In the midsummer, a coastal sewage treatment plant encountered an unexpected dilemma: large areas of polyaluminium chloride (PAC) piled in the warehouse agglomerated, and the dosing system was frequently blocked, resulting in fluctuations in the water quality of the biochemical section and continuous excess of the total phosphorus index in the effluent. This phenomenon revealed a summer hidden danger that is often overlooked in the application of polyaluminium chloride - the storage agglomeration problem in high temperature and high humidity environments. Today, Zhengzhou Xinhuan Company will explain the high temperature agglomeration problem of polyaluminium chloride to you. Let's follow us to learn about it.
Problem of high-temperature agglomeration of polyaluminium chloride:
After continuous heavy rain, the barreled PAC (28% aluminium content) stored in the factory had hard lumps at the bottom of the barrels, and even sparks when it was manually broken. Laboratory tests showed that the dissolution time of agglomerated PAC was extended from 20 minutes at room temperature to 2 hours, and the viscosity of the solution increased abnormally after dissolution. Through environmental simulation experiments, technicians restored the agglomeration process:
Hygroscopic chain reaction:The hydroxyl structure of polyaluminium chloride PAC makes it highly hygroscopic.When the relative humidity exceeds 75% (typical coastal environment in summer), a slightly soluble layer is formed on the surface of the particles.As water penetrates, the aluminium ions hydrolyze to produce a local acidic environment, which accelerates the cementation between particles.
Crystal transformation inducement: High temperature (>30°C) accelerates the transformation of polyaluminium chloride PAC from amorphous to crystalline state. XRD analysis shows that the proportion of β-AlO(OH) crystal phase in the agglomerated sample increased by 42%, and the crystal growth caused the porosity to decrease by 37%.
Mechanical stress superposition: The vibration generated by forklift handling causes the slightly wet particles to produce a "cold welding" effect, and the contact points between the particles form a bond due to the intermolecular force.
Solution to the agglomeration problem of polyaluminium chloride PAC:
In order to cure the stubborn problem of agglomeration, the factory implemented multi-dimensional improvement measures:
Environmental control upgrade: Add an industrial dehumidifier in the warehouse to control the relative humidity below 60%; install a temperature and humidity linkage alarm system to automatically start the ventilation equipment when the environmental parameters exceed the standard.
Packaging process innovation: Use woven bags covered with polyethylene film, and fill them with nitrogen to replace the air in the bag during packaging. Accelerated aging tests show that the improved packaging can keep PAC in an environment of RH85% for 90 days without agglomeration.
Dosing system transformation: Add a vibration screening device in the silo to break potential agglomerates using 200Hz low-frequency vibration; replace the screw conveyor with a pneumatic conveying system to avoid secondary agglomeration caused by mechanical extrusion.
Chemical pretreatment technology: An ultrasonic disperser is added to the polyaluminium chloride (PAC) dissolution tank to break up the agglomerated particles through the 20kHz ultrasonic cavitation effect, so that the dissolution efficiency is restored to the normal level.
After the transformation, the agglomeration rate of polyaluminium chloride (PAC) in the plant dropped from 35% to 1.2%, the dissolution time was stabilized within 25 minutes, the total phosphorus index of the effluent was restored to below 0.3mg/L, and the annual chemical loss was reduced by 180,000 yuan.
The storage agglomeration problem of polyaluminium chloride is essentially the result of the interaction between environmental factors and material properties. By building a three-in-one prevention and control system of "environment-packaging-process", it not only solves the management problem in summer, but also inspires us: in the era of refined operation, the effectiveness of water treatment chemicals is no longer limited to the chemical properties themselves, but extends to the full process management of storage, transportation, and addition. If you encounter any other problems during use, please feel free to contact the polyaluminium chloride manufacturer Xinhuan Company, and we will arrange professional technicians to communicate with you to help you solve the problem.
The main products of flocculant manufacturer Xinhuan Water Treatment are:
White polyaluminium chloride (food grade), drinking grade polyaluminium chloride, industrial grade polyaluminium chloride, anionic polyacrylamide, cationic polyacrylamide, nonionic polyacrylamide, petroleum recycling polyacrylamide, oil recovery polyacrylamide, polyacrylamide, polymer flocculant polymer flocculation coagulant, polymeric ferrous sulphate, polyferric aluminium chloride and other water treatment chemicals. Welcome customers to write to us to negotiate business! Tel/WhatsApp：+8619003830067 Email：joanna@xhwtm.com Contact:Joanna
