Magnetic separation

these will help you to understand the process of magnetic separation. it will help in industries

1. Particle Technology By Gulshad Ahmad Department of Chemical & Polymer Engineering University of Engineering & Technology Lahore (FSD Campus)

2. MAGNETIC SEPARATION Magnetic separation is a process in which magnetically susceptible material is extracted from a mixture using a magnetic force. This separation technique can be useful in mining iron as it is attracted to a magnet. 12/24/2018 2

3. MAGNETIC SEPARATION 12/24/2018 3

4. MAGNETIC SEPARATION Principle: Magnetic separation is technique used in metallurgy for the concentration  of ore particles. The principle of this method is that the magnetic ore particles can be separated from non magnetic impurities (gangue) or vice versa. 12/24/2018 4

5. Principle 12/24/2018 5

6. MAGNETIC SEPARATION Uses: In general terms, magnetic separation methods are used in several distinct processes: Magnetic filtration - recovery of liquid ( the magnetizable solids are discarded) - recovery of magnetizable solids (liquid is discarded) 12/24/2018 6

7. APPLICATIONS Concentration of magnetizable component into the magnetic fraction and rejection of the “non-magnetic” waste. Concentration of non-ferrous metals by discarding the non-metallic components of a mixture. It is also widely used to remove metal contaminants from plastics but not to separate plastics from each other. 12/24/2018 7

8. Types of magnetic separation processes Dry magnetic separation process. Wet magnetic separation process. 12/24/2018 8

9. DRY MAGNETIC SEPARATION In a dry mode, coarse magnetic particles can be recovered by a variety of high-intensity magnetic separators Including induced magnetic roll , cross belt separator , permanent magnet roll separator, rare-earth drum separator and open-gradient separator. 12/24/2018 9

10. The MagMill - for dry coal cleaning 12/24/2018 10 Pulverizer

11. Working The MagMill is a selective dry screening and magnetic separation process that is integrated into the existing coal pulverizers to remove unwanted coal constituents prior to combustion. The MagMill can reduce emissions of mercury and/or sulfur, improve boiler performance by reducing ash components that contribute to slagging and/or erosion, and reduce coal costs by upgrading poor quality coals. Within a pulverizer , coal falls down a central feed pipe onto a rotating table in the bottom portion of the pulverizer . As the table rotates, the coal is slung radially outward and crushed as it passes underneath gigantic steel tires which roll in grooves on the table. Hot air blown from underneath the rotating table enters the grinding chamber through a gap at the outer circumference of the rotating table. This hot air both dries the coal and sweeps the fine particles released in the crushing upward to the classifier at the top of the mill. Oversize particles are returned for additional grinding and the fine particles are blown directly to the burners. 12/24/2018 11

12. Cont… Because of their weight and hardness, the minerals in the feed coal require more passes underneath the rollers than does the relatively soft hydrocarbon component of the coal.  The minerals, therefore, become concentrated on the grinding table. In the MagMill configuration a stream rich in these hard-to-grind minerals such as iron pyrite is withdrawn through the wall of the pulverizer to the magnetic separator. Outside the pulverizer the material is processed through mechanical and magnetic separators to reject the minerals and to recover the carbon which is returned to the mill for grinding to specification. 12/24/2018 12

13. DRY MAGNETIC SEPARATION APPLICATIONS In the removal of tramp iron from process streams. Purification of numerous industrial minerals such as glass sand, fluorspar, feldspar, diamond and others, by removing fine strongly magnetic impurities. 12/24/2018 13

14. DRY MAGNETIC SEPARATION For magnetic separator to be successful, the material should be pletely dry, which sometimes involves an expansive heating stage. For particles smaller than a certain threshold size (for instance 75 µm), the attractive electrostatic and van der Waals forces will cause sticking and the formation of aggregates. Selectivity of separation can thus be severely affected. 12/24/2018 14

15. WET MAGNETIC SEPARATION Wet low intensity drum magnetic separation (LIMS) are used to recover strongly magnetic solids from a slurry feed. 12/24/2018 15

16. WET MAGNETIC SEPARATOR 12/24/2018 16

17. WET MAGNETIC SEPARATION USES: As a magnetic filter to remove a single solid component from a suspension. As a magnetic separator to remove unwanted magnetic component from a mixture of materials For a concentration of valuable weakly magnetic materials from a mixture. 12/24/2018 17

18. MAGNETIC FILTRATION Magnetic filtration is used primarily for the removal of fine particulates from dilute fluid suspensions. Removal is carried out by passing suspensions through a magnetized matrix, which leads to the retention of particles throughout the matrix. The fluid stream may be either liquid or gas. 12/24/2018 18

19. MAGNETIC FILTERATION PROCESS The process of magnetic filtration is analogous to that of deep be filtration, the difference being that an additional external force, namely the magnetic force, contributes to the filtration efficiency in magnetic filtration. The magnitude of the applied magnetic field is dictated by the magnetic susceptibility of the suspended solids . 12/24/2018 19