RU2183202C2 - Method of integrated processing of natural mineralized waters - Google Patents

Abstract

FIELD: chemical engineering. SUBSTANCE: invention relates to production of high-utility mineral substance from natural waters such as associated oil-deposit waters and oceanic waters. Method involves following consecutive stages: mechanical filtration, adsorption isolation of calcium, isolation of magnesium via passage of filtrate through carboxylic cationite in Na+ form, concentrated sodium chloride solution-mediated regeneration of adsorbent followed by treating regenerate to yield carbonates, electrodialysis-mediated concentration of treated water to give secondary solutions and desalted water, and additional strontium carbonate and iodine recovery stages. Stages of selective isolation of calcium, magnesium, and strontium are performed in countercurrent ion- exchange tower with separation of softened water and strontium and magnesium compound-containing brine flows followed by precipitation of magnesium in the hydroxide form by treatment with sodium hydroxide solution, filtration through mechanical filter and treatment of filtrate with sodium carbonate solution to isolate strontium carbonate. Iodine recovery is performed by treating water with hydrochloric acid solution to attain pH 2,0-2,5, adding chlorine water as oxidant in amount corresponding to 1.1 equivalents chlorine per 1 equivalent iodine, and passing solution through anionite AB-17 in Cl- form, which is regenerated with solution containing 65-75 g/l sodium sulfite and 130-150 g/l sodium chloride followed by recovering elementary iodine from regenerate solution. Reagents needed for implementation of process, in particular chlorine water and sodium hydroxide and hydrochloric acid solutions are obtained from the secondary electrodialysis solution via electrolysis in diaphragm electrolyzer. Method provides integrated and economically advantageous technology for recovering high-utility mineral raw materials from natural waters. Additionally recovered from water are strontium and iodine and reagent needed for use in the process. Closed-cycle technology yielding recovered solutes and water is elaborated. EFFECT: enabled efficient recovery of increased number of high-utility water-dissolved chemicals. 2 dwg, 4 tbl

Description

 The invention relates to the field of general chemical technology, mainly to ion exchange, and is intended to produce valuable minerals from natural waters, such as associated water from oil fields, as well as oceanic waters. It is most effective to use the proposed method for extracting valuable microcomponents from the groundwater of the Aptalb-Cenomanian complex of oil production regions.

где x и у - эквивалентные доли каждого из ионов в ионите и растворе, соответственно.A known method of countercurrent ion-exchange separation of strontium and calcium, developed at the Faculty of Chemistry of Moscow State University (AS 1473835, USSR, 4MKI 01 I 47/02, C 01 F 11/24). According to this method, the separation is carried out on the KB-4 carboxyl cation exchanger in the Na ⁺ form, for which the separation coefficient of calcium and strontium a $\genfrac{}{}{0ex}{}{\text{Ca}}{\text{Sr}}$ is 2.5-2.6

where x and y are the equivalent fractions of each of the ions in the ion exchanger and solution, respectively.

Moreover, a $\genfrac{}{}{0ex}{}{\text{Ca}}{\text{Sr}}$ practically does not change when the ratio of components in the solution changes (Gorshkov V.I. et al. Ionic exchange in countercurrent columns. M.: Nauka, 1978. - 224 p.). The treated water is passed through a dense layer of ion exchanger from the bottom up, while the ion exchanger moves from top to bottom. With a certain ratio of water and ionite velocities at the top of the column, a zone is formed free of calcium ions, Ca ²⁺ and containing only Na ⁺ , Sr ²⁺ and Mg ^{2+ ions} . Magnesium is precipitated in the form of hydroxide during the treatment of water with sodium hydroxide. Then strontium is precipitated in the form of carbonate after treatment with a soda solution. The regeneration of cation exchanger is carried out 2.5 N. sodium chloride solution, NaCl. Due to the high concentration, Na ⁺ ions displace doubly charged Ca ²⁺ , Mg ^2+, and Sr ²⁺ ions from the resin, and the NaCl solution should be in significant excess. Water at the end of the cycle contains only Na ⁺ ions.

 The disadvantage of this method is that its implementation requires large investments, which can pay off at sufficiently high concentrations of strontium in water, at least 200 g / t, or with the associated extraction of some other valuable components.

There is a method of complex processing of industrial iodine-bromine waters (Complex processing of mineralized water / Pilipenko A.G. et al. - Kiev: Naukova Dumka, 1984. - 284 p.). According to this method, in the first stage of processing hydromineral raw materials, iodine is extracted by adsorption on activated carbon or on ion-exchange resins. In the second stage, bromine is extracted by air desorption. Then the solution is treated with 70% calcium oxide to a pH of 7.5-8. After filtering and washing, the resulting precipitate containing calcium, magnesium, manganese, boron, chlorine, copper, zinc and iron can be used as micronutrient for vegetable crops on acidic soils. The filtrate is again treated with calcium oxide at a rate of 15 g / m ³ and magnesium oxide is isolated, which contains 98% of the basic substance. At the final stage, by thermal evaporation, food grade sodium chloride is obtained. In this case, the indicator of integrated water use reaches 97%.

 This method has the disadvantage that only iodine and bromine are extracted from trace elements, and residual brines are pumped into absorbing horizons, which increases the cost of production. This method is cost-effective only if the iodine content is at least 18 g / t and bromine is at least 200 g / t.

Closest to the proposed method in terms of technical nature and the achieved result is a method of complex processing of sea water (Pat. 2089511, Russia, 6MKI C 02 F 1/42; 1/28). This method is selected as a prototype. According to this method, water passes through the following successive processing steps: mechanical filtration through natural zeolite; calcium excretion by passing the filtrate through a modified artificial zeolite in the Na ⁺ form; regeneration of zeolites with a concentrated NaCl solution followed by processing of the regenerate to lime, bromine evolution by electro-adsorption on modified activated carbon, followed by its regeneration; a magnesium evolution step by passing the solution through a carboxyl cation exchanger in a Na ⁺ form; regeneration of the carboxyl cation exchanger with a solution of sodium carbonate, followed by spontaneous precipitation of magnesium carbonate from the regenerate; the allocation of boron by passing the solution through a weakly basic anion exchange resin in the CO ₃ ² -form; obtaining fresh water by electrodialysis, thermal distillation and membrane distillation to obtain secondary brines and their processing in order to obtain sodium salts by vacuum evaporation.

 The specified method has the following disadvantages. The aim of the method is to obtain fresh water, and the associated extraction of bromine and boron increases the quality of fresh water, but the economic feasibility of their extraction is not calculated. The method at the stage of magnesium extraction involves the regeneration of the sorbent with a solution of sodium carbonate and subsequent spontaneous separation of magnesium carbonate from the resulting supersaturated solution, while, firstly, in connection with the duration of the last process, the method requires significant material costs for its technological implementation, and secondly, the product It will be contaminated with strontium carbonate, which is present in sea water and other natural waters and is associated with calcium and magnesium.

 Thus, the objective of the invention is to develop a comprehensive and cost-effective technology for the extraction of valuable mineral raw materials from natural waters.

 The technical result achieved by the invention is that additional strontium and iodine are extracted from water, as well as chemical reagents that are necessary for use in the technology. Those. The technology of a complete closed cycle with the release of extracted components and water has been developed.

To solve this problem, the method of complex processing of natural mineralized water, like the prototype, includes successive stages of mechanical filtration, a stage of calcium adsorption, a stage of magnesium separation by passing the filtrate through a carboxyl cation exchange resin in a Na ⁺ form, regeneration of the adsorbent with a concentrated solution of sodium chloride, followed by treatment regenerate to carbonates; concentrate waste water by electrodialysis to obtain secondary brines and demineralized water. Unlike the prototype, additionally, the stages of separation of strontium and iodine carbonate are carried out, while the stage of selective separation of calcium, magnesium and strontium is carried out in a countercurrent ion-exchange column with separation of streams of softened water and brine containing compounds of strontium and magnesium, followed by precipitation of magnesium in the form of hydroxide by treatment with a solution of sodium hydroxide, filtration through a mechanical filter and treatment of the filtrate with a solution of sodium carbonate in order to separate strontium carbonate, the stage of separation of iodine is carried out by treating water solution with hydrochloric acid to pH 2,0-2,5, addition of an oxidant bleach in water at the rate of 1.1 eq. chlorine per 1 eq. iodine and passing the solution through anion exchange resin AB-17 in the Cl ^- form, the regeneration of which is carried out with a solution containing 65-75 g / l sodium sulfite and 130-150 g / l sodium chloride, followed by the isolation of elemental iodine from the regenerate, and the necessary the method, chemicals, in particular chlorine water, solutions of sodium hydroxide and hydrochloric acid are obtained from the secondary electrodialysis brine by electrolysis in a diaphragm electrolyzer.

 The proposed method of complex processing of natural mineralized waters differs from previously known by a number of significant features, the essence of which can be explained as follows. The authors carried out an economic analysis and determined that strontium and iodine are the most valuable trace elements from an economic point of view in the associated waters of oil fields.

 A significant feature of the proposed method compared to the prototype is the selective separation of strontium from calcium and magnesium, while in the prototype strontium was not taken into account at all, although the strontium content in the sea water is 10-30 mg / l. The pretreatment and softening of mineralized water with the extraction, in addition to calcium and magnesium, of strontium also increase the productivity of the subsequent electrodialysis concentration of wastewater with obtaining a concentrated solution of sodium chloride as a secondary brine.

 The regimes and concentrations of reagents for the stage of iodine separation were experimentally determined, which make it possible to obtain the highest yield of the product with the least cost, since the necessary chemical reagents are obtained from the treated water.

 An essential feature of the whole scheme in the proposed method for the integrated processing of natural mineralized waters, in contrast to the previously known ones, is the combination and interconnection of all stages of the process, which only in this way provide the possibility of an efficient process as a whole. Thus, the proposed method according to a technical solution, according to the combination and interconnection of all stages in a complex scheme, fully meets the criteria of "novelty" and "significant difference".

 The authors are not aware of any other methods of complex processing of associated water from oil fields, allowing to isolate in pure form all macrocomponents, strontium and iodine with the simultaneous absence of wastewater.

 In the future, the invention is illustrated by a description of the technological scheme shown in figures 1 and 2, and an example of a specific implementation of the method.

 The initial solution (see figure 1), previously passed through a mechanical filter, from the storage tank 7 (made of stainless steel) through the pump 21 is fed into the column 1A. Column 1a is a movable ion-exchange reactor made of steel lined with polyvinyl chloride. It consists of 3 parts: a bunker - I, a working part - II and a collection of spent ionite - III. The initial solution is supplied to the lower part of the working chamber of the reactor under a pressure of 5 atm, rises up through the layer of ion exchanger. Ionite in the reactor also moves, but from top to bottom. The feed hopper is fed with a suspension containing regenerated ion exchanger, and spent ion exchanger is transferred from collector III by means of a screw device to the reactor hopper 1b for regeneration. The ratio of the flow rates of the solution and the ion exchanger is selected in such a way that in the middle part of the column a zone is formed in which calcium ions are already absorbed by the resin, and strontium and magnesium ions are present in the solution. Rising higher in the column, the solution is also cleaned of them, softened water purified from all doubly charged ions is discharged from the upper drainage hole. From the middle, water is removed containing magnesium and strontium, but not containing calcium.

 The reactor 1b is similar in structure to the reactor 1a and is designed to regenerate spent ion exchanger, which is fed to the upper part of the reactor. Regeneration is carried out by treating the ion exchanger with a concentrated solution of sodium chloride (2.5 N NaCl solution), which is fed into the reactor from below. Sodium ions displace divalent metal ions from the ion exchanger, and regenerated ion exits into collection III, and a solution containing divalent metal chlorides (calcium, magnesium and strontium) is discharged from the upper drainage hole of the working part of the reactor. The solution, purified from calcium, from column 1a enters one of the collection reactors 3a or 3b. Reactors are made of stainless steel. In these reactors, magnesium hydroxide is precipitated from the solution by adding sodium hydroxide from the measuring unit 9. Mernik 9 is made of enameled steel and is used to prepare a 40% solution of sodium hydroxide, NaOH and dosed feed it into the collection reactor.

The clarified solution from the collection reactors 3a and 3b is pumped by a pump 19 through a suction filter 14, in which a suspension of magnesium hydroxide is separated into one of the collection reactors 4a or 4b. Their device is similar to that of reactors 3a and 3b. They are intended for the precipitation of strontium carbonate by adding sodium carbonate to the solution from the measurer 10. Mernik 10 is similar to the measurer 9 and is designed to prepare a saturated solution of sodium carbonate, Na ₂ CO ₃ and dosed it into reactors 4a and 4b.

 The clarified solution from the collection reactors 4a and 4b by the pump 20 through the suction filter 15, in which the suspension of strontium carbonate is separated, is fed further to the extraction of iodine (see figure 2).

A solution containing divalent metal chlorides from column 1b is fed to one of the collection reactors 5a or 5b. Their device is similar to that of reactors 3a and 3b. They are intended for the precipitation of calcium, magnesium and strontium carbonates by adding sodium carbonate to the solution from the measurer 11. Mernik 11 is similar to the measurer 9 and is designed to prepare a saturated solution of sodium carbonate, Na ₂ CO ₃ and dosed it into reactors 5a and 5b.

 The clarified solution from the collection reactors 5a and 5b is pumped by a pump 22 to a packed filter 16, where it is cleaned of insoluble carbonate particles and is again used to regenerate the ion exchanger in column 1b.

 Chlorine electrolyzer 17 is designed to produce chlorine, which is necessary for the oxidation of iodide ions to an elementary state. Along with chlorine in the electrolyzer are formed: a solution of hydrochloric acid, necessary in the production of iodine to acidify water; sodium hydroxide solution, necessary in the already described technological cycle for the separation of magnesium in the form of hydroxide; An important by-product is hydrogen, which can be used in the factory or sold to consumers. Chlorine electrolyzer is a standard chemical equipment and is produced by chemical engineering factories.

 Softened water, acidified with hydrochloric acid to a pH of 2.0-2.5 and treated with chlorine at a rate of 1.1 equiv. chlorine per 1 eq. iodine, enters the lower part of the working chamber of the column 2A. The amount of chlorine should be strictly dosed, because with a lack of chlorine, not all iodide ions are oxidized to an elementary state. With an excess of chlorine, iodine is oxidized to iodate ions, which are poorly absorbed by the resin. In both cases, there is a loss of iodine with waste water. Column 2a is a reactor with a moving bed of ion exchanger, similar to the reactors 1a and 1b described above. The treated solution, as well as in the process of strontium separation, rises along the column from the bottom up, and the ion exchanger moves from top to bottom. The iodine contained in the water is absorbed by the ion exchanger, and the water enters the next stage - concentration of the NaCl solution. Concentration of a solution of sodium chloride to a concentration of 2.5 N. (140 g / l) is carried out in an electrodialyzer 18. This solution is necessary for the regeneration of ion exchangers and the operation of a chlorine electrolyzer 17. In addition, the concentrate itself is a commercial product when used as a heavy solution for repairing boreholes. With further processing of the concentrate in the evaporator, food grade table salt can be obtained. In addition to concentrate, a stream of demineralized water is formed in the electrodialyzer, which can be used to feed the boiler room and other factory needs. Electrodialyzer 18 is standard equipment and is manufactured at the Tambov Engineering Plant.

 The spent ion exchanger from the collector of the column 2a is fed through a screw device to the feed hopper of the column 2b, in which it is regenerated with a solution consisting of 70-75 g / l sodium sulfite and 140-170 g / l sodium chloride. In this case, sodium sulfite reduces elemental iodine to an iodide ion, and sodium chloride displaces the iodide ion from the ion exchanger, replacing it with a chloride ion. As our experiments showed, when the concentration of sodium sulfite is less than 70 g / l, not all iodine will be reduced to iodide ions and a lot of iodine will remain in the resin. The use of a solution with a concentration of more than 75 g / l leads to irrational consumption of the reagent. Sodium chloride displaces iodide ions from the resin due to the high concentration of chloride ions in it, therefore, at a concentration of less than 140 g / l, the regeneration of the ion exchanger is sharply slowed down, and the use of a concentration of more than 170 g / l is economically disadvantageous.

 The solutions are prepared in measuring tanks 12 and 13, similar to measuring tank 11. From measuring tanks, the solutions are dosed into the reactor with mechanical stirring 6. It is similar to the reactors 5a and 5b described above. In it, the solutions are mixed and pump 23 is fed into the column of regeneration of ion exchange resin 2b, which is similar in structure to column 2a.

 The solution after regeneration of the ion exchanger, containing up to 14-17 g / l of sodium iodide, enters the tank 8 for accumulation of the concentrate, and then goes for further processing in special reactors in order to isolate elemental iodine.

 The technological scheme has been tested in laboratory conditions.

 Example 1. The research was conducted on the produced water of the Senomanian horizon of the Sovetskoye field of Tomskneft OJSC. The composition of water with a total salinity of 22 kg / t is presented in table 1.

50 l of feed water was passed through a countercurrent ion-exchange column with a diameter of 2 cm and a height of 300 cm, filled with KB-4 cation exchanger in a Na ⁺ form. Received 44.5 liters of softened water and 5.5 liters of strontium concentrate. Regeneration of 1.3 L of an ion exchanger suspension required 22.5 L of NaCl solution. The results of calculating the balance of the system are presented in table 2.

A slight mismatch in the balance can be explained by the fact that a certain amount of ions remains in the resin. As follows from table 2, 58.7% Sr, 16.1% Mg and 1.5 10 ^-2 % Ca went into the concentrate. 12 ml of a 40% NaOH solution was added to the concentrate and 2.92 g of Mg (OH) ₂ , or 1.205 g in terms of Mg, was isolated. Then added 12 ml of a concentrated solution of Na ₂ CO ₃ and allocated 2.22 g of SrCO ₃ or 1,315 g in terms of Sr. The regenerate was treated with 300 ml of a concentrated solution of Na ₂ CO ₃ and 116.11 g of a mixture of Ca, Mg, and Sr carbonates were isolated. Thus, 2.22 g of strontium carbonate (58.4% of the strontium contained in water) and 2.92 g of magnesium hydroxide (16.1% of the magnesium contained in water) were obtained. The iodine concentration in the treated water decreased slightly (from 9.2 to 8.9 g / l).

In the second stage, iodine was concentrated on resin AB-17 in a Cl ^- form in a column with a diameter of 2 cm and a height of 20 cm. Water was pumped through a dense ion exchanger layer from the bottom up, acidifying it with HCl to pH 2.0-2.5 and adding chlorine water as an oxidizing agent at the rate of 5.07 mg of chlorine per 1 liter of water. A solution of Hcl and chlorine water were obtained by electrolysis of 2.5 N. NaCl solution in a laboratory diaphragm electrolyzer. During the adsorption process, the lower resin layer gradually darkened, becoming black-brown. 50 L of water was treated, but iodine was not detected at the column outlet, since it was all absorbed by the resin. The height of the blackened layer was 8.5 cm. Iodine was desorbed with a solution containing 70 g / L sodium sulfite and 140 g / L sodium chloride. Received 0.3 l of concentrate with an iodine content of 1300 mg / l. The results are presented in table 3.

 As follows from table 3, 390 mg of iodine or 87.6% of those present in water passed into the regenerate.

 Softened water, freed from iodine, was passed through an electrodialyzer, after which it was divided into two streams. 5 L of a concentrated NaCl solution with a concentration of 145 g / L and 45 L of water with a NaCl concentration of 0.5 g / L were obtained.

 Thus, in comparison with the prototype, the proposed method allows to extract 58.4% of strontium and 87.6% of iodine in the form of carbonate. It is possible to develop a method for the extraction of other valuable elements, including boron and bromine, but their concentration in the source water is below industrial value.

The results of the calculation of the economic efficiency of the method are given in table 4. The calculations were carried out for one well BKSN-3A of the Sovetskoye field with a debit of Cenomanian water of 8800 m ³ / hour. The calculations did not take into account capital costs for full water treatment (drilling and construction of wells, construction of pipelines, which makes up 60% of the cost of the plant), since all this is already available when extracting from associated water. Prices are average: $ 20 / kg for iodine, $ 6 / kg for strontium carbonate and $ 60 / t for sodium chloride.

 From the table it follows that at a capital cost of $ 2 million, the cost of the resulting product will be $ 3.916 million, i.e. the payback period of the plant is less than 1 year.

Claims (1)

A method for the complex processing of natural mineralized waters, including the sequential stage of mechanical filtration, the stage of calcium adsorption and the stage of magnesium separation by passing the filtrate through the carboxyl cation exchange resin in the Na ⁺ form, regenerating the adsorbent with a concentrated solution of sodium chloride, followed by processing the regenerate to carbonates, concentrating the waste water by electrodialysis with obtaining secondary brines and demineralized water, characterized in that it further conduct st adia of the separation of strontium and iodine carbonate, while the stage of selective separation of calcium, magnesium and strontium is carried out in a countercurrent ion-exchange column with separation of streams of softened water and brine containing compounds of strontium and magnesium, followed by precipitation of magnesium in the form of hydroxide by treatment with sodium hydroxide solution, filtration through a mechanical filter and treatment of the filtrate with a solution of sodium carbonate in order to separate strontium carbonate, the stage of separation of iodine is carried out by treating water with a solution of salt acid to pH 2.0-2.5 with the addition of an oxidant bleach in water at the rate of 1.1 eq. chlorine per 1 eq. iodine and passing the solution through anion exchange resin AB-17 in the Cl ^- form, the regeneration of which is carried out with a solution containing 65-75 g / l sodium sulfite and 130-150 g / l sodium chloride, followed by the isolation of elemental iodine from the regenerate, and the necessary the method, chemicals, in particular chlorine water, solutions of sodium hydroxide and hydrochloric acid, are obtained from the secondary electrodialysis brine by electrolysis in a diaphragm electrolyzer.

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