JPS5854176B2 - Method for preventing particle size segregation of sintered raw fuel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing raw fuel particle size segregation for optimizing the particle size of raw fuel, that is, cut coke breeze, when feeding raw material to a sintering machine.

Particle size control of coke powder, which is the heat source in the sintering process, is considered to be extremely important in ensuring the quality of sintered products and stabilizing operations.

Generally, coke breeze is mixed in a constant range of 2.5 to 4.0% in all raw materials, but when feeding the raw material to the sintering machine, the cut particle size changes periodically due to fluctuations in the amount of stock in the ore storage tank. It is known to do.

To explain concretely, in the tank, fine coke particles are formed in the center of the tank, as shown in Figure 2A.
Coarse coke is deposited on the wall side, and if there is a large amount of inventory in the tank, fine coke is cut out first (Fig. 2B).
), coarse coke is cut out as the inventory decreases (Figure 2C).

As described above, when coke breeze is charged, particle size segregation within the tank is significant, and this causes periodic fluctuations in the cut particle size every time the stock amount in the tank changes.

This fluctuation in the cut-out particle size causes fluctuations in the wind box exhaust gas temperature and air volume of the sintering machine, causing problems such as deterioration of sintering quality, and if the coke breeze particle size becomes extremely coarse. An alarming situation occurs in which a seizure phenomenon occurs on the surface of the sintered pallet grade, shortening the life of the grate bar and causing extreme operational disruption due to air leakage.

As a method for solving the above problem, this invention is characterized by reducing and preventing particle size segregation in the tank by controlling the amount of water added during the mixing process of coke powder in accordance with the amount of water content after mixing. This is a method that can stabilize the particle size of raw fuel.

This invention detects the amount of moisture contained in the mixed coke breeze when adding moisture in the process of mixing raw fuel, that is, coke breeze, and adjusts the moisture content by 15 to 25 by feedback operation based on the moisture value. This is a method that can reduce the particle size segregation of raw fuel in the ore storage tank by adding it within the range of .

Figure 1 shows an example of equipment for carrying out the method of the invention, in which 1 is a raw fuel tank, 2 is a blending belt conveyor, 3 is a mixing device (crusher), 4 is a transport conveyor, and 5 is an ore storage tank. , 6 is a charging conveyor, T is an injection device, and 8 is a moisture detector.

That is, during transportation of the mixed coke powder to be charged into the ore storage tank 5, the moisture content of the mixed coke powder is detected by the moisture detector 8, and based on this moisture value, the amount of water injected is controlled by feedback operation to ensure an appropriate amount. of water is added.

According to this method, the water content of the coke breeze can be adjusted before charging it into the ore storage tank 5, so particle size segregation in the ore storage tank can be reduced, and fluctuations in the cut particle size can be reduced. ,
And it is possible to stabilize it.

This will be explained in detail below.

This invention method is based on the fact that it has been confirmed in the laboratory that the change in the particle size of coke breeze cut out is greatly related to the moisture content of coke breeze. This is a chart showing the results of determining the relationship between the values.The chart shows that when the moisture content is low, the cut-out particle size fluctuations due to stock particle size fluctuations are large, and conversely, as the moisture content increases, the grain size fluctuations over time decrease. Is recognized.

The reason why such a phenomenon occurs is clear from FIG. 5, which shows the relationship between the moisture value during the mixing process and the internal friction coefficient of the ore storage tank.

In other words, as the water content of coke breeze rises, the friction angle of the coke breeze in the tank increases (the internal friction coefficient increases), and the particle size segregation at the center and wall during deposition in the tank decreases as the water content rises. be.

The relationship between the friction coefficient μ and the friction angle θ is μ=-tanθ
It is expressed as

Figure 6 shows the particle size segregation situation when piled up in an ore storage tank when measured using the equipment shown in Figure 1. From this diagram, it is clear that the amount of water added during the mixing process is 15 to 25%.
It can be seen that within the range of , the particle size segregation within the tank is significantly reduced.

In other words, this means that when the moisture content is in the range of 15 to 25, the ore storage tank is 5.
Due to the increase in the internal friction coefficient of the internal coke powder, slippage (rolling) during charging is reduced, resulting in less particle size segregation in the state shown in Figure 2 A, and a decrease in inventory as shown in Figure 2 B and C. This is because the coefficient of internal friction is high, so it is difficult to reduce slippage.

On the other hand, when the moisture value is less than 15, although a decrease in particle size fluctuation over time can be seen as described above, the moisture content is lower than when the moisture is 15 or more, so segregation is easy to occur, and when more than 25 is added, coke tends to stick to each other. This causes shelf hanging.

Therefore, fluctuations in the cut particle size due to changes in inventory will result in moisture 15
A range of ~25% is considered appropriate.

As explained above, according to the method of the present invention, the moisture content of mixed coke powder is detected before it enters the ore storage tank, and the moisture content in the mixing process is varied based on this moisture value. Since fluctuations in grain size segregation within the ore tank can be controlled, fluctuations in cut grain size can be reduced and stabilized.

Further, according to the method of the present invention, the life of the bar can be extended by 20 times compared to the conventional method, and the air leakage rate in the wind box can be reduced by 10 to 20 times.

Furthermore, the method of this invention has the advantage that it can be easily applied to existing equipment by simple equipment improvement.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing an example of a device for carrying out the method of this invention, Fig. 2 is an explanatory diagram showing the current state of cutting out coke breeze in an ore storage tank, and Figs. 8 and 4 are illustrations of coke breeze cutting. Figure 5 is a diagram showing the relationship between cut-out particle size change and moisture value obtained in a laboratory. Figure 5 is a diagram showing the relationship between moisture value and internal friction angle. Figure 6 is the result of actual measurement using the equipment shown in Figure 1. This is a chart showing the grain size segregation situation when the ore is piled up in a storage tank. In the diagram, 1... Raw fuel tank, 2... Blending belt conveyor, 3... Mixing device, 4...
・Transportation conveyor, 5...Ore storage tank, 6...
...Charging conveyor 7...Water injection device, 8...
...Moisture detector.

Claims (1)

[Claims] 1. By detecting the moisture content of the raw fuel mixed in the sintering raw fuel mixing process and adding the moisture content of the raw fuel within the range of 15 to 25% by feedback operation based on the moisture value, A method for preventing particle size segregation of sintered raw fuel, characterized by being able to reduce particle size segregation of raw fuel in an ore storage tank.