含碳球团还原熔分综合利用硼铁精矿新工艺

基于硼铁矿资源综合利用的现状和转底炉珠铁工艺的基本特点, 提出了含碳球团还原熔分综合利用硼铁精矿的新工艺。在实验室条件下, 以硼铁精矿和碳质还原剂为原料, 系统研究了焙烧温度、配碳量(C/O摩尔比)、还原剂种类、熔融保持时间等因素对球团还原熔分过程的影响, 以及熔分产物的基本特性。试验结果表明: 焙烧温度过高或过低均不利于熔分; 提高配碳量有助于缩短还原熔分时间; 煤灰熔点对熔分有较大影响; 随着熔融保持时间的延长渣中FeO含量降低。优化的工艺参数为: 以无烟煤为还原剂, 配入量为C/O=1.2, 焙烧温度为1 400 ℃, 焙烧时间为15 min。此时, 渣铁分离彻底, 得到含硼元素0.065%的纯净珠铁和B₂O₃品位为20.01%的富硼渣, 珠铁中铁的收得率在96.5%以上, 富硼渣中硼的收得率在95.7%以上。经缓冷处理, 富硼渣主要由遂安石和橄榄石两相组成, 活性达86.46%。含硼珠铁和富硼渣分别是钢铁和硼化工工业的优质原料, 该工艺可为我国低品位硼铁矿的综合利用提供一种新思路。

New Technology for Comprehensive Utilization of Boron-Bearing Iron Concentrate by Reduction and Melting-Separation of Carbon-Containing Pellet

According to the current situation of paigeite utilization and basic characteristics of iron nugget production in rotary hearth furnace(RHF), a novel technology was proposed for comprehensive utilization of boron-bearing iron concentrate by reduction and melting-separation of carbon-containing pellet. In the lab test, with boron-bearing iron concentrate and carbonaceous reducing agent as raw material, effects of those factors including temperature, carbon content(C/O mole ratio), reducing agents and duration of melting process on processes of reduction and melting-separation for the pellet, as well as properties of products from melting-separation were all thoroughly investigated. Test results show that both too high and too low temperature were not favorable to the melting-separation process, while increasing carbon content could help shortening reduction and melting-separation time. Ash fusion point can bring a big difference on the melting-separation effect. The FeO content in the slag decreased with the duration of melting-separation process being prolonged. Under the following optimal conditions, that is, by using anthracite as reducing agent with C/O of 1.2, iron could be completely separated from slag after 15 mins of reduction at a reduction temperature of 1 400 ℃, yielding a nugget containing 0.065% boron with iron recovery over 96.5%, and the boron-rich slag grading 20.01% boron oxide with boron recovery over 95.7%. After slow-cooling process, boron-rich slag was mainly composed of suanite and olivine, with efficiency of boron extraction up to 86.46%. Both boron-bearing nugget and boron-rich slag are good raw materials for metallurgy and boron industry. This new technology can provide reference for comprehensive utilization of low grade paigeite in China.