絮凝剂对细粒铁精矿沉降效果的影响

摘要

In order to improve the problems of long settling time,low filtration rate,severe wear leakage phenomenon,low content in filter cake during thickening and dehydration for fine grained hematite concentrate. Effects of types and dosage of flocculants,slurry pH,temperature,and degree of mixedness on the sedimentation behavior were studied,using an iron concen-trate from Brazil as research object. The results indicated that:there were significant influence on sedimentation of hematite concentrate by adjusting flocculants addition,for too low addition have no obvious improvement on the sedimentation rate,with excessive addition could initiate colloid protecting,and the sedimentation velocity will not increase with dosage increase of floc-culants. Sodium polyacrylate flocculants have good settling performance in alkaline conditions,while polyacrylamide flocculants have good settling performance in acidic condition. Hypothermia have disadvantage in improving the sedimentation rate,hyper-thermia would lead to degradation of flocculants. Sufficient reversal and mixing was conducive to sedimentation,excessive mix-ing will worsen sedimentation effects. The results have important implications for suitable flocculant selection in iron concen-trate settling and improve the concentrate sedimentation.%为改善细粒赤铁矿精矿在浓缩脱水过程中存在的沉降时间长、过滤速率低、穿漏现象严重、滤饼含水率高等问题,以巴西某赤铁矿精矿为研究对象,考察了絮凝剂种类及用量、矿浆pH、温度及混匀程度等对赤铁矿沉降行为的影响. 结果表明:絮凝剂添加量对赤铁矿精矿沉降效果有显著影响,用量过低时,对改善沉降效果不明显,用量过高时会产生"胶体保护",沉降速率不再随絮凝剂用量增加而提高;聚丙烯酸钠类絮凝剂在酸性条件下对精矿的沉降效果好,聚丙烯酰胺类在碱性条件下沉降效果较好;温度较低时,不利于絮凝剂与矿物颗粒作用,沉降效果差,温度过高时,絮凝剂发生降解,沉降效果变差;翻转混匀次数少时絮凝剂分子分散不好,精矿沉降速率低,在充分混合时,细粒赤铁矿沉降速率达到最大值,进一步增加翻转混匀次数,会造成絮团断裂,精矿沉降速率降低. 试验结果对赤铁矿精矿沉降时选取合适的絮凝剂,提高精矿沉降效果具有重要意义.