SU1260344A1 - Method of producing lime - Google Patents

Description

The invention relates to methods for the production of lime, mainly for the metallurgical processing of iron ore.

The purpose of the invention is to reduce the consumption of solid fuels, loss of raw materials and increase productivity. The essence of the method is as follows. Periodic feeding of the mountain gases and atmospheric air into the layer. Allows you to adjust the time of the High-temperature treatment of the upper part within the limits ensuring that it almost completely burns out carbon and dissociates limestone. At the same time, the cooling effect of atmospheric air does not have a fundamental effect on the firing rates. The full use of carbon in the upper part of the layer is one of the main conditions that provide the advantages of the proposed method. Due to the characteristic for the layered processes of heat recovery in the middle and lower parts of the layer, the heat consumed from burning residual after the first stage of carbon burning in its upper part allows reducing the equivalent fuel consumption to the charge. In addition, the intermittent feeding of the furnace gases into the bed provides the replacement of a large part of expensive solid fuel with cheaper gaseous. The proposed limits for the supply of mining gases practically exclude the presence of solid fuel in the main combustion zone to, respectively, the development of its smoldering in front of this zone. Before the onset of this period, atmospheric air begins to be supplied to the layer, and only after re-preparation of the main combustion zone does the supply of rock gases resume, etc. Reducing the consumption of solid fuel to the charge reduces focal lime burns, which increases its quality.

The method is carried out as follows.

Calcination of limestone is carried out at: a vacuum under the installation grid of 1000 Pa. In all experiments, the first stage of ignition is supplied for 90 s. The flue gases with a temperature of 1100 C. At this stage, heat is introduced into the layer with gases equal to 1.45 Mcal / ton of charge.

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With known technology, at the second stage of ignition after the temperature in the upper part of the layer decreases to 700 ° C, all furnace gases are supplied in one feed, and according to the proposed method, the same amount of heat from the furnace gases is introduced into the layer in several feeds. At the same time, in the gaps between the flows of the mountain gases, atmospheric air enters the layer. The beginning of the second stage of ignition is established on the basis of heating the upper part of the layer with furnace gases up to 1100 C.

In the course of the experiments, the optimum consumption of gaseous and solid fuels for lime burning, the degree of lime burning and the capacity of the installation were determined. Lime samples were taken to determine the residual carbon content in the upper part of the bed.

The results of the experiments are given in the table.

From the data presented in the table it follows that, according to a known method, an increase in heat consumption in the second stage of ignition, especially more than 182 Mcal / ton of charge, adversely affects the process. This is due to the occurrence between the main zone of combustion of the area of inefficient use of solid fuel. It was established experimentally that the content of CO (products of incomplete combustion of fuel) in the exhaust gases may increase more than 2 times. Heat savings and the replacement of solid fuels with gaseous fuels are not achieved.

The use of the proposed method allows to significantly improve the performance of the process of lime burning.

Experimental sintering showed that the proposed method reduces the fuel consumption by 1.4-2.2 kg / ton of sinter, reduces the fines content of less than 5 mm in the finished product by 1.5-2.0%, reduces the variability of the chemical composition of the agglomerate by 20 -28% and raw material losses by 0.6-0.7%, an increase in the capacity of the installation by 14-18% due to a decrease in the exhaust gas volume, an increase in equipment durability, in particular, grates and an exhauster rotor.

Studies have shown that the second stage of ignition should be carried out with periodic feeding into the layer

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no more than 80 s of gorny gas and atmospheric air.

Using the proposed method of obtaining lime in comparison with the prototype allows reducing the consumption of solid fuels and lime production by 1.5–4%, increasing the degree of lime burning by 4.6–10%; reduce the loss of raw materials by 0.5-0.7%; increase lime production by 5-9%.

 Determined by the change in the aerodynamic resistance of the layer during the period of the intake of the mountain gases

Compiled by A. Kulabukhova Editor A. Ogar Tehred L. Oleinik Corrector A. Zimokosov

Order 5185/19 Circulation 640 Subscription

VNIIPI State Committee of the USSR

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., D.4 / .5

. Production and printing: enterprise, Uzhgorod, Projecto st., 4

603444

The use of lime in sinter production ensures a reduction in fuel consumption, fines content less than 5 mm in the sinter, the variability of its chemical composition and raw material losses, as well as an increase in the productivity of sinter machines and equipment durability, in particular, grates and extractor rotor - 10 ra.

Claims (1)

'METHOD FOR PRODUCING LIME by two-stage ignition of a mixture with suction of furnace gases through a layer with a supply between stages in a layer of atmospheric air, characterized in that, in order to reduce the consumption of solid fuel, loss of raw materials and increase productivity, the second stage of ignition is carried out with alternating supply to the layer furnace gases and atmospheric air with a gas supply period of 20-80 s.