Is it true that the lower the outlet temperature for the purification of acid produced from smelting flue gas, the better?
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It is likely that over the past decade, the introduction of advanced smelting furnaces has led to a significant increase in the concentration of smelting flue gases, creating favorable conditions for producing acid from such gases. So, in the new era, is it true that the outlet temperature of the acid production purification process using smelting flue gas should be as low as possible? For the acid production system using smelting flue gas, the waste acid that needs to be purified before discharge must have its heavy metals and arsenic removed, which results in high treatment costs; if the amount of waste acid requiring purification can be reduced, the treatment expenses can also be lowered. In just a short time, it was found that some users deliberately raised the temperature at the purification outlet in order to reduce the amount of waste discharged as a result of purification. From the perspective of reducing the amount of waste gas generated during purification, in the case of acid production using high-concentration smelting flue gas, it is possible to increase the temperature at the purification outlet appropriately, thanks to the enhanced capacity for dry absorption balance, thereby reducing the amount of waste gas produced.
The primary factor we use to regulate the flow of acidic waste in our plant is acidity, and the second factor is arsenic content. In any case, arsenic must not enter the dry absorption conversion process; it always has to be removed from the acid production system. Even if the arsenic level in the primary scrubber is kept high, the amount of arsenic removed per day remains the same.
Is the first step in arsenic removal using sulfurous acid also arsenic removal using sodium sulfide? ?
This post was last edited by yywot on 2018-7-11 at 11:36. Our acidic waste has SO2 removed from it in the purification area using negative pressure in the flue, and then it is sent on to the waste acid treatment station. The first step upon arriving at the spent acid treatment station is to add sodium sulfide.
Reducing the amount of waste discharged cannot significantly lower the costs associated with treating acidic waste； The cost of acid treatment consists of electricity costs and chemical costs ； The electricity cost is related to the amount of acidic waste generated, but the cost of chemical treatment depends on the level of SO3 production and the impurity content in the acidic waste; therefore, this cost does not change with the amount of acidic waste. Therefore, the control of the temperature at the purification outlet is not primarily aimed at regulating the amount of acidic waste generated; rather, it takes into account the following factors: 1) the concentration of the purified acid (to remain within the requirements for fiberglass and to meet the needs of arsenic removal via sulfidation); 2) the concentration of F ions in the purified acidic waste; 3) the water flow rate required for adding water glass; 4) the amount of water that needs to be added to the purification process. For the items mentioned above, when the concentrations in items 1 and 2 are low, appropriately increasing the temperature of the flue gas at the purification outlet helps to control the amount of acidic waste generated and reduce the amount of water in the treated effluent, thereby creating conditions for emission reduction