Process, technical measures and characteristics of small ball sintering technology

The ball sintering method is to mix iron concentrate, rich ore powder, solvent ( limestone or dolomite), returning ore, lime and a small part of solid fuel with water to form small pellets, and then mix the small pellets with the solid fuel and mix them. The small ball material is placed on the sintering machine by the segregation cloth method, and then ignited and sintered to produce a small ball sintered ore. The process flow is shown in the following process sequence.

(1) Preparation of raw materials for iron concentrates with a particle size requirement of less than 0.08 mm, 40% to 90%, solvent (limestone or dolomite) with a particle size of less than 3.15 mm, 80% or more, and lime (lime or hydrated lime), less than The content of 3.15mm accounts for more than 58%, and the content of solid fuel particles less than 3mm should account for more than 80%.
The problem of solid fuel particle size is a key issue. The sintering of the Fukuyama pellets in Japan requires that the particle size of the coke powder should be finely ground to less than 1 mm, while the coke powder size of the sintering plant in China is coarse, and the coke powder with a particle size of less than 3 mm generally accounts for about 80%. The practice of fine concentrate sintering in China proves that the particle size of coke powder is too fine, which is unfavorable to the quality and energy consumption of sinter. Fine grinding of coke powder not only has a high investment, increases costs, but also affects the operating rate. Therefore, the effect of fuel particle size on pellet sintering was studied firstly. The results show that the particle size effect of the common sintering method is better.
When the ingredients are mixed, the amount of the solvent is adjusted according to the alkalinity required by the blast furnace, the batching room is filled with a small amount of coke powder, and the rest is an iron-containing raw material.
(B) mixed ball according to the heat transfer analysis of the ball and the thermal characteristics of the sintering process, the particle size of the ball should not be too large, generally 3 ~ 12mm accounted for about 75%. To meet this requirement, two new technologies have been adopted:
(1) The original cylinder mixer of the sinter plant was transformed into a powerful cylinder mixing pelletizer, thereby solving the problem of pelleting. Specific technical measures are;
1) Adjust the inclination and rotation speed of the mixer to achieve the best condition. The purpose is to prolong the ball making time, increase the mixing speed of the mixture and improve the ball making effect.
2) Install a guiding device at the feeding end of the mixer to prevent the material from falling and leaking.
3) Install a reinforcing ball-and-ball stop device in the mixer. The device can avoid the occurrence of throwing of the mixture, and the mixture is in a state of forced rolling motion.
4) Install a multi-layer reinforced retaining ring at the discharge end of the mixer. The device has enhanced granulation and sieving of the finished ball. [next]
(2) Atomized water spray ball making technology is adopted in the cylinder mixer. In China, the water is added to the mixer, and the method of drilling on the pipeline is generally adopted to make the feed water flow. This method of adding water is not conducive to the sintering of the mixture into a ball. The mechanism of the sintering mixture is different from the pellet. The pellet needs to be first. Make the cue ball, add water to drop, that is, drip nucleation (cue ball). In the sinter mix, only the amount of returning minerals is about! (", plus some slag-rich powders and other coarse-grained raw materials, the nucleus of the spheroid is sufficient. Sintering the mixture into the ball is mainly to promote the nucleus as soon as possible. Growing up, the misty water is evenly distributed, which is obviously beneficial to the rapid growth of the core (cuebar). In addition, the mixing and mixing time of the mixer is very short, generally 1 to 3 minutes, and the water is added to the part by the flow-injecting method. When the water is dispersed and the ball is played, the mixture is almost removed from the discharge end of the mixer. Therefore, the flow-injection method is not conducive to the mixing of the balls into balls.
(3) Secondary distribution plus coke powder and mixing of small balls and coke powder Secondary addition plus coke powder can be based on the following conditions:
(1) The secondaryly-mixed coke powder is applied to a feed belt between the first and second mixers.
(2) The secondaryly blended coke powder is added to the optimum position in the second mixing by the belt conveyor from the two mixed discharge ends.
The first method is commonly used in production. Most of the coke powder is mixed into the mixture for the second time. The secondary coke powder and the small ball material from the one-time mixing ball machine all enter the second mixing. Ball machine, further mixing and pelletizing. Because there is a certain amount of small balls in the primary mixture, most of the coke powder is between the outer layer and the spheroid. The coke powder is fully burned, fast, and effective.
(4) Segregation fabric
The segregation of the cloth is to make the mixture disperse along the height of the layer, that is, the particle size of the upper part of the sintered layer is too small, and the particle size of the lower part is too large. This method of clothing can improve the gas permeability of the sinter layer and make the distribution of carbon in the layer more reasonable. In order to realize the segregation of the fabric, the existing mud roller and reflector plate distributor of the sintering plant is modified to make the fabric roller at an optimum height. By making necessary adjustments to the inclination and length of the reflector, and using the principle that the curve of the ball is faster, the shape of the reflector is appropriately changed, and the moving speed of the ball in the horizontal direction is increased. Since the diameter of the small ball is larger, the moving speed is faster, and therefore, it is advantageous to realize segregation of the cloth.
(5) After the ignition and sintering of the small ball material is discharged onto the sintering machine, ignition sintering is performed. Due to the new fuel addition technology, most of the coke powder is between the outer layer of the ball and the spherule, so that the small ball material is easy to ignite, and the ignition temperature is 50-100 ° C lower than the ordinary sintering method, which is beneficial to improve the sintering layer. Breathability. In addition, the small ball drying section is not provided on the sintering machine, which can reduce investment and increase the output of the sintering machine.
(6) Crushing, hot sieving, cooling, cold sieving and finished spheroid sinter The sinter sinter is crushed to below 130 mm by a shear-type single-roll crusher, and the sinter is sifted by a hot sieve. After the hot screening, the small ball sinter is cooled to below 150 ° C and then sieved and granulated to finally obtain the finished small ball sinter, and the product is directly sent to the blast furnace raw material warehouse as the ironmaking raw material of the blast furnace.
In summary, the main technical measures and features of the new process are as follows:
(1) There are no special requirements for sintering raw materials. The Japanese Fukuyama pellet sintering method requires fine grinding of the coke powder to 1 mm. The new process maintains the solid fuel particle size of the ordinary sintering method, which is expected to increase the operating rate and reduce the cost.
(2) Transforming the original cylinder mixer of the sinter plant into a powerful cylinder mixing pelletizer, which is convenient for the transformation of old equipment.
(3) The use of atomized water spray ball making technology improves the ball making effect.
(4) Using solid fuel addition technology, most of the fuel is in the surface of the small sphere or between the pellets, and better combustion results can be obtained.
(5) The segregation fabric technology is adopted to improve the gas permeability of the sintered layer.

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