SU1678771A1 - Process for preparing inorganic matters from sea water - Google Patents

Abstract

The invention relates to the production of mineral substances from seawater and makes it possible to simplify the process, increase its environmental safety, and also increase the purity of the substances obtained. The method is carried out by passing sea water through the sorption material in the Na + form, concentrating the spent solution, electrochemically treating the concentrate, and desorbing the target products. In this case, seawater passes through the natural zeolite clinoptilolite (CL) and carboxyl cation-nitrite (KB) at a volume ratio of 1: 1-1: 100 with a speed of 0.1–0.8 bpm. / h through the CL layer and at a rate of 0.1–20 bpm / h through the KB layer, the desorption of the target products from the CL and its subsequent regeneration are carried out with a concentrate of seawater, and the desorption of substances with a CB is successively acid and alkali obtained during the electrochemical processing of sea water concentrate. 2 Il. J

Description

The invention relates to chemical technology and can be used in the chemical industry and hydrometallurgy for the preparation of salts, hydroxides of sodium, magnesium and calcium, fresh water, acid and chlorine. Sea (ocean) water is one of the most promising sources for the production of mineral compounds. At present, global production of sodium chloride from seawater accounts for 29% of total production, bromine — 70%, magnesium — 60%, and drinking water — 60%.

The aim of the invention is to simplify the process of obtaining minerals from sea water and increase its environmental safety by eliminating the preliminary reagent stage.

water treatment, as well as an increase in the purity of the substances obtained due to the sorption separation of magnesium ions from calcium ions and microcomponents and sodium ions from potassium ions.

The process is carried out by passing sea water through the sorption material in the Na-form, concentrating the treated solution, electrochemical processing of the concentrate, desorbing the target products and regenerating the sorption material, while the seawater is passed through the natural zeolite clinoptilolite (CL) and carboxyl cationite (KB) with their volume ratio of 1: 1-1: 100 with a speed of 0.1-0.8 beats. rpm through a layer of clinoptilolite

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and at a speed of 0, beats. / h through the layer of cation exchanger, desorption of the target products from clinoptilolite and its subsequent regeneration is carried out with seawater concentrate, and desorption of substances from the cation exchanger is carried out successively with acid and alkali, obtained by electrochemical processing of seawater concentrate,

Figure 1 shows the output sorption curves of metal ions from seawater on clinoptilolite with a layer height of L 1 m and values of the linear flow rates I - 0.1; II - 0.5; III - 2.5 m / h; Fig. 2 shows a scheme for the production of mineral substances from sea water.

The method is based on a combination of equilibrium and kinematic properties of clinoptilolite and carboxyl cation exchanger. It has been found that there are process conditions under which, in practice, quantitative separation of magnesium and calcium from seawater on a clinoptilolite layer is achieved. From the output curves of Ca2 + and Md2 sorption shown in Fig. 1, it can be seen that at certain values of the linear flow rate, the dynamic exchange capacity for magnesium is almost zero with almost complete absorption of calcium from 30 beats. sea water. This is due to the difference in the sorption kinetics of magnesium and calcium. When the flow is too slow, redistribution occurs: the absorption of magnesium ions on clinoptilolite due to the partial displacement of calcium ions. At high linear speeds, there is no separation at all due to the slippage of both magnesium and calcium. If, following the clinoptilolite layer, a carboxyl cation exchanger layer is put in such a way that a solution is fed from the first to the second sorbent before Ca breakthrough (shaded part in Fig. 1), and if the volume ratios and layer heights are chosen in such a way that the sorbents are optimally taken into account and the kinetic properties of the carboxyl cation exchanger (very different from the properties of clinoptilolite), it is possible to implement a process in which:

Calcium and potassium are extracted from the seawater on the clinoptilolite layer, micro-components, in particular iron ions are absorbed, and complete removal of mechanical impurities occurs;

on the carboxyl cation exchanger, the extraction of magnesium ions occurs, when the cation exchanger passes into a pure magnesium form, s, during regeneration, a highly concentrated solution of magnesium salt is obtained, only pure sodium salt solution passes through the layer of carboxyl cation exchanger;

The sodium salt solution is concentrated (fresh water is obtained), part of the concentrate is periodically used for regeneration of clinoptilolite, the main part is electrolytically processed to produce acid and alkali, part of the acid and alkali is used to regenerate the carboxyl cation exchanger and release magnesium hydroxide. Such a process can be implemented on the basis of the proposed method.

The seawater is passed through a clinoptilolite column 1 (see Fig. 2) in a specific mode, while calcium and potassium ions are sorbed. A solution containing only magnesium and sodium ions is fed to a system consisting of three columns 2-4 loaded with carboxyl cation exchanger (CB). With the passage of the solution through column 2 (KB in the Ma + form), there is a quantitative separation of the magnesium ion from the solution and the transition of the cation exchanger into the MD2 + form. In column 3, the MD is expelled from the CB in the form of a solution of hydrochloric acid to obtain a solution of MgCl2 and cation exchanger in the H + form. In column 4, the cation exchanger is regenerated with alkali to obtain a CB in the original Na-form. The column system 2-4 can work both according to the scheme with a stationary layer of sorbent with periodic replacement of the waste column with the regenerated one, and according to a step-countercurrent scheme with the movement of the cation exchanger from the column into the column. The solution passed through column 2, containing only sodium cations, is directed to concentration.

Concentration (see Fig. 2) is carried out in two stages: first on the electrodialysis apparatus 5, where the concentration and the production water are 4 times concentrated, and then on the evaporator 6, where further concentration is carried out until a 35% solution is obtained NaCI and pure water. (Concentration can also be carried out in one stage only on evaporators). The resulting brine is sent for electrolysis according to the industry standard scheme. The electrolytic alkali solution obtained in the electrolyzer 7 is sent to the evaporator 8 to separate the NaCI and to the furnace 9 to separate the NaOH. The first is dissolved in water and returned to the electrolyzer. Chlorine gas containing bromine impurities is sent to a desiccant 10 and a heat exchanger 11 cooled with raw seawater to separate

Brz and is directed to reactor 12, where hydrogen is also directed from the electrolyzer. The resulting HCl gas is irrigated with water in the reactor 13 to produce concentrated hydrochloric acid. Part of the acid is diluted with water (approximately to a concentration of 2-3 g-eq / l HCl), the resulting solution is desorbed with MD2 from the carboxyl cation exchanger in column 3. A part of the alkali is dissolved to obtain a diluted (1N) solution used to regenerate the cation exchanger in column 4, and to obtain a concentrated alkaline solution (10N) used for precipitating Mg (OH) 2 from the MgCla solution. The deposition is carried out in the reactor 14, separated into liquid and solid phases on the separator 15, MD (OH) 2 in the form of a paste is sent to the furnace 16, where a dry product is obtained - magnesium hydroxide. The NaCI solution, separated by the separator, is returned to the evaporator 6. Part of the NaCI solution obtained on the electrodialyzer 5, with a concentration of 2 g-eq / l, is sent back to the regeneration of clinoptilolite. Carbon dioxide is passed through the regenerate in the reactor 17 by adding alkali to precipitate calcium carbonate. After filtering or settling, the latter is calcined in a furnace 18 to obtain quicklime and regenerate CO. The solution after precipitating CaCO3, containing sodium and potassium ions in a ratio of 10: 1, is directed successively to the evaporator 19, the electrolyzer 20, the evaporator 21 and the furnace 22 to obtain technical alkali. The circuit is closed and does not require the use of imported reagents.

Example 1. a) Raw seawater containing 0.4 g-eq / l NaCI, 0.12 g-eq / l MgCl2.0.02 g-eq / l CaCl2, 0.01 g-eq / l KCI, as well as microcomponents in various concentrations, are passed at a rate of 12 l / h through two successive columns. In the first column - a layer of clinoptilolite in the Na-form, I 100 cm, S 314 cm2, the linear velocity of the solution transmission - 0.38 m / h. (The average grain radius is 0.5 mm sorbental). In the second column, there is a layer of carboxyl cation exchanger KB-4 in No. + -form, I 200 cm, S 11.3 cm2, the linear velocity of the solution transmission is 10.6 m / h. The ratio of sorbent volumes is 14: 1. The process continues until the detection of the breakthrough of MD2 + ions at the level of g-eq / l (0.1% of the initial content) at the exit from the second column, which corresponds to passing through the system 57 l of the solution and the duration of the process 4.75 h.

b) The column with the spent carboxyl cation exchanger is replaced with exactly the same column with fresh cation exchanger in the No. 4 form and water is continued under the specified conditions. After passing 57 liters of seawater, the column is changed again. This process continues until 855 liters of solution pass through the system. The past solution has the composition, r-ion / l: Na + 0.55; SG 0.54; SO2 0.01; Calcium, magnesium, iron and potassium ions are not detected by atomic spectroscopy. This solution is sent to concentration and electrochemical processing to produce alkali and acid. The duration of the entire process is 71.25 hours. In this case, the column with carboxyl cation exchanger is worked out 15 times before treating the column with clinoptylolite,

c) After testing the carboxyl cation exchanger, 3.75 liters of 2.5N are passed through the column. HCI solution at a rate of 2 l / h, and then 1 l of fresh water at the same rate. The first fraction of the solution flowing out of the column before the breakthrough of MD2 + at the level of 10 r-ion / l is collected in a separate container. The MgCl2 content in the rest of the solution obtained (3.75 L) is at least 2 g-eq / l (100 g / l). The content of CaCte is not more than 0.1 wt.% With respect to MgCl2. After working up, the cationite is converted to the hydrogen form. The degree of desorption of magnesium is not less than 95%.

d) Deposition of MD (OH) g is carried out by adding to the resulting solution 800 ml Yun. NaOH solution. The precipitate is separated in a centrifugal separator, again separated from 1 l of fresh water and dried at 100 ° C. The yield of Md (OH) 2 is 220 g per one cycle of carboxyl cationite or 3.3 kg per one full cycle of clinoptilolite. A solution above the precipitate (4.55 l) containing 1.75 g-eq / l of NaCl and an admixture of NaOH is combined with the washings and collected in a separate container.

e) Through a column with carboxyl cation exchanger in hydrogen form, 7 l 1 n are passed. NaOH solution at a rate of 5 l / h, water (5 l) passed through the column is returned to it for washing, and we end up with 7 l of a weakly alkaline solution of NaCl, pH 13. This solution is combined with all the washings and solutions obtained at the stage x C) and d), neutralized with a solution of HCI to a neutral environment. The resulting NaCl solution is directed along with the solution obtained in stage b) to concentration and electrochemical processing. The output of products for one cycle of clinoptilolite mining will be 55 m

fresh water, 18.8 kg of NaOH without KOH impurities and 47 kg of 37% HCI solution. At the same time, recycling reagents for own needs (regeneration and washing of KV-4 cation exchanger and precipitation and washing of Md (HE will be: HCI - 30%, NaOH - 57%, NaO - 3.5% of the amounts of the corresponding products. Column with cation exchanger КВ-4 in Na + form is used to replace the spent cation exchanger in stage b).

e) After completion of stage b), 56 l 2 N is passed through the column with clinoptilolite. NaCl solution at a rate of 15 l / h and 15 liters of seawater at the same rate. The resulting solution (56 l) has the composition, g-eq / l: NaCl 1,5; COP 0.15; 0.32; MgCte 0.25. 10 n is added to the solution in small portions. NaOH solution with simultaneous transmission of gaseous COz so that the pH value of the solution does not exceed 9. At the same time, there is a quantitative precipitation of CaCOz with an impurity of not more than 5% Mg (OH) a. Alkali solution consumption 1.85 l. The precipitate is separated by filtration and sent to calcination to obtain CaO and C02. Another 1.6 L of Yun was added to the solution. NaOH solution. The precipitate MD (OH) 2 is separated in a centrifugal separator, again separated from 2 liters of fresh water and dried at 100 ° C. The yield of products in one complete cycle is, g: CaO 500, Md (OH) and 450 (less than 15% of the amount of the main product obtained in step g). The content of Ca (OH) and not more than 1%. The remaining weakly alkaline solution containing 1.85 g-eq / l of NaC and 0.15 g-eq / l of KCI is combined with wash water, neutralized with a solution of HCl and sent to concentration and a separate electrochemical processing unit to produce acid and alkali NaOH with a COC content of about 12% by weight. The yield of such a product will be 4.5 kg of alkali in one cycle of clinoptilolite mining, i.e. less than 24% of the main pure product obtained after step d),

g) After stage e), the clinoptilolite goes back to the Na-form and the process is repeated as described in stage a).

Example 2. Seawater containing 0.4 g-eq / l NaCI. 0.12 g-ccv / l MgCte, 0.2 r-ehv / l CaC12 0.01 g-eq / l KCI, passed through a layer of clinoptilolite B, I 100 cm, S - 314 cm2, with a speed of 3 l / h . (The specific speed is 0.1). The process continues until the leakage of the Ca2 + ion is detected at an output of 10 g-ion / l, which corresponds to the transmission of 600 l of solution. The average magnesium concentration in the passing solution is 0.1 r-ion / l. The column capacity per MgCte is 0.3 g-eq / h, calculated on NaCI -1.35 g-eq / h.

Example 3. The process is carried out as described in Example 2, except

which is a pass rate of 0.38. The volume of the missed solution to breakthrough Ca 855 l. The average concentration of the MD ion in the passing solution is 0.12 r-ion / L. The performance of the column in the calculation of MgCIa

0 1.44 g-eq / h, based on NaCI - 5.4 g-eq / h.

Example 4. Conduct the process as

described in example 2 except

that the transmission rate of seawater is 25

l / h (speed in specific volumes - 0.8).

5 The average concentration of the MD2 + ion in the passing solution is 0.5 r-ion / l, the volume of the missed solution until the breakthrough of the Ca2 ion + 30 l. Capacity of the column on MgCl2 is 1.25 g-eq / h,

0 EXAMPLE 5. The process is carried out as described in Example 2, except that the transmission rate of seawater is 1. The volume of the missed solution to breakthrough 15l (no sorption).

5 EXAMPLE 6 The process is carried out as described in Example 2, but with a seawater flow rate of 0.05. The productivity of the column in terms of MgCIa is 0.15 g-eq / h, which is 10 times more expensive

0 compared to example 3.

In the remaining cases, the process is carried out as described in Example 4, except that the ratios of the volumes of sorbents: clinoptilolite (CL) and carboxy-5 of strong cationite (KB) and the transmission rate of seawater in specific volumes per hour () are changed. Download clinoptilolite 31.4 liters. Acid and base costs are given for a cation exchanger recovery rate of 95%, with

The process was carried out under conditions similar to those in Example 1. From the results obtained, it follows that with an increase in the ratio of sorbents KB-4 and clinoptilolite to 100: 1, even at the very minimum rate of increase in the flow of seawater, the alkali consumption to the expected output of NaCI is 90%. At other speeds with a ratio of 100: 1 sorbents, the scheme is no longer closed and requires imported reagents.

0 The same thing happens when increasing the specific flow rate through carboxyl xionite to more than 20.

When the ratio is less than 1: 1, a sufficient amount of the solution is not produced on clinoptilolite to a sufficient amount for further processing at K5-4.

Even at a 1: 1 ratio, at a low rate of 0.1, clinoptilolite is processed faster than carboxyl cation. By reducing the specific speed to

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Compiled by V. Vilinska Q

Editor M.Kuznetsova Tehred M.MorgentalKorrektor S.Shevkun

Order 3180 Circulation: Subscription

VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow. Zh-35, Raushska nab., 4/5

Production and publishing combine Patent, Uzhgorod, Gagarin st. 101

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Claims (1)

Claim The method of obtaining mineral substances from sea water by passing sea water through a sorption material in the No. ⁺ form, concentrating the treated solution, electrochemical processing of the concentrate, desorption of target products and regeneration of the sorption material, characterized in that, in order to simplify the process of obtaining mineral substances, increase it environmental safety and increase the purity of substances, as the sorption material in the No. ⁺ form, use natural zeolite clinoptilolite and carboxyl cation exchange resin while seawater is passed sequentially through clinoptilolite and cation exchanger at their volume ratio of 1: 1-1: 100 at a rate of 0.1-0.8 beats per hour through a layer of clinoptilolite and at a speed of 0.1-20 beats. v / h through a layer of cation exchange resin, desorption of the target products from clinoptilolite and its regeneration is carried out with sea water concentrate, and desorption from the cation exchange resin is carried out sequentially with acid and alkali obtained by electrochemical processing of sea water concentrate. > 1 uionh Qty 27op d-d 'vpog dow _C \ J