92 XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3
a Handbook that included a chapter entitled “Water
Management and Stewardship in Mining Regions” (Kunz,
2021). In 2022 a book entitled “Dry Mineral Processing”
was published by Springer (Chelgani, 2022) that included
chapters on: 1) grinding, 2) magnetic separation, 3) grav-
ity separation, 4) electrostatic separation, 5) sensor-based
separation, and 6) mixed methods. Most chapters include
a section listing the main applications and producers. With
recent technological advances, hand-sorting as described
by Agricola (1556) and Taggart (1945) remains relevant
today because it can be achieved with sensor-based sorting
instead of by actual people using their hands. An excellent
comprehensive chapter on mineral sorting was prepared
by Klein and Bamber (2019) that describes the hurdles to
adoption, sensor types, applications, commercial opera-
tions, and recovery results for various ore types including
lead-zinc, uranium, nickel, nickel-copper, and gold at 41
installations.
DRY UNIT OPERATIONS
Liberation via dry beneficiation methods may include
crushing by gyratory, jaw, or roll-crushers and/or grinding
with autogenous, semi-autogenous, vertical (a.k.a. tower),
rod, and/or ball mills. Dry separation occurs by using
equipment to exploit the differences in the properties of
the minerals to be separated such as size (screens), appear-
ance or chemical composition (sensor-based), magnetic
susceptibility (magnetic), density (gravity), and electrical
conductivity (electrostatic). The particle size range(s) of the
materials to be separated impacts the separation efficiency
depending on the equipment and whether the separation is
wet or dry, as shown in Figure 2. A similar figure was pub-
lished by Perry (1997) for additional solid-solid separations
categorized according to: 1) size, 2) density (heavy media),
3) size and density, 4) magnetic susceptibility, 5) electrical
conductivity, and 6) surface wettability (Perry, p. 19–19).
Crushing
After mining (drilling, blasting, loading, hauling, dump-
ing), the first step during mineral beneficiation is crushing.
Ore at around 60-inches in diameter is crushed so that it can
be transported by conveyors and through transfer chutes.
Crushing can occur in one or more stages, with each stage
limited to about a 6:1 reduction ratio. Crushing is an inher-
ently dry unit operation as it is conducted with only minor
water addition as necessary for dust control. When the ore
is too wet, e.g., from rained-on stockpiles, it tends to cause
operational upsets by plugging the crusher and subsequent
blinding of downstream dry screening. Ore is crushed
under tensile, compression, impaction, and shearing forces
with equipment includes: jaw (single -or double-toggle),
impact, gyratory, and cone crushers (Bearman, 2019).
Grinding
The primary objective of grinding is to liberate the indi-
vidual valuable mineral grains from the gangue minerals so
that they can then be separated based on the physical and/
or chemical differences between them. Harlowe Hardinge
described the primary factors that determine whether a
material is to be ground wet or dry (Taggart, 1945), most
0
50
100
150
200
250
300
350
400
450
2000 2005 2010 2015 2020 2025
Figure 1. Number of publications per year that included “water management,” mining, and minerals
according to a ScienceDirect.com search on January 2, 2024
№
a Handbook that included a chapter entitled “Water
Management and Stewardship in Mining Regions” (Kunz,
2021). In 2022 a book entitled “Dry Mineral Processing”
was published by Springer (Chelgani, 2022) that included
chapters on: 1) grinding, 2) magnetic separation, 3) grav-
ity separation, 4) electrostatic separation, 5) sensor-based
separation, and 6) mixed methods. Most chapters include
a section listing the main applications and producers. With
recent technological advances, hand-sorting as described
by Agricola (1556) and Taggart (1945) remains relevant
today because it can be achieved with sensor-based sorting
instead of by actual people using their hands. An excellent
comprehensive chapter on mineral sorting was prepared
by Klein and Bamber (2019) that describes the hurdles to
adoption, sensor types, applications, commercial opera-
tions, and recovery results for various ore types including
lead-zinc, uranium, nickel, nickel-copper, and gold at 41
installations.
DRY UNIT OPERATIONS
Liberation via dry beneficiation methods may include
crushing by gyratory, jaw, or roll-crushers and/or grinding
with autogenous, semi-autogenous, vertical (a.k.a. tower),
rod, and/or ball mills. Dry separation occurs by using
equipment to exploit the differences in the properties of
the minerals to be separated such as size (screens), appear-
ance or chemical composition (sensor-based), magnetic
susceptibility (magnetic), density (gravity), and electrical
conductivity (electrostatic). The particle size range(s) of the
materials to be separated impacts the separation efficiency
depending on the equipment and whether the separation is
wet or dry, as shown in Figure 2. A similar figure was pub-
lished by Perry (1997) for additional solid-solid separations
categorized according to: 1) size, 2) density (heavy media),
3) size and density, 4) magnetic susceptibility, 5) electrical
conductivity, and 6) surface wettability (Perry, p. 19–19).
Crushing
After mining (drilling, blasting, loading, hauling, dump-
ing), the first step during mineral beneficiation is crushing.
Ore at around 60-inches in diameter is crushed so that it can
be transported by conveyors and through transfer chutes.
Crushing can occur in one or more stages, with each stage
limited to about a 6:1 reduction ratio. Crushing is an inher-
ently dry unit operation as it is conducted with only minor
water addition as necessary for dust control. When the ore
is too wet, e.g., from rained-on stockpiles, it tends to cause
operational upsets by plugging the crusher and subsequent
blinding of downstream dry screening. Ore is crushed
under tensile, compression, impaction, and shearing forces
with equipment includes: jaw (single -or double-toggle),
impact, gyratory, and cone crushers (Bearman, 2019).
Grinding
The primary objective of grinding is to liberate the indi-
vidual valuable mineral grains from the gangue minerals so
that they can then be separated based on the physical and/
or chemical differences between them. Harlowe Hardinge
described the primary factors that determine whether a
material is to be ground wet or dry (Taggart, 1945), most
0
50
100
150
200
250
300
350
400
450
2000 2005 2010 2015 2020 2025
Figure 1. Number of publications per year that included “water management,” mining, and minerals
according to a ScienceDirect.com search on January 2, 2024
№