The recovery of chromite from the tailings streams of South African UG2 platinum concentrators adds significant financial returns to these operations. Whilst the coarser fractions are amenable to processing by physical separation, the focus is now also on the recovery of fine (typically −75 µm) chromite by flotation.

This paper describes the results of a series of physical separation, and chromite bench flotation tests that have been carried out at acidic and natural pH respectively, on UG2 tailings from Pilanesberg Platinum Mines (PPM) on the western limb of the Bushveld Complex in South Africa. The objective of the work is to find a route that would best produce, from a feed assaying around 18 % Cr₂O₃ and with 50 % of the chromite in the −38 µm fraction, a concentrate of at least 40 % Cr₂O₃ and an overall yield of more than 13 %.

Results showed that shaking tables and wet high intensity magnetic separation (WHIMS) alone were not capable of upgrading the tailings to the target grade. However, flotation tests at a pH of 2.5 on a sample that was deslimed at 10 µm by cycloning, as well as a sample that was screened at 25 µm and subjected to WHIMS, demonstrated that a product assaying 42 % Cr₂O₃ could be attained at yields between 8 and 11 %, with recoveries ranging between 19 and 27 %. The results highlighted the importance of desliming prior to flotation, in reducing the dosage of the Flotinor V-2711 collector by more than 60 %.

Subsequent flotation tests at natural pH on hot tailings samples with two stages of cleaning showed good upgrading, where a feed grade of 16.1 % Cr₂O₃ after desliming was converted to a concentrate of 29.4 % Cr₂O₃ at a yield, based on deslimed feed, of 28.6 % and a recovery of 52.4 %. The overall upgrade ratio in this case of 1.83 was slightly lower than those of the acidic tests (i.e., 1.87 and 2.31 respectively) but also at lower yields (28.6 % vs 33 %) and recoveries (52.4 % vs 62 %). Further work is underway to investigate various flowsheet options, including the flotation of fines spiral concentrates, staged collector addition to the cleaning stages, and froth washing.

从南非 UG2 铂金选矿厂的尾矿流中回收铬铁矿为这些业务增加了可观的财务回报。虽然较粗的部分可以通过物理分离进行处理，但现在的重点还在于通过浮选回收细小的（通常为 -75 µm）铬铁矿。

本文介绍了一系列物理分离和铬铁矿台架浮选试验的结果，这些试验分别在酸性和自然 pH 值下对南非布什维尔德综合体西部边缘匹兰斯堡铂矿 (PPM) 的 UG2 尾矿进行. 这项工作的目的是找到一条最好的路线，从测定约 18 % Cr ₂ O ₃的进料和 -38 µm 馏分中 50 % 的铬铁矿中生产至少 40 % Cr ₂ O的精矿₃，总收率超过13%。

结果表明，仅靠振动台和湿式高强度磁选 (WHIMS) 无法将尾矿提升至目标品位。然而，在 pH 值为 2.5 的情况下，对通过旋流在 10 µm 处脱泥的样品以及在 25 µm 处筛选并进行 WHIMS 的样品进行的浮选测试表明，测定 42% Cr ₂ O ₃的产品可以收率在 8% 到 11% 之间，回收率在 19% 到 27% 之间。结果突出了浮选前脱泥的重要性，它将 Flotinor V-2711 捕收剂的用量减少了 60% 以上。

随后在自然 pH 条件下对热尾矿样品进行了两阶段清洁的浮选测试显示出良好的提质效果，其中脱泥后 16.1 % Cr ₂ O ₃的进料品位以收率转化为 29.4 % Cr ₂ O ₃的精矿，基于脱泥饲料，28.6 % 和 52.4 % 的回收率。在这种情况下，整体提质率为 1.83，略低于酸性测试（即分别为 1.87 和 2.31），但产率（28.6% 对 33%）和回收率（52.4% 对 62%）也较低。正在进行进一步的工作以研究各种流程选项，包括细粒螺旋精矿的浮选、在清洁阶段添加分级收集器和泡沫洗涤。