2295
Performance of Sorghum Flour as a Depressant in
Reverse Cationic Flotation of Iron Ore
Carlos E.D. Mata
Universidade Federal do Mato Grosso (UFMT)
André C. Silva, Elenice M.S. Silva, Paulo P. França Neto
Universidade Federal de Catalão (UFCAT)
ABSTRACT: Batch-scale flotation tests of iron ore were conducted to assess the performance of sorghum flour
as a depressant. The results were compared with tests using the commercially employed corn grits as the standard
depressant. Statistical tools were employed for result analysis. In the initial tests using only corn grits, a flotation
time of 4 minutes was determined for subsequent tests. In the second stage, statistically, tests with sorghum flour
exhibited comparable performance to those with corn grits, achieving iron concentrate content and recovery of
62.00 ± 1.13% and 81.82 ± 2.91%, respectively. In the third stage, it was observed that pH was not a significant
variable within the studied range (9.5, 10.0, and 10.5), while increasing the dosage of sorghum flour up to a
value of 1700 g/tFe enhanced the quality of the generated iron concentrate, reaching values of 63.91 ± 1.56%
and 91.69 ± 4.19% for Fe content and Fe recovery, respectively. The results indicated the potential of sorghum
flour as an alternative depressant in the reverse cationic flotation of iron ore.
Keywords: Sorghum flour, Froth flotation, Depressant, Iron ore, Starch.
INTRODUCTION
Brazil stands as the world’s third-largest producer and
second-largest exporter of iron ore concentrate, a vital raw
material for various industries including basic, infrastruc-
ture, and high-tech sectors. The primary deposits are situ-
ated in the states of Minas Gerais and Pará. Within Minas
Gerais, key iron ore provinces include the Quadrilátero
Ferrífero, Conceição do Mato Dentro, and Nova Aurora
(CAXITO and DIAS, 2018). These regions host itabirites,
rocks characterized by alternating layers rich in iron oxides
and silicate minerals (predominantly quartz) and/or carbon-
ates (KATSUTA et al., 2012). Hematite (Fe2O3), boasting
an iron content of 69.9%, stands out as the most significant
iron-bearing mineral in Brazilian deposits.
Inputs derived from corn starch, such as flour (in
Portuguese called fubá), grits, and conventional starch
(pure), act as depressants in Brazilian flotation plants utiliz-
ing the reverse cationic route for iron ore. Starches comprise
polymers, namely amylose (linear chain) and amylopectin
(branched chain). The depressant effect is primarily attrib-
uted to amylopectin (ARAUJO et al., 2005). Additionally,
zein, a protein found in the endosperm of corn grains, exhib-
its a depressing effect on hematite (PERES and CORREA,
1996). To ensure proper solubilization for enhanced
depressant efficacy, starch must undergo the gelatinization
process, which can be thermal, chemical, or a combination
of both. However, a significant portion of the corn starch
production in Brazil is allocated to the food industry and
Performance of Sorghum Flour as a Depressant in
Reverse Cationic Flotation of Iron Ore
Carlos E.D. Mata
Universidade Federal do Mato Grosso (UFMT)
André C. Silva, Elenice M.S. Silva, Paulo P. França Neto
Universidade Federal de Catalão (UFCAT)
ABSTRACT: Batch-scale flotation tests of iron ore were conducted to assess the performance of sorghum flour
as a depressant. The results were compared with tests using the commercially employed corn grits as the standard
depressant. Statistical tools were employed for result analysis. In the initial tests using only corn grits, a flotation
time of 4 minutes was determined for subsequent tests. In the second stage, statistically, tests with sorghum flour
exhibited comparable performance to those with corn grits, achieving iron concentrate content and recovery of
62.00 ± 1.13% and 81.82 ± 2.91%, respectively. In the third stage, it was observed that pH was not a significant
variable within the studied range (9.5, 10.0, and 10.5), while increasing the dosage of sorghum flour up to a
value of 1700 g/tFe enhanced the quality of the generated iron concentrate, reaching values of 63.91 ± 1.56%
and 91.69 ± 4.19% for Fe content and Fe recovery, respectively. The results indicated the potential of sorghum
flour as an alternative depressant in the reverse cationic flotation of iron ore.
Keywords: Sorghum flour, Froth flotation, Depressant, Iron ore, Starch.
INTRODUCTION
Brazil stands as the world’s third-largest producer and
second-largest exporter of iron ore concentrate, a vital raw
material for various industries including basic, infrastruc-
ture, and high-tech sectors. The primary deposits are situ-
ated in the states of Minas Gerais and Pará. Within Minas
Gerais, key iron ore provinces include the Quadrilátero
Ferrífero, Conceição do Mato Dentro, and Nova Aurora
(CAXITO and DIAS, 2018). These regions host itabirites,
rocks characterized by alternating layers rich in iron oxides
and silicate minerals (predominantly quartz) and/or carbon-
ates (KATSUTA et al., 2012). Hematite (Fe2O3), boasting
an iron content of 69.9%, stands out as the most significant
iron-bearing mineral in Brazilian deposits.
Inputs derived from corn starch, such as flour (in
Portuguese called fubá), grits, and conventional starch
(pure), act as depressants in Brazilian flotation plants utiliz-
ing the reverse cationic route for iron ore. Starches comprise
polymers, namely amylose (linear chain) and amylopectin
(branched chain). The depressant effect is primarily attrib-
uted to amylopectin (ARAUJO et al., 2005). Additionally,
zein, a protein found in the endosperm of corn grains, exhib-
its a depressing effect on hematite (PERES and CORREA,
1996). To ensure proper solubilization for enhanced
depressant efficacy, starch must undergo the gelatinization
process, which can be thermal, chemical, or a combination
of both. However, a significant portion of the corn starch
production in Brazil is allocated to the food industry and
