JPS58225187A - Manufacture of formed coke - Google Patents

Abstract

PURPOSE:To effectively obtain a formed coke without deformation, fusing and/or degradation, by adding, as a binder, a PVA-aqueous solution to a coal, carrying out forming under pressure followed by dry distillation, and by utilizing the heat of combustion of the combustible gas generated for the formed coal drying and the sensible heat of the resulting exhaust gas for PVA dissolving, respectively. CONSTITUTION:A feedstock coal A is fed to a crusher 1 to make a pulverized coal. Various grades of coal are blended in a blender 2 followed by kneading in a kneader 4 together with a binder prepared by mixing polyvingl alcohol (PVA) B with water C to make a PVA aqueous solution. The resulting mixture is fed to a press 5 to carry out a forming under pressure to make it into a formed coal, which is then dried in a dryer 6 followed by dry distillation in an inner heat-type furnace 7, thus obtaining the final formed coke D. In this process, part of a combustible gas generated during the dry distillation is subjected to combustion to utilize it for a drying heat source for the formed coal, while the sensible heat of the exhaust gas generated by combustion during the drying process is used as a heat source for dissolving the PVA B in the water C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an industrially advantageous method for manufacturing high-quality molded wood.

Normally, when producing shaped coke, various binders as binders are added and mixed to raw coal in advance, and molded under pressure to produce shaped coal, and then the shaped coal is loaded into a carbonization furnace. The method is to obtain molded coke by carbonizing the coke.

Therefore, during the carbonization process, briquette coal acquires a temperature history from room temperature (2) to 1000℃ and becomes molten coke, and the shape of briquette coal must be maintained as it is during that time. Therefore, one of the important roles of the binder is to increase the temperature from room temperature to the softening and melting temperature of coal (approximately 350℃~
The purpose is to maintain the shape of the briquettes when they are charged until the temperature reaches 400°C, and to prevent them from melting together or collapsing.

Incidentally, in the past, coal-based pitch was used as a binder when manufacturing such molded coke because of its excellent affinity with coking coal, but in recent years, petroleum-based pitch has been used. Asphalt also came into use.

However, the quantity of the former pitch is not sufficient to produce only the pinch obtained from the cool by-product during molded coke production, and it must be replenished with pitch obtained from other production equipment, such as coal carbonization in a horizontal coke oven. Despite the fact that this kind of pinch is in demand as a useful i-material in other industrial fields, it is always in short supply as a raw material for molded coke production (3 ) Karika, the pinch contains harmful substances,
There are disadvantages such as an inconvenient working environment.

In addition, since the latter is an organic compound mainly composed of straight hydrocarbons, it has poor affinity with coal, which is an aggregate of aromatic compounds, and when used as a binder, The disadvantage is that the strength of the briquette coal when heated is extremely low, and the briquette coal deforms, fuses, collapses, etc. during carbonization.

Furthermore, since both of the above materials have high softening points, when mixing them with coking coal, it is necessary to heat the binder made of pitch or asphalt above its softening point in advance, and a heat source for this purpose must be prepared. This has the drawback of being extremely uneconomical in terms of operation.

Recently, attention has been paid to organic polymer compounds whose aqueous solutions are liquid at room temperature and which do not lose their bonding strength even at high temperatures, and proposals have begun to be made to use them as binders in the production of metallurgical molded coke. . Although such high-molecular organic compounds were used on a small scale in the past as binders for household use and as binders in the production of charcoal briquettes, they have not been used on a large scale in the production of metallurgical molded coke. At present, there are still many problems to be solved regarding its use as a binder.

The purpose of the present invention is to provide a method for economically producing high-quality metallurgical molded coke in large quantities using a binder made of a specific high-molecular organic compound. polyvinyl alcohol (including modified polyvinyl alcohol, below-1) is added to raw coal as a binder.
The same) is added in the form of an aqueous solution and kneaded, and the resulting briquette coal is dried and carbonized in an internal heating carbonization furnace to obtain shaped coke. combust to use as a heat source for drying the briquette charcoal,
The method of producing molded coke is characterized in that the sensible heat of the combustion exhaust gas during drying is used as a heat source for melting the polyvinyl alcohol into water.

In the present invention, the polyvinyl alcohol used as a binder not only exhibits a good (5) bonding force to briquette charcoal at room temperature, but also exhibits a high bonding force (5) to the briquette charcoal during the carbonization process of the briquette. When heated, it quickly thermally decomposes and loses its carbonization behavior, so it still retains its binding strength.

Therefore, briquette coal does not undergo deformation, fusion, collapse, etc. during carbonization.

Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 is a process diagram showing steps for carrying out the present invention.

First, raw coal (A) consisting of various brands is supplied to a pulverizer (11) for each brand or similar brands, and is pulverized to a predetermined particle size.

Each of the pulverized raw material coals is once supplied to a blending tank (2) consisting of a large number of hoppers arranged in parallel, and then thrown into a predetermined tank depending on the brand. The raw coal of each brand put into the blending tank (2) is cut out from the bottom onto a conveyor heald according to a preset blending ratio, and then merged to form a blended coal and sent to the kneader (4). Supplied.

Normally, when coke for metallurgy is carbonized in a horizontal coke oven using mixed powdered coal, most of the coking coal must be coking coal. Although it uses a type coke oven,
Even in the so-called briquette coal partial blending method, in which pulverized coal is blended with briquettes obtained by molding separately and carbonized, high-quality coke cannot be obtained unless caking coal accounts for 70% or more of the coking coal. . On the other hand, in the so-called molded coke manufacturing method in which the briquette coal obtained is carbonized in a shaft furnace while retaining its shape, the blending ratio of this coking coal is further reduced. As a result, it is expected that the scope of use of coking coal will expand significantly more than ever before, and research on this topic has been extremely active in recent years. Even if the blending ratio of charcoal is set to 30 to 40%, it is possible to produce a 2-liter cox with a quality that can be used for metallurgy.

Therefore, in the present invention, raw coal is divided into two categories: coal on the coking coal side and coal on the non- and/or slightly coking coal side, and in particular, the blending index (7) of the coal on the coking coal side is (×: value of the product of the average reflectance (fly.) of the coal on the coking coal side and the maximum flow rate (log MFD)) must be blended so that it is 4.0 or more.

Usually, the average reflectance (R,) of coking coal shows a value of 1.0 or more, but the maximum fluidity (log MFI)
is small, less than 3.6, and it is difficult for the value of the product to be more than 4.0, so in order to compensate for this, some high fluidity coals such as Miike coal and Yubari coal are used as coking coal. Domestic expanded coking coal is added and blended.

Figure 2 shows the coal on the coking coal side (with other manufacturing conditions being the same).
In this case, the blending ratio of coal on the coking coal side in the total raw material coal was 40%) When the blending index (X) was variously changed,
Drum strength of the resulting molded coke (<: JISK
2151) is a graphical representation of the test results showing what will happen, but it is generally said that unless the drum strength is 78% or more, the coke is for metallurgy and ζ cannot be used. It can be seen from FIG. 2 that the above blending index must be 4.0 or more.

On the other hand, if the coal is on the non- and/or slightly coking coal side, ζ
)(8) is generally weakly coking coal, low-coking coal, anthracite, semi-anthracite,
Any carbon material such as oil coke can be used.
Although there are no particular restrictions on use, it is preferable to use loga with a low number of seeds (Summer So/TC27) and a low volatile content.

On the other hand, water (C) is added to the powdered polyvinyl alcohol (B) as a binder added to raw coal in a melting tank (3) to a predetermined concentration, that is, 10 to 18%.
It is dissolved by the heat of the combustion exhaust gas obtained from the dryer (6), which will be described later, to become an aqueous solution, which is added to the raw coal in the kneader (4).

The amount of polyvinyl alcohol (B) added to the raw coal is preferably 0.5 to 1.5% based on the raw coal.
．． A very small amount of 2% is sufficient. In addition, if this is converted into the form of an aqueous solution, it will be 2.8 to 15% based on the raw material I' charcoal.

The raw coal to which polyvinyl alcohol has been added is thoroughly kneaded in a kneader (4), and then sent to the next step, a molding machine (5), where it is made into briquette coal. .

(9) Molded coal obtained from the molding machine (5) is supplied to the next step, the dryer (6). The dryer (6) is a device that combusts a part of the carbonization gas obtained from the carbonization furnace (7) in the carbonization process to be described later, and uses the combustion heat as a heat source to dry the briquette coal. The temperature (drying temperature) of the atmosphere through which the briquette coal passes through is maintained at 110 to 160°C. If the drying temperature is below 110°C, the drying time will be long and the strength of the final molded coke will be weak, and if it is above 160°C, the molded coal will crack, which is disadvantageous. In addition, the moisture content of the briquette coal after drying should be within the range of 1.3 to 4.5%, preferably 3 to 4%, and even if the moisture content is higher or lower than that, the final The strength of the resulting briquette is reduced.

Figure 3 shows that the concentration of polyvinyl alcohol aqueous solution is 12
．． This is a graph showing the test results showing the relationship between the moisture content of molded coal and the crushing strength of the resulting molded coal when 5% of coke is added to raw coal at 8%. Considering that it is necessary (lO), the appropriate moisture content of briquette coal after drying is 1.3 to 4.5%, preferably 3 to 4%. This can be seen from Figure 3.

The dried briquette discharged from the dryer is then charged into an internal heating type vertical carbonization furnace (7) from the top, and is then charged into the furnace from the bottom or side of the carbonization furnace (7). 900℃ supplied to
It is carbonized using high-temperature gas at ~1100°C and is discharged from the bottom of the furnace as shaped coke (D).

In the carbonization process, the gas generated from the coal briquette is led out from the top of the furnace, and by burning a part of it, most of the other gas is indirectly heated to 900°C to 1100°C. Since it is circulated and supplied as a gas to the carbonization furnace (7), this special surplus gas exhibits a high calorific value equivalent to that of regular coke oven gas, and can be used as a fuel gas. . The carbonized exhaust gas supplied as fuel to the dryer (6) is this surplus gas.

(11) As described above, the present invention uses an aqueous solution of polyvinyl alcohol, which is liquid at room temperature, as a binder for producing briquette charcoal. In addition to the gas obtained from the carbonization furnace and the combustion gas obtained by burning the gas in the drying process and the heating process of the polyvinyl alcohol aqueous solution, the high-temperature gas supplied to the carbonization furnace can be obtained by indirect heating. It is extremely economical as it can be used as a by-product gas and can produce high-quality molded coke, so its industrial value is great.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing each step of the present invention. Figure 2 is a graph showing the relationship between the blending index (X) on the coking coal side and the drum strength (() of the molded coke. Figure 3 is a graph showing the relationship between the moisture content of the molded coal and the crushing strength of the molded coal. It is a graph showing +1) ----・Crusher, (2) -1--Blending tank, +3
1--1 melting tank, +41--A construction, +51. − ＊□
1.6-. U, 1” (12) (7) -- Carbonization furnace (A) -- Coking coal, (Bi-
Polyvinyl alcohol (C) - water (D')
------1 Molded coke applicant Japan Iron and Steel Federation agent Patent attorney Seibu Omen (13) Figure 1 (D)

Claims (5)

[Claims] (1) Add polyvinyl alcohol as a binder in the form of an aqueous solution to the blended raw coal, knead it, dry the briquette obtained after pressure molding, and carbonize it in an internal heating carbonization furnace to produce molded coke. In obtaining the polyvinyl alcohol, a part of the flammable gas generated during carbonization is combusted to serve as a heat source for drying the briquette coal, and the sensible heat of the combustion exhaust gas during the drying is used as a heat source for melting the polyvinyl alcohol into water. A method for producing molded coke characterized by using (2) The blended raw material coal has the highest flow ring (logMFD)
) and average reflectance (f2.) is 30% by weight or more of coal on the coking coal side and 70% by weight of coal on the non- and/or slightly coking coal side, adjusted so that the product value is 4.0 or more. A method for producing molded coke according to claim 1, which is made as follows. (3) Coal 30 on the coking coal side, where the blended raw material coal is adjusted so that the product of the highest flow ring (log(1) MPD) and the average reflectance (Po) is 4.0 or more 40% by weight and 70-60% by weight of coal on the non- and/or slightly coking coal side
A method for producing molded coke according to claim 1. (4) Polyvinyl alcohol is used as a raw material 0 for charcoal
．． The method for producing molded coke according to claim 1, wherein 5 to 1.5% by weight is added. (5) The method for producing molded coke according to claim 1, characterized in that the molded coal is dried so that the moisture content of the molded coal becomes 1.3 to 4.5%.