SU954458A1 - Method for preparing limestone for agglomeration - Google Patents

Description

The invention relates to the preparation of lime for the sintering process and can be applied in ferrous metallurgy.

The known method of preparing limestone for the sintering process, which includes crushing of the initial limestone in hammer mills to a fraction of 0-30 mm, its classification on vibrating screens with the separation of classes -3 and +3 mm. Class -: 3 mgl is used in the sintering mixture, a class of more than 3 mm is directed to the addition of Cll. This method does not allow for the production of lime required for the agglomeration from the initial limestone.

The closest to the proposed technical essence and the achieved result is a method of preparing limestone for the sintering process, including crushing the original limestone in hammer crushers to a fraction of 0-30 mm, its classification on vibrating screens with a separation of -3 mm, re-classification of the product H - 3 mm on the vibrating screen with a grade of 3–12 mm and addition of limestone of a class + 12 mm. The resulting fraction, lime tea 0-3 mm is sent to aglopress, the fraction 3-12 mm is fired in a fluidized bed furnace. Produced lime is used in the sintering process 2.

The disadvantage of this method is the practical impossibility of obtaining the required ratio between the limestone classes to be released under the condition of a balanced agglomeration supply with a limestone of 3 mm class and a fraction, for example, 3-12 mm.

- for firing. Upon receipt of the required amount of a fraction of -3 mm,

15 lack of limestone class 3-12 mm and vice versa - when you get the right amount of limestone fraction 3-12 mm, an excess of -3 mm class is observed, not intended for use as

20 in the agro-process, and in general at the metallurgical plant.

The purpose of the invention is to increase the degree of use of the initial limestone and the efficiency of the sintering process.

The goal is achieved by TeJMj. According to the method of preparing limestone for the sintering process, which includes crushing of the initial limestone, primary classification, secondary classification with separation of fractions used to produce lime, in the initial classification. The fraction is (3-5) mm. sowing, separating the -2 mm fraction into the gas phase and +2 mm for unloading from the aerodynamic sieving apparatus, and secondary classification separating a fraction (3-10) mm, which is mixed with the product discharged Arata aerodynamic screening.

The developed method has several advantages over the known ones, the main ones being the following.

The separation in the primary classification (3-5 mm), e.g. -4 mm, leads to an increase in the degree of separation of the fraction -3 mm, which leads to a decrease in the circulation flow of hammer mills and, therefore, saves energy consumed in the process. The lower limit of the separated fraction is determined by the requirements of the agglomeration process, the upper one by the efficiency of the subsequent conversion — aerodynamic separation. A further increase in the upper limit, for example, to 8-10 mm, leading to an increase in the degree of release of the -3g1M fraction to almost 100%, will increase the costs in the process of aerodynamic separation, roughly proportional to the square root W3 ratios of the above diameters.

The introduction of the developed method of aerodynamic sieving pursues two goals more fully to exclude from the limestone used in the charge fractions of 3 mm and to increase the proportion of limestone sent for roasting by transferring to the agloprocessor limestone a fraction of 2 mm. This operation will completely eliminate the white in the agglomerate so that it will improve its quality. In the methods of preparing limestone for the sintering process currently used, for a number of reasons, the content of the +3 mm fraction reaches 13% or more on certain days. In addition, the developed method makes it possible to isolate the fraction 0-iOO µm from the mass of lime fraction of -2 mm, using it to roll on the granules of the charge.

The process of aerodynamic sieving involves the separation of the fraction - (3-5) mm into two, the release of particles in the gas phase is less than 2 mm. The choice of this size is due to economic factors, since a further increase in the size of particles leaving the gas phase will lead to excessive costs for obtaining compressed air. So, for discharge to gas,

a phase of particles of -1 mm requires 200 m of air per ton of the product obtained, with the release of 2 about 400, etc.

The separation in the secondary classification of fractions in the range of 3-10 mm is dictated by considerations of an increase in the proportion of lime used for firing.

The last operation of the developed method, the mixing of fractions, is carried out in order to increase the proportion of limestone used for firing.

The drawing shows the flow chart for the implementation of the proposed method.

It includes the initial limestone bunker 1, a crushing compartment (or crusher) 2, a vibrating screen 3 of the primary classification, a vibrating screen 4 of the secondary classification, an aerodynamic screening system with a bunker 5, a boiling bed 6, a cleaning air cleaning system 7. The conveyor system 8-11 directs limestone to firing, conveyor 12 is known to the charge section of the sinter plant.

The operation of the circuit is as follows.

The initial limestone, for example, fractions 40-80 mm is fed to the hopper 1 and from them to the crushing section 2 After the drills, the material of the 030 mm fraction is directed to the vibrating screen of the primary classification 3, where the fraction 0-5 mm is released. A fraction of 0-5 mm is directed to the aerodynamic separation system, and a fraction of +5 mm is fed to the screen of the secondary classification 4. It contains limestone fractions 5-8: 8-12, 12-20 and more than 20 mm. The second and third of these fractions are sent to the conveyors 10 and 11 and further to the calcination, the latter is returned for crushing to the crushing section. The limestone fractions 8–12, 12–20 mm after calcination are sent to the preparation department of the sinter plant.

In the sowing system, a lime fraction of 0-5 mm is divided into fractions of 0-2 mm and 2-5 mm. The first of them is carried away by the air fluidizing the LAYER in the apparatus 6, is separated in the cleaning system 7 and conveyed by the conveyor 12 to the charge compartment of the sintering plant. The material of the 2-5 mm fraction, discharged from apparatus 6, is fed to the conveyor 9. After displacement, a fraction of 2-8 mm is formed on the conveyor, which is sent for firing. Lime formed after burning is fed to the charge department of the sinter plant.

As a result of the firing scheme, limestone to fraction

2-20 mm, divided into classes. In order to obtain high quality lime from this material at a reduced cost, it is advisable to burn each of the limestone classes independently. In this case, in the firing department of the sintering plant there are several lines of firing apparatus operating on the limestone of a certain particle size distribution. KS furnaces, rotary kilns, and KM-14 type machines can be used as kilns.

Example: To maintain the sintering process, the charge is introduced

80 kg of lime (per tonne of sinter) and 180 kg of limestone fraction -3 mm. At the same time, the limestone preparation department for each ton of sinter should produce:

limestone fraction -3 mm 180 kg,

limestone fraction 3–20 mm for roasting lime, divided into a number of classes, 150 kg.

Hammer crushers, working in a closed cycle and processing lime to the Elenovsky deposit of 40-80 mm, provide ground limestone, the particle size of which

following (see table):

Claims (2)

In the initial classification of 100 to crushed material, 63 to a fraction of -5 mm was isolated. The -5 mm fraction is sent to the aerodynamic sieving system, where 42.4 kg of the -2 mm fraction, which is sent to the charge, and 20.6 kg of the 2-5 mm fraction are obtained. The latter is mixed with a fraction of 5–8 mm obtained in the secondary classification, and 25.6 kg of lime of a fraction of 2–8 mm is obtained, which is sent for firing. The +5 mm fraction is subjected to secondary classification, during which fraction 5- is separated. 8 mm in an amount of 5 kg and a fraction of 8-20 mm in an amount of 8.6 kg and direct it to roasting. A fraction of +20 mm in an amount of 23.4 kg is sent to tia dredging. In total, in the course of work of the preparation department, according to the proposed method, fractions 0-2 mm - 42.4 kg. This material is sent to the charge department of the sintering plant and is introduced into the total charge without pretreatment, Fractions 2-8, 8-20 mm - 34.2 kg. This product is calcined and used in the form of lime. The percentage of the -2 mm fraction is 55%, the fractions 220 mm 45%. This ensures the use of the original inverter without waste. The implementation of the method will allow reducing the costs of the peripheral metallurgical lime and improving the quality of the agglomerate by eliminating undigested lime particles in it. Claims method of preparing limestone for sintering process, including crushing of initial limestone, primary classification, secondary classification with separation of fractions used for lime production, characterized in a fraction of - (3-5) mm is allocated to the primary classification, the resulting product is subjected to aerodynamic sieving, a -2 mm fraction is separated into the gas phase and +2 mm for discharge from the apparatus erodynamic sieving, and in the secondary classification, a fraction (3–10) mm is mixed, which is mixed with the product discharged from the aerodynamic sieving unit. F., Aglomeratsi, M., Metallurgists, 1968, p. 368, 2. Nehlebaev Yu.P., and Puzovsky E, B, Sat, High-temperature endothermic processes in a fluidized bed, M., Metallurgists, 19S8, s, 285-297, / Source