The invention discloses a technique method for producing high-concentration nitric
phosphate, which comprises the following steps of: adding
nitric acid into
phosphorus ore for acidolysis, depositing and separating acid non-soluble substance, freezing and crystallizing
calcium nitrate, filtering the
calcium nitrate, neutralizing the mother liquid,
vaporization, pelleting and
drying. The invention is characterized in that: a step of thoroughly removing the
calcium of the mother liquid is arranged between the steps of filtering the
calcium nitrate, and neutralizing the mother liquid. The steps comprise the following steps of: I) thoroughly removing the calcium of the mother liquid and adding
sulfuric acid or
ammonium sulfate; the calcium ions and the
sulfate ions in the mother liquid generate
dihydrate calcium sulfate crystal; II) the grading
processing of reaction
slurry: employing a grading device to carry out grading
processing to the reaction
slurry; returning the reaction
slurry provided with small grain calcium
sulfate to the mother liquid for thoroughly removing the calcium, and feeding the reaction slurry provided with large grain calcium sulfate to the calcium sulfate for filtering; and III) filtering and washing the filtering reaction slurry of calcium sulfate by a filter, feeding the primary filtrate and the primary
lavage fluid into the working procedure of neutralizing, and returning the secondary
lavage fluid to the filter. The invention has the
advantage of using middle-low quality
phosphorite to prepare the high-concentration nitric
phosphate.