Method for recycling fluoride in the process of preparing silicon-containing compounds
A silicon compound and fluoride technology, applied in the direction of halide silicon compound, silicon oxide, silicon dioxide, etc., can solve the problem that fluoride cannot be recycled.
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Embodiment 1
[0057] Embodiment 1: Preparation of high-purity SiF 4 CaF 2 recycling
[0058] Will contain SiO 2 waste with CaF 2 Mix well to get a mixture, SiO 2 with CaF 2 The particle size is below 3mm, the CaF in the resulting mixture 2 The mass percentage is 80%. Calcinate the mixture at a temperature of 900-1100°C for 1 hour to generate CaO and SiF 4 , SiF 4 It is gaseous at high temperature and escapes from solid reactants. SiF that will escape 4 Introduce into another reactor and hydrolyze at a temperature of 810-1000°C to form SiO 2 and HF gas. Introduce the HF gas produced by hydrolysis into the reactor, and react with the reaction product CaO at 300-600°C for 2.5 hours to obtain CaF again 2 , thus realizing CaF 2 of reuse. The reaction equation is as follows:
[0059] SiO 2 +2CaF 2 →2CaO+SiF 4 (4)
[0060] SiF 4 +2H 2 O→SiO 2 +4HF (5)
[0061] CaO+2HF→CaF 2 +H 2 O (6)
Embodiment 2
[0062] Embodiment 2: Preparation of high-purity SiF 4 Process AlF 3 recycling
[0063] Bauxite ((Al 2 o 3 ) m (TiO 2 ) nSiO 2 ) with AlF 3 Mix well to get a mixture, bauxite and AlF 3 The particle size is below 5mm, and the AlF in the resulting mixture 3 The mass percentage is 60%. Calcinate the mixture at a temperature of 1100-1350°C for 3 hours to generate Al 2 o 3 、H 2 O and SiF 4 . SiF 4 Escape from solid reactant. SiF that will escape 4 Introduce into another reactor and hydrolyze at a temperature above 1000-1200°C to form SiO 2 and HF gas. The HF gas produced by hydrolysis is introduced into the reactor, and the reaction product Al 2 o 3 After reacting at 100°C for 5 hours, AlF was recovered 3 , thus achieving AlF 3 of reuse. The reaction equation is as follows:
[0064] 3SiO 2 +4AlF 3 ·3H 2 O→2Al 2 o 3 +3SiF 4 +12H 2 O (7)
[0065] SiF 4 +2H 2 O→SiO 2 +4HF (8)
[0066] al 2 o 3 +6HF→2AlF 3 +3H 2 O (9)
Embodiment 3
[0067] Embodiment 3: Preparation of nano-SiO 2 NH in process 4 HF 2 efficient use of
[0068] SiO 2 Coarse particles and NH 4 HF 2 Mix well, SiO 2 with NH 4 HF 2 The particle size is below 7mm, and the NH in the resulting mixture 4 HF 2 The mass percentage is 40%. Calcinate the mixture at a temperature of 600-700°C for 5 hours to generate NH 3 、H 2 O and SiF 4 , SiF 4 escaped from the solid. SiF that will escape 4 Introduce into another reactor and hydrolyze at a temperature of 1200-1300°C to form SiO 2 and HF gas. The HF gas produced by hydrolysis is introduced into the reactor, and the reaction product NH 3 and H 2 O was reacted at 150°C for 4.5 hours to regain NH 4 HF 2 , thus achieving NH 4 HF 2 of reuse. The reaction equation is as follows:
[0069] SiO 2 +2NH 4 HF 2 →SiF 4 +2NH 3 +2H 2 O (10)
[0070] SiF 4 +2H 2 O→SiO 2 +4HF (11)
[0071] NH 3 ·H 2 O+2HF→NH 4 HF 2 +H 2 O (12)
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