Red mud is an alkaline solid waste inevitably produced in the process of alumina production (a step in refining metallic aluminum). According to statistics, every 1.0 ton of alumina produced generates 1.0 ~ 2.0 tons of dry red mud. By the end of 2021, the stockpile of red mud in China has exceeded 1.5 billion tons, and with the development of the economy, it is rapidly growing at a rate of 120 million tons per year. Shandong Province, as the largest aluminum industry province in the country, has an alumina production capacity of over 30 million tons/year, a red mud stockpile of over 500 million tons, covering more than 35,000 acres, and an annual increase of over 45 million tons of red mud emissions, accounting for about 40% of the country's alumina production capacity, is the province with the largest scale of red mud production in the country. The red mud stockyards of 47 alumina enterprises nationwide (4 temporarily suspended production in 2020) have mostly approached the stockpile limit, and in the next few years, they will face the situation of nowhere to pile up red mud, which will have a great impact on the development of China's aluminum industry and strategic security. Due to the complex and variable physical and chemical properties of red mud, it is difficult to be recycled and can only be stockpiled on site (as shown in Fig. 1.1 Red Mud Stockyard), however, the harm caused by the large amount of red mud emissions and accumulation to the environment and safety is becoming increasingly serious. Therefore, it is urgent to effectively recycle and utilize red mud resources, which has also become a universally recognized global problem. Exploring large-scale red mud absorption technology has become the most core and urgent problem of red mud resource utilization.