SU697583A1 - Method of producing fluxed iron ore pellets using conveyer machine - Google Patents

Description

The invention relates to a process for the preparation of iron ore for processing and blast furnaces and other metallurgical plants. A known method for producing pellets on a conveyor machine, including drying, heating, roasting, recovery and cooling 1. The disadvantage of this method is that the process of heating fluxed pellets in the temperature range of 600-1200 ° C is characterized by a low speed due to the negative thermal effect of carbonate decomposition (known , dolomite, etc.), requiring additional heat iodine and limiting the rate of heat transfer. In order to maintain the productivity of the conveyor machine at the same level, 40-50% of carbonates are decomposed in the heating zone, and in the remaining 50-60% in the burning, recuperation and even cooling zones. Delayed decomposition process. carbonates leads to incomplete absorption of calcium oxide and, therefore, reduces the strength of the pellets. The closest to the invention to the technical essence is the method of heat treatment of the ore-coating, which includes drying, heating, cooling the surface of the layer to 500-900 ° C, burning by burning the fuel in the layer at 1200-1350 ° C, recovery and cooling 2. The disadvantage of this method is that it is impossible to obtain fluxed, of the required quality at high productivity of the unit, due to the fact that the dissociation of carbonates in the burning zone at 1200-1350C proceeds at a low speed and slows down the burning process itself; Combustion of the fuel in the bed in the burning zone requires precooling of the surface with an oxylate layer, i.e. introduces an additional operation, reducing performance. The purpose of the invention is to intensify the process by completely decarbonizing the pellets in the preheating zone. The goal is achieved by the fact that the combustion of the fuel in the bed is carried out in the preheating zone in the area in the temperature range in the layer from 600 to 0.09-0.55 cc / s heat input and simultaneous removal of gaseous dissociation products 0.1-0. 6 g / s per 1 kg of pellets,

The limiting values of the parameters are determined by calculation for the charge: containing from 3 to 30% CaCOj, based on the fact that for decomposition of 1 gm CaCOd It is required to bring 425 kcal / g mol of heat and this is seen as 1 g mop CO.

The method was tested on pellets with a basicity of 1.4 with a lime content of 22%. Tests were carried out. On the installation of the type roasting bowl.

Example. The pellets are dried when blowing and blowing through the coolant, heated by blowing through the coolant and burning gas in the furnace. At a temperature above the layer and in the upper third of its 700 ° C, a gas-air mixture is introduced into the layer. Combustion of gas in the bed is carried out with a heat input of 0.12 kcal per 1 kg of octane and removal of gaseous dissociation products of 0.15 g / s per 1 kg of pellet. Upon reaching the bed-bed interface, the flow of gas-air mixture is stopped and they continue to heat the layer until, then they are fired at 1200–1250 s, recuperation until all the height of the layer is reached

1200 C and cooling.

The test results of fluxed iron ore pellets obtained by the proposed and known methods are presented in the table.

Duration

min

including drying

heating

cooling

surface

lay

burning.

recuperation

and cooling Specific gas consumption per process,

The strength of the pellets for crushing, kg / okat Varabanny indicator, fraction content,%

+5 mm

-5-0,5 mm

-0.5 mm

The content of fractions after recovery. %

FR, 5-0 mm: FR. +5 mm

The accomplishment of decarbonization of pellets in the preheating zone ensures the achievement of maximum oxidation rates in the range of 1000-1200 ° C and heat transfer in the burning zone at appropriate temperatures, and: 5.Also, silicate, ferrite and other compounds with calcium oxides in solid and liquid phases.

The implementation of the proposed method under the aforementioned conditions is carried out by installing any of the known gas-burning devices for feeding and burning gas in a layer in the preheating zone or devices for feeding other types of fuel to the bed,

The acceleration of the processes of heating and firing / and also the elimination of the operation of cooling the surface of the layer before firing (see table) will allow for 1531, 2 7.3 4.0

6.6 13.3 43.8

263

96.4 1.4 2.2

3.0 .97.0

18% increase in the unit productivity in the production of low-carbonates high-yield mixtures,

In the production of pellets from charge materials with a high carbonate content, due to their complete decarbonization in the preheating zone and the intensive formation of ferrites and calcium silicates in the burning zone, high quality pellets can be obtained without reducing the performance of the roasting machine.

Claims (2)

Invention Formula The method of producing fluxed iron ore pellets on a conveyor machine, including drying, heating, firing with fuel combustion in LT4 GTTT, characterized in that, in order to intensify the process by zoning; ogG from G to 5h; heat supply 0.09-0 55 CKYL / OAV and single kcal / s and simultaneous removal of gaseous dissociation products 0.1-0.6 g / s per 1 kg of pellets. kg of pellets. Sources of iLooi fii taken by Gwniman:; G Gak; pertise i. Yusfin Yu.S., Baeilevich G.N. M t alGuyiT - EG - 1si1lur1ii, la / j. 2. USSR author's certificate No. 497337, cl. From 22 to 1/16, 1976.