Leak prevention measures for underground acid tanks
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I have a total of 6 underground tanks for concentrated acid in my workshop, and recently it was found that the dry-suction type underground tanks in the old system are leaking acid severely! The aforementioned acid-leakage underground tank has a steel-lined tile structure and is located in a pit; this pit is constructed from reinforced concrete, with an inner diameter that is 15 cm larger than the outer diameter of the tank. The disadvantages of doing this are: 1. Acid leakage is not easy to detect ； 2. The acid leakage point is difficult to handle. Another possible issue is related to the structure of the underground tank; currently, the cylindrical tank walls are lined with acid-resistant tiles, and it’s very difficult to handle this properly. In my workshop, leaks of acid from the underground tanks have occurred frequently!
Most of the underground tanks currently under construction still use acid-resistant tiles as lining for their cylindrical structures. There are various reasons for acid leakage, and it seems that current manufacturers do not have any effective solutions for this problem. In most cases, the entire underground tank has to be replaced; of course, the foundation of the tank as well as the interior of the pit need to be treated to prevent corrosion.
It mainly depends on the location of the sulfuric acid plant; if it is in a mountainous area, the problem can be easily resolved. 1. By taking advantage of the height differences in the mountains, the underground channel can be placed at the edge of a ridge, turning it into an above-ground channel. 2. Or lead the pipe out from the bottom of the underground pit ；
In the projects I have worked on, square concrete pits were used, with two underground channels placed inside these pits; sufficient space was left between the channels and the pit walls for maintenance purposes. The bottom of the pit is lined with acid-resistant ceramic tiles, while the walls are covered with acid-resistant ceramic slabs for corrosion protection; shallow grooves are present around the pit to collect any leaked acid into a small secondary pit, where it can be pumped and reused. The key is that the underground trench foundation must be higher than the bottom surface of the pit, and the bottom surface of the pit should have a slope that directs water flow toward the ditch.
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The circulation tank of dry absorption towers is designed in such a way that the tower and the tank are integrated together; the outer layer is made of carbon steel, while the inner layer is lined with the special steel XDS – a high-silicon austenitic stainless steel. No bricks are needed for lining, and this design is already in use at Jinchuan in Gansu. The pipes used in dry absorption systems are also made of this material; it performs well, though its cost is relatively high.
It’s best to use a cast-iron pot (around 10 cubic feet); we’ve used one for many years with no leaks. Raise the edge of the pot 300 millimeters above the ground, construct a top cover for installing the pump, and then build a rain shelter. It’s truly a one-time solution. :victory:
The glue injection sealing technique is very effective for our circulating acid tanks and underground tanks. Our company deals with leaks at the joints of mother-and-child tanks that use suction; we employed the glue injection sealing technique from Yancheng, Shandong. They said that this method can seal leaks whether there is acid present or not. In terms of the effectiveness of sealing, it’s better to empty the acid first, as that yields better results.
Using acid-resistant concrete with dense sodium silicate also yields very good results.