Physicochem. Probl. Miner. Process.

, 57(5), 2021, 15-22 Physicochemical Problems of Mineral Processing

ISSN 1643-1049
http://www.journalssystem.com/ppmp
© Wroclaw University of Science and Technology

Received April 15, 2021; reviewed; accepted July 06, 2021

Comparison of anionic, cationic and amphoteric collectors used in

pyrite flotation
Gülay Bulut, A.A. Sirkeci, Beril Arı
Mineral Processing Engineering Department, Istanbul Technical University, Istanbul Turkey

Corresponding author: gbulut@itu.edu.tr (G. Bulut)

Abstract: In this study, flotation tests were conducted with purified pyrite and ore samples. The
collectors employed were anionic and cationic type such as potassium ethlyl-amyl xanthate, Tomamine
M73 and Resanol Bal. According to the flotation tests, it was found that pyrite floated at low pH and
depressed at high pH values with xanthates. On the other hand, in the case of cationic collectors which
are Tomamine M73 (alkyl ether amine, an amphoteric surfactant) and Resanol Bal (N-3-tridecyloxy
propyl 1-3 diamine, branched acetate) pyrite floated at high pH values. It was shown that amine type
collectors could be efficient to selectively float pyrite from chalcopyrite at alkali pH ranges in the case
of ore samples.

Keywords: flotation, pyrite, amine, collectors, xanthate

1. Introduction
Pyrite in many cases is a kind of undesired mineral mine yet it is an important input for sulphuric acid
production. Pyrite is often associated with other valuable metal sulphides such as chalcopyrite, galena,
sphalerite, etc. Feasible extraction of those valuable minerals demands selective depression of pyrite
during flotation. Thiol type collectors are almost unique used in the flotation of sulphide ores. When
separating chalcopyrite from pyrite, chalcopyrite is always floated first and then pyrite is enriched in
industrial applications. Short chain xanthates are often employed in chalcopyrite flotation and lime is
used the pH regulator to depress iron sulphides, if required, cyanide may be used as the secondary
depressant.
One of the very important characteristics of pyrite is that at an alkaline pH it is well depressed and
at an acidic pH the floatability improves significantly. Depressants other than lime such as organic
compounds, sulphates and cyanide may be quite effective. Successful pyrite depression is very much
dependent on the ability of the pyrite to oxidize rapidly. As a result of oxidation, iron hydroxide
Fe(OH)3 is formed on the surface of the pyrite, which increases hydration and reduces adsorption of the
collector (Fornasiero and Ralston, 1992; Bulatoviç, 2007; Altun et al., 2010).
Xanthates and dithiophosphates are thiol type collectors having been widely used in sulphide
flotation. Xanthate is the most commonly employed collector in sulphide flotation and it reverses the
positive surface charge of pyrite in acid pH pulps, and gets it more negative at neutral and alkaline pH
range as the xanthate concentration increases (Fuerstenau et al., 1968; Jiang et al., 1998; Bulut et al., 2004;
López Valdivieso et al., 2005; Blondin et al., 2005). It is generally accepted that xanthates render pyrite
hydrophobic adsorbing as dixanthogen and, in the meantime, the loss of positive charge associates with
surface ferric hydroxide formation on the surface resulting in an increase in the negativity of the zeta
potential of pyrite. Some authors have also suggested that various ferric xanthate compounds might
form during pyrite flotation. Xanthate has been proposed to adsorb on pyrite chemically in acidic
condition as a compound of xanthate and dixanthogen.
Amines are cationic surfactants consisting of an organic compound, which constitutes the
hydrophobic part of the collector, and a hydrophilic, polar group based on pentavalent nitrogen (Atak,

DOI: 10.37190/ppmp/140014
16 Physicochem. Probl. Miner. Process., 57(5), 2021, 15-22

2017; Bulatoviç, 2007). The adsorption mechanism of amine type collectors is proposed to be through
columbic forces (Smith and Akhtar, 1976) between the polar group of the collector and the charged
electrical double layer on the mineral surface. In general, the amines are characterized by low selectivity
and mainly used for oxide minerals (Smith and Akhtar, 1976; Filippova et al., 2014) and silicate mineral
(Pearse, 2005; Weng et al., 2013), and not for sulphide minerals. Studies on the flotation of sulphide
minerals with amines started more than 70 years ago [Kellogg et al., 1946). However, because of the
success of thiol type collectors, amines have not been paid much attention. Few studies have been
conducted in order to compare the flotation response of amine and xanthate when used as collectors for
sulphides. A different pH dependency was noted by Sirkeci (2000; a, b) who conducted flotation
experiments on pyrite using HTA (hexyl thioethylamine hydrochloride; i.e. a derivative of a primary
amine). Up to pH 9.3, flotation of pyrite was observed to be poor, almost lacking, while the maximum
flotation recovery was maintained between pH 10.5 and 11.5. Good relationship was found between
flotation recoveries and adsorption measurements as a function of pH, whereas no correlation was
found between surface charge (zeta potential) and flotation behaviour.
A comparative study of the adsorption mechanisms of an amine thioacetate (Armac C) and the well-
known amyl xanthate on pyrite was studied (Kongolo et al., 2004). Armac C gave the best results for
cyanide bearing tailings compared with KAX even after washing and sulphide activation.
Nanthakumar and Kelebek (2007) conducted flotation tests on pyrrhotite using EDTA (ethylene
diamine terraacetic acid), TETA (tri ethylene tetra amine) and KAX at pH 9.2. The results showed that
the flotation of pyrrhotite was improved on using EDTA, compared to KAX and TETA.
In the production of ground calcium carbonate for the paper industry, any colouring contaminants
such as pyrrhotite and pyrite, were removed using flotation method at alkaline pH with the use of amine
collectors (Bunkholt and Kleiv, 2015).
Conventional flotation of pyrite is achieved employing xanthate type collectors at slightly acidic pH
medium. In the selective separation of chalcopyrite from pyrite, chalcopyrite is floated first at very high
alkaline conditions and then pyrite is floated after pH is regulated to acidic pH values. In this study,
amine type collectors were used to eliminate the low pH requirement stage, which causes a lot of acid
consumption.

2. Materials and method

2.1. Materials
In this study a purified pyrite sample and a pyrite containing chalcopyrite ore were used in the tests.
Pyrite samples were collected from open pit Murgul mine and handpicked to obtain the purified
sample. The chalcopyrite bearing ore sample was taken from Siirt-Madenköy deposit, in Turkey.
Chemical analyses of the test samples are given in Table 1 and Table 2.

Table 1. Chemical analysis of the purified pyrite sample

Element %
Fe 45.07
S 51.75
Si 0.18
Cu 0.12
Al 0.11
Ca 0.04
Zn 0.02
Pb 0.03

Table 2. Chemical analysis of the Siirt-Madenköy ore

Element Fe Cu Al Zn Pb SiO2

(%) 40.29 2.95 0.75 0.21 0.03 20.22

17 Physicochem. Probl. Miner. Process., 57(5), 2021, 15-22

According to the mineralogical analyses, the ore sample contains chalcopyrite (CuFeS2) and pyrite
(FeS2) as the major sulphide minerals and to a lesser degree sphalerite (ZnS), galena (PbS), hematite
(Fe2O3), limonite (FeO(OH)·nH2O), calcite (CaCO3) and quartz (SiO2). The chalcopyrite phase was seen
to be locked with cataclastic pyrite structure and to fill in the fractures of pyrite as a matrix material as
well as it showed a colloidal structure within pyrite. Furthermore, chalcopyrite particles between 5 and
70 µm were seen to scatter in gangue minerals (Ceylan et al., 2014).
In this study, the effect of different collectors have been examined, they are;
Potassium amyl xanthate (KAX), potassium ethyl xanthate (KEX) are thiol type conventional
collectors for sulfide flotation.
Resonal Bal; N-3-tridecyloxy propyl-1,3 diamine branched acetate, is a simple diamine with the
formula (CH2)3(NH2)2.
Tomamine M73, alkyl ether amine, is an amphoteric surfactant for use in alkaline and acidic cleaner
circuits (Rodrigues et al., 2013).
Aerophine 3418A is an aqueous solution of sodium diisobutyldithiophosphinate [(C4H9)2PH].
Aerophine 3418A has been widely used in the flotation of copper and lead-sulfide minerals, particularly
they associate in complex sulfide ores containing sphalerite mineralization, and ores with high levels of
pyrite and/or pyrrhotite (Cytec, 2002; Pecina –Trevio et al., 2003).

2.2. Method
Fundamental flotation experiments were carried out in a microflotation cell using 1 g of -105 +44 µm
purified pyrite sample, methyl isobutyl carbinol (MIBC) as a frother and nitrogen gas for bubble
generation. An agate mortar and pestle was used for grinding fresh sample prior to each test. All tests
were conducted using four different collectors at a constant collector concentration of 1 x 10-4 M. The
pH value of the slurry was modified using HCl and NaOH. The floating and non-floating fractions were
dewatered, dried and weighed for assessment. Double distilled water was used in micro flotation tests
and zeta potential measurements, whereas bench flotation tests were conducted with tap water.
Zeta potential of pyrite particles freshly ground below 44 µm was measured using a Zeta- Meter 3.0+
equipment. The electrokinetic potential of pyrite particles was investigated with and without collector
addition at different pH values.
In flotation tests crushed ore was wet ground by ball milling prior to each test. Table 3 presents the
size distribution of the flotation sample.

Table 3. Size distribution of the flotation sample

Size (µm) Weight (%) Cumulative

Passing (%)
+106 0.2 100.0
-106+75 1.8 99.8
-75+53 8.8 98.0
-53+38 17.4 89.2
-38 71.8 71.8
Total 100.0

In the Siirt-Madenköy Copper Plant, Aerophine 3418 A, MIBC, sodium silicate and lime are used as
flotation reagents. Pyrite together with silicates is discharged as tailings. In the bench flotation
experiments test conditions were adopted in accordance with the conditions the plant, i.e., the type of
reagents, pH etc. In the plant operation pyrite is not recovered as a by-product. In this study, the
flotation of pyrite has also been studied comparing various collectors. In the investigation bench scale
flotation tests were carried out to confirm microflotation tests.
The bench scale flotation experiments were performed using a 2.5 litre mechanically agitated
flotation cell. Each experiment was conducted using 500 g of the chalcopyrite ore sample. The slurry
was agitated for 5 mins in the cell while adjusting the pH to the desired level using lime. Following
this initial conditioning stage, the collector Aerophine 3418 A for chalcopyrite was added and additional
18 Physicochem. Probl. Miner. Process., 57(5), 2021, 15-22

5 min conditioning was given. The collector and frother dosages were 50 and 20 g/ton of ore
respectively in the copper flotation circuit where the pH was 12 impeller speed was 1500 rpm.
Following Chalcopyrite pyrite flotation was continued at pH 11. In this stage, four different collectors
were tested adding 150 g/ton of collector dosage. The flowsheet of batch flotation tests is given in Fig.
1.
Ground Ore

Rougher Cu Flotation Cu Concentrate

Pyrite Flotation Pyrite Concentrate

Tailings

Fig. 1. The flowsheet of the batch flotation tests

3. Results and discussion

3.1. Microflotation tests
The flotation behavior of pyrite with different collectors was investigated as a function of pH and the
results are given in Fig. 2. The purified pyrite sample was floated well between pH 3 and 6, with the
highest recovery around pH 4 using xanthate. The decrease in flotation ability below pH 4 with
xanthates may be attributed to the to the rapid decomposition of xanthates (Bulut, 1999; Bulut and Atak,
2002; Bulut et al., 2004). On the other hand, when pH increases above 6, a competition between OH- and
X- ions starts to adsorb on the pyrite surface, therefore, when pH increases, OH- ions accumulate on the
surface of pyrite sample. Thus, pyrite is completely depressed above pH 6 when xanthates are
employed.
In the microflotation experiments, it is seen that the pyrite recoveries have obtained the best values
with the amine type collectors around pH 11, where the recoveries are very low when xanthates are
used. Amines are found in undissociated form at alkaline pH values particularly above pH 10 (see Fig.
4), therefore, the interaction with the surface of pyrite in a flotation done at pH 11 is unlikely to be due
to coulombic forces.

Fig. 2. Flotation experiments of pyrite using different collectors

19 Physicochem. Probl. Miner. Process., 57(5), 2021, 15-22

The result of flotation using Tomamin M73 reflects its amphoteric nature giving two maxima in
acidic and basic pH ranges.

3.2. Zeta potential measurements

Electrophoretic mobility measurements of pyrite were conducted at various pH values in the absence
and presence of collectors. The results of measurements are given in Fig. 3.

Fig. 3. Zeta potential of pyrite with and without collectors

As shown in Fig. 3, results indicated that the isoelectric point (i.e.p.) of pyrite was around pH 6 in
the absence of any collectors whereas the surface charge seems to be altered by the presence of collectors.
The surface charge of pyrite at all pH values is highly negative in the presence of xanthate, however, it
becomes positive at all pH values examined with amine type of collectors. Results showed that the
positively charged pyrite surface in acidic pH region became negatively charged due to the presence of
xanthate. This situation was observed in the pH range 3 to 6, where pyrite was well floated. In some
studies (Fornasiero and Ralston, 1992; Bulut et al., 2004; Fuerstenau and Mishra, 1980), it was reported
that the addition of xanthate ions, especially in the acidic region, shifts the surface charge of pyrite to
negative values. This was explained by the replacement of positively charged iron hydroxide species,
which adsorbed onto negatively charged sulfide sites on the pyrite surface, by uncharged iron
hydroxide-xanthate complexes.
When the zeta potential of pyrite in the existence of Resonal Bal and Tomamine is examined, it was
observed that amines shift the zeta potential curve towards positive, particularly in alkaline pH ranges.
Regarding the flotation of pyrite in alkali conditions the reversal of zeta potential towards positive
values can contribute to the increase in the floability. These results showed that amine-type collectors
may electrostatically adsorb on the surfaces of pyrite in alkali pH ranges. Amines are weak bases
derived from ammonia, so they are present in the pulp as molecular, ionic or dimers species, depending
on the pH (Gao et al., 2015). The amine ionization occurs by protonation and the cationic species RNH3+
predominates at the acid to low alkaline pH range. In the pH range where amine molecular species
predominates (Fig. 4), a non-electrostatic mechanism for collector adsorption on the pyrite surface is
implied. Therefore, the adsorption occurs by a chemical interaction mechanism. The amine molecule
(RNH2) has unshared electron pairs in the nitrogen atom that has a strong ability to complex metals by
means of coordinated covalent bonds (Cartmell and Fowles, 1956). This adsorption mechanism was also
suggested by Freeman et al. (2009), Gao et al. (2015), Oliveira and Baltar (2020).

3.3. Bench scale flotation experiments

Figs. 4, 5, 6 and 7 present the results from bench scale flotation tests of the chalcopyrite-pyrite bearing
ore using different collectors.
20 Physicochem. Probl. Miner. Process., 57(5), 2021, 15-22

Fig. 4. Species distribution diagram for DDA (1x10-4 M) as a function of pH (Liu et al., 2015)

The results of bench scale floatation tests conducted with the ore showed that pyrite best floated
with amine type Tomamine M73 and Resanol Bal collectors. Pyrite recoveries of 71.6 and 76.2% were
obtained with Resanol Bal and Tomamine M73, respectively. On the other hand, comparatively low
recoveries were achieved on using xanthates. The results of bench scale flotation tests were seen to be
compatible with those of micro flotation experiments.
In industrial applications it is a common practice to float pyrite at a slightly acidic pH following
flotation of copper at high pH with xanthates. This study shows that pyrite can be floated using amine
type collectors maintaining the same pH value where copper is floated. Thus, acid consumption will be
prevented and control of the flotation process will be simpler.

Table 4. Effect of KEX on pyrite flotation

Weight Pyrite (%) Cu (%)

Products
(%) Content Recovery Content Recovery
Cu Conc. 11.4 23.70 5.3 14.32 61.0
Pyrite Conc. 7.8 40.03 6.1 6.31 18.4
Tailing 80.8 56.31 88.7 0.68 20.5
Total 100 51.33 100.0 2.67 100.0

Table 5. Effect of KAX on pyrite flotation

Weight Pyrite (%) Cu (%)

Products
(%) Content Recovery Content Recovery
Cu Conc. 9.2 26.40 5.0 16.52 57.3
Pyrite Conc. 9.0 39.46 7.3 9.30 31.6
Tailing 81.8 52.27 87.7 0.36 11.1
Total 100 48.73 100.0 2.65 100.0

Table 6. The results of pyrite flotation with Resanol Bal

Weight Pyrite (%) Cu (%)

Products
(%) Content Recovery Content Recovery
Cu Conc. 11.7 28.52 6.6 14.19 59.7
Pyrite Conc. 65.0 56.01 71.6 1.46 34.1
Tailing 23.3 47.62 21.8 0.74 6.2
Total 100.0 50.84 100.0 2.78 100.0
21 Physicochem. Probl. Miner. Process., 57(5), 2021, 15-22

Table 7. The results of pyrite flotation with Tomamine M73

Weight Pyrite (%) Cu (%)

Products
(%) Content Recovery Content Recovery
Cu Conc. 11.5 28.89 6.7 14.8 61.5
Pyrite Conc. 68.2 55.64 76.2 1.34 33.0
Tailing 20.3 42.02 17.1 0.75 5.5
Total 100.0 49.80 100.0 2.77 100.0

4. Conclusions
In this study, the flotation behaviour of pyrite using xanthates as an anionic collector and amines as an
cationic collector was investigated. As a result of these experimental studies, the following findings
were obtained:
• Micro flotation tests with purified pyrite sample showed that amine type collectors, unlike
xanthates, were effective to float pyrite at alkali pH region.
• Bench flotation studies on the real ore sample showed that amine type collectors floated pyrite at
much higher recoveries compared to xanthates. The results of tests using amines as the collector
showed excellent flotation performance for pyrite at high pH values. In industrial applications,
the use of amine type collectors will provide an advantage over conventional methods,
particularly in the circuits where chalcopyrite and pyrite are recovered as separate products
without the need to reduce the pH for pyrite flotation following alkaline range copper flotation.
Thus, acid consumption and the corrosion caused by the low pH will be reduced the in the
flotation plants.

5. References
ALTUN, E., GÜLER, E. T., AKDEMIR, Ü., 2010. Pyrite Flotation: A review, XIIth International Mineral Processing
Symposium, 6-8 October Cappadocia-Nevşehir, Turkey, Vol.1, 295-303.
ATAK, S., Flotasyon, Cevher Hazırlamada 100 Yıl, 2017. İTÜ Vakfı Yayınları, Istanbul (In Turkish).
BLONDIN, R. M., KONGOLO, M., DONATO, P., BENZAAZOUA, M., BARRES, O., BUSSIERE, B., AUBERTIN,
M., 2005. Pyrite Flotation with Xanthate Under Alkaline Conditions - Application to Environmental Desulfurisation,
Centenary of Flotation Symposium, Brisbane, 6-9, June, pp. 683-691.
BULATOVIC, S. M, 2007. Handbook of Flotation Reagents; Chemistry, Theory, Practice, Canada, Elsevier Science, pp. 5-
18.
BULUT, G., ARSLAN, F., ATAK, S., 2004. Flotation behaviors of pyrites with different chemical compositions. Minerals
and Metallurgical Processing, 21, 86-92.
BULUT, G., 1999. Surface Properties and Flotation Behaviors of Pyrites, Ph.D. thesis, Istanbul Technical University,
Istanbul, ( in Turkish).
BULUT, G., ATAK, S., 2002. Role of dixanthogen on pyrite flotation: solubility, adsorption studies and Eh, FTIR
measurements, Mineral and Metallurgical Processing, SME, May, V.19, No. 2, 81-86.
BUNKHOLT, I., KLEIV, R. A., 2015. Flotation of pyrrhotite and pyrite in saturated CaCO3 solution using a quaternary
amine collector, Minerals Engineering, 70, 55-63.
CARTMELL, E., FOWLES, G. W. A., 1956. Complex compounds. In: Cartmell, E., Fowles, G. A., Valency and molecular
structure. London: Butter Worths Scientific Publications, 184-194.
CEYLAN, A., BULUT, G., GÖKTEPE, F., 2014. Evaluation of Pyrite in a Tailings Dam by Flotation, Journal of Materials
Science and Engineering, B 4 (4), 119-128.
CYTEC, 2002. Mining Chemicals Handbook. Revised Edition.
FILIPPOVO, O. L., SEVEROV, V. V., FILIPPOVA, I. V., 2014. An overview of the beneficiation of iron ores via reverse
cationic flotation, International Journal of Mineral Processing, 127, 62-69.
FORNASIERO, D., RALSTON, J., 1992. Iron hydroxide complexes and their influence on the interaction between ethyl
xanthate and pyrite, Journal of Colloid and Interface Science, 151, 225-235.
22 Physicochem. Probl. Miner. Process., 57(5), 2021, 15-22

FREEMAN, C. L., 2009. Interactions of organic molecules with calcite and magnesite surfaces, The Journal of Physical
Chemistry C,113, 3666-3673.
FUERSTENAU, M. C., KUHN, M.C. D. A. ELGILLANI, D.A. 1968. The role of dixanthogen in xanthate flotation of
pyrite, SME Transaction, pp. 148-156.
FUERSTENAU, D. W., MISHRA, R. K., 1980., On the mechanism of pyrite flotation with xanthate collectors, The
Metallurgical Society, Pennsylvania, pp. 271-278.
GAO, Z., SUN, W., HU, Y., 2015. New insights into the dodecylamine adsorption on scheelite and calcite: an adsorption
model, Minerals Engineering, 79, 54-61.
JIANG, C. L., WANG, X. H., PAREKH, B. K., LEONARD, J. W., 1998. The surface and solution chemistry of pyrite
flotation with xanthate in the presence of iron ions, Colloids and Surfaces A: Physicochemical Engineering Aspects,
136, 51-62.
KELLOGG, H., HERBERT H., H. VISQUEZ-ROSAS, H., 1946. Amine flotation of splelerite, galena ores, Trans. AIMME,
169, 470-504.
KONGOLO, M., BENZAAZOUA, M. M., DONATOA, P., BENOIT, D., DROUETA, B., BARRESA, O., 2004. The
comparison between amine thioacetate and amyl xanthate collector performances for pyrite flotation and its application to
tailings, Mineral Engineering, 17, 505-513.
LIU, A., FAN, A. J. C., FAN, M. Q., 2015. Quantum chemical calculations and molecular dynamics simulations of amine
col lector adsorption on quartz (0 0 1) surface in the aqueous solution. International Journal of Mineral Processing,
134, 1-10.
LÓPEZ VALDIVIESO, A., SÁNCHEZ LÓPEZ AND SONG, S., 2005. On the cathodic reaction coupled with the oxidation
of xanthates at the pyrite/aqueous solution interface, International Journal of Mineral Processing, 77, 154-164.
NANTHAKUMAR, B., KELEBEK, S., 2007. Stagewise analysis of flotation by factorial design approach with an application
to the flotation of oxidized pentlandite and pyrrhotite, International Journal of Mineral Processing, 84, 192-206.
OLIVEIRA, A. C., BALTAR, A. M., 2020. Influence of the pH regulator on the dolomite hydrophobization process, REM,
International Engineering Journal, Vol. 73, online version.
PEARSE, M. J., 2005. An overview of the use of chemical reagents in mineral processing. Mineral Engineering, 18, 139–
149.
PECINA-TREVINO, E. T., URIBE-SALAS, A., NAVA-ALONSO, F., PE ́REZ-GARIBAY, R., 2003. On the sodium-
diisobutyl dithiophosphinate(Aerophine 3418A) interaction with activated andunactivated galena and pyrite,
International Journal of Mineral Processing, 71, 201–217.
RODRIGUES, O. M. S., PERESB, A. E. C., MARTINS, A. H., PEREIRA, C. A., 2013. Kaolinite and hematite flotation
separation using etheramine and ammonium quaternary salts, Minerals Engineering, 40,12-15.
SİRKECİ, A. A., 2000. Electrokinetic properties of pyrite, arsenopyrite and quartz in the absence and presence of cationic
collectors and their flotation behavior, Mineral Engineering, Vol. 13, No:10-11, pp.1037-1048.
SİRKECİ, A. A., 2000. The flotation separation of pyrite from arsenopyrite using hexyl thioethylamine as collector,
International Journal of Mineral Processing, 60, 263–276.
SMITH, R. W. AKHTAR, S., 1976. Cationic Flotation of Oxides and Silicates, vol. 1. Flotation A.M. Gaudin Memorial,
American Chemical Society, Washington, DC.
WENG, X., MEI, G., ZHAO, T., ZHU, Y., 2013. Utilization of novel ester-containing quaternary ammonium surfactant as
cationic collector for iron ore flotation, Separation and Purification Technology, 103, 187-194.