Permanent magnetic drum separator

Wet magnetic drum separator structure and magnetic field characteristics

The structure of this magnetic separator is shown in Figure 1. It is composed of three main parts: Magnetic drum 1, magnetic system 2 and bottom tank 3.

The magnetic drum is made of rolled and welded stainless steel plate with thickness of 2 to 3 mm. The end cover of the magnetic drum is a cast aluminum piece, connected to the drum with stainless steel screws. The reason why use stainless steel (or copper) or aluminum for the drum is because these materials are non-conductive materials, with good permeability, so that the magnetic lines of force and the drum does not form a magnetic short circuit. The surface of the magnetic drum is also covered with a layer of wear-resistant rubber so that the drum surface is not worn. At the same time, it is conducive to the adhesion of magnetic particles on the drum surface, which strengthens the carrying effect of the drum on the magnetic particles, and the drum rotation is driven by the motor.
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Drum magnetic separator

Magnetic separators introduction

By creating an environment comprimizing a magnetic force (Fm), a gravitational force (Fg) and a drag force (Fd) magnetic particles can be separated from nonmagnetic particles by Magnetic separators.

Magnetic separation – Magnetic attraction force (Fm)
Fm = V x X x H x grad H
V = particle volume (determined by process)
X = magnetic susceptibility (see table below)
H = magnetic field (created by the magnet system design) in mT
(milliTesla) or kG (kiloGauss) 1 kG = 100 mT = 0.1 T
grad H = Magnetic field gradient (created by the magnet system design) in mT/m

Magnetic field and magnetic gradient are equally important factors for creating the magnet attraction force.

Magnetic separation – Competing forces

    • Gravitational force (Fg) is determined by particle size and density.
    • Drag force (hydrodynamic, aerodynamic), Fd, is determined by particle size, shape, fluid density, viscosity, turbidity and velocity.
    • Centripetal force (Fc).
    • Adhesion
    • Electrostatic forces etc.

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What is beneficiation?

1. What is beneficiation or mineral processing?

Beneficiation simply means by various kinds of equipments to extract useful minerals from the tailings, in this way useful minerals will be collected for smelting. Generally there are three methods, one is by magnetic separator for magnetic materials like magnetite, one is by gravity method, most for the materials that have specific gravity differences, like Chromite, Hematite, the third one is by flotaiton, like copper ores and gold ores

2. What’s the purpose of beneficiation?

The purpose of beneficiation is get rid of useless materials and tailings from the resources, so can get one or several kind of useful materials for better use. It greatly reduce the transportation cost and smelting cost.

Introduction of Magnetic Separation

Dry low-intensity magnetic separation is confined mainly to the concentration of coarse sands which are strongly magnetic, the process being known as cobbing, and often being carried out in drum separators. Below the 0.5 cm size range, dry separation tends to be replaced by wet methods, which produce much less dust loss and usually a cleaner product. Low-intensity wet separation is now widely used for purifying the magnetic medium in the dense medium separation process, as well as for the concentration of ferromagnetic sands.
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