EFFECT OF COAGULANTS AND FLOCCULANTS ON DEWATERING OF KAOLIN SUSPENSIONS

Öz

   Kaolin tailings are commonly generated in the mineral industry. They are invariably negatively charged and consequently tend to form stable dispersions with poor flocculation characteristics. Coagulation–flocculation treatments are suitable methods for removing colloidal particles from wastewater. In this study, the effects of mono/multivalent ions (coagulants) and polymers (flocculants) on the sedimentation and electrokinetic behaviours of kaolin have been investigated. In experimental studies, Al₂(SO₄)₃, FeCl₃, MgCl₂, CaCl₂, NaCl were used as coagulant, while as flocculant anionic (A150), cationic (C521) and nonionic (N100) polymers were used. Isoelectric point of kaolin was determined as pH 4.2. The effectiveness of coagulants increased with the increase in the ionicity degree of the metal ions. Among the coagulants, FeCl₃ provided the highest efficiency (91%). Low sedimentation velocities (6.3-12.2 mm/min) were obtained with coagulants. The highest sedimentation efficiency (94%) was achieved with anionic flocculants and the same sedimentation velocity (58 mm/min) was reached with all flocculants. 

Anahtar Kelimeler

• Kaolin,dewatering,polymer,metal salts,zeta potential

KAOLEN SÜSPANSİYONLARININ SUSUZLAŞTIRILMASINDA KOAGÜLANT VE FLOKÜLANTLARIN ETKİSİ

Öz

   Kaolin atıkları mineral endüstrisinde yaygın olarak üretilir. Negatif yüklü olan bu atıklar zayıf flokülasyon özelliklerine sahip kararlı dağılımlar oluşturmaya eğilimlidirler. Koagülasyon-flokülasyon işlemleri, koloidal parçacıkları atık sulardan uzaklaştırmak için uygun yöntemlerdir. Bu çalışmada, mono/multivalent iyonların (koagülant) ve polimerlerin (flokülant) kaolenin çökelme ve elektrokinetik davranışlarına etkisi araştırılmıştır. Deneysel çalışmalarda, koagülant olarak Al₂(SO₄)₃, FeCl₃, MgCl₂, CaCl₂, NaCl ve flokülant olarak, anyonik (A150), katyonik (C521) ve noniyonik (N100) polimerler kullanılmıştır. Kaolenin sıfır yük noktası pH 4.2 olarak belirlenmiştir. Koagülantların etkinliği, metal iyonlarının iyoniklik derecesinin artması ile artmıştır. Koagülantlar arasında FeCl₃ en yüksek verimi (%91) sağlamıştır. Koagülantlar ile düşük sedimantasyon hızları (6.3-12.2 mm/dk) elde edilmiştir. En yüksek sedimantasyon verimliliği (%94) anyonik flokülant ile sağlanmış ve tüm flokülantlar ile yaklaşık olarak aynı çökelme hızına (58 mm/dk) ulaşılmıştır.

Anahtar Kelimeler

• Kaolen,susuzlaştırma,polimer,metal tuzları,zeta potansiyeli

Kaynakça

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