Method for smelting low-phosphorus steel by using semi-steel

The invention provides a method for smelting low-phosphorus steel by using semi-steel. The method comprises the following steps: (a) supplying oxygen to a converter molten pool by using an oxygen lance, simultaneously adding a slag making material, and pouring out slag when the temperature of the molten pool is 1460-1520 DEG C, the basicity of the cinder is 1.2-1.9, and the weight percent of total iron content in the cinder is 10-15wt%; (b) supplying oxygen to the converter molten pool by using the oxygen lance again, simultaneously adding the slag making material, and pouring out the slag when the temperature of the molten pool is 1640-1660 DEG C, the basicity of the slag is 4.3-5.2, and the weight percent of total iron content in the slag is 16-20wt%; (c) adding 2-3kg/t steel of final slag adjusting agent by each ton of tapping molten steel to the converter molten pool so as to thicken the slag; (d) adding alloy with low phosphorous content in a tapping process so as to alloy the molten steel; and (e) after molten steel alloying, adding 3-5kg/t steel of active lime by each ton of tapping molten steel and fluorite, the weight of which is 15-20% of the weight of the active lime, to steel ladles. According to the method, phosphorous can be effectively removed in a semi-steel converter steel-making process, and the low-phosphorous steel with the phosphorus content of no more than 0.008% is stably produced.