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低温协同捕收剂在铁矿石反浮选脱硅中的作用机制

Reaction Mechanism of Low-Temperature Synergistic Collectors in Reverse Flotation Desilication of Iron Ore

  • 摘要: 针对低温条件下阴离子捕收剂油酸钠(NaOL)因长碳链导致溶解性差、捕收性能受限,致使工业浮选需维持矿浆温度≥35℃而能耗高的问题,本文提出将短碳链癸酸钠(NaD)与NaOL复配,利用分子协同效应改善低温浮选效率。在10℃条件下系统考察了组合捕收剂配比、pH值、抑制剂用量等对磁铁矿和石英浮选行为的影响。结果表明,当NaOL与NaD摩尔比为8∶2、总用量20 mg/L时,单矿物浮选中石英回收率达91.12%,而磁铁矿回收率仅约4.46%,二者可浮性差异显著。在此基础上,对人工混合矿(磁铁矿与石英质量比3∶2)进行浮选分离试验,获得铁品位64.64%、回收率98.63%的精矿指标,较相同条件下单独使用油酸钠时品位和回收率分别提高12.24个百分点和8.86个百分点,实现了磁铁矿与石英的高效分离。Zeta电位、接触角、红外光谱及原子力显微镜(AFM)分析表明,NaOL与NaD在石英表面发生协同共吸附,NaD填充于NaOL团簇间隙,形成致密均匀的混合吸附层,显著增强石英表面疏水性并降低其表面电位,从而改善了低温下的捕收选择性。本研究通过分子结构互补策略有效解决了脂肪酸类捕收剂的低温适应性问题,为低温浮选工艺降本增效提供了新途径。

     

    Abstract: To address the issue that sodium oleate(NaOL),an anionic collector commonly used in reverse flotation,suffers from poor solubility and limited collecting performance at low temperatures due to its long carbon chain,which necessitates maintaining pulp temperature ≥35 ℃ in industrial flotation and significantly increases energy consumption,this study proposes a blending strategy of short-chain sodium decanoate(NaD) with NaOL to improve lowtemperature flotation efficiency through molecular synergistic effects. The effects of combined collector ratio,pH value,and depressant dosage on the flotation behaviors of magnetite and quartz were systematically investigated at 10 ℃. The results show that at a NaOL-to-NaD molar ratio of 8 ∶2 and a total dosage of 20 mg/L,the quartz recovery reaches 91. 12% in single-mineral flotation,while the magnetite recovery is only about 4. 46%,indicating a significant difference in floatability between the two minerals. Based on these conditions,flotation separation tests on artificially mixed ore(magnetite-to-quartz mass ratio of 3 ∶2) were conducted,yielding a concentrate with iron grade of 64. 64% and recovery of 98. 63%,which are respectively 12. 24 percentage points and 8. 86 percentage points higher than those obtained with NaOL alone under the same conditions,achieving efficient separation of magnetite and quartz. Zeta potential,contact angle,Fourier-transform infrared(FTIR) spectroscopy,and atomic force microscopy(AFM) analyses reveal that NaOL and NaD undergo synergistic co-adsorption on the quartz surface,where NaD fills the gaps among NaOL clusters to form a dense and uniform mixed adsorption layer,significantly enhancing the surface hydrophobicity and reducing the surface potential of quartz,thereby improving the collecting selectivity at low temperature. This study effectively overcomes the low-temperature adaptability issue of fatty acid collectors through a molecular structure complementarity strategy,providing a new approach to reduce costs and improve efficiency in low-temperature flotation processes.

     

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