铜熔渣喷吹地沟油还原贫化

Reduction and dilution of melting copper slag by blowing waste cooking oil

以地沟油为生物质还原剂,高温裂解后对铜火法冶炼铜渣进行还原贫化。结果表明,地沟油裂解产物主要是C,H2,CO和CH4等还原性小分子物质,1373, 1473和1573K下裂解积碳的转化率分别为78.36%,79.83%和80.07%,因此地沟油高温裂解时碳元素主要以积碳形式存在。热力学计算发现,高温下裂解产物均有良好的还原Fe3O4的活性,用地沟油替代传统化石类还原剂还原铜渣中磁性铁在热力学上是可行的。以N2为载气不仅有利于高温下地沟油顺利喷入铜熔渣中,且通过动量传递起到搅拌熔渣的作用,增大了微小铜滴碰撞聚集长大的机会。在熔炼温度1573K、载气流量3L/min、地沟油喷吹量2.055mL/min、喷吹时间4min、沉降时间50min的最优还原贫化条件下,铜渣中Fe3O4含量从33.40wt%降至1.60wt%,含铜量从4.49wt%降至0.49wt%,渣中Fe3O4相转变为2FeO·SiO2相。根据Einstein-Roscoe方程分析,渣中Fe3O4含量减少有利于降低熔渣粘度,改善铜滴的沉降条件。继续增加地沟油喷吹时间沉降金属中杂质含量增加;沉降时间过长时,由于铜渣对铜的机械夹带和化学溶解作用,沉降效果不会更好。实验的铜回收率达89.09%。

Waste cooking oilis a kind of biomass energy that has not been used very well.In this work, waste cooking oil was used as reducing agent to reduce the copper slag by pyrolysis at different temperatures.The pyrolysis experiments at high temperature(1 373~1 573K) showed that the pyrolysis products were mainly small molecule reductive substance such as C, H2, CO and CH4. At 1 373, 1 473 and 1573 K, the conversion rates of carbon deposits were 78.36%, 79.83% and 80.07%, respectively, so after pyrolysisthe carbon element in waste cooking oil mainly existed in the form of carbon deposits.Thermodynamic analysis showed that these pyrolysis products had good reductionactivityto magnetic(Fe3O4) at high temperature, it was feasible to use waste cooking oil instead of traditional fossil reductant to realize the reduction of magnetic in copper slag.Using N2 as the carrier gas was not only conducive to the waste cooking oil blowing into copper slag at high temperatures, but also agitates the slag through the momentum transfer, increasing the chance of the tiny copper droplets aggregating and growing.Under the optimum conditions of melting temperature 1573K, flow rate of waste cooking oil 2.055mL/min, flow rate of carrier gas 3L/min, blowing time 4 min and settling time 50 min, the content of Fe3O4 in copper slag decreased from 33.40wt% to 1.60wt%, the content of Cu in copper slag decreased from 4.49wt% to 0.49wt%, the Fe3O4 phase was transformed into 2FeO·SiO2 phase. According to the Einstein-Roscoe equation, the decrease of Fe3O4 in slag was favorable to the decrease of viscosity, thus improving the settling conditions of copper droplets. However, increasing the blowing time of waste cooking oil to deeply reduction of Fe3O4 would increase the impurity content in the deposited metal and prolonging the settling time, because of themechanical entrainment and chemical dissolution of copper slag to the copper, it could not bring a better settlement effect. The final recovery rate of copper in experiment was 89.09%.