KR100983666B1 - A method of preparing thermal radiation coating material from waste MgO-Cr2O3 brick - Google Patents

Abstract

The present invention mechanically pulverizes the lead with waste magnet; Reacting the waste grinds with an aqueous sulfuric acid solution to prepare a chromite compound having a high Cr ₂ O ₃ content; Provided is a method of preparing a ceramic thermal radiation insulation coating agent having a high thermal radiation rate by mixing the chromate compound, fumed silica and water as a bond dispersant.

Waste macrorefractories, heat radiation. Chrome Ore, Fireproof Paint

Description

A method of preparing thermal radiation coating material from waste MgO-Cr2O3 brick}

The present invention relates to a method for producing a ceramic thermal radiation insulation coating agent from waste macro lead, more specifically, ceramic heat radiation with high thermal radiation rate using the magnesium lead and waste which are discarded after use in steel, cement, and glass industries. The present invention relates to a method for producing an insulation coating agent.

Recently, heat radiation insulation coating agent is mainly used to reduce heat energy in domestic and foreign industrial sites using industrial urinary tracts. Chromite (FeCr ₂ O ₄ ; emissivity 0.95), a material that is mainly spotlighted as a conventional thermal radiation insulation coating agent, is not present in nature as a single compound and is mainly included in chromite produced mainly in nature. In order to take advantage of such high thermal radiation characteristics of chromite, Japanese Patent Laid-Open No. 63-29712 employs natural chromium light containing a small amount of these chromite components as a main radiant filler of a radiation insulating material. However, this method has a disadvantage in that the Japanese patent method that adopts only expensive natural chromium ore as the main raw material is expensive and the economical efficiency of the refractory paint.

Recently, in Korea, chromium-containing wastes containing chromium-based oxides have been selectively collected through crushing flotation, which contains a large amount of chromium, and the mixture is added to natural chromium. It is described that the radiation coating material can be prepared (Korean Patent Publication No. 2002-58174).

However, the above method uses a method of adding a pulverized product obtained through simple grinding and flotation from waste chrome to natural chromium ore for the purpose of cost reduction. The removal method of chromium component from waste macro lead is based on the extraction of high concentration of chromium compound through flotation by using specific gravity difference between waste lead and the compound component in the pulverized product. This is because most of the chromium components in the wort are not separated from the magnesia, which is the main wort, by the process. Therefore, floating beneficiation of these chromium-rich compound phases is not technically feasible, and in fact, such a flotation facility requires large-scale facilities. Rather than employing it is less economical.

The present invention is a method for obtaining a low-cost chromite compound in order to solve the above problems, to obtain a low-cost chromite-containing raw material more economically and technically from waste magnesia lead, and obtained chromite compound It is to provide a method for producing a ceramic thermal radiation insulation coating agent having a high thermal radiation rate.

In order to achieve the above object, the present invention is to mechanically pulverize the lead with a waste magnet; Reacting the waste grinds with an aqueous sulfuric acid solution to prepare a chromite compound having a high Cr ₂ O ₃ content; Provided is a method of preparing a ceramic thermal radiation insulation coating agent having a high thermal radiation rate by mixing the chromate compound, fumed silica and water as a bond dispersant.

Hereinafter, the present invention will be described in more detail.

First, MgO-Cr ₂ O _{3 having} a Cr ₂ O ₃ content of 10 to 30% by weight, preferably 20 to 30% by weight, in order to prepare a chromite compound containing a high concentration of Cr ₂ O ₃ from waste Mg The waste scrap is made into fine powder through mechanical grinding. The size of the ground fine powder of the waste refractories is not limited, but a fine powder of 200 # or less is most suitable.

The obtained fine powder is reacted with an aqueous sulfuric acid solution to remove the MgO component present in excess in the spent lead in the form of MgSO ₄ (liquid). When the waste lead and fine powder are added and stirred in an aqueous sulfuric acid solution having a concentration of 10% or more, the temperature of the reaction solution rapidly increases and the reaction proceeds at a violent rate. In this case, the main reaction that occurs mainly in the solution is that the free MgO component, which is present in excess in waste smoke and in the chromium compound and does not form a compound, reacts with sulfuric acid.

Free MgO + H ₂ SO ₄ = MgSO ₄ (Liquid) + H ₂ ↑

The reaction is continued until the free MgO in the waste smoke and the pulverized product is completely consumed, and the completion point of the reaction is when the temperature of the reaction system falls back to room temperature. After the reaction, the solution is present in the form of an aqueous solution containing excess MgSO ₄ and unreacted (solid powder). When cooling is completed, an unreacted mineral having a high Cr ₂ O ₃ content can be easily recovered through an industrial filtering process. Can be.

The concentration of sulfuric acid solution used in the sulfuric acid reaction is 2 to 90%, preferably 10 to 90% sulfuric acid solution can be used, but considering the reaction rate and safety 20 to 50% sulfuric acid solution is optimal.

The unreacted material remaining after the sulfuric acid reaction is washed with water and dried to prepare a chromite (FeCr ₂ O ₄ ) compound having a relatively high Cr ₂ O ₃ content compared with the waste smoke before the sulfuric acid reaction. The chromite compound comprises 35-55 wt% Cr ₂ O ₃ , which is equivalent to or similar to the Cr ₂ O ₃ content of commercially available natural chromium ores. Chromite compounds have a high efficiency of radiation and are therefore a major raw material for thermal radiation insulation coatings.

The high-purity chromite compound obtained by the above method has an average particle size of 10-20 micrometers, which is lower than the particle size of the waste smoke and powder before sulfuric acid reaction, and thus no additional grinding process is required. A ceramic heat radiation insulation coating agent having high heat radiation rate is prepared by mixing / stirring fumed silica and water, which may simultaneously act as a binder and a dispersant, to the chromite compound. The fumed silica is used in an amount of less than 2% by weight, preferably 0.1 to 1.0% by weight based on the total amount of the heat-insulating coating agent in solution.

The fumed silica acts as a dispersant in the paint at room temperature and high temperature, and a bond dispersant between the paint and the refractory, and preferably has a mean particle size of 7 to 100 nm, preferably 7 to 50 nm. The water is used in an amount of 20 to 50% by weight, preferably 28 to 48% by weight with respect to the insulating coating agent. The chromite compound is used so that the content of the insulating coating agent is 100% by weight except for the fumed silica and water. The stirring can be carried out using a conventional stirrer, the stirring time is carried out for 24 hours or more. The paint having the stirring process is in a state where the chromite compound and the ultra fine fumed silica particles are mixed and dispersed homogeneously.

In addition, a small amount of natural chromium light having a chromium content of 40 to 56% by weight may be additionally added to the insulation coating agent. Preferably, natural chromium light may be added in an amount of 5 to 50 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the heat insulating coating agent.

Natural chromium light is preferably added in a fine powder state of 200 # or less. Natural chromium light is MgO components present in the surface of the chromium fine powder is dissolved in water to increase the pH of the heat insulating coating composition up to 12 or more. These high pH conditions correspond to the optimal dispersion pH of fumed silica, which has been added to the chromite compound and additives as a dispersing binder, to aid in homogeneous dispersion of the coating and also to increase the solubility of the fumed silica, thereby allowing the dissolved silicate hydrate to be relatively Even small amounts of additives are placed close to the chromite compound and improve the bonding strength between the coating particles at room temperature and at high temperature after application of the insulation coating agent and between the coating agent and the refractory material. The reactivity of the natural chromium in water and the behavior of fumed silica at high pH are associated with a relatively long stirring time of 24 hours.

The heat-insulating coating prepared according to the present invention has excellent coating workability and bonding property of the paint at high temperature, and is applied to the inner wall refractory of an industrial urinary furnace operated at a high temperature of 700 ° C. or higher to provide a heat-resistant and heat-resistant insulating coating material. Can be used.

The following presents a preferred embodiment to aid the understanding of the present invention. However, the following examples are provided only to more easily understand the present invention, and the present invention is not limited to the following examples.

Example 1

Waste Magnesium Lead and 2 kinds (RDB-63F, RDB-71C) with Cr ₂ O ₃ content of 10 ~ 30% by weight are mechanically pulverized to below 200 # powder and 100g of each powder is 50% sulfuric acid solution Each beaker was put in a 1 liter beaker was mechanically stirred. As the stirring started, the temperature of the spent smoke and sulfuric acid solution in the beaker rapidly increased to reach 90 ° C. or more within 10 minutes. As a result of continuous stirring for 1 hour in this state, the reaction between the waste smoke and the fine powder and sulfuric acid aqueous solution was completed and the temperature of the aqueous solution in the beaker began to drop and reached room temperature within 2 hours to confirm that the reaction was completed. After stopping the stirring and maintaining the aqueous solution in each beaker for more than 2 hours to induce spontaneous sedimentation of the suspended unreacted residues, the precipitated unreacted material was collected using a filter. The collected unreacted material was removed with residual sulfuric acid through three washing processes and placed in a 110 ° C. dryer for 24 hours to obtain an unreacted powder from which moisture was completely removed. XRD analysis of these two unreacted residues showed typical FeCr ₂ O ₄ crystalline phases of the _two unreacted materials, and the results using XRF for these chemical components are shown in Table 1.

[Table 1] Changes in components before and after sulfuric acid reaction with spent smoke

(Unit: weight%)

ingredient
Yeonwa type MgO Cr ₂ O ₃ Al ₂ O ₃ Fe ₂ O ₃ CaO SiO ₂ RDB-63F (closed) 64.06 24.08 4.70 6.13 0.54 0.50 RDB-63F (Sulfate Reactant) 21.20 54.60 10.54 11.88 0.57 1.21 RDB-71C (closed smoke) 63.33 22.54 4.62 7.84 0.88 1.29 RDB-71C (Sulfate Reactant) 20.32 49.82 13.11 14.52 0.32 1.91

As shown in Table 1, the amount of MgO, which is the main lead and component of the two types of waste macro lead, significantly decreased before and after the sulfuric acid reaction, and thus the content of Cr ₂ O ₃ was more than doubled to reach up to 54.6 wt%. It can be seen that. Therefore, it can be seen that sulfuric acid reaction is very efficient for obtaining a high Cr ₂ O ₃ chromite compound from the waste smoke.

Based on the experimental data obtained in Table 1 was prepared a thermal insulation thermal insulation coating agent. First, 50 g of fumed silica powder having a particle size of 40 nm was weighed and mixed with 6000 g of residue (Cr ₂ O ₃ content 49%) after sulfuric acid reaction obtained from RDB-71C waste smoke, and then 3950 g of water was added and 500rpm per minute using a strong stirrer. Stirred at a rate of 24 hours. The paint mixture after stirring was homogeneous, and there was no separation between the chromite compound and the fumed silica. The well mixed paint was applied to the alumina plate, and then maintained at 1200 ° C for 10 hours to naturally cool to prepare a radiation insulating coating agent coated specimen. After the heat treatment, the coated specimen was well adhered without cracks on the coated surface, and it was found that the adhesion was excellent even with the addition of a small amount of binder. The radiation efficiency of the coating agent prepared using the chromite compound obtained by the sulfuric acid reaction from waste smoke was shown as the result of measuring the radiation efficiency at 300 ℃ using the radiation tester. This excellence could be confirmed.

Example 2

As shown in Table 1 of Example 1, using a chromite compound (Cr ₂ O ₃ content: about 55% by weight) obtained through the sulfuric acid reaction from the RDB-63F waste smoke and the radiation insulation coating agent in the same manner as in Example 1 Prepared. However, in this case, the chromium content of 46% by weight of natural chromium ore was pulverized to 200 # or less, 10 parts by weight were added to 100 parts by weight of the paint, and then stirred for 12 hours. As a result of the addition of natural chromium ore, a sharp increase in pH of the paint solution was observed, and the pH of the paint solution reached 12 or more within 1 hour after the stirring was started. As a result of measuring the thermal radiation performance under the same conditions after preparing the coating material with the thermal radiation coating agent in the same manner as in Example 1, it was confirmed that the total emissivity was excellent as the total emissivity was 0.86.

The present invention obtains a chromite (Fe ₂ SO ₄ ) nitrite compound having a high efficiency of radiation using waste magnesia waste that is a general waste, and by using the compound to prepare a radiation insulation coating, high efficiency radiation material and radiation insulation coating agent It is possible to provide an economical manufacturing method of the present invention and to obtain the additional effect of improving the recyclability of waste refractory materials. By employing the radiation insulation coating agent of the present invention in the industrial furnace of the industrial site, it is possible to induce an improvement in the industrial competitiveness by improving the thermal efficiency.

Claims (7)

Mechanically pulverizing the lead with the waste magnet; Reacting the waste grinds with an aqueous sulfuric acid solution to prepare a chromite compound containing Cr ₂ O ₃ ; A method of manufacturing a ceramic thermal radiation insulating coating by mixing the chromate compound, fumed silica and water as a bond dispersant. The method of claim 1, wherein the pulverized powder is a fine powder of 200 # or less and the sulfuric acid aqueous solution is a 2 to 90% aqueous sulfuric acid solution. The method of claim 1, wherein the fumed silica is used in an amount less than 2% by weight based on the insulating coating and the water is used in an amount of 20 to 50% by weight based on the insulating coating. The method of claim 1, wherein the fumed silica has an average particle diameter of 7 to 100 nm. The method of claim 1, wherein the thermal insulation coating agent further comprises 5 to 50 parts by weight of natural chromium light based on 100 parts by weight of the thermal insulation coating agent. The method of claim 5, wherein the natural chromium light has a fine powder of 200 # or less. The method of claim 1, The chromite compound is a method for producing a ceramic heat radiation insulating coating containing 35 to 55% by weight of Cr ₂ O ₃ .