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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