Optimization of the neutralization of Red Mud by pyrolysis bio-oil using a design of experiments approach

A factorial design and response surface approach has been employed to optimize the neutralization, partial reduction, magnetization and carbonization of highly alkaline Red Mud bauxite residues as derived from the Bayer process using highly acidic pyrolysis bio-oil as the limiting reagent. The impact of the factors temperature, reaction time and - most importantly - the minimum bio-oil/Red Mud ratio required was explored. The significant response parameters evaluated were the minimization of the sodium content and the quantity of the aqueous phase, the maximization of the carbon content and magnetization of the solid neutralized Red Mud phase as well as the stabilization of the pH of both phases close to 7. The optimum process parameters determined provide a starting point for a possible scale-up and suggest a potential pathway for the environmental remediation of Red Mud lagoons using a renewable biomass derived resource.

采用析因设计和响应面方法，以高酸性热解生物油为限制试剂，对拜耳法产生的高碱性赤泥铝土矿残渣的中和、部分还原、磁化和碳化进行优化。探讨了温度、反应时间以及最重要的所需最小生物油/赤泥比等因素的影响。所评估的重要响应参数包括钠含量和水相量的最小化、固体中和赤泥相碳含量和磁化强度的最大化以及两相的pH稳定在接近7。所确定的最佳工艺参数为可能的放大提供了一个起点，并为利用可再生生物质衍生资源对赤泥湖进行环境修复提出了一条潜在途径。