Efficient separation of antimony oxide ore has always been a global challenge in the field of ore dressing. Antimony oxide resources are typically treated using gravity separation. However, the slurry of oxidized antimony ore after crushing and grinding poses a serious challenge, with a recovery rate of only around 20% in gravity separation operations, making it difficult to achieve comprehensive recovery. What can be done? This article introduces a successful case of a combined flotation and gravity separation process for antimony oxide ore.
We know that, in general, fine particle recovery is considered using flotation methods. However, due to the similar properties of gangue minerals and antimony oxide, it is challenging to separate them using flotation. Many antimony oxide projects are attempting to use flotation to increase recovery rates, and this case aims to serve as a valuable reference.
The sample has an antimony oxide content of around 50%, making it an antimony oxide ore. It contains 2.21% antimony, indicating high utility value. The antimony minerals exhibit uneven grain distribution, with coarse-grained sulfide antimony minerals reaching up to 3.9 mm, generally ranging from 0.05 to 0.25 mm. The antimony minerals have low hardness, are easily ground, and prone to over-grinding.
Based on the characteristics of this ore sample, after extensive exploration and experimental research, two test schemes that can adapt to the ore properties and achieve high ore dressing indicators have been selected as the main focus of this experiment.
Scheme 1: Gravity separation for the recovery of coarse-grained antimony oxide, flotation for the recovery of fine-grained antimony oxide.
Scheme 2: Ore grinding to 57.5%-0.074 mm, using CuSO4 and Pb(NO3)2 as activators, 25# Balck collector, and butyl xanthate as collectors, pine oil as a frother, carrying out flotation of sulfide minerals in a weakly acidic medium. Subsequently, recovering antimony oxide using a shaking table, and using flotation to recover fine antimony oxide.
The characteristics of the former process are a relatively complex process but with a high antimony recovery rate. It has been widely used in antimony oxide ore dressing. The latter process follows the ore dressing principle of "sulfur first, oxide later." Both test schemes have achieved good results. Upon analysis, the process of Scheme 1 is relatively complex but has a high antimony recovery rate, making it more suitable for the ore's nature and adhering to the ore dressing principle of "recover early if possible." Therefore, based on the main technical features of the ore sample, the "gravity separation - flotation" process is chosen: gravity separation to recover coarse-grained antimony oxide, flotation to recover fine-grained antimony oxide, namely, the process flow of "classification - jigging - shaking table - flotation" for antimony oxide ore dressing.
Stage 1: Classification, Jigging, and Shaking Table Sorting
The original ore is screened into -15 mm particles, and particles larger than 15 mm undergo crushing and additional screening until the particle size requirements are met.
The -15 mm antimony ore is further classified into three grades: 6-15 mm, 2-6 mm, and 0.25-2 mm, which enter jigging for sorting, resulting in Jigging Concentrate I, Jigging Concentrate II, and Jigging Concentrate III.
Using a shaking table to sort the 0.25 mm fraction, obtaining Shaking Table Concentrate.
Stage 2: Jigging and Shaking Table Tailings Further Classification and Shaking Table Sorting
Tailings (+2 mm) from jigging (i.e., Jigging Concentrate I and Jigging Concentrate II) are initially processed using a roll crusher. They are then combined with tailings (-2 mm) from jigging and shaking table (i.e., Jigging Concentrate III and Shaking Table Concentrate) for further grinding to 52%-0.074 mm.
The mixed tailings enter a classifier to separate into +0.28 mm, +0.074 mm (0.0740.28 mm), and -0.074 mm size fractions. The 0.0740.28 mm fraction undergoes shaking table sorting to obtain Shaking Table Concentrate, Middlings, and Tailings 1; the -0.074 mm fraction undergoes shaking table sorting to obtain Shaking Table Concentrate and Tailings 2; the 0.28 mm fraction, with low antimony content, is directly treated as Tailings 3.
Stage 3: Gravity Separation Tailings Flotation for Antimony Oxide Ore
Middlings (+0.074 mm) from the shaking table undergo further grinding to 98%-0.074 mm. They are then combined with tailings (-0.074 mm) from the shaking table and subjected to flotation for antimony oxide. The flotation of antimony oxide is a challenging aspect of this experiment, especially for fine-grained antimony oxide. Therefore, based on the principle of synergistic effects from the combined use of reagents and changes in the performance of certain reagents, superior results can be obtained by using moderately mixed reagent formulations for flotation.
The original ore, after screening, crushing, classification, jigging, and shaking table, followed by grinding and additional shaking table treatment, and finally, grinding of shaking table tailings and flotation, using the process flow of "classification - jigging - shaking table - flotation," results in antimony concentrate with a high recovery rate of 89.06%.
