CN116986741B

CN116986741B - Composition for salt anticaking agent, salt anticaking agent and application of salt anticaking agent

Info

Publication number: CN116986741B
Application number: CN202311056992.5A
Authority: CN
Inventors: 岳科红; 蒋国良; 岳鹏飞
Original assignee: Changzhou Jingpeng Environmental Protection Technology Co ltd; Changzhou Kejing Environmental Protection Technology Co ltd
Current assignee: Changzhou Jingpeng Environmental Protection Technology Co ltd; Changzhou Kejing Environmental Protection Technology Co ltd
Priority date: 2023-08-22
Filing date: 2023-08-22
Publication date: 2025-10-31
Anticipated expiration: 2043-08-22
Also published as: CN116986741A

Abstract

The invention discloses a composition for a salt anti-caking agent, the salt anti-caking agent and application thereof, and belongs to the technical field of salt-containing wastewater treatment. The composition for the salt anticaking agent comprises ferrocyanide salt, a high-temperature stabilizer, a crystal nucleus dispersing agent and a nucleating agent which is selectively contained, wherein the weight ratio of the ferrocyanide salt to the nucleating agent is 1 (0.3-2.0) (0.05-0.25) (0-0.10), and the composition does not contain a metal chelating agent. The salt anti-caking agent can furthest change the salt crystallization process and the adhesive force on the surface of salt particles in the solution, greatly increase the number of crystal nuclei, lead the particles of salt crystals to become fine, reduce the binding force among salt particles, and avoid aggregation into large-block particles, thereby inhibiting, preventing or reducing the formation of large-block salt. The salt anti-caking agent can be applied to salt-containing wastewater drying and/or crystallization recovery waste salt processes in industries such as fine chemical industry, petrochemical industry and coal chemical industry, desulfurization and water treatment industry, garbage treatment, metallurgical industry, hazardous waste treatment and the like.

Description

Composition for salt anticaking agent, salt anticaking agent and application of salt anticaking agent

Technical Field

The invention belongs to the technical field of salt-containing wastewater treatment, relates to application of a salt anti-caking agent in a process for drying and/or crystallizing salt-containing wastewater and recycling waste salt, and in particular relates to a composition for the salt anti-caking agent, the salt anti-caking agent and application thereof.

Background

MVR evaporation technology is widely applied to various fields such as biochemical industry, petrochemical industry, pharmacy, food manufacturing, environmental protection, sea water desalination and the like. The MVR technology can well solve the problem of difficult RO concentrated water treatment, the MVR evaporation technology is used for treating reverse osmosis concentrated water, the RO concentrated water can be re-concentrated, meanwhile, the distilled water can be reused, the combination of wastewater treatment and recycling is realized, the concentration is carried out to a crystallization stage, inorganic salt or wastewater can be obtained through subsequent treatment, spray drying is carried out on the crystallization, condensate and waste salt are recovered, and the purpose of zero emission of industrial wastewater is achieved. Industrial wastewater is concentrated by wastewater, enters spray drying equipment for drying and salting out, and in the salt crystallization process, inorganic salt, especially inorganic salt such as sodium chloride and sodium sulfate, often causes hardening of crystal salt on the inner wall of the drying equipment, poor salt fluidity, blockage of equipment pipelines, difficult cleaning, equipment failure or production shutdown. In the dangerous waste incineration treatment industry, when salt-containing wastewater is sprayed back into a quenching tower to recover waste salt, the waste salt is separated out not only at the bottom of the quenching tower, but also at the inner wall of the quenching tower to form a dense hard salt layer with the thickness of tens of centimeters to several meters, so that a channel is easily blocked, and the device is stopped. In order to put the device back into operation, manual removal of salt deposits is necessary. On one hand, the generation of salt deposit seriously affects the normal operation of the device, and on the other hand, the operation environment for cleaning salt in the other area is worse, so that great health influence and potential safety hazard are brought to operators. Therefore, a method is needed to obtain crystallized salt powder, which has good fluidity, is easy to rinse and self-clean, and is easy to post-treat.

CN112079454a discloses a salt inhibitor for salt-containing waste water back-spraying quenching tower process, its effective component includes water-soluble ferrocyanide salt, preferably any one or more than two of potassium ferrocyanide, sodium ferrocyanide, calcium ferrocyanide and ammonium ferrocyanide. CN112079452a discloses a polycarboxylic acid salt inhibitor for salt-containing wastewater back-spraying quench tower process, the active ingredient comprises a polybasic organic carboxylic acid and/or its salt, including but not limited to any one or more than two mixtures of ethylenediamine tetraacetic acid, citric acid, tartaric acid, succinic acid, nitrilotriacetic acid, diethylenetriamine pentaacetic acid, and gluconic acid. US3213018 discloses that the addition of small amounts of a compound MXn having a complex anionic form to a saturated or high concentration sodium chloride solution can effectively prevent substantial crystallization of NaCl due to temperature decrease. Wherein M can be Fe or Co, X can be (CN), (NO ₂) or (C ₂O₄), and n takes on the value of 3 when X is oxalate and other takes on the value of 6.

Zhao Fang [ preparation of sustained-release salt inhibitors study [ D ]. Shandong university, 2006] reported that in salt inhibition experiments, either ferrocyanide alone or polyacrylic acid polymer alone could change sodium chloride crystals from cubic to loose crystals.

Liu Renzhi et al [ potassium ferrocyanide has a crystallization inhibition effect on sodium chloride [ J ]. And university of south China university school (Nature science and medical edition), 2015,36 (6): 448-452] report the process and mechanism of K ₄Fe(CN)₆ on the crystallization inhibition effect on NaCl. The result shows that K ₄Fe(CN)₆ has an adsorption effect on Na ⁺, inhibits the formation of crystal nuclei, changes NaCl from the original cubic crystal form into the dendritic crystal form in the crystallization process, and promotes unbalanced growth of the crystal to form a dendritic structure.

The patent and literature studies show that adding ferrocyanide or water-soluble polymer into solution containing sodium chloride can raise the solubility of salt obviously, delay crystallization, change phase and raise the concentration of salt water, and change the shape of salt crystal. Particularly, due to the viscosity of the water-soluble polymer, salt crystallization is difficult, crystals are crosslinked mutually, salt hardening is increased, the fluidity of salt crystals is reduced, and the transportation and the discharge of the salt crystals are not facilitated. In addition, the flue gas inlet temperature of a quenching tower of a hazardous waste incineration enterprise is often more than 500 ℃, the temperature range is generally 500-650 ℃ according to different process conditions, at such high temperature, organic salt inhibitors can be thermally decomposed, the thermal decomposition temperature of polycarboxylic acid compounds (such as sodium polyacrylate, hydrolyzed polymaleic acid and the like) is less than 300 ℃, even common salt anti-caking agents such as potassium ferrocyanide begin to decompose at the temperature of more than 400 ℃, and at the conventional flue gas temperature operation conditions of 520-620 ℃, the salt is almost completely decomposed, and a good salt anti-caking effect cannot be achieved.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a composition for a salt anti-caking agent, the salt anti-caking agent and application of the salt anti-caking agent in a process for drying and/or crystallizing salt-containing wastewater to recover waste salt.

In order to achieve the above object, the present invention provides a composition for a salt anticaking agent.

The composition for the salt anti-caking agent does not contain a metal chelating agent, and comprises ferrocyanide salt, a high-temperature stabilizer, a crystal nucleus dispersing agent and a nucleating agent which are optionally contained, wherein the weight ratio of the ferrocyanide salt to the high-temperature stabilizer to the crystal nucleus dispersing agent to the nucleating agent is 1 (0.3-2.0) (0.05-0.25) (0-0.10), and the preferred weight ratio is 1 (0.5-1.0) (0.10-0.20) (0-0.05).

Among the above components, the ferrocyanide salt is one of the important constituent components in the composition for a salt anticaking agent. The ferrocyanide salt is at least one of potassium ferrocyanide, sodium ferrocyanide and ammonium ferrocyanide.

It is well known to those skilled in the art that the addition of ferrocyanide salt to a sodium chloride solution or a solution having sodium chloride as the major salt component can alter the crystalline form of sodium chloride in the solution. The addition of ferrocyanide salts to the brine waste affects the crystallization process of the salt species in the brine waste, particularly the crystallization process of sodium chloride. The principle is that the interface state and growth order of microcrystals are changed, so that crystals (especially sodium chloride crystals) are changed from a hard regular cube structure into a loose irregular dendritic structure, and salt grains are reduced, thereby achieving the effect of preventing hardening salt. In addition, in the hazardous waste treatment industry, in the waste water back spraying process, the designed flue gas temperature at the inlet of a quenching tower is 500-650 ℃, and according to the literature report, potassium ferrocyanide/sodium can decompose extremely toxic cyanide solid or gas when the temperature is higher than 400 ℃, and when the flue gas temperature is more than or equal to 520 ℃, the potassium ferrocyanide/sodium is almost completely decomposed, so that the salt-formation resisting effect is greatly reduced or lost. Therefore, high temperature stabilizers must be added, or the temperature conditions used reduced, to mitigate or reduce the decomposition of the ferrocyanide salt.

Among the above components, the high temperature stabilizer is one of the important constituent components in the composition for salt anticaking agent, and the addition of the high temperature stabilizer can significantly reduce the decomposition of ferrocyanide salt at a temperature of more than 400 ℃. The high-temperature stabilizer is at least one of potassium hydroxide, sodium carbonate, potassium carbonate and lithium carbonate.

The applicant found in the actual production operation that the addition of sodium carbonate to potassium/sodium ferrocyanide can improve the salt anti-caking properties of the mixture at high temperatures. For example, under the same dosing concentration, the time of salt formation on the inner wall of the quenching tower is prolonged to more than 6 months (sodium carbonate is added) from 2 months (sodium carbonate is not added) at the actual operation inlet temperature of the quenching tower smoke of a certain dangerous waste incineration enterprise of 520-620 ℃. The applicant has also tested potassium hydroxide, sodium hydroxide, potassium carbonate and lithium carbonate, all of which improve the salt anti-caking properties at high temperatures. The reason is that the burnt flue gas is the flue gas containing acid gas according to the production process, the acid gas can cause ferrocyanide salt in the solution to generate ferricyanic acid, the ferricyanic acid is unstable and easy to decompose, so that the anti-caking property of the ferrocyanide salt disappears, and the acid gas can be neutralized by adding the high-temperature stabilizer, so that acidification and decomposition caused by the generation of the ferricyanic acid are avoided. The applicant has further verified by thermogravimetric analysis experiments that by increasing the aqueous solution of the salt anticaking agent to alkaline, in particular to a pH above 10, the degree of thermal decomposition of the ferrocyanide salt can be significantly reduced, whereas the more ferrocyanide is decomposed when the pH of the solution is adjusted from alkaline to weakly acidic. When salt anti-caking agent is added into the salt-containing wastewater and the pH value of the salt-containing wastewater solution is maintained to be alkaline, salt blocks are not easy to form on the inner wall of the drying equipment than when the salt-containing wastewater solution is neutral or slightly acidic, and the waste salt is easy to keep the powder flowing easily.

Among the above components, the crystal nucleus dispersant is one of the important constituent components in the composition for salt anticaking agent. The crystal nucleus dispersing agent is a copolymer formed by sulfonic acid group-containing olefin and carbonyl group-containing olefin with the carbon number of 3-4, the mol percent of structural units formed by the sulfonic acid group-containing olefin is 10-25 percent based on the total amount of the crystal nucleus dispersing agent, and the weight average molecular weight of the crystal nucleus dispersing agent is 1500-50000. The crystal nucleus dispersant contains carbonyl olefin of acrylic acid and/or maleic acid/anhydride and at least one of 2-methyl-2-acrylamide propane sulfonic acid, ethylene sulfonic acid, styrene sulfonic acid, 3-allyloxy-2-hydroxy propane sulfonic acid and allyl polyethylene glycol sulfonic acid.

The use amount of the crystal nucleus dispersing agent is not too small or too excessive, and the dispersing agent is too small to play a role in dispersing, and the excessive dispersing agent is a polymer, so that salt crystallization is difficult due to the viscosity of the polymer, crystals are crosslinked with each other, salt hardening is increased, the fluidity of salt crystals is reduced, and the transportation and the discharge of the salt crystals are not facilitated. The optimal dosage of the crystal nucleus dispersing agent is kept at the concentration of 0.02 kg-2.5 kg/ton of dry salt in the salt-containing wastewater. When the drying operation temperature exceeds 300 ℃, the negative effect of the dispersant on the salt may not be considered due to the pyrolysis of the polymer. Because the salt-containing wastewater often contains trace heavy metal ions, the heavy metal ions can react with ferrocyanide salt in the salt anticaking agent to generate indissolvable compounds, and after the crystal nucleus dispersing agent is added, the indissolvable compounds can be kept in a suspension state and cannot be precipitated, so that the process of inducing crystallization can be realized in the salt crystallization process, and the crystallization refinement is promoted.

Among the above components, the nucleating agent is an optional component in the composition for salt anticaking agent. The nucleating agent is a soluble metal ion, such as at least one of Zn²⁺、Fe³⁺、Cd²⁺、Ni²⁺、Pb²⁺、Co²⁺、Cu²⁺、Ag⁺、Mn²⁺、Al³⁺, other soluble metal ions capable of forming a precipitate in aqueous solution with ferrocyanide salt, or soluble metal ions capable of forming a precipitate in alkaline aqueous solution can be used as the nucleating agent.

In particular, when the salt-containing wastewater contains heavy metal ions (such as at least one of Zn²⁺、Fe³⁺、Cd²⁺、Ni²⁺、Pb²⁺、Co²⁺、Cu²⁺、Ag⁺、Mn²⁺、Al³⁺), a nucleating agent is not needed, because ferrocyanide salts in the salt anticaking agent react with the heavy metal ions to generate a large amount of precipitates which can be used as heterogeneous crystal nuclei, and when the salt-containing wastewater does not contain heavy metal ions, nucleating agents such as Zn²⁺、Fe³⁺、Cd²⁺、Ni²⁺、Pb²⁺、Co²⁺、Cu²⁺、Ag⁺、Mn²⁺、Al³⁺ and the like can be additionally added, and the ions can react with the ferrocyanide salts to form precipitates or can generate insoluble matters as heterogeneous crystal nuclei under the alkaline aqueous solution condition. The concentration of the nucleating agent in the salt-containing wastewater is kept to be less than 0.05 kg/ton of dry salt.

Of the above components, the present invention is particularly limited to the salt anticaking agent composition which does not contain a metal chelator. This is because the use of metal chelators greatly reduces the rate and extent of crystallization nucleation, interfering with the formation of small nuclei and thus reducing the effect of the nucleating agent. The metal chelating agent described herein is a carboxyl group-containing or phosphonic group-containing organic substance capable of forming a soluble chelate with the aforementioned nucleating agent. The metal chelating agent may be a commercially available metal chelating agent, mainly chelating agents containing an acetoacetate group, chelating agents containing a hydroxyacetate group, chelating agents containing an ethylenephosphonate group, polycarboxylic acid homopolymers, etc., as long as they can form a soluble chelate with the above-mentioned nucleating agent (e.g., Zn²⁺、Fe³⁺、Cd²⁺、Ni²⁺、Pb²⁺、Co²⁺、Cu²⁺、Ag⁺、Mn²⁺、Al³ ⁺ plasma), and are not used in the composition. Specifically, at least one of nitrilotriacetic acid, ethylenediamine tetraacetic acid, hydroxyethyl ethylenediamine triacetic acid, diethylenetriamine pentaacetic acid, gluconic acid, citric acid, tartaric acid, succinic acid, aminotrimethylene phosphonic acid, hydroxyethylenediphosphonic acid, ethylenediamine tetraethylenephosphonic acid, diethylenetriamine pentamethylene phosphonic acid, triethylenetetramine hexamethylene phosphonic acid, bis (1, 6-methylene) -triamine pentamethylene phosphonic acid, polyaminoether tetramethylene phosphonic acid, polyacrylic acid, polymaleic acid, polyepoxysuccinic acid, polyaspartic acid, and alkaline earth metal salts of the foregoing is mentioned.

The composition for the salt anticaking agent also comprises an antioxidant and/or a reducing agent, and the weight ratio of the antioxidant and/or the reducing agent to ferrocyanide is (0.01-0.05): 1. The antioxidant and/or reducing agent is used because, if the composition for salt anti-caking agent is formulated into an aqueous solution in which the ferrocyanide salt is susceptible to oxidative decomposition by light and air, in general, the aqueous solution of the ferrocyanide salt starts to become cloudy and a brick-red substance is precipitated for several days, thereby affecting salt anti-caking performance and reducing effect, and in order to ensure stability of the ferrocyanide salt in the aqueous solution, the antioxidant and/or reducing agent may be added to the aqueous solution. The antioxidant and/or reducing agent is not particularly limited, and at least one of hydrazine hydrate, carbohydrazide, N-diethylhydroxylamine, hydroxylamine hydrochloride, hydroxylamine sulfate, dimethyl ketoxime, sodium erythorbate, potassium erythorbate, sodium ascorbate, potassium ascorbate, sodium sulfite, potassium sulfite, sodium dithionate, and potassium dithionate may be preferable.

In order to achieve the above object, the present invention also provides a salt anticaking agent.

The salt anticaking agent is an aqueous solution formed by the composition for the salt anticaking agent and water.

In the present invention, the content of the salt anticaking agent composition in the salt anticaking agent may be selected in a wide range as required. Typically, the salt anti-caking agent composition comprises from 10 to 40% by weight of the total salt anti-caking agent, preferably from 20 to 40% by weight of the total salt anti-caking agent, more preferably from 25 to 35%. In addition, the aqueous salt anticaking agent solution has a pH greater than 10, more preferably a pH greater than 12.

In the present invention, the above-mentioned salt anticaking agent can be obtained by various methods in the prior art, for example, it can be obtained by uniformly mixing the raw materials for forming the salt anticaking agent in the aforementioned desired ratio, and thus the present invention has no special requirements for the mixing step and conditions.

In order to achieve the above purpose, the invention also provides application of the salt anti-caking agent in a salt-containing wastewater drying and/or crystallization waste salt recovery process, in particular application in a salt-containing wastewater drying and/or crystallization waste salt recovery process in industries such as fine chemical industry, petrochemical industry, coal chemical industry, desulfurization industry, water treatment industry, garbage treatment industry, metallurgical industry, hazardous waste treatment and the like. The salt-containing wastewater in the industries and industries is one of salt-containing wastewater mainly containing sodium chloride, salt-containing wastewater mainly containing sodium chloride and sodium sulfate and salt-containing wastewater mainly containing sodium chloride and potassium chloride, wherein the mass percentage of the sodium chloride is more than 85%.

When the salt anti-caking agent is used, after the salt anti-caking agent and the salt-containing wastewater are uniformly mixed, the salt-containing wastewater containing the salt anti-caking agent is pumped into crystallization equipment or spray drying equipment or high-temperature drying equipment, and after crystallization or drying is carried out at 25-620 ℃, waste salt solids are recovered. The salt anti-caking agent is added into the salt-containing wastewater according to the effective components, and the salt anti-caking agent has better effect when being added into the salt-containing wastewater according to the addition amount of more than 1.0kg of salt anti-caking agent per ton of dry salt in the salt-containing wastewater, but the salt anti-caking agent is added into the salt-containing wastewater according to the addition amount of 1.0-20.0 kg of salt anti-caking agent per ton of dry salt solid in the salt-containing wastewater for cost reasons, preferably 1.0-10.0 kg of salt anti-caking agent is added into the salt-containing wastewater per ton of dry salt solid, namely 0.1-1.0 kg of salt anti-caking agent is added into the salt-containing wastewater (the salt content of 10 wt.%). When the addition amount of the salt anti-caking agent in the salt-containing wastewater is within the above-described preferred range, excellent salt anti-caking performance is exhibited.

The beneficial technical effects of the invention are as follows:

The components in the composition for the salt anticaking agent can act synergistically, so that the salt anticaking agent formed by the composition for the salt anticaking agent and water has stable chemical property, meets the requirements of environmental protection, has excellent crystallization modification performance, and has the advantages of less consumption, simple treatment process and obvious effect, and is easy to popularize and apply.

According to the salt anti-caking agent, the salt anti-caking agent is added into the salt-containing wastewater before the salt-containing wastewater is dried and/or crystallized, so that the salt-containing wastewater is crystallized or waste salt separated out by drying in the drying equipment can be in a highly dispersed powder state, the viscosity of crystallized salt is obviously reduced, the fineness and the fluidity of the crystallized salt are improved, and the formation of a large salt deposit layer on the inner wall of the equipment is avoided, so that the stop accident caused by the continuous accumulation of a channel of the equipment or the falling and blockage of the large salt deposit is avoided.

Drawings

FIG. 1 is a salt-forming effect graph of a blank applied in scenario 1;

FIG. 2 is one of the salt-forming effects of example 1 of the present application (3.0 g/kg dry salt added) applied in scenario 1;

FIG. 3 is a second graph showing the salt formation effect of example 1 (10.0 g/kg dry salt added) of the present application applied in scenario 1;

FIG. 4 is a third graph showing the effect of salt formation in scenario 1 of example 1 of the present application (20.0 g/kg of dry salt added);

FIG. 5 is a graph showing the salt formation effect of comparative example 1 of the present application applied in scenario 1;

FIG. 6 is a graph showing the salt formation effect of comparative example 3 of the present application applied in scenario 1;

FIG. 7 is a graph showing the salt formation effect of comparative example 4 of the present application applied in scenario 1;

FIG. 8 is a photograph showing the effect of the crystal nucleus dispersant on the crystallization property in Table 2 of the present application, showing the crystallization patterns of examples 1, comparative example 2 and examples 1 to 3;

FIG. 9 is a photograph showing the crystallization of the metal chelator of Table 4 in the present application, showing the crystallization patterns of example 1 and comparative example 5;

FIG. 10 is a photograph showing the crystallization of salt anti-caking agent according to the present application in Table 5, which is a blank, and the crystallization of example 1 according to the amounts of the respective compositions, and the crystallization of examples 2 to 6.

Detailed Description

In order that the manner in which the above recited features of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized below, may be had by reference to specific embodiments thereof which are illustrated in the appended drawings.

The "effective content" used in the following examples and comparative examples means the weight of the components excluding the solvent based on the total weight of the solution, and the reagents used in the examples and comparative examples are all analytically pure reagents (all available from the national medicine group chemical reagent Co., ltd.) (the tests are all converted into the effective content calculation).

The sources and brands of some of the ingredients used in the examples and comparative examples of the present invention are as follows.

Polyacrylic acid (PAA for short, the number average molecular weight is less than 1200, which accords with GB/T10533-2014 water treatment agent polyacrylic acid, and is purchased from Shandong Tai and water treatment Co., ltd.).

Acrylic acid and 2-methyl-2-acrylamidopropane sulfonic acid copolymer (AA/AMPS for short, accords with HG/T3642-2016 water treatment agent acrylic acid-2-methyl-2-acrylamidopropane sulfonic acid copolymer), and is purchased from Shandong Tai and water treatment Co., ltd.

Acrylic acid-hydroxypropyl acrylate copolymer (abbreviated as AA/HPA, brand T-225) was purchased from WUYUN WUYIN water stabilizer mill.

Acrylic acid and 3-allyloxy-2-hydroxypropanesulfonic acid (abbreviated as AA/AHPS) are available from GE Betz, inc. under the brand PY5200.

Acrylic acid and allyl polyethylene glycol sulfonic acid (abbreviated as AA/APES), available from GE Betz, inc. under the trademark AEC3302.

Salt-forming anti-caking agents were prepared as in the following examples and comparative examples.

Example 1

1.0G of potassium ferrocyanide, 0.75g of sodium hydroxide, 0.15g of AA/AMPS,0.025g of zinc chloride and 0.01g of hydrazine hydrate are weighed, finally the solution with the effective content of 25% is diluted by water, and the solution is stirred uniformly (the PH of the solution is=14.0).

Example 2

1.0G of sodium ferrocyanide, 0.5g of potassium carbonate, 0.20g of AA/AHPS and 0.05g of sodium erythorbate are weighed, finally diluted with water to form a solution with the effective content of 25 percent, and uniformly stirred (solution PH=11.0).

Example 3

1.0G of potassium ferrocyanide, 0.5g of sodium carbonate, 0.5g of potassium hydroxide, 0.1g of AA/APES,0.05g of copper nitrate and 0.025g of diethylhydroxylamine are weighed, finally diluted with water to obtain a solution with the effective content of 25 percent, and stirred uniformly (the PH of the solution is=13.0).

Example 4

1.0G of potassium ferrocyanide, 0.3g of potassium hydroxide, 0.25gAA/AMPS and 0.05g of sodium sulfite are weighed, finally diluted with water to obtain a solution with the effective content of 25 percent, and stirred uniformly (solution PH=10.0).

Example 5

1.0G of sodium ferrocyanide, 2.0g of potassium carbonate, 0.05g of AA/AHPS,0.1g of ferric chloride and 0.01g of carbohydrazide are weighed, finally the solution with the effective content of 25% is diluted with water, and the solution is stirred uniformly (PH=10.5).

Example 6

1.0G of potassium ferrocyanide, 1.0g of sodium carbonate, 0.5g of sodium hydroxide, 0.05g of AA/APES,0.01g of nickel nitrate and 0.05g of sodium ascorbate are weighed, finally diluted with water to obtain a solution with the effective content of 25%, and uniformly stirred (solution PH=12.0).

Comparative example 1

Referring to the salt inhibitor described in example 5 disclosed in document CN112079454a in the background art, namely, potassium ferrocyanide 0.5%, hydrolyzed polymaleic anhydride 5%, sodium gluconate 5%, sodium ethylenediamine tetraacetate 10% and the balance water, an aqueous salt inhibitor solution (solution ph=9.5) was used as a salt anti-caking agent, and the addition amount was 18.75 kg/ton of dry salt after conversion.

Comparative example 2

Salt anti-caking agents were prepared according to the components described in example 1 herein, except that comparative example 2 used 2.0gAA/AMPS instead of 0.15g AA/AMPS.

Comparative example 3

A salt anti-caking agent was prepared according to the formulation described in example 1 herein, except that comparative example 3 did not use the high temperature stabilizer sodium hydroxide (solution ph=9.5).

Comparative example 4

Salt anti-caking agents were prepared according to the components described in example 1 herein, except that comparative example 4 did not use the crystal nucleus dispersant AA/AMPS (solution PH > 14.0).

Comparative example 5

A salt anticaking agent was prepared as described in example 1 herein, except that 0.1g of the metal chelator tetra sodium ethylenediamine tetraacetate (solution ph=14.0) was also added to comparative example 5.

A. Stability test of high temperature stabilizer in salt anticaking agent on ferrocyanide salt

A salt anti-caking agent solution was prepared with reference to the components described in example 1, and the amount of the high temperature stabilizer sodium hydroxide added therein was varied to adjust the solution to have a different pH from example 1, examples corresponding to examples 1-1 (different pH from the component of example 1) and examples 1-2 (different pH from the component of example 1), respectively. Examples after 120 ℃ drying, 1.0 g of the dry product was taken out in a thermogravimetric analyzer sample pan, and the temperature was rapidly raised to a specified temperature of 520 ℃, 620 ℃ and 650 ℃ at a temperature rise rate of 50 ℃ per minute under nitrogen atmosphere, and the time was maintained for 2 minutes after reaching the set temperature, and the temperature was rapidly lowered, and then the content of remaining ferrocyanide salt (other organic decomposition temperature less than 300 ℃ C., irrespective of the above) was measured, and the cases of comparative examples 1 and 3 were simultaneously measured (see Table 1). The results show that the salt anticaking agent at high temperature has better stability under the strong alkaline condition. When the PH is more than 10 and the temperature is 520-620 ℃, ferrocyanide salt still can remain 45-28%, and after the PH exceeds 650 ℃, ferrocyanide is completely decomposed, which indicates that the salt anticaking agent can be completely decomposed and fail after the PH is 650 ℃.

TABLE 1 stability test of high temperature stabilizers in salt anticaking Agents against ferrocyanide salts

Examples of the examples	PH of solution	Temperature/°c	Ferrocyanide residual/wt.%
				Example 1-1	8.0	520	Not detected
Comparative example 1	9.5	520/620	2/Undetected
				Comparative example 3	9.5	520/620	3/Go undetected
Examples 1 to 2	10.0	520/620/650	45/28/Undetected
				Example 1	14.0	520/620	48/29

B. Test of influence of the amount of Crystal nucleus dispersant on salt crystallization Property

To 250 ml of a 100 ℃ constant temperature saturated sodium chloride solution, quantitative salt anticaking agents as exemplified in table 2 were added, and after stirring uniformly, the temperature was kept constant for 10 minutes, and then the saturated solution was poured into a dish from a 100 ℃ constant temperature state to be cooled, and the crystal shape was checked (see table 2). Wherein examples 1-3 were the preparation of salt anti-caking agent solutions for the components described in reference to example 1, and the amount of the crystal nucleus dispersant added thereto was varied so that the crystal nucleus dispersant amount reached 2.5g/kg of dry salt.

TABLE 2 Effect of Crystal nucleus dispersants on crystallization Properties

As can be seen from the crystallization phenomena in examples 1 and 2 (see example 1, but different amounts of AA/AMPS used) and examples 1 to 3 (see example 1, but different amounts of AA/AMPS used), the use of a crystal nucleus dispersant affects salt crystallization, and excessive crystal nucleus dispersant causes adhesion of crystals, and the viscosity of the polymer tends to cause difficulty in salt crystallization, cross-linking of crystals, increased salt crystallization, and adverse effect on crystallization refinement.

C. Influence of different Crystal nucleus dispersants on salt anti-caking agent

The effect on the stability of the salt anti-caking agent solution was investigated using different crystal nucleus dispersants.

Salt anti-caking agent solutions were prepared with reference to the components described in example 1, and the kinds of crystal nucleus dispersants added therein were changed, corresponding examples being examples 1 to 4 (with reference to example 1 but using different crystal nucleus dispersants) and examples 1 to 5 (with reference to example 1 but using different crystal nucleus dispersants), respectively. The stability of the solutions of examples 1, 1-4, 1-5 was examined (see Table 3 for phenomena). The solution does not delaminate, indicating good dispersibility, and the solution delaminates/precipitates, indicating poor dispersibility.

TABLE 3 Effect of different Crystal nucleus dispersants on stability of salt anti-caking agent solutions

Examples of the examples	Type of crystal nucleus dispersant	The solution is prepared and left to stand for 24 hours
			Examples 1 to 4	PAA	Layering, and precipitating with white layer at bottom
Examples 1 to 5	AA/HPA	Layering, and small amount of white precipitate at bottom of bottle
			Example 1	AA/AMPS	Non-layering, milky turbid liquid

D. Test of influence of Metal chelator on salt crystallization Properties

To 250 ml of 100 ℃ saturated sodium chloride solution, a quantitative amount of salt anti-caking agent was added, and after stirring uniformly, the temperature was kept constant for 10 minutes, and then the saturated solution was poured into a petri dish from a state of constant temperature at 100 ℃ to be cooled, and the crystal shape was examined (see table 4).

TABLE 4 influence of Metal chelators on salt crystallization Properties

As can be seen from the crystallization phenomenon in example 1 and comparative example 5, the metal chelating agent was not used to crystallize more loosely than the salt using the metal chelating agent under the same conditions of the amount of the metal chelating agent used, and the time for starting the crystallization was slower than the time without using the metal chelating agent under the same experimental conditions.

E. laboratory testing of salt anticaking agents

The laboratory test method is as follows:

A certain amount of salt anti-caking agent is added into 250 milliliters of 100 ℃ constant-temperature saturated sodium chloride solution, the temperature is kept for 10 minutes after uniform stirring, and then the saturated solution is poured into a surface dish from a 100 ℃ constant-temperature state to be cooled, so that the crystal shape is checked. The test results are shown in table 5.

Table 5 salt anticaking agent laboratory test results

As can be seen from the crystallization phenomenon in examples 1 to 6, as the amount of the salt anti-caking agent increases, the salt crystals become loose and fragile from a small amount of dendrites to a large amount of dendrites. Examples 2 and 4, since no nucleating agent was added, the time to begin precipitation of salt crystals in the experiment was slower than in the examples with the addition of nucleating agent.

F. Industrial test of salt anticaking Agents

Industrial tests were carried out on examples 1 and 1, 3 and 4.

The industrial site trial cases are as follows:

Scene 1. Waste incineration enterprises in Shandong danger produce about 40 tons of waste water with 15-20 wt.% of salt content (the salt is mainly sodium chloride, and the sodium chloride content is more than 90%) each day. The flue gas inlet temperature of the quenching tower is 520-620 ℃, a quantitative salt anti-caking agent is added into a salt water pipeline before entering the quenching water tank, a pipeline mixer is arranged on the pipeline, after the agent and the salt water are uniformly mixed, the mixture enters the quenching water tank for buffering, and then the mixture is pumped by a quenching water pump at the outlet of the quenching water tank, and is sprayed into the quenching tower through the salt water pipeline and a spray gun at the tail end of the pipeline.

Scene 2-in the scene of a dangerous waste incineration enterprise in Hubei, about 20 tons of wastewater with the salt content of 20-23 wt% are produced every day (the salt is mainly sodium chloride and sodium sulfate, the sodium chloride is more than 85%, and the sodium sulfate is more than 10%). And (3) carrying out supercritical concentration and crystallization to obtain salt, wherein the operation temperature is 60-90 ℃, adding a salt anti-caking agent into the salt water, and checking the salt caking condition of a salt water conveying pipeline and concentration equipment.

Scene 3, a waste salt generating enterprise in Jiangsu produces waste water with 15-17% of salt content every day, spray hot air is used for drying waste brine (the salt content is mainly sodium chloride and potassium chloride, the sodium chloride is more than 88%, and the potassium chloride is more than 10%), the drying temperature is 200-280 ℃, the waste salt is recovered, and a quantitative salt anti-caking agent is added into the salt-containing waste water before drying to prevent the produced waste salt from hardening and influencing production.

The industrial application effects of the salt anticaking agents in the above examples and comparative examples under the above three application scenarios are shown in table 6. Wherein the blank is the case without any agent. The salt accumulation analysis in the application effect is used for showing the high temperature resistance condition of the salt anti-caking agent under different scenes, if the analysis result contains ferrocyanide, the salt anti-caking agent has excellent high temperature resistance effect, and if the salt anti-caking agent does not contain ferrocyanide, the salt anti-caking agent does not resist high temperature. The longer the device is in stable operation, the better the salt anti-caking agent effect is, and the stronger the performance is.

Table 6 salt anticaking agent industrial application scenario application Effect

When the comparative example 1 is applied in the environment of 520-620 ℃ of scene 1, the salt is found to be free of potassium ferrocyanide after salt accumulation analysis, which indicates that the salt anticaking agent is not resistant to high temperature and the potassium ferrocyanide is decomposed at high temperature. Therefore, the salt anti-caking agent in comparative example 1 has a certain salt anti-caking effect at the same concentration, but has poor effect, the inner wall has thicker salt caking thickness and a large number of ash salt blocks with fist size, and the stable running time of the device is far lower than 240 days of example 1 even 60 days.

Comparative example 3 (comparative example 1 only lacks the high temperature stabilizer, solution ph=9.5) was applied in the environment of 520-620 ℃ in scenario 1, and after salt precipitation, the salt was found to be free of potassium ferrocyanide, indicating that the salt anticaking agent is not resistant to high temperatures, and potassium ferrocyanide has been decomposed at high temperatures. Therefore, the high temperature stabilizer is not used in the case where the other components are the same, so that the salt anti-caking agent has a better anti-caking effect than comparative example 1 (a smaller caking thickness in the case of longer time than comparative example 1). However, the overall effect is still poor, and the salt precipitation is particularly shown by the thickness of about 40cm on the inner wall when the salt is used for about 70 days, and a large number of ash salt blocks with the size of a fist are formed. From the salt accumulation analysis of example 1 and comparative example 3, it was found that the addition of the high-temperature stabilizer and the maintenance of the solution pH >10.0 or more effectively stabilized the pyrolysis of ferrocyanide.

When comparative example 4 (comparative example 1 lacks only the crystal nucleus dispersant) was applied to the environment of 520 to 620 ℃ in scene 1, it was found after salt precipitation that potassium ferrocyanide was contained in the salt, which indicates that the salt anticaking agent has high temperature resistance, and potassium ferrocyanide, which is one of the main components, was not decomposed at high temperature or was not decomposed at high temperature in its entirety, and the salt anticaking effect was fully exhibited. Meanwhile, the crystal nucleus dispersing agent is lack, so that crystal nuclei and fine precipitates in the system are difficult to disperse, and the inner wall of the crystal nucleus dispersing agent is not salted, but potato salt blocks are formed.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the scope of the technical concept of the present invention, and all the simple modifications belong to the protection scope of the present invention.

In addition, the specific features described in the above embodiments may be combined in any suitable manner, and in order to avoid unnecessary repetition, various possible combinations are not described further.

Moreover, any combination of the various embodiments of the invention can be made without departing from the spirit of the invention, which should also be considered as disclosed herein.

Claims

1. A composition for salt anticaking agent is characterized in that the composition for salt anticaking agent does not contain metal chelating agent, and the composition for salt anticaking agent comprises ferrocyanide salt, high-temperature stabilizer, crystal nucleus dispersant and nucleating agent which are selectively contained, wherein the weight ratio of the ferrocyanide salt to the high-temperature stabilizer to the crystal nucleus dispersant is 1 (0.3-2.0): 0.05-0.25): 0-0.10;

wherein the high-temperature stabilizer is at least one of potassium hydroxide, sodium carbonate, potassium carbonate and lithium carbonate;

the crystal nucleus dispersing agent is a copolymer formed by sulfonic acid group-containing olefin and carbonyl group-containing olefin with the carbon number of 3-4, wherein the mol percent of structural units formed by the sulfonic acid group-containing olefin is 10-25 percent based on the total amount of the crystal nucleus dispersing agent, and the weight average molecular weight of the crystal nucleus dispersing agent is 1500-50000;

Wherein the nucleating agent is a soluble metal ion capable of forming a precipitate with the ferrocyanide salt or a soluble metal ion capable of forming a precipitate in an aqueous alkaline solution.

2. The composition for a salt anticaking agent according to claim 1, wherein the ferrocyanide salt is at least one of potassium ferrocyanide, sodium ferrocyanide and ammonium ferrocyanide.

3. The composition for a salt anti-caking agent according to claim 1, wherein the carbonyl-group-containing olefin having 3 to 4 carbon atoms is acrylic acid and/or maleic acid/anhydride, and the sulfonic acid group-containing olefin is at least one of 2-methyl-2-acrylamidopropane sulfonic acid, ethylene sulfonic acid, p-styrene sulfonic acid, 3-allyloxy-2-hydroxy propane sulfonic acid and allyl polyethylene glycol sulfonic acid.

4. The composition for a salt anti-caking agent according to claim 1, wherein the nucleating agent is at least one of soluble metal ions Zn²⁺、Fe³⁺、Cd²⁺、Ni²⁺、Pb²⁺、Co²⁺、Cu²⁺、Ag⁺、Mn²⁺、Al³⁺.

5. The composition for a salt anti-caking agent according to claim 1, wherein the composition for a salt anti-caking agent further comprises an antioxidant and/or a reducing agent, and the weight ratio of the antioxidant and/or the reducing agent to ferrocyanide is (0.01-0.05): 1.

6. The composition for a salt anti-caking agent according to claim 5, wherein the antioxidant and/or the reducing agent is at least one of hydrazine hydrate, carbohydrazide, N-diethylhydroxylamine, hydroxylamine hydrochloride, hydroxylamine sulfate, dimethyl ketoxime, sodium erythorbate, potassium erythorbate, sodium ascorbate, potassium ascorbate, sodium sulfite, potassium sulfite, sodium dithionate and potassium dithionate.

7. The composition for a salt anti-caking agent according to claim 1, wherein the metal chelating agent is a carboxyl group-containing or phosphonic acid group-containing organic compound capable of forming a soluble chelate with the nucleating agent.

8. The composition for a salt anti-caking agent according to claim 7, wherein the metal chelating agent is at least one of nitrilotriacetic acid, ethylenediamine tetraacetic acid, hydroxyethyl ethylenediamine triacetic acid, diethylenetriamine pentaacetic acid, gluconic acid, citric acid, tartaric acid, succinic acid, aminotrimethylene phosphonic acid, hydroxyethylenediphosphonic acid, ethylenediamine tetraethylenephosphonic acid, diethylenetriamine pentamethylene phosphonic acid, triethylenetetramine hexamethylenephosphonic acid, bis (1, 6-methylene) -triamine pentamethylene phosphonic acid, polyaminoether tetramethylene phosphonic acid, polyacrylic acid, polymaleic acid, polyepoxysuccinic acid, polyaspartic acid, and alkaline earth metal salts thereof.

9. A salt anticaking agent is an aqueous solution formed by a composition for salt anticaking agent and water, and is characterized in that the pH of the aqueous solution is more than 10, wherein the composition for salt anticaking agent is the composition for salt anticaking agent according to any one of claims 1 to 8.

10. The salt anticaking agent according to claim 9, wherein the content of the composition for salt anticaking agent is 10 to 40% by weight based on the total weight of the salt anticaking agent.

11. Use of the salt anti-caking agent according to claim 10 in a process for drying and/or crystallizing salt-containing wastewater to recover waste salt.

12. The method according to claim 11, wherein the salt-containing wastewater is one of sodium chloride-based salt-containing wastewater, sodium chloride-based salt-containing wastewater and sodium sulfate-based salt-containing wastewater, and sodium chloride-based salt-containing wastewater, and potassium chloride-based salt-containing wastewater, and the mass percentage of sodium chloride is greater than 85%.

13. The method according to claim 11, wherein the salt-containing wastewater is subjected to crystallization or drying at 25-620 ℃ after the salt-containing anti-caking agent and the salt-containing wastewater are uniformly mixed, and the salt-containing wastewater containing the salt-containing anti-caking agent is pumped into a crystallization device, a spray drying device or a high-temperature drying device, so that the waste salt solids are recovered.

14. The application of the method of claim 11, wherein the salt anti-caking agent is added into the salt-containing wastewater in an amount of 1.0-10.0 kg of salt anti-caking agent per ton of dry salt in the salt-containing wastewater based on the active ingredient.