Method for producing strontium hydroxide and byproduct sodium thiosulfate by using strontium sulfide solution

Abstract

The invention belongs to a method for producing strontium hydroxide and a byproduct sodium thiosulfate by using a strontium sulfide solution, and belongs to the field of chemical engineering. According to the technical scheme, the method comprises the following steps: introducing carbon dioxide-removed air into a strontium sulfide solution to carry out oxidation reaction, carrying out hot filtration, and discarding slag to obtain a red water solution; adding alkali into the red water solution to react, cooling, crystallizing, carrying out solid-liquid separation, and washing to obtain a crude strontium hydroxide octahydrate crystal; recrystallizing the crude strontium hydroxide octahydrate crystal, filtering the solution, cooling and crystallizing, carrying out solid-liquid secondary separation to obtain the strontium hydroxide octahydrate crystal, and drying to obtain a strontium hydroxide octahydrate product; mixing the mother solution with the washing solution, then introducing carbon dioxide-removed air or oxygen for secondary oxidation reaction until the end point is that the red water is completely whitened, and filtering and discarding slag; and carrying out concentration, evaporation, cooling crystallization and centrifugal separation on the white water to obtain sodium thiosulfate pentahydrate crystals. The method comprises the following steps: oxidizing yellow water, adding alkali, filtering, cooling, centrifuging and washing to obtain a crude product, and recrystallizing to obtain a refined product.

Description

Technical Field

[0001] The invention relates to a method for producing strontium hydroxide and a byproduct sodium thiosulfate by utilizing a strontium sulfide solution, and belongs to the field of chemical industry. Technical Background

[0002] The utilization of strontium has attracted more and more attention. Strontium hydroxide, as a basic raw material for strontium salts, has been used more and more, and various production methods have continued to emerge in a large number of applications.

[0003] The method of producing strontium hydroxide and byproduct sodium thiosulfate from strontium sulfide is an economical, reasonable, simple, easy to control and easy to operate production process. At present, there is no clear technical solution for how to use strontium sulfide (alkaline earth metal sulfide) solution to produce strontium hydroxide (alkaline earth metal hydroxide) and byproduct sodium thiosulfate (alkaline earth metal thiosulfate). The existing solution has a complicated production process, a large amount of caustic soda, and it is difficult to effectively utilize wastewater. Summary of the invention

[0004] In view of the above problems, the present invention provides a method for producing strontium hydroxide and byproduct sodium thiosulfate by utilizing strontium sulfide solution, wherein strontium hydroxide and byproduct sodium thiosulfate are obtained by directly processing in strontium-containing yellow water.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for producing strontium hydroxide and a byproduct sodium thiosulfate using a strontium sulfide solution, comprising the following steps: 1) Passing carbon dioxide-removed air or oxygen into the strontium sulfide solution for oxidation reaction, hot filtering and discarding the residue to obtain a red aqueous solution; 2) adding alkali to the red aqueous solution in step 1) to react, cooling and crystallizing, performing solid-liquid separation, and washing to obtain crude strontium hydroxide octahydrate crystals, and the mother liquor is set aside; 3) Recrystallizing the crude strontium hydroxide octahydrate crystals obtained in step 2), filtering the solution and cooling it for crystallization, performing secondary solid-liquid separation to obtain strontium hydroxide octahydrate crystals, and drying to obtain strontium hydroxide octahydrate product; 4) Mix the mother liquor and washing liquid in step 2) together, and then introduce air or oxygen to remove carbon dioxide for secondary oxidation reaction, until the end point is that the red water completely turns white, and filter and discard the residue; 5) The white water from step 4) is concentrated and evaporated to 48-51Be, cooled for crystallization and centrifuged to obtain sodium thiosulfate pentahydrate crystal product, and the obtained mother liquor is added to step 4) for recycling.

[0006] According to the method for producing strontium hydroxide and byproduct sodium thiosulfate using strontium sulfide solution, in step 1), the mass concentration of strontium sulfide in the strontium sulfide solution is 60-240 g / L, the strontium sulfide solution is pumped into the reactor a, the temperature is controlled between 50-90 degrees Celsius, and air is continuously added to remove carbon dioxide for oxidation reaction at a rate of 15m 3 / minute, when V2 dropped from 39.8112 g / L to 19.9056 g / L, and from 154.10808 g / L to 77.0540 g / L, about half of the initial value, the oxidation reaction ended and a red aqueous solution was obtained.

[0007] According to the method for producing strontium hydroxide and by-product sodium thiosulfate using strontium sulfide solution, the red aqueous solution in step 1) is immediately filtered at the end of the reaction, and the red aqueous solution is added into the reactor b, and alkali is added to continue the reaction, while cooling and crystallizing to a temperature of about 5-10 degrees Celsius, standing for 0.2-2h, centrifuging for solid-liquid separation, and washing to obtain crude strontium hydroxide octahydrate crystals.

[0008] According to the method for producing strontium hydroxide and by-product sodium thiosulfate using strontium sulfide solution, the crude strontium hydroxide octahydrate crystals in step 3) are redissolved to 90° C., and then a flocculant polyacrylamide is added. The precipitation is filtered and then cooled, and the crystals are crystallized to about 5-10° C. and allowed to stand for 0.2-2 hours. The crystals obtained after solid-liquid separation are dried to obtain the product Sr(ou)2·8H2O.

[0009] According to the method for producing strontium hydroxide and by-product sodium thiosulfate using strontium sulfide solution, the specification of polyacrylamide is an anion molecular weight of 8 million.

[0010] According to the method for producing strontium hydroxide and byproduct sodium thiosulfate using strontium sulfide solution, the mother liquor in step 4) is added to the reactor c, and air from which carbon dioxide is removed is continuously added to the reactor c for secondary oxidation reaction, and the end point is when the solution changes from red to white.

[0011] According to the method for producing strontium hydroxide and byproduct sodium thiosulfate using strontium sulfide solution, the filtered solution in step 4) is concentrated and evaporated to 48-52Be, filtered and then cooled, cooled and crystallized. When the temperature is about 5-20 degrees, the crystal product sodium thiosulfate is obtained by centrifugation.

[0012] The present invention changes the disadvantages of the traditional production process, which is complicated. After directly obtaining yellow water, the process is oxidized, alkali is added, filtered, cooled, centrifuged, washed, and a crude product is obtained, and a fine product is obtained by recrystallization. The characteristics of this process are that the production process is simple and easy, the amount of caustic soda used is reduced, and energy is saved. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0014] The specific contents of the present invention are further described below: The present invention uses a strontium sulfide solution to produce strontium hydroxide and a byproduct of sodium thiosulfate, which is a method for extracting alkaline earth metal sulfides containing strontium sulfide to prepare strontium hydroxide and a byproduct of sodium thiosulfate. The alkaline earth metal sulfide containing strontium sulfide is dissolved in water to form yellow water in the field, which contains Sr(0H)2 and Sr(HS)2. The alkaline earth metal sulfide of strontium sulfide is added to water at a rate of 60-240 g / L to form yellow water, and the initial concentration of Sr(0H) in the yellow water is measured. 2为 V1, Sr (HS) 2为 V2.

[0015] The method of producing strontium hydroxide and byproduct sodium thiosulfate by using strontium sulfide solution comprises the following steps: 1) Pump the yellow aqueous solution containing strontium sulfide into the reactor a, control the temperature between 50-90 degrees Celsius, and continuously add air without carbon dioxide for oxidation reaction at a rate of 15m / s. 3 / minute, when V2 drops from 39.8112 g / L to 19.9056 g / L (or from 15.4180 g / L to 77.0544), and drops to about half of the initial value, it is the end point of the oxidation reaction, and a red aqueous solution is obtained; 2) The red aqueous solution of step 1) is immediately filtered at the end of the reaction, and the red aqueous solution is added into the reactor b, and alkali is added to continue the reaction, while cooling and crystallizing to a temperature of about 5-10 degrees Celsius, standing for 0.2-2 hours, centrifuging for solid-liquid separation, washing to obtain crude strontium hydroxide octahydrate crystals, and the mother liquor is set aside; 3) The crude strontium hydroxide octahydrate crystals in step 2) are redissolved, heated to 90°C, and then a flocculant polyacrylamide is added. After the precipitation is filtered, the temperature is lowered and cooled, and the crystals are crystallized to about 5-10°C and allowed to stand for 0.2-2h. The crystals obtained after solid-liquid separation are dried to obtain the product Sr(ou)2·8H2O; the specification of polyacrylamide is an anion molecular weight of 8 million; 4) Mix the mother liquor and washing liquid in step 2) together, add them to the reactor c, and continuously add air or oxygen to remove carbon dioxide to the reactor c for secondary oxidation reaction. The end point is when the solution changes from red to white, and filter and discard the residue; 5) The white water from step 4) is concentrated and evaporated to 48-51Be, filtered and cooled for crystallization, and centrifuged when the temperature is about 5-20 degrees to obtain sodium thiosulfate pentahydrate crystal product. The obtained mother liquor is added to step 4) for recycling.

[0016] The following is explained based on the production example Production Example: 1. Prepare yellow water with a concentration between 60-240g / L, measure the initial concentration V2 and record it, pump the solution with a temperature between 50-90 degrees Celsius into reactor a, and continue to add air to remove carbon dioxide for oxidation reaction at a rate of 15m 3 / minute, the time is controlled at 67 minutes, when V2 drops to 19.9056 g / L-77.0540 g / L, which is about half of the initial value, it is the end point. Filter while hot, the solution enters the reactor b, sodium hydroxide is added to continue the reaction, and the temperature is cooled to crystallize to about 5-10 degrees Celsius, stand for 0.2-2h, centrifuge for solid-liquid separation, wash to obtain crude crystals, and the mother liquor red water is set aside.

[0017] 2. After the crude crystals are redissolved to 90°C, add flocculant polyacrylamide to precipitate and filter, cool and crystallize to about 5-10°C and stand for 0.2-2h. After solid-liquid separation, the obtained crystals are dried to obtain the product Sr(ou)2·8H2O, and the mother liquor containing Sr(ou)2·8H2O is recycled. The amount of polyacrylamide added is determined according to the V2 concentration. When V2 drops from 39.81g / L to 19.905g / L, or from 154.11 to 77.055, the addition of polyacrylamide is stopped.

[0018] 3. The mother liquor red water undergoes a second oxidation reaction, and air that removes carbon dioxide is continuously added to reactor C for a secondary reaction. The end point is when the solution changes from red to white, and the time is about 203.3 minutes of the first oxidation. After filtration, it is concentrated and evaporated to 48-52Be, and then filtered and cooled, cooled, and crystallized. When the temperature is about 5-20 degrees, the crystal product sodium thiosulfate is obtained by centrifugation, and the mother liquor is evaporated to remove the sodium thiosulfate concentration for utilization.

Claims

1. A method for producing strontium hydroxide and sodium thiosulfate as a byproduct using a strontium sulfide solution, characterized in that: The following steps are included: 1) Passing carbon dioxide-removed air or oxygen into the strontium sulfide solution for oxidation reaction, hot filtering and discarding the residue to obtain a red aqueous solution; 2) adding alkali to the red aqueous solution in step 1) to react, cooling and crystallizing, performing solid-liquid separation, and washing to obtain crude strontium hydroxide octahydrate crystals, and the mother liquor is set aside; 3) Recrystallizing the crude strontium hydroxide octahydrate crystals obtained in step 2), filtering the solution and cooling it for crystallization, performing secondary solid-liquid separation to obtain strontium hydroxide octahydrate crystals, and drying to obtain strontium hydroxide octahydrate product; 4) Mix the mother liquor and washing liquid in step 2) together, and then introduce air or oxygen to remove carbon dioxide for secondary oxidation reaction, until the end point is that the red water completely turns white, and filter and discard the residue; 5) The white water from step 4) is concentrated and evaporated to 48-51Be, cooled for crystallization and centrifuged to obtain sodium thiosulfate pentahydrate crystal product, and the obtained mother liquor is added to step 4) for recycling.

2. The method for producing strontium hydroxide and sodium thiosulfate as a byproduct by using strontium sulfide solution according to claim 1, characterized in that: Step 1) The strontium sulfide solution has a strontium sulfide concentration of 60-240 g / L. The strontium sulfide solution is pumped into the reactor a. The temperature is controlled between 50 and 90 degrees Celsius. Air without carbon dioxide is continuously added for oxidation reaction at a rate of 15 m / s. 3 / minute, when V2 drops from 39.8112 g / L to 19.9056 g / L -154.1080 g / L to 77.0540 g / L, and drops to about half of the initial value, it is the end point of the oxidation reaction and a red aqueous solution is obtained.

3. The method for producing strontium hydroxide and sodium thiosulfate as a byproduct by using strontium sulfide solution according to claim 1, characterized in that: In step 1), the red aqueous solution is immediately filtered at the end of the reaction, and the red aqueous solution is added into the reactor b, and the alkali is added to continue the reaction, while cooling and crystallizing to a temperature of about 5-10 degrees Celsius, standing for 0.2-2h, centrifuging for solid-liquid separation, and washing to obtain crude strontium hydroxide octahydrate crystals.

4. The method for producing strontium hydroxide and sodium thiosulfate as a byproduct by using strontium sulfide solution according to claim 1, characterized in that: In step 3), the crude strontium hydroxide octahydrate crystals are redissolved to 90° C., and then a flocculant polyacrylamide is added. The precipitate is filtered and cooled, and then crystallized to about 5-10° C. and allowed to stand for 0.2-2 h. The crystals obtained after solid-liquid separation are dried to obtain the product Sr(ou)2·8H2O.

5. The method for producing strontium hydroxide and sodium thiosulfate as a byproduct by using strontium sulfide solution according to claim 4, characterized in that: The specification of polyacrylamide is anionic 8 million molecular weight.

6. The method for producing strontium hydroxide and sodium thiosulfate as a byproduct by using strontium sulfide solution according to claim 4, characterized in that: In step 4), the mother liquor is added to reactor c, and air from which carbon dioxide has been removed is continuously added to reactor c for secondary oxidation reaction. The end point is when the solution changes from red to white.

7. The method for producing strontium hydroxide and sodium thiosulfate as a byproduct by utilizing strontium sulfide solution according to claim 4, characterized in that: The filtered solution in step 4) is concentrated and evaporated to 48-52Be, filtered and then cooled, cooled and crystallized. When the temperature is about 5-20 degrees, the crystal product sodium thiosulfate is obtained by centrifugation.

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