A method for recycling binder of waste lithium battery negative electrode material

Abstract

The present invention belongs to the technical field of recycling and utilizing waste lithium batteries, and specifically relates to a method for recovering negative electrode binders from waste lithium batteries. The method comprises: treating the negative electrode material including the negative electrode binder separated from the waste lithium batteries with a solvent, filtering the separated negative electrode current collector with a filter, and obtaining a mixed solution I containing the negative electrode binder and negative electrode powder; performing solid-liquid separation to obtain a mixed solution II containing the negative electrode powder and the negative electrode binder; recovering the solvent by distillation to obtain a mixed solution III; adding a precipitating agent I for precipitation; and performing solid-liquid separation to obtain a mixed solution IV containing carboxylated styrene-butadiene rubber and carboxymethyl cellulose; and further adding a precipitating agent II for precipitation to obtain carboxymethyl cellulose. The method of the present invention has high recovery efficiency and effectively separates the two main components of the negative electrode binder, sodium carboxymethyl cellulose and carboxylated styrene-butadiene rubber, to avoid the generation of pollutants from the pyrolysis of the negative electrode binder during pyrolysis, thereby reducing resource waste and being more environmentally friendly.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling waste lithium batteries, and particularly relates to a method for recycling a binder of a negative electrode material of waste lithium batteries. Background Art

[0002] Against the backdrop of "carbon peak and carbon neutrality," the lithium battery industry has experienced rapid development. Lithium-ion power batteries are a core component of new energy, but the number of scrapped lithium batteries is also increasing (Patent No.: CN 117393749 A). Lithium batteries are typically composed of a positive electrode material, a negative electrode material, an electrolyte, and a separator (Patent No.: CN 117488080 A). The negative electrode material includes negative electrode graphite powder, a negative electrode binder, and a negative electrode current collector. The properties of the binder not only help to increase the energy density of lithium batteries but also significantly reduce the battery's internal resistance, playing a significant role in improving lithium battery performance (Patent No.: CN117563557A). The combination of sodium carboxymethyl cellulose, which has a dispersing effect on negative electrode graphite powder and conductive additives, and carboxylated styrene-butadiene rubber, a flexible material with excellent bonding properties, complement each other when used as a negative electrode binder for lithium batteries. Both are indispensable and are the result of long-term practical experience in the lithium battery industry.

[0003] However, the presence of negative electrode binders makes it difficult to separate the negative electrode powder from the negative electrode collector during the recycling process of waste lithium battery negative electrode materials. The stripping of waste lithium ion battery negative electrode powder and negative electrode collector copper foil is the key to achieving efficient recycling of negative electrode materials. It is of great significance and is also a very challenging task. If only the conventional friction de-powdering method is adopted, when recycling waste lithium battery negative electrode materials, the copper content in the separated negative electrode powder seriously exceeds the standard. It is necessary to further remove copper by acidity and other methods to achieve effective recycling of negative electrode powder, and wastewater that needs further treatment will still be produced. At present, the main method for achieving the stripping of waste lithium ion battery negative electrode materials and negative electrode collector copper foil is the high-temperature calcination method. The binder remains in the negative electrode powder after high-temperature pyrolysis and carbonization (CN109216822A). However, the disadvantage of the high-temperature calcination method is that toxic gases will be produced during the combustion process, polluting the environment.

[0004] Therefore, it is necessary to seek a method with simple process and low cost to recover the two main components of negative electrode binder, sodium carboxymethyl cellulose and carboxylated styrene-butadiene rubber, and to effectively separate them. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for recycling the binder of the negative electrode material of waste lithium batteries, which has a short process flow, is less time-consuming, and is easy to implement.

[0006] The technical solutions adopted are:

[0007] The steps include:

[0008] (1) disassembling waste lithium batteries in an inert atmosphere to separate negative electrode materials including negative electrode powder, negative electrode current collector, and negative electrode binder; wherein the negative electrode binder comprises carboxylated styrene-butadiene rubber and carboxymethyl cellulose;

[0009] (2) adding a solvent to the negative electrode material obtained in step (1), dissolving the negative electrode binder after treatment, so that the negative electrode powder and the negative electrode current collector are effectively separated, filtering through a filter to obtain a mixed solution I containing the negative electrode binder, the negative electrode powder and the solvent; and drying the material on the filter to obtain the negative electrode current collector;

[0010] (3) subjecting the mixed solution I obtained in step (2) to solid-liquid separation to obtain a solid material I and a mixed solution II, and drying the solid material I to obtain a negative electrode powder; wherein the mixed solution II comprises a negative electrode binder and a solvent;

[0011] (4) distilling the mixed solution II obtained in step (3) to recover the solvent to obtain a mixed solution III, wherein the mixed solution III includes a negative electrode binder carboxylated styrene-butadiene rubber and sodium carboxymethyl cellulose and a residual solvent;

[0012] (5) adding a precipitating agent I to the mixed solution III obtained in step (4) to precipitate, and then performing solid-liquid separation to obtain a solid substance II and a mixed solution IV, wherein the solid substance II is dried to obtain carboxylated styrene-butadiene rubber, and the mixed solution IV comprises sodium carboxymethyl cellulose, the precipitating agent I, and the residual solvent;

[0013] (6) adding a precipitating agent II to the mixed solution IV obtained in step (5) to precipitate, and then performing solid-liquid separation to obtain a solid material III and a mixed solution V, wherein the solid material III is dried to obtain carboxymethyl cellulose, and the mixed solution V comprises the precipitating agent I, the precipitating agent II, and the residual solvent;

[0014] (7) treating the mixed solution V obtained in step (6) to recover the precipitation agent II, the residual solvent and the precipitation agent I.

[0015] Preferably, in the step (2), the solvent is at least one of benzene, toluene, xylene, hexane, cyclohexane, isooctane, ether, ethylene glycol dimethyl ether, petroleum ether, methyl formate, methyl acetate, ethyl formate, ethyl acetate, propyl acetate, ethyl propionate, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dichloromethane, chloroform, tetrachloromethane, dichloroethane, dichloroethylene, trichloroethylene, tetrachloroethylene, acetonitrile, acetone, tetrahydrofuran, water, methanol, ethanol, propanol, and isopropanol, and the mass ratio of the solvent to the negative electrode material of the waste lithium battery is 2 to 8:1.

[0016] Preferably, in step (2), the treatment refers to at least one of soaking, standing, shaking, stirring, hydrothermal, solvent thermal, and ultrasonic treatment, with a treatment temperature of 10 to 150° C. and a treatment time of 0.1 to 48 hours;

[0017] As a further preference, the treatment temperature is 20-50° C., and the treatment time is 0.1-3 h.

[0018] Preferably, in step (2), filtering is performed using a large-pore filter, and the filter screen has a pore size of 4 to 50 meshes.

[0019] Preferably, in step (4), the distillation is one of atmospheric distillation and reduced pressure distillation, the distillation temperature is 30 to 210° C., and the pressure is 0.1 Pa to 100 kPa;

[0020] As a further preference, the temperature is 30-90°C.

[0021] Preferably, in the step (5), the precipitating agent I is at least one of sodium fluoride, sodium chloride, sodium bromide, sodium iodide, sodium sulfate, sodium bisulfate, sodium sulfide, sodium hydrosulfide, sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, sodium nitrate, sodium citrate, sodium carbonate, sodium bicarbonate, ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, ammonium sulfate, ammonium bisulfate, ammonium sulfide, ammonium hydrosulfide, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium pyrophosphate, ammonium citrate, ammonium carbonate, ammonium bicarbonate, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, potassium sulfate, potassium bisulfate, potassium sulfide, potassium hydrosulfide, potassium phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, potassium pyrophosphate, potassium nitrate, potassium citrate, potassium carbonate, potassium bicarbonate, magnesium chloride, magnesium bromide, magnesium iodide, magnesium sulfate, magnesium nitrate, and aqueous solutions thereof;

[0022] Wherein, the mass ratio of the precipitating agent I to the mixed solution III is 0.001 to 3:1;

[0023] As a further preference, the mass ratio of the precipitating agent I to the mixed solution III is 0.01-0.3:1.

[0024] Preferably, in step (6), the precipitating agent II is at least one of benzoic acid, benzenesulfonic acid, phenol, nitric acid, hydrogen chloride, hydrogen bromide, hydrogen iodide, carbon dioxide, sulfuric acid, sulfurous acid, hydrogen sulfide, formic acid, acetic acid, propionic acid, oxalic acid, citric acid, perchloric acid, permanganic acid, selenic acid, phosphoric acid, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium bisulfate, potassium bisulfate, and their aqueous solutions.

[0025] Preferably, the mass ratio of the precipitation agent II to the mixed solution IV is 0.00001 to 0.1:1;

[0026] As a further preference, the mass ratio of the precipitation agent II to the mixed liquid IV is 0.00001 to 0.01:1.

[0027] Preferably, in step (7), the treatment refers to at least one of distillation, volatilization, evaporation, desalination, crystallization, precipitation, recrystallization, membrane separation, washing, filtration, neutralization, and acidification.

[0028] Preferably, the solid-liquid separation adopts at least one of sedimentation, filtration, membrane filtration, filter press, suction filtration, centrifugation, electrophoresis, crystallization, and spray drying.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The method of the present invention is suitable for effectively separating and recovering sodium carboxymethyl cellulose and carboxyl styrene-butadiene rubber negative electrode binders in negative electrode materials of waste lithium batteries such as waste lithium iron phosphate batteries, waste lithium cobalt oxide batteries, waste lithium manganese oxide batteries, waste nickel cobalt manganese oxide batteries, waste lithium titanate batteries, and waste ternary lithium batteries. The method also includes the recovery of negative electrode powder, the recovery of negative electrode current collector copper foil, and the recycling of solvents and precipitation agents.

[0031] The present invention adopts a solvent to dissolve the negative electrode binder, so that the negative electrode material is effectively separated from the negative electrode current collector sheet. Compared with the traditional pyrolysis method, it avoids the generation of pollutants by the pyrolysis of the negative electrode binder during the pyrolysis process, which is more environmentally friendly and safe; and it can maintain the molecular structure of the negative electrode binder, providing the prerequisite for the subsequent recovery of the negative electrode binder.

[0032] Compared with traditional friction de-powdering processes, this method significantly reduces the negative electrode binder and copper content in the recovered negative electrode powder, thereby improving the quality and value of the recovered negative electrode powder. The recovered negative electrode powder can be used as a negative electrode material for lithium batteries.

[0033] The present invention not only effectively recycles the negative electrode binder in the negative electrode material of waste lithium batteries, but also effectively separates the two main components of the negative electrode binder, namely sodium carboxymethyl cellulose and carboxy styrene butadiene rubber, thereby providing a foundation for the subsequent high-value utilization of sodium carboxymethyl cellulose and carboxy styrene butadiene rubber.

[0034] The carboxymethyl cellulose and carboxylated styrene-butadiene rubber recovered by the present invention can be directly reused as a negative electrode binder for lithium batteries, and can also be used as an anti-reprecipitation agent and thickener in cosmetics, a sizing agent in the printing and dyeing industry, and a paper smoothing agent and sizing agent in the papermaking industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 The present invention discloses a flow chart of a method for recycling a binder of a negative electrode material of waste lithium batteries. DETAILED DESCRIPTION

[0036] The accompanying drawings are for illustrative purposes only; in order to make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for the purpose of explaining the present invention and are not intended to limit the present invention.

[0037] Example 1

[0038] like Figure 1 As shown, a method for recycling a binder of a negative electrode material of a waste lithium battery comprises the following steps:

[0039] (1) Dismantling waste lithium iron phosphate square soft-pack batteries in an inert atmosphere to separate the negative electrode material containing negative electrode powder, negative electrode current collector, and negative electrode binder carboxyl styrene butadiene rubber and carboxymethyl cellulose;

[0040] (2) adding methanol, acetonitrile and tetrahydrofuran in a ratio of 1:1:1 to the negative electrode material obtained in step (1), with the mass ratio of the solvent to the negative electrode material being 5:1, and ultrasonicating for 0.5 h at a temperature of 30° C. to obtain a mixture I, which was filtered through a filter with a pore size of 20 mesh to obtain a mixed solution I; the material on the filter was dried to obtain a negative electrode current collector; the mixed solution I comprises a negative electrode binder, a negative electrode powder and a solvent;

[0041] (3) Centrifuging the mixed solution I obtained in step (2) at 10,000 rpm for 15 minutes to obtain a solid I and a mixed solution II; the solid I is dried to obtain a negative electrode powder; the mixed solution II includes a negative electrode binder and a solvent;

[0042] (4) distilling the mixed solution II obtained in step (3) at 0.04 MPa and 30° C. for 1 h, recovering the solvents methanol, acetonitrile and tetrahydrofuran, to obtain a mixed solution III comprising the negative electrode binder carboxylated styrene-butadiene rubber and sodium carboxymethyl cellulose and the residual solvent;

[0043] (5) adding a precipitating agent I (sodium sulfate) to the mixed solution III obtained in step (4) at a mass ratio of precipitating agent I to mixed solution III of 0.02:1, and centrifuging at 10,000 rpm for 15 minutes after precipitation for 0.5 hours to obtain a solid II and a mixed solution IV. The solid II was dried at 100° C. for 1 hour to obtain carboxylated styrene-butadiene rubber. The mixed solution IV included sodium carboxymethyl cellulose, precipitating agent I, and residual solvent.

[0044] (6) Adding precipitation agent II, i.e., 10% sulfuric acid solution, to the mixed solution IV obtained in step (5), the mass ratio of precipitation agent II to mixed solution IV being 10 -5 : 1, after precipitation for 1 hour, centrifugation at 10000 rpm for 15 minutes to obtain solid III and mixed solution V, solid III is dried at 120 ° C for 1 hour to obtain carboxymethyl cellulose, mixed solution V includes precipitation agent I, precipitation agent II and residual solvent;

[0045] (7) The mixed solution V obtained in step (6) was subjected to reduced pressure distillation at 0.04 MPa and 37° C. for 0.5 h to recover the residual solvent and precipitating agent II (10% sulfuric acid solution), and then filtered. The filtrate was a sulfuric acid solution, and the solid was washed, recrystallized, and dried to obtain precipitating agent I, i.e., sodium sulfate.

[0046] Example 2

[0047] A method for recycling a binder for a waste lithium battery negative electrode material, which differs from Example 1 in that:

[0048] The 1:1:1 ratio of methanol, acetonitrile and tetrahydrofuran in step (2) was replaced with 1:1:1 ratio of ethanol, acetonitrile and tetrahydrofuran.

[0049] The remaining parts not mentioned are the same as those in Example 1.

[0050] Example 3

[0051] A method for recycling a binder for a waste lithium battery negative electrode material, which differs from Example 1 in that:

[0052] The 1:1:1 ratio of methanol, acetonitrile and tetrahydrofuran in step (2) was replaced with 1:1:1 ratio of methanol, ethyl acetate and tetrahydrofuran.

[0053] The remaining parts not mentioned are the same as those in Example 1.

[0054] Example 4

[0055] A method for recycling a binder for a waste lithium battery negative electrode material, which differs from Example 1 in that:

[0056] The sodium sulfate in the precipitation agent I in step (5) is replaced by ammonium sulfate, and the mass ratio of the precipitation agent I to the mixed solution III is 0.06:1.

[0057] The remaining parts not mentioned are the same as those in Example 1.

[0058] Example 5

[0059] A method for recycling a binder for a waste lithium battery negative electrode material, which differs from Example 1 in that:

[0060] The 10% sulfuric acid solution of precipitation agent II in step (6) is replaced with 10% sodium bisulfate solution.

[0061] The remaining parts not mentioned are the same as those in Example 1.

[0062] Comparative Example 1

[0063] The traditional pyrolysis process is used to recycle waste lithium battery negative electrode materials. The specific steps are as follows: dismantling the waste lithium batteries to obtain waste lithium battery negative electrode materials; calcining the waste lithium battery negative electrode materials at 600°C in a nitrogen-protected tube furnace for 3 hours, ball milling for 1.5 hours, and sieving them through a 120-mesh screen to obtain recycled negative electrode powder and recycled negative electrode current collector.

[0064] Comparative Example 2

[0065] The conventional friction de-powdering process was used to recycle the negative electrode materials of waste lithium batteries. The difference from Comparative Example 1 was that the calcination at 600° C. for 3 h in a nitrogen-protected tubular furnace was omitted.

[0066] Table 1 Comparison of the recovery effect of waste lithium battery negative electrode materials between Examples 1-5 and Comparative Examples 1-2

[0067]

[0068]

[0069] From the comparison of the recovery effects of waste lithium battery negative electrode materials of Examples 1-5 and Comparative Examples 1-2 in Table 1, it can be seen that the method for recycling a binder for waste lithium battery negative electrode materials of the present invention can achieve high-efficiency recovery of negative electrode powder, negative electrode current collector, negative electrode binder carboxyl styrene butadiene rubber and carboxymethyl cellulose, while the traditional pyrolysis process and the traditional friction de-powdering process cannot recover the negative electrode binder carboxyl styrene butadiene rubber and carboxymethyl cellulose; and the content of metallic copper impurities in the negative electrode powder recovered by the present invention is much lower than that of the negative electrode powder recovered by the traditional pyrolysis process (Comparative Example 1) and the traditional friction de-powdering process (Comparative Example 2), thereby improving the quality and value of the recovered negative electrode powder.

[0070] Of course, the above description is not a limitation of the present invention, and the present invention is not limited to the above examples. Changes, modifications, additions or substitutions made by technicians in this technical field within the essential scope of the present invention should also fall within the scope of protection of the present invention.

Claims

1. A method for recycling a binder of anode materials of waste lithium batteries, characterized in that: The steps include: (1) disassembling waste lithium batteries in an inert atmosphere to separate negative electrode materials including negative electrode powder, negative electrode current collector, and negative electrode binder; wherein the negative electrode binder comprises carboxylated styrene-butadiene rubber and carboxymethyl cellulose; (2) adding a solvent to the negative electrode material obtained in step (1), dissolving the negative electrode binder after treatment, so that the negative electrode powder and the negative electrode current collector are effectively separated, filtering through a filter to obtain a mixed solution I containing the negative electrode binder, the negative electrode powder and the solvent; and drying the material on the filter to obtain the negative electrode current collector; (3) subjecting the mixed solution I obtained in step (2) to solid-liquid separation to obtain a solid material I and a mixed solution II, and drying the solid material I to obtain a negative electrode powder; wherein the mixed solution II comprises a negative electrode binder and a solvent; (4) distilling the mixed solution II obtained in step (3) to recover the solvent to obtain a mixed solution III, wherein the mixed solution III includes carboxylated styrene-butadiene rubber, sodium carboxymethyl cellulose and residual solvent; (5) adding a precipitating agent I to the mixed solution III obtained in step (4) to precipitate, and then performing solid-liquid separation to obtain a solid substance II and a mixed solution IV, wherein the solid substance II is dried to obtain carboxylated styrene-butadiene rubber, and the mixed solution IV comprises sodium carboxymethyl cellulose, the precipitating agent I, and the residual solvent; (6) adding a precipitating agent II to the mixed solution IV obtained in step (5) to precipitate, and then performing solid-liquid separation to obtain a solid material III and a mixed solution V, wherein the solid material III is dried to obtain carboxymethyl cellulose, and the mixed solution V comprises the precipitating agent I, the precipitating agent II, and the residual solvent; (7) treating the mixed solution V obtained in step (6) to recover the precipitation agent II, the residual solvent and the precipitation agent I.

2. The method for recycling a binder for a negative electrode material of a waste lithium battery according to claim 1, characterized in that: In the step (2), the solvent is at least one of benzene, toluene, xylene, hexane, cyclohexane, isooctane, ether, ethylene glycol dimethyl ether, petroleum ether, methyl formate, methyl acetate, ethyl formate, ethyl acetate, propyl acetate, ethyl propionate, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, dichloromethane, chloroform, tetrachloromethane, dichloroethane, dichloroethylene, trichloroethylene, tetrachloroethylene, acetonitrile, acetone, tetrahydrofuran, water, methanol, ethanol, propanol, and isopropanol, and the mass ratio of the solvent to the negative electrode material of the waste lithium battery is 2 to 8:

1.

3. The method for recycling a binder for a negative electrode material of a waste lithium battery according to claim 1, characterized in that: In the step (2), the treatment refers to at least one of soaking, standing, shaking, stirring, hydrothermal, solvent thermal, and ultrasonic treatment, with a treatment temperature of 20 to 50° C. and a treatment time of 0.1 to 3 hours.

4. The method for recycling a binder for a negative electrode material of a waste lithium battery according to claim 1, characterized in that: In the step (2), the pore size of the filter screen is 4 to 50 meshes.

5. The method for recycling a binder for a negative electrode material of a waste lithium battery according to claim 1, characterized in that: In the step (4), the distillation is one of atmospheric distillation and reduced pressure distillation, the temperature is 30 to 90° C., and the pressure is 0.1 Pa to 100 kPa.

6. The method for recycling a binder for a negative electrode material of a waste lithium battery according to claim 1, characterized in that: In the step (5), the precipitating agent I is at least one of sodium fluoride, sodium chloride, sodium bromide, sodium iodide, sodium sulfate, sodium bisulfate, sodium sulfide, sodium hydrosulfide, sodium phosphate, sodium hydrogen phosphate, sodium dihydrogen phosphate, sodium pyrophosphate, sodium nitrate, sodium citrate, sodium carbonate, sodium bicarbonate, ammonium fluoride, ammonium chloride, ammonium bromide, ammonium iodide, ammonium sulfate, ammonium bisulfate, ammonium sulfide, ammonium hydrosulfide, ammonium phosphate, ammonium hydrogen phosphate, ammonium dihydrogen phosphate, ammonium pyrophosphate, ammonium citrate, ammonium carbonate, ammonium bicarbonate, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, potassium sulfate, potassium bisulfate, potassium sulfide, potassium hydrosulfide, potassium phosphate, potassium hydrogen phosphate, potassium dihydrogen phosphate, potassium pyrophosphate, potassium nitrate, potassium citrate, potassium carbonate, potassium bicarbonate, magnesium chloride, magnesium bromide, magnesium iodide, magnesium sulfate, magnesium nitrate, and aqueous solutions thereof, and the mass ratio of the precipitating agent I to the mixed solution III is 0.01 to 0.3:

1.

7. The method for recycling a binder for anode materials of waste lithium batteries according to claim 1, characterized in that: In the step (6), the precipitating agent II is at least one of benzoic acid, benzenesulfonic acid, phenol, nitric acid, hydrogen chloride, hydrogen bromide, hydrogen iodide, carbon dioxide, sulfuric acid, sulfurous acid, hydrogen sulfide, formic acid, acetic acid, propionic acid, oxalic acid, citric acid, perchloric acid, permanganic acid, selenic acid, phosphoric acid, sodium dihydrogen phosphate, potassium dihydrogen phosphate, sodium bisulfate, potassium bisulfate, and their aqueous solutions.

8. The method for recycling a binder for a negative electrode material of a waste lithium battery according to claim 7, characterized in that: The mass ratio of the precipitating agent II to the mixed liquid IV is 0.00001 to 0.01:

1.

9. The method for recycling a binder for a negative electrode material of a waste lithium battery according to claim 1, characterized in that: In the step (7), the treatment refers to at least one of distillation, volatilization, evaporation, desalination, crystallization, precipitation, recrystallization, membrane separation, washing, filtration, neutralization, and acidification.

10. The method for recycling a binder for a negative electrode material of a waste lithium battery according to claim 1, characterized in that: The solid-liquid separation adopts at least one of sedimentation, filtration, membrane filtration, filter press, suction filtration, centrifugation, electrophoresis, crystallization and spray drying.

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