KR20020020985A - Method for removing Cl components from slag and or dust - Google Patents

Abstract

PURPOSE: A method for removing chlorine from slag and/or dust generated from iron manufacturing is provided to save the cost and recycle used organic solvent by mixing slag and/or dust with organic solvent or mixed solvent of organic solvent and water. CONSTITUTION: The removing method comprises the steps of: dissolving chlorine(Cl) contained in dust and /or slag into an organic solvent or a mixed solvent of 100pts.wt. of organic solvent and 5-50pts.wt. of water, wherein the organic solvent is selected from alcohols, acetones, ethers or hydrocarbons; centrifuging to separate solid from liquid; drying the solid at 60-80deg.C under reduced pressure and recovering residual solvent in the solid. The separated solvent is recycled by distillation under reduced pressure, ion exchange resin method and sedimentation.

Description

Method for removing Cl components from slag and or dust}

The present invention relates to a method for removing Cl components from dust and / or slag, which is a solid waste generated in a steel mill, and more specifically, mixing a dust and / or slag with an organic solvent, or a mixed solvent of an organic solvent and water. Dissolving the Cl component contained in the dust and / or slag; Solid-liquid separation of the dust and / or slag and solvent of the mixture by centrifugation; Recovering the residual solvent at the same time by drying the separated solid component under a reduced pressure at 60-80 ° C .; And removing Cl from the dust and / or slag to remove the Cl to recycle the separated solvent. Dust and slag are by-products from the processing of metals and minerals and are made of a melted mixture of various metal components including Ca, Si, and Al. The slag produced in steel mills in Pohang and Dangjin is more than 6 million tons per year, and a large amount of slag is emitted, and they are mainly used as roadbed, civil aggregate and cement raw materials. The application as a cement raw material is the most important application field. However, when used as cement, if the Cl component is excessively contained over 500ppm, the Cl component corrodes the reinforcing steel in the concrete, making it impossible to use. For example, many of the slag discharged from Pohang and Dangjin steelworks, especially dust slag of electric furnace, contain more than 3000ppm of Cl component. In order to remove Cl from these slag, we can think about how to wash it with water first, but this is a big problem that a huge amount of waste water is generated, and in order to use the wet slag as a cement raw material in the washing process It needs to be dried again, and the energy cost is enormous, and economic problems appear to be another difficulty. Cl contained in the dust and slag discharged from the steel mill will exist mainly in the form of sodium chloride (NaCl) or metal chloride (MCl: M is a metal), and these substances are calcium oxide (CaO) or calcium hydroxide (slag) in slag or dust. Considering the fact that the metathesis reaction proceeded by continuous contact with Ca (OH) 2) and the large amount was converted into calcium chloride (CaCl2), the resultant Cl component in slag or dust was mostly calcium chloride, sodium chloride, and / or a small amount of It can be said that it exists as a metal chloride compound, and an effective method for removing the substances has not been developed yet.

Accordingly, the inventors of the present invention conducted extensive research and found that the removal of Cl components in dust and slag using an organic solvent such as alcohols or acetones is effective and efficient, and the present invention was based on this. Accordingly, an object of the present invention is to provide a method for effectively removing Cl and dust components from dust and / or slag using an organic solvent or a mixed solvent of organic solvent and water.

The method of the present invention for achieving the above object comprises the steps of dissolving the Cl component contained in the dust and / or slag by mixing the dust and / or slag and the organic solvent, or a mixed solvent of the organic solvent and water; Solid-liquid separation of the dust and / or slag and solvent of the mixture by centrifugation; Recovering the residual solvent at the same time by drying the separated solid component under a reduced pressure at 60-80 ° C .; And removing the Cl component to recycle the separated solvent.

1 is a schematic diagram illustrating a process diagram for removing Cl components from slag and / or dust according to the method of the present invention.

Table 1 shows the experimental solubility of Cl compounds in various solvents.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

First, according to the present invention, the Cl component contained in the dust and / or slag is dissolved by mixing the dust and / or slag with the organic solvent, or a mixed solvent of the organic solvent and water.

Solvents such as acetone in organic solvents are not used to dissolve Cl components, so they are mixed with a small amount of water. Generally, 10 ml of water has the ability to dissolve about 0.1 to 0.4 g of Cl, but when used alone, only a small amount of dust comes into contact with water. The Cl component is dissolved only in the portion where it is used, so that only a very small amount of Cl component is dissolved. However, when water is used together with an organic solvent, water is an extractant of Cl component, and the organic solvent acts as a diluent so that water is in contact with dust and / or slag and extracts Cl component effectively. In addition to these methods, organic solvents such as alcohols are capable of dissolving and extracting Cl components in dust and / or slag even when used alone without being mixed with water, and may be used alone.

The preferred amount of the solvent may vary depending on the type of organic solvent, but generally, 50 to 200 parts by weight of 100 parts by weight of dust and / or slag is used, and water is generated when the organic solvent is mixed with water. It is preferable to use a small amount in consideration of problems such as the above, but it is preferable to use 5 to 50 parts by weight with respect to 100 parts by weight of the organic solvent in consideration of efficiency.

After dissolving Cl component by contacting organic solvent with dust and / or slag, the solid-liquid separation method of dust and / or slag and solvent can be used by centrifugation, simple separation method using manure paper, etc. In this case, the amount of residual solvent is reduced, which is preferable.

In order to obtain dust and / or slag from which the Cl component is recyclable in the present invention, it is preferable to dry the solid component separated in the above process using a vacuum distillation method. In this process, the residual solvent contained in the solid component is Once retrieved, it can be reused.

On the other hand, the solvent separated in the solid-liquid separation process can be separated into a Cl component and a reusable solvent extracted by a vacuum distillation method, an ion exchange resin method, or a layer separation phenomenon between the organic solvent and water. In addition, various methods known to those skilled in the art can be used.

According to a preferred embodiment of the present invention, the solubility of the Cl component in alcohol, acetone, tetrahydrofuran, and 2,4-pentanedione was investigated. Among the alcohols such as ethanol and methanol, Since it shows a very high dissolution rate with respect to calcium chloride, it can be said that it is very suitable for this invention. In addition, in the case of acetone, the amount of Cl dissolved in a single solvent is small, but the amount of dissolved Cl increases by 45 times when water is mixed.

The dissolution amount of Cl in the alcohols and acetones shown above is generally an amount capable of sufficiently and efficiently removing the Cl component in dust and / or slag.

Hereinafter, the present invention will be described in more detail with reference to the following examples, but the scope of the present invention is not limited thereto.

Example 1

10 g of calcium chloride and sodium chloride were added to 100 ml of each organic solvent, and after stirring for 20 minutes, the amount of dissolved calcium chloride and sodium chloride was examined, and the results are shown in Table 1 below.

Table 1 Solubility test results for four solvents, NaCl and CaCl2

Table 1 shows that CaCl2 has a very high solubility in methanol and ethanol, which are relatively polar, but very little or almost insoluble in THF or 2,4-Pentanedione. NaCl was also somewhat soluble in methanol and ethanol, but almost insoluble in THF or 2,4-Pentanedione.

These results show that CaCl2 has a very high solubility in methanol and ethanol, which are relatively polar, but very little or very insoluble in THF or 2,4-Pentanedione. appear. NaCl was also somewhat soluble in methanol and ethanol, but almost insoluble in THF or 2,4-Pentanedione.

The experimental results show that the Cl separation process from dust and / or slag using alcohols can be a very effective process. If the Cl component in the dust and / or slag is mainly NaCl compound due to various incident conditions or the surrounding environment, this process can be sufficiently separated. The amount of Cl contained in the dust and / or slag is about 3000 ppm, so when 1 kg of dust and / or slag is treated as 1 L of methanol, the amount of Cl that 1 L methanol must dissolve is about 0.3 g (100% separation). Only so much less than the solubility shown in Table 1. In the case of acetone, when acetone alone is present, the Cl component is very small (CaCl2 100ml: 0.23g, NaCl 100ml: 0.05g), but a small amount of water is mixed therein and used as a solvent. The amount of Cl component dissolved will increase dramatically. For example, if 90 ml of acetone and 10 ml of water are mixed and used as an extraction solvent for Cl components, the amount of Cl components that can be dissolved therein is extracted from all the Cl components in the dust and / or slag as shown in the table. Appeared in a sufficient amount. This is not only acetone solvents but also organic solvents such as alcohol, the solubility is remarkably increased.

As described above, the method of the present invention can not only efficiently remove Cl components, but also inexpensive to process and can recycle organic solvents, so that there is no problem of environmental pollution.

Claims (4)

Mixing the mixed solvent of dust and / or slag with an organic solvent and water to dissolve the Cl component contained in the dust and / or slag; Solid-liquid separation of the dust and / or slag and the organic solvent of the mixture by centrifugation; Drying the separated solid component under reduced pressure at 60 to 80 ° C., and simultaneously recovering the residual solvent; And Method for removing Cl component from the dust and / or slag comprising the step of separating, removing the Cl component in the solvent to recycle the separated solvent. The dust and / or dust according to claim 1, wherein the solvent is selected from the group consisting of alcohols, acetones, ethers or hydrocarbons (petrol, kerosene, diesel, etc.) and used alone or in combination with water. How to remove Cl from slag Extraction and separation of Cl in dust and / or slag using an organic solvent such as alcohols and acetones or an organic solvent mixed with water, and then an adsorption treatment system, an ion exchange resin system, or an organic solvent in a solvent recovery process for recycling. Method for removing Cl component from dust and / or slag, characterized in that it is one or more selected from the method using layer separation of solvent and water. The method of claim 1, wherein the water is used in an amount of 5 to 50 parts by weight based on 100 parts by weight of the organic solvent when using the mixed solvent.