Know About The Preparation Methods of Poly Aluminium Chloride
Polymerized alumina is definitely an inorganic polymer flocculant that has been widely studied and applied in the field of water treatment in recent years. When removing turbidity and natural organic matter, PAC has the features of small alkalinity consumption, low treatment cost, little influence on temperature and less sludge production, therefore it is widely found in domestic drinking water, industrial water supply treatment, industrial wastewater and domestic sewage purification treatment. Additionally, it can be widely found in foundry, medicine, tanning, papermaking, etc. At present, there are many methods for producing polyalumina, and several popular synthetic methods are introduced here.
There are numerous ways to prepare polyaluminium chloride, which may be divided in to acid method, subtraction method, neutralization method, pyrolysis method, pressurized reaction method, mixed gel method, electrodialysis method, electrolysis method, etc. in line with the production process. Powder polyaluminum chloride for water treatment is obtained by spray drying or drum drying liquid polyaluminum chloride. Spray drying is an ideal drying method and is ideal for large-scale production. It can be feasible for small-scale production enterprises to use drum drying.
You can find two main types of raw materials for the production of polyaluminum chloride. One is aluminum-containing minerals, including bauxite (gibbsite, boehmite, diaspore), clay, kaolin, alunite, etc..The other category is other aluminum-containing raw materials, including metal aluminum, waste aluminum scraps, gray aluminum, aluminum hydroxide, aluminum trichloride, coal gangue, fly ash, etc. Only with aluminum ingots, aluminum chips, aluminum hydroxide as raw materials and aluminum sulfate, aluminum dichloride as raw materials can produce relatively pure aluminum oxide products.
Metal Aluminum method. The raw materials for the synthesis of polyaluminum chloride by metal aluminum method are mainly leftovers from aluminum processing, such as aluminum scrap, aluminum ash and aluminum slag. Slowly add hydrochloric acid to react with aluminum ash based on a specific proportion under stirring, and obtain liquid polyaluminum chloride through aging polymerization and sedimentation, and then dilute, filter, concentrate, and dry to acquire it. When it comes to technology, it could be divided in to three types: acid method, alkali method and neutralization method. The acid method mainly uses HCl, and the product quality is difficult to regulate; the alkali method suppliers have high process difficulty, large equipment investment and large amount of alkali consumption, pH value control costs raw materials, and high cost; the neutralization method is mostly used. So long as the ratio is well controlled, it could generally meet up with the standards of our country.
Aluminum hydroxide method. Aluminum hydroxide powder has high purity, and this content of toxic substances such as heavy metals such as synthetic polyaluminum chloride is low. Generally, the production procedure for heating, pressurizing and dissolving acid is adopted. The process is relatively simple, however the polyaluminum chloride produced has low alkalinity, so aluminum hydroxide is generally used to heat and pressurize the acid solution, and calcium aluminate powder is included with neutralize it.
Alumina method. The raw materials containing alumina mainly include gibbsite, bauxite, kaolin, coal gangue and so on. The production process may be divided in to two steps: the first step is to acquire crystalline aluminum chloride, and the 2nd step is to acquire polyaluminum chloride through pyrolysis or neutralization.
Aluminum chloride method. Probably the most commonly used method is always to process polyaluminum chloride with aluminum chloride powder as raw material. Boiling and pyrolyzing with crystalline aluminum chloride at 170°C, adding water to solidify and polymerize, and then solidified and dried.
Alkali solution method. The aluminum ash is reacted with sodium hydroxide to acquire a sodium aluminate solution, and then a pH value is adjusted with hydrochloric acid to prepare a polyaluminum chloride solution. The item prepared by the strategy has better color and less insoluble matter, but this content of sodium chloride is high, the consumption of raw materials is high, this content of aluminum oxide in the clear answer is low, and the industrial production cost is high.
