电弧炉粉尘球团非等温还原的动力学研究

Research of Non isothermal Reduction Kinetics of EAF Dust Pellets

在连续加热条件下 ,对电弧炉粉尘球团的还原过程动力学进行了研究 .电弧炉粉尘与碳和粘结剂白云石均匀混合后制粒 ,然后将球团置于热重分析仪中以平均 4 0 K/ min的速度加热至 150 0℃ ,并利用计算机对球团重量变化进行监控 .金属还原率的计算中 ,考虑了球团的失重、水的蒸发、铅和锌在高温下挥发 .经实验研究证实电弧炉粉尘的还原分为 3个步骤 ,并建立了每一步骤的还原动力学方程 ,找出了有关的动力学参数表观活化能和频率因子 ,从而确定第 1步由化学反应控制 ,第 2步由扩散控制 ,第 3步与球团中的含碳量和加热温度有关 ,主要是铬的氧化物 ( Cr O)的还原 。

Kinetics studies of the electric arc furnace (EAF) dust reduction process have been carried out under non isothermal temperature condition. EAF dust pellets are made with carbon as the reducing agent and dolomite as the binder. A Thermo Gravimetric Analyzer (TGA) is used to determine the weight loss of pellets, which are heated at an average rate of 40 K/min up to a temperature of 1500℃. The reduction degree is calculated by taking into account the pellet weight loss, evaporation of moisture, dust, zinc and lead at high temperatures. The reduction process of EAF dust consists of three steps related to the change in temperature and time. The non isothermal reduction kinetics equations are set up to describe every step. The kinetics parameters such as apparent activation energies and frequency factors are established at the same time. It is found that the first step is chemically controlled, the second step diffusion controlled and the third step strongly dependent on the initial content of carbon in the pellets. Chromium oxide (CrO) could be reduced only in the last step in which high reduction temperature and high initial carbon content in pellets are required.