Control of carbon balance in a silicon smelting furnace by monitoring calcium.

摘要

A method is described for controlling the carbon balance of a silicon smelting furnace by maintaining the concentration of calcium within the silicon formed in the furnace within a range of 0.4 to 2.0 weight percent. The calcium yield of the furnace is a rapid and sensitive indicator of the carbon balance of the furnace. More specifically, a calcium yield of less than 80 weight percent indicates a negative carbon balance in the furnace; a calcium yield of greater than 90 weight percent indicates an excess carbon balance in the furnace; and a calcium yield within a range of 80 weight percent to 90 weight percent indicates a furnace in carbon balance. A preferred embodiment of the present invention uses calcium yield in conjunction with a harmonic volts parameter and a electrode consumption measurement to further control carbon balance of the furnace.