Spray drying polyaluminium chloride has high stability, wide adaptability to water area, fast hydrolysis speed, strong absorbency, rapid and large flocculation formation, low turbidity and strong dehydration. For the same water quality, spray drying polyaluminum chloride is smaller than other flocculants, especially for high pollution water quality. Spray drying products only require half of the drum drying product consumption, which not only reduces labor intensity, but also reduces the cost of customers. In addition, spray drying products will not cause pollution if they are put too much. It can avoid accidents and ensure the safety of drinking water quality.
Spray drying polyaluminium chloride has the following characteristics:
(1) A large number of polynuclear hydroxyl complexes with positive charge and stable morphology can effectively promote flocculation and sizing.
(2) It has white appearance and low iron content, which can meet the needs of manufacturing high-quality paper.
(3) Polyaluminium chloride is the pre hydrolysate of aluminum chloride, the degree of hydrolysis is relatively low, and the decline of pH value of pulp is smaller than that of aluminum sulfate.
(4) When polyaluminium chloride is used as sizing agent, the retention and filtration aid of the slurry are obviously improved.
(5) In addition to the breaking strength, other indexes of paper performance are improved in varying degrees.
The spray drying process of polyaluminum chloride is through spray drying tower to dry liquid polyaluminium chloride in fog form, and then to produce non very fine powdery solid. The polyaluminium chloride produced by spray drying process has less impurities, less insoluble matter, and quick hydrolysis, and its color is usually yellow or golden yellow. At present, drinking water grade polyaluminium chloride and food grade polyaluminium chloride are produced by spray drying process. The spray drying process is more complicated than that of the drum drying process, and the price is higher than that of the drum type polyaluminium chloride.