KR20090083971A - Environment-conscious embankment material using high-volume industrial waste and manufacturing method thereby - Google Patents

Abstract

A method for manufacturing an environment-friendly embankment material is provided to increase concretion strength of embankment material, and to prevent elution of harmful materials by phosphogypsum and bypass dust as a stimulant of slag. A method for manufacturing an environment-friendly embankment material using a large amount of industrial waste comprises the steps of: homogeneously mixing 100.0 parts by weight of slag fine powder, 100~300 parts by weight of phosphogypsum and 20~100 parts by weight of bypass dust to obtain a binder; and mixing 100.0 parts by weight of the binder and 100~1000 parts by weight of at least one selected from mud sludge, waste fundary sand and construction material waste.

Description

Eco-friendly soil material using a large amount of industrial waste and its manufacturing method {ENVIRONMENT-CONSCIOUS EMBANKMENT MATERIAL USING HIGH-VOLUME INDUSTRIAL WASTE AND MANUFACTURING METHOD THEREBY}

The present invention relates to a method for producing an environmentally friendly earthen material that can produce artificial landfill material with excellent physical properties by recycling industrial by-products and waste, and more specifically, homogeneous mixing of phosphate gypsum and bypass dust in fine slag powder. It relates to a method for producing environmentally friendly landfill material using a large amount of industrial waste, characterized in that it comprises the step of obtaining, and mixing the binder with at least one selected from mud sludge, waste foundry sand and construction waste.

Various materials are used in various construction works, and the most amount is consumed, and the materials used in various fields are basic materials.

Soil has been used as a natural material in almost all fields so far. Generally, soil in construction works includes silt, clay, sand and gravel.

Filling is carried out throughout the construction work such as civil works, building work, road work, and landscaping work, and the filling material is earthwork, site facility work, facility facility work, designation and foundation work, road body, roadbed, frostbite prevention layer, auxiliary base and It is used for base construction, site construction, stop construction and landscaping packaging.

In particular, the Saemangeum construction work is being carried out in Jeonbuk area, and a large amount of landfill materials are needed in the future. If the landfill site is developed and used for landfill construction, the environmental destruction problem arises due to the development of landfill sites. With the prosperity of the business, the development of terrestrial landfills is becoming increasingly difficult. Moreover, the recovery of forests after the development and use of the pit is expensive, but the recovery of the natural environment, such as the original state, is difficult and the cost of landfill construction is also increasing.

Recently, some artificial soil materials are used as a countermeasure. However, most of them are simple substitutes for replacing only a small amount of existing soil materials, or mixed cement or solid material with existing soil materials, or in the form of cement blocks or concrete blocks from the beginning. It is only manufactured and applied to fill, and construction waste materials such as waste concrete and waste asphalt are being considered, but there are still problems that cannot be solved in terms of conservation of natural environment and economic feasibility.

Therefore, it can be said that it is urgent to develop a new fill material that can replace the existing soil material natural soil material.

Recently, the landfill method using a part of various industrial wastes such as steelmaking slag, waste concrete, and waste foundry sand in natural soil has been adopted in many construction sites. This method is characterized by the reduction of the natural soil at the same time as the treatment of industrial waste, but it is only a physical substitution, it is not certain about the immobilization mechanism by elution of harmful substances.

In order to prevent this, the method of increasing the freezing strength by using Portland cement is the most widely used. This is because it can improve the high strength of the sedimentary soil material and reduce the secondary environmental pollution caused by the dissolution of harmful substances. In reality, however, the economical efficiency of the large amount of Portland cement is poor. Therefore, the method of solidifying the soil material using such cement may be disadvantageous in terms of economical efficiency.

The Ministry of Environment clarified the basis for appropriately managing and improving the unreasonable regulations in order to minimize the burden on corporations and expanding the scope of recycling to promote the recycling of waste. If industrial wastes are used as landfill materials in an indiscriminate manner as described above, it is difficult to have stability against secondary environmental pollution. Therefore, the Ministry of Environment must meet the regulations on soil pollution standards as of January 1, 2007. The bill was newly issued.

On the other hand, phosphate gypsum produced in the production of phosphoric acid in the fertilizer plant is not only economic value, but also very strong acidic material of pH 2-3, contains some heavy metals (Cr, Cd) and radioactive material (radon) Classified as general waste. Domestic phosphate gypsum is discharged about 2.35 million tons per year, most of which is unused, and most of it is stored in gypsum. In addition, the gypsum stockyards of N and other fertilizer companies are almost saturated, and the utilization rate of phosphate gypsum is gradually decreasing as the quality of desulfurized gypsum emissions from power plants and petrochemical plants increases. The reserve is about 30 million tons.

Blast furnace slag is an industrial by-product generated from various metal smelting processes, and its use and method are very similar to coal ash. Especially, unpowdered slag has latent hydrophobicity and is widely used in cement and concrete fields. In the case of slag, a large amount of slag is generated in the steelmaking process of a global steelmaker. Slag emitted from the steelmaking and steelmaking processes is also widely used as a fill material. Blast furnace slag is similar to general rock when it is slow cooled, so it can be used as semi-finished soil material after crushing. However, when blast furnace slag is quenched and pulverized, it can be used as a substitute for cement with high added value. The use of landfill material is disadvantageous in terms of economic feasibility. Since steel slag does not exhibit any potential hydraulic property, it is currently used 100% as a total amount of landfill and road substrate.

Bypass dust is the waste generated during the cement manufacturing process, which is installed in the inlet of the cement kiln (firing furnace), and refers to the dust generated from the bypass precipitator which mainly collects the volatiles generated from the cement kiln. About 7-10% of the total. Bypass dust, on the other hand, contains a large amount of chlorides and alkalis, which are then coated on cement kilns to corrode the plant and cause process problems such as the formation of low melting point reaction products and nonuniformity of firing temperatures. The cement industry has a lot of difficulties in their proper disposal problem.

Mud sludge refers to by-products such as construction sludge, dredged soil treated turbidity, stone and aggregate plants, and by-products such as mud sludge containing approximately 40% or more of silica. desirable. Above turbid water is used to remove mud powder and unnecessary fine stone powder attached to the spinning equipment using washing water to improve product quality in the production equipment for producing fine aggregates for concrete. Refers to washing after washing, which contains particles or mud, or muddy water. In the turbid water, mud separated from water by a mechanical equipment for concentrated dehydration such as a concentrator and a filter press, or sedimentation knowledge equipment is concentrated and dewatered to become a mud sludge containing silica and containing water. Such mud sludge does not have a stable mass demand at all times, so it is not possible to expect an increase in the amount of use. In addition, the crushed stone is classified into a crusher having a particle size of 5 mm or less in a crushing plant of a crushed stone plant by a dry classifier such as an air separator to remove the fine crystalline particles of 75 μm or less, and collected by a dust collector. It refers to the fine stone particles that are μm. Although the development is progressing to use as a substitute for limestone powder, which is a mixture of high-flowing concrete, the amount of limestone powder is insufficient compared to the amount of limestone powder. It is true. In addition, dredged soil treatment turbidity usually occurs when the dredged soil, which has a high water content, generated when dredging lakes, swamps, rivers, and dam lakes is separated into large and small stones, sand, etc. using a sieve classifier. Turbidity refers to turbid water, and construction sludge has high water content and high-molecular excavation due to civil construction such as underground continuous wall construction, water shielding, and high pressure spray stirring. Say Most of such dredged soil treated sewage and construction sludge are not only mud cakes due to reduction of water, but also a useful process that leads to reduction of waste from an environmental health point of view is required.

The mud sludge has characteristics very similar to that of natural soil, but it is not easily utilized as a fill material because of high water content, low shear strength, and high compressibility. Therefore, the development of a method for improving or reinforcing the characteristics of the fill material is required.

Over 900,000 tons are generated annually as by-products in steelmaking, foundries, ports, ships, and steelmaking, but more than 90% of them are simply landfilled, and only 6% of them are produced from road substrates and cement secondary products. The situation is being recycled. In general, the casting industry is a field that needs continuous support development at the national level, such as industrial machinery, harbors, ships, automobile parts, and metal machine tools. Various waste castings generated during the smelting and production process of each company are added with various chemicals, which are components of the wastewater treatment agent, and a large amount of iron oxide, zinc oxide, silica calcium silica, and some sulfur, etc. It is included. And the harmful substance contains a small amount of lead, cadmium, chromium, copper and the like. Despite the fact that such waste foundry sand can be recycled and used, most of them rely on or leave landfill due to the lack of technology for reclaiming waste foundry sand at each company, excessive investment, and avoidance of recycled foundry sand at foundries. Is most of them.

Construction wastes means waste soils, waste concrete, waste asphalt concrete, waste bricks, wastes, waste stones and other non-metallic mineral materials, which account for the majority of construction wastes and are increasing rapidly.

In Europe and Japan, there are many cases of active re-use as a landfill material, not only for wastes specified in the domestic waste management law, but also for wastes containing some other harmful substances. However, industrial wastes containing hazardous substances are solidified with cement and lime, and contain secondary environmental pollution. They are reused as asphalt pavement, cement stabilization, and soil improver.

The present invention uses the industrial waste phosphate gypsum and bypass dust as a slag stimulant to improve the solidity strength of the sedimentation material by their hydration reaction, prevent the leaching of harmful substances, the mass utilization of industrial waste, such as physically compared to the existing artificial landfill material · The purpose is to provide an environment-friendly landfill material manufacturing method using a large amount of industrial waste, which can produce landfill material excellent in environmental and economic aspects.

The present invention for achieving the above object comprises the steps of: a) homogeneously mixing the phosphate gypsum and bypass dust in the fine slag powder;

b) mixing the binder with at least one selected from mud sludge, waste foundry sand and construction wastes; provides an environmentally friendly earthenware material using a large amount of industrial waste, characterized in that it comprises a.

In the step a), 100 to 300 parts by weight of fine slag powder is mixed with 100 to 300 parts by weight of phosphate and bypass dust to 20 to 100 parts by weight to obtain a binder.

In addition, the step b) is preferably 100 to 1000 parts by weight of one or more selected from mud sludge, waste foundry sand and construction wastes to 100 parts by weight of the binder.

In addition, the present invention provides an environmentally friendly fill material using a large amount of industrial waste, characterized in that produced by the manufacturing method.

Hereinafter, a description will be given of a manufacturing method of environmentally friendly landfill material using a large amount of industrial waste of the present invention.

The method of manufacturing the fill material of the present invention comprises the steps of homogeneously mixing the phosphate gypsum and bypass dust into the slag powder to obtain a binder, and mixing the binder with at least one selected from mud sludge, waste foundry sand and construction wastes. Is done.

First, the binder manufacturing step is to enhance the high grain strength of the fill material, it is made by homogeneously mixing the phosphate gypsum and bypass dust in the fine slag powder.

The fine slag powder is suitable for the blast furnace slag and stainless slag having a latent hydraulic properties and a powder degree of 3,000 to 6,000 cm 2 / g.

And the phosphate gypsum is to induce an appropriate hydration reaction with the fine slag powder, since the pH of the discharged state is a strong acid of 2-4, it is preferable to use it after neutralization using quicklime and slaked lime. The phosphate gypsum can be used if it is neutralized with the discharged and accumulated hydrated state, after crushing the agglomerate, and the specific surface area is 2,000 cm2 / g or more.

In particular, the phosphate gypsum is preferably mixed with 100 to 300 parts by weight based on 100 parts by weight of fine slag powder in order to induce an appropriate hydration reaction with the fine slag powder.

The bypass dust is a 6,000 ~ 10,000 ㎠ / g ultra-fine particles containing a large amount of alkali and chloride, has a hardening property like a general cement, and serves as an alkali stimulator of slag. In particular, the chloride component contained in the bypass dust promotes the hydration reaction of slag-phosphate gypsum, thereby further enhancing the high grain strength of the fill material.

In addition, the bypass dust is filled with a small gap between soil and soil such as dredged soil, which is a mud sludge, because the specific surface area of general portland cement is about 3,300 cm 2 / g of ultrafine particles having a specific surface area of 6,000 to 10,000 cm 2 / g. Hydrates can be produced, contributing to stabilization of fill material.

In particular, the bypass dust is preferably mixed 20 to 100 parts by weight with respect to 100 parts by weight of slag in order to effectively promote the curing reaction of the slag-phosphate gypsum.

Next, the binder is mixed with at least one selected from mud sludge, waste foundry sand and construction wastes to obtain an artificial landfill material.

At this time, at least one selected from the mud sludge, waste foundry sand and construction wastes is preferably mixed 100 to 1000 parts by weight based on 100 parts by weight of the binder.

Mud sludge refers to by-products such as construction sludge, dredge sludge, dredged soil treated turbidity, turbid sludge, and stone powder from stone and aggregate plants.At this time, mud sludge containing approximately 40% or more silica is used, It is preferable to prepare.

Since mud sludge has a very high water content at the time of discharge, the discharged solids should be dehydrated to below 70% water content.

The mud sludge has characteristics very similar to that of natural soil, but it has not been easily used as a fill material since it has high field water ratio, low shear strength, and high compressibility. It is possible to increase the quality of the fill material when using relatively large and solid waste foundry sand and construction waste materials as reinforcement materials.

And it is good to use the waste casting sand that the amount of traverse of trachea 4 is 25-100%, the traverse of the trachea 300 is 25% or less. When manufacturing the fill material using only waste casting sand, the compressive strength is low and the particle size distribution is poor, but when the binder and the mud sludge are mixed, a good particle size can be formed and the compressive strength can be prevented from being lowered. Waste casting sand acts as a sand of the natural soil in the landfill material of the present invention, it contains a heavy metal, it is preferable to use a batch dissolution test to meet the waste disposal criteria, but even when exceeded by the hydration reaction of the binder Hazardous substances can be immobilized stably.

Construction wastes means waste soils, waste concrete, waste asphalt concrete, waste bricks, waste, waste stone and other non-metallic minerals, and can be used with a maximum diameter of 100mm or less and 1% of foreign matter (volume basis).

Since construction wastes do not contain harmful components, it is preferable to recycle them for other purposes besides landfill materials, but it is preferable to use those that are not suitable for recycling for other purposes. For example, waste concrete and waste asphalt concrete can be used as waste aggregates for asphalt concrete and cement concrete when the waste mortar is properly removed.

Environment-friendly landfill material using a large amount of industrial waste of the present invention prepared as described above can be used as a subbase material, road substrate material, ground stabilizer and cover material at the construction site by replacing by using 50 to 100 parts by weight.

Environment-friendly landfill material using a large amount of industrial wastes according to the present invention uses phosphate gypsum and bypass dust as slag stimulants to enhance the high-strength strength of the landfill material by the hydration reaction, prevent the dissolution of harmful substances, and make large use of industrial wastes. Compared to artificial landfill materials, it has excellent effects in terms of physical, environmental, and economic.

Hereinafter, described in more detail with reference to the production method of the environment-friendly landfill material using a large amount of industrial waste of the present invention as follows, the scope of the present invention is not limited to the following examples.

For comparison of the performance of conventional construction materials using natural materials and eco-friendly soil materials by phosphate gypsum-slag hydration reaction, mud sludge, waste foundry sand, As the construction wastes were mixed, each performance ratio was examined through KS standard tests such as liquid limit, plasticity index, modified CBR, permeability coefficient, stability, wear rate, and sand equivalent. Each test was carried out according to the test method specified in KS standard.

[Table 1] Evaluation Items and Methods

Test Type Test standard Evaluation item Liquid limit KSF 2303    Physical performance evaluation Plasticity index KSF 2304 Modified CBR KSF 2320 Permeability coefficient (cm / sec) KSF 2303 stability(%) KSF 2303 Wear rate (%) KSF 2303 Sand equivalent (%) KSF 2303 Heavy Metal Dissolution Test Domestic Dissolution Test Method (KMS Method) American Dissolution Test Method (TCLP)  Eco-friendly Stability Assessment

Example 1

A binder was prepared by mixing 200 parts by weight of phosphate gypsum and 30 parts by weight of bypass dust to 100 parts by weight of fine slag powder. And the clay material of Example 1 was prepared by mixing 100 parts by weight of dredged soil having a water content of 65% as mud sludge with respect to 100 parts by weight of the binder.

After replacing 50 parts by weight of the landfill material with respect to the natural soil, experiments were conducted on various physical properties such as liquid limit and plasticity index.

Example 2

A binder was prepared by mixing 300 parts by weight of phosphate gypsum and 20 parts by weight of bypass dust in 100 parts by weight of fine slag powder. And the clay substitute material of Example 2 was prepared by mixing 200 parts by weight with respect to 100 parts by weight of the earth substitute material composed of a mixture of dredged soil having a water content of 65% as a mud sludge and waste foundry sand at a ratio of 4: 3.

After replacing 50 parts by weight of the landfill material with respect to the natural soil, experiments were conducted on various physical properties such as liquid limit and plasticity index.

Example 3

A binder was prepared by mixing 100 parts by weight of fine slag powder with 100 parts by weight of phosphate gypsum and 25 parts by weight of bypass dust. In addition, the earth substitute material of Example 3 was prepared by mixing 300 parts by weight of an earth substitute made by mixing a construction sludge having a water content of 60% as mud sludge and waste concrete at a ratio of 4: 3 as a construction waste material.

After replacing 70 parts by weight of the fill material with respect to natural soil, experiments were conducted on various physical properties such as liquid limit and plasticity index.

Example 4

A binder was prepared by mixing 250 parts by weight of phosphate gypsum and 100 parts by weight of bypass dust in 100 parts by weight of fine slag powder. In addition, the earth substitute material, which is a waste casting sand and construction bricks, was mixed in a ratio of 1: 1 by mixing 150 parts by weight with respect to 100 parts by weight of the binder to prepare a fill material of Example 4.

After replacing 60 parts by weight of the soil material with respect to the natural soil, experiments were conducted on various physical properties such as liquid limit and plasticity index.

Example 5

A binder was prepared by mixing 200 parts by weight of phosphate gypsum and 30 parts by weight of bypass dust to 100 parts by weight of fine slag powder. And the soil substitute material of Example 5 by mixing 100 parts by weight of the earth substitute material made by mixing the waste concrete with a water content of 65% as mud sludge, waste foundry sand and construction wastes in a ratio of 3: 1: 1. Prepared.

After replacing 100 parts by weight of the fill material with respect to natural soil, the experiments were performed on various physical properties such as liquid limit and plasticity index.

Comparative Example 1

As Comparative Example 1, experiments were conducted on various physical properties such as liquid limit and plasticity index using only natural soil.

Comparative Example 2

Without using slag powder, phosphate gypsum, and bypass dust, and mixing waste concrete with mud sludge (65% water content), waste foundry sand, and construction wastes at a ratio of 4: 3: 3, the artificial soil material is mixed with natural soil. 70 wt% was substituted for the various physical properties such as liquid limit and plasticity index.

Experimental results of Examples 1 to 5 and Comparative Examples 1 and 2 are shown in Tables 2 and 3 below, and the experiment was carried out after 28 days of laying the fill material on site.

[Table 2] Physical performance test results

Test Type Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 Liquid limit NP * NP NP NP NP NP NP Plasticity index NP NP NP NP NP NP NP Modified CBR 69 86 83 86 92 78 32 Permeability coefficient (cm / sec) 1.171 × 10 ^-2 1.367 × 10 ^-2 1.359 × 10 ^-2 1.431 × 10 ^-2 1.431 × 10 ^-2 1.231 × 10 ^-2 1.345 × 10 ^-2 stability(%) 16.2 11.9 12.4 13.4 10.9 13.8 19.4 Wear rate (%) 31.2 30.2 32.4 31.6 29.2 32.1 39.6 Sand equivalent (%) 54.2 53.4 51.8 61.6 54.2 58.4 59.2

NP: Non-Plastic

As confirmed in Table 2, in Examples 1 to 5 and Comparative Examples 1 and 2, the soil material permeability coefficient of 1.0 × 10 ^-2 cm / sec in the construction specifications was satisfied, and the liquid limit and the plasticity index were natural. Soil material and artificial soil material showed good values so that the numerical values could not be measured, which satisfies the liquid material limit and the plasticity index of 20 or less in the construction specifications.

In addition, the modified CBR, which means the target value of the strength of the roadbed material in the field, was excellent in showing the same value or higher than that of Comparative Example 1 composed of natural soil in Examples 1 to 5, whereas the waste was simply physically replaced with natural soil. One comparative example 2 showed a very low value compared to the example.

In the case of Examples 1 to 5, the slag powder, phosphate gypsum and bypass dust generate hydrate to prevent the decrease in strength due to the mixing of mud sludge, waste foundry sand, and construction wastes, which are used as soil substitutes. Compared to the case, the performance could be improved, but the comparative example 2 in which the physical replacement of the wastes with the natural soil without the use thereof was greatly reduced because of high grain strength.

In the wear rate showing the strength of the material, all of the examples except Comparative Example 2 showed good results compared to the natural soil material. These results directly affect the stability results, which can be confirmed from the similarity between the stability and the wear rate.

In addition, in the sand equivalent which shows the ratio of sand and clay, it showed better than the natural soil material in Example 4 which does not use mud sludge. This far exceeds the sand equivalent of 25 or more in the construction specifications. In other words, all of the embodiments of the present invention appear to satisfy the landfill material property standards in the construction specifications such as modified CBR and permeability coefficient, and thus, it is judged that the existing landfill material can sufficiently replace the natural soil material.

[Table 3] Environmental Stability Test Results

Sujin Environmental Conservation Act Standard (mg / ℓ) Inspection items Test result (mg / ℓ) Example 1 Example 2 Example 3 Example 4 Example 5 Comparative Example 1 Comparative Example 2 0.5 to 2.0 Cr KMS 0.052 0.038 0.092 0.056 0.089 0.012 0.124 TCLP 0.101 0.068 0.105 0.096 0.186 0.036 0.612 2.0-10.0 Mn KMS 0.038 0.042 0.126 0.099 0.129 0.123 0.126 TCLP 0.201 0.048 0.169 0.135 0.189 0.096 0.238 2.0-10.0 Fe KMS 0.038 0.012 0.085 0.069 0.099 0.086 0.963 TCLP 1.28 0.89 0.024 0.086 0.1312 0.098 1.234 1.0 to 5.0 Zn KMS 0.024 0.032 0.069 0.078 0.048 0.039 0.096 TCLP 0.098 0.043 0.062 0.096 0.092 0.096 0.335 0.01 to 0.02 CD KMS N.D 0.006 N.D N.D N.D N.D 0.012 TCLP N.D N.D N.D N.D N.D N.D 0.034 0.2 to 1.0 Pb KMS N.D N.D N.D N.D N.D N.D 0.129 TCLP N.D N.D N.D N.D N.D N.D 0.329 0.5 to 3.0 Cu KMS 0.011 N.D 0.019 0.011 0.014 0.009 0.096 TCLP 0.012 0.034 0.023 0.056 0.013 0.025 0.106

As can be seen from the dissolution test results, in the case of Examples 1 to 5, it was shown that the water content of the pollutants presented in the Water Quality Conservation Act was satisfied. Comparative Example 2, which was simply physically substituted, was found to satisfy the domestic dissolution test method, but the US dissolution test method (TCLP) was found to exceed the standard value for some heavy metal items. This means that there is no confidence in the immobilization mechanism of the elution of the hazardous substances if the physical substitution of the wastes for natural soil without chemical bonding force is required .

Claims (4)

a) homogeneously mixing phosphate gypsum and bypass dust in the fine slag powder to obtain a binder; b) mixing at least one selected from the mud sludge, waste foundry sand and construction wastes in the binder material; manufacturing method of environment-friendly landfill material using a large amount of industrial waste, characterized in that it comprises a. According to claim 1, wherein the step a) is the production of eco-friendly soil material using a large amount of industrial waste, characterized in that to obtain a binder by mixing 100 to 300 parts by weight of phosphate gypsum, 20 to 100 parts by weight of bypass dust to 100 parts by weight of the slag fine powder Way. The method of claim 2, wherein the step b) comprises 100 to 1000 parts by weight of one or more selected from mud sludge, waste foundry sand, and construction wastes to 100 parts by weight of the binder. Manufacturing method. Eco-friendly landfill material using a large amount of industrial waste, characterized in that produced by the manufacturing method of any one of claims 1 to 3.