Molecular sieve and spent bleaching clay recycling method

Abstract

The invention discloses a molecular sieve and a spent bleaching clay recycling method, and belongs to the field of environmental protection and resource recycling. According to the waste white clay recycling method, the oil-containing waste white clay is used as a raw material, crystallization is performed by additionally supplementing a sodium silicate compound and an aluminum source, adjusting the ratio of silicon to aluminum and the like and performing hydrothermal reaction in the presence of alkali, so that the molecular sieve is prepared, and the prepared molecular sieve does not need to be subjected to further oil removal treatment; the method can be directly applied to the fields of adsorption, air separation, catalysis and the like, so that the whole spent bleaching clay recycling method is simple in process and low in energy consumption, the preparation cost is effectively reduced, and the economic value is improved.

Description

Technical Field

[0001] The present application belongs to the field of environmental protection and resource recycling, and specifically, relates to a molecular sieve and a method for recycling waste clay. Background Art

[0002] The decolorized waste clay is solid waste and is usually handed over to environmental protection companies for incineration and landfill treatment. Some companies will choose solvent extraction, extrusion and other methods to recover the residual oil in the waste clay. Most existing technologies use solvent extraction to mix the oil-containing waste clay with the extractant and then settle and evaporate to separate. However, pigment impurities are adsorbed on the surface and pores of the clay, occupying the pores of the clay. It is difficult to wash away all the pigment impurities by pickling, extraction and other methods. The adsorption performance of the clay obtained in this way is reduced, and the low-quality recovered oil is difficult to use. In addition, the process is complicated and energy consumption is high. Summary of the invention

[0003] The present application provides a molecular sieve and a method for recycling waste clay. The method for recycling waste clay can directly use waste clay as raw material and process it to prepare a molecular sieve. Not only is the process simple and energy-saving, but the prepared molecular sieve can also be applied to fields such as adsorption, air separation and catalysis.

[0004] The embodiment of the present application is implemented as follows:

[0005] In a first aspect, the present application example provides a method for recycling waste clay, which comprises:

[0006] The oil-containing waste clay, sodium silicate compounds, aluminum source and alkali are mixed in water to carry out a hydrothermal reaction. After the reaction is completed, the mixture is cooled, the solid-liquid separation is performed, and the obtained solid product is washed and dried to obtain a molecular sieve.

[0007] In the waste clay recycling method of the present application, oil-containing waste clay can be directly used as raw material, and a molecular sieve can be obtained by additionally adding sodium silicate compounds and aluminum sources, adjusting the ratio of silicon and aluminum, and crystallizing through a hydrothermal reaction in the presence of an alkali. Although there is a trace amount of waste oil in the prepared molecular sieve, it has little effect on its performance. Therefore, the prepared molecular sieve does not need further oil removal treatment and can be directly applied to fields such as adsorption, air separation and catalysis, etc., so that the entire waste clay recycling method has a simple process, low energy consumption, and effectively reduces the preparation cost, thereby improving the economic value.

[0008] In some optional embodiments, the method for recycling spent clay does not include a calcination step.

[0009] In some optional embodiments, the oil content of the oil-containing waste clay is less than 30%.

[0010] In some optional embodiments, the sodium silicate compound is water-soluble, the aluminum source is water-soluble, and the alkali is a strong alkali; wherein the mass ratios of the added amounts of oil-containing waste clay, the sodium silicate compound, the aluminum source, and the alkali are 10:(12-26):(4-16):(2-13) respectively.

[0011] In some optional embodiments, the mass ratios of the added amounts of oil-containing waste clay, sodium silicate compounds, aluminum source, and alkali are 10:(24.5-25.5):(15-15.5):(12.5-13) respectively.

[0012] In some optional embodiments, the sodium silicate compound includes at least one of soluble sodium silicate powder, anhydrous sodium metasilicate, sodium metasilicate pentahydrate and sodium metasilicate nonahydrate.

[0013] In some alternative embodiments, the aluminum source includes sodium metaaluminate and / or aluminum sulfate.

[0014] In some alternative embodiments, the base includes sodium hydroxide and / or potassium hydroxide.

[0015] In some optional embodiments, the sodium silicate compound is sodium metasilicate nonahydrate, the aluminum source is sodium aluminate, and the alkali is sodium hydroxide.

[0016] In some optional embodiments, the mixing temperature is 45-55°C.

[0017] In some optional embodiments, mixing includes:

[0018] Mix the oily waste clay, sodium silicate compounds, alkali and water, and dissolve them at 45-55°C to obtain a suspension;

[0019] dissolving an aluminum source in water to obtain an aluminum-containing solution;

[0020] The suspension and the aluminum-containing solution were mixed with stirring at 45-55° C. for 50-90 min.

[0021] In some optional embodiments, the temperature of the hydrothermal reaction is 90-150° C., and the time of the hydrothermal reaction is 3-24 h.

[0022] The waste clay recycling method also includes collecting waste liquid, separating and removing the oil layer, diluting the waste liquid by 1-2 times, adding a demulsifier to demulsify and stratify the waste liquid, and adding acid to adjust the pH value to 6-9;

[0023] The waste liquid includes the liquid obtained after solid-liquid separation and the liquid produced by washing, and the liquid produced by washing is alkaline.

[0024] In some optional embodiments, the ratio of the amount of demulsifier added to the amount of waste liquid added is (4.5-6) ​​g:1L.

[0025] In a second aspect, the present application provides an example of a molecular sieve, which is produced by the waste clay recycling method provided in the first aspect of the present application.

[0026] In some optional embodiments, the molecular sieve is 4A molecular sieve. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0028] Figure 1 This is a schematic diagram of the waste liquid produced in Example 1 of the present application before and after demulsification and stratification and after acid addition and adjustment;

[0029] Figure 2 This is a SEM image of the molecular sieve prepared in Example 1 of the present application;

[0030] Figure 3 This is the XRD diagram of the molecular sieve prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0031] The embodiments of the present application will be described in detail below in conjunction with the examples, but it will be appreciated by those skilled in the art that the following examples are only used to illustrate the present application and should not be considered as limiting the scope of the present application. In the examples, if specific conditions are not specified, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0032] The following is a specific description of the molecular sieve and waste clay recycling method of the present application embodiment:

[0033] The present application provides a method for recycling waste clay, which comprises:

[0034] The oil-containing waste clay, sodium silicate compounds, aluminum source and alkali are mixed in water to carry out a hydrothermal reaction. After the reaction is completed, the mixture is cooled, the solid-liquid separation is performed, and the obtained solid product is washed and dried to obtain a molecular sieve.

[0035] In this application, the oil-containing waste clay refers to the clay mud after decolorization in the oil refining process, which contains unsaturated oil and other harmful substances. The oil-containing waste clay used in this application does not need additional pretreatment and can be directly used as a raw material to prepare molecular sieves.

[0036] The oily waste clay contains a large amount of silicon dioxide and aluminum trioxide. Therefore, by additionally adding sodium silicate compounds and aluminum sources, adjusting the ratio of silicon and aluminum, and hydrothermally reacting in the presence of alkali, molecular sieve crystals are generated, followed by solid-liquid separation, washing and drying to obtain molecular sieves. At the same time, the waste clay recycling method of the present application is adopted. After the hydrothermal reaction, floating oil appears on the top layer. By solid-liquid separation and washing, most of the waste oil will be removed. Although there is a trace amount of waste oil in the finished molecular sieve, it has little effect on its performance. Therefore, the prepared molecular sieve does not need to be further deoiled and can be directly applied to fields such as adsorption, air separation and catalysis, so that the entire waste clay recycling method has a simple process, low energy consumption, and effectively reduces the preparation cost, thereby improving the economic value.

[0037] It is understandable that the oil-containing waste clay contains not only oil but also certain pigments and organic matter, etc., which are not limited here.

[0038] In some optional embodiments, the oil content of the oil-containing waste clay is within 30%.

[0039] The oil content of the oil-containing waste clay is within 30% means that the oil content of the oil-containing waste clay is greater than 0 and less than or equal to 30%. That is, the preparation method of the molecular sieve adopted in this application can directly use the waste clay with high oil content as raw material to directly prepare the molecular sieve, effectively simplifying the preparation process and reducing the production cost.

[0040] Exemplarily, the oil content of the oil-containing waste clay is any value among 5%, 10%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, or between any two values.

[0041] Among them, the sodium silicate compound is water-soluble, the aluminum source is water-soluble, the alkali is a strong alkali, and the mass ratio of the added amount of oil-containing waste clay, sodium silicate compound, aluminum source and alkali can be 10:(9-29):(3-19):(1.5-15).

[0042] In some optional embodiments, the sodium silicate compound is water-soluble, the aluminum source is water-soluble, the alkali is a strong alkali, and the mass ratios of the added amounts of oil-containing waste clay, the sodium silicate compound, the aluminum source, and the alkali are 10:(12-26):(4-16):(2-13) respectively.

[0043] By controlling the mass ratio of the added amount of each raw material within the above range, it is beneficial for the oil-containing waste clay to react with other raw materials to prepare a molecular sieve with excellent performance and extremely low oil content.

[0044] In some optional embodiments, the mass ratios of the added amounts of oil-containing waste clay, sodium silicate compounds, aluminum source, and alkali are 10:(24.5-25.5):(15-15.5):(12.5-13) respectively.

[0045] By controlling the mass ratio of the added amount of each raw material within the above range, it is beneficial to prepare a molecular sieve with good performance and extremely low oil content.

[0046] In some optional embodiments, the sodium silicate compound includes at least one of soluble sodium silicate powder, anhydrous sodium metasilicate, sodium metasilicate pentahydrate and sodium metasilicate nonahydrate.

[0047] Silicon is provided by the water-soluble sodium silicate compounds to adjust the silicon-aluminum ratio in the molecular sieve, while also avoiding the introduction of impurities.

[0048] In some alternative embodiments, the aluminum source includes sodium metaaluminate and / or aluminum sulfate.

[0049] Silicon is provided by the water-soluble sodium silicate compounds to adjust the silicon-aluminum ratio in the molecular sieve, while also reducing the introduction of impurities.

[0050] In some alternative embodiments, the base includes sodium hydroxide and / or potassium hydroxide.

[0051] In some optional embodiments, the sodium silicate compound is sodium metasilicate nonahydrate, the aluminum source is sodium aluminate, and the alkali is sodium hydroxide.

[0052] The above raw materials have good matching effect and are conducive to the production of sodium A-type molecular sieve.

[0053] The mixing may be performed at room temperature.

[0054] In some optional embodiments, the mixing temperature is 45-55°C.

[0055] Controlling the mixing temperature within the above range is not only conducive to fully dissolving the sodium silicate compound, the aluminum source, and the alkali in water, but also helps to reduce the difficulty of dissolution, improve production efficiency, and prevent side reactions.

[0056] Illustratively, the mixing temperature is any one of 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C or between any two values.

[0057] Optionally, the mixing temperature is 48°C-53°C.

[0058] The mixing may be one-step mixing or step-by-step mixing.

[0059] For example, the mixing includes: mixing the oil-containing waste clay, the aluminum source and water to obtain a suspension;

[0060] Dissolve a sodium silicate compound and an alkali in water at 45-55° C. to obtain a mixed solution;

[0061] The suspension and the mixed solution were stirred at 45-55°C for 50-90 min.

[0062] In some optional embodiments, mixing includes:

[0063] Mix the oily waste clay, sodium silicate compounds, alkali and water, and dissolve them at 45-55°C to obtain a suspension;

[0064] dissolving an aluminum source in water to obtain an aluminum-containing solution;

[0065] The suspension and the aluminum-containing solution were mixed with stirring at 45-55° C. for 50-90 min.

[0066] Sodium silicate compounds have poor solubility at room temperature, so mixing with water at 45-55°C is conducive to their full dissolution.

[0067] Since the oil-containing waste clay also contains a small amount of aluminum, the oil-containing waste clay, sodium silicate compounds, alkali and water are mixed to disperse the oil-containing waste clay in the water and dissolve the sodium silicate compounds in the water to obtain a suspension.

[0068] In the present application, the method of first forming a suspension and a mixed solution, and then stirring and mixing the suspension with the aluminum-containing solution is adopted, which is conducive to the production of a gel. During the subsequent hydrothermal reaction, this gel can be dissolved and quickly produce a large number of fine crystal nuclei for the crystallization reaction, which is conducive to the synthesis of molecular sieves with small particle size and large exchange capacity.

[0069] Among them, stirring and mixing the suspension and the aluminum-containing solution at 45-55° C. for 50-90 minutes is conducive to uniform mixing of the two and generating a gel. Exemplarily, the stirring and mixing time is any value of 50 minutes, 60 minutes, 70 minutes, 80 minutes, 90 minutes or between any two values. The specific stirring time can be selected within the above range according to actual needs.

[0070] In some optional embodiments, the temperature of the hydrothermal reaction is 90-150° C., and the time of the hydrothermal reaction is 3-24 h.

[0071] Controlling the temperature and time of the hydrothermal reaction within the above range is beneficial to the crystallization reaction to obtain the molecular sieve.

[0072] Exemplarily, the temperature of the hydrothermal reaction is any value among 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or between any two values, and the time of the hydrothermal reaction is any value among 3h, 5h, 7h, 10h, 12h, 15h, 18h, 20h, 24h or between any two values.

[0073] Optionally, the temperature of the hydrothermal reaction is 95-120° C., and the time of the hydrothermal reaction is 3-18 h.

[0074] After the hydrothermal reaction, solid-liquid separation is performed. The solid-liquid separation method includes but is not limited to filtration, separation after centrifugation, or direct removal of the supernatant after clarification.

[0075] After solid-liquid separation, the solid product is washed. Water can be used for washing to remove surface impurities and unreacted alkali loaded on its surface. Therefore, whether the solid product is cleaned can be directly determined by testing whether the pH value of the supernatant after washing is alkaline.

[0076] Since the alkali content is limited, the obtained solid product can be optionally washed until the pH of the supernatant is 8-9, which means that it is basically clean and can be subsequently dried.

[0077] The water and unreacted components are removed by drying, wherein the drying methods include but are not limited to air drying and oven drying, etc. In order to improve the preparation efficiency, the drying method is usually adopted, for example, drying at a temperature of 80-120°C.

[0078] It should be noted that in the process of adopting the above-mentioned waste clay recycling method, waste liquid is produced, and the waste liquid cannot be discharged directly.

[0079] Therefore, in some optional embodiments, the method for recycling waste clay also includes collecting waste liquid, separating and removing the oil layer, diluting the waste liquid by 1-2 times, adding a demulsifier to demulsify and stratify the waste liquid, and adding acid to adjust the pH value to 6-9; wherein the waste liquid includes the liquid obtained after solid-liquid separation and the liquid produced by washing, and the liquid produced by washing is alkaline.

[0080] The above-mentioned method is used to treat waste liquid and can meet relevant emission standards.

[0081] The demulsifier can be selected according to actual needs, and its composition is not limited here.

[0082] In some optional embodiments, the ratio of the amount of demulsifier added to the amount of waste liquid added is (4.5-6) ​​g:1L.

[0083] Controlling the ratio of the added amounts of the two within the above range is beneficial to fully eliminate the emulsification effect and facilitate the subsequent removal of the oil layer.

[0084] Exemplarily, the ratio of the amount of demulsifier added to the waste liquid is any one of 4.5 g:1L, 4.8 g:1L, 5.0 g:1L, 5.3 g:1L, 5.5 g:1L, 5.8 g:1L, 6.0 g:1L or between any two values.

[0085] The present application also provides a molecular sieve produced by the above-mentioned waste clay recycling method, and the molecular sieve can be applied to the fields of adsorption, air separation, catalysis, etc.

[0086] In some optional embodiments, the molecular sieve is 4A molecular sieve.

[0087] The molecular sieve and waste clay recycling method of the present application are further described in detail below in conjunction with the embodiments.

[0088] In the following examples and comparative examples, unless otherwise specified, all reagents used were of analytical grade, and all solutions and suspensions were prepared with deionized water.

[0089] Example 1

[0090] A method for recycling waste clay, comprising:

[0091] 10 g of waste clay with an oil content (mass content) of about 30%, 25 g of sodium silicate nonahydrate and 12.72 g of sodium hydroxide were added to 200 ml of pure water in a polytetrafluoroethylene bottle, and stirred and dissolved at 50°C to obtain a suspension.

[0092] 15.25 g of sodium aluminate was dissolved in 71 ml of pure water to obtain a sodium aluminate solution.

[0093] The sodium aluminate solution was poured into the polytetrafluoroethylene bottle containing the suspension, and the mixture was stirred at 50°C for 1 hour, and then placed in an oven for reaction at 100°C for 4 hours. After the reaction was completed, the mixture was cooled and the solid and liquid were separated.

[0094] The waste liquid obtained after solid-liquid separation and the waste liquid produced by washing are mixed together, separated and the oil layer is removed, and then diluted by half. At this time, the waste liquid has the following form: Figure 1 As shown in part a, add demulsifier at 5 g / L, such as Figure 1 The waste liquid shown in part b is demulsified and separated. Acid is added to adjust the pH of the remaining waste liquid to 6-9, and finally the waste liquid is Figure 1 As shown in part c, it meets the third-level comprehensive sewage discharge standard.

[0095] The solid product obtained after solid-liquid separation is washed with pure water until the pH of the supernatant is between 8 and 10, and then the product is dried at 105° C. to obtain a molecular sieve.

[0096] in Figure 2The SEM image of the molecular sieve obtained by drying the water is shown in Figure 1. Figure 2 It can be seen that the product obtained by drying the water has a clear particle structure, a regular cubic structure, and a relatively uniform grain size, which is a unique morphology of molecular sieves.

[0097] Figure 3 This is the XRD diagram of the molecular sieve obtained by drying the moisture. Figure 3 It can be seen that the molecular sieve contains few impurities, and the position and intensity of the X-ray diffraction peak are consistent with the basic characteristics of sodium A type 4A type molecular sieve.

[0098] Example 2

[0099] A method for recycling waste clay, comprising:

[0100] 10 g of waste clay with an oil content (mass content) of about 20%, 12.69 g of sodium silicate nonahydrate and 2.32 g of sodium hydroxide were added to 150 ml of pure water in a polytetrafluoroethylene bottle, and stirred and dissolved at 50°C to obtain a suspension.

[0101] 4.32 g of sodium aluminate was dissolved in 41 ml of pure water to obtain a sodium aluminate solution.

[0102] Pour the sodium aluminate solution into the polytetrafluoroethylene bottle containing the suspension, stir and mix at 50°C for 1 hour, and then place it in an oven for reaction at 100°C for 4 hours. After the reaction is completed, cool and pour out the supernatant, wash the product with distilled water until the pH is below 10, and dry to obtain the finished molecular sieve.

[0103] Example 3

[0104] 10 g of waste clay with an oil content (mass content) of about 25%, 25.58 g of sodium silicate nonahydrate and 11.97 g of sodium hydroxide were added to 210 ml of pure water in a polytetrafluoroethylene bottle, and stirred and dissolved at 50°C to obtain a suspension.

[0105] 15.62 g of sodium aluminate was dissolved in 74 ml of pure water to obtain a sodium aluminate solution.

[0106] Pour the sodium aluminate solution into the polytetrafluoroethylene bottle containing the suspension, mix and stir at 50°C for 1 hour, and then place it in an oven for reaction at 100°C for 4 hours. After the reaction is completed, cool and pour out the supernatant, wash the product with distilled water until the pH is below 10, and dry it to obtain the finished molecular sieve.

[0107] Example 4

[0108] 10 g of waste clay with an oil content (mass content) of about 40%, 25 g of sodium silicate nonahydrate and 12.72 g of sodium hydroxide were added to 200 ml of pure water in a polytetrafluoroethylene bottle, and stirred and dissolved at 50°C to obtain a suspension.

[0109] 15.25 g of sodium aluminate was dissolved in 41 ml of pure water to obtain a sodium aluminate solution.

[0110] Pour the sodium aluminate solution into the polytetrafluoroethylene bottle containing the suspension, stir and mix at 50°C for 1 hour, and then place it in an oven for reaction at 100°C for 4 hours. After the reaction is completed, cool and pour out the supernatant, wash the product with distilled water until the pH is below 10, and dry to obtain the finished molecular sieve.

[0111] Example 5

[0112] 10 g of waste clay with an oil content (mass content) of about 20%, 9.6 g of sodium silicate nonahydrate and 1.5 g of sodium hydroxide were added to 194 ml of pure water in a polytetrafluoroethylene bottle, and stirred and dissolved at 50°C to obtain a suspension.

[0113] 3.1 g of sodium aluminate was mixed and dissolved in 40 ml of pure water to obtain a sodium aluminate solution.

[0114] Pour the sodium aluminate solution into the polytetrafluoroethylene bottle containing the suspension, stir and mix at 50°C for 1 hour, and then place it in an oven for reaction at 100°C for 4 hours. After the reaction is completed, cool and pour out the supernatant, wash the product with distilled water until the pH is below 10, and dry to obtain the finished molecular sieve.

[0115] Example 6

[0116] 10 g of waste clay with an oil content (mass content) of about 25%, 28.44 g of sodium silicate nonahydrate and 14.05 g of sodium hydroxide were added to 284 ml of pure water in a polytetrafluoroethylene bottle, and stirred and dissolved at 50°C to obtain a suspension.

[0117] 18.29 g of sodium aluminate was dissolved in 85 ml of pure water to obtain a sodium aluminate solution.

[0118] Pour the sodium aluminate solution into the polytetrafluoroethylene bottle containing the suspension, stir and mix at 50°C for 1 hour, and then place it in an oven for reaction at 100°C for 4 hours. After the reaction is completed, cool and pour out the supernatant, wash the product with distilled water until the pH is below 10, and dry to obtain the finished molecular sieve.

[0119] Test example

[0120] Performance tests were conducted on Examples 1-6 and commercial molecular sieves available on the market, and the results are shown in Table 1. The control group was a purchased commercial molecular sieve, which was a commercially available product and initially had spherical particles, which were ground and then tested.

[0121] Among them, the static water adsorption method refers to the saturated sodium chloride solution method of GBT6287-2021.

[0122] The preparation process of the control group is to dissolve sodium silicate and sodium hydroxide in water in a reactor, dissolve sodium aluminate and add it into the reactor to mix evenly, heat it to 120℃ and keep it for 4 hours, then cool it to room temperature, filter it in a filter and wash it. Then dry it, add an appropriate amount of binder, pore-forming agent and foaming agent, press it into a sphere, and calcine it at 600℃ to obtain the finished spherical molecular sieve.

[0123] Table 1 Test results

[0124]

[0125] According to the comparative examples and the control group, the waste clay recycling method adopted in the present application can effectively prepare the waste clay into a molecular sieve with similar performance to that of the control group without pretreating the waste clay and sintering during the recycling process, so that the entire waste clay recycling method has a simple process, low energy consumption, and effectively reduces the preparation cost, thereby improving the economic value.

[0126] Among them, it can be seen from Examples 1 and 4 that the oil content of the oil-containing waste clay is 20%-30%, which is more conducive to obtaining a molecular sieve with better performance.

[0127] According to the comparison of Examples 1-3 and 4-5, it can be seen that the mass ratio of the added amount of oil-containing waste clay, water-soluble sodium silicate compounds, water-soluble aluminum source, and strong alkali is within the range of 10:(12-26):(4-16):(2-13), which is more conducive to obtaining a molecular sieve with good performance.

[0128] The above are only specific embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for recycling waste clay, characterized in that: include: The oil-containing waste clay, sodium silicate compounds, aluminum source and alkali are mixed in water to carry out a hydrothermal reaction. After the reaction is completed, the mixture is cooled, the solid-liquid separation is performed, and the obtained solid product is washed and dried to obtain a molecular sieve.

2. The method for recycling waste clay according to claim 1, characterized in that: The method for recycling waste clay does not include a calcination step.

3. The method for recycling waste clay according to claim 1, characterized in that: The oil content of the oil-containing waste clay is less than 30%.

4. The method for recycling waste clay according to claim 1, characterized in that: The sodium silicate compound is water-soluble, the aluminum source is water-soluble, and the base is a strong base; Among them, the mass ratios of the added amounts of the oil-containing waste clay, the sodium silicate compound, the aluminum source, and the alkali are 10:(12-26):(4-16):(2-13) respectively.

5. The method for recycling waste clay according to claim 4, characterized in that: The mass ratios of the added amounts of the oil-containing waste clay, the sodium silicate compound, the aluminum source, and the alkali are 10:(24.5-25.5):(15-15.5):(12.5-13) respectively.

6. The method for recycling waste clay according to claim 1, characterized in that: The sodium silicate compound includes at least one of soluble sodium silicate powder, anhydrous sodium metasilicate, pentahydrate sodium metasilicate and nonahydrate sodium metasilicate.

7. The method for recycling waste clay according to claim 1, characterized in that: The aluminum source includes sodium metaaluminate and / or aluminum sulfate.

8. The method for recycling waste clay according to claim 1, characterized in that: The base includes sodium hydroxide and / or potassium hydroxide.

9. The method for recycling waste clay according to claim 1, characterized in that: The sodium silicate compound is sodium metasilicate nonahydrate, the aluminum source is sodium metaaluminate, and the alkali is sodium hydroxide.

10. The method for recycling waste clay according to any one of claims 1 to 9, characterized in that: The mixing temperature is 45-55°C.

11. The method for recycling waste clay according to claim 10, characterized in that: The mixing includes: Mixing the oil-containing waste clay, the sodium silicate compound, the alkali and water, and dissolving them at 45-55° C. to obtain a suspension; dissolving the aluminum source in water to obtain an aluminum-containing solution; The suspension and the aluminum-containing solution are stirred and mixed at 45-55° C. for 50-90 min.

12. The method for recycling waste clay according to any one of claims 1 to 8, characterized in that: The temperature of the hydrothermal reaction is 90-150° C., and the time of the hydrothermal reaction is 3-24 hours.

13. The method for recycling waste clay according to any one of claims 1 to 9, characterized in that: The waste clay recycling method further comprises collecting waste liquid, separating and removing the oil layer, diluting the waste liquid by 1-2 times, adding a demulsifier to demulsify and stratify the waste liquid, and adding acid to adjust the pH value to 6-9; Wherein, the waste liquid includes the liquid obtained after solid-liquid separation and the liquid produced by washing; the liquid produced by washing is alkaline.

14. The method for recycling waste clay according to claim 13, characterized in that: The ratio of the added amount of the demulsifier to the added amount of the waste liquid is (4.5-6) ​​g:1L.

15. A molecular sieve, characterized in that: The waste clay is prepared by the waste clay recycling method described in any one of claims 1 to 14.

16. The molecular sieve according to claim 15, characterized in that The molecular sieve is 4A molecular sieve.

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