
- Enstitü: Fen Bilimleri Enstitüsü
- Ana Bilim Dalı: Cevher Hazırlama Mühendisliği Ana Bilim Dalı
- Bilim Dalı: Belirtilmemiş.
- Sayfa Sayısı: 89
Özet
Bu tez çalışmasında tanelerin morfolojik özelliklerinin, flotasyonla kazanılmalarını ne ölçüde etkilediği gerek mikro-flotasyon gerekse tane-kabarcık etkileşimlerinin görüntülenmesiyle araştırılmıştır. Bu amaçla çalışmada hidrofilik yüzey özelliklerine sahip kuvars ve hidrofobik yüzey özelliklerine sahip talk gibi iki farklı türde mineral taneleri kullanılmıştır. Öncelikle farklı öğütme koşullarının (pülpte katı oranı, öğütme süresi, öğütücü ortam), asit ve aşındırıcı tozla muamele işlemlerinin tanelerin morfolojik parametreleri (yuvarlaklık ve tane pürüzlülüğü) üzerindeki etkileri görüntü analizi yöntemiyle tespit edilmiştir. Tane morfolojilerinde meydana gelen değişimlerin tanelerin yüzey enerjisi ve temas açısındaki etkileri de“kapiler yükselme”yöntemiyle belirlenmiş olup, Washburn denklemleri kullanılarak tanelerin ıslanabilirlik dereceleri de saptanmıştır. İkinci aşamada ise diğer şartlar (pH değeri, kollektör konsantrasyonu, karıştırma ve havalandırma hızı) sabit alınarak, yalnızca tane morfolojisinin etkisinin incelendiği mikro-flotasyon çalışmaları gerçekleştirilmiş, elde edilen sonuçlar bu özelliklerin bir fonksiyonu olarak değerlendirilmiştir. Bu çalışmalara ek olarak, tane-kabarcık etkileşimleri hızlı kamera ile görüntülenerek, morfolojide meydana gelen değişimlerin tane-kabarcık etkileşimlerine ne yönde etkilediği de gösterilmiştir. Sonuç olarak gerek kuvars gerekse talk mineralinde farklı öğütme şartlarında elde edilen en düşük yuvarlaklık ve en yüksek pürüzlülüğe sahip tanelerin hem yüksek flotasyon verimiyle alınabildikleri hem de daha düşük yüzey enerji değerine sahip oldukları tespit edilmiştir. Kuvars taneleriyle yürütülen flotasyon çalışmalarında aynı kollektör konsantrasyonunda herhangi bir morfolojik değişime uğramamış kuvars taneleriyle yaklaşık olarak %40-45 aralığında verimler elde edilebiliyorken, bu oran bilyalı değirmenle %50 şarj oranında yapılan öğütme işleminden sonra %56 yükselirken, çubuklu değirmenlerde %51, aşındırma işlemlerinde %49 ve asitle muamele işlemlerinde ise %48 oranlarındadır. Elde edilen bu sonuçlar öğütme gibi mevcut endüstriyel tesislerde uygulanan yöntemlerin daha kontrollü olarak yapılması durumunda %40-45'lerden %56'lık verimlere ulaşılabileceğini göstermektedir. Talk taneleriyle yürütülen flotasyon çalışmalarında, bilyalı değirmenle yaş olarak elde edilebilen maksimum verim yaklaşık %24'te kalırken, bu durum asitle muamele ve aşındırma için yaklaşık %20 civarındadır. Elde edilen bu morfolojik karakterizasyon verileriyle, mikro flotasyon sonuçları arasında korelasyonlar kurularak, tane morfolojisinin flotasyon verimlerini %13 oranında yükselttiğini gösterilmiştir. Hızlı kamera görüntülerinden elde dilen sonuçlarda ise, düşük konsantrasyonlarda tane köşelilik oranı arttıkça tanelerin kabarcığa yaklaşım hızının arttığı, tanelerin en yüksek yüzey alanına sahip kısımlarından ve pürüzlü yüzeyleri boyunca kabarcığa yaklaştıkları gösterilmiştir. Bunun yanında yüksek konsatrasyonlarda, köşeli ve pürüzlü tanelerin kabarcığa yaklaşma aşamasında bir araya gelerek kabarcığa tutunmalarıdır. Sonuç olarak artan köşelilik ve pürüzlülük değerlerinde daha yüksek flotasyon verimlerinin elde edildiği gösterilmiştir.
Özet (Çeviri)
The evaluation of the underground resources, which are becoming increasingly important nowadays, is of great importance in terms of technological and economic investments. In the assessment of existing underground resources, the main physical, chemical and physico-chemical properties of the ores are utilized. In order to meet the desired product qualities (content, yield, etc.), the most important parameters is the liberation size of the minerals to concentrate precious minerals. Despite the application of many methods in very fine sizes, the flotation process which is made by utilizing the physico-chemical properties of minerals is the most used process among these methods. In this method, the surface properties of the minerals are important; while the hydrophobic minerals float in the air bubbles, minerals that are hydrophilic are sinking in water. Hydrophilic minerals can be attached to air bubbles by changing surface properties with various reagents when necessary. In flotation, the determination of the medium pH value, the type of additive and the amount of valuable and gang minerals as well as the morphological properties of the minerals (surface roughness and shape factor) may give an indication of the differences in the process. The morphological properties directly influence the flotation yields as they effect on both particle-particle interactions and adsorption ratios of the reagents. Grinding systems in both the industrial and laboratory scale have some issues in the process with fine particles and the optimum conditions are determined by modeling of these systems by evaluating many parameters such as grinding media, solid wt. %, grinding environment ratio and grinding time. When an evaluation is made in terms of grain size according to the literature, it is known that material can be produced in a narrower size range in the rod mill while the material can be produced in a finer and wider size range in ball mills. However, it has been shown that the particles obtained from the rod mill are more angular than the particles obtained from the ball mill. On the other hand, angularity value ontained from the autogenous mill is between one obtained from the rod mill and the ball mill. The roughness of the particles changes depending on grinding type whether it is dry or wet , as the fine particles attached to the surface of the relatively coarser particles are washed away in the wet grinding process smaller roughness values can be obtained. In the case of dry grinding conditions, roughnesses in micro size will be obtained. The surface roughness, which is the morphological characteristics of the particles, refers to the textural structure of the surface, in other words, the ratio of the true surface to the ideal surface area. In addition, roughness can be calculated by many formulas and/or approaches. Roughness has effect on some parameters such as solidsolid interaction and adsorption of chemicals to mineral surfaces as much as in contact angle measurements used to determine the wettability properties of solids or mineral grains, especially when assessed for ore preparation. In this thesis, production parameters (as a result of milling, grinding, acid treatment processes) and its degree were determined for the shape factor and, in particular, the roughness of particles. At the same time the differences between smooth and rough particles are explained. It is important to reveal the effect of roughness of particles on contact angle, surface energy of particles and flotation efficiency in terms of scintific and industrial applications. In many studies in the literature effects of parameters such as particle size, pH value of the medium, the effects of reagent type and amount are investigated intensively in the evaluation of flotation. However, studies considering the effect of roughness on flotation. are insufficient In many studies in the literature, the average roughness of the particles obtained from different processes are discussed, but the differences that occur in varying roughness values have not been examined in detail. Hence, this is a one of the major problem in revealing the effect of roughness. Revealing the effect of particle morphology on particle bubble interactions, which is one of the effective parameters for flotation, is crucial for flotation. In the literature, there are very few studies shown the effect of roughness on flotation while the effectiveness of the shape factor is mainly revealed. In this study, the effect of morphological properties of particles on their enrichment characteristics were investigated by performing micro-flotation tests and bubbleparticle interactions. For this purpose, two different types of mineral, such as quartz with hydrophilic surface properties and talc with hydrophobic surface properties, were used. Firstly, for the purpose of changing the surface roughness of the particles milling in different grinding media (autogenous grinding with ball, rod, acid and fine-size abrasive powder) and different grinding conditions (solid wt. %, grinding time, grinding medium) were used. Then, the size distributions of the particles obtained from grinding processes were determined and shape factor analysis was performed by image analysis method in each size range. Micro-flotation tests were carried out in order to reveal the behavior of the flotation process by taking morphological characteristics of particles and those of certain size groups (150-106, 106-75 and 75-53 μm). In addition, wettability properties of materials modified morphologically under certain conditions are supported by contact angle measurements. For this purpose,“capillary rise”method has been used in measuring contact angles of fine particles. As a result of measurements with apolar and polar liquids with different surface energies, morphological variations, changes in contact angle values of materials and free surface energies have been determined. In addition, bubble-particle interactions has shown by using a high speed camera to show the effect of morphological properties in bubble- particle interactions during flotation. Therefore, the main objective of this thesis is to determine the effect of shape factor and especially the effect of roughness parameter on flotation yields by considering different approaches from the literature. Moreover obtained data from the experimets have calculated by MiniTAB for getting a useful model for both in scientific and industrial scale. As a result, it was determined that higher flotation recoveries and lower surface energy values were obtained with quartz and talc particles having lower roundness and higher roughness degrees. In flotation studies carried out with quartz particles which have different morphological properties, approximately 40-45% flotation recovery can be obtained for particles that have not been subjected to any treatment This ratio increases to 56% in ball mill grinding with 50% ball charge ratio. It is 51% for the rod mill, 49% for the abrasion and 48% for the acid treatment. These results show that if the methods applied in existing industrial applications such as grinding are conducted with more controlled, the efficiencies can increase from 40-45 % to 56%. As a result of different grinding conditions, abrassion and acid treatment for talc, which is another mineral studied in the thesis, particles were investigated in terms of both morphological and flotation characteristics. If a comparison is made in terms of the effect of the morphological indices of the particles on flotation recoveries, the maximum recovery obtained by wet ball mill as 24%. It is around 20% for acid treatment and abrasion. A correlation has been established between these morphological characterization and micro flotation results and it has shown that particle morphology can make an increment in flotation recovery of 13%. In the results obtained from high speed camera, it has been shown that the morphological properties have an important role in bubble-particle interactions. It has been shown that as the angularity of particles increase at lower collector concentrations, the particles approach the bubble at higher speed. I has also shown that particles attach to the buble surface with their highest surface area and rough surfaces However, another phenomenon that occurs in bubble-particle interactions. At higher collector concentrations before tha attachment to the buble surface, angular and rough particles are coagulated and come together in the process of approaching through the bubble surface. As a result, it has been shown that higher flotation recoveries are obtained with increasing angularity and roughness values.
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