JPS6012389B2 - Manufacturing method of molded coke for metallurgy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing metallurgical shaped coke using coal as a main raw material, which is unsuitable for producing metallurgical coke by the current room-furnace coke production method.

The main raw material is coal with little viscous streakiness, and this also includes tar,
The process of producing metallurgical shaped coke by carbonization of coal produced by briquetting or pelletizing with the addition of pitch, petroleum asphalt, bentonite, sulfite solutions or other binders is generally well known. This is where I am.

Industrially completed technology already exists for the process of producing agglomerated coal, especially for briquetting, but for the carbonization process, the heating method is direct heating or indirect heating, and the heating medium is gas, sand, coke, etc. Various continuous or batch methods using various combinations of vertical furnaces, rotary furnaces, grates, etc. as carbonization furnaces have been proposed, but no technology has been completed industrially and economically. The current situation is that there is no such thing. In order to maintain high-efficiency operating performance in today's large-scale blast furnaces, molded coke must have a shape and volume that maintains sufficient voids to maintain sufficient ventilation and permeability of gas and melt in the blast furnace. In addition, it must have sufficient wear resistance against reaction with CO2 in the blast furnace and pulverization due to combustion by Q.

In order to produce molded coke for metallurgical use suitable for such purposes by carbonizing lump coal to which a binder has been added, the composition of the raw materials including the binder, the particle size of the raw materials, the density of the lump coal before carbonization, Although it is necessary to select the size appropriately, the heating conditions of the lump coal are particularly important for the quality of the finished product. The present invention was developed as a result of repeated basic research and work research on the relationship between the coking properties and heating conditions of various coals, binders, and agglomerated coal produced by mixing these. They established completely new heating conditions and discovered a carbonization method for producing . When the temperature of coal is increased by heating, dehydration occurs until the coal temperature reaches 100℃.
Coal that is softened and melted or sticky starts to soften and melt at around 300°C, and in the temperature range where the softened and molten state is maintained, expansion, fluidization, detarring, degassing, and bonding actions of coal particles occur, resulting in 500° C. It re-solidifies before and after, producing semi-finished coke.

At this resolidification temperature, a significant volume reduction occurs due to a phase change in which the softened and molten semi-molten coal becomes solid, resulting in the largest shrinkage rate. In the temperature range from after resolidification to 100,000 ℃, the strength increases while gradually contracting mainly due to the dawning reaction of semi-formed coke accompanied by dehydrogenation reaction, but the second peak occurs at the peak of secondary decomposition at a temperature of around 70 and 0. shows the peak of contraction. in this way,
The softening, melting, and shrinking phenomena that occur during the process of heating coal from room temperature to 100 mm and turning it into coke are influenced by the temperature rise speed when heating the coal, and are Expansion and flow phenomena during softening and melting are important factors that regulate the strength of the bond between coal particles and determine coke strength.The faster the heating speed is, the greater the degree of expansion and flow, and the stronger the bond between coal particles. However, the slower the heating speed, the smaller the expansion and flow, and below a certain speed, particles may not be able to bond. Also, the faster the temperature rise speed, the faster the shrinkage rate becomes.
Conversely, if the heating speed is slow, it will become smaller. The coal particle size affects the softening and melting phenomenon of coal, and the larger the coal particle size, the higher the gas pressure in the pores within the particles, which causes the particles to expand and flow more. However, as the particle size becomes finer, the bond between particles becomes weaker due to the opposite orientation. Binder changes when heated depend on the type of binder, but binders such as coal tar, pitch, and petroleum asphalt melt at temperatures above their softening point and decompose at temperatures up to 50°C. It generates gas and turns into coke in the same way as when the remainder is coal, becoming semi-formed coke, and at subsequent temperatures up to 100 and 0, it behaves similar to semi-formed coke mainly composed of coal. These binders also decompose depending on the temperature increase speed,
The state of coking changes, and the farther the heating speed is, the greater the amount of decomposition and the less residual liquid is turned into coke, and the opposite is true when the heating speed is slow. The coking property of lump coal produced by mixing coal and a binder is based on the coking property of each individual substance, especially the coking property of the coal that makes up the majority of lump coal. However, it also has unique properties as lump coal.

The charcoal produced by briquetting and/or pelletizing has a much higher density than pulverized coal, and when it is made into coke, the individual charcoals are not fused together but are fused together. The fact that it needs to be molded coke and that it needs to be in the upper range of 20 to 100 when used as metallurgical coke is closely related to the heating conditions when coking. . In order to maintain the target quality of metallurgical molded coke, which is produced by coking agglomerated coal, the shape of the agglomerated coal before coking is maintained without loss in the product after coking. It is first necessary to have sufficient abrasion strength and concentrated tearing strength, and "maintaining these qualities at the target values is the target value for powderability in the hot state associated with reaction with CQ and combustion by 02. This is a prerequisite for achieving this.In the process of heating agglomerated coal and raising the salt from room temperature to 100 to 0, if the heating speed is too fast in the temperature range below 500qo, the gas pressure in the agglomerated coal will become too high. If the heating speed is too slow, the lump coal will become soft and molten, causing blistering and cracking. The initial shape cannot be maintained and the quality necessary for the final product cannot be maintained.On the other hand, in the temperature range up to 500°C until semi-formed coke is formed, a bonding reaction of coal particles occurs, and depending on the degree of bonding, the temperature range is 1000°C. ℃
The abrasion strength of the product when heated to
The slower the heating speed, the weaker the bonding of particles becomes. In the temperature range up to 50 mm, where the entire lump coal resolidifies and semi-coke is produced, it is necessary to prevent blistering and cracking and strengthen the bonds of coal particles. The temperature rising speed of coal coal must be within a certain range by setting upper and lower limits. Lump coal needs to have an appropriate size, so when it is heated, there will be a temperature difference between the surface and center of the lump coal. When the temperature is 200°C, the overflow speed is in the range of 10 to 40°C/min, and then the overflow speed in the center is slowed down as the temperature of the agglomerated coal increases, and at 600°C, the overflow speed is 10°C/min or less. need to be controlled. In a temperature range where the temperature at the center of agglomerated coal exceeds 500℃, the entire agglomerated coal re-solidifies and becomes semi-formed coke, so the temperature increase speed in this temperature range is due to the formation of cracks due to the contraction of semi-formed coke. It is necessary to decide from the viewpoint of preventing thermal cracking.

The formation of cracks and the occurrence of cracks due to heat shock are closely related to the shrinkage rate of semi-formed coke, and in order to prevent this, it is necessary to raise the temperature to reduce the temperature gradient between the surface and center of semi-formed coke. You have to choose the speed. However, semi-formed coke costs 50,000 to 1,000 oo
As mentioned above, the shrinkage rate changes depending on the temperature, and the thermal conductivity also changes during the time it reaches , so it is necessary to change the heating speed depending on the temperature. In order to prevent the formation of cracks and cracks, it is best to slow down the overflowing speed as much as possible, but if the raising speed is slowed down, the carbonization time will increase, which is undesirable as equipment productivity will decrease and costs will increase. The overflow speed should be set as far as possible within a limit that does not cause such inconvenient problems, and there is an upper limit to the heating speed of lump coal after it has been semi-coked. The upper limit of the streak rising speed when carbonizing semi-formed coke at high temperature to 100°C is 10°C/min at 600°C, and the heating speed is gradually increased as the temperature rises.
The upper limit temperature increase speed at 0 and 0 is 20℃/min.
It is appropriate to do so. When producing molded coke for metallurgy by high-temperature carbonization of Tama coal up to 1000℃, it is necessary to increase the temperature at the above-mentioned temperature depending on the temperature. It is also influenced by its coking property, so by adjusting these two factors, it is possible to produce the required molded coke by heating at the above-mentioned temperature increase rate.

As a heating method to give the necessary temperature rise speed to lump coal, both gas and solid can be used in the case of direct heating using heated soot, and it is also possible to achieve the purpose by indirect heating. . All conventional carbonization furnaces can be used, such as shaping furnaces, mobile grates, and horizontal rotary kilns; however, they require ease of control of heating speed, equipment technology, equipment costs, and operating costs. For these reasons, a vertical furnace using high-temperature gas as a heating medium is desirable. The drawing shows the relationship between the temperature of lump coal and the necessary heating speed. When heating lump coal to 100 mm, the required heating speed shown in the drawing should be It has to be within range.

In that case, the upper limit of the heating rate is as shown in the drawing.When the temperature at the center of the coal is 200°C to 600°C, the upper limit L of the heating rate is T. (object in) = 2.26 volume 2 - 25.57 (high 182.・o When the temperature of the center of lump coal is 600℃, it is 10℃'min, and the temperature of the center of lump coal is 600℃ to 1000℃ ℃, the upper limit T3 of the heating rate is L(℃/min)=0.
64 (kato) - 7.72 (kayaku) 133.

It is 28.

On the other hand, from the drawing, the lower limit of the temperature increase rate is 2.
From 00°C to 60°C, the lower limit L of the temperature increase rate is t(°C'min)=〇. 53 breath 2-6
-773 points 121-43 The temperature at the center of lump coal is 6000
0, and from 600qC to 1000°C, the lower limit of the temperature increase rate is 0°C Jmin.

The reason why the range of 20,000 or less is not particularly restricted in the drawings is because the temperature increase speed of agglomerated coal is not directly related to its coking property in the range from room temperature to 200 qo. Examples according to the present invention are shown below.

The heating device is capable of heating the agglomerated coal at an arbitrary temperature and at an arbitrary heating speed by blowing combustion gas at an arbitrary temperature into a shaft furnace filled with agglomerated coal. The quality of the product was determined by measuring the index of 15m/ (hereinafter referred to as DI Royal o index) and the index of 25' (hereinafter referred to as D Sato index) by a 150 rotation test according to the drum test method regulated by JIS K2151. The DI Mikio index is an index that represents the abrasion strength of molded coke, and 01KiO is an index that represents the concentrated cracking strength of molded coke. The difference between both indexes is preferably 10% or less. Example 1 Temperature increase speed shown in the drawing for 80-grade agglomerated coal produced by briquetting by adding 8% pitch as a binder to powdered coal whose coking properties were suitably adjusted using non-caking coal as the main raw material 1000 in the case of three heating patterns: upper, middle and lower limit of
The original yield and coke strength when carbonized to oo were as follows.

150 150 Increasing salt speed Prototype walking crab association D1,5 D125' association upper limit 100 86.1 77.3 medium limit
100 84.7 79.6 Lower limit 100
83.1 79.5 Example 2 30 lumps of agglomerated coal were produced by adding 8% pitch as a binder to pulverized coal whose coking properties were suitably adjusted using non-caking coal as the main raw material and briquetting it. 10 in the case of the three heating patterns of upper, middle and lower limits of heating speed shown in the drawing.
The prototype yield and coke strength when carbonized to 00 qo were as follows.

Noboru Spi-Hori Shibarumigiri D11 Chapter g Rin△D1 Listen.

Mackerel upper limit 100 85.7 76.9 middle limit 100 84.2 78.3 lower limit
100 82.8 78.5 Reference example 1
The lump coal used in Example 1 was heated up to 500°C at a heating speed close to the upper limit within the necessary heating speed range shown in the drawing, and at a heating speed exceeding this upper limit above 500q○. The strength of the molded coke at that time was D, although the DI guest o index was 84.7%.

The index was 69.3%, and the concentrated cracking strength was insufficient. Reference Example 2 When the lump coal used in Example 1 is heated to 500°C exceeding the upper limit of the temperature increase speed shown in the drawing, and heated while maintaining the required temperature increase speed range above 500 °C. The DI royal o index of the molded coke was 83.0%, but the molded coke was deformed due to the swelling of the lump coal, and the prototype walking speed decreased.

Reference Example 3 The lump coal used in Example 1 was heated up to 500°C at a heating speed that was below the lower limit of the required heating speed shown in the drawing, and above 500°C it was heated while maintaining the required heating speed. The strength of the molded coke is DI Royal O index 7.
4.3%, and D's o index was 73.9%, and only molded coke with low abrasion strength was obtained.

As explained above, when producing metallurgical molded coke that maintains the required quality by coking lump coal made of non-caking coal as the main raw material, the heating rate depends on the temperature of the lump coal. There is a need to control
This study clarified this point and clarified the basic conditions for the carbonization method of agglomerated coal in a completely new manner.

This invention has made it possible to easily design the carbonization method and carbonization equipment for agglomerated coal, and has made a significant contribution to the practical application of economical and industrial carbonization methods, which have hitherto been considered difficult to produce molded coke. It is something that does.

[Brief explanation of drawings]

The drawing is an explanatory diagram of the appropriate temperature increase speed during carbonization in the present invention.

Claims (1)

[Claims] 1 When producing molded coke for metallurgy by carbonizing lump coal produced by adding a binder to coal with low caking property as the main component, the temperature at the center of the lump coal is from 200°C to 600°C.
The temperature increase speed of the center of lump coal while rising to ℃200
℃, 10 to 40℃/min, and the upper limit speed for lump coal temperature T is T_1 (℃/min) = 2.26
(T/(100))^2-25.57(T/(100)
)+82.10 lower limit speed T_2(℃/min)=
0.53(T/(100))^2-6.773(T/(
100)) +21.43, gradually decreasing as the temperature increases, 0 to 10 °C/m at 600 °C
The temperature at the center of the lump coal increases from 600℃ to 10℃.
The temperature increase speed at the center of the lump coal while rising to 00°C is the upper limit speed with respect to the lump coal temperature T, which is T_3 (°C/mi
n)=0.64(T/(100))^2-7.72(T
/(100))+33.28 lower limit speed to 0℃/mi
A method for producing molded coke for metallurgical use, characterized in that the temperature is increased gradually within a region defined as n so that the temperature increase rate at 1000°C is a maximum of 20°C/min.