The issue of preparing KPI mortar
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Recently, our plant has been gradually adopting KPI cement linings for its sulfuric acid flue gas pipelines. However, during the construction process, a rather significant issue was quickly identified: the preparation of the mortar! Most construction firms mix the mixture directly on the cement floor; due to the high viscosity of potassium water glass, the resulting slurry appears uneven to the naked eye, which affects the quality of the lining surface. The main issues are an uneven surface of the lining and cracks, with some wire mesh even showing through! I remember that in 2005, during the installation of the acid-resistant tile linings in the drying towers and circulation tanks of our plant’s sulfuric acid III system, I took note of a particular method being used. It was a professional team from Pingxiang, Jiangxi who carried out the work, and they used large iron pots to mix the mortar, which yielded good results.
The preparation of the clay mixture must be carried out in a mixing bowl; ingredients are added in measured amounts each time, and the resulting mixture is taken out in batches for use, with it being packaged in small buckets to prevent the inclusion of foreign substances.
The lining work for the three towers and circulation tanks in our company was also carried out by a construction team from Pingxiang, Jiangxi. They used iron pots to mix the clay; there was a specialist responsible for preparing the clay mixture. He never weighed the ingredients, and when I asked why, he said it could be felt by touch – the temperatures differ in winter and summer, so it’s difficult to maintain a fixed ratio
Why does your factory line the flue pipes with KP-1?
The moisture levels are poor, there is a lot of acid buildup inside the pipes, which accelerates corrosion. Steel pipes that used to last 10–12 years can now only last around 2 years.
It’s not the temperature of the smoke that’s low; it’s the dew point that’s low.
It is the increase in moisture in the flue gas that causes the dew point to rise.
When preparing KPI mortar, it is absolutely impossible to do so on a cement floor. I have been involved in the construction of two new sulfuric acid plants, and the workers prepared the mortar in large iron pots. Since KPI mortar is applied using potassium water glass, the cured mortar sets very quickly; initial setting generally occurs within about 45 minutes. At this point, the surface of the mortar oxidizes and loses its stickiness. Therefore, only a small amount of mortar is used each time, usually around 15 kg, in order to maintain quality.