HUANG Yongcheng (1994-), male, Master candidate. E-mail: 982634899@qq.com
Silica fume (SF, containing SiO2>85%, in mass fraction) collected from emitting soot of silicon-metallurgical workshop was used as a raw material for preparation of pure crystalline silicon. Silicon was prepared via refining pretreatment of pristine SF and ball-milling mixing to make magnesium and SF powder reactant, subsequent magnesiothermic reduction reaction (MRR) process and final purification by two-step acid-etching treatment of HCl-HF acids. The experimental results show that a core-shell structure Mg@SiO2, i.e., Mg particles coated uniformly by a dense layer of submicron-sized primary particles of silica fume in a desired stoichiometric ratio of reactants Mg:SiO2 of 0.85∶1.00, is formed via micron-scale diffusion reaction after mixing for 12 h at a rotational speed of 150 r/min. A high-performance route of MRR was proposed based on the wrapping-micron-reactor model. The extent of MRR is as high as 96% and Si species of HCl-etched sample are more than 90% (in mass fraction), and the final prepared product of crystalline silicon achieves a purity of 99.88% (in mass fraction) after HF+CH3COOH acid-etching.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |