矿山酸性废水中和处理工艺优化研究
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摘要
采用石灰中和酸性废水的矿山普遍存在氧化钙反应不彻底、污泥沉降性能不理想问题。为了提高氧化钙的利用效率、改善污泥的沉降效果,以某铜矿环保车间的废水为试样,进行了氧化钙直接中和废水工艺条件研究和污泥回流+氧化钙中和废水工艺条件研究。结果表明:①在氧化钙用量为24 g/L、消化时间为20 min、搅拌速度为400 r/min情况下进行氧化钙直接中和试验,反应75 min的料浆p H>6。②在污泥(pH>6)回流比例为40%、氧化钙用量为22.0 g/L情况下进行废水中和,也可将废水的pH调至6以上,且废水中金属离子浓度得到大幅度下降,满足送尾矿库储存的要求。③污泥的回流不仅可以充分利用其中未反应的氧化钙,减少新添氧化钙的用量,还可以改善污泥的沉降性能、提高污泥的固含量,有利于尾矿库回水的澄清。
Lime neutralization is a common method for the treatment of mine acid drainage,whereas the performance of this process is often not so good as expected due to the problems of incomplete reaction of calcium oxide and poor settling property of sludge. In order to tackle these problems,the comparison study between direct neutralization by calcium oxide and sludge reflux + calcium oxide neutralization was performed on the wastewater from a copper mine. The results show that when the calcium oxide dosage was 24 g/L,calcium oxide slaking time was 20 minutes and stirring rate was 400 r/m,the pH value of sludge could reach over 6 after 75 minutes by direct neutralization. The pH value of wastewater can also reach over 6 when wastewater was neutralized with sludge(pH>6) with reflux ratio of 40% and calcium oxide dosage of 22.0 g/L,the concentration of metal ions was greatly reduced,meeting the requirements of tailing pond storage. The sludge reflux process could not only make good use of the unreacted calcium oxide to reduce the amount of new calcium oxide,but also improve the settling property and solid content of sludge,which are good for the clarification of the backwater of tailings pond.
Lime neutralization is a common method for the treatment of mine acid drainage,whereas the performance of this process is often not so good as expected due to the problems of incomplete reaction of calcium oxide and poor settling property of sludge. In order to tackle these problems,the comparison study between direct neutralization by calcium oxide and sludge reflux + calcium oxide neutralization was performed on the wastewater from a copper mine. The results show that when the calcium oxide dosage was 24 g/L,calcium oxide slaking time was 20 minutes and stirring rate was 400 r/m,the pH value of sludge could reach over 6 after 75 minutes by direct neutralization. The pH value of wastewater can also reach over 6 when wastewater was neutralized with sludge(pH>6) with reflux ratio of 40% and calcium oxide dosage of 22.0 g/L,the concentration of metal ions was greatly reduced,meeting the requirements of tailing pond storage. The sludge reflux process could not only make good use of the unreacted calcium oxide to reduce the amount of new calcium oxide,but also improve the settling property and solid content of sludge,which are good for the clarification of the backwater of tailings pond.
引文
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[7]林倩,曾祥饮,刘定富,等.絮凝沉降的温度效应[J].贵州大学学报:自然科学版,2006(3):272-274.Lin Qian,Zng Xiangyin,Liu Dingfu,et al.The effect of temperature on flocculation settling[J].Journal of Guizhou University:Natureal Sciences,2006(3):272-274.
[8]焦华喆,王洪江,吴爱祥,等.全尾砂絮凝沉降规律及其机理[J].北京科技大学学报,2010(6):702-707.Jiao Huazhe,Wang Hongjiang,Wu Aixiang,et al.Rule and mechanism of flocculation sedimentation of unclassified tailings[J].Journal of University of Science and Technology Beijing,2010(6):702-707.