METHOD OF CALCULATION OF MAGNETIC SEPARATORS WITH A FERROMAGNETIC BALL NOZZLE FOR CLEANING SUSPENSIONS FROM MAGNETIC IMPURITIES

Для повышения эффекта очистки суспензий от магнитных частиц экономически целесообразно в промышленных условиях использовать устройства с магнитными полями невысокой напряженности, но имеющими высокие градиенты магнитного поля в рабочем пространстве. В качестве таких устройств используются магнитные сепараторы с ферромагнитной шаровой насадкой. Для расчетов за основу взята модель процесса осаждения магнитных частиц в квазисплошном поглощающем экране магнитного фильтра, при этом предполагается, что рельеф зоны захвата в окрестности точек контакта намагниченных шаров будет в виде сегментов с характерными размерами rо и b. Анализ такой модели позволил отметить подобие рассмотренных процессов осаждения в магнитном сепараторе процессам адсорбции и в дальнейшем использовать элементы теории процесса адсорбции для расчетов таких сепараторов. Представлена методика расчета магнитных сепараторов с ферромагнитной шаровой насадкой для очистки суспензий от магнитных примесей. Экспериментальная проверка расчетных зависимостей при очистке антифрикционной присадки «Деста» подтвердила возможность использования предложенной методики для магнитных сепараторов с ферромагнитной шаровой насадкой To increase the effect of cleaning suspensions from magnetic particles, it is economically feasible in industrial conditions to use devices with low-intensity magnetic fields, but having high magnetic field gradients in the working space. As such devices, magnetic separators with a ferromagnetic ball nozzle are used. The calculations are based on a model of deposition of magnetic particles in a magnetic absorbing screen, and it is assumed that the topography of the capture zone in the vicinity of the contact points of the magnetized balls will have the form of segments with characteristic sizes ro and b. The analysis of such a model allowed us to note the similarity of the considered deposition processes in the magnetic separator with the adsorption processes and to further use the elements of the theory of the adsorption process for the calculations of such separators. A method for calculating magnetic separators with a ferromagnetic ball nozzle for cleaning suspensions from magnetic impurities is presented. Experimental verification of the calculated dependences during the cleaning of the anti-friction additive "Desta" confirmed the possibility of using the proposed calculation method for magnetic separators with a ferromagnetic ball nozzle.

Download Full-text

Enrichment of magnetic particles using temperature and magnetic field gradients induced by benchtop fabricated micro-electromagnets

Lab on a Chip ◽

10.1039/c7lc00825b ◽

2017 ◽

Vol 17 (23) ◽

pp. 4097-4104 ◽

Cited By ~ 2

Author(s):

A. Hosseini ◽

D. N. Philpott ◽

L. Soleymani

Keyword(s):

Magnetic Field ◽

Magnetic Particles ◽

Magnetic Forces ◽

Field Gradients ◽

Magnetic Field Gradients

Cooperation of thermal and magnetic forces used to drive and capture magnetic particles inside microsystems.

Download Full-text

Ion-Selective Ligands: How Colloidal Nano- and Micro-Particles Can Introduce New Functionalities

Zeitschrift für Physikalische Chemie ◽

10.1515/zpch-2018-1172 ◽

2018 ◽

Vol 232 (9-11) ◽

pp. 1307-1317 ◽

Cited By ~ 4

Author(s):

Indranath Chakraborty ◽

Dorleta Jimenez de Aberasturi ◽

Nicolas Pazos-Perez ◽

Luca Guerrini ◽

Atif Masood ◽

...

Keyword(s):

Magnetic Particles ◽

Colloidal Particles ◽

Particle Surface ◽

Ion Concentration ◽

Micro Particles ◽

Field Gradients ◽

Selective Ligands ◽

Magnetic Field Gradients ◽

Fluorescent Ligands ◽

Magnetic Resonance Imaging Mri

Abstract Colloidal nano- and micro-particles can introduce new properties and functionalities to existing materials and thus are a valuable building block for the construction of novel materials. This is discussed for the case of ion-selective ligands, hence molecules that can bind specifically ions of one type. First, in case ion-selective fluorescent ligands are attached to the surface of particles, these fluorophores sense the local ion concentration at the particle surface and not the bulk ion concentration. Thus, the ion-response of the ligands can be tuned by attaching them to the surface of particles. Second, in case ligands specific for particular ions are bound to the surface of particles, these ions can provide contrast and thus the particles can be imaged. This involves for example Gd-ions, which provide contrast for magnetic resonance imaging (MRI), and 111In-ions, which provide contrast for imaging of radioactivity. By attaching the ligands to the surface of particles, their physicochemical properties (as for example size and solubility) are changed, which affects their interaction with cells and, consequently, biodistribution. Attachment of ion-chelators for imaging to particles thus allows for tuning their biodistribution. Third, ion-specific ligands can be also attached to the surface of magnetic particles. In this case ions bound to the ligands can be extracted with magnetic field gradients and magnetic separation becomes possible. Therefore, magnetic particles provide a handle to the ligands, which enables the extraction of ions from solution. These examples demonstrate how the attachment of different types of colloidal particles to one existing class of molecules, ion-selective ligands, can open new fields of applications of these molecules.

Download Full-text

Patterning magnetic particles based on localized magnetic field gradients in microchannels for realization of multi-biosensors

2016 International Symposium on Micro-NanoMechatronics and Human Science (MHS) ◽

10.1109/mhs.2016.7824217 ◽

2016 ◽

Author(s):

Toshiki Minemura ◽

Satoshi Soga ◽

Moeto Nagai ◽

Takayuki Shibata

Keyword(s):

Magnetic Field ◽

Magnetic Particles ◽

Field Gradients ◽

Magnetic Field Gradients ◽

Localized Magnetic Field

Download Full-text

Nuclear magnetic resonance microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100156110 ◽

1989 ◽

Vol 47 ◽

pp. 828-829

Author(s):

Paul C. Lauterbur

Keyword(s):

Magnetic Field ◽

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Magnetic Fields ◽

Signal To Noise ◽

Field Gradients ◽

Useful Signal ◽

Magnetic Field Gradients ◽

Observation Times ◽

Nuclear Magnetic

Nuclear magnetic resonance imaging can reach microscopic resolution, as was noted many years ago, but the first serious attempt to explore the limits of the possibilities was made by Hedges. Resolution is ultimately limited under most circumstances by the signal-to-noise ratio, which is greater for small radio receiver coils, high magnetic fields and long observation times. The strongest signals in biological applications are obtained from water protons; for the usual magnetic fields used in NMR experiments (2-14 tesla), receiver coils of one to several millimeters in diameter, and observation times of a number of minutes, the volume resolution will be limited to a few hundred or thousand cubic micrometers. The proportions of voxels may be freely chosen within wide limits by varying the details of the imaging procedure. For isotropic resolution, therefore, objects of the order of (10μm) may be distinguished.Because the spatial coordinates are encoded by magnetic field gradients, the NMR resonance frequency differences, which determine the potential spatial resolution, may be made very large. As noted above, however, the corresponding volumes may become too small to give useful signal-to-noise ratios. In the presence of magnetic field gradients there will also be a loss of signal strength and resolution because molecular diffusion causes the coherence of the NMR signal to decay more rapidly than it otherwise would. This phenomenon is especially important in microscopic imaging.

Download Full-text