Dilute nitric acid concentration
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There is a lot of dilute nitric acid in the industrial waste water of our factory, which needs to be concentrated. What materials should be used and what process should be used?
It can be concentrated by distillation, or used to dilute concentrated nitric acid (or dilute nitric acid with high concentration)
It is my personal opinion that the third floor of nitric acid in industrial wastewater will not work. Please give me more advice.
It depends on what concentration needs to be mentioned. If the concentration is below 68.4%, use the distillation method. If it exceeds 68.4%, it needs to be divided into two steps. Distillation first, and then concentration with magnesium nitrate. Because dilute nitric acid and water form a binary azeotrope, the azeotropic point concentration is 68.4%. The temperature is 120.05 degrees. If you want to make concentrated nitric acid, you need to add the dehydrating agent magnesium nitrate.
We have a set of high-efficiency and energy-saving membrane separation technology that can more economically recover nitric acid and recycle water from dilute nitric acid wastewater. The first step: Operating between 40-70 degrees, the dilute nitric acid wastewater is concentrated to contain 15% hydrochloric acid, and the nitric acid in the recovered water does not exceed 0. 01%. Each ton of dilute nitric acid processed consumes low-temperature heat energy equivalent to 0.1 - 0.2 tons of normal pressure steam. Step 2: Operating between 50-90 degrees, the pickling wastewater continues to be concentrated to contain 55-60% hydrochloric acid, and the nitric acid in the recovered water does not exceed 0. 1% (it can be mixed into the original acid wastewater and recycled). The low-temperature heat energy consumed per ton of dilute nitric acid processed is equivalent to 1 ton of atmospheric pressure steam. The process we developed can be used to concentrate dilute acid, alkali and brine solutions. This process does not require high temperature, high pressure or negative pressure (or vacuum) to operate. This process can use low-temperature heat sources (50-120 degrees) as a driving force, but the heat energy utilization rate (water production ratio) is better than multi-stage flash evaporation and multi-effect evaporation. Of course, the heat energy utilization rate is several times or even ten times better than that of the stripping and distillation process. Another feature of this process is that most of the equipment used is plastic, thus completely overcoming the corrosion problem of multi-stage flash evaporation and multiple-effect evaporation operations. The compactness of the equipment used in this process is close to reverse osmosis, so for a given separation task, its equipment is much smaller than the equipment volume of multi-stage flash evaporation and multiple-effect evaporation. If you are interested, you can contact me at my email address: yqin@chembrane.com or yjqin1@yahoo.com .
If the concentration is too low, the cost of increasing the concentration will be too high, making it uneconomical.
This makes sense. If you quantify what you said, it means that if sulfuric acid is less than 1%, hydrochloric acid is less than 0.5%, nitric acid is less than 0.4%, phosphoric acid is less than 0.2%, acetic acid is less than 0.5, it is not economical to recycle it by this method. It should be about 5-10 yuan to treat one ton of wastewater.
I wonder if the plant has a dilute nitric acid device? If there is water that can be used as a dilute nitric acid device (it is best to have a 270,000-ton double-pressurized dilute nitric acid device, then you don’t have to worry), if not, it can be used as a detergent in the power plant (replacing low-concentration hydrochloric acid washing).