Treatment method for improving viscosity concentration of kaolin through shearing and extruding

Abstract

The invention discloses a treatment method for improving viscosity concentration of kaolin by shearing and extruding, which comprises the following steps: mixing a kaolin raw material with water to prepare a kaolin mud cake; adjusting the wheel spacing of the shearing and extruding equipment to be 1-5mm; adding the kaolin mud cake into shearing and extruding equipment for shearing and extruding treatment; pulping the kaolin mud subjected to shearing and extruding treatment again; and carrying out spray drying or flash drying on the slurried kaolin to obtain a high-viscosity concentration kaolin product. According to the method, the laminated kaolin sheet structure is stripped by adopting a physical method, the ordered arrangement of the kaolinite structure is promoted, sharp edges and corners between the kaolinite sheet corners are slowed down, and since no chemical agent is added, the viscosity concentration of the kaolin can be improved, and subsequent pollution to the kaolin is avoided, so that the viscosity concentration of the kaolin is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of deep processing of non-metallic mineral materials and environmental engineering, and particularly relates to a treatment method for improving the viscosity concentration of kaolin by shear extrusion. Background Art

[0002] Kaolin is a non-metallic clay mineral resource with high economic value. Due to its excellent properties, it has been widely used in many industrial fields; in recent years, the uses of kaolin in new materials such as composite materials, new ceramics, and coated papermaking have attracted more and more attention.

[0003] Viscosity concentration is an important index for the application of kaolin in the paper industry. For a kaolin slurry with a certain concentration, the lower the viscosity, the higher the viscosity concentration value, the better the fluidity, and the better the viscosity concentration characteristics of its products; China is rich in kaolin resources, but the viscosity characteristics are generally poor; taking Maoming, the main production base of kaolin for paper coatings in China, as an example, the viscosity concentration is basically below 70%, mainly 68%, while the viscosity concentration of kaolin in the United States and Brazil can reach about 72% - 74%.

[0004] Thus, there is still a certain gap between the viscosity concentration characteristics of kaolin in China and those abroad. With the development of papermaking technology, the speed of papermaking coating machines is getting faster and faster, which requires the coating to have good fluidity. Improving its viscosity concentration can effectively improve the fluidity of the coating.

[0005] At a certain particle size, the stepped lamellar structure and abundant surface hydroxyl groups of water molecules will cause a large shear stress on the kaolin slurry, resulting in a large velocity gradient between the liquid layers on the surface of the kaolin lamellae, causing the kaolin slurry to have a high viscosity. Starting from the key points of the flake morphology that affect the viscosity of the kaolin slurry, how to change the microstructure of kaolin without adding chemical agents and with a simple process flow is the key to determining whether the viscosity concentration of the kaolin slurry can be improved. Summary of the Invention

[0006] In view of this, the main purpose of the present invention is to provide a treatment method for improving the viscosity concentration of kaolin by shear extrusion.

[0007] To achieve the above object, the technical solution of the present invention is realized as follows:

[0008] The embodiment of the present invention provides a treatment method for improving the viscosity concentration of kaolin by shear extrusion, and the method is as follows:

[0009] Mix the kaolin raw material with water to make a kaolin mud cake;

[0010] Adjust the wheel spacing of the shear extrusion equipment to 1 - 5 mm;

[0011] Add the kaolin mud cake into a shearing and extrusion device for 3 - 9 times of shearing and extrusion treatment;

[0012] Redisperse the kaolin after the shearing and extrusion treatment;

[0013] Prepare a product with high viscosity concentration by drying the redispersed kaolin.

[0014] In the above solution, mixing the kaolin raw material with water to make a kaolin mud cake specifically includes: performing purification pretreatment on the kaolin raw material, and then mixing it with water to make a kaolin mud cake with a moisture content of 20% - 35%, and the thickness of the kaolin mud cake is 10mm - 20mm.

[0015] In the above solution, the composition of the kaolin raw material includes 34.839% of Al2O3, 48.892% of SiO2, 0.143% of P2O5, 0.059% of SO3, 0.388% of K2O, 0.029% of CaO, 0.102% of MgO, 0.234% of TiO2, 0.951% of Fe2O3, 0.004% of PbO, 0.005% of Rb2O, 0.009% of Na2O, 0.009% of ZnO, and the loss on ignition during high - temperature calcination is 14.272%.

[0016] In the above solution, the particle size distribution of the kaolin raw material is that the content of - 2μm accounts for 96.15%, among which, the proportion of greater than 5.0μm is 3.99%, 5.0 - 2.0μm is 2.40%, 2.0 - 1.0μm is 10.13%, 1.0 - 0.4μm is 13.69%, and less than 0.4μm is 72.3%.

[0017] In the above solution, the composition of the kaolin raw material includes 34.819% of Al2O3, 49.656% of SiO2, 0.038% of P2O5, 0.082% of SO3, 0.46% of K2O, 0.015% of CaO, 0.256% of TiO2, 0.599% of Fe2O3, 0.005% of Rb2O, 0.002% of Y2O3, 0.1% of MgO, and the loss on ignition during high - temperature calcination is 13.968%.

[0018] In the above solution, the particle size distribution of the kaolin raw material is that the content of - 2μm accounts for 92.97%, among which, the proportion of greater than 5.0μm is 3.74%, 5.0 - 2.0μm is 3.31%, 2.0 - 1.0μm is 8.84%, 1.0 - 0.4μm is 14.60%, and less than 0.4μm is 69.53%.

[0019] In the above solution, some particles of the kaolin raw material have a pseudo-hexagonal flake morphology, but the particle size is relatively coarse; the remaining particles of the kaolin raw material have a stacked flake structure, but the particle size is relatively coarse.

[0020] In the above solution, when the kaolin mud cake after shear extrusion treatment is placed in an oven for drying, the temperature of the oven is 105 °C.

[0021] In the above solution, when the dried kaolin mud cake is broken by an impact crusher, the crushing time is 30 s.

[0022] In the above solution, the broken kaolin powder is prepared into a kaolin ore pulp with an increased viscosity concentration of 68%-71%.

[0023] Compared with the prior art, the present invention uses a physical method to peel off the stacked flake structure of kaolin, promote the orderly arrangement of the kaolinite structure, and slow down the sharp edges between the kaolinite flakes. Since no chemical agents are added, the viscosity concentration of kaolin can be increased without subsequent pollution to kaolin, thereby realizing the increase of the viscosity concentration of kaolin. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The drawings described herein are used to disclose a further understanding of the present invention, and constitute a part of the present invention. The schematic embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation to the present invention. In the drawings:

[0025] Figure 1 It is a scanning electron microscope image of the first kaolin raw material in a method for increasing the viscosity concentration of kaolin by shear extrusion provided by an embodiment of the present invention.

[0026] Figure 2 It is a scanning electron microscope image of the second kaolin raw material in a method for increasing the viscosity concentration of kaolin by shear extrusion provided by an embodiment of the present invention.

[0027] Figure 3 It is a graph showing the relationship between the Zeta potential and pH value of the first kaolin raw material in a method for increasing the viscosity concentration of kaolin by shear extrusion provided by an embodiment of the present invention.

[0028] Figure 4 It is a graph showing the relationship between the Zeta potential and pH value of the second kaolin raw material in a method for increasing the viscosity concentration of kaolin by shear extrusion provided by an embodiment of the present invention.

[0029] Figure 5 It is a schematic connection diagram of a processing device for increasing the viscosity concentration of kaolin by shear extrusion provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clear and understandable, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0031] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, article or device including a series of elements not only includes those elements, but also includes other elements not expressly listed, or also includes elements inherent to such process, article or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, article or device including that element.

[0032] An embodiment of the present invention provides a treatment method for increasing the viscosity concentration of kaolin by shear extrusion. The method includes the following steps:

[0033] Step (1): Mix the kaolin raw material with water to make a kaolin mud cake.

[0034] Specifically, the kaolin raw material is subjected to purification pretreatment, and then mixed with water to make a kaolin mud cake with a moisture content of 20%-35%. The thickness of the kaolin mud cake is 10mm-20mm.

[0035] The purification pretreatment includes raw material crushing, pounding, sand removal, screw classification, and drying.

[0036] The making of the kaolin mud cake is to add water to the dried kaolin according to the proportion of the solid content, or the kaolin mud cake pressed after horizontal screw classification.

[0037] Step (2): Adjust the wheel spacing of the shear extrusion equipment to 1-5mm.

[0038] Specifically, the shear extrusion changes the microscopic morphology of the kaolin, making its stacked flakes into single flakes. The shear extrusion equipment can be a rubber mixing mill, a wheel mill, a pair of roll mills, or a hammering machine.

[0039] Step (3): Add the kaolin mud cake into the shear extrusion equipment for 3-9 times of shear extrusion treatment.

[0040] Step (4): Repulp the kaolin mud after shear extrusion treatment.

[0041] Specifically, the crushed kaolin powder is prepared into a kaolin ore pulp with an increased viscosity concentration of 50%-70%.

[0042] Step (5) prepares a product with a high viscosity concentration from the pulped kaolin by spray drying or flash drying.

[0043] The first type of kaolin raw material can be used. The composition of the kaolin raw material includes 34.839% of Al2O3, 48.892% of SiO2, 0.143% of P2O5, 0.059% of SO3, 0.388% of K2O, 0.029% of CaO, 0.102% of MgO, 0.234% of TiO2, 0.951% of Fe2O3, 0.004% of PbO, 0.005% of Rb2O, 0.009% of Na2O, 0.009% of ZnO, and the loss on ignition during high-temperature calcination is 14.272%.

[0044] Table 1 XRF analysis of the first type of kaolin raw material

[0045]

[0046] The particle size distribution of the kaolin raw material is that the content of -2μm accounts for 96.15%. Among them, the proportion of particles larger than 5.0μm is 3.99%, the proportion of 5.0 - 2.0μm is 2.40%, the proportion of 2.0 - 1.0μm is 10.13%, the proportion of 1.0 - 0.4μm is 13.69%, and the proportion of particles smaller than 0.4μm is 72.3%.

[0047] Table 2 Particle size distribution of the first type of kaolin raw material

[0048]

[0049] As Figure 1 shown, some particles of the kaolin raw material have a pseudo-hexagonal flake morphology, but the particle size is relatively coarse; the remaining particles of the kaolin raw material have a stacked flake structure, but the particle size is relatively coarse.

[0050] As Figure 3 shown, the repulsive force between the particles of the kaolin raw material causes an increase in the absolute value of the Zeta potential on the particle surface. As the pH value of the solution increases, the negative value of the Zeta potential of the kaolin raw material increases relatively quickly between pH values of 6.0 - 8.0, indicating that the dispersion degree of the kaolin slurry system is optimal between pH values of 6.0 - 8.0. As the pH value of the slurry increases, the change trend of the Zeta potential of the kaolin raw material is the same, indicating that the influence of the pH value on the two samples is the same. It only needs to control the pH value of the kaolin slurry to be within the optimal range, and the pH value has no influence on the viscosity characteristics of the pulp.

[0051] The kaolin raw material can be the second type. The composition of the kaolin raw material includes 34.819% of Al2O3, 49.656% of SiO2, 0.038% of P2O5, 0.082% of SO3, 0.46% of K2O, 0.015% of CaO, 0.256% of TiO2, 0.599% of Fe2O3, 0.005% of Rb2O, 0.002% of Y2O3, and 0.1% of MgO. The loss on ignition during high-temperature calcination is 13.968%.

[0052] Table 3 XRF analysis of the first type of kaolin raw material

[0053]

[0054] The particle size distribution of the kaolin raw material is that the content of particles with a size of -2μm accounts for 92.97%. Among them, the proportion of particles larger than 5.0μm is 3.74%, the proportion of particles with a size of 5.0 - 2.0μm is 3.31%, the proportion of particles with a size of 2.0 - 1.0μm is 8.84%, the proportion of particles with a size of 1.0 - 0.4μm is 14.60%, and the proportion of particles smaller than 0.4μm is 69.53%.

[0055] Table 4 Particle size distribution of the second type of kaolin raw material

[0056]

[0057] As Figure 2 shown, some particles of the kaolin raw material are in a pseudo-hexagonal flake morphology, but the particle size is relatively coarse; the remaining particles of the kaolin raw material are in a stacked flake structure, but the particle size is relatively coarse.

[0058] As Figure 4 shown, the repulsive force between the particles of the kaolin raw material causes an increase in the absolute value of the Zeta potential on the particle surface. As the pH value of the solution increases, the negative value of the Zeta potential of the kaolin raw material increases relatively fast between pH values of 6.0 - 8.0, indicating that the dispersion degree of the kaolin slurry system is optimal between pH values of 6.0 - 8.0. As the pH value of the slurry increases, the change trend of the Zeta potential of the kaolin raw material is the same, indicating that the influence of the pH value on the two samples is the same. It only needs to control the pH value of the kaolin slurry to be within the optimal range, and the pH value has no influence on the viscosity characteristics of the pulp.

[0059] Exemplarily, an embodiment of the present invention provides a treatment method for increasing the viscosity concentration of kaolin by shear extrusion. The method includes the following steps:

[0060] Step (1): Mix the kaolin raw material with water to make a kaolin mud cake.

[0061] Specifically, the kaolin raw material can be the first type. The components of the kaolin raw material include 34.839% of Al2O3, 48.892% of SiO2, 0.143% of P2O5, 0.059% of SO3, 0.388% of K2O, 0.029% of CaO, 0.102% of MgO, 0.234% of TiO2, 0.951% of Fe2O3, 0.004% of PbO, 0.005% of Rb2O, 0.009% of Na2O, 0.009% of ZnO, and the loss on ignition during high-temperature calcination is 14.272%.

[0062] The particle size distribution of the kaolin raw material is that the content of -2μm accounts for 96.15%. Among them, the proportion of particles larger than 5.0μm is 3.99%, the proportion of particles in the range of 5.0 - 2.0μm is 2.40%, the proportion of particles in the range of 2.0 - 1.0μm is 10.13%, the proportion of particles in the range of 1.0 - 0.4μm is 13.69%, and the proportion of particles smaller than 0.4μm is 72.3%.

[0063] As Figure 1 shown, some particles of the kaolin raw material are in the shape of pseudo-hexagonal flakes, but the particle size is relatively coarse; the remaining particles of the kaolin raw material are in a stacked flake structure, but the particle size is relatively coarse.

[0064] As Figure 3 shown, the repulsive force between the particles of the kaolin raw material causes the absolute value of the Zeta potential on the particle surface to increase. As the pH value of the solution increases, the negative value of the Zeta potential of the kaolin raw material increases relatively fast between pH values of 6.0 - 8.0, indicating that the dispersion degree of the kaolin slurry system is optimal between pH values of 6.0 - 8.0. As the pH value of the slurry increases, the change trend of the Zeta potential of the kaolin raw material is the same, indicating that the influence of the pH value on the two samples is the same. It only needs to control the pH value of the kaolin slurry to be within the optimal range, and the pH value has no influence on the viscosity characteristics of the pulp.

[0065] The kaolin raw material is subjected to purification pretreatment, and then mixed with water to make a kaolin mud cake with a moisture content of 20% - 35%. The thickness of the kaolin mud cake is 10mm - 20mm.

[0066] The purification pretreatment includes raw material crushing, pounding, sand removal, spiral classification, and drying.

[0067] The making of the kaolin mud cake is to add water to the dried kaolin according to the proportion of the solid content, or the kaolin mud cake pressed after horizontal spiral classification.

[0068] In step (2), adjust the wheel spacing of the shear extrusion equipment to 1mm;

[0069] Specifically, the shearing and extrusion change the microscopic morphology of kaolin, transforming its stacked flake shape into single flake shape. The shearing and extrusion equipment can be a rubber mixing mill, a wheel mill, a pair-roll mill, or a hammer mill.

[0070] Step (3): Add the kaolin mud cake into the shearing and extrusion equipment for three times of shearing and extrusion treatment.

[0071] Step (4): Repulp the kaolin after the shearing and extrusion treatment.

[0072] Specifically, the pulverized kaolin after being broken is prepared into a kaolin ore pulp with a viscosity concentration increased to 50%-70%.

[0073] Step (5): Prepare a product with a high viscosity concentration from the pulpified kaolin through spray drying or flash drying.

[0074] Exemplarily, an embodiment of the present invention further provides a treatment method for increasing the viscosity concentration of kaolin through shearing and extrusion. The method includes the following steps:

[0075] Step (1): Mix the kaolin raw material with water to make a kaolin mud cake.

[0076] Specifically, the second type of kaolin raw material can be adopted. The composition of the kaolin raw material includes 34.819% of Al2O3, 49.656% of SiO2, 0.038% of P2O5, 0.082% of SO3, 0.46% of K2O, 0.015% of CaO, 0.256% of TiO2, 0.599% of Fe2O3, 0.005% of Rb2O, 0.002% of Y2O3, 0.1% of MgO, and the loss on ignition during high-temperature calcination is 13.968%.

[0077] The particle size distribution of the kaolin raw material is that the content of particles with a size of -2μm accounts for 92.97%. Among them, the proportion of particles larger than 5.0μm is 3.74%, the proportion of particles with a size of 5.0 - 2.0μm is 3.31%, the proportion of particles with a size of 2.0 - 1.0μm is 8.84%, the proportion of particles with a size of 1.0 - 0.4μm is 14.60%, and the proportion of particles smaller than 0.4μm is 69.53%.

[0078] As Figure 2 shown, some particles of the kaolin raw material are in the shape of pseudo-hexagonal flakes, but the particle size is relatively coarse; the remaining particles of the kaolin raw material are in a stacked flake structure, but the particle size is relatively coarse.

[0079] As Figure 4As shown, the repulsive force between the particles of the kaolin raw material causes an increase in the absolute value of the Zeta potential on the particle surface. As the pH value of the solution increases, the negative value of the Zeta potential of the kaolin raw material increases relatively rapidly between pH values of 6.0 - 8.0, indicating that the dispersion degree of the kaolin slurry system is optimal between pH values of 6.0 - 8.0. As the pH value of the slurry increases, the changing trend of the Zeta potential of the kaolin raw material is the same, indicating that the influence of the pH value on the two samples is the same. It is only necessary to control the pH value of the kaolin slurry to be within the optimal range, and the pH value has no influence on the viscosity characteristics of the pulp.

[0080] The kaolin raw material is subjected to purification pretreatment and then mixed with water to form a kaolin mud cake with a moisture content of 20% - 35%. The thickness of the kaolin mud cake is 10 mm - 20 mm.

[0081] The purification pretreatment includes raw material crushing, pounding, sand removal, screw classification, and drying.

[0082] The preparation of the kaolin mud cake is to add water to the dried kaolin according to the proportion of the solid content, or the kaolin mud cake pressed after horizontal screw classification can also be used.

[0083] In step (2), adjust the wheel spacing of the shear extrusion equipment to 1 mm;

[0084] Specifically, the shear extrusion changes the microscopic morphology of the kaolin, making its stacked flakes into single flakes. The shear extrusion equipment can be a rubber mixing mill, a wheel mill, a pair of roll mills, or a hammering machine.

[0085] In step (3), add the kaolin mud cake into the shear extrusion equipment for 3 times of shear extrusion treatment;

[0086] In step (4), re-slurry the kaolin mud after the shear extrusion treatment.

[0087] Specifically, the crushed kaolin powder is prepared into a kaolin slurry with an increased viscosity concentration of 50% - 70%.

[0088] In step (5), the re-slurried kaolin is prepared into a product with a high viscosity concentration by spray drying or flash drying.

[0089] The embodiment of the present invention also provides a processing equipment for increasing the viscosity concentration of kaolin by shear extrusion, as Figure 5 shown, including:

[0090] A mud cake preparation device for mixing the kaolin raw material with water to form a kaolin mud cake with a moisture content of 20% - 35%. The thickness of the kaolin mud cake is 10 mm - 20 mm;

[0091] A shearing and extrusion device with an adjustable wheel spacing of 1-5 mm is used to perform 3-9 times of shearing and extrusion treatment on the kaolin mud cake;

[0092] A pulping device is used to repulp the kaolin mud after shearing and extrusion treatment;

[0093] A drying device is used to prepare a high-viscosity concentration product by spray drying or flash drying the pulpified kaolin.

[0094] Specifically, the mud cake preparation device includes a purification pretreatment unit and a mixing and cake-making unit. The purification pretreatment unit is used to purify the kaolin raw material, and the mixing and cake-making unit is used to mix the purified kaolin raw material with water to make the kaolin mud cake.

[0095] The shearing and extrusion device is any one of a rubber mill, a wheel mill, a pair-roll mill or a hammer mill, and its wheel spacing can be adjusted by an adjustment mechanism.

[0096] Furthermore, a drying device is also included, which is used to dry the kaolin mud cake after shearing and extrusion treatment therein, and the temperature of the drying device can be controlled at about 105°C.

[0097] Furthermore, a crushing device is also included, which is used to break up the dried kaolin mud cake for subsequent preparation of kaolin slurry.

[0098] Specifically, the crushing device is an impact crusher, and its crushing time can be set at about 30 s.

[0099] Specifically, the pulping device can prepare a kaolin slurry with an increased viscosity concentration of 68%-71% from the broken kaolin powder.

[0100] Furthermore, a control system is also included, which is used to control the operating parameters of each device to ensure the stability and accuracy of the entire processing process.

[0101] Example 1:

[0102] An embodiment of the present invention provides a treatment method for improving the viscosity concentration of kaolin by shearing and extrusion. The specific implementation steps are as follows:

[0103] (1) Weigh 500 g of purified kaolin into a container and add water according to a water content of 25% for making the kaolin mud cake;

[0104] (2) Adjust the wheel spacing of the extruder to 1 mm;

[0105] (3) Cut the thickness of the kaolin mud cake to 5 mm with a utility knife;

[0106] (4) Start the extruder, add the cut kaolin mud cakes into it, and let the extruder rotate one full circle for one full extrusion. After all the prepared kaolin mud cakes have been extruded, repeat the extrusion two more times.

[0107] (5) Collect the sheared and extruded kaolin mud cakes and place them in an oven at 105 °C.

[0108] (6) Crush the dried kaolin mud cakes with an impact mill for 30 s and collect them for measuring the viscosity concentration to be tested.

[0109] (7) Test and calculate the viscosity concentration value according to the national standard testing method for the viscosity concentration of kaolin.

[0110] Example 2:

[0111] The raw materials and steps are the same as those in Example 1, except that water is added according to the water content of the kaolin mud cake being 32%.

[0112] Example 3:

[0113] The raw materials and steps are the same as those in Example 1, except that water is added according to the water content of the kaolin mud cake being 25%; the thickness of the kaolin mud cake is 25 mm, and the distance between the extruder is 20 mm.

[0114] Example 4:

[0115] The raw materials and steps are the same as those in Example 1, except that water is added according to the water content of the kaolin mud cake being 32%; the thickness of the kaolin mud cake is 25 mm, and the distance between the extruder is 20 mm.

[0116] Example 5:

[0117] The steps are the same as those in Example 1, except that the kaolin is bleached.

[0118] Example 6:

[0119] The steps are the same as those in Example 2, except that the kaolin is bleached.

[0120] Example 7:

[0121] The steps are the same as those in Example 3, except that the kaolin is bleached.

[0122] Example 8:

[0123] The steps are the same as those in Example 4, except that the kaolin is bleached.

[0124] Using the comparison between the viscosity concentration of the sheared and extruded kaolin and the viscosity concentration of the original ore as the evaluation index, the comparison results of Examples 1 to 8 are shown in Table 1.

[0125] As can be seen from Table 5, through the shear extrusion condition test, it can be seen that the viscosity concentration of kaolin with 3 extrusion times has a relatively obvious increase compared to the viscosity concentration of the original ore. For the unbleached kaolin, after 3 shear extrusions, its viscosity concentration value increases from 68.64% to 71.12%, an increase of 2.48 percentage points; for the bleached kaolin, after 3 shear extrusions, its viscosity concentration value increases from 68.79% to 71.85%, an increase of 3.06 percentage points. For the unbleached kaolin, after 9 extrusions, its viscosity concentration value is 69.53%, and for the bleached kaolin, after 9 shear extrusions, its viscosity concentration value is 69.56%. Although it has increased compared to the viscosity concentration of the original ore, it is lower than the viscosity concentration of the soil after 3 shear extrusions. Combining the scanning electron microscope test analysis, it can be known that after 3 extrusions, the stacked sheets are peeled off, but after 9 extrusions, the particle size is significantly reduced, resulting in agglomeration and increasing the viscosity. Repeated extrusion after the stacked sheets are peeled off will make the particle size too fine, resulting in agglomeration and also causing damage to the surface of kaolinite scales, overall showing an increase in viscosity. Therefore, 3 extrusions can meet the viscosity reduction requirements.

[0126] Table 5 Comparison results of viscosity concentration values of raw materials and Examples 1 to 8

[0127]

[0128] Experimental data:

[0129] Tests and studies on viscosity reduction of the present invention, chemical method for viscosity reduction, physical and chemical combined method for viscosity reduction, new viscosity reduction technology, etc. were carried out on two samples of the first kaolin raw material YH and the second kaolin raw material FM. Among them, the classification test and extrusion test in the chemical method for viscosity reduction test and the mechanical and physical method for viscosity reduction test, and the intercalation test and ion addition test in the new viscosity reduction test are all effective for kaolin viscosity reduction. Although the chemical method for viscosity reduction test and the ion addition test in the new viscosity reduction test can increase the viscosity concentration of the pulp, the effect is limited, and it has an impact on the subsequent treatment of the kaolin pulp; the extrusion test increases the viscosity concentration of YH and FM kaolin by 2.48 and 2.96 percentage points respectively.

[0130] A total of 8 shear extrusions were carried out on two types of kaolin, the first kaolin raw material YH and the second kaolin raw material FM, and the specific test conditions are shown in Table 6.

[0131] Table 6 Extrusion test conditions

[0132]

[0133] The sheet-like kaolin after shear extrusion was dried and broken into powder for viscosity testing. The treatment conditions with obvious viscosity reduction effect were selected, and repeated tests were carried out for viscosity concentration testing. The test results of viscosity testing are shown in Table 7.

[0134] The viscosity concentration test results are shown in Table 8.

[0135] Table 7 Viscosity test results of extrusion test

[0136]

[0137] Table 8 Viscosity concentration test results of extrusion test

[0138]

[0139] It can be seen from the test results in Table 7 and Table 8 that after the extrusion condition test, the viscosity of the YH kaolin filter cake slurry shows an increasing trend with the increase of the extrusion times, while the viscosity of the FM kaolin filter cake slurry shows a decreasing trend with the increase of the extrusion times. Therefore, the samples after three extrusions are taken for viscosity concentration test. The viscosity concentration is calculated for the repeated test of FM kaolin, and the result is 71.04%, which has a relatively significant improvement compared with the original FM kaolin (68.79%).

[0140] The FM sample with good extrusion effect and the YH sample with poor effect are subjected to scanning electron microscope test, and the test results are shown in Figures 1 - 4 . It can be seen from the test results that the FM sample is peeled off after 3 extrusions, and the YH sample is also peeled off, but after 9 extrusions, the particle size is significantly reduced, resulting in agglomeration and increasing the viscosity.

[0141] Under the condition of constant roller spacing, the YH kaolin test is repeated, and its viscosity value is 71.12%. To ensure the rigor of the test, the two effective condition repeated tests are carried out for viscosity concentration verification, and the viscosity concentration results of YH and FM are 70.87% and 71.85% respectively.

[0142] The main influencing factors of the extrusion test are the moisture content of the filter cake, the extrusion times, and the roller spacing. Among them, the roller spacing is the decisive factor. As long as the kaolin laminations are peeled off, the purpose of viscosity reduction can be achieved. It can be seen from the viscosity test results of 3 extrusions and 9 extrusions that after the laminations are peeled off and then extruded multiple times, the particle size will be too fine, resulting in agglomeration, and it will also cause damage to the surface of kaolinite scales, and the overall performance is an increase in viscosity. Therefore, 3 extrusions can meet the viscosity reduction requirements.

[0143] By extrusion, the kaolin laminations are peeled off, and its viscosity concentration can be increased by more than 2 percentage points. No chemical agents are added during the extrusion process, which has no impact on subsequent applications. However, if the extrusion intensity is too large, the particle size will be too fine and the scales will be damaged, resulting in a decrease in viscosity concentration.

[0144] It can be seen from the scanning electron microscope photos that extrusion can peel off the kaolin laminations, and the scale particle size becomes finer after 9 extrusions.

[0145] The above are only the preferred embodiments of the present invention and are not intended to limit the protection scope of the present invention.

Claims

1. A treatment method for increasing the viscosity concentration of kaolin by shear extrusion, characterized in that, The method is as follows: Mix the kaolin raw material with water to make a kaolin mud cake; Adjust the wheel spacing of the shearing and extrusion equipment to 1 - 5 mm; Add the said kaolin mud cake into the shearing and extrusion equipment for 3 - 9 times of shearing and extrusion treatment; Redisperse the kaolin mud after the shearing and extrusion treatment; Prepare a product with high viscosity concentration by drying the redispersed kaolin.

2. The treatment method for increasing the viscosity concentration of kaolin by shear extrusion according to claim 1, characterized in that, The step of mixing the kaolin raw material with water to make a kaolin mud cake specifically includes: performing purification pretreatment on the kaolin raw material, and then mixing it with water to make a kaolin mud cake with a moisture content of 20% - 35%, and the thickness of the kaolin mud cake is 10 mm - 20 mm.

3. The treatment method for increasing the viscosity concentration of kaolin by shear extrusion according to claim 1, characterized in that, The composition of the kaolin raw material includes 34.839% of Al2O3, 48.892% of SiO2, 0.143% of P2O5, 0.059% of SO3, 0.388% of K2O, 0.029% of CaO, 0.102% of MgO, 0.234% of TiO2, 0.951% of Fe2O3, 0.004% of PbO, 0.005% of Rb2O, 0.009% of Na2O, 0.009% of ZnO, and the loss on ignition during high-temperature calcination is 14.272%.

4. The treatment method for increasing the viscosity concentration of kaolin by shear extrusion according to claim 3, characterized in that, The particle size distribution of the kaolin raw material is that the content of -2μm accounts for 96.15%, among which, the proportion of particles larger than 5.0μm is 3.99%, the proportion of 5.0 - 2.0μm is 2.40%, the proportion of 2.0 - 1.0μm is 10.13%, the proportion of 1.0 - 0.4μm is 13.69%, and the proportion of particles smaller than 0.4μm is 72.3%.

5. The treatment method for increasing the viscosity concentration of kaolin by shear extrusion according to claim 1, characterized in that, The composition of the kaolin raw material includes 34.819% of Al2O3, 49.656% of SiO2, 0.038% of P2O5, 0.082% of SO3, 0.46% of K2O, 0.015% of CaO, 0.256% of TiO2, 0.599% of Fe2O3, 0.005% of Rb2O, 0.002% of Y2O3, 0.1% of MgO, and the loss on ignition during high-temperature calcination is 13.968%.

6. The treatment method for increasing the viscosity concentration of kaolin by shear extrusion according to claim 5, characterized in that, The particle size distribution of the kaolin raw material is that the content of -2μm accounts for 92.97%, among which, the proportion of particles larger than 5.0μm is 3.74%, the proportion of 5.0 - 2.0μm is 3.31%, the proportion of 2.0 - 1.0μm is 8.84%, the proportion of 1.0 - 0.4μm is 14.60%, and the proportion of particles smaller than 0.4μm is 69.53%.

7. The treatment method for increasing the viscosity concentration of kaolin by shear extrusion according to claim 1, characterized in that, Some particles of the kaolin raw material are in the shape of pseudo-hexagonal flakes, but the particle size is relatively coarse; the remaining particles of the kaolin raw material are in a stacked flake structure, but the particle size is relatively coarse.

8. The treatment method for increasing the viscosity concentration of kaolin by shear extrusion according to any one of claims 1-7, characterized in that, Place the kaolin mud cake after the shearing and extrusion treatment in an oven for drying, and the temperature of the oven is 105°C.

9. The treatment method for increasing the viscosity concentration of kaolin by shear extrusion according to claim 8, characterized in that, Break the dried kaolin mud cake by an impact mill, and the crushing time is 30 s.

10. The treatment method for increasing the viscosity concentration of kaolin by shear extrusion according to claim 9, characterized in that, Prepare the broken kaolin powder into a kaolin slurry with a viscosity concentration increased to 68% - 71%.

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