Ca2PO4Cl decomposition and Ca / P resource utilization method

Abstract

The invention belongs to the field of solid waste utilization, and particularly provides a Ca2PO4Cl decomposition and resource utilization method, which comprises the following steps: dispersing Ca2PO4Cl in an alcohol solvent, and carrying out solvothermal modification treatment to obtain a modified material; carrying out protonation treatment on the modified material in a separation liquid containing an imgabs0 # auxiliary agent in a formula 1 # and hydrochloric acid, and decomposing to obtain a treatment product of phosphoric acid and calcium chloride; and separating to obtain calcium chloride and phosphoric acid. The method for decomposition and resource utilization of Ca2PO4Cl still belongs to the industry blank, and in order to fill the technical blank, the innovative research shows that Ca2PO4Cl is subjected to solvothermal modification transformation in alcohol in advance, and then ion exchange is performed in a hydrochloric acid solution containing a formula 1, so that decomposition of Ca2PO4Cl can be realized, and calcium chloride and phosphoric acid are formed.

Description

Technical Field

[0001] The present invention belongs to the field of slag recycling, and specifically relates to the field of P / Ca separation in Ca 2 PO 4 Cl. Background Art

[0002] Due to its advantages such as green safety, long cycle life, and economic cost, the market share of lithium iron phosphate batteries in China has been increasing year by year, accounting for about 60%. However, a large number of retired power lithium iron phosphate batteries need to be recycled urgently. Although existing processes can recover valuable metals from lithium iron phosphate, some lithium iron phosphate recycling processes will produce slag with a Ca 2 PO 4 Cl phase. For the composition of this phase, there is no good decomposition and Ca / P selective separation method in the prior art.

[0003] For example, the Chinese patent document with the publication number CN104773716A discloses a method for feed-grade calcium sodium phosphate, specifically discloses a method for obtaining feed-grade calcium sodium phosphate by roasting calcium chlorophosphate and table salt at 800 - 1200°C. In addition, the Chinese patent document with the publication number CN115043384A discloses a method for manufacturing calcium pyrophosphate by decomposing medium and low-grade phosphate rock with hydrochloric acid, specifically records a method for obtaining calcium pyrophosphate by roasting calcium chlorophosphate at a temperature of 550 ± 20°C.

[0004] In summary, there is no method in the prior art to efficiently decompose Ca 2 PO 4 Cl and resourcefully produce calcium chloride and phosphoric acid. Summary of the Invention

[0005] Aiming at the problem of the lack of existing Ca 2 PO 4 Cl decomposition and calcium and phosphorus resource utilization processes, the first object of the present invention is to provide a method for decomposing Ca 2 PO 4 Cl, aiming to decompose calcium and phosphorus in Ca 2 PO 4 Cl to form phosphoric acid and calcium chloride.

[0006] The second object of the present invention is to provide a method for resource utilization of Ca / P in Ca 2 PO 4 Cl, aiming to decompose and resourcefully recycle calcium and phosphorus in Ca 2 PO 4 Cl to obtain calcium phosphate and calcium chloride.

[0007] Ca 2 PO 4The method for decomposing Ca 2 PO 4 Cl is dispersed in an alcohol solvent for solvothermal modification treatment to obtain a modified material;

[0008] Then, the modified material is protonated in a separation liquid containing the additive of Formula 1 and hydrochloric acid, and the decomposition treatment products of phosphoric acid and calcium chloride are obtained;

[0009]

[0010] In Formula 1, at least one of R 1 ~R 3 is substituted with an alkyl group of C 1 ~C 3 and the remaining substituents are H.

[0011] Ca 2 PO 4 The method for decomposing and resource utilization of Ca 2 PO 4 Cl still belongs to a blank in the industry. To fill this technical blank, the innovative research of the present invention shows that Ca 2 PO 4 Cl is pre-transformed by solvothermal modification in alcohol, and then ion exchange is carried out in a hydrochloric acid solution containing Formula 1, so that the decomposition of Ca 2 PO 4 Cl can be realized to form calcium chloride and phosphoric acid.

[0012] In the present invention, the Ca 2 PO 4 Cl can be any raw material containing the Ca 2 PO 4 Cl phase in the industry. For example, it can be obtained by roasting and water leaching of waste battery lithium iron phosphate materials with calcium chloride and sodium salt to obtain Ca

[0013] In the present invention, the solvothermal under the alcohol solvent is one of the keys to realizing the transformation of Ca 2 PO 4 Cl and facilitating the subsequent resource recovery of calcium and phosphorus. Preferably, the alcohol solvent includes alcohols with 1 to 4 carbon atoms; preferably at least one of methanol and ethanol; most preferably methanol. Research shows that using methanol as the solvent can unexpectedly further improve the modification effect and contribute to further improving the calcium and phosphorus decomposition effect.

[0014] In the present invention, the liquid-solid ratio of the alcohol solvent, Ca 2 PO 4 Cl is 10 to 40 mL / g, and further can be 15 to 35 mL / g.

[0015] In the present invention, the temperature of the solvothermal modification treatment is 100 - 200 °C, preferably 120 - 180 °C; more preferably 125 - 145 °C. The research of the present invention also shows that at the preferred temperature, it helps to further optimize the modification effect and further improve its decomposition and subsequent separation effect.

[0016] Preferably, the time of the solvothermal modification treatment is 1 - 10 h, and considering the treatment efficiency, it can be further 2 - 4 h.

[0017] In the present invention, the modified material obtained by solvothermal modification is placed in a hydrochloric acid solution containing the additive of Formula 1 for protonation treatment, which is beneficial to promoting the decomposition of Ca 2 PO 4 Cl and improving the decomposition efficiency.

[0018] In the present invention, in the additive of Formula 1, R 1 ~R 3 is methyl, ethyl or isopropyl.

[0019] In the present invention, the additive of Formula 1 can be prepared by reacting with hydrochloric acid according to Formula 2 and hydrochloric acid.

[0020] In the present invention, the separation liquid further contains an alcohol solvent. The alcohol solvent can be at least one of methanol and ethanol.

[0021] In the present invention, the modified material can be dispersed in a mixed solution containing the additive of Formula 1 and an alcohol solvent, and then a hydrochloric acid solution is added to adjust the pH of the system to complete the protonation reaction.

[0022] In the present invention, the weight ratio of the additive of Formula 1 to the modified material is 1.5 - 3:1; preferably 2 - 2.5:1.

[0023] In the present invention, the temperature of the protonation treatment is 35 - 65 °C; further it can be 45 - 55 °C. Research shows that at the preferred temperature, it helps to further optimize the decomposition effect.

[0024] The pH during the protonation treatment is controlled at 1 - 3, preferably 1 - 2.

[0025] Preferably, the time of the protonation treatment is 0.15 - 2 h; preferably 0.5 - 1 h.

[0026] As the same inventive concept, the present invention also provides a method for the Ca / P resource utilization of Ca 2 PO 4 Cl, for Ca 2 PO 4The Cl is subjected to solvothermal modification and protonation treatment to obtain a treatment product of phosphoric acid and calcium chloride; the treatment product is crystallized at a low temperature of 0 to 10 °C to obtain a calcium chloride product and a crystallization mother liquor enriched with phosphoric acid.

[0027] In the present invention, the crystallization mother liquor is subjected to water extraction with soft water to obtain a phosphoric acid solution.

[0028] Beneficial effects

[0029] The present invention fills the technical gap in the decomposition and resource utilization of Ca 2 PO 4 Cl. Innovatively, Ca 2 PO 4 Cl is subjected to solvothermal modification and transformation in alcohol, and then ion exchange is carried out in a hydrochloric acid solution containing Formula 1, so that the decomposition of Ca 2 PO 4 Cl can be achieved, forming calcium chloride and phosphoric acid, and realizing the separation of calcium and phosphorus. In the present invention, the purity of H 3 PO 4 can be as high as 99%, and it can be prepared for use as a product. CaCl 2 As an important chemical product, it can be used in various industries. Description of the drawings

[0030] Figure 1 XRD pattern of Ca 2 PO 4 Cl used in Example 1;

[0031] Figure 2 XRD pattern of the recovered phosphoric acid after transformation with ammonium molybdate in Example 1. Detailed implementation manners

[0032] The present invention will be further described in detail below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0033] In the present invention, the Ca 2 PO 4 Cl can be derived from the tailings after the treatment of waste lithium batteries, and its obtaining method is, for example:

[0034] The waste LFP (lithium iron phosphate) cathode material is mixed evenly with calcium chloride and sodium salts (such as one or several of sodium chloride, sodium carbonate, and sodium bicarbonate), then subjected to roasting treatment, and then subjected to water leaching treatment to obtain an iron and lithium leaching solution and Ca 2 PO 4 Cl water leaching residue (specifically, reference can be made to the patent document with the application number 2025100576368). Its XRD is shown in Figure 1 . Research in the present invention shows that this Ca 2 PO4 The decomposition efficiency of the Cl water leaching residue directly in the hydrochloric acid system is not high. Therefore, the present invention provides a process of alcohol-assisted solvothermal modification and decomposition assisted by the additive of Formula 1, specifically as follows:

[0035] Ca as described in the present invention 2 PO 4 The steps of the method for decomposing and recycling Cl include, for example:

[0036] Step (1): Solvothermal treatment

[0037] Put Ca 2 PO 4 Cl and alcohol into a high-pressure reactor according to a certain volume ratio, control the temperature at 120 - 180 °C, the time at 120 - 600 min, and the liquid-solid ratio at 10 - 30 mL / g.

[0038] Step (2): Filtration

[0039] Perform atmospheric pressure filtration on the above-obtained mixture, wash the filter residue with absolute ethanol, and dry it for later use.

[0040] Step (3): Protonation treatment

[0041] Under atmospheric pressure, mix the filter residue from Step 2 with triethylamine hydrochloride, control the mass ratio of the filter residue to triethylamine hydrochloride at 1:2 - 2.3, use absolute ethanol as the solvent, control the pH of the system at 1 - 2 with hydrochloric acid, control the temperature at 40 - 50 °C, and react for 15 - 40 min.

[0042] Step (4): Low-temperature separation

[0043] Control the system temperature at 0 - 10 °C. After CaCl 2 precipitates crystals from the solution, filter and dry it to obtain CaCl 2 product; extract the filtrate with soft water to obtain H 3 PO 4 and the raffinate. The raffinate can be acidified with hydrochloric acid and used as an additive, and recycled to the protonation treatment step of Step 3.

[0044] Example 1

[0045] Step 1 Solvothermal treatment: Put Ca 2 PO 4 Cl in a 50 mL polytetrafluoroethylene inner liner, add methanol with a liquid-solid ratio of 20 ml / g, then seal it and place it in a reaction oven at a temperature of 120 °C for 140 min.

[0046] Step 2 Filtration: Perform atmospheric pressure filtration on the above-obtained mixture, wash the filter residue with absolute ethanol repeatedly 3 - 5 times, and place it in an 80 °C oven to dry for later use.

[0047] Step 3 Protonation treatment: Add triethylammonium hydrochloride, which is 2.3 times the weight of the dried filter residue, and disperse it with a solvent (anhydrous ethanol, liquid-solid ratio of 20 mL / g -1 ). Then adjust the pH of the system to 1 - 2 with 1 - 2 M hydrochloric acid, control the reaction temperature at 40 °C, and react for 30 min.

[0048] Step 4 Low-temperature separation: Cool the reaction solution to between 0 - 10 °C, and white crystals will gradually appear, which are CaCl 2 crystals. Filter and dry them; extract the filtrate with soft water to obtain dilute H 3 PO 4 and the raffinate. The raffinate is recycled after hydrochloric acid acidification. The dilute H 3 PO 4 needs to be further concentrated to be used as a product.

[0049] Detect the obtained phosphoric acid. First, conduct a preliminary qualitative analysis with a pH test paper, and the pH value is 1 - 2. Subsequently, use the ammonium molybdate phosphoric acid method for more accurate detection. The specific steps are as follows: Take the obtained phosphoric acid solution, add ammonium molybdate tetrahydrate, stir. After precipitation appears, slow down the stirring speed, filter the obtained mixture, wash the precipitate with anhydrous ethanol. The bright yellow precipitate is preliminarily determined to be ammonium molybdate phosphate. Dry the precipitate and wait to be measured by XRD to determine the phase. The XRD results of the test are shown in Figure 2 . It shows that the obtained is indeed phosphoric acid, indicating that the method of the present invention realizes the resource-based preparation of phosphoric acid.

[0050] Example 2

[0051] Compared with Example 1, the only difference is that in Step 1, methanol in the solvothermal treatment step is replaced with anhydrous ethanol, and other operations and parameters are the same as those in Example 1.

[0052] Example 3

[0053] Compared with Example 1, the only difference is that in Step 1, adjust the liquid-solid ratio of methanol to Ca 2 PO 4 Cl in the solvothermal treatment process to 30 mL / g, and other operations and parameters are the same as those in Example 1.

[0054] Example 4

[0055] Compared with Example 1, the only difference is that in Step 1, the reaction temperature in the solvothermal treatment process is 180 °C, and the reaction time is 120 min, and other operations and parameters are the same as those in Example 1.

[0056] Example 5

[0057] Compared with Example 1, the only difference is that in Step 3, during the protonation treatment step, the reaction temperature is 50°C and the reaction lasts for 40 min, and other operations and parameters are the same as those in Example 1.

[0058] Comparative Example 1

[0059] Compared with Example 1, the only difference is that in Step 3, hydrochloric acid is not added, and other operations and parameters are the same as those in Example 1.

[0060] Comparative Example 2

[0061] Compared with Example 1, the only difference is that in Step 3, triethylamine hydrochloride in the protonation treatment step is replaced with ammonium chloride, and other operations and parameters are the same as those in Example 1.

[0062] Comparative Example 3

[0063] Compared with Example 1, the only difference is that in Step 1, instead of solvothermal treatment, ultrasonic pretreatment is carried out. The type and proportion of the solvent remain unchanged, and the ultrasonic treatment lasts for 60 min.

[0064] Comparative Example 4

[0065] Compared with Example 1, the only difference is that in Step 1, the treatment process is carried out under reflux at atmospheric pressure, and other operations and parameters are the same as those in Example 1.

[0066] Comparative Example 5

[0067] Compared with Example 1, the only difference is that in Step 1, an equal volume of water is used to replace the methanol, and other operations and parameters are the same as those in Example 1.

[0068] Table 1 The purity and yield of the obtained products are as follows:

[0069]

[0070] The present invention fills the technical gap in the efficient classification of Ca 2 PO 4 Cl and the separation and utilization of Ca / P. Innovatively, Ca 2 PO 4 Cl is subjected to solvothermal modification and transformation in alcohol, and then ion exchange is carried out in the hydrochloric acid solution containing Formula 1, so that the decomposition of Ca 2 PO 4 Cl can be achieved to form calcium chloride and phosphoric acid, realizing the separation of calcium and phosphorus.

Claims

1. A method for decomposing Ca2PO4Cl, characterized in that: Dispersing Ca2PO4Cl in an alcohol solvent and subjecting it to solvent thermal modification to obtain a modified material; The modified material is then protonated in a separation solution containing an auxiliary agent of formula 1 and hydrochloric acid to decompose and obtain treatment products of phosphoric acid and calcium chloride; In Formula 1, at least one of R1 to R3 is substituted with a C1 to C3 alkyl group, and the remaining substituents are H.

2. The Ca2PO4Cl decomposition method according to claim 1, characterized in that: Ca2PO4Cl is prepared by mixing waste LFP positive electrode materials with calcium chloride and sodium salt, roasting, and water immersion, followed by solid-liquid separation to obtain Ca2PO4Cl.

3. The Ca2PO4Cl decomposition method according to claim 1, characterized in that: The alcohol solvent includes C1-C4 alcohols; preferably at least one of methanol and ethanol.

4. The Ca2PO4Cl decomposition method according to claim 1, characterized in that: The liquid-to-solid ratio of the alcohol solvent and Ca2PO4Cl is 10-40 mL / g.

5. The Ca2PO4Cl decomposition method according to claim 1, characterized in that: The temperature of the solvent thermal modification treatment is 100 to 200°C, preferably 120 to 180°C; Preferably, the solvent thermal modification treatment time is 1 to 10 hours.

6. The Ca2PO4Cl decomposition method according to claim 1, characterized in that: In the auxiliary agent of formula 1, R1 to R3 are methyl, ethyl or isopropyl.

7. The Ca2PO4Cl decomposition method according to claim 1, characterized in that: The separation liquid also includes an alcohol solvent; Preferably, the weight ratio of the auxiliary agent of formula 1 to the modified material is 1.5 to 3:1; preferably 2 to 2.5:

1.

8. The Ca2PO4Cl decomposition method according to claim 1, characterized in that: The temperature of the protonation treatment is 35 to 65°C; Preferably, the pH during the protonation treatment is controlled at 1 to 3; Preferably, the protonation treatment time is 0.15 to 2 h; preferably 0.5 to 1 h.

9. A method for resource utilization of Ca2PO4ClCa / P, characterized in that: The Ca2PO4Cl decomposition method according to any one of claims 1 to 8 is used to perform solvent thermal modification and protonation treatment on Ca2PO4Cl to obtain a treatment product of phosphoric acid and calcium chloride; the treatment product is low-temperature crystallized at 0 to 10°C to obtain a calcium chloride product and a crystallization mother liquor enriched with phosphoric acid.

10. The Ca2PO4ClCa / P resource utilization method according to claim 9, characterized in that: The crystallization mother liquor is extracted with soft water to obtain a phosphoric acid solution.

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