Purification and iron removal process for waste hydrochloric acid

Abstract

The invention relates to a waste hydrochloric acid purification and iron removal process, which comprises the following steps: (1) waste acid filtration: carrying out a filtration process on waste hydrochloric acid to obtain a filtered liquid; (2) resin pretreatment: firstly backwashing the quaternary amine type strong-basicity ion exchange resin by using diluted hydrochloric acid, then washing and transforming by using a NaOH solution, and finally washing by using pure water until the Na content is lower than 5.0 ppm; (3) adsorption: adsorbing the filtered liquid by using the quaternary amine type strong-basicity ion exchange resin obtained in the step (2) until the iron content of the adsorbed liquid is within 5.0 ppm; (4) regeneration: eluting and washing the resin obtained in the step (3) after adsorption saturation to obtain regenerated qualified ion exchange resin; and returning the regenerated ion exchange resin to the step (3) to remove the iron in the waste hydrochloric acid for the next time. The method is simple in process, low in cost, efficient and environmentally friendly, and the production efficiency and economic benefits are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy of non-ferrous metals, and particularly to a process for purifying and removing iron from waste hydrochloric acid. Background Art

[0002] In the process of non-ferrous metal metallurgy, waste hydrochloric acid mainly comes from the production process of high-quality nickel salt products. Waste hydrochloric acid usually contains a high concentration of iron ions, which not only affects its reuse value but also may cause corrosion to equipment and increase the cost of subsequent treatment. At present, the methods for purifying and removing iron from waste hydrochloric acid mainly include chemical precipitation method, membrane separation method, electrochemistry method, etc. However, these methods have some deficiencies: (1) Chemical precipitation method: Iron ions are formed into precipitates by adding chemical agents and then removed by filtration. Although this method is simple, the consumption of chemical agents is large, the treatment cost of the generated sludge is high, and it is difficult to achieve a high iron removal effect. (2) Membrane separation method: Using the selective permeability of membrane materials to separate iron ions from waste acid. This method has high requirements for membrane materials, and the membrane is easily contaminated and needs to be cleaned or replaced regularly, with high maintenance costs. (3) Electrochemistry method: Iron ions are reduced and precipitated at the cathode through electrolysis to achieve iron removal. This method has high energy consumption, complex equipment, and great operation difficulty. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a process for purifying and removing iron from waste hydrochloric acid that is simple in process, low in cost, highly efficient and environmentally friendly.

[0004] To solve the above problems, a process for purifying and removing iron from waste hydrochloric acid according to the present invention includes the following steps: ⑴ Filtration of waste acid: The waste hydrochloric acid with a temperature of 40 - 50 °C, a hydrogen ion concentration of 4.0 - 6.0 g / L, and an iron content of 0.2 - 0.5 g / L is subjected to a filtration process to obtain a filtered solution. ⑵ Pretreatment of resin: The quaternary ammonium type strongly basic ion exchange resin is first backwashed with dilute hydrochloric acid with a volume concentration of 2% - 10%, then washed and transformed with a NaOH solution with a mass concentration of 2% - 5%, and finally washed with pure water until the Na content is lower than 5.0 ppm. ⑶ Adsorption: The filtered solution is adsorbed with the quaternary ammonium type strongly basic ion exchange resin obtained in the step ⑵ until the iron content in the adsorbed solution is within 5.0 ppm. ⑷ Regeneration: The resin saturated with adsorption obtained in step (3) is eluted with a NaCl solution having a mass concentration of 5% - 15%, and then washed with pure water until the Na content is lower than 5.0 ppm, thus obtaining a regenerated and qualified ion exchange resin; the ion exchange resin after this regeneration treatment is returned to step (3) for the next removal of iron from waste hydrochloric acid.

[0005] In step (1), the filtration method is filter paper filtration or microfiltration; for filter paper filtration, filter paper with a pore size of 1.0 - 3.0 microns is used; for microfiltration, a filter membrane with a pore size of 0.3 - 2.0 microns is used.

[0006] In step (2), the elution flow rate of the dilute hydrochloric acid is 5.0 - 10.0 BV / h, and the time is 3.0 - 8.0 h.

[0007] In step (2), the washing flow rate of the NaOH solution is 2 - 5 BV / h, and the time is 2 - 3.5 h.

[0008] In step (3), the adsorption flow rate of the filtered liquid is 3.0 - 6.0 BV / h.

[0009] In step (4), the elution flow rate of the NaCl solution is 6.0 - 9.0 BV / h, and the time is 4.0 - 7.0 h.

[0010] The present invention has the following advantages compared with the prior art: 1. The present invention first pre-treats the quaternary ammonium strong basic ion exchange resin, aiming to facilitate the subsequent adsorption of iron in hydrochloric acid.

[0011] 2. The present invention uses the pre-treated quaternary ammonium strong basic ion exchange resin for iron adsorption removal, and no impurities will be introduced during the impurity removal process, avoiding the influence of other additives on the quality of hydrochloric acid.

[0012] 3. The present invention can complete the iron removal from waste hydrochloric acid only by filtration and adsorption. The process is not only simple, low-cost, but also highly efficient and environmentally friendly, effectively improving the production efficiency and economic benefits. Specific Embodiments

[0013] A process for purifying and removing iron from waste hydrochloric acid includes the following steps: (1) Waste acid filtration: The waste hydrochloric acid with a temperature of 40 - 50 °C, a hydrogen ion concentration of 4.0 - 6.0 g / L, and an iron content of 0.2 - 0.5 g / L is subjected to a filtration process to remove insoluble impurities, thus obtaining a filtered liquid.

[0014] Among them: the filtration method is filter paper filtration or microfiltration; for filter paper filtration, filter paper with a pore size of 1.0 - 3.0 microns is used; for microfiltration, a filter membrane with a pore size of 0.3 - 2.0 microns is used.

[0015] ⑵ Resin pretreatment: For the quaternary ammonium strong basic ion exchange resin, first backwash it with dilute hydrochloric acid with a volume concentration of 2% - 10%, the elution flow rate is 5.0 - 10.0 BV / h, and the time is 3.0 - 8.0 h. Then wash and transform it with a NaOH solution with a mass concentration of 2% - 5%, the washing flow rate is 2 - 5 BV / h, and the time is 2 - 3.5 h. Finally, wash it with pure water until the Na content is lower than 5.0 ppm.

[0016] Through pretreatment cleaning or filtration, impurities, bubbles or undissolved particles in the resin can be removed, thereby improving the purity and adsorption performance of the resin.

[0017] ⑶ Adsorption: The filtered liquid is adsorbed using the quaternary ammonium strong basic ion exchange resin obtained in step ⑵, the adsorption flow rate is 3.0 - 6.0 BV / h, until the iron content in the adsorbed liquid is within 5.0 ppm, reaching the system reuse standard.

[0018] ⑷ Regeneration: The resin saturated with adsorption obtained in step ⑶ is eluted with a NaCl solution with a mass concentration of 5% - 15%, the elution flow rate is 6.0 - 9.0 BV / h, and the time is 4.0 - 7.0 h. After washing with pure water until the Na content is lower than 5.0 ppm, the regenerated qualified ion exchange resin is obtained; the ion exchange resin after this regeneration treatment is returned to step ⑶ for the next removal of iron in waste hydrochloric acid.

[0019] Example 1 ⑴ Waste acid filtration: Take 5000 mL of waste acid, the temperature of the waste hydrochloric acid is 45°C, the hydrogen ion concentration is 5.0 g / L, and the iron content is 0.3 g / L. Remove insoluble impurities by means of filter paper filtration, and the filtered liquid enters the resin adsorption process.

[0020] ⑵ Pretreatment process: Before using the newly filled resin column, first backwash it with 5% dilute hydrochloric acid, the backwash flow rate is 7.5 BV / h, and the time is 5.5 h. Then transform it with 3% NaOH, the transformation flow rate is 3.5 BV / h, and the time is 2.5 h. Finally, wash it with pure water until the Na content of the resin effluent is 5.0 ppm.

[0021] ⑶ Adsorption process: The filtered liquid is adsorbed using the quaternary ammonium strong basic ion exchange resin, the adsorption flow rate is 4.5 BV / h, and the iron content of the adsorbed liquid is 4.0 ppm, reaching the system reuse standard.

[0022] ⑷ Regeneration process: The resin after adsorption saturation was eluted with 10% NaCl at an elution flow rate of 7.5 BV / h for 5.5 h, and then washed with pure water until the Na content was lower than 4.25 ppm to obtain a regenerated qualified ion exchange resin. The ion exchange resin after regeneration treatment was returned to the adsorption process for the removal of iron in waste acid in the next cycle.

[0023] Example 2 ⑴ Waste acid filtration: Take 5000 mL of waste acid with a temperature of 42 °C, a hydrogen ion concentration of 4.5 g / L, and an iron content of 0.4 g / L. The insoluble impurities were removed by microfiltration, and the filtered liquid entered the resin adsorption process.

[0024] ⑵ Pretreatment process: Before use, the newly filled resin column was backwashed with 8% dilute hydrochloric acid at a backwash flow rate of 6.0 BV / h for 6.0 h. Then it was transformed with 4% NaOH at a transformation flow rate of 4.0 BV / h for 3.0 h. Finally, it was washed with pure water until the Na content in the resin effluent was lower than 5.0 ppm.

[0025] ⑶ Adsorption process: The filtered liquid was adsorbed using a quaternary amine type strongly basic ion exchange resin at an adsorption flow rate of 5.0 BV / h. The iron content in the adsorbed liquid was 3.5 ppm, meeting the system reuse standard.

[0026] ⑷ Regeneration process: The resin after adsorption saturation was eluted with 12% NaCl at an elution flow rate of 8.0 BV / h for 6.0 h. Then it was washed with pure water until the Na content was lower than 5.0 ppm to obtain a regenerated qualified ion exchange resin. The ion exchange resin after regeneration treatment was returned to the adsorption process for the removal of iron in waste acid in the next cycle.

[0027] Example 3 ⑴ Waste acid filtration: Take 5000 mL of waste acid with a temperature of 48 °C, a hydrogen ion concentration of 5.5 g / L, and an iron content of 0.2 g / L. The insoluble impurities were removed by filter paper filtration, and the filtered liquid entered the resin adsorption process.

[0028] ⑵ Pretreatment process: Before use, the newly filled resin column was backwashed with 3% dilute hydrochloric acid at a backwash flow rate of 5.0 BV / h for 4.0 h, then transformed with 2% NaOH at a transformation flow rate of 2.5 BV / h for 2.0 h, and finally washed with pure water until the Na content in the resin effluent was lower than 5.0 ppm.

[0029] ⑶ Adsorption process: The filtered liquid is adsorbed by quaternary ammonium strong base ion exchange resin. The adsorption flow rate is 3.5 BV / h. The iron content in the adsorbed liquid is 4.5 ppm, meeting the system reuse standard.

[0030] ⑷ Regeneration process: The resin saturated by adsorption is eluted with 5% NaCl. The elution flow rate is 6.0 BV / h and the time is 4.0 h. Then it is washed with pure water until the Na content is lower than 5.0 ppm, obtaining the ion exchange resin qualified for regeneration. The ion exchange resin after regeneration treatment is returned to the adsorption process for removing iron in the waste acid next time.

[0031] Example 4 ⑴ Waste acid filtration: Take 5000 mL of waste acid. The temperature of the waste hydrochloric acid is 43 °C, the hydrogen ion concentration is 4.8 g / L, and the iron content is 0.5 g / L. Microporous filtration is used to remove insoluble impurities. The filtered liquid enters the resin adsorption process.

[0032] ⑵ Pretreatment process: Before use, the newly filled resin column is backwashed with 6% dilute hydrochloric acid. The backwash flow rate is 7.0 BV / h and the time is 5.0 h. Then it is transformed with 3% NaOH. The transformation flow rate is 3.0 BV / h and the time is 2.5 h. Finally, it is washed with pure water until the Na content in the resin effluent is lower than 5.0 ppm.

[0033] ⑶ Adsorption process: The filtered liquid is adsorbed by quaternary ammonium strong base ion exchange resin. The adsorption flow rate is 4.0 BV / h. The iron content in the adsorbed liquid is 3.0 ppm, meeting the system reuse standard.

[0034] ⑷ Regeneration process: The resin saturated by adsorption is eluted with 15% NaCl. The elution flow rate is 9.0 BV / h and the time is 7.0 h. Then it is washed with pure water until the Na content is lower than 5.0 ppm, obtaining the ion exchange resin qualified for regeneration. The ion exchange resin after regeneration treatment is returned to the adsorption process for removing iron in the waste acid next time.

[0035] Example 5 ⑴ Waste acid filtration: Take 5000 mL of waste acid. The temperature of the waste hydrochloric acid is 46 °C, the hydrogen ion concentration is 5.2 g / L, and the iron content is 0.35 g / L. Filter paper filtration is used to remove insoluble impurities. The filtered liquid enters the resin adsorption process.

[0036] ⑵ Pretreatment process: Before use, the newly filled resin column is backwashed with 4% dilute hydrochloric acid at a backwashing flow rate of 6.5 BV / h for 4.5 h. Then it is transformed with 3% NaOH at a transformation flow rate of 3.5 BV / h for 2.5 h. Finally, it is washed with pure water until the Na content in the resin effluent is lower than 5.0 ppm.

[0037] (3) Adsorption process: The filtered liquid is adsorbed using quaternary amine strongly basic ion exchange resin at an adsorption flow rate of 4.5 BV / h. The iron content in the adsorbed liquid is 4.0 ppm, meeting the system reuse standard.

[0038] (4) Regeneration process: The resin saturated with adsorption is eluted with 10% NaCl at an elution flow rate of 7.0 BV / h for 5.5 h. Then it is washed with pure water until the Na content is lower than 5.0 ppm to obtain regenerated qualified ion exchange resin. The ion exchange resin after regeneration treatment is returned to the adsorption process for the removal of iron in waste acid next time.

Claims

1. A purification and iron removal process for waste hydrochloric acid, comprising the following steps: ⑴ Waste acid filtration: The waste hydrochloric acid with a temperature of 40 - 50 °C, a hydrogen ion concentration of 4.0 - 6.0 g / L, and an iron content of 0.2 - 0.5 g / L is subjected to a filtration process to obtain the filtered liquid. ⑵ Resin pretreatment: The quaternary amine type strongly basic ion exchange resin is first backwashed with dilute hydrochloric acid having a volume concentration of 2% - 10%, then washed and transformed with a NaOH solution having a mass concentration of 2% - 5%, and finally washed with pure water until the Na content is lower than 5.0 ppm. ⑶ Adsorption: The filtered liquid is adsorbed using the quaternary amine type strongly basic ion exchange resin obtained in the step ⑵ until the iron content in the adsorbed liquid is within 5.0 ppm. ⑷ Regeneration: The resin saturated with adsorption obtained in the step ⑶ is eluted with a NaCl solution having a mass concentration of 5% - 15%, and after being washed with pure water until the Na content is lower than 5.0 ppm, a regenerated qualified ion exchange resin is obtained; the ion exchange resin after this regeneration treatment is returned to the step ⑶ for the next removal of iron from waste hydrochloric acid.

2. The purification and iron removal process for waste hydrochloric acid according to claim 1, characterized in that: In the step ⑴, the filtration method is filter paper filtration or microfiltration; for the filter paper filtration, a filter paper with a pore size of 1.0 - 3.0 microns is used; for the microfiltration, a filter membrane with a pore size of 0.3 - 2.0 microns is used.

3. The purification and iron removal process for waste hydrochloric acid according to claim 1, characterized in that: In the step ⑵, the elution flow rate of the dilute hydrochloric acid is 5.0 - 10.0 BV / h, and the time is 3.0 - 8.0 h.

4. The purification and iron removal process for waste hydrochloric acid according to claim 1, characterized in that: In the step ⑵, the washing flow rate of the NaOH solution is 2 - 5 BV / h, and the time is 2 - 3.5 h.

5. The purification and iron removal process for waste hydrochloric acid according to claim 1, characterized in that: In the step ⑶, the adsorption flow rate of the filtered liquid is 3.0 - 6.0 BV / h.

6. The purification and iron removal process for waste hydrochloric acid as described in claim 1, characterized in that: In the step ⑷, the elution flow rate of the NaCl solution is 6.0 - 9.0 BV / h, and the time is 4.0 - 7.0 h.