| The price of high quality iron ore is going up year by year for the high-grade ore resource is becoming rare, in order to reduce cost, many iron and steel enterprise pay their attention on low grade ore that the storage is very large. However, low grade ore need to be ore grinding, beneficiation and some other flow to increase ore grade, high-grade ore, which come from low-grade ore after beneficiation, always is ore fines and can't be thrown into furnace to be smelted, we have to use it to produce pellets before smelting.Binder is very important material when producing pellet, without it pellet can't be produced or the quality of pellet is very low which can't satisfy smelting requirement, as a result, the equipment can't work normally. At present, the most popular binder is amargosite for its advantage such as good properties which can improve pellet's performance, big storage and low price. The average of addition amount in China is 2.5%, some special enterprises' addition is as much as 3.5%or higher than this number. However, amargosite contains large amount of SiCh, Al2O3 and some other inorganic substance which will reduce iron ore grade.Based on some know-how, when adding 1% of amargosite, the grade of ore will reduce 0.66%, the iron ore grade increase 1%, coke ratio will reduce 2% and the yield will increase 3%, so it is very important to find or develop some binder that can instead of amargosite or instead partly, which is a very important area for many college and R&D institution.Based on bonding mechanism of binder on the particle in pellets, our team have dealed with some material to get DHH series binder, DHH-1 and DHH-2 has their own character, so when dealing with them we design different process:DHH-lis just only to be added as binder to produce oxidized pellets; while DHH-2 is used to added as binder to produce oxidized pellets and carbon pellets, we have get some conclusion as follow:1) In the rolling process, DHH-1 composite binder's ability in improving pellet's compressive and drop strength isn't obvious, however, it can improve pellet's cracking temperature and oxidized pellets'compressive strength dramatically, without binder, cracking temperature and finish ball's compressive strength are 450? and 1670N/one, while when the addition amount is 1%, the cracking temperature is as high as 770?, the compressive strength can get 2798.6N/one, which increase nearly 320? and 1120N/one, respectively.2) DHH-2 composite binder can improve green ball's drop and compressive strength dramatically, when the addition is 0.4%, the drop and compressive strength of green ball are more than 6 times and 12N/one, although on this addition the cracking isn't the best(addition is 0.25%,cracking is 790?), it is higher than 600 ?,what more, the oxidized pellet's is about 2400N/one, which is a high level, so the addition of DHH-2 is 0.4%when produce oxidized pellets is a good choice.3) DHH-2 is adjusted to as binder to produce pellets containing carbon, when the addition is 0.5%,the drop strength of green ball containing carbon is 7.2 times and the compressive strength is 15.7N/one, and the cracking temperature is 630?, the pellets containing carbon in this addition can be metalized in non blast furnace to produce sponge iron.4) In compressing experiment, if just only adding amargosite, the improvement of drop strength isn't obvious, even if the addition amount is 2.5%, the drop strength is just 3.6 times, if just only adding DHH-2 composite binder, the cracking temperature of pellet containing carbon is generally low, by combing DHH-2 composite binder and amargosite, when the addition of DHH-2 is 0.35%and the addition of amargosite is 1%, which getting a precede combination for producing pellets containing carbon by compressing process comparatively, the drop strength of green-ball and dry-bulb are 8.2 times and 6.9 times, respectively, and the compressive strength are 107.6N/one and 284.1N/one, respectively, the cracking is as high as 640 ?. |
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