A method for treating solid waste residues from the production of silane products by the magnesium silicide process

Abstract

This invention belongs to the technical field of solid waste treatment, and particularly relates to a method for treating solid waste from the preparation of silane products using the magnesium silicide method. The method includes: S1, crushing the waste residue, adding water and stirring to dissolve it, separating to obtain filtrate A and precipitate B; S2, adding hydrochloric acid aqueous solution to filtrate A to adjust its pH value to <7, concentrating and crystallizing, and then separating the solid and liquid to obtain ammonium chloride solid C and filtrate D1; S3: adding hydrochloric acid aqueous solution to precipitate B and stirring, then separating the solid and liquid to obtain magnesium ion-containing filtrate D2 and silicon-containing solid E; S4: mixing filtrate D1 and filtrate D2 to form solution D; S5: adding ammonia water to solution D to adjust the pH value to >8, then separating the solid and liquid to obtain magnesium-containing precipitate F and filtrate G. This invention can effectively recover ammonium salts and magnesium ion-containing precipitates contained in the waste residue, and does not introduce other components during the treatment, nor does it increase the cost of additional treatment equipment.

Description

Technical Field

[0001] This invention belongs to the technical field of solid waste treatment, and particularly relates to a method for treating solid waste residue from the preparation of silane products using the magnesium silicide method. Background Technology

[0002] Silane-based electronic gases are widely used in the manufacturing processes of integrated circuits, solar cells, and flat panel displays. Currently, the main processes for preparing silanes include the chlorosilane disproportionation method and the magnesium-silicon process. The magnesium-silicon process uses ammonium chloride and magnesium silicide to react in liquid ammonia to produce silane-based electronic specialty gases. This process generates waste residue containing complex components such as ammonium chloride, ammonia, hexaammine magnesium chloride, silicon oxides, and magnesium oxides.

[0003] This waste residue releases ammonia gas at room temperature, causing pollution to the soil and air. Furthermore, magnesium ammonium resources have a wide range of uses, and the recycling value of this waste residue is very high. For example, ammonium chloride can be used as fertilizer and in the dye industry; magnesium hydroxide is an excellent flame retardant for plastics and rubber products, and can also be used in the electronics industry, pharmaceuticals, as insulation materials, and in the manufacture of other magnesium salt products.

[0004] Currently, existing technologies only address the treatment of single-component ammonia-containing magnesium chloride or other magnesium-containing waste residues through processes such as deammoniation and high-temperature calcination to recover magnesium compounds such as magnesium chloride and magnesium carbonate. For example, patent document CN104030326A discloses a method for preparing magnesium carbonate using hexaammine magnesium chloride, which recovers hexaammine magnesium chloride, a byproduct of polysilicon production using the silane method. Patent document CN110606610A discloses a method for recycling metal chloride wastewater using an ammonia method, achieving the recovery and utilization of chloride ions in the metal chloride wastewater. Patent document CN101983922A discloses a method for preparing anhydrous magnesium chloride by calcining and deammoniation of hexaammine magnesium chloride, using high-temperature ammonia gas generated by the process itself as a protective gas, while simultaneously providing the heat required for the drying process of hexaammine magnesium chloride, preventing the decomposition of hexaammine magnesium chloride during the low-temperature drying stage and leaving complexation vacancies, thus preventing the formation of chlorides by organic matter with magnesium chloride during the drying stage, resulting in a qualified anhydrous magnesium chloride product. Patent document CN109626396A discloses a method for treating ammonium chloride solid waste, which is not only complex in operation and requires high energy consumption, but also cannot be applied to the recycling and treatment of waste residue produced in the production of silane electronic specialty gases with complex and diverse components.

[0005] It is evident that the recycling and treatment of waste residues generated from the production of silane-based electronic specialty gases, which have complex and diverse compositions, cannot simply be based on processes designed for single-component waste residues. Existing publicly available technical solutions are all aimed at the harmless treatment of single components, and no effective solutions have been proposed for complex components. Furthermore, the presence of insoluble substances such as Si in the waste residues from the production of silane-based electronic specialty gases increases the difficulty of separating precipitates and insoluble substances during the treatment process, and the presence of ammonium ions can inhibit or affect the formation of magnesium ion precipitation.

[0006] Therefore, it is particularly important to develop a new method for the treatment and recycling of waste residue from the magnesium silicide process for preparing silane products. Summary of the Invention

[0007] The purpose of this invention is to address the high difficulty in the harmless treatment of multi-component waste residues (especially the harmless separation of soluble, insoluble, and difficult-to-dissolve substances) by providing a method for treating solid waste residues from the preparation of silane products using the magnesium silicide method. This method can effectively recover ammonium salts and magnesium ion precipitates contained in the waste residues, without introducing other components during the treatment process, and without adding extra treatment equipment and costs.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] A method for treating solid waste residue from the magnesium silicide process for preparing silane products includes the following steps:

[0010] S1. Crush and grind the solid waste residue to be treated into powder, then add water and stir to dissolve until the weight of the precipitate no longer decreases. Let it stand and perform solid-liquid separation to obtain filtrate A (containing ammonium ions, magnesium ions, and chloride ions) and precipitate B (containing silicon impurities and magnesium impurities).

[0011] S2. Add hydrochloric acid aqueous solution to the filtrate A to adjust its pH value to <7 (e.g., 4, 4.5, 5, 5.5, 6, 6.5), preferably pH value ≤5. Then, concentrate and crystallize until the concentration of ammonium ions in the solution is not less than 23 wt% of the solution mass and the concentration of magnesium ions is not greater than the concentration of ammonium ions, and then stop the concentration and crystallization. After solid-liquid separation, ammonium chloride solid C and filtrate D1 containing ammonium ions and magnesium ions are obtained.

[0012] S3: Add hydrochloric acid aqueous solution to the precipitate B and stir until the weight of the precipitate no longer decreases. After solid-liquid separation, obtain magnesium ion-containing filtrate D2 and silicon-containing solid E.

[0013] S4: Mix the filtrate D1 and the filtrate D2 to form solution D;

[0014] S5: Add ammonia to the solution D to adjust the pH value to >8 (e.g., 8.5, 9, 9.5, 10.5, 11), preferably 8-10, and then perform solid-liquid separation to obtain magnesium precipitate F and filtrate G containing ammonium ions and magnesium ions.

[0015] The production of silane products using the magnesium silicide process generates various types of byproducts, such as magnesium chloride and hexaammine magnesium chloride suspensions. These byproducts can be recycled and utilized as solid waste. According to the treatment method provided by this invention, in some embodiments, the solid waste to be treated includes insoluble components and soluble components, wherein:

[0016] The content of insoluble components accounts for less than 10 wt% of the total solid waste (e.g., 1 wt%, 3 wt%, 5 wt%, 8 wt%).

[0017] Based on the molar amount of ions in the soluble component, the molar ratio of ammonium ions to magnesium ions in the soluble component is 0.5:1 to 20:1 (e.g., 0.8:1, 1:1, 2:1, 4:1, 8:1, 10:1, 14:1, 18:1).

[0018] In some implementations, in step S1, the solid waste to be treated is ground into powder with a particle size of ≤2mm (e.g., 0.01mm, 0.1mm, 0.2mm, 0.5mm, 0.8mm, 1mm).

[0019] In some implementations, in step S1, the temperature for adding water and stirring to dissolve is 20-30°C (e.g., 25°C), the stirring time is 20-40 min (e.g., 30 min), and the standing time is 20-60 min (e.g., 30 min, 50 min).

[0020] In some embodiments, the filtrate A contains chloride ions as anions and ammonium ions and magnesium ions as cations; wherein, in terms of molar amounts of ions, the molar ratio of ammonium ions to magnesium ions is 0.5:1 to 80:1 (e.g., 1.0:1, 1.5:1, 4:1, 8:1, 10:1, 15:1, 20:1, 30:1, 40:1, 50:1, 60:1, 65:1, 70:1).

[0021] In some embodiments, the precipitate B comprises silicon, silicon oxide, magnesium oxide, magnesium hydroxide, magnesium carbonate, and mixtures thereof.

[0022] In some implementations, based on the total mass of the solution, the concentration of ammonium ions in the filtrate D1 of step S2 is not less than 23 wt% (e.g., 25 wt%, 28 wt%, 30 wt%, 40 wt%) and the concentration of magnesium ions is not greater than the concentration of ammonium ions.

[0023] In some implementations, the concentration and crystallization methods include heating concentration, evaporation concentration, or vacuum evaporation concentration.

[0024] In some embodiments, the filtrate D2 contains magnesium ions, with the magnesium ion content being 1-20 wt% (e.g., 2 wt%, 4 wt%, 8 wt%, 12 wt%, 15 wt%) based on the total mass of the solution.

[0025] Compared to filtrate D1, filtrate D2 contains virtually no ammonium ions; its ion concentration is related to the amount of hydrochloric acid added.

[0026] In some implementations, in step S5, the mass fraction of ammonia is ≤35%, for example, 5%, 10%, 20%, or 30%.

[0027] In some implementations, in step S5, the main component of the magnesium-containing precipitate F is magnesium hydroxide. The filtrate G containing ammonium and magnesium ions can be recycled back to step (1).

[0028] Compared with the prior art, the beneficial effects of the technical solution of this invention are as follows:

[0029] This invention provides a method for the recycling of solid waste containing multiple complex components. Through a series of steps including water washing and filtration, concentration and crystallization with hydrochloric acid, and precipitation with ammonia, the method achieves efficient recovery of ammonium salts and magnesium ion precipitates from solid waste generated during the magnesium silicide process for silane products. A small amount of solution is then recycled using energy-efficient methods. Furthermore, the method requires no additional components and incurs no extra processing equipment or costs. Attached Figure Description

[0030] Figure 1 This is a flowchart illustrating one embodiment of the processing method described in this invention.

[0031] Figure 2 This is a flowchart illustrating the processing method for Comparative Example 3. Detailed Implementation

[0032] To provide a detailed understanding of the technical features and content of this invention, preferred embodiments will be described in more detail below. While preferred embodiments of the invention are described in the examples, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0033] <Source of Raw Materials>

[0034] The solid waste residue from the magnesium silicide method for preparing silane products originates from the waste residue generated during the process of producing silane products using the magnesium silicide method, specifically the waste residue generated during the synthesis of silane products from ammonium chloride and magnesium chloride.

[0035] Example 1:

[0036] The solid waste generated from the preparation of silane products by the magnesium silicide method includes: insoluble components and soluble components; wherein, the content of insoluble components is <10wt%, and in the soluble components, the molar ratio of ammonium ions to magnesium ions is 0.5:1.

[0037] like Figure 1 As shown, the treatment method for this solid waste residue is as follows:

[0038] S1. Place 10.01g of the solid waste residue to be treated in a mortar and grind it for 0.5 hours to form a powder with a particle size of 1.9mm. Transfer the ground waste residue powder to a beaker, add 150ml of water at room temperature, stir for 30min, let stand for 30min, and then separate the solid and liquid after the waste residue has hardly changed. The separated filtrate A contains 35wt% ammonium ions and 1wt% magnesium ions, and the amount of precipitate B containing silicon and magnesium impurities obtained by filtration is 1.87g.

[0039] S2. Add 60 ml of 20 wt% hydrochloric acid to filtrate A, stir for 30 minutes, adjust the pH to 5, then heat the reaction solution to 100℃ and heat for 1 hour to concentrate and crystallize until the ammonium ion concentration in the solution is not less than 23 wt% and the magnesium ion concentration is not greater than the ammonium ion concentration. Filter to obtain 10.614 g of ammonium chloride solid C and filtrate D1 containing 0.059 g of solute; in filtrate D1, the ammonium ion content is 25 wt% and the magnesium ion content is 1.2 wt%.

[0040] S3: Add 20wt% hydrochloric acid to precipitate B until the precipitate no longer decreases, filter, and obtain filtrate D2 containing 6.771g of solute (of which the magnesium ion content is 19wt%), and obtain 0.871g of harmless solid E.

[0041] S4: Mix the filtrate D1 and filtrate D2 obtained in the above steps to form solution D. Add 25wt% ammonia water to solution D. When pH=8, filter to obtain 4.169g of magnesium ion precipitate F and filtrate G containing ammonium ion and magnesium ion. Filtrate G is recycled to filtrate A.

[0042] The ammonium salt solid C contains 23.5% nitrogen by mass and less than 1 ppm of heavy metal ions. In the magnesium ion precipitate F, the magnesium ion compound mass fraction is 99%, removing harmless Si impurities, and the magnesium ion compound recovery efficiency reaches 91.3%.

[0043] Example 2:

[0044] The solid waste generated from the preparation of silane products by the magnesium silicide method includes: insoluble components and soluble components; wherein, the content of insoluble components is <10wt%, and in the soluble components, the molar ratio of ammonium ions to magnesium ions is 1:1.

[0045] like Figure 1 As shown, the treatment method for this solid waste residue is as follows:

[0046] S1. Place 10.02g of the solid waste residue to be treated in a mortar and grind it for 0.5 hours to form a powder with a particle size of 1.8mm. Transfer the ground waste residue powder to a beaker, add 150ml of water at room temperature, stir for 30min, let stand for 30min, and then separate the solid and liquid after the waste residue has hardly changed. The separated filtrate A contains 37wt% ammonium ions and 1wt% magnesium ions, and the amount of precipitate B containing silicon and magnesium impurities obtained by filtration is 1.78g.

[0047] S2. Add 60 ml of 20 wt% hydrochloric acid to filtrate A, stir for 30 minutes, adjust the pH to 5, then heat the reaction solution to 100℃ and heat for 1 hour to concentrate and crystallize until the ammonium ion concentration in the solution is not less than 23 wt% and the magnesium ion concentration is not greater than the ammonium ion concentration. Filter to obtain 9.707 g of ammonium salt solid C and filtrate D1 containing 0.098 g of solute; in filtrate D1, the ammonium ion content is 26 wt% and the magnesium ion content is 1.2 wt%.

[0048] S3: Add 20wt% hydrochloric acid to precipitate B until the precipitate no longer decreases, filter, and obtain filtrate D2 containing 4.773g of solute (of which the content of magnesium ions is 19wt%), and obtain 0.74g of harmless solid E.

[0049] S4: Mix the filtrate D1 and filtrate D2 obtained in the above steps to form solution D. Add 25wt% ammonia water to solution D. When pH=8, filter to obtain 2.973g of magnesium ion precipitate F and filtrate G containing ammonium ion and magnesium ion. Filtrate G is recycled to filtrate A.

[0050] The ammonium salt solid C contains 23.7% nitrogen by mass, and the content of heavy metal ions is less than 1 ppm. In the magnesium ion precipitate F, the mass fraction of magnesium ion compounds is 99.2%, removing harmless impurities such as Si, and the recovery efficiency of magnesium ion compounds reaches 92.7%.

[0051] Example 3:

[0052] The solid waste generated from the preparation of silane products by the magnesium silicide method includes: insoluble components and soluble components; wherein, the content of insoluble components is <10wt%, and in the soluble components, the molar ratio of ammonium ions to magnesium ions is 10:1.

[0053] like Figure 1 As shown, the treatment method for this solid waste residue is as follows:

[0054] S1. Place 10.03g of the solid waste residue to be treated in a mortar and grind it for 0.5 hours to form a powder with a particle size of 1.9mm. Transfer the ground waste residue powder to a beaker, add 150ml of water at room temperature, stir for 30min, let stand for 30min, and then separate the solid and liquid after the waste residue has hardly changed. The separated filtrate A contains 37wt% ammonium ions and 0.9wt% magnesium ions, and the amount of precipitate B containing silicon and magnesium impurities obtained by filtration is 1.53g.

[0055] S2. Add 60 ml of 20 wt% hydrochloric acid to filtrate A, stir for 30 minutes, adjust the pH to 5, then heat the reaction solution to 100℃ and heat for 1 hour to concentrate and crystallize until the ammonium ion concentration in the solution is not less than 23 wt% and the magnesium ion concentration is not greater than the ammonium ion concentration. Filter to obtain 9.330 g of ammonium salt solid C and filtrate D1 containing 0.345 g of solute; in filtrate D1, the ammonium ion content is 27 wt% and the magnesium ion content is 1.2 wt%.

[0056] S3: Add 20wt% hydrochloric acid to precipitate B until the precipitate no longer decreases, then filter to obtain filtrate D2 containing 1.682g of solute (of which the magnesium ion content is 18wt%), and obtain 0.520g of harmless solid E.

[0057] S4: Mix the filtrate D1 and filtrate D2 obtained in the above steps to form solution D. Add 25wt% ammonia water to solution D. When pH=8, filter to obtain 1.237g of magnesium ion precipitate F and filtrate G containing ammonium ion and magnesium ion. Filtrate G is recycled to filtrate A.

[0058] The ammonium salt solid C contains 24% nitrogen by mass and less than 1 ppm of heavy metal ions. In the magnesium ion precipitate F, the magnesium ion compound mass fraction is 99.5%, removing harmless Si impurities, and the magnesium ion compound recovery efficiency reaches 94.8%.

[0059] Example 4:

[0060] The solid waste generated from the preparation of silane products by the magnesium silicide method includes: insoluble components and soluble components; wherein, the content of insoluble components is <10wt%, and in the soluble components, the molar ratio of ammonium ions to magnesium ions is 20:1.

[0061] like Figure 1 As shown, the treatment method for this solid waste residue is as follows:

[0062] S1. Place 10.010g of the solid waste residue to be treated in a mortar and grind it for 0.5 hours to form a powder with a particle size of 1.9mm. Transfer the ground waste residue powder to a beaker, add 150ml of water at room temperature, stir for 30min, let stand for 30min, and then separate the solid and liquid after the waste residue has hardly changed. The separated filtrate A contains 38wt% ammonium ions and 0.8wt% magnesium ions, and the amount of precipitate B containing silicon and magnesium impurities obtained by filtration is 1.22g.

[0063] S2. Add 60 ml of 20 wt% hydrochloric acid to filtrate A, stir for 30 minutes, adjust the pH to 5, then heat the reaction solution to 100℃ and heat for 1 hour to concentrate and crystallize until the ammonium ion concentration in the solution is not less than 23 wt% and the magnesium ion concentration is not greater than the ammonium ion concentration. Filter to obtain 9.870 g of ammonium salt solid C and filtrate D1 containing 0.263 g of solute; in filtrate D1, the ammonium ion content is 26 wt% and the magnesium ion content is 1 wt%.

[0064] S3: Add 20wt% hydrochloric acid to precipitate B until the precipitate no longer decreases, then filter to obtain filtrate D2 containing 1.142g of solute (of which the magnesium ion content is 16wt%), and obtain 0.210g of harmless solid E.

[0065] S4: Mix the filtrate D1 and filtrate D2 obtained in the above steps to form solution D. Add 25wt% ammonia water to solution D. When pH=8, filter to obtain 0.858g of magnesium ion precipitate F and filtrate G containing ammonium ion and magnesium ion. Filtrate G is recycled to filtrate A.

[0066] The nitrogen content in ammonium salt solid C is 23.6% by mass, and the content of heavy metal ions is less than 1 ppm. In the magnesium ion precipitate F, the magnesium ion compound mass fraction reaches 99.1%, removing harmless Si impurities, and the magnesium ion compound recovery efficiency reaches 97.9%.

[0067] Comparative Example 1

[0068] The solid waste generated from the preparation of silane products by the magnesium silicide method includes: insoluble components and soluble components; wherein, the content of insoluble components is <10wt%, and in the soluble components, the molar ratio of ammonium ions to magnesium ions is 20:1.

[0069] The treatment method for this solid waste residue is as follows:

[0070] 10.011g of solid waste residue to be treated was placed in a mortar and ground for 0.5 hours to form a powder with a particle size of 1.8mm. The ground waste residue powder was transferred to a beaker, and 150ml of water was added at room temperature. The mixture was stirred for 30 minutes and allowed to stand for 30 minutes until the waste residue showed almost no change. Solid-liquid separation was then performed to obtain filtrate A, which contained 38wt% ammonium ions and 0.8wt% magnesium ions. The amount of precipitate B containing silicon and magnesium impurities was 1.21g.

[0071] The filtrate A was directly heated to 100°C and concentrated for 1 hour to obtain an ammonium salt solid containing magnesium ion impurities. The mass fraction of nitrogen in the ammonium salt solid was 19%, and the content of heavy metal ions was 100 ppm.

[0072] Precipitate B contains magnesium ions and harmless Si impurities. The magnesium ion mass fraction accounts for 70% of the total, making it unsuitable for direct landfill.

[0073] Comparative Example 2

[0074] The solid waste generated from the preparation of silane products by the magnesium silicide method includes: insoluble components and soluble components; wherein, the content of insoluble components is <10wt%, and in the soluble components, the molar ratio of ammonium ions to magnesium ions is 20:1.

[0075] The treatment method for this solid waste residue is as follows:

[0076] S1. Place 10.020g of the solid waste residue to be treated in a mortar and grind it for 0.5 hours to form a powder with a particle size of 1.9mm. Transfer the ground waste residue powder to a beaker, add 150ml of water at room temperature, stir for 30min, let stand for 30min, and then separate the solid and liquid after the waste residue has hardly changed. The separated filtrate A contains 38wt% ammonium ions and 0.8wt% magnesium ions, and the amount of precipitate B containing silicon and magnesium impurities obtained by filtration is 1.23g.

[0077] S2. Add 60 ml of 20 wt% hydrochloric acid to filtrate A, stir for 30 minutes, adjust the pH to 5, then heat the reaction solution to 100℃ and heat for 1 hour to concentrate and crystallize until the ammonium ion concentration in the solution is not less than 23 wt% and the magnesium ion concentration is not greater than the ammonium ion concentration. Filter to obtain 9.860 g of ammonium salt solid C and filtrate D1 containing 0.258 g of solute; in filtrate D1, the ammonium ion content is 27 wt% and the magnesium ion content is 1 wt%.

[0078] S3: Add 20wt% hydrochloric acid to precipitate B until the precipitate no longer decreases, then filter to obtain filtrate D2 containing 1.141g of solute (of which the magnesium ion content is 16wt%), and obtain 0.220g of harmless solid E.

[0079] S4: Mix the filtrate D1 and filtrate D2 obtained in the above steps to form solution D.

[0080] The nitrogen content in ammonium salt solid C is 23.6% by mass, and the content of heavy metal ions is less than 1 ppm. However, in the recovered magnesium ion-containing filtrate D, the magnesium ion compound content reaches 99.1% by mass, and the waste magnesium ion solution still has a significant impact on the environment.

[0081] Comparative Example 3

[0082] The solid waste generated from the preparation of silane products by the magnesium silicide method includes: insoluble components and soluble components; wherein, the content of insoluble components is <10wt%, and in the soluble components, the molar ratio of ammonium ions to magnesium ions is 20:1.

[0083] like Figure 2 The treatment method for this solid waste residue is as follows:

[0084] S1. Place the solid waste residue to be treated in a mortar and grind it for 0.5 hours to form a powder with a particle size of 1.9 mm. Transfer the ground waste residue powder to a beaker, add 150 ml of water at room temperature, stir for 30 min, let stand for 30 min, and then separate the solid and liquid after the waste residue has hardly changed. The separated filtrate A contains 38 wt% ammonium ions and 0.8 wt% magnesium ions, and the amount of precipitate B containing silicon and magnesium impurities obtained by filtration is 1.21 g.

[0085] S2. Add 60 ml of 20 wt% hydrochloric acid to filtrate A, stir for 30 minutes, adjust the pH to 5, then heat the reaction solution to 100℃ and heat for 1 hour to concentrate and crystallize until the ammonium ion concentration in the solution is not less than 23 wt% and the magnesium ion concentration is not greater than the ammonium ion concentration. Filter to obtain 9.871 g of ammonium salt solid C and filtrate D1 containing 0.264 g of solute; in filtrate D1, the ammonium ion content is 26 wt% and the magnesium ion content is 1 wt%.

[0086] S3: Add 20wt% hydrochloric acid to precipitate B until the precipitate no longer decreases, then filter to obtain filtrate D2 containing 1.141g of solute (of which the magnesium ion content is 16wt%), and obtain 0.211g of harmless solid E.

[0087] S4: Mix the filtrate D1 and filtrate D2 obtained in the above steps to form solution D.

[0088] S5: Add 30wt% ammonium carbonate to solution D. When pH=8, filter to obtain a precipitate F containing magnesium ions and a filtrate G containing ammonium ions and magnesium ions.

[0089] S6: Add 20wt% hydrochloric acid to filtrate G.

[0090] S7: The solution obtained in step S6 is concentrated by heating to obtain ammonium salt solid H.

[0091] According to Comparative Example 3, if other alkaline solutions containing ammonia ions are used instead of ammonia water, such as ammonium carbonate, it will add 2-3 steps, including the use of hydrochloric acid and concentration treatment, and the processing cost will also increase significantly.

[0092] For the solid waste residue from the magnesium silicide process for preparing silane products, directly entrusting it to a third party for post-processing incurs additional costs. However, by treating the waste residue harmlessly according to the method of this invention, the resulting ammonium salt solid and magnesium ion precipitate can serve as value-added products in the magnesium silicide process for preparing silane products. Furthermore, the method of this invention can increase the enterprise's revenue by 2-7 times compared to the cost of third-party processing, thus saving costs.

[0093] Some embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for treating solid waste residue from the preparation of silane products using the magnesium silicide method, characterized in that, The steps include the following: S1. Crush and grind the solid waste residue to be treated into powder, then add water and stir to dissolve until the weight of the precipitate no longer decreases. Let it stand and perform solid-liquid separation to obtain filtrate A and precipitate B. S2. Add hydrochloric acid aqueous solution to the filtrate A to adjust its pH value to <7, and then concentrate and crystallize until the concentration of ammonium ions in the solution is not less than 23wt% of the mass of the solution and the concentration of magnesium ions is not greater than the concentration of ammonium ions. Then, stop the concentration and crystallization. After solid-liquid separation, ammonium chloride solid C and filtrate D1 containing ammonium ions and magnesium ions are obtained. S3: Add hydrochloric acid aqueous solution to the precipitate B and stir until the weight of the precipitate no longer decreases. After solid-liquid separation, obtain magnesium ion-containing filtrate D2 and silicon-containing solid E. S4: Mix the filtrate D1 and the filtrate D2 to form solution D; S5: Add ammonia water to the solution D to adjust the pH value to 8-10, and then perform solid-liquid separation to obtain magnesium precipitate F and filtrate G containing ammonium ions and magnesium ions.

2. The processing method according to claim 1, characterized in that, In step S2, hydrochloric acid aqueous solution is added to the filtrate A to adjust its pH value to ≤5.

3. The processing method according to claim 1, characterized in that, The solid waste residue to be treated includes insoluble components and soluble components, wherein: The content of insoluble components accounts for less than 10 wt% of the total solid waste residue. Based on the molar amount of ions in the soluble component, the molar ratio of ammonium ions to magnesium ions in the soluble component is 0.5:1 to 20:

1.

4. The processing method according to claim 1, characterized in that, In step S1, the solid waste residue to be treated is ground into powder with a particle size of ≤2mm.

5. The processing method according to claim 1, characterized in that, In step S1, the temperature for adding water and stirring to dissolve is 20-30℃, the stirring time is 20-40 min, and the standing time is 20-60 min.

6. The processing method according to claim 1, characterized in that, The filtrate A contains chloride ions as anions and ammonium and magnesium ions as cations; wherein, based on the molar mass of the ions, the molar ratio of ammonium ions to magnesium ions is 0.5:1 to 80:1; and / or The precipitate B includes silicon, silicon oxide, magnesium oxide, magnesium hydroxide, and magnesium carbonate.

7. The processing method according to claim 1, characterized in that, Based on the total mass of the solution, the concentration of ammonium ions in the filtrate D1 in step S2 is not less than 23 wt%, and the concentration of magnesium ions is not greater than the concentration of ammonium ions.

8. The processing method according to claim 1, characterized in that, The concentration and crystallization method is heating concentration.

9. The processing method according to claim 1, characterized in that, The concentration and crystallization method is evaporation concentration.

10. The processing method according to claim 1, characterized in that, The filtrate D2 contains magnesium ions, and the content of magnesium ions is 1-20 wt% based on the total mass of the solution.

11. The processing method according to claim 1, characterized in that, In step S5, the mass fraction of ammonia is ≤35%.

12. The processing method according to claim 1, characterized in that, In step S5, the main component of the magnesium-containing precipitate F is magnesium hydroxide.

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