Evaluation of grinding circuits for iron ore

Abstract Grinding has become one of the most important unitary operations for producing pellet feed for direct reduction from low-grade ores and small liberation size, such as compact itabirites. The aim of this study was to evaluate and compare two grinding circuits in an industrial iron ore plant, by evaluating the current operation through sampling, industrial data analysis and mass balancing. The flows analyzed were the grinding circuit, flotation throughput and desliming hydrocyclone overflow. In total, two grinding circuits were tested. One circuit had two mills installed in series, with the first mill operating in an open circuit and the second mill, in a reverse closed circuit. The second grinding circuit involved two mills operating in parallel, both in direct closed circuits. The results indicated that the parallel circuit produced 20% less slime than the series circuit, with an additional 4.3% throughput in the flotation feed. No circuit produced particles (> 0.15mm). The parallel circuit spent less 8.3% of energy by not using one of the hydrocyclone batteries.

摘要 磨矿已成为利用低品位矿石及嵌布粒度较细的原料（如致密铁英岩（itabirite））生产直接还原用球团给料的最为关键的单元作业之一。本研究旨在通过采样、工业数据分析与物料衡算对当前生产作业开展评估，以此对比某工业铁矿厂的两套磨矿流程。本次分析的流程涵盖磨矿回路、浮选处理量及脱泥旋流器溢流。共计测试了两套磨矿回路：第一套回路采用两台磨机串联配置，首台磨机采用开路磨矿，第二台磨机采用反向闭路磨矿；第二套磨矿回路采用两台磨机并联配置，两台均采用正向闭路磨矿。结果表明，并联回路较串联回路生成的矿泥量低20%，浮选给料处理量额外提升4.3%。两套回路均未产出粒径大于0.15mm的颗粒。并联回路因省去一组旋流器组，能耗降低8.3%。