A kind of kaolin ultrafine grinding medium and preparation method thereof

Abstract

The present invention relates to the field of grinding media, and in particular to a kaolin ultrafine grinding medium and a preparation method thereof, comprising the following components by weight: 40-65 parts of modified kaolin, 20-25 parts of aluminum oxide, 10-15 parts of zirconium oxide, 10-20 parts of corundum, 5-15 parts of silicon nitride, 1-3 parts of feldspar and 5-10 parts of nano silicon dioxide. The present invention pre-treats kaolin in a sulfuric acid solution, and then dry-heats a mixture of kaolin material and nano zinc oxide at 100-200°C for 2-3h to obtain modified kaolin, which can significantly improve the corrosiveness, stability and wear resistance of the grinding medium.

Description

Technical Field

[0001] The invention relates to the field of grinding media, and in particular to an ultrafine kaolin grinding medium and a preparation method thereof. Background Art

[0002] Kaolin is an important non-metallic mineral mainly composed of kaolinite clay minerals. It is white, fine, soft and has good plasticity and fire resistance. Its mineral components mainly include: kaolinite, halloysite, hydromica, illite, montmorillonite, quartz, feldspar, etc. The crystal structure of kaolinite is characterized by: the unit layer structure consists of two layers, one layer of -Si-O-tetrahedron layer and one layer of -Al-(O,OH)-octahedron layer. These structural unit layers are connected by hydrogen bonds to form overlapping layered stacks, thus forming the flaky structure of kaolinite. Therefore, kaolin is widely used, mainly in papermaking, ceramics and refractory materials, secondly in coatings, rubber fillers, enamel glazes and white cement raw materials, and a small amount is used in plastics, pigments, grinding wheels, agriculture, medicine, petroleum, chemicals, environmental protection, national defense and other industrial sectors. Peeling off the layers of kaolinite to obtain kaolin with smaller particle sizes or even ultrafine kaolin can significantly improve the grade of kaolin products and increase the added value of the products.

[0003] Chinese patent CN108483458B discloses a wet method for increasing the specific surface area of ​​kaolin, by quickly adding concentrated sulfuric acid to the slurry, and inputting the slurry into a flaking machine for flaking, to obtain a kaolin product, and the grinding medium for flaking is a zirconium oxide aluminum composite ball. Since the wet flaking has a certain corrosiveness, the loss rate of the grinding medium during grinding is relatively large. Therefore, under the condition of keeping the existing grinding equipment unchanged, it is urgent to develop a kaolin grinding medium with wear resistance, corrosion resistance and stability, which can reduce the wear rate, improve production efficiency, save a large amount of non-renewable mineral resources, and play a positive role in environmental protection. Summary of the invention

[0004] Technical issues solved

[0005] In view of the deficiencies of the prior art, the present invention aims to provide a kaolin ultrafine grinding medium and a preparation method thereof, which can improve the corrosion resistance, wear resistance and stability of the grinding medium, thereby reducing the wear rate of the grinding medium when grinding kaolin powder and reducing the consumption of the grinding medium.

[0006] Technical Solution

[0007] In order to achieve the above object, the present invention adopts the following technical scheme: a kaolin ultrafine grinding medium and a preparation method thereof, comprising the following components in parts by weight:

[0008] 40-65 parts of modified kaolin, 20-25 parts of alumina, 10-15 parts of zirconium oxide, 10-20 parts of corundum, 5-15 parts of silicon nitride, 1-3 parts of feldspar and 5-10 parts of nano silicon dioxide.

[0009] A method for preparing ultrafine kaolin grinding media comprises the following steps:

[0010] S1: adding modified kaolin, alumina, zirconia, corundum, silicon nitride, feldspar and nano-silicon dioxide into a ball mill, ball-milling to 2000-2200 mesh, discharging the material, and obtaining ultrafine powder of mixed raw materials;

[0011] S2: Stir and disperse the mixed raw materials at a speed of 800 to 1000 r / min for 1 to 2 hours, then put them into a spheroidizer and roll them into spheres with a diameter of 1 mm to 15 mm;

[0012] S3: Firing in a kiln at a heating rate of 5-10°C / min, from room temperature to 800-1200°C, keeping the temperature constant for 2-4h, and then firing at a heating rate of 5-10°C / min, and when the temperature reaches 1200-1500°C, keep the temperature constant for 0.5-1h;

[0013] S4: Natural cooling and annealing, taking out of the kiln, self-polishing the sphere, and screening to obtain the finished product.

[0014] Preferably, the preparation method of modified kaolin comprises the following steps:

[0015] 1) Place kaolin in a sulfuric acid solution at 80-100°C and stir continuously for 2-3 hours, then rinse with clean water, filter and dry, and crush to 200-300 mesh to obtain kaolin material;

[0016] 2) Add zinc sulfate to a sodium hydroxide solution, then add sodium dodecyl sulfate, heat the solution to 50-60°C for reaction for 6-9 hours, filter after the reaction, wash with deionized water until neutral, and calcine at 600-800°C for 4-6 hours to obtain nano zinc oxide;

[0017] 3) Evenly mix the kaolin material and nano zinc oxide to obtain a mixture, and dry-heat the mixture at 100-200° C. for 2-3 hours;

[0018] 4) After natural cooling, grinding and sieving, the modified kaolin is obtained.

[0019] The preparation process of modified kaolin includes two parts: sulfation of kaolin and intercalation treatment. Using sulfuric acid solution to remove impurities and ions on the surface of kaolin and between the layers helps the kaolin material and the nano zinc oxide mixture to combine and evenly disperse during dry heating, and then chemical reactions occur on the surface of kaolin and between the layers. Since nano zinc oxide has a relatively high specific surface area, its nano-scale particle size and high specific surface area can provide more active surfaces, increase its contact area with kaolin, and thus improve the reaction of zinc oxide with kaolin materials. Modified kaolin is obtained by the coordination reaction of zinc ions with anions in the layered structure of kaolin to form stable compounds. The covering protective film formed by the stable compound can block the erosion of corrosive media, thereby improving its corrosion resistance, and then improving the corrosion resistance, stability and wear resistance of kaolin ultrafine grinding media.

[0020] Furthermore, the percentage concentration of the sulfuric acid solution in step 1) is 40% to 50%.

[0021] Furthermore, the percentage concentration of the sodium hydroxide solution in step 2) is 10% to 20%.

[0022] Furthermore, in step 2), the weight ratio of zinc sulfate to sodium dodecyl sulfate is 1:25-40.

[0023] Furthermore, in step 3), the weight ratio of kaolin material to nano zinc oxide is 1:20-30.

[0024] Beneficial Effects

[0025] The present invention provides a kaolin ultrafine grinding medium and a preparation method thereof, wherein kaolin is pretreated with a sulfuric acid solution to remove impurities and ions on its surface and between lamellae, and the surface activity is increased to increase the combination and uniform dispersion of the kaolin material and the nano zinc oxide mixture in dry heating, and the zinc ions can coordinate with the anions in the kaolin layered structure to form a stable covering protective film to block the erosion of the corrosive medium, thereby improving its corrosion resistance, and further improving the corrosion resistance, stability and wear resistance of the kaolin ultrafine grinding medium. The process of the present invention is simple to operate, stable and reliable in operation, and low in cost. DETAILED DESCRIPTION

[0026] The technical scheme of the present invention is further described below through specific examples. Unless otherwise specified in the present invention, the raw materials and equipment used can be purchased from the market or are commonly used in the art, and the methods in the embodiments are conventional methods in the art unless otherwise specified.

[0027] Example 1

[0028] A kaolin ultrafine grinding medium is prepared from the following raw materials in parts by weight: 65 parts of modified kaolin, 25 parts of aluminum oxide, 15 parts of zirconium oxide, 20 parts of corundum, 15 parts of silicon nitride, 3 parts of feldspar and 10 parts of nano silicon dioxide.

[0029] The preparation method of modified kaolin comprises the following steps:

[0030] 1) Place kaolin in a 50% sulfuric acid solution at 100°C and stir for 3 hours, then rinse with clean water, filter and dry, and crush to 300 mesh to obtain kaolin material;

[0031] 2) Add zinc sulfate to a 20% sodium hydroxide solution, and then add sodium dodecyl sulfate, wherein the weight ratio of zinc sulfate to sodium dodecyl sulfate is 1:40, heat the solution to 60°C for reaction for 9 hours, filter after the reaction, wash with deionized water until neutral, and calcine at 800°C for 6 hours to obtain nano zinc oxide;

[0032] 3) The kaolin material and nano zinc oxide were mixed uniformly in a weight ratio of 1:30 to obtain a mixture, and the mixture was dry-heated at 200° C. for 3 h;

[0033] 4) After natural cooling, grinding and sieving, the modified kaolin is obtained.

[0034] A method for preparing ultrafine kaolin grinding media comprises the following steps:

[0035] S1: adding modified kaolin, alumina, zirconia, corundum, silicon nitride, feldspar and nano-silicon dioxide into a ball mill, and grinding to 2200 mesh, discharging the material to obtain ultrafine powder of mixed raw materials;

[0036] S2: The mixed raw materials were stirred and dispersed at a speed of 1000 r / min for 2 h, and then put into a spheroidizer and rolled into spheres with a diameter of 15 mm;

[0037] S3: Firing in a kiln at a heating rate of 10°C / min, from room temperature to 1200°C, keeping the temperature constant for 4 hours, and then firing at a heating rate of 10°C / min, when the temperature reaches 1500°C, keeping the temperature constant for 1 hour;

[0038] S4: Natural cooling and annealing, taking out of the kiln, self-polishing the sphere, and screening to obtain the finished product.

[0039] Example 2

[0040] A kaolin ultrafine grinding medium is prepared from the following raw materials in parts by weight: 40 parts of modified kaolin, 20 parts of aluminum oxide, 10 parts of zirconium oxide, 10 parts of corundum, 5 parts of silicon nitride, 1 part of feldspar and 5 parts of nano silicon dioxide.

[0041] The preparation method of modified kaolin comprises the following steps:

[0042] 1) Place kaolin in a 40% sulfuric acid solution at 80°C and stir for 2 hours, then rinse with clean water, filter and dry, and grind to 200 mesh to obtain kaolin material;

[0043] 2) Add zinc sulfate to a 10% sodium hydroxide solution, and then add sodium dodecyl sulfate, wherein the weight ratio of zinc sulfate to sodium dodecyl sulfate is 1:25, heat the solution to 50°C for reaction for 6 hours, filter after the reaction, wash with deionized water until neutral, and calcine at 600°C for 4 hours to obtain nano zinc oxide;

[0044] 3) Mix kaolin material and nano zinc oxide in a weight ratio of 1:20 to obtain a mixture, and dry-heat the mixture at 100° C. for 2 h;

[0045] 4) After natural cooling, grinding and sieving, the modified kaolin is obtained.

[0046] A method for preparing ultrafine kaolin grinding media comprises the following steps:

[0047] S1: adding modified kaolin, alumina, zirconia, corundum, silicon nitride, feldspar and nano-silicon dioxide into a ball mill, ball-milling to 2000 mesh, discharging the material, and obtaining ultrafine powder of mixed raw materials;

[0048] S2: The mixed raw materials were stirred and dispersed at a speed of 800 r / min for 1 h, and then put into a spheroidizer and rolled into spheres with a diameter of 1 mm;

[0049] S3: Firing in a kiln at a heating rate of 5°C / min, from room temperature to 800°C, keeping the temperature constant for 2h, and then firing at a heating rate of 5°C / min, and when the temperature reaches 1200°C, keep the temperature constant for 0.5h;

[0050] S4: Natural cooling and annealing, taking out of the kiln, self-polishing the sphere, and screening to obtain the finished product.

[0051] Example 3

[0052] A kaolin ultrafine grinding medium is prepared from the following raw materials in parts by weight: 55 parts of modified kaolin, 22 parts of aluminum oxide, 12 parts of zirconium oxide, 15 parts of corundum, 10 parts of silicon nitride, 2 parts of feldspar and 8 parts of nano silicon dioxide.

[0053] The preparation method of modified kaolin comprises the following steps:

[0054] 1) Place kaolin in a 45% sulfuric acid solution at 90°C and stir for 2.5 hours, then rinse with clean water, filter and dry, and grind to 250 mesh to obtain kaolin material;

[0055] 2) Add zinc sulfate to a 15% sodium hydroxide solution, and then add sodium dodecyl sulfate, wherein the weight ratio of zinc sulfate to sodium dodecyl sulfate is 1:35, heat the solution to 55°C for reaction for 7.5 hours, filter after the reaction, wash with deionized water until neutral, and calcine at 700°C for 5 hours to obtain nano zinc oxide;

[0056] 3) The kaolin material and nano zinc oxide were mixed uniformly in a weight ratio of 1:25 to obtain a mixture, and the mixture was dry-heated at 150° C. for 2.5 h;

[0057] 4) After natural cooling, grinding and sieving, the modified kaolin is obtained.

[0058] A method for preparing ultrafine kaolin grinding media comprises the following steps:

[0059] S1: adding modified kaolin, alumina, zirconia, corundum, silicon nitride, feldspar and nano-silicon dioxide into a ball mill, and grinding to 2100 mesh, discharging the material to obtain ultrafine powder of mixed raw materials;

[0060] S2: The mixed raw materials were stirred and dispersed at a speed of 900 r / min for 1.5 h, and then put into a spheroidizer and rolled to form spheres with a diameter of 10 mm;

[0061] S3: Firing in a kiln at a heating rate of 8°C / min, from room temperature to 1000°C, keeping the temperature constant for 3h, and then firing at a heating rate of 8°C / min, when the temperature reaches 1350°C, keeping the temperature constant for 0.8h;

[0062] S4: Natural cooling and annealing, taking out of the kiln, self-polishing the sphere, and screening to obtain the finished product.

[0063] Comparative Example 1:

[0064] The difference between Comparative Example 1 and Example 3 is that the kaolin is not modified.

[0065] Comparative Example 2

[0066] The difference between Comparative Example 2 and Example 3 is that the kaolin was not treated with sulfuric acid during modification.

[0067] Comparative Example 3

[0068] The difference between Comparative Example 3 and Example 3 is that the nano zinc oxide is replaced by zinc oxide.

[0069] Test results:

[0070] The corrosion resistance of the sample is evaluated by exposing it to the corrosive medium for a period of time and then measuring the weight loss of the sample. The weight loss rate is proportional to the corrosion rate, so the smaller the weight loss, the better the corrosion resistance of the sample.

[0071] Table 1 Corrosion resistance results of products

[0072] Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Weight loss rate 0.98% 1.52% 2.03% 12.47% 9.88% 7.62%

[0073] As can be seen from Table 1, the corrosion resistance of the example product is greater than that of the comparative example. This is mainly because the examples all contain modified kaolin, which can significantly improve the corrosion resistance, stability and wear resistance of the grinding medium. The kaolin material and the nano zinc oxide mixture are combined and evenly dispersed during dry heating, and then the zinc ions react with the anions in the layered structure of the kaolin to form a stable compound, thereby obtaining modified kaolin. A covering protective film is formed by a stable compound, which in turn blocks the erosion of the corrosive medium, thereby improving its corrosion resistance and improving the corrosion resistance, stability and wear resistance of the kaolin ultrafine grinding medium. As can be seen from Table 1, the corrosion resistance of comparative example 1 is less than that of comparative example 2.

Claims

1. A kaolin ultrafine grinding medium, characterized in that: The invention comprises the following components by weight: 40-65 parts of modified kaolin, 20-25 parts of alumina, 10-15 parts of zirconium oxide, 10-20 parts of corundum, 5-15 parts of silicon nitride, 1-3 parts of feldspar and 5-10 parts of nano silicon dioxide; the preparation method of the modified kaolin comprises the following steps: 1) placing kaolin in a sulfuric acid solution at 80-100°C and stirring continuously for 2-3 hours, then washing with clean water, filtering and drying, and crushing to 200-300 mesh to obtain kaolin material; 2) adding zinc sulfate to a sodium hydroxide solution, then adding sodium dodecyl sulfate, heating the solution to 50-60°C for reaction for 6-9 hours, filtering after the reaction, washing with deionized water to neutrality, and calcining at 600-800°C for 4-6 hours to obtain nano zinc oxide; 3) uniformly mixing the kaolin material and the nano zinc oxide to obtain a mixture, and dry-heating the mixture at 100-200°C for 2-3 hours; 4) naturally After cooling, grinding and sieving, the modified kaolin is obtained. The method for preparing the kaolin ultrafine grinding medium comprises the following steps: S1: adding the modified kaolin, alumina, zirconia, corundum, silicon nitride, feldspar and nano-silicon dioxide into a ball mill, ball-milling to 2000-2200 meshes, discharging the material, and obtaining the mixed raw material ultrafine powder; S2: stirring and dispersing the mixed raw material at a speed of 800-1000 r / min for 1-2 h, then put it into a ball forming machine and roll it to make a sphere with a diameter of 1mm to 15mm; S3: sinter it in a kiln, with a heating rate of 5 to 10℃ / min, from room temperature to 800 to 1200℃, keep the temperature constant for 2 to 4h, and then sinter it at a heating rate of 5 to 10℃ / min, and when the temperature reaches 1200 to 1500℃, keep it warm for 0.5 to 1h; S4: natural cooling and annealing, take it out of the kiln, polish the sphere by self-grinding, and screen out the finished product.

2. The kaolin ultrafine grinding medium according to claim 1, characterized in that: The percentage concentration of the sulfuric acid solution in step 1) is 40% to 50%.

3. The kaolin ultrafine grinding medium according to claim 1, characterized in that: The percentage concentration of the sodium hydroxide solution in step 2) is 10% to 20%.

4. The kaolin ultrafine grinding medium according to claim 1, characterized in that: In the step 2), the weight ratio of zinc sulfate to sodium dodecyl sulfate is 1:25-40.

5. The kaolin ultrafine grinding medium according to claim 1, characterized in that: In the step 3), the weight ratio of kaolin material to nano zinc oxide is 1:20-30.