Modeling the Process of Mining Silicon Through a Single Displacement/Redox Reaction
As the popularity of photovoltaic (PV) cells and integrated circuits (IC) increases, the need for silicon also increases. Silicon is one of the most used materials in these two industries. It is an inexpensive and abundant semiconductor. However, the process of producing pure silicon adds cost, and it is generally unknown to the public. One of the first steps in producing silicon is a process called carbon-thermic reduction. Silicon dioxide (SiO2) that is found in beach sand and quartz is melted down in a caldron at a temperature of 1450 degrees Celsius. Coke and other forms of carbon are then added to the mixture, because at this high temperature, the oxygen has more of an affinity to carbon instead of the silicon. A current is then run through the solution. As the impurities float to the top of the mixture, carbon monoxide (CO) vaporizes out of the solution and the metallurgical grade silicon (MGS) is siphoned off the bottom. Although there are more steps needed to produce silicon for the IC and PV industries, this initial step may be modeled in a high school laboratory, through a single displacement redox reaction.
1. Energy is a physical quantity that follows precise natural laws.
Associated Grade Levels:
1.6 Chemical and nuclear reactions involve transfer and transformation of energy.