Reduce residual phosphorus in gypsum

Your question is too vague! If it is to reduce water-soluble phosphorus, control the level balance of the filtration system, manage the temperature and phosphorus content of the three wash waters, minimize the frequency of starting up and shutting down the system, and ensure stable production and operation as well as an appropriate vacuum level in the filtration system ； For insoluble phosphorus, maintain a constant amount of acid ore added, extend the reaction time as much as possible, and reduce the temperature of the extraction reaction. The designed production capacity of the extraction tank should be at least 1.2 times that of the filter when it is operating at full capacity. If possible, a low-level flash vaporization unit can be installed to reduce the residual phosphorus in the gypsum even when the plant is operating at full capacity; an digestion tank can also be used. In all cases, the goal is to extend the reaction time and lower the reaction temperature. Of course, the fineness and moisture content of the ore also have a significant impact on insoluble phosphorus!

If the gypsum crystallization is poor, how can it be adjusted? Methods other than increasing reaction time,

Adding surfactants can effectively improve gypsum crystallization. In addition to reaction time, the reaction volume is also one of the key factors that affect gypsum crystallization; after each cleaning of the extraction tank in our plant, the size of the gypsum crystals increases significantly.

Where are surfactants generally added? Can it be added to the extraction tank? Right now, the crystallization effect here is poor; the crystals are in the form of small, thin flakes. They appear quite dry when filtered, but moisture is present if you squeeze them hard. The water-soluble phosphorus content in gypsum remains high, and there are also many cases of washing out

Reply to 5# abin21: It is usually added at the slurry distributor of the filter, but this approach has a drawback – it accelerates the formation of scale in the filter and pipelines, and this effect can even extend to the concentration system. Especially after using a flocculant for some time, scaling occurs more rapidly once use is stopped; therefore, it should be used with caution. The best approach is still to increase the reaction dissolution time and reaction duration; one could consider adding a digestion tank or directly installing a low-level flash evaporation system.

It’s the reaction volume; I typed it wrong!

The issue can be examined from the following aspects: filtration efficiency (filtering capacity should not be enhanced), the location where water is added (the water should be added at a point where the filter cake in front has been dried out, but cracks should not form), the temperature of the washing water (usually above 60 degrees), and the amount of water used for washing (determined based on the operating conditions of the device).

Problems can be identified from the following aspects: filtration efficiency (filtering capacity should not be enhanced), the location where water is added (the water should be added at a point where the filter cake in front has been dried out, but cracks should not form), water temperature (usually above 60 degrees), and the amount of water used (determined based on the operating conditions of the device).

The washing efficiency is over 98%, and the extraction efficiency is over 96%.

Everything said upstairs is correct; I would like to add one more point: pay attention to controlling the liquid-phase SO3 level and the liquid-solid ratio, as these are crucial for improving both the extraction efficiency and the washing efficiency. Furthermore, when adding surfactants between the reaction tank and the filter, sufficient mixing time and space are required.