Chemical polishing solution for precipitating aluminum ions and phosphoric acid
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Process details: 1. Purpose: To recover phosphoric acid from the solution. The cleaning solution produced by the anodic chemical polishing of aluminum alloys: it is a mixture acid comprising approximately 40% of various acids, including phosphoric acid at ~20-30%, sulfuric acid at ~10%, nitric acid at ~1-2%, and aluminum ions at ~10-25 g/L. It also contains small amounts of copper, as well as some sulfuric acid amine and ammonium phosphate (the purpose of these substances is to remove the yellow smoke – nitrogen oxides – that are generated when nitric acid reacts with aluminum at high temperatures). Sulfuric acid and nitric acid can be ignored; the focus is on recovering phosphoric acid. We want to precipitate the aluminum ions first, preferably using a precipitation method (since the equipment for air flotation is relatively more complex). We want to precipitate the aluminum ions before evaporation, but we cannot neutralize the acid, nor can we generate any harmful substances as a result of this process; the goal is to remove the aluminum ions so that we can concentrate the remaining liquid, which can then be reused (added back into the process). If the ammonium bifluoride method is used, then a quaternary ammonium salt is added (I’m not sure which one would be suitable?) It’s best to precipitate it directly, then we collect the upper clear liquid and concentrate it right away. Are there any better methods besides this? Please advise, thank you Process Option 2: 80% phosphoric acid + 10% sulfuric acid + 5-8% nitric acid + 40-50 g/L of aluminum ions; the specific gravity is around 1.80-1.85. The goal here is also to precipitate the aluminum ions and recover the phosphoric acid contained in the mixture (it’s not necessary to remove sulfuric acid or nitric acid; the key is to remove the aluminum ions). Is this method effective? Are there any other simpler methods for precipitation? ）Please give me some advice! Thank you!
As a hint, BDR can be used to recycle polishing phosphoric acid. Apaik Environmental Protection Technology, Han Qiang, 15962277858, neterli@126.com. BDR phosphoric acid polishing is a widely used chemical polishing method. However, a large amount of phosphoric acid is consumed during the application of this method. That is, when the polished piece exits the polishing tank, it carries away a large amount of polishing fluid. These polishing solutions are washed away in the subsequent wash tank. Typically, the composition of the wastewater removed from the washing tanks is as follows: 1. 30-40% phosphoric acid; 2. 0-8% sulfuric acid; 3. 1-5% nitric acid; 4. 20-45 g/l aluminum ions. To treat this wastewater, a large amount of alkali is required, and significant amounts of solid waste are generated. More importantly, a large amount of high-value available chemicals, such as phosphoric acid, are wasted needlessly. The use of a BDR system can remove aluminum ions from wastewater, allowing phosphoric acid to be reused in polishing tanks.
Update: With our current technological advancements, the acid etching solutions containing two or three acids can now be reused, no longer restricted by the high concentration of acids in such solutions. Slurry and cleaning solutions can often be handled. Those who are interested can talk about it. QQ1804426805
Existing pilot-scale equipment and small-scale treatment equipment are available to provide recycling services (charged based on results).
Was the problem solved? Which quaternary ammonium salt?