阅读说明：本技术 一种利用磷石膏制备复合阻燃剂的方法 (Method for preparing composite flame retardant by using phosphogypsum ) 是由 徐韦洪 赵建波 刘晓惠 韦明志 肖玉方 朱东辉 李贵汶 朱国飞 张艳 于 2021-08-30 设计创作，主要内容包括：本发明提供一种利用磷石膏制备复合阻燃剂的方法,包括以下步骤：S1.生石膏颗粒制备；S2.浆料制备；S3.裹料；S4.过滤；S5.干燥；S6.低温放置；S7.循环处理；S8.成品。本发明采用在石膏颗粒外多次复合混合浆料的方法来制备复合阻燃剂,该方法不仅可以进一步的利用磷石膏,降低磷石膏堆存量,同时在不降低阻燃性的前提下,能有效降低阻燃剂成本；制得的复合阻燃剂外的包裹层受热时发生分解吸收燃烧物表面热量,降低它所填充的合成材料在火焰中的表面温度,同时释放出大量水分稀释燃物表面的氧气,分解生成的活性氧化物附着于可燃物表面又进一步阻止了燃烧的进行,其内部生石膏颗粒的温度不会过度升高并产生有害物质。(The invention provides a method for preparing a composite flame retardant by using phosphogypsum, which comprises the following steps: s1, preparing gypsum particles; s2, preparing slurry; s3, wrapping; s4, filtering; s5, drying; s6, placing at a low temperature; s7, circulating treatment; and S8, finishing the product. The composite flame retardant is prepared by compounding the mixed slurry outside the gypsum particles for multiple times, and the method not only can further utilize the phosphogypsum and reduce the stockpiling amount of the phosphogypsum, but also can effectively reduce the cost of the flame retardant on the premise of not reducing the flame retardance; the prepared coating layer outside the composite flame retardant is decomposed to absorb the surface heat of the combustion products when being heated, the surface temperature of the synthetic materials filled in the coating layer in the flame is reduced, simultaneously, a large amount of moisture is released to dilute the oxygen on the surface of the combustion products, the active oxides generated by decomposition are attached to the surface of the combustion products to further prevent the combustion, and the temperature of the gypsum particles in the coating layer is not excessively increased and harmful substances are generated.)

1. A method for preparing a composite flame retardant by using phosphogypsum is characterized by comprising the following steps:

s1, preparing gypsum particles: removing impurities from phosphogypsum, purifying to prepare raw gypsum powder, uniformly mixing the raw gypsum powder with water, and preparing raw gypsum particles with the particle size of 0.5-1.2 mm;

s2, preparing slurry: uniformly mixing magnesium hydroxide powder, one or two of aluminum hydroxide powder, clay powder and water according to the proportion of 10 (2-7) to 10-19 to prepare a slurry with fluidity;

s3, wrapping: immersing gypsum particles into slurry at 70-85 ℃ and standing for 10-25 seconds;

s4, filtering: filtering the slurry soaked with the gypsum particles in the step S3 to filter the slurry, wherein the particles coated with a layer of slurry are on the screen, and the slurry under the screen is collected and reserved for the next coating treatment;

s5, drying: drying the granules obtained by filtering the S4 in the air or at medium temperature;

s6, low-temperature placement: placing the dried granules in the S5 in a low-temperature refrigerating chamber for 30-60 minutes;

s7, cyclic treatment: circularly treating the granules obtained in the step S6 for 2-6 times according to the operation of the steps S3-S6 until the grain diameter of the granules reaches 1.5-2.5 mm;

s8, finished product: and (5) slowly heating the granules obtained in the step S7 to normal temperature to obtain the composite flame retardant.

2. The method for preparing the composite flame retardant by using the phosphogypsum as claimed in claim 1, is characterized in that: the gypsum particles in step S1 are spherical or cylindrical.

3. The method for preparing the composite flame retardant by using the phosphogypsum as claimed in claim 1, is characterized in that: in the step S2, the slurry is prepared by uniformly mixing magnesium hydroxide powder, clay powder and water according to the proportion of 10:5: 16.

4. The method for preparing the composite flame retardant by using the phosphogypsum as claimed in claim 1, is characterized in that: in the step S2, the slurry is prepared by uniformly mixing aluminum hydroxide powder, clay powder and water according to the ratio of 10:4: 15.

5. The method for preparing the composite flame retardant by using the phosphogypsum as claimed in claim 1, is characterized in that: in the step S2, the slurry is prepared by uniformly mixing the magnesium hydroxide and aluminum hydroxide mixed powder, clay powder and water according to the proportion of 10:7: 19; wherein, in the mixed powder of magnesium hydroxide and aluminum hydroxide, the ratio of magnesium hydroxide to aluminum hydroxide is 1 (1-3).

6. The method for preparing the composite flame retardant by using the phosphogypsum as claimed in claim 1, is characterized in that: in the step S5, the medium-temperature drying is drying under hot air at 85-95 ℃.

7. The method for preparing the composite flame retardant by using the phosphogypsum as claimed in claim 1, is characterized in that: the temperature of the low-temperature refrigerating chamber in the step S6 is-10 ℃ to-1 ℃.

8. The method for preparing the composite flame retardant by using the phosphogypsum according to any one of claims 1 to 7, which is characterized in that: the particle sizes of the magnesium hydroxide powder, the aluminum hydroxide powder and the clay powder are 200-600 meshes.

Technical Field

The invention relates to the technical field of flame retardant processing, in particular to a method for preparing a composite flame retardant by using phosphogypsum.

Background

Phosphogypsum is a solid waste in phosphate fertilizer industry, generally, 4.5-5.0 tons of phosphogypsum are generated every 1 ton of phosphoric acid, and 2.5-5.0 tons of phosphogypsum are discharged every 1 ton of diammonium phosphate. The annual emission of phosphogypsum in China is more than 7000 million tons, the utilization rate is only about 40 percent, and the current stockpiling amount exceeds 3 hundred million tons. The treatment and utilization of the phosphogypsum are one of the main problems to be urgently waited in the phosphorus chemical industry at present, become a bottleneck restricting the development of the Guizhou phosphorus chemical industry, develop and apply the phosphogypsum resource in multiple channels, and are effective ways for promoting the sustainable development of the phosphorus chemical industry in China. In order to improve the utilization rate of the phosphogypsum, the applicant and a scientific research institution in Guizhou province cooperate to reduce the storage amount of the phosphogypsum by processing the phosphogypsum into various PVC power pipes, communication pipes, various PE drainage and drainage pipes, road manhole covers, water grates and other products, but the consumption amount of the phosphogypsum is still difficult to quickly consume the storage amount, and the phosphogypsum is continuously generated along with the continuous extension of a phosphate fertilizer industry, so that more phosphogypsum utilization channels are still needed to be developed.

Disclosure of Invention

In order to solve the problems, the invention aims to provide a method for preparing a composite flame retardant by using phosphogypsum, which can further use the phosphogypsum to reduce the stockpiling amount of the phosphogypsum and effectively reduce the cost of the flame retardant on the premise of not reducing the flame retardance.

The purpose of the invention is realized by the following technical scheme:

a method for preparing a composite flame retardant by using phosphogypsum comprises the following steps:

s1, preparing gypsum particles: removing impurities from phosphogypsum, purifying to obtain gypsum powder, mixing the gypsum powder with water, and making into gypsum particles with particle size of 0.5-1.2 mm.

S2, preparing slurry: uniformly mixing magnesium hydroxide powder, one or two of aluminum hydroxide powder, clay powder and water according to the proportion of 10 (2-7) to 10-19 to prepare the slurry with fluidity.

S3, wrapping: the gypsum particles are immersed in the slurry at 70-85 ℃ for 10-25 seconds. The gypsum particles are wrapped (hung) with a layer of slurry, and the slurry contains clay, so that the magnesium hydroxide powder and one or two of the aluminum hydroxide powders can be well bonded and attached to the outside of the gypsum particles.

S4, filtering: and S3, filtering the slurry soaked with the gypsum particles to remove the slurry, wherein the particles coated with a layer of slurry are on the screen, and the slurry under the screen is collected and reserved for the next coating treatment.

S5, drying: and (4) drying the granules obtained by filtering the S4 in the air or at medium temperature.

S6, low-temperature placement: and (4) placing the dried granules in the step (S5) in a low-temperature refrigerating chamber for 30-60 minutes.

S7, cyclic treatment: and (4) circularly treating the granules obtained in the step S6 for 2-6 times according to the operation of the steps S3-S6 until the particle diameter of the granules reaches 1.5-2.5 mm.

S8, finished product: and (5) slowly heating the granules obtained in the step S7 to normal temperature to obtain the composite flame retardant.

Further, the gypsum particles are spherical or cylindrical in step S1.

Further, in step S2, the slurry is prepared by uniformly mixing magnesium hydroxide powder, clay powder and water according to a ratio of 10:5: 16.

Further, in step S2, the slurry is prepared by uniformly mixing aluminum hydroxide powder, clay powder and water according to the ratio of 10:4:15

Further, in the step S2, the slurry is prepared by uniformly mixing the magnesium hydroxide and aluminum hydroxide mixed powder, the clay powder and the water according to the ratio of 10:7: 19; wherein, in the mixed powder of magnesium hydroxide and aluminum hydroxide, the ratio of magnesium hydroxide to aluminum hydroxide is 1 (1-3).

Further, the medium-temperature drying in step S5 is drying under hot air at 85-95 ℃.

Further, the temperature of the low-temperature refrigerating chamber in the step S6 is-10 ℃ to-1 ℃.

Further, the particle sizes of the magnesium hydroxide powder, the aluminum hydroxide powder and the clay powder are 200-600 meshes.

The invention adopts a method of compounding the mixed slurry outside the gypsum particles for multiple times to prepare the composite flame retardant, and the method not only can further utilize the phosphogypsum and reduce the stockpiling amount of the phosphogypsum, but also can effectively reduce the cost of the flame retardant on the premise of not reducing the flame retardance. The composite flame retardant prepared by the invention is mainly used for polypropylene (PP), Polyethylene (PE) and the like, and not only can be used as a flame retardant but also can be used as a filler. The composite flame retardant is externally coated with a coating layer made of composite mixed slurry, and the coating layer is decomposed to absorb the surface heat of the combustion object when being heated, so that the surface temperature of the synthetic material filled in the coating layer in the flame is reduced, a large amount of water is released to dilute the oxygen on the surface of the combustion object, and the active oxide generated by decomposition is attached to the surface of the combustion object to further prevent the combustion from being carried out; the clay on the outer parcel layer of compound fire retardant can take place to warp under high temperature, and then form the through-hole of the inside gypsum granule of intercommunication compound fire retardant outside the parcel layer, the heat is got into the back by these through-holes, heat the gypsum granule, the inside binding water of gypsum granule becomes vapor release and goes out, further dilute the oxygen on thing surface of burning, these through-holes can also be synthetic material burning produced harmful gas and smog in a large number, eliminate smog when making the burning very fast stop, prevent to melt the drop. In addition, because the oxide generated after the heating of the wrapping layer outside the gypsum particles has certain heat insulation property, heat can only enter the interior from the through hole formed after the clay deforms, the temperature of the gypsum particles cannot be excessively increased to the degree of decomposing the calcium sulfate, and harmful substances cannot be generated.

Detailed Description

The following description of the embodiments of the present invention is provided for illustrative purposes, and other advantages and effects of the present invention will become apparent to those skilled in the art from the present disclosure.

In the description of the present invention, it is to be noted that, unless otherwise explicitly specified or limited, the terms "connected" and "connected" are to be interpreted broadly, e.g., as being fixed or detachable or integrally connected; can be mechanically or electrically connected; may be directly connected or indirectly connected through an intermediate. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.

After the gypsum is heated to 128 ℃, most of crystal water is lost and the gypsum becomes mature; heating to above 163 deg.C to completely lose crystal water; when the raw gypsum is heated to 800 ℃ or higher, calcium oxide and sulfur dioxide are decomposed, and if the temperature of the decomposition is lower in the presence of carbon, sulfur dioxide is a toxic pollutant gas, it is considered that the raw gypsum is used as a raw material for a flame retardant, and the following examples of the present application are obtained.

The first embodiment is as follows:

a method for preparing a composite flame retardant by using phosphogypsum comprises the following steps:

s1, preparing gypsum particles: removing impurities from phosphogypsum, purifying to obtain gypsum powder, mixing the gypsum powder with water, and making into spherical gypsum particles with particle size of 0.5-1.2mm and rough surface.

S2, preparing slurry: uniformly mixing magnesium hydroxide powder, clay powder and water according to the proportion of 10:5:16 to prepare the slurry with fluidity. The particle sizes of the magnesium hydroxide powder, the aluminum hydroxide powder and the clay powder are 200-600 meshes.

S3, wrapping: the gypsum particles were immersed in the slurry at 70-85 ℃ for 15 seconds. The gypsum particles are wrapped (hung) with a layer of slurry, and the slurry contains clay, so that the magnesium hydroxide powder and one or two of the aluminum hydroxide powders can be well bonded and attached to the outside of the gypsum particles. When the outer wrapping layer of the composite flame retardant is heated, because magnesium oxide generated after the outer wrapping layer of the gypsum particles is heated has certain heat insulation property, heat can only enter the interior of the clay deformation-formed through hole, the temperature of the gypsum particles can not be excessively increased to the degree of decomposing calcium sulfate, and harmful substances can not be generated.

S4, filtering: and S3, filtering the slurry soaked with the gypsum particles to remove the slurry, wherein the particles coated with a layer of slurry are on the screen, and the slurry under the screen is collected and reserved for the next coating treatment.

S5, drying: drying the granules obtained by filtering the S4 by hot air at 85-95 ℃.

S6, low-temperature placement: and (4) placing the dried granules in the S5 in a low-temperature refrigerating chamber at the temperature of-10 ℃ for 35 minutes. After the low-temperature particles are placed in the slurry at 70-85 ℃, the surface of the particles suddenly rises due to the temperature, and then cracks are formed on the surface of the particles, which is beneficial to the next process of wrapping (hanging).

S7, cyclic treatment: the pellets obtained in step S6 were treated in a cycle of 5 times in accordance with the operations of steps S3-S6 until the pellet size reached 1.8 mm.

S8, finished product: and (5) slowly heating the granules obtained in the step S7 to normal temperature to obtain the composite flame retardant.

Example two:

a method for preparing a composite flame retardant by using phosphogypsum comprises the following steps:

s1, preparing gypsum particles: removing impurities from phosphogypsum, purifying to obtain gypsum powder, mixing the gypsum powder with water, and making into spherical gypsum particles with particle size of 0.5-1.2mm and rough surface.

S2, preparing slurry: uniformly mixing aluminum hydroxide powder, clay powder and water according to the proportion of 10:4:15 to prepare the slurry with fluidity. The particle sizes of the magnesium hydroxide powder, the aluminum hydroxide powder and the clay powder are 200-600 meshes.

S3, wrapping: the gypsum particles were immersed in the slurry at 70-85 ℃ for 15 seconds. The gypsum particles are wrapped (hung) with a layer of slurry, and the slurry contains clay, so that the magnesium hydroxide powder and one or two of the aluminum hydroxide powders can be well bonded and attached to the outside of the gypsum particles. When the outer wrapping layer of the composite flame retardant is heated, because magnesium oxide generated after the outer wrapping layer of the gypsum particles is heated has certain heat insulation property, heat can only enter the interior of the clay deformation-formed through hole, the temperature of the gypsum particles can not be excessively increased to the degree of decomposing calcium sulfate, and harmful substances can not be generated.

S4, filtering: and S3, filtering the slurry soaked with the gypsum particles to remove the slurry, wherein the particles coated with a layer of slurry are on the screen, and the slurry under the screen is collected and reserved for the next coating treatment.

S5, drying: drying the granules obtained by filtering the S4 by hot air at 85-95 ℃.

S6, low-temperature placement: and (4) placing the dried granules in the S5 in a low-temperature refrigerating chamber at the temperature of-10 ℃ for 40 minutes. After the low-temperature particles are placed in the slurry at 70-85 ℃, the surface of the particles suddenly rises due to the temperature, and then cracks are formed on the surface of the particles, which is beneficial to the next process of wrapping (hanging).

S7, cyclic treatment: the pellets obtained in step S6 were treated in a cycle of 6 times in accordance with the operations of steps S3-S6 until the pellet size reached 2.0 mm.

S8, finished product: and (5) slowly heating the granules obtained in the step S7 to normal temperature to obtain the composite flame retardant.

Example three:

a method for preparing a composite flame retardant by using phosphogypsum comprises the following steps:

s1, preparing gypsum particles: removing impurities from phosphogypsum, purifying to obtain gypsum powder, mixing the gypsum powder with water, and making into spherical gypsum particles with particle size of 0.5-1.2mm and rough surface.

S2, preparing slurry: uniformly mixing the mixed powder of magnesium hydroxide and aluminum hydroxide, clay powder and water according to the proportion of 10:7:19 to prepare the slurry with fluidity. Wherein in the mixed powder of magnesium hydroxide and aluminum hydroxide, the ratio of magnesium hydroxide to aluminum hydroxide is 1 (1-3); the particle sizes of the magnesium hydroxide powder, the aluminum hydroxide powder and the clay powder are 200-600 meshes.

S3, wrapping: the gypsum particles were immersed in the slurry at 70-85 ℃ for 20 seconds. The gypsum particles are wrapped (hung) with a layer of slurry, and the slurry contains clay, so that the magnesium hydroxide powder and one or two of the aluminum hydroxide powders can be well bonded and attached to the outside of the gypsum particles. When the outer wrapping layer of the composite flame retardant is heated, because magnesium oxide generated after the outer wrapping layer of the gypsum particles is heated has certain heat insulation property, heat can only enter the interior of the clay deformation-formed through hole, the temperature of the gypsum particles can not be excessively increased to the degree of decomposing calcium sulfate, and harmful substances can not be generated.

S4, filtering: and S3, filtering the slurry soaked with the gypsum particles to remove the slurry, wherein the particles coated with a layer of slurry are on the screen, and the slurry under the screen is collected and reserved for the next coating treatment.

S5, drying: drying the granules obtained by filtering the S4 by hot air at 85-95 ℃.

S6, low-temperature placement: and (4) placing the dried granules in the S5 in a low-temperature refrigerating chamber at the temperature of-5 ℃ for 45 minutes. After the low-temperature particles are placed in the slurry at 70-85 ℃, the surface of the particles suddenly rises due to the temperature, and then cracks are formed on the surface of the particles, which is beneficial to the next process of wrapping (hanging).

S7, cyclic treatment: the pellets obtained in step S6 were treated in a cycle of 4 times in accordance with the operations of steps S3-S6 until the pellet size reached 1.6 mm.

S8, finished product: and (5) slowly heating the granules obtained in the step S7 to normal temperature to obtain the composite flame retardant.

It is to be noted that the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

The scope of the present invention is not limited to the technical solutions disclosed in the embodiments, and any modifications, equivalent substitutions, improvements, etc. made to the above embodiments according to the technical spirit of the present invention fall within the scope of the present invention.