A method for preparing soil conditioner by activating phosphate tailings with residual acid during extraction.

Abstract

The invention discloses a method for preparing a soil conditioner by activating phosphate tailings with raffinate acid, which belongs to the technical field of slag recycling and saline-alkali soil improvement, and comprises the following steps: (1) removing lignin and hemicellulose from wood chips by a chemical method and pre-carbonizing them; (2) using graphene as a template, aniline, resorcinol and formaldehyde as monomers and polymerizing them on the surface of the pre-carbonized product; (3) compounding with phosphate tailings, raffinate acid and organic materials after carbonization to obtain granules; the invention activates the phosphate tailings with raffinate acid, and simultaneously prepares the soil conditioner with composite modified porous carbon and organic materials, which can effectively reduce harmful salt in the soil and improve the soil environment required for crop growth and development.

Description

Technical Field

[0001] The invention relates to the technical field of slag recycling and saline-alkali land soil improvement, and in particular to a method for preparing a soil conditioner by activating phosphate tailings with raffinate acid. Background Art

[0002] Saline-alkali land is a general term for various salinized and alkaline soils; there are about 9.5×10 8 hm 2 The total area of ​​saline-alkali soil in my country is about 36 million hm2. 2 , accounting for 4.88% of the country's available land area, and growing at an annual rate of 1%. In recent years, its area has tended to expand, and the degree of salinization has continued to intensify. Soil salinization is a bottleneck problem restricting the sustainable development of agriculture. Therefore, taking reasonable and effective measures to control or manage the occurrence of salinized soil is a key issue that needs to be solved urgently.

[0003] In order to meet the production requirements of high-concentration phosphate fertilizers and fine phosphorus chemicals, it is necessary to concentrate and purify dilute phosphoric acid to obtain P 2 O 5 Refined concentrated phosphoric acid with a mass fraction of 46%-54%. In the process of concentrated purification of dilute phosphoric acid or concentrated phosphoric acid, slag acid containing a large amount of solid phase or raffinate acid containing a large amount of metal ion impurities will inevitably be produced. According to relevant research, for every ton of wet-process phosphoric acid produced, 0.15 tons of slag acid will be produced, and the national slag acid production will reach 215,000 tons in 2022; for every ton of refined phosphoric acid produced, 1 ton of raffinate acid will be produced, and the current annual production of raffinate acid is 1-2 million tons. The direct discharge of raffinate acid will seriously affect the surrounding environment and cause waste of resources. Due to the strong acidity of slag acid and inconvenient transportation, its effective utilization is greatly limited.

[0004] Phosphate tailings are the byproducts of phosphate concentrate obtained by flotation enrichment of phosphate ore. Its main phase is white jade [Mg(CO 3 ) 2 ] and fluorapatite [Ca 5 F(PO 4 ) 3 ], its P 2 O 5 The content is 4-7%, and the MgO content is 15-19%, which is a high-magnesium low-grade phosphate ore. For a long time, the production process of domestic and foreign flotation plants has adopted the method of selecting natural damming and storage for the treatment of phosphate flotation tailings. The storage of a large number of flotation phosphate tailings not only occupies a large amount of land resources, but also brings pollution to the environment and poses huge safety hazards.

[0005] Therefore, from the perspective of resource recycling and economic utilization, it is of great practical significance to study how to use residual acid and phosphate tailings for soil improvement. Summary of the invention

[0006] In view of the above problems, the present invention provides a method for preparing a soil conditioner by activating phosphate tailings with raffinate acid.

[0007] The purpose of the present invention is achieved by the following technical solutions:

[0008] A method for preparing a soil conditioner by activating phosphate tailings with raffinate acid comprises the following steps:

[0009] (1) Soaking wood chips in a mixed solution of sodium hydroxide and sodium bisulfite, keeping warm and stirring at 70-90° C. for 1-10 hours, filtering out and washing to neutrality after the insulation is completed, vacuum drying to constant weight, and then pre-carbonizing in a flowing protective gas, washing the pre-carbonized product with deionized water, and vacuum drying to constant weight to obtain a pre-treated product;

[0010] (2) dispersing the pre-treated product and graphene in an ethanol aqueous solution, adding aniline monomer and resorcinol monomer, adding formaldehyde solution after sufficient stirring and mixing, sealing the reaction system, and stirring and reacting at 80-110° C. under autogenous pressure for 12-20 hours. After the reaction is completed, cooling, separating and washing the precipitate, drying, and then carbonizing in a flowing protective gas to obtain a carbonized product;

[0011] (3) The phosphate tailings are crushed and uniformly mixed with the raffinate and the carbonization product to react completely at room temperature, and then compounded with organic materials after drying and granulated to obtain the soil conditioner.

[0012] In some preferred embodiments, the concentration of the sodium hydroxide in the mixed solution of step (1) is 1-3 mol / L, and the concentration of the sodium sulfite is 1-2 mol / L.

[0013] In some preferred embodiments, the pre-carbonization temperature in step (1) is 200-300° C., and the pre-carbonization holding time is 4-8 h.

[0014] In some preferred embodiments, the volume ratio of ethanol to water in the ethanol aqueous solution in step (2) is (0.5-5):1, and the dispersion concentration of the graphene in the ethanol aqueous solution is 8-12 g / L.

[0015] In some preferred embodiments, the mass ratio of the pre-treatment product in step (2) to the graphene, the aniline monomer, the resorcinol monomer, and the formaldehyde in the formaldehyde solution is 10: (0.07-0.09): (1.9-2.4): (7-7.6): (3-3.5).

[0016] In some preferred embodiments, the carbonization temperature in step (2) is 800-1000° C., and the carbonization time is 1-6 h.

[0017] In some preferred embodiments, the crushed particle size of the phosphate tailings is less than 100 mesh; the phosphate tailings comprises the following composition by mass percentage: 3.5-12% phosphorus pentoxide, 30.13-32.5% calcium oxide, 16.58-19.86% magnesium oxide, 1.03-1.25% ferric oxide, and 1.93-2.22% silicon dioxide.

[0018] In some preferred embodiments, the raffinate acid is a slurry byproduct of wet production of phosphoric acid, and the pH value of the raffinate acid is 1.5-3.0; in terms of mass percentage, the raffinate acid comprises the following composition: 31.8-35.1% phosphorus pentoxide, 4.82-5.13% calcium oxide, 1.71-2.19% magnesium oxide, and 9.02-9.55% ferric oxide.

[0019] In some preferred embodiments, the mass ratio of the phosphate tailings to the raffinate acid and the carbonization product is (3-3.5):(1.5-1.8):1.

[0020] In some preferred embodiments, the organic material is one or more of crop straw, seaweed residue, manure, fungus residue, wood chips, furfural residue, and oil cake; the purpose of adding the organic material is to increase the organic matter in the soil and improve the preliminary conditions for soil improvement and planting. The organic material can not only directly increase the organic matter content, but also serve as a carrier of microorganisms. Applying it to the soil is beneficial to the growth and reproduction of microorganisms and indirectly supplements the soil organic matter.

[0021] The beneficial effects of the present invention are:

[0022] In view of the problem that there is a lack of resource recycling methods for phosphate tailings in the prior art, the present invention activates the phosphate tailings with another industrial by-product, namely, raffinate acid, and prepares a soil conditioner by composite modified porous carbon and organic materials, which can effectively reduce harmful salt in the soil and improve the soil environment required for crop growth and development; specifically, the present invention uses discarded wood chip biomass as raw material, first removes lignin and hemicellulose therein through chemical treatment, increases the pore structure of the wood raw material, and after pre-carbonization, uses graphene as a template, and uses aniline, resorcinol and formaldehyde as monomers and polymerizes on the surface of the pre-carbonized product, and after carbonization, composites it with the raffinate acid and phosphate tailings to obtain a hard carbon-type porous nano-carbon material with accessible carbonyl / hydroxyl groups. , by making use of the rapid transport of sodium ions by micropores, the rapid redox reaction and chemical adsorption process between carbonyl and hydroxyl functional groups and sodium ions on the surface are utilized to reduce the activity of sodium ions in the soil, reduce the harmful salt content in the soil, and thus improve the soil planting environment; the extracting acid and phosphate tailings can reduce the alkalinity of the soil and provide the soil with rich phosphorus content; the organic matter is used to improve the fertilizer efficiency of the soil and can be adjusted according to the actual soil composition and the needs of the crops planted; the present invention not only realizes the recycling of waste resources, but also reduces environmental pollution and the cost and land for treating waste, opens up a new way for the recycling of phosphate tailings, and has good economic benefits, environmental benefits and social benefits. DETAILED DESCRIPTION

[0023] The present invention is further described in conjunction with the following examples.

[0024] In the actual application process of the soil conditioner prepared by the present invention, some nitrogen fertilizer, potassium fertilizer and trace elements can be added during application according to the physical and chemical properties of the soil.

[0025] Example 1

[0026] A method for preparing a soil conditioner by activating phosphate tailings with raffinate acid comprises the following steps:

[0027] (1) Soaking poplar wood chips in a mixed solution of sodium hydroxide and sodium bisulfite, keeping the mixture warm at 85° C. and stirring for 6 h, filtering out the chips after the heat preservation, washing them to neutrality, vacuum drying them to constant weight, and then pre-carbonizing them in a flowing protective gas, washing the pre-carbonized products with deionized water, and vacuum drying them to constant weight to obtain a pre-treated product; the concentration of sodium hydroxide in the mixed solution is 1.5 mol / L, and the concentration of sodium sulfite is 2 mol / L; the pre-carbonization temperature is 260° C., and the pre-carbonization heat preservation time is 5 h;

[0028] (2) dispersing the pre-treatment product and graphene in an ethanol aqueous solution, adding aniline monomer and resorcinol monomer, adding formaldehyde solution after sufficient stirring and mixing, sealing the reaction system, and stirring and reacting at 100°C under autogenous pressure for 16 hours. After the reaction is completed, cooling is performed, separating the precipitate and washing, drying, and then carbonizing in a flowing protective gas to obtain a carbonized product; the volume ratio of ethanol to water in the ethanol aqueous solution is 4:1, and the dispersion concentration of the graphene in the ethanol aqueous solution is 10g / L; the mass ratio of the pre-treatment product to the graphene, the aniline monomer, the resorcinol monomer, and the formaldehyde in the formaldehyde solution is 10:0.08:2.1:7.2:3.2; the carbonization temperature is 900°C, and the carbonization time is 2h;

[0029] (3) crushing the phosphate tailings, uniformly mixing with the raffinate and the carbonization product, reacting at room temperature for 6 hours until complete, and compounding with organic materials after drying, and granulating to obtain the soil conditioner;

[0030] The crushed particle size of the phosphorus tailings is not greater than 100 meshes; the phosphorus tailings include the following components by mass percentage: 6.4% phosphorus pentoxide, 31.15% calcium oxide, 17.26% magnesium oxide, 1.14% ferric oxide, and 1.99% silicon dioxide;

[0031] The raffinate acid is a slurry byproduct of wet-process phosphoric acid production, and the pH value of the raffinate acid is 2.1; the raffinate acid comprises the following components by mass percentage: 34.6% phosphorus pentoxide, 4.94% calcium oxide, 1.97% magnesium oxide, and 9.28% ferric oxide;

[0032] The mass ratio of the phosphate tailings to the raffinate acid, the carbonization product, and the organic material is 3.3:1.6:1:0.1;

[0033] The organic material is fungus residue.

[0034] Example 2

[0035] A method for preparing a soil conditioner by activating phosphate tailings with raffinate acid comprises the following steps:

[0036] (1) Soaking poplar wood chips in deionized water, keeping the temperature at 85° C. and stirring for 6 hours, filtering out after the heat preservation, vacuum drying to constant weight, and then pre-carbonizing in a flowing protective gas, washing the pre-carbonized product with deionized water, and vacuum drying to constant weight to obtain a pre-treated product; the pre-carbonization temperature is 260° C., and the pre-carbonization heat preservation time is 5 hours;

[0037] (2) dispersing the pre-treatment product and graphene in an ethanol aqueous solution, adding aniline monomer and resorcinol monomer, adding formaldehyde solution after sufficient stirring and mixing, sealing the reaction system, and stirring and reacting at 100°C under autogenous pressure for 16 hours. After the reaction is completed, cooling is performed, separating the precipitate and washing, drying, and then carbonizing in a flowing protective gas to obtain a carbonized product; the volume ratio of ethanol to water in the ethanol aqueous solution is 4:1, and the dispersion concentration of the graphene in the ethanol aqueous solution is 10g / L; the mass ratio of the pre-treatment product to the graphene, the aniline monomer, the resorcinol monomer, and the formaldehyde in the formaldehyde solution is 10:0.08:2.1:7.2:3.2; the carbonization temperature is 900°C, and the carbonization time is 2h;

[0038] (3) crushing the phosphate tailings, uniformly mixing with the raffinate and the carbonization product, reacting completely at room temperature, and compounding with organic materials after drying, and granulating to obtain the soil conditioner;

[0039] The phosphate tailings and the raffinate acid are the same as those in Example 1;

[0040] The mass ratio of the phosphate tailings to the raffinate acid, the carbonization product, and the organic material is 3.3:1.6:1:0.1;

[0041] The organic material is the same as in Example 1.

[0042] Example 3

[0043] A method for preparing a soil conditioner by activating phosphate tailings with raffinate acid comprises the following steps:

[0044] (1) dispersing graphene in an ethanol aqueous solution, adding aniline monomer and resorcinol monomer, stirring and mixing thoroughly, adding formaldehyde solution, sealing the reaction system, and stirring and reacting at 100°C under autogenous pressure for 16 hours. After the reaction is completed, cooling, separating and washing the precipitate, drying, and then carbonizing in a flowing protective gas to obtain a carbonized product; the volume ratio of ethanol to water in the ethanol aqueous solution is 4:1, and the dispersion concentration of the graphene in the ethanol aqueous solution is 10 g / L; the mass ratio of the graphene to the aniline monomer, the resorcinol monomer, and the formaldehyde in the formaldehyde solution is 0.08:2.1:7.2:3.2; the carbonization temperature is 900°C, and the carbonization time is 2 hours;

[0045] (3) crushing the phosphate tailings, uniformly mixing with the raffinate and the carbonization product, reacting completely at room temperature, and compounding with organic materials after drying, and granulating to obtain the soil conditioner;

[0046] The phosphate tailings and the raffinate acid are the same as those in Example 1;

[0047] The mass ratio of the phosphate tailings to the raffinate acid, the carbonization product, and the organic material is 3.3:1.6:1:0.1;

[0048] The organic material is the same as in Example 1.

[0049] Example 4

[0050] A method for preparing a soil conditioner by activating phosphate tailings with raffinate acid comprises the following steps:

[0051] (1) pre-carbonizing and carbonizing poplar wood chips in a flowing protective gas in sequence to obtain a carbonized product; the pre-carbonization temperature is 260° C., the pre-carbonization heat preservation time is 5 hours; the carbonization temperature is 900° C., and the carbonization time is 2 hours;

[0052] (2) crushing the phosphate tailings, uniformly mixing with the raffinate and the carbonized product, reacting completely at room temperature, and compounding with organic materials after drying, and granulating to obtain the soil conditioner;

[0053] The phosphate tailings and the raffinate acid are the same as those in Example 1;

[0054] The mass ratio of the phosphate tailings to the raffinate acid, the carbonization product, and the organic material is 3.3:1.6:1:0.1;

[0055] The organic material is the same as in Example 1.

[0056] Example 5

[0057] A method for preparing a soil conditioner comprises the following steps:

[0058] (1) Soaking poplar wood chips in a mixed solution of sodium hydroxide and sodium bisulfite, keeping the mixture warm at 85° C. and stirring for 6 h, filtering out the chips after the heat preservation, washing them to neutrality, vacuum drying them to constant weight, and then pre-carbonizing them in a flowing protective gas, washing the pre-carbonized products with deionized water, and vacuum drying them to constant weight to obtain a pre-treated product; the concentration of sodium hydroxide in the mixed solution is 1.5 mol / L, and the concentration of sodium sulfite is 2 mol / L; the pre-carbonization temperature is 260° C., and the pre-carbonization heat preservation time is 5 h;

[0059] (2) The pre-treatment product and graphene are dispersed in an ethanol aqueous solution, aniline monomer and resorcinol monomer are added, and formaldehyde solution is added after sufficient stirring and mixing. The reaction system is sealed, and the reaction is stirred and reacted at 100°C under autogenous pressure for 16 hours. After the reaction is completed, the reaction is cooled, the precipitate is separated and washed, and then carbonized in a flowing protective gas after drying to obtain a carbonized product. The carbonized product is compounded with organic materials and granulated to obtain the soil conditioner; the volume ratio of ethanol to water in the ethanol aqueous solution is 4:1, and the dispersion concentration of the graphene in the ethanol aqueous solution is 10g / L; the mass ratio of the pre-treatment product to the graphene, the aniline monomer, the resorcinol monomer, and the formaldehyde in the formaldehyde solution is 10:0.08:2.1:7.2:3.2; the carbonization temperature is 900°C, and the carbonization time is 2h;

[0060] The mass ratio of the carbonized product to the organic material is 1:0.1;

[0061] The organic material is the same as in Example 1.

[0062] Example 6

[0063] A method for preparing a soil conditioner by activating phosphate tailings with raffinate acid comprises the following steps:

[0064] The phosphate tailings are crushed and uniformly mixed with the raffinate acid, reacted completely at room temperature, and then compounded with organic materials after drying and granulated to obtain the soil conditioner;

[0065] The phosphate tailings and the raffinate acid are the same as those in Example 1;

[0066] The mass ratio of the phosphate tailings to the raffinate acid and the organic material is 3.3:1.6:0.1;

[0067] The organic material is the same as in Example 1.

[0068] Experimental example

[0069] The soil conditioner described in Example 1-6 was applied to saline-alkali soil at an application rate of 160 kg / hm 2 , the pH value, water-soluble salt and conductivity of the soil before and after application (1 month) were measured. Specifically, the mixed soil samples were collected and naturally air-dried, and the samples were thoroughly mixed through a 0.25 mm pore size sieve before the measurement. Corn was used as the test crop to measure the effects of the saline-alkali soil conditioning on corn growth and yield before and after the conditioning. Corn was routinely applied with corn-specific water-soluble fertilizers. The measurement results are as follows:

[0070]

[0071] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a soil conditioner by activating phosphate tailings using raffinate acid, characterized in that: The following steps are involved: (1) Soaking wood chips in a mixed solution of sodium hydroxide and sodium bisulfite, keeping warm and stirring at 70-90° C. for 1-10 hours, filtering out and washing to neutrality after the insulation is completed, vacuum drying to constant weight, and then pre-carbonizing in a flowing protective gas, washing the pre-carbonized product with deionized water, and vacuum drying to constant weight to obtain a pre-treated product; (2) dispersing the pre-treated product and graphene in an ethanol aqueous solution, adding aniline monomer and resorcinol monomer, adding formaldehyde solution after sufficient stirring and mixing, sealing the reaction system, and stirring and reacting at 80-110° C. under autogenous pressure for 12-20 hours. After the reaction is completed, cooling, separating and washing the precipitate, drying, and then carbonizing in a flowing protective gas to obtain a carbonized product; The mass ratio of the pre-treatment product in step (2) to the graphene, the aniline monomer, the resorcinol monomer, and the formaldehyde in the formaldehyde solution is 10: (0.07-0.09): (1.9-2.4): (7-7.6): (3-3.5); (3) crushing the phosphate tailings, uniformly mixing with the raffinate and the carbonization product, reacting completely at room temperature, and compounding with organic materials after drying, and granulating to obtain the soil conditioner; The mass ratio of the phosphate tailings to the raffinate acid and the carbonization product is (3-3.5):(1.5-1.8):1; The raffinate acid is a slurry byproduct of wet-process phosphoric acid production, and the pH value of the raffinate acid is 1.5-3.

0. In terms of mass percentage, the raffinate acid comprises the following components: 31.8-35.1% phosphorus pentoxide, 4.82-5.13% calcium oxide, 1.71-2.19% magnesium oxide, and 9.02-9.55% ferric oxide.

2. The method for preparing a soil conditioner by activating phosphate tailings with raffinate acid according to claim 1, characterized in that: The concentration of the sodium hydroxide in the mixed solution of step (1) is 1-3 mol / L, and the concentration of the sodium bisulfite is 1-2 mol / L.

3. The method for preparing a soil conditioner by activating phosphate tailings with raffinate acid according to claim 1, characterized in that: The pre-carbonization temperature in step (1) is 200-300° C., and the pre-carbonization insulation time is 4-8 hours.

4. The method for preparing a soil conditioner by activating phosphate tailings with raffinate acid according to claim 1, characterized in that: The volume ratio of ethanol to water in the ethanol aqueous solution in step (2) is (0.5-5):1, and the dispersion concentration of the graphene in the ethanol aqueous solution is 8-12 g / L.

5. The method for preparing a soil conditioner by activating phosphate tailings with raffinate acid according to claim 1, characterized in that: The carbonization temperature in step (2) is 800-1000° C., and the carbonization time is 1-6 hours.

6. The method for preparing a soil conditioner by activating phosphate tailings with raffinate acid according to claim 1, characterized in that: The crushed particle size of the phosphorus tailings is less than 100 meshes; in terms of mass percentage, the phosphorus tailings include the following components: 3.5-12% phosphorus pentoxide, 30.13-32.5% calcium oxide, 16.58-19.86% magnesium oxide, 1.03-1.25% ferric oxide, and 1.93-2.22% silicon dioxide.

7. The method for preparing a soil conditioner by activating phosphate tailings with raffinate acid according to claim 1, characterized in that: The organic material is one or more of crop straw, seaweed residue, excrement, fungus residue, wood chips, furfural residue and oil cake.

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