Acid gas problem in hydrofluoric acid production slag
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Gentlemen, recently there has been a significant amount of acidic gas and dust emitted from the slag coming out of the converter. The slag is mostly in powder form. Sampling analysis conducted in the slag-gas absorption tower showed that HF is the main component present in the slag. According to one analysis report from that tower: sulfate: 0.36%, hydrofluoric acid: 5.9% (with values reaching 15% at the highest levels), and fluorosilicic acid: 1.8%. Regarding the high level of HF in the slag, what exactly is going on? I would appreciate it if experts could help analyze this.
Is there a problem with the internal return slag? Without slag returning to the furnace head to increase productivity, production must decrease.
It’s also possible that the temperature of the burner is not high enough, resulting in an insufficient reaction. Check the heating pipes to see if there are any blockages that could be causing the low temperature.
Thank you all for your replies. It seems there is a problem with the burner temperature; the pre-heating gas temperature is only 130°C, and it doesn’t rise any higher! There’s no issue with the internal return slag; it has been checked several times and everything is fine. Is it possible that the screw seal at the furnace outlet is not working properly, causing the gases inside the converter to be drawn out directly?
The temperature of the gas guide pipe is an important reference; if this temperature is high, the temperature of the mixed acid will also be high. In such cases, it is necessary to increase the amount of cooling provided by the distillation tower or other cooling systems, and as a result, the previous values will change. Is the converter current high when the gas duct temperature is low?
It’s a temperature issue; the reaction temperature at the burner is 130 degrees, which is too low. Check whether there’s a malfunction in the valve that controls the air supply to the burner, resulting in insufficient airflow Either the overall furnace temperature is too low; make sure to address that properly!
I disagree with the experts upstairs. First, it is necessary to determine the sulfuric acid content in the residue; only then can we determine whether it is a problem related to the reactions taking place inside the furnace. Each party has its own minimum standards regarding the conversion rate of these reactions. As long as no problems are detected, then there is nothing wrong with the furnace temperature； As mentioned by the poster, the levels of HF and fluorosilicic acid in the slag gas absorption stream are quite high. First, it is necessary to check the air pressure of the fan used for slag gas absorption. Second, the sealing at the furnace tail should be improved (by raising the rear end of the screw or adjusting the screw reducer). Third, and most importantly, it is necessary to examine the adherence to process protocols to determine what the negative pressure at the furnace inlet actually is
What are the inlet and outlet temperatures of the converter? Sour rice noodle ratio? How is the negative pressure being controlled?
Residence time, negative pressure, sludge sealing, temperature, sludge layer, acid-to-powder ratio and acid ratio, etc. – check each one individually