Seek advice on the use of plate and frame filter presses
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The conditions are as follows: the material is at 95–100°C, with a solid content of 40–45%; the solids consist of calcium sulfate dihydrate. There is also 10% of the material that dissolves in water at temperatures above 70°C, with the remainder being water. Solid-liquid separation is required. Question: 1. Given the high solid content, is it appropriate to use a plate and frame filter press? 2. How much free water is approximately present in the filter cake after filtration by a plate and frame filter press, once it has been blown with compressed air? 3. For the same material, which has lower free water content: the filter cake obtained by centrifugation or the one obtained by plate and frame filtration? Generally, what are the respective amounts? Thank you!
【1. The solid content is high; is it appropriate to use a plate and frame filter press? 】That’s possible, but after filtration and before cleaning, compressed air should be used for cooling before the frame panels can be opened, in order to prevent deformation.
【2、How much free water is approximately present in the filter cake after filtration by a plate and frame filter press, once it has been blown with compressed air?】 】The moisture content is roughly around 20-30%; blow on it while it’s hot, and blow for a longer period of time to achieve a lower moisture content.
It seems that the solid content is a bit high; could we first lower the temperature to allow precipitation and then filter it?
The temperature entering the filter press seems too high; both the filter cloth and the filter plates might not be able to handle it. If it is feasible to do so: 1. If a feed pressure of 6 bar is used, along with diaphragm compression and air purging, and testing is carried out using the methods employed in cement factories, the free water content is expected to be between 35-40% ； Without diaphragm compression, it can be about 4% higher ； 2. The efficiency of centrifuges varies; the separation factor ranges from 300 to 1250, so it’s difficult to determine the amount of free water. Furthermore, the method of formation of dihydrate gypsum has a significant impact on dehydration, especially the type and amount of impurities present. For your reference, as the conditions you mentioned aren’t entirely accurate either
Insurance method: Determine it after having the manufacturer conduct tests on-site. Otherwise, there is a significant gap between reality and theory.
Why not use a centrifuge?