Magnetic separation

N

S

nadawa

koncentratodpad

Principle of magnetic separation Utilized feature: magnetic

susceptibility

B0 = 0 H

0 – magnetic permeability of vacuum (410–7 V·s/(A·m) = H/m

In vacuum:

H - magnetic field intensity (A/m)

B0 - magnetic induction in vacuum (V·s/m2 = T)

In any medium (e.g. particle):

B = H

B = 0 (H + M) = B0 + 0 M

vacuum imput

particle input

Vector of magnetic induction B in a particle is difefrent from that of in vacuum. Therefore:

= (B – B0)/B0 = ( – 0)/ 0 = 0M/B0

is the volumetric dimensionless magnetic susceptibility

MATERIALS

paramagnetics diamagnetics

+ -

Ways of expressing magnetic susceptibility

volume

(dimensionless)

mass (specific)

(cm3/g)

w= /

molar

(cm3/mol)

M = w M

xH

Hx

HH

x

HHmF z

zy

yx

xwx 0

generally:

xH

HmF xxwx 0

N

S

feed

concentrate tailing

true paramagnetics

ferromagnetics

ferri- and antyferromagnetics

diamagnetics

magnetic field, H

mag

net

isat

ion

, M

0

Classification of materials

M= H

mag

net

ic s

usc

epti

bil

ity

temperature

diamagnetics

antyferromagnetics

paramagneticsferromagnetics

Néel point

Curie point

Influence of temperature

DiamagneticsTable 8.3. Specific magnetic susceptibility of diamagnetic materials

(293 K, after Hopstock, 1985)

Mineraland its chemical formula

– M(10–6 cm3/g) (SI)

Mineraland its chemical formula

– M(10–6 cm3/g) (SI)

Elements

Diamond, C 6,17 Silver, Ag 2,41

Graphite, C 44 Gold, Au 1,79

Sulfur, -S 6,09 Bismuth, Bi 16,8

Copper, Cu 1,08

Sulfides

Sphalerite, ZnS 3,27 Stibnite, Sb2S3 3,17

Molibdenite, MoS2 6,05 Cinnabar, HgS 2,99

Argentite, Ag2S 3,71 Galena, PbS 4,40

Oxides

Water (ice), H2O 9,07 Cuprite, Cu2O 1,76

Corundum, Al2O3 3,80 Zincite, ZnO 4,29

Quartz, SiO2 6,20 Cassiterite, SnO2 2,33

Halogens

Halite, NaCl 6,49 Fluoryt, CaF2 4,51

Sylvite, KCl 6,54

Carbonates

Magnezyt, MgCO3 4,83 Cerusyt, PbCO3 2,88

Kalcyt, CaCO3 4,80

Sulfates

Anhydryt, CaSO4 4,47 Baryt, BaSO4 3,84

Gips, CaSO4·2H2O 5,33 Anglezyt, PbSO4 2,89

Smitsonit, ZnSO4 3,41

Paramagnetics

-true paramagnetics

-antyferromagnetics

-ferrimagnetics

-ferromagnetics

True paramagneticsTable 8.5. Magnetic susceptibility of selected true parmagnetics at room temperature

Paramagnetic Susceptibility, w (SI)

cm3/g*Paramagnetic

Susceptibility, M (SI)cm3/mol**

FeCO3 1000 200·10–6 UO2 29657·10–6

CuSO4·5H2O 76,7·10–6 KMnO4 251,3·10–6

FeSO4 844·10–6 Pt 2537·10–6

NiSO4·7H2O 201·10–6 NiS 2388·10–6

MnO 860·10–6 MoO3 37,7·10–6

CoS 2827·10–6 Al 207,3·10–6

* w after Svoboda (1986/87).** M after CRC (1987).

Antyferromagnetyki

Table 8.6. Selected antyferromagnetics and their Néel point (temperature) N, when they become true paramagnetics havingconstant magnetic susceptibility at a given temp. and obeying the Curie–Weissa equation = C/(T + p))

(after CRC, 1986/87)

Antyferromagnetic M(cgs) N (K) p (K), dla T > N

Hematite, Fe2O3 3586·10–6 (1033 K) 950 2000Bunsenite, NiO – 533–650 ~2000Pirrhotite, FeS* 1074·10–6 (293 K) 613 857

Cr2O3 1960·10–6 (300 K) 318 –Tenorite, CuO 238,6·10–6 (289 K) 230 –

Alabandite, MnS 3850·10–6 (293 K) 165 528Pirolusite, MnO2 2280·10–6 (293 K) 84 –Ilmenite, FeTiO3 68 –Siderite, FeCO3 11300·10–6 (293 K) 57 –

* FeS is a bertolid (non-stoichiometric) compound and its properties depend on composition. FeS1,10 and FeS1,14 is a ferrimagnetic

Ferrimagnetyki

Table 8.7. Magnetic susceptability of ferrimagnetic magnetiteas a function of field intensity

(after Svoboda, 1986/87)

Intensity ofmagnetic field

H, kA/m

Specific (mass)magnetic susceptibility,

w (SI), cm3/g

Magnetite 2 1,40 4 1,65

8 2,7516 2,2524 1,8032 1,5348 1,11

Ferromagnetics

Table 8.8. Selected ferromagnetic materials with significant remanence (Br)and energy product (BH)

Material Br

(Tesla)(BH)max

(kJ·m–3)

Alnico 12 (13,5Ni; 8Al; 24,5Co; 2Nb) 1,20 76,8

PrCo5 1,20 286

NdCo5 1,22 295

Sm(Co0,65Fe0,28Cu0,05Zr0,02)7,7 1,20 264

Fe; 23Cr; 15Co; 3V; 2Ti 1,35 44

a

+H+Hc

B

+Br

-Br

-Hc

-H H

c

c

ba – domeins orientationb – decreasing fieldc – hysteresis

field intensity, H

mag

net

ic in

du

ctio

n, B

Paramagnetyk Podatność

w (SI), cm3/g

Paramagnetyk Podatność

w (SI), cm3/gGetyt, FeOOH 250–380·10–6 malachit, Cu2(OH)2CO3 100–200·10–6

Hausmanit, Mn3O4 500–760·10–6 monacyt, (Ce,La,Dy)PO4 120–250·10–6

Ilmenit, (Fe, Mn)TiO3 200–1500·10–6 syderyt, FeCO3 380–1500·10–6

Limonit, Fe2O3 .H2O 250–760·10–6 wolframit, (MnFe)WO4 380–1200·10–6

S

S S

N

N

N

Magnetic

Feed

N

S

Nonmagnetic

dry separation

drum separator

Feed

Magnetic

permanent magnets

Nonmagnetic

Wet separation (drum separator)

Magnetic separation

Magnetic

N

Nonmagnetic

Feed

S

Semiproduct

Drum with easy and difficult to magnetisediscs (IIIIII)

Induction type separator

Magnetic Nonmagnetic

Semiproduct

Feed

belt type separator

Magnetic

Feed

Nonmagnetic

cross-belt separator

Kriostat

Magnet

Feed

Magnet

MagneticNonmagnetic

Supercoducting

Feed

N S

Cycle I

Filling

WaterCycle II

Magnetic particles

Magnetic particles

Nonmagnetic particles

HGMS, peridical

HGMS, continueous

Feed

Feed

Nonmagnetic

Washing off semiproduct

Separating compartment

Washing off magnetic particles

Magnet coil

Magnet yoke

Fw =Fg sin

Coils

Tray with particles

Isodynamic filed H dH/dx = const.

Fm

Fg

Fm = Fw

mgsin = owm H dH /dx

Ver

tica

l

Horizontal

Magnetic particle

ISD