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Method for decreasing content of sodium chloride impurities in recovered sodium formate

A technology of impurity content and sodium chloride, applied in the separation/purification of carboxylic acid compounds, etc., can solve problems such as the decrease in yield of hydrosulfite products, poor particle size of hydrosulfite, and adverse effects of hydrosulfite synthesis

Inactive Publication Date: 2012-10-24
湖南中成化工有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When the recovered sodium formate with high sodium chloride impurity content is returned to the hydrosulfite synthesis system as a raw material for production, it will in turn cause the content of sodium chloride in the sodium hydrosulfite synthesis mother liquor to increase, thereby adversely affecting the synthesis of hydrosulfite
[0004] Production practice has proved that in the recovery process of sodium hydrosulfite mother liquor, the content of sodium chloride in the sodium formate recovered in the distillation raffinate concentration process has a greater impact on the quality of sodium hydrosulfite products. When the sodium chloride content in the recovered sodium formate is too high to reach When it is above 9%, the particle size of the produced sodium hydrosulfite is poor and the yield of hydrosulfite product decreases

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0015] A batch of rectification raffinate was taken from the workshop, and the analysis results were: specific gravity 1.108, sodium chloride 33.1 g / L, sodium sulfite 2.1 g / L, sodium thiosulfate 25.3 g / L, sodium formate 197.9 g / L. Add 2500ml of the above-mentioned rectification raffinate to a 1000ml four-necked bottle, heat and concentrate under stirring at a vacuum degree of -0.09Mpa, when the concentration reaches a solution temperature of 105°C, turn off the vacuum, vent, and continue to heat and concentrate to the solution temperature At 130°C, the concentration was stopped, and the material was transferred to a jacketed filter heated and kept warm by steam while it was still hot, and vacuum filtered to obtain 410 milliliters of filtrate, which was transferred to a crystallization reactor with a reflux condenser and stirring. Add 100 ml of methanol, cool and crystallize naturally to 60-70°C, filter with suction and centrifuge, dry the filter cake to obtain solid recovered s...

Embodiment 2

[0017] Accumulatively add 2500 ml of the same rectification raffinate as in Example 1 to a 1000 ml four-neck bottle, heat and concentrate at a concentration vacuum of -0.08Mpa under stirring, when concentrated to a solution temperature of 110°C, turn off the vacuum and vent , continue heating and concentrating to a solution temperature of 135°C, stop concentrating, transfer the material to a jacketed filter heated and kept warm by steam while it is hot, and vacuum filter to obtain 370 milliliters of filtrate, which is transferred to a reflux condenser, Add 95 ml of methanol into the stirred crystallization reactor, cool and crystallize naturally to 60-70°C, filter with suction and centrifuge, dry the filter cake to obtain solids and recover sodium formate, and use chemical analysis to determine sodium chloride, The measured values ​​of sodium sulfite, sodium thiosulfate and sodium formate are 3.7%, 1.4%, 3.7% and 91.2% respectively.

Embodiment 3

[0019] Accumulatively add 2500 milliliters of rectification raffinate identical to Example 1 to a 1000 milliliter four-necked bottle, heat and concentrate at a concentration vacuum degree of -0.085 Mpa under stirring, when concentrated to a solution temperature of 108 ° C, turn off the vacuum, vent, Continue heating and concentrating to a solution temperature of 132°C, stop concentrating, transfer the material to a jacketed filter heated and kept warm by steam while it is hot, and vacuum filter to obtain 390 milliliters of filtrate, which is transferred to a reflux condenser, stirred Add 100 ml of methanol into the crystallization reactor, cool and crystallize naturally to 60-70°C, filter with suction and centrifuge, dry the filter cake to obtain solid recovery of sodium formate, and use chemical analysis to determine sodium chloride and sodium sulfite in recovered sodium formate , sodium thiosulfate and sodium formate, the measured values ​​were 4.3%, 1.7%, 2.5% and 90.5% resp...

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Abstract

The invention relates to a method for decreasing the content of sodium chloride impurities in recovered sodium formate, which is applicable for recovering the sodium formate from a rongalite mother solution. According to the method, sodium chloride is separated out in the concentrating working procedure of a rectified raffinate, and the method comprises the following steps of A. heating the concentrated rectified raffinate to the temperature of 105-110 DEG C under the vacuum degree of -0.08 to -0.09Mpa to separate out the sodium chloride from the raffinate; B. closing the vacuum, emptying, and continuously heating to the temperature of 130-135 DEG C to dissolve the sodium formate which is separated out through crystallization in the vacuum concentrating process of the raffinate; and C. after the temperature reaches to 130-135 DEG C, placing a material into a filter with a jacket, and carrying out vacuum filtration to separate the sodium chloride which is separated out of the material from a material solution; and placing the material solution which is obtained through the filtration into a crystallization kettle, and adding methanol with the volume accounting for about 1 / 4 of that of the material solution to obtain the recovered sodium formate with the low-content sodium chloride impurities through filter-pressing and drying processes after extraction and crystallization. The content of the sodium formate in a recovered sodium-formate product which is obtained by the method is higher than 88 percent, and the content of the sodium chloride impurities is lower than 5 percent.

Description

technical field [0001] The invention relates to a method for reducing the impurity content of sodium chloride in recovered sodium formate, and the method is suitable for recovering sodium formate from sodium hydrosulfite mother liquor. technical background [0002] After nearly 20 years of development, the sodium formate method has gradually replaced the zinc powder method as the most important method for hydrosulfite production. Sodium formate is one of the main raw materials for the production of sodium hydrosulfite by the sodium formate method. In the process of producing hydrosulfite by the sodium formate method, the process of excessive sodium formate is generally used. Only a part of the mother liquor produced by each reaction is recycled for the next synthesis reaction. The excess mother liquor needs Carry out comprehensive recycling. In addition to the solvent methanol, the treated mother liquor also contains inorganic salts such as sodium bisulfite, sodium thiosulf...

Claims

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Application Information

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IPC IPC(8): C07C53/06C07C51/42C07C51/43
Inventor 邓帛辉邓伟国
Owner 湖南中成化工有限公司
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