XXXI International Mineral Processing Congress 2024 Proceedings/Washington, DC/Sep 29–Oct 3 2581
overflow from the hydrocyclone chamber, while coarse
sand and the remaining phosphate particles settle at the
bottom. This separation paves the way for the subsequent
flotation process(Beavers et al., 2013 Duan et al., 2021
Pittman, 1990).
Since the 1940s, the “Crago” process has been a sta-
ple in the Florida phosphate industry for fine-size fraction
flotation, maintaining a remarkably consistent processing
flowsheet(Crago, 1950 Guan, 2009). This well-established
flotation method conditions phosphate feed with a fatty
acid as the primary collector, supplemented by fuel oil or
diesel as a secondary collector, within a pH range of 9.0 to
9.3. pH modification is achieved using soda ash or ammo-
nia. Fuel oil or diesel serves as a booster of tall oil fatty acid
collectors, causing phosphate surfaces more hydrophobic.
In addition, fuel oil or diesel has a significant role on con-
trolling foam to a proper level for flotation. The resultant
rough concentrate from the fine flotation circuit comprises
both phosphate and a fraction of fine quartz particles. To
obtain the final phosphate concentrate, an additional step
of amine flotation is indispensable to separate quartz par-
ticles from phosphate. Successful amine flotation necessi-
tates the removal of fatty acid adsorbed on the phosphate
particle surfaces, accomplished through scrubbing with sul-
furic acid. However, the environmental concerns associated
with the use of fuel oil or diesel in the current process are
significant, stemming from their non-biodegradability and
potential inclusion of aromatic hydrocarbons, such as ben-
zene, toluene, ethylbenzene, and xylene, along with other
hazards(Davidson et al., 2021). Moreover, the existing pro-
cess relies on pH control, introducing handling challenges
and complicating overall operations. The pH modifiers like
caustic and ammonia, employed for pH adjustment, pose
risks to both human health and the environment(Usman
et al., 2023).
In response to the aforementioned challenges, exten-
sive efforts have been dedicated to exploring alternative
flotation reagents, especially collectors(Fan et al., 2023
Gao et al., 2021). A range of collector types, includ-
ing phosphoric ester(Baudet and Save, 1999), hydroxa-
mate and its derivatives(Assis et al., 1996 Nettour et
al., 2019 Yu et al., 2016a Yu et al., 2016b), sarcosinate
&sulfosuccinamate(Pinto et al., 1991), and modi-
fied fatty acids(Alsafasfeh and Alagha, 2017 Filippova
et al., 2018 Zou et al., 2021), have been meticulously
investigated(Usman et al., 2023 Yang et al., 2021).
Unfortunately, none of these alternatives has yielded entirely
satisfactory results. For instance, phosphoric esters exhib-
ited effectiveness in carbonate flotation from phosphate
particles in sedimentary ores but required an acidic pH,
employing sulfuric acid or fluorosilicic acid as a phosphate
depressant(Baudet and Save, 1999). Sulfosuccinate and sul-
fosuccinamate demonstrated accelerated flotation of apatite
minerals compared to sodium oleate, albeit within a lim-
ited size range(Pinto et al., 1991). Hydroxamates displayed
notable flotation efficiency, but their selectivity depended
on mineral solubility and the stability constant of the
complex formed with the hydroxamate ion and the cation
within the mineral lattice(Wang et al., 2006). In exploring
alternative raw materials, vegetable oils such as rice bran,
hydrogenated soybean, cottonseed, and jojoba oils emerged
as promising and cost-effective sources of fatty acids(Ruan
et al., 2019). However, their flotation intensities typically
fell short of achieving satisfactory selectivity. Additionally,
promising reports indicate that the utilization of fuel oil/
diesel can potentially be reduced by up to 50% through
the incorporation of a nonionic polymer(SnoW and Miller,
2004). It is essential to note that this advancement is still in
the laboratory development stage, highlighting the ongoing
quest for environmentally friendly and economically viable
alternatives in the field of phosphate flotation.
In recent years, Arkema-ArrMaz has spearheaded the
development of novel reagents meticulously tailored for
application in the rougher phosphate flotation circuit. The
primary objective of these innovative reagent schemes is to
curtail or entirely eliminate the need for pH modifiers and
diesel (or fuel oil) in the flotation process. This strategic
development holds the promise of streamlining the entire
flotation process while simultaneously presenting a more
environmentally friendly alternative to traditional meth-
ods. A comprehensive case study is presented in this paper,
highlighting the successful application of the newly devised
reagent schemes for phosphate flotation. It is noteworthy
that, in accordance with the client’s request to maintain
confidentiality, specific names of the mine site and compa-
nies involved are deliberately omitted in this publication.
Nonetheless, the case study serves as a tangible illustration
of the practical implementation and efficacy of these cut-
ting-edge reagents in a real-world phosphate beneficiation
scenario.
MATERIALS &METHODS
Phosphate Samples
Phosphate feed samples utilized in the test work were
extracted from the underflow of the sizing cyclone just
before entering the conditioning tank at the phosphate
processing plants of our client in Florida, US. Upon recep-
tion, the feed underwent a decantation process to eliminate
excess water, followed by meticulous mixing. The feed was
in a size range of –28+150 mesh, and it contained ~15.6%
overflow from the hydrocyclone chamber, while coarse
sand and the remaining phosphate particles settle at the
bottom. This separation paves the way for the subsequent
flotation process(Beavers et al., 2013 Duan et al., 2021
Pittman, 1990).
Since the 1940s, the “Crago” process has been a sta-
ple in the Florida phosphate industry for fine-size fraction
flotation, maintaining a remarkably consistent processing
flowsheet(Crago, 1950 Guan, 2009). This well-established
flotation method conditions phosphate feed with a fatty
acid as the primary collector, supplemented by fuel oil or
diesel as a secondary collector, within a pH range of 9.0 to
9.3. pH modification is achieved using soda ash or ammo-
nia. Fuel oil or diesel serves as a booster of tall oil fatty acid
collectors, causing phosphate surfaces more hydrophobic.
In addition, fuel oil or diesel has a significant role on con-
trolling foam to a proper level for flotation. The resultant
rough concentrate from the fine flotation circuit comprises
both phosphate and a fraction of fine quartz particles. To
obtain the final phosphate concentrate, an additional step
of amine flotation is indispensable to separate quartz par-
ticles from phosphate. Successful amine flotation necessi-
tates the removal of fatty acid adsorbed on the phosphate
particle surfaces, accomplished through scrubbing with sul-
furic acid. However, the environmental concerns associated
with the use of fuel oil or diesel in the current process are
significant, stemming from their non-biodegradability and
potential inclusion of aromatic hydrocarbons, such as ben-
zene, toluene, ethylbenzene, and xylene, along with other
hazards(Davidson et al., 2021). Moreover, the existing pro-
cess relies on pH control, introducing handling challenges
and complicating overall operations. The pH modifiers like
caustic and ammonia, employed for pH adjustment, pose
risks to both human health and the environment(Usman
et al., 2023).
In response to the aforementioned challenges, exten-
sive efforts have been dedicated to exploring alternative
flotation reagents, especially collectors(Fan et al., 2023
Gao et al., 2021). A range of collector types, includ-
ing phosphoric ester(Baudet and Save, 1999), hydroxa-
mate and its derivatives(Assis et al., 1996 Nettour et
al., 2019 Yu et al., 2016a Yu et al., 2016b), sarcosinate
&sulfosuccinamate(Pinto et al., 1991), and modi-
fied fatty acids(Alsafasfeh and Alagha, 2017 Filippova
et al., 2018 Zou et al., 2021), have been meticulously
investigated(Usman et al., 2023 Yang et al., 2021).
Unfortunately, none of these alternatives has yielded entirely
satisfactory results. For instance, phosphoric esters exhib-
ited effectiveness in carbonate flotation from phosphate
particles in sedimentary ores but required an acidic pH,
employing sulfuric acid or fluorosilicic acid as a phosphate
depressant(Baudet and Save, 1999). Sulfosuccinate and sul-
fosuccinamate demonstrated accelerated flotation of apatite
minerals compared to sodium oleate, albeit within a lim-
ited size range(Pinto et al., 1991). Hydroxamates displayed
notable flotation efficiency, but their selectivity depended
on mineral solubility and the stability constant of the
complex formed with the hydroxamate ion and the cation
within the mineral lattice(Wang et al., 2006). In exploring
alternative raw materials, vegetable oils such as rice bran,
hydrogenated soybean, cottonseed, and jojoba oils emerged
as promising and cost-effective sources of fatty acids(Ruan
et al., 2019). However, their flotation intensities typically
fell short of achieving satisfactory selectivity. Additionally,
promising reports indicate that the utilization of fuel oil/
diesel can potentially be reduced by up to 50% through
the incorporation of a nonionic polymer(SnoW and Miller,
2004). It is essential to note that this advancement is still in
the laboratory development stage, highlighting the ongoing
quest for environmentally friendly and economically viable
alternatives in the field of phosphate flotation.
In recent years, Arkema-ArrMaz has spearheaded the
development of novel reagents meticulously tailored for
application in the rougher phosphate flotation circuit. The
primary objective of these innovative reagent schemes is to
curtail or entirely eliminate the need for pH modifiers and
diesel (or fuel oil) in the flotation process. This strategic
development holds the promise of streamlining the entire
flotation process while simultaneously presenting a more
environmentally friendly alternative to traditional meth-
ods. A comprehensive case study is presented in this paper,
highlighting the successful application of the newly devised
reagent schemes for phosphate flotation. It is noteworthy
that, in accordance with the client’s request to maintain
confidentiality, specific names of the mine site and compa-
nies involved are deliberately omitted in this publication.
Nonetheless, the case study serves as a tangible illustration
of the practical implementation and efficacy of these cut-
ting-edge reagents in a real-world phosphate beneficiation
scenario.
MATERIALS &METHODS
Phosphate Samples
Phosphate feed samples utilized in the test work were
extracted from the underflow of the sizing cyclone just
before entering the conditioning tank at the phosphate
processing plants of our client in Florida, US. Upon recep-
tion, the feed underwent a decantation process to eliminate
excess water, followed by meticulous mixing. The feed was
in a size range of –28+150 mesh, and it contained ~15.6%