Recently, Professor Liu Wanyi from the School of Chemistry and Chemical Engineering at Ningxia University shared insights during a meeting with representatives from over 60 ferroalloy production enterprises in the region. He highlighted that the annual production capacity of ferroalloys in the province is around 1.2 million tons, generating approximately 30,000 tons of silica fume annually. If the silicon dioxide content in this fine powder exceeds 92%, and impurities are removed, it could be sold domestically at a price of up to 2,000 yuan per ton, resulting in an annual revenue of about 60 million yuan. Further purification could even allow for export to international markets, where prices are significantly higher.
Professor Liu expressed regret that some companies still treated the silica fume as waste. Later, he learned that it wasn’t a lack of interest in recovery, but rather the technical and economic challenges that made it difficult. The ferroalloy industry is well aware that the dust emitted from submerged arc furnaces—used in producing ferrosilicon and industrial silicon—can cause severe atmospheric pollution. These fine particles are also linked to high rates of lung cancer. However, this dust is not without value. If properly recycled, it can be turned into a high-value material known as "silica fume," which is considered a "magic material" abroad. This process offers both environmental and economic benefits.
However, in practice, many companies struggle. For example, Lan Lanjun, an engineer at Ningxia Rongsheng Ferroalloy Group, explained that while pure silicon powder costs about 500 yuan per ton, the operating cost of a recovery system is as high as 700 yuan per ton. This makes recycling economically unviable. In 2003, the company invested 32 million yuan to install a dust recovery system, which could recover 5,000 tons of silica fume annually. But due to low purity (between 85% and 90%), the investment has yet to be recouped after three years.
Some companies have even stopped using their recovery systems altogether, only turning them on during inspections or at night to avoid scrutiny. This not only leads to significant loss of valuable material but also causes environmental damage. Kong Lingbin from the Ningxia Hui Autonomous Region Environmental Monitoring Brigade pointed out that such practices are common and harmful.
According to an industry insider, more than 20 of the 60 ferroalloy companies in the region have stopped recovering silica fume entirely, while the rest barely manage to operate. Only Helanshan Ferroalloy Co., Ltd. has maintained a better recovery rate.
Additionally, limited market demand for silica fume within China has further discouraged recycling efforts. Rong Shengjun from Rongsheng Group noted that the building materials industry in China lacks awareness of the material’s potential. Most companies don’t understand its applications and use it very little. In contrast, in developed countries like Japan and the U.S., construction products often require silica fume to enhance flexibility and durability, creating a much larger market. However, due to the difficulty in scaling production, most Ningxia-based companies find it hard to export their product directly. As a result, they often sell their silica fume at low prices to Norway’s Elkem Group, which then distributes it globally.
Professor Liu concluded his lecture by emphasizing that Shizuishan City, a major hub for silicon resources in China, holds vast potential for silica fume recycling. To unlock this potential, the government must not simply impose strict regulations on companies but instead support them in finding sustainable solutions. This includes promoting the application of silica fume in various industries, expanding its market, and ultimately encouraging greater enthusiasm among ferroalloy companies to recycle this valuable resource.
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