Method for recovering phosphogypsum solid-phase phosphorus and eutectic phosphorus

Abstract

The invention discloses a method for recovering solid-phase phosphorus and eutectic phosphorus in ardealite, which specifically comprises the following steps: mixing ardealite, a targeted crystal form regulating agent and water to prepare ardealite slurry, adding the ardealite slurry into a first tank of a crystallization reactor, and stirring and reacting at 80-90 DEG C and 120-200r / min for 10-30 minutes; a reaction product enters a second tank and is stirred to react for 30-60 min at the temperature of 30-60 DEG C and the speed of 30-80 r / min; feeding a reaction product into a third tank, stirring and reacting for 20-30 minutes at the temperature of 30-60 DEG C and the speed of 20-60 r / min, carrying out solid-liquid separation and solid washing, and combining separated liquid and washing liquid to obtain a phosphorus-rich product; the method is easy to operate and mild in reaction condition, purification and impurity removal are also achieved in the process of recovering solid-phase phosphorus and eutectic phosphorus in the phosphogypsum, and solid waste resource utilization is facilitated.

Description

Technical Field

[0001] The invention belongs to the technical field of phosphorus chemical production and solid waste resource recovery, and in particular relates to a method for recovering solid-phase phosphorus and eutectic phosphorus in phosphogypsum. Background Art

[0002] The phosphorus chemical industry is an important foundation for the development of my country's high-tech industries, food and national defense security. The wet phosphorus industry accounts for more than 90% of the phosphorus chemical industry. During its processing, the annual by-product phosphogypsum contains a large amount of phosphorus and fluorine impurities. If it is not deeply purified, there will be great environmental hazards and safety risks, which seriously limits the large-scale and intensive utilization of phosphogypsum.

[0003] Phosphorus is a national strategic resource. my country consumes a large amount of phosphorus resources every year, and the resource is seriously depleted. Therefore, it is of great significance to recover phosphorus resources in phosphogypsum. At present, many studies have been carried out at home and abroad on the recovery of phosphorus from phosphogypsum, but all of them are water-soluble phosphorus, and there is no systematic research on the recovery of solid phase phosphorus and eutectic phosphorus. According to the results of previous studies, most of the insoluble phosphorus and eutectic phosphorus are interspersed between the fine crystals of phosphogypsum, and the effect of ball milling and leaching is not ideal. For example, CN 118180122 A discloses a method for washing and purifying phosphogypsum, in which the phosphogypsum is treated by slurry adjustment, pH adjustment, and filtrate treatment to reduce the water-soluble phosphate (in terms of P) to less than 0.5 mg / L. CN 117800379 A discloses a method for harmlessly treating phosphogypsum and removing and / or recovering phosphorus, by using a curing agent to solidify the phosphogypsum eluent, and then using polyaluminum ferric sulfate for flocculation treatment, and then filtering to remove and / or recover phosphorus in the phosphogypsum eluent. CN 116900027 A reports a method for separating phosphorus and fluorine in phosphogypsum and its application. The method comprises the steps of wet grinding phosphogypsum, water and a leaching agent in proportion and filtering to obtain washed phosphogypsum and a wet grinding filtrate; adding water and a curing agent in proportion to the washed phosphogypsum, stirring and reacting for a period of time, filtering to obtain harmless phosphogypsum; and standing the obtained wet grinding filtrate for separation to obtain an organic solvent rich in phosphorus. Phase and inorganic phase containing F. A variety of technologies have been published for the recovery and disposal of phosphorus in phosphogypsum, but these methods still have the following problems: the process is complicated, all of them are for treating water-soluble phosphorus elements, and a variety of organic impurities may be introduced at the same time. The process is long and it is easy to cause secondary pollution to the environment and products. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for recovering solid-phase phosphorus and eutectic phosphorus in phosphogypsum. Through the synergistic effect of a crystal regulating agent, a new method for dissolving and recrystallizing fine phosphogypsum crystals is established. Part of the dissolved phosphogypsum fine crystals release insoluble phosphorus and eutectic phosphorus during the recrystallization process, and grow in situ on the basis of coarse crystals into coarser phosphogypsum crystals that are easy to filter and wash, thereby solving the problems of environmental risks and waste of phosphorus resources in phosphogypsum.

[0005] The method for recovering solid phase phosphorus and eutectic phosphorus in phosphogypsum of the present invention comprises the following steps: mixing phosphogypsum, a targeted crystal form regulator and water to prepare phosphogypsum slurry; adding the phosphogypsum slurry into a first tank of a crystallization reactor; stirring and reacting at 80-90° C. and 120-200 r / min for 10-30 min; the reaction product enters a second tank, stirring and reacting at 30-60° C. and 30-80 r / min for 30-60 min; the reaction product enters a third tank, stirring and reacting at 30-60° C. and 20-60 r / min for 20-30 min, performing solid-liquid separation, washing the solid, combining the separated liquid and the washing liquid to obtain a phosphorus-rich product, and entering a wet phosphoric acid system for further recovery, thereby realizing recovery of solid phase phosphorus and eutectic phosphorus in phosphogypsum.

[0006] The solid-liquid mass volume ratio of the phosphogypsum to water is g:mL 1:3-5.

[0007] The targeted crystal form regulator is composed of regulator A and regulator B, wherein regulator A is sodium phosphate, and its addition amount is 0.01% to 0.03% of the mass of phosphogypsum; the main function of regulator A is to inhibit the growth of the X-axis of the phosphogypsum crystal surface and promote the growth of the Y-axis of the phosphogypsum crystal, so that the phosphogypsum forms coarse crystals; The regulating agent B is composed of 0.05% to 0.08% of sodium dihydrogen phosphate by weight of phosphogypsum, 0.005% to 0.01% of oxalic acid by weight of phosphogypsum, and 0.001% to 0.005% of ethylenediaminetetraacetic acid by weight of phosphogypsum; the main function of the regulating agent B is to promote the dissolution of solid phase phosphorus and eutectic phosphorus into the liquid phase.

[0008] The solid is washed twice, and the washing liquid from the second washing is recycled for the first washing, and the liquid after solid-liquid separation and the first washing liquid are combined.

[0009] Compared with the prior art, the beneficial effects of the present invention are: 1. The present invention adjusts the unsaturation of the phosphogypsum aqueous solution and adds a targeted crystal form regulator to dissolve fine crystals. At the same time, insoluble phosphorus and eutectic phosphorus migrate from the solid phase to the liquid phase. By adjusting the process parameters, the Ca2+ dissolved in fine crystals 2+ and SO4 2-Through dynamic adsorption to the surface of large-particle phosphogypsum crystals, coarse phosphogypsum crystals are formed; solid-phase phosphorus and eutectic phosphorus enter the liquid phase as water-soluble phosphorus and enter the wet-process phosphoric acid system for recovery; the method of the present invention greatly increases the average particle size of phosphogypsum, which is conducive to filtration, and greatly reduces the total phosphorus content in the recovered phosphogypsum; 2. The present invention realizes the true harmlessness of phosphogypsum, and will not cause phosphorus and fluorine to leak out due to changes in the environment, causing the risk of environmental pollution; 3. The method of the present invention is simple, easy to operate and suitable for industrial application. DETAILED DESCRIPTION

[0010] The present invention is further described in detail below in conjunction with the examples, but the contents described should not be regarded as limiting the present invention. The methods in the present examples are operated according to conventional methods unless otherwise specified, and the reagents used are conventional reagents or reagents prepared according to conventional methods unless otherwise specified; Example 1

[0011] 100m 3 / h of phosphogypsum is transported by belt conveyor and 300m 3 / h of water is continuously added to the steady-state crystallizer, and a targeted crystal regulator is added at the same time. The targeted crystal regulator consists of regulator A and regulator B. Regulator A is sodium phosphate, and its addition amount is 0.01% of the mass of phosphogypsum; regulator B consists of 0.05% of sodium dihydrogen phosphate by mass of phosphogypsum, 0.005% of oxalic acid by mass of phosphogypsum, and 0.001% of ethylenediaminetetraacetic acid by mass of phosphogypsum; the raw materials entering the first tank are stirred and reacted at 85°C (stirring speed 160 r / min) for 20min; the reaction product enters the second tank and continues to stir (stirring speed 45 r / min), and reacts at 35°C for 50min; the reaction product enters the third tank, and stirs and reacts at 40°C and 34r / min for 25min, filtered, and the solid is washed with water twice, and the filtrate and the first washing liquid are combined to obtain a phosphorus-rich product, which enters the wet phosphoric acid system for further recovery. The results are shown in Table 1; Table 1 Composition of raw phosphogypsum and purified phosphogypsum . Example 2

[0012] 100m 3 / h of phosphogypsum is transported by belt conveyor and 400m 3 / h of water is continuously added to the steady-state crystallizer, and a targeted crystal regulator is added at the same time. The targeted crystal regulator consists of a regulator A and a regulator B. The regulator A is sodium phosphate, and its addition amount is 0.02% of the mass of phosphogypsum; the regulator B consists of 0.06% of sodium dihydrogen phosphate by mass of phosphogypsum, 0.007% of oxalic acid by mass of phosphogypsum, and 0.003% of ethylenediaminetetraacetic acid by mass of phosphogypsum; the raw materials entering the first tank are stirred and reacted at 80°C (stirring speed 150 r / min) for 30min; the reaction product enters the second tank and continues to stir (stirring speed 70r / min), and reacts at 45°C for 40min; the reaction product enters the third tank again, and is stirred and reacted at 40°C and 25r / min for 25min, filtered, and the solid is washed for the first time with the second washing liquid of Example 1, and washed for the second time with water, and the filtrate and the first washing liquid are combined to obtain a phosphorus-rich product, which enters the wet phosphoric acid system for further recovery. The results are shown in Table 2; Table 2 Composition of raw phosphogypsum and purified phosphogypsum . Example 3

[0013] 100m 3 / h of phosphogypsum is transported by belt conveyor and 500m 3 / h of water is continuously added to the steady-state crystallizer, and a targeted crystal regulator is added at the same time. The targeted crystal regulator consists of a regulator A and a regulator B. The regulator A is sodium phosphate, and its addition amount is 0.03% of the mass of phosphogypsum; the regulator B consists of 0.08% of sodium dihydrogen phosphate by mass of phosphogypsum, 0.01% of oxalic acid by mass of phosphogypsum, and 0.005% of ethylenediaminetetraacetic acid by mass of phosphogypsum; the raw materials entering the first tank are stirred and reacted at 90°C (stirring speed 190r / min) for 10min; the reaction product enters the second tank and continues to stir (stirring speed 45r / min), and reacts at 60°C for 30min; the reaction product enters the third tank again, and stirs and reacts at 55°C and 40r / min for 20min, and is filtered. The solid is washed for the first time with the second washing liquid of Example 2, and washed for the second time with water, and the filtrate and the first washing liquid are combined to obtain a phosphorus-rich product, which enters the wet phosphoric acid system for further recovery. The results are shown in Table 3; Table 3 Composition of raw phosphogypsum and purified phosphogypsum .

Claims

1. A method for recovering solid phase phosphorus and eutectic phosphorus in phosphogypsum, characterized in that: The phosphogypsum, targeted crystal form regulator and water are mixed to form phosphogypsum slurry, and the phosphogypsum slurry is added to the first tank of the crystallization reactor, and stirred and reacted at 80-90°C and 120-200r / min for 10-30min; the reaction product enters the second tank, and stirred and reacted at 30-60°C and 30-80r / min for 30-60min; the reaction product enters the third tank, and stirred and reacted at 30-60°C and 20-60r / min for 20-30min, solid-liquid separation, solid washing, and combining the separated liquid and washing liquid to obtain a phosphorus-rich product, thereby realizing the recovery of solid phase phosphorus and eutectic phosphorus in the phosphogypsum.

2. The method for recovering solid phase phosphorus and eutectic phosphorus in phosphogypsum according to claim 1, characterized in that: The solid-liquid volume ratio of phosphogypsum to water is 1:3~5.

3. The method for recovering solid phase phosphorus and eutectic phosphorus in phosphogypsum according to claim 1, characterized in that: The targeted crystal form regulator is composed of regulator A and regulator B. Regulator A is sodium phosphate, and its addition amount is 0.01%~0.03% of the mass of phosphogypsum; regulator B is composed of 0.05%~0.08% of sodium dihydrogen phosphate by mass of phosphogypsum, 0.005%~0.01% of oxalic acid by mass of phosphogypsum, and 0.001%~0.005% of ethylenediaminetetraacetic acid by mass of phosphogypsum.

4. The method for recovering solid phase phosphorus and eutectic phosphorus in phosphogypsum according to claim 1, characterized in that: The solid was washed twice.