The role of interparticle forces in colloidal aggregates: local investigations and modelling of restructuring during filtration

2006 ◽  
Vol 53 (7) ◽  
pp. 25-32 ◽  
Author(s):  
J.B. Madeline ◽  
M. Meireles ◽  
R. Botet ◽  
B. Cabane
Keyword(s):  
Scaling Laws ◽  
Particle Distribution ◽  
Model Systems ◽  
Separation Processes ◽  
Interparticle Forces ◽  
Colloidal Aggregates ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
Applied Stresses

Industrial solid–liquid separation processes, such as pressure filtration or membrane processes, involve the application of pressure to suspensions. In response, some water is extracted, the suspension volume is reduced, and the dispersed aggregates start to form a network. In recent works, we aimed to make a prediction for the response of aggregates to stress which occurs during a filtration. We chose model systems made of aggregated silica nanoparticles. Some of these systems offer a strong resistance to applied stresses, and retain their permeability; others yield and collapse. We used small angle neutron scattering by which we can locally quantify the particle distribution within the network to determine the processes by which particles reorganise during collapse: we found that reordering processes at the scale of 1 to 10 particle diameters control the course of collapse and the loss of permeability. Finally we constructed a numerical model for describing the processes by which colloidal aggregates are compressed. This model predicts that the response of such networks to pressure follows some scaling laws, which depend only on the elastic vs. dissipative nature of interparticle bonds.

Theoretical and Experimental Study of Hydrocyclone Performance and Equivalent Settling Area

2014 ◽  
Author(s):  
Reza Sabbagh ◽  
Michael G. Lipsett ◽  
Charles R. Koch ◽  
David S. Nobes
Keyword(s):  
Mathematical Model ◽  
Settling Tank ◽  
Performance Model ◽  
Separation Performance ◽  
Separation Processes ◽  
Gravity Settling ◽  
Approaches To Study ◽  
Equivalent Area ◽  
Solid Liquid ◽  
Solid Liquid Separation

Predicting the performance of a solid-liquid separation process can help in comparing different separators for selection and design. This can be applied to hydrocyclone technology which is used widely in industry due to being an inexpensive device that is easy to operate and maintain and which has no moving parts. Environmental concerns and technological issues in separation processes are motivating the design of higher efficiency systems with less capital and operating costs. There is a need therefore for, methods to compare different separation technologies. In spite of extensive research into hydrocyclone performance, a mathematical model that can predict the performance of a hydrocyclone for comparison with other centrifugal separators is rare in the literature. The main objective of this research is to apply theoretical and experimental approaches to study hydrocyclone performance in order to propose an applicable separation performance model that represents the whole hydrocyclone operating range. A mathematical model is developed to explore the performance of the separator and to predict the hydrocyclone’s equivalent area as compared to a continuous gravity settling tank. A performance chart that can be used for selection and design of hydrocyclones is the result of the model.

Obtaining Constitutive Equations for Thickening and Filtration Non-Newtonian Fluids

2014 ◽  
Vol 802 ◽  
pp. 274-279 ◽  
Author(s):  
Helio de Oliveira ◽  
Bruno Arantes Moreira ◽  
João Jorge Ribeiro Damasceno ◽  
Fabio de Oliveira Arouca
Keyword(s):  
Constitutive Equations ◽  
Xanthan Gum ◽  
Sediment Concentration ◽  
Particulate Material ◽  
Newtonian Fluids ◽  
Liquid Separation ◽  
Separation Processes ◽  
Medium Permeability ◽  
Solid Liquid ◽  
Solid Liquid Separation

The study of filtration and thickening of particulate systems are used in many industrial processes involving processes of solid-liquid separation, such as in sedimentation ponds, filters, the drilling of oil wells, among others. This paper aims to advance the empirical mechanisms involved in the processes of solid-liquid separation and obtain constitutive equations relating the pressure in solids and porous media permeability from non-Newtonian fluids. In the experiments used aqueous solutions of xanthan gum concentration of 0.1% in weight basis in order to ensure non-newtonian means. For the preparation of suspensions, was used calcium carbonate as particulate material in the separation process involved an initial concentration of 12% by volume. The concentrated sediment was maintained between 30 and 48% by volume. Settling tests were carried to term and sediments resulting from each test were evaluated by making use of the Gamma Rays Attenuation Technique (GRAT). The results show that GRAT is effective in determining sediment concentration distributions formed from non-Newtonian solutions, allowing the constitutive equations to obtain pressure and the solid porous medium permeability, very important for simulations of solid-liquid separation processes.

scholarly journals STUDI RECOVERY ALUMINA DARI TANAH LEMPUNG GAMBUT KAWASAN LANDASAN ULIN KOTA BANJARBARU

Konversi ◽  
2012 ◽  
Vol 1 (1) ◽  
pp. 13
Author(s):  
Sofyan Hadi ◽  
Sugianto Sugianto ◽  
Agus Mirwan
Keyword(s):  
Peat Soil ◽  
Weight Ratio ◽  
Initial Sample ◽  
Separation Processes ◽  
Calcined Clay ◽  
Leaching Process ◽  
P Leaching ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
Alumina Recovery

Abstrak- Tanah lempung gambut memiliki kandungan alumina yang memiliki banyak manfaat. Proses recovery alumina dari tanah lempung gambut dapat dilakukan menggunakan metode kalsinasi dan elutriasi. Penelitian bertujuan untuk mengambil kembali alumina dari tanah lempung gambut dan mempelajari pengaruh variasi penambahan CaCl2 serta keefektifan variasi kecepatan pengadukan terhadap pengambilan alumina dari tanah lempung gambut. Penelitian dilakukan dengan beberapa tahap. lempung yang berasal dari tanah gambut dibersihkan dan dikeringkan. Lempung gambut yang sudah kering dilakukan penggerusan dan pengayakan hingga didapatkan lempung gambut berukuran 75 mesh. Lempung gambut yang berukuran 75 mesh  dicampur dengan CaCl2 dengan variasi perbandingan CaCl2 :  lempung gambut adalah 0,5:1, 1:1, dan 1,5:1. Masing-masing campuran CaCl2 dan  lempung gambut dikalsinasi dengan pemanasan dalam furnace pada suhu 800oC selama 4 jam. Lempung gambut hasil kalsinasi kemudian digerus dan diayak hingga  berukuran 200 mesh. 80 gram lempung gambut hasil kalsinasi ukuran 200 mesh ditambahkan 400 mL larutan HCl 6 N, kemudian dilakukan p leaching dengan pengadukan selama 2 jam dengan kecepatan pengadukan sebesar 200 rpm, 300 rpm dan 400 rpm. Larutan hasil leaching didekantasi dan difiltrasi. Filtrat hasil leaching diuapkan  sampai tersisa 100 mL, selanjutnya ditambahkan dengan 100 mL aquadest. Penguapan kembali campuran filtrat dan aquadest sampai volumenya 100 mL dilakukan dengan pengadukan. Cairan yang dihasilkan diuji kandungan aluminanya dengan menggunakan titrasi volumetrik berdasarkan SNI 13-6620-2001. Berdasarkan hasil analisis untuk sampel awal diperoleh kadar alumina dalam tanah lempung gambut 2,81%. Hasil akhir diperoleh kadar alumina optimum yang dapat terambil dari tanah lempung gambut sebesar 0,622% menggunakan variasi perbandingan berat CaCl2 dan lempung gambut 0,5:1 dengan kecepatan pengadukan sebesar 400 rpm.Keywords: tanah lempung, alumina, kalsinasi, elutriasiAbstract- Peat clay contains alumina (Al2O3) that has many benefits. The process of recovery of alumina from clay peat can be done by using the method of calcination and elutriasi (stirring). This research aims to recover the alumina from clay peat and study the effect of the addition of CaCl2variations and the effectiveness of stirring speed variations in the process of alumina recovery from clay soils. This research was conducted with several steps. Clay from the peat soil is cleaned and dried by drying. The dry clay that has been done peat milling and sifting to obtain the size of 75 mesh peat clay. A 75 mesh peat clay mixed with a variation ratio of CaCl2 and peat clay is 0,5:1, 1:1, and 1.5:1. Each mixture of CaCl2 and peat clay calcined by heating in a furnace at a temperature of 800°C for 4 hours. Calcined peat clay was performed milling and sifting through a 200 mesh. 80 grams of calcined clay peat size of 200 mesh is added 400 mL of HCl 6 N, then performed solid-liquid separation processes (leaching) with stirring for 2 hours with stirring speed of 200 rpm, 300 rpm and 400 rpm. Solution of the leaching process was decanted and filtered. The filtrate of the result of leaching process is heated (evaporated) until the remaining 100 mL, then added with 100 mL of aquadest. Heating (evaporating) re-mixed filtrate and aquadest until the volume of 100 mL of this process while stirring by using stirer. Liquid contents alumina was tested using volumetric titration method based on SNI 13-6620-2001. Based on the results of the analysis initial sample obtained for the content of alumina in the  peat clay is 2.81%. The final result is obtained optimum levels of alumina which can be recover from peat clay soi is 0,622%l using a variation of weight ratio CaCl2 and peat clay 0,5:1 with stirring speed of 400 rpmKeywords: peat clay, alumina, calcination, elutriasi.

Prediction of the dewatering of selected inorganic sludges

2001 ◽  
Vol 44 (10) ◽  
pp. 191-196 ◽  
Author(s):  
P.J. Harbour ◽  
A.A.A. Aziz ◽  
P.J. Scales ◽  
D.R. Dixon
Keyword(s):  
Volume Fraction ◽  
Efficient Operation ◽  
Capillary Suction ◽  
Laboratory Techniques ◽  
Dependent Parameter ◽  
Solid Liquid ◽  
Solid Liquid Separation ◽  
Separation Devices ◽  
Different Sources

There are a number of laboratory techniques traditionally used in the characterisation of sludges for the prediction of the efficient operation of dewatering processes such as centrifugation and filtration. In industry, capillary suction time and specific resistance to filtration measurements are common. Whilst useful in predicting trends, they do not assist in the design and optimisation of devices from first principles. Recent work in our laboratories has developed a technique for the fast measurement of the permeability and compressibility of sludge. This information, when coupled with first-principle models is useful for the prediction of the performance of solid-liquid separation devices. The work has shown that a single volume fraction dependent parameter, namely the solids diffusivity, calculated from permeability and compressibility, is able to fully characterise the dewaterability of sludge. This allows different sludges to be compared in an unequivocal fashion. Data will be presented for a range of sludges from different sources showing vastly different dewatering properties. The dewaterability of the different sludges is easily compared and the true role of flocculants in dewatering is highlighted.

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