SU1052483A1 - Method for processing slag melt - Google Patents

Abstract

1. A process for processing slag melt, including its crystallization by feeding onto moving cooling surfaces, convective cooling of the obtained slag solid tape to 200-250 ° C with a cooling agent and further grinding the slag to obtain a finished product, characterized in that an increase in the utilization rate of heat, a reduction in capital expenditures and a better quality of the finished product, prior to convective cooling of the slag tape, it is pre-cooled to 700–750 ° C by radiation heat exchange. . / 7ffft

Description

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2. POP.1 method, characterized by the TCMf that, in order to surface harden the donkey tape, ensuring its strength, radiation heat exchange is carried out at a rate of 3-5 C per second.

The invention relates to methods for processing slag melts and can be used in the chemical industry in the production of yellow phosphorus, as well as in metallurgy. industry in the production of iron, steel, etc.

There is a known method for processing slag melt, which consists in spraying it and cooling it in an air stream. The cooled slag is used as a gravel, and the air heated to EOO-SUE C generates steam in the Cl 3 waste heat boiler.

In this method, the granulation (crystallization) process of the slag is carried out in an air stream with low intensity, resulting in poor quality of the granulate, as well as a large amount of slag sand and slag wool, which makes it difficult to use hot air. as an agent in waste heat boilers, Pptx. In addition, granulated slag is the most low-value product of slag processing, 3-4 times lower than the cost of molten slag rubble.

Closest to the invention is a method carried out in a plant for processing blast furnace slag melt, which includes crystallization of the slag melt by feeding it onto moving cooling surfaces (rolls-crystallizers) with subsequent convective cooling of the resulting slag solid tape to 200-250 with a cooling agent, aimed at the production of paraenergy parameters with further grinding of slag to obtain the finished product. The solid slag ribbon is cooled with humid air, fed by Elm through nozzles installed under the rolls-crystallizers. Hot air is directed to a convective heat exchanger (boiler) where it generates steam energy parameters C2 3.

CkiHOBHbiM the disadvantage of this method is inefficient op3. The method according to Claims 1 and 2, o and in that, in order to evenly cool the solid slag tape, during radiation heat exchange, the cooling agent is fed in the direction opposite to the movement of the slag tape.

organizing the cooling process of solid slag. The use of intermediate heat carrier for cooling slags (air practically excludes participation in heat transfer of radiative heat exchange, which results in a low heat transfer coefficient / This, as well as the need to use a large amount of air for cooling, leads to high heat loss 6 the environment (slag heat utilization rate does not exceed 60-70%) and to the large size of the heat utilization equipment.

five

Another disadvantage of this method is the low quality of the material obtained1) due to the low hardness of the face caused by the unevenness of the cooling process of the slag tape.

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The purpose of the invention is to increase the heat utilization rate, reduce capital costs and improve the quality of the finished product.

The goal is achieved by

1 that according to the method of processing slag dispersion / including its crystallization by feeding onto moving cooling surfaces, convective cooling obtained by slag-solid solid sheet DO 200-250С

0 cooling agent and further grinding of slag. Before the final product is obtained, the slag tape is made before convective cooling of the slag tape.

5 pre-cooling it to 700-750 ° C by radiation heat exchange.

In addition, for the purpose of surface hardening of slag tape, providing its strength, radiation

0; heat exchange is carried out at a rate of c. give me a sec.

For the purpose of uniform cooling of solid slag tape during radiation heat exchange, the cooling agent

5 served in the opposite direction of the donkey tape.

1 shows a schematic diagram of the energy process for the processing of slag melt)

0 in Fig. 2 is a graph of the dependence of the density of the heat flow of the cooled slag on temperature. Liquid slag enters the accumulator 1. From the accumulator 1, liquid slime is supplied to the unit for continuous casting and cooling of slag, consisting of a roll-type mold 2 and radiation 3 and a convective 4 heat exchangers-cooling amps. The slag hard tape is then crushed in crusher 5 and fed to a vibrating screen b, where fine, coarse sand is separated from large crushed stone. Slag sand and crushed stone are loaded into appropriate hoppers 7 and 8. Wet saturated water; tnap enters separator 9, where there is a separation of dry saturated steam and water. Dry steam. The water is supplied to the superheater 10, and the water is returned to the evaporative cooling system of the crystallizer and the radiation heat exchanger 3. From the superheater, the steam that has been superheated to the required temperature goes to the turbogenerator. In the steam boiler, only a fraction of the heat of the combustion products obtained from the combustion of fuel in the boiler is used. Another part of the heat of the combustion products is combined with the air heated in a convective heat exchanger used in the air duct 11 and the water economizer 1 The proposed method of processing slag melt is carried out. in the following way. In order to maintain the required temperature, the slag entering the dust register 1 is burned with liquid or gas-gaseous fuel. The temperature of the gases in the chamber 1 is maintained at ISO20O from above the temperature of the flowable state of the slag. This gas temperature is provided by the high-temperature heating of the air in the air heater 11. In the mold 2, which is included in the unit for continuous casting and cooling, slag,; Liquid slag is formed into a flat continuous tape with a thickness of 20-V 30 mm which is then successively cooled in heat exchangers 3 and 4. In the radiant heat exchanger 3, the die is cooled to 700–75b C. After the convective heat exchanger, the slag tape is crushed in crusher 5 and fed to the vibrating screen b to separate fine slag powder. ka from large rubble, which are then loaded into the appropriate hoppers 7. and 8. Chemically purified water is heated in a water economizer 12 and sent to the system: evaporative cooling of the crystallizer and a radiation heat exchanger, where wet saturated steam is formed that enters separator 9. In. the separator separates dry dry steam and water. The dry saturated steam enters the superheater 10 and the water returns to the evaporative cooling system. In the superheater use only part of the heat of the combustion products. Another part of the heat of the combustion products together with the air heated in the convective heat exchanger 4 is used in the air heater 11 and the water economizer 12. The mixture of the combustion products cooled to 120-1 OBS and: the exhaust air is removed from the apparatus 12 and 11 and is thrown into the chimney . In order to ensure a high utilization rate of slag heat with a minimum of expenditure in the heat utilization system, it is necessary, when cooling the solid slag, to rationally combine radiation and convective heat exchange. The radiation density of the surface of the slag depends on the temperature, degree of blackness, roughness, chemical decomposition. Figure 2 shows the radiation density Cg t, j) of the slag when its temperature changes. It also shows the change. heat flux density (.) when cooling the slag surface with air, moving with an average ctcopocTbfo of 15 m / s. As follows from the dependence presented, the radiation density of the surface of the liquid slag is 6–10 times higher than the heat flux density during convective heat transfer. When cooling the surface of solid slag, the difference between the values of specific heat fluxes during radiation in convection decreases, and at temperatures below 700-750s the convective component exceeds the radiation component of heat transfer. Thus, with. Bbmje 700-750 C slag surface temperature is rational to cool the slag by radiation heat exchange, and at temperatures below 700-750С - by convection heat exchange. The strength of the slag ribbon depends on the conditions of its cooling. To ensure maximum slag strength | at a minimum of costs in the heat-use system, the cooling of the slag tape must be carried out at a speed of 3-5 ° C per second. When the slag is cooled at a rate of more than 5s per second, thermal cracking is observed, leading to a sharp decrease in the strength properties of the slag. So, when cooling phosphoric slag with a speed of 8 ° C per second, the slag compressive strength does not exceed the value of 45-50 kgf / cm against 200-250 kgf / cm 2 achieved during cooling and the proposed

speed .. The cooling of slag with a goodness of less than a second does not lead to an increase in the strength properties of the slag. At the same time, at low cooling rates, the envelopes of the radiation heat exchanger increase, and hence the investment in the heat management system. In addition to that, the slag tape from the crystal rolls comes out with a temperature close to the melting point, and O even liquid slag is inside it. Cooling such a tape at a speed of less than a second leads to stretching and breaking off of the tape under its own weight.

It is known that the intensity of radiative heat transfer between bodies is directly proportional to the difference in the fourth power temperatures of the bodies. To ensure that the cooling of the slag is uniform over the entire length of the non-radiative heat exchanger, it is necessary to maintain a sufficiently high temperature difference between the surface of the slag and the wall of the radiating heating surfaces. 25 This is possible only with the movement of the taylon carrier in the direction opposite to the movement of the slag tape. Example. Slag from the blast furnace with a flow rate of 100 t / h goes to the energy technology accumulator ag. regatta for slag processing. The heat of the molten slag is 187.3.110 Mge. To maintain the slag in a fluid state and yeko, g. In addition, the accumulator is heated with natural gas, as a result of which 25, 14–10 MJ of heat are released in the chamber. From the digger slag with the temperature goes to the rolls-crystallizers; where oh 40

is cooled to 1300 ° C. During the crystallization process, 18.8b "lO MJ or 8.9% of the applied heat is utilized. From the rolls, the solid slag tape is successively fed to the radia- tional and convective heat exchangers, where it is cooled to 730 and 200 ° C. the ribbon is crushed. During the cooling process, the slag ribbon is utilized 50,100.5610 MJ or 47.3% of the heat added. 41, or 19.7% of the heat input to it, is utilized in the evaporative cooling and digger system. amak 24.1 10 MJ

(11, exhaust gases 17.64 x YoZmJ (8.3%;; - to the environment 9.33 10 MJ (4.5%). The efficiency of the power technology unit is 76.9%. When processing 100 t / h molten blast furnace slag produces 60 t / h of water vapor Energy parameters and 90 t / h (rubble with a strength of 250 kgf / cm.

P p and m e p 2. Phosphoric slag from the tap hole of an electrothermal furnace with a temperature of 1480 ° C is fed to the crystallizer rolls. The phosphorus slag consumption is 60 tons per hour. In the process of slag crystallization, Ilj8010 MJ or 9.5% of the applied heat is utilized. The solid slag ribbon enters the radiation heat exchanger where it is cooled to, and Water Steam is generated in the evaporative cooling system,.,

whereby it is utilized. ..

52.8-10 MJ or 42.5% of the contribution. heat After the radiation heat exchanger, the slag is cooled to

in a convection heat exchanger where, by cooling the slag, heating takes place: air to 550-600 ° C. Hot air is used as a heat carrier, in a superheater and economizer of an energy technological unit. In a convective heat exchanger, 33.9% of 10 MJ or 27.3% of Heat applied is utilized. The heat loss of the energy process (with chilled slag, c-flue gases, to the environment 7 is; 25/7 "10 3 MJ or 20.7% of the heat input, and the efficiency of the energy-technology unit is 79.3% As a result of slag cooling, 37, t / h are formed. A pair of energy, parameters, as well as 55 t / h of molten slag rubble.

Comparison of the technical advantages of the proposed and well-known methods. Given in the table.

The proposed method of slag melt processing allows the most complete use of the physical heat of the slag melt (the heat utilization factor is 75-85% 7 / reduction of capital expenditures in the heat-use system by 25-30%; improve the quality of the final product (yield of crushed stone reaches 80-90 %

Unit capacity, t / h

slag

a couple

The temperature of the slag / leaving the unit, with

Slag processing product

The yield of the product,%

Cost of suitable product, rub./t

Durability,

wrrr / pm

CGS / CM

Consumption of process water for slag cooling,

The consumption of chemically treated water with allowance for purging and losses, m / h

Slag heat utilization rate,%

Specific capital investments in the system of heat use and granulation, rub./t

The total economic effect of steam generation and gravel production, thousand rubles.

100

100 .45 50

200-250

200-.250

Rubble

Rubble

Gravel

75

90

1.0

1.2

150-200

200-250

1200

50

55

80

60

1.8

2.2

910.0

760.0

-3

f /

w / f

180 170

t

ISO

t t t

100 90 80 70 60 50

 40 30 20 10

О 72 J 4 S 6 7 8 S 7О // Г2 Л7 / (: fig.g

Claims (3)

1. METHOD FOR PROCESSING SLAG MELT, including its crystallization by feeding on moving cooled surfaces, convective cooling of the resulting slag solid tape to 200-250 ° C with a cooling agent and further grinding of the slag to obtain the finished product, characterized in that, for the purpose to increase the heat utilization coefficient, reduce capital costs and improve the quality of the finished product, before convective cooling of the slag belt, it is pre-cooled to 700-750 ° C by · _o 'radiation oh heat transfer. © Superheated Dodianou Feast SU ... 1052483 2. The method according to claim 1, characterized in that, with the aim of surface hardening of the slag tape, providing its strength, radiation 1052483 ny heat exchange carry out with speed 3 - 5 ** C per second Do. > 3. The method according to claims 1 and 2, about τ’l and characterized in that, in order to uniformly cool the solid slurry tape *, during radiative heat transfer, the cooling agent is fed in the opposite direction to the movement of the slag tape. D.