The earliest industrial application of high pressure grinding rolls (HPGR) at comminution was in 1984 in the cement industry. Since then, the equipment has been widely applied in mining activities. Despite the rapid spread across the industry, several challenges are still present in the equipment’s application, especially considering the complex ore breakage behaviour reported for this process. The pellet feed’s HPGR comminution was recognized as fundamental to efficiently increase the particle surface area (e.g., blaine specific area, BSA) at a lower energy and water consumption level (Chapman et al. in J Southern Afr Instit Mining Metall 113:407–413, 2013 ). The present study considers a novel milling process applying only HPGR as a re-regrind stage after concentration. The amount of successive ground product recirculation into the machine to achieve the required particle size for the pelletizing process was investigated. The study compared the ball wet milling process with the innovative processing technology for hematite–goethite ores. Green pellet balling and induration processes were simulated in bench and pilot scale. The milling results showed a considerably steep increase in BSA after each recirculation step into the HPGR, although compared with the ball-milled product the size fraction <45 μm% increased a modest five percentage points after three recirculation cycles, remaining steady until the last recirculation step. As a result, the green pellet generated presented higher concentration of pellets between 10 and 16 mm (%10-16 mm), with a higher drop number than typically observed when produced with ball-milled feedstock. Consequently, on the induration process, a higher pellet deformation was observed during the pot grate loading. Despite that, the fired pellets still presented an outstanding performance in cold crush strength (CSS) considered suitable to an industrial application.

中文翻译：

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闭路HPGR磨粉铁矿球团新工艺开发

高压磨辊（HPGR）在粉碎方面最早的工业应用是在 1984 年的水泥工业中。此后，该设备被广泛应用于采矿活动。尽管在整个行业中迅速普及，但该设备的应用仍然存在一些挑战，特别是考虑到该过程报告的复杂矿石破碎行为。颗粒饲料的 HPGR 粉碎被认为是在较低的能源和水消耗水平下有效增加颗粒表面积（例如，布莱恩比面积，BSA）的基础（Chapman 等人在 J Southern Afr Instit Mining Metall 113:407–413 ，2013 年）。本研究考虑了一种新的研磨工艺，仅应用 HPGR 作为浓缩后的再研磨阶段。研究了连续研磨产品再循环到机器中以达到造粒过程所需的粒度的量。该研究将球湿磨工艺与赤铁矿-针铁矿的创新加工技术进行了比较。以台架和中试规模模拟生球团成球和硬化过程。研磨结果显示，在进入 HPGR 的每个再循环步骤后，BSA 显着增加，尽管与球磨产品相比，<45 μm% 的粒度分数在三个再循环循环后适度增加了五个百分点，直到最后一次再循环保持稳定步。结果，产生的生球团在 10 到 16 毫米（%10-16 毫米）之间呈现出较高的球团浓度，具有比使用球磨原料生产时通常观察到的更高的滴数。因此，在硬化过程中，在锅篦加载期间观察到更高的颗粒变形。尽管如此，燃烧后的球团在冷压强度 (CSS) 方面仍然表现出出色的性能，被认为适合工业应用。