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Comminution (Size reduction). Mechanical comminution. Outer forces. Special forces. Chemical comminution. Leaching and disssolution . acid. biological . Ways of size reduction . smashing. breaking . attrition . splitting . cutting. crunching . CRUSHING dry, + 50 mm.
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Comminution (Size reduction)
Mechanical comminution Outer forces Special forces
Chemical comminution Leaching and disssolution acid biological
Ways of size reduction smashing breaking attrition splitting cutting crunching
CRUSHING dry, + 50 mm Size reduction GRINDING wet, - 50 mm
Types of intergrowths of minerals regular vein coating oclusion
Indices of comminution I = degree of reduction = D/d L = Degree of liberation = eL Mass of free particles of a given component eL = Mass of a given component in feed
Physicomechanical delineation of particle breaking Noice, heat, etc. Er = En + Ep + Einne Energy of stress formation Energy of surface formation Er = 0.5G2 V/E + S Er = 0.5G2 V/E + S Er - breaking energy G - stress at the moment of breaking V - particle volume S - surface area of particle - surface energy of particle E - Young’s modulus
The Young modulus and surface energy as two principal parameters of comminution. The Young modulus after Lipczyński and co-workers (1984) and www, surface energy after Drzymala (1994)
Empirical delineation of size reduction dEo = - C dd/df(d) Hukki, 1975 dEo - increase of specific (per mass unit) energy of comminution C - constant f(d) - function dependent on particle size dd - change of partcie size or in a simplified version: dEo = - C dd/dn Walker, 1937
Rittinger Bond Kick
Specific solutions of the Waker equation Kick, 1885 n=1 KK ln(D/d) = Eo = Er/m = Er/V d - average size of particles after size reduction, m D - average size of particles before size reduction, m KK - constant - density of particle, Mg/m3 V - volume of particle, m3 m -mass of particle, kg Er - comminution energy, J Eo - specific energy of size reduction, J/kg (Energy of comminution is proportional to the volume of the particle)
Specific solutions of the Waker equation Bond, 1952 n=1.5 Eo = KB (1/d0.5 -1/D0.5) (Energy of size reduction depends on both volume and surface area of particle)
Specific solutions of the Waker equation n =2 Rittinger, 1857 Eo = KR (1/d -1/D) Eo = Er/V That is Er = KR*(Sd - SD) S - surface area of particle (Comminution energy is proportional to the surface area of particles)
Comminution equipment: crushers and mills Selected devices for size reduction.a) crushing rolls, b) tumbling mills, c) pendular mill, d) hammer mill, e) jaw crusher, f) gyratory crusher
http://www.retsch-technology.com/ jaw crusher
Ball mills http://ball-mill.fam.de/english/Products
Ball mills http://ball-mill.fam.de/english/Products
Rod mills http://ball-mill.fam.de/english/Products
Impact hammer mills http://ball-mill.fam.de/english/Products
Impact crushers http://ball-mill.fam.de/english/Products