SU1518396A1 - Method of sintering a charge - Google Patents

Abstract

This invention relates to ferrous metallurgy and can be used in the sintering of iron ores and concentrates on sintering machines. The purpose of the invention is to reduce the dust content of waste gases and the fuel consumption for ignition and sintering of the sintering mixture. During sintering of the sintering mixture, ignition is carried out in two stages. First, a gradual increase in the vacuum in the charge layer is carried out, and after 0.2-0.6 times the supply of the kiln gases into the layer is reduced by an amount not exceeding 0.35 of its working value, and then again increased at a rate of 4.4 -8.2 times lower initial dilution rate. Optimization of ignition leads to an intensification of the combustion of solid charge fuel. 1 tab.

Description

The invention relates to ferrous metallurgy and is intended for sintering iron ores and concentrates on sintering machines.

The purpose of the invention is to reduce the dust content of waste gases and fuel consumption for ignition and sintering of sinter charge "

The essence of the invention is as follows.

With an increase in the rate of movement of the mountain gases, the extreme heat transferred by them to the nearby layer of the charge mixture decreases and most of it goes to the subsequent horizons. In the initial stage, this can have a positive effect.

on the ignition, since the upper part of the charge is dried sufficiently deeply and heated to high temperatures. However, upon reaching the optimum level, further expansion of the drying zone and heating of the charge begins to impair the heat concentration in the layer. Therefore, after the initial preparatory stage of ignition, the feed rate of the flue gases into the layer must be limited to values that ensure complete optimization of the ignition. At the same time, the feed rate of the furnace gases, as a rule, should be reduced so as to achieve the maximum approximation of the high temperature zone and the drying zone of the charge at the limiting stage

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 with a

Split the heating zone. Moving at low speed, the furnace gases give up most of the heat to heat. After the layer leaves the hearth, atmospheric air enters it, the combustion of solid charge fuel intensifies and the nature of heat exchange in the layer changes.

In addition, optimization of ignition requires the maximum allowable reduction of the heating period of the upper part of the layer to the temperature of the formation of the cake, and thereby increasing its period of stay under the mountain, that is, when fed into the layer of mountain gases. To do this, it is necessary at first to achieve a high permeability of gas, partially realizing it, to ensure rapid heating of the upper part of the layer to the temperatures of formation of the cake. The subsequent supply of gaseous gases should provide only input to the upper part of the layer of external heat consumed to melt it during the formation of the cake. At this stage of ignition, it is necessary to preserve a large part of the increased gas permeability of the layer initially achieved for its subsequent sintering. Such a condition is achieved with the exception of the excess supply of furnace gases to the layer during its ignition,

In general, it is divided into two stages. At the first stage, forced gradual suction of the underpressure under the layer being ignited is performed, ensuring an optimal increase in its gas permeability, suzhu and heating the upper part to the temperatures of formation of the cake. In the second stage of ignition, taking into account the changed aerodynamic resistance of the layer, the formation of a cake is completed in the upper part of the layers, narrowing of the heating zone and, most importantly, preserving most of the layer’s increased rason level at the beginning due to the reduction of the inlet rock to it. In order to implement this techno-pogii in the global conditions at the percussion stage of the ignition, the optimum is 4 1 1 the increase in the underpressure under the layer at a speed of 200-270 Tlii / s, and on the second - 33-45 Pa / s.

The maximum time is 1 :, the final stage of increasing the rarefaction; d-, H under the layer should not get any O, b ignition period. Otherwise, an excess amount of gaseous gases enters the layer and it is reached at the outset by increased gas permeability which decreases sharply. Reducing the flow of gaseous gases to 0.2 of the total ignition period does not allow for intense heating of the upper part

The layer to the temperature of the formation of the cake and the process indices are sharply deteriorating.

After the initial stage, in most cases, before the final stage of ignition, it is necessary to reduce the vacuum under the layer. At the same time, due to an optimally excessive initial increase in the rarefaction, it is possible to minimize the first stage of ignition and go to the second stage as soon as possible, i.e. holding the upper part of the layer at the temperature of the formation of the cake and reducing the zones of heating and drying in the layer. However, reducing the negative pressure tla of the transition between the stages of ignition by more than 0.35 of the working value is not feasible; Incomplete this condition

leads to the fact that it is necessary to subsequently speed up the rate of suction of the vacuum under the fire layer or to excessively prolong the period of smooth throttling. in the first case, the gas permeability of the lighted layer is not maximized, and in the second, the area of underpressure under pressure

the upper part of it is supplied insufficiently to complete the formation of the sinter amount of external heat. In both cases, the optimal conditions for the sintering process of the material are violated and its final indicators deteriorate.

To fully optimize the process in the second stage of ignition, the increase in the cut-out or under the layer must be carried out at a speed of 4.4-8.2 times

less than the first. When the ratio of these speeds is more than B 8.2 times, there is a shortage of heat in the upper part of the layer or excessive elongation.

kgf section of smooth throttling, and at a ratio of less than 4.4 times the layer enters an excess amount of gorny gases and its resistance increases sharply.

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Conducted laboratory tests of the proposed method.

The experiments were carried out on a laboratory bowl with an area of 0.16 m during sintering of the charge of the current production of sintering plant Krivorozhstal KMK in a layer, 320-mm shank and an increase in vacuum to 8-12 kPa. During sintering of the charge by a known method during the ignition period, the rate of increase in the underpressure under the layer is kept constant, and according to the proposed procedure, the rate of optimization along the process is determined using a gate valve located on the duct from under the bowl.

During the experiments, the flow rate — gaseous fuel (a mixture of 50:50 coke-domain gases) is fixed with the help of an agglomerate installed on a support on the layer after ignition, and the rate of air filtration into it. According to the conventional method, the dust content of the exhaust gases is determined by internal filtration and the optimum consumption of solid fuel in the charge is selected that corresponds to the minimum fines content less than 5 mm in the sinter after 2 times dropping the cake to the metal plate from a height of 2 m. At optimum consumption of solid fuel is fixed installation performance.

The results of the experiments are given in the table.

From the data presented in the table, it follows that in order to achieve the purpose of the invention, after 0.2-0.6 the time of the supply of the mountain gases to the bed

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below it, its working value is reduced to no more than 0.35, and the subsequent arc increase in underpressure under the bed is carried out at a speed of 4, D-8 times lower than its initial speed. Increase

The use of the advanced method of sintering the sinter blend according to

10 compared to the known, it reduces the dust content of waste gases by 1.3–1.5 times, the gas consumption for ignition of the charge - by 2.9–4.0 sinter, the solid fuel of the ingigtu -

15 1.6-2.6 kg / t sinter, increase

productivity of sintering machines by 9–20% decrease in the content of fines in the sinter by 1.2–1.7% and increase in equipment durability, in particular, the exhauster rotor,

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Claims (1)

Invention Formula 25 Sintering sintering mixture sintering method, which includes supplying the mountain gases and atmospheric air to the layer of material with a gentle dilution which differs 30 so that, in order to reduce the dust content of the exhaust gases and the fuel consumption for ignition and sintering of the sintering mixture, after 0.2 -0.6 time of delivery of the mountain gases in the layer the vacuum is reduced by not exceeding 0.35 of its working value, and then increase with a speed 4.4–8.2 times lower than the initial speed of 1: rarefaction