Method for purifying byproduct phosphogypsum of wet-process phosphoric acid

Abstract

The invention relates to a method for purifying byproduct phosphogypsum of wet-process phosphoric acid, which comprises the following steps of S1, flotation tank decolorization: adding water into byproduct phosphogypsum in the phosphoric acid process to regulate ore pulp, proportionally adding a decolorization reagent, and overflowing to enter a flotation tank, S2, jigging reselection column desilicication: supplementing water to the decolorized ardealite concentrate pulp obtained in the step S1, pumping the decolorized ardealite concentrate pulp into a desilicication reselection column for jigging classification, and filtering the silicon tailing pulp in a belt filter to obtain silicon tailings, and feeding top overflow concentrate pulp for thickening and filtering, S3, filtering, washing and dephosphorizing: pumping the desiliconized ardealite concentrate pulp obtained in the S2 into an inclined plate thickener for thickening and dewatering, obtaining ardealite concentrate pulp through underflow, then pumping the ardealite concentrate pulp into a belt filter for filtering, and discharging a washed filter cake into a warehouse, so as to obtain a refined ardealite product. The method is suitable for a large-scale industrial device, can realize continuous, stable and reliable production, has strong adaptability to the byproduct phosphogypsum, and is especially suitable for the byproduct phosphogypsum of a phosphoric acid device using low-quality phosphate ore at present.

Description

technical field [0001] The invention relates to the technical field of phosphogypsum, in particular to a method for purifying the by-product phosphogypsum of wet-process phosphoric acid. Background technique [0002] Phosphogypsum is a chemical by-product with calcium sulfate as the main component produced in the process of preparing phosphoric acid from phosphate rock by wet method. Nearly five tons of phosphogypsum are produced for every ton of phosphoric acid produced. Phosphogypsum also contains undecomposed phosphate rock, SiO 2 , alumina, iron oxide, magnesium oxide, fluorine-containing substances, acidic insoluble organic substances and other impurities that are harmful to human health and biological growth, and affect the quality of phosphogypsum products; phosphogypsum is different from natural gypsum, although its CaSO 4 2H 2 The content of O is relatively high, but it contains 0.3% to 2.0% of P 2 o 5 , 0.1% to 1.5% of F, wet base phosphogypsum is acidic. At ...

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Problems solved by technology

At present, the amount of phosphogypsum stacked in China is more than 600 million tons, and it is still growing at a rate of more than 70 million tons every year, but its effective utilization rate is less than 20%. A large amount of phosphogypsum is still stored in the form of direct stacking, which not only occupies land resources , bring a heavy burden to the production enterprises, and also cause safety hazards and environmental pollution

[0005] In the existing literature, there have been reports on the removal of silicon, soluble salt and organic matter from phosphogypsum by flotation and other beneficiation methods, but a continuous process and equipment are used to comprehensively remove silicon from phosphogypsum. Three types of impurities that affect the comprehensive utilization, namely soluble salts headed by soluble phosphorus, organic matter and other impurities that affect the whiteness of gypsum, and silicates mainly quartz chalcedony. The industrialized devices are not mature enough.

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