Silicon is an important material for outdoor solar-powered photovoltaic cells, and the requirements for industrial silicon are very high during production. Whether industrial silicon meets national standards will directly affect the quality and photoelectric conversion rate of solar photovoltaic cells. If you have other related questions, you can also contact the online customer service or leave a message.

     The silicon tetrachloride produced is used to manufacture solar photovoltaic cells, which requires high purity. Therefore, chemical silicon should be used, that is, grade A silicon and grade B silicon. It is better to use a grade A silicon to form tetrachloride in a fixed furnace. Silicon can be produced without using high-priced silicon powder as raw material, and directly using industrial silicon blocks. As a result, the cost of synthesis will be greatly reduced, but the particle size of the silicon block should be suitable to facilitate the full contact of chlorine gas. Increase the reaction rate.

     The particle size of silicon is too large, the specific surface area of silicon is small, the reaction area is small, and the reaction rate is slow; the particle size of silicon is too small, the specific surface area of silicon is large, and the gap between particles is small, so that Will increase the resistance of chlorine gas, and even hinder the passage of chlorine gas. Therefore, industrial silicon is required to have a suitable particle size. It is generally believed that the particle size of silicon is 30-50mm. The purity of silicon for chemical use is already very high, and it can be directly used to produce tetrachloroethylene. Silicon, however, in order to improve product purity, industrial silicon needs to be processed to achieve further purification.

     The most common treatment method is acid leaching in industrial silicon production. When silicon is solidified, most impurities (Fe, A, C, B, P, Cu, etc.) are separated around the particles. These impurities are silicide or silicon. Acid state. In addition to silicon carbide and iron oxide, most of these impurities can be dissolved with acid, while silicon is insoluble in acid.

     The above characteristics of silicon and impurities provide convenience for people to use industrial acid silicon by acid leaching method, and the effect is very good, the process equipment is simple, and the acid used for acid leaching method includes hydrochloric acid, sulfuric acid, aqua regia, hydrofluoric acid. And their different combinations are mixed with acid. The addition of ferric oxidizing agent to the acid can accelerate the dissolution of impurities and improve the acid leaching effect; increasing the temperature and using small-sized silicon powder are beneficial to improving the purity of silicon tetrachloride. Large-grained industrial silicon can also be purified by acid leaching, but the acid leaching time is extended.

     Generally for industrial silicic acid leaching, it is an acid solution with different components such as 10% hydrochloric acid, sulfuric acid, aqua regia, hydrofluoric acid, etc. The acid leaching time should be more than half a day, generally 12~18h, after industrial silicate soaking, wash with water. Industrial silicon should be washed to neutral. Use clean water when washing, and finally use pure water to prevent water from contaminating industrial silicon.

     The industrial silicon after washing must be dried in a drying oven (dryer), the drying temperature is about 150 °C, the general time is maintained for 2~8h (depending on the drying condition of industrial silicon), the industrial silicon after drying It should be loaded into the synthesis furnace immediately, not in the air, because the dry industrial silicon is very easy to absorb water. If a boiling furnace is used to prepare trichlorosilane, the industrial silicon powder should be used. Generally, the purity of the industrial silicon powder used for the preparation of trichlorosilane is 98% to 99%.

     Industrial silicon powder is too thick or too thin to be too good, too rough airflow can not blow up, it is not good for boiling: too thin will often block the pipeline. It is generally considered that the particle size is preferably from 80 to 120 mesh. The quality of industrial silicon powder is relatively high, so there is no need to choose, but it is necessary to pretreat free oxygen and its compounds, especially moisture, which is very harmful to the preparation of trichlorosilane. The principle is based on silicon-oxygen bonds (sO is more stable than silicon-chloride bonds (S-C), and trichlorosilane is easily oxidized and hydrolyzed, thereby reducing the yield. Therefore, the task of industrial silicon powder pretreatment is mainly pickling and drying.

     The pickling of the industrial silicon powder is the same as the pickling of the above industrial silicon block. It can be completely referred to the above industrial silicon block. The drying of the industrial silicon powder is also the same as the drying of the above industrial silicon block, and the drying of the above industrial silicon block can be completely referred to. The practice can also be done with a dryer.

     Whether industrial silicon is selected according to national standards and whether it is strictly handled will seriously affect the quality of outdoor solar lamps. Nuusolar uses A-grade silicon. It also selects silicon according to national standards and carefully handles it to provide customers with high-quality products in all aspects of quality and quality.

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