Azo Derivatives of Pyrocatechol, Resorcinol, and Salicylic Acid as Collectors for Sulfide Ore Flotation

Article abstract of DOI:10.1134/S1070427219120150

Heterocyclic and aromatic azo derivatives of pyrocatechol, resorcinol, and salicylic acid have been investigated as collectors for the flotation of sulfide ores. The acid-base properties of the compounds were studied, their solubility in an alkaline solution was determined. It was established that the fixing of reagents on the surface of the ore occurs mainly by the chemical mechanism. Adsorption constants were calculated. It was found that most of the studied reagents exhibit collective properties with respect to sulfide copper—nickel ore. The use of mixtures of azo compounds with potassium butyl xanthogenate leads to an increase in the degree of extraction of nickel and copper, as well as the quality of the concentrates, in comparison with one butyl xanthogenate.

Full text of DOI:10.1134/S1070427219120150

ISSN 1070-4272, Russian Journal of Applied Chemistry, 2019, Vol. 92, No. 12, pp. 1734−1744. © Pleiades Publishing, Ltd., 2019.
Russian Text © The Author(s), 2019, published in Zhurnal Prikladnoi Khimii, 2019, Vol. 92, No. 12, pp. 1598−1609.
VARIOUS TECHNOLOGICAL
PROCESSES
Azo Derivatives of Pyrocatechol, Resorcinol,
and Salicylic Acid as Collectors
for Sulfide Ore Flotation
V. Yu. Guseva,*, E. V. Baigachevaa, and V. O. Gogolishvilia
a Institute of Technical Chemistry, Perm, 614013 Russia
*e-mail: gusevvyu53@mail.ru
Received March 1, 2019; revised September 16, 2019; accepted September 16, 2019
Abstract—Heterocyclic and aromatic azo derivatives of pyrocatechol, resorcinol, and salicylic acid have been
investigated as collectors for the flotation of sulfide ores. The acid-base properties of the compounds were studied,
their solubility in an alkaline solution was determined. It was established that the fixing of reagents on the surface
of the ore occurs mainly by the chemical mechanism. Adsorption constants were calculated. It was found that most
of the studied reagents exhibit collective properties with respect to sulfide copper–nickel ore. The use of mixtures
of azo compounds with potassium butyl xanthogenate leads to an increase in the degree of extraction of nickel and
copper, as well as the quality of the concentrates, in comparison with one butyl xanthogenate.
Keywords: azo derivatives of pyrocatechol, resorcinol, and salicylic acid; sulfide ores; flotation
DOI: 10.1134/S1070427219120150
Flotationisoneofthemaintechnologicalprocessesof
theorebeneficiation.Thedepletionofdepositsrichinraw
materials and the involvement of poorer ores with a poor
composition and similar technological characteristics of
minerals in the processing require developing ways to
increase its efficiency. One of the possible approaches to
solving this problem is the use of new flotation reagents,
in particular reagent-collectors. Xanthogenates and
several types of dialkyldithiophosphates (aeroflot
reagents) and their mixtures with various collectors
are used as the main types of collectors for flotation of
sulfide ores [1–4]. Dialkyldithiophosphates and their
modifications are more selective than xanthates and
provide high-quality concentrates of non-ferrous, rare
and precious metals. For selective flotation of sulfides
of copper–zinc ores, a phenylpyrazole-type collector,
1-phenyl-2,3-dimethyl-4-dimethylaminopyrazolone-5,
is recommended [5]. Collectors for flotation of sulfide
copper–molybdenum and copper–nickel ores based
on aliphatic acid hydrazides pronounced collective
properties and selectivity for non-ferrous metal sulfide
minerals, provide a higher yield of target metals in
comparison with potassium butyl xanthogenate, are less
toxic and stable during long-term storage [6]. Of recent
developments, new carbamate class collectors should
be noted for the selective separation of chalcopyrite
from galena and arsenopyrite [7, 8]. It was found that
the degrees of extraction of chalcopyrite and galena by
O-isopropyl-N-ethylthiocarbamate differ with about
20%. In [9, 10], the reagents of the thioamide class were
studied. They showed good selectivity for chalcopyrite
and are proposed as collectors for its separation
from pyrite and galena. The authors investigated
1-hydroxyethylidene-1,1-diphosphonic acid used in
water treatment as a collector [11]. It was found that
the reagent has better selectivity for chalcopyrite in
comparison with ethylxanthogenate and is considered
as its potential substitute.
Potassium butyl xanthogenate (PBX), which is the
main type of collector for sulfide ores in our country,
in addition to low selectivity, which complicates the
technological schemes and losses of metals in numerous
operations of cleaning concentrates, is unstable during
long-term storage and decomposes with the release of
toxic carbon disulfide. Therefore, an important task is the
development of more selective and less toxic collectors.
1734

AZO DERIVATIVES OF PYROCATECHOL, RESORCINOL, AND SALICYLIC ACID
1735
Azo compounds are one of the classes of reagents that
have shown collective properties.Azo compounds are low
toxic; they are the most numerous class of synthetic dyes.
They are sustainable, their production technology has
proven itself in the industry. Given these circumstances,
it was of interest to study these compounds as collectors
for flotation of sulfide ores. However, there is only a few
information about their use as collectors for flotation.
Handbook1 lists several aromatic azo compounds used
for flotation of oxidized non-ferrous metals ores. The
authors of [12] studied aromatic and heterocyclic azo
derivatives of phenol and 1-naphthol. It was established
that they have high flotation properties in relation to
sulfide copper–nickel ores. In a number of cases, a
higher degree of enrichment and extraction of metals
was achieved compared to PBX. The use of a mixture of
azo compounds with PBX (1 : 1) significantly improves
flotation performance. Their adsorption on the surface of
the ore occurs due to physical interaction.
an acidic medium and its subsequent azo coupling with a
hydroxyl-containing aromatic compound. Since pyrocat-
echol is easily oxidized by diazocompounds, to obtain its
azo derivatives a method, which consisted in azo coupling
with its Al salt was used. Applied in the form of a cyclic
Al salt, pyrocatechol reacts well with diazo compounds in
an acidic mmedium.At the same time, the oxidizing effect
of diazocompounds is suppressed. After the reaction, the
Al salt is decomposed by excess acid with the release of
azo dye [17]. Using this method, all the pyrocatechol azo
derivatives were synthesized. The resulting compounds
and their designations are given in Table 1.
The individuality and purity of the reagents are
confirmed by 1H NMR, IR spectroscopy, and thin layer
chromatography.
IR spectra were recorded on a Vertex80V Fourier
spectrometer (Bruker, Germany), 1H NMR spectra were
recorded on an Avance Neo 400 spectrometer (Bruker,
Germany) in DMSO-d6 and CDCl3. Protolytic equilibria,
solubility, and complexation of the studied compounds
with Ni(II) and Cu(II) were studied by spectrophotometric
method.2 Electronic spectra and optical density were
recorded on an SP-2000 spectrophotometer (OKB Spectr,
Russia), and pH values of solutions were recorded on an
I-160M ionomer (ANTEKh, Belarus) with glass indicator
and silver cloride reference electrodes.
According to modern concepts, the fixation of
reagents on the surface of the ore is considered as the
formation of coordination compounds [13]. This allows
application of existing patterns of interaction of reagents
with metal cations in solution to predict their interaction
with minerals containing the same cations. Therefore,
for further studies, azo compounds containing several
functional groups with a mobile hydrogen atom, in
particular, OH and COOH groups, were of interest in
the azo component. Such compounds form complexes
with transition metal ions in solution [14–16]. It could
be assumed that they will also form complexes with the
ions of these metals located on the surface of the ore.
Changing the mechanism of fixing reagents from physical
to chemical can affect their flotation properties.
The measurement of surface tension at the interface
between an aqueous solution of a reagent and air was
studied by the stalagmometric method. Solutions of
0.1 M KOH were used as the standard liquid, since these
compounds are poorly soluble in water. A study of the
adsorption of compounds was carried out by shaking a
sample of ore (0.5000 g) in a shaker-incubator KS 4000 i
control (IKA, Germany) with an alkaline solution of azo
compounds.After reaching equilibrium (the time to reach
adsorption equilibrium was 3–5 min with a flask shaking
frequency of 500 min–1), an aliquot was taken from the
solution, filtered, and the residual reagent content was
determined photometrically using a calibration curve.
The desorption study was carried out with the same ore
sample. An alkali solution of the same concentration
containing no reagent was added to the flask. Its volume
was equal to the volume of an aliquot taken to determine
the adsorption. Thus, a solution of a reagent of a lower
concentration was obtained in the flask, into which part
The aim of the work was to establish the effect of an
azo component containing two functional groups (COOH
and OH) on the physicochemical and flotation properties
of azo compounds. The studies were carried out with
heterocyclic and aromatic azo derivatives of pyrocatechol,
resorcinol, and salicylic acid.
EXPERIMENTAL
Reagents were synthesized by preparing a diazosalt by
reacting the corresponding amine with sodium nitrite in
––––––––––––––
––––––––––––––
1 Shubov, L.Ya., Ivankov, S.I., Shcheglova, N.K., Flotation Reagents in
the Processes of Mineral Processing. Handbook, Kondratieva, L.V.,
Ed., Moscow: Nedra, 1990, p. 136.
2 Bernshtein, I.Ya. and Kaminskii, Yu.L., Spektrofotometricheskii
analiz v organicheskoi khimii (Spectrophotometric Analysis in
Organic Chemistry), Leningrad: Chemistry, 2010, pp. 130–170.
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GUSEV et al.
Table 1. Investigated reagents
Reagent
Formula
Signification
4-(Phenylazo)pyrocatechol
PAP
4-(2-Thiazolylazo)pyrocatechol
4-(2-Benzthiazolylazo)pyrocatechol
ТАP
BeTAP
5-(Phenylazo)salicylic acid
PАSA
5-(o-Tolylazo)salicylic acid
5-(2-Benzthiazolylazo)salicylic acid
TolASA
BеТASA
4-(Phenylazo)resorcinol
PAR
4-(o-Tolylazo)resorcinol
TolAR
4-(1-Naphthylazo)resorcinol
NAR
4-(2-Benzthiazolylazo)resorcinol
BeТАR
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AZO DERIVATIVES OF PYROCATECHOL, RESORCINOL, AND SALICYLIC ACID
Table 2. Reagent solubility in 0.1 M NaOH
1737
5-(Phenyl- 5-(o-Tolyl- 5-(2-Ben- 4-(Phenyl- 4-(2-Thiazol- 4-(2-Benz-
4-(Phenyl- 4-(1-Naphth- 4-(o-Tolyl-
azo)- ylazo)- azo)-
resorcinol resorcinol resorcinol
azo)-
salicylic salicylic lylazo)sali-
acid acid
azo)-
zthiazo-
azo)-
pyro-
ylazo)-
pyro-
catechol
thiazolyl-
azo)pyro-
catechol
Reagent
cylic acid catechol
Solubility, 8.64 × 10–2 7.17 × 10–2 9.14 × 10–2 8.78 × 10–2 6.98 × 10–2 2.74 × 10–2 1.76 × 10–2 3.54 × 10–2 1.25 × 10–2
M (g L–1) (18.51)
(18.95) (20.87) (21.26) (17.89) (7.76) (3.78) (7.83) (3.39)
Table 3. Acid-base properties of compounds
4-(Phenylazo)-
resorcinol
5-(Phenylazo)-
salicylic acid
5-(2-Benzthiazolylazo)- 4-(2-Thiazolylazo)- 4-(2-Benzthiazolylazo)-
Reagent
salicylic acid
pyrocatechol
pyrocatechol
a
pKa1
6.38 ± 0.03
2.41 ± 0.08
3.94 ± 0.09
10.32 ± 0.07
7.12 ± 0.08
7.23 ± 0.07
12.40 ± 0.05
a
pKa2
12.10 ± 0.08
11.85 ± 0.05
11.23 ± 0.09
a P = 0.95, n = 4–5.
of the reagent from ore was transferred to establish a new
equilibrium, if it was fixed on it by a physical mechanism.
In the case of a chemical fixing mechanism, the reagent
remained on the ore.After shaking, its content in the solu-
tion was determined by a similar technique. Determina-
tion of the adsorption of azo compounds was carried out
with the same samples of ore at each experimental point.
The following reagents were used in the work:
2-aminobenzothiazole (97%), 2-aminothiazole (97%),
1-naphthylamine of analytical pure grade, o-toluidine
(1-methylaniline) of reagent purity, aniline 99.8%, resor-
cinol 99%, salicylic acid of reagent purity, pyrocatechol
of reagent purity, NaNO2, KOH, NaOH, Na2CO3, HCl,
H2SO4 of highest grade, CuSO4‧5H2O, CoSO4‧7H2O,
NiSO4‧7H2O of analytical pure grade.
The flotation activity of the reagents was studied on
sulfide copper–nickel ore with a Cu content of 0.210%,
Ni 0.390%, Co 0.014%, and fineness of about 3 mm. An
ore sample together with soda taken from the calculation
of 3 kg ton–1 was ground in a ball mill to a fraction of the
class –0.063 mm (the content of this fraction is not less
than 75%). Flotation was carried out in a 237FLlaboratory
flotation machine (chamber volume 0.5 L, impeller rotation
speed 2760 rpm; Mechanobr-Technika, St. Petersburg)
according to the collective scheme, which included the
main (10 min) and control (15 min) flotations. Sodium
butyl aeroflot reagent was used as a foaming agent, and
the studied azo compounds or their mixtures with PBX
were used as collectors. The collector was introduced as
a 1% solution in 0.1 M KOH. The products obtained after
the experiments were dried, weighed, and abraded. After
that, samples were taken for analysis. The samples were
decomposed by dissolving them in a HCl : HNO3 mixture
(3 : 1) in a MARS 6 microwave oven (CEMCorporation,
USA). The content of copper, nickel, cobalt was determined
by atomic absorption spectroscopy on an iCE 3500 spec-
trometer (ThermoScientific, USA) with flame atomization.
The results were compared with the enrichment indices
obtained when using one PBX as a collector.
RESULTS AND DISCUSSION
The solubility of the compounds in alkaline solutions
was sufficient for the preparation of solutions of the
required concentration used in flotation (Table 2). The
constants of acid dissociation of azo compounds (Table 3)
were determined in aqueous solutions by adding to them
a minimal aliquot of the reagent in alcohol. The obtained
values of pKa1 were in the range 2.41–7.23, pKa2,
10.32–12.40. Thus, under flotation conditions occurring
in aqueous solutions at pH ~ 10, all reagents are in a single
ionized form. It should also be noted that additives of the
studied compounds practically do not reduce the surface
tension of the alkali solution (Table 4).
The absorption spectra of aqueous solutions of TAP
(Fig. 1a, 1) and PASA (Fig. 1b, 1) and their mixtures
with Ni(II) (Fig. 1a, 2) and Cu(II) (Fig. 1a, 2) do not
coincide. The spectra of mixtures are characterized by
a shift in the light absorption maxima relative to the
spectra of the reactants, which indicates the chemical
interaction proceeding in them. Thus, the azo derivatives
of pyrocatechol and salicylic acid form complexes with
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GUSEV et al.
Table 4. Surface tension σ of 0.1 M KОН solutions in the
presence of the reagents and without them at T = 20°C
metal cations in an aqueous solution, and it could be
expected that chemisorption will be observed for these
compounds.
Reagent (R)
cR, M
σ, J m–2
To determine the nature of the interaction of the
reactants with the ore surface, their adsorption and
desorption were studied. Since the adsorption process
is reversible during physical interaction, the degree of
absorption of the reagent depends on its concentration in
the solution, regardless of how it was obtained–by moving
from low to higher concentrations or vice versa. In this
case, the adsorption and desorption isotherms coincide.
In the case of chemisorption, when a surface compound
is formed due to the reagent–metal bond, the adsorption
process is not reversible, the adsorbed substance remains
on the surface of the ore, and the isotherms will not
4-(Phenylazo)pyrocatechol
0
75.72
66.81
73.26
1.5 × 10–2
1.2 × 10–3
5-(Phenylazo)salicylic acid
0
75.72
72.59
74.65
2.3 × 10–2
1.8 × 10–3
4-(2-Benzthiazolylazo)-
pyrocatechol
0
75.72
74.80
76.65
1.1 × 10–2
9.1 × 10–4
A
(a)
(a)
λ, nm
(b)
A
cres × 105, M
(b)
λ, nm
cres × 105, M
Fig. 1. Spectra of solutions of (a, 1) 4-(2-thiazolylazo)
pyrocatechol (R1) and (b, 1) 5-(phenylazo)salicylic acid (R2),
and their mixtures with (а, 2) Ni(II) and (b, 2) Cu(II). l =
1 cm; (а) [R1]in = [Ni(II)]in = 3 × 10–5 M, pH 8.6; (b) [R2]in =
[Cu(II)]in = 5 × 10–5 M, pH 10.1.
Fig. 2. Adsorption (1) and desorption (2) isotherms of
(а)4-(2-thiazolylazo)pyrocatecholand(b)4-(2-benzthiazolylazo)
pyrocatechol.
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AZO DERIVATIVES OF PYROCATECHOL, RESORCINOL, AND SALICYLIC ACID
1739
(a)
(b)
cres × 105, M
cres × 105, M
(c)
cres × 105, M
Fig. 3. Adsorption (1) and desorption (2) isotherms of (а) 5-(phenylazo)salicylic acid, (b) 5-(o-tolylazo)salicylic acid, and
(c) 5-(2-benzthiazolylazo)salicylic acid.
(a)
(b)
cres × 105, M
cres × 105, M
Fig. 4. Adsorption (1) and desorption (2) isotherms (a) 4-(o-tolylazo)resorcinol and (b) 4-(1-naphthylazo)resorcinol.
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GUSEV et al.
Table 5. The parameters of the Langmuir isotherms (k1, a), Henry (k2), the values of the Langmuir adsorption constants (KL),
Henry (KH) and the limiting adsorption (A∞)
k1 × 105
a
1
A∞, mol g–1
KL, M–1
KH, L g–1
1
Reagent
k2 (k2 = KH)
(
k1
)
(a =
)
A
KLA
4-(o-Tolylazo)resorcinol
–
–
0.0057
–
–
0.0057
0.0252
0.0076
0.0051
0.0527
0.0182
0.0699
4-(1-Naphthylazo)resorcinol
5-(Phenylazo)salicylic acid
14.748
21.698
–
39.724
131.420
–
–
6.78 × 10–7
4.61 × 10–7
–
3.71 × 104
1.65 × 104
–
–
0.0051
–
5-(o-Tolylazo)salicylic acid
5-(2-Benzthiazolylazo)salicylic acid
4-(2-Thiazolylazo)pyrocatechol
4-(2-Benzthiazolylazo)pyrocatechol
6.525
–
18.981
–
1.53 × 10–6
–
3.44 × 104
–
0.0182
–
3.349
14.297
2.99 × 10–6
2.34 × 104
coincide. The adsorption and desorption isotherms
of TAP, BeTAP, TolASA, BeTASA, TolAR, NAR do
not coincide (Figs. 2–4). Thus, the adsorption of these
compounds has a chemical nature, which is due to the
presence in their structure of OH and COOH groups
capable of reacting with metal cations located on the
surface of the ore. In PASA, the adsorption and desorption
isotherms coincide. In this case, physical adsorption
takes place.
it possible to apply the Langmuir theory and calculate
the limiting adsorption (A∞) and the adsorption constant
(KL). Adsorption of TAP, TolASA, and TolAR is not
described by a linear isotherm in Langmuir coordinates.
At low concentrations, the amount of adsorbed reagent is
proportional to its concentration; therefore, the calculation
of the adsorption constants in this case can be performed
using the Henry equation for the adsorption isotherm.
For these compounds, the linear dependences of their
adsorption on the residual concentration were obtained
(Fig. 6), which allows calculating the values of the Henry
and Langmuir adsorption constants (Table 5).
For the reagents PASA, NAR, BeTASA, and BeTAP
the linear dependences of the adsorption isotherms in the
Langmuir coordinates were obtained (Fig. 5). This makes
Adsorption decreases in the series of BeTAP >
BeTASA > NAR > TAP > PASA > TolAR > TolASA
compounds. Obviously, the degree of adsorption is
determined primarily by the presence of aromatic and
heterocyclic rings in the diazocomponent. In the first four
compounds, it is much higher. BeTAP and BetASA are
adsorbed significantly better than TAPdue to the presence
of an additional benzene ring in their molecules. NAR
occupies an intermediate position. Compounds having an
aromatic and heterocyclic ring in the diazocomponent are
adsorbed better than a compound having two aromatic
rings, and it, in turn, is adsorbed better than a compound
having one heterocyclic ring.
Table 6 shows the flotation results of sulfide copper-
nickel ore with the studied reagents in comparison with
PBX. Since the yield of the foam product is different
for different compounds, it is difficult to judge their
enrichment properties by the degree of metal extrac-
tion. A high degree of extraction may be due to a large
cres × 105, M
Fig. 5. Adsorption isotherms in Langmuir coordinates:
(1) 5-(Phenylazo)salicylic acid, (2) 4-(1-naphthylazo)-
resorcinol, (3) 5-(2-benzthiazolylazo)salicylic acid,
(4) 4-(2-benzthiazolylazo)pyrocatechol.
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AZO DERIVATIVES OF PYROCATECHOL, RESORCINOL, AND SALICYLIC ACID
1741
Table 6. The results of collective flotation of copper–nickel ore in a rough concentrate with butyl xanthogenate and studied
collectors. Reagent consumption: main flotation—reagent 100 g t–1, CuSO4 15 g t–1, aeroflot 60 g t–1; control flotation—reagent
35 gt–1, CuSO4 15 g t–1, aeroflot 35 g t–1, sample of ore 200 g; grinding of ore with soda (3 kg t–1) 50 min
Collector
Butyl xanthogenate
Comparison options
Ni
Cu
Co
Foam yield, % 48.60
Extraction, %
Concentrate quality, %
Tail quality, %
82.83
0.744
0.146
92.61
0.348
0.026
82.35
0.029
0.006
4-(Phenylazo)resorcinol
Foam yield, % 57.41
Extraction, %
88.71
0.718
0.123
93.35
0.282
0.027
84.13
0.032
0.008
Concentrate quality, %
Tail quality, %
4-(1-Naphthylazo)resorcinol
4-(o-Tolylazo)resorcinol
Foam yield, % 54.25
Extraction, %
Concentrate quality, %
Tail quality, %
85.42
0.724
0.146
90.77
0.278
0.034
81.02
0.032
0.009
Foam yield, % 58.77
Extraction, %
Concentrate quality, %
Tail quality, %
88.12
0.680
0.131
93.22
0.265
0.027
84.22
0.032
0.008
5-(2-Benzthiazolylazo)salicylic acid
4-(2-Benzthiazolylazo)resorcinol
4-(2-Benzthiazolylazo)pyrocatechol
4-(2-Thiazolylazo)pyrocatechol
4-(Phenylazo)pyrocatechol
Foam yield, % 55.52
Extraction, %
Concentrate quality, %
Tail quality, %
83.96
0.665
0.159
90.87
0.267
0.033
81.30
0.034
0.010
Foam yield, % 56.74
Extraction, %
Concentrate quality, %
Tail quality, %
59.92
0.476
0.417
81.11
0.230
0.070
57.19
0.020
0.019
Foam yield, % 47.77
Extraction, %
Concentrate quality, %
Tail quality, %
82.09
0.721
0.144
92.36
0.408
0.031
77.22
0.027
0.007
Foam yield, % 61.28
Extraction, %
Concentrate quality, %
Tail quality, %
87.20
0.631
0.147
92.93
0.233
0.028
86.94
0.025
0.006
Foam yield, % 45.65
Extraction, %
Concentrate quality, %
Tail quality, %
84.14
0.855
0.135
90.49
0.337
0.030
82.79
0.036
0.006
5-(Phenylazo)salicylic acid
Foam yield, % 51.16
Extraction, %
86.99
0.857
0.134
92.19
0.308
0.027
82.98
0.039
0.008
Concentrate quality, %
Tail quality, %
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GUSEV et al.
(a)
(b)
cres × 105, M
cres × 105, M
Fig. 6. Adsorption of reagents vs. their residual concentration. (а) (1) 4-(2-thiazolylazo)pyrocatechol, (2) 5-(o-tolylazo)salicylic acid,
(b) 4-(o-tolylazo)resorcinol.
yield of foam product, rather than enrichment of raw
materials. Therefore, to characterize the concentration,
the ratio of the metal content in the concentrate to its
initial content in the ore (degree of concentration) was
selected. The initial content is calculated as the sum of
the products of the metal content in the concentrate and
in the tailings to their yields in percent divided by 100.
The results of the basic experiment with one PBX are
the averaged values of two experiments. The degree of
concentration in PBX is: 1.70 for Ni, 1.91 for Cu, 1.70
for Co. Among the studied compounds, PAP has the best
collective properties. Its indices are higher than that of
PBX, especially for Ni and Co: the degree of concentra-
tion for Ni, Cu, Co are 1.84, 1.98, 1.83, respectively.
BeTAP is not inferior to PBX in terms of flotation of
nickel and copper (1.72 and 1.93, respectively), for
cobalt this indicator is slightly lower (1.63). TAP has
markedly worse enrichment results compared to other
reagents studied, with the exception of BeTAR. Ahigher
degree of metal recovery in this case is achieved due
to the greater amount of foam product. Derivatives of
salicylic acid, especially BeTASA, have a higher foam
mass. Despite this, the degree of metal recovery is
lower due to the worse quality of the concentrate. PASA
has enrichment properties higher than other salicylic
acid derivatives, and they are close to the PBX values
(degree of concentration for Ni, Cu, Co is 1.70, 1.80,
1.63, respectively). For BeTASA, they are lower by
0.15–0.20. PAR, NAR, TolAR have approximately the
same flotation properties. Azo derivatives of resorcinol
are characterized by a noticeably greater yield of foam
product. Due to this, in some cases, a higher degree of
metal recovery is achieved, but the degree of concentra-
tion in them is worse than that of PBX, and is in the range
of 1.45–1.67. In the case of BeTAR, nickel and cobalt
enrichment is practically not observed. Correlations
between the adsorption of reagents and their flotation
properties could not be found.
Table 7 shows the flotation results of sulfide copper-
nickel ore with mixtures of reagents with PBX in a ratio
of 1 : 1.
The use of these mixtures significantly increases the
flotation properties of the reagents. In many mixtures, the
yield of foam product is either at the level of or less than
that of PBX. This with similar or higher degrees of metal
recovery provides a higher quality concentrate. In some
cases, an increase in enrichment is achieved compared to
one PBX. The enrichment properties ofTAPincreased most
significantly. Its mixture surpasses PBX: for Ni, degree of
concentration is 1.87, for Cu 2.02, for Co 1.85. PAP has
the same degree of concentration of Ni and Co at close
to PBX for Cu. BeTAP showed slightly worse proper-
ties: the degree of metal concentration is in the range of
1.63–1.85. The mixture with BeTASA has lower enrich-
ment characteristics for all the metals under study, and the
mixture with PASA has a higher rate for Ni (1.81), for Cu
and Co they are similar to the base experiment 1.94 and
1.74, respectively. The enrichment properties of resorcinol
derivatives have increased significantly. In NAR, PAR,
and TolAR, the degree of concentration of Ni, Cu, and
Co is in the ranges 1.61–1.80, 1.93–2.05, and 1.68–1.91,
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AZO DERIVATIVES OF PYROCATECHOL, RESORCINOL, AND SALICYLIC ACID
1743
Table 7. The results of collective flotation of copper–nickel ore in rough concentrate with mixtures of butyl xanthogenate :
reagent (1 : 1). Reagent consumption: main flotation—reagent 100 g t–1, CuSO4 15 g t–1, aeroflot 60 g t–1; control flotation—
reagent 35 g t–1, CuSO4 15 g t–1, aeroflot 35 g t–1, sample of ore 200 g, grinding of ore with soda (3 g t–1) 50 min
Collector
Comparison options
Ni
Cu
Co
Butyl xanthogenate
Foam yield, % 48.60
Extraction, %
82.83
0.744
0.146
92.61
0.348
0.026
82.35
0.029
0.006
Concentrate quality, %
Tail quality, %
Butyl xanthogenate : 4-(phenylazo)resorcinol
Foam yield, % 44.69
Extraction, %
80.67
0.673
0.130
91.47
0.389
0.029
84.72
0.022
0.003
Concentrate quality, %
Tail quality, %
Butyl xanthogenate : 4-(1-naphthylazo)resorcinol
Butyl xanthogenate : 4-(o-tolylazo)resorcinol
Foam yield, % 48.40
Extraction, %
Concentrate quality, %
Tail quality, %
85.36
0.798
0.128
93.33
0.393
0.026
83.26
0.026
0.005
Foam yield, % 48.24
Extraction, %
Concentrate quality, %
Tail quality, %
84.44
0.738
0.127
93.81
0.413
0.025
81.03
0.023
0.005
Butyl xanthogenate : 5-(2-benzthiazolylazo)salicylic acid
Butyl xanthogenate : 4-(2-benzthiazolylazo)resorcinol
Butyl xanthogenate : 4-(2-benzthiazolylazo)pyrocatechol
Butyl xanthogenate : 4-(2-thiazolylazo)pyrocatechol
Butyl xanthogenate : 4-(phenylazo)pyrocatechol
Butyl xanthogenate : 5-(phenylazo)salicylic acid
Foam yield, % 52.57
Extraction, %
Concentrate quality, %
Tail quality, %
84.77
0.722
0.144
94.50
0.391
0.028
85.72
0.023
0.007
Foam yield, % 58.18
Extraction, %
Concentrate quality, %
Tail quality, %
82.61
0.619
0.181
92.01
0.265
0.032
81.78
0.027
0.008
Foam yield, % 50.42
Extraction, %
Concentrate quality, %
Tail quality, %
84.21
0.671
0.128
93.44
0.376
0.027
81.00
0.027
0.006
Foam yield, % 45.76
Extraction, %
Concentrate quality, %
Tail quality, %
85.66
0.898
0.127
92.54
0.363
0.025
85.46
0.033
0.005
Foam yield, % 50.21
Extraction, %
Concentrate quality, %
Tail quality, %
86.30
0.792
0.127
91.97
0.311
0.027
86.26
0.034
0.005
Foam yield, % 47.54
Extraction, %
Concentrate quality, %
Tail quality, %
85.95
0.914
0.135
91.99
0.331
0.026
82.20
0.042
0.008
RUSSIAN JOURNAL OF APPLIED CHEMISTRY Vol. 92 No. 12 2019

1744
GUSEV et al.
pp. 9–12.
respectively. They are either at the level of PBX, or in the
case of NAR surpass it. A mixture of PBX with BeTAR
has weaker enrichment properties compared to one PBX.
2. Ryaboi, V.I., Tsv. Metally, 2011, no. 3, pp. 7–14.
3. Chandra, A.P. and Gerson, A.R., Advances in Colloid and
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CONCLUSIONS
4. Ignatkina, V.A., Bocharov, V.A., Stepanova, V.V., and
Kustova, T.I., Obogashchenie Rud, 2005, no. 6, pp. 45–48.
It was established that under flotation conditions the
reagents are in a single ionized form. They do not alter
the surface tension of aqueous alkali solutions, which
indicates the absence of activity at the reagent–air
interface. The adsorption of reagents on the ore surface is
mainly chemical in nature, and the degree of adsorption
is determined by the number of aromatic and heterocyclic
rings in the diazocomponent. Of the individual azo
compounds studied, only 4-(phenylazo)pyrocatechol,
4-(2-benzthiazolylazo)pyrocatechol, and 5-(phenylazo)
salicylic acid have enriching properties that are higher
or close to those of potassium butyl xanthogenate. Other
reagents, especially azo derivatives of resorcinol, turned
out to be worse. The use of mixtures of azo compounds
with potassium butyl xanthogenate in a ratio of 1 : 1
significantly increases their flotation properties. In some
cases, they surpass it both in enrichment of Ni, Cu, Co,
and in the degree of extraction of Ni and Co. Therefore,
the studied reagents can be considered as potential
modifiers for flotation.
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Chanturiya, E.L., Fiz.-Tekhn. Prob. Razrab. Polez. Iskop.,
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Chernova, G.V., Khim. Tekhnol., 2009, vol. 10, no. 1,
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https://doi.org/10.3390/min8030115
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ACKNOWLEDGMENTS
The work was carried out on the topic of state assignment
no. AAAA-A18-118032790022-7.
12. Gusev, V.Y., Radushev, A.V., Chekanova, L.G., Bayga-
cheva, E.V., Manylova, K.O., and Gogolishvili, V.O., Russ.
J. Appl. Chem., 2018, vol. 91, no. 4, pp. 573–582.
https://doi.org/10.1134/S1070427218040079
FUNDING
13. Ryaboi, V.I., Obogashchenie Rud, 2008, no. 6, pp. 24–30.
This work was financially supported by the grant of the
Russian Foundation for Basic Research no. 17-03-00727a.
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Rozovskii, Yu.G., Russ. J. Inorg. Chem., 2009, vol. 54,
no. 10, pp. 1619–1624.
CONFLICT OF INTEREST
https://doi.org/10.1134/S0036023609100180
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& Chem. Eng., 2012, vol. 6, no. 7, pp. 651–657.
The authors declare that there is no conflict of interest
requiring disclosure in this article.
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Spect., 2011, vol. 78, no. 4, pp. 586–593.
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