Lihu Liu, Jiahe Shi
Wuqi Oil Production Plant, Yanchang Oilfield Co., Ltd, Yan'an, China.
Bristol Business School, University of Bristol, Bristol, United Kingdom.
PLoS One. 2025 Aug 29;20(8):e0331415. doi: 10.1371/journal.pone.0331415. eCollection 2025.
Northern Shaanxi's oil-gas drilling produces large amounts of waste drilling fluids with high-value solids (barite, bentonite). Traditional disposal causes resource waste and pollution. This study proposes a stepwise flotation process for typical local oil-based waste: surface cleaning to break oil film wrapping and combined reagents to regulate mineral surface hydrophobicity differences, enabling efficient separation and recovery of barite and bentonite. The flotation mechanism is also preliminarily explored. The experimental results show that: ultrasonic cleaning with 0.5% sodium dodecyl sulfate (SDS) solution makes the oil desorption rate of solid phase >95%, restoring the natural surface properties of minerals. Through the stepwise flotation design, in the first stage at pH = 4.0, 0.8 kg/t sodium dodecyl sulfate and 0.6 kg/t sodium hexametaphosphate are added, and the recovery rate of bentonite reaches 86.3%; in the second stage at pH = 8.0, 1.2 kg/t sodium dodecyl sulfate and 0.7 kg/t gellan gum are added, and the grade of barite concentrate is 92.1% (BaSO₄ content), with a recovery rate of 88.7%. Through the flotation closed-circuit experiment, using the process of "one roughing, two cleaning and three scavenging", the first stage can obtain bentonite concentrate with a recovery rate of 91.4% and a grade of 91.5%; the second stage can obtain barite concentrate with a recovery rate of 90.2% and a grade of 92.1%. SEM shows that bentonite is dissociated lamella, and barite presents clean prismatic crystals without oil film impurities, verifying the high efficiency of separation. Mechanism studies show that SDS has dual functions of oil breaking and collecting. Sodium hexametaphosphate inhibits the flotation of barite by chelating Ba²⁺ in barite. Gellan gum realizes separation by shielding the active sites of bentonite through hydrogen bonds. This study provides an efficient and low-consumption solution for the resource utilization of drilling waste liquid in northern Shaanxi.
陕北油气钻探产生大量含高价值固体（重晶石、膨润土）的废钻井液。传统处置方式造成资源浪费和污染。本研究针对当地典型油基废弃物提出一种分步浮选工艺：进行表面清洗以破除油膜包裹，并使用复合药剂调节矿物表面疏水性差异，从而实现重晶石和膨润土的高效分离与回收。同时对浮选机理也进行了初步探索。实验结果表明：用0.5%十二烷基硫酸钠（SDS）溶液进行超声清洗，使固相的油脱附率>95%，恢复了矿物的天然表面性质。通过分步浮选设计，第一阶段在pH = 4.0时，添加0.8 kg/t十二烷基硫酸钠和0.6 kg/t六偏磷酸钠，膨润土回收率达到86.3%；第二阶段在pH = 8.0时，添加1.2 kg/t十二烷基硫酸钠和0.7 kg/t结冷胶，重晶石精矿品位为92.1%（BaSO₄含量），回收率为88.7%。通过浮选闭路实验，采用“一粗、两扫、三精”工艺，第一阶段可获得回收率为91.4%、品位为91.5%的膨润土精矿；第二阶段可获得回收率为90.2%、品位为92.1%的重晶石精矿。扫描电子显微镜（SEM）显示膨润土呈解离片状，重晶石呈现干净的棱柱状晶体且无油膜杂质，验证了分离的高效性。机理研究表明，SDS具有破乳和捕收双重作用。六偏磷酸钠通过螯合重晶石中的Ba²⁺抑制重晶石浮选。结冷胶通过氢键屏蔽膨润土的活性位点实现分离。本研究为陕北钻井废液的资源利用提供了一种高效低耗的解决方案。
