Application Of High Voltage Pulse Discharge Technology In Crushing Of Silicon Raw Materials

The traditional production technology and products of silicon materials in photovoltaic market are mainly rod-shaped polysilicon materials produced by Siemens method.Because of its large size,rod-shaped polysilicon materials cannot be directly applied to the growth of Czochralski single crystals,so they need to be broken to a certain size before they can be used.As a key link in the post-treatment process of polysilicon,the crushing of silicon raw materials has high requirements for the size distribution of crushed particles and the cleanliness of silicon materials.Under the background of the continuous increase of newly added photovoltaic installed capacity in the world and the significant increase of silicon material demand,coupled with the single crystal CCZ Technology(continuous crystal drawing technology)and RCZ re feeding technology(multiple loading crystal drawing technology)at the present stage The silicon material used has extremely strict requirements on particle size.Exploring more advanced crushing methods to reduce the crushing cost of silicon raw materials is the future development direction of silicon material crushing.Mechanical crushing is one of the traditional crushing methods of rod-shaped polysilicon.In this thesis,by introducing high-voltage pulse crushing technology,the experimental comparative study of rod-shaped polysilicon crushing is carried out.ICP-MS and bt-2900 dry method dynamic image particle size and shape analysis system are used to analyze the surface metal impurity content,particle size distribution,stacking angle Analysis of appearance and morphological characteristics;At the same time,the disadvantages and processing cost of the two crushing methods are compared.The research results show that the method of high-voltage pulse crushing silicon raw materials has high production capacity,controllable and adjustable particle size of crushed bulk polysilicon,low manual dependence,and can realize intelligent production.It has obvious advantages in crushing,which is more conducive to the industrialization promotion in the industrial production of rod polysilicon crushing.The proportion of 2-15 mm bulk polysilicon with two crushing methods is as follows: high voltage pulse crushing method accounts for 34.29% and mechanical crushing method accounts for 31.39%.In terms of appearance and morphological characteristics,the particles crushed by the two methods show needle flakes,but there are more long strip particles,more small particles and less spherical particles after mechanical crushing;After pulse crushing,there are fewer long strip particles,fewer small particles and more spherical like particles.Through the detection and analysis of the content of metal impurities on the surface,the pollution degree of block polysilicon by the two crushing methods is compared.It is found that the mechanical crushing is significantly higher than the high-voltage pulse crushing.In the process of mechanical crushing,the main pollution stages are crushing stage and screening stage.The stacking angle of bulk polysilicon materials with two crushing methods is tested.It is found that the average stacking angle of pulse crushing material is39.13°less than that of mechanical crushing material is 40.03°.The average stacking angle of high-pressure pulse crushing material is small and has the best fluidity,which is more conducive to the secondary feeding in the growth process of Czochralski single crystal.Through the cost analysis of the two crushing methods,it is found that the cost of mechanical crushing is 2.452 yuan / kg;The cost of pulse crushing is 2.349 yuan / kg,which is slightly lower than that of mechanical crushing.In addition,based on the principle analysis of high-voltage pulse crushing equipment,this thesis preliminarily explores and designs the charging power supply,energy storage capacitor,gas switch and so on.Through the comparative analysis of the two crushing methods and the further study of high voltage pulse discharge crushing technology,as a rod polysilicon crushing method with low cost,low pollution,high quality and high production capacity,high voltage pulse discharge crushing method has practical feasibility and economy in terms of technical advantages,economic indicators and cost control,Its application prospect in engineering field is broad and worth popularizing.This paper has 28 figures,13 tables and 67 references.