Method for controllably preparing silicon monoxide by using silicon wafer cutting waste

Abstract

The invention relates to a method for controllably preparing silicon monoxide by using silicon wafer cutting waste, and belongs to the technical field of silicon wafer cutting waste recovery and utilization. Aiming at the characteristics that the particle size of the silicon wafer cutting waste is submicron and the silicon wafer cutting waste is easy to oxidize, the silicon wafer cutting waste is dried and crushed, and impurities in the silicon wafer cutting waste are removed through wet-process acid leaching to obtain silicon powder with the purity greater than 2N; placing the silicon powder in a vacuum environment, slowly introducing oxygen, and carrying out a controllable reaction under a high-temperature condition to generate silicon monoxide; the gas trapping device is used for rapidly guiding silicon monoxide into the condensation pipeline for cooling and condensation, the temperature gradient of the condensation pipeline is controlled, and deposition is regulated and controlled to be silicon monoxide powder. The method has the advantages of being high in raw material adaptability, simple in equipment operation, high in economic benefit, energy-saving, environment-friendly and the like, and a reliable technical approach is provided for cost preparation of silicon monoxide.

Description

Technical Field

[0001] The invention relates to a method for controllably preparing silicon monoxide by utilizing silicon slice cutting waste, belonging to the technical field of recycling and utilizing silicon slice cutting waste. Background Art

[0002] During the silicon wafer cutting process, a large amount of 6N grade high-purity silicon is lost in the form of silicon wafer cutting waste, resulting in waste of high-purity silicon resources, reduced profits, environmental pollution and other problems. However, the surface oxidation caused by the uncontrolled oxygen content of silicon wafer cutting waste not only hinders the reaction between acid and impurities and limits the purity of the product during the wet acid leaching process, but also oxidizes metal impurities and forms gaseous volatiles during the pyrometallurgical refining process, hinders the separation of slag silicon, reduces the recovery rate of silicon, and the residual oxygen content of the refined ingot product is too high, making it difficult to return to the crystalline silicon preparation link.

[0003] As a highly active inorganic material, silicon monoxide exhibits good stability at high temperatures (greater than 1200°C) and in a vacuum environment, but it easily reacts with oxygen in the air to form silicon dioxide at room temperature. It has advantages such as high specific capacity, excellent cycle stability, and environmental friendliness in the preparation of silicon-oxygen negative electrode materials. However, its preparation methods such as high-temperature reduction, hydrogen reduction, and carbon thermal reduction have problems such as high energy consumption, difficulty in purity control, large environmental impact, and poor material stability. In particular, in the high-temperature reduction method, excessive addition of carbon as a reducing agent may lead to the generation of silicon carbide impurities, affecting the purity of silicon monoxide; hydrogen reduction is not suitable for large-scale industrial production due to its dangerousness; and although the carbon thermal reduction method can prepare nano-scale silicon monoxide powder, it also faces challenges in energy consumption and efficiency. Summary of the invention

[0004] In view of the problems of silicon waste from existing silicon wafer cutting waste and the difficulty in purity control and low efficiency in the silicon monoxide preparation process, the present invention proposes a method for controllably preparing silicon monoxide using silicon wafer cutting waste, which performs wet leaching and purification on silicon wafer cutting waste particles, and controllably oxidizes and condenses to prepare high-purity and high-activity silicon monoxide powder, thereby realizing high-value utilization of silicon wafer cutting waste.

[0005] A method for controlling the preparation of silicon monoxide using silicon wafer cutting waste, the specific steps are as follows:

[0006] (1) drying and dehydrating the silicon wafer cutting waste block material, and crushing it to obtain silicon wafer cutting waste particles;

[0007] (2) subjecting the silicon wafer cutting waste particles to wet acid leaching to remove impurities and obtain silicon powder with a purity greater than 2N;

[0008] (3) placing silicon powder in a vacuum furnace, evacuating the vacuum furnace until the pressure inside is less than 10 Pa, slowly and evenly introducing oxygen into the vacuum furnace, and controlling the oxidation of silicon powder and oxygen to generate silicon monoxide through a high-temperature oxidation reaction;

[0009] (4) Using a gas capture device to quickly introduce silicon monoxide into a condensation pipe for condensation, and controlling the temperature gradient of the condensation pipe to deposit it into silicon monoxide powder.

[0010] Preferably, the particle size of the silicon wafer cutting waste particles in step (1) is less than 1 μm.

[0011] Preferably, the acid solution used in the wet acid leaching in step (2) is one or more of sulfuric acid, hydrochloric acid, hydrofluoric acid, nitric acid, citric acid, and tartaric acid.

[0012] More preferably, the acid solution contains H + The concentration is 0.1-4 mol / L, the liquid-solid ratio of the acid solution to the silicon wafer cutting waste particles is 5-50:1 in mL:g, the leaching temperature is 40-100°C, and the stirring rate is 100-1000 rpm.

[0013] Preferably, in step (3), the oxygen rate is 1 to 10 mL / min, the temperature of the high-temperature oxidation reaction is 1200 to 1400° C., and the time is 0.1 to 3 h.

[0014] Preferably, the temperature gradient of the condensation pipeline in step (4) is 10 to 150° C. / m.

[0015] The gas capture device in step (4) may use a capture method including, but not limited to, cyclone, gravity, cloth bag, and static electricity.

[0016] The beneficial effects of the present invention are:

[0017] (1) The present invention uses easily oxidizable, high-purity silicon wafer cutting waste as raw material, and prepares a high-purity and high-activity silicon monoxide powder product through wet acid leaching, high-temperature controlled oxidation and controlled condensation;

[0018] (2) By means of temperature control, slow oxygen flow, reaction time control and heating before condensation, etc., the disproportionation reaction of silicon dioxide and silicon monoxide is avoided to ensure the purity of silicon monoxide powder products;

[0019] (3) The high-purity and high-activity silicon monoxide powder product of the present invention has uniform particle size and can be used to prepare negative electrode materials for lithium batteries, thus achieving high-value utilization of waste silicon resources and helping to alleviate the current situation of insufficient silicon monoxide supply;

[0020] (4) The present invention has the advantages of strong raw material adaptability, simple equipment operation, high economic benefit, energy saving and environmental protection, etc., which provides a reliable technical approach for the cost-effective preparation of silicon monoxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a process flow chart of the present invention;

[0022] Figure 2 It is a schematic diagram of the principle of the controllable preparation of silicon monoxide according to the present invention. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below in conjunction with specific implementation modes, but the protection scope of the present invention is not limited to the described contents.

[0024] Example 1: The silicon wafer cutting waste in this example is a filter cake obtained by plate and frame filtration of silicon wafer cutting slurry, with an initial water content of 55.43% and an initial block particle size of 1 to 10 cm;

[0025] A method for controlling the preparation of silicon monoxide using silicon wafer cutting waste, the specific steps are as follows:

[0026] (1) drying and dehydrating the silicon wafer cutting waste block material, and crushing it to obtain silicon wafer cutting waste particles with a particle size of less than 1 μm;

[0027] (2) adding the silicon wafer cutting waste particles into sulfuric acid with a concentration of 0.5 mol / L, and performing wet acid leaching for 3 hours at a temperature of 60° C. and a stirring rate of 600 r / min to remove impurities, thereby obtaining silicon powder with a purity greater than 2N, wherein the total impurity content in the silicon powder is 125.46 ppmw; the liquid-to-solid ratio of the sulfuric acid to the silicon wafer cutting waste particles is 15:1 in mL:g;

[0028] (3) Figure 1 As shown, silicon powder is placed in a vacuum furnace, and the vacuum furnace is evacuated until the pressure inside the vacuum furnace is less than 10Pa. Oxygen is introduced into the vacuum furnace at a rate (5mL / min), and a high-temperature oxidation reaction (0.5h) is performed at a temperature (1300°C) to controllably oxidize the silicon powder with oxygen to generate silicon monoxide;

[0029] (4) using a gas capture device to quickly introduce silicon monoxide into a condensation pipe for condensation, and controlling the temperature gradient of the condensation pipe (70° C. / m) to deposit it into silicon monoxide powder;

[0030] The total impurity content of the silicon monoxide powder in this example is 218 ppmw.

[0031] Example 2: The silicon wafer cutting waste in this example is a filter cake obtained by plate and frame filtration of silicon wafer cutting slurry, with an initial water content of 57.68% and an initial block particle size of 1 to 10 cm;

[0032] A method for controlling the preparation of silicon monoxide using silicon wafer cutting waste, the specific steps are as follows:

[0033] (1) drying and dehydrating the silicon wafer cutting waste block material, and crushing it to obtain silicon wafer cutting waste particles with a particle size of less than 1 μm;

[0034] (2) adding the silicon wafer cutting waste particles into hydrochloric acid with a concentration of 2 mol / L, and performing wet acid leaching for 2.5 hours at a temperature of 55° C. and a stirring rate of 800 r / min to remove impurities, thereby obtaining silicon powder with a purity greater than 2N, wherein the total impurity content in the silicon powder is 111.75 ppmw; the liquid-to-solid ratio of the hydrochloric acid to the silicon wafer cutting waste particles is 20:1 in mL:g;

[0035] (3) Figure 1 As shown, silicon powder is placed in a vacuum furnace, and the vacuum furnace is evacuated until the pressure inside the vacuum furnace is less than 10Pa. Oxygen is introduced into the vacuum furnace at a rate (2mL / min), and a high-temperature oxidation reaction (1h) is performed at a temperature (1400°C) to controllably oxidize the silicon powder with oxygen to generate silicon monoxide;

[0036] (4) using a gas capture device to quickly introduce silicon monoxide into a condensation pipe for condensation, and controlling the temperature gradient of the condensation pipe (40° C. / m) to deposit it into silicon monoxide powder;

[0037] The total impurity content of the silicon monoxide powder in this example is 261 ppmw.

[0038] Example 3: The silicon wafer cutting waste in this example is a filter cake obtained by plate and frame filtration of silicon wafer cutting slurry, with an initial water content of 57.68% and an initial block particle size of 1 to 10 cm;

[0039] A method for controlling the preparation of silicon monoxide using silicon wafer cutting waste, the specific steps are as follows:

[0040] (1) drying and dehydrating the silicon wafer cutting waste block material, and crushing it to obtain silicon wafer cutting waste particles with a particle size of less than 1 μm;

[0041] (2) adding the silicon wafer cutting waste particles into a mixed acid (the hydrofluoric acid concentration in the mixed acid is 1 mol / L, and the sulfuric acid concentration is 1 mol / L), and performing wet acid leaching for 1.5 hours at a temperature of 50° C. and a stirring rate of 500 r / min to remove impurities, thereby obtaining silicon powder with a purity greater than 2N, wherein the total impurity content in the silicon powder is 183.17 ppmw; the liquid-to-solid ratio of the mixed acid to the silicon wafer cutting waste particles is 20:1 in mL:g;

[0042] (3) Figure 1 As shown, silicon powder is placed in a vacuum furnace, and the vacuum furnace is evacuated until the pressure inside the vacuum furnace is less than 10Pa. Oxygen is introduced into the vacuum furnace at a rate (6mL / min), and a high-temperature oxidation reaction (1.5h) is performed at a temperature (1350°C) to controllably oxidize the silicon powder with oxygen to generate silicon monoxide;

[0043] (5) using a gas capture device to quickly introduce silicon monoxide into a condensation pipe for condensation, and controlling the temperature gradient of the condensation pipe (80° C. / m) to deposit silicon monoxide powder;

[0044] The total impurity content of the silicon monoxide powder in this example is 110 ppmw.

[0045] Example 4: The silicon wafer cutting waste in this example is a filter cake obtained by plate and frame filtration of silicon wafer cutting slurry, with an initial water content of 57.94% and an initial block particle size of 1 to 10 cm;

[0046] A method for controlling the preparation of silicon monoxide using silicon wafer cutting waste, the specific steps are as follows:

[0047] (1) drying and dehydrating the silicon wafer cutting waste block material, and crushing it to obtain silicon wafer cutting waste particles with a particle size of less than 1 μm;

[0048] (2) adding the silicon wafer cutting waste particles to tartaric acid with a concentration of 1 mol / L, and performing wet acid leaching for 2 hours at a temperature of 65° C. and a stirring rate of 600 r / min to remove impurities, thereby obtaining silicon powder with a purity greater than 2N, wherein the total impurity content in the silicon powder is 128.47 ppmw; the liquid-to-solid ratio of the tartaric acid to the silicon wafer cutting waste particles is 20:1 in mL:g;

[0049] (3) Figure 1 As shown, silicon powder is placed in a vacuum furnace, and the vacuum furnace is evacuated until the pressure inside the vacuum furnace is less than 10Pa. Oxygen is introduced into the vacuum furnace at a rate (3mL / min), and a high-temperature oxidation reaction (3h) is performed at a temperature (1200°C) to controllably oxidize the silicon powder with oxygen to generate silicon monoxide;

[0050] (5) using a gas capture device to quickly introduce silicon monoxide into a condensation pipe for condensation, and controlling the temperature gradient of the condensation pipe (50° C. / m) to deposit it into silicon monoxide powder;

[0051] The total impurity content of the silicon monoxide powder in this example is 245 ppmw.

[0052] Example 5: The silicon wafer cutting waste in this example is a filter cake obtained by plate and frame filtration of silicon wafer cutting slurry, with an initial water content of 56.93% and an initial block particle size of 1 to 10 cm;

[0053] A method for controlling the preparation of silicon monoxide using silicon wafer cutting waste, the specific steps are as follows:

[0054] (1) drying and dehydrating the silicon wafer cutting waste block material, and crushing it to obtain silicon wafer cutting waste particles with a particle size of less than 1 μm;

[0055] (2) adding the silicon wafer cutting waste particles to citric acid with a concentration of 2 mol / L, and performing wet acid leaching at a temperature of 45° C. and a stirring rate of 700 r / min for 1 hour to remove impurities, thereby obtaining silicon powder with a purity greater than 2N, wherein the total impurity content in the silicon powder is 234.47 ppmw; the liquid-to-solid ratio of the citric acid to the silicon wafer cutting waste particles is 25:1 in mL:g;

[0056] (3) Figure 1 As shown, silicon powder is placed in a vacuum furnace, and the vacuum furnace is evacuated until the pressure inside the vacuum furnace is less than 10Pa. Oxygen is introduced into the vacuum furnace at a rate (5mL / min), and a high-temperature oxidation reaction (2.5h) is performed at a temperature (1250°C) to controllably oxidize the silicon powder with oxygen to generate silicon monoxide;

[0057] (5) using a gas capture device to quickly introduce silicon monoxide into a condensation pipe for condensation, and controlling the temperature gradient of the condensation pipe (45°C / m) to deposit it into silicon monoxide powder;

[0058] The total impurity content of the silicon monoxide powder in this example is 262 ppmw;

[0059] The impurity content results of the silicon monoxide products in Examples 1 to 5 are shown in Table 1 below;

[0060] Table 1 Impurity content results of silicon monoxide products of Examples 1 to 5 (ppmw)

[0061]

[0062] As can be seen from Table 1, the embodiments of the present invention avoid the disproportionation reaction of silicon dioxide and silicon monoxide by means of temperature control, slow oxygen flow, control of reaction time and heating before condensation, thereby ensuring the purity of the silicon monoxide powder product, and the content of the impurity elements Fe, Al and Ni is relatively low.

[0063] The specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose of the present invention.

Claims

1. A method for controllably preparing silicon monoxide using silicon wafer cutting waste, characterized in that: The specific steps are as follows: (1) drying and dehydrating the silicon wafer cutting waste block material, and crushing it to obtain silicon wafer cutting waste particles; (2) subjecting the silicon wafer cutting waste particles to wet acid leaching to remove impurities and obtain silicon powder with a purity greater than 2N; (3) placing silicon powder in a vacuum furnace, evacuating the vacuum furnace until the pressure inside is less than 10 Pa, slowly and evenly introducing oxygen into the vacuum furnace, and controlling the oxidation of silicon powder and oxygen to generate silicon monoxide through a high-temperature oxidation reaction; (4) Using a gas capture device to quickly introduce silicon monoxide into a condensation pipe for condensation, and controlling the temperature gradient of the condensation pipe to deposit it into silicon monoxide powder.

2. The method for controllably preparing silicon monoxide using silicon wafer cutting waste according to claim 1, characterized in that: The particle size of the silicon wafer cutting waste particles in step (1) is less than 1 μm.

3. The method for controllably preparing silicon monoxide using silicon wafer cutting waste according to claim 1, characterized in that: The acid solution used in the wet acid leaching in step (2) is one or more of sulfuric acid, hydrochloric acid, hydrofluoric acid, nitric acid, citric acid, and tartaric acid.

4. The method for controllably preparing silicon monoxide using silicon wafer cutting waste according to claim 2, characterized in that: The acid solution contains H + The concentration is 0.1-4 mol / L, the liquid-solid ratio of the acid solution to the silicon wafer cutting waste particles is 5-50:1 in mL:g, the leaching temperature is 40-100°C, and the stirring rate is 100-1000 rpm.

5. The method for controllably preparing silicon monoxide using silicon wafer cutting waste according to claim 5, characterized in that: In step (3), the oxygen rate is 1 to 10 mL / min, the temperature of the high-temperature oxidation reaction is 1200 to 1400° C., and the time is 0.1 to 3 h.

6. The method for controllably preparing silicon monoxide using silicon wafer cutting waste according to claim 1, characterized in that: The temperature gradient of the condensation pipeline in step (4) is 10 to 150°C / m.

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