Acid treatment issues in nitric acid production
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In our country, nitric acid is generally produced in combination as dilute nitric acid and concentrated nitric acid. The common method for producing concentrated nitric acid is the magnesium nitrate process, which involves converting 55% dilute nitric acid into 98% concentrated nitric acid; in this process, 0.01 cubic meters of acidic wastewater are generated per hour per ton of concentrated nitric acid, and the discharge of such wastewater can pollute the environment. For treatment, the only options are to use alkaline substances such as lime, soda ash, or caustic soda for neutralization; it can also be used as the water used in the production of dilute nitric acid. However, the exhaust gas emissions do not meet the required standards. See if a physicochemical method can be used to recover this portion of acidic wastewater, so as to avoid environmental pollution while also generating benefits. Interested netizens can come together to discuss it. China] This post was last edited by DAC The army rules the world on 2008-3-14 11:00.]
Our factory sends its acidic wastewater to the desalination unit for use in regenerating resin; this technology is well-established and many companies use it. It is a technology developed by the Xuzhou Water Treatment Research Institute. However, 3% concentration of acidic wastewater is a bit high – what is your production level like? Mine is 2.0%
We possess an efficient and energy-saving membrane separation technology that enables the economical recovery of nitric acid and recycled water from dilute nitric acid wastewater. The first step involves operating at temperatures between 40-70 degrees, concentrating the dilute nitric acid wastewater to a concentration containing 15% hydrochloric acid, with the nitric acid content in the recovered water being no more than 0.01%. The low-temperature thermal energy required to process one ton of dilute nitric acid is equivalent to 0.1–0.2 tons of steam at normal pressure. Step 2: The acid wash wastewater is further concentrated to a concentration of 55–60% hydrochloric acid, with the nitric acid content in the recovered water not exceeding 0.1% (it can be mixed back into the original acid wastewater for further recycling). The low-temperature thermal energy required to process one ton of dilute nitric acid is equivalent to that of 1 ton of steam at normal pressure. The process we have developed can be used to concentrate dilute acidic, alkaline, and saline solutions. This process does not require high temperatures, high pressures, or negative pressures (or vacuum) for operation. It can utilize low-temperature heat sources (50–120 degrees) as a driving force, and its heat efficiency (water production ratio) is better than that of multi-stage flash evaporation and multi-effect evaporation. Of course, the thermal energy utilization efficiency is several times, or even ten times, better than that of stripping and distillation processes. Another feature of this process is that the equipment used is mostly made of plastic, which completely eliminates the corrosion problems associated with multi-stage flash evaporation and multi-effect evaporation processes. The equipment required for this process is relatively compact, similar to that used in reverse osmosis; therefore, for a given separation task, the volume of the equipment needed is much smaller than that required for multi-stage flash evaporation and multi-effect evaporation. If you are interested, feel free to contact me at my email addresses: yqin@chembrane.com or yjqin1@yahoo.com.
If there is a dilute nitric acid facility, this portion of acidic wastewater can be diluted with water to an appropriate concentration, and then used as water for absorbing NOx gases in the dilute nitric acid facility.
The situation in our factory is basically concentrated evaporation