CN-117682543-B - Method for recycling high-calcium magnesium phosphate tailings

Abstract

The invention discloses a method for recycling high-calcium magnesium phosphate tailings, which comprises the steps of adding leaching agent and water into phosphate tailings to obtain calcium magnesium leaching solution and high-quality phosphorite, adding pH regulator and surfactant into the calcium magnesium leaching solution, reacting, filtering to obtain calcium leaching solution and impurity-containing magnesium hydroxide slag, adding alkaline substances into the calcium leaching solution, introducing CO 2 to prepare light calcium carbonate and salt solution, introducing CO 2 to prepare magnesium bicarbonate solution after pulping the magnesium hydroxide slag, and finally pyrolyzing, filtering, washing and drying to obtain light magnesium carbonate. According to the invention, the calcium element and the magnesium element in the high-calcium magnesium solid waste are efficiently separated, the high-purity light calcium carbonate, the high-quality magnesium carbonate and the high-quality phosphorite are prepared, the CO 2 generated in the process is recycled, and the emission of greenhouse gases is reduced. The invention realizes the high-value utilization of the phosphate tailings, and has high product purity and simple process.

Inventors

• Dong Kangni
• ZHENG GUANGMING
• LI FANG
• ZHU HE
• SUN HUALIN
• WANG FENGLING
• YIN HUIBIN
• Hu Panjin
• GAO XIANHONG

Assignees

• 宜都兴发化工有限公司

Dates

Publication Date

20260508

Application Date

20231114

Claims (8)

1. 1. A method for recycling high-calcium magnesium phosphate tailings is characterized by comprising the following steps: (1) Grinding the phosphate tailings and sieving the phosphate tailings with a 100-mesh sieve to obtain phosphate tailings powder; (2) Mixing the phosphorus tailing powder, the leaching agent and water in proportion, fully stirring and reacting, and filtering to obtain calcium-magnesium leaching solution and phosphorite; (3) Adding a pH regulator and a surfactant into the calcium-magnesium leaching solution obtained in the step (2), stirring for reaction, standing, cooling, and filtering to obtain a calcium leaching solution and magnesium hydroxide slag containing impurities; (4) Adding ammonia water into the calcium leaching solution obtained in the step (3), introducing CO 2 , reacting while stirring, stopping ventilation when the pH value of the solution is 8, continuously stirring for 0.5-1h, and filtering to obtain light calcium carbonate and ammonium salt solution; (5) Adding water into the magnesium hydroxide slag containing the impurities obtained in the step (3) to prepare 10-20wt% of magnesium hydroxide slag slurry, introducing CO 2 , reacting while stirring, stopping ventilation when the pH value of the solution is 7, and filtering to obtain a magnesium bicarbonate solution; (6) Pyrolyzing, filtering and drying the magnesium bicarbonate solution obtained in the step (5) to obtain light magnesium carbonate; (7) Concentrating and crystallizing the ammonium salt solution obtained in the step (4) to recover ammonium salt crystals; The leaching agent is prepared by compounding 30-70% of gluconic acid, 10-25% of lactic acid, 10-25% of acetic acid and 10-20% of iminosuccinic acid according to mass percentage.
2. 2. The method for recycling high-calcium magnesium phosphate tailings according to claim 1, wherein the mass ratio of the phosphate tailings powder to the leaching agent to the water in the step (2) is 1:2-3:6-12, the reaction temperature is 80-90 ℃, and the reaction time is 3-5h.
3. 3. The method for recycling high-calcium magnesium phosphate tailings according to claim 1, wherein the pH regulator in the step (3) is calcium oxide, the pH value of calcium magnesium leaching solution after calcium oxide is added is 11, the surfactant is butyl titanate, the reaction temperature is 80-90 ℃, and the reaction time is 0.5-1h.
4. 4. The method for recycling high-calcium magnesium phosphate tailings according to claim 3, wherein the amount of the surfactant is 2.6 per mill of the mass of the phosphate tailings powder.
5. 5. The method for recycling high-calcium magnesium phosphate tailings according to claim 1, wherein the mass ratio of the ammonia water to the leaching agent in the step (4) is 2.05-3.15:1, and the pH value of the solution when ventilation is stopped is 8.
6. 6. The method for recycling high-calcium magnesium phosphate tailings according to claim 1, wherein the flow rate of CO 2 introduced in the step (4) and the step (5) is 300-500mL/min.
7. 7. The method for recycling high-calcium magnesium phosphate tailings according to claim 1, wherein the pyrolysis temperature in the step (6) is 70-80 ℃ and the drying temperature is 200-240 ℃.
8. 8. The method for recycling high-calcium magnesium phosphate tailings according to claim 1, wherein CO 2 generated in the reaction of the step (2) is collected and mixed with CO 2 generated in the pyrolysis of the step (6) to obtain 20-35% of CO 2 by mass fraction, and then the collected CO 2 is introduced into the step (4) and the step (5) for reaction.

Description

Method for recycling high-calcium magnesium phosphate tailings Technical Field The invention belongs to the technical field of recycling of inner tailings, and particularly relates to a method for recycling high-calcium magnesium phosphate tailings. Background The phosphate tailings are high-calcium magnesium solid waste generated in the phosphate ore dressing process, the main chemical compositions of the phosphate tailings are CaO, mgO, siO 2, P 2O5 and the like, the comprehensive utilization rate of the phosphate tailings in China is low, a large amount of phosphate tailings are piled up in a tailings pond, and the piled up tailings not only occupy a large amount of land resources, but also can influence the surrounding ecological environment. The phosphate tailings are rich in elements such as calcium and magnesium, and the elements in the phosphate tailings are extracted and converted, so that the yield of the tailings can be reduced, and the phosphate tailings can be converted into products with high added value, and the economic benefit is brought while the environmental pollution is solved, the ecological environment is improved, and the domestic soil is remedied. At present, the comprehensive utilization way of the phosphate tailings mainly comprises the steps of phosphate concentrate re-separation, mine filling, building material preparation, phosphate fertilizer production, glass ceramics preparation and the like. However, the development difficulty of the agents used in the flotation method is high because the phosphorus content of the phosphate tailings is low, and the development of the phosphate tailings into building material products and fertilizers has low product value although a large amount of phosphate tailings can be consumed. The method for converting the calcium and magnesium in the phosphate tailings into the light calcium carbonate and the light magnesium carbonate is a method for efficiently utilizing the calcium and magnesium elements in the phosphate tailings, and is also a way for realizing high-value utilization of the phosphate tailings. The key point of the preparation of the light calcium carbonate and the light magnesium carbonate from the phosphate tailings is to separate calcium and magnesium, and the current methods for separating calcium and magnesium in the phosphate tailings comprise a carbonization method, an acidolysis method and an ammonium leaching method. The carbonization method is to calcine phosphate tailings, digest and carbonize the phosphate tailings, wherein calcium is converted into calcium carbonate to be present in filter residues, magnesium exists in a filtrate in the form of magnesium bicarbonate, for example, the method is adopted in the CN102923739A patent to separate calcium and magnesium, but the obtained calcium carbonate product contains unreacted magnesium and insoluble impurities, the product purity is low, and a large amount of energy is consumed for calcination. The acidolysis method is to add hydrochloric acid, sulfuric acid, organic acid and the like to dissolve magnesium and calcium in the phosphate tailings, then to realize calcium-magnesium separation by adding a precipitant or carbonizing, for example, in the CN111484063A patent, hydrochloric acid is adopted to dissolve the phosphate tailings to obtain filtrate containing calcium and magnesium, and then decalcifying agent is adopted to precipitate calcium to obtain calcium sulfate whisker, and as elements such as iron, aluminum and the like in the phosphate tailings are released in the acidolysis process, the prepared calcium-magnesium product contains the metal elements. The ammonium leaching method is to leach calcined phosphate tailings by ammonium salt, separate calcium and magnesium by leaching for multiple times, for example, in the CN104860278A patent, leach calcium by ammonium nitrate and leach magnesium in filter residues by ammonium sulfate, and the leaching rate is low and the energy consumption is high. In summary, the phosphogypsum for preparing the light calcium carbonate and the light magnesium carbonate has the technical defects of insufficient product purity, high energy consumption, complex process and the like, and especially the problem of low product purity is a key for restricting the high-value utilization technology of the phosphate tailings to the industrialization, and the method for efficiently separating calcium and magnesium in the phosphate tailings is continuously developed to obtain the high-purity calcium and magnesium product, and meanwhile, the process is simplified and the energy consumption is reduced. Disclosure of Invention Aiming at the technical problems, the invention provides a method for recycling high-calcium magnesium phosphate tailings, which utilizes the reaction of compound organic acid and calcium magnesium in the phosphate tailings to generate soluble chelated calcium magnesium, then adjusts the pH value, adds a surfactant to separat