| 摘要 |
PROBLEM TO BE SOLVED: To provide a manufacturing method capable of stably manufacturing a "slag phosphate fertilizer" specified in Fertilizer Control Law, without variation in quality.SOLUTION: The manufacturing method of a slag phosphate fertilizer containing fertilizer components of 3.0 mass% or more of citric acid-soluble phosphates, 20.0 mass% or more of alkali content, and 10.0 mass% of silicates relative to the whole slag phosphate fertilizer comprises: a pulverization step of pulverizing slag with an alkalinity of 1.5 to 3.0, a soluble silicate content of 15 to 35 mass%, a soluble lime content of 30 to 45 mass%, and an aluminum oxide content of 4.5 mass% or less produced as a byproduct in a pretreating step of molten iron in a steel mill; and a magnetic separation step of magnetically separating the slag so as to reduce the iron content in the whole slag phosphate fertilizer to 17 mass% or less. |
