Method for recycling fluorine from phosphorus-containing fluorine slag and cogenerating calcium superphosphate

Abstract

The invention discloses a method for recycling fluorine from a phosphorus-containing fluorine slag and cogenerating calcium superphosphate. The method comprises the following steps: adding a phosphorus-containing fluorine slag and concentrated sulfuric acid to a defluorination reaction tank according to the ratio of 1 to (0.6-1.1), stirring and reacting at 60-200 DEG C for 0.1-3 hours; recovering escaped fluorine-containing gas in the reaction process and preparing fluoride products such as hydrofluoric acid and the like to recover fluorine resources; stirring and reacting the phosphorus-containing fluorine slag and the concentrated sulfuric acid in the defluorination reaction tank for 0.1-3 hours; adding a phosphorus-containing calcium material to reaction slurry, stirring and reacting for 0.1-5 hours, and neutralizing free acids in the slurry; and drying the reactants after reacting, so as to obtain a calcium superphosphate product. Compared with the prior art, the method has the characteristics of being simple in process, mild in operation condition, high in recovery rate of phosphorus-fluorine resources, and free of 'three wastes' on the whole.

Description

technical field [0001] The invention relates to the field of treatment of three wastes in phosphorus chemical industry, in particular to a method for recovering fluorine from phosphorus-containing fluorine slag and co-producing superphosphate. Background technique [0002] The phosphorus chemical industry in my country will produce a large amount of phosphorous and fluorine-containing wastewater in the production process of wet-process phosphoric acid. In the process of treating fluoride ions in phosphorus- and fluorine-containing wastewater, calcium salts such as milk of lime and calcium carbonate are mainly used to precipitate fluorine in wastewater. ions, filtered the precipitated residue to obtain P 2 o 5 Phosphorous and fluorine-containing slag with a content of about 15% to 28% and a F content of about 15% to 30%. Because this phosphorus-containing fluorine slag contains a large amount of F, it may cause plant poisoning if it is directly applied to crops as a fertil...

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Problems solved by technology

Because this phosphorus-containing fluorine slag contains a large amount of F, it may cause plant poisoning if it is directly applied to crops as a fertilizer; Phosphorus content requirements subject to addition restrictions

Based on the above reasons, at present, the phosphorus-fluorine-containing slag is mainly treated as waste for stockpiling, not only does not use the phosphorus-fluorine resources in the slag, but also occupies land for stockpiling, paying expensive maintenance costs, and causing certain pollution to the environment

[0003] In the patent document with application number 201110319555.9, "A Method for Recovering Phosphorus and Fluorine from Defluoridation Slag" is disclosed. method to recover phosphorus and fluorine resources in defluorination slag, but the process is complex, equipment investment is large, and the recovery rate of fluorine resources is low

[0004] In the patent literature with application number 200880003959.3, "Preparation of Hydrogen Fluoride by Calcium Fluoride and Sulfuric Acid" is disclosed, the patent uses calcium fluoride-containing fine powder to react with sulfuric acid Preparation of hydrogen fluoride, but the amount of sulfuric acid is greatly excessive, the reaction temperature is high, and the requirements for equipment and materials are high

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