The production of primary aluminium generally goes through three stages: bauxite mining, alumina preparation, electrolytic aluminium and aluminium ingot casting. The output of primary aluminium is huge because of its wide application. With the economic development of our country, the production of primary aluminium increased from 5.55 million tons in 2003 to 22.26 million tons in 2013. Although compared with 10 years ago, the energy consumption of raw aluminium production in China has decreased by about 16%, and the greenhouse gas emissions have decreased by about 21%. Significant achievements have been made in environmental protection. But in order to meet the needs of its rapid development, there are always some things contrary to the concept of green development.

Aluminum production environment has obvious footprint

Aluminum production is an energy-intensive industry, and its electricity consumption accounts for more than 5% of the national electricity consumption. At the same time, a large number of air pollutants (such as fluoride, sulfur dioxide, nitrogen oxides and polycyclic aromatic hydrocarbons (PAH) etc.) will be produced in the process of aluminium manufacturing, which will seriously damage the environment and human health in the vicinity. Professor Hong Jinglan, School of Environmental Science and Engineering, Shandong University, put forward in his report "Environmental Footprint Study on the Production of Recycled Aluminum by Electrolytic Aluminum in China". The production of primary Aluminum brings more burden to the environment than that of alumina and reclaimed Aluminum. The production of primary aluminium produces 15800 kg of greenhouse gas carbon dioxide, which is 21 times as much as the combined production of alumina and recycled aluminium.

If we use modern means to destroy the environment, the consequences are very serious. Shandong and Henan provinces are the largest producers of alumina, accounting for 59.28% of the total output. These two areas are also the intensive distribution areas of electrolytic aluminium industry. Aluminum production will produce toxicity to freshwater. According to the investigation, aluminum production will have an impact on freshwater ecology. It was found that Henan, Shandong and Xinjiang had the greatest potential environmental impact on freshwater ecology. A bauxite mining site of Dongchenzhuang Formation in Peiling Village, Beiye Town, Xin'an County, Henan Province, is mined without backfilling and plowing. It is surrounded by deep ditches and trenches, causing serious ecological damage. There are large open-pit yards and slag and soil materials. No environmental protection measures have been taken to pollute the environment.

For Shandong Province, last year, Liaocheng Environmental Protection Bureau found that the daily average carbon dioxide emission concentration of No. 1-3 boiler of Sinfa Huayuan Aluminum Industry Co., Ltd. was 607 mg/m3, 475 mg/m3, 401 mg/m3, 501 mg/m3, 326 mg/m3 and 554 mg/m3, respectively; on April 26, 2016, the daily average sulfur dioxide emission concentration of No. 4-5 boiler of the enterprise was 245 mg/m3, which exceeded the air pollutant emission standard of Shandong Thermal Power Plant. 》 The prescribed sulfur dioxide is 200 mg/m3. The EPA has asked the company to make a decision on a fine of 1 million yuan. In 2015, Xinfa Aluminum Power Company in Guangxi was also punished by the Ministry of Environmental Protection for illegal discharge of wastewater. Enter the names of several major aluminum enterprises in Shandong Province on the blue map, and it is not difficult to see their past pollution emission violations from the regulatory records.

Red mud, as the main solid waste of aluminium production, has accumulated 610 million tons of red mud in Shandong, Shanxi and Henan provinces alone in 2016. A large amount of red mud eventually becomes a landfill, causing serious environmental impact and burden. Comprehensive utilization of red mud has become an urgent problem in aluminium smelting industry. Red mud is a polluting waste residue discharged from alumina extraction in the aluminium industry. Generally, it produces 1 ton of alumina per ton on average and 1.0-2.0 tons of red mud incidentally. Because red mud contains a large number of strong alkaline chemicals, such as fluoride, sodium and aluminium, its pH value is still 11.25-11.50 after 10 times dilution (the original soil is more than 12). The extremely high pH value determines that red mud has strong corrosiveness to biological, metal and siliceous materials. High alkalinity sewage infiltrates into underground or surface water, which increases the pH value of water body. At the same time, the high or low pH value often affects the toxicity of compounds in water, so it will cause more serious water pollution. It is generally believed that the alkali content of 30-400 mg/L is the suitable range for public water sources, and the alkalinity of red mud adsorbent is as high as 26348 mg/L. The pollution of red mud adsorbent with such high alkalinity into water body is self-evident.

As the world's largest alumina producer, China emits tens of millions of tons of red mud every year. In 2014, Dongfang hoped that the red mud pond of Sanmenxia Aluminum Industry Co., Ltd., which is several kilometers long, would affect the nearby villages because of the lack of relevant coverage measures, resulting in the relocation of the whole village. The company's red mud depot suffered an accidental landslide in 2016 that killed two people. The best way to treat red mud is to develop comprehensive utilization, such as using red mud to produce building materials, soil amendments, and recovering metals from red mud.

Recycled aluminium is conducive to green development

Although aluminium production enterprises are also striving to develop the concept of green environmental protection production, according to the most commonly used international standardized environmental management and evaluation tool - Life Cycle Assessment (LCA), China's aluminium production enterprises are still one of the main "murderers" of environmental pollution. Its emissions of carbon dioxide, dust, sulfur dioxide and nitro compounds accounted for 3.53%, 1.99%, 3.47% and 5.34% of the total national air pollutant emissions, respectively. Its electricity consumption has accounted for 5% of the country's total electricity consumption and 83.0% of the non-ferrous metal industry. In addition, as astronomical figures of water consumption, raw aluminium production enterprises must have a wealth of energy strategy support. Huge energy consumption, if not handled properly, often means serious environmental pollution. But recycled aluminium seems to be able to change the image of high pollution and high energy consumption of aluminium production enterprises.

Recycled aluminium not only has 100% characteristics of primary aluminium, but also can save 95% energy of primary aluminium production. The data show that the output of recycled aluminium accounts for 99.43% of total primary aluminium in Japan, 89.53% in Italy, 62.35% in the United States and 60.74% in Germany, while only 19.24% in China. It is estimated that every 10% increase in the production of recycled aluminium in China can reduce the pollution source by 11.2%.

Aluminum production enterprises take the road of green development, and the utilization of recycled aluminium is one of the inevitable choices. Since 2001, China's aluminium production has ranked first in the world for 16 consecutive years, with a cumulative production of 230 million tons. There is no doubt that the growth rate of scrap aluminium has always been far ahead of China. China is a major producer and consumer of aluminium products, and the scrap aluminium resources are growing at an annual rate of more than 20%. With the approaching of the scrap period of a large number of aluminium products, the huge scrap aluminium resources are waiting for recycling, which provides a rich basis for the rapid development of recycled aluminium in China. In addition, when approving the construction of aluminium production enterprises, more innovative factors should be considered, such as replacing traditional thermal power generation with clean energy such as hydroelectric power generation and bioelectric power generation; applying advanced technology and technology to reduce waste emissions; and adding traffic logistics to change the current capacity, energy consumption and energy consumption of aluminium production enterprises in China. Low efficiency, heavy metal loss, serious environmental pollution and other problems hinder the green development.

It is believed that the future environmental footprint of the aluminium industry will be gradually reduced with the development of recycled aluminium, efficient production, strict control of pollution emissions and elimination of backward production capacity. It will be replaced by the development mode with the coexistence of human and nature as the value orientation and the green low carbon cycle as the main principle.