Journal of Minerals & Materials Characterization & Engineering, Vol. 8, No.6, pp 469-477, 2009
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469
Synthesis and Structural Characterization of Xanthate (KEX) in Sight of
Their Utilization in the Processe s of Sulphides Flotation
Nedjar. Zohir*1, Bouhenguel. Mustapha2 and Djebaili Abd Elbaki3
1Engineering laboratory of Chemical and Process Engineering.Sciences and Engineer Faculty, Industrial
Chemistry Department, Med Khider Biskra University. ALGERIA
2Engineering laboratory of Chemical and Process Engineering.Sciences and Engineer Faculty, Industrial
Chemistry Department,Med Larbi Ben Mhidi oum elbouaghi University. ALGERIA
3Engineering laboratory of Chemical and Process Engineering.Sciences and Engineer Faculty, Industrial
Chemistry Department, L’hadj lakhdar Batna University. ALGERIA
E-mail*: [e-mail]
ABSTRACT
A lot of industries (chemical, mining) developed numerous processes based on the use of the
adsorption, From then on, the resolution of practice problems pass inevitably by the
understanding of fundamental concepts governing the phenomena of flotation and the interaction
in the solid- liquid or solid - gas interface.
In this study, we suggest proceeding to a theoretical and experimental study concerning the
organic synthesis of an organo metallic product (KEX) by intermittent method and their use in
the processes of sulphides flotation. Searches showed that the surface state after grinding
resulted from a combination of oxidized sorts of sulfur treat type with copper sulphate and lead
oxy-hydroxide thickness of which is very superior to 200 nm. The addition of an organometallic
molecule sulphurated (Potassium ethyl xanthate KEX) in available concentrations of 1g/l (6,
24.10-3 M) is going to lead the forming of an organometallic layer mixed in the galena surface.
From weak concentrations in collector, the organometallic layer present in the mineral surface
is mixed. It is formed by a complex xanthate type of lead (PbX, bandages IR in 1200 cm-1), of
dixanthogene (X2 forms oxidized with the molecule of xanthate, bandages IR in 1262 cm-1), of
elementary sulfur and a certain proportion of initial superficial oxidized phases. The mechanism
leading to the forming of PbX is the type of ionic exchanges. On the other hand, two types of
different mechanisms can be at the origin of dixanthogene forming (X2).
A first type consists of a catalytic oxidation in the mineral surface with reduction of the dissolved
oxygen. This type of mechanism depends essentially on the potential redox of the system. A
second type brings in the forming of xanthate salts of lead by a mechanism of Ionic exchange
(eq. 1) then their catalytic degradation (eq. 2):
Pbn + + n X- → (Pb X) n Equation 1: independent from the potential rédox.
Pb(X) n (catal. by PbS) + 1/2 O2 + n/2 H2O → Pb (OH) n + n/2 X2 Equation 2: dependent on
the redox potential.
Key Words: Flotation; Synthesis; Xanthate (KEX); Adsorption; Galena

470 Nedjar. Zohir, Bouhenguel. Mustapha and Djebaili Abd Elbaki Vol.8, No.6
1. PROBLEM
A lot of industries (chemical, mining,) developed numerous processes based on the use of the
adsorption, what means in big part a good mastery of the superficial ability to react of the used
solids. From then on, the resolution of practice problems pass inevitably by the understanding of
fundamental concepts governing the phenomena of flotation and the interaction in the solid-
liquid or solid - gas interface.
The knowledge of the composition variations of the ore to be dealt, reproduces the concentration
of the reagent in the pulp determine the results of the flotation. This research aims to better
understand the phenomena of interaction (adsorption, haste,) of typical organic molecules thiols
(Xanthate) on natural solid (sulphides).
The control and the regulation of the reagent concentration in the pulp is practically the only way
of the establishment of an automatic system and an optimal regime of the reagent and an
obtaining of a possible maximum of indication of flotation with a minimal consumption of the
reagent of flotation [1-10].
2. METHODS AND STEPS
In every case, the researches lean on a global approach of phenomena that is a consideration of
the compartments set of the system and the links which unite them. This imposes the tools
application of observation and description of interfaces on molecular and even atomic scales and
so the same thing for the mechanisms of interaction in aqueous phase in systems of adsorbant /
adsorbat. These two main approaches make by combining the techniques of adsorption robust
liquid and the techniques of physical analyses of the solids surface. This approach is coupled
with a study by physical tools of the surface state of adsorbants before and after contact. It is
then necessary to be able to have non- destructive tools that information is of superficial origin
by modulating the depth of investigation. Spectroscopy or molecular micro spectroscopy
(Visible UV, infrared, RX) answer this contract conditions. It is important to be able to couple
these techniques with a method of direct observation of the surface which is the electronic
microscopy with sweeping (MEB) [11-14].
3 MAIN RESULTS
3.1 Synthesis of Potassium Ethyl Xanthate (KEX) By the Discontinuous Method:
During the intermittent method, in the basic solution of alcohol, consisted of a mole of éthylique
alcohol, one mole of water and one mole of potassium hydroxide, one mole of disulfure of
carbon (CS2) was slowly added. After that, we separate the deposit of xanthate, which after
addition of all the portion of disulfide of carbon representing constituent formed crystals. This
method allows of obtaining of the high quality xanthates (superior activity of xanthates has
90 %) [15-21].

Vol.8, No.6 Synthesis and Structural Characterization of Xanthate 471
3.2. Characterization of Used Collector: The Case of Potassium Ethyl Xanthate (KEX)
3.2.1. Characterization of potassium ethyl xanthate (KEX) synthetized with the electron
microscope with sweeping (MEB):
The principle of the sweeping consists in investigating the surface of the sample by successive
lines and in passing on the signal of the detector to a cathode-ray screen sweeping of which is
exactly synchronized with the one of the incidental bundle. Under the impact of the electron
beam accelerated, diffused retro electrons and secondary electrons emitted by the sample are
collected selectively by detectors which transmit a signal to a cathode ray tube whose sweeping
is synchronized with the sweeping of the object (Figure 1) [22].
Fig. 1. Microphotography taken with the electron microscope with sweeping (X1480) for KEX.
3.2.2. Characterization of synthesized potassium ethyl xanthate (KEX) by X-Ray :
This method is used to identify the nature and the structure of the crystallized products.
Figure 2 shows intense reflexions with 2θ = 11, 81 and 2θ= 37, 96.
Fig. 2. Spectre RX of potassium ethyl xanthate synthetized.

472 Nedjar. Zohir, Bouhenguel. Mustapha and Djebaili Abd Elbaki Vol.8, No.6
3.2.3. Characterization of synthesized potassium ethyl xanthate (KEX) by infra-red
spectroscopy:
The infra-red synthesized ethyl xanthate spectrum (Figure 3) indicates the appearance of the
absorption bands to 1147.44-1120.44-1050.87-1006.66 cm -1 and other bands to 1438.64 -
1380.78 -1295.93-1250.58 cm -1 allotted respectively to the vibrations of connections (C=S) and
(O-CS) [30].
Fig. 3. Spectre FTIR of KEX synthetized.
3.2.4. Characterization of potassium ethyl xanthate (KEX) by RMN1 H:
Spectrum RMN1 H of synthesized KEX (Figure 4) is characterized by the presence of the peaks
towards 1.37 ppm of grouping methyl (- CH3) and 4.45 ppm of grouping (- CH2).
Fig. 4. Spectra RMN1H of potassium ethyl xanthate synthetized (KEX).

Vol.8, No.6 Synthesis and Structural Characterization of Xanthate 473
3.3. Characteristics of Minerals Used: The Case of Crystal
3. 3.1. Characterization of crystal by infra-red spectroscopy:
The infra-red spectroscopy plays a very significant role in characterization and identification of
minerals, where we have resort to characterize and identify crystal by spectroscopy FTIR in a
broad interval (4000-400) cm -1.The infra-red galena spectrum (Figure 5) in KBr illustrates the
appearance of the absorption bands with:
(615.181-838.838.883) cm -1 characterized cm -1 Pb with CO32 -.(1616.06-1637.27) cm -1
characterized with ions OH (M-OH), said water of structure.
(3235.97-3552.24) cm -1 characterized cm -1 grouping OH of the water of hydration. [23-25]
Fig. 5. FTIR Spectrum of the galena.
3.3.2. Characterization of crystal by X-ray:
This method is used to identify the crystallized products nature and structure.
According to Figure 6, there is the diameter d1 = 2.945 and d2 = 3.405; the angle
2θ1 = 30.25 and 2θ2 = 26.17; (conformed with ASTM files)
Fig. 6. RX Spectra of the galena.

474 Nedjar. Zohir, Bouhenguel. Mustapha and Djebaili Abd Elbaki Vol.8, No.6
4.4. Theoretical and Experimental Methods Used in Flotation
4. 4.1. Qualitative determination of the adsorption of the collectors used in flotation:
The qualitative determination of the adsorption of anion collectors on the mineral surface of
crystal (PbS) was made by electronic microscopy has sweeping MEB and by the infra-red
spectroscopy, being able to give direct information on the active centers of adsorption. For that
we made a comparative study of the images of infra-red MEB and spectra of crystal before and
after treatment of this last by the suitable collector under the operating conditions of the process
of flotation.
4.4.2. Qualitative determination of the adsorption of potassium ethyl xanthate (KEX) by
infra-red spectroscopy:
The qualitative study of the adsorption of the collectors on mineral surfaces is an essential factor
for the development of technology of enrichment and concentration of the ores by flotation.
The hydrophobicity of surface necessary to flotation is obtained because the big length of
hydrocarbon chain of the collectors used, and the concentration of these collectors must remain
sufficiently low to avoid the formation of micelles of surface. Indeed if it is formed a second
layer on solid surface, it will present the polar part of the collector outside and gives a surface
hydrophobia to the solid. This surface hydrophobia will be able to disappear, but the conditions
of flotation will remain bad.
During anion flotation, the charge of mineral surface that we need to float, is it the only which
must be positive, in order to obtain selectivity between various present minerals.
The qualitative study of the adsorption of ethyl xanthates of potassium prepared starting from
carbon bisulphide and a mixture of ethanol and a strong base of potassium hydroxide and water
on the level of laboratory, on mineral surfaces of the crystal and iron sulphide required the
preparation of a standard solution of concentration 1g/l.
For the study of the ethyl adsorption of potassium xanthates on the mineral surface of crystal, we
carry out an experiment with a concentration of 1mg/l in basic medium pH (9-10) and to adjust
the pH we used sodium carbonate, and iron sulphide we carry out the experiment of adsorption
in an acid medium pH (5-6) and for adjusted the pH uses the sulfuric acid (Figure 7).
4. 4.3. Qualitative determination of the adsorption of potassium ethyl xanthate (KEX) on
crystal:
On the infra-red galena spectrum (Figure 7) after treatment by synthesized potassium ethyl
xanthate (KEX) by the concentration 1g/l under the conditions of contacts with the atmosphere
in basic medium pH = 9-10, we note the combination of some peaks of xanthate PbKX2 lead
(1210, 1110, 1020 cm -1) and dixanthogene X2 (1262, 1240cm -1).

Vol.8, No.6 Synthesis and Structural Characterization of Xanthate 475
On the analyzed spectrum, we note an average peak to 1128 cm - 1 allotted to PbKX2 and the
remainder of the characterized peaks Pb with carbonates.
Fig. 7. Spectra FTIR of galena treated by KEX.
4. 4.4. Qualitative determination of the adsorption of xanthate (KEX) by electron
microscope with sweeping
The qualitative study of the ethyl adsorption of xanthate of potassium on the surface of crystal
(PbS) by the electron microscope with sweeping (Figure 8-9) with different enlarging treated
under the same conditions of the pH and of concentration show the existence of one or more
white stains that means the adsorption of KEX on mineral surfaces. [26-29]
Fig. 8. Microphotography taken with the electron microscope with sweeping (X1480):
galena pure.

476 Nedjar. Zohir, Bouhenguel. Mustapha and Djebaili Abd Elbaki Vol.8, No.6
Fig. 9. Microphotography taken with the electron microscope with sweeping (X1480):
galena treated by KEX
5. CONCLUSIONS
This work enabled us to carry out the organic synthesis of anion collector standard potassium
ethyl xanthate (KEX) under determined conditions and the importance of the use of xanthates in
the flotation of sulphides.
The qualitative determination of collector’s adsorption (KEX) on surface mineral of galena, by
IR spectroscopy and electronic scan microscopy (MEB) in different enlarging treated under same
the conditions from concentration and pH made it possible to give direct information on the form
of adsorption.
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