An Introduction to Montmorillonite Purification

Purification of montmorillonite is a process to remove non clay minerals (gangue) such as calcite, feldspar, quartz, opal (C-T), and mica from montmorillonite ore. This is performed to make montmorillonite suitable for use in sensitive applications such as pharmaceutical, cosmetic, food, and advanced materials for nanotechnology. Gangue minerals in raw montmorillonite ores can cause serious health problems when used in pharmaceutics, cosmetic, and food industries and reduce material quality in advanced materials production. Montmorillonite purification can be divided into two main classes as physical and chemical purification. Physical purification processes are based on particle size difference between the gangue and montmorillonite minerals. Purification processes based on gravity separation are ineffective since the specific weights of gangue and montmorillonite minerals are very close to each other. Physical purification process includes sedimentation, centrifugal separation, aero separation, and sieving techniques. Chemical purification of montmorillonite is based on dissolution and so extraction of carbonates, metal hydroxides, organic materials, and silica, respectively, using different leaching techniques.

Improving the mechanical-mathematical model of pneumatic vibration centrifugal fractionation of grain materials based on their density

This paper has substantiated the mechanical-mathematical modeling of the process of fractionation of grain material into fractions. It has been established that this could optimize the process parameters and would make it possible to design new or improve existing working surfaces of centrifugal separators. A mechanical-mathematical model of the pneumatic vibratory centrifugal separation of grain material by density has been improved. This research is based on the method of hydrodynamics of multiphase media. The improved mechanical-mathematical model takes into consideration the interaction between the discrete and continuous phases of grain material by introducing conditions of interaction at the interface of these phases. In the hydrodynamic modeling of the movement of the circular layer of seeds, the coefficient of dynamic viscosity of discrete and continuous phases was taken into consideration. It was established that the pneumatic vibratory centrifugal separation process parameters are critically affected by the circular frequency of rotation of the cylindrical working surface, the frequency and amplitude of its oscillations. As well as such process characteristics as the airflow rate, dynamic viscosity coefficient, the average thickness of a grain material layer, and the mean density of its particles. Rational values for the technical parameters of the grain material pneumatic vibratory centrifugal fractionation process in terms of density have been determined by using the improved mechanical-mathematical model. The amplitude and oscillation frequency of the working surface are in the ranges A=(35…50)·10–5 m, ω=15.0...15.6 rad/s. The circular rotation frequency of the working surface, ω=24...25 rad/s. The airflow rate, V=2 m/s. It was established that using the improved mechanical-mathematical model of fractionation makes it possible to improve the performance of a pneumatic vibratory centrifugal separator by 9 %. At the same time, the effectiveness of grain material separation could reach 100 %.

High Concentration Fine Particle Separation Performance in Hydrocyclones

The vast majority of current research on hydrocyclone field centrifugal separation focuses on low concentration fluids having volume fraction less than 3%. For high-concentration fluids having volume fractions greater than 10%, which are often encountered in engineering, the law governing particle motion and the classification mechanism are still unclear. In order to gain insights into the interaction between fine particles in the high concentration hydrocyclone field and to improve the hydrocyclone separation performance of these particles, a Dense Discrete Phase Model (DDPM) of the Euler-Eulerian method under the Ansys Fluent 14.5 software was employed. Numerical simulations were carried out to study the characteristics of the hydrocyclone field of dense particles and the influence of parameters, such as the diameter of the overflow outlet, diameter of the underflow outlet, and material concentration, on separation performance. The trajectories and separation efficiencies of two kinds of fine particles with different densities and six different particle sizes at high concentration were obtained. The results show that for the hydrocyclone classification of high-concentration fine particles, particles with large density and small particle size are more likely to enter the internal cyclone and discharge from the overflow. Particles with small density and large particle size are more likely to enter the external cyclone and discharge from the underflow. The research results of this topic could provide a feasible reference and theoretical basis for the centrifugal separation of high-concentration fine particle fluid.

A centrifugal microfluidic cross-flow filtration platform to separate serum from whole blood for the detection of amphiphilic biomarkers

The separation of biomarkers from blood is straightforward in most molecular biology laboratories. However, separation in resource-limited settings, allowing for the successful removal of biomarkers for diagnostic applications, is not always possible. The situation is further complicated by the need to separate hydrophobic signatures such as lipids from blood. Herein, we present a microfluidic device capable of centrifugal separation of serum from blood at the point of need with a system that is compatible with biomarkers that are both hydrophilic and hydrophobic. The cross-flow filtration device separates serum from blood as efficiently as traditional methods and retains amphiphilic biomarkers in serum for detection.