SU755865A1 - Method of fuel preparation for agglomeration - Google Patents

Description

The invention relates to the field of preparation of raw materials for blast smelting.

The known method of preparation of sinter coke breeze by joint crushing of metallurgical coke wet quenching and lime [1] ·

The essence of the method lies in the fact that coke wet quenching is pre-mixed with burnt lime and served for co-crushing in coke crushers. Due to the high hygroscopicity of the lime is partially hydrated by the moisture of coke, forming a colloidal aqueous alkaline solution. Calcium ions, penetrating into the pores and microcracks of coke, activate carbonaceous matter and thereby increase its burning rate.

The disadvantages of this method are the following: deteriorating sanitary and hygienic working conditions due to the release of lime dust, and the joint crushing of coke and lime leads to the passivation of the active centers of coke due to their screening with calcium hydroxide.

The closest ¹ technical solution of the present invention

2

is a method of coking using burnt lime in the charge, which is pre-metered in the amount of 8-10% and mixed with the charge for coking.

The essence of the method lies in the fact that the charge for coking is mixed with a dosed amount of lime, served in coke oven batteries and subjected to coke wet quenching with water. The introduction of active flux helps to increase the bulk mass of the charge and the rate of formation

15 melt.

Lime in the process of coking actively interacts with coke ash, forming calcium silicates and

20 low-melting effektiki, crystallized in vitreous phases. Under these conditions, aggravated by wet quenching, the quality of metallurgical coke deteriorates significantly. Therefore, this technical solution did not go beyond the stage of industrial testing.

The disadvantages of this method are the following: dilution of metallurgical

30 coke on its carbon content *,

3

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increase) operating costs for crushing and cost of coke)

irretrievable loss of heat during wet quenching of coke;

lack of reactivity of coke breeze due to a significant shielding effect.

The aim of the invention is to increase the reactivity of sintering fuel and reduce its cost.

The goal is achieved by the fact that in the method involving coking the mixture using enriched lime in it, subsequent wet quenching and crushing of coke, red-hot coke is extinguished with water-alkaline solutions of calcium and sodium oxides, taken in a ratio of 1: (0.02-0, 03), while the concentration of the solution is maintained in the range of 1.3-5 g / l.

The drawing shows the dependence of the rate of combustion of coke from its temperature.

The catalytic effect of alkaline additives on the rate of burning of coke is manifested only when the quenching of the components involved (1.3–5 g / l) at a temperature not lower than 500 ° С (curve 1). The cooling of coke, which did not pass the preliminary stage of mineralization with alkaline additives, is accompanied by a sharp decrease in the burning rate (curve 2). X-ray diffraction analysis showed that coke, which did not undergo mineralization, undergoes a structural change in the process of quenching: a decrease in the interbasic distance and a slight increase in the proportion of ordered carbon (the intensity of the stock decreases from 1.4 to 1.1). These factors are responsible for reducing the rate of coke burning.

Mineralized fuel is characterized by the radiation orientation of the carbon atoms in the package, while the size ί _ο increases from 48.5 to 51 A. At ⁰ these conditions, oxygen access to carbon atoms improves, the rate of combustion of the fuel increases.

A characteristic feature of the combustion of mineralized fuel is a decrease in the oxygen demand necessary for the formation of the C _x O ^ complex. The analysis of exhaust gases showed that the oxygen content of air in this case can be reduced by 15–20% (rel.), Which is a significant reserve for more complete use of fuel and intensification of the agglomerate.

The effect of sodium dioxide on the mechanism and kinetics of burning solid fuel, as shown; X-ray analysis, similar to the effects of lime. However, the need to use complex water-alkali

solution for quenching and mineralization of coke-due to the fact that sodium dioxide, being a surface-active substance, the radius of the ion Ia ⁺¹ which is much less _{about the} radius of the ion Ca ¹ ^

(0.098 and 1.06 A, respectively) are adsorbed in the micropores of coke, inaccessible to calcium ions, causing a wedging pressure that increases significantly as the water film thickness decreases. At the same time, in the process of quenching hot coke, aqueous alkaline solutions, penetrating into the volume of coke, cause its destruction not only due to thermal shock, but also due to considerable forces due to the wedging effect. Degree of destruction

(i.e., coke particle size distribution) is proportional to the concentration of Ia ions in the aqueous solution. Therefore _ the decomposition of Ca and Νθ oxides is limited by the ratio 1: (0.02-0.03). An increase in the content of the latter in excess of the optimal values leads to an increase in the yield of small classes (^ 0.5 mm) both during the quenching period and during the crushing of coke. Reducing the flow rate Ia ₂ 0 is accompanied by a significant decrease in the propping pressure, which leads to an increase in operating costs for crushing. So, when crushing mineralized coke (in terms of the relative ratio of CaO: Νβ ₂ 0), power consumption decreases by more than 20% compared to the cost of crushing non-mineralized coke.

From the drawing (curve 3) it can be seen that an increase in the concentration of the solution in excess of 5 g / l (8-15 g / l) is accompanied by a monotonic decrease in the burning rate. This circumstance is explained by passivation and reduction of the reaction specific surface. The highest solubility of calcium oxide in water at room temperature is 1.3 g / l.

The decrease in the concentration of the solution below the specified value (0.5—

1 g / l) leads to a decrease in the burning rate (curve 4), and the nature of the change in the course of the curve is similar to the change in the kinetic pattern of combustion of non-mineralized fuel (curve 2).

Thus, the activation of hot coke with an aqueous-alkaline solution will allow an increase in the burning rate of the fuel by more than 15%.

At the same time, the cost of crushing is about 20%. In addition, as shown by the experiments, the coke breeze, activated during the quenching process, acquires hydrophilic properties, the wetting angle for OHMK technical water decreases from 130 to 30-32 °. It is characteristic that for the Mikhail aggloods possessing

five

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the highest hydrophilicity, boundary angle 28 °. Consequently, the use of activated fuel in the charge will significantly improve the quality of its preparation.

The method can be implemented 5

by using gas cleaning from a sintering plant containing about 1-6 g of CaO with the addition of the optimal amount of caustic soda for quenching coke. For softer. here

heat treatment, activation and cooling of coke, it is advisable to use the method of pulse quenching, used in a number of plants.

In the intervals between water intakes, health coke more effectively adsorbs alkali metal oxides, causing a disorientation of carbon atoms and increasing its activity. Also in this

coke time is cooled by steam, which allows to increase the time of coke activation in the high temperature region.

Π p and me. The study of coking was carried out in a laboratory shaft furnace at 1100 ° C. For the study used the mixture, consisting of 50% .coking coal and 50%. coal grade SS, lime consumption 10% by weight of the charge.

Quenching of coke was carried out with a water-alkaline solution, the concentration of which was changed in the range of 0.5-10 g / l with a content of CaO and Ea ₂ 0 0.49-9.8 and 0.01-0.2 g, respectively, in one liter. To obtain comparative data water quenching was carried out.

The results of laboratory studies are presented in the table.

Coke quenching

Water indicators

Water-alkaline solution

Water-alkaline solution, 'pulsed mode with a ratio

The concentration of the solution, g / l between feed pulses and heat treatment 10:20 s 0.5 3.0 10.0 The concentration of the solution, g / l Cao Νθ _ζ 0 Cao N3 ^ 0 Cao Νβχί 0 ,five 3, ( ) 10.0 0.49 b; όΐ 2.94 0.06 WITH σ 0.2 Cao ΝβχΟ Cao Cao Νβχ 0 0.49 0.01 2.94 0.06 9.8 0.2

L

giving agent m ^a / t Quenching time, min 2.2 to 3.0 ...... ''BUT 2.2 alto Reactionary ability, ml / gs 2.97 2.82 3.25 Costs one splitting up, 1.60 1–45 rub, cop / t Cost price 1 ton coke little things rub, cop / t 24.60 24.45

2.85

_

2.2

3.0

3.40

2.98

1.30

24.30

Claims (1)

Claim The method of preparing fuel for agglomeration, including coking the charge with the use of calcined lime, subsequent wet quenching and crushing of coke, characterized in that, in order to increase the reactivity of sinter fuel and reduce its cost, the red-hot coke is extinguished with aqueous-alkaline solutions of oxides calcium and sodium, taken in a ratio of 1: (0.02-0.03), while the concentration of the solution is maintained in the range of 1.3-5 g / l.