Method for purifying and pulverizing attapulgite clay

Abstract

This invention discloses a method for purifying and pulverizing attapulgite clay. The method includes: (1) soaking attapulgite clay particles in acid solution for a certain period of time, followed by washing with water; (2) adding the attapulgite clay treated in step (1) and polymethyl methacrylate-polysiloxane block copolymer to an ethanol aqueous solution, ultrasonically stirring until homogeneous, allowing it to settle naturally for a certain period of time, then taking the upper suspension for filtration, drying, and pulverizing to obtain attapulgite powder. Compared with the traditional acid washing method, this invention can use dilute acid to obtain high-purity attapulgite, avoiding structural damage to attapulgite caused by concentrated acid.

Description

Technical Field

[0001] This invention relates to a method for purifying and grinding attapulgite clay. Background Technology

[0002] Attapulgite is a hydrous magnesium aluminum silicate clay mineral with a unique fibrous crystal structure. Due to its high specific surface area, strong adsorption capacity, ion exchange capacity, and biocompatibility, it is widely used in slow-release fertilizer coating agents, soil conditioners, functional additives for polymer materials, and environmentally friendly adsorbent materials. However, existing attapulgite purification and powdering technologies still face significant bottlenecks. 1. Traditional acid washing methods (such as concentrated hydrochloric acid and concentrated sulfuric acid treatment) can remove impurities, but concentrated acid can easily cause attapulgite crystals to dehydrate and collapse. If dilute acid is used, the impurity removal effect is poor.

[0003] 2. Conventional ball milling is difficult to achieve ultra-fine dissociation, and the particles are prone to agglomeration, resulting in a high bulk density of the product (>0.45g / cm³), which cannot meet the uniform dispersion required for slow-release fertilizer coating. Summary of the Invention

[0004] The purpose of this invention is to provide a method for purifying and pulverizing attapulgite clay.

[0005] A method for purifying and pulverizing attapulgite clay includes: (1) After soaking the attapulgite clay particles in acid for a certain period of time, they are washed with water; (2) Add the attapulgite clay and polymethyl methacrylate-polysiloxane block copolymer treated in step (1) to an ethanol aqueous solution, stir evenly with ultrasonication, and let it settle naturally for a certain period of time. Then take the upper suspension, filter, dry and crush it to obtain attapulgite powder.

[0006] Preferably, the acid solution is a nitric acid or hydrochloric acid solution with a concentration of 5-10 wt%. When attapulgite products are used in agricultural fertilizers, a nitric acid solution is preferred. This avoids the presence of residual chloride ions that can harm the soil, and the residual nitrate ions can provide nitrogen to crops.

[0007] More preferably, in step (1), the solid-liquid ratio of the attapulgite clay particles to the acid solution is 1:(1~3) g / mL.

[0008] Preferably, in step (1), the particle size of the attapulgite clay particles is 1~3 mm.

[0009] Preferably, in step (2), the amount of polymethyl methacrylate-polysiloxane block copolymer used is 1 to 3% of the mass of attapulgite clay.

[0010] Preferably, in step (2), the solid-liquid ratio of attapulgite clay to ethanol aqueous solution is 1:(1~3) g / mL.

[0011] Preferably, the concentration of the aqueous ethanol solution is 10~30 v.

[0012] Preferably, in step (2), the ultrasonic stirring time is 1-2 hours and the temperature is 70-90℃.

[0013] Preferably, in step (2), the natural settling time is 24 hours.

[0014] Preferably, in step (2), the dried attapulgite and pentaerythritol di(hexadecyl) phosphite are mixed and pulverized in a ball mill.

[0015] More preferably, the amount of pentaerythritol di(hexadecyl) phosphite used is 1 to 5 wt% of attapulgite.

[0016] Beneficial effects 1. This invention uses an ethanol / water system and a polymethyl methacrylate-polysiloxane block copolymer additive (whose main function is to adjust the surface charge of attapulgite and secondly to suspend it) to significantly improve the sedimentation and separation effect of attapulgite and impurities after pickling. This allows dilute acid to be used instead of concentrated acid in the initial pickling stage, avoiding excessive damage to the attapulgite structure during traditional pickling.

[0017] 2. In this invention, adding an appropriate amount of pentaerythritol di(hexadecyl) phosphite ester during ball milling can significantly improve the dissociation effect of attapulgite powder, thereby reducing the bulk density of the powder and improving the dispersibility of the product. Detailed Implementation

[0018] The technical solution of the present invention will be further described in detail below with reference to the embodiments.

[0019] Attapulgite clay (Linze County Fenjun Mining Co., Ltd.), with an attapulgite content of not less than 60%.

[0020] The polymethyl methacrylate-polysiloxane block copolymer (PMMA-PDMS) was purchased from Liyang Ruipu New Materials Co., Ltd.

[0021] Example 1 1. Purification: Crush 500g of attapulgite clay into small particles of 1-3 mm, then add 1L of 10wt% nitric acid solution, stir for 30 minutes, let stand for 24 hours, wash with water 2-3 times, and filter by pressure. Next, disperse the filter cake in 1L of 20% ethanol aqueous solution, add 10g of PMMA-PDMS, and then sonicate at 80 degrees Celsius for 1 hour. After natural sedimentation for 24 hours, take the supernatant, filter, and dry to obtain attapulgite (purity 98.8%), denoted as ATP-1.

[0022] 2. Powdering: Mix 3g of pentaerythritol di(hexadecyl) phosphite and 100g of ATP-1, add to a ball mill, and ball mill at 200 rpm for 20 minutes to obtain attapulgite powder (bulk density 0.21g / cm³). 3 Powder particle size D100 < 3 micrometers).

[0023] Comparative Example 1 500g of attapulgite clay was crushed into small particles of 1-3 mm, then 1L of 10wt% nitric acid solution was added. After stirring for 30 minutes, the mixture was allowed to stand for 24 hours, washed 2-3 times with water, and then filtered by pressure. The filter cake was then dispersed in 1L of 20% (v / v) ethanol aqueous solution and ultrasonically stirred at 80°C for 1 hour. After natural sedimentation for 24 hours, the supernatant was collected, filtered, and dried to obtain attapulgite (purity 81.3%).

[0024] Comparative Example 2 100g of ATP-1 from Example 1 was added to a ball mill and milled for 20 minutes at 200 rpm to obtain attapulgite powder (bulk density 0.46g / cm³). 3 Powder particle size D100 < 5 micrometers).

[0025] Example 2 1. Purification: Crush 500g of attapulgite clay into small particles of 1-3 mm, then add 1L of 10wt% nitric acid solution, stir for 30 minutes, let stand for 24 hours, wash with water 2-3 times, and filter by pressure. Next, disperse the filter cake in 1L of ethanol / water solution, add 5g of PMMA-PDMS, and then sonicate at 80°C for 2 hours. After that, let it settle naturally for 24 hours, take the upper suspension, filter, and dry to obtain attapulgite (purity 90.5%).

[0026] 2. Powdering: Mix 1g of pentaerythritol di(hexadecyl) phosphite and 100g of attapulgite, add to a ball mill, and ball mill at 200 rpm for 20 minutes to obtain attapulgite powder (bulk density 0.41g / cm³). 3Powder particle size D100 < 4.5 micrometers).

[0027] Example 3 1. Purification: Crush 500g of attapulgite clay into small particles of 1-3 mm, then add 1L of 10wt% nitric acid solution, stir for 30 minutes, let stand for 24 hours, wash with water 2-3 times, and filter by pressure. Next, disperse the filter cake in 1L of ethanol / water solution, add 15g of PMMA-PDMS, and then sonicate at 80 degrees Celsius for 1 hour. After that, let it settle naturally for 24 hours, take the upper suspension, filter, and dry to obtain attapulgite (purity 94.9%).

[0028] 2. Powdering: Mix 5g of pentaerythritol di(hexadecyl) phosphite and 100g of attapulgite, add to a ball mill, and ball mill at 200 rpm for 20 minutes to obtain attapulgite powder (bulk density 0.39g / cm³). 3 Powder particle size D100 < 4 micrometers).

[0029] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for purifying and pulverizing attapulgite clay, comprising: (1) After soaking the attapulgite clay particles in acid for a certain period of time, they are washed with water; (2) Add the attapulgite clay and polymethyl methacrylate-polysiloxane block copolymer treated in step (1) to an ethanol aqueous solution, stir evenly with ultrasonication, and let it settle naturally for a certain period of time. Then take the upper suspension, filter, dry and crush it to obtain attapulgite powder.

2. The purification and powdering method according to claim 1, characterized in that: The acid solution is a nitric acid solution with a concentration of 5-10 wt%.

3. The purification and powdering method according to claim 2, characterized in that: In step (1), the solid-liquid ratio of attapulgite clay particles to acid solution is 1:(1~3) g / mL.

4. The purification and powdering method according to claim 1, characterized in that: In step (1), the particle size of the attapulgite clay particles is 1~3 mm.

5. The purification and powdering method according to claim 1, characterized in that: In step (2), the amount of polymethyl methacrylate-polysiloxane block copolymer used is 1 to 3% of the mass of attapulgite clay.

6. The purification and powdering method according to claim 1, characterized in that: In step (2), the solid-liquid ratio of attapulgite clay to ethanol aqueous solution is 1:(1~3) g / mL, and preferably, the concentration of ethanol aqueous solution is 10~30 v.

7. The purification and powdering method according to claim 1, characterized in that: In step (2), the ultrasonic stirring time is 1~2 hours and the temperature is 70~90℃.

8. The purification and powdering method according to claim 1, characterized in that: In step (2), the natural settling time is 24 hours.

9. The purification and powdering method according to claim 1, characterized in that: In step (2), the dried attapulgite and pentaerythritol di(hexadecyl) phosphite are mixed and pulverized in a ball mill.

10. The purification and powdering method according to claim 1, characterized in that: The amount of pentaerythritol di(hexadecyl) phosphite used is 1-5 wt% of attapulgite.