Low-impurity low-specific-surface-area iron phosphate and preparation method thereof

The invention relates to preparation of iron phosphate, and provides low-impurity low-specific-surface-area iron phosphate and a preparation method thereof, and the preparation method comprises the following preparation steps: (1) synthesizing amorphous iron phosphate; (2) preparing an amorphous iron phosphate suspension: mixing the amorphous iron phosphate obtained in the step (1), a dispersing agent and phosphoric acid, and pulping to prepare the suspension; (3) aging: feeding the suspension liquid prepared in the step (2) into a multi-channel tubular reactor, carrying out heating, crystal transformation and heat preservation, feeding the suspension liquid into a crystallization reactor after heat preservation to obtain crystal transformation slurry, adding the suspension liquid obtained in the step (2) into the crystallization reactor, controlling the flow velocity of the crystal transformation slurry and the suspension liquid, and carrying out mixing, heating, crystal transformation and heat preservation