有色金属工程（有色金属（中英文））

本研究针对微硅粉-炭黑复合球团的碳热还原反应过程，开展了系统的动力学建模分析。通过在高温热重分析装置中分别于1 625、1 650和1 675℃条件下对微硅粉与炭黑的混合球团样品进行热重试验，测定反应失重率与速率，采用等温等转化率法，获得反应速率常数k(T)、活化能E与指前因子A等关键参数。结果表明，微硅粉的F_SiO2值为1.72。Si C生产步骤的平均活化能为427 k J·mol^-1。在温度1 898 K(1 625℃)、1 923 K(1 650℃)、1 948 K(1 675℃)获得的指前因子A为2.01E+12 min^-1；气固界面因子n随SiO₂含量升高显著增大，表明其对界面控制机制具有强化作用。实验拟合结果良好。建立的动力学模型可准确预测不同原料与温度条件下的SiC生成速率。微硅粉反应速率方程为：■。

Research purpose: Micro-silica,a significant by-product of industrial silicon smelting,possesses high SiO₂ content and a large specific surface area,rendering it a promising candidate for carbothermal reduction processes. Yet its widespread,efficient utilization has been constrained by the absence of precise kinetic models that capture its high-temperature reaction behavior and the evolving gas-solid interface. This study aims to advance the resource utilization of micro-silica by optimizing the reaction of carbon-silicon composite pellets through comprehensive kinetic analysis that remains faithful to industrially relevant conditions. Specifically,the objective is to build a reliable,mechanistically informed rate model that can be transferred to plant settings for superior process control,improved energy efficiency,and high-value reuse of this by-product. To bridge laboratory observations and industrial practice,we explicitly quantify an interfacial-growth factor that responds to feedstock composition,and we introduce a silica-specific correction to reflect micro-silica's distinctive physicochemical attributes(high amorphous fraction,nano-aggregation,and extensive surface hydroxylation). The resulting framework clarifies how composition,temperature,and interface evolution couple to determine the formation of silicon carbide(SiC),providing a basis for predictive control,residence-time targeting,and decarbonization-oriented optimization. Methods: Carbon-silicon composite pellets were prepared from micro-silica and carbon black at a fixed mole ratio of SiO₂∶C=1∶3 to ensure stoichiometric sufficiency of reductant for SiC formation with CO evolution. Thermogravimetric experiments were performed at three isothermal setpoints-1 625 ℃,1 650 ℃,and 1 675 ℃-to track mass loss and instantaneous reaction rate continuously during carbothermal reduction. The conversion degree η was calculated from the measured mass change,enabling direct comparison across temperatures and compositions. An isothermal iso-conversional approach was used to extract the apparent rate constant k(T) at defined η levels;Arrhenius analysis of k(T) then yielded the apparent activation energy E and pre-exponential factor A. To capture morphology-and composition-driven changes in reactive area,a gas-solid interface factor n was introduced and regressed from the experimental rate-conversion profiles. The dependence of n on the silica mass fraction X_SOi2 was quantified by a power-law relation,and a Micro-Silica correction factor F_SiO2 was incorporated to account for its unique surface chemistry and ultra-fine particle size distribution. Model identification proceeded by simultaneous fitting of multi-temperature,multi-composition datasets,and validation was performed by comparing the predicted and measured rate-time and rate-conversion curves,emphasizing the fidelity of earlystage nucleation/growth and later-stage approach to completion. Results: The average apparent activation energy for SiC formation was 427 kJ · mol ^-1,with a corresponding preexponential factor of 2. 01×10¹² min ^-1,indicating a thermally activated pathway consistent with interface-controlled growth at the studied temperatures. The gas-solid interface factor n increased markedly with rising SiO₂ content,revealing stronger interface-control as reactive silica becomes more prevalent and accessible. The corrected interface factor was formulated as:where the correction factor F_SOi2 for micro-silica was determined to be 1. 72. The near-inverse exponent(-0. 99) underscores the sensitivity of interfacial dynamics to feed composition. Incorporating this correction significantly improved rate predictions across the tested thermal window. The final kinetic rate equation exhibited excellent agreement with experiments(R²=0. 9724),capturing both the acceleration phase and the deceleration as the reaction approaches completion. The kinetic equation for the carbothermal reduction of micro-silica is expressed as:■ .Conclusions: Micro-silica displays stable,predictable high-temperature behavior,and its carbothermal reduction can be effectively described by a first-order kinetic framework integrated with a corrected interfacial-growth mechanism. The established rate equation reliably forecasts SiC formation across feed compositions and temperatures,offering a practical tool for industrial process control,pellet design,residence-time setting,and temperature field optimization. By enabling quantitative energy-use assessments and supporting carbon-emission accounting during smelting,the model substantiates the high-value reuse of a by-product as a strategic resource. The approach strengthens cleaner metallurgical production by translating laboratory kinetics into actionable plant-level parameters and provides a foundation for future extensions to non-isothermal heating profiles,larger pellets with internal diffusion effects,and online coupling with off-gas diagnostics for closed-loop control.