Method for preparing soil conditioner from red mud and soil conditioner

Abstract

The invention relates to the technical field of red mud solid waste recycling, in particular to a method for preparing a soil conditioner from red mud and the soil conditioner. The red mud comprises alkaline components, and the method comprises the following steps: mixing an activating agent, a modifying agent, cellulose-containing waste biomass, water and the red mud to obtain red mud mixed slurry containing the alkaline components and the cellulose; the method comprises the following steps: carrying out co-hydrothermal reaction on red mud mixed slurry containing alkaline components and cellulose by using reaction raw material gas containing carbon dioxide to obtain a mixed product; and carrying out post-treatment on the mixed product to obtain the soil conditioner. According to the method, under the co-reaction action of carbon dioxide and red mud mixed slurry, fine fiber bodies can be exposed out of the surface of the waste biomass, the fine fiber bodies and the red mud can form a three-dimensional fused copolymer structure, the specific surface area of the three-dimensional fused copolymer structure is 63.25 m < 2 > / g-70.85 m < 2 > / g, and the porosity of the three-dimensional fused copolymer structure is 82.17%-90.79%.

Description

Technical Field

[0001] The present application relates to the technical field of recycling red mud solid waste, and in particular to a method for preparing a soil conditioner using red mud and the soil conditioner. Background Art

[0002] Red mud is a general industrial solid waste with strong alkalinity produced in the process of producing alumina from bauxite. Depending on the iron oxide content of red mud, the appearance of red mud is red, reddish brown, dark red or gray. In addition, red mud has a high water content and contains harmful components such as heavy metals. Moreover, the comprehensive utilization rate of red mud is less than 10% at present, so the large-scale treatment of red mud is still a global problem. At present, using red mud to produce building materials is an effective way to consume red mud on a large scale. However, due to the high alkali content, fine particle size and complex composition of red mud, these defects of red mud will have a great impact on process production and product quality. Therefore, at present, most red mud is still stored in the form of open air. On the one hand, a large amount of red mud stored in the open air will occupy a large amount of land resources, and the maintenance cost of the storage site is high. On the other hand, a large amount of red mud stored in the open air will have the risk of dam breach and toxic and harmful substances seeping out. Therefore, the resource utilization of red mud has important practical significance, economic benefits and ecological benefits. At present, there are problems such as soil acidification, structural degradation, reduced organic matter content, lack of nutrients, poor water and fertilizer retention capacity in domestic farmland soil, which have largely restricted the development of agricultural production and rural economy. And with the aggravation of factors such as drought and semi-arid climate, bad farming methods and deforestation, these factors will cause the soil to suffer serious erosion, resulting in the gradual sandification and loss of fertility of the land, and then causing the productivity of farmland, forest farm, grassland and grassland to decline. In view of this situation of soil, most of the physical, chemical and biological properties of soil are improved by soil conditioners at present, so that soil can be more suitable for plant growth. However, existing soil conditioners are mostly synthesized and processed by organic extracts, natural minerals or artificial high molecular polymers, with high production costs and are not easy to industrial production.

[0003] In view of the above-mentioned defects of soil conditioners, red mud can be used as a raw material to prepare soil conditioners, but the addition of red mud will reduce the number of pore structures of the soil conditioner and reduce the specific surface area and porosity of the soil conditioner. Summary of the invention

[0004] The present application provides a method for preparing a soil conditioner using red mud and the soil conditioner to solve the following technical problem: how to increase the number of pore structures of the soil conditioner doped with red mud.

[0005] In a first aspect, the present application provides a method for preparing a soil conditioner using red mud, wherein the components of the red mud include alkaline components, and the method comprises:

[0006] Mixing an activator, a modifier, waste biomass containing cellulose and the red mud to obtain a red mud mixed slurry;

[0007] The reaction raw gas containing carbon dioxide is subjected to a co-hydrothermal reaction with the red mud mixed slurry to generate carbonate and form a three-dimensional fused copolymer structure to obtain a mixed product;

[0008] The mixed product is post-treated to obtain a soil conditioner.

[0009] Optionally, the temperature of the co-hydrothermal reaction is 80°C to 200°C, and the time of the co-hydrothermal reaction is 4h to 20h.

[0010] Optionally, the volume V1 of the carbon dioxide introduced into the reaction raw gas and the volume V2 of the red mud mixed slurry satisfy the relationship: V1:V2≥10:1.

[0011] Optionally, the weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the dry basis weight m4 of the red mud satisfy the relationship: m1:m2:m3:m4=(1-5):(0.5-2):(5-10):100.

[0012] Optionally, the cellulose in the waste biomass is ≥ 35% of the weight of the waste biomass.

[0013] Optionally, the red mud comprises Bayer process red mud; and / or

[0014] The waste biomass comprises at least one of the following: corn straw, wheat straw, rice straw, biogas residue, sugarcane bagasse, distiller's grains residue and leaves; and / or

[0015] The activator comprises at least one of sodium silicate, white carbon black and nano silicon dioxide; and / or

[0016] The modifier includes at least one of the following: polyacrylic acid, polystyrene sulfonic acid and polylactic acid.

[0017] Optionally, the particle size of the waste biomass containing cellulose is <0.1 mm.

[0018] Optionally, the mixed product is post-processed to obtain a soil conditioner, comprising the steps of:

[0019] Cooling and filtering the mixed product to obtain filter residue;

[0020] The filtered residue is dried and finely ground to obtain a soil conditioner.

[0021] Optionally, the final particle size of the fine grinding treatment is less than 0.1 mm.

[0022] In a second aspect, the present application provides a soil conditioner, which is prepared by the method described in the first aspect.

[0023] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0024] An embodiment of the present application provides a method for preparing a soil conditioner using red mud, wherein the method first mixes an activator, a modifier, waste biomass containing cellulose, and red mud, and fully mixes the sodium hydroxide and sodium aluminate of the red mud with the cellulose of the waste biomass to obtain a red mud mixed slurry containing alkaline components and cellulose, and then introduces a reaction raw gas containing carbon dioxide into the obtained red mud mixed slurry. During the co-hydrothermal reaction, the carbon dioxide in the reaction raw gas reacts with the alkaline components of the red mud at the liquid phase interface of the red mud mixed slurry to generate carbonates, and the carbonates catalyze and destroy the long-chain molecular structure of the cellulose in the waste biomass during the co-hydrothermal reaction, so that the cellulose in the waste biomass swells and agglomerates, thereby exposing fine fibers on the surface of the waste biomass. Therefore, under the joint reaction of carbon dioxide, the solid matter of the red mud mixed slurry, and the liquid phase, the surface of the waste biomass will expose fine fibers, and the exposed fine fibers can wrap A large amount of red mud will form a three-dimensional fused copolymer structure with the red mud. In addition, the reaction raw gas will enter the formed three-dimensional fused copolymer structure to form a large number of pores in the three-dimensional fused copolymer structure. These pores, together with the supporting effect of the fine fiber body, can promote the solidification reaction between the red mud in the red mud mixed slurry and the carbon dioxide in the reaction raw gas to change the mineral phase and microscopic morphology of the red mud, thereby improving the pore structure of the three-dimensional fused copolymer structure, so as to increase the specific surface area and porosity of the three-dimensional fused copolymer structure, and further increase the number of pore structures of the soil conditioner doped with red mud; in addition, the addition of activators and modifiers can further improve the bonding strength between red mud and the three-dimensional fused copolymer structure, and further increase the specific surface area and porosity of the three-dimensional fused copolymer structure, so as to further increase the number of pore structures of the soil conditioner doped with red mud; therefore, the method can increase the number of pore structures of the soil conditioner doped with red mud. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0027] Figure 1 A schematic flow chart of a method for preparing a soil conditioner using red mud provided in an embodiment of the present application;

[0028] Figure 2 A detailed schematic diagram of a method for preparing a soil conditioner using red mud provided in an embodiment of the present application;

[0029] Figure 3 A scanning electron microscope schematic diagram of red mud provided in an embodiment of the present application;

[0030] Figure 4 This is a scanning electron microscope schematic diagram of a soil conditioner provided in Example 1 of the present application. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0032] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity and should not be understood as a rigid limitation on the scope of the present application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within the range; for example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which applies regardless of the range; in addition, whenever a numerical range is indicated in this document, it is meant to include any cited numbers (fractions or integers) within the indicated range.

[0033] In this document, the terms including "including" and "including" mean "including but not limited to". Relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone; where A and B can be singular or plural. "At least one" means one or more, and "plurality" means two or more; "at least one", "at least one of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items; for example, "at least one of a, b, or c", or "at least one of a, b, and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be single or multiple. "Parts" such as parts by weight and parts by mass indicate the proportional relationship between the components. In the proportional relationship involved in this article, the parameters that need to be described by proportion should be understood as the first term of the proportional formula in the order of description, and the proportional numbers should be understood as the second term of the proportional formula. For example, if the mass ratio of substance A, substance B and substance C is 1:2:3, then substance A, substance B and substance C should correspond to the proportional numbers in the proportional formula in the order of description, that is, the mass of substance A: the mass of substance B: the mass of substance C = 1:2:3.

[0034] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this article can be purchased from the market or prepared by existing methods.

[0035] Figure 1 A schematic flow chart of a method for preparing a soil conditioner using red mud provided in an embodiment of the present application is shown exemplarily;

[0036] like Figure 1 As shown, the embodiment of the present application provides a method for preparing a soil conditioner using red mud, wherein the components of the red mud include alkaline components, and the method includes:

[0037] S1. mixing an activator, a modifier, waste biomass containing cellulose and the red mud to obtain a red mud mixed slurry;

[0038] S2. The reaction raw gas containing carbon dioxide is subjected to a co-hydrothermal reaction with the red mud mixed slurry to generate carbonates and form a three-dimensional fusion copolymer structure to obtain a mixed product;

[0039] S3. post-processing the mixed product to obtain a soil conditioner.

[0040] It should be noted that the mixing method may be stirring mixing, and slurry adjustment may be performed during the mixing process to promote sufficient mixing between the alkaline components of the red mud and the cellulose of the waste biomass.

[0041] It should be noted that the reaction raw material gas may contain only carbon dioxide gas, or may be a mixed gas of carbon dioxide gas and an inert gas.

[0042] It should be noted that the alkaline component can be sodium hydroxide, sodium aluminate and sodalite, among which sodium hydroxide and sodium aluminate are generally present as the main components of the free alkali of red mud, and sodalite is generally present as the combined alkali of red mud. These free alkalis and combined alkalis will react with carbon dioxide at the liquid phase interface to obtain carbonates, and the generated carbonates can catalyze the destruction of the long-chain molecular structure of cellulose in the waste biomass during the subsequent co-hydrothermal reaction, so that the cellulose in the waste biomass is expanded and agglomerated, thereby exposing fine fibers on the surface of the waste biomass.

[0043] It should be noted that the mixture of activator, modifier, waste biomass containing cellulose and red mud

[0044] It should be noted that the amount of water added is 2 to 10 times the sum of the weights of the activator, modifier, cellulose-containing waste biomass and red mud, so that the red mud mixed slurry has sufficient moisture to ensure that sufficient carbonate is generated during the subsequent co-hydrothermal reaction.

[0045] In some optional embodiments, the temperature of the co-hydrothermal reaction is 80°C to 200°C, and the time of the co-hydrothermal reaction is 4h to 20h;

[0046] In these embodiments, the temperature of the co-hydrothermal reaction can be 80°C to 200°C, and the time of the co-hydrothermal reaction can be 4h to 20h. Through the co-hydrothermal reaction, fine fibers can be exposed on the surface of the waste biomass under the joint reaction of carbon dioxide, solid matter of the red mud mixed slurry and the liquid phase, and a large amount of red mud can be wrapped to form a three-dimensional fused copolymer structure with the red mud. In addition, the co-hydrothermal reaction can cause the reaction raw gas to form a large number of pores in the three-dimensional fused copolymer structure. These pores, together with the supporting effect of the fine fibers, can improve the pore structure of the three-dimensional fused copolymer structure, so as to increase the specific surface area and porosity of the three-dimensional fused copolymer structure, thereby increasing the number of pore structures of the soil conditioner doped with red mud.

[0047] The temperature of the co-hydrothermal reaction may be 80°C, 100°C, 120°C, 140°C, 160°C, 180°C or 200°C.

[0048] The co-hydrothermal reaction time can be 4 h, 6 h, 8 h, 10 h, 12 h, 14 h, 16 h, 18 h or 20 h.

[0049] In some optional embodiments, the volume V1 of the carbon dioxide introduced into the reaction raw gas and the volume V2 of the red mud mixed slurry satisfy the relationship: V1:V2≥10:1;

[0050] In these embodiments, the volume V1 of carbon dioxide introduced into the reaction raw gas and the volume V2 of the red mud mixed slurry can satisfy the relationship: V1:V2≥10:1, so that the reaction raw gas contains a sufficient amount of carbon dioxide. The sufficient amount of carbon dioxide can cause acid-base reactions with the alkaline components of the red mud at the liquid interface of the red mud mixed slurry to generate a sufficient amount of carbonate, so that the cellulose of the waste biomass can be expanded and agglomerated, thereby exposing the fine fiber body from the surface of the waste biomass to wrap a large amount of red mud; and a sufficient amount of carbon dioxide will enter into the three-dimensional fused copolymer structure formed by the fine fiber body and the red mud, and form a large number of pores in the three-dimensional fused copolymer structure, thereby improving the pore structure of the three-dimensional fused copolymer structure, so as to increase the specific surface area and porosity of the three-dimensional fused copolymer structure, and then can increase the number of pore structures of the soil conditioner doped with red mud.

[0051] In some optional embodiments, the weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the red mud on a dry basis satisfy the relationship: m1:m2:m3:m4=(1-5):(0.5-2):(5-10):100;

[0052] In these embodiments, the weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=(1-5):(0.5-2):(5-10):100, so that the red mud mixed slurry has sufficient activator and sufficient modifier. Sufficient activator not only promotes the reaction degree of waste biomass decomposition and conversion into cellulose, but also can fully colloidally combine oxygen-containing functional groups such as hydroxyl and carboxyl groups on the surface of cellulose to improve the stability of the three-dimensional fusion copolymer structure, thereby promoting cellulose to The red mud is adsorbed more tightly to increase the red mud doping amount of the soil conditioner; in addition, a sufficient amount of modifier can be adsorbed on the surface of the waste biomass to cause the surface of the waste biomass to carry a sufficient amount of negative charge, and the sufficient amount of negative charge will form active sites on the surface of the waste biomass. These surface active sites can promote the cellulose of the waste biomass to form a chelate structure with the red mud; in addition, since the modifier generally contains a large number of hydrophilic groups, these hydrophilic groups will further promote the cellulose of the waste biomass to adsorb red mud, so as to promote the gelation of red mud on the cellulose surface, which is conducive to the formation of a multi-layer cross-linked stable three-dimensional fusion copolymer structure between red mud and cellulose.

[0053] The weight m1 of the activator can be 0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8 or 2.0; the weight m2 of the modifier can be 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4 or 5; the weight m3 of the waste biomass containing cellulose can be 5, 6, 7, 8, 9 or 10.

[0054] In some optional embodiments, the cellulose of the waste biomass is ≥ 35% of the weight of the waste biomass;

[0055] In these embodiments, the cellulose in the waste biomass is ≥ 35% of the weight of the waste biomass, so that the waste biomass contains sufficient cellulose. Under the joint reaction of carbon dioxide, solid matter and liquid phase of the red mud mixed slurry, fine fibers are exposed on the surface of the waste biomass. The exposed fine fibers can wrap a large amount of red mud and form a three-dimensional fused copolymer structure with the red mud. The three-dimensional fused copolymer structure can increase the number of pore structures of the soil conditioner doped with red mud.

[0056] In some optional embodiments, the red mud comprises Bayer process red mud; and / or

[0057] The waste biomass includes at least one of the following:

[0058] Corn stover, wheat straw, rice straw, biogas residue, sugarcane bagasse, distiller's grains and leaves; and / or

[0059] The activator comprises at least one of the following:

[0060] Sodium silicate, white carbon black and nano-silicon dioxide; and / or

[0061] The modifier comprises at least one of the following:

[0062] polyacrylic acid, polystyrene sulfonic acid, and polylactic acid;

[0063] In these embodiments, the red mud may include Bayer red mud, which may cause the red mud to contain a sufficient amount of alkaline components, so that during the co-hydrothermal reaction, the carbon dioxide in the reaction raw gas reacts with the alkaline components of the red mud at the liquid phase interface of the red mud mixed slurry to generate a sufficient amount of carbonate, which is convenient for the subsequent expansion and agglomeration of cellulose in the waste biomass; in addition, the waste biomass may include at least one of corn straw, wheat straw, rice straw, biogas residue, sugarcane bagasse, distiller's grains residue and leaves, which may cause the waste biomass to have a sufficient amount of cellulose. The sufficient amount of cellulose may fully expose a large amount of fine fiber bodies on the surface of the waste biomass under the action of the hydrothermal reaction of carbon dioxide, the solid matter of the red mud mixed slurry and the liquid phase, and these fine fiber bodies may wrap a large amount of red mud and form a three-dimensional fusion copolymer structure with the red mud, so as to improve the red mud of the soil conditioner. doping amount; in addition, the activator may include: at least one of sodium silicate, white carbon black and nano silicon dioxide, which can cover most types of activators. The activator can improve the stability of the three-dimensional fusion copolymer structure, thereby promoting cellulose to adsorb red mud more tightly, so as to increase the red mud doping amount of the soil conditioner; in addition, the modifier may include: at least one of polyacrylic acid, polystyrene sulfonic acid and polylactic acid, which can cover most of the modifiers, and the modifier can be adsorbed on the surface of the waste biomass to promote the surface of the waste biomass to carry a sufficient amount of negative charge, and the sufficient amount of negative charge will form active sites on the surface of the waste biomass. These surface active sites can promote the cellulose of the waste biomass to form a chelate structure with red mud, thereby avoiding the invasion of red mud into the pore structure, so as to increase the number of pore structures of the soil conditioner doped with red mud.

[0064] It should be noted that, based on the characteristic that the activator can cause cellulose to adsorb red mud more tightly, the soil conditioner can effectively adsorb nitrogen, phosphorus, potassium and other elements of the fertilizer during the soil conditioning process and slow down the release rate of these elements, thereby improving the utilization efficiency of the fertilizer.

[0065] It should be noted that, based on the characteristic that the modifier can promote the formation of chelate structures between cellulose in waste biomass and red mud, soil conditioners can adsorb metal ions in the soil through these chelate structures to avoid the toxic effects of metal ions on the soil; in addition, based on the promoting effect of the modifier on the formation of multi-layer cross-linked stable three-dimensional fusion copolymer structures between red mud and cellulose, these three-dimensional fusion copolymer structures can be used to increase the number of pore structures of soil conditioners doped with red mud, and sufficient pore structures can improve the ability of soil conditioners to store water and fertilizers, so as to further improve the improvement effect of soil conditioners on the soil.

[0066] In some optional embodiments, the particle size of the waste biomass containing cellulose is <0.1 mm;

[0067] In these embodiments, the particle size of the waste biomass containing cellulose is less than 0.1 mm, which enables the particle size of the waste biomass to be within a finer particle size range, and enables the cellulose to form sufficiently fine microfibers during the co-hydrothermal reaction. The sufficiently fine microfibers can wrap a large amount of red mud and form a three-dimensional fused copolymer structure with the red mud. In addition, the cellulose in the finer particle size range has a better supporting effect, and cooperates with the reaction raw gas to enter the formed three-dimensional fused copolymer structure to form a large number of pores, which can increase the specific surface area and porosity of the three-dimensional fused copolymer structure, thereby increasing the number of pore structures of the soil conditioner doped with red mud.

[0068] Figure 2 A detailed schematic diagram of a method for preparing a soil conditioner using red mud provided in an embodiment of the present application is shown by way of example;

[0069] In some optional embodiments, such as Figure 2 As shown, the mixed product is post-processed to obtain a soil conditioner, comprising the steps of:

[0070] S301. The mixed product is cooled and filtered to obtain a filter residue;

[0071] S302. The filtered residue is dried and finely ground to obtain a soil conditioner;

[0072] In these embodiments, the mixed product is sequentially cooled, filtered, dried and finely ground to remove impurities in the mixed product and obtain a soil conditioner with a finer particle size.

[0073] In some optional embodiments, the final particle size of the fine grinding treatment is less than 0.1 mm;

[0074] In these embodiments, the terminal particle size of the fine grinding treatment is less than 0.1 mm, which enables the soil conditioner to have a smaller particle size. The soil conditioner that is small enough can better exert the characteristics of its three-dimensional fusion copolymer structure, effectively adsorb metal ions, fertilizers and moisture in the soil, thereby improving the conditioning effect of the soil conditioner on the soil.

[0075] Based on a general inventive concept, an embodiment of the present application provides a soil conditioner, which is prepared by the method.

[0076] The soil conditioner is realized based on the above method. The specific steps of the method can refer to the above embodiment. Since the soil conditioner adopts part or all of the technical solutions of the above embodiment, it has at least all the beneficial effects brought by the technical solutions of the above embodiment, which will not be described one by one here.

[0077] The present application is further described below in conjunction with specific examples. The experimental methods in the following examples where specific conditions are not specified are usually measured in accordance with national standards / industry standards; if there are no corresponding national standards / industry standards, they are measured in accordance with common international standards, conventional conditions or conditions recommended by the manufacturer.

[0078] Example 1

[0079] like Figure 2 As shown, a method for preparing a soil conditioner using red mud, wherein the components of the red mud include alkaline components, including:

[0080] S1. mixing an activator, a modifier, waste biomass containing cellulose and red mud to obtain a red mud mixed slurry containing an alkaline component and cellulose;

[0081] S2. using a reaction raw gas containing carbon dioxide to perform a co-hydrothermal reaction on a red mud mixed slurry containing an alkaline component and cellulose to generate carbonates and form a three-dimensional fusion copolymer structure to obtain a mixed product;

[0082] S301. The mixed product is cooled and filtered to obtain a filter residue;

[0083] S302. The filtered residue is dried and finely ground to obtain a soil conditioner;

[0084] The amount of water added is 5 times the total weight of the activator, the modifier, the waste biomass containing cellulose and the red mud.

[0085] The temperature of the co-hydrothermal reaction is 120° C., and the time of the co-hydrothermal reaction is 10 h.

[0086] The volume V1 of carbon dioxide introduced into the reaction raw gas and the volume V2 of the red mud mixed slurry satisfy the relationship: V1:V2=20:1.

[0087] The weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=1:0.8:8:100.

[0088] The cellulose of the waste biomass is ≥ 35% by weight of the waste biomass.

[0089] The red mud is Bayer red mud;

[0090] The waste biomass was corn stover;

[0091] The activator is nano-silicon dioxide;

[0092] The modifier is polyacrylic acid.

[0093] The particle size of the waste biomass containing cellulose is <0.1 mm.

[0094] The final particle size of fine grinding is less than 0.1 mm.

[0095] Example 2

[0096] Based on the contents disclosed in Example 1, the following modifications are further made:

[0097] The amount of water added is twice the sum of the weights of the activator, the modifier, the waste biomass containing cellulose and the red mud.

[0098] The temperature of the co-hydrothermal reaction is 180°C, and the time of the co-hydrothermal reaction is 15 h.

[0099] The weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=5:1.5:6.5:100.

[0100] The waste biomass is rice straw;

[0101] The activator is white carbon black;

[0102] The modifier is polyacrylic acid.

[0103] Example 3

[0104] Based on the contents disclosed in Example 1, the following modifications are further made:

[0105] The amount of water added is 10 times the sum of the weights of the activator, the modifier, the waste biomass containing cellulose and the red mud.

[0106] The temperature of the co-hydrothermal reaction is 160°C, and the time of the co-hydrothermal reaction is 8 hours.

[0107] The weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=4:2:5:100.

[0108] The waste biomass is sugarcane bagasse;

[0109] The activator is sodium silicate;

[0110] The modifier is polylactic acid.

[0111] Example 4

[0112] Based on the contents disclosed in Example 1, the following modifications are further made:

[0113] The amount of water added is 8 times the total weight of the activator, the modifier, the waste biomass containing cellulose and the red mud.

[0114] The temperature of the co-hydrothermal reaction is 200°C, and the time of the co-hydrothermal reaction is 4 hours.

[0115] The weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=3:0.5:9:100.

[0116] Waste biomass is digestate;

[0117] The activator is sodium silicate;

[0118] The modifier is polystyrene sulfonic acid.

[0119] Example 5

[0120] Based on the contents disclosed in Example 1, the following modifications are further made:

[0121] The amount of water added is 6 times the total weight of the activator, the modifier, the waste biomass containing cellulose and the red mud.

[0122] The temperature of the co-hydrothermal reaction is 80°C, and the time of the co-hydrothermal reaction is 20 h.

[0123] The weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=2.5:1.2:10:100.

[0124] The waste biomass was wheat straw;

[0125] The activator is white carbon black;

[0126] The modifier is polystyrene sulfonic acid.

[0127] Comparative Example 1

[0128] Based on the contents disclosed in Example 1, the following modifications are further made:

[0129] The volume V1 of carbon dioxide introduced into the reaction raw gas and the volume V2 of the red mud mixed slurry satisfy the relationship:

[0130] V1:V2=8:1.

[0131] Comparative Example 2

[0132] Based on the contents disclosed in Example 1, the following modifications are further made:

[0133] The temperature of the co-hydrothermal reaction is 60°C, and the time of the co-hydrothermal reaction is 30 h.

[0134] Comparative Example 3

[0135] Based on the contents disclosed in Example 1, the following modifications are further made:

[0136] The temperature of the co-hydrothermal reaction is 250°C, and the time of the co-hydrothermal reaction is 2h.

[0137] Comparative Example 4

[0138] Based on the contents disclosed in Example 1, the following modifications are further made:

[0139] The weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=0.5:0.1:3:100.

[0140] Comparative Example 5

[0141] Based on the contents disclosed in Example 1, the following modifications are further made:

[0142] The weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=10:5:15:100.

[0143] Related experiments and effect data:

[0144] 1. The red mud doping amount, specific surface area and porosity of the soil conditioner obtained in each comparative example and embodiment were statistically analyzed, and the results are shown in Table 1.

[0145] Table 1 Red mud doping amount, specific surface area and porosity of soil conditioners in various comparative examples and embodiments

[0146]

[0147] As can be seen from Table 1, the present invention provides a method for preparing a soil conditioner using red mud. In this method, under the joint reaction of carbon dioxide, solid matter and liquid phase of the red mud mixed slurry, fine fibers are exposed on the surface of the waste biomass, and the exposed fine fibers can wrap a large amount of red mud and form a three-dimensional fused copolymer structure with the red mud. In addition, the reaction raw gas will also enter the formed three-dimensional fused copolymer structure, which can increase the specific surface area of ​​the three-dimensional fused copolymer structure to 63.25 m 2 / g~70.85m 2 / g and the porosity reaches 82.17% to 90.79%, which indicates that the method significantly increases the number of pore structures of the soil conditioner doped with red mud, and a sufficient number of pore structures can further increase the adsorption amount of red mud in the red mud mixed slurry by the three-dimensional fusion copolymer structure, thereby increasing the red mud doping amount of the soil conditioner to 88.50% to 91.07%. In Comparative Example 1, the ratio of the volume V1 of the carbon dioxide introduced into the reaction raw gas and the volume V2 of the red mud mixed slurry is reduced to 9:1 on the basis of Example 1; in Comparative Example 2, the temperature of the co-hydrothermal reaction is reduced to 60°C on the basis of Example 1; in Comparative Example 2, the temperature of the co-hydrothermal reaction is increased to 250°C on the basis of Example 1; in Comparative Example 4, the raw material ratio is changed on the basis of Example 1 (the weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=0.5:0.1:3:100); and in Comparative Example 5, the raw material ratio is changed on the basis of Example 1 (the weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud satisfy the relationship: m1:m2:m3:m4=10:5:15:100). Although the red mud doping amount of comparative examples 1-4 does not change much, the specific surface area and porosity indicators of the soil conditioners prepared in comparative examples 1-5 are significantly worse than those of the soil conditioners prepared in embodiments 1-5, which indicates that the various poor process conditions of the comparative examples will significantly affect the pore structure distribution and quantity of the soil conditioners.

[0148] 2. The soil conditioners of each embodiment and comparative example were respectively applied to the barren soil for experiment: the soil conditioners prepared in each embodiment were added to the barren soil of 30 cm in the surface layer according to the application amount of 5% of the soil mass, and then the soil and the soil conditioner were mixed evenly by a tiller, and watered. After 7 days of stable cultivation, the porosity, field water holding capacity, soil specific surface area, and organic matter content of the soil were sampled and tested. At the same time, ryegrass crops were uniformly planted during the stable cultivation period, and the germination rate of ryegrass after 10 days of cultivation and the plant height after 30 days were counted during the stable cultivation period. In addition, blank group and control group experiments were carried out according to the above steps. The blank group was a barren soil without adding soil conditioners, and replaced with water samples of the same mass; the control group was a barren soil with only 5% of the soil mass of dry red mud added. The results are shown in Table 2.

[0149] Table 2 Soil test results of soil conditioners in various embodiments and comparative examples

[0150]

[0151]

[0152] It can be seen from Table 2 that compared with the control group in which dry red mud was directly added to the barren soil at an addition amount of 5%, the porosity, field water holding capacity, soil specific surface area and organic matter content of the control group increased by only 3.2%, 4.7%, 0.56% and 0.22%, respectively. A soil conditioner provided in an embodiment of the present application is added to the barren soil at an addition amount of 5%, which can increase the soil porosity, field water holding capacity, soil specific surface area and organic matter content to more than 11%, more than 12%, more than 7% and more than 15%, respectively. In addition, through the comparison of the growth conditions of ryegrass crops, it can be seen that the germination rates of the ryegrass crops in the blank group without adding soil conditioners and the control group with only adding dry red mud are only 55.25% and 57.46% at 10 days, and the average plant heights at 30 days are only 13.38 cm and 14.32 cm; after being treated with various soil conditioners provided in the embodiments of the present application, the germination rate of the ryegrass crops at 10 days can be increased to more than 80%, and the average plant height at 30 days can be more than 25 cm. In Comparative Example 1, the ratio of the volume V1 of the carbon dioxide of the reaction raw material gas to the volume V2 of the red mud mixed slurry is reduced to 9:1 on the basis of Example 1; in Comparative Example 2, the temperature of the co-hydrothermal reaction is reduced to 60°C on the basis of Example 1; in Comparative Example 2, the temperature of the co-hydrothermal reaction is increased to 250°C on the basis of Example 1; in Comparative Example 4, the raw material ratio (the weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the weight m4 of the dry basis of the red mud) is changed on the basis of Example 1. 4 satisfies the relationship: m1:m2:m3:m4=0.5:0.1:3:100), and Comparative Example 5 changes the raw material ratio on the basis of Example 1 (the weight of the activator m1, the weight of the modifier m2, the weight of the waste biomass containing cellulose m3 and the weight of the dry basis of the red mud m4 satisfy the relationship: m1:m2:m3:m4=10:5:15:100), and the experimental results of the soil conditioners prepared in the above Comparative Examples 1 to 5 in the soil test process are significantly worse than the experimental results of Examples 1 to 5. This shows that the soil conditioner provided in the embodiments of the present application can significantly improve the soil porosity, field water holding capacity and soil specific surface area of ​​barren soil, and can also increase the organic matter content of barren soil, and the soil conditioner also has the beneficial effects of retaining water, retaining fertilizer and promoting crop growth.

[0153] In summary, the embodiment of the present application provides a method for preparing a soil conditioner using red mud. In this method, under the joint reaction of carbon dioxide, solid matter in red mud mixed slurry and liquid phase, fine fibers will be exposed on the surface of the waste biomass. These fine fibers will form a three-dimensional fused copolymer structure with the red mud. In addition, the reaction raw gas will also enter the formed three-dimensional fused copolymer structure, which can increase the specific surface area and porosity of the three-dimensional fused copolymer structure, thereby significantly increasing the number of pore structures of the soil conditioner doped with red mud, and then increasing the adsorption amount of red mud of the red mud mixed slurry by the three-dimensional fused copolymer structure, so as to increase the doping amount of red mud in the soil conditioner to 88.50%~91.07%.

[0154] In addition, an embodiment of the present application provides a method for preparing a soil conditioner using red mud. The method uses carbon dioxide, waste biomass containing cellulose and red mud as raw materials, and can achieve coordinated processing of red mud, waste biomass resources and carbon dioxide to increase the red mud doping amount of the soil conditioner and reduce production costs, so as to achieve the purpose of coordinated utilization of "waste to treat waste".

[0155] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. It will be apparent to those skilled in the art that various modifications to these embodiments are possible, and the general principles defined in the present application can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown in the present application, but will conform to the widest range consistent with the principles and novel features applied for by the present application.

Claims

1. A method for preparing a soil conditioner using red mud, wherein the components of the red mud include alkaline components, and the method comprises: Mixing an activator, a modifier, waste biomass containing cellulose and the red mud to obtain a red mud mixed slurry; The reaction raw gas containing carbon dioxide is subjected to a co-hydrothermal reaction with the red mud mixed slurry to generate carbonate and form a three-dimensional fused copolymer structure to obtain a mixed product; The mixed product is post-treated to obtain a soil conditioner.

2. According to the method of claim 1, the temperature of the co-hydrothermal reaction is 80°C to 200°C, and the time of the co-hydrothermal reaction is 4h to 20h.

3. According to the method of claim 1, the volume V1 of the carbon dioxide in the reaction raw gas and the volume V2 of the red mud mixed slurry satisfy the relationship: V1:V2≥10:

1.

4. According to the method of claim 1, the weight m1 of the activator, the weight m2 of the modifier, the weight m3 of the waste biomass containing cellulose and the dry weight m4 of the red mud satisfy the relationship: m1:m2:m3:m4=(1-5):(0.5-2):(5-10):

100.

5. The method according to claim 1 or 4, wherein the cellulose of the waste biomass is ≥ 35% of the weight of the waste biomass.

6. The method according to claim 1 or 4, wherein the red mud comprises Bayer process red mud; and / or The waste biomass comprises at least one of the following: corn straw, wheat straw, rice straw, biogas residue, sugarcane bagasse, distiller's grains residue and leaves; and / or The activator comprises at least one of the following: sodium silicate, white carbon black and nano silicon dioxide; and / or The modifier includes at least one of the following: polyacrylic acid, polystyrene sulfonic acid and polylactic acid.

7. The method according to claim 1, wherein the particle size of the waste biomass containing cellulose is <0.1 mm.

8. The method according to claim 1, wherein the mixed product is post-processed to obtain a soil conditioner, comprising the steps of: Cooling and filtering the mixed product to obtain filter residue; The filtered residue is dried and finely ground to obtain a soil conditioner.

9. The method according to claim 8, wherein the final particle size of the fine grinding treatment is less than 0.1 mm.

10. A soil conditioner, which is prepared by the method according to any one of claims 1 to 9.

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