Method for using composite microorganisms to improve gelling performance of iron-containing solid waste

Abstract

The present invention belongs to the technical field of iron-containing solid waste exploitation and microorganisms and specifically provides a method for using composite microorganisms to improve the gelling performance of iron-containing solid waste by. The provided method involves treating iron-containing solid waste with iron reducing bacteria, Bacillus aceticus, and Bacillus mucilaginosus. Under the combined action of the iron reducing bacteria, Bacillus aceticus, and Bacillus mucilaginosus, the dissolution of ions such as iron, calcium, and magnesium from the iron-containing solid waste can be accelerated, and the carbonization strength of the iron-containing solid waste is improved, so that the strength of the iron-containing solid waste as a gel material is significantly improved. It can be seen from the disclosure of the embodiments that by means of the provided method for improving the gelling performance of iron-containing solid waste, the demolding strength and the carbonization strength of iron-containing solid waste such as steel slag, stainless steel slag, and nickel slag are significantly higher than those in the prior art.

Description

A method for improving the gelling properties of iron-containing solid waste using composite microorganisms

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on October 27, 2023, with application number CN202311407950.1 and invention name “A method for improving the gelling properties of iron-containing solid waste using composite microorganisms”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The invention belongs to the field of iron-containing solid waste development and microbial technology, and particularly relates to a method for improving the gelling properties of iron-containing solid waste by utilizing composite microorganisms. Background Art

[0003] Steel slag is a solid residue formed during the steelmaking process, composed of slag-forming materials, smelting reactants, impurities introduced by corroded and detached furnace bodies and filler materials, and metal charge materials. It is a byproduct of steel production, generating an average of 15% to 20% of slag for every ton of steel produced. However, this large amount of slag is not being effectively utilized, occupying increasing amounts of land, polluting the environment, and wasting resources. Consequently, the treatment and resource utilization of waste slag in steel plants is receiving increasing attention.

[0004] Currently, building materials are one of the most widespread and effective ways to recycle solid waste. The main active mineral components of steel slag are C2S, C3S, C4AF, and RO phase (a solid solution formed by oxides of Mg, Fe, Mn, etc.) Fe2O3, which are similar to cement components. However, steel slag has a slow hydration rate, especially iron-containing mineral phases such as RO phase Fe2O3, which lack hydration activity. This results in slow strength development of iron-containing solid wastes such as steel slag when used as cementitious materials. Ultimately, the low gel strength severely limits the use of steel slag as a cementitious material in civil engineering.

[0005] Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a method for improving the gelling properties of iron-containing solid waste using composite microorganisms. The iron-containing solid waste is treated with a mixture of iron-reducing bacteria, Bacillus aceticus and Bacillus mucilaginosus, which can promote the dissolution of iron ions in the iron-containing solid waste, increase the carbonization strength, and significantly improve the strength of the iron-containing solid waste when used as a gel material.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides application of a microbial combination comprising iron-reducing bacteria, acetic acid Bacillus and mucilaginous Bacillus in improving the gelling performance of iron-containing solid waste.

[0009] Preferably, the microbial combination is iron-reducing bacteria, acetic acid Bacillus and mucilaginous Bacillus.

[0010] The present invention also provides a method for improving the gelling properties of iron-containing solid waste, comprising the following steps:

[0011] inoculating iron-reducing bacteria and acetic acid Bacillus into a first proliferation culture medium for a first proliferation culture to obtain a composite bacterial liquid;

[0012] inoculating the Bacillus subtilis into a second proliferation culture medium for a second proliferation culture to obtain a Bacillus subtilis bacterial liquid;

[0013] The iron-containing solid waste, the composite bacterial solution, the Bacillus subtilis bacterial solution and sand are mixed and stirred to obtain a mortar;

[0014] The obtained mortar is poured into a mold for shaping and then cured.

[0015] Preferably, the mass ratio of the iron-containing solid waste, the volume of the composite bacterial solution, the volume of the Bacillus subtilis bacterial solution and the sand is (3-6) g: (1-2) mL: (0.5-1) mL: (12-18) g.

[0016] Preferably, the iron-containing solid waste includes one or more of steel slag, stainless steel slag and nickel slag.

[0017] Preferably, the particle size of the iron-containing solid waste is less than 100 μm.

[0018] Preferably, the curing includes: curing the molded specimen at a relative humidity of 90% to 100% and a temperature of 18°C ​​to 22°C for 24 hours; after demolding, curing the demolded specimen in a CO2 atmosphere with a relative humidity of 55% to 65% and a pressure of 0.2 MPa for 2 hours.

[0019] Preferably, the bacterial concentration of the composite bacterial solution is 10 7 ~10 8 The bacterial concentration of the Bacillus subtilis liquid is 10 7 ~10 8 pieces / mL.

[0020] Preferably, the pH value of the composite bacterial solution is 3-6.

[0021] Preferably, the first proliferation culture medium uses water as a solvent and includes (NH4)2SO40.1~0.5g / L, KH2PO40.01~0.1g / L, KCl 0.01~0.1g / L, MgSO40.1~0.5g / L, Ca(NO3)20.001~0.01g / L and glucose 10~50g / L.

[0022] Preferably, the culture conditions of the first proliferation culture include: temperature 10°C to 40°C, rotation speed 50 to 200 r / min, and time 6 to 48 hours.

[0023] Preferably, the second proliferation culture medium uses water as a solvent and includes 1-20 g / L of peptone, 5-40 g / L of beef extract, and 1-10 g / L of NaCl.

[0024] Preferably, the culture conditions of the second proliferation culture include: temperature 10°C to 40°C, rotation speed 50 to 200 r / min, and time 12 to 60 h.

[0025] The present invention also provides a gel building material, which includes a mortar product obtained by the method described in the above scheme. Beneficial effects:

[0026] The present invention provides a method for improving the gelling properties of iron-containing solid waste using composite microorganisms, wherein the iron-containing solid waste is treated with iron-reducing bacteria, acetic acid Bacillus, and gelatinous Bacillus. Among them, acetic acid Bacillus can convert glucose into acetic acid, which can accelerate the dissolution rate of calcium and magnesium ions in calcium and magnesium minerals in the iron-containing solid waste. The iron-reducing bacteria can dissolve iron ions in the solid solution of iron-containing minerals without hydration activity and RO phase in ionic form, providing cations for the hydration and carbonization reactions of the gelling material. At the same time, the iron-reducing bacteria can also use acetate as a carbon source for growth metabolism, providing an internal carbon source for the mineralization reaction of gelatinous Bacillus, thereby improving the early strength of the gelling material. Gelatinous Bacillus can produce carbonic anhydrase, significantly improving the carbon dioxide hydration reaction rate, improving the carbon dioxide transmission rate in the gelling material, and then significantly improving the carbonization reaction rate. The iron-reducing bacteria, acetic acid Bacillus, and gelatinous Bacillus work together to significantly improve the strength of the iron-containing solid waste when used as a gelling material. As described in the examples, the method for improving the gelling properties of iron-containing solid waste provided by the present invention can significantly improve the demoulding strength and carbonization strength (gelling properties) of iron-containing solid waste such as steel slag, stainless steel slag and nickel slag compared to existing technical methods. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments are briefly introduced below.

[0028] FIG1 is a graph showing the change in iron ion dissolution concentration of the steel slag during the curing process as a function of curing time in Example 1, Comparative Example 1, and Comparative Example 4;

[0029] FIG2 is a comparison of 1d demoulding strength and carbonization strength of the steel slags of Example 1, Comparative Example 1 and Comparative Example 4 during the curing process;

[0030] FIG3 is a comparison of 1d demoulding strength and carbonization strength of the stainless steel slags of Example 2, Comparative Example 2 and Comparative Example 5 during the curing process;

[0031] FIG4 is a comparison diagram of the 1d demoulding strength and carbonization strength of the nickel slags of Example 3, Comparative Example 3 and Comparative Example 6 during the curing process. DETAILED DESCRIPTION

[0032] The present invention provides the use of a microbial combination comprising iron-reducing bacteria, Bacillus aceticus and Bacillus mucilaginosus in improving the gelling properties of iron-containing solid waste. The microbial composition of the present invention preferably comprises only iron-reducing bacteria, Bacillus aceticus and Bacillus mucilaginosus.

[0033] The present invention also provides a method for improving the gelling properties of iron-containing solid waste, comprising the following steps:

[0034] inoculating iron-reducing bacteria and acetic acid Bacillus into a first proliferation culture medium for a first proliferation culture to obtain a composite bacterial liquid;

[0035] inoculating the Bacillus subtilis into a second proliferation culture medium for a second proliferation culture to obtain a proliferation culture fluid containing the Bacillus subtilis;

[0036] The iron-containing solid waste, the composite bacterial solution, the Bacillus subtilis bacterial solution and sand are mixed and stirred to obtain a mortar;

[0037] The obtained mortar is poured into a mold for shaping and then cured.

[0038] The present invention inoculates iron-reducing bacteria and acetic acid Bacillus into a first proliferation culture medium for a first proliferation culture to obtain a composite bacterial liquid. The iron-reducing bacteria of the present invention is preferably decolorization Shewanella (S.decolorationis) S12, and the acetic acid Bacillus is preferably Acetobacter pasteurianus AS1.41 or Acetobacter pasteurianus CICC 20753. The inoculation volume ratio of the iron-reducing bacteria and Acetobacter pasteurianus of the present invention is preferably 1:3 to 1:5, and more preferably 1:4. The first proliferation culture medium of the present invention is preferably water as a solvent, and further preferably includes (NH4)2SO40.1~0.5g / L, KH2PO40.01~0.1g / L, KCl 0.01~0.1g / L, MgSO40.1~0.5g / L, Ca(NO3)20.001~0.01g / L and glucose 10~50g / L. The concentration of (NH4)2SO4 in the first proliferation culture medium of the present invention is further preferably 0.1-0.3 g / L, more preferably 0.15 g / L; the concentration of KH2PO4 is further preferably 0.02-0.06 g / L, more preferably 0.05 g / L; the concentration of KCl is further preferably 0.02-0.06 g / L, more preferably 0.05 g / L; the concentration of MgSO4 is further preferably 0.3-0.6 g / L, more preferably 0.5 g / L; the concentration of Ca(NO3)2 is further preferably 0.005-0.015 g / L, more preferably 0.01 g / L; the concentration of glucose is further preferably 20-40 g / L, more preferably 30 g / L.

[0039] In the present invention, before inoculating the iron-reducing bacteria and acetic acid Bacillus into the first proliferation culture medium, the first proliferation culture medium is preferably sterilized. The sterilization temperature is preferably 130° C., the time is preferably 1 hour, and the pressure is preferably 0.3 MPa.

[0040] The first proliferation culture of the present invention is preferably carried out on a shaker, and the culture temperature is preferably 10°C to 40°C, more preferably 20°C to 40°C, and more preferably 30°C; the rotation speed is preferably 50 to 200r / min, more preferably 100 to 200r / min, and more preferably 170r / min; the culture time is preferably 6 to 48h, more preferably 10 to 30h, and more preferably 24h. The pH value of the composite bacterial solution obtained by the first proliferation culture of the present invention is preferably 3 to 6, and more preferably 4. The bacterial cell concentration of the composite bacterial solution of the present invention is preferably 10 7 ~10 8 / mL, more preferably 10 7 / mL. The acetic acid Bacillus in the composite bacterial liquid of the present invention can convert glucose into acetic acid, thereby accelerating the dissolution rate of calcium and magnesium ions in calcium and magnesium minerals in iron-containing solid waste. The iron-reducing bacteria in the composite bacterial liquid of the present invention can dissolve the iron ions in the solid solution of the iron-containing minerals without hydration activity and the RO phase in the form of ions, providing cations for the hydration and carbonization reactions of the cementitious material. At the same time, the iron-reducing bacteria can also use acetate as a carbon source for growth metabolism, providing an internal carbon source for the mineralization reaction of the gelling Bacillus, and improving the early strength of the cementitious material.

[0041] At the same time, the present invention inoculates Bacillus mucilaginosus into a second proliferation culture medium for a second proliferation culture to obtain a proliferation culture solution containing Bacillus mucilaginosus. The second proliferation culture medium of the present invention preferably uses water as a solvent, and preferably includes 1 to 20 g / L of peptone, 5 to 40 g / L of beef extract, and 1 to 10 g / L of NaCl. The concentration of peptone in the second proliferation culture medium of the present invention is further preferably 7 to 15 g / L, more preferably 10 g / L; the concentration of the beef extract is further preferably 10 to 20 g / L, more preferably 15 g / L; the concentration of NaCl is further preferably 1.2 to 5 g / L, more preferably 1.5 g / L. Before the present invention inoculates the Bacillus mucilaginosus into the second proliferation culture medium, the second proliferation culture medium is preferably sterilized, and the sterilization temperature is preferably 150°C; the time is preferably 1 hour; and the pressure is preferably 0.2 MPa. The second proliferation culture of the present invention is preferably carried out in a shaker, and the culture temperature is preferably 10°C to 40°C, more preferably 20°C to 30°C, and more preferably 30°C; the rotation speed is preferably 50 to 200 r / min, more preferably 100 to 200 r / min, and more preferably 170 r / min; the culture time is preferably 12 to 60 h, more preferably 20 to 40 h, and more preferably 24 h.

[0042] The water of the present invention is preferably deionized water. The bacterial concentration of the mucilaginous Bacillus liquid of the present invention is preferably 10 7 ~10 8 / mL, more preferably 10 8 The Bacillus subtilis in the Bacillus subtilis bacterial solution of the present invention can produce carbonic anhydrase, which significantly increases the carbon dioxide hydration reaction rate, increases the carbon dioxide transmission rate in the cementitious material, and significantly increases the carbonization reaction rate.

[0043] After obtaining the composite bacterial solution and the mucilaginous Bacillus solution, the present invention mixes and stirs the iron-containing solid waste, the composite bacterial solution, the mucilaginous Bacillus solution and sand to obtain a mortar. The mass ratio of the iron-containing solid waste, the volume of the composite bacterial solution, the volume of the mucilaginous Bacillus solution and the sand in the present invention is preferably (3-6) g: (1-2) mL: (0.5-1) mL: (12-18) g, more preferably (4-6) g: (1.4-2) mL: (0.6-1) mL: (13-18) g, and more preferably 6 g: 2 mL: 1 mL: 18 g. The iron-containing solid waste in the present invention preferably includes one or more of steel slag, stainless steel slag and nickel slag, more preferably steel slag. The particle size of the iron-containing solid waste in the present invention is preferably less than 100 μm. The present invention does not specifically limit the mixing method, and a conventional mixing method in the art can be used. The present invention does not specifically limit the stirring method, and a conventional stirring method in the art can be used.

[0044] After obtaining the mortar, the present invention pours the obtained mortar into a mold to form the mortar. The specification of the mold of the present invention is preferably 40mm long x 40mm wide x 160mm high.

[0045] After the molding, the present invention preferably performs pre-demolding curing on the molded specimen; the relative humidity of the pre-demolding curing is 90% to 100%, preferably 95%; the temperature is preferably 18°C ​​to 22°C, more preferably 20°C; and the time is preferably 10 to 40 hours, more preferably 24 hours.

[0046] After the pre-demolding curing, the present invention preferably demolds the specimen and cures the demolded specimen in a CO2 atmosphere with a relative humidity of 55% to 65% and a pressure of 0.2 MPa for 2 hours. The relative humidity is further preferably 60%.

[0047] Unless otherwise specified, the raw materials and reagents described in the above technical solutions of the present invention can be conventional commercial products in the field.

[0048] The method for improving the gelling properties of iron-containing solid waste described in the present invention uses a mixture of iron-reducing bacteria, Bacillus aceticus and Bacillus mucilaginosus to treat the iron-containing solid waste, which can promote the dissolution of iron ions in the iron-containing solid waste, improve the carbonization strength, and significantly improve the strength of the iron-containing solid waste when used as a gel material. In addition, the demoulding strength and carbonization strength of iron-containing solid waste such as steel slag, stainless steel slag and nickel slag can be significantly higher than those of existing technical methods.

[0049] Based on the above advantages, the present invention further provides a gel building material, which includes a mortar product obtained by the method described in the above solution.

[0050] To further illustrate the present invention, the method for improving the gelling properties of iron-containing solid waste using composite microorganisms provided by the present invention is described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0051] Example 1

[0052] A method for improving the gelling properties of iron-containing solid waste, comprising the following steps:

[0053] 1) Shewanella decolorationis S12 and Acetobacter pasteurianus CICC 20753 were inoculated into a sterilized first proliferation medium (1 L), wherein the culture medium used water as a solvent and consisted of (NH4)2SO4 0.15 g / L, KH2PO4 0.05 g / L, KCl 0.05 g / L, MgSO4 0.5 g / L, Ca(NO3)2 0.01 g / L, and glucose 30.0 g / L; after completion of the inoculation, the first proliferation medium was placed in a shaker and cultured at a temperature of 30°C and a rotation speed of 170 r / min for 24 hours; after the pH value of the bacterial solution dropped to 3-6, a composite bacterial solution was obtained, and the bacterial cell concentration was 10 7 / mL;

[0054] 2) Bacillus mucilaginosus (purchased from the China Industrial Microbial Culture Collection Center, numbered CI CC 22523) was inoculated into a sterilized second proliferation medium (1 L), which was composed of 10 g / L peptone, 15 g / L beef extract, and 1.5 g / L NaCl in water. After inoculation, the second proliferation medium was placed in a shaker and cultured at a temperature of 30°C and a speed of 170 r / min for 24 h to obtain a bacterial solution containing Bacillus mucilaginosus, and a bacterial cell concentration of 10 8 Bacillus subtilis liquid of 1000 / mL;

[0055] 3) Mixing and stirring 450 g of steel slag fine powder (particle size less than 100 μm), 150 mL of the composite bacterial solution obtained in step 1), 75 mL of the Bacillus subtilis bacterial solution obtained in step 2), and 1350 g of sand to prepare a steel slag mortar;

[0056] 4) pouring the steel slag mortar obtained in step 3) into a mold and vibrating it into shape; after molding, curing it in an environment of 95±5% RH and 20±2°C for 24 hours; after demolding, placing the specimen in a curing box and curing it at a relative humidity of 60±5% RH and a CO2 pressure of 0.2MPa for 2 hours to obtain a composite microbial mortar product.

[0057] Example 2

[0058] A method for improving the gelling properties of iron-containing solid waste, comprising the same steps as in Example 1, except that the steel slag powder in step 3) is replaced with stainless steel slag powder.

[0059] Example 3

[0060] A method for improving the gelling properties of iron-containing solid waste, comprising the same steps as in Example 1, except that the steel slag powder in step 3) is replaced with nickel slag powder.

[0061] Comparative Example 1

[0062] A method for improving the gelling properties of iron-containing solid waste, comprising the following steps as in the prior art CN105481469A example, wherein a single bacillus colloid is used to prepare an iron-containing solid waste building material product, except that the raw material used is the steel slag powder in Example 1.

[0063] Comparative Example 2

[0064] A method for improving the gelling properties of iron-containing solid waste, comprising the following steps: preparing iron-containing solid waste building materials using a single bacillus colloidus as in the prior art CN105481469A, except that the raw material used is the stainless steel slag powder in Example 2.

[0065] Comparative Example 3

[0066] A method for improving the gelling properties of iron-containing solid waste, comprising the following steps as in the prior art CN105481469A example, wherein a single bacillus colloid is used to prepare an iron-containing solid waste building material product, except that the raw material used is the nickel slag powder in Example 3.

[0067] Comparative Example 4

[0068] A method for improving the gelling properties of iron-containing solid waste, comprising the following steps: preparing a composite microbial building material product by compounding acid-producing microorganisms (acetic acid bacteria) and mineralizing microorganisms (colloidal Bacillus) as in Example 1 of the prior art CN111775270A, except that the raw material used is the steel slag powder in Example 1.

[0069] Comparative Example 5

[0070] A method for improving the gelling properties of iron-containing solid waste, comprising the following steps: preparing a composite microbial building material product by compounding acid-producing microorganisms (acetic acid bacteria) and mineralizing microorganisms (colloidal Bacillus) as in Example 1 of the prior art CN111775270A, except that the raw material is the stainless steel slag powder in Example 2.

[0071] Comparative Example 6

[0072] A method for improving the gelling properties of iron-containing solid waste, comprising the following steps: preparing a composite microbial building material product by compounding acid-producing microorganisms (acetic acid bacteria) and mineralizing microorganisms (colloidal Bacillus) as in Example 1 of the prior art CN111775270A, except that the raw material used is the nickel slag powder in Example 3.

[0073] The iron ion dissolution concentration, demoulding strength and carbonization strength of the composite microbial mortar or cement products obtained in Examples 1 to 3 and Comparative Examples 1 to 6 were measured using ICP and a universal testing machine, respectively. The results are shown in Tables 1 to 4 and Figures 1 to 4. Figure 1 compares the iron ion dissolution concentration of the steel slag powder in Example 1 with the iron ion dissolution concentration of the solid waste in Comparative Examples 1 and 4; Figure 2 compares the demoulding strength and carbonization strength of the composite microbial mortar product obtained in Example 1 with the demoulding strength and carbonization strength of the building materials obtained in Comparative Examples 1 and 4; Figure 3 compares the demoulding strength and carbonization strength of the composite microbial mortar product obtained in Example 2 with the demoulding strength and carbonization strength of the building materials obtained in Comparative Examples 2 and 5; and Figure 4 compares the demoulding strength and carbonization strength of the composite microbial mortar product obtained in Example 3 with the demoulding strength and carbonization strength of the building materials obtained in Comparative Examples 3 and 6.

[0074] Table 1 Iron ion dissolution concentration in steel slag powder of Example 1 and iron ion dissolution concentration in solid waste of Comparative Example 1 and Comparative Example 4

[0075] Table 2 Comparison of 1d demoulding strength and carbonization strength of steel slag powder of Example 1 and solid waste of Comparative Examples 1-2

[0076] Table 3 Comparison of 1d demoulding strength and carbonization strength of stainless steel slag powder of Example 2 and solid waste of Comparative Examples 1-2

[0077] Table 4 Comparison of 1d demoulding strength and carbonization strength of nickel slag powder of Example 3 and solid waste of Comparative Examples 1-2

[0078] As can be seen from Table 1 and Figure 1, the iron ion dissolution rate and concentration of the steel slag powder of Example 1 under the mixed treatment of iron-reducing bacteria, Bacillus aceticus and Bacillus mucilaginosus are significantly higher than the iron ion dissolution rate and concentration in the steel slag in the methods of Comparative Examples 1 and 4.

[0079] As can be seen from Tables 2 to 4 and Figures 2 to 4, Examples 1 to 3 use a mixture of iron-reducing bacteria, Bacillus aceticus, and Bacillus mucilaginosus to treat steel slag, stainless steel slag, and nickel slag. Compared with the methods of Comparative Examples 1 to 6, the carbonization rate of the above-mentioned iron-containing solid waste during the curing process is significantly improved, and the demolding strength is more than doubled.

[0080] From the above examples, it can be seen that the method provided by the present invention, which uses a mixture of iron-reducing bacteria, Bacillus aceticus and Bacillus mucilaginosus to treat iron-containing solid waste, can promote the dissolution of iron ions in the iron-containing solid waste, improve the carbonization strength and demolding strength, and significantly improve the strength of the iron-containing solid waste when used as a gel material. In addition, the carbonization strength and demolding strength of iron-containing solid waste such as steel slag, stainless steel slag and nickel slag can be significantly higher than those of existing technical methods.

[0081] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. Application of a microbial combination in improving the gelling properties of iron-containing solid waste, the microbial combination comprising iron-reducing bacteria, acetic acid Bacillus and gelatinous Bacillus.

2. The use according to claim 1, characterized in that: The microbial combination consists of iron-reducing bacteria, acetic acid bacillus and mucilaginous bacillus.

3. A method for improving the gelling properties of iron-containing solid waste, characterized in that: The following steps are involved: Inoculating iron-reducing bacteria and Bacillus aceticus into a first proliferation culture medium for first proliferation culture to obtain a composite bacterial liquid; inoculating the Bacillus subtilis into a second proliferation culture medium for second proliferation culture to obtain a Bacillus subtilis bacterial liquid; The iron-containing solid waste, the composite bacterial solution, the Bacillus subtilis bacterial solution and sand are mixed and stirred to obtain mortar; The obtained mortar is poured into a mold for shaping and then cured.

4. The method according to claim 3, characterized in that The mass ratio of the iron-containing solid waste, the volume of the composite bacterial solution, the volume of the mucilaginous bacillus bacterial solution and the sand is (3-6) g: (1-2) mL: (0.5-1) mL: (12-18) g.

5. The method according to claim 3 or 4, characterized in that: The iron-containing solid waste includes one or more of steel slag, stainless steel slag and nickel slag.

6. The method according to claim 5, characterized in that The particle size of the iron-containing solid waste is less than 100 μm.

7. The method according to claim 3, characterized in that The curing comprises: curing the molded specimen at a relative humidity of 90% to 100% and a temperature of 18° C. to 22° C. for 24 hours; after demolding, curing the demolded specimen in a CO2 atmosphere with a relative humidity of 55% to 65% and a pressure of 0.2 MPa for 2 hours.

8. The method according to claim 3 or 4, characterized in that: The bacterial concentration of the composite bacterial solution is 10 7 ~10 8 The bacterial concentration of the Bacillus colloids liquid is 10 7 ~10 8 Pieces / mL.

9. The method according to claim 3, characterized in that: The pH value of the composite bacterial liquid is 3-6.

10. The method according to claim 3, characterized in that The first proliferation culture medium uses water as solvent, and includes (NH4)2SO4 0.1-0.5 g / L, KH2PO4 0.01-0.1 g / L, KCl 0.01-0.1 g / L, MgSO4 0.1-0.5 g / L, Ca(NO3)2 0.001-0.01 g / L and glucose 10-50 g / L.

11. The method according to claim 3 or 10, characterized in that: The culture conditions of the first proliferation culture include: temperature 10°C to 40°C, rotation speed 50 to 200 r / min, and time 6 to 48 hours.

12. The method according to claim 3, characterized in that The second proliferation culture medium uses water as a solvent and includes 1-20 g / L of peptone, 5-40 g / L of beef extract and 1-10 g / L of NaCl.

13. The method according to claim 3 or 12, characterized in that: The culture conditions of the second proliferation culture include: temperature 10°C to 40°C, rotation speed 50 to 200 r / min, and time 12 to 60 hours.

14. A gel building material, characterized in that: The gel building material comprises a mortar product obtained by the method according to any one of claims 3 to 13.

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