China’S Electrodes Catch Up With International Standards

In recent years, with the progress of society and the development of science and technology, especially the convening of Copenhagen and Cancun climate conferences, the concepts of green energy and sustainable development have become increasingly popular. As a strategic emerging industry, the development of new materials and new energy will become a new economic growth point in the future, which will inevitably bring about the rapid development of silicon industry and photovoltaic industry.
First, the rapidly developing silicon industry in China

According to the statistics of Silicon Branch of China Nonferrous Metals Industry Association, China’s industrial silicon production capacity has increased from 1.7 million tons/year in 2006 to 2.75 million tons/year in 2010, and the output has increased from 800,000 tons to 1.15 million tons in the same period, with average annual growth rates of 12.8% and 9.5% respectively. Especially after the financial crisis, with a large number of silicone and polysilicon projects put into production and the rise of the automobile industry, the domestic industrial silicon market demand increased greatly, which further stimulated the enthusiasm of private investment in industrial silicon industry, and its production capacity showed a rapid growth trend in the short term.

By the end of 2010, the industrial silicon production capacity under construction in major areas in China has reached 1.24 million tons/year, and it is estimated that the newly built industrial silicon production capacity in China is expected to reach about 2-2.5 million tons/year between 2011 and 2015.

At the same time, the state actively promotes the large-scale and large-scale industrial silicon electric furnaces. According to the industrial policy, a large number of 6300KVA small electric furnaces will be completely eliminated before 2014. It is estimated that the production capacity of small industrial silicon furnaces in China will be eliminated by 1-1.2 million tons every year before 2015. At the same time, at present, the newly-built projects realize industrial scale and large-scale equipment by virtue of advanced technological advantages, quickly seize the market through their own advantages in resources or logistics, and accelerate the elimination of backward production capacity.

Therefore, it is estimated that China’s metal silicon production capacity will reach 4 million tons/year in 2015, and the industrial silicon output will reach 1.6 million tons in the same period.

From the perspective of global silicon industry development, the metal silicon industry in western developed countries will gradually shift to developing countries in the future, and the output will enter a low-speed growth stage, but the demand will still maintain a steady growth trend, especially from the demand for silicone and polysilicon industries. Therefore, western countries are bound to increase the import of metal silicon. From the perspective of global supply and demand balance, in 2015, the gap between supply and demand of metallic silicon in developed countries such as the United States, Western Europe, Japan and South Korea will reach 900,000 tons, while China will export 750,000 tons to meet its demand, while other developing countries will supply the rest. Of course, in the future, the Chinese government is bound to further strengthen the qualification management of enterprises, and may further increase export tariffs, which will create favorable conditions for large enterprises to export metal silicon.

At the same time, in the process of the rapid development of the national polysilicon industry, China’s polysilicon industry has basically realized the scale industrialization of polysilicon by introducing foreign advanced technology, combining digestion and absorption with independent innovation, and the production capacity and output have increased rapidly. With the support of national policies, domestic enterprises have basically mastered the key technologies of polysilicon production by relying on independent innovation and re-innovation of imported technologies, breaking the monopoly and blockade of polysilicon production technology in developed countries. According to the survey and relevant statistics, as of the end of 2010, there were 87 polysilicon projects built and under construction in China. Among the 41 enterprises that have been built, 3 are silane methods with a production capacity of 5,300 tons, 10 are physical methods with a production capacity of 12,200 tons, and 28 are improved Siemens methods with a production capacity of 70,210 tons. The total scale of built projects is 87,710 tons; In the other 47 projects under construction, the production capacity of Siemens method was improved by 85,250 tons, silane method by 6,000 tons and physical metallurgy and other methods by 22,200 tons. The total scale of projects under construction is 113,550 tons.
Second, the demand and new requirements of carbon products in the development of silicon industry at present

China’s 12th Five-Year Plan puts forward new energy and new materials as strategic emerging industries. With the rapid development of new energy industry, customers’ demand for high-grade metal silicon is increasing, which requires metal silicon smelters to optimize raw materials and process to produce high-grade metal silicon with low harmful trace elements.

High-performance carbon materials are the industrial base for the development of silicon industry, and they coexist and prosper together. Because carbon material has good density, hardness and compressive strength, and has the advantages of high temperature resistance, high pressure resistance, corrosion resistance, good conductivity and stable performance, in the manufacturing process of silicon wafers, carbon material can be made into a heating container (composite graphite crucible) for silicon stone, and can be used as a thermal field for purifying polysilicon, drawing single crystal silicon rods and manufacturing polysilicon ingots. Due to the outstanding performance of carbon materials, there is no other material to replace it.

In the new development form, Hebei Hexi Carbon Co., Ltd. has realized the upgrading of product structure by persisting in independent innovation in order to continuously create value for customers and fulfill the promise of “providing new materials for new energy industry”, and its strategy focuses on new energy and new materials.

In 2020, the technicians of our company successfully developed φ1272mm graphite electrode and φ1320mm special carbon electrode for high purity silicon by optimizing combination, selecting formula and adjusting process for many times. The successful research and development of this product fills the gap of domestic large-size electrodes, reaches the international advanced level, and is recognized by customers. It is an ideal choice for customers to smelt high-purity metal silicon. In the next few years, with the further implementation of national energy conservation and environmental protection work, small silicon furnaces with high energy consumption will eventually be eliminated. The use of large-sized graphite electrodes and silicon-dedicated carbon electrodes will become a major trend in domestic metal silicon furnace smelting. This kind of electrode has three characteristics; (1) high density, low resistance and high mechanical strength; (2) Low thermal expansion rate and good thermal shock resistance; (3) Iron, aluminum, calcium, phosphorus, boron and titanium are low in trace elements, and high-grade metallic silicon can be smelted.

In order to meet customers’ needs and expectations, we rely on rich production experience and strong technical force, establish a perfect ISO9001 quality management system, implement “7S” management and “6σ” management methods, and provide customers with high-quality products under the guarantee of advanced equipment and quality management mode:
(1) Advanced equipment is the guarantee of quality ability: Our company has the high-efficiency kneading technology imported from Germany, which has unique process and effectively guarantees the paste quality, thus ensuring the forming quality of electrodes. In the molding process, the vacuum two-way hydraulic vibration molding machine is adopted, and its unique frequency conversion and pressure vibration technology makes the product quality stable and the volume density uniformity of the electrode good through reasonable distribution of vibration time; For roasting, the matching of combustion device and automatic control system is carried out on the ring roasting furnace. The CC2000FS system can preheat and bake the electrodes in the material boxes within the temperature and negative pressure range of each material box and fire channel in preheating zone and baking zone. The temperature difference between the upper and lower furnace chambers does not exceed 30℃, which ensures the uniform resistivity of each part of the electrode; On the machining side, the numerical control boring and milling technology is adopted, which has high machining precision and the accumulated tolerance of pitch is less than 0.02mm, so the connection resistance is low and the current can pass evenly.
(2) Advanced quality management mode: our company’s quality control engineers control all links according to 32 quality control and stop points; Control and manage the quality records, provide evidence that the product quality meets the specified requirements and the quality system runs effectively, and provide the original basis for realizing traceability and taking corrective or preventive measures; Implement a product number system, and the whole inspection process has quality records, such as raw material inspection records, process inspection records, product inspection records, product inspection reports, etc., to ensure the traceability of the whole production process of products.
In the future development, we will always adhere to the policy of “relying on science and technology and management, continuously developing and meeting user needs and increasing enterprise competitiveness”, and adhere to the enterprise purpose of “reputation first and creating value for customers”. Under the leadership of trade associations and with the strong support of peers and customers, we will continue to carry out technological innovation and develop new products to meet customer needs and create greater value for customers.

Post time: Jan-25-2021