Patent ID: 7879130
Filing Date: 2011-02-01
Classification: C01B,C21C,Y02P

Abstract:
1. A method for producing a low phosphorous calcium-silicate based slag comprising the steps of: (a) providing a layer of molten ferrosilicon alloy in a vessel; (b) forming a layer of molten calcium-silicate based slag on top of the layer of molten ferrosilicon alloy in the vessel; (c) stirring said layer of molten ferrosilicon alloy and layer of molten calcium-silicate based slag by supplying a reducing and/or an inert gas to the vessel, whereby phosphorous in the layer of molten calcium-silicate based slag is transferred to the layer of molten ferrosilicon alloy and a molten low phosphorous calcium-silicate based slag having a phosphorous content of less than 3 ppmw is produced; (d) removing molten low phosphorous calcium-silicate based slag containing less than 3 ppmw phosphorous from the vessel; (e) maintaining the layer of molten ferrosilicon alloy in the vessel; and (f) repeating steps (b)-(e) to produce low phosphorous calcium-silicate based slag having a phosphorous content of less than 3 ppmw.