Method for preparing snow melting agent from chlor-alkali salt mud solid waste

Abstract

The application provides a method for preparing snow-melting agent by comprehensively utilizing chlor-alkali salt mud solid waste, and belongs to the technical field of comprehensive utilization of solid waste and inorganic material synthesis. Firstly, the chlor-alkali salt mud is prepared into slurry with water, then under the action of dispersant and acidification aid, concentrated hydrochloric acid is added at one time, then the solution is adjusted and concentrated by adding calcium-containing solid alkaline material, impurities are removed by adding chitosan, and finally the snow-melting agent is precipitated in the alcohol precipitation solution of ethanol and ethyl acetate. 2+ 2+ The method can make the utilization rate of the salt mud reach 86.37-88.61%, the effective component extraction rate reach 96.5-99.0%, the Ca 2+ 2+ precipitation rate reach more than 95% and more than 96.3% respectively, the snow-melting agent yield reach 95.5-99.99%, the whiteness of the snow-melting agent reach more than 98.0, no waste liquid is generated in the whole process, the recycling of the salt mud solid waste is realized, and the method has remarkable environmental and economic benefits.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solid waste resource comprehensive utilization and inorganic material synthesis, and particularly relates to a method for preparing a snow-melting agent by comprehensively utilizing chlor-alkali salt mud solid waste. BACKGROUND

[0002] Salt mud is a product of primary brine refining in the chlor-alkali industry, and 50-60 kg of salt mud solid waste is produced per ton of caustic soda produced. The domestic chlor-alkali production capacity is about 50 million tons per year, and about 2.5-3 million tons of salt mud is produced per year. As general industrial solid waste, if not properly treated, a large amount of solid waste becomes a problem for enterprises, and will have adverse effects on the ecological environment and human life.

[0003] The production capacity of the chlor-alkali device of Shandong Haihua is 300,000 tons per year, and the salt mud produced has a water content of 50%. The main components of the salt mud after drying (i.e. dry basis salt mud) are CaCO3 (about 58.5%), NaCl (about 19.5%), Mg(OH)2 (about 10%), Fe2O3 (about 0.08%), Al2O3 (about 1%), and the remaining components are insoluble substances (about 10.5%, mainly CaSO4 and SiO2, about 8.0% CaSO4). Due to the high chlorine content in the salt mud, direct discharge not only easily causes soil pollution, but also wastes effective components such as calcium and magnesium in the salt mud.

[0004] Although many enterprises have conducted some basic research on salt mud, the comprehensive utilization of salt mud is still insufficient, especially in terms of economic cost. The current salt mud treatment methods of most domestic chlor-alkali enterprises are basically limited to direct stacking or landfill after pressure filtration to recover brine. How to treat salt mud solid waste at low cost has become a problem for the chlor-alkali industry. Therefore, developing advanced salt mud solid waste resource comprehensive utilization technology has become the trend of the industry. Producing high-value-added products from salt mud not only realizes the reduction of solid waste emissions, but also creates high economic benefits for enterprises, and turns chlor-alkali salt mud into treasure. In addition, due to the frequent price inversion of by-product hydrochloric acid in the chlor-alkali industry, combining by-product hydrochloric acid with salt mud to prepare a snow-melting agent will also become one of the breakthrough directions for chlor-alkali enterprises.

[0005] At present, the method for preparing snow-melting agent from chlor-alkali salt mud solid waste is to prepare a slurry by mixing salt mud with water, then to perform acidification reaction by using hydrochloric acid as acidification reagent, to perform evaporation and concentration, to obtain high-concentration calcium-magnesium solution, to add corrosion inhibitor and then to perform spray drying and granulation to obtain snow-melting agent. In the acidification reaction process, in order to reduce the possibility of tank boiling, researchers will use the method of adding hydrochloric acid acidification reagent dropwise or increasing the volume of the reaction kettle to reduce the risk of solution overflow caused by the violent reaction of hydrochloric acid and salt mud to produce a large amount of carbon dioxide gas, but there will be problems of prolonging the total time of acidification reaction and reducing the utilization rate of the volume of the reaction kettle. In addition, researchers will also control the speed of carbon dioxide gas production by reducing the instantaneous concentration of hydrochloric acid acidification reagent to reduce the risk of tank boiling, that is, by increasing the liquid-solid ratio of the slurry prepared by mixing water and salt mud, but the addition of a large amount of water will lead to the decrease of the concentration of calcium and magnesium in the reaction system, thereby increasing the process cost of evaporation and concentration, and thus the economic benefit is poor. Therefore, the fast preparation method of high salt mud utilization rate, high-concentration calcium-magnesium solution and low-cost snow-melting agent is the focus of attention of enterprises and researchers.

[0006] At present, the raw material of snow-melting agent is mostly solid waste of oxide or carbonate compound, which is reacted with acidification reagent such as hydrochloric acid to prepare snow-melting agent solution, and then the solid snow-melting agent is obtained by evaporation and concentration and crystallization. Since the solid waste contains iron and other non-ferrous metals, the whiteness of the obtained solid snow-melting agent is low, which affects the sales of the product. In addition, the method of evaporation and concentration for preparing solid snow-melting agent has the characteristics of high energy consumption and high corrosion resistance of equipment. Therefore, there is an urgent need for a mild and low-cost method for preparing solid snow-melting agent.

[0007] The Chinese invention patent document with publication number CN106398649A discloses a method for preparing calcium-magnesium hydrochloride snow-melting agent from two-alkali salt mud. The method mixes two-alkali salt mud with water, adds waste hydrochloric acid to react to prepare calcium-magnesium chloride mother liquor, and the mother liquor is concentrated under reduced pressure, spray dried and granulated to obtain calcium-magnesium hydrochloride snow-melting agent. The patent uses the method of adding waste hydrochloric acid dropwise, which leads to long acidification reaction time and low reaction efficiency. At the same time, since no alkaline substance is added during the reaction process, the excess hydrochloric acid cannot be neutralized, and hydrogen chloride gas will be volatilized during the evaporation and concentration process, which not only causes environmental hazards, but also causes harm to equipment and human body. In addition, the calcium-magnesium chloride mother liquor contains impurity iron ions, and the scheme does not have a means for removing impurity iron ions, which easily leads to the color of the obtained snow-melting agent being red or yellow, which does not meet the color requirements of the national standard snow-melting agent (GB / T 23851-2017).

[0008] The Chinese invention patent document with the publication number CN113292093A discloses a method for crystallizing calcium chloride from an aqueous solution using solvent displacement crystallization. The method involves adding a calcium chloride solution to an organic solvent and controlling the crystallization temperature and the amount of organic solvent added to achieve the precipitation of calcium chloride. The patent mostly uses isopropylamine, ethylamine, and water azeotropic organic solvents without further treatment means, making it difficult to recover high-purity organic solvents. The recovered organic solvents contain water, which can lead to a decrease in calcium chloride yield after repeated use. Additionally, due to the addition of organic solvents, the total volume of the filtrate is the sum of the volume of the calcium chloride solution and the volume of the organic solvent. However, the patent assumes that the solution volume remains unchanged after adding the organic solvent (see paragraph 0040 of the specification), resulting in an error in the calculation of the precipitation rate of calcium chloride. The actual precipitation rate of calcium chloride is 18.6-33.9%, not 67.8-80%. Furthermore, the different organic solvents can also affect the precipitation efficiency. SUMMARY

[0009] The technical problem to be solved by the present invention is to provide a method for preparing a snow-melting agent from chlor-alkali salt mud solid waste, which can effectively overcome the problems of long acid addition time or low utilization rate of acidification reactor volume during acidification, long time and low yield during alcohol precipitation of the snow-melting agent, and low whiteness of the snow-melting agent. At the same time, it can solve the problem of high cost of salt mud comprehensive utilization and direct concentration crystallization, realize the value-added utilization of salt mud, waste-to-resource, solid waste reduction, and no waste liquid discharge, effectively promote the healthy development of the chlor-alkali industry, and has a broad industrial application prospect.

[0010] To solve the above problems, the technical solution of the present invention is a method for preparing a snow-melting agent from chlor-alkali salt mud solid waste, comprising the following steps:

[0011] (1) The salt mud is mixed with water to prepare a slurry, and the ratio of the mass of the salt mud to the water in the slurry is controlled to be 1g:2-4mL on a dry basis, then an acidification aid and a dispersing agent are added to the slurry to obtain a first mixed solution;

[0012] (2) Under stirring, 37% concentrated hydrochloric acid is added to the first mixed solution at one time, and the reaction is carried out at 25-55℃ for 0.5-2h, then the residue and a second mixed solution are obtained after separation;

[0013] (3) A calcium-containing alkaline substance is added to the second mixed solution to adjust the pH to 7-8.9, then chitosan is added, and the mixture is stirred and reacted for 0.5-1h, then the chitosan after adsorption and a third mixed solution are obtained after separation, and the chitosan after adsorption is regenerated and recycled for reuse;

[0014] (4) preparing an alcohol precipitation solution by mixing ethanol and ethyl acetate, and adding the third mixed solution into the alcohol precipitation solution to perform an alcohol precipitation reaction, so as to obtain a fourth mixed solution;

[0015] (5) separating the fourth mixed solution to obtain a crude deicing agent and a fifth mixed solution; drying the crude deicing agent to obtain the deicing agent; performing vacuum distillation on the fifth mixed solution, so as to obtain gaseous mixed gas of ethanol, ethyl acetate and water at the top, and condensing the gaseous mixed gas of ethanol, ethyl acetate and water to obtain a sixth mixed solution; and obtaining reaction residue at the bottom, and recycling the reaction residue;

[0016] (6) adding 3A molecular sieve into the sixth mixed solution to perform adsorption, and then separating to obtain the alcohol precipitation solution and the adsorbed 3A molecular sieve; returning the alcohol precipitation solution to step (4) for recycling; and recycling and repeatedly using the adsorbed 3A molecular sieve.

[0017] Further, in the step (1), the dispersing agent is sodium dodecyl sulfate or sodium polyacrylate; and the acidification aid is allyl polyoxyalkyl epoxy ether, allyl alcohol polyoxyalkyl ether or nonylphenol polyoxyethylene ether.

[0018] Further, in the step (1), the ratio of the amount of the dispersing agent to the total amount of water in the first mixed solution is 0.02-0.04 g: 1 mL; and the ratio of the amount of the acidification aid to the total amount of water in the first mixed solution is 0.001-0.005 g: 1 mL.

[0019] Further, in the step (2), the stirring speed is 100-300 r / min; and the ratio of the amount of the concentrated hydrochloric acid with a mass fraction of 37% to the mass of the salt mud in the first mixed solution is 0.02-0.024 moL: 1 g.

[0020] Further, in the step (3), the calcium-containing alkaline substance is calcium oxide or calcium hydroxide.

[0021] Further, in the step (3), the ratio of the amount of the chitosan to the total amount of water in the first mixed solution is 0.04-0.08 g: 1 mL.

[0022] Further, in the step (3), the recycling and repeatedly using condition of the adsorbed chitosan is: soaking in a 0.01-0.03 moL / L nitric acid solution for 0.3-0.5 h, then separating, and vacuum drying at 100-150 °C for 2-5 h.

[0023] Further, in the step (4), the volume ratio of ethanol to ethyl acetate is 1:1-3; and the volume ratio of the amount of the alcohol precipitation solution to the third mixed solution is 2-8: 1.

[0024] Further, in the step (4), the alcohol precipitation reaction conditions are: alcohol precipitation temperature 5-30 DEG C, alcohol precipitation time 0.2-0.5 h, stirring speed 100-150 r / min.

[0025] Further, in the step (5), the drying conditions are: vacuum drying 40-80 DEG C, vacuum drying time 1-2 h; the reaction residue is recycled by returning to the step (1) to serve as water.

[0026] Further, in the step (6), the adsorption conditions are: 3A molecular sieve addition amount 2-5% of the mass of the sixth mixed solution, adsorption time 0.5-1 h, stirring speed 100-300 r / min.

[0027] Further, in the step (6), the 3A molecular sieve after adsorption is regenerated and recycled for reuse under the following conditions: vacuum drying temperature 100-150 DEG C, vacuum drying time 1-3 h.

[0028] The present inventors found in the step (3) that when the calcium-containing alkaline substance adjusts the solution pH to more than 9, the solution immediately has precipitates, and the precipitates are analyzed by X-ray diffraction (XRD) structure analysis, and it is found that the precipitates are Ca(OH)2 and Mg(OH)2. Therefore, to obtain a magnesium-containing snow-melting agent, the pH of the reaction system needs to be appropriately controlled.

[0029] The present application has the following beneficial effects:

[0030] (1) In the present application, the acidification reaction is optimized by adding a dispersant and an acidification aid, so that hydrochloric acid can be directly added continuously in the industrial amplification process. The addition of the dispersant not only has the effect of improving the dispersibility of the salt mud, but also has the effect of improving the hydrophilicity of the solution, thereby reducing the surface tension of the solid-liquid mixed solution. The carbon dioxide bubbles generated in the reaction process will not tightly adhere to the salt mud, and thus the bubbles and the salt mud in the mixed solution will not form a viscous solid agglomerate at a low liquid-solid ratio, which will not prevent the acidification reaction from occurring, thereby facilitating the continuous acidification reaction and improving the utilization rate of the salt mud. The addition of the acidification aid will inhibit the large carbon dioxide bubbles in the reaction, and the large bubbles will be dispersed into small bubbles. The small bubbles are more likely to be broken in the stirring reaction, and have a synergistic effect with the dispersant to promote the mild acidification reaction, and thus the dropping speed of the hydrochloric acid does not need to be controlled, so that the hydrochloric acid can be directly added at one time, thereby laying a foundation for the industrial continuous operation.

[0031] (2) The calcium-containing alkaline substance used in the application is solid, which can not only neutralize the excess hydrochloric acid to adjust the pH to neutral or weak alkaline, avoiding the escape of hydrogen chloride gas in the subsequent process, but also introduce calcium source, thereby increasing the concentration of calcium ions in the solution, and the concentration of calcium ions in the third mixed solution reaches 2.05-2.95 moL / L. In addition, the chitosan in the application can selectively adsorb Fe 3+ ions, and basically does not adsorb Ca 2+ and Mg 2+ ions. At the same time, the chitosan can be regenerated by nitric acid solution and drying treatment repeatedly, and can be recycled.

[0032] (3) The alcohol precipitation method of the application does not involve chemical reaction, and only by optimizing the volume ratio of alcohol precipitation solution of ethanol and ethyl acetate, the addition amount of alcohol precipitation solution of ethanol and ethyl acetate and other alcohol precipitation conditions, the precipitation rates of Ca 2+ and Mg 2+ reach more than 95% and more than 96.3% respectively, the yield of snow melting agent reaches 95.5-99.99%, and the whiteness reaches more than 98.0, which improves the alcohol precipitation efficiency and the whiteness of the snow melting agent. The method is 60 times of the alcohol precipitation rate of single organic solvent ethanol, 1.19 times of the alcohol precipitation yield of single organic solvent ethanol, 40 times of the direct evaporation concentration crystallization rate, and 1.03 times of the whiteness of the direct concentration crystallization product. At the same time, the method of using ethanol and ethyl acetate to precipitate snow melting agent reduces the drying conditions of snow melting agent, and does not need high temperature drying, thereby reducing energy consumption. In addition, the boiling points of selected ethanol and ethyl acetate are low and the cost is low, which is easier to distill and recycle, thereby reducing the process operation cost.

[0033] (4) By optimizing the solid-liquid ratio, reaction temperature, reaction time and hydrochloric acid addition amount of salt mud and water, the application can not only ensure a high concentration of calcium and magnesium-containing solution, but also realize high utilization of salt mud and extraction of effective components in salt mud, so that the utilization rate of salt mud reaches 86.37-88.61%, the extraction rate of effective components in salt mud reaches 96.5-99.0%, and only part of the residue is discharged in the whole process, so that the salt mud is reduced in discharge, which is helpful for the healthy development of chlor-alkali industry. At the same time, most of the hydrochloric acid in inorganic acid comes from chlor-alkali industry, and the price of hydrochloric acid is mostly inverted, so that the method can realize the self-circulation use of hydrochloric acid in chlor-alkali industry, which is helpful for extending the downstream application of hydrochloric acid in chlor-alkali industry and improving the added value of products.

[0034] (5) The 3A molecular sieve in the application can adsorb and treat water in the alcohol precipitation solution, and by optimizing the addition amount of 3A molecular sieve to adsorb water, the water content is reduced to below 0.5%, which is helpful for the recycling of alcohol precipitation solution and reduces the process operation cost. At the same time, the 3A molecular sieve can be regenerated by drying treatment repeatedly, so that the circular economy is realized.

[0035] (6) The present application realizes efficient and full utilization of resources, wherein the chitosan and 3A molecular sieve and the recovery and recycling of the alcohol precipitation solution are reduced, thereby reducing the operation cost and improving the competitiveness. Meanwhile, the reaction residue is used in step (1) to act as water for dispersing the salt mud, thereby realizing zero discharge of waste liquid and greatly reducing the production cost, and having significant environmental and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 A test chart for salt mud utilization rate and effective component extraction rate of salt mud of examples 1-4, comparative example 2 and comparative example 4;

[0037] Figure 2 An X-ray diffraction (XRD) structure chart of the snow-melting agent obtained in step (5) of examples 1-4. DETAILED DESCRIPTION

[0038] The present application will be described in detail below in combination with examples and drawings, but the protection scope of the present application is not limited to this. Example 1

[0039] (1) 1000g of salt mud (containing 50% of water) is uniformly mixed with 1000mL of water to prepare a slurry, and 45g of sodium dodecyl sulfate and 4.5g of allyl polyoxyalkyl epoxy ether are added to the slurry to obtain a first mixed solution;

[0040] (2) 11mL of 37% concentrated hydrochloric acid is added to the first mixed solution at a stirring speed of 200r / min, and the reaction is carried out at 40℃ for 1h, and then the residue and a second mixed solution are obtained by filtration separation;

[0041] (3) calcium oxide is added to the second mixed solution to adjust the pH to 7, and then 90g of chitosan is added and stirred for 0.8h, and then the chitosan after adsorption and a third mixed solution are obtained by filtration, and the chitosan after adsorption is soaked in 0.02moL / L nitric acid solution for 0.4h, and then centrifugal separation, vacuum drying at 120℃ for 3.5h, and then regenerated and recycled;

[0042] (4) ethanol and ethyl acetate are prepared into an alcohol precipitation solution according to a volume ratio of 1:2, 1000mL of the third mixed solution is taken, and the alcohol precipitation solution is added to the third mixed solution for alcohol precipitation reaction, the alcohol precipitation solution is controlled to be 5 times of the volume of the third mixed solution, the alcohol precipitation temperature is controlled to be 15℃, the alcohol precipitation time is controlled to be 0.3h, and the stirring speed is controlled to be 120r / min, and then a fourth mixed solution is obtained;

[0043] (5) The fourth mixed solution is filtered and separated to obtain a crude snow-melting agent and a fifth mixed solution. The crude snow-melting agent is vacuum dried at 60°C for 1.5 hours to obtain the snow-melting agent. The fifth mixed solution is fed into a distillation column for vacuum distillation. Gaseous ethanol, ethyl acetate and water are obtained at the top of the distillation column. The gaseous ethanol, ethyl acetate and water are condensed to obtain a sixth mixed solution. Reaction residue is obtained at the bottom of the distillation column and is returned to step (1) to serve as water for recycling.

[0044] (6) The sixth mixed solution is mixed with 3A molecular sieves and subjected to adsorption treatment. The amount of 3A molecular sieves added is 3.5% of the mass of the sixth mixed solution, the adsorption time is 0.8 hours, and the stirring speed is 200 r / min. After filtration and separation, an alcohol precipitation solution and adsorbed 3A molecular sieves are obtained. The alcohol precipitation solution is returned to step (4) for recycling. The adsorbed 3A molecular sieves are vacuum dried at 120°C for 2 hours and then regenerated for recycling.

[0045] The residue in step (2) is dried and weighed. The test results are shown in Table 1. The utilization rate of salt mud and the extraction rate of effective components in salt mud are tested. The test results are shown in Table 1. Figure 1 ;

[0046] In step (3), the Ca 2+ , Mg 2+ and Fe 3+ concentrations of the third mixed solution are tested by inductively coupled plasma spectrometer (ICP). The test results are shown in Table 1.

[0047] In step (5), the Ca 2+ , Mg 2+ and Fe 3+ concentrations of the fifth mixed solution are tested by ICP. The test results are shown in Table 1.

[0048] In step (5), the snow-melting agent is subjected to X-ray diffraction (XRD) structure and yield and whiteness tests. The test results are shown in Table 1, Table 1 and Table 1, respectively. Figure 2

[0049] In step (6), the alcohol precipitation solution is subjected to moisture testing. The test results are shown in Table 1.

[0050] The utilization rate of salt mud is tested as follows: The dried residue is weighed. The calculation formula is: Y 总 = (m0-m1) / m0 x 100%, Y 总 is the utilization rate of salt mud, %; m0 is the mass of salt mud on a dry basis, g; and m1 is the mass of the dried residue, g. m0 is 500 g.

[0051] ​The operation of the effective component extraction rate test in the salt slurry is as follows: the dried residue is weighed, and the formula is: Y 有效 = (m0-m1) / (m0x (1-X 酸性不溶物 ))x100%, Y 有效 is the effective component extraction rate in the salt slurry, %; m0 is the salt slurry mass on a dry basis, g; X 酸性不溶物 is the content of acid-insoluble substances in the salt slurry on a dry basis, %; m1 is the mass of the dried residue, g. Among them, X 酸性不溶物 is the total of SiO2 and CaSO4 in the salt slurry on a dry basis, which is 10.5%, and m0 is 500 g.

[0052] The test method of the Ca 2+ and Mg 2+ and Fe 3+ concentration of ICP: the calcium chloride, magnesium chloride and ferric chloride are respectively prepared into different concentrations of calcium chloride solution or magnesium chloride solution or ferric chloride standard curve, the average error is ≥0.999, and the Ca 2+ concentration, Mg 2+ concentration and Fe 3+ concentration of the test sample are obtained according to the standard curves of the calcium chloride solution and the magnesium chloride solution and the ferric chloride solution.

[0053] The operation of the Ca 2+ and Mg 2+ precipitation rate test in the third mixed solution is as follows: the Ca 2 + and Mg 2+ concentration and volume of the fifth mixed solution in step (5) are obtained, and then the amount of substance (moL) of the remaining Ca and Mg in the fifth mixed solution is obtained; the Ca 2+ and Mg 2+ concentration and volume of the third mixed solution in step (3) are obtained, and then the amount of substance (moL) of Ca and Mg in the third mixed solution, i.e. the amount of substance (moL) of Ca and Mg before precipitation, is obtained. The formula is: X Ca或Mg = (C Ca或Mg，第三混合溶液 x V 第三混合溶液 -C Ca或Mg，第五混合溶液 x V 第五混合溶液 ) / (C Ca或Mg，第三混合溶液 x V 第三混合溶液 ) x 100%, X Ca或Mg is the Ca 2+ and Mg 2+ precipitation rate, %; C Ca或Mg，第三混合溶液 is the Ca 2+ and Mg 2+ concentration in the third mixed solution, moL / L; V 第三混合溶液 is the volume of the third mixed solution, L; C Ca或Mg，第五混合溶液For the fifth mixed solution, Ca 2+ Mg 2+ Concentration, mol / L; V 第五混合溶液 Let L be the volume of the fifth mixed solution.

[0054] The yield test of the de-icing agent is performed as follows: the de-icing agent in step (6) is dried and weighed to obtain m2; the Ca in the third mixture in step (3) 2+ Mg 2+ The amount of substance (mol) of the corresponding snow-melting agent is calculated from the concentration and volume, and then the theoretical mass (m) of the snow-melting agent is obtained. max The formula is: Y 融雪剂 =m2 / m max ×100%, Y 融雪剂 m is the yield of the de-icing agent, %; m2 is the total mass of the de-icing agent, g; m max For the third mixture of Ca 2+ Mg 2+ The total mass of the theoretically converted snow-melting agent is expressed in grams.

[0055] Method for testing moisture in alcohol precipitation solution: First, clean the AKF-1 fully automatic Karl Fischer moisture analyzer with anhydrous methanol, then perform blank and drift correction, and finally calibrate with a mixed solution of deionized water and Karl Fischer reagent. Then add the sample to be tested, and the system automatically calculates the percentage of moisture content.

[0056] Whiteness test method for de-icing agent: First, preheat the WSB-3C fluorescence whiteness meter for more than 15 seconds, then zero it, then place the calibration reference white plate on the sample holder for calibration, and perform multiple calibrations with an error range of ±0.1. Finally, place the sample to be tested on the sample holder and take the reading.

[0057] Chitosan and Ca 2+ Mg 2+ Fe 3+ The adsorption rate test procedure is as follows: The Ca before and after adding chitosan in step (3) is compared. 2+ Mg 2+ Fe 3+ The concentration is determined by ICP testing, and the formula is: Z 吸附率 =(C 吸附前 -C 吸附后 ) / C 吸附前 ×100%, Z adsorption rate is Ca 2+ or Mg 2+ or Fe 3+ Adsorption rate, %; C 吸附前 For the second mixed solution Ca 2+ or Mg 2+ or Fe 3+ Concentration, mol / L; C 吸附后For the third mixed solution Ca 2+ or Mg 2+ or Fe 3+ Concentration, mol / L.

[0058] As shown in Table 1, the mass of the residue is 61.45g, and combined with... Figure 1 Calculations show that the utilization rate of salt mud is 87.71%, and the extraction rate of effective components from salt mud reaches 98.0%.

[0059] Table 1 shows that the Ca in the third mixed solution 2+ Mg 2+ Fe 3+ The concentrations were 2.75 mol / L, 0.30 mol / L, and 0 mol / L, respectively. The Ca concentration in the fifth mixed solution... 2+ Mg 2+ Fe 3+ With concentrations of 2.29 mmol / L, 0.25 mmol / L, and 0 mmol / L respectively, calculations show that the Ca in the third mixed solution of the alcohol precipitation solution is... 2+ Mg 2+ The precipitation rates were 99.5% and 99.5% respectively; the mass of the de-icing agent was 463.19g, and the yield was calculated to be 99.5%; the whiteness of the de-icing agent was 98.5; and the water content in the alcohol precipitation solution was 0.3%.

[0060] Depend on Figure 2 It is known that the de-icing agent is a mixture of calcium chloride dihydrate and magnesium chloride hexahydrate, corresponding to the standard cards calcium chloride dihydrate (PDF#98-000-0039) and magnesium chloride hexahydrate (PDF#97-002-6744), respectively. Therefore, this de-icing agent belongs to the chloride salt class of de-icing agents. Example 2

[0061] (1) Mix 1000g of salt mud (with a water content of 50%) with 500mL of water to prepare a slurry. Add 20g of sodium polyacrylate and 1.0g of allyl alcohol polyoxyalkyl ether to the slurry and mix well to obtain the first mixed solution.

[0062] (2) At a stirring speed of 100 r / min, 10 mol of concentrated hydrochloric acid with a mass fraction of 37% was added to the first mixed solution at one time, and the reaction was carried out at 25°C for 2 h. After centrifugation, the residue and the second mixed solution were obtained.

[0063] (3) Add calcium oxide to the second mixed solution to adjust the pH to 8, then add 40g of chitosan, stir and react for 1h, and centrifuge to obtain the adsorbed chitosan and the third mixed solution; soak the adsorbed chitosan in 0.01mol / L nitric acid solution for 0.5h, centrifuge, vacuum dry at 100℃ for 5h, and regenerate for reuse;

[0064] (4) Prepare an alcohol precipitation solution by mixing ethanol and ethyl acetate in a volume ratio of 1:1. Take 1000 mL of the third mixed solution and add the alcohol precipitation solution to the third mixed solution to carry out the alcohol precipitation reaction. Control the amount of alcohol precipitation solution added to be twice the volume of the third mixed solution. Control the alcohol precipitation temperature to be 5℃, the alcohol precipitation time to be 0.5 h, and the stirring speed to be 150 r / min to obtain the fourth mixed solution.

[0065] (5) The fourth mixed solution is filtered and separated to obtain crude de-icing agent and fifth mixed solution. The crude de-icing agent is dried under vacuum at 40°C for 2 hours to obtain de-icing agent. The fifth mixed solution is distilled under reduced pressure in a distillation tower. A mixture of gaseous ethanol, ethyl acetate and water is obtained at the top of the distillation tower. The mixture of gaseous ethanol, ethyl acetate and water is condensed to obtain the sixth mixed solution. The reaction residue is obtained at the bottom of the distillation tower and is returned to step (1) as water for recycling.

[0066] (6) The sixth mixed solution is mixed with 3A molecular sieve and then subjected to adsorption treatment. The amount of 3A molecular sieve added is controlled to be 2% of the mass of the sixth mixed solution, the adsorption time is 1h, and the stirring speed is 300r / min. After centrifugation, the alcohol precipitation solution and the adsorbed 3A molecular sieve are obtained. The alcohol precipitation solution is returned to step (4) for recycling. The adsorbed 3A molecular sieve is vacuum dried at 100℃ for 3h and then regenerated for recycling.

[0067] The residue from step (2) was dried and weighed. The test results are shown in Table 1. The utilization rate of the salt mud and the extraction rate of the effective components in the salt mud were also tested. The test methods were the same as in Example 1. The test results are shown in Table 1. Figure 1 ;

[0068] In step (3), the third mixed solution was subjected to inductively coupled plasma atomic emission spectrometry (ICP) for Ca... 2+ Mg 2+ Fe 3+ Concentration testing was conducted using the same method as in Example 1, and the results are shown in Table 1.

[0069] In step (5), the fifth mixed solution is subjected to ICP Ca2+. 2+ Mg 2+ Fe 3+ Concentration testing was conducted using the same method as in Example 1, and the results are shown in Table 1.

[0070] In step (5), the de-icing agent was subjected to X-ray diffraction (XRD) structure, yield, and whiteness tests. The test methods were the same as in Example 1, and the test results are shown in [reference needed]. Figure 2 Table 1.

[0071] The moisture content of the alcohol precipitation solution in step (6) was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0072] As shown in Table 1, the mass of the residue is 68.16 g, and combined with... Figure 1 Calculations show that the utilization rate of salt mud is 86.37%, and the extraction rate of effective components from salt mud reaches 96.5%.

[0073] Table 1 shows that the Ca in the third mixed solution 2+ Mg 2+ Fe 3+ The concentrations were 2.91 mol / L, 0.37 mol / L, and 2.20 mol / L, respectively. The Ca concentration in the fifth mixed solution... 2+ Mg 2+ Fe 3+ The concentrations were 48.50 mmol / L, 4.56 mmol / L, and 0.37 mmol / L, respectively. Calculations showed that the Ca concentration in the third mixed solution of the alcohol precipitation solution was... 2+ Mg 2+ The precipitation rates were 95.0% and 96.3%, respectively; the mass of the de-icing agent was 480.63g, and the yield was calculated to be 95.5%; the whiteness of the de-icing agent was 98.0; and the water content in the alcohol precipitation solution was 0.5%.

[0074] Depend on Figure 2 It is known that the de-icing agent is a mixture of calcium chloride dihydrate and magnesium chloride hexahydrate, corresponding to the standard cards calcium chloride dihydrate (PDF#98-000-0039) and magnesium chloride hexahydrate (PDF#97-002-6744), respectively. Therefore, this de-icing agent belongs to the chloride salt class of de-icing agents. Example 3

[0075] (1) Mix 1000g of salt mud (with a water content of 50%) with 1500mL of water to prepare a slurry. Add 80g of sodium polyacrylate and 10g of nonylphenol polyoxyethylene ether to the slurry and mix well to obtain the first mixed solution.

[0076] (2) Add 12 mol of concentrated hydrochloric acid with a mass fraction of 37% to the first mixed solution at a stirring speed of 300 r / min, react at 55°C for 0.5 h, and then separate by centrifugation to obtain the residue and the second mixed solution;

[0077] (3) Add calcium oxide to the second mixed solution to adjust the pH to 8.9, then add 160g of chitosan, stir and react for 0.5h, and separate by filtration to obtain the adsorbed chitosan and the third mixed solution; soak the adsorbed chitosan in 0.03mol / L nitric acid solution for 0.3h, separate by filtration, vacuum dry at 150℃ for 2h, and regenerate for reuse;

[0078] (4) Prepare an alcohol precipitation solution by mixing ethanol and ethyl acetate in a volume ratio of 1:3. Take 1000 mL of the third mixed solution and add the alcohol precipitation solution to the third mixed solution to carry out the alcohol precipitation reaction. Control the amount of alcohol precipitation solution added to be 8 times the volume of the third mixed solution. Control the alcohol precipitation temperature to be 30℃, the alcohol precipitation time to be 0.2 h, and the stirring speed to be 100 r / min to obtain the fourth mixed solution.

[0079] (5) The fourth mixed solution is filtered to obtain crude de-icing agent and fifth mixed solution. The crude de-icing agent is dried under vacuum at 80°C for 1 hour to obtain de-icing agent. The fifth mixed solution is distilled under reduced pressure in a distillation tower. A mixture of gaseous ethanol, ethyl acetate and water is obtained at the top of the distillation tower. The mixture of gaseous ethanol, ethyl acetate and water is condensed to obtain the sixth mixed solution. The reaction residue is obtained at the bottom of the distillation tower and is returned to step (1) as water for recycling.

[0080] (6) After mixing the sixth mixed solution with the 3A molecular sieve, the adsorption treatment is carried out. The amount of 3A molecular sieve added is controlled to be 5% of the mass of the sixth mixed solution, the adsorption time is 0.5h, and the stirring speed is 100r / min. After filtration and separation, the alcohol precipitation solution and the adsorbed 3A molecular sieve are obtained. The alcohol precipitation solution is returned to step (4) for recycling. The adsorbed 3A molecular sieve is vacuum dried at 150℃ for 1h and then regenerated for recycling.

[0081] The residue from step (2) was dried and weighed. The test results are shown in Table 1. The utilization rate of the salt mud and the extraction rate of the effective components in the salt mud were also tested. The test methods were the same as in Example 1. The test results are shown in Table 1. Figure 1 ;

[0082] In step (3), the third mixed solution was subjected to inductively coupled plasma atomic emission spectrometry (ICP) for Ca... 2+ Mg 2+ Fe 3+ Concentration testing was conducted using the same method as in Example 1, and the results are shown in Table 1.

[0083] In step (5), the fifth mixed solution is subjected to ICP Ca2+. 2+ Mg 2+ Fe 3+ Concentration testing was conducted using the same method as in Example 1, and the results are shown in Table 1.

[0084] In step (5), the de-icing agent was subjected to XRD structure, yield, and whiteness tests. The test methods were the same as in Example 1, and the test results are shown in [reference needed]. Figure 2 Table 1.

[0085] The moisture content of the alcohol precipitation solution in step (6) was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0086] As shown in Table 1, the mass of the residue is 56.98g, and combined with... Figure 1 Calculations show that the utilization rate of salt mud is 88.61%, and the extraction rate of effective components from salt mud reaches 99.0%.

[0087] Table 1 shows that the Ca in the third mixed solution 2+ Mg 2+ Fe 3+ The concentrations were 2.05 mol / L, 0.25 mol / L, and 0 mol / L, respectively. The Ca concentration in the fifth mixed solution... 2+ Mg 2+ Fe 3+ The concentrations of all solutions were 0 mol / L. Calculations show that the Ca concentration in the third mixed solution of the alcohol precipitation solution is [missing information]. 2+ Mg 2+ The precipitation rates were 100% and 100% respectively, but the mass of the de-icing agent was 352.34g, and the calculated yield was 99.99%. The reason for the difference between the yield and the precipitation rate may be the presence of Ca in the fifth mixed solution. 2+ Mg 2+ Fe 3+ A concentration of 0 mol / L is below the ICP detection limit and was not detected. The whiteness of the de-icing agent is 98.8; the water content in the alcohol precipitation solution is 0.05%.

[0088] Depend on Figure 2 It is known that the de-icing agent is a mixture of calcium chloride dihydrate and magnesium chloride hexahydrate, corresponding to the standard cards calcium chloride dihydrate (PDF#98-000-0039) and magnesium chloride hexahydrate (PDF#97-002-6744), respectively. Therefore, this de-icing agent belongs to the chloride salt class of de-icing agents. Example 4

[0089] (1) Mix 1000g of salt mud (with a water content of 50%) with 1250mL of water to prepare a slurry. Add 56g of sodium dodecyl sulfate and 7.0g of allyl polyoxyalkyl epoxy ether to the slurry and mix well to obtain the first mixed solution.

[0090] (2) At a stirring speed of 250 r / min, 11.5 mol of concentrated hydrochloric acid with a mass fraction of 37% was added to the first mixed solution at one time, and the reaction was carried out at 35°C for 2 h. After centrifugation, the residue and the second mixed solution were obtained.

[0091] (3) Add calcium hydroxide to the second mixed solution to adjust the pH to 7, then add 114g of chitosan, stir and react for 0.8h, and centrifuge to obtain the adsorbed chitosan and the third mixed solution; soak the adsorbed chitosan in 0.02mol / L nitric acid solution for 0.4h, centrifuge, vacuum dry at 140℃ for 3.5h, and regenerate for reuse;

[0092] (4) Prepare an alcohol precipitation solution by mixing ethanol and ethyl acetate in a volume ratio of 1:2. Take 1000 mL of the third mixed solution and add the alcohol precipitation solution to the third mixed solution to carry out the alcohol precipitation reaction. Control the amount of alcohol precipitation solution added to be 4.5 times the volume of the third mixed solution. Control the alcohol precipitation temperature to be 25℃, the alcohol precipitation time to be 0.5 h, and the stirring speed to be 150 r / min to obtain the fourth mixed solution.

[0093] (5) The fourth mixed solution is filtered and separated to obtain crude de-icing agent and fifth mixed solution. The crude de-icing agent is dried under vacuum at 50°C for 1.5 h to obtain de-icing agent. The fifth mixed solution is distilled under reduced pressure in a distillation tower. A mixture of gaseous ethanol, ethyl acetate and water is obtained at the top. The mixture of gaseous ethanol, ethyl acetate and water is condensed to obtain the sixth mixed solution. The reaction residue is obtained at the bottom of the distillation tower and is returned to step (1) as water for recycling.

[0094] (6) The sixth mixed solution is mixed with 3A molecular sieve and then subjected to adsorption treatment. The amount of 3A molecular sieve added is controlled to be 4.0% of the mass of the sixth mixed solution, the adsorption time is 0.8h, and the stirring speed is 200r / min. After filtration and separation, the alcohol precipitation solution and the adsorbed 3A molecular sieve are obtained. The alcohol precipitation solution is returned to step (4) for recycling. The adsorbed 3A molecular sieve is vacuum dried at 110℃ for 3h and then regenerated for recycling.

[0095] The residue from step (2) was dried and weighed. The test results are shown in Table 1. The utilization rate of the salt mud and the extraction rate of the effective components in the salt mud were also tested. The test methods were the same as in Example 1. The test results are shown in Table 1. Figure 1 ;

[0096] In step (3), the third mixed solution was subjected to inductively coupled plasma atomic emission spectrometry (ICP) for Ca... 2+ Mg 2+ Fe 3+ Concentration testing was conducted using the same method as in Example 1, and the results are shown in Table 1.

[0097] In step (5), the fifth mixed solution is subjected to ICP Ca2+. 2+ Mg 2+ Fe 3+ Concentration testing was conducted using the same method as in Example 1, and the results are shown in Table 1.

[0098] In step (5), the de-icing agent was subjected to XRD structure, yield, and whiteness tests. The test methods were the same as in Example 1, and the test results are shown in [reference needed]. Figure 2 Table 1.

[0099] The moisture content of the alcohol precipitation solution in step (6) was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0100] As shown in Table 1, the mass of the residue is 62.35g. Combined with the graph and calculation, the utilization rate of salt mud is 87.53%, and the extraction rate of effective components of salt mud reaches 97.8%.

[0101] Table 1 shows that the Ca in the third mixed solution 2+ Mg 2+ Fe 3+ The concentrations were 2.36 mol / L, 0.28 mol / L, and 0 mol / L, respectively. The Ca concentration in the fifth mixed solution... 2+ Mg 2+ Fe 3+ With concentrations of 2.57 mmol / L, 0.24 mmol / L, and 0 mmol / L, respectively, calculations show that the Ca in the third mixed solution of the alcohol precipitation solution is... 2+ Mg 2+ The precipitation rates were 99.40% and 99.53%, respectively; the mass of the de-icing agent was 401.86g, and the yield was calculated to be 99.45%; the whiteness of the de-icing agent was 98.3; and the water content in the alcohol precipitation solution was 0.15%.

[0102] Depend on Figure 2 It is known that the de-icing agent is a mixture of calcium chloride dihydrate and magnesium chloride hexahydrate, corresponding to the standard cards calcium chloride dihydrate (PDF#98-000-0039) and magnesium chloride hexahydrate (PDF#97-002-6744), respectively. Therefore, this de-icing agent belongs to the chloride salt class of de-icing agents. Comparative Example 1

[0103] The difference between Comparative Example 1 and Example 1 is that the amount of water used in step (1) is different. 1000 mL of water is replaced with 450 mL of water, while the other steps remain the same.

[0104] During the experiment, it was found that when the ratio of salt mud to water was less than 1g:2mL, after adding concentrated hydrochloric acid with a mass fraction of 37%, the entire reaction system quickly turned into a viscous solid agglomerate, making the acidification reaction impossible. The reason for the formation of this viscous solid agglomerate state is that the hydrochloric acid reacts violently with the calcium carbonate in the salt mud, generating a large amount of heat and carbon dioxide bubbles. This heat carries away some water, and the calcium chloride produced in the reaction absorbs water, resulting in a high solid content in the entire reaction system. Because the water content is low, the viscosity of the bubbles further increases, causing them to combine with the salt mud to form viscous solid agglomerates, making the stirring acidification reaction impossible, and the utilization rate of the salt mud is zero. Therefore, the liquid-to-solid ratio of water to salt mud is a crucial factor determining whether the acidification reaction can proceed, and the ratio of salt mud to water should be appropriately controlled. Comparative Example 2

[0105] The difference between Comparative Example 2 and Example 1 is that sodium dodecyl sulfate dispersant was not added in step (1), while the other steps remained the same.

[0106] In step (2), the residue was dried and weighed. The test results are shown in Table 1. The utilization rate of the salt mud and the extraction rate of the effective components in the salt mud were also tested. The test methods were the same as in Example 1. The test results are shown in Table 1. Figure 1 .

[0107] As shown in Table 1, the mass of the residue is 105.59 g. Figure 1 It can be seen that the utilization rate of salt mud was 78.88%, and the extraction rate of effective components was 88.14%, resulting in a significant waste of effective components. Furthermore, during the experiment, we found that without the addition of sodium dodecyl sulfate dispersant, the carbon dioxide bubbles generated during the reaction were larger and less prone to breaking, which facilitated the adhesion of salt mud to the walls and hindered the acidification reaction. Compared to Comparative Example 2, Example 1 was easier to acidify because the dispersant not only improved the dispersibility of the salt mud but also increased the hydrophilicity of the solution, reducing surface tension. This prevented the carbon dioxide bubbles from becoming excessively large or adhering tightly to the salt mud. Comparative Example 3

[0108] The difference between Comparative Example 3 and Example 1 is that no allyl polyoxyalkyl epoxy ether acidification aid was added in step (1), while the other steps remained unchanged.

[0109] During the experiment, it was found that without the addition of acidifying aids, the acidification reaction was violent, producing large amounts of carbon dioxide gas bubbles that caused salt mud and solution to overflow, posing a dangerous hazard. Therefore, acidifying aids are a key factor in ensuring the safe and gentle conduct of the acidification reaction, and they have a synergistic effect with dispersants. Comparative Example 4

[0110] The difference between Comparative Example 4 and Example 1 is the reaction time in step (2), where 1 h is changed to 0.3 h, while the other steps remain the same.

[0111] In step (2), the residue was dried and weighed. The test results are shown in Table 1. The utilization rate of the salt mud and the extraction rate of the effective components in the salt mud were also tested. The test methods were the same as in Example 1. The test results are shown in Table 1. Figure 1 .

[0112] As shown in Table 1, the mass of the residue is 200.56g. Figure 1 It can be seen that the utilization rate of salt mud was 59.89%, and the extraction rate of effective components from salt mud was 66.91%, resulting in a significant waste of the effective components from the salt mud. Therefore, the reaction time affects the utilization rate of salt mud and the extraction rate of effective components, and the reaction time should be appropriately controlled. Comparative Example 5

[0113] The difference between Comparative Example 5 and Example 1 is that chitosan was not added in step (3), while the other steps remained the same.

[0114] In step (3), the third mixed solution is subjected to ICP Ca2+. 2+ Mg 2+ Fe 3+ Concentration testing was conducted using the same method as in Example 1, and the results are shown in Table 1.

[0115] In step (5), the yield and whiteness of the de-icing agent were tested. The test method was the same as in Example 1, and the test results are shown in Table 1.

[0116] Table 1 shows that the Ca in the third mixed solution 2+ Mg 2+ Fe 3+ The concentrations were 2.76 mol / L, 0.31 mol / L, and 8.8 mol / L, respectively; the yield of the de-icing agent was 99.6%, and the whiteness of the de-icing agent was 92.0. The reason for the decrease in the whiteness of the de-icing agent was Fe. 3+ The precipitation of chitosan leads to a decrease in the whiteness of the de-icing agent. Comparison of data from Comparative Example 5 and Example 1 shows that chitosan affects the whiteness of Ca... 2+ Mg 2+ Fe 3+ The adsorption rates were 0.36%, 3.22%, and 100%, respectively, for Ca... 2+ and Mg 2+ Adsorption is negligible. Comparative Example 6

[0117] The difference between Comparative Example 6 and Example 1 is that no ethyl acetate was added in step (4), while the other steps remained the same.

[0118] In step (5), the yield of the de-icing agent was tested, and the test method was the same as in Example 1.

[0119] Experiments revealed that no de-icing agent precipitated within 0.3 hours, resulting in a 0% yield. The inventors further tested the yield by extending the precipitation time. They found that extending the precipitation time to 10 hours increased the yield to 80.5%, while further extending it to 18 hours resulted in only 83.5%, indicating limited improvement. This demonstrates that the addition of ethyl acetate not only accelerates the precipitation of the de-icing agent but also increases its yield, exhibiting a synergistic effect with ethanol. Therefore, the precipitation time for the ethanol and ethyl acetate solution in Example 1 was 18 minutes, while the precipitation time for the ethanol solution in Comparative Example 6 was 1080 minutes, 60 times the precipitation rate of ethanol alone. The yield of Example 1 was 1.19 times that of Comparative Example 6. Comparative Example 7

[0120] The difference between Comparative Example 7 and Example 1 is that no ethanol was added in step (4), while the other steps remained the same.

[0121] During the experiment, it was found that without the addition of ethanol, ethyl acetate and the third mixed solution separated into two immiscible phases, and the yield of the de-icing agent was 0%. Comparative Example 8

[0122] The difference between Comparative Example 8 and Example 1 is that the volume ratio of ethanol and ethyl acetate in step (4) is different. When the volume ratio of ethanol and ethyl acetate is changed from 1:2 to 1:6, the other steps remain unchanged.

[0123] In step (5), the yield of the de-icing agent was tested using the same method as in Example 1. The test results are shown in Table 1.

[0124] As shown in Table 1, the yield of the de-icing agent was 70.5%, which was much lower than the yield of Example 1. Combined with Comparative Examples 6-7, it can be seen that although ethyl acetate can improve the precipitation rate and yield, the ratio of ethanol to ethyl acetate must be controlled and should not be too high, as too high a ratio will also affect the precipitation effect. Comparative Example 9

[0125] The difference between Comparative Example 9 and Example 1 is that the amount of ethanol and ethyl acetate added in step (4) is different. When the amount of ethanol and ethyl acetate added is changed from 5 times the volume of the third mixed solution to 1 time, the other steps remain unchanged.

[0126] In step (5), the yield of the de-icing agent was tested using the same method as in Example 1. The test results are shown in Table 1.

[0127] As shown in Table 1, the yield of the de-icing agent was 50.5%, which is far lower than the yield in Example 1. This indicates that the amount of ethanol and ethyl acetate added also affects the precipitation effect. Comparative Example 10

[0128] The difference between Comparative Example 10 and Example 1 is that steps (4)-(6) are omitted. The specific operation steps are as follows:

[0129] The third mixed solution was placed in a beaker and sealed with tin foil. The moisture was evaporated in a forced-air drying oven at 90-110℃. After evaporation for 12 hours, the de-icing agent was obtained.

[0130] The yield and whiteness of the de-icing agent were tested using the same method as in Example 1. The test results are shown in Table 1.

[0131] As shown in Table 1, the yield of the de-icing agent was 100%, and the whiteness was 96.0. Compared with the whiteness of Example 1, the whiteness of Example 1 was 1.03 times that of Comparative Example 10. This is because the whiteness decreased due to the presence of other impurity ions in the solution or due to air oxidation. The alcohol precipitation method in Example 1 took 18 minutes, while the evaporation and concentration method in Comparative Example 10 took 720 minutes. The speed of Example 1 was 40 times that of Comparative Example 10. The alcohol precipitation method can significantly save time and reduce energy consumption. Comparative Example 11

[0132] The difference between Comparative Example 11 and Example 1 is that the organic solvent in the alcohol precipitation solution in step (4) is different, and ethanol and ethyl acetate are replaced with ketone organic solvents such as acetone.

[0133] During the experiment, it was found that acetone and the third mixed solution were immiscible, with acetone dispersed above the mixed solution, indicating a two-phase state. This demonstrates that acetone, as a ketone organic solvent, cannot facilitate the precipitation of de-icing agents. Comparative Example 12

[0134] The difference between Comparative Example 12 and Example 1 is that the organic solvent in the alcohol precipitation solution in step (4) is different, and ethanol and ethyl acetate are replaced with amine organic solvents of N,N-dimethylformamide.

[0135] During the experiment, it was found that no de-icing agent precipitated within 0.3 hours. However, even when the alcohol precipitation time was extended to 24 hours, no de-icing agent precipitated. This indicates that amine organic solvents containing N,N-dimethylformamide cannot induce the precipitation of de-icing agents. Comparative Example 13

[0136] The difference between Comparative Example 13 and Example 1 is that chitosan in step (3) is replaced with activated carbon, while the other steps remain unchanged.

[0137] In step (3), the third mixed solution is subjected to ICP Ca2+. 2+ Mg 2+ Fe 3+ Concentration testing was conducted using the same method as in Example 1, and the results are shown in Table 1.

[0138] In step (5), the yield and whiteness of the de-icing agent were tested. The test method was the same as in Example 1, and the test results are shown in Table 1.

[0139] Table 1 shows that the Ca in the third mixed solution 2+ Mg 2+ Fe 3+ The concentrations were 2.48 mol / L, 0.25 mol / L, and 0; the yield of the de-icing agent was 94.30%, and the whiteness of the de-icing agent was 98.5. The reason for the decrease in the yield of the de-icing agent was that, under the condition that the amount of ethanol and ethyl acetate added remained unchanged, the Ca in the solution increased. 2+ Mg 2+ A decrease in concentration leads to a decrease in alcohol precipitation yield. Comparison of data from Comparative Example 13 and Example 1 shows that activated carbon affects the Ca... 2+ Mg 2+ Fe 3+ The adsorption rates were 9.82%, 16.67%, and 100%, respectively, for Ca. 2+ and Mg 2+ Large adsorption capacity leads to Ca 2+ and Mg 2+ To avoid wasting ingredients, it is important to choose a suitable impurity removal agent.

[0140]

[0141] As can be seen from the above, by comparing Example 1 and Comparative Example 1, it was found that when the ratio of the dry weight of salt mud to water in the slurry is less than 1 g: 2 mL, a viscous solid agglomerate will be formed, which will prevent the acidification reaction from proceeding normally. Therefore, the liquid-solid ratio of water to salt mud is an important factor in determining whether the acidification reaction can proceed, and the liquid-solid ratio should not be too low. Comparing Example 1 with Comparative Examples 2-3, it is evident that both dispersants and acidifying aids affect the utilization rate of salt mud and the extraction rate of effective components, with the acidifying aid having the greatest impact. Without the addition of the acidifying aid, a low liquid-to-solid ratio acidification reaction cannot be carried out, resulting in a lower concentration solution. Consequently, under the same alcohol precipitation conditions, the alcohol precipitation efficiency is affected, thus increasing process costs. The dispersant not only improves the dispersibility of the salt mud but also enhances the hydrophilicity of the solution, reducing surface tension and preventing the carbon dioxide bubbles generated during the reaction from adhering tightly to the salt mud. The acidifying aid suppresses large carbon dioxide bubbles in the reaction, generating more small bubbles that are easier to break. The simultaneous addition of both dispersants and acidifying aids has a good synergistic effect, jointly promoting the acidification reaction. Comparing Example 1 with Comparative Example 4, it is evident that the reaction time affects the result of the acidification reaction, and the reaction time should be appropriately controlled. Comparing Example 1 with Comparative Example 5, it is evident that chitosan can selectively adsorb Fe. 3+ It improves the whiteness of the snow-melting agent without significantly affecting the Ca2+ content. 2+ and Mg 2+ Concentration. Comparing Example 1 with Comparative Examples 6-7 shows that ethanol can precipitate the de-icing agent, but the precipitation efficiency is low. Ethyl acetate cannot precipitate the de-icing agent. Combining the two promotes the precipitation of the de-icing agent and has a synergistic effect. Furthermore, ethanol and ethyl acetate have low boiling points, making them easy to recover and reuse, resulting in low energy consumption. Comparing Example 1 with Comparative Examples 8-9 shows that the ratio and amount of ethanol and ethyl acetate in the alcohol precipitation solution affect the precipitation efficiency. Appropriate parameter control is necessary to maximize efficiency. Comparing Example 1 with Comparative Example 10 shows that the traditional method of preparing de-icing agents by evaporation and concentration is not only slow but also energy-intensive. Comparing Example 1 with Comparative Examples 11-12 shows that ketone organic solvents such as acetone and amine organic solvents such as N,N-dimethylformamide cannot precipitate the de-icing agent. Not all organic solvents can precipitate the de-icing agent; the choice of organic solvent is limited, considering not only the precipitation rate of the de-icing agent but also the yield and cost. As can be seen from Example 1 and Comparative Example 13, different impurity removal agents have different effects on Ca. 2+ Mg 2+ Fe 3+ Different adsorption effects exist, so the appropriate adsorption method should be selected for Fe. 3+ It has strong adsorption capacity, but is not effective against Ca. 2+ Mg 2+ Impurity removal agents (adsorbents) that do not adsorb impurities.

Claims

1. A method for preparing de-icing agent through comprehensive utilization of chlor-alkali salt sludge solid waste, characterized in that, Includes the following steps: (1) Prepare a slurry by mixing salt mud with water, and control the ratio of salt mud mass to water in the slurry on a dry basis to be 1g:2-4mL. Then add acidification aid and dispersant to the slurry to obtain the first mixed solution. (2) Under stirring, add 37% concentrated hydrochloric acid to the first mixed solution at one time, react at 25-55℃ for 0.5-2h, and after separation, obtain the residue and the second mixed solution; (3) Add calcium-containing alkaline substances to the second mixed solution to adjust the pH to 7-8.9, then add chitosan, stir the reaction for 0.5-1h, and after separation, obtain the adsorbed chitosan and the third mixed solution. The adsorbed chitosan is then regenerated and reused. (4) Prepare an alcohol precipitation solution by mixing ethanol and ethyl acetate, add the alcohol precipitation solution to the third mixed solution to carry out the alcohol precipitation reaction, and obtain the fourth mixed solution; (5) The fourth mixed solution is separated to obtain crude de-icing agent and fifth mixed solution; the crude de-icing agent is dried to obtain de-icing agent; the fifth mixed solution is distilled under reduced pressure, and a mixture of gaseous ethanol, ethyl acetate and water is obtained at the top of the distillation column. The mixture of gaseous ethanol, ethyl acetate and water is condensed to obtain the sixth mixed solution; the reaction residue is obtained at the bottom and is recycled. (6) Add 3A molecular sieve to the sixth mixed solution for adsorption, and then separate the solution to obtain alcohol precipitation solution and adsorbed 3A molecular sieve. Return the alcohol precipitation solution to step (4) for recycling and reuse. The adsorbed 3A molecular sieve is regenerated and reused. In step (1), the dispersant is sodium dodecyl sulfate or sodium polyacrylate; the acidification aid is allyl polyoxyalkyl epoxy ether or allyl alcohol polyoxyalkyl ether or nonylphenol polyoxyethylene ether.

2. The method for preparing de-icing agent through comprehensive utilization of chlor-alkali salt sludge solid waste according to claim 1, characterized in that, In step (1), the ratio of the amount of dispersant added to the total amount of water in the first mixed solution is 0.02-0.04 g: 1 mL; the ratio of the amount of acidifying agent added to the total amount of water in the first mixed solution is 0.001-0.005 g: 1 mL.

3. The method for preparing de-icing agent through comprehensive utilization of chlor-alkali salt sludge solid waste according to claim 1, characterized in that, In step (2), the stirring speed is 100-300 r / min; the mass ratio of concentrated hydrochloric acid with a mass fraction of 37% to the dry salt mud in the first mixed solution is 0.02-0.024 mol: 1 g.

4. The method for preparing de-icing agent through comprehensive utilization of chlor-alkali salt sludge solid waste according to claim 1, characterized in that, In step (3), the calcium-containing alkaline substance is calcium oxide or calcium hydroxide; In step (3), the ratio of the amount of chitosan added to the total amount of water in the first mixed solution is 0.04-0.08 g: 1 mL; In step (3), the conditions for regenerating and reusing the adsorbed chitosan are as follows: soaking in 0.01-0.03 mol / L nitric acid solution for 0.3-0.5 h, then separating, and vacuum drying at 100-150℃ for 2-5 h.

5. The method for preparing de-icing agent through comprehensive utilization of chlor-alkali salt sludge solid waste according to claim 1, characterized in that, In step (4), the volume ratio of ethanol to ethyl acetate is 1:1-3; the volume ratio of the added alcohol precipitation solution to the third mixed solution is 2-8:

1.

6. The method for preparing de-icing agent through comprehensive utilization of chlor-alkali salt sludge solid waste according to claim 1, characterized in that, In step (4), the alcohol precipitation reaction conditions are: alcohol precipitation temperature 5-30℃, alcohol precipitation time 0.2-0.5h, and stirring speed 100-150r / min.

7. The method for preparing de-icing agent through comprehensive utilization of chlor-alkali salt sludge solid waste according to claim 1, characterized in that, In step (5), the drying conditions are: vacuum drying at 40-80℃ and vacuum drying time of 1-2h; the reaction residue is recycled and reused by returning the reaction residue to step (1) to be used as water.

8. The method for preparing de-icing agent through comprehensive utilization of chlor-alkali salt sludge solid waste according to claim 1, characterized in that, In step (6), the adsorption treatment conditions are as follows: the amount of 3A molecular sieve added is 2-5% of the mass of the sixth mixed solution, the adsorption time is 0.5-1h, and the stirring speed is 100-300r / min.

9. The method for preparing de-icing agent through comprehensive utilization of chlor-alkali salt sludge solid waste according to claim 1, characterized in that, In step (6), the conditions for regenerating and reusing the adsorbed 3A molecular sieve are: vacuum drying temperature 100-150℃ and vacuum drying time 1-3h.

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