Study On The Viscosity Characteristics Of Copper Slag And The Depletion Of Injection Waste Oil

With the problem of global warming becoming more and more serious,the greenhouse gas emissions have been concerned by people all over the world.Metallurgical Industry as the main carbon emission industry in China,it is an urgent task for metallurgical enterprises to find alternative green low carbon energy.Waste cooking oil is mainly composed of C,H and O elements,the pyrolysis products were mainly small molecule reductive substance such as C,H₂,CO and CH₄,those reducing substances are commonly used as reductant in metallurgical field.Thermodynamic analysis shows that it is feasible to reduce Fe₃O₄ in copper slag by waste cooking oil.China produced 19.75²5.76 million tons of copper slag in 2018.Using carbon neutral energy instead of traditional fossil energy can not only bring remarkable economic benefits,but also accord with the national conditions of energy saving and emission reduction in China.According to the Stokes formula,the viscosity is an important parameter in the process of depleting copper slag,and the accurate grasp of viscosity will provide a theoretical guidance for the electric furnace depleting copper slag.In this paper,the effects of iron phase transformation on the viscosity of copper slag after reduction are discussed in terms of the viscosity of silicate melt of copper slag,the structure of silicate melt and the volume fraction of solid phase.The reduction of copper slag is beneficial to the decrease of viscosity,the viscosity of copper slag reaches the lowest when the addition of anthracite was 1%.Then,due to the deep reduction of Fe₃O₄ in the slag,the Cu-Fe alloy forming in the copper slag increased the solid phase ratio and the viscosity of copper slag.Fe₃O₄ in copper slag was reduced by pyrolysis gas of waste cooking oil,then the viscosity of copper slag decreased and the settlement conditions improved.In the experiment of using waste cooking oil blowing into 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 agitated the slag through the momentum transfer,increasing the chance of the tiny copper droplets aggregating and growing.Fe₃O₄ in copper slag increased the solid phase rate and then the viscosity of molten slag increase,by the way,Fe₃O₄ also trapped copper droplets to form"copper drop-spinel"combination to prevent copper droplets settle down.The reduction of Fe₃O₄ in copper slag by using high temperature pyrolysis gas of waste cooking oil was beneficial to the depleting of copper slag.Under the optimum conditions of melting temperature 1573 K,flow rate of waste cooking oil 2.055 mL/min,flow rate of carrier gas 3 L/min,blowing time 4 min,settling time 50 min,the content of Fe₃O₄ in copper slag decreased from 33.4wt%to1.6wt%,the content of Cu in copper slag decreased from 4.49wt%to 0.49wt%,the final recovery rate of copper in experiment was 89.09%.Increasing the blowing time of waste cooking oil to deeply reduction of Fe₃O₄ would increase the impurity content in the deposited metal;prolonging the settling time,because of the mechanical entrainment and chemical dissolution of copper slag to the copper,it could not bring a better settlement effect.