A treatment agent for removing aluminum from high-boiling substances in polysilicon and its application

Abstract

The present invention provides a treatment agent for removing aluminum from high-boiling polysilicon and its application. The treatment agent for removing aluminum from high-boiling polysilicon of the present invention comprises the following components by mass: 900 to 1000 parts of alkali metal chloride, 2 to 10 parts of alkaline earth metal chloride, and 1 to 5 parts of transition metal chloride. The treatment agent for removing aluminum from high-boiling polysilicon of the present invention can efficiently remove aluminum chloride impurities in high-boiling polysilicon, and the treatment agent is obtained by compounding a plurality of cheap and readily available metal salts, and has the advantage of low cost.

Description

Technical Field

[0001] The invention belongs to the technical field of polysilicon production, and relates to a treatment agent for removing aluminum from high-boiling substances in polysilicon and application thereof. Background Art

[0002] Polysilicon is the basic raw material of the photovoltaic industry. During its preparation process, a portion of high-boiling compounds (commonly known as "high-boiling substances") with a boiling point exceeding 70°C will be produced as by-products, accounting for 7.0% to 8.0% of the crude monomer product. 99% of these high-boiling substances are polychlorosilanes, which have very complex components and similar boiling points. It is difficult to separate the components using commonly used separation methods, so they cannot be effectively utilized. In the actual production process, the main treatment method is to first concentrate, then separate and recover a portion of the remaining low-boiling substances such as silicon tetrachloride, and then hydrolyze them together with solid impurities brought out during the processing of other polysilicon such as metal chlorides, which consumes a large amount of valuable Si and Cl elements, which is not conducive to the sustainable development of polysilicon production. In addition, if these high-boiling substances are not handled properly, it will increase the production costs of the enterprise and cause safety and environmental problems.

[0003] In order to solve the above problems, people have developed organic amines such as tributylamine, tri-n-octylamine, N,N-diethylaniline, N,N-diethylbutylamine, etc. as catalysts to crack high-boiling products and convert them into monosilicon compounds for recycling. However, high-boiling products contain some metal chloride impurities, mainly aluminum chloride impurities, with a mass content of thousands of ppm in terms of aluminum element. Under normal pressure conditions, the boiling point of aluminum chloride is 182.7°C, but it will sublime at 177.8°C. The sublimation temperature is very close to the distillation range of high-boiling products (120-180°C), so it is difficult to remove by common separation methods. The aluminum chloride metal impurities in the high-boiling products will react with the organic amines in the catalyst in the subsequent catalytic cracking step, resulting in a large amount of cracking catalyst loss. In order to ensure the catalytic effect, it is necessary to continuously replenish the lost catalyst, which increases the operating cost and seriously affects the stability of the production process.

[0004] At present, people have developed some methods to avoid the loss of catalysts caused by aluminum chloride impurities. For example, patent CN108658082A discloses a method for removing aluminum chloride by pre-treating high-boiling substances. The method is to send the high-boiling substances to a cooling and stirring tank, stir them at low temperature for 1-5 hours, send them to a sedimentation tank, and then let the high-boiling substances settle in a nitrogen environment for 1-20 hours, thereby separating the slurry including solid impurities and metal halides. However, the method has a long processing flow and the effect of removing aluminum chloride is not ideal; patent CN113149017A discloses a method for removing aluminum from high-boiling substances in polysilicon The complexing agent and its application are used, and the structure of the complexing agent is complex, which is difficult to be used in actual production; Patent CN105271246A discloses a method for removing aluminum chloride from high boiling points, which first adds an auxiliary agent and aluminum-containing impurities to the high boiling points to form a mixed system containing non-volatile aluminum compounds, and then separates the remaining components in the high boiling points from the mixed system by distillation, thereby removing the aluminum chloride impurity. However, the auxiliary agent used in this method is obtained by mixing "deferoxamine", "deferiprone" and "testiron" in a certain proportion, and its iron removal effect is relatively high, but the aluminum removal effect is not ideal, and the cost is also relatively high.

[0005] Therefore, developing a treatment agent that is low-cost and can efficiently remove metal impurities such as aluminum chloride in high-boiling products of polysilicon is an urgent problem to be solved in the art. Summary of the invention

[0006] In view of the defects existing in the prior art, the present invention provides a treatment agent for removing aluminum from high-boiling substances in polysilicon. The treatment agent is obtained by compounding a plurality of metal salts according to specific mass fractions, and has the advantages of good aluminum removal effect and low cost.

[0007] The present invention also provides a method for removing aluminum chloride impurities in polysilicon high boiling points. The method uses the above-mentioned treatment agent to treat the polysilicon high boiling points, which can effectively remove the aluminum chloride impurities in the polysilicon high boiling points, thereby avoiding the loss of catalysts in the subsequent cracking process.

[0008] The first aspect of the present invention provides a treatment agent for removing aluminum from high boiling points of polysilicon, which comprises the following components in parts by mass: 900-1000 parts of alkali metal chloride, 2-10 parts of alkaline earth metal chloride, and 1-5 parts of transition metal chloride.

[0009] The inventors have found that after the above-mentioned different types of metal chlorides are compounded according to specific mass fractions to obtain a polysilicon high-boiling material aluminum removal treatment agent and mixed with the polysilicon high-boiling material, a multi-component molten salt system can be formed with the metal aluminum chloride impurities in the high-boiling material. Unlike a single aluminum chloride that is easy to sublime within the distillation range of the high-boiling material, the phase change conditions of aluminum chloride in the multi-component molten salt system are changed, and it is not easy to sublime within the distillation range of the high-boiling material. Therefore, the difference in boiling points between aluminum chloride and the high-boiling material can be used to separate and remove aluminum chloride impurities in the high-boiling material, which greatly reduces the difficulty of separating aluminum trichloride in the high-boiling material, and the aluminum trichloride impurities in the high-boiling material can be efficiently removed by simple distillation.

[0010] The metal chlorides in the treatment agent for removing aluminum from high-boiling-point polysilicon of the present invention can be selected from cheap and readily available inorganic metal salts in the art. Therefore, compared with the organic complexing agents used in the prior art, the treatment agent has the advantages of low cost and high economic benefit.

[0011] Furthermore, when the treatment agent for removing aluminum from high-boiling-point products of polysilicon also includes 1 to 3 parts by mass of alkaline earth metal sulfate, the aluminum removal effect is more prominent.

[0012] The alkali metal chloride of the present invention is selected from one or more of lithium chloride, sodium chloride and potassium chloride, and more preferably sodium chloride and / or potassium chloride which are relatively cheap and easily available.

[0013] The alkaline earth metal chloride of the present invention is selected from one or more of calcium chloride, magnesium chloride, strontium chloride and barium chloride, more preferably calcium chloride and / or magnesium chloride.

[0014] The transition metal element in the transition metal element chloride of the present invention is selected from one or more of iron, manganese, chromium, nickel, molybdenum, titanium, zinc and cobalt.

[0015] The alkaline earth metal sulfate of the present invention is selected from one or more of calcium sulfate, magnesium sulfate, strontium sulfate and barium sulfate, and more preferably calcium sulfate and / or magnesium sulfate.

[0016] The second aspect of the present invention provides a method for removing aluminum chloride impurities from high-boiling polysilicon products, the method comprising: mixing the treatment agent for removing aluminum from high-boiling polysilicon products provided by the first aspect of the present invention with the high-boiling polysilicon products to obtain a mixed system; performing a distillation treatment on the mixed system, and collecting volatiles generated in the distillation treatment by condensation.

[0017] In the above method, the process of mixing the treatment agent for removing aluminum from high-boiling materials of polycrystalline silicon with the high-boiling materials of polycrystalline silicon is the process of fully mixing the metal salt in the treatment agent with the high-boiling materials of polycrystalline silicon to form a multi-component molten salt system; after obtaining the mixed system, the difference between the boiling range of the high-boiling materials and the boiling point of the aluminum chloride impurity in the multi-component molten salt system is utilized to separate them by distillation treatment, and finally the volatiles produced by the distillation treatment collected by condensation are the high-boiling materials of polycrystalline silicon with the aluminum chloride impurity removed.

[0018] Furthermore, when the mass ratio of the treatment agent for removing aluminum from high boiling points of polysilicon to the high boiling points of polysilicon is controlled to be 1:(25-100), preferably 1:(35-65), a better impurity removal effect can be obtained.

[0019] According to the difference in boiling points between aluminum chloride impurities and high-boiling substances in polysilicon, the temperature of the distillation process can be controlled to be 140°C to 180°C, preferably 152°C to 177°C.

[0020] The present invention has no particular limitation on the pressure of the distillation treatment, and there is no need to use harsh high pressure or negative pressure conditions. In a specific embodiment, the pressure of the distillation treatment is 0.1 MPa to 1.0 MPa, preferably controlled to be 0.1 MPa to 0.4 MPa.

[0021] The implementation of the present invention has at least the following advantages:

[0022] 1. The treatment agent for removing aluminum from high-boiling products of polysilicon of the present invention forms a multi-component molten salt system with aluminum chloride impurities in high-boiling products of polysilicon by compounding alkali metal chlorides, alkaline earth metal chlorides and transition metal element chlorides in specific mass fractions, so that the phase change conditions of aluminum chloride are changed, making it difficult for it to sublime within the distillation range of high-boiling products, thereby reducing the difficulty of separating aluminum chloride from high-boiling products, and the aluminum chloride impurities in high-boiling products can be efficiently separated through simple distillation operations.

[0023] 2. Compared with the organic complexing agents in the prior art, the raw materials of the polysilicon high-boiling-point aluminum removal treatment agent of the present invention come from cheaper and more readily available inorganic metal salt compounds, and therefore have the advantages of low cost and high economic benefits.

[0024] 3. The method for removing aluminum chloride impurities from high-boiling polysilicon provided by the present invention can achieve efficient separation of aluminum chloride impurities by simply distilling the mixed system of the above-mentioned polysilicon high-boiling aluminum removal treatment agent and the polysilicon high-boiling polysilicon. The method has the advantages of high efficiency, low cost and simple operation. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] The following will further describe in detail the treatment agent for removing aluminum from high boiling points of polysilicon and its application provided by the present invention in conjunction with specific embodiments.

[0027] In the following examples, unless otherwise specified, all raw materials can be obtained by commercial purchase or conventional methods.

[0028] In the following examples, the Al content of the high-boiling products of polysilicon to be treated and the condensed and collected distillates after treatment are determined according to the method given in Section 5.5. "Determination of iron, aluminum, chromium, titanium, copper, manganese, nickel, boron and phosphorus contents" of China Chemical Industry Standard HG / T 5745-2020, and the unit wppm refers to one part per million by mass.

[0029] Example 1

[0030] 1. The polysilicon high boiling point aluminum removal treatment agent of this embodiment is composed of the following raw materials in parts by mass: 960 parts of NaCl, 2 parts of KCl, 3 parts of CaCl2, 1 part of FeCl3 and 2 parts of CaSO4. The above raw materials are added to a ball mill and ball milled for 3 hours, and then put into a vibrating screen, and the polysilicon high boiling point aluminum removal treatment agent of this embodiment is prepared after being sieved through a 120-mesh stainless steel screen.

[0031] 2. This embodiment also provides a method for removing aluminum chloride impurities in polysilicon high boiling products, comprising the following steps:

[0032] 1) 1 g of the treatment agent for removing aluminum from the polycrystalline silicon high boiling point of this embodiment and 50 g of the polycrystalline silicon high boiling point to be treated (with an Al content of 851 wppm) were added to a reactor, the top outlet of the reactor was connected to a condenser via a back pressure valve, and stirring was turned on to fully mix the treatment agent for removing aluminum from the polycrystalline silicon high boiling point and the polycrystalline silicon high boiling point;

[0033] 2) Maintain stirring, and raise the temperature of the reactor to 155°C at a heating rate of 5°C / min and maintain it thereafter. The operating pressure is controlled at 0.2 MPa by a back pressure regulating valve. The volatile substances in the reactor are condensed by a condenser and collected in a container connected to the condenser.

[0034] 3) When no more volatile substances continue to condense and be produced, the heating is stopped and the biological residues in the reactor are discharged.

[0035] The Al content of the condensed and collected evaporation was measured to be 8wppm. Calculation showed that the aluminum removal rate of this embodiment (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated × 100%) was 99.1%.

[0036] Example 2

[0037] 1. The polysilicon high boiling point aluminum removal treatment agent of this embodiment is composed of the following raw materials in parts by mass: 900 parts of NaCl, 15 parts of KCl, 4 parts of CaCl2, 4 parts of MgCl2, 3 parts of FeCl3, 1 part of MnCl2 and 2 parts of CaSO4. The above raw materials are added to a ball mill and ball milled for 3 hours, and then put into a vibrating screen, and the polysilicon high boiling point aluminum removal treatment agent of this embodiment is prepared after being sieved through a 120-mesh stainless steel screen.

[0038] 2. This embodiment also provides a method for removing aluminum chloride impurities in polysilicon high boiling products, comprising the following steps:

[0039] 1) 1 g of the treatment agent for removing aluminum from the high boiling point of polysilicon of this embodiment and 65 g of the high boiling point of polysilicon to be treated (with an Al content of 851 wppm) were added to a reactor, the top outlet of the reactor was connected to a condenser via a back pressure valve, and stirring was turned on to fully mix the treatment agent for removing aluminum from the high boiling point of polysilicon with the high boiling point of polysilicon;

[0040] 2) Maintain stirring, and raise the temperature of the reactor to 177°C at a heating rate of 5°C / min and maintain it thereafter. The operating pressure is controlled at 0.3 MPa by a back pressure regulating valve. The volatile substances in the reactor are condensed by a condenser and collected in a container connected to the condenser.

[0041] 3) When no more volatile substances continue to condense and be produced, the heating is stopped and the biological residues in the reactor are discharged.

[0042] The Al content of the condensed and collected evaporation was measured to be 16wppm. Calculation shows that the aluminum removal rate of this embodiment (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated × 100%) is 98.1%.

[0043] Example 3

[0044] 1. The polysilicon high boiling point aluminum removal treatment agent of this embodiment is composed of the following raw materials in parts by mass: 800 parts of NaCl, 150 parts of KCl, 8 parts of MgCl2, 3 parts of FeCl3, 2 parts of MnCl2 and 3 parts of MgSO4. The above raw materials are added to a ball mill and ball milled for 3 hours, and then put into a vibrating screen, and the polysilicon high boiling point aluminum removal treatment agent of this embodiment is prepared after being sieved through a 120-mesh stainless steel screen.

[0045] 2. This embodiment also provides a method for removing aluminum chloride impurities in polysilicon high boiling products, comprising the following steps:

[0046] 1) 1 g of the treatment agent for removing aluminum from the polycrystalline silicon high boiling point of this embodiment and 35 g of the polycrystalline silicon high boiling point to be treated (with an Al content of 1133 wppm) were added to a reactor, the top outlet of the reactor was connected to a condenser via a back pressure valve, and stirring was turned on to fully mix the treatment agent for removing aluminum from the polycrystalline silicon high boiling point and the polycrystalline silicon high boiling point;

[0047] 2) Maintain stirring, and raise the temperature of the reactor to 152°C at a heating rate of 5°C / min and maintain the temperature thereafter. The operating pressure is controlled at 0.15 MPa by a back pressure regulating valve. The volatile substances in the reactor are condensed by a condenser and collected in a container connected to the condenser.

[0048] 3) When no more volatile substances continue to condense and be produced, the heating is stopped and the biological residues in the reactor are discharged.

[0049] The Al content of the condensed and collected evaporation was measured to be 13wppm. Calculation shows that the aluminum removal rate of this embodiment (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated × 100%) is 98.9%.

[0050] Example 4

[0051] 1. The polysilicon high boiling point aluminum removal treatment agent of this embodiment is composed of the following raw materials in parts by mass: 970 parts of NaCl, 5 parts of KCl, 5 parts of CaCl2, 5 parts of MgCl2, 5 parts of FeCl3 and 3 parts of CaSO4. The above raw materials are added to a ball mill and ball milled for 3 hours, and then put into a vibrating screen, and the polysilicon high boiling point aluminum removal treatment agent of this embodiment is prepared after being sieved through a 120-mesh stainless steel screen.

[0052] 2. This embodiment also provides a method for removing aluminum chloride impurities in polysilicon high boiling products, comprising the following steps:

[0053] 1) 1 g of the treatment agent for removing aluminum from high boiling points of polysilicon of this embodiment and 100 g of the high boiling points of polysilicon to be treated (with an Al content of 1006 wppm) were added to a reactor, the top outlet of the reactor was connected to a condenser via a back pressure valve, stirring was turned on, and the treatment agent for removing aluminum from high boiling points of polysilicon and the high boiling points of polysilicon were fully mixed;

[0054] 2) Maintain stirring, and raise the temperature of the reactor to 180°C at a heating rate of 5°C / min and maintain it thereafter. The operating pressure is controlled at 0.4 MPa by a back pressure regulating valve. The volatile substances in the reactor are condensed by a condenser and collected in a container connected to the condenser.

[0055] 3) When no more volatile substances continue to condense and be produced, the heating is stopped and the biological residues in the reactor are discharged.

[0056] The Al content of the condensed and collected evaporation was measured to be 25wppm. Calculation showed that the aluminum removal rate of this embodiment (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated × 100%) was 97.5%.

[0057] Example 5

[0058] 1. The polysilicon high boiling point aluminum removal treatment agent of this embodiment is composed of the following raw materials in terms of mass fractions: 960 parts of NaCl, 2 parts of KCl, 3 parts of CaCl2 and 1 part of FeCl3. The above raw materials are added to a ball mill and ball milled for 3 hours, and then put into a vibrating screen, and the polysilicon high boiling point aluminum removal treatment agent of this embodiment is prepared after being sieved through a 120-mesh stainless steel screen.

[0059] 2. This embodiment also provides a method for removing aluminum chloride impurities in polysilicon high boiling products, comprising the following steps:

[0060] 1) 1 g of the treatment agent for removing aluminum from the polycrystalline silicon high boiling point of this embodiment and 50 g of the polycrystalline silicon high boiling point to be treated (with an Al content of 1057 wppm) were added to a reactor, the top outlet of the reactor was connected to a condenser via a back pressure valve, and stirring was turned on to fully mix the treatment agent for removing aluminum from the polycrystalline silicon high boiling point and the polycrystalline silicon high boiling point;

[0061] 2) Maintain stirring, and raise the temperature of the reactor to 155°C at a heating rate of 5°C / min and maintain it thereafter. The operating pressure is controlled at 0.2 MPa by a back pressure regulating valve. The volatile substances in the reactor are condensed by a condenser and collected in a container connected to the condenser.

[0062] 3) When no more volatile substances continue to condense and be produced, the heating is stopped and the biological residues in the reactor are discharged.

[0063] The Al content of the condensed and collected evaporation was measured to be 71wppm. Calculation shows that the aluminum removal rate of this embodiment (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated × 100%) is 93.3%.

[0064] Example 6

[0065] The difference between this embodiment and embodiment 1 is that the Al content of the high boiling point product of the polysilicon to be treated is 497wppm. After treatment, the Al content of the evaporated product is measured by sampling and is 3.1wppm. Through calculation, it can be known that the aluminum removal rate of this embodiment (aluminum removal rate = 1-Al content of the evaporated product collected by condensation / Al content in the high boiling point product of the polysilicon to be treated × 100%) is 99.4%.

[0066] Comparative Example 1

[0067] The method for removing aluminum chloride impurities in polysilicon high boiling products in this comparative example comprises the following steps:

[0068] 1) 50 g of polysilicon high boiling point product to be treated (Al content of 1057 wppm) was added into the reactor, the top outlet of the reactor was connected to the condenser via a back pressure valve, and stirring was started;

[0069] 2) Maintain stirring, and raise the temperature of the reactor to 155°C at a heating rate of 5°C / min and maintain it thereafter. The operating pressure is controlled at 0.2 MPa by a back pressure regulating valve. The volatile substances in the reactor are condensed by a condenser and collected in a container connected to the condenser.

[0070] 3) When no more volatile substances continue to condense and be produced, the heating is stopped and the biological residues in the reactor are discharged.

[0071] The Al content of the condensed and collected evaporation was measured to be 1019wppm. Calculation showed that the aluminum removal rate of this comparative example (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated × 100%) was 3.6%.

[0072] Comparative Example 2

[0073] 1. In this comparative example, 1 g ZnCl2 was added into a ball mill and milled for 3 hours, and then put into a vibrating screen. After being sieved through a 120-mesh stainless steel screen, a treatment agent for removing aluminum from high-boiling substances in polysilicon was prepared.

[0074] 2. This comparative example also provides a method for removing aluminum chloride impurities in high boiling products of polysilicon, comprising the following steps:

[0075] 1) 1 g of the treatment agent for removing aluminum from the polycrystalline silicon high boiling point of this comparative example and 50 g of the polycrystalline silicon high boiling point to be treated (with an Al content of 1057 wppm) were added to a reactor, the top outlet of the reactor was connected to a condenser via a back pressure valve, and stirring was turned on to fully mix the treatment agent for removing aluminum from the polycrystalline silicon high boiling point and the polycrystalline silicon high boiling point;

[0076] 2) Maintain stirring, and raise the temperature of the reactor to 155°C at a heating rate of 5°C / min and maintain it thereafter. The operating pressure is controlled at 0.2 MPa by a back pressure regulating valve. The volatile substances in the reactor are condensed by a condenser and collected in a container connected to the condenser.

[0077] 3) When no more volatile substances continue to condense and be produced, the heating is stopped and the biological residues in the reactor are discharged.

[0078] The Al content of the condensed and collected evaporation was measured to be 520wppm. Calculation shows that the aluminum removal rate of this embodiment (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated × 100%) is 50.8%.

[0079] Comparative Example 3

[0080] 1. In this comparative example, 1 g of CuCl2 was added into a ball mill and milled for 3 hours, and then put into a vibrating screen. After being sieved through a 120-mesh stainless steel screen, a treatment agent for removing aluminum from high-boiling materials in polysilicon was prepared.

[0081] 2. This comparative example also provides a method for removing aluminum chloride impurities in high-boiling materials of polysilicon. The specific steps are basically the same as those of comparative example 2, except that the treatment agent for removing aluminum from high-boiling materials of polysilicon is replaced by the treatment agent for removing aluminum from high-boiling materials of polysilicon of this comparative example.

[0082] The Al content of the sample collected by condensation in this comparative example was 457wppm. Through calculation, it can be known that the aluminum removal rate of this comparative example (aluminum removal rate = 1-Al content of the condensed and collected vapor / Al content in the polysilicon high boiling product to be treated × 100%) is 56.8%.

[0083] Comparative Example 4

[0084] 1. In this comparative example, 0.5 g of deferoxamine (CAS No.: 70-51-9) and 0.5 g of deferiprone (CAS No.: 30621-11-0) were mixed and added to a ball mill for ball milling for 3 hours, and then put into a vibrating screen. After screening through a 120-mesh stainless steel screen, a polysilicon high-boiling aluminum removal treatment agent was prepared.

[0085] 2. This comparative example also provides a method for removing aluminum chloride impurities in high-boiling materials of polysilicon. The specific steps are basically the same as those of comparative example 2, except that the treatment agent for removing aluminum from high-boiling materials of polysilicon is replaced by the treatment agent for removing aluminum from high-boiling materials of polysilicon of this comparative example.

[0086] The Al content of the condensed and collected evaporation sample of this comparative example was 269wppm. Through calculation, it can be known that the aluminum removal rate of this comparative example (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated×100%) is 74.6%.

[0087] Comparative Example 5

[0088] 1. In this comparative example, 1 g of NaCl was added into a ball mill and milled for 3 hours, and then put into a vibrating screen. After being sieved through a 120-mesh stainless steel screen, a treatment agent for removing aluminum from high-boiling substances in polysilicon was prepared.

[0089] 2. This comparative example also provides a method for removing aluminum chloride impurities in high-boiling materials of polysilicon. The specific steps are basically the same as those of comparative example 2, except that the treatment agent for removing aluminum from high-boiling materials of polysilicon is replaced by the treatment agent for removing aluminum from high-boiling materials of polysilicon of this comparative example.

[0090] The Al content of the condensed and collected evaporation sample of this comparative example was 152wppm. Through calculation, it can be known that the aluminum removal rate of this comparative example (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated×100%) is 85.6%.

[0091] Comparative Example 6

[0092] 1. In this comparative example, 1 g of CaCl2 was added into a ball mill and milled for 3 hours, and then put into a vibrating screen. After being sieved through a 120-mesh stainless steel screen, a treatment agent for removing aluminum from high-boiling substances in polysilicon was prepared.

[0093] 2. This comparative example also provides a method for removing aluminum chloride impurities in high-boiling materials of polysilicon. The specific steps are basically the same as those of comparative example 2, except that the treatment agent for removing aluminum from high-boiling materials of polysilicon is replaced by the treatment agent for removing aluminum from high-boiling materials of polysilicon of this comparative example.

[0094] The Al content of the condensed and collected evaporation sample of this comparative example was 1014wppm. Through calculation, it can be known that the aluminum removal rate of this comparative example (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated×100%) is 4.1%.

[0095] Comparative Example 7

[0096] 1. In this comparative example, 1 g of FeCl3 was added into a ball mill and milled for 3 hours, and then put into a vibrating screen. After being sieved through a 120-mesh stainless steel screen, a treatment agent for removing aluminum from high-boiling substances in polysilicon was prepared.

[0097] 2. This comparative example also provides a method for removing aluminum chloride impurities in high-boiling materials of polysilicon. The specific steps are basically the same as those of comparative example 2, except that the treatment agent for removing aluminum from high-boiling materials of polysilicon is replaced by the treatment agent for removing aluminum from high-boiling materials of polysilicon of this comparative example.

[0098] The Al content of the condensed and collected evaporation sample of this comparative example was 1020wppm. Through calculation, it can be known that the aluminum removal rate of this comparative example (aluminum removal rate = 1-Al content of the condensed and collected evaporation / Al content in the polysilicon high boiling product to be treated×100%) is 3.5%.

[0099] The following conclusions can be drawn from the data of the above embodiments and comparative examples:

[0100] 1. It can be seen from the data of Examples 1 to 6 that the treatment agent for removing aluminum from high-boiling-point polysilicon of the present invention can effectively remove aluminum chloride impurities in high-boiling-point polysilicon, and the aluminum removal rate can basically reach more than 90%.

[0101] 2. According to the comparison between Example 1 and Comparative Example 1, it can be seen that without adding any treating agent, it is basically impossible to remove the aluminum chloride impurity in the high boiling point by relying solely on the distillation operation, and the aluminum removal rate is only 3.6%.

[0102] 3. According to the comparison between Example 1 and Comparative Examples 2 to 3 and Comparative Examples 5 to 7, it can be seen that the aluminum removal effects of using single alkali metal chlorides, alkaline earth metal chlorides and transition metal chlorides as treatment agents are poor, especially using single calcium chloride and ferric chloride as treatment agents has almost no aluminum removal effect.

[0103] 4. According to the comparison between Example 1 and Comparative Example 4, it can be seen that although the use of a mixture of deferoxamine and deferiprone as a treatment agent to treat polysilicon high boiling points has a good aluminum removal effect, it is still obviously inferior to the aluminum removal effect of the treatment agent of the present invention, and the reagents of deferoxamine and deferiprone are relatively expensive, resulting in high aluminum removal costs.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A treatment agent for removing aluminum from high boiling points of polysilicon, characterized in that: The composition comprises the following components in parts by mass: 900-1000 parts of alkali metal chloride, 2-10 parts of alkaline earth metal chloride, 1-5 parts of transition metal chloride and 1-3 parts of alkaline earth metal sulfate; The alkali metal chloride is selected from one or more of lithium chloride, sodium chloride and potassium chloride; The alkaline earth metal chloride is selected from one or more of calcium chloride, magnesium chloride, strontium chloride and barium chloride; The transition metal element in the transition metal chloride is selected from one or more of iron, manganese, chromium, nickel, molybdenum, titanium, zinc and cobalt; The alkaline earth metal sulfate is selected from one or more of calcium sulfate, magnesium sulfate, strontium sulfate and barium sulfate.

2. A method for removing aluminum chloride impurities from high boiling products of polysilicon, characterized in that: include: The polysilicon high boiling point aluminum removal treatment agent according to claim 1 is mixed with the polysilicon high boiling point to obtain a mixed system; the mixed system is subjected to a distillation treatment, and the volatiles generated in the distillation treatment are collected by condensation.

3. The method according to claim 2, characterized in that The mass ratio of the treatment agent for removing aluminum from the polysilicon high boiling point to the polysilicon high boiling point is 1: (25-100).

4. The method according to claim 2 or 3, characterized in that: The temperature of the distillation treatment is 140°C to 180°C.

5. The method according to claim 4, characterized in that The pressure of the distillation treatment is 0.1 MPa ~1.0 MPa.