The invention discloses a method for preparing a liquid
fertilizer and co-producing a medium element
fertilizer by using
raffinate acid, and relates to the technical field of preparation of fertilizers by using
raffinate acid. Comprising the following steps: S1, carrying out filter pressing on
raffinate acid: adding a modified filter aid into the raffinate acid, uniformly mixing, pumping into a plate-and-frame
filter press, and carrying out filter pressing to obtain a raffinate acid
clear liquid and filter residues; s2, preparing a liquid
fertilizer from the raffinate acid
clear liquid: sequentially adding desalted water,
nutrient elements, synergistic factors and the raffinate acid
clear liquid into a reaction kettle, and completely dissolving to obtain an acidic liquid fertilizer; s3, preparing the medium element fertilizer from the filter residues: uniformly stirring and mixing the filter residues,
phosphate tailings and a modified synergistic granulating agent, granulating,
drying, screening and cooling to obtain the medium element fertilizer. The technological process is simple and easy to operate, raffinate acid is only subjected to filter pressing, the treatment cost is low, the fertilizer efficiency is improved through synergistic factors in the acid liquid fertilizer, the particle strength is improved after filter residues are granulated through the modified synergistic granulating agent, and meanwhile the medium element fertilizer is endowed with the
biological stimulation effect.