Abstract:

In view of the fact that the phosphorus in the by-product crude calcium nitrate solution of frozen nitrophosphate en-ters the filter residue and is difficult to be recycled,the production capacity of the nitrophosphate fertilizer plant is low,and the ammonia escape rate in the leaching section of the collophanite enrichment technology is low,which leads to the high content of ammonium nitrate in the leaching solution,causing the the question of unable to be used in downstream. Study on the use of crude calcium nitrate solution for phosphate rock removal was carried out.Experimental method and optimal reac-tion conditions：the raw ore was crushed and calcined（calcination temperature was 900~1 100 ℃,calcining time was 1.5~3.0 h）,leached with crude calcium nitrate solution,using the thermal energy and chemical reaction of the crude calcium ni-trate solution The thermal control reaction temperature was 60~70 ℃,which saved steam consumption and didn′t need heat-ing.The reaction pH was 4.5~6.5,and no phosphorus was precipitated during the reaction.In the phosphate concentrate pre-pared under these conditions,the mass fraction of phosphorus pentoxide was≥35%,the mass fraction of magnesium oxide was≤1.0%,and the phosphorus recovery rate was 100.49%~100.60%.The phosphate concentrate produced by this technolo-gy was acidified.The separation efficiency of acid-insoluble matter was improved,which could meet the raw material require-ments for downstream production of white nitrophosphate.The by-product extract could be used to produce amino acid liquid fertilizer and medium element nutrient masterbatch.The method had no tailings,which was green and environmentally friend-ly,and provided a new research idea for the efficient utilization of phosphate rock.

Key words: nitrophosphate, crude calcium nitrate solution, phosphate rock demagnesium, phosphate concentrate