Polyaluminum chloride (PAC) is a new type of water purification material and inorganic polymer coagulant, referred to as polyaluminium. It is a water-soluble inorganic polymer between AlCI3 and Al(OH)3. It has a high degree of electrical neutralisation and bridging effect on colloids and particles in water, and can strongly remove trace poisons and heavy metal ions with stable performance. Due to the bridging effect of hydroxide ions and polymerisation of multivalent anions, the polyaluminum chloride produced is a kind of inorganic polymer water treatment agent with larger molecular weight and higher charge.
Models of polyaluminum chloride (PAC)
According to the preparation method of polyaluminum chloride, it can be divided into three categories: drum polyaluminum chloride, plate and frame polyaluminum chloride and spray polyaluminum chloride.
1. Roller polyaluminum chloride
Appearance colour is yellow or light yellow, dark brown, dark grey resin solid. It is produced by roller drying technology, so it is called roller polyaluminum chloride (also called roller simple polyaluminium). Oxidation content is generally 24%-28%. Roller polyaluminum chloride is mainly used in smelting, chemical industry, printing and dyeing, papermaking, coal washing, steelmaking, oil field, oil refining, leather, radioactive wastewater, metal processing, coal, food, dyes and other wastewater treatment. Widely used in living water, ding industry water and pure water pretreatment.
2. plate and frame polyaluminum chloride
Appearance is golden yellow or light yellow granular. It is produced by plate and frame filtering technology, so it is called plate and frame polyaluminum chloride (also called plate and frame polyaluminium). It is one of the excellent products of water treatment chemicals. Its alumina content is between 28%-31%, which can remove bacteria, odour, nitrogen, aluminium, mind, oil, turbidity, heavy metal salts and radioactive pollutants. It is widely used in the purification of various water sources. At present, it is mainly used for the purification of domestic drinking water, industrial water, domestic sewage and industrial wastewater.
3. Spray polyaluminum chloride
Its alumina content of 28% -32%, the appearance of the colour can be divided into high-grade white, light yellow powder, spray-dried polyaluminum chloride production process: liquid raw materials filtering - spray tower spray drying - finished products. So it is called spray polyaluminum chloride (also known as spray polyaluminium). Spray polyaluminum chloride has the advantages of good stability, wide adaptability to water, fast hydrolysis, strong adsorption capacity, large alumina, dense precipitate, low oil dehydration and so on. In the same water quality conditions, spray PAC dosage is very small. Especially in the case of bad water quality, the dosage of spray polyaluminum chloride is reduced by half compared with roll simple polyaluminum chloride.
According to the use of polyaluminum chloride, it can be divided into drinking water grade polyaluminum chloride and industrial grade polyaluminum chloride.
1. Drinking water grade polyaluminum chloride
Drinking water grade polyaluminum chloride is generally required to have low aluminium content, fast flocculation speed, economic and practical characteristics. In the field of water supply treatment, plate and frame polyaluminium and spray polyaluminium are widely used because of their excellent flocculation effect and low aluminium content.
2. Industrial grade polyaluminum chloride
Industrial grade polymeric aluminium chloride requires good treatment effect, stable quality and low treatment cost. Roller polyaluminium, plate and frame polyaluminium and spray polyaluminium are all used in the field of wastewater treatment, but roller polyaluminium performs better in the treatment of high salinity wastewater.
Characteristics of each model:
Spray: Spray products have the advantages of good stability, wide adaptability to water area, high hydrolysis speed, strong adsorption capacity, large alumina formation, fast dense precipitation, low turbidity of effluent, good dewatering performance and so on.
Roller: roller products floc formation fast and coarse, high activity, fast precipitation, high turbidity water purification effect is particularly obvious, adapt to a wide range of PH value, reduce the PH value of the original water is small, and thus no corrosion of pipeline equipment, suitable for a wide range of PH value (5 ~ 9), and after treatment of the water PH value and alkalinity decline is small.
Plate and frame material: plate and frame refers to the production of liquid semi-finished products in the polyaluminum chloride through the filtering method, the impurities of water insoluble matter, etc., so as to improve the content of the product, in general, after the plate and frame of the polyaluminium content of not less than 28%, the appearance of the majority of the golden yellow.
To sum up, according to its preparation method and use, polyaluminum chloride can be divided into drum polyaluminum chloride, plate and frame polyaluminum chloride, spray polyaluminum chloride, industrial grade polyaluminum chloride and drinking water grade polyaluminum chloride. When using, you need to choose the appropriate polyaluminum chloride category according to the actual situation.