Process for desiliconizing and desulphurizing pig iron

Claim 1

A PROCESS FOR PRODUCING FROM A STARTING PIG IRON, A MODIFIED PIG IRON CONTAINING LOWER AMOUNTS OF SILICON AND SULPHUR THAN THE STARTING PIG IRON, WHICH COMPRISES MIXING MOLTEN STARTING PIG IRON WITH SOLID SLAG FORMING ELEMENTS WHICH, WHEN MELTED, FORM A BASIC SLAG CONTAINING A BASIC ELEMENT OF THE GROUP CONSISTING OF LIME, MAGNESIA, BARIUM OXIDE AND SODA AND ALSO CONTAINING AN OXIDIZING AGENT OF THE GROUP CONSISTING OF CALCIUM NITRATE, CALCIUM PEROXIDE, SODIUM NITRATE AND SODIUM PERCARBONATE, THE AMOUNT AND COMPOSITION OF SAID SLAG BEING SUCH THAT THE SLAG CONTAINS LESS OF SAID OXIDIZING AGENT THAN IS REQUIRED TO OXIDIZE ALL OF THE SILICON OF THE STARTING PIG IRON SO THAT AFTER REACTION OF SUBSTANTIALLY ALL OF SAID OXIDIZING AGENT IN SAID SLAG WITH SILICON IN THE PIG IRON THE PIG IRON CONTAINS A SUBSTANTIAL AMOUNT OF SILICON AND THE SLAG IS CONVERTED TO A REDUCING SLAG, CARRYING OUT THE REACTION UNTIL SUBSTANTIALLY ALL OF SAID OXIDIZING AGENT HAS BEEN REDUCED TO METAL, THE SILICON CONTENT OF THE PIG IRON HAS BEEN SUBSTANTIALLY LOWERED WITHOUT SUBSTANTIALLY ALTERING THE CARBON CONTENT OF THE PIG IRON AND THE SLAG IS CONVERTED TO A REDUCING SLAG, AND CONTINUING THE ACTION OF THE REDUCING SLAG ON THE PIG IRON CONTAINING A SUBSTANTIAL AMOUNT OF SILICON FOR A TIME SUFFICIENT TO SUBSTANTIALLY LOWER THE SULPHUR CONTENT OF THE PIG IRON.