CN109650808B

CN109650808B - Composite curing agent based on biomass and sludge mixed burning ash and application thereof

Info

Publication number: CN109650808B
Application number: CN201811618798.0A
Authority: CN
Inventors: 侯浩波; 陈宇驰; 王腾; 石靖雯; 曾越; 李嘉豪
Original assignee: Zhaoqing City Jiawang Environmental Technology Research Institute
Current assignee: Zhaoqing City Jiawang Environmental Technology Research Institute
Priority date: 2018-12-28
Filing date: 2018-12-28
Publication date: 2022-04-01
Anticipated expiration: 2038-12-28
Also published as: CN109650808A

Abstract

The invention discloses a composite curing agent based on biomass/sludge co-fired ash and application thereof. The curing agent has good curing and stabilizing effects on solid wastes such as sludge, bottom mud and fly ash which are rich in heavy metals, can effectively prevent secondary pollution of the heavy metals to the environment, and has wide sources and low cost by using biomass ash, sludge incineration ash and the like as main raw materials, thereby achieving the purpose of treating wastes with wastes.

Description

Composite curing agent based on biomass and sludge mixed burning ash and application thereof

Technical Field

The invention relates to a heavy metal sludge curing agent, in particular to a curing agent which takes biomass raw material and sludge raw material mixed burning ash as main raw materials and application of the curing agent in curing and stabilizing treatment of heavy metal solid waste, belonging to the technical field of heavy metal treatment.

Background

Sludge is a by-product produced in municipal wastewater treatment and sewage treatment processes. With the increase of the treatment amount of urban sewage, the production amount of sludge is increased gradually. These sludges contain a large amount of harmful substances, such as parasitic ova, pathogenic microorganisms, bacteria, viruses, synthetic organic matter, heavy metal ions, and the like. The sludge is easy to deteriorate, can pollute soil and underground water, and can also pollute surface water bodies such as rivers, lakes, oceans and the like.

Toxic organic matters and heavy metals in the sludge can migrate and be enriched in a food chain in an ecosystem, and cause long-term potential harm to the ecological environment and human health. Therefore, the sludge with huge yield and complex components is reduced, stabilized, harmless and recycled after being scientifically treated.

At present, municipal sludge in China is treated mainly by landfill, composting, incineration, throwing into the sea and the like, wherein the incineration can reduce the sludge to the maximum extent and fully recycle the heat energy of the sludge, so the municipal sludge is developed rapidly in recent years. The urban sludge contains a large amount of organic matters and a certain amount of cellulose and lignin, and the incineration utilizes the characteristics of higher organic components and heat value in the sludge. At high temperature, combustible components in the sludge and oxygen in the air undergo violent chemical reaction, organic matters in the sludge are converted into harmless substances such as water, carbon dioxide and the like, and simultaneously, energy is released to generate solid residues. If the heat is recycled, the purpose of comprehensive utilization of waste can be achieved. Meanwhile, incineration treatment also has the characteristics of high organic matter removal rate, wide adaptability and the like, so the method is widely applied in developed countries.

The sludge can be converted into stable sludge ash after incineration, which accounts for more than 50% of the dry weight of the sludge, and the sludge incineration ash with large amount not only occupies the land space, but also generates fly ash which is harmful to the human health. Most of organic matters of the sludge incineration ash are toxic substances resistant to thermochemical degradation, and various harmful substances are attached to the particle surfaces of the ash after combustion, wherein the most typical substances are heavy metals in various forms.

The biomass energy is important renewable energy and has the characteristics of greenness, low carbon, cleanness, renewability and the like. The method for accelerating the development and utilization of biomass energy is an important content for promoting energy production and consumption revolution, and is an important task for improving environmental quality and developing circular economy. China has rich biomass resources and great energy utilization potential. The total amount of biomass resources such as crop straws and agricultural product processing residues, forestry residues, energy crops, household garbage, organic wastes and the like which can be used as energy resources nationwide is about 4.6 hundred million tons of standard coal every year. The biomass power generation has obvious effect on the emission reduction of carbon dioxide and various atmospheric pollutants. At present, power plants taking biomass as fuel in China develop rapidly, and the trend of biomass ash is urgent to solve.

Disclosure of Invention

In view of the defects in the prior art, the first object of the present invention is to provide a curing agent with good curing and stabilizing effects on solid wastes such as sludge, bottom mud and fly ash rich in heavy metals, which has good curing and stabilizing effects on the solid wastes to effectively prevent secondary pollution of heavy metals to the environment, and uses biomass ash and sludge incineration ash as main raw materials, which have wide sources and low cost, so as to achieve the purpose of treating wastes with wastes.

The second purpose of the invention is to provide the application of the composite curing agent based on the biomass/sludge co-combustion ash slag, the composite curing agent is used for curing solid wastes such as sludge, bottom mud and fly ash which are rich in heavy metals, the leaching value of the heavy metals of the cured body reaches the ground water four-level standard (GB/T14848-93), and the curing agent has low cost and is beneficial to popularization and use.

In order to achieve the technical purpose, the invention provides a composite curing agent based on biomass/sludge co-combustion ash, which comprises the following components in parts by mass: 18-25 parts of biomass sludge mixed burning ash; 12-15 parts of cement; 45-56 parts of emulsified asphalt; 0.5-1.5 parts of gypsum and 0.1-0.5 part of water reducing agent.

The composite curing agent provided by the invention utilizes biomass sludge mixed burning ash as a main strength providing material, cement as a bonding raw material of each component, emulsified asphalt is mainly prepared to increase compactness, and gypsum and a water reducing agent are used as corresponding auxiliary agents. The biomass sludge co-fired ash, the emulsified asphalt and the cement have obvious synergistic effect on the curing effect, and are beneficial to enhancing the curing and stabilizing effect on heavy metal solid wastes and reducing the leaching capacity of heavy metal ions. Minerals such as high potassium, silicon, phosphorus and the like in the biomass ash in the mixed-burned ash promote the initial hydration of cement gelled substances, the initial setting time is shortened, and the long-term strength increase of a solidified body can be promoted by sludge ash active substances; the emulsified asphalt and the portland cement system serve as a dual guarantee for curing the heavy metal ions, and chemical bonds of the crystallized heavy metal ions are prevented from being broken again.

In a preferred scheme, the biomass sludge mixed burning ash consists of biomass ash and sludge ash.

According to the preferable scheme, the mass ratio of biomass ash to sludge ash in the biomass sludge mixed combustion ash is 2: 1-3.

In a preferred scheme, the biomass sludge mixed burning ash is obtained by burning a mixture of biomass and sludge at the temperature of 800-850 ℃. The ash obtained by burning is simply ball-milled and crushed, and then is sieved by 0.075mm, and the sieved powder is taken out. The biomass ash mainly contains a large amount of minerals such as potassium, phosphorus and silicon, and can be used for initial hydration of cement. Domestic sludge, printing and dyeing sludge, oil sludge and the like are sludge rich in organic matters, most of the organic matters are used as heat energy to be utilized after incineration, most of the residual organic matters are toxic substances resistant to thermochemical degradation, and various harmful substances are attached to the particle surfaces of ash residues after combustion, wherein the most typical substances are heavy metals in various forms. The technical scheme of the invention utilizes the sludge ash as the solidification raw material, not only utilizes the active ingredients of the sludge ash to enhance the solidification effect, but also ensures that heavy metals and the like contained in the sludge ash are solidified and stabilized. Ash slag obtained after sludge incineration is simply ball-milled and crushed, and then is sieved by 0.075mm, and sieved powder is taken out.

In a more preferable scheme, the biomass comprises at least one of rice hulls, straws and wood chips.

In a more preferable embodiment, the sludge ash includes at least one of domestic sludge, printing sludge, and oil sludge.

Preferably, the cement is P.O 42.5-grade ordinary portland cement which is a conventional commercial product.

In a preferred scheme, the emulsified asphalt is cationic emulsified asphalt PC-2 which is a conventional commercially available product.

Preferably, the gypsum comprises at least one of desulfurized gypsum, fluorgypsum and phosphogypsum.

In a preferred scheme, the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent which is a conventional commercially available product.

Preferably, the composite curing agent comprises 20-25 parts of standard sand. The strength of the solidified body can be improved by introducing standard sand, and the solidified body is favorable for being used as building, garden roadbed, backfill material and the like.

The invention also provides application of the composite curing agent based on the biomass/sludge co-fired ash, and the composite curing agent is applied to curing treatment of heavy metal materials.

In the preferred scheme, the mass ratio of the composite curing agent to the heavy metal material is 100: 5-20. Heavy metal materials such as waste incineration fly ash, heavy metal sludge and the like.

The process of the invention for curing heavy metal materials by using the composite curing agent comprises the following steps: mixing the biomass/sludge mixed burning ash, cement, gypsum and the solidified object domestic sludge ash/printing and dyeing sludge ash by ball milling at the normal temperature for 40min at 300r/min, and collecting the mixed dry powder for forming. And (3) uniformly stirring and mixing the water reducing agent and the water, adding the mixture into the mixture, stirring in a planet for 10min, adding the emulsified asphalt, and continuously stirring for 10min to obtain a solidified body. Curing the cured body for 7 days at the temperature of 20-30 ℃ and the relative humidity of 80 percent to finish the curing process of the sludge ash.

Compared with the prior art, the technical scheme of the invention has the following beneficial technical effects:

1) the technical scheme of the invention aims to treat waste by waste, two conventional waste biomass ashes and sludge ashes in the prior art are used as main components of the curing agent, and the curing agent has good curing and stabilizing effects on solid wastes rich in heavy metal substances, such as heavy metal ash, sludge, fly ash and the like, through formula improvement, thereby preventing secondary pollution of heavy metals to the environment, simultaneously realizing resource utilization on the biomass ashes, the sludge ashes and the like, and being beneficial to reducing the cost of the curing agent.

2) The curing agent raw material of the invention adopts industrial waste, has wide source and low price, treats waste by waste, and has higher social benefit and economic benefit.

3) The solidified body obtained after the curing of the curing agent has an obvious curing and stabilizing effect, the leaching value of heavy metals reaches the four-level standard (GB/T14848-93) of underground water, and the solidified body can be directly used for preparing high value-added materials.

4) The curing agent has good curing effect under the freeze-thaw condition, and reduces the physical strength of a curing body due to freeze-thaw loss.

Detailed Description

The following examples are intended to further illustrate the present disclosure, but not to limit the scope of the claims.

The biomass/sludge mixed combustion ash obtained in the following examples and comparative examples is prepared by mixing wood dust, rice hull and domestic sludge (dry basis weight), burning at a temperature of about 820 ℃, simply ball-milling and crushing ash obtained by burning, sieving by a 0.075mm sieve, and taking undersize powder to obtain the biomass/sludge mixed combustion ash, wherein the mass ratio of the wood dust ash, the rice hull ash and the domestic sludge ash in the mixed combustion ash is about 1:2: 3.

Example 1

A heavy metal solidified body is prepared from the following raw materials by weight (kg):

the biomass/sludge mixed burning ash is 10 percent, the P.O 42.5 grade ordinary portland cement is 7.2 percent, the desulfurized gypsum is 0.6 percent, and the domestic sludge ash/printing and dyeing sludge ash is 4.5 percent, and the mixture is ball-milled and mixed for 40min at the normal temperature at 300r/min, and the mixed dry powder is collected for forming.

0.25 parts of polycarboxylic acid high-efficiency water reducing agent and 4.8 parts of deionized water are stirred, mixed and uniformly added into the mixture. Stirring with planet for 10min, adding cationic emulsified asphalt PC-227.1, and stirring for 10min to obtain solidified body. The solidified body is maintained for 7 days at the temperature of 20-30 ℃ and the relative humidity of 80 percent to finish the heavy metal solidification process of the sludge ash.

The leaching characteristics of the target heavy metals (Ba, Cr, Cu, Mn, Ni, Zn) in the composite solidified body were evaluated, and the leaching results of the raw sludge ash and the solidified body are shown in tables 1-1a and b and tables 1-2:

tables 1-1a, b values of TCLP heavy metal leaching values for printing sludge ash, domestic sludge ash

TABLE 1-2 solidified body weight Metal Leaching Rate

Example 2

In the same raw material mixture and method as in example 1, 21.7 weight (kg) of sand was added before molding and stirring to obtain a biomass ash-based heavy metal solidified body that is a solidification-stabilized object of sludge ash, and according to the mechanical properties of the solidified body: fluidity (Table 2-1), compressive and flexural strength (Table 2-2), and freeze-thaw resistance (Table 2-3).

TABLE 2-1 cured body fluidity

TABLE 2-2 compression and rupture strengths of the cured bodies

TABLE 2-3 Freeze-thaw Strength loss of the cured bodies

The cured body has good mechanical property, can be applied to buildings, garden roadbeds, backfill materials and the like, and has wide application prospect.

Comparative example 1

The freeze-thaw resistance experiment tests the strength loss result and leaching result of the solidified body after 28 days as shown in the table 3-1a and b, wherein the solidified body is solidified aiming at domestic sludge through comparison of the emulsified asphalt without cation doping PC-2 and the emulsified asphalt with cation doping PC-2 in the example 1.

TABLE 3-1a comparison of Strength loss of cured bodies

TABLE 3-1a comparison of Leaching rates of solidification bodies

The results show that the asphalt well promotes the solidification of heavy metal ions under the freeze-thaw condition in a solidification system, and reduces the physical strength of a solidified body due to freeze-thaw loss.

Claims

1. The composite curing agent based on biomass and sludge mixed burning ash is characterized in that: the adhesive comprises the following components in parts by mass:

18-25 parts of biomass and sludge mixed burning ash;

12-15 parts of cement;

45-56 parts of emulsified asphalt;

0.5-1.5 parts of gypsum;

0.1-0.5 part of a water reducing agent;

the biomass and sludge mixed burning ash consists of biomass ash and sludge ash;

the mass ratio of biomass ash to sludge ash in the biomass and sludge mixed combustion ash is 2: 1-3;

the biomass and sludge mixed burning ash is obtained by burning a mixture of biomass and sludge at the temperature of 800-850 ℃;

the biomass comprises at least one of rice hulls, straws and wood chips.

2. The composite curing agent based on the biomass and sludge mixed burning ash as claimed in claim 1, wherein: the sludge ash comprises at least one of domestic sludge, printing and dyeing sludge and oil sludge.

3. The composite curing agent based on the biomass and sludge mixed burning ash as claimed in claim 1, wherein:

the cement is PO42.5 grade ordinary portland cement;

the emulsified asphalt is cationic emulsified asphalt PC-2;

the gypsum comprises at least one of desulfurized gypsum, fluorgypsum and phosphogypsum;

the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.

4. The composite curing agent based on the biomass and sludge mixed burning ash as claimed in claim 1, wherein: the composite curing agent comprises 20-25 parts of standard sand.

5. The application of the composite curing agent based on the biomass and sludge mixed burning ash as claimed in any one of claims 1 to 4, is characterized in that: the method is applied to the curing treatment of heavy metal materials.