Tane pürüzlülüğü ve yuvarlaklığının flotasyona etkisi
Effect of particle roughness and roundness on flotation
Yazar: NURGÜL KODRAZI
Danışman: DOÇ. DR. FIRAT KARAKAŞ
İstanbul Teknik Üniversitesi / Fen Bilimleri Enstitüsü / Cevher Hazırlama Mühendisliği Ana Bilim Dalı
Derece: Yüksek Lisans, 2017
Konu: Maden Mühendisliği ve Madencilik = Mining Engineering and Mining

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.

Abstract:
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.