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A: Usually the metal elements are divided into two major categories, black and colored. Except that iron, manganese, and chromium are ferrous metals, the others are all non-ferrous metals, and aluminum belongs to non-ferrous metals and the like.
?? 2, non-ferrous metals according to some of its characteristics can be divided into several categories?
A: Non-ferrous metals can be classified into heavy metals, light metals, precious metals, rare metals, and semi-metals according to certain characteristics. Aluminum is a kind of metal of colored light metals.
3, what are the properties and uses of aluminum?
A: Nature: Aluminum is a light metal with a silver-white metallic luster and is known in the industry as a multifunctional metal. The specific gravity of aluminum is 2.7/cm3 and the melting point is 660°C. Aluminum has good electrical conductivity, thermal conductivity, and corrosion resistance. It also has good ductility and plasticity, while aluminum alloys have high mechanical strength.
Uses: Due to the light weight of aluminum and the high strength of aluminum and its alloys, aluminum can be used as light structural materials and construction industrial materials, such as aircraft, ships, and profiles, as well as electrical, thermal and corrosion-resistant materials, and food packaging. Materials and so on.
??4, the history of aluminum can be divided into two stages?
A: The chemical method of aluminum and electrolytic aluminum are two stages.
5, what is electrolysis of aluminum?
A: Electrolytic aluminum is cryolite-aluminum molten salt electrolysis. It uses cryolite as a solvent, alumina as a smelting substance, and powerful DC electricity into the electrolysis cell, and electrochemically acts on the cathode and the anode. reaction. Electrolysis products, the cathode is aluminum liquid, the anode is CO2 and CO gas (carbon as the anode), this method is electrolytic aluminum.
What is the raw material for aluminum electrolysis?
A: The raw materials for aluminum electrolysis are roughly divided into three categories: raw materials - alumina; flux - fluoride salts (including cryolite, aluminum fluoride, sodium fluoride, magnesium fluoride, calcium fluoride, lithium fluoride Etc.); anode material - pre-baked carbon blocks (pre-baked cells).
7. What is the purpose of aluminum electrolysis in direct current?
Answer: The direct current is fed to the electrolytic cell. On the one hand, it uses its thermal energy to melt the cryolite into a molten state and maintain a certain electrolytic temperature. On the other hand, the main purpose is to achieve electrochemical reactions at the two electrodes. Aluminum ions in the electrolyte get electrons from the cathode to be precipitated to obtain aluminum, and oxygen ions are discharged on the anode to produce a mixed gas of CO2 and CO with carbon.
?? 8, aluminum oxide impurities in the production of what harm?
A: The aluminum tulo solution produces relatively high purity requirements for alumina, generally industrial alumina, with a purity of more than 98%, usually containing small amounts of silica, ferric oxide, sodium oxide, calcium oxide, and moisture. These impurities have an adverse effect on aluminum electrolysis. The oxide impurities such as silicon oxide, iron oxide, and titanium dioxide, whose elements have a potential higher than that of aluminum, are reduced by aluminum during the electrolysis process. The reduced Si and Fe enter into the aluminum, thereby lowering the grade of aluminum and those potentials. Oxide impurities of elements that are negative to aluminum, such as Na20 and CaO, decompose cryolite, alter the electrolyte composition and increase the consumption of fluoride salts. Moisture decomposes cryolite and increases the hydrogen content in the liquid. If the water is too much, it will cause electrolyte explosion and endanger the safety of workers. P205 and SO2 will reduce the current efficiency. Therefore, the aluminum industry puts strict requirements on the purity of alumina.
9. What are the requirements of industrial aluminum electrolysis on the physical properties of the A1203?
A: The physical properties of industrial alumina are very important for ensuring the normal electrolysis process and improving the efficiency of gas purification. It is generally required to have less water absorption, can be dissolved more quickly in molten cryolite, less flying loss during processing, and can better seal the carbon anode, prevent it from oxidizing in the air, and has good heat insulation performance. For gas purification it is also required to have good activity and a sufficient specific surface area to be able to efficiently absorb HF gas. These physical properties depend on the crystal form, particle size and shape of the alumina crystals.
10, according to Al2O3, the physical properties of the alumina can be divided into three types of shapes, which type of better production
A: According to the physical properties of alumina, alumina can be divided into sand, medium and powder type. Sand alumina is better for production.
What is the role of cryolite flux?
A: The cryolite is used as a flux for electrolytic aluminum; its role is that it can dissolve aluminum oxide well before it is dissolved, and the formed melt can be electrolyzed below the melting point of pure cryolite and has good fluidity; Second, at the electrolysis temperature, the density of the cryolite-alumina melt is 10% less than that of the aluminum liquid. Therefore, the electrolytically produced aluminum liquid can be deposited on the cathode below the electrolytic solution, which can reduce the loss of oxidation of the aluminum. The structure of the aluminum electrolytic cell is simplified. Third, the cryolite has good conductivity. Fourth, the cryolite does not contain metal impurities whose electrical potential sequence is more positive than aluminum, and can guarantee the quality of product aluminum. Currently, cryolite is still An ideal flux in aluminum electrolysis production.
12. Why use carbon anode for aluminum electrolysis?
Answer: In the process of aluminum electrolysis, the highly erosive cryolite melt directly contacts the electrode. As conductive yin and yang both pole materials, not only good conductivity, but also high temperature resistance, corrosion resistance, and at the same time low price only carbon materials. Therefore, the aluminum industry uses carbon materials for the two poles.
13. How does the series current flow through the electrolytic cell?
A: The electrolytic cells in the series are all connected in series, and the direct current is sent from the positive electrode of the rectification through the aluminum bus to the anode of the electrolysis cell in the foreground, and then to the cathode through the electrolyte and the aluminum liquid layer, and then through the large bus. The anodes of the two electrolyzers, and so on, analogously, the current from the cathode of the latter electrolyzer is then returned to the cathode of the rectifier via the large busbar, making the entire series a closed series circuit.
Aluminum electrolytic production overview
1. Which of the two major categories of metal elements are common and which of the following is aluminum?