Calcium-based solid waste residue slurry desulfurizer, preparation method, desulfurization method and soil remediation agent

Abstract

The invention relates to a calcium-based solid waste residue slurry desulfurizer, a preparation method, a desulfurization method and a soil remediation agent, and belongs to the technical field of solid waste utilization. The method comprises the following steps: carrying out sedimentation treatment on calcium-based solid waste residue slurry to obtain a calcium-based solid waste residue slurry reaction solution; adding a phase change inhibitor into the calcium-based solid waste residue slurry reaction liquid to obtain mixed slurry; and carrying out solid-liquid separation on the mixed slurry to obtain a solid-phase substance, mixing the solid-phase substance with water, and adding a conditioning agent to obtain the calcium-based solid waste residue slurry desulfurizer. The desulfurizer can be used for desulfurization reaction to obtain a desulfurization solution and desulfurization solid slag; carrying out solid-liquid separation on the desulfurization solution after neutralization reaction to obtain washing water filtrate and secondary desulfurization solid residues; and preparing the soil ecological restoration agent from the desulfurized solid residues and the secondary desulfurized solid residues. The desulfurizer is prepared from the calcium-based solid waste residue slurry discharged by aluminum oxide, alkali resources are recycled, the loss of aluminum oxide is reduced, the desulfurizer is used for flue gas desulfurization, the purpose of resource utilization of solid waste is achieved, and the desulfurizer has the value and significance of reducing pollution and carbon and achieving synergistic interaction.

Description

Technical Field

[0001] The present application relates to the technical field of solid waste utilization, and in particular to a calcium-based solid waste slurry desulfurizer, a preparation method, a desulfurization method, and a soil remediation agent. Background Art

[0002] In the process of producing alumina from bauxite, impurities in the ore need to react with calcium-based materials to produce a mixture of hydrocalumite, calcium carbonate, calcium aluminate and its hydrates and alkali solution. The alkali solution is returned to the alumina system for continued use, and the remaining mixture is calcium-based solid waste slurry, which is sent to the red mud reservoir as general solid waste after solid-liquid separation. At present, there is no document recording how to use calcium-based solid waste slurry to achieve waste utilization. Summary of the invention

[0003] The present application provides a calcium-based solid waste slurry desulfurizer, a preparation method, a desulfurization method, and a soil remediation agent to solve the following technical problem: how to utilize calcium-based solid waste slurry waste.

[0004] In a first aspect, the present application provides a method for preparing a calcium-based solid waste slurry desulfurizer, comprising the following steps:

[0005] Obtaining a calcium-based solid waste slurry reaction liquid;

[0006] adding a phase change inhibitor to the calcium-based solid waste slurry reaction liquid to obtain a mixed slurry;

[0007] The mixed slurry is subjected to solid-liquid separation to obtain a solid phase substance;

[0008] Adding water to the solid phase material and mixing it with a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer;

[0009] Wherein, the pH value of the calcium-based solid waste slurry desulfurizer is 7-10.

[0010] Optionally, the step of obtaining a calcium-based solid waste slurry reaction solution specifically includes:

[0011] The calcium-based solid waste slurry is sedimented to obtain an underflow of the calcium-based solid waste slurry;

[0012] diluting the calcium-based solid waste slurry underflow to obtain a calcium-based solid waste slurry reaction liquid;

[0013] The solid-liquid ratio of the calcium-based solid waste slurry reaction liquid is (0.1-1):1.

[0014] Optionally, diluting the calcium-based solid waste slurry underflow specifically includes: stirring and mixing the calcium-based solid waste slurry underflow with hot water at a temperature of 72° C. to 98° C. for a stirring time of 0.5 h to 5 h.

[0015] Optionally, the mass of the phase change inhibitor is 0.02% to 0.15% of the total mass of sodium and aluminum in the calcium-based solid waste slurry reaction solution; and / or,

[0016] The phase change inhibitor comprises at least one of the following: sugar acid salt, cellulose, wood calcium and sodium humate.

[0017] Optionally, the sugar acid salt is calcium gluconate and sodium gluconate.

[0018] Optionally, the solid-liquid separation of the mixed slurry to obtain a solid phase substance specifically includes:

[0019] The mixed slurry is filtered once, and then the solid is washed with hot water under pressure and filtered again to obtain a solid phase substance and a primary filtrate.

[0020] Optionally, the conditioning agent comprises at least one of the following: citric acid, citrate, gluconate, tannic acid and aminocarboxylate; and / or,

[0021] The mass of the conditioning agent is 0.005% to 0.5% of the total mass of the calcium-based solid waste slurry desulfurizer.

[0022] In a second aspect, the present application provides a desulfurizer, which is prepared by the preparation method of the calcium-based solid waste slurry desulfurizer described in the first aspect.

[0023] In a third aspect, the present application provides a desulfurization method, comprising the following steps:

[0024] Obtaining the calcium-based solid waste slurry desulfurizer described in the second aspect;

[0025] The calcium-based solid waste slurry desulfurizer is subjected to a desulfurization reaction with the flue gas to be desulfurized to obtain a desulfurized slurry;

[0026] The pH of the desulfurization reaction is 4.8 to 6.2.

[0027] Optionally, the desulfurization reaction of the calcium-based solid waste slurry desulfurizer with the flue gas to be desulfurized to obtain a desulfurized slurry specifically includes:

[0028] The calcium-based solid waste slurry desulfurizer is fed into a desulfurization reactor to undergo a reverse desulfurization reaction with the flue gas to be desulfurized to obtain a desulfurized slurry.

[0029] Optionally, the temperature of the flue gas to be desulfurized in the desulfurization reaction is 50°C to 150°C.

[0030] Optionally, after the calcium-based solid waste slurry desulfurizer is subjected to a desulfurization reaction with the flue gas to be desulfurized to obtain a desulfurized slurry, the method further comprises:

[0031] The desulfurized slurry is subjected to solid-liquid separation to obtain a desulfurized solution and desulfurized solid slag.

[0032] Optionally, when the desulfurization solution meets the set conditions, the desulfurization solution is subjected to a neutralization reaction to obtain secondary desulfurization solid slag;

[0033] The set conditions include: the total mass concentration of sodium and aluminum in the desulfurization solution is greater than 25g / L.

[0034] Optionally, the neutralizing reaction of the desulfurization solution specifically includes: adding a neutralizing agent to the desulfurization solution for reaction; performing solid-liquid separation on the desulfurization solution after the reaction to obtain secondary desulfurization solid residue and washing water filtrate;

[0035] The neutralizing agent includes at least one of lime, calcium silicate and calcium silicate.

[0036] Optionally, the wash water filtrate can enter the desulfurization agent preparation process and be mixed with calcium-based solid waste slurry for recycling.

[0037] Optionally, in the neutralization reaction, the reaction temperature is 40°C to 100°C, the mass ratio of the desulfurization solution to the neutralizing agent is 10:(0.1 to 1.5), and the pH value is 7.2 to 10.5.

[0038] In a fourth aspect, the present application provides a soil remediation agent, comprising the desulfurized solid slag and / or the secondary desulfurized solid slag described in the third aspect.

[0039] Optionally, the mixture includes 1 to 7 parts of desulfurization solid slag and / or secondary desulfurization solid slag, 10 to 25 parts of red mud, 1 to 3 parts of wood ash and 2 to 6 parts of soil, calculated by mass.

[0040] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0041] The present application discloses a calcium-based solid waste slurry desulfurizer, a preparation method, a desulfurization method, and a soil repair agent. The method comprises the following steps: obtaining a calcium-based solid waste slurry reaction liquid, which mainly contains unstable hydrocalumite, calcium carbonate, calcium aluminate and hydrates thereof; adding a phase change inhibitor to the calcium-based solid waste slurry reaction liquid to inhibit the reaction of calcium hydroxide and alumina in the reaction liquid, reduce the generation of hydrocalumite, further reduce the generated stable calcium aluminate and its hydrates, and at the same time generate more calcium carbonate substances to reduce the loss of alumina, to obtain a mixed slurry; separating the mixed slurry into solid and liquid, discharging most of the sodium oxide and aluminum oxide through the filtrate, leaving solid phase substances such as calcium carbonate, calcium aluminate and its hydrates, and hydrocalumite; adding water to the solid phase substances and mixing them with a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer; the pH value of the tempered calcium-based solid waste slurry desulfurizer is 7-10, which can improve the desulfurization performance of calcium aluminate and its hydrates, break the gelation of active silicon, aluminum and magnesium, reduce the agglomeration of active silicon and aluminum oxide, and enhance the oxidation and filtration performance of desulfurization by-products.

[0042] The method uses solid waste calcium-based solid waste slurry as raw material to prepare a desulfurizing agent, thereby realizing resource utilization of solid waste, achieving zero discharge of solid waste, and reducing flue gas desulfurization operating costs and alumina production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] 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.

[0044] 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.

[0045] Figure 1 A schematic flow chart of a method for preparing a calcium-based solid waste slurry desulfurizer according to some embodiments of the present application;

[0046] Figure 2 A schematic diagram of a calcium-based solid waste slurry desulfurization method according to some embodiments of the present application. DETAILED DESCRIPTION

[0047] 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.

[0048] 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.

[0049] 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, refers 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.

[0050] 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.

[0051] Figure 1 A schematic flow chart of a method for preparing a calcium-based solid waste slurry desulfurizer according to some embodiments of the present application;

[0052] like Figure 1 As shown, the present application embodiment provides a method for preparing a calcium-based solid waste slurry desulfurizer, comprising:

[0053] S1, obtaining a calcium-based solid waste slurry reaction liquid;

[0054] S2, adding a phase change inhibitor to the calcium-based solid waste slurry reaction liquid to obtain a mixed slurry;

[0055] S3, performing solid-liquid separation on the mixed slurry to obtain a solid phase material;

[0056] S4, adding water to the solid phase material and mixing it with a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer;

[0057] Wherein, the pH value of the calcium-based solid waste slurry desulfurizer is 7-10.

[0058] In the above embodiment, a calcium-based solid waste slurry reaction liquid is obtained, which mainly contains unstable hydrocalumite, calcium carbonate, calcium aluminate and their hydrates; a phase change inhibitor is added to the calcium-based solid waste slurry reaction liquid to inhibit the reaction of calcium hydroxide and alumina in the reaction liquid, reduce the production of hydrocalumite, further reduce the generated stable calcium aluminate and its hydrates, and at the same time produce more calcium carbonate substances to reduce the loss of alumina, thereby obtaining a mixed slurry; the mixed slurry is subjected to solid-liquid separation, and most of the sodium oxide and alumina are discharged through the filtrate, leaving solid phase substances such as calcium carbonate, calcium aluminate and its hydrates, and hydrocalumite; the solid phase substances are mixed with a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer; the pH value of the tempered calcium-based solid waste slurry desulfurizer is 7-10, which can improve the desulfurization performance of calcium aluminate and its hydrates, break the gelling property of active silicon, aluminum and magnesium, reduce the agglomeration of active silicon and alumina, and enhance the oxidation and filtration performance of desulfurization by-products.

[0059] The method uses solid waste calcium-based solid waste slurry as raw material to prepare a desulfurizing agent, thereby realizing resource utilization of solid waste, achieving zero discharge of solid waste, and reducing flue gas desulfurization operating costs and alumina production costs.

[0060] As an optional implementation manner, the step of obtaining the calcium-based solid waste slurry reaction solution specifically includes:

[0061] S11, settling the calcium-based solid waste slurry to obtain an underflow of the calcium-based solid waste slurry;

[0062] S12, diluting the calcium-based solid waste slurry underflow to obtain a calcium-based solid waste slurry reaction liquid;

[0063] The solid-liquid ratio in the calcium-based solid waste slurry reaction liquid is (0.1-1):1.

[0064] In the above embodiment, the calcium-based solid waste slurry is precipitated in a sedimentation tank to obtain a calcium-based solid waste slurry bottom flow with a higher solid content and a sedimentation tank overflow, and the sedimentation tank overflow is sent to the alumina slurry dilution tank to recover a portion of sodium hydroxide; the calcium-based solid waste slurry bottom flow is sent to the alkali recovery reaction tank for dilution to prepare a calcium-based solid waste slurry reaction liquid. The sedimentation process can not only increase the solid content of the prepared calcium-based solid waste slurry reaction liquid, but also reduce the alkali concentration in the prepared calcium-based solid waste slurry reaction liquid.

[0065] The reason for controlling the solid-liquid ratio in the calcium-based solid waste slurry reaction liquid to be (0.1-1):1 is that a suitable solid-liquid ratio helps to improve the sodium oxide removal effect and reduce the water content of the solid phase obtained after the later solid-liquid separation. When the solid-liquid ratio is greater than 1:1, it will affect the solid-liquid separation effect, and the solid phase after the solid-liquid separation will have a higher sodium oxide content; when the solid-liquid ratio is less than 0.1:1, it will increase the solid-liquid separation time, and the solid phase after the solid-liquid separation will have a higher water content. Exemplarily, the solid-liquid ratio can be 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1 or 1:1.

[0066] As an optional implementation, the diluting of the calcium-based solid waste slurry underflow specifically includes: stirring and mixing the calcium-based solid waste slurry underflow with hot water at a temperature of 72°C to 98°C for a stirring time of 0.5h to 5h to ensure that the reaction liquid is fully mixed.

[0067] In the above embodiment, hot water is used for dilution, and the temperature of adding the phase change inhibitor is controlled to be 72°C to 98°C because the temperature and stirring conditions will directly affect the reaction of calcium oxide and aluminum oxide. When the temperature is higher than 98°C, the loss of aluminum oxide will increase and more hydrocalumite will be generated. When the temperature is lower than 72°C, the reaction of calcium oxide and aluminum oxide in the reaction liquid can hardly proceed, and the effect is poor. Exemplarily, when the phase change inhibitor is added, the temperature of the calcium-based solid waste slurry reaction liquid can be 72, 75, 78, 80°C, 82°C, 85°C, 88°C, 90°C, 92°C, 95°C or 98°C.

[0068] As an optional implementation manner, the mass of the phase change inhibitor is 0.02% to 0.15% of the total mass of sodium and aluminum in the calcium-based solid waste slurry reaction liquid.

[0069] In the above embodiment, the reason for controlling the mass fraction of the phase change inhibitor to be 0.02% to 0.15% of the total mass of sodium and aluminum in the calcium-based solid waste slurry reaction liquid is to ensure that the calcium hydroxide in the calcium-based solid waste slurry reaction liquid is converted into calcium carbonate, and to avoid aluminum oxide from participating in the reaction, thereby reducing the loss of aluminum oxide. If the mass fraction is lower than 0.02%, the physical phase transformation of calcium hydroxide cannot be promoted; if the mass fraction is higher than 0.15%, the reaction effect of the phase change inhibitor is almost not increased, and the calcium hydroxide has been completely converted into calcium carbonate, which causes a waste of the phase change inhibitor and increases the cost. Exemplarily, the added mass of the phase change inhibitor accounts for 0.02%, 0.04%, 0.05%, 0.06%, 0.08%, 0.1%, 0.12%, 0.14% and 0.15% of the total mass of sodium and aluminum in the calcium-based solid waste slurry reaction liquid.

[0070] The working principle of the phase change inhibitor is: adsorbing on the surface active sites of the unstable intermediate phase of calcium aluminate, inhibiting the diffusion reaction of active substances on these surface active sites, and accelerating the transformation of the unstable intermediate phase of calcium aluminate into calcium carbonate and aluminum oxide. As an optional embodiment, the phase change inhibitor includes at least one of the following: calcium gluconate, potassium gluconate, cellulose, wood calcium and sodium humate.

[0071] In the above embodiment, the phase change inhibitor can be selected from any one of calcium gluconate, potassium gluconate, cellulose, wood calcium, and sodium humate; a mixture of any two of calcium gluconate, potassium gluconate, cellulose, wood calcium, and sodium humate; a mixture of any three or four of calcium gluconate, potassium gluconate, cellulose, wood calcium, and sodium humate; and finally, five substances, calcium gluconate, potassium gluconate, cellulose, wood calcium, and sodium humate, can be selected and mixed as the phase change inhibitor.

[0072] As an optional embodiment, the mixed slurry is subjected to solid-liquid separation to obtain a solid phase substance, specifically comprising:

[0073] The mixed slurry is filtered once, and then the solid is washed with hot water under pressure and filtered again to obtain a solid phase substance and a primary filtrate.

[0074] In the above embodiment, the reaction liquid to which the phase change inhibitor is added is reacted to obtain a mixed slurry; the mixed slurry is subjected to a procedure of two filter presses and one washing, wherein the mixed slurry is first subjected to a filter press to achieve solid-liquid separation in the mixed slurry, and most of the solution containing sodium oxide and aluminum oxide is discharged; after the filter press, fresh hot water is added under the pressure maintaining state to soak the retained solid again, and then the filter press is performed again to bring out the residual alkali and aluminum in the retained solid, thereby realizing the recovery of the alkali and aluminum oxide in the mixed slurry, and the solution containing the alkali and aluminum can be directly sent to the alumina red mud sedimentation system for recovery.

[0075] As an optional embodiment, the conditioning agent includes at least one of the following: citric acid, citrate, gluconate, tannic acid, aminocarboxylate;

[0076] In the above embodiment, the citrate is a mixture of one or more of calcium citrate, ferric citrate, magnesium citrate, and ammonium citrate; the gluconate is a mixture of calcium gluconate and sodium gluconate; and the aminocarboxylate is a mixture of one or more of trisodium nitrilotriacetate, tetrasodium ethylenediaminetetraacetic acid, and disodium magnesium ethylenediaminetetraacetic acid.

[0077] As an optional implementation, the mass of the conditioning agent is 0.005% to 0.5% of the mass of the calcium-based solid waste slurry desulfurizer.

[0078] In the above embodiment, the mass of the conditioning agent is controlled to be 0.005% to 0.5% of the mass of the calcium-based solid waste slurry desulfurizer because the conditioning agent can change the desulfurization efficiency of the slurry, enhance the agglomeration and precipitation performance of impurities, improve the desulfurization performance of calcium aluminate substances, and at the same time break the aggregation of carbon and active silicon in the slurry, reduce slurry foaming, and promote the discharge of aluminum ions. When the addition amount is greater than 0.5%, it not only causes a waste of conditioning agent, but also more substances enter the desulfurization slurry, which in turn causes a decrease in desulfurization efficiency; when the addition amount is less than 0.005%, the slurry conditioning effect does not change much, and the desulfurization efficiency and slurry desulfurization performance are not changed.

[0079] In a second aspect, based on a general inventive concept, the present application provides a desulfurizer, which is prepared by the preparation method of the calcium-based solid waste slurry desulfurizer described in the first aspect.

[0080] The desulfurizer is realized based on the preparation method of the above-mentioned calcium-based solid waste slurry desulfurizer. The specific steps of the preparation method of the calcium-based solid waste slurry desulfurizer can refer to the above-mentioned embodiment. Since the desulfurizer adopts part or all of the technical solutions of the above-mentioned embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, which will not be repeated here one by one.

[0081] In a third aspect, the present application provides a desulfurization method, comprising the following steps:

[0082] Obtaining the calcium-based solid waste slurry desulfurizer described in the second aspect;

[0083] The calcium-based solid waste slurry desulfurizer is subjected to a desulfurization reaction with the flue gas to be desulfurized to obtain a desulfurized slurry;

[0084] The pH of the desulfurization reaction is 4.8 to 6.2.

[0085] In the above embodiment, the calcium-based solid waste slurry desulfurizer is used to carry out desulfurization reaction with flue gas, which can realize the recycling and reuse of the calcium-based solid waste slurry. At the same time, due to the addition of a conditioning agent to the desulfurizer, not only the enrichment of aluminum ions in calcium aluminate and its hydrate in the solution is reduced, but also the aluminum ions are discharged from the desulfurization system together with the desulfurization by-products; at the same time, the influence of sodium on the desulfurization efficiency is further reduced, the enrichment reaction of sodium-calcium in the desulfurization system is reduced, and the blockage and scaling of the desulfurization system are reduced; finally, Huaneng improves the filtration performance of the desulfurization slurry, reduces the silicon-aluminum agglomeration performance of the desulfurization slurry, breaks the gelling property of active silicon, aluminum and magnesium, and reduces the water content of the desulfurization by-products. Exemplarily, the pH of the desulfurization reaction can be 4.8, 4.9, 5.0, 5.1, 5.2, 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1 or 6.2.

[0086] As an optional embodiment, the calcium-based solid waste slurry desulfurizer is subjected to a desulfurization reaction with the flue gas to be desulfurized to obtain a desulfurized slurry, which specifically includes:

[0087] The calcium-based solid waste slurry desulfurizer is fed into a desulfurization reactor to undergo a reverse desulfurization reaction with the flue gas to be desulfurized to obtain a desulfurized slurry.

[0088] In the above embodiment, the reverse desulfurization reaction is adopted to enable the flue gas to be desulfurized to fully contact with the desulfurizer, thereby achieving the desulfurization reaction to the maximum extent.

[0089] As an optional implementation manner, the temperature of the flue gas to be desulfurized in the desulfurization reaction is 50°C to 150°C.

[0090] In the above embodiment, the temperature of the flue gas to be desulfurized is controlled to be 50°C to 150°C because the temperature affects the desulfurization efficiency and the amount of solid sulfur. When the flue gas temperature exceeds 150°C, the reaction temperature is too high, the amount of evaporation of the desulfurizer slurry is large, the solid-liquid ratio is difficult to control, and the desulfurization efficiency decreases; when the flue gas temperature is lower than 50°C, the flue gas desulfurization efficiency is slow and the amount of desulfurizer slurry is large. Exemplarily, the temperature of the flue gas to be desulfurized in the desulfurization reaction is 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C.

[0091] As an optional embodiment, after the calcium-based solid waste slurry desulfurizer is subjected to a desulfurization reaction with the flue gas to be desulfurized to obtain a desulfurized slurry, the method further comprises:

[0092] The desulfurized slurry is subjected to solid-liquid separation to obtain a desulfurized solution and desulfurized solid slag.

[0093] In the above embodiment, the desulfurization solution contains excess alkali, aluminum, silicon and other substances, which can participate in the preparation process of the calcium-based solid waste slurry desulfurizer, or can be neutralized and set aside; the main components of the desulfurized solid slag are calcium sulfate, calcium oxide, silicon oxide, aluminum oxide and other components, with a pH value of 6 to 9, and can be used as a soil modifier.

[0094] As an optional implementation, when the desulfurization solution meets the set conditions, the desulfurization solution is subjected to a neutralization reaction to obtain secondary desulfurization solid slag;

[0095] The set conditions include: the total mass concentration of sodium and aluminum in the desulfurization solution is greater than 25g / L.

[0096] In the above embodiment, when the total mass concentration of sodium and aluminum in the desulfurization solution is less than 25 g / L, the desulfurization solution can be used to prepare a calcium-based solid waste slurry desulfurizer, such as in combination with a tempering agent; and when the total mass concentration of sodium and aluminum in the desulfurization solution is greater than 25 g / L, it is first necessary to perform a neutralization reaction to remove sodium and aluminum in the filtrate and reduce the sodium and aluminum content in the filtrate.

[0097] As an optional embodiment, the neutralization reaction of the desulfurization solution specifically includes: adding a neutralizing agent to the desulfurization solution for reaction; performing solid-liquid separation on the desulfurization solution after the reaction to obtain a secondary desulfurization solid residue and a washing water filtrate;

[0098] The neutralizing agent includes at least one of lime, calcium silicate and calcium silicate.

[0099] In the above embodiment, one or more of lime, calcium silicate and calcium silicate are used to react with sodium ions and aluminum ions in the desulfurization solution to generate calcium sulfate and aluminum hydroxide precipitates, thereby achieving the discharge of impurities.

[0100] As an optional implementation, the wash water filtrate can be mixed with calcium-based solid waste slurry in the desulfurization agent preparation process for recycling.

[0101] As an optional embodiment, in the neutralization reaction, the reaction temperature is 40°C to 100°C, the mass ratio of the desulfurization solution to the neutralizing agent is 10:(0.1 to 1.5), and the pH value is controlled at 7.2 to 10.5.

[0102] In the above embodiment, the reason for controlling the reaction temperature to 40°C to 100°C is that temperature affects the efficiency of the neutralization reaction. When the reaction temperature is lower than 40°C, the reaction rate is too slow, the reaction is incomplete, and more neutralizing agents need to be added, which is costly. Exemplarily, the reaction temperature can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C or 100°C.

[0103] In a fourth aspect, the present application provides a soil remediation agent, comprising the desulfurized solid slag and / or the secondary desulfurized solid slag described in the third aspect.

[0104] In the above embodiment, the desulfurization solid slag mainly contains calcium sulfate, calcium oxide, silicon oxide, aluminum oxide and other components, with a pH value of 6 to 9. The main components of the secondary desulfurization solid slag are calcium sulfate, calcium sulfite, aluminum sulfate, silicon oxide, with a pH value of 7.5 to 10, and can be used as a soil remediation agent.

[0105] As an optional implementation manner, it includes, by mass, 1 to 7 parts of desulfurization solid slag and / or secondary desulfurization solid slag, 10 to 25 parts of red mud, 1 to 3 parts of wood ash and 2 to 6 parts of soil.

[0106] In the above embodiment, the reason for controlling the mass fraction of the soil remediation agent is that red mud is a clay mineral, mainly composed of silicates, iron oxides, aluminum hydroxide and other substances. Wood ash can adjust the pH value of the soil and mainly contains carbonates and trace elements, thereby improving the soil structure. It can be used in combination with desulfurization solid slag and / or secondary desulfurization solid slag as a remediation agent for alkaline contaminated land.

[0107] 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.

[0108] The experimental conditions for the desulfurization reaction in the following examples and comparative examples are: SO2 concentration is 1000 mg / m 3 ~10000mg / m 3 , the desulfurization slurry pH value below 4.8 is used as the control index of the desulfurization reaction time.

[0109] Example 1

[0110] This embodiment provides a desulfurizing agent, and the preparation method comprises the following steps:

[0111] S1. The calcium-based solid waste slurry is sent to a pre-sedimentation tank, and the bottom flow of the sedimentation tank is sent to an alkali recovery reaction tank and diluted with hot water. After stirring for 0.5 hours, a calcium-based solid waste slurry reaction liquid is obtained; wherein the temperature of the calcium-based solid waste slurry reaction liquid is 70° C., and the solid-liquid ratio is 0.4;

[0112] S2, adding a phase change inhibitor to the calcium-based solid waste slurry reaction liquid to obtain a mixed slurry; wherein the amount of the phase change inhibitor is 0.05% of the total mass of sodium and aluminum in the reaction liquid, and the phase change inhibitor includes 3 parts of calcium gluconate, 5 parts of potassium gluconate and 2 parts of cellulose;

[0113] S3, filtering the mixed slurry in a primary liquid-solid separation device, washing, and filtering again to obtain a primary filtrate and a solid phase;

[0114] S4. Mix the solid phase material with water, adjust the temperature to 65°C, and then add a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer with a pH value of 8.2; wherein the mass of the conditioning agent accounts for 0.01% of the total mass of the calcium-based solid waste slurry desulfurizer; the conditioning agent includes 1 part of calcium citrate, 1 part of sodium citrate, 3 parts of disodium magnesium ethylenediaminetetraacetic acid, and 0.5 parts each of calcium gluconate and sodium gluconate.

[0115] Using it for desulfurization reaction includes the following steps:

[0116] The prepared calcium-based solid waste slurry desulfurizer is sent to a desulfurization reactor to carry out a reverse desulfurization reaction with the 50°C flue gas to be desulfurized to obtain a desulfurized slurry;

[0117] When the pH value of the desulfurized circulating slurry is lower than 4.8, the desulfurized slurry is sent to a secondary solid-liquid separation device for solid-liquid separation to obtain a desulfurized solution and desulfurized solid slag.

[0118] Among them, the content of sodium and aluminum in the desulfurization solution does not exceed 25g / L, so the desulfurization solution is directly used as the batching water of the solid phase material;

[0119] Desulfurized solid slag is used in the preparation of soil remediation agent as a soil ecological remediation agent for alkaline polluted land. The specific components include: 2 parts of desulfurized solid slag, 12 parts of red mud, 1.3 parts of wood ash, and 2.6 parts of soil.

[0120] Chemical analysis of the desulfurized solid slag showed that the solid sulfur content of the desulfurized solid slag was 35.1%, the sodium oxide content was 0.02%, the aluminum oxide content was 0.49%, and the water content was 7.8%.

[0121] Example 2

[0122] This embodiment provides a desulfurizing agent, and the preparation method comprises the following steps:

[0123] S1. Send the calcium-based solid waste slurry into a pre-sedimentation tank, send the bottom flow of the sedimentation tank to an alkali recovery reaction tank and add hot water for dilution, and obtain a calcium-based solid waste slurry reaction liquid after stirring for 3 hours; wherein the temperature of the calcium-based solid waste slurry reaction liquid is 90° C. and the solid-liquid ratio is 0.3;

[0124] S2, adding a phase change inhibitor to the calcium-based solid waste slurry reaction liquid to obtain a mixed slurry; wherein the amount of the phase change inhibitor is 0.11% of the total mass of sodium and aluminum in the reaction liquid, and the phase change inhibitor includes 1 part of calcium gluconate, 5 parts of potassium gluconate, 3 parts of cellulose, 0.5 parts of wood calcium, and 0.1 parts of sodium humate;

[0125] S3, filtering the mixed slurry in a primary liquid-solid separation device, washing, and filtering again to obtain a primary filtrate and a solid phase;

[0126] S4. Mix the solid phase material with water, control the temperature to 80°C and add a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer with a pH value of 7; wherein the mass of the conditioning agent is 0.5% of the total mass of the calcium-based solid waste slurry desulfurizer; the conditioning agent includes 3 parts of ammonium citrate, 0.8 parts of trisodium nitrilotriacetate, 3 parts of disodium magnesium ethylenediaminetetraacetic acid, and 0.5 parts each of calcium gluconate and sodium gluconate.

[0127] Using it for desulfurization reaction includes the following steps:

[0128] The prepared calcium-based solid waste slurry desulfurizer is sent to a desulfurization reactor to carry out a reverse desulfurization reaction with the flue gas to be desulfurized at 60°C to obtain a desulfurized slurry;

[0129] When the pH value of the desulfurized circulating slurry is lower than 4.8, the desulfurized slurry is sent to a secondary solid-liquid separation device for solid-liquid separation to obtain a desulfurized solution and desulfurized solid slag.

[0130] Among them, the content of sodium and aluminum in the desulfurization solution does not exceed 25g / L, so the desulfurization solution is directly used as the batching water of the solid phase material;

[0131] Desulfurized solid slag is used in the preparation of soil remediation agent as a soil ecological remediation agent for alkaline polluted land. The specific components include: 1 part of desulfurized solid slag, 25 parts of red mud, 3 parts of wood ash and 4 parts of soil.

[0132] Chemical analysis of the desulfurized solid slag showed that the solid sulfur content of the desulfurized solid slag was 36.2%, the sodium oxide content was 0.015%, the aluminum oxide content was 0.4%, and the water content was 7.0%.

[0133] Example 3

[0134] This embodiment provides a desulfurizing agent, and the preparation method comprises the following steps:

[0135] S1. The calcium-based solid waste slurry is sent to a pre-sedimentation tank, and the bottom flow of the sedimentation tank is sent to an alkali recovery reaction tank and diluted with hot water. After stirring for 5 hours, a calcium-based solid waste slurry reaction liquid is obtained; wherein the temperature of the calcium-based solid waste slurry reaction liquid is 95° C., and the solid-liquid ratio is 1;

[0136] S2, adding a phase change inhibitor to the calcium-based solid waste slurry reaction liquid to obtain a mixed slurry; wherein the amount of the phase change inhibitor is 0.15% of the total mass of sodium and aluminum in the reaction liquid, and the phase change inhibitor includes 0.1 parts of calcium gluconate, 0.5 parts of potassium gluconate, 2 parts of cellulose, 1 part of wood calcium, and 0.5 parts of sodium humate;

[0137] S3, filtering the mixed slurry in a primary liquid-solid separation device, washing, and filtering again to obtain a primary filtrate and a solid phase;

[0138] S4. Mix the solid phase material with water, control the temperature to 90°C and add a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer with a pH value of 10; wherein the mass of the conditioning agent is 0.005% of the total mass of the calcium-based solid waste slurry desulfurizer; the conditioning agent includes 2 parts of sodium citrate, 1 part of ferric citrate, 1 part of tetrasodium ethylenediaminetetraacetic acid, and 0.5 parts each of calcium gluconate and sodium gluconate.

[0139] Using it for desulfurization reaction includes the following steps:

[0140] The prepared calcium-based solid waste slurry desulfurizer is sent to a desulfurization reactor to carry out a reverse desulfurization reaction with the 150°C flue gas to be desulfurized to obtain a desulfurized slurry;

[0141] When the pH value of the desulfurized circulating slurry is lower than 4.8, the desulfurized slurry is sent to a secondary solid-liquid separation device for solid-liquid separation to obtain a desulfurized solution and desulfurized solid slag.

[0142] Among them, the content of sodium and aluminum in the desulfurization solution does not exceed 25g / L, so the desulfurization solution is directly used as the batching water of the solid phase material;

[0143] Desulfurized solid slag is used in the preparation of soil remediation agent as a soil ecological remediation agent for alkaline polluted land. The specific components include: 7 parts of desulfurized solid slag, 20 parts of red mud, 1.5 parts of wood ash and 6 parts of soil.

[0144] Chemical analysis of the desulfurized solid slag showed that the solid sulfur content of the desulfurized solid slag was 36.7%, the sodium oxide content was 0.02%, the aluminum oxide content was 0.5%, and the water content was 8%.

[0145] Example 4

[0146] This embodiment provides a desulfurizing agent, and the preparation method comprises the following steps:

[0147] S1. Send the calcium-based solid waste slurry into a pre-sedimentation tank, send the bottom flow of the sedimentation tank to an alkali recovery reaction tank and add hot water for dilution, and stir for 3.5 hours to obtain a calcium-based solid waste slurry reaction liquid; wherein the temperature of the calcium-based solid waste slurry reaction liquid is 100° C., and the solid-liquid ratio is 0.6;

[0148] S2, adding a phase change inhibitor to the calcium-based solid waste slurry reaction liquid to obtain a mixed slurry; wherein the amount of the phase change inhibitor accounts for 0.08% of the total mass of sodium and aluminum in the reaction liquid, and the phase change inhibitor includes 1 part of calcium gluconate, 0.8 parts of cellulose, and 2 parts of wood calcium;

[0149] S3, filtering the mixed slurry in a primary liquid-solid separation device, washing, and filtering again to obtain a primary filtrate and a solid phase;

[0150] S4. Mix the solid phase material with water, control the temperature to 75°C and add a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer with a pH value of 8.1; wherein the mass of the conditioning agent is 0.01% of the total mass of the calcium-based solid waste slurry desulfurizer; the conditioning agent includes 2 parts of sodium citrate, 0.5 parts of trisodium nitrilotriacetate, 0.5 parts of tetrasodium ethylenediaminetetraacetic acid, 1.2 parts each of calcium gluconate and sodium gluconate, and 0.6 parts of tannic acid.

[0151] Using it for desulfurization reaction includes the following steps:

[0152] The prepared calcium-based solid waste slurry desulfurizer is sent to a desulfurization reactor to carry out a reverse desulfurization reaction with the 100°C flue gas to be desulfurized to obtain a desulfurized slurry;

[0153] When the pH value of the desulfurized circulating slurry is lower than 4.8, the desulfurized slurry is sent to a secondary solid-liquid separation device for solid-liquid separation to obtain a desulfurized solution and desulfurized solid slag.

[0154] The content of sodium and aluminum in the desulfurization solution exceeds 25 g / L, the desulfurization solution is reacted with lime, the solid-liquid ratio is 0.01, the reaction temperature is 40°C, the reaction time is 5 hours, and after the reaction, it is sent to a three-stage solid-liquid separation device to obtain a wash water filtrate and a secondary desulfurization solid slag;

[0155] The washing water filtrate is sent to the pre-sedimentation tank, and the secondary desulfurization solid slag and the desulfurization solid slag mixture are used to prepare the soil remediation agent as a soil ecological remediation agent for alkaline contaminated land. The specific components include: 7 parts of desulfurization solid slag and secondary desulfurization solid slag mixture, 17 parts of red mud, 2 parts of wood ash and 2.5 parts of soil.

[0156] Chemical analysis of the desulfurized solid slag showed that the solid sulfur content of the desulfurized solid slag was 35.5%, the sodium oxide content was 0.018%, the aluminum oxide content was 0.45%, and the water content was 7.5%.

[0157] Example 5

[0158] This embodiment provides a desulfurizing agent, and the preparation method comprises the following steps:

[0159] S1. Send the calcium-based solid waste slurry into a pre-sedimentation tank, send the bottom flow of the sedimentation tank to an alkali recovery reaction tank and add hot water for dilution, and obtain a calcium-based solid waste slurry reaction liquid after stirring for 2 hours; wherein the temperature of the calcium-based solid waste slurry reaction liquid is 88° C. and the solid-liquid ratio is 0.75;

[0160] S2, adding a phase change inhibitor to the calcium-based solid waste slurry reaction liquid to obtain a mixed slurry; wherein the amount of the phase change inhibitor is 0.06% of the total mass of sodium and aluminum in the reaction liquid, and the phase change inhibitor includes 1.5 parts of calcium gluconate, 1.2 parts of cellulose, 1.8 parts of wood calcium, and 0.1 parts of sodium humate;

[0161] S3, filtering the mixed slurry in a primary liquid-solid separation device, washing, and filtering again to obtain a primary filtrate and a solid phase;

[0162] S4. Mix the solid phase material with water, control the temperature to 68°C and add a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer with a pH value of 7.6; wherein the mass of the conditioning agent is 0.09% of the total mass of the calcium-based solid waste slurry desulfurizer; the conditioning agent includes 1 part of sodium citrate, 1.2 parts of calcium gluconate and sodium gluconate each, 0.5 part of trisodium nitrilotriacetate, and 0.9 part of disodium magnesium ethylenediaminetetraacetic acid.

[0163] Using it for desulfurization reaction includes the following steps:

[0164] The prepared calcium-based solid waste slurry desulfurizer is sent to a desulfurization reactor to carry out a reverse desulfurization reaction with the flue gas to be desulfurized at 70°C to obtain a desulfurized slurry;

[0165] When the pH value of the desulfurized circulating slurry is lower than 4.8, the desulfurized slurry is sent to a secondary solid-liquid separation device for solid-liquid separation to obtain a desulfurized solution and desulfurized solid slag.

[0166] Wherein, the content of sodium and aluminum in the desulfurization solution exceeds 25g / L, the desulfurization solution is reacted with a mixture of 0.5 parts of lime, 1 part of calcium silicate slag and 0.5 parts of calcium silicate, with a solid-liquid ratio of 0.15, a reaction temperature of 100°C, a reaction time of 1h, and after the reaction, it is sent to a three-stage solid-liquid separation device to obtain a wash filtrate and a secondary desulfurization solid slag;

[0167] The washing water filtrate is sent to the pre-sedimentation tank, and the secondary desulfurization solid slag and the desulfurization solid slag mixture are used to prepare the soil remediation agent as a soil ecological remediation agent for alkaline contaminated land. The specific components include: 5 parts of desulfurization solid slag and secondary desulfurization solid slag mixture, 13 parts of red mud, 3 parts of wood ash and 1 part of soil.

[0168] Chemical analysis of the desulfurized solid slag showed that the desulfurized solid slag calcium-based solid waste slag had a sulfur content of 37.1%, a sodium oxide content of 0.01%, an aluminum oxide content of 0.39%, and a water content of 7.3%.

[0169] Comparative Example 1

[0170] This comparative example provides a desulfurizer, and its preparation method is the same as that in Example 5, except that in this comparative example, no phase change inhibitor is added, and a conditioning agent is directly added to the calcium-based solid waste slurry reaction liquid to obtain a calcium-based solid waste slurry desulfurizer;

[0171] The prepared calcium-based solid waste slurry desulfurizer was used for desulfurization reaction, and the reaction steps were the same as the desulfurization reaction steps in Example 5. The final results showed that the desulfurized solid slag in this comparative example had a solid sulfur content of 22.4%, a sodium oxide content of 1.7%, an aluminum oxide content of 2.5%, and a water content of 20.6%.

[0172] Comparative Example 2

[0173] This comparative example provides a desulfurizer, and its preparation method is the same as that in Example 5, except that in this comparative example, no conditioning agent is added, and the solid phase material after the mixed slurry is filtered is directly mixed with water to obtain a calcium-based solid waste slurry desulfurizer;

[0174] The prepared calcium-based solid waste slurry desulfurizer was used for desulfurization reaction, and the reaction steps were the same as the desulfurization reaction steps in Example 5. The final results showed that the desulfurized solid slag in this comparative example had a solid sulfur content of 26.8%, a sodium oxide content of 0.05%, an aluminum oxide content of 1.2%, and a water content of 25.9%.

[0175] Comparative Example 3

[0176] This comparative example provides a desulfurizer, and its preparation method is the same as that in Example 5, except that in this comparative example, no phase change inhibitor and conditioning agent are added, and after the solid-liquid separation of the calcium-based solid waste slurry reaction liquid, the solid phase material is mixed with water to form a calcium-based solid waste slurry desulfurizer;

[0177] The prepared calcium-based solid waste slurry desulfurizer was used for desulfurization reaction, and the reaction steps were the same as the desulfurization reaction steps in Example 5. The final results showed that the desulfurized solid slag in this comparative example had a solid sulfur content of 20.8%, a sodium oxide content of 2.2%, an aluminum oxide content of 2.8%, and a water content of 37.1%.

[0178] Comparative Example 4

[0179] This comparative example provides a desulfurizer, and its preparation method is the same as that in Example 5, except that in this comparative example, the mixed slurry obtained by adding the phase change inhibitor is not subjected to solid-liquid separation, and a conditioning agent is directly added to obtain a calcium-based solid waste slurry desulfurizer;

[0180] The prepared calcium-based solid waste slurry desulfurizer was used for desulfurization reaction, and the reaction steps were the same as the desulfurization reaction steps in Example 5. The final results showed that the desulfurized solid slag in this comparative example had a solid sulfur content of 27.3%, a sodium oxide content of 0.19%, an aluminum oxide content of 0.78%, and a water content of 9.2%.

[0181] Comparative Example 5

[0182] This comparative example provides a desulfurizing agent, and the preparation method comprises the following steps:

[0183] The calcium-based solid waste slurry is sent to the pre-sedimentation tank, and the bottom flow of the calcium-based solid waste slurry is directly subjected to liquid-solid separation. The solid slag separated by liquid-solid separation is mixed with water to prepare a calcium-based solid waste slurry desulfurizer, and the liquid-solid ratio is the same as that in Example 5. The above-mentioned fresh desulfurized slurry is contacted with sulfur-containing flue gas for reaction. After analysis, the desulfurized solid slag in this comparative example has a solid sulfur content of 15.7%, a sodium oxide content of 2.5%, an aluminum oxide content of 4.7%, and a water content of 55%.

[0184] In summary, Examples 1 to 5 all adopt the desulfurizer preparation method provided in the present application to prepare the desulfurizer and conduct desulfurization experiments. The results show that the solid sulfur content of the obtained desulfurized solid slag is greater than 35%, and the contents of sodium oxide and aluminum oxide are less than 1%. In Comparative Examples 1 to 5, some technical means in Example 5 of the present application are replaced to prepare the desulfurizer. Compared with Example 5, the solid sulfur content is reduced, and the contents of sodium oxide and aluminum oxide in the desulfurized solid slag are relatively high. The reasons are analyzed as follows:

[0185] No phase change inhibitor was added during the preparation of the desulfurizer provided in Comparative Example 1, and therefore the material composition in the calcium-based solid waste slurry reaction liquid was not changed. Although a tempering agent was added, a large amount of aluminum oxide and sodium oxide entered the desulfurization system. At the same time, the solid phase material contained calcium aluminate, hydrocalumite and other substances, and the tempering effect was limited, so that the prepared desulfurizer affected the flue gas desulfurization efficiency and reduced the fixed sulfur amount.

[0186] The desulfurizer provided in Comparative Example 2 does not add a tempering agent during the preparation process. As the desulfurization reaction proceeds during the desulfurization process, impurities begin to accumulate, the filtration performance of the desulfurizer slurry deteriorates, the desulfurization efficiency is affected, and the contact area between the desulfurizer slurry and the flue gas reaction is reduced, resulting in a decrease in desulfurization performance and an increase in the moisture content of the desulfurized solid slag.

[0187] The desulfurizer provided in Comparative Example 3 has a preparation method comprising: adding hot water to dilute the calcium-based solid waste slurry sedimentation underflow, stirring for 2 hours, and then separating the solid-liquid reaction liquid of the obtained calcium-based solid waste slurry, and mixing the solid phase material with water as a desulfurizer. After the liquid-solid separation of the desulfurizer, although the sodium oxide content in the solid phase material is reduced to a certain extent, the composition properties of the solid phase material are not changed, and it still contains more calcium aluminate, calcium aluminate, hydrocalumite, calcium hydroxide, sodium carbonate, and sodium hydroxide. When it is used as a desulfurizer for desulfurization reaction, as the desulfurization reaction continues, it will also cause more and more soluble salts in the desulfurization slurry, the desulfurization slurry is viscous, and the desulfurization efficiency is low, resulting in poor desulfurization performance.

[0188] In the desulfurizer provided in Comparative Example 4, after the phase change inhibitor is added, the mixed slurry is not separated into solid and liquid, and the aluminum oxide and sodium oxide in the slurry directly enter the desulfurization system. Compared with the embodiment, although the addition of the conditioning agent weakens the influence of aluminum and sodium, the amount of solid sulfur is still reduced. At the same time, compared with Comparative Example 2, it is also shown that the addition of the conditioning agent helps to improve the desulfurization performance of the slurry containing aluminum and sodium impurities, and helps to reduce the moisture content of the desulfurized solid slag.

[0189] The desulfurizer provided in Comparative Example 5 is obtained by directly separating the calcium-based solid waste slurry from the bottom flow by liquid-solid separation, and then mixing the solid phase with water; since the solid slag obtained by liquid-solid separation contains more calcium aluminate, calcium aluminate, hydrocalumite, calcium hydroxide, sodium carbonate and sodium hydroxide, the soluble salts in the desulfurization slurry are increasing, the desulfurization slurry is viscous, the desulfurization efficiency is low, and gypsum filtering is difficult, resulting in poor desulfurization performance and a small amount of sulfur dioxide capture.

[0190] In summary, a method for preparing a calcium-based solid waste slurry desulfurizer is provided in an embodiment of the present application, the method comprising: subjecting the calcium-based solid waste slurry to sedimentation treatment, sending the sedimentation overflow to an alumina slurry dilution tank, adding hot water and a phase change inhibitor to the sedimentation underflow to obtain a mixed slurry; separating the mixed slurry from solid and liquid, sending the filtrate to an alumina red mud sedimentation separation and washing system, mixing the filter cake with water and adding a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer; the calcium-based solid waste slurry desulfurizer reacts with flue gas to undergo a desulfurization reaction, and after the desulfurization slurry is subjected to solid-liquid separation, a desulfurization solution and a desulfurization solid slag are obtained; the desulfurization solution is subjected to a neutralization reaction treatment and then subjected to solid-liquid separation to obtain a wash water filtrate and a secondary desulfurization solid slag; the desulfurization solid slag and the secondary desulfurization solid slag are used to prepare a soil ecological restoration agent. The present invention utilizes the calcium-based solid waste slurry discharged from alumina to prepare the desulfurizer, which not only recovers the alkali resources and reduces the loss of alumina, but also is used for flue gas desulfurization, thus achieving the purpose of resource utilization of solid waste, and has the value and significance of pollution reduction, carbon reduction and synergistic efficiency improvement.

[0191] 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 calcium-based solid waste slurry desulfurizer, comprising the following steps: Obtaining a calcium-based solid waste slurry reaction liquid; adding a phase change inhibitor to the calcium-based solid waste slurry reaction liquid to obtain a mixed slurry; The mixed slurry is subjected to solid-liquid separation to obtain a solid phase substance; The solid phase material is mixed with water and a conditioning agent to obtain a calcium-based solid waste slurry desulfurizer; Wherein, the pH value of the calcium-based solid waste slurry desulfurizer is 7-10.

2. The preparation method according to claim 1, wherein the calcium-based solid waste slurry reaction liquid is obtained, specifically comprising: The calcium-based solid waste slurry is sedimented to obtain an underflow of the calcium-based solid waste slurry; diluting the calcium-based solid waste slurry underflow to obtain a calcium-based solid waste slurry reaction liquid; The solid-liquid ratio of the calcium-based solid waste slurry reaction liquid is (0.1-1):

1.

3. The preparation method according to claim 1, wherein the added mass of the phase change inhibitor accounts for 0.02% to 0.15% of the total mass of sodium and aluminum in the calcium-based solid waste slurry reaction solution; and / or, The phase change inhibitor comprises at least one of the following: sugar acid salt, cellulose, wood calcium and sodium humate.

4. The preparation method according to claim 1, wherein the conditioning agent comprises at least one of the following: citric acid, citrate, gluconate, tannic acid and aminocarboxylate; and / or, The mass of the conditioning agent is 0.005% to 0.5% of the total mass of the calcium-based solid waste slurry desulfurizer.

5. A desulfurizing agent, prepared by the preparation method of the calcium-based solid waste slurry desulfurizing agent according to any one of claims 1 to 4.

6. A desulfurization method comprising the following steps: Obtaining the calcium-based solid waste slurry desulfurizer according to claim 5; The calcium-based solid waste slurry desulfurizer is subjected to a desulfurization reaction with the flue gas to be desulfurized to obtain a desulfurized slurry; The pH of the desulfurization reaction is 4.8 to 6.

2.

7. The desulfurization method according to claim 6, after the calcium-based solid waste slurry desulfurizer is subjected to a desulfurization reaction with the flue gas to be desulfurized to obtain a desulfurized slurry, further comprising: The desulfurized slurry is subjected to solid-liquid separation to obtain a desulfurized solution and desulfurized solid slag.

8. The desulfurization method according to claim 7, wherein when the desulfurization solution meets the set conditions, the desulfurization solution is subjected to a neutralization reaction to obtain a secondary desulfurization solid slag; The setting conditions include: The total mass concentration of sodium and aluminum in the desulfurization solution is greater than 25 g / L.

9. A soil remediation agent, comprising the desulfurized solid slag described in claim 7 and / or the secondary desulfurized solid slag described in claim 8.

10. The soil remediation agent according to claim 9, comprising, by weight, 1 to 7 parts of desulfurized solid slag and / or secondary desulfurized solid slag, 10 to 25 parts of red mud, 1 to 3 parts of plant ash and 2 to 6 parts of soil.

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