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Dry Beneficiation
S. Jayson Ripke
McCarl’s Technical Services, LLC
ABSTRACT: Dry processing is important for the future of mineral processing to reduce water consumption
and improve sustainability. The unit operations used in dry processing include grinding, magnetic, gravity,
electrostatic, screening, drying, and sensor-based separation. This paper focuses on reviewing the current state
of the art in dry beneficiation and includes two specific examples of dry mineral processing techniques which
were able to improve feed rates, grade and recovery: 1) high-tension electrostatic separation used to remove silica
gangue and upgrade hematite concentrate at one iron ore operation in Canada and 2) dry low- and medium-
intensity magnetic drums used in pilot-scale operations in Canada and Peru to reject silica from magnetite and
titano-magnetite concentrates from iron sand.
INTRODUCTION
The two fundamental steps of beneficiation (i.e., mineral
processing) are liberation and separation. Liberation is
achieved by size reduction through blasting and/or com-
minution (crushing and/or grinding) necessary to generate
individual mineral particles. It is the most energy-intensive
stage of mineral processing. Separation of these free mineral
particles can then be achieved by exploiting the physical or
chemical differences between the minerals. Physical differ-
ences include specific gravity, hardness, size, shape, color,
conductivity, magnetic susceptibility, etc. Chemical differ-
ences include surface chemistry (i.e., for froth flotation),
and bulk chemistry such as solubility (i.e., for leaching
and solvent extraction). Beneficiation occurs either with
or without the presence of water. Wet or dry beneficiation
each have their unique advantages and challenges.
The importance of dry beneficiation can be measured by
the increase in related publications over the past 25-years,
as show in Figure 1. Processing one metric ton of copper
ore through a conventional crushing, grinding, and froth
flotation circuit requires 0.81 tons of water per ton of ore in
the southwestern United States (Uhrie, 2024) and as much
as 4 to 5 tons of water and at a mine in Poland (Bleiwas,
2012). This amount could be reduced significantly if more
water could be recovered from the tailings.
Why are dry beneficiation operations relatively scarce
compared to wet? Water often increases grinding and
separation efficiency while minimizing dust generation
although “it depends” applies here as well as being one of
three possible answers to any metallurgical engineering
question. Dry beneficiation lacks adoption and may be
due to several reasons including misperceptions and lack of
awareness (Klein, 2019, p. 763 and Kipp, 1959)
LITERATURE REVIEW
As early as 1556, Agricola described dry mineral separation
even prior to beneficiation as experienced miners would
selectively mine ore instead of waste rock then further use
their vision to hand-sort while mining. Dry mineral pro-
cessing included unit operations such as: 1) crushing with
iron -clad stamps (Agricola, p. 268) in closed-circuit with
dry-sieving in-combination with 2) hand-sorting, 3) dry
grinding with a mill stone, and 4) waterless leaching of gold
with quicksilver (mercury). In 2021, Springer published
Dry Beneficiation
S. Jayson Ripke
McCarl’s Technical Services, LLC
ABSTRACT: Dry processing is important for the future of mineral processing to reduce water consumption
and improve sustainability. The unit operations used in dry processing include grinding, magnetic, gravity,
electrostatic, screening, drying, and sensor-based separation. This paper focuses on reviewing the current state
of the art in dry beneficiation and includes two specific examples of dry mineral processing techniques which
were able to improve feed rates, grade and recovery: 1) high-tension electrostatic separation used to remove silica
gangue and upgrade hematite concentrate at one iron ore operation in Canada and 2) dry low- and medium-
intensity magnetic drums used in pilot-scale operations in Canada and Peru to reject silica from magnetite and
titano-magnetite concentrates from iron sand.
INTRODUCTION
The two fundamental steps of beneficiation (i.e., mineral
processing) are liberation and separation. Liberation is
achieved by size reduction through blasting and/or com-
minution (crushing and/or grinding) necessary to generate
individual mineral particles. It is the most energy-intensive
stage of mineral processing. Separation of these free mineral
particles can then be achieved by exploiting the physical or
chemical differences between the minerals. Physical differ-
ences include specific gravity, hardness, size, shape, color,
conductivity, magnetic susceptibility, etc. Chemical differ-
ences include surface chemistry (i.e., for froth flotation),
and bulk chemistry such as solubility (i.e., for leaching
and solvent extraction). Beneficiation occurs either with
or without the presence of water. Wet or dry beneficiation
each have their unique advantages and challenges.
The importance of dry beneficiation can be measured by
the increase in related publications over the past 25-years,
as show in Figure 1. Processing one metric ton of copper
ore through a conventional crushing, grinding, and froth
flotation circuit requires 0.81 tons of water per ton of ore in
the southwestern United States (Uhrie, 2024) and as much
as 4 to 5 tons of water and at a mine in Poland (Bleiwas,
2012). This amount could be reduced significantly if more
water could be recovered from the tailings.
Why are dry beneficiation operations relatively scarce
compared to wet? Water often increases grinding and
separation efficiency while minimizing dust generation
although “it depends” applies here as well as being one of
three possible answers to any metallurgical engineering
question. Dry beneficiation lacks adoption and may be
due to several reasons including misperceptions and lack of
awareness (Klein, 2019, p. 763 and Kipp, 1959)
LITERATURE REVIEW
As early as 1556, Agricola described dry mineral separation
even prior to beneficiation as experienced miners would
selectively mine ore instead of waste rock then further use
their vision to hand-sort while mining. Dry mineral pro-
cessing included unit operations such as: 1) crushing with
iron -clad stamps (Agricola, p. 268) in closed-circuit with
dry-sieving in-combination with 2) hand-sorting, 3) dry
grinding with a mill stone, and 4) waterless leaching of gold
with quicksilver (mercury). In 2021, Springer published