铬铁矿球团焙烧固结特性

本文系统研究铬铁矿球团的焙烧固结特性.结果表明：预热时间对于预热球强度影响不大,在预热时间为10 min时,随着预热温度的提高,预热球强度和氧化率呈直线型增加,适宜温度为1050益,此时预热球强度可达每个400 N以上；与传统铁矿球团相比,铬铁矿球团焙烧所需的温度高,焙烧时间为10 min时,焙烧温度从1250益提高到1350益,球团强度从每个1078 N提高到1973 N.在铬铁矿球团预热和焙烧过程中,铬尖晶石( Fe,Mg)( Cr,Fe,Al)2 O4氧化生成富镁的( Fe,Mg)( Cr, Fe,Al)2O4和铬铁铝复合氧化物(Cr,Fe,Al)2O3,当温度高于1000益时,(Cr,Fe,Al)2O3新相生成,其主要以环状分布在颗粒外层,颗粒内部为针状与(Fe,Mg)(Cr,Fe,Al)2O4形成交织结构,降低Cr/Fe比或升高焙烧温度均有助于(Cr,Fe,Al)2O3向颗粒外层富集和再结晶长大,有利于球团的固结,提高球团强度.

Oxidation consolidation characteristics of chromite pellets during the roasting process

The roasting consolidation characteristics of chromite pellets were systematically studied in this paper. The results show that preheating time has little effect on the compressive strength of preheating chromite pellets. Under the appropriate preheating time of 10 min, increasing the preheating temperature can improve the compressive strength and oxidation rate of preheating chromite pellets linearly. The appropriate preheating temperature is 1050℃, at which the compressive strength of preheating chromite pellets can reach more than 400 N. In addition, compared with conventional iron ore pellets, a higher roasting temperature is required for chromite pel-lets. The compressive strength of chromite pellets increases from 1078 N to 1973 N when the roasting temperature increases from 1250℃ to 1350℃. During the preheating and roasting of chromite pellets, (Fe,Mg)(Cr,Fe,Al)2O4 is oxidized into (Fe,Mg)(Cr,Fe, Al) 2 O4 and ( Cr,Fe,Al) 2 O3 . The new phase ( Cr,Fe,Al) 2 O3 is obviously generated when the temperature surpasses 1000℃. ( Cr, Fe,Al) 2 O3 mainly distributes in the outer layer of the particles in a ring shape, while the acicular ( Cr,Fe,Al) 2 O3 interlaces together with ( Fe,Mg) ( Cr,Fe,Al) 2 O4 in the internal part. Decreasing the Cr/Fe ratio in the raw ore concentrate or increasing the roasting temperature can facilitate the aggregation of ( Cr,Fe,Al) 2 O3 around the outer layer of the particles, which in terms assists in the pellet consolidation and then enhances the compressive strength of chromite pellets.