Red Mud,The ECOLOGICAL DEBT behind the world's largest producer of alumina
As the world's largest producer of alumina, China's output of alumina has been increasing year by year. According to data from the National Bureau of Statistics, China's alumina output reached 85.522 million tons in 2024, up 3.9% year-on-year, accounting for as much as 60% of the global total. According to information from Alarid, among the world's top ten alumina producers, the combined output of five Chinese enterprise groups, including China Aluminium Corporation and China Hongqiao Group, reached 61.82 million tons, accounting for a staggering 63.77%.
Underneath this impressive record sheet, however, lies a rather serious "ecological debt": red mud. In 2024, with an output of 85.524 million tons of alumina in China, the red mud discharge reached 101.8 million tons, while the utilization was only 13.8 million tons, with a utilization rate of merely 12%.
According to statistics, the cumulative amount of red mud globally currently stands at approximately 4 billion tons, with an annual production of about 1.8-200 million tons. The cumulative amount of red mud in China is approximately 1.5 billion tons, with an annual production of about 100 million to 105 million tons. Before 2023, the utilization rate of red mud has been consistently below 10%. Even though it has now increased to 12%, the amount of red mud being digested is still far lower than the amount being discharged. This means that the accumulation of red mud is still showing a trend of rapid increase.
What is red mud?
Bauxite is a by-product during the process of extracting alumina from bauxite ore. It gets its red-brown color due to its high content of hematite, hence the name.
Around 1888, Austrian chemist Carl Josef Bayer developed a method for producing alumina from bauxite. First, the bauxite was mixed with NaOH solution and heated. The aluminum oxide contained in the bauxite could be dissolved in the NaOH solution to form sodium aluminate. After filtering out the precipitate, adding Al(OH)3 seed crystals to the sodium aluminate solution would cause Al(OH)3 to re-precipitate, while the remaining mother liquor mainly containing NaOH would be reused for processing the next batch of bauxite; the obtained Al(OH)3 could be converted into Al2O3 through calcination.This method is called the Bayer process. Currently, more than 90% of the factories worldwide still use the Bayer process to produce Al2O3, and the precipitated substances filtered out are called red mud. Depending on the different production processes, in addition to Bayer red mud, there are also sintering red mud, and Bayer-sintering combined red mud.
Why insist on eliminating or "transforming" red mud?
(1) Reducing red mud pollution and protecting the environment
Red mud, as a highly alkaline solid waste, contains substances such as NaOH, Al(OH)3, and Fe(OH)3. When left to accumulate in open areas for a long time, the alkaline liquid within it will pollute the soil, damage the soil structure, and make it difficult for vegetation to grow; with the help of rainwater, the alkaline liquid will also enter the groundwater system, affecting the safety of drinking water sources.
Furthermore, the fine particles of red mud are prone to cause dust pollution during strong wind conditions, posing a threat to the atmospheric environment and the health of surrounding residents. The red mud also contains heavy metal elements such as chromium, lead, and cadmium. During the storage process, these heavy metals will enter the water bodies and soil through leaching, disrupting the ecological balance. The soil and water bodies near the red mud storage sites often have excessive levels of heavy metals, which have adverse effects on crop growth and the diversity of flora and fauna. Therefore, developing new technologies for the comprehensive utilization of red mud and reducing the amount of red mud storage are important measures for building a resource-conserving and environment-friendly society, and are of great significance for protecting the regional ecological environment.
(2) Transform waste into resources and achieve circular economy
Although red mud is an industrial solid waste, it is also an important resource. To solve the problem of red mud, it is necessary to fully recognize its resource attributes. From the composition perspective, the main elements of red mud are iron, aluminum and silicon, all of which have high utilization value; red mud also contains rare elements such as gallium and scandium, which are all highly valuable resources. From the perspective of comprehensive utilization products, selected iron products, building materials, road engineering materials, powder materials, ecological restoration materials, etc., are all key directions for the comprehensive utilization of red mud. Therefore, only by fully recognizing the resource attributes of red mud can we promote the comprehensive utilization of red mud from a more scientific perspective, achieve the full utilization of resources, and promote the sustainable development of the alumina industry. This is an important measure for building a resource-conserving and environment-friendly society, and is of great significance for protecting the regional ecological environment.
(3) Expand the aluminum ore industry chain and increase economic added value
At present, most of the aluminum ore industries in China adopt the direct exploitation mode of "mining - alumina production - electrolytic aluminum smelting", and the red mud produced from the beneficiation of aluminum ore has not yet achieved large-scale resource utilization. The entire industrial chain is relatively simple. With the reduction of high-quality aluminum ore resources, the guarantee of raw materials for the aluminum industry is facing severe challenges. Developing new technologies for the comprehensive utilization of red mud not only can convert waste materials into renewable resources to ensure the supply of industry raw materials, but also can expand to fields such as building materials, chemicals, metallurgy, and agriculture, achieving the cascade utilization of aluminum ore resources.
Taking the production of cement from red mud as an example, raw materials can be obtained locally near existing mines and alumina plants, and an "aluminum ore - alumina - cement" integrated industrial park can be built to achieve local conversion and value-added of resources. Extracting rare precious metals such as iron, aluminum, and titanium from red mud can further expand the development space and increase the added value of aluminum resources. Especially in the context of the gradual depletion of aluminum ore resources, systematically developing the utilization technology of red mud resourceization from the perspective of the industrial chain is of great significance for extending the industrial chain, optimizing the development mode of the aluminum industry, and promoting the transformation and upgrading of regional economy. It has high utilization value; red mud also contains rare elements such as gallium and scandium, which are all valuable resources. From the perspective of comprehensive utilization products, selected iron products, building materials, road engineering materials, powder materials, ecological restoration materials, etc., are all key directions for the comprehensive utilization of red mud. Therefore, only by fully recognizing the resource attributes of red mud can the comprehensive utilization work of red mud be promoted from a more scientific perspective, achieving the full utilization of resources and promoting the sustainable development of the alumina industry. It is an important measure for building a resource-conserving and environment-friendly society, and is of great significance for protecting the regional ecological environment.
With the vigorous development of the alumina industry, the comprehensive management and resource utilization of red mud have become a focus of the industry. On December 31, 2024, the Ministry of Industry and Information Technology and six other departments jointly released the "Action Plan for the Comprehensive Utilization of Red Mud", clearly setting the phased goals of "increasing the utilization rate of red mud by 15% in 2027 and reaching 25% by 2030".
With the utilization rate of red mud in China rising to 12%, we have taken a solid step in the field of red mud resource utilization. However, it is necessary to face the fact that the current consumption of red mud in China is far lower than its emissions, the accumulation of red mud is still showing a sharp increase trend, the resource utilization technology is not yet mature, the "bad debt" problem of red mud we are facing is still severe, and the so-called spring for the development of red mud comprehensive utilization has not yet arrived.
