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Method for recovering and refining salts and alkalis in high-salt hydrazine hydrate solution
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A technology of high salt water and hydrazine hydrate, applied in chemical instruments and methods, hydrazine, alkali metal chloride, etc., can solve problems such as lack of salt separation process, and achieve the effects of simple process, reduced production cost, and easy process
Inactive Publication Date: 2020-02-11
JIANGSU SOPO CHEM +1
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Problems solved by technology
For high-salt wastewater whose solubility in water does not change much with temperature, the content of inorganic salts is much greater than that of inorganic salts whose solubility is more sensitive to temperature changes, there is still a lack of practical salt separation technology
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Embodiment 1
[0031] A method for reclaiming and refining saline-alkali from high-salt hydrazine hydrate solution, comprising the following steps (such as figure 1 shown):
[0032] First, the water quality of a high-salt hydrazine hydrate solution in a chemical company in Jiangsu Province was measured as shown in Table 1:
[0033] Table 1 Water quality of high-salt hydrazine hydrate solution in a chemical company in Jiangsu Province
[0034] serial number project unit value 1 pH none 12.82 2 NaCl g / L 147.12 3 Na 2 CO 3
g / L 80.25 4 Na 2 SO 4
g / L 0.23 5 total salt g / L 248.60 6 TOC g / L 2.59 7 Hydrazine hydrate wt% 4.83
[0035] 1. After evaporating the high-salt hydrazine hydrate solution, crystallize and recover the NaCl crude product at 25°C
[0036] Use a 1000mL glass measuring cylinder to take 1L of high-salt hydrazine hydrate solution and place it in a 90°C electric blast drying oven (model DH...
Embodiment 2
[0064] Steps 1-3 of this embodiment are the same as in Embodiment 1.
[0065] Step 4. Recovery of high-purity Na 2 CO 3 finished product
[0066] Freeze and crystallize the concentrated brine in step 2 at 0° C. (add 0.0200 g of anhydroussodium carbonate crystals per 1 L of concentrated brine) to obtain sodium carbonate crystals. The sodium carbonate crystals were dried at 105°C to constant weight, and then roasted at 600°C for 3 hours. Finally, 21.43g of anhydrous sodium carbonate could be obtained per liter of brine hydrazine hydrate solution. After calculation, the purity of sodium carbonate containing crystal water is 91.06%.
[0067] As can be seen from this embodiment, although adding anhydrous sodium carbonate seed crystal can significantly improve the rate of recovery of sodium carbonate, the sodium carbonate purity that gained contains water of crystallization also significantly descends.
Embodiment 3
[0069] Except the step change of step 3, all the other are the same as embodiment 1.
[0070] Step 3. Refining NaCl Crude Product
[0071] Weigh 2.0000g of the crude sodium chloride product in a crucible, add 1.6g of 37% concentrated hydrochloric acid, then add 2.5g of 30% hydrogenperoxide in the crucible, stir carefully with a glass rod, and let stand at room temperature for 30min. Then it was placed in a muffle furnace, the temperature was raised to 300°C and kept for 2 hours, and finally 1.9566g of sodium chloride product with a purity of 97.83% was obtained.
[0072] As can be seen from this embodiment, the calcination temperature has a significant impact on the purity of the sodium chloride finished product, and the calcination temperature is reduced to 300 ℃ by 600 ℃, and then the purity of the sodium chloride finished product is correspondingly dropped to 97.83% by 99.52%.
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Abstract
The invention discloses a method for recovering and refining salts and alkalis in a high-salt hydrazine hydrate solution. The method concretely comprises the following steps: (1) evaporating the high-salt hydrazine hydrate solution at a high temperature, and crystallizing and recovering a crude NaCl product at room temperature; (2) condensing steam generated during evaporation in step (1), then performing rectification to separate and recover hydrazine hydrate, and enabling a part of condensed water to flow back to a filtrate generated after evaporationcrystallization of NaCl in the step (1)and filtration to obtain concentrated brine containing Na2CO3 and NaCl; (3) refining the crude NaCl product obtained in the step (1) to obtain a high-purity finished NaCl product; (4) freezing and crystallizing the concentrated brine obtained in step (2) to recover a high-purity finished Na2CO3 product; and (5) mixing a liquid residual after freezing crystallization in step (4) with raw water, andthen carrying out evaporation circulation treatment. The method has the advantages of realization of separation of sodiumchloride and sodiumcarbonate in the high-salt hydrazine hydrate solution andefficient purification of sodiumchloride and sodium carbonate, no wastewaterdischarge, and achieving of win-win of environmental protection benefits and economic benefits.
Description
technical field [0001] The invention belongs to the technical field of chemical industry, relates to the technical field of chemical industrial waste water disposal and resource recovery, in particular to a method for recovering and refining saline-alkali from a high-salt hydrazine hydrate solution. Background technique [0002] In recent years, with the rapid growth of my country's economy and the continuous expansion of industrial scale, the amount of wastewater generated in industrial production has also increased rapidly, making the treatment of industrial wastewater face unprecedented challenges. High-salt wastewater is a type of industrial wastewater, which mainly comes from industrial production, seawater utilization and domestic sewage, etc. It has a high salt content (usually contains a total dissolved solidmass fraction ≥ 3.5%), and usually contains a large amount of Cl - , SO 4 2- 、Na + , Ca 2+ and other soluble inorganic salt ions, and some high-salt wastewa...
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