Introduction to aluminum

1. Natural attribute

Aluminum is a light metal, and its compounds are widely distributed in nature. The content of aluminum in the earth’s crust is about 8% (by weight), second only to oxygen and silicon. In the metal varieties, it is the second largest category of metal, second only to steel. Aluminum is one of the most commonly used industrial metals due to its special chemical and physical properties. It is not only light in weight and hard in texture, but also has good ductility, conductivity, thermal conductivity, heat resistance and nuclear radiation resistance. It is an important basic raw material for the development of national economy.

The specific gravity of aluminum is 2.7, and its density is about 1 / 3 of that of common metals. The conductivity of aluminum conductor is about 61% of copper and half of silver. Although pure aluminum is extremely soft and ductile, it can be hardened by cold working and making alloys. Bauxite is an important source of aluminum. It takes about two pounds of bauxite to make a pound of alumina, and two pounds of alumina to make a pound of metal aluminum.

2. Classification of aluminum varieties

According to the main component content of aluminum ingot, it can be divided into three categories: high-grade pure aluminum (the content of aluminum is 99.93% – 99.999%), the industrial high-purity aluminum (the content of aluminum is 99.85% – 99.90%), and the industrial pure aluminum (the content of aluminum is 98.0% – 99.7%).

3. Quality standard of aluminum

The quality of aluminum ingot must meet the national standard GB / 1196-1993. The aluminum content of al99.80 and al99.70 shall not be less than 99.80 and 99.70. According to the national standard (GB / t1196-93), it should be called “aluminum ingot for remelting”, but we are used to calling it “aluminum ingot”. It is produced by electrolysis of alumina cryolite. There are two types of aluminum ingots after they are used in industry: cast aluminum alloy and wrought aluminum alloy. Cast aluminum and aluminum alloy are the casting of aluminum produced by casting method; wrought aluminum and aluminum alloy are the processed products of aluminum produced by pressure processing method: plate, strip, foil, tube, bar, mold, wire and forging. According to the national standard of aluminum ingots for remelting, “aluminum ingots for remelting are divided into six grades according to the chemical composition, which are al99.85, al99.80, al99.70, al99.60, al99.50 and al99.00″ (Note: the number after al is the aluminum content). At present, some people call “A00″ aluminum, which contains 99.7% pure aluminum, is called “standard aluminum” in the London market. As we all know, in the 1950s, China’s technical standards were all from the former Soviet Union, “A00″ was the Russian brand in the national standards of the Soviet Union, “a” was the Russian letter, not the English “a” character, nor the “a” of the Chinese phonetic alphabet. In line with international standards, it is more accurate to call it “standard aluminum”. Standard aluminum is ingots containing 99.7% aluminum, which is registered in the London market.

4. Main uses of aluminum

In the past 50 years, aluminum has become one of the most widely used metals in the world. In the construction industry, due to the stability of aluminum in the air and the excellent appearance after anode treatment, aluminum alloy materials are widely used in aviation and defense military industry departments; aluminum cable reinforced by high-strength steel wire is commonly used in power transmission; in addition, a large amount of aluminum is required for automobile manufacturing, container transportation, daily necessities, household appliances, mechanical equipment, etc.

With the rapid development of the national economy, China has gradually become the “global processing base”. The basic industries such as steel and nonferrous metals are booming. In recent years, the output of electrolytic aluminum has increased sharply, making China the largest aluminum producer in the world.

At the same time, China is also playing an important role in the global aluminum market. Due to the strong growth momentum of China’s demand in recent years, the changes of China’s supply and demand fundamentals directly affect the balance of the world’s aluminum market through international trade.

However, there are many uncertain factors in the supply of raw aluminum in China. This uncertainty comes from the continuous tight supply of alumina, and partly due to the power shortage caused by the defects of China’s system. Due to the limitation of its own resources and the influence of insufficient investment in mining and primary mineral product development for a period of time, there has been a serious shortage of raw materials in China in recent years. A large amount of alumina needs to be purchased from abroad every year, and 5.87 million tons of alumina were imported in 2004.

In addition to the problems of raw alumina and electric energy, the government has begun to impose restrictive policies on the supply of raw aluminum, which is higher than the growth of domestic consumption, in order to control some of the overheated electrolytic aluminum industry. However, the overall impact of power shortage or alumina supply on China’s aluminum production is limited.

Post time: Sep-02-2020