Research On The Properties Of Petroleum Coke Used In Industrial Silicon Productio

At present,high coke and high coal are the main development direction of reducing agents used in industrial silicon smelting,among which petroleum coke is the main carbon reducing agent theoretically,due to its characteristics of high fixed carbon content and low ash content,it is a relatively ideal reducing agent.However,in the process of industrial silicon smelting,high temperature will lead to the increase of graphitization degree of petroleum coke,and then reduce its specific resistance,reactivity and other physicochemical properties.In order to balance this disadvantage,the amount of carbon allocation in the actual production process has to be increased,which also makes the massive use of petroleum coke not meet the concept of low-carbon.In this paper,microwave assisted strengthening of metal-salt coupled petroleum coke is systematically studied to explore a new reducing agent,which can improve the reactivity of petroleum coke and meet the requirements of carbon reducing agent for industrial silicon smelting.Specific research contents include the following:（1）Statistical methods and MIVM models were used to evaluate the influence of impurity content on actual production.The presence of Ni is conducive to the removal of Fe and Al in Si.When the content of Ni in Si is higher,the removal of Fe and Al in pickling refining is more favorable.The removal of Fe and Al and then Ni reduces the energy consumption of industrial silicon production,which is helpful for the preparation of solar grade polysilicon by metallurgical method.（2）According to the conclusion of（1）,the effect of Ni SO₄on petroleum coke used in industrial silicon smelting production is studied.The petroleum coke is treated with microwave-assisted coupling with different metal salts to load corresponding metal ions and their compounds.The effects of microwave-assisted coupling with metal salt on the thermodynamic and kinetic characteristics of petroleum coke reaction were studied by thermogravimetric analysis and kinetic model.When Ni SO₄was added,the activation energy of petroleum coke after microwave treatment decreased from 54.56k J/mol to 10.86k J/mol.The reactivity of petroleum coke is improved and the carbonthermal reduction of silica in high temperature zone is promoted.（3）The effects of additives（La₂C₃O₉,Ce₂C₃O₉,Pr₂C₃O₉）on the reaction properties of petroleum coke after being treated with different media（distilled water,anhydrous ethanol）and different roasting conditions（conventional roasting,microwave roasting）were studied,and the mechanism of their influence on the carbonthermal reduction process of silica was revealed.The results showed that under the same additive conditions,the reaction performance of petroleum coke was significantly improved when the organic solvent was used as the grinding medium,the initial reaction temperature and activation energy of the carbonthermal reduction reaction of silica were significantly reduced,the reaction rate was accelerated,and the maximum reaction rate of the reduction reaction was increased by 49.48%.