Device and process for dechlorinating frozen liquid of lithium carbonate

Abstract

The invention relates to the technical field of lithium carbonate production, in particular to a dechlorination device and a dechlorination process for frozen liquid of lithium carbonate. The device comprises an activation equipment group, wherein the activation equipment group is configured to be an area for activating a dechlorinating agent by using acid liquor and performing solid-liquid separation to obtain dechlorinating agent activated slag and activated liquor; the dechlorination reaction equipment group is configured to be an area in which dechlorination is carried out on the frozen lithium carbonate liquid by using the dechlorination agent activation slag and solid-liquid separation is carried out to obtain dechlorinated liquid and chlorine-containing filter residues; the alkali washing reaction equipment group is configured to be an area for carrying out mixed regeneration on the chlorine-containing filter residues by utilizing alkali liquor and carrying out solid-liquid separation to obtain alkali washing residues and alkali washing liquid; the alkali washing slag is returned to the activation equipment group through a pipeline to be used as a dechlorinating agent, and the activated liquid is returned to the activation equipment group through a pipeline to be used as acid liquid. The device and the method have the advantages that the chlorine removal effect is good, Li < + > is basically not lost in the treatment process, and the cycle performance of the chlorine removal agent is good when the device and the method are used for removing the chlorine ions in the lithium carbonate frozen liquid.

Description

Technical Field

[0001] The invention relates to the technical field of lithium carbonate production, and in particular to a device for dechlorinating frozen lithium carbonate liquid and a dechlorination process. Background Art

[0002] The lithium carbonate production process generally uses sodium carbonate as a precipitant to obtain the product. Currently, the sodium carbonate products on the market generally contain 0.2% to 0.36% of chlorine. The chloride ions in the system are enriched as the production progresses (the high point is reflected in the liquid after freezing). Chlorine is a harmful element in the lithium carbonate production system. High-chlorine operation will have a great impact on the safe operation and service life of the equipment, and will also affect the purity of subsequent products. The system needs to open-circuit the chloride ions.

[0003] The inventors found in the process of researching and implementing the dechlorination of lithium carbonate after freezing that the extraction method uses the principle that N235 can extract chlorine for dechlorination, and its cost is satisfactory, but the extraction process will take away some Li + The loss of Li + At the same time, it will also bring organic matter into the solution, increasing the cost of removing organic matter, and the recyclability is poor. The chlorine removal effect of ion exchange resin is limited, and when treating high-concentration chlorine solutions, the amount of wastewater produced by washing and reproducing the exchange resin is large, and it is also difficult to recover the lithium contained in the wastewater.

[0004] In view of the technical or economic deficiencies of the above methods, a method is proposed to remove chloride ions from the frozen lithium carbonate liquid with good removal effect and little loss of Li in the treatment process. + A method with low treatment cost and good recyclability is very necessary. Summary of the invention

[0005] In view of the shortcomings of the prior art, the object of the present invention is to provide a device and a process for removing chlorine from frozen lithium carbonate liquid. The device and method have a good removal effect on chloride ions in frozen lithium carbonate liquid, and the treatment process basically does not lose Li + , low processing cost and good recyclability.

[0006] In order to achieve the above object, the present invention adopts the following technical solution: The object of the present invention is to provide a device for dechlorinating a frozen lithium carbonate liquid, the device comprising: An activation equipment group, configured to activate the dechlorinating agent with an acid solution and separate the solid from the liquid to obtain an activated slag of the dechlorinating agent and an activated liquid; A dechlorination reaction equipment group, configured to use dechlorination agent activated slag to dechlorinate the frozen lithium carbonate liquid and separate the solid and liquid to obtain a dechlorinated liquid and a chlorine-containing filter residue; The alkali washing reaction equipment group is configured as an area for mixing and regenerating the chlorine-containing filter residue with alkali solution and performing solid-liquid separation to obtain alkali washing residue and alkali washing liquid; the alkali washing residue is returned to the activation equipment group through a pipeline for use as a dechlorination agent, and the activated liquid is returned to the activation equipment group through a pipeline for use as an acid solution.

[0007] As a further technical solution, the dechlorination reaction equipment group includes a dechlorination reaction tank, a dechlorination transfer tank, a dechlorination filter press and a dechlorination post-liquid tank; The dechlorination reaction tank is configured as an area where dechlorination of frozen lithium carbonate liquid is performed using dechlorination agent activated slag to obtain a dechlorination mixture. The top of the dechlorination reaction tank has an acid inlet, an alkali liquid inlet, a dechlorination agent activated slag inlet and a frozen lithium carbonate liquid inlet; the bottom of the dechlorination reaction tank has a dechlorination mixture outlet; The inlet of the dechlorination transfer tank is connected to the outlet of the dechlorination mixture through a pipeline; the outlet of the dechlorination transfer tank is connected to the inlet of the dechlorination filter press through a pipeline; the liquid outlet of the dechlorination filter press is connected to the post-dechlorination liquid tank through a pipeline, and the solid outlet of the dechlorination filter press is connected to the alkaline washing reaction equipment group through a pipeline.

[0008] As a further technical solution, the activation equipment group includes an activation kettle, an activation filter press and a post-activation liquid tank; The activation kettle is configured as an area for activating the alkali-washing slag with acid solution to obtain an activated slurry. The top of the activation kettle is provided with an acid solution inlet, a dechlorination agent inlet and an alkali-washing slag inlet. The bottom of the activation kettle is provided with an activated slurry outlet. The activated slurry outlet is connected to the activation filter press inlet through a pipeline. The liquid outlet of the activation filter press is connected to the activated liquid tank through a pipeline. The solid outlet of the activation filter press is connected to the dechlorination agent activated slag inlet of the dechlorination reaction tank through a pipeline.

[0009] As a further technical solution, the alkali washing reaction equipment group includes an alkali washing reaction tank, an alkali washing residue filter press, an alkali washing transfer tank and an alkali washing wastewater storage tank; The alkali washing reaction tank is configured as an area for regenerating the mixture of chlorine-containing filter residue and alkali solution. The top of the alkali washing reaction tank is provided with an alkali solution inlet and a chlorine-containing filter residue inlet, and the bottom of the alkali washing reaction tank is provided with an alkali washing mixture outlet, the alkali washing mixture outlet is connected to the alkali washing transfer tank inlet through a pipeline, the alkali washing transfer tank outlet is connected to the alkali washing residue filter press inlet through a pipeline, the alkali washing residue filter press liquid outlet is connected to the alkali washing wastewater storage tank through a pipeline, and the alkali washing residue filter press solid outlet is connected to the alkali washing residue inlet on the activation kettle through a pipeline.

[0010] Another object of the present invention is to provide a method for dechlorinating a frozen lithium carbonate liquid, comprising the following steps: S1, activating a dechlorinating agent with an acid solution to obtain an activated slurry, wherein the dechlorinating agent is selected from at least one of bismuth trioxide and alkali-washed slag containing bismuth trioxide; S2, filtering the activated slurry obtained in S1 to obtain activated liquid and dechlorination agent activated residue; S3, mixing the frozen high chloride lithium carbonate liquid with the dechlorinating agent activated residue obtained in S2, adjusting the pH to perform a dechlorination reaction to obtain a dechlorination mixture; S4, filtering the dechlorinated mixed material obtained in S3 to obtain a dechlorinated liquid and a chlorine-containing filter residue; S5, mixing the chlorine-containing filter residue obtained in S4 with alkali solution for regeneration treatment, filtering to obtain bismuth trioxide-containing alkali-washed residue, and returning to S1 for circulation as a dechlorination agent.

[0011] The main reaction principle involved in the process of dechlorinating the chlorine-containing lithium carbonate liquid after freezing by using bismuth trioxide (Bi2O3) in this application is: Bi2O3+ 6H + → 2Bi 3+ + 3H2O Bi 3+ + 3Cl − → BiC13 BiC13+ H2O → BiOCl↓ + 2HCl 2BiOCl↓ + 2NaOH →Bi2O3↓ +2NaCl + H2O The present application utilizes sulfuric acid to activate bismuth trioxide and alkaline washing slag containing bismuth trioxide. The activation process can be carried out in a conventional activation kettle. There are no special restrictions on the activation reagents and activation conditions. It is sufficient to convert bismuth trioxide into (Bi2O)(OH)2SO4 or Bi2(SO4)3. Therefore, the activation treatment described in S1 is to convert bismuth trioxide into at least one of (Bi2O)(OH)2SO4 and Bi2(SO4)3 under the action of acid solution.

[0012] As a further technical solution, the activation treatment in S1 is to generate at least one of (Bi2O)(OH)2SO4 and Bi2(SO4)3 from bismuth trioxide under the action of acid solution; Preferably, the acid solution in S1 is selected from at least one of dilute sulfuric acid or activated solution; the concentration of sulfuric acid in the acid solution in S1 is 8% to 10%; the weight ratio of the dechlorination agent used in the activation treatment to the acid solution is 1:10 to 13; the activation treatment time is 5 min to 30 min; Preferably, the concentration of sulfuric acid in the acid solution in S1 is 10%, the weight ratio of the dechlorination agent to the dilute sulfuric acid used in the activation treatment is 1:10, and the activation treatment time is 20 minutes.

[0013] As a further technical solution, in S2, the activated liquid returns to S1 as acid liquid circulation.

[0014] As a further technical solution, the high-chloride lithium carbonate frozen liquid described in S3 is the high-chloride filtrate after the sodium carbonate lithium precipitation process in the lithium carbonate production workshop; The composition of the frozen high chloride lithium carbonate liquid includes: Li + 20~40g / L, K + 40~50g / L, Na + 50~65g / L、Cl - 30~50g / L and SO4 2- 150~200g / L; As a further technical solution, the dosage of the dechlorinating agent is 20 to 40 g / L of the frozen high-chloride lithium carbonate liquid.

[0015] As a further technical solution, the method for adjusting pH in S3 is to use a pH regulator to maintain the pH at 4 to 6; Preferably, the pH adjuster is selected from at least one of an acid and a base; Preferably, the pH regulator is selected from at least one of a sodium hydroxide solution, a sulfuric acid solution or an activated solution.

[0016] As a further technical solution, the dechlorination reaction in S3 is carried out by stirring at 20°C to 60°C for 30min to 120min.

[0017] As a further technical solution, in S4, if the chlorine content of the obtained dechlorinated liquid is ≤10g / L, it is returned to the lithium carbonate workshop for use; if the chlorine content of the dechlorinated liquid is ≥10g / L, it is returned to S3 as a high-chloride lithium carbonate frozen liquid to continue the dechlorination reaction.

[0018] As a further technical solution, the alkali solution in S5 is a sodium hydroxide solution with a concentration of 3% to 5%; The mass ratio of the alkali solution to the chlorine-containing filter residue is 5 to 7:1.

[0019] As a further technical solution, the filtration methods described in S2, S4 and S5 are respectively selected from centrifugation or plate and frame filtration.

[0020] Compared with the prior art, the present invention has the following beneficial effects: 1. The present application provides a device for dechlorinating the frozen liquid of lithium carbonate, which is suitable for dechlorinating the frozen liquid of lithium carbonate by bismuth trioxide precipitation method. The device first activates the dechlorinating agent by acid solution through an activation equipment group and separates the solid and liquid to obtain the dechlorinating agent activated residue and the activated liquid; then dechlorinates the frozen liquid of lithium carbonate by using the dechlorinating agent activated residue through a dechlorination reaction equipment group and separates the solid and liquid to obtain the dechlorinated liquid and the chlorine-containing filter residue; the chlorine-containing filter residue is mixed and regenerated by using alkali solution through an alkali washing reaction equipment group and solid-liquid separation is performed to obtain the alkali washing residue and the alkali washing liquid; then the alkali washing residue is returned to the activation equipment group through a pipeline for use as a dechlorinating agent, and the activated liquid is returned to the activation equipment group through a pipeline for use as an acid. Through the above-mentioned design method, the above-mentioned device can not only realize the efficient dechlorination of the frozen liquid of high-chloride lithium carbonate, but also protect the equipment to reduce the corrosion of chloride ions to the equipment and pipelines, and extend the service life of the equipment. The device can also realize the activation and regeneration process of the dechlorination agent and the reuse of the activated acid solution, thereby realizing the raw material circulation of the dechlorination process of the frozen lithium carbonate liquid, and has the advantages of high reagent utilization rate and good circulation performance. In addition, the functions of each device in the device are single and stable, and it has the advantages of stable operation and easy control, and has a high value for industrial promotion.

[0021] 2. The method for dechlorination of frozen lithium carbonate liquid provided in this application utilizes bismuth trioxide (Bi2O3) as a dechlorinating agent, and the dechlorinating agent is activated with sulfuric acid and used for dechlorination of frozen lithium carbonate liquid, and the optimal reaction conditions are determined. By recycling this process, the chloride ions in the frozen lithium carbonate liquid can be reduced to below 10g / L, which can effectively reduce the corrosion of chloride ions to equipment and pipelines and extend the service life of the equipment.

[0022] 3. The main raw material consumed by this process is sodium hydroxide, a common and cheap chemical raw material in industry. The production cost is low, which can save a lot of costs for enterprises and have considerable economic benefits. In addition, this process does not have complicated post-processing procedures, shortening the process flow. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic diagram of the structure of the dechlorination device for the refrigerated lithium carbonate liquid in this application. DETAILED DESCRIPTION

[0024] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] Please combine Figure 1The present application provides a device for dechlorinating frozen lithium carbonate liquid, the device comprising: an activation equipment group, configured to use acid to activate the dechlorinating agent and perform solid-liquid separation to obtain a dechlorinating agent activated residue and an activated liquid area; a dechlorination reaction equipment group, configured to use the dechlorinating agent activated residue to dechlorinate the frozen lithium carbonate liquid and perform solid-liquid separation to obtain a dechlorinated liquid and a chlorine-containing filter residue area; an alkali washing reaction equipment group, configured to use alkali liquid to mix and regenerate the chlorine-containing filter residue and perform solid-liquid separation to obtain an alkali washing residue and an alkali washing liquid area; the alkali washing residue is returned to the activation equipment group through a pipeline for use as a dechlorinating agent, and the activated liquid is returned to the activation equipment group through a pipeline for use as an acid solution.

[0026] As a preferred embodiment, the dechlorination reaction equipment group includes a dechlorination reaction tank 21, a dechlorination transfer tank 22, a dechlorination filter press 23 and a dechlorination liquid tank 24; the dechlorination reaction tank 21 is configured as a region for dechlorinating the frozen lithium carbonate liquid using dechlorination agent activated slag to obtain a dechlorination mixture, and the top of the dechlorination reaction tank 21 has an acid inlet, an alkali liquid inlet, a dechlorination agent activated slag inlet, a lithium carbonate frozen liquid inlet and a dechlorination liquid inlet; the bottom of the dechlorination reaction tank 21 has a dechlorination mixture outlet; the inlet of the dechlorination transfer tank 22 is connected to the dechlorination mixture outlet through a pipeline; the outlet of the dechlorination transfer tank 22 is connected to the inlet of the dechlorination filter press 23 through a pipeline; the liquid outlet of the dechlorination filter press 23 is connected to the dechlorination liquid tank 24 through a pipeline, and the solid outlet of the dechlorination filter press 23 is connected to the alkaline washing reaction equipment group through a pipeline.

[0027] As a preferred embodiment, the activation equipment group includes an activation kettle 11, an activation filter press 12 and an activated liquid tank 13; the activation kettle 11 is configured to activate the alkali-washed slag using acid (the acid is pre-prepared in the dilute acid preparation tank 41 using concentrated sulfuric acid in the concentrated sulfuric acid tank 49 or the activated liquid) to obtain an activated slurry area, the top of the activation kettle 11 has an acid inlet, a dechlorination agent inlet and an alkali-washed slag inlet, the bottom of the activation kettle 11 has an activated slurry outlet, the activated slurry outlet is connected to the activation filter press 12 inlet through a pipeline, the liquid outlet of the activation filter press 12 is connected to the activated liquid tank 13 through a pipeline, and the solid outlet of the activation filter press 12 is connected to the dechlorination agent activated slag inlet of the dechlorination reaction tank 21 through a pipeline.

[0028] As a preferred embodiment, the alkali washing reaction equipment group includes an alkali washing reaction tank 31, an alkali washing residue filter press 32, an alkali washing transfer tank 33 and an alkali washing wastewater storage tank 34; the alkali washing reaction tank 31 is configured as an area for mixing chlorine-containing filter residue with alkali solution (the alkali solution is pre-prepared in the alkali solution tank 42) for regeneration treatment, the top of the alkali washing reaction tank 31 has an alkali solution inlet and a chlorine-containing filter residue inlet, the bottom of the alkali washing reaction tank 31 has an alkali washing mixture outlet, the alkali washing mixture outlet is connected to the inlet of the alkali washing transfer tank 33 through a pipeline, the outlet of the alkali washing transfer tank 33 is connected to the inlet of the alkali washing residue filter press 32 through a pipeline, the liquid outlet of the alkali washing residue filter press 32 is connected to the alkali washing wastewater storage tank 34 through a pipeline, and the solid outlet of the alkali washing residue filter press 32 is connected to the alkali washing residue inlet on the activation kettle 11 through a pipeline.

[0029] In the above device, the activation kettle 11, the dechlorination reaction tank 21, the alkali washing reaction tank 31, the alkali washing transfer tank 33 and the alkali washing residue filter press 32 are equipped with a clean water pipe 43 for washing or batching. The filter press unit is equipped with a compressed air pipe 43 and a squeeze water tank 47 for assistance. The lithium carbonate frozen liquid pipe 44 is connected to the dechlorination reaction tank 21 for feeding the high-chloride lithium carbonate frozen liquid; the steam pipe 46 is used for auxiliary heating of the equipment; the sewage in the device enters the sewage station through the sewage pipe 48 for unified collection and treatment.

[0030] The present application provides a device for dechlorination of frozen lithium carbonate liquid, which is suitable for dechlorination of frozen lithium carbonate liquid by bismuth trioxide precipitation method. The device first activates the dechlorinating agent with acid solution through an activation equipment group and separates the solid and liquid to obtain dechlorinating agent activated residue and activated liquid; then dechlorinates the frozen lithium carbonate liquid with dechlorinating agent activated residue through a dechlorination reaction equipment group and separates the solid and liquid to obtain dechlorinated liquid and chlorine-containing filter residue; uses alkali solution to mix and regenerate the chlorine-containing filter residue through an alkali washing reaction equipment group and separates the solid and liquid to obtain alkali washing residue and alkali washing liquid; returns the alkali washing residue to the activation equipment group through a pipeline for use as a dechlorinating agent, and returns the activated liquid to the activation equipment group through a pipeline for use as an acid. Through the above-mentioned design method, the above-mentioned device can not only realize efficient dechlorination of high-chloride lithium carbonate frozen liquid, but also protect the equipment to reduce the corrosion of chloride ions to the equipment and pipelines, and extend the service life of the equipment. The device can also realize the activation and regeneration process of the dechlorination agent and the reuse of the activated acid solution, thereby realizing the raw material circulation of the dechlorination process of the frozen lithium carbonate liquid, and has the advantages of high reagent utilization rate and good circulation performance. In addition, the functions of each device in the device are single and stable, and it has the advantages of stable operation and easy control, and has a high value for industrial promotion.

[0031] Another embodiment of the present invention provides a method for dechlorinating a frozen lithium carbonate solution, comprising the following steps: S1, activating a dechlorinating agent with an acid solution to obtain an activated slurry, wherein the dechlorinating agent is selected from at least one of bismuth trioxide and alkali-washed slag containing bismuth trioxide; S2, filtering the activated slurry obtained in S1 to obtain activated liquid and dechlorination agent activated residue; S3, mixing the frozen high chloride lithium carbonate liquid with the dechlorinating agent activated residue obtained in S2, adjusting the pH to perform a dechlorination reaction to obtain a dechlorination mixture; S4, filtering the dechlorinated mixed material obtained in S3 to obtain a dechlorinated liquid and a chlorine-containing filter residue; S5, mixing the chlorine-containing filter residue obtained in S4 with alkali solution for regeneration treatment, filtering to obtain bismuth trioxide-containing alkali-washed residue, and returning to S1 for circulation as a dechlorination agent.

[0032] As a preferred embodiment, the acid solution in S1 is selected from at least one of dilute sulfuric acid or activated solution; the sulfuric acid concentration in the acid solution in S1 is 8% to 10%; the weight ratio of the dechlorinating agent used in the activation treatment to the acid solution is 1:10 to 13; the activation treatment time is 5 min to 30 min; preferably, the sulfuric acid concentration in the acid solution in S1 is 10%, the weight ratio of the dechlorinating agent used in the activation treatment to the dilute sulfuric acid is 1:10, and the activation treatment time is 20 min; And / or, in S2, the activated liquid returns to S1 as acid liquid circulation.

[0033] As a preferred embodiment, the high chloride lithium carbonate frozen liquid in S3 is a high chloride filtrate after the sodium carbonate lithium precipitation process in the lithium carbonate production workshop; preferably, the composition of the high chloride lithium carbonate frozen liquid includes: Li + 20~40g / L, K + 40~50g / L, Na + 50~65g / L、Cl - 30~50g / L and SO4 2- 150~200g / L.

[0034] And / or, the amount of dechlorinating agent used is 20-40 g / L of high chloride lithium carbonate frozen liquid.

[0035] As a preferred embodiment, the method for adjusting pH in S3 is to use a pH regulator to maintain the pH at 4 to 6; Preferably, the pH adjuster is selected from at least one of an acid and a base; Preferably, the pH regulator is selected from at least one of a sodium hydroxide solution, a sulfuric acid solution or an activated solution; Preferably, the dechlorination reaction in S3 is carried out by stirring at 20°C to 60°C for 30min to 120min; Preferably, the dechlorination reaction is carried out by stirring at 40° C. for 100 min.

[0036] As a preferred embodiment, multiple cycles are used in S4 to reduce the chloride ions in the dechlorinated liquid. Specifically, if the chlorine content of the dechlorinated liquid is ≤10 g / L, it is returned to the lithium carbonate workshop for use; if the chlorine content of the dechlorinated liquid is ≥10 g / L, it is returned to S3 as a high-chloride lithium carbonate frozen liquid to continue the dechlorination reaction.

[0037] As a preferred embodiment, the alkali solution in S5 is a sodium hydroxide solution with a concentration of 3% to 5%; The mass ratio of the alkali solution to the chlorine-containing filter residue is 5 to 7:1; The scheme and effect of the above-mentioned method for removing chlorine from frozen lithium carbonate liquid are further described below through specific examples. The methods described in the following specific implementation cases are conventional methods unless otherwise specified, and the raw materials can be obtained from public commercial channels unless otherwise specified.

[0038] Example 1 Pump 98% concentrated sulfuric acid and water into the dilute acid preparation tank to prepare 10% dilute sulfuric acid for standby use. Prepare 4% sodium hydroxide solution in the alkali solution tank for standby use. The process of dechlorination of frozen lithium carbonate liquid is as follows: S1. Activate the dechlorinator with acid in an activation kettle and stir for 20 minutes to obtain a milky white activated slurry; wherein the dechlorinator is bismuth trioxide or alkali-washed residue containing bismuth trioxide; the concentration of dilute sulfuric acid used in the S1 acid is 10%, and the weight ratio of the dechlorinator to the dilute sulfuric acid is 1:10; S2, the activated slurry is filtered by a plate and frame filter press to obtain an activated liquid and a filter residue, the filter residue is used as a dechlorination agent activated residue to enter the next process, and the activated liquid returns to step 1 as an acid solution circulation; S3, mixing the frozen high chloride lithium carbonate liquid and the dechlorinating agent activated slag in a dechlorination reaction tank, wherein the dechlorinating agent is 20 g / L of the frozen high chloride lithium carbonate liquid; maintaining the pH at 5.0, reacting at a temperature of 40° C. for 60 min, and performing a dechlorination reaction to obtain a dechlorination mixture; S4, filtering the dechlorinated mixture using a dechlorination filter press to obtain a dechlorinated liquid and a chlorine-containing filter residue; S5, the chlorine-containing filter residue is regenerated in an alkali washing reaction tank using 4% alkali solution, the mass ratio of alkali solution to chlorine-containing filter residue is 6:1, and the alkali washing residue containing bismuth trioxide is obtained by filtering with an alkali washing residue filter press, and returning to step 1 for circulation as a dechlorinating agent; S6. The changes in the liquid substance content of chlorinated lithium carbonate after freezing are shown in Table 1.

[0039] Embodiments 2 to 12 According to the method of Example 1, the difference is that the amount of the dechlorination agent activated slag in S3, the pH and the reaction temperature are as shown in Table 1, and the change of the liquid substance content of the chlorine-containing lithium carbonate after freezing is as shown in Table 1, wherein the chlorine content is determined by mercuric nitrate solution titration method, and the bismuth content is determined by EDTA method; Table 1: Reaction conditions and substance contents of Examples 1 to 12

[0040] According to Table 1, the process can reduce the chlorine content in the frozen liquid to about 20 g / L and the residual bismuth to below 0.5 mg / L when the amount of dechlorinating agent added is 20-40 g / L, the temperature is room temperature to 60°C, and the pH is 5-6.

[0041] After multiple cycles, the chlorine content in the frozen lithium carbonate liquid can be reduced to below 10g / L, which can effectively reduce the corrosion of chloride ions on equipment and pipelines and extend the service life of the equipment. The chlorine-containing filter residue can be returned to the system for use after alkaline washing regeneration and acid activation. The effect of recycling for more than 20 times remains basically unchanged. The discharged alkaline washing liquid Li + The loss rate is about 0.3%. The above device and process are used to remove chlorine from the frozen lithium carbonate liquid, which has a good dechlorination effect and basically no loss of Li in the dechlorination process. + , the advantages of dechlorination agent circulation performance.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present application and not to limit it. Although the present application has been described in detail with reference to the preferred embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present application can still be modified or some technical features can be replaced by equivalents, which should all be included in the scope of the technical solution requested for protection in this application.

Claims

1. A device for dechlorinating frozen lithium carbonate liquid, characterized in that: The device includes: An activation equipment group, configured to activate the dechlorinating agent with an acid solution and separate the solid from the liquid to obtain an activated slag of the dechlorinating agent and an activated liquid; A dechlorination reaction equipment group, configured to use dechlorination agent activated slag to dechlorinate the frozen lithium carbonate liquid and separate the solid and liquid to obtain a dechlorinated liquid and a chlorine-containing filter residue; The alkali washing reaction equipment group is configured as an area for mixing and regenerating the chlorine-containing filter residue with alkali solution and performing solid-liquid separation to obtain alkali washing residue and alkali washing liquid; the alkali washing residue is returned to the activation equipment group through a pipeline for use as a dechlorination agent, and the activated liquid is returned to the activation equipment group through a pipeline for use as an acid solution.

2. A device for dechlorinating lithium carbonate after freezing according to claim 1, characterized in that: The dechlorination reaction equipment group includes a dechlorination reaction tank, a dechlorination transfer tank, a dechlorination filter press and a dechlorination post-liquid tank; The dechlorination reaction tank is configured as an area where dechlorination of frozen lithium carbonate liquid is performed using dechlorination agent activated slag to obtain a dechlorination mixture. The top of the dechlorination reaction tank has an acid inlet, an alkali liquid inlet, a dechlorination agent activated slag inlet and a frozen lithium carbonate liquid inlet; the bottom of the dechlorination reaction tank has a dechlorination mixture outlet; The inlet of the dechlorination transfer tank is connected to the outlet of the dechlorination mixture through a pipeline; the outlet of the dechlorination transfer tank is connected to the inlet of the dechlorination filter press through a pipeline; the liquid outlet of the dechlorination filter press is connected to the post-dechlorination liquid tank through a pipeline, and the solid outlet of the dechlorination filter press is connected to the alkaline washing reaction equipment group through a pipeline.

3. A device for dechlorinating the frozen lithium carbonate liquid according to claim 2, characterized in that: The activation equipment group includes an activation kettle, an activation filter press and a post-activation liquid tank; The activation kettle is configured as an area for activating the alkali-washing slag with acid solution to obtain an activated slurry. The top of the activation kettle is provided with an acid solution inlet, a dechlorination agent inlet and an alkali-washing slag inlet. The bottom of the activation kettle is provided with an activated slurry outlet. The activated slurry outlet is connected to the activation filter press inlet through a pipeline. The liquid outlet of the activation filter press is connected to the activated liquid tank through a pipeline. The solid outlet of the activation filter press is connected to the dechlorination agent activated slag inlet of the dechlorination reaction tank through a pipeline.

4. A device for dechlorinating the frozen lithium carbonate liquid according to claim 3, characterized in that: The alkali washing reaction equipment group includes an alkali washing reaction tank, an alkali washing residue filter press, an alkali washing transfer tank and an alkali washing wastewater storage tank; The alkali washing reaction tank is configured as an area for regenerating the mixture of chlorine-containing filter residue and alkali solution. The top of the alkali washing reaction tank is provided with an alkali solution inlet and a chlorine-containing filter residue inlet, and the bottom of the alkali washing reaction tank is provided with an alkali washing mixture outlet, the alkali washing mixture outlet is connected to the alkali washing transfer tank inlet through a pipeline, the alkali washing transfer tank outlet is connected to the alkali washing residue filter press inlet through a pipeline, the alkali washing residue filter press liquid outlet is connected to the alkali washing wastewater storage tank through a pipeline, and the alkali washing residue filter press solid outlet is connected to the alkali washing residue inlet on the activation kettle through a pipeline.

5. A method for dechlorinating a frozen lithium carbonate solution, characterized in that: The following steps are involved: S1, activating a dechlorinating agent with an acid solution to obtain an activated slurry, wherein the dechlorinating agent is selected from at least one of bismuth trioxide and alkali-washed slag containing bismuth trioxide; S2, filtering the activated slurry obtained in S1 to obtain activated liquid and dechlorination agent activated residue; S3, mixing the frozen high chloride lithium carbonate liquid with the dechlorinating agent activated residue obtained in S2, adjusting the pH to perform dechlorination reaction to obtain a dechlorination mixture; S4, filtering the dechlorinated mixed material obtained in S3 to obtain a dechlorinated liquid and a chlorine-containing filter residue; S5, mixing the chlorine-containing filter residue obtained in S4 with alkali solution for regeneration treatment, filtering to obtain bismuth trioxide-containing alkali-washed residue, and returning to S1 for circulation as a dechlorination agent.

6. A method for dechlorinating a frozen lithium carbonate liquid according to claim 5, characterized in that: The acid solution in S1 is selected from at least one of dilute sulfuric acid or activated solution; the concentration of sulfuric acid in the acid solution in S1 is 8% to 10%; the weight ratio of the dechlorinating agent used in the activation treatment to the acid solution is 1:10 to 13; the activation treatment time is 5 min to 30 min; Preferably, the concentration of sulfuric acid in the acid solution in S1 is 10%, the weight ratio of the dechlorination agent to the dilute sulfuric acid used in the activation treatment is 1:10, and the activation treatment time is 20 minutes; And / or, in S2, the activated liquid returns to S1 as acid liquid circulation.

7. A method for dechlorinating a frozen lithium carbonate liquid according to claim 5, characterized in that: S3 The high chloride lithium carbonate frozen liquid is the high chloride filtrate after the sodium carbonate lithium precipitation process in the lithium carbonate production workshop; preferably, the composition of the high chloride lithium carbonate frozen liquid includes: Li + 20~40g / L, K + 40~50g / L, Na + 50~65g / L、Cl - 30~50g / L and SO4 2- 150~200g / L; And / or, the amount of dechlorinating agent used is 20-40 g / L of high chloride lithium carbonate frozen liquid.

8. A method for dechlorinating a frozen lithium carbonate liquid according to claim 5, characterized in that: The method for adjusting pH in S3 is to use a pH regulator to maintain the pH at 4 to 6; Preferably, the pH adjuster is selected from at least one of an acid and a base; Preferably, the pH regulator is selected from at least one of a sodium hydroxide solution, a sulfuric acid solution or an activated solution; Preferably, the dechlorination reaction in S3 is carried out by stirring at 20°C to 60°C for 30min to 120min.

9. A method for dechlorinating a frozen lithium carbonate liquid according to claim 5, characterized in that: In S4, if the chlorine content of the obtained dechlorinated liquid is ≤10g / L, it is returned to the lithium carbonate workshop for use; if the chlorine content of the dechlorinated liquid is ≥10g / L, it is returned to S3 as a high-chloride lithium carbonate frozen liquid to continue the dechlorination reaction.

10. A method for dechlorinating a frozen lithium carbonate liquid according to claim 5, characterized in that: The alkali solution described in S5 is a sodium hydroxide solution with a concentration of 3% to 5%; The mass ratio of the alkali solution to the chlorine-containing filter residue is 5 to 7:1.

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