CC BY
32
https ://doi.org/10.29013/ESR-19-11.12-82-87
Rosilov Mansur Sirgievich, Tashkent Institute of Chemical Technology Karshi Engineering Economical Institute
Samadiy Murojon Abdusalimzoda, Tianjin University of Science and Technology Tashkent Institute of Chemical Technology
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RHEOLOGICAL PROPERTIES OF PULPS AND SOLUTIONS OF ZINC CHLORIDE CONVERSION PROCESS
Abstract. The article provides information on rheological properties of pulps and solutions of conversion of zinc chloride obtained from zinc-containing concentrate and hydrochloric acid. Rheological properties in time and temperature variations in laboratory conditions are described in detail. The main parameters that determine the rheology process are the fluidity of pulps and solutions in the production of zinc chloride. The conclusion is made about the technological possibility of transporting the reaction pulp of zinc chloride in production conditions, since the pulps and solutions of the process are quite tangible.
Keywords: zinc containing ore, concentrate, rheological properties, solution, pulp.
Introduction: Zinc has been used by man since in addition to zinc may contain additional valuable ancient times. The first information about metallic zinc refers to the V century BC. Initially, it was obtained in the form of an alloy with copper-brass, which was smelted in India, China and other countries of the Ancient East.
Zinc chloride is widely used in Uzbekistan, but today is not produced, although it has a large number of raw materials zinc [1].
The largest zinc producers are: China, Canada, Australia [2]. These countries are the main exporters of zinc. The largest importers of zinc are the USA, Taiwan, Germany. The largest consumers of zinc are (million tons per year): China (1.3-1.4); USA (1.1-1.3); Japan (0.7-0.8); Germany (0.4); great Britain (0.3); France (0.2-0.24); Belgium, Canada, Italy, Australia, India-0.1-0.17.
Given the volume of production of zinc concentrate, it is now necessary to make a comprehensive processing of sphalerite concentrate, because at the moment the zinc concentrate produced by the plants
components such as gold, silver, indium, cadmium, copper and other metals that are not extracted.
Objects and methods: The investigations were carried out with zinc-containing ore of Khandiza deposit containing zinc concentrate 39.45-40.50% Zn. Chemical analysis of initial, intermediate and final products was carried out by known methods [3-5].
Manufacturability and efficiency of the individual stages of the process of obtaining zinc chloride is largely determined by the rheological characteristics of the initial, intermediate and final solutions and suspensions. The most important, from the point ofview of the analysis of the possibility of transportation of saturated solutions, are the density and viscosity.
The density of solutions and pulps was determined using a PJ-2 pycnometer with a measurement accuracy of 0.05 ratio%. Kinematic viscosity of solutions and pulps was measured by glass capillary viscometers VPJ-1 and VPJ-2 with an error of 0.2 ratio%.
The density value was calculated by the formula:
m p=—;
v
where m - mass of the pulp, g; v - the capacity of the pycnometer, cm3.
Viscosity was determined according to the following formula:
n =K-p-z;
where k - viscometer constant and it is equal to 0.3262 and 3.404, respectively, for VPJ -1 and VPJ -2 with a capillary diameter of 1.31 mm. p - pulp
density in g/cm3. t - time of the pulp passing through the capillary of the viscometer, s.
Determination of pulp viscosity and density was carried out at temperatures from 20 to 80 °C and Zn: HCI ratios from 1:0.6 to 1: 2.0. The results are presented in (tables 1-2). According to the obtained research results, empirical equations with correlation coefficient (R2) are derived. The corresponding coefficients are in the range of0.9269 and 1.000 indicate that the experimental data are well shuffled with the established values.
Table 1. - Density of pulps obtained by conversion of zinc concentrate with hydrochloric acid
№ Ratio Zn: HCI Density (g/cm3) Empirical equation R2
20 °C 40 °C 60 °C 80 °C
1. 1 0.6 1.698 1.690 1.685 1.683 y= -0.0050x+1.7015 0.9328
2. 1 0.8 1.689 1.683 1.677 1.674 y= -0.0051x+1.6935 0.9797
3. 1 0.9 1.684 1.676 1.670 1.661 y= -0.0075x+1.6915 0.9947
4. 1 1.0 1.680 1.671 1.664 1.654 y= -0.0085x+1.6885 0.9959
5. 1 1.1 1.676 1.668 1.659 1.651 y= -0.0084x+1.6845 0.9994
6. 1 1.2 1.644 1.622 1.599 1.581 y= -0.0212x+1.6645 0.9974
7. 1 1.4 1.592 1.566 1.541 1.514 y= -0.0259x+1.6180 0.9998
8. 1 1.5 1.550 1.518 1.491 1.472 y= -0.0261x+1.5730 0.9876
9. 1 1.7 1.508 1.472 1.452 1.434 y= -0.0242x+1.5273 0.9699
10. 1 2.0 1.476 1.442 1.424 1.408 y= -0.0222x+1.4930 0.9645
Analysis of the data indicates changes in pulp density depending on changes in the Zn: HCI ratio, i.e. decrease in the Zn: HCI ratio, and temperature (table 1). With an increase in the amount ofhydrochloric acid and temperature, the density of solutions decreases. Thus, at 20 °C, the pulp density at the ratio Zn: HCI=1:0.6 is 1.698 g/cm3, and at Zn: HCI=1:2.0-1.476 g/cm3.
Table 2.- Viscosity of pulps obtained by conversion of zinc concentrate with hydrochloric acid
Whereas, at the same Zn: HCI ratio, an increase in temperature leads to a decrease in the pulp density. For example, at a ratio of1:1.1 and a temperature of 20 to 80 °C, the density value varies from 1.676 to 1.651 g/cm3.
№ Ratio Zn: HCI Viscosity, MPa^s Empirical equation R2
20 °C 40 °C 60 °C 80 °C
1 2 3 4 5 6 7 8
1. 1:0.6 8.45 5.58 4.38 3.58 y= -3.53ln(x)+8.303 0.9905
2. 1:0.8 8.42 5.49 4.30 3.50 y= -3.57ln(x)+8.262 0.9892
3. 1:0.9 8.38 5.39 4.21 3.42 y= -3.60ln(x)+8.208 0.9876
1 2 3 4 5 6 7 8
4. 1:1.0 8.36 5.33 4.10 3.38 y= -3.63ln(x)+8.176 0.9858
5. 1:1.1 8.33 5.29 4.05 3.35 y= -3.63ln(x)+8.143 0.9851
6. 1:1.2 8.30 5.15 3.98 3.30 y= -3.65ln(x)+8.079 0.9800
7. 1:1.4 8.25 5.04 3.87 3.25 y= -3.66ln(x)+8.001 0.9759
8. 1:1.5 8.15 4.92 3.80 3.20 y= -3.62ln(x)+7.894 0.9726
9. 1:1.7 7.94 4.81 3.73 3.15 y= -3.50ln(x)+7.690 0.9723
10. 1:2.0 7.70 4.72 3.60 3.02 y= -3.43ln(x)+7.482 0.9774
A similar pattern is observed in the study of viscosity (table. 2). Pulp viscosity at 20 °C at a ratio of Zn: HCI=1:0.6 decreases from 8.45 MPa-s to 7.70 MPa-s at a ratio of Zn: HCI=1:2.0, respectively, with an increase in temperature from 20 to 80 °C. In addition, with a constant ratio of Zn: HCI and an increase in temperature, it reduces the viscosity from 8.45 to 3.58 and from 7.70 to 3.02 MPa-s. All pulps have good rheological properties. Experiments
show that the pulp has sufficient transportability. From the obtained data the most optimal is the ratio Zn: HCI = 1: 1,1.
Further, the rheological properties were studied depending on the conversion time of zinc-containing concentrate and hydrochloric acid in the preparation of zinc chloride at a ratio of Zn: HCI=1:1,1 and the time was varied from 0 to 12 hours. The data are shown in (tables 3 and 4).
Table 3.- Density of pulps obtained at the stage of preparation of zinc chloride at molar correlation Zn: HCI = 1: 1,1
№ Conversion time, h Density (g/cm3) Empirical equation R2
20 °C 40 °C 60 °C 80 °C
1. 0 1.780 1.771 1.762 1.754 y= -0.0087x+1.7885 0.9992
2. 1 1.766 1.757 1.749 1.740 y= -0.0086x+1.7745 0.9995
3. 2 1.752 1.743 1.735 1.727 y= -0.0083x+1.7600 0.9991
4. 3 1.741 1.732 1.724 1.716 y= -0.0083x+1.7490 0.9991
5. 4 1.730 1.721 1.713 1.705 y= -0.0083x+1.7300 0.9991
6. 5 1.720 1.711 1.702 1.694 y= -0.0087x+1.7285 0.9992
7. 6 1.709 1.700 1.692 1.685 y= -0.0080x+1.7165 0.9969
8. 7 1.699 1.691 1.683 1.675 y= -0.0080+1.7070 0.1000
9. 8 1.690 1.682 1.674 1.666 y= -0.0080x+1.6980 0.1000
10. 9 1.682 1.674 1.666 1.658 y= -0.0080x+1.6900 0.1000
11. 10 1.676 1.668 1.659 1.651 y= -0.0084x+1.6845 0.9994
12. 11 1.672 1.664 1.656 1.648 y= -0.0080x+1.6800 0.1000
13. 12 1.670 1.662 1.654 1.646 y= -0.0080x+1.6780 0.1000
Table 4.- The viscosity of pulps obtained at the stage of preparation of zinc chloride at the molar ratio Zn: HCI = 1: 1,1
№ Conversion time, hour Viscosity, MPa^s Empirical equation R2
20 °C 40 °C 60 °C 80 °C
1 2 3 4 5 6 7 8
1. 0 8.59 5.45 4.17 3.45 y= -3.75ln(x)+8.396 0.9850
1 2 3 4 5 6 7 8
2. 1 8.57 5.44 4.16 3.44 y= -3.74ln(x)+8.377 0.9852
3. 2 8.54 5.42 4.15 3.43 y= -3.73ln(x)+8.347 0.9851
4. 3 8.52 5.41 4.14 3.42 y= -3.72ln(x)+8.329 0.9853
5. 4 8.49 5.39 4.12 3.40 y= -3.71ln(x)+8.301 0.9855
6. 5 8.46 5.37 4.11 3.39 y= -3.70ln(x)+8.271 0.9854
7. 6 8.43 5.35 4.09 3.38 y= -3.69ln(x)+8.241 0.9852
8. 7 8.40 5.33 4.08 3.37 y= -3.67ln(x)+8.211 0.9852
9. 8 8.37 5.31 4.07 3.36 y= -3.66ln(x)+8.181 0.9851
10. 9 8.35 5.30 4.06 3.36 y= -3.64ln(x)+8.161 0.9849
11. 10 8.33 5.29 4.05 3.35 y= -3.63ln(x)+8.143 0.9851
12. 11 8.30 5.27 4.03 3.33 y= -3.63ln(x)+8.114 0.9853
13. 12 8.27 5.25 4.01 3.31 y= -3.62ln(x)+8.086 0.9855
The filtrate densities decrease from 1.780 to 1.670 g/cm3 and to 1.646 g/cm3, respectively, as the conversion time increases and the temperature rises from 20 to 80 °C.
Similarly, solution viscosities decrease from 8.59 MPa-s to 8.27 and to 3.31 MPa-s, respectively, with increasing conversion time and increasing temperature from 20 to 80 °C.
Zinc chloride pulps have acceptable rheological properties and are quite transportable.
Tables 5 and 6 provide data on the density and viscosity of zinc chloride solutions in the process of evaporation of saturated solutions.
As can be seen from the table, increasing the temperature significantly reduces the density of mother
solutions at a constant concentration of ZnCI2. For example, at a concentration of 45%, an increase in temperature from 20 to 80 °C contributes to a decrease in density from 1.369 to 1.337 g/cm3. At the same time, increasing the amount of evaporated water at a constant temperature, on the contrary, increases the density values in all studied temperatures. For example, at temperatures of 20 and 80 °C, the density increases from 1.350 to 1.466 g/cm3 and from 1.327 to 1.403 g/cm3, respectively, i.e. from 0.92 to 1.06 times.
Similarly, the viscosity of solutions decreases from 3.82 to 1.42 MPa-s and increases to 4.75 MPa-s, respectively, with an increase in temperature from 20 to 80 °C and the amount of evaporated water.
Table 5.- The density of the pulps obtained at the residue stage of zinc chloride solution at the ratio Zn: HCI = 1: 1,1
№ Effect of conc. ZnCI2,% Density (g/cm3) Empirical equation R2
20 °C 40 °C 60 °C 80 °C
1 2 3 4 5 6 7 8
1. 30 1.350 1.340 1.333 1.327 y= -0.0076 x+1.3565 0.9857
2. 35 1.358 1.343 1.334 1.329 y= -0.0096 x+1.3650 0.9481
3. 40 1.363 1.347 1.338 1.332 y= -0.0102 x+1.3705 0.9527
4. 45 1.369 1.351 1.342 1.337 y= -0.0105 x+1.3760 0.9269
5. 50 1.376 1.358 1.349 1.344 y= -0.0105 x+1.3830 0.9269
6. 55 1.384 1.367 1.358 1.353 y= -0.0102 x+1.3910 0.9339
7. 60 1.392 1.375 1.366 1.362 y= -0.0099 x+1.3985 0.9198
8. 65 1.401 1.384 1.375 1.370 y= -0.0102 x+1.4080 0.9339
1 2 3 4 5 6 7 8
9. 70 1.410 1.394 1.384 1.379 y= -0.0103 x+1.4175 0.9460
10. 75 1.428 1.406 1.393 1.382 y= -0.0151 x+1.4400 0.9721
11. 80 1.446 1.420 1.405 1.393 y= -0.0174x+1.4595 0.9667
12. 85 1.466 1.437 1.416 1.403 y= -0.0210 x+1.4830 0.9718
Table 6.- Viscosity of pulps obtained at the stage of zinc chloride solution evaporation at the ratio Zn: HCI = 1: 1,1
№ Effect of conc. ZnCI2,% Viscosity, MPa^s Empirical equation R2
20 °C 40 °C 60 °C 80 °C
1. 30 3.82 2.66 1.94 1.42 y= -1.73ln(x)+3.834 0.9997
2. 35 3.90 2.76 2.03 1.46 y= -1.75ln(x)+3.928 0.9984
3. 40 3.98 2.84 2.12 1.49 y= -1.77ln(x)+4.017 0.9967
4. 45 4.04 2.92 2.20 1.54 y= -1.78ln(x)+4.086 0.9949
5. 50 4.10 2.99 2.27 1.60 y= -1.77ln(x)+4.149 0.9941
6. 55 4.17 3.07 2.34 1.67 y= -1.78ln(x)+4.222 0.9937
7. 60 4.24 3.15 2.42 1.74 y= -1.77ln(x)+4.296 0.9928
8. 65 4.32 3.24 2.51 1.81 y= -1.78ln(x)+4.382 0.9913
9. 70 4.41 3.33 2.59 1.90 y= -1.78ln(x)+4.471 0.9917
10. 75 4.51 3.44 2.69 1.97 y= -1.80ln(x)+4.580 0.9895
11. 80 4.62 3.57 2.81 2.10 y= -1.78ln(x)+4.693 0.9890
12. 85 4.75 3.70 2.93 2.23 y= -1.79ln(x)+4.823 0.9894
It is relevant to note here that in all studied conditions (influence ratio, conversion time and concentration) temperature and concentration are the main factor. Changes in density under the influence of temperature and concentration lead to volume changes and other thermodynamic properties [6-8]. The decrease in density with increasing temperature is explained by the relaxation of the "solute-solvent" interaction between Zn+2 ions and water molecules. Whereas, an increase in density with an increase in the concentration ofzinc chloride is an increase in "solute-solute" interactions, the formation of an Association and the displacement of water molecules from the hydrate shell.
In any case, all solutions have good rheological properties. This is evidenced by the mobility and high fluidity of the pulps and that they can be transported in production conditions by existing devices without any restrictions.
Conclusion: Thus, the conducted researches have shown possibility of processing of zinc-containing concentrates of the Khandiza Deposit on zinc chloride. To do this, the process of decomposition of zinc-containing concentrate must be carried out with hydrochloric acid at a ratio of Zn: HCI = not less than 1: 1,1 and the duration of the process is not less than 10 hours.
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