Gemini型含酯基胍盐阳离子捕收剂制备及其对磁铁矿浮选性能研究

Preparation of Gemini Type Ester−containing Guanidine Salt Cationic Collector and Study on Its Flotation Performance for Magnetite

    摘要
  • 摘要: 为解决传统捕收剂功能单一、难以满足多金属矿或复杂矿石高效浮选需求以及在浮选过程中对环境造成二次污染的问题，以溴代十二烷、1，1，3，3−四甲基胍、丁二酸和环氧氯丙烷为原料，合成一种新型含酯基连接基团的Gemini型十二胍盐阳离子捕收剂（C12−2−C12）。通过吊环法测定25 ℃时C12−2−C12表面张力为25.10 mN/m，其临界胶束浓度(CMC)（0.01 mmol/L）显著低于单链十二烷基胍（5.01 mmol/L），泡沫稳定性达到74.79%，C12−2−C12乳化性能优异，分出10 mL水所需时间为313 s。实验过程中系统评估了C12−2−C12作为磁铁矿反浮选捕收剂的捕收性能，结果表明，在单矿物浮选实验中，当pH=7、捕收剂浓度为0.3 mmol/L时，C12−2−C12对石英表现出良好选择性，且回收率达87.6%，显著高于十二烷基胍对石英69.46%的回收率。在针对磁铁矿实际样品浮选实验中，在pH=7、捕收剂用量为320 g/t、抑制剂苛性淀粉用量为250 g/t条件下，一次反浮选获得铁品位为67.58%、回收率为76.35%的铁精矿。在生物降解实验中，采用振荡培养法研究了C12−2−C12的生物降解性能，在40 d时，C12−2−C12和十二烷基胍最终的降解率分别为52.12%和44.56%，表明C12−2−C12的生物降解性能优于十二烷基胍。与传统单链捕收剂（生物降解能力为30%）和Gemini季铵盐捕收剂（生物降解能力为26%）相比，具有更优异的环境友好性。最后，对合成的C12−2−C12捕收剂的捕收机理进行分析，红外光谱和Zeta电位测试结果表明，该捕收剂主要与石英表面产生静电吸附作用，对磁铁矿表面几乎无作用。量子化学计算进一步表明，C12−2−C12具有较强的正电性，通过石英提供电子占据C12−2−C12最低空分子轨道，进而与石英表面发生相互作用。由此可见，C12−2−C12是一种优良的磁铁矿反浮选捕收剂，同时具有良好的生物降解性。

     

    Abstract: Traditional collectors often suffer from limited functionality, rendering them inadequate for meeting the flotation requirements of polymetallic or complex ores. Moreover, they frequently causes sencondary polution to the environment during the flotation process. Bromododecane, 1, 1, 3, 3−tetramethylguanidine, succinic acid and epichlorohydrin were used as raw materials to synthesize a new type of Gemini dodecanidine salt cationic collector (C12−2−C12) featuring an ester bond linkage. At 25 ℃, C12−2−C12 exhibits a surface tension of 25.10 mN/m. Notably, its critical micelle concentration (0.01 mmol/L) is significantly lower than that of single−chain dodecyl guanidine (5.01 mmol/L). The foam stability of C12−2−C12 reaches 74.79% with a water separation time of 313 seconds for 10 mL of water, exhibiting outstanding emulsification performance. The collection performance of C12−2−C12 as a magnetite reverse flotation collector was systematically evaluated during the experiment. The results show that the single mineral simulated flotation tests reveal that C12−2−C12 show excellent selectivity towards quartz at pH=7 and a collector concentration of 0.3 mmol/L. Under these conditions, the quartz recovery rate achieved with C12−2−C12 is 87.6%, which is significantly higher than the 69.46% recovery rate obtained with dodecylguanidine. In the reverse flotation of actual magnetite ore samples at pH=7, with a collector dosage of 320 g/t and an inhibitor (caustic starch) dosage of 250 g/t, the concentrate grade reaches 67.58%, with a recovery rate of 76.35%. In the biodegradation experiment, the biodegradability of C12−2−C12 was investigated using the shaking culture method. After 40 days, the final degradation rates of C12−2−C12 and dodecylguanidine are 52.12% and 44.56%, respectively. In comparison to traditional single−chain collectors (with a biodegradability of approximately 30%) and Gemini quaternary ammonium salt collectors (with a biodegradability of around 26%), C12−2−C12 demonstrates superior environmental friendliness. Finally, the collection mechanism of the C12−2−C12 collector synthesized in this study was analyzed. Results from infrared spectroscopy and Zeta−potential tests indicate that the adsorption of the collector on the surfaces of quartz is mainly eiectrostatic adsorption and and it has almost no effect on the surface of magnetite. Quantum chemical calculations further reveal that C12−2−C12 carries a strong positive charge and interact with the quartz surface by donating electrons to the lowest molecular orbital of C12−2−C12 through quartz. In conclusion, C12−2−C12 proved to be an excellent reverse flotation collector for magnetite, exhibiting favorable biodegradability.

     

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