Composition for treating waste residues generated in sodium carbonate preparation through ammonia-alkali method, method for preparing engineering soil through composition and application of engineering soil

Abstract

The invention relates to the technical field of waste residue treatment, in particular to a composition for treating waste residues generated in sodium carbonate preparation through an ammonia-alkali method, a method for preparing engineering soil through the composition and application of the engineering soil. The composition comprises the following components in parts by weight: 20 parts of ferrous sulfate, 20 parts of citric acid, 10 parts of composite organic acid, 5 parts of a modifier, 5 parts of a catalyst and 40 parts of water, the composite organic acid is a chelating agent of citric acid and tartaric acid. The method treats waste with waste, and is simple in process, low in cost, mild in reaction condition, short in process period, low in energy consumption, large in treatment capacity, safe, efficient, green and environment-friendly; a thermal refining method is adopted, one-step treatment is achieved, the follow-up outward transportation amount is basically not increased, and the purposes of preparing engineering soil and meeting the stacking requirement are achieved. The engineering soil can also be used as common soil and can also be used for vegetation growth.

Description

Technical Field

[0001] The present invention relates to the technical field of waste residue treatment, and particularly to a composition for treating waste residue generated in the production of soda ash by the ammonia-alkali method, a method for preparing engineering soil therefrom, and an application thereof. Background Art

[0002] Engineering soil indexes: (1) Meet the relevant technical standards for medium saline soil in the "Code for Geotechnical Investigation" (GB 50021-2001 (2009 Edition)). (2) Meet the relevant indexes in the "Soil Environmental Quality Risk Control Standards for Construction Land Soil Pollution" (GB36600-2018). The engineering soil made from alkali residue is mainly used for filling municipal land and green spaces according to the application scenarios, belonging to the first type of land use, and needs to meet the screening value limit requirements for the first type of land use in the "Soil Environmental Quality Risk Control Standards for Construction Land Soil Pollution (Trial)" (GB36600-2018): (3) When the engineering soil made from alkali residue is used for filling, it needs to meet the relevant technical requirements in the "Quality Control Standards for Land Reclamation" (TD / T1036-2013). The bearing capacity index of the engineering soil needs to be better than that of the proposed backfill area. It is required that the bearing capacity index of the engineering soil used for land reclamation is greater than 100 kPa, fully meeting the bearing capacity requirements of the application scenario. (4) The pH value meets the requirements for slight and moderate alkalization in the "Technical Guidelines for Environmental Impact Assessment - Soil Environment" (HJ 964-2018) (pH value < 9.5).

[0003] The currently adopted methods mainly include: 1. Directly mixing with fly ash and landfilling. The defects of this method are that the pH value is high, not meeting the landfill standard of engineering soil, the amount of fly ash is large and it is not easy to purchase and the cost is high, and the mixing is difficult; it increases the total amount of pollutants, resulting in an increase in the cost of transporting external materials. 2. Adding concentrated sulfuric acid (sulfuric acid content 93%) and loess to achieve the purpose of modification for easy stacking. The defects of this method are that the components of sulfuric acid are uncertain (such as sulfuric acid produced from smelting tail gas may contain some harmful elements), sulfuric acid is a hazardous chemical controlled by the state, it is an inorganic strong acid with strong corrosiveness and oxidizing property, posing potential hazards to equipment, pipelines, and operators, with high danger in operation and great potential safety hazards. There are sundries such as grass roots, tree roots, and stones in the loess, which are easy to block the production system, causing the production to be discontinuous. The addition ratio of loess is high (the current addition amount of loess is 20% - 40%), increasing the total amount of pollutants, and increasing the amount and cost of transporting external materials. The operation is complicated and the labor intensity is high. Summary of the Invention

[0004] To solve the above problems, the present invention provides a composition for treating waste residue generated in the production of soda ash by the ammonia-alkali process, a method for preparing engineering soil therefrom, and an application thereof. The present invention aims to provide a process that is simple, easy to operate, has mild reaction conditions, a short process cycle, low energy consumption, fast reaction speed, large treatment capacity, is safe and efficient, and is environmentally friendly and green; by using a tempering treatment method, it can be treated in one step without increasing the total amount of pollutants, achieving the purpose of making engineering soil that meets the requirements for stacking and landfill.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a composition for treating waste residue generated in the production of soda ash by the ammonia-alkali process, comprising the following components in parts by weight:

[0007] 20 parts of ferrous sulfate, 20 parts of citric acid, 10 parts of composite organic acid, 5 parts of modifier, 5 parts of catalyst, and 40 parts of water;

[0008] The composite organic acid is a chelating agent of citric acid, tartaric acid, and water, and the mass ratio of citric acid, tartaric acid, and water is 12:8:80.

[0009] Preferably, the modifier is ceramic powder with a particle size of 5 mm to 1 cm.

[0010] Preferably, the catalyst is prepared by compounding FeCl3 solution and polyferric sulfate solution in an equal mass ratio;

[0011] The mass percentage content of the FeCl3 solution is 20 to 30%;

[0012] The mass percentage content of the polyferric sulfate solution is 30%.

[0013] The present invention also provides an application of the composition described in the above technical solution in treating waste residue generated in the production of soda ash by the ammonia-alkali process.

[0014] The present invention provides a method for preparing engineering soil from waste residue generated in the production of soda ash by the ammonia-alkali process, comprising the following steps:

[0015] 1) Mix the composition described in the above technical solution with the waste residue to obtain a mixture;

[0016] 2) Aerate and react the mixture obtained in step 1), and after solid-liquid separation, the obtained solid is engineering soil.

[0017] Preferably, the volume ratio of the composition to the mass of the waste residue in step 1) is 3 to 4 mL:100 g.

[0018] Preferably, the volume ratio of the composition to the waste residue in step 1) is 82:253.

[0019] Preferably, the pH value of the waste residue in step 1) is 11.0 - 12.0, and the solid content is 20 - 30%.

[0020] Preferably, the conditions for the aeration reaction in step 2) include: the time is 0.5 - 4.5 h.

[0021] Preferably, the time for the aeration reaction is 1 h.

[0022] The mechanism of the composition for treating waste residue in the present invention is as follows:

[0023] Through the reaction, divalent iron ions are uniformly coated on the surface of the alkali residue particles, and at the same time, the acidity of ferrous sulfate is used to reduce the pH value; after aeration, the divalent iron ions are oxidized into trivalent iron ions, making the particles turn red as a whole. In this process, by controlling the dosage of ferrous sulfate, the required reddish-brown engineering soil is obtained.

[0024] Beneficial effects:

[0025] The present invention uses waste to treat waste, has a simple process, low cost, mild reaction conditions, short process cycle, low energy consumption, large treatment capacity, is safe and efficient, and is green and environmentally friendly; by adopting the method of conditioning treatment, it can be treated in one step, and basically does not increase the subsequent amount of transported materials, achieving the purpose of making engineering soil and meeting the stacking requirements. Such engineering soil can also be used as ordinary soil and can also be used for vegetation growth. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the embodiments.

[0027] Figure 1 It is the process flow chart of the present invention;

[0028] Figure 2 It is the test flow chart of the present invention;

[0029] Figure 3 It is the test process diagram;

[0030] Figure 4 It is the experimental result of Example 2;

[0031] Figure 5 It is the test result of the engineering soil mechanical properties in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0032] The present invention provides a composition for treating waste residue generated in the production of soda ash by the ammonia-alkali method, comprising the following components in parts by weight: 20 parts of ferrous sulfate, 20 parts of citric acid, 10 parts of composite organic acid, 5 parts of modifier, 5 parts of catalyst and 40 parts of water; the composite organic acid is a chelating agent of citric acid, tartaric acid and water. In the present invention, the preparation method of the composite organic acid preferably includes: adding 12 grams of citric acid to 80 grams of water, stirring for 20 minutes, and then adding 8 grams of tartaric acid and stirring for 1 hour to obtain the composite organic acid. In the present invention, the modifier is preferably ceramic powder. In the present invention, the main components of the ceramic powder are silicon dioxide and aluminum trioxide, and the pH value is 6.0-7.0; the particle size is 5 mm-1 cm. In the present invention, the ceramic powder is a common building material, and there is no special regulation on the source of the ceramic powder in the present invention, and it can be obtained by conventional commercial purchase, such as from Zibo Luzhou Porcelain Industry Co., Ltd., Shandong Kangdefumei Greenway Co., Ltd., Foshan Henghui Ceramics Co., Ltd., etc.

[0033] In the present invention, the catalyst is preferably prepared by compounding FeCl3 solution and polyferric sulfate solution according to an equal mass ratio. In the present invention, the mass percentage content of the FeCl3 solution is preferably 20-30%. In the present invention, the mass percentage content of the polyferric sulfate solution is preferably 30%. In the present invention, the relative density of the polyferric sulfate is 2.44, and it is a common chemical raw material. There is no special limitation on the source of the polyferric sulfate in the present invention, and it can be obtained by conventional commercial purchase, such as from Lanzhou Beichen Environmental Protection Technology, Henan Shengfulai Environmental Protection Technology, Henan Tangda Water Purification Materials Co., Ltd., etc.

[0034] In the present invention, the ferrous sulfate: (the molecular weight of FeSO4·7H2O is 278.01), and in the present invention, its coloring property is used to change the color of the alkali residue. In the present invention, the citric acid: (the molecular weight of C6H8O7 is 192.12), and in the present invention, its acidity is used to adjust the pH value of the alkali residue. In the present invention, the composite organic acid is a chelating agent of citric acid and tartaric acid, and in the present invention, its acidity is used to finely adjust the pH of the alkali residue and specifically chelate metal residues. In the present invention, the modifier is nano-ceramic powder, and in the present invention, its chemical bond is used to enhance the strength and compressive resistance of the alkali residue and improve the bearing capacity. In the present invention, the catalyst is composed of FeCI3 solution with a solid content of 20%-30% and polyferric sulfate solution with a solid content of 30%; they are compounded and each accounts for 50% by mass ratio in the catalyst. In the present invention, it is used to increase the reaction rate without changing the total standard Gibbs free energy change of the reaction. In the present invention, the water plays a dissolving role in the present invention.

[0035] The present invention has no special limitation on the preparation method of the composition, and conventional mixing can be used.

[0036] The present invention also provides an application of the composition described in the above technical solution in the treatment of waste residue generated in the production of soda ash by the ammonia-alkali process.

[0037] The present invention also provides a method for preparing engineering soil by using waste residue generated in the production of soda ash by the ammonia-alkali process, comprising the following steps:

[0038] 1) Mix the composition described in the above technical solution with the waste residue to obtain a mixture;

[0039] 2) Aerate and react the mixture obtained in step 1), and after solid-liquid separation, the obtained solid is engineering soil.

[0040] In the present invention, the volume ratio of the composition to the mass of the waste residue is preferably 3-4 mL: 100 g. In the present invention, the volume ratio of the composition to the waste residue is preferably 82:253. In the present invention, the pH value of the waste residue is preferably 11.0-12.0, and the solid content is preferably 20-30%. The present invention has no special limitation on the source of the waste residue, and it is preferably the waste residue generated in the production of soda ash by the ammonia-alkali process.

[0041] In the present invention, the conditions of the aeration reaction (without special requirements) preferably include: the time is 0.5-4.5 h. In the present invention, the time of the aeration reaction is preferably 1 h. The present invention has no special limitation on other conditions of the aeration reaction, and conventional ones can be adopted.

[0042] In order to further illustrate the present invention, the present invention will be described in detail below with reference to examples, but they should not be construed as limiting the protection scope of the present invention.

[0043] Example 1

[0044] A composition for treating waste residue generated in the production of soda ash by the ammonia-alkali process contains the following components in mass percentage:

[0045] 1. Ferrous sulfate: (FeSO4·7H2O molecular weight 278.01), accounting for 20% of the mass of the composition;

[0046] 2. Citric acid: (C6H8O7 molecular weight 192.12), accounting for 20% of the mass of the composition;

[0047] 3. Composite organic acid: a chelating agent of citric acid and tartaric acid, accounting for 10% of the mass of the composition; the preparation method of the composite organic acid is: add 12 g of citric acid to 80 g of water, stir for 20 minutes, and then add 8 g of tartaric acid and stir for 1 hour to obtain the composite organic acid;

[0048] 4. The modifier is ceramic powder, accounting for 5% of the mass of the composition;

[0049] 5. Catalyst: Obtained by mixing FeCl3 solution and polyferric sulfate solution in equal mass. The mass percentage content of FeCl3 solution is 20%, and the solid content of polyferric sulfate solution is 30%. The catalyst accounts for 5% of the mass of the composition.

[0050] 6. Water: It accounts for 40% of the mass of the composition.

[0051] Process steps:

[0052] (1) Dissolve ferrous sulfate in water;

[0053] (2) Sequentially add citric acid, compound organic acid, modifier, and catalyst, and stir well to mix to obtain the composition;

[0054] (3) Add the composition to the alkali residue slurry (pH value 11.0 - 12.0, solid content 10 - 12%) at a ratio of 3 - 5% of the amount of the alkali residue slurry, and aerate and mix well for reaction for 1 hour;

[0055] (4) Perform solid-liquid separation, and the qualified filtrate is discharged according to regulations; the solid is the prepared engineering soil with a bearing capacity of 110 kPa.

[0056] For four batches of laboratory small-scale tests with different pH adjustments, while ensuring that the pH of the slag slurry meets the index requirements, adjust the reagent ratio to reduce the reagent cost. The test data are shown in Table 1:

[0057] Table 1 Test data results

[0058]

[0059] Example 2

[0060] 1. Basic test situation

[0061] Based on the laboratory small-scale test of Example 1, from June 24th to June 30th, 2024, the composition of Example 1 was used for the test. A total of 2 batches of tests were carried out, treating 253 m 3 of wet alkali residue, verifying the operation status of 7 filter presses, and preparing 170 tons of engineering soil. The pH value of the wet alkali residue before treatment was 11.8, and the pH value after treatment was 7.5 - 9.5.

[0062] Among them, (1) Physical properties of wet alkali residue: The moisture content of alkali residue is 25.5% - 76%, with an average of 65.6%. The solid components mostly exist in a granular state. The particles with a particle size between 2.0 μm and 25.0 μm account for more than 60%. The particle size is extremely fine, the specific surface area is relatively large, and it has certain colloidal properties, making dehydration and utilization difficult.

[0063] (2) Chemical properties of wet alkali residue: The contents of CaCO3, CaCl2, Al2O3, etc. in the alkali residue are relatively high, accounting for 30% in the dry basis, with a high pH value and certain corrosiveness, making it difficult to reuse in industrial production.

[0064] (3) Mechanical properties of wet alkali residue: The unconfined compressive strength of the alkali residue is higher than that of the local silt, but the thixotropy is greater, and the strength drops sharply after disturbance.

[0065] Experimental steps: 253 m3 of wet alkali residue, 82 m3 of the composition dosage, and the aeration reaction time is 4.5 h.

[0066] Through experiments, it is verified that this process has the ability to adjust the pH and color of the alkali residue slurry. The pH values of the filtrate and the engineering soil both drop below 9.5, and the color of the engineering soil is similar to that of the added loess.

[0067] The main test data are as Figure 4 shown: (In this test, 253 m3 of wet alkali residue was treated and 170 tons of engineering soil was prepared). It can be seen from Figure 4 that the moisture content of the filter cake is lower than 60%, the pH value of the filter cake is lower than 9.5, the pH value of the filtrate is lower than 8.5, and the COD and total nitrogen both meet the environmental protection requirements and can meet the control requirements of the engineering soil after adjustment.

[0068] 2. Entrusted inspection situation

[0069] After the test, Lianyungang Kejian Engineering Quality Co., Ltd. was entrusted to detect the mechanical properties of the engineering soil. The test results are as Figure 5 shown. It can be seen from Figure 5 that its mechanical properties (bearing capacity, compaction coefficient, porosity, etc.) meet the index requirements of the engineering soil.

[0070] According to the calculation method of the foundation bearing capacity in the engineering code, the characteristic value of the foundation bearing capacity determined by the shear strength index of the engineering soil is:

[0071] f a =M b γb+M d γ m d+M C C k

[0072] Among them:

[0073] f a - The characteristic value of the foundation bearing capacity determined by the shear strength index of the soil (kPa);

[0074] M b 、M d 、M C - Bearing capacity coefficients;

[0075] γ - Unit weight of soil below the foundation base. Take the buoyant unit weight below the groundwater level;

[0076] γ m - Weighted average unit weight of soil above the foundation base. Take the buoyant unit weight below the groundwater level. According to the project investigation, the depth of the groundwater level is 0.6 - 15 m;

[0077] C k - Cohesion.

[0078] The characteristic value of the foundation bearing capacity of the soil for this project, f a is: 160 kPa, which is higher than the technical index of 100 kPa.

[0079] Although the above embodiments have described the present invention in detail, they are only a part of the embodiments of the present invention, not all embodiments. People can also obtain other embodiments based on these embodiments without creative efforts, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A composition for treating waste residue produced by the ammonia-soda process for producing soda ash, characterized in that: The composition comprises the following components in parts by weight: 20 parts of ferrous sulfate, 20 parts of citric acid, 10 parts of composite organic acid, 5 parts of modifier, 5 parts of catalyst and 40 parts of water; The composite organic acid is a chelating agent of citric acid, tartaric acid and water, and the mass ratio of the citric acid, tartaric acid and water is 12:8:

80.

2. The composition according to claim 1, characterized in that The modifier is ceramic powder, and the particle size is 5mm-1cm.

3. The composition according to claim 1, characterized in that The catalyst is prepared by mixing FeCl3 solution and polyferric sulfate solution in equal mass ratio; The mass percentage of the FeCl3 solution is 20-30%; The mass percentage of the polyferric sulfate solution is 30%.

4. Use of the composition according to any one of claims 1 to 3 in treating waste residue produced by the ammonia-soda process for producing soda ash.

5. A method for preparing engineering soil using waste residue produced by the ammonia-soda process for producing soda ash, characterized in that: The following steps are involved: 1) mixing the composition according to any one of claims 1 to 3 with waste residue to obtain a mixture; 2) subjecting the mixture obtained in step 1) to an aeration reaction, and after solid-liquid separation, the obtained solid is engineering soil.

6. The method according to claim 5, characterized in that The mass ratio of the volume of the composition in step 1) to the waste residue is 3-4 mL:100 g.

7. The method according to claim 5, characterized in that The volume ratio of the composition to the waste residue in step 1) is 82:

253.

8. The method according to claim 5, characterized in that The pH value of the waste residue in step 1) is 11.0-12.0, and the solid content is 20-30%.

9. The method according to claim 5, characterized in that The conditions for the aeration reaction in step 2) include: a time of 0.5 to 4.5 hours.

10. The method according to claim 5 or 9, characterized in that: The aeration reaction time is 1 h.

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