A method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling treatment

Abstract

The present invention relates to the technical field of iron phosphate, and in particular to a method for preparing high-quality iron phosphate by improving calcination conditions and ball milling. The present application discloses a method for preparing high-quality iron phosphate by improving calcination conditions and ball milling, comprising the following steps: preparing dihydrate iron phosphate powder; fully mixing the dihydrate iron phosphate powder and a flux, and sequentially performing flash evaporation and calcination to obtain calcined iron phosphate; ball milling the calcined iron phosphate, and washing and drying the ball-milled iron phosphate to obtain a finished iron phosphate product. The method for preparing high-quality iron phosphate by improving calcination conditions and ball milling described in the present application promotes crystallization and growth between reactants at high temperature by adding a flux during the solid-phase reaction process, reduces the reaction temperature and time, and improves the completeness of the reaction and the uniformity of the product.

Description

Technical Field

[0001] The invention relates to the technical field of ferric phosphate, in particular to a method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling treatment. Background Art

[0002] Ferric phosphate is an important electrode material with a wide range of applications in electrochemical energy storage, catalysts, and other fields. However, traditional methods for preparing ferric phosphate have problems such as coarse grains, uneven particle distribution, and unstable surface properties, which affect its application performance. In the prior art, the calcination conditions and ball milling process have a significant impact on the preparation of ferric phosphate, directly affecting the purity and quality of the product. Therefore, how to optimize the calcination conditions and ball milling process to improve the purity and quality of the product has become a research hotspot in this field. Summary of the Invention

[0003] In order to overcome the shortcomings of the existing technology, the present invention provides a method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling treatment. By adding a flux during the solid-phase reaction, crystallization and growth between the reactants are promoted at high temperatures, the reaction temperature and time are reduced, and the reaction completeness and product uniformity are improved.

[0004] The technical solution adopted by the present invention to solve its technical problem is:

[0005] A method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling treatment comprises the following steps:

[0006] Step 1: Preparation of ferric phosphate dihydrate powder

[0007] The reaction raw materials are mixed and reacted to obtain a primary reaction solution. After the reaction is completed, the primary reaction solution is aged and dried to obtain ferric phosphate dihydrate powder.

[0008] Step 2: Calcination

[0009] The ferric phosphate dihydrate powder and the flux are fully mixed, and then flash evaporated and calcined to obtain calcined ferric phosphate;

[0010] Step 3: Ball milling

[0011] The calcined ferric phosphate is ball-milled, and the ball-milled ferric phosphate is washed with water and dried to obtain a finished ferric phosphate product.

[0012] As a preferred solution, in step 2, the flux is sodium carbonate.

[0013] As a preferred solution, in step 2, the feed ratio of the ferric phosphate dihydrate powder and the flux is calculated by mass, ferric phosphate dihydrate powder: flux = 1:0.001-0.015.

[0014] As a preferred solution, in step 2, the flash evaporation treatment is carried out at a temperature of 200-230°C.

[0015] As a preferred solution, in step 2, the calcination treatment is to enter a rotary kiln for step-by-step temperature-controlled calcination.

[0016] As a more preferred solution, the step-by-step temperature-controlled calcination process is to carry out calcination in the first calcination zone to the sixth calcination zone;

[0017] The temperature during calcination in the primary calcination zone and the secondary calcination zone is controlled at 340-510℃;

[0018] The temperature is maintained at 680°C during calcination in the third, fourth and fifth calcination zones;

[0019] During calcination in the sixth calcination zone, the temperature is maintained at 500°C;

[0020] The step-by-step temperature control calcination process takes 2-3 hours.

[0021] As a preferred solution, in step three, the ball milling treatment is performed using a ball mill, and the ball milling stone of the ball mill is a zirconia ball milling stone or an alumina ball milling stone.

[0022] As a preferred solution, in step three, the ball milling speed is controlled at 500-700 rpm.

[0023] As a preferred solution, in step three, the diameter of the ball mill is 0.8 mm.

[0024] As a more preferred solution, in step three, the weight ratio of the ball mill stone to the calcined ferric phosphate is 1:1.0-1.5.

[0025] The beneficial effects of the present invention are:

[0026] 1. This application improves the calcination conditions and uses a rotary kiln for step-by-step temperature control calcination, which shortens the time compared to traditional drying and calcination, reducing the overall drying and calcination time of the product from 4-5h to 2-3h, thereby improving the drying speed and production efficiency; by improving the ball milling process, the prepared iron phosphate has a narrow particle size distribution and uniform morphology.

[0027] 2. This application promotes crystallization and growth between reactants at high temperatures by adding flux during the solid-phase reaction process, reduces reaction temperature and time, and improves reaction completeness and product uniformity.

[0028] 3. The present application ball-mills the solid-phase reaction product containing flux, crushes it into fine particles under the action of mechanical force, and smoothes its surface under the action of friction, thereby controlling the particle size distribution and morphology of the product and improving its uniformity.

[0029] 4. This application improves the purity and stability of the product by washing and drying the product after ball milling, dissolving the flux remaining on the surface in the aqueous solution, and removing excess water during the drying process. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention will be further described below with reference to the accompanying drawings and examples.

[0031] Figure 1 This is a SEM image of the finished ferric phosphate product prepared in Example 1 of the present application;

[0032] Figure 2 This is the XRD pattern of the finished iron phosphate product prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0033] In order to facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the embodiments. The contents mentioned in the embodiments are not intended to limit the present invention.

[0034] As used herein, "and / or" includes the term of any and all combinations of one or more of the associated listed items. The terms used herein are only used to describe specific embodiments and are not intended to limit the invention. As used herein, the singular forms "a", "an", "an" and "the" are also intended to include the plural forms, unless the context clearly indicates otherwise. It is further understood that "including", when used in this specification, specifies the stated features, integers, steps, operations, elements and / or components, but does not preclude the existence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0035] Unless otherwise defined, all terms (including 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. It is further understood that terms, such as those defined in commonly used dictionaries, are interpreted in accordance with their meanings in the context of the relevant art and are not idealized or overly formalized unless expressly defined herein.

[0036] The exemplary inventions described herein may suitably lack any one or more element limitations not specifically disclosed herein. Therefore, terms such as "comprises," "includes," "contains," and the like should be understood broadly and non-restrictively. In addition, the terminology used herein is used as a description, not a limitation, and it is unintentional to use these terminology expressions that do not include any equivalent characteristics, but only describe a portion of their characteristics, but various modifications are possible within the scope of the invention according to the rights. Therefore, although the present invention has been specifically disclosed through preferred embodiments and optional features, the modifications disclosed herein to embody the changes of the invention may be recorded by those skilled in the art, and such modifications and changes will be considered to be within the scope of the invention.

[0037] The raw materials or reagents used in the embodiments of the present invention and the comparative examples are all purchased from market mainstream manufacturers. The manufacturer or concentration is not specified. They are all analytically pure raw materials or reagents that can be routinely obtained. As long as the desired effect can be achieved, there are no particular restrictions. The reactor and rotary evaporator and other instruments used in the present embodiment are all purchased from market major manufacturers. As long as the desired effect can be achieved, there are no particular restrictions. In the present embodiment, if specific techniques or conditions are not specified, the technology or conditions described in the literature in this area or the product specifications are used.

[0038] In Examples 1-3 and Comparative Examples 1-3, the preparation of ferric phosphate dihydrate powder includes the following steps:

[0039] The various reaction raw materials are mixed and reacted to obtain a primary reaction solution; the primary reaction solution is aged and dried to obtain ferric phosphate dihydrate powder;

[0040] Specifically, the reaction raw materials include ferrous sulfate solution, MAP mixed solution (monoammonium phosphate, hydrogen peroxide), and ammonia solution; each reaction raw material is sequentially added dropwise with 83.7±1g / L ferrous sulfate as the base liquid and a MAP mixed solution containing 47.8±0.3g / L monoammonium phosphate and 3% hydrogen peroxide.

[0041] The ferrous sulfate and monoammonium phosphate in the reaction raw materials are added in a molar ratio of 1:1, and ammonia water with a mass concentration of 27% is added. The pH is adjusted to an end point pH of 2.0, and the reaction is carried out at a reaction temperature of 90-95° C. and a reaction time of 3.5 hours. After the reaction is completed, a primary reaction liquid is obtained; the primary reaction liquid is cooled to room temperature, aged for 2-3 days, and dried to obtain ferric phosphate dihydrate powder (moisture content required to be ≤1.0%).

[0042] Example 1

[0043] A method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling treatment comprises the following steps:

[0044] Step 1: Preparation of ferric phosphate dihydrate powder

[0045] Step 2: Calcination

[0046] Prepare ferric phosphate dihydrate powder and flux according to the mass ratio of ferric phosphate dihydrate powder: flux = 1:0.001; fully mix the ferric phosphate dihydrate powder and flux sodium carbonate, and sequentially perform flash evaporation and calcination to obtain calcined ferric phosphate;

[0047] The flash treatment temperature is 200-230℃;

[0048] After the flash evaporation treatment is completed, the product enters the rotary kiln for step-by-step temperature control calcination; the step-by-step temperature control calcination process is carried out in the first to sixth calcination zones;

[0049] The temperature during calcination in the primary calcination zone and the secondary calcination zone is controlled at 340°C;

[0050] The temperature is maintained at 680°C during calcination in the third, fourth and fifth calcination zones;

[0051] During calcination in the sixth calcination zone, the temperature is maintained at 500°C;

[0052] The entire step-by-step temperature control calcination process takes 3 hours.

[0053] Step 3: Ball milling

[0054] The calcined iron phosphate obtained in step 2 is ball milled; the ball milling process is performed using a ball mill, the ball milling stone of the ball mill is a zirconia ball milling stone or an alumina ball milling stone, the diameter of the ball milling stone is 0.8 mm, the weight ratio of the ball milling stone to the calcined iron phosphate is 1:1.0, the ball milling speed is controlled at 500-700 rpm, and the ball milling time is controlled at 15-20 minutes.

[0055] The ball-milled ferric phosphate is washed with water (using water 5 times the weight of the ferric phosphate) and dried (dried to a moisture content of less than 1%) to obtain a finished ferric phosphate product.

[0056] Example 2

[0057] A method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling treatment comprises the following steps:

[0058] Step 1: Preparation of ferric phosphate dihydrate powder

[0059] Step 2: Calcination

[0060] Prepare ferric phosphate dihydrate powder and flux according to the mass ratio of ferric phosphate dihydrate powder: flux = 1:0.012; fully mix the ferric phosphate dihydrate powder and flux sodium carbonate, and sequentially perform flash evaporation and calcination to obtain calcined ferric phosphate;

[0061] The flash treatment temperature is 200-230℃;

[0062] After the flash evaporation treatment is completed, the product enters the rotary kiln for step-by-step temperature control calcination; the step-by-step temperature control calcination process is carried out in the first to sixth calcination zones;

[0063] The temperature during calcination in the primary calcination zone and the secondary calcination zone is controlled at 510°C;

[0064] The temperature is maintained at 680°C during calcination in the third, fourth and fifth calcination zones;

[0065] During calcination in the sixth calcination zone, the temperature is maintained at 500°C;

[0066] The entire step-by-step temperature control calcination process takes 2 hours.

[0067] Step 3: Ball milling

[0068] The calcined iron phosphate obtained in step 2 is ball-milled; the ball milling process is performed using a ball mill, the ball milling stone of the ball mill is a zirconia ball milling stone or an alumina ball milling stone, the diameter of the ball milling stone is 0.8 mm, the weight ratio of the ball milling stone to the calcined iron phosphate is 1:1.5, the ball milling speed is controlled at 500-700 rpm, and the ball milling time is controlled at 25-30 minutes.

[0069] The ball-milled ferric phosphate is washed with water (using water 10 times the weight of the ferric phosphate) and dried (dried to a moisture content of less than 1%) to obtain a finished ferric phosphate product.

[0070] Example 3

[0071] A method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling treatment comprises the following steps:

[0072] Step 1: Preparation of ferric phosphate dihydrate powder

[0073] Step 2: Calcination

[0074] Prepare ferric phosphate dihydrate powder and flux according to the mass ratio of ferric phosphate dihydrate powder: flux = 1:0.015; fully mix the ferric phosphate dihydrate powder and flux sodium carbonate, and sequentially perform flash evaporation and calcination to obtain calcined ferric phosphate;

[0075] The flash treatment temperature is 200-230℃;

[0076] After the flash evaporation treatment is completed, the product enters the rotary kiln for step-by-step temperature control calcination; the step-by-step temperature control calcination process is carried out in the first to sixth calcination zones;

[0077] The temperature during calcination in the primary calcination zone and the secondary calcination zone is controlled at 450°C;

[0078] The temperature is maintained at 680°C during calcination in the third, fourth and fifth calcination zones;

[0079] During calcination in the sixth calcination zone, the temperature is maintained at 500°C;

[0080] The entire step-by-step temperature-controlled calcination process takes 2.5 hours.

[0081] Step 3: Ball milling

[0082] The calcined iron phosphate obtained in step 2 is ball-milled; the ball milling process is performed using a ball mill, the ball milling stone of the ball mill is a zirconia ball milling stone or an alumina ball milling stone, the diameter of the ball milling stone is 0.8 mm, the weight ratio of the ball milling stone to the calcined iron phosphate is 1:1.2, the ball milling speed is controlled at 500-700 rpm, and the ball milling time is controlled at 20-25 minutes.

[0083] The ball-milled ferric phosphate is washed with water (using water 8 times the weight of the ferric phosphate) and dried (dried to a moisture content of less than 1%) to obtain a finished ferric phosphate product.

[0084] Comparative Example 1

[0085] The ferric phosphate dihydrate powder prepared in step 1 of Example 1 was calcined in a muffle furnace with step-by-step temperature control (the heating and holding time were the same as in Example 1). The calcined ferric phosphate was then crushed in a jet mill (mesh size was 500 mesh) to obtain a powdery ferric phosphate product.

[0086] Comparative Example 2

[0087] The ferric phosphate dihydrate powder prepared in step 1 of Example 1 was calcined in a steel belt furnace with step-by-step temperature control (the temperature rise and the holding time were the same as in Example 1). The calcined ferric phosphate was then crushed in a jet mill (mesh size was 500 mesh) to obtain a powdery ferric phosphate product.

[0088] Comparative Example 3

[0089] No flux was added in step 2, and the other processes were the same as those in Example 1.

[0090] The finished ferric phosphate powders prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance tests, including scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests, to detect performance indicators such as product morphology and grain size. Some performance data are summarized in Table 1 below.

[0091] Table 1

[0092]

[0093]

[0094] Table 1 shows that the finished ferric phosphate products prepared in Examples 1-3 of the present application exhibit relatively concentrated product distribution, excellent particle size uniformity, high product yield, and a short calcination time, eliminating the need for separate, time-consuming cooling. Furthermore, the materials are uniformly sintered and circulated in the rotary kiln. Among them, the product obtained in Example 2 exhibits the highest quality, indicating that the addition of an appropriate amount of flux can improve product uniformity.

[0095] At the same time from Figure 1-Figure 2 It can be seen that the nano-scale iron phosphate prepared in Example 1 has fine particles, is porous, has a good peak shape and is free of impurity peaks, while in Comparative Example 1, the calcination treatment is carried out in a muffle furnace, and Comparative Example 2 is calcined in a steel belt furnace. The muffle furnace and the steel belt furnace cannot be dynamically heated, which will cause the iron phosphate to be sintered unevenly, and is prone to over-burning or incomplete sintering. It can be seen from Table 1 that the finished iron phosphate products prepared by step-by-step temperature control calcination in the rotary kiln of Examples 1-3 are better than Comparative Example 1 and Comparative Example 2 in various indicators. The particle size distribution of the product obtained after ball milling in the later pulverization process is also more concentrated, and the product is more uniform. Comparative Example 3 does not add a flux, and the product obtained has a lower specific surface area and a larger discreteness, which shows that the addition of a flux promotes crystallization and growth between the reactants and improves the uniformity of the product.

[0096] The above embodiments are preferred implementation schemes of the present invention. In addition, the present invention can also be implemented in other ways. Any obvious replacement without departing from the concept of the present invention is within the scope of protection of the present invention.

Claims

1. A method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling treatment, characterized in that: The following steps are involved: Step 1: Preparation of ferric phosphate dihydrate powder The reaction raw materials are mixed and reacted to obtain a primary reaction solution, and the primary reaction solution is obtained after the reaction is completed; the primary reaction solution is aged and dried to obtain ferric phosphate dihydrate powder; the reaction raw materials include ferrous sulfate solution, MAP mixed solution, and ammonia solution; the MAP mixed solution includes monoammonium phosphate and hydrogen peroxide; the reaction raw materials are sequentially added dropwise with 83.7±1g / L ferrous sulfate as the base solution, and the MAP mixed solution containing 47.8±0.3g / L monoammonium phosphate and 3% hydrogen peroxide is added; Step 2: Calcination The ferric phosphate dihydrate powder and the flux are fully mixed, and then flash evaporated and calcined to obtain calcined ferric phosphate; In step 2, the flux is sodium carbonate; In step 2, the calcination process is to enter the rotary kiln and perform step-by-step temperature control calcination; The step-by-step temperature control calcination process is to carry out calcination in the first to sixth calcination zones; The temperature during calcination in the primary calcination zone and the secondary calcination zone is controlled at 340-510℃; The temperature is maintained at 680°C during calcination in the third, fourth and fifth calcination zones; During calcination in the sixth calcination zone, the temperature is maintained at 500°C; The calcination process with step-by-step temperature control takes 2-3 hours; Step 3: Ball milling The calcined ferric phosphate is ball-milled, and the ball-milled ferric phosphate is washed and dried to obtain a finished ferric phosphate product; In step three, the ball milling treatment is performed using a ball mill, and the ball milling stone of the ball mill is a zirconia ball milling stone or an alumina ball milling stone.

2. The method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling according to claim 1, characterized in that: In step 2, the feed ratio of the ferric phosphate dihydrate powder and the flux is calculated based on mass, ferric phosphate dihydrate powder: flux = 1:0.001-0.

015.

3. The method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling according to claim 1, characterized in that: In step 2, the flash evaporation temperature is 200-230°C.

4. The method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling according to claim 1, characterized in that: In step three, the ball milling speed is controlled at 500-700 rpm during the ball milling process.

5. The method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling according to claim 1, characterized in that: In step 3, the diameter of the ball milling stone is 0.8 mm.

6. The method for preparing high-quality ferric phosphate by improving calcination conditions and ball milling according to claim 1, characterized in that: In step 3, the weight ratio of the ball mill stone to the calcined ferric phosphate is 1:1.0-1.5.

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