The invention discloses a method for manufacturing slow-release
nitrogen fertilizer and construction sand from high-pressure roller-milled iron
tailings, and belongs to the technical field of comprehensive utilization of iron
tailings. The method comprises the following steps: adding water into high-pressure roller-milled iron
tailings to prepare high-pressure roller-milled iron tailing
slurry, selecting stone
powder particle
slurry of which the total amount of stone
powder particles is more than 50%, dehydrating the residual particle
slurry which is not selected to be used as sand for construction, flocculating,
settling and concentrating the stone
powder particle slurry to obtain a stone powder
particle filter cake, and filtering the stone powder
particle filter cake to obtain the high-pressure roller-milled iron tailings. The preparation method comprises the following steps: fully mixing the raw materials with a mixture 1 of
calcium bentonite,
sodium bentonite and a
nitrogen source to obtain a mixture 2, determining a forming mode and adjusting the
water content of the mixture 2 to obtain a slow-release
fertilizer material, and granulating,
drying and cooling the slow-release
fertilizer material to obtain the high-pressure roller milling iron tailing slow-release
nitrogen fertilizer. The method makes the best use of the particles of each size fraction of the high-pressure roller milling iron tailings, exerts respective advantages, effectively solves the problem of large-amount stockpiling of the high-pressure roller milling iron tailings, and generates huge economic, environmental and
social benefits at the same time.