KR20110098536A - Dredging sludge solidified agent and menufacturing method of mixed soil usign the same - Google Patents

Abstract

The present invention relates to a dredged sludge solidified material and a dredged mixed soil manufacturing method, more specifically, by using the absorption and exothermic action of CaO contained in a large amount of incineration residue to reduce the water content of the dredging sludge, deodorization and sterilization of microorganisms sterilization The present invention relates to a sludge solidified material and a dredged mixed soil manufacturing method using the same.
Dredging sludge solidified material according to the present invention is based on 100 parts by weight of incineration residue having a calcium oxide (CaO) content of 20% to 70%, 5 to 50 weight of fly ash having a calcium oxide content of 0.1 to 5% Contains wealth.

Description

Dredging sludge solidified fire and dredging mixed soil manufacturing method using same {DREDGING SLUDGE SOLIDIFIED AGENT AND MENUFACTURING METHOD OF MIXED SOIL USIGN THE SAME}

The present invention relates to a dredged sludge solidified material and a method of manufacturing a dredged mixed soil for landfill / embankment, and more specifically, by using the absorption and exothermic action of CaO contained in a large amount of incineration residues to reduce the water content of dredged sludge, lowland agricultural land The present invention relates to a dredged sludge solidified material used as a landfill / fill material or to construct a super dike, and a method of manufacturing dredged mixed soil using the same.

Korea is the last in 2001 to continue to increase the amount of dredging due to dredging operations, including maintenance fairway dredged up in 2006 to handle these dredged to achieve the maximum in 2006. Since then plummeted, but year around 1,300 to 22,400 10 000 m ³ range Tens of billions of dollars are spent each year. Nationwide, the dredging was done about 729,151,000 m ³ during this time was mostly athletics arena disposal (approximately 89%), offshore dumping an average of 4.6%, the effective recycling of dredged is very low. In 2008, the dredged soil dumped in other offshore and three designated waters off Busan was 1,557,000 tons, an increase of 2.6 times that of 398,900 tons in 2007. Recently, as the environmental impact assessment for the Four Rivers Restoration Project aimed at coping with floods and droughts, water quality improvement and ecological river creation, river-centered regional development and job creation, construction began with 16 reports. On November 10, 2009, construction of the four beams of Nakdong River, Gumibo, Hapcheonbo, and Yeongsan River Seungchonbo began. In addition, general construction such as river dredging and maintenance projects will begin soon (2009. 11. 16), and all construction will begin in sequence, and all projects will be completed in 2012, two years later. According to the Master Plan of Four Rivers Restoration (2009), the total dredging volume is about 5.7 million, and the aggregate (sand) is estimated to be 2.6 billion, which is 46% and 54% of dredging sludge will occur. Sand of 2.6 with a value as an aggregate eok m ³ is an environmental without problems through the selection operation, but can be sold directly, in the case of dredging sludge by introducing the flocculating agent to be embedded in the dredged treatment after dehydration and then treatment with a coagulating sedimentation do. According to the legal regulations on dredging sludge, if the dredging sludge is environmentally safe, the water content is 70% according to the 「Enforcement Regulation Annex 1-2 of the Construction Waste Recycling Promotion Act」 and “Enforcement Regulation Annex 17 of the Waste Management Act”. It can be dehydrated and dried so that it can be recycled to fill soil, auxiliary base material, road base material and landfill facility, farmland, lowland.

On the other hand, if the dredging sludge exceeds the criteria of "Exhibit 1 of the Enforcement Regulations of the Waste Management Act" and Exhibit 3 of the Enforcement Regulations of the Soil Environment Conservation Act, "the dredging sludge may be solidified or solidified by fire in accordance with the Enforcement Regulations of the Waste Management Act. It should be stabilized and buried in a managed landfill facility that can be disposed of designated wastes.

In this situation, technologies for recycling dredged soil have been studied. These techniques are technologies in which Portland cement, which is produced mainly from limestone, is mixed with dredged soil, as shown in Table 1.

Researcher Dredged soil initial function ratio Additive type, content rate Type of solidifying agent, content rate Uniaxial compressive strength Optimum solidification cost E ₅₀ -q _u Kim Ju-cheol and Lee Jong-kyu (2002) 100-160 Vegetable Bubble,
13-19.9% by volume cement
4, 6, 8, 10% 100-600 kPa
6.6 (aquatic curing)
4 (air cure) E ₅₀ = 82.857q _u (UC)
E ₅₀ = 22-167q _u (TC)
Restraint Pressure = 50 ~ 300kPa Kim Susam et al. (2002) 90-180% EPS beads 1, 2, 3% cement
1,2,3% 150 ~ 450kPa - - Gillim Lim and Byung-Tak Kim (2004) 125-200 Vegetable Bubble,
0.9-1.6% cement
6-18% 200 ~ 500kPa - E ₅₀ = 18 ~ 120, Restraint pressure = 50 ~ 400kPa Yoon Gil-lim and Kim Byeong-tak (2002) 90, 135, 180% EPS beads, cement
1,2,3% 200 ~ 500kPa Cement: 2%, restraint pressure = 50kPa
EPS: 3 ~ 4% E ₅₀ = 22q _u (UC)
E ₅₀ = 20 ~ 40q _u (TC)
Restraint Pressure = 50 ~ 300kPa Nam Jung-man and Yoon Joong-man (2004) 130-133.5% Pozzolanics, surfactants cement 100-500 kPa - Yun Tae Kim et al. (2005) 125-250% Waste Fishing Net, Bubble 1,2,3,4,5% cement
8, 12, 16, 20% 10 to 80 kPa (no reinforcement), 20 to 100 kPa (when reinforcing fishing nets) - (No reinforcement)
Yoon Tae Kim et al. (2006) 125-250% Bubble 1,2,3,4,5% cement
8, 12, 16, 20% 10 to 80 kPa -
Kim Yun-tae and Kang Hyo-seop (2008) 140% Waste tire powder 0 ~ 100%, low ash 100% 20% cement 180 ~ 450kPa - Kim Yun-tae and Han Woo-jong (2008) 120% Low Ash 100%, Synthetic Surfactant Foam 2%, Monofilament Short Fiber 0.25 ~ 1% 20% cement 130 ~ 200kPa -

Portland cement and lime is CO ₂ of limestone _{(CaCO 3, CaO · CO 2} ) About 0.55 tons of carbon dioxide is emitted in the calcining process for decomposition, and about 0.40 tons of carbon dioxide is burned when burning fossil fuel in the firing process, and thus, about 1 ton of carbon dioxide is produced every time 1 ton of cement and quicklime is produced. ₂ Concentration and cement production are highly correlated. In an international consultation on climate warming in Copenhagen, Denmark, in 2009, the Korean government announced a voluntary goal at home and abroad to reduce greenhouse gas emissions by 30% from the Business as Usual by 2020.

In this regard, future greenhouse gas reductions will emerge as the biggest issue in the cement and lime industry, with production expected to be reduced by more than 50%. Therefore, the recycling of dredged soil using cement used both in Korea and abroad so far requires huge economic costs to recycle the dredged soil that will be dredged through the Four Rivers Restoration Project. It is accompanied by a huge amount of CO ₂ emissions and damage to the natural environment.

Therefore, there is a need for a new concept of solidified fire which does not use quicklime, cement and iron sulfate, which are essential to recycle dredging sludge, and a technology for recycling dredging sludge using the same.

The present invention has been made to solve the above problems, an object of the present invention is to reduce the water content of dredged sludge by absorbing and exothermic action of CaO contained in a large amount of incineration residues, and utilized as landfill / soil material for lowland agricultural land The present invention provides a dredged sludge solidified fire used for building a super levee or a dredged mixed soil using the same.

In order to solve the above technical problem, the dredged sludge solidified material according to the present invention is fly ash having a calcium oxide content of 0.1 to 5% based on 100 parts by weight of the incineration residue having a calcium oxide (CaO) content of 20% to 70%. (fly ash) 5 to 50 parts by weight.

In addition, the incineration residue is one or a mixture of two or more selected from the group consisting of coal ash, paper sludge incineration residue, biomass incineration residue, sewage sludge incineration residue, RDF (Refuse Derived Fuel) incineration residue and RPF (Refuse Plastic Fuel) incineration residue. Is preferably.

In addition, the incineration residues preferably have a specific surface area of 2,500 to 6,000 cm 2 / g.

In addition, the fly ash preferably has an unburned carbon content of 8% or more.

In addition, it is preferable that a strength expression agent is further included in order to prevent the dredged sludge from solidifying the solidified product.

In addition, the strength expression agent is preferably a mixture of fine slag powder and sulfate stimulant.

In addition, the slag fine powder is preferably any one or a mixture of two or more selected from the group consisting of blast furnace slag fine powder, stainless steel slag fine powder and copper smelting fine powder.

In addition, the sulfate stimulant is preferably any one selected from calcium sulfate, aluminum sulfate, magnesium sulfate and sodium sulfate or a mixture of two or more thereof.

In addition, the strength expression agent is preferably mixed 5 to 50 parts by weight based on 100 parts by weight of the incineration residue.

In addition, it is preferable to further include a solidification accelerator in order to facilitate dredging sludge to solidify as soon as possible.

In addition, the solidification accelerator is preferably any one or a mixture of two or more selected from the group consisting of calcium aluminate cement, calcium sulfur aluminate cement, alumina cement and cemented carbide.

In addition, the solidification accelerator is preferably mixed with 0.1 to 10 parts by weight based on 100 parts by weight of the incineration residue.

In addition, it is preferable to further include an anti-sticking agent to prevent the solidified material or dredging sludge from being fixed to a manufacturing facility in the process of manufacturing or transporting the solids produced by solidification.

In addition, the anti-sticking agent is preferably any one or a mixture of two or more selected from the group consisting of limestone fine powder, feldspar fine powder, silica fine powder and granite fine powder.

In addition, the anti-sticking agent is preferably mixed 10 to 100 parts by weight based on 100 parts by weight of the incineration residue.

Dredged mixed soil manufacturing method according to the present invention comprises the steps of 1) preparing the solidified material; 2) mixing 5 to 100 parts by weight of the solidified material with respect to 100 parts by weight of dredging sludge; And 3) curing the mixture of the dredging sludge and the solidified material.

In addition, step 3) is preferably carried out by room temperature curing or heating curing the mixture.

In addition, step 3) is preferably performed until the water content of the mixture is less than 60%.

According to the present invention, there is an effect of reducing the water content of the dredged sludge by using CaO contained in a large amount in the incineration residue.

In particular, the exothermic effect of CaO has the effect of evaporating moisture.

In addition, porous incineration residue and unburned carbon present in fly ash have an effect of adsorbing and deodorizing ammonia gas.

In addition, it is also effective to sterilize the microorganisms contained in the dredging sludge by initially maintaining the pH 12 or more.

Figure 1a is a photograph showing the appearance of the dredging sludge at the time of occurrence, Figure 1b is a photograph of the appearance of dredged mixed soil specimen according to the present invention.
2a to 2c show the uniaxial compressive strength of the dredged mixed soil prepared by Examples 1 to 3, respectively.
3 is an electron micrograph of a solidified material in which the solidified material according to the present invention is mixed with dredging sludge.

Hereinafter, the dredging sludge solidified material according to the present invention and the preparation method of the dredging mixed soil using the same will be described in detail.

First, the components and actions of the dredging sludge solidified material according to the present invention will be described.

The dredged sludge solidified material according to the present invention includes an incineration residue having a calcium oxide (CaO) content of 20% to 70%, and a fly ash having a calcium oxide content of less than 0.1 to 5%.

Calcium oxide contained in a large amount in the incineration residue reacts with water to be absorbed, exothermic, and expand to form calcium hydroxide. The reaction scheme is as follows.

CaO + H ₂ O-> Ca (OH) ₂ +15.6 mol ^-1

Although incineration residues are generally recycled to concrete admixtures, incineration residues containing a large amount of calcium oxide are incapable of being used as concrete admixtures because of their absorption, heat generation, and expansion characteristics.

Therefore, the present invention is to use incineration residues that can not be utilized as a concrete admixture.

That is, when the dredging sludge having a high water content and the incineration residue containing a large amount of calcium oxide are mixed, the moisture of the dredging sludge is reduced while calcium hydroxide is produced by the above reaction. In addition, since the heat generated by the above reaction evaporates the moisture of the dredging sludge, it is possible to further reduce the water content of the dredging sludge.

Incineration residues containing 20% or more of calcium oxide are coal ash, biomass incineration residue, paper sludge incineration residue, sewage sludge incineration residue, RDF incineration residue and RPF incineration residue.

It is preferable that the specific surface area of the said incineration residue is 2,500-6,000 / g. If the specific surface area of the incineration residues is less than 2,500 / g, the amount of fine particles is insufficient, and the water content reduction effect is reduced when the dredging sludge is solidified, and when the specific surface area is more than 6,000 / g, the apparent density is lowered during the conveyance of the solidified material during weighing and conveying. It scatters and facility operability falls.

Coal ash is produced in many power plants. In particular, coal ash produced in a power plant having a desulfurization method in a furnace has a high content of calcium oxide. In the furnace desulfurization method, coal and limestone are mixed and burned, so the coal ash contains a large amount of free CaO.

In contrast, coal ash produced in power plants with separate desulfurization facilities has less than 5% calcium oxide.

Table 2 shows the difference between coal ash in power plants with separate wet desulfurization equipment and coal ash in power plants by furnace desulfurization.

Item Power plant coal ash with separate desulfurization Furnace  Desulfurization Power Plant Coal Ash Combustion fuel Coal (Import Bituminous Coal) Coal, limestone, waste tire (some power plants) Combustion temperature About 1350
-High combustion efficiency for economic power plant operation, reduction of coal ash generation rate and high quality coal ash discharge About 850
-Nitrogen emission reduction while decarbonation temperature range Exhaust Gas Desulfurization Facility Separate wet desulfurization facility Desulfurization Reaction with Limestone Mixture Exhaust gas denitrification plant Separate denitrification equipment Maintain low combustion temperatures and spray ammonia and other chemicals into boilers Chemical composition SiO _{2 ,} Al ₂ O _{3 ,} Fe ₂ O ₃ Due to limestone mixing
High free CaO component. Vitrification Degree high low Main recycling purpose Peak season with concrete admixture
Recycle all generation Clay substitute cement raw material,
Landfill of waste disposal site through long distance transportation Advantages and problems of using concrete admixture -Increased long-term strength with pozzolanic activity
- Improved workability
-Reduced unit quantity (durability, improved strength)
-Reduced heat of hydration (structure crack prevention) -Free CaO exothermic reaction
-Unit quantity increase (strength, durability decline)
-Increased heat of hydration (structure cracking)
-Reduced workability Etc KS L 5405 conformity product generation Do not satisfy the chemical composition and physical performance of KS L 5405

That is, the coal ash produced by the furnace desulfurization method contains a large amount of calcium oxide, but the coal ash produced in a facility equipped with a separate desulfurization device contains a very small amount of calcium oxide. Therefore, as described above, the coal ash produced in the facility equipped with a separate desulfurization device contains a small amount of calcium oxide can be recycled as a concrete admixture.

In other words, the incineration residue used in the solidified fire of the present invention is a coal ash produced by the desulfurization method with a high CaO content.

In addition, the fly ash is less than 5% calcium oxide content, the water absorption properties are relatively small compared to the incineration residues.

 Meanwhile, since the KS standard of fly ash for use as cement admixture is less than 5% of unburned carbon content, it is not suitable for use as a cement admixture, that is, fly ash with more than 12% of unburned carbon content at the time of occurrence. Or it is preferable to use a granulated fly ash having an unburned carbon content of 8% or more selected after purification. The unburned carbon contained in the fly ash has a property of adsorbing ammonia gas and heavy metal generated during solidification of the dredged sludge.

Therefore, the solidified material of the present invention is to use the incineration residue and fly ash as the main raw material that can not be recycled as a concrete mixed material.

The mixing ratio of the incineration residue and fly ash is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the incineration residue, but when the amount of fly ash is less than 5 parts by weight, the adsorption performance of ammonia and heavy metals is lowered. The water content reduction effect of dredging sludge is reduced.

In addition, the solidified material according to the present invention further comprises a strength expression agent in order to prevent the dredged sludge solidified and the resulting solids resludge, the strength expression agent is preferably a mixture of fine slag powder and sulfate stimulant.

In addition, the slag fine powder is any one selected from the group consisting of blast furnace slag fine powder, stainless steel slag fine powder and copper smelting fine powder, or a mixture of two or more thereof, and the sulphate stimulant is either one selected from calcium sulfate, aluminum sulfate, magnesium sulfate and sodium sulfate. It is preferable that it is a mixture of the above.

The strength expression at the early age according to the hydration reaction of the fine slag powder and the sulphate stimulant is achieved by the C-S-H gel produced simultaneously with a large amount of ettringite. In addition, CSH gel wraps Ettlingite, and as the age of the aging continues to increase, the CSH gel fills the voids of the hardened paste tightly, forming a dense network type network with Ettlingite, and continuously expressing high strength. Do it.

The strength expression agent is preferably mixed 5 to 50 parts by weight based on 100 parts by weight of the incineration residue. If the amount of the strength expression agent is less than 5 parts by weight, the amount of hydrate produced may be insufficient, and reslurrying may occur. If the amount is more than 50 parts by weight, the amount of hydrate is excessively increased and the strength is greatly increased. Can't use it.

In addition, the solidifying material according to the present invention may further contain a solidification accelerator such as calcium aluminate cement, calcium sulfur aluminate cement, alumina cement and cemented carbide. When the solidification accelerator is further mixed, the dredging sludge is solidified as soon as possible, thereby exhibiting the strength of the solids within a short time, and thus making it possible to use it as a cover material.

In addition, in the solidified material according to the present invention, limestone, feldspar, silica, granite fine powder, and the like may be further mixed as an anti-sticking agent. This is to increase productivity by preventing the solidified material or dredging sludge is fixed to the manufacturing equipment in the process of manufacturing or transporting the solids produced by solidification.

The amount of the anti-sticking agent is mixed in an amount of 10 to 100 parts by weight based on 100 parts by weight of the incineration residue. If the amount of the anti-sticking agent is less than 10 parts by weight with respect to 100 parts by weight of the incineration residue, there is no anti-sticking effect, and if it exceeds 100 parts by weight, the water content reduction effect is lowered.

Hereinafter, a method for preparing dredged mixed soil according to the present invention will be described.

First, the above-mentioned solidified material is manufactured, and then 5-100 parts by weight of the solidified material is uniformly mixed with respect to 100 parts by weight of the dredging sludge. If the solidified material is mixed at less than 5 parts by weight, the moisture content is not sufficiently reduced, so that it cannot be used as a cover material. If it is mixed at more than 100 parts by weight, the water content is too low, and solids are scattered and covering work becomes difficult.

Finally, the mixture of the dredging sludge and solidified material is cured at room temperature or heated until the moisture content is 70% or less.

Example  One

First, 20 parts by weight of fly ash having an unburned carbon content of 11% and a calcium oxide content of 0.6% with respect to 100 parts by weight of coal ash having a calcium oxide content of 42% by furnace desulfurization, and 60 blast furnace slag fine powders as a strength expression agent 20 parts by weight of a mixture consisting of% and 40% by weight of calcium sulfate, 3 parts by weight of calcium aluminate cement as a solidifying accelerator, and 20 parts by weight of limestone as a fixing agent were uniformly mixed to prepare a solidified material.

Next, with respect to 100 parts by weight of the dredging sludge having a water content of 100%, by mixing 10 parts by weight of the solidified material prepared as above to prepare a dredging mixed soil by room temperature curing.

Example  2

With respect to 100 parts by weight of the dredging sludge having a water content of 100%, 15 parts by weight of the same solid material as in Example 1 was mixed to cure at room temperature to prepare a dredged mixed soil.

Example  3

With respect to 100 parts by weight of the dredging sludge having a water content of 100%, 20 parts by weight of the same solid material as in Example 1 was mixed to cure at room temperature to prepare a dredged mixed soil.

Performance test method and result of dredged mixed soil

As shown in Table 3 below, the water content was measured by the KS F 2306 method, and the compressive strength and permeability test were performed by the KS F 2343 and KS F 2322 methods.

Experiment Way Remarks Water content KS F 2306 Soil content measurement method Compressive strength KS F 2343 Uniaxial compressive strength method

(1) water content change

The moisture content of the dredged mixed soil prepared by Examples 1 to 3 according to time is shown in Table 4 below. As confirmed in Table 4, the water content of the dredging sludge before mixing the solid fire was 100%, it can be seen that the water content is rapidly reduced over time. As described above, the moisture content is greatly reduced because the exothermic reaction occurs immediately after the solidified material is mixed with the dredging sludge and the hydration reaction proceeds simultaneously. In addition, the moisture content is rapidly reduced by the formation of hydrate and natural drying over time. Except for the results of the daily curing of Example 1, it can be seen that in the case of Example 2 and Example 3, an improvement suitable for recycling the dredged mixed soil as a fill material, etc. was achieved only by the daily curing. If it is used as fill material after 3 days of natural curing, it is expected to not only be easier to handle but also to increase the compressive strength.

Figure 1a shows the appearance at the time of discharge of dredged sludge, Figure 1b shows the appearance of the dredged mixed soil specimen solidified by Example 2. The color of dredged soil solids is similar to natural ocher, so even if it is used as landfill material when compared with dredged soil at the time of occurrence, it is expected to greatly reduce psychological rejection among local residents and engineers.

division Dredged raw material 1 day 3 days Example 1 100% 72.4% 68.7% Example 2 100% 66.5% 57.3% Example 3 100% 65.1% 53.55%

(2) Uniaxial compressive strength  change

2A to 2C show changes in the uniaxial compressive strength of the dredged mixed soil prepared by Examples 1 to 3, respectively. As can be seen through the seven days of curing, Example 1 was 1.45kgf / cm ² , Example 2 was 3.61kgf / cm ² , Example 3 was shown to increase to 4.37kgf / cm ² . This is much higher than 0.5kgf / cm ² and 1.0kgf / cm ² , which are the strength standards of cover and fill materials, and showed strength expression that can be used for various ground materials such as soft ground improvement material, water repellent material, and backfill material. . When mixed with solidified materials, it can reduce moisture and surface dredging sludge due to absorption heat generation reaction, resulting in the consolidation of particles by the consolidation of particles, and the calcium silicate reaction is induced by CaO and SiO ₂ to increase the compressive strength. This is because the solidification reaction that can be secured occurs to increase the strength. In addition, the moisture content of dredged sludge is relatively lowered by the absorbency of solidified materials, and the clay and colloidal components, which are particulates, are separated by the absorbent and ion exchange, pozzolanic, and carbonation reactions of solidified materials. Thus, uniaxial compressive strength is increased.

Figure 3 shows the microstructure of the dredged mixed soil prepared by Example 3. In the dredged mixed soil prepared by the present invention, a large number of reaction products of acetrite and honeycomb CSH gel of needle crystals have been observed.

(3) before and after immersion Uniaxial compressive strength  change

When the dredged mixed soil prepared by the present invention is used as daily cover material of landfill, it should not only have the required strength, but also the reslurrification phenomenon and the strength reduction phenomenon caused by the flooding of heavy rain, heavy snow, etc. something to do. Therefore, in this experiment, the change of uniaxial compressive strength of the dredged mixed soil cured for 7 days was investigated before and after 1 day inundation.

The change in uniaxial compressive strength before and after immersion is shown in Table 5 below. As can be seen through this, dredged mixed soil prepared by Example 1 is -0.07kg / kg / cm ² , dredged mixed soil prepared by Example 2 is -0.10kg / cm ² , prepared by Example 3 The dredged mixed soils showed -0.18kg / cm ² intensity change rate.

As can be seen from the above results, the change in uniaxial compressive strength before and after immersion of dredged mixed soils by the mixing ratio of solidified materials showed a relatively small reduction rate. It seems that absorption does not occur. Therefore, when the dredged mixed soil manufactured according to the present invention is used in landfills, reslurrying or deterioration of strength due to flooding due to snowfall is insignificant. It is not expected to interfere with the operation of the equipment and the equipment.

Strength expression at early age following solid fire input is achieved by the C-S-H gel in which the strength-expressing agent is formed simultaneously with a large amount of ethringite. In addition, the C-S-H gel fills the voids of the hardened paste tightly, forming a dense networked network structure with ettringite and continuously expressing high strength. Therefore, if the content of the strength-expressing agent is increased according to the use of the solidified, it can express the strength that can be utilized not only for the cover material but also for various ground materials such as the fill material, the order material, and the backfill material.

Before immersion (kg /) After immersion (kg /) Intensity change Example 1 1.45 1.38 0.07 Example 2 3.61 3.51 0.10 Example 3 4.37 4.19 0.18

(4) pH  change

The pH change according to the natural curing date of the mixture of dredging sludge and solidified material is shown in Table 6. As a result of the experiment, strong alkali was changed from pH 4 ~ 5 from pH 4 to 5, when the physical change of dredged sludge was finished, and it was considered that it could minimize the environmental pollution caused by pH. It is thought to act as an inhibitor.

In the solidified material according to the present invention, the CaO reacts with water and is transferred to Ca (OH) ₂ , and the solids exhibit a strong alkali state. However, as the curing process proceeds, the hydration of Ca (OH) ₂ fly ash and fine slag powder is performed. It is thought to gradually change to a weak alkali state as the pH is lowered gradually.

Right after mixing 3 hours after mixing 1 day 3 days 5 days 7 days 9th 11th 13th Example 1 11.8 11.5 11.5 11.0 10.0 9.0 8.9 9.0 8.9 Example 2 11.9 11.5 11.6 11.0 10.2 9.1 9.0 9.2 9.1 Example 3 12.1 11.6 11.6 11.2 10.3 9.1 9.1 9.2 9.2

(5) heavy metal elution

Table 7 below shows the heavy metal dissolution test results of the dredged mixed soil prepared by Example 1. As can be seen from this, most of heavy metals were not eluted, and when applied to the waste dissolution test method in Korea, trace amounts of lead, mercury, and arsenic were detected, but the environmental standards were satisfied. This is because the heavy metal is substituted or fixed into the crystal structure by being fixed by the hydrate generated in the hydration reaction. Therefore, the dissolution concentration in all these experiments is much lower than the standard value or is not detected. Therefore, even if the dredging sludge is solidified and used as daily cover material of landfill, secondary pollution due to heavy metal leaching is not considered to be a concern.

Hazardous Substances
Dissolution Method CD As Pb Hg Cr ⁶⁺ Cu Org.P TCE PCE Waste Dissolution Test Method
(KSLP) standard 0.3 1.5 3.0 0.05 1.5 3.0 1.0 0.1 0.3 Solid N.D. 0.004 0.001 0.001 0.001 0.28 N.D. N.D. N.D. US EPA
(TCLP) standard 1.0 - 5.0 0.2 5.0 - - - - Solid N.D. - 0.002 N.D. N.D. - - - - * N.D: Not Detected

(6) Small model test evaluation to evaluate the stability of cover material in landfill

Small model test is to test performance performance of cover material at the time of actual landfill. A cylinder with diameter of 10cm and height of 15cm is made, and a valve is installed at the lower 4cm part. After mixing, adjust the ratio at 25, 30, 35, 40, and 45%, and after 28 days, apply the condensation test with a compression tester to calculate the strength and test the COD, pH, and heavy metal content of the effluent flowing down. And organic matter content was measured.

As a result, environmental engineering experiments such as pH, organic matter, heavy metal elution, BOD and COD showed weak alkalinity with pH of 7.7, and heavy metal elution was (Cd, Cu, Pb, Cr, Zn) between 0.00102 and 0.3427. Enforcement Rule The leachate discharge limit was met. In addition, BOD and COD also satisfies the 150 mg / L and 70 mg / L values specified in the Waste Management Act.

(7) To evaluate the settlement of cover material at landfill Earthwork Test

Soil test was conducted to analyze the settlement amount of cover material at the time of landfill using 105 cm high, 42 cm wide and 78 cm long. Up to 500kg was loaded to observe the load and settlement over time. The results of the soil test showed that almost all settlements occurred within 80 hours. In other words, dredged mixed soil prepared by the present invention is not suitable for use as a landfill cover material because the settlement is not long.

As a result of all the experiments, the dredged mixed soil produced by the present invention can be said to be highly applicable as a cover material and landfill material. The results are summarized in Table 7 below.

division  Performance of this product Mixture appearance Natural ocher Reslurry None (after 7 days of age) pH 3 days after discharge: pH 11 ~ 12
After 3 days: pH 9-10 Water content 53-68% (3 days after mixing) Uniaxial compressive strength Fit (approximately 1.5-4.5 kgf / cm ² , 7 days old) Heavy metal elution Appropriate (age 7 days, baseline 1/10 or less) Small model test (BOD, COD) BOD 10 or less (baseline 150 mg / L)
COD 40 or less (reference value 70 mg / L) Earthwork Experiment Almost all settlements occur within 80 hours

Claims (18)

Dredging sludge characterized in that it comprises 5 to 50 parts by weight of fly ash having a calcium oxide content of 0.1 to 5% with respect to 100 parts by weight of incineration residue having a calcium oxide (CaO) content of 20 to 70%. fire.
The method of claim 1,
The incineration residue is any one or a mixture of two or more selected from the group consisting of coal ash, paper sludge incineration residue, biomass incineration residue, sewage sludge incineration residue, RDF (Refuse Derived Fuel) incineration residue and RPF (Refuse Plastic Fuel) incineration residue. Dredge sludge solidified fire, characterized in that.
The method of claim 2,
The incineration residue is dredged sludge solidified material, characterized in that the specific surface area of 2,500 ~ 6,000 ㎠ / g.
The method of claim 1,
The fly ash dredged sludge solidified material, characterized in that the unburned carbon content is 8% or more.
The method of claim 1,
A dredging sludge solidified fire further comprising a strength expression agent to prevent the dredged sludge solidified from being solidified.
The method of claim 5,
The strength expression agent is dredged sludge solidified material, characterized in that the mixture of fine slag powder and sulfate stimulant.
The method of claim 6,
The slag fine powder is any one or a mixture of two or more selected from the group consisting of blast furnace slag fine powder, stainless steel slag fine powder and copper smelting slag fine powder.
The method of claim 6,
The sulfate stimulator is dredge sludge solidified material, characterized in that any one selected from calcium sulfate, aluminum sulfate, magnesium sulfate and sodium sulfate or a mixture of two or more.
The method of claim 6,
Dredging sludge solidified material, characterized in that the strength expression agent is mixed 5 to 50 parts by weight based on 100 parts by weight of the incineration residue.
The method of claim 1,
Dredging sludge solidified material, characterized in that it further comprises a solidification accelerator in order to facilitate the dredging sludge solidified quickly.
The method of claim 10,
The solidification accelerator is any one or a mixture of two or more selected from the group consisting of calcium aluminate cement, calcium sulfur aluminate cement, alumina cement and cemented carbide cement.
The method of claim 11,
The solidification accelerator dredging sludge solidified material, characterized in that mixed 0.1 to 10 parts by weight based on 100 parts by weight of the incineration residue.
The method of claim 1,
Dredging sludge solidified material, characterized in that the solidified material or dredged sludge is further solidified to prevent adhesion to the manufacturing equipment in the process of manufacturing or transporting the solids produced by solidification.
The method of claim 13,
The anti-sticking agent is dredged sludge solidified material, characterized in that any one or a mixture of two or more selected from the group consisting of limestone fine powder, feldspar fine powder, silica fine powder and granite fine powder.
The method of claim 14,
Dredging sludge solidified material, characterized in that the anti-sticking agent is mixed 10 to 100 parts by weight based on 100 parts by weight of the incineration residue.
1) preparing a solidified material according to any one of claims 1 to 15;
2) mixing 5 to 100 parts by weight of the solidified material with respect to 100 parts by weight of dredging sludge; And
3) curing the mixture of the dredge sludge and solidified material; dredging mixed soil manufacturing method comprising a.
The method of claim 16,
Step 3) is a method for producing dredged mixed soil, characterized in that the mixture is carried out at room temperature curing or heating curing.
The method of claim 16,
Step 3) is a method of producing dredged mixed soil, characterized in that performed until the water content of the mixture is less than 60%.

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