CN112079559A - Method for controlling lithium ion concentration in molten salt and molten salt treating agent - Google Patents
Method for controlling lithium ion concentration in molten salt and molten salt treating agent Download PDFInfo
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- CN112079559A CN112079559A CN202011022772.7A CN202011022772A CN112079559A CN 112079559 A CN112079559 A CN 112079559A CN 202011022772 A CN202011022772 A CN 202011022772A CN 112079559 A CN112079559 A CN 112079559A
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B27/00—Tempering or quenching glass products
- C03B27/02—Tempering or quenching glass products using liquid
- C03B27/03—Tempering or quenching glass products using liquid the liquid being a molten metal or a molten salt
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- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C21/00—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface
- C03C21/001—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions
- C03C21/002—Treatment of glass, not in the form of fibres or filaments, by diffusing ions or metals in the surface in liquid phase, e.g. molten salts, solutions to perform ion-exchange between alkali ions
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
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Abstract
The invention relates to a method for controlling the concentration of lithium ions in molten salt and a molten salt treating agent, wherein the method for controlling the concentration of the lithium ions in the molten salt comprises the following steps: providing a molten salt treatment agent; contacting the molten salt with a molten salt treatment agent for a predetermined time; wherein the molten salt treating agent comprises meta-aluminate. The method can economically, simply and conveniently control Li in the molten salt on the basis of avoiding introducing harmful impurities into the molten salt+Concentration to avoid the conditions of stopping production and replacing molten salt.
Description
Technical Field
The invention relates to the technical field of toughened glass preparation, in particular to a method for controlling the concentration of lithium ions in molten salt and a molten salt treating agent.
Background
The molten salt has wide application in the fields of metallurgical industry, energy technology, solid electrochemical technology, environmental technology and the like. Currently, ion exchange is the mainstream method for chemically strengthening glass, and the method must be realized by high-temperature molten salt.
The ion exchange method can increase the magnitude of the compressive stress and the depth of the stress layer of the glass substrate, thereby obviously improving the strength of the glass substrate, preventing the surface of the glass from being damaged due to impact and scratch and prolonging the service life of the product. In the existing ion exchange process, the ion exchange catalyst is prepared by adding a small alkali metal cation (Li)+)Is immersed in a solution containing one or more larger alkali metal cations (Na)+、K+) In the molten salt of (1). At this time, smaller Li+Diffusion from the glass surface into the molten salt, with larger Na from the molten salt+、K+Replacing Li in glass surfaces+. After the glass is strengthened and cooled, Na+、K+The glass surface generates a 'jamming' effect to form a compressive stress layer on the surface, so that the effect of enhancing the glass strength is achieved.
However, as ion exchange proceeds, Li in the molten salt+Is increased in concentration of Na+、K+The concentration of (b) is reduced, resulting in a decrease in ion exchange capacity, a significant decrease in strength of the glass substrate, and an end of the life of the molten salt. At the moment, production needs to be stopped, furnace water needs to be cleaned, a furnace platform needs to be cleaned, and new molten salt needs to be added, so that the next production can be continued, the process efficiency is low, and cost control is obviously not facilitated.
It has been reported that the industry uses phosphates added to molten salts to precipitate lithium ions, but the phosphates dissociate and release a large amount of phosphate ions, which adversely affect the subsequent cation exchange on the glass surface.
At present, the industry determines the lithium ion concentration reserved in the molten salt for strengthening the glass substrate according to the subsequent application scene of the glass substrate, the lithium ion concentration in the molten salt is high, the lithium ion content in the obtained strengthened glass is relatively high, and the lithium ion content has important influence on the density, the thermal expansion rate, the surface tension and the chemical stability of the glass. Therefore, the lithium ion concentration retained in the molten salt is not as low as possible, but should be in a controllable state, and the industry has not found a simple method for controllably adjusting the lithium ion concentration in the molten salt.
Therefore, there is an urgent need in the industry to find a method for economically and simply controlling Li in molten salt while avoiding the introduction of harmful impurities into the molten salt+Concentration method to avoid the condition of stopping production and replacing molten salt.
Disclosure of Invention
Based on the above, there is a need for a method for controlling the concentration of lithium ions in a molten salt and a molten salt treatment agent, which can economically and simply control Li in the molten salt while avoiding the introduction of harmful impurities into the molten salt+And (4) concentration.
A method of controlling the concentration of lithium ions in a molten salt comprising the steps of:
providing a molten salt treatment agent;
contacting a molten salt with the molten salt treatment agent for a predetermined time;
wherein the molten salt treatment agent comprises meta-aluminate.
In one embodiment, 0.1g to 10g of the molten salt treatment agent is added per 100g of the molten salt; and/or
In the molten salt treating agent, the mass percentage of the metaaluminate is 50-80%.
In one embodiment, the meta-aluminate is selected from: one or more of sodium metaaluminate, potassium metaaluminate, magnesium metaaluminate or calcium metaaluminate.
In one embodiment, the molten salt treatment agent further comprises silicate, a forming material and a surfactant.
In one embodiment, the step of providing the molten salt treatment agent comprises the steps of:
mixing raw materials for preparing the molten salt treatment agent;
and (3) sequentially adopting an extrusion forming process and a calcining process to treat to prepare the porous solid molten salt treating agent.
In one embodiment, the molten salt treatment agent is spherical, flaky or strip-shaped; and/or
The average grain diameter of the molten salt treating agent is 0.5 cm-2 cm.
A molten salt treating agent comprises metaaluminate, silicate, a forming material and a surfactant.
In one embodiment, the molten salt treatment agent is a porous solid prepared by an extrusion forming process and a calcining process.
In one embodiment, the molten salt treatment agent is spherical, flaky or strip-shaped; and/or
The average grain diameter of the molten salt treating agent is 0.5 cm-2 cm.
A salt bath for strengthening glass comprises an inorganic salt for preparing molten salt and a molten salt treating agent, wherein the molten salt treating agent contains meta-aluminate.
Has the advantages that:
after a large number of screening experiments, technicians of the invention find that: normally, the molten salt is a clear and transparent liquid at high temperature, the metaaluminate is not fused with the molten salt due to high temperature after being added into the molten salt, but continues to exist in the molten salt as powder or solid particles, and presumably, ion exchange occurs on the surface of the metaaluminate, so that the lithium ion concentration in the molten salt is reduced, and harmful impurities are also prevented from being introduced. When the metaaluminate is made into solid, especially porous solid, the effect of controllable sedimentation of the lithium ion concentration in the molten salt is realized. Therefore, the invention has the advantages that:
(1) lithium ions in the molten salt can be subjected to ion exchange with metal cations in meta-aluminate in the molten salt treatment agent to be settled, so that the concentration of the lithium ions in the molten salt is remarkably reduced;
(2) the meta-aluminate in the molten salt treating agent has stable structure, can bear high-temperature molten salt without degradation or decomposition, can be directly separated from the molten salt after the lithium ions are settled, and does not introduce harmful impurities;
(3) when the fused salt is treated by using the fused salt treating agent, the speed and the degree of reduction of the lithium ion concentration are controllable;
(4) the use of the molten salt treating agent can reduce the frequency of molten salt replacement in the tempering furnace, remarkably improve the service life of the molten salt, reduce the production cost and the waste discharge, and reduce the environmental protection pressure.
Detailed Description
In order that the invention may be more fully understood, a more particular description of the invention will now be rendered by reference to specific embodiments thereof that are illustrated in the appended drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
An embodiment of the present invention provides a method for controlling a lithium ion concentration in a molten salt, including the steps of:
s101: providing a molten salt treatment agent; wherein the molten salt treating agent comprises meta-aluminate.
After a large number of screening experiments, technicians of the invention find that: normally, the molten salt is a clear and transparent liquid at high temperature, the metaaluminate is not fused with the molten salt due to high temperature after being added into the molten salt, but continues to exist in the molten salt as powder or solid particles, and presumably, ion exchange occurs on the surface of the metaaluminate, so that the lithium ion concentration in the molten salt is reduced, and harmful impurities are also prevented from being introduced. When the metaaluminate is made into solid, especially porous solid, the effect of controllable sedimentation of lithium ion concentration in the molten salt is realized, so that the metaaluminate is particularly suitable for being applied to molten salt treatment.
It is understood that the "molten salt" in the present invention refers to a liquid ion melt composed of cations and anions formed by melting inorganic salts at a high temperature; further, the molten salt is potassium nitrate molten salt or sodium nitrate molten salt; further, it is preferable that the concentration of lithium ions in the molten salt is more than 10ppm and a certain amount of sodium ions and/or potassium ions are contained.
It is understood that the amount of the molten salt treatment agent added in the present invention may be adjusted according to the lithium ion concentration in the molten salt, the treatment requirement, and the like, and is not to be construed as limiting the present invention. In one embodiment, 0.1g to 10g of the molten salt treatment agent is added per 100g of the molten salt; furthermore, 0.2g to 4g of the molten salt treating agent is added to every 100g of the molten salt; the above addition amounts satisfy most of the requirements of practical production.
Further, in the molten salt treating agent, the mass percentage of the meta-aluminate is more than or equal to 20 percent; furthermore, in the molten salt treating agent, the mass percentage of the meta-aluminate is 20-95%; furthermore, in the molten salt treating agent, the mass percentage of the meta-aluminate is 30-90%; furthermore, in the molten salt treating agent, the mass percentage of the meta-aluminate is 40-85%; furthermore, in the molten salt treating agent, the mass percentage of the meta-aluminate is 50-80%;
further, the meta-aluminate is selected from: one or more of sodium metaaluminate, potassium metaaluminate, magnesium metaaluminate or calcium metaaluminate; in one embodiment, the metaaluminate is sodium metaaluminate or potassium metaaluminate; in one embodiment, the meta-aluminate is a mixture of sodium meta-aluminate and potassium meta-aluminate in a mass ratio of 1: 0.5-1: 2; furthermore, the metaaluminate is a mixture of sodium metaaluminate and potassium metaaluminate in a mass ratio of 1: 1;
further, the molten salt treating agent also comprises silicate, a forming material and a surfactant, so that the molten salt treating agent with a required shape can be prepared, the silicate has a certain lithium ion adsorption effect, and the adsorption effect of the molten salt treating agent can be improved by compounding the silicate with meta-aluminate.
It is understood that the specific type of the shaping material is not particularly limited, and may be the existing shaping materials, including but not limited to: clay, kaolin, talc, and the like; preferably, the shaping material is clay;
furthermore, the mass ratio of the meta-aluminate to the silicate is 1: 100-100: 1; furthermore, the mass ratio of the meta-aluminate to the silicate is 1: 10-10: 1; furthermore, the mass ratio of the meta-aluminate to the shaping material is 1: 10-10: 1; furthermore, in the molten salt treating agent, the mass percentage of the surfactant is 0.1-10%; still further, the surfactant is polyvinylpyrrolidone (PVP);
it is understood that the "molten salt treatment agent" in the present invention may be in the form of solid powder or solid particles having a certain particle size, and since the metaaluminate is in a solid state when the molten salt is in a molten state, it can be removed by filtration or sieving, and is preferably in the form of solid particles having a certain particle size.
Further, it is preferable that the molten salt treatment agent has a porous structure to improve the treatment efficiency; furthermore, the molten salt treating agent is a porous solid prepared by an extrusion forming process, so that the particle size of the molten salt treating agent can be controlled conveniently, and the molten salt treating agent and the molten salt can be separated conveniently; furthermore, the molten salt treating agent is a porous solid prepared by extrusion forming and calcining processes, so that the porosity of the molten salt treating agent is improved, and the treatment efficiency is further improved;
it is to be understood that the apparatus and the specific operation method used in the extrusion molding process and the calcination process are not particularly limited, and should not be construed as limiting the present invention. For example, the raw materials can be uniformly mixed, and then extruded by the existing extrusion apparatus to be pressed into a target shape, preferably a spherical particle, a tablet or a strip solid, so as to improve the surface area contacted with the molten salt and improve the treatment effect.
Further, step S101 includes the steps of:
s1011: mixing raw materials for preparing the molten salt treating agent;
it is understood that, in step S1011, a proper amount of solvent (such as water) can be added to facilitate the subsequent steps, and since the solvent volatilizes in the subsequent steps, the treatment effect of the molten salt treatment agent is not affected, and the type and the addition amount of the solvent only need not be contrary to the purpose of the invention, and should not be construed as limiting the invention.
S1012: and (3) sequentially adopting an extrusion forming process and a calcining process to treat to prepare the porous solid molten salt treating agent.
Specifically, the product with the target shape is pressed by adopting an extrusion forming process, then the product is placed in a calcining furnace for calcining, and after the calcining is finished, the product is taken out and cooled. Further, it is preferable that the calcination temperature is 500 ℃ or more; furthermore, the calcining temperature is 500-700 ℃; further, cooling is preferably performed under an inert gas atmosphere;
in addition, the molten salt treatment agent may further include an appropriate amount of an existing additive to facilitate the production of the product, as long as it does not contradict the gist of the present invention, and it should not be construed as limiting the present invention. Further, the average grain diameter of the molten salt treating agent is 0.5-2 cm;
in one embodiment, the molten salt treatment agent is in the form of spherical particles with a particle size of 0.8 cm to 1.2 cm;
in one embodiment, the molten salt treatment agent is in the form of a circular tablet with a diameter of 0.8 cm to 1.2 cm;
in one embodiment, the molten salt treatment agent is a strip solid with a length of 0.8-1.2 cm and a cross-sectional average diameter of 0.2-0.6 cm;
s102: contacting the molten salt with a molten salt treatment agent for a predetermined time;
the fused salt can be waste fused salt or new fused salt, the waste fused salt is treated by the fused salt treating agent, and the waste fused salt can be recycled by reducing the concentration of lithium ions in the fused salt; the proper amount of the molten salt treating agent is added into the new molten salt, so that the control of the lithium ion concentration in the glass strengthening process can be realized, the service time of the molten salt is further prolonged, and the condition of stopping production and replacing the molten salt is avoided.
In step S102, the preset time can be adjusted according to the concrete condition of the molten salt and the lithium ion concentration requirement; further, in step S102, the predetermined time is 30 minutes to 180 minutes; this treatment time is basically suitable for most industrial processes.
In step S102, "contacting the molten salt with the molten salt treatment agent", the molten salt treatment agent may be added before the molten salt is to be formed, and the whole system is heated to melt the corresponding inorganic salt to form the molten salt; the molten salt treatment agent can also be added after the molten salt is formed, and the molten salt treatment agent is understood to be in the protection scope of the invention; preferably, the molten salt treatment agent is added after the molten salt is formed, so as to improve the treatment effect; further, it is preferable that the molten salt treatment agent is added after the molten salt is formed, and the molten salt treatment agent is preheated before the molten salt treatment agent is added; furthermore, the temperature of the molten salt is more than 500 ℃, and the preheating temperature of the molten salt treating agent is 200-400 ℃.
The embodiment of the invention also provides application of the meta-aluminate in molten salt recycling or glass strengthening.
The embodiment of the invention also provides a molten salt treating agent. Specifically, the molten salt treatment agent is as described above, and will not be described in detail here.
An embodiment of the present invention also provides a salt bath for strengthening glass, including an inorganic salt for forming a molten salt and a molten salt treatment agent. Specifically, the inorganic salt and the molten salt treatment agent are as described above, and will not be described in detail here.
An embodiment of the present invention also provides a method of strengthening glass, comprising the steps of:
s201: providing a salt bath comprising a molten salt and a molten salt treatment agent;
molten salts and molten salt treatment agents are as described above; are not described herein again;
s202: placing the glass in a salt bath for treatment;
specifically, the conventional glass strengthening method may be employed, and only the salt bath thereof needs to be replaced with the salt bath in step S201, which will not be described herein again.
The method for reducing the lithium ion concentration in the molten salt according to the present invention will be described in further detail with reference to specific examples. All operations in the following embodiments may be carried out under normal pressure.
Example 1
Adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding potassium metaaluminate into the molten salt when the solid in the furnace reaches a molten state to form the molten salt, wherein the adding amount is 0.2 percent of the mass of the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃ until the concentration of the lithium ions in the molten salt is 1ppm (the detection limit of an instrument is 1ppm), obtaining the molten salt with low lithium ion concentration, and taking about 67 minutes without generating impurities.
Example 2
Adding 25 kg of potassium nitrate solid containing 8000ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding sodium metaaluminate into the molten salt when the solid in the furnace reaches a molten state to form the molten salt, wherein the adding amount is 10% of the mass of the molten salt, then stopping heating, keeping the temperature of the molten salt at 500 ℃ until the concentration of the lithium ions in the molten salt is 1ppm (the detection limit of an instrument is 1ppm), obtaining the molten salt with low lithium ion concentration, and taking about 52 minutes without generating impurities.
Example 3
Adding 25 kg of sodium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding sodium metaaluminate into the molten liquid when the molten salt in the tempering furnace reaches a molten state to form molten liquid, wherein the adding amount is 0.1 percent of the mass of the molten salt, stopping heating, and keeping the temperature of the molten salt at 500 ℃ until the concentration of the lithium ions in the molten salt is 1ppm (the detection limit of an instrument is 1ppm), so that the molten salt with low lithium ion concentration is obtained, the total time is about 116 minutes, and no impurities are generated.
Example 4
Adding 25 kg of sodium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding calcium metaaluminate into the molten liquid when the molten salt in the furnace reaches a molten state to form molten liquid, wherein the adding amount is 4% of the mass of the molten salt, then stopping heating, keeping the temperature of the molten salt at 500 ℃ until the concentration of the lithium ions in the molten salt is 1ppm (the detection limit of an instrument is 1ppm), obtaining the molten salt with low lithium ion concentration, and taking about 36 minutes without generating impurities.
Example 5
250 g of potassium metaaluminate, 22.5 g of silicate, 40 g of clay, 5 g of polyvinylpyrrolidone (PVP) and a proper amount of water are uniformly mixed, the mixture is extruded into a tablet-shaped solid with the diameter of about 1 cm, the tablet-shaped solid is dried and dehydrated after being sieved, the tablet-shaped solid is placed into a calcining furnace, the calcining furnace is vacuumized and calcined at 550 ℃ for 30 minutes, and then the tablet-shaped solid is cooled and sieved under the protection of nitrogen to obtain the porous tablet-shaped solid.
Slowly heating the potassium metaaluminate solid to 300 ℃ for preheating, adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding the preheated potassium metaaluminate solid into the molten salt when the solid in the furnace reaches a molten state to form the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃, monitoring the change of the concentration of the lithium ions in the molten salt, and consuming about 35 minutes until the concentration of the lithium ions in the molten salt is 100ppm (the detection limit of an instrument is 1ppm), filtering the potassium metaaluminate solid to obtain the molten salt with low lithium ion concentration, wherein the total time is about 76 minutes, and no impurity is generated.
Example 6
250 g of potassium metaaluminate, 22.5 g of silicate, 40 g of clay, 5 g of polyvinylpyrrolidone (PVP) and a proper amount of water are uniformly mixed, the mixture is extruded into a strip-shaped solid with the length of about 1 cm and the average diameter of the cross section of about 0.5cm, the strip-shaped solid is dried and dehydrated after being screened, the strip-shaped solid is placed into a calcining furnace, is calcined for 30 minutes at 550 ℃ after being vacuumized, and then is cooled and screened under the protection of nitrogen to obtain the porous strip-shaped solid.
Slowly heating the potassium metaaluminate solid to 300 ℃ for preheating, adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding the preheated potassium metaaluminate solid into the molten salt when the solid in the furnace reaches a molten state to form the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃, monitoring the change of the concentration of the lithium ions in the molten salt, and consuming about 43 minutes until the concentration of the lithium ions in the molten salt is 100ppm (the detection limit of an instrument is 1ppm), filtering the potassium metaaluminate solid to obtain the molten salt with low lithium ion concentration, wherein the total time is about 89 minutes, and no impurity is generated.
Example 7
250 g of potassium metaaluminate, 22.5 g of silicate, 40 g of clay, 5 g of polyvinylpyrrolidone (PVP) and a proper amount of water are mixed uniformly, the mixture is extruded into spherical particles with the diameter of about 1 cm, the spherical particles are sieved, dried and dewatered, put into a calcining furnace, vacuumized, calcined at 550 ℃ for 30 minutes, cooled by nitrogen protection and sieved to obtain porous spherical solids.
Slowly heating the potassium metaaluminate solid to 300 ℃ for preheating, adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding the preheated potassium metaaluminate solid into the molten salt when the molten salt in the tempering furnace reaches a molten state to form the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃, monitoring the change of the concentration of the lithium ions in the molten salt, and consuming about 23 minutes until the concentration of the lithium ions in the molten salt is 100ppm (the detection limit of an instrument is 1ppm), filtering the potassium metaaluminate solid to obtain the molten salt with low lithium ion concentration, wherein the total time is about 52 minutes, and no impurity is generated.
Example 8
250 g of potassium metaaluminate, 300 g of silicate, 700 g of clay, 50 g of polyvinylpyrrolidone (PVP) and a proper amount of water are uniformly mixed, the mixture is extruded into spherical particles with the diameter of about 1 cm, the spherical particles are sieved, dried and dewatered, put into a calcining furnace, vacuumized, calcined at 550 ℃ for 30 minutes, cooled by nitrogen protection and sieved to obtain porous spherical solids.
Slowly heating the potassium metaaluminate solid to 300 ℃ for preheating, adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding the preheated potassium metaaluminate solid into the molten salt when the molten salt in the tempering furnace reaches a molten state to form the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃, monitoring the change of the lithium ion concentration in the molten salt, and consuming about 27 minutes until the lithium ion concentration in the molten salt is 100ppm (the detection limit of an instrument is 1ppm) to obtain the molten salt with low lithium ion concentration, wherein the total time is about 60 minutes and no impurity is generated.
Example 9
Uniformly mixing 125 g of potassium metaaluminate, 45 g of silicate, 80 g of clay, 15 g of polyvinylpyrrolidone (PVP) and a proper amount of water, extruding the mixture into spherical particles with the diameter of about 1 cm, sieving, drying to remove water, putting the spherical particles into a calcining furnace, vacuumizing, calcining at 550 ℃ for 30 minutes, cooling by using nitrogen protection, and sieving to obtain the porous spherical solid.
Slowly heating the potassium metaaluminate solid to 300 ℃ for preheating, adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding the preheated potassium metaaluminate solid into the molten salt when the molten salt in the tempering furnace reaches a molten state to form the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃, monitoring the change of the concentration of the lithium ions in the molten salt, and consuming about 53 minutes until the concentration of the lithium ions in the molten salt is 100ppm (the detection limit of an instrument is 1ppm), filtering the potassium metaaluminate solid to obtain the molten salt with low lithium ion concentration, wherein the total consumption time is about 167 minutes, and no impurity is generated.
Example 10
Adding a mixed solid of 12.5 kg of sodium nitrate and 12.5 kg of potassium nitrate containing 8000ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding 500 g of sodium metaaluminate and 500 g of potassium metaaluminate into molten liquid when the solid in the tempering furnace reaches a molten state to form molten salt, wherein the total amount of the added molten salt is 4% of the mass of the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃ until the concentration of the lithium ions in the molten salt is 1ppm (the detection limit of an instrument is 1ppm), obtaining the molten salt with low lithium ion concentration, and taking 111 minutes without generating impurities.
Example 11
Adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding magnesium metaaluminate into the molten salt when the solid in the furnace reaches a molten state to form the molten salt, wherein the adding amount is 3% of the mass of the molten salt, then stopping heating, and keeping the temperature of the molten salt at 500 ℃ until the concentration of the lithium ions in the molten salt is 1ppm (the detection limit of an instrument is 1ppm), so that the molten salt with low lithium ion concentration is obtained, the total time is about 72 minutes, and no impurities are generated.
Comparative example 1
Adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding aluminum hydroxide into the molten salt when the solid in the tempering furnace reaches a molten state to form the molten salt, wherein the adding amount is 0.2 percent of the mass of the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃, and detecting the content of the lithium ions in the molten salt after 67 minutes, wherein the content of the lithium ions is unchanged, and the added aluminum hydroxide is converted into aluminum oxide.
Comparative example 2
Adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding aluminum oxide into the molten salt when the solid in the furnace reaches a molten state to form the molten salt, wherein the adding amount is 0.2 percent of the mass of the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃, and detecting the content of the lithium ions in the molten salt after 67 minutes, wherein the content of the lithium ions is unchanged.
Comparative example 3
Adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding potassium aluminosilicate into the molten salt when the solid in the furnace reaches a molten state to form the molten salt, wherein the adding amount is 0.2 percent of the mass of the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃, and detecting the lithium ion content in the molten salt to be 184ppm after 67 minutes.
Comparative example 4
Adding 25 kg of potassium nitrate solid containing 200ppm of lithium ions into a tempering furnace, heating to 500 ℃, adding silicic acid into the molten salt when the solid in the furnace reaches a molten state to form the molten salt, wherein the adding amount is 0.2 percent of the mass of the molten salt, stopping heating, keeping the temperature of the molten salt at 500 ℃, and detecting that the lithium ion content in the molten salt is 192ppm after 67 minutes.
From examples 1 to 11, it can be seen that the method of the present invention can effectively reduce the concentration of lithium ions in the molten salt without introducing impurities; in addition, as can be seen from comparative examples 1-2, aluminum hydroxide is decomposed at high temperature to generate alumina, and the alumina can not absorb lithium ions basically, which shows that inorganic salts not containing aluminum can achieve the technical effects of the invention; in addition, the potassium aluminosilicate is adopted in the comparative example 3, the silicic acid is adopted in the comparative example 4, and the potassium metaaluminate is obviously weaker than the potassium metaaluminate in the example 1 according to the experimental result, so that the meta-aluminate of the invention has better lithium ion adsorption effect.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A method for controlling the concentration of lithium ions in a molten salt, comprising the steps of:
providing a molten salt treatment agent;
contacting a molten salt with the molten salt treatment agent for a predetermined time;
wherein the molten salt treatment agent comprises meta-aluminate.
2. The method according to claim 1, characterized in that 0.1g to 10g of the molten salt treatment agent is added per 100g of the molten salt; and/or
In the molten salt treating agent, the mass percentage of the metaaluminate is 50-80%.
3. The method according to claim 1, wherein the meta-aluminate is selected from the group consisting of: one or more of sodium metaaluminate, potassium metaaluminate, magnesium metaaluminate or calcium metaaluminate.
4. The method of claim 1 wherein the molten salt treatment agent further comprises a silicate, a forming material, and a surfactant.
5. The method of any of claims 1-4 wherein the step of providing a molten salt treatment agent comprises the steps of:
mixing raw materials for preparing the molten salt treatment agent;
and (3) sequentially adopting an extrusion forming process and a calcining process to treat to prepare the porous solid molten salt treating agent.
6. The method of claim 5 wherein the molten salt treatment agent is in the form of spheres, flakes or strands; and/or
The average grain diameter of the molten salt treating agent is 0.5 cm-2 cm.
7. A molten salt treating agent is characterized by comprising metaaluminate, silicate, a forming material and a surfactant.
8. The molten salt treatment agent of claim 7, which is a porous solid prepared by an extrusion molding process and a calcination process.
9. A molten salt treatment agent as claimed in claim 8, characterised in that the molten salt treatment agent is in the form of spheres, flakes or strips; and/or
The average grain diameter of the molten salt treating agent is 0.5 cm-2 cm.
10. A salt bath for strengthening glass, which is characterized by comprising an inorganic salt for preparing molten salt and a molten salt treating agent, wherein the molten salt treating agent contains meta-aluminate.
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| CN112079559B (en) | 2023-03-10 |
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