The reduction of silica with carbon is a more complicated process of thermochemical reaction than metal smelting. After a large number of scientific studies, the basic laws of thermal reaction of Metal Silicon are obtained, In the process of production, the correctness and reference of the obtained rules are demonstrated.
The following brief description of the past 54 years since the experience of the industry's predecessors, and we on this basis, a deeper level of scientific induction.
1143 ~ 2001K, from the quartz phase, excessive to the scale of quartz, the volume increase of up to 14.7%, such a large volume change, resulting in the charge as a component of quartz (commonly known as silica) in the furnace surface thermal cracking. The higher the water absorption, the conductive quartz component, the more severe the bursting.
In the metallurgical theory of metallic silicon, a major theoretical breakthrough is the discovery of a new silicon low-cost oxide-SiO. This is confirmed by the recovery of large amounts of SiO2 dust from the Metal Silicon precipitator. And it can be further confirmed that the oxide SiO plays a very important reduction during melting, and it is a necessary intermediate. Production of SiO in Si-O:
Therefore, it is possible to understand the importance of preventing the formation of SiO effluent from the furnace, reducing the flue gas, reducing the thermal energy divergence, and eliminating dust and dust (also known as micro-silica), so as to fully understand the basic theory of the formation and participation of SiO in the furnace. Powder) is to improve the efficiency of metallurgical furnace, metallurgical furnace to improve the technical and economic indicators important work.
The carbon in the furnaces produced by the submerged arc furnace is carried out according to the above reaction formula (7), which is called the theoretical carbon content. However, in practice,Metal Silicon the process of SiO2 being reduced by C at different temperatures is carried out by forming the intermediate product solid SiC, gaseous SiO and condensed SiO. Therefore, the reaction process can not be simply carried out according to (7). The thermodynamic range of the production of metallic silicon must grasp the phase equilibrium principle of the cross reaction between Si-O-C series, elemental, alloying ratio between the concentration ratio and the melting temperature.
The large amount of heat (69 to 72% of the heat consumed) is mainly derived from the arc high temperature combustion zone at the bottom of the electrode (working end), and a gas hole in the combustion zone High temperature reflector), in this extremely high temperature of the hole, the material melting,Metal Silicon decomposition, ionization, vaporization, boiling, sublimation and phase change, and so on a variety of intense and complex reactions. In order to study this complex system, we have established a visual crucible reaction zone model.
When we format this model, the resulting constraint (conservation) condition is:
(1) When the vapor partial pressure of the "condensed phase" substance participating in the reaction is equal to the saturated vapor pressure of these substances,Metal Silicon the equilibrium of all the evaporation and condensation reactions can be achieved in the system.
(2) to maintain all the reaction equilibrium that the system may exist, including the mass balance of the chemical elements in the gas phase, and the equilibrium of the compound atomization constant values, and to achieve a balance between the dissociation and the reaction in the system.
(3) volume balance of the gas components in the system.
The above three equilibrium constraints may be fulfilled in the laboratory, but this restriction is an inevitable law, which reflects the response of the material to the equilibrium of the material in the model. According to the basic theory of thermodynamics, this model reveals the relationship between the initial reaction of Metal Silicon formation, the gas / liquid / solid phase of the intermediate reaction and the end point reaction, and the temperature and pressure. Therefore, we believe that in the smelting of silicon metal submerged arc furnace, there is a "pot" of the reaction zone, it should be used as a source of the establishment of the model.