Importance is carried out by this equation: 2Al2O3==4Al+3O2.
Anode: 2o2ˉ-4eˉ= O2↓
Cathode: Al3+ +3eˉ=Al
Aluminum electrolysis process flow chart
Aluminum electrolysis process:
Modern aluminum industry adopts cryolite-alumina molten salt electrolysis method. Molten cryolite is used as solvent, alumina as solute, carbon as anode and aluminum liquid as cathode. After introducing strong direct current, electrochemical reaction, namely electrolysis, is carried out at the two poles in the electrolytic cell at the temperature of 950-970℃. The anode products are mainly carbon dioxide and carbon monoxide, which contain a certain amount of harmful gases such as hydrogen fluoride and solid dust. In order to protect the environment and human health, it is necessary to purify the anode gas to remove harmful gases and dust, and then discharge them into the atmosphere. The cathode product is aluminum liquid, which is pumped out of the tank by vacuum bag, sent to the casting workshop, purified and clarified in the holding furnace, and cast into aluminum ingots or directly processed into wire blanks and profiles. The production process is as follows:
Aluminum fluoride carbon anode DC
↓ ↓ ↓ ↓
↓
Waste gas anode gas electrolytic cell.
↑ ↓ ↓
Aluminum liquid waste gas/gas purification
↓ ↓
Purification and clarification of recovered fluoride.
↓ ↓ ↓
Return to electrolyzer
Casting, rolling or casting
↓ ↓
Aluminum ingot wire rod blank or profile [edit this paragraph] The development of electrolytic aluminum industry began to produce electrolytic aluminum in June 1954+00, and it took nearly 40 years to 1992. The output of electrolytic aluminum in China only exceeded1960,000 tons. Even in the 1990s when aluminum was the priority, the output of electrolytic aluminum in China increased from 65,438+10.87 million tons in 1995 to 2.83 million tons in 2000, and it took five years, with an average annual growth rate of 1 1.2%.
From 2002 to 2007, the average annual growth rate of electrolytic aluminum production in China reached 29.7%, which surprised the world. The annual increase of electrolytic aluminum output exceeds 1 10,000 tons. At the same time, since the growth rate of global electrolytic aluminum production in 2007 has exceeded the growth rate of consumption by 2 percentage points, the annual supply has exceeded 400,000 tons. Similar to the global market, the domestic electrolytic aluminum market in 2007 was also oversupply, and it is estimated that the market surplus is about 300,000 tons. Since the beginning of this year, China's economic development has slowed down and its demand for aluminum has decreased. Since August, the aluminum inventory in the domestic market has been increasing, and now it has exceeded 400,000 tons. Due to the depression of the real estate industry, the sales of aluminum profiles, which account for about 35% of the total consumption, are blocked, and the automobile industry is also a major consumer of aluminum in recent years. However, due to the slowdown in growth, the demand for aluminum decreased, and the sales of aluminum wheels and their alloys decreased significantly.