Method for directly producing compound fertilizer by utilizing medium-low-grade phosphorite

The invention discloses a method for directly producing a compound fertilizer by using medium-low-grade phosphorite, and relates to the technical field of fertilizer production. Comprising the following steps: uniformly mixing mixed acid with sulfuric acid and water, and controlling the temperature at 65-80 DEG C; adding urea and reacting at 75-95 DEG C to obtain a mixed solution; adding the mixed solution into the phosphoric ore pulp, and reacting for 90-250min under the conditions that the temperature is 70-90 DEG C and the stirring strength is 50-100m/min, so as to obtain mixed slurry; and adding the mixed slurry into a granulator for spraying and granulating, and drying and screening to obtain the multifunctional multi-nutrient compound fertilizer. The mixed acid and the sulfuric acid are mixed, then the urea is added, the obtained mixed solution directly converts all elements such as phosphorus, calcium, magnesium, silicon and the like in the medium-low grade into a form capable of being absorbed by crop