粗细分级粒度对齐大山赤铁矿石分选效果的影响研究

齐大山铁矿选矿厂现场粗细分级旋流器给矿铁品位为32.43%,铁矿物在细粒级有明显的富集现象,而现场旋流器粗细分离粒度较粗(d₅₀=0.043 mm),沉砂产率较低,重选给矿量较少,磁选—反浮选流程给矿量较大,不利于生产成本控制和企业经济效益改善。为了确定适合现场的粗细分离粒度,以现场选别流程为基础,对d₅₀分别为0.036、0.025、0.020 mm情况下的溢流和沉砂进行了选别试验,并根据研究成果给出了工艺改造建议。试验结果表明,随着分离粒度d₅₀的降低,总精矿铁品位先小幅下降后降幅明显,总精矿产率和铁回收率先明显上升后维持在高位,重选精矿与总精矿产率之比大幅度上升;齐大山铁矿选矿厂粗细分离粒度d₅₀应从0.043 mm降至0.025～0.020mm。研究最终建议:选矿厂在对粗细分离粒度d₅₀进行优化的同时,通过实现螺旋溜槽粗选作业的3产品模式,让终将进入磁选—反浮选系统的微细粒铁矿物及粗粒脉石矿物尽早进入该系统,以改善重选作业的环境和效果;取消重选中矿中磁选抛尾作业,充分实现铁矿物连生体的单体解离度,改善铁矿物的回收效果。推荐流程突出了重选系统的地位,强化了重选系统的优势,减轻了磁选—反浮选系统的压力,有望实现选矿厂经济技术指标的全面好转。

Influence of Coarse and Fine Fractions Classification Size on Beneficiation of Qidashan Hematite Ore

The iron grade of feeding to coarse and fine fraction classification hydrocyclone was 32.43% in Qidashan Iron Concentrator. Some features， including obvious enrichment of iron minerals in fine fraction， the coarser cut size of coarse and fine fraction （d50=0.043 mm）， lower yield of underflow， less feeding of gravity concentration， and larger feeding of magnetic separation-reverse flotation process， led to higher production cost. Beneficiation tests were conducted with d50 of 0.036 mm， 0.025 mm and 0.020 mm respectively， in order to determine the suitable classification size of coarse and fine fraction classification. Suggestions for technological improvement were given accordingly. The results show that， with the decrease of d50， the iron grade of total concentrate decreases slightly at first and then obviously， while the yield and iron recovery increase obviously at first and then keep in a higher level， the ratio of gravity concentrate to total concentrate increases substantially. The cut size d50 should be suitable of 0.025-0.020 mm from 0.043 mm for the coarse and fine fraction classification of Qidashan Iron Concentrator. The final suggestion is that， while optimizing the d50 of coarse and fine fraction classification， fine iron minerals should be fed into magnetic separation-reverse flotation process as soon as possible by realizing the three-product model of the roughing spiral. Medium intensity magnetic separation for tailings discarding should be abolished， to improve the liberation degree and recovery of iron minerals. In the recommended process， the advantage of gravity concentration process is intensified， and the pressure of magnetic separation-reverse flotation process is lightened， a clear improvement of technical-economical index should be promising.