Urea intercalation stripping method of kaolin

Abstract

The invention provides a urea intercalation stripping method of kaolin, which comprises the following steps: crushing and sieving kaolin mineral salt to obtain coarsely sieved mineral powder; soaking the coarsely screened ore powder by using an acid solution, and carrying out solid-liquid separation to obtain kaolin; urea particles and water are prepared according to the mass ratio of 1: (0.3-0.5), and an intercalator is obtained; mixing kaolin with an intercalator, and grinding to obtain intercalated kaolin; aging the intercalated kaolin, and calcining at high temperature to obtain kaolin powder. The intercalator prepared from urea particles and water according to the mass ratio range is selected, coarse mineral salt is preliminarily intercalated and stripped through competitive hydrogen-bond interaction with a kaolin layer by utilizing the synergistic effect of self-diffusion of urea micromolecules and auxiliary diffusion of water molecules, and then hydroxyl hydrogen is consumed through high-temperature calcination and urea high-temperature hydrolysis reaction; the crystal structure of the kaolin is compressed, the delamination effect is further improved, and the kaolin with small granularity is obtained.

Description

Technical Field

[0001] The present application belongs to the field of kaolin, and specifically relates to a urea intercalation stripping method of kaolin. Background Art

[0002] Kaolin process technology is a processing technology that uses kaolin, a clay mineral with a high content of aluminum oxide. Kaolin is mainly composed of silicate and aluminum oxide and is widely used in ceramics, building materials, cosmetics and medicine.

[0003] In the kaolin process, the ore is first processed by beneficiation, grinding, washing and other processing steps to obtain the ideal particle size and purity. Next, kaolin may need to be modified according to different needs to improve its specific properties. In the ceramic industry, kaolin can improve the plasticity and structural strength of ceramic products, and is also used in the preparation of ceramic glazes. In terms of building materials, kaolin can be used to prepare kaolin bricks, coatings, etc., with good heat insulation and sound insulation properties. In the field of cosmetics, kaolin is often used as an oil absorbent, oil control, thickener, etc., and is commonly found in products such as foundation and facial masks. In addition, kaolin is also used in pharmaceutical preparations, such as coating materials for tablets and stabilizers for oral suspensions. Since kaolin is a natural mineral resource, its mining and utilization will not cause excessive damage to the environment and has certain renewability, so it has certain environmental advantages and sustainability. With the advancement of science and technology, kaolin technology continues to develop. By improving process flow and control technology, the extraction rate and product quality of kaolin are improved. At the same time, new modification technology is used to make its application in different fields more extensive and effective.

[0004] The kaolin intercalation process is a technology that uses the unique structure of kaolin for processing. Kaolin has a layered structure in which the layers are linked by hydrogen bonds and there are certain gaps, so that some substances can be inserted into it in the form of molecules or ions to form intercalation complexes. The intercalation process inserts the target substance (such as polymers, dyes, drugs, etc.) into the interlayers of kaolin by selecting a suitable intercalant, thereby achieving the regulation of kaolin properties and functions. The process includes pretreatment, intercalant selection, mixed reaction, centrifugal separation and other steps, among which the selection of intercalants and the mixed reaction process are crucial to the intercalation effect. With the increasing demand for new materials and functional materials, the kaolin intercalation process is also constantly developing. By optimizing the process flow and improving the intercalation efficiency, it provides new possibilities for material preparation and application, and promotes the progress of materials science and engineering technology. Summary of the invention

[0005] The present application provides a urea intercalation stripping method for kaolin, which can refine kaolin and effectively reduce the particle size of kaolin to meet the ultrafine process particle size requirements of kaolin; it can also activate kaolin and broaden the application market of kaolin.

[0006] The urea intercalation stripping method of kaolin in the present application comprises:

[0007] The kaolinite is crushed and sieved to obtain a coarse-screened ore powder; the coarse-screened ore powder is soaked in an acidic solution to separate the solid and the liquid to obtain kaolin;

[0008] The urea granules and water are prepared in a mass ratio of 1: (0.3-0.5) to obtain an intercalation agent; the kaolin and the intercalation agent are mixed and ground to obtain intercalated kaolin;

[0009] The intercalated kaolin is aged and calcined at high temperature to obtain kaolin powder.

[0010] In a feasible implementation manner of the present application, in the step of crushing and sieving kaolinite to obtain coarse-screened ore powder, the sieving includes sieving through a sieve of 50 to 150 meshes.

[0011] In a feasible implementation of the present application, in the step of soaking the coarse-screened ore powder with an acidic solution and performing solid-liquid separation to obtain kaolin, the acidic solution includes a 0.8 mol / L to 1.5 mol / L hydrochloric acid solution.

[0012] In a feasible implementation manner of the present application, in the step of soaking the coarse-screened ore powder with an acidic solution to separate the solid and the liquid to obtain kaolin, the soaking time is 60 hours to 120 hours.

[0013] In a feasible embodiment of the present application, the viscosity of the intercalant is 2.5 to 5.5 mPa·s.

[0014] In a feasible implementation manner of the present application, in the step of mixing kaolin and an intercalating agent, grinding, and obtaining intercalated kaolin, the mass of the intercalating agent is 2% to 4% of the mass of the kaolin.

[0015] In a feasible implementation manner of the present application, the step of mixing kaolin with an intercalating agent, grinding, and obtaining intercalated kaolin specifically includes mixing kaolin with an intercalating agent, grinding until urea particles disappear, and then continuing to grind for 20 to 50 minutes to obtain intercalated kaolin.

[0016] In a feasible implementation manner of the present application, in the step of aging the intercalated kaolin and calcining at high temperature to obtain kaolin powder, the aging time is 3h to 6h.

[0017] In a feasible implementation of the present application, in the step of aging the intercalated kaolin and calcining at high temperature to obtain kaolin powder, the high temperature calcination temperature is 500° C. to 600° C., and the high temperature calcination time is 1.5 h to 3 h.

[0018] In a feasible embodiment of the present application, the high temperature calcination includes heating the temperature to 500° C. to 600° C. at a heating rate of 3° C. / min to 7° C. / min. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a Fourier transform infrared spectrum of the kaolin product of Example 1;

[0020] Figure 2 is the XRD pattern of the kaolin product of Example 1;

[0021] Figure 3 This is a N2 adsorption and desorption diagram of the kaolin product of Example 1;

[0022] Figure 4 This is a pore size comparison chart of the kaolin product in Example 1. DETAILED DESCRIPTION

[0023] In order to make the invention purpose, technical scheme and beneficial technical effect of the present application clearer, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the embodiments described in this specification are only for explaining the present application, not for limiting the present application.

[0024] For simplicity, only some numerical ranges are explicitly disclosed herein. However, any lower limit can be combined with any upper limit to form an unambiguous range; and any lower limit can be combined with other lower limits to form an unambiguous range, and any upper limit can be combined with any other upper limit to form an unambiguous range. In addition, although not explicitly stated, each point or single value between the range endpoints is included in the range. Thus, each point or single value can be combined with any other point or single value as its own lower limit or upper limit or with other lower limits or upper limits to form an unambiguous range.

[0025] In the description herein, when a composition is described as containing, comprising or including specific components, or when a process is described as containing, comprising or including specific process steps, it is expected that the composition of the present application also consists essentially of or consists of the components, and the process of the present application also consists essentially of or consists of the process steps.

[0026] The use of the terms "including," "comprising," "containing," and "having" should generally be interpreted as open ended and non-limiting unless expressly stated otherwise.

[0027] In the description of this article, it should be noted that, unless otherwise specified, “above” and “below” are inclusive of the number itself, and the “multiple” in “one or more” means more than two.

[0028] The above invention summary of the present application is not intended to describe each disclosed embodiment or each implementation in the present application. The following description more specifically illustrates exemplary embodiments. In many places throughout the application, guidance is provided by a series of examples, which can be used in various combinations. In each embodiment, enumeration is only used as a representative group and should not be interpreted as exhaustive.

[0029] The present application provides a urea intercalation stripping method of kaolin, comprising:

[0030] The urea intercalation stripping method of kaolin in the present application comprises:

[0031] The kaolinite is crushed and sieved to obtain a coarse-screened ore powder; the coarse-screened ore powder is soaked in an acidic solution to separate the solid and the liquid to obtain kaolin;

[0032] The urea granules and water are prepared in a mass ratio of 1: (0.3-0.5) to obtain an intercalation agent; the kaolin and the intercalation agent are mixed and ground to obtain intercalated kaolin;

[0033] The intercalated kaolin is aged and calcined at high temperature to obtain kaolin powder.

[0034] The intercalation method of the present application is between the solid phase intercalation method and the liquid phase intercalation method. An intercalation agent prepared by urea particles and water in the above-mentioned mass ratio range is selected, and the synergistic effect of the self-diffusion of urea small molecules and the assisted diffusion of water molecules is utilized to initially intercalate and strip the coarse mineral salt by competing with the kaolin layer for hydrogen bonding. Then, high-temperature calcination is performed and the high-temperature hydrolysis reaction of urea is utilized to consume hydroxyl hydrogen and compress the crystal structure of kaolin. The hydrolysis of urea produces NH3 and CO2 gases, which will cause the interlayer structure of kaolin to expand and contract, further improving the stripping effect and obtaining kaolin with small particle size.

[0035] In some embodiments, in the step of crushing and sieving kaolinite to obtain coarse-screened ore powder, the sieving includes sieving through a sieve of 50-150 meshes.

[0036] In some embodiments, in the step of soaking the coarse-sieved ore powder with an acidic solution and performing solid-liquid separation to obtain kaolin, the acidic solution comprises a 0.8 mol / L to 1.5 mol / L hydrochloric acid solution.

[0037] In some embodiments, in the step of soaking the coarse-screened ore powder with an acidic solution to separate the solid and the liquid to obtain kaolin, the soaking time is 60 hours to 120 hours.

[0038] The kaolin in the coarse-screened ore powder will be stratified and agglomerated after centrifugal sedimentation due to its high viscosity, while the non-clay impurities such as sand, stone, quartz, etc. in the mineral salt can be easily separated by screening.

[0039] In some embodiments, the viscosity of the intercalant is 2.5 to 5.5 mPa·s.

[0040] In some embodiments, in the step of mixing kaolin and an intercalant, and grinding to obtain intercalated kaolin, the mass of the intercalant is 2% to 4% of the mass of the kaolin.

[0041] In some embodiments, the step of mixing kaolin and an intercalating agent, grinding, and obtaining intercalated kaolin specifically includes mixing kaolin and an intercalating agent, grinding until urea particles disappear, and then continuing to grind for 20 minutes to 50 minutes to obtain intercalated kaolin.

[0042] In some embodiments, in the step of aging the intercalated kaolin and calcining at high temperature to obtain kaolin powder, the aging time is 3 hours to 6 hours.

[0043] In some embodiments, in the step of aging the intercalated kaolin and calcining at high temperature to obtain kaolin powder, the high temperature calcination temperature is 500° C. to 600° C., and the high temperature calcination time is 1.5 h to 3 h.

[0044] In some embodiments, high temperature calcination includes increasing the temperature to 500° C. to 600° C. at a heating rate of 3° C. / min to 7° C. / min.

[0045] Example

[0046] The following examples more specifically describe the disclosure of the present application, which are intended for illustrative purposes only, as it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the disclosure of the present application. Unless otherwise stated, all parts, percentages, and ratios reported in the following examples are by weight, and all reagents used in the examples are commercially available or synthesized according to conventional methods and can be used directly without further processing, and the instruments used in the examples are commercially available.

[0047] Example 1

[0048] This embodiment uses Ordos coal-based kaolinite from Inner Mongolia, and after crushing, breaking up and screening, 100-mesh kaolin is selected as the raw material. The raw material is subjected to elemental analysis to obtain kaolin with the composition characteristics shown in Table 1.

[0049] After the raw material is soaked and stirred in 1 mol / L hydrochloric acid solution for three days, it is centrifuged for cleaning and sedimentation, and then the sample is dried at 60°C and sieved for separation. Urea granules are selected, pure water is added to the urea granules, the mass ratio of urea to water is 0.5, and the mixture is mixed and stirred to obtain viscous fine urea granules, which are the kaolin intercalation agent.

[0050] An intercalating agent is added to the kaolin, the mass of the intercalating agent being 3% of the mass of the kaolin, and the kaolin is finely ground until the urea particles completely disappear, and then the grinding is continued for 30 minutes to obtain intercalated kaolin.

[0051] After aging the intercalated kaolin at room temperature for 4 hours, the temperature was raised to 550°C at 5°C per minute and calcined for 2 hours. Finally, the final sample was ground twice.

[0052] Figure 1 The FTIR images of Example 1 and the original soil are shown at 3600 cm -1 The left and right are the characteristic peaks of hydroxyl. After treatment, the characteristic peaks are greatly weakened, indicating that the sample has consumed hydroxyl hydrogen very well. Figure 2 The XRD diagrams of Example 1, the original soil and Comparative Example 1 show that part of the 6-coordinated alumina in the kaolin layer changes to 4-coordinated alumina, and the overall crystal form changes to an amorphous structure. Figure 3 , 4 The N2 adsorption and desorption diagrams of Example 1 and the original soil as well as the pore size distribution diagram are given.

[0053] Example 2

[0054] Compared with Example 1, the difference is that the mass ratio of urea granules to water is 1:0.4.

[0055] Example 3

[0056] Compared with Example 1, the difference is that the mass ratio of urea granules to water is 1:0.3.

[0057] Example 4

[0058] Compared with Example 1, the difference is that the mass of the intercalant is 5% of the mass of the kaolin.

[0059] Example 5

[0060] Compared with Example 1, the difference is that the mass of the intercalant is 1% of the mass of the kaolin.

[0061] Example 6

[0062] Compared with Example 1, the difference is that the high-temperature calcination temperature is 450° C. and the calcination time is 4 hours.

[0063] Example 7

[0064] Compared with Example 1, the difference is that the high-temperature calcination temperature is 650° C. and the calcination time is 2 h.

[0065] Comparative Example 1

[0066] The process of this comparative example is to calcine kaolin at 1500℃ twice at high temperature, which belongs to the calcination process of kaolin. After crushing, breaking and sieving the kaolinite salt, 300 to 500 mesh high fine kaolin is selected and first calcined at 1000℃. The purpose of this calcination is to burn off the reducing substances such as C and S in the kaolin and increase the whiteness of the kaolin. Then, calcination at 1500℃ for 8 hours is carried out to obtain the final sample. Table 3 shows the main element composition of kaolin after two calcination processes.

[0067] Comparative Example 2

[0068] The process of this comparative example is water-treated kaolin, and the blank control group without intercalation agent. Pure water is added to the 100-mesh crude ore and stirred for 48 hours, ethanol centrifuged 3 times, dried at 60°C overnight, calcined at 550°C for 2 hours after secondary grinding, and cooled naturally to obtain the final sample. The water-treated kaolin sample is equivalent to the flotation process, which washes and filters out the lighter impurities in the soil to obtain relatively clean kaolin.

[0069] Comparative Example 3

[0070] The process of this comparative example is to treat kaolin by liquid phase intercalation method, which is different from Example 1 in that a large amount of water is added as a solvent, and a stirring process is added. First, water 5 times the mass of kaolin is added, and urea particles with a mass percentage of 50% of kaolin are added respectively, and finally 100 mesh kaolin is added, stirred at room temperature for 48 hours, centrifuged with ethanol 3 times, dried at 60°C overnight, calcined at 550°C for 2 hours after secondary grinding, and naturally cooled to obtain the final sample. The sample obtained by the liquid phase intercalation method is fine, with fewer impurities, and the reaction is mild during calcination. Calcination will not cause sample expansion and contraction, and the sample will not be porous and broken. However, the required process is complicated and time-consuming, and the aggregation hydrogen bonding effect of the solvent will greatly weaken the self-diffusion effect of urea entering the interlayer. The obtained sample has similar physical and chemical properties to Comparative Example 2.

[0071] Comparative Example 4

[0072] The process of this comparative example is to treat kaolin by solid phase intercalation method. The difference from Example 1 is that no solvent is added and only a crushing and grinding process is used. Urea particles with a mass percentage of 50% kaolin are added to kaolin, and fine grinding is performed until the urea disappears completely. After aging at room temperature for 4 hours, it is calcined at 550°C for 2 hours, and the temperature is naturally lowered to obtain the final sample. The sample obtained by the solid phase intercalation method is relatively rough and has an uneven particle size distribution. After calcination at 550°C, the urea decomposition reaction is violent and occurs almost immediately, the sample expands and contracts, and the final sample appears fluffy and porous. The solid phase intercalation method is simple and time-consuming, but it cannot achieve a good intercalation effect only through urea self-diffusion and grinding.

[0073] Compared with Comparative Examples 3 and 4, Example 1 is more suitable for intercalation and exfoliation of kaolin from the perspective of molecular diffusion, and is simpler and more time-saving from the perspective of process and time consumption.

[0074] Comparative Example 5

[0075] Compared with Example 1, the difference is that the mass ratio of urea granules to water is 1:0.8.

[0076] Table 1 Element composition of kaolinite in the Ordos coal series in Inner Mongolia

[0077]

[0078] Table 2 Test results of the final product kaolin of each embodiment and comparative example

[0079]

[0080]

[0081] Table 3 Element composition of kaolin after calcination process in comparative example 1

[0082]

[0083] Table 2 shows the BET characterization results of the treated kaolin and the original soil. It can be seen that compared with the comparative example, the specific surface area and pore volume data of the sample in the embodiment of the present application are significantly increased, while the pore size distribution has basically not changed, indicating that the intercalation and exfoliation of kaolin is achieved without changing the pore structure. The intercalation rate of the embodiment of the present application is high, and the particle size of the obtained kaolin product is small.

[0084] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A urea intercalation stripping method for kaolin, characterized in that: include: The kaolinite is crushed and sieved to obtain coarse-screened ore powder; Using an acidic solution to soak the coarsely screened ore powder, separate the solid from the liquid, and obtain kaolin; The urea granules and water are prepared in a mass ratio of 1: (0.3-0.5) to obtain an intercalation agent; The kaolin and the intercalation agent are mixed and ground to obtain intercalated kaolin; The intercalated kaolin is aged and calcined at high temperature to obtain kaolin powder.

2. The urea intercalation stripping method of kaolin according to claim 1, characterized in that: In the step of crushing and sieving the kaolin salt to obtain coarse-screened ore powder, the sieving includes sieving through a sieve with a mesh size of 50 to 150.

3. The urea intercalation stripping method of kaolin according to claim 1, characterized in that: In the step of soaking the coarse-screened ore powder with an acidic solution to separate the solid from the liquid to obtain kaolin, the acidic solution comprises a 0.8 mol / L to 1.5 mol / L hydrochloric acid solution.

4. The urea intercalation stripping method of kaolin according to claim 1, characterized in that: In the step of soaking the coarse-screened ore powder with an acidic solution to separate the solid and the liquid to obtain kaolin, the soaking time is 60 hours to 120 hours.

5. The urea intercalation stripping method of kaolin according to claim 1, characterized in that: In the step of mixing the kaolin and the intercalating agent, grinding, and obtaining the intercalated kaolin, the mass of the intercalating agent is 2% to 4% of the mass of the kaolin.

6. The urea intercalation stripping method of kaolin according to claim 1, characterized in that: The step of mixing the kaolin and the intercalating agent, grinding, and obtaining the intercalated kaolin specifically includes mixing the kaolin and the intercalating agent, grinding until urea particles disappear, and then continuing to grind for 20 minutes to 50 minutes to obtain the intercalated kaolin.

7. The urea intercalation stripping method of kaolin according to claim 1, characterized in that: In the step of aging the intercalated kaolin and calcining at high temperature to obtain kaolin powder, the aging time is 3h to 6h.

8. The urea intercalation stripping method of kaolin according to claim 1, characterized in that: In the step of aging the intercalated kaolin and calcining at high temperature to obtain kaolin powder, the temperature of the high temperature calcination is 500° C. to 600° C., and the time of the high temperature calcination is 1.5 h to 3 h.

9. The urea intercalation stripping method of kaolin according to any one of claims 1 to 8, characterized in that: The high temperature calcination includes heating the temperature to 500° C. to 600° C. at a heating rate of 3° C. / min to 7° C. / min.

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