阅读说明：本技术 一种酯化法资源化全利用氯化钠废渣盐的方法 (Method for recycling and fully utilizing sodium chloride waste slag salt by esterification method ) 是由 冯春全 李政 周含峰 于 2020-05-31 设计创作，主要内容包括：本发明属于工业废盐渣处理技术领域,公开了一种酯化法资源化全利用氯化钠废渣盐的方法。在含醇类氯化钠废盐渣中加入酰氯和碱催化剂,搅拌混合反应后过滤；将正己烷加入得到的溶液中,搅拌混合均匀,静置分层,上层液体进行回收得到酯化产物；下层溶液加入碳酸钠溶液,静置并过滤,滤渣进行干燥回收,滤液中加入盐酸,静置后加热浓缩,分离析出的晶体并干燥,得到纯化的氯化钠。本发明方法通过常温处理,高效、彻底地酯化盐渣中的醇类有机物,达到提纯氯化钠的目的,同时回收可资源化利用的酯类物质,为化工行业实现节能减排提供技术支撑,促进化工行业的可持续协调发展。(The invention belongs to the technical field of industrial waste salt residue treatment, and discloses a method for recycling and fully utilizing sodium chloride waste salt by an esterification method. Adding acyl chloride and an alkali catalyst into the waste salt slag containing the alcohol sodium chloride, stirring, mixing, reacting and filtering; adding n-hexane into the obtained solution, stirring and mixing uniformly, standing for layering, and recovering the upper layer liquid to obtain an esterification product; adding a sodium carbonate solution into the lower-layer solution, standing and filtering, drying and recovering filter residues, adding hydrochloric acid into the filtrate, standing, heating and concentrating, separating out crystals, and drying to obtain purified sodium chloride. According to the method, the alcohol organic matters in the salt residues are efficiently and thoroughly esterified through normal-temperature treatment, the aim of purifying sodium chloride is achieved, ester substances capable of being recycled are recycled, technical support is provided for the chemical industry to achieve energy conservation and emission reduction, and sustainable coordinated development of the chemical industry is promoted.)

1. A method for recycling and fully utilizing sodium chloride waste slag salt by an esterification method is characterized by comprising the following processing steps:

(1) adding acyl chloride and an alkali catalyst into the waste salt slag containing the alcohol sodium chloride, stirring, mixing, reacting and filtering;

(2) adding n-hexane into the solution obtained in the step (1), stirring and mixing uniformly, standing for layering, separating upper and lower layer liquid, and recovering the upper layer liquid to obtain an esterification product;

(3) taking the lower layer solution obtained by separation in the step (2), adding a sodium carbonate solution while stirring, standing and filtering after the addition is finished, and drying and recovering filter residues obtained by filtering;

(4) and (4) adding hydrochloric acid into the solution obtained by filtering in the step (3), standing, heating and concentrating, separating precipitated crystals, and drying to obtain purified sodium chloride.

2. The method for recycling and fully utilizing sodium chloride waste residue salt by the esterification method according to claim 1, which is characterized by comprising the following steps: the acyl chloride in the step (1) is at least one of acetyl chloride, benzoyl chloride, oxalyl chloride, chloroacetyl chloride and trichloroacetyl chloride; the ratio of the waste salt residues containing alcohol sodium chloride to acyl chloride is 0.12-0.25 kg/L.

3. The method for recycling and fully utilizing sodium chloride waste residue salt by the esterification method according to claim 1, which is characterized by comprising the following steps: the alkali catalyst in the step (1) is at least one selected from sodium hydroxide, pyridine and amine; the addition concentration of the alkali catalyst is 1-10 wt.%.

4. The method for recycling and fully utilizing sodium chloride waste residue salt by the esterification method according to claim 1, which is characterized by comprising the following steps: and (3) adding the n-hexane in the step (2) in an amount of 5-20 wt% of the solution obtained by filtering in the step (1).

5. The method for recycling and fully utilizing sodium chloride waste residue salt by the esterification method according to claim 1, which is characterized by comprising the following steps: and (3) standing for 5-10 min in the step (2).

6. The method for recycling and fully utilizing sodium chloride waste residue salt by the esterification method according to claim 1, which is characterized by comprising the following steps: the mass ratio of the addition amount of the sodium carbonate to the waste salt residues containing the alcohol sodium chloride in the step (3) is (6.0-7.5): 1000; the concentration of the sodium carbonate solution is 10 g/L.

7. The method for recycling and fully utilizing sodium chloride waste residue salt by the esterification method according to claim 1, which is characterized by comprising the following steps: the proportion of the amount of the hydrochloric acid used in the step (4) to the waste salt residues containing the alcohol sodium chloride is (0.3-0.5) 1 mol/kg; the hydrochloric acid is a hydrochloric acid solution with the concentration of 1 mol/L.

8. The method for recycling and fully utilizing sodium chloride waste residue salt by the esterification method according to claim 1, which is characterized by comprising the following steps: and (4) standing for 2-3 min.

9. The method for recycling and fully utilizing sodium chloride waste residue salt by the esterification method according to claim 1, which is characterized by comprising the following steps: and (4) heating at the temperature of 60-90 ℃.

Technical Field

The invention belongs to the technical field of industrial waste salt residue treatment, and particularly relates to a method for recycling sodium chloride waste salt by an esterification method.

Background

In the production process of a plurality of fine chemical industry and chemical pesticide products or intermediates, a large amount of byproduct waste salt containing toxic and harmful chemical substances is generated, for example, 4-5 tons of byproduct sodium chloride waste salt containing toxic and harmful chemical substances is generated every 1 ton of hydrazine hydrate, 1.1-1.4 tons of byproduct sodium chloride salt containing toxic and harmful chemical substances is generated every 1 ton of glyphosate pesticide, the byproduct sodium chloride waste salt containing alcohol type waste salt containing toxic and harmful chemical substances is generated in the production of trimethyl orthoformate, the amount of byproduct sodium chloride waste salt in the national chemical industry reaches more than 100 million tons every year, and with the development of a plurality of important fine chemical industry and intermediate products, the amount of byproduct waste salt is continuously increased, so that the byproduct waste salt becomes a bottleneck for hindering the development of the industry. The salt slag which is a byproduct of the chemical production is easy to agglomerate and difficult to treat due to the moisture content, and can not be directly used as an industrial raw material due to the toxic and harmful chemical substances, so that most enterprises can pile the salt slag in the open or directly dump the salt slag into rivers. The long-term stacking of the salt slag not only occupies a large amount of land, but also poses great threat to the environment. Most of the waste salts are soluble salts, and the soluble salts and toxic and harmful chemical substances are lost along with rainwater, so that the waste salts seriously salinize surrounding soil, destroy surrounding vegetation, deteriorate water quality and pollute water sources, and the waste salts seriously threaten the life of people. Therefore, the harmless treatment and resource utilization of the byproduct waste salt become important problems which are urgently needed to be solved by the industry.

Taking the fine chemical industry and the intermediate product industry as an example, in the preparation process of the product, a large amount of by-products of waste salt residues containing methanol and sodium chloride are produced, and the by-products mainly comprise sodium chloride, calcium carbonate, alcohols (methanol, ethanol, butanol and the like) and other substances. Because alcohols have the characteristics of flammability and explosiveness, the treatment of the sodium chloride waste salt residues becomes a bottleneck problem which hinders the development of the industry. The current treatment methods for byproduct waste salt in chemical production are reported to be mainly three types: (1) direct thermal incineration: the method is that the waste salt slag is directly added to the top of an incinerator, the materials are heated at about 900 ℃ from top to bottom, inorganic salt is melted and flows into the bottom of the incinerator, the inorganic salt is cooled and then recovered, the organic matters contained in the inorganic salt are volatilized and decomposed at high temperature, the furnace gas enters a secondary combustion chamber for further combustion or is directly treated by physical chemistry and then discharged, for example, the method of harmless treatment and resource utilization of the waste salt slag of the industrial byproduct of CN 103267296B; CN 104344407B is a harmless treatment method of industrial waste salt slag. However, these methods require pre-drying of the waste salt slag and require the waste salt slag to have uniform particles and as small particle sizes as possible, and are very likely to cause clogging and damage of the apparatus. (2) And (3) secondary concentration and crystallization treatment after dissolution and refining: the method is to re-dissolve the waste salt slag in fresh water, concentrate and crystallize after chemical treatment and recycle, for example, CN 105883911B molten salt chlorination slag resource treatment method, CN 103979576A method for evaporating and crystallizing salt slag from organic waste water containing ammonium sulfate; however, the methods have high treatment cost, secondary wastewater is generated, the effect of physical and chemical treatment after dissolution is difficult to guarantee, the water content of the recrystallized recycled salt is high, a large amount of crystal water exists in some of the methods, and the secondary utilization value is low. (3) Harmless landfill disposal: the method is to mix various waste salt residues, solidify the waste salt residues by curing agents such as concrete and the like, and perform special landfill disposal according to relevant regulations and technical specifications of national hazardous waste management and disposal. The disposal method is high in cost, not only occupies a large amount of land, but also has the risk of secondary environmental damage caused by external factors such as geological disasters.

At present, most people concentrate on the research on the synthesis and preparation methods of front-end chemical products, but the research on the comprehensive recovery and treatment methods of process waste salt is less, so that the waste salt generated in the synthesis process of many chemical products is not effectively treated all the time, and the waste of a large amount of recoverable resources is caused.

Patent CN 109455741A discloses a method for recycling and fully utilizing sodium chloride waste salt slag by using a low-temperature roasting and interface regulation and control combined method. The low boiling point characteristic of the organic matter is utilized to carry out low temperature roasting of inert gas to carbonize the organic matter, thereby achieving the purpose of purifying sodium chloride. The normal hexane and the sodium oleate have the function of surface interface regulation and control, and the principle is the interaction of chemical groups in two phases, so that organic matters of an inorganic phase are transferred to an organic phase, the sodium chloride solution of the inorganic phase is further purified, and carbon which can be used in a high-value mode is recovered. However, in the method, low-temperature roasting is firstly utilized to convert part of organic impurities into carbon materials for recycling, but the method inevitably generates higher energy consumption; then, the interface regulating agent is used for further recovering the residual organic matters in the waste salt, but the qualitative and quantitative analysis is not carried out on the organic matters in the waste salt, so that the organic matters occupying the main position in the waste salt cannot be recovered in a targeted manner, and the final recovery efficiency of the organic matters is low. Therefore, organic reaction can be designed according to the characteristic of organic impurities occupying the main part in the waste salt, a method which is lower in energy consumption and can efficiently recover organic matters is developed, and then inorganic salt is further purified deeply.

Disclosure of Invention

Aiming at the defects and shortcomings of the prior art, the invention aims to provide a method for recycling sodium chloride waste slag salt by an esterification method. The method has the advantages of simple process, low cost, quick response, large treatment capacity and thorough purification, and can realize the full utilization of the waste salt residues of the alcohol-containing sodium chloride. The sodium chloride extracted by the method can be reused for preparing industrial raw materials such as chlorine, hydrogen, bleaching powder, metal sodium and the like, and for salting out soap, tanning leather, food seasoning, pickling fish, meat, vegetables and the like; the calcium carbonate obtained by the method can be used as a filler and a composite material in the industries of coating, printing ink, daily chemicals, plastics, plastic steel doors and windows, PVC cable materials, papermaking, rubber, soles, polyethylene blown films, sealing rubber strips, profiles, pipes, building materials, ceramics and the like; the recovered organic solvent can be used in the production processes of resin, coating, printing ink, paint, adhesive, leather and the like. The complete waste is changed into valuable.

The purpose of the invention is realized by the following technical scheme:

a method for recycling and fully utilizing sodium chloride waste slag salt by an esterification method comprises the following processing steps:

(1) adding acyl chloride and an alkali catalyst into the waste salt slag containing the alcohol sodium chloride, stirring, mixing, reacting and filtering;

(2) adding n-hexane into the solution obtained in the step (1), stirring and mixing uniformly, standing for layering, separating upper and lower layer liquid, and recovering the upper layer liquid to obtain an esterification product;

(3) taking the lower layer solution obtained by separation in the step (2), adding a sodium carbonate solution while stirring, standing and filtering after the addition is finished, and drying and recovering filter residues obtained by filtering;

(4) and (4) adding hydrochloric acid into the solution obtained by filtering in the step (3), standing, heating and concentrating, separating precipitated crystals, and drying to obtain purified sodium chloride.

Preferably, the acyl chloride in the step (1) is at least one selected from acetyl chloride, benzoyl chloride, oxalyl chloride, chloroacetyl chloride and trichloroacetyl chloride; the ratio of the waste salt residues containing alcohol sodium chloride to acyl chloride is 0.12-0.25 kg/L.

Preferably, the base catalyst in step (1) is selected from at least one of sodium hydroxide, pyridine and amine; the addition concentration of the alkali catalyst is 1-10 wt.%.

Preferably, the n-hexane is added in the step (2) in an amount of 5-20 wt% of the solution obtained by filtering in the step (1).

Preferably, the standing time in the step (2) is 5-10 min.

Preferably, the mass ratio of the addition amount of the sodium carbonate to the waste salt residues containing the alcohol sodium chloride in the step (3) is (6.0-7.5): 1000; the concentration of the sodium carbonate solution is 10 g/L.

Preferably, the ratio of the use amount of the hydrochloric acid in the step (4) to the waste salt residues containing the alcohol sodium chloride is (0.3-0.5) 1 mol/kg; the hydrochloric acid is a hydrochloric acid solution with the concentration of 1 mol/L.

Preferably, the standing time in the step (4) is 2-3 min.

Preferably, the heating temperature in the step (4) is 60-90 ℃.

The principle of the invention is as follows:

the characteristic that alcohol substances are easy to generate esterification reaction with acyl chloride is utilized, the alcohol substances and the acetyl chloride are fully mixed to generate esterification products which can be recycled, and other impurity ions can not be introduced in the esterification reaction, so that the aim of purifying sodium chloride is fulfilled. Meanwhile, the n-hexane has the function of surface interface regulation and control, and the principle is the interaction of chemical groups in two phases, so that organic matters (esterification products) in an inorganic phase (sodium chloride solution) are transferred to an organic phase (n-hexane), and the esterification products are obtained by recovery. And adding a sodium carbonate solution into the inorganic phase solution for precipitation reaction to obtain nano calcium carbonate, thereby further purifying the inorganic phase sodium chloride solution. Adding hydrochloric acid into the residual inorganic phase solution, heating, concentrating, crystallizing and drying to obtain purified sodium chloride.

The treatment method of the invention has the following advantages and beneficial effects:

(1) through normal temperature treatment, alcohol organic matters in the salt residues are esterified efficiently and thoroughly, the aim of purifying sodium chloride is achieved, ester substances capable of being recycled are recovered, technical support is provided for the chemical industry to achieve energy conservation and emission reduction, and sustainable coordinated development of the chemical industry is promoted.

(2) The method can realize the resource full utilization of the sodium chloride waste residue and salt, and has no pollution discharge.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.