Isothermal Evaporation of Water from the Brine of Lake Bolshoye Yarovoye
Abstract Generated abstract
This study examines the change in salt composition of natural brine from Lake Bolshoye Yarovoye during isothermal evaporation at 25°C, with the practical aim of assessing mineral raw materials in the Kulunda steppe. Parallel evaporation experiments were conducted in a thermostated crystallizer, with density measurements, chemical analyses of liquid and solid phases, and graphical interpretation using the equilibrium diagram of the NaCl, MgSO4, MgCl2, and water system. The work determines the sequence of crystallization: sodium chloride begins to separate at about 25 to 25.4° Baumé and predominates until about 30.3° Baumé, followed by magnesium sulfate hydrates, and finally magnesium chloride hexahydrate near 37.5 to 37.7° Baumé. The results provide approximate concentration points for phase separation and suggest directions for semi-industrial exploitation of the lake brine.
Full Text
Yakimov M. N., Grigorieva A. A., Kuminova E. I.
Isothermal Evaporation of Water from the Brine of Lake Bolshoye Yarovoye.
The present investigation is one of the topics concerning the development of mineral raw materials in the Kulunda steppe. The purpose of this work was to trace the change in the salt composition of the natural brine of Lake B. Yarovoye during isothermal evaporation at 25°C. Lake B. Yarovoye is a basin situated to the southwest, 5 kilometers from the railway branch of the Omsk Railway, Tatarskaya—Kulunda—Pavlodar. It covers an area of 7000 ha; its greatest length is 10 km, and its depth reaches 8.5 meters. The volume of brine is about 400,000,000 cubic meters, with a total salt reserve of up to 70 million tons.
For the purpose of the most complete study of the process, we carried out several parallel experiments with natural brine.
V. P. Ilyinskii and V. M. Filipenko¹) studied the course of isothermal evaporation of two large bodies of water, applying illustrative geometrical images for this purpose and methods of graphical calculations, and gave a classification of evaporation processes with crystallization of NaCl from natural brines. N. S. Kurnakov and V. I. Nikolaev²) studied salt equilibria during the evaporation of seawater, and gave the distinction from the theoretical Van’t Hoff equilibrium diagram of the paths of crystallization during natural evaporation of seawater.
Our aim was, using the theoretical equilibrium diagram of the reciprocal system:
\[ 2\mathrm{NaCl} + \mathrm{MgSO}_4 \rightleftarrows \mathrm{Na}_2\mathrm{SO}_4 + \mathrm{MgCl}_2, \]
which has been repeatedly studied by N. S. Kurnakov, Zhemchuzhnyi, Opytnaya, Voskresenskaya, Ilyinskii, Sagaidachnyi, Van’t Hoff, D’Ans, Jencke, Blasdale, Tägert and others, to trace the course of the crystallization ray during evaporation of lake brine, which in its chemical composition differs somewhat from the chemical composition of seawater, and also, using the method of graphical calculations, to give approximately the points at which one or another solid phase begins to appear.
I. Experimental apparatus.
Evaporation was carried out in a large open crystallizer, placed in a thermostat with double asbestos walls. Heating was carried out by electric furnaces; the temperature was regulated by a mercury thermoregulator and fluctuated within ±0.5°.
¹) Zh. Khim. pr. VI, 1929, 1163.
²) Izv. I. F. Kh. A. VI, issue 2, 389.
II. Method of Work
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Observation of the change in concentrations was carried out by determining specific gravities; at the corresponding temperature, using a Renard pycnometer, the data were recalculated from a table into degrees Baumé (Bé).
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Samples of the liquid phases for analysis were taken with a pipette with a cotton filter, slightly warmed to \(30^\circ\mathrm{C}\), and weighed in weighing bottles with ground-glass stoppers.
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The evaporated water was accounted for by weighing, which made it possible, taking into the calculation the salts remaining in the liquid phase, to compute the pure solvent and thereby approach the degree of evaporation of the brine. In addition, the evaporation of the brine was checked, in the precipitation of sodium chloride, by the non-precipitating salt—magnesium chloride.
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Before analysis, the sample of solid phases was sucked on a Büchner funnel at \(25^\circ\mathrm{C}\) and pressed between sheets of filter paper. In the calculations the coating of salts from the liquid phases was taken into account. The amount of adhering liquid phase was determined from the moisture content of the sample, by drying with soda at \(180^\circ\mathrm{C}\).
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Chemical analyses were carried out according to the following procedure:
a) Determination of the dry residue by Efremov’s method—drying the brine sample with soda at \(180^\circ\mathrm{C}\) to constant weight.
b) Determination of \(\mathrm{SiO_2}\), \(\mathrm{Al_2O_3}\), and \(\mathrm{Fe_2O_3}\) by the usual gravimetric method.
c) Determination of Ca—by the gravimetric method, by double precipitation in the form of \(\mathrm{CaC_2O_4}\).
d) Determination of magnesium by the gravimetric method—by precipitation from hot solutions.
e) Determination of \(\mathrm{SO_4}\) by the gravimetric method, by precipitation with \(\mathrm{BaCl_2}\).
f) Determination of chlorine by titration with \(\mathrm{AgNO_3}\), by Mohr’s method.
g) Total alkalinity by titration with \(0.1N\ \mathrm{HCl}\) with methyl orange.
h) The amount of sodium was calculated from the excess of anions over cations, except for important transition points, where the alkalis were determined experimentally.
In the calculations only the ions \(\mathrm{Na}\), \(\mathrm{Mg}\), \(\mathrm{SO_4}\), and \(\mathrm{Cl}\) were taken into consideration, which combined into salts. The ions \(\mathrm{HCO_3}\), \(\mathrm{Ca}\), \(\mathrm{K}\), and \(\mathrm{Br}\) were omitted from the calculation, since their insignificant presence does not have a noticeable effect on the equilibrium of the system. Thus, the system was reduced to a 4-component one. We selected the components \(\mathrm{MgCl_2}\), \(\mathrm{NaCl}\), \(\mathrm{MgSO_4}\), and \(\mathrm{H_2O}\).
III. Results
At our disposal was brine from Lake B. Yarovoe, collected in July 1931; density \(16.2^\circ\) Baumé, specific gravity 1.127, with the following chemical composition in weight percent per 100 grams of brine:
\[ \begin{aligned} \mathrm{Na} &= 4.52 \qquad & \mathrm{Cl} &= 9.94 \\ \mathrm{Mg} &= 1.16 \qquad & \mathrm{SO_4} &= 0.58 \\ \mathrm{Ca} &= 0.04 \qquad & \mathrm{HCO_3 + CO_2} &= 0.04 \\ \mathrm{K} &= \text{traces} \qquad & \mathrm{Br} &= 0.02 \end{aligned} \]
and with a solid residue of 16.26 grams. The table given below shows the course of evaporation and the change in salt composition. After the corresponding calculation, the data, in moles per 1000 moles of water, were plotted on the horizontal projection of N. S. Kurnakov’s equilibrium diagram.
Comparing the data of the table, one may draw a conclusion as to at what concentration and in what sequence the crystallization of salts from the brine of the lake under our study occurs during isothermal evaporation.
Conclusion.
Summarizing the foregoing, the following conclusions may be drawn:
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The crystallization of common salt begins at 25—25.4° Baumé. The concentration by this moment has increased approximately twofold.
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The crystallization of common salt continues in pure form up to 30.3 Baumé. (Points of the diagram 1, 2, 3, 4).
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With further concentration of the brine, heptahydrated magnesium sulfate joins the precipitating common salt.
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The crystallization of common salt together with magnesium sulfate continues up to 33.8° Baumé. By this moment the brine has been concentrated approximately tenfold (point 5).
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From 33.8° Baumé onward, hexahydrated magnesium sulfate crystallizes simultaneously with common salt. Owing to the low value of the vapor pressure and the high viscosity of the brine, further evaporation is greatly hindered. By this moment the common salt separates almost entirely, in the form of the finest crystals, which remain suspended for a long time, and the solution remains turbid for a long time.
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From 34—37.3° Baumé, hexahydrated magnesium sulfate crystallizes with a large admixture of magnesium chloride, carried away from the mother liquor by the crystals of hexahydrate (points 6, 7, 8, 9).
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At 37.7° Baumé we found in the solid phase almost pure magnesium chloride. The admixture of magnesium sulfate is only 0.6% (points 10, 11, 12).
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The density of the mother liquor at the moment of bischofite separation fluctuates within the limits from 37.5 to 37.7° Baumé, and the solution dries out mainly with the composition of two salts—bischofite, with an insignificant admixture of common salt, potassium, and bromine, which were not determined quantitatively.
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For the practical application of the results of our study, we have submitted a report to the Coal People’s Commissariat of Heavy Industry of the Western Siberian Territory, with the aim of organizing a semi-factory experimental installation on Lake B. Yarovoe, at which the influence of those natural factors should be clarified on which the choice of the best method of exploiting the lake depends.
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In addition, we have carried out work on the use of concentrated brines with a high content of magnesium chloride for the manufacture of new building materials, which has shown its complete suitability for this purpose. The results of the study are printed in this same issue.
Table 1
Course of change of the salt composition of spring water during isothermal evaporation
| No. of observation | Density \(d\), g/cm\(^3\) | Density \(p\), g wt. | Ions per 100 g, wt. %: Na | Ions per 100 g, wt. %: Cl | Ions per 100 g, wt. %: Mg | Ions per 100 g, wt. %: SO\(_4\) | Salt content per 100 g of brine: NaCl | Salt content per 100 g of brine: MgSO\(_4\) | Moles per 1000 g water: NaCl | Moles per 1000 g water: MgSO\(_4\) | Moles per 1000 g water: MgCl\(_2\) | Sum: mole equiv. | Sum: wt. | Metamorphization coefficient | Solid phases |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| — | 1,127 | 16,2 | 4,53 | 9,94 | 1,15 | 0,58 | 11,48 | 0,71 | 21,12 | 1,27 | 9,08 | 31,41 | 16,21 | 0,14 | Natural composition |
| 1 | 1,214 | 25,4 | 7,23 | 15,28 | 1,62 | 0,90 | 18,46 | 1,14 | 37,87 | 2,27 | 13,77 | 53,91 | 25,07 | 0,16 | NaCl |
| 2 | 1,230 | 26,9 | 4,86 | 16,32 | 3,37 | 1,32 | 12,34 | 1,68 | 25,63 | 3,39 | 30,33 | 59,35 | 25,92 | 0,14 | " |
| 3 | 1,246 | 28,5 | 3,50 | 16,74 | 4,33 | 1,74 | 8,90 | 2,22 | 18,62 | 4,51 | 39,05 | 62,18 | 26,33 | 0,14 | " |
| 4 | 1,266 | 33,3 | 1,73 | 18,61 | 6,16 | 2,74 | 4,39 | 3,48 | 9,57 | 7,36 | 57,07 | 74,00 | 29,24 | 0,13 | " |
| 5 | 1,274 | 31,0 | 0,62 | 19,14 | 6,96 | 2,83 | 1,51 | 3,55 | 3,30 | 7,70 | 65,28 | 76,28 | 29,55 | 0,12 | NaCl + MgSO\(_4\cdot 7\)H\(_2\)O |
| 6 | 1,306 | 33,8 | 0,05 | 21,29 | 8,01 | 2,91 | 0,13 | 3,71 | 0,30 | 8,20 | 79,36 | 87,84 | 31,26 | 0,10 | NaCl + MgSO\(_4\cdot 6\)H\(_2\)O |
| 7 | 1,315 | 34,6 | — | 21,91 | 8,10 | 2,37 | — | 3,05 | — | 6,75 | 82,18 | 88,93 | 32,40 | 0,10 | " |
| 8 | 1,321 | 35,1 | — | 22,21 | 8,53 | 2,54 | — | 3,18 | — | 7,10 | 84,00 | 91,10 | 32,94 | 0,10 | " |
| 9 | 1,349 | 37,3 | — | 23,54 | 8,74 | 2,58 | — | 3,32 | — | 7,62 | 85,13 | 92,75 | 34,86 | 0,10 | " |
| 10 | 1,354 | 37,7 | — | 24,51 | 9,14 | 3,13 | — | 3,91 | — | 9,25 | 98,57 | 107,82 | 36,86 | 0,12 | NaCl + MgSO\(_4\cdot 6\)H\(_2\)O MgCl\(_2\cdot 6\)H\(_2\)O |
| 11 | 1,354 | 37,7 | — | 25,01 | 9,20 | 2,80 | — | 3,50 | — | 8,31 | 100,5 | 108,81 | 37,01 | 0,10 | " |
| 12 | 1,354 | 37,7 | — | 25,13 | 9,19 | 2,23 | — | 2,78 | — | 6,36 | 101,9 | 108,28 | 36,85 | 0,08 | " |
| 13* | — | — | — | 24,19 | 9,16 | 3,39 | — | 4,23 | — | 10,00 | 98,43 | 108,43 | 37,04 | 0,13 | " |
*) The brine with this composition is highly viscous.
Table No. 2
Beginning of the charge
Composition of liquid phases, wt.%
| Experiment No. | Concentration, °Bé | NaCl | MgSO₄ | MgCl₂ | KCl | Cl | Mg | SO₄ | Σ | Metamorphization coefficient | Degree of thickening of brine |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 25.4° | 15.28 | 0.90 | 1.62 | 7.23 | 18.46 | 5.17 | 1.14 | 25.07 | 0.20 | 1.9 times |
| 2 | 25.4° | 16.00 | 1.08 | 2.26 | 6.62 | 16.81 | 7.78 | 1.37 | 25.94 | 0.18 | 2 times |
| 3 | 25° | 15.80 | 0.85 | 2.06 | 6.61 | 16.79 | 7.53 | 1.06 | 25.38 | 0.14 | 1.9 times |
Table No. 3
End of the charge of the main mass of common salt.
Composition of liquid phases, wt.%
| Experiment No. | Concentration, °Bé | Cl | SO₄ | Mg | Na | NaCl | MgCl₂ | MgSO₄ | Σ | Metamorphization coefficient | Degree of thickening of brine | Solid phase |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 33.5° | 19.88 | 3.05 | 7.51 | 0.09 | 0.23 | 26.45 | 3.88 | 30.56 | 0.14 | 10.9 times | NaCl + MgSO₄·7H₂O |
| 2 | 33.8° | 21.29 | 2.91 | 8.01 | 5.05 | 0.13 | 28.42 | 3.71 | 32.26 | 0.13 | 10.5 times | NaCl + MgSO₄·7H₂O |
| 3 | 34.2° | 23.81 | 2.84 | 8.90 | 0.05 | 0.13 | 31.90 | 3.78 | 35.50 | 0.11 | — | — |
| 4 | 34.4° | 19.31 | 2.88 | 7.41 | 0.05 | 0.13 | 25.63 | 3.79 | 29.42 | 0.14 | — | — |
“B. Yarovoe” 25°C.
Horizontal projection of the mutual-equilibrium diagram:
\[ \mathrm{Na_2Cl_2} + \mathrm{MgSO_4} \rightleftarrows \mathrm{Na_2SO_4} + \mathrm{MgCl_2} \]
at 25°C. The course of crystallization is shown →
Labels in the diagram:
- \(\mathrm{MgCl_2}\)
- \(\mathrm{MgSO_4 \cdot 6H_2O}\)
- \(\mathrm{MgSO_4 \cdot 7H_2O}\)
- \(\mathrm{MgSO_4}\)
- \(\mathrm{NaCl}\)
- \(\mathrm{Na_2Cl_2}\)
- \(\mathrm{Na_2SO_4}\)
- \(\mathrm{Na_2SO_4 \cdot 10H_2O}\)
- \(\mathrm{Na_2SO_4 \cdot MgSO_4 \cdot 4H_2O}\)
Scale marks: 10, 0, 10, 20, 30, 40, 50.
Lake Ebeity
Horizontal projection of the equilibrium diagram:
\[ \mathrm{Na_2Cl_2 + MgSO_4 \rightleftharpoons Na_2SO_4 + MgCl_2} \]
at \(25^\circ\mathrm{C}\)
The course of the crystallization ray is shown by \(\rightarrow\).
Dashed lines are labile fields.
Diagram labels:
- \(\mathrm{MgCl_2}\)
- \(\mathrm{MgSO_4 \cdot 6H_2O}\)
- \(\mathrm{MgSO_4}\)
- \(\mathrm{MgSO_4 \cdot 7H_2O}\)
- \(\mathrm{NaCl}\)
- \(\mathrm{Na_2Cl_2}\)
- \(\mathrm{Na_2SO_4}\)
- \(\mathrm{Na_2SO_4 \cdot MgSO_4 \cdot 4H_2O}\)
- \(\mathrm{MgSO_4 \cdot 4H_2O}\)
- \(\mathrm{Na_2SO_4 \cdot 10H_2O}\)
- \(\mathrm{Na_2SO_4}\)
- \(\mathrm{Na_2SO_4}\) field
- \(\mathrm{Na_2SO_4 \cdot MgSO_4 \cdot 4H_2O}\), main
- Point labels on the crystallization path: \(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15\)
Scale markings: \(0, 10, 20, 30, 40, 50, 100, 150\).
Lake Kulundinskoye.
Horizontal projection of the equilibrium diagram:
\[ \mathrm{Na_2Cl_2 + MgSO_4 \rightleftharpoons Na_2SO_4 + MgCl_2} \]
at \(25^\circ\mathrm{C}\). The course of the crystallization ray is shown by arrows. Dashed lines indicate labile fields.
Labels visible on the diagram:
- \(\mathrm{MgCl_2}\)
- \(\mathrm{MgSO_4 \cdot 6H_2O}\)
- \(\mathrm{MgSO_4 \cdot 7H_2O}\)
- \(\mathrm{MgSO_4}\)
- \(\mathrm{NaCl}\)
- \(\mathrm{Na_2Cl_2}\)
- \(\mathrm{Na_2SO_4}\)
- \(\mathrm{Na_2SO_4 \cdot 10H_2O}\)
- \(\mathrm{Na_2SO_4 \cdot MgSO_4 \cdot 4H_2O}\), labile
- \(\mathrm{Na_2SO_4 \cdot MgSO_4 \cdot H_2O}\) [[unclear: hydrate coefficient/label]]
- Points marked: \(0, 2, 3, 4, 5, 6, 7, IX, XIII\)
- Scale marks: \(0, 0, 10, 20, 30, 40, 50, 100, 150\)