JP2022116475A - Slag hue control device and method - Google Patents

Abstract

A black slag obtained by melting waste or incineration ash is made green or brown to widen its range of use in various applications. SOLUTION: The above problems are solved by a melting furnace that melts waste or incinerated ash to generate slag, an analysis means that analyzes the components of the slag generated in the melting furnace, and a Based on the analysis results, the additive selection means for selecting additives for making the slag a desired hue, the slag generated and discharged from the melting furnace, and the additive selection means. Solved by a slag hue control device comprising a mixing furnace for melting and mixing an additive to generate a modified slag and a cooling means for receiving and cooling the modified slag generated in the mixing furnace, and a hue control method be done. [Selection diagram] Fig. 1

Description

The present invention relates to an apparatus and method for controlling the hue of slag produced after melting municipal solid waste and incineration ash.

Conventionally, effective utilization of slag produced after melting general waste and incineration ash in a melting furnace has been made. This slag generally exhibits a black color, and is used as civil engineering materials, construction materials, and roadbed materials after undergoing a certain treatment for each application.

As a conventional example, for example, Patent Document 1 discloses an invention relating to a slag reforming method for supplying slag obtained by melting and solidifying waste as a civil engineering and construction material. According to this invention, the slag surface is eroded by immersing the slag in the molten calcium chloride, and the particle shape, surface properties, and blackness can be improved at the same time, so that the slag can be used as a civil engineering and construction material. A possible slag is obtained.

Further, Patent Document 2 discloses an invention relating to a method for coloring molten slag, which enables recycling of molten slag. According to the present invention, 1 to 10% by weight of titanium oxide is added to molten ash slag and melted in the presence of metal carbide or graphite, thereby coloring the molten slag golden and reusing the molten slag. can do.

JP-A-10-101383 JP-A-8-259281

Akira Yamaguchi: “Coloring of Glass” Shikizai, 52, 11 p.642-649, 1979

However, the invention disclosed in Patent Document 1 has a problem that the process for improving the blackness of the slag becomes complicated. Moreover, in the invention disclosed in Patent Document 2, there is a problem that the molten slag can only be colored in golden color. SUMMARY OF THE INVENTION It is an object of the present invention to provide a slag hue control apparatus and a slag hue control method that can easily control the hue to another hue.

The inventors of the present invention have been researching the effective use of slag from incinerated residue, and happened to come across green slag, which they thought had an elegant color and high commercial value. Therefore, iron oxide was considered as an additive to make it green, and from the properties of colored glass, it was thought that if it was made of divalent iron, it would be green, and if it was made of trivalent iron, it would be brown. As an example of the description of the properties, for example, Non-Patent Document 1 describes that Fe ²⁺ imparts a blue tint to the glass and Fe ³⁺ imparts a yellowish brown color to the glass as iron ion coloring. Since the equilibrium of divalent iron and trivalent iron in the slag is related to the atmosphere and basicity, when the partial pressure of oxygen decreases and the reducibility increases and the basicity increases, iron ions are reduced to 3. I thought it would change from valence to 2 valence. Therefore, when iron oxide is added to the slag, and the basicity is adjusted and the atmosphere is adjusted to be either oxidizing or reducing, the molten slag becomes green. It was found that a brown color was obtained regardless of basicity.

The present invention has been made based on such knowledge, and includes a melting furnace that melts waste or incinerated ash to generate slag, an analysis means that analyzes the components of the slag generated in the melting furnace, Based on the analysis results analyzed by the analysis means, additive selection means for selecting additives for making the slag a desired hue, the slag generated and discharged from the melting furnace, and the addition A slag hue control device comprising: a mixing furnace for melting and mixing an additive selected by an agent selecting means to generate a modified slag; and a cooling means for receiving and cooling the modified slag generated in the mixing furnace. Then, the waste or incineration ash is melted to generate slag, the components of the slag are analyzed, and based on the analysis results, additives are selected to make the slag the desired hue. The present invention provides a method for controlling the hue of slag, characterized in that the added additive is mixed with the slag and melted in an oxidizing or reducing atmosphere to modify the hue of the slag.

According to the present invention, the conventionally black slag obtained by incinerating waste and melting the residue can be changed to green or brown by a simple means to increase the commercial value and expand the range of use to reduce waste. Incineration residue can be effectively used.

It is a block diagram showing an example of hue control of the present invention. 4 is a photograph of slag obtained with the hue control of the present invention; 4 is a photograph of slag obtained with the hue control of the present invention;

The slag whose hue is controlled by the present invention is produced by melting waste or incineration ash. Regardless of the type of waste, for example, cut plants, waste materials from houses, industrial waste such as waste plastic, food processing waste, kitchen garbage, waste plastic, municipal waste mixed with plants, etc. be

The melting furnace for melting waste or incinerated ash to produce slag may be any furnace that is generally used for melting slag. Furnaces such as gasification melting furnaces and gasification reforming furnaces are used. In the case of incineration ash, which is incineration residue such as bottom ash and fly ash left after incineration in other furnaces, and non-combustible waste, there is an ash melting furnace. Furnace types classified into type (burner type ash melting furnace, coke bed type ash melting furnace) and electric type (electric resistance type ash melting furnace, plasma type ash melting furnace) are used.

Color control of the slag of the present invention is achieved by using iron oxide to make it green or brown. Therefore, iron oxide is added when the iron oxide content of the slag is insufficient. However, iron oxide containing a large amount of sulfur and phosphorus is not preferable. The iron oxide may be divalent or trivalent, and the iron oxide may be scale (divalent) produced in a rolling mill. The content of iron oxide is 0.1% by mass or more and is added up to about 10% by mass in terms of Fe ₂ O ₃ . Although there is no particular difference in color depending on the amount added, if the amount is less than 0.1% by mass, the color becomes unclear. If the amount of iron oxide added is too large, energy for melting is wasted, so about 1% by mass is sufficient.
In the molten state with added iron oxide,

の反応が成立していると考えられる。

It is considered that the reaction of

When the color is to be green, the basicity (weight ratio of CaO/SiO ₂ ) is 1 or more and the atmosphere is made a reducing atmosphere. It is thought that increasing the basicity increases the chemical energy of the oxygen ions of Formula 1, so that the reaction of Formula 1 proceeds leftward and the number of divalent iron ions increases. In addition, it is considered that the oxygen partial pressure decreases when the atmosphere is reduced, so that the reaction of Formula 1 proceeds leftward and the amount of divalent iron ions also increases. The green color of the slag tends to become darker when the basicity is increased or the atmosphere is reduced. Since the reaction of Equation 1 is a reaction at high temperatures, it is believed that equilibrium will be reached quickly enough.

On the other hand, when making the color brown, if the atmosphere is an oxidizing atmosphere, the color will be brown regardless of the basicity. Since the oxygen partial pressure increases in an oxidizing atmosphere, the reaction of Formula 1 proceeds rightward, and it is thought that the amount of trivalent iron ions also increases. In an oxidizing atmosphere, the brown color of slag tends to become darker.

In addition, when the basicity is decreased, the chemical energy of the oxygen ion in Formula 1 decreases, so the reaction in Formula 1 proceeds to the right, and it was thought that the amount of trivalent iron ions would increase, but no clear difference was observed. rice field.

The basicity is adjusted by adding a basicity adjuster, but when increasing the basicity, calcium and magnesium compounds such as calcium oxide, calcium hydroxide, calcium carbonate, and complex salts of magnesium oxide and magnesium carbonate are added. Add. Among calcium compounds, for example, calcium chloride is not preferable because it deliquesces the slag. On the other hand, when lowering the basicity, silicon dioxide is added. Silicon dioxide can be added in the form of silica stone, soil, or the like.

Means for making the atmosphere oxidizing or reducing are usually by making the entire atmosphere oxidizing or reducing by the presence of an oxidizing gas or a reducing gas in an air-based atmosphere. Practically, oxygen gas is used as the oxidizing gas, and carbon monoxide gas is used as the reducing gas. In the case of a reducing atmosphere, the oxygen gas partial pressure is set to 0.1 atm or less, preferably 10 ^-3 atm or less. is used as is.

In order to control the hue of the slag produced in the melting furnace, the components are first analyzed. In the present invention, since the hue is controlled by the iron oxide contained in the slag and the basicity (weight ratio of CaO/SiO ₂ ), the components are analyzed. Fluorescent X-ray analysis or the like can be used as analysis means.

Next, based on the results of this component analysis, additives are selected to give the slag a desired hue. In order to bring hue-controlled slag to the market, it is necessary to be able to supply slag of the same quality. do. Therefore, the amount of iron oxide to be added is determined so that the content of iron oxide (for example, Fe ₂ O ₃ , FeO, etc.) in the slag is within the set value range. Then, the amount of lime or silicon dioxide to be added is determined so that the basicity is within the range of the set value.

Since the additive selection means is a means for performing these, iron oxide input amount determination means, weighing means and supply means, lime or silica stone selection means and input amount determination means according to slag basicity, weighing means It consists of supply means and the like.

After the selection of the additive and the amount to be added are determined, the additive is added to the slag generated in the melting furnace. Iron oxide is usually powdered, but can also be added as a solution or slurry. At this time, since the slag has been discharged from the melting furnace, the slag is put into a mixing furnace and melted, and the additives specified above are added to modify the hue.

The mixing furnace may be any furnace capable of melting slag, and electric furnaces, induction heating furnaces, plasma melting furnaces, and the like are also used. Since these furnaces can change the atmosphere to either an oxidizing atmosphere or a reducing atmosphere, as a general rule those with a closed structure are used. However, the additive can be added without removing the slag from the melting furnace that generated the slag, in which case the melting furnace that generated the slag also serves as the mixing furnace.

The additive may be added before or after the slag is melted, and may be added at once, continuously, or intermittently.

The heating temperature in the mixing furnace may be about 1100 to 1500° C., as long as the slag can be melted, and the heating time is about 3 minutes to 30 hours, which is enough to substantially complete the color change.

The modified slag that has undergone color modification in the mixing furnace is taken out and cooled.

Various cooling means can be selected according to the shape of the slag, and either water cooling or air cooling may be used, but water cooling is usually used in view of crushing and operational efficiency. As an apparatus, a water granulator, a slow cooling apparatus (pan cooling), a twin roll apparatus, or the like can be used.

If necessary, the modified slag cooled by the cooling means is provided with a hue measuring means for measuring its hue. This hue measuring means confirms whether the obtained modified slag has a predetermined hue, and measures the absorption spectrum of the slag in the visible light region using a visible spectrometer, A simple visual judgment or the like is used.

If the hue measuring means does not indicate that the modified slag has a predetermined hue, the hue of the modified slag is readjusted. As a means for readjusting the hue, if the amount is small, it is desirable to put it back into the mixing furnace to change the hue, but if the amount is large, put it back into the original melting furnace and melt it.

An example of slag hue control according to the present invention is shown in FIG. As shown in the figure, waste or incinerated ash is melted in an ash melting furnace to generate slag, the components of the slag are analyzed, and the additive iron oxide and basicity are adjusted to achieve the desired hue. Calculate the amount of the agent to be added, add it to the mixing furnace and mix and melt it with the slag, remove the slag from the mixing furnace and cool it with a cooling device, measure the hue, and store it if it has the predetermined hue. Store in yard.

Incinerated ash, mainly composed of plants, was heated to 1300° C. in an electric furnace and melted, and then put into water and rapidly cooled to obtain three kinds of samples of greenish black, black, and green.
Table 1 shows the results of analyzing these three types of samples with a fluorescent X-ray analyzer.

All three samples are a mixture of light grass-colored and black-brown particles, the green-black sample contains a considerable amount of all particles, the black sample contains many black-brown particles, and the green sample contains most of the particles. The particles were pale grass color.

5 g of each particle was placed in an alumina crucible and a carbon crucible, held at 1300° C. in an air atmosphere for 30 minutes, and then placed in water together with the crucible for quenching.

A photograph of each obtained slag taken with a ×50 microscope is shown in FIG. All the slags melted in the oxidizing atmosphere of the alumina crucible turned brown, while all the slags melted in the reducing atmosphere of the carbon crucible turned green.

Incinerated ash discharged from a municipal waste incineration facility was heated to 1,300° C. in an electric furnace to melt it, and then it was quenched by putting it into water to obtain black slag. When this slag was analyzed by a fluorescent X-ray spectrometer, it was found to be 2.02 wt% CaO, 43.26 wt% _SiO2 , 15.79 wt% _{Al2O3 , 0} wt% _Fe2O3 , and a basicity of 0.50. Met.

Slaked lime was added to this black slag to adjust the basicity to 1 or 1.2, and 1.5% by weight of Fe ₂ O ₃ (exclusive value for the sum of slag and slaked lime) was added.

In this way, three types of slag with basicities of 0.5, 1, and 1.2 were prepared, and 5 g of each was placed in an alumina crucible in an oxidizing atmosphere and in a carbon crucible in a reducing atmosphere, and each was placed in the atmosphere at 1300 After holding at ℃ for 30 minutes, the whole crucible was immersed in water and quenched.

A photograph of each obtained slag taken with a ×50 microscope is shown in FIG. The slag melted in the oxidizing atmosphere of the alumina crucible turned brown regardless of the basicity. The slag melted in the reducing atmosphere of the carbon crucible remained colorless when the basicity was 0.5, but changed to green when the basicity was 1 or more.

The slag whose hue is controlled by the present invention has elegant green and brown colors and is highly favored, so it can be used for civil engineering materials, construction materials, and roadbed materials. can also be used for

Claims (4)

a melting furnace for melting waste or incineration ash to produce slag;
analysis means for analyzing components of the slag produced in the melting furnace;
Additive selection means for selecting an additive for making the slag a desired hue based on the analysis result analyzed by the analysis means;
a mixing furnace for melting and mixing the slag generated and discharged from the melting furnace and the additive selected by the additive selecting means to generate a modified slag;
cooling means for receiving and cooling the reformed slag produced in the mixing furnace;
Slag hue control device with 2. A slag hue control apparatus according to claim 1, further comprising hue measuring means for measuring the hue of said modified slag cooled by said cooling means. 3. The slag hue control device according to claim 1, further comprising hue readjustment means for readjusting the hue of the modified slag when the modified slag does not have a desired hue. Waste or incineration ash is melted to generate slag, the components of the slag are analyzed, and based on the analysis results, additives are selected to make the slag the desired hue. A method for controlling the hue of slag, comprising mixing an additive into the slag and melting the slag in an oxidizing or reducing atmosphere to modify the hue of the slag.

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