Soft foundation material prepared by solidifying sludge and preparation method thereof
Technical Field
The invention relates to the field of road materials, in particular to a soft foundation material prepared by solidifying sludge and a preparation method thereof.
Background
In order to improve the water quality of rivers and lakes and ensure the normal flood discharge capacity of rivers and the smoothness of navigation channels and ports, large-scale dredging and desilting projects are carried out in all countries including China, and the problem of sludge dredging with huge quantity generated along with the large-scale dredging becomes a reality which is difficult to avoid. And aiming at the problems of environmental pollution, land waste and the like caused by conventional technical means such as stacking, abandoning and the like of sludge treatment, for example, the sludge is cured by adopting a proper method or material and is used for road paving, so that multiple environmental and social benefits can be generated. In the prior art, lime, cement and other materials are mostly adopted for solidifying sludge, the solidifying effect of the solidifying agent depends on the granularity and the water content of soil, the precipitation effect is poor, the solidified sludge mostly shows the defects of low strength, poor permeability and the like, and the using effect of the solidified sludge in engineering application is unsatisfactory, so that the defect of the prior art in order to solve the problem of the novel environment-friendly and harmless sludge solidifying agent is urgently needed to be developed.
Most of the existing sludge solidification methods are mainly cement and quicklime, wherein the cement is used for increasing the tackiness of the sludge, so that the sludge is bonded together and is hardened, and the quicklime is mainly used for absorbing water, for example, Chinese patent No. CN201210012249.5 discloses a sludge curing agent and a sludge solidification method using the sludge curing agent, which relate to the field of sludge treatment, and the sludge curing agent is prepared according to the following method: the method firstly mixes seven components including expandable graphite, cement, fly ash, carbon black, silica powder, china clay and quick lime, and the method also has the problems of long curing time, incapability of removing special odor of sludge and the like.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the soft foundation material prepared by curing the sludge and the preparation method thereof, the sludge curing agent has good curing effect, short curing time and high efficiency, and the cured sludge is used as a protective filler for a road subgrade or a side slope, so that the road construction cost is reduced, and the environment is protected.
The technical scheme provided by the invention is as follows: a soft foundation material prepared by solidifying sludge is prepared by preparing 70-80 parts of sludge, 5-10 parts of sludge solidifying agent, 1-3 parts of aluminum silicate, 2-5 parts of coal gangue, 0-3 parts of slag powder, 1-5 parts of modified phosphogypsum and 2-6 parts of red mud by the following raw materials in parts by weight;
the sludge curing agent is prepared from the following raw materials in percentage by weight: 25-45% of modified diatomite, 20-40% of attapulgite, 8-15% of magnesium oxide, 3-4% of calcium chloride, 1-3% of potassium permanganate, 6-14% of peroxide, 1-3% of cationic chelate, 1-2% of sodium hypochlorite, 0-1% of isothiazolinone, 0.1-0.5% of sodium lauryl sulfate, 0.5-2% of polyoxyethylene-polyoxypropylene copolymer, 0-5% of chitosan, 1-5% of triethanolamine and 2-3% of melamine formaldehyde resin.
A soft foundation material prepared by solidifying sludge is prepared from the following raw materials in parts by weight: 72-78 parts of sludge, 6-9 parts of a sludge curing agent, 1-3 parts of aluminum silicate, 3-4 parts of coal gangue, 1-2 parts of slag powder, 2-4 parts of modified phosphogypsum and 3-5 parts of red mud.
Further, the modified phosphogypsum is obtained by aging the phosphogypsum for more than 5 days to obtain a material A; calcining the material A at the temperature of 200-250 ℃ for 1-3 hours to obtain a material B, and naturally cooling the material B; uniformly mixing the material A and the material B according to the weight percentage of 90-95 percent to 5-12 percent, wherein the particle size of the material A and the material B is 200-mesh powder of 300 meshes; the red mud is powder with the water content of 22-27% and the particle size of 200-300 meshes.
Further, the preparation method of the modified diatomite comprises the following steps: roasting diatomite, cooling, adding into ferric chloride solution, stirring at constant temperature, soaking for 5-15min, concentrating under reduced pressure, drying, and adding Na2CO3And (3) heating the solution for 20-30min by microwave, removing the upper solution, carrying out vacuum filtration, washing to be neutral, carrying out solid-liquid separation, drying and crushing to obtain the modified diatomite.
Further, the peroxide is one or more of sodium peroxide, potassium peroxide, calcium peroxide, magnesium peroxide, zinc peroxide, potassium hydrogen peroxymonosulfate and strontium peroxide.
Furthermore, the cation chelate is formed by chelating a chelating agent and metal ions, wherein the chelating agent is one or a combination of more of Ethylene Diamine Tetraacetic Acid (EDTA), nitrilotriacetic acid (NTA), Tartaric Acid (TA) and Dihydroxyethylglycine (DEG), and the metal ions are magnesium ions, calcium ions or iron ions.
Further, the water content of the sludge is 60-75%.
A method for preparing soft foundation material by solidifying sludge comprises the following steps:
(1) selecting red mud produced by Bayer process or sintering process, adjusting the water content to 22-27%, and grinding or pulverizing into powder with particle size of 200-300 meshes;
(2) aging the phosphogypsum for more than 5 days to obtain a material A; calcining the material A at the temperature of 200-250 ℃ for 1-3 hours to obtain a material B, and naturally cooling the material B; uniformly mixing the material A and the material B according to the weight percentage of 90-95 percent to 5-12 percent, and obtaining the modified phosphogypsum with the particle size of 200-300 meshes;
(3) preparing a sludge curing agent according to the following substances in percentage by weight: 25-45% of modified diatomite, 20-40% of attapulgite, 8-15% of magnesium oxide, 3-4% of calcium chloride, 1-3% of potassium permanganate, 6-14% of peroxide, 1-3% of cationic chelate, 1-2% of sodium hypochlorite, 0-1% of isothiazolinone, 0.1-0.5% of sodium lauryl sulfate, 0.5-2% of polyoxyethylene-polyoxypropylene copolymer, 0-5% of chitosan, 1-5% of triethanolamine and 2-3% of melamine formaldehyde resin.
(4) Taking 70-80 parts by weight of sludge and 5-10 parts by weight of sludge curing agent obtained in the step (3), fully mixing, naturally airing and curing for 0.5-1h, then adding 1-3 parts of aluminum silicate, 2-5 parts of coal gangue, 0-3 parts of slag powder, 1-5 parts of modified phosphogypsum obtained in the step (2) and 2-6 parts of red mud obtained in the step (1), uniformly stirring to prepare a mixed dry powder, and compacting to obtain the soft foundation material.
The invention has the beneficial effects that:
(1) the sludge curing agent adopts the modified diatomite with a porous structure, removes the moisture in the sludge through physical adsorption, and meanwhile, the moisture can slowly extend into pores to perform chemical reaction with some parasite substances in the pores to further absorb the moisture, so that the structure forms a mode of simultaneous existence of physical water absorption and chemical water absorption. Modified diatomaceous earth contains Al2O3、Fe2O3、CaO、MgO、K2O、Na2O、P2O5When oxides and organic matters are used, in the physical water absorption process, water in the sludge is distributed and expanded into the inner pores of the modified diatomite along the surface of the modified diatomite, the oxides react with the water to completely combine water molecules, and the solidification effect is achieved;
(2) the invention adopts the attapulgite as one of the main raw materials of the silt curing agent, the attapulgite has unique layer chain structure characteristics, has strong water absorption, unique dispersion, high temperature resistance, good colloid properties of saline-alkali resistance and the like, higher adsorption decoloring capacity and certain plasticity and cohesive force, can effectively remove substances such as hormone, pesticide, virus, toxin, heavy metal ions and the like, and prevents harmful substances from remaining in the silt to cause harm to people;
(3) the invention adopts strong oxidants such as potassium permanganate and peroxide as main raw materials of the sludge curing agent, can perform oxidation reaction with water to remove water in the sludge, simultaneously generates alkaline hydroxide, adjusts the acid environment of the sludge and improves the characteristics of the sludge; the magnesium oxide and other metal oxides are used as main raw materials of the curing agent, so that moisture in the sludge can be effectively captured through various oxidation reactions, the moisture content of the sludge is reduced, and the functional characteristics of short curing time and high efficiency are realized;
(4) according to the invention, chitosan is used as a main raw material of the curing agent, so that heavy metals can be effectively adsorbed, microbial structures can be destroyed, organic pollutants can be hydrolyzed, the pollution is reduced, simultaneously, the odor can be eliminated, and the application of products obtained by subsequent storage or landfill and curing of sludge is facilitated;
(5) the invention adopts sodium hypochlorite and isothiazolinone as the sterilizing disinfectant, can sterilize and disinfect the sludge, kill a large number of microorganisms in the sludge, prevent the microorganisms from further fermenting to generate malodorous gas, and also has the effect of a deodorizer.
(6) The cation chelate is used for removing toxic heavy metal ions, and meanwhile, a water reducing agent and an exciting agent are added to excite the oxide in the soil to react and absorb water.
(7) Compared with the traditional curing agent, the sludge curing agent adopted by the invention has the advantages of simple and easily-obtained raw materials, low price, simple curing process, short curing time, high efficiency, convenient transportation and low treatment cost, the cured sludge does not cause secondary pollution, the traditional curing time is 8-24h, and the sludge curing agent can be used for quickly carrying out subsequent treatment after the sludge is cured, thereby saving the working procedure time.
(8) The solidified sludge is matched with aluminum silicate, coal gangue, slag powder, modified phosphogypsum and red mud to prepare a novel foundation material, and the aluminum silicate is used as a cementing material filler, so that the hardness, wear resistance, weather resistance and storage stability of the sludge can be improved, the solidified sludge has stronger early-stage compression and bending strength, and the mechanical operation during landfill is facilitated.
(9) The soft foundation material prepared by the invention is used for road bed or slope protection filler, reduces the road construction cost and is more beneficial to environmental protection.
Drawings
FIG. 1 is a graph showing the change of water content of sludge with curing time after the sludge curing agent of the present invention is used;
in the figure: the abscissa is the curing time, unit: min, ordinate is water content, unit: % of the total weight of the composition.
Detailed Description
The present invention will be further described with reference to the following specific examples.
Example 1
A method for preparing soft foundation material by solidifying sludge comprises the following steps:
(1) selecting red mud produced by Bayer process or sintering process, adjusting the water content to 22%, and grinding or pulverizing into powder with particle size of 200-300 meshes;
(2) aging the phosphogypsum for 5d to obtain a material A; calcining the material A at 250 ℃ for 1 hour to obtain a material B, and naturally cooling the material B; uniformly mixing the material A and the material B according to the weight percentage of 90 to 10 percent, and obtaining the modified phosphogypsum with the particle size of 200-mesh and 300-mesh powder;
(3) preparing a sludge curing agent according to the following substances in percentage by weight: 26% of modified diatomite, 38% of attapulgite, 14% of magnesium oxide, 3% of calcium chloride, 1% of potassium permanganate, 7% of sodium peroxide, 1% of cationic chelate, 2% of sodium hypochlorite, 0.5% of sodium lauryl sulfate, 2% of polyoxyethylene-polyoxypropylene copolymer, 1.5% of chitosan, 1% of triethanolamine and 3% of melamine formaldehyde resin. The cation chelate is formed by chelating Ethylene Diamine Tetraacetic Acid (EDTA) and magnesium ions.
(4) And (3) taking 78 parts of sludge, 6 parts of sludge curing agent obtained in the step (3) according to the parts by weight, fully mixing, naturally airing and curing for 1h, then adding 3 parts of aluminum silicate, 3 parts of coal gangue, 3 parts of slag powder, 5 parts of modified phosphogypsum obtained in the step (2) and 2 parts of red mud obtained in the step (1), uniformly stirring to prepare a mixed dry powder material, and compacting to obtain the soft foundation material.
Example 2
A method for preparing soft foundation material by solidifying sludge comprises the following steps:
(1) selecting red mud produced by Bayer process or sintering process, adjusting the water content to 24%, and grinding or pulverizing into powder with particle size of 200-300 meshes;
(2) aging the phosphogypsum for more than 7 days to obtain a material A; calcining the material A at 230 ℃ for 2.5 hours to obtain a material B, and naturally cooling the material B; uniformly mixing the material A and the material B according to the weight percentage of 92% to 8%, and obtaining the modified phosphogypsum with the particle size of 200-mesh and 300-mesh powder;
(3) preparing a sludge curing agent according to the following substances in percentage by weight: 30% of modified diatomite, 30% of attapulgite, 10% of magnesium oxide, 4% of calcium chloride, 3% of potassium permanganate, 10% of calcium peroxide, 2% of strontium peroxide, 2% of cationic chelate, 1% of sodium hypochlorite, 0.5% of isothiazolinone, 0.4% of sodium lauryl sulfate, 1.1% of polyoxyethylene-polyoxypropylene copolymer, 2% of chitosan, 2% of triethanolamine and 2% of melamine formaldehyde resin. The cation chelate is formed by chelating dihydroxyethyl glycine (DEG) and calcium ions.
(4) And (3) taking 75 parts of sludge and 8 parts of sludge curing agent obtained in the step (3) according to the parts by weight, fully mixing, naturally airing and curing for 0.7h, then adding 2 parts of aluminum silicate, 4 parts of coal gangue, 2 parts of slag powder, 4 parts of modified phosphogypsum obtained in the step (2) and 5 parts of red mud obtained in the step (1), uniformly stirring to prepare a mixed dry powder, and compacting to obtain the soft foundation material.
Example 3
A method for preparing soft foundation material by solidifying sludge comprises the following steps:
(1) selecting red mud produced by Bayer process or sintering process, adjusting the water content to 25%, and grinding or pulverizing into powder with particle size of 200-300 meshes;
(2) aging the phosphogypsum for more than 8 days to obtain a material A; calcining the material A at 210 ℃ for 2 hours to obtain a material B, and then naturally cooling the material B; uniformly mixing the material A and the material B according to the weight percentage of 93 percent to 7 percent to obtain powder with the particle size of 200-mesh and 300-mesh, thus obtaining the modified phosphogypsum;
(3) preparing a sludge curing agent according to the following substances in percentage by weight: 35% of modified diatomite, 25% of attapulgite, 15% of magnesium oxide, 4% of calcium chloride, 1% of potassium permanganate, 6% of magnesium peroxide, 6% of zinc peroxide, 1% of cationic chelate, 1% of sodium hypochlorite, 0.2% of isothiazolinone, 0.1% of sodium lauryl sulfate, 0.5% of polyoxyethylene-polyoxypropylene copolymer, 1.7% of chitosan, 1% of triethanolamine and 2.5% of melamine formaldehyde resin. The cation chelate is formed by chelating Tartaric Acid (TA) and calcium ions.
(4) And (3) taking 72 parts of sludge and 6 parts of sludge curing agent obtained in the step (3) according to the parts by weight, fully mixing, naturally airing and curing for 0.6h, then adding 3 parts of aluminum silicate, 5 parts of coal gangue, 3 parts of slag powder, 5 parts of modified phosphogypsum obtained in the step (2) and 6 parts of red mud obtained in the step (1), uniformly stirring to prepare a mixed dry powder, and compacting to obtain the soft foundation material.
Example 4
A method for preparing soft foundation material by solidifying sludge comprises the following steps:
(1) selecting red mud produced by Bayer process or sintering process, adjusting the water content to 27%, and grinding or pulverizing to powder with particle size of 200-300 meshes;
(2) aging the phosphogypsum for more than 10 days to obtain a material A; calcining the material A at 200 ℃ for 1 hour to obtain a material B, and then naturally cooling the material B; uniformly mixing the material A and the material B according to the weight percentage of 95 percent to 5 percent, and obtaining the modified phosphogypsum with the particle size of 200-mesh and 300-mesh powder;
(3) preparing a sludge curing agent according to the following substances in percentage by weight: 40% of modified diatomite, 20% of attapulgite, 8% of magnesium oxide, 3% of calcium chloride, 3% of potassium permanganate, 5% of potassium peroxide, 2% of zinc peroxide, 3% of cationic chelate, 2% of sodium hypochlorite, 1% of isothiazolinone, 0.3% of sodium lauryl sulfate, 1.7% of polyoxyethylene-polyoxypropylene copolymer, 4% of chitosan, 4% of triethanolamine and 3% of melamine formaldehyde resin. The cation chelate is formed by chelating ethylenediaminetetraacetic acid (EDTA), Tartaric Acid (TA) and calcium ions.
(4) And (3) taking 70 parts of sludge and 10 parts of sludge curing agent obtained in the step (3) according to the parts by weight, fully mixing, naturally airing and curing for 0.5h, then adding 2 parts of aluminum silicate, 4 parts of coal gangue, 3 parts of slag powder, 5 parts of modified phosphogypsum obtained in the step (2) and 6 parts of red mud obtained in the step (1), uniformly stirring to prepare a mixed dry powder, and compacting to obtain the soft foundation material.
The following table shows the test results of curing of the above examples 1 to 4, and the existing sludge curing agent mainly composed of cement and quicklime is used as a comparative example.
TABLE 1 sludge curing agent test results
The traditional sludge curing agent needs longer curing time, and the degree of reduction of the water content of the cured sludge is smaller than that of the traditional sludge curing agent, and the compressive strength is also poorer. The invention has the characteristics of short curing time and high efficiency, and the cured sludge has less odor.
The soft foundation material prepared from the sludge treated by the sludge curing agent achieves the test of the compression resistance of the roadbed material.
The invention also makes a relevant test aiming at the curing time of the sludge, and under the condition of the same other conditions, the change of the water content of the sludge after different curing times is measured, as shown in figure 1, the result shows that the water content of the sludge is obviously reduced when the curing agent is added, and the reduction rate is very slow after 60 minutes, the invention selects the better curing time of 30-60min, and under the condition, the curing effect is achieved.
The above description is only a detailed description of specific embodiments of the present invention, and should not be taken as limiting the invention, and any modifications, equivalents, improvements, etc. made on the design concept of the present invention should be included in the protection scope of the present invention.