WO2010089803A1 - Process for producing solar battery from waste salt and sand in desert - Google Patents

Process for producing solar battery from waste salt and sand in desert Download PDF

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WO2010089803A1
WO2010089803A1 PCT/JP2009/000489 JP2009000489W WO2010089803A1 WO 2010089803 A1 WO2010089803 A1 WO 2010089803A1 JP 2009000489 W JP2009000489 W JP 2009000489W WO 2010089803 A1 WO2010089803 A1 WO 2010089803A1
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sio
solar cell
waste salt
solar
desert
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鈴木文雄
高橋一平
佐々木耕司
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アーベル・システムズ株式会社
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Priority to PCT/JP2009/002439 priority patent/WO2010089812A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L31/00—Semiconductor devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation and specially adapted either for the conversion of the energy of such radiation into electrical energy or for the control of electrical energy by such radiation; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L31/18—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
    • H01L31/1804—Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof comprising only elements of Group IV of the Periodic System
    • H01L31/182—Special manufacturing methods for polycrystalline Si, e.g. Si ribbon, poly Si ingots, thin films of polycrystalline Si
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/021—Preparation
    • C01B33/023—Preparation by reduction of silica or free silica-containing material
    • C01B33/025—Preparation by reduction of silica or free silica-containing material with carbon or a solid carbonaceous material, i.e. carbo-thermal process
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/02—Silicon
    • C01B33/037—Purification
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/546—Polycrystalline silicon PV cells
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
    • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

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  • the present invention relates to a method of manufacturing a solar cell using as raw materials a salt remaining after fresh water is removed from seawater in order to obtain fresh water from seawater and sand existing in a large amount in a desert.
  • the present invention was developed for the purpose of realizing the above.
  • An important object of the present invention is to effectively use waste salt generated in large quantities due to desalination in the desert region, and further to produce solar grade silicon from almost infinite sand as a raw material. It is to provide a method for manufacturing solar cells from waste salt and desert sand, which realizes an ideal environment by producing electricity and effectively generating power in a desert with little rain.
  • the method for producing a solar cell from waste salt and desert sand according to claim 1 of the present invention includes an electrolysis step of obtaining NaOH from Na obtained by electrolyzing NaCl of waste salt separated from fresh water from seawater; NaOH obtained in this electrolysis process and desert sand containing SiO 2 are reacted as shown by the formula (1) to form Na 2 SiO 3, and this Na 2 SiO 3 and waste salts are electrolyzed.
  • a sol-gel process in which the resulting HCl is reacted to form H 2 SiO 3 as shown by the formula (2), and the resulting H 2 SiO 3 is fired to increase the purity of SiO 2 ;
  • SiO 2 + 2NaOH ⁇ Na 2 SiO 3 + H 2 O (2) Na 2 SiO 3 + 2HCl ⁇ H 2 SiO 3 + 2NaCl
  • a carbon reduction step in which SiO 2 concentrated in the above sol-gel step is reduced with C as shown by the formula (3) to form high-purity metal silicon; (3) SiO 2 + C ⁇ Si + CO 2
  • the metal silicon obtained in this carbon reduction process is irradiated with an electron beam in vacuum to evaporate and remove impurities, and further oxidized to remove impurities to obtain solar grade silicon,
  • the method for producing a solar cell from waste salt and desert sand according to claim 2 of the present invention includes an electrolysis step of obtaining NaOH from Na obtained by electrolyzing NaCl of waste salt separated from fresh water from seawater; NaOH obtained in this electrolysis process and desert sand containing SiO 2 are reacted as shown by the formula (1) to form Na 2 SiO 3, and this Na 2 SiO 3 and waste salts are electrolyzed.
  • a sol-gel process in which the resulting HCl is reacted to form H 2 SiO 3 as shown by the formula (2), and the resulting H 2 SiO 3 is fired to increase the purity of SiO 2 ;
  • SiO 2 + 2NaOH ⁇ Na 2 SiO 3 + H 2 O (2) Na 2 SiO 3 + 2HCl ⁇ H 2 SiO 3 + 2NaCl
  • a carbon reduction step in which SiO 2 concentrated in the above sol-gel step is reduced with C as shown by the formula (3) to form high-purity metal silicon; (3) SiO 2 + C ⁇ Si + CO 2
  • the metal silicon obtained in the above carbon reduction process is reacted with chlorine to form gaseous silicon tetrachloride, which is distilled to obtain solar grade silicon.
  • a purification process (4) Si + Cl 2 ⁇ SiCl 4 (5) SiCl 4 + 2H 2 ⁇ Si + 4HCl
  • a method for producing a solar cell from waste salt and desert sand comprising a solar cell production step for producing a solar cell from solar grade silicon obtained by the above purification process.
  • the above-mentioned method for producing solar cells from waste salt and desert sand effectively utilizes waste salt generated in large quantities due to desalination in the desert region, and further uses sand that exists almost infinitely in the desert region.
  • Solar grade silicon can be manufactured as a raw material, solar cells can be manufactured, and an ideal environment can be realized by effectively generating power in a desert with little rain.
  • the desert sand containing NaOH and SiO 2 obtained in the electrolysis step is represented by the formula (1) in the sol-gel process.
  • sodium silicate (1) SiO 2 + 2NaOH ⁇ Na 2 SiO 3 + H 2 O
  • a glass production process for producing glass by mixing the obtained sodium silicate into silica A solar cell can be manufactured from a solar cell manufacturing process in which a solar cell layer is provided on the surface of the glass obtained in the glass manufacturing process using solar grade silicon.
  • the method of manufacturing solar cells from the above waste salt and desert sand is to produce glass from waste salt generated in large quantities due to desalination in the desert region and sand that is almost infinite in the desert region. Since this glass is used to manufacture solar cells, waste salt and sand are used to manufacture both solar grade silicon and glass, and these are used to manufacture solar cells. A solar cell can be manufactured using both salt and sand effectively.
  • FIG. 1 is a process diagram showing a method for producing a solar cell from waste salt and desert sand.
  • Solar grade silicon is produced from waste salt and sand by the following electrolysis process, sol-gel process, carbon reduction process, and metallurgical process, and a solar cell is produced using the solar grade silicon.
  • this step is a step of electrolyzing NaCl, which is a waste salt separated from fresh water from seawater, to separate Na, and reacting this Na with water to obtain NaOH.
  • NaCl can be converted to metallic sodium by molten salt electrolysis.
  • molten salt electrolysis NaCl is heated and melted, and this is electrolyzed to separate Na.
  • a flux is added to lower the melting point of NaCl.
  • CaCl 2 can be used as the flux.
  • the melting point of NaCl is about 800 ° C., the melting point can be lowered to about 500 ° C. by adding CaCl 2 to NaCl at a molar ratio of 54:46.
  • NaCl and CaCl 2 are mixed and heated to be dissolved, and a positive electrode 11 and a negative electrode 12 are arranged on this to be electrolyzed.
  • molten salt electrolysis Na is generated on the negative electrode 12 and chlorine is generated on the positive electrode 11.
  • a diaphragm (not shown) is provided between the electrodes so that the produced Na and chlorine do not react.
  • the positive electrode 11 uses carbon
  • the negative electrode 12 uses a metal such as tungsten, stainless steel, or molybdenum.
  • An inert gas is supplied to the negative electrode 12 to prevent the produced Na from reacting with oxygen in the air.
  • the positive electrode 11 and the negative electrode 12 are electrolyzed by applying a DC voltage of 7V.
  • Metal Na obtained in the above steps is reacted with water to become NaOH, and reacted with oxygen to become Na 2 O.
  • Chlorine reacts with water to become HCl.
  • reaction (1) sand pulverized in powder form is suspended in an aqueous solution of NaOH to form a sol, and SiO 2 in the sand is dissolved in NaOH to form Na 2 SiO 3 .
  • impurities such as MgO, S (CuS), Ca (CaCO 3 ), Al (AlO), NiO, Ag, Au, and Cu are precipitated and removed.
  • the produced Na 2 SiO 3 is hydrolyzed to obtain a water glass composed of gel-like H 2 SiO 3 .
  • HCl is added to the gel water glass and reacted as shown in (2) to form H 2 SiO 3 .
  • impurity NaCl is precipitated and removed.
  • the produced H 2 SiO 3 is fired to evaporate moisture, and the purity of SiO 2 is increased to 99%.
  • the SiO 2 powder and the carbon powder are mixed by the mixer 22 so as to have a molar ratio of 1: 1 to 1: 2, and supplied from the hopper 23 to the arc furnace 20 of the carbon electrode 21.
  • the arc furnace 20 arc-discharges the carbon electrode 21 to heat and reduce the supplied SiO 2 and carbon.
  • the arc furnace 20 shown in the drawing is heated by a burner 24 from below.
  • the SiO 2 and carbon supplied to the arc furnace 20 react as shown by the equation (3) to produce metal silicon having a purity of 99.9%. Slag is separated on the generated metal silicon. Nitrogen and sulfur are removed in this process.
  • the generated carbon dioxide gas is discharged from the arc furnace 20.
  • SiO 2 and carbon are discharged from the arc furnace 20 together with carbon dioxide, partly as carbon monoxide.
  • the metal silicon obtained in the above carbon reduction process is supplied to the melting furnace 30 in a vacuum, and is irradiated with an electron beam from the electron beam device 31 to be liquid impurities by the electron beam. Is removed by evaporation.
  • the metal silicon from which impurities have been removed is discharged to the unidirectional solidification crucible 32 and solidified.
  • the solidified metal silicon is further oxidized by supplying hydrogen and oxygen in an inert gas argon to burn and oxidize the metal silicon. In this step, polycrystalline solar grade silicon having a purity of 99.9999% is obtained.
  • a solar cell is manufactured as follows, as conventionally performed. Melt polycrystalline solar grade silicon, drop seed crystal, pull it up and rotate it to grow into a single crystal to form a cylindrical ingot, and slice this ingot thinly from 0.3mm to 0.4mm A single crystal cell is manufactured.
  • polycrystalline solar grade silicon can be produced by slicing this ingot thinly by making the ingot solidified in a polycrystalline state without making it a single crystal.
  • Phosphorus is diffused from one side of the single crystal cell or polycrystalline cell manufactured as described above to form a pn junction, and electrodes are provided on both sides to form a solar cell.
  • the electrode transmits sunlight through one side as a transparent electrode. Sun rays that pass through the transparent electrode are incident on a silicon pn junction to generate an electromotive force.
  • solar grade silicon is manufactured by an electrolysis process, a sol-gel process, a carbon reduction process, and a metallurgical process.
  • solar grade silicon can be produced by an electrolysis process, a sol-gel process, a carbon reduction process, and a purification process using the metallurgical process as the following purification process.
  • a solar cell can be manufactured by the solar cell manufacturing process described above.
  • a glass can be manufactured from waste salt and desert sand, and a solar cell can be manufactured using this glass.
  • This manufacturing method manufactures glass by the glass manufacturing process shown below, and manufactures a solar cell by a solar cell manufacturing process using the manufactured glass.
  • silica As a raw material for glass. That is, SiO 2 contained in desert sand is used as a raw material for glass, and sodium carbonate produced from NaO obtained by oxidizing Na obtained in the electrolysis process is used. Silica and sodium carbonate are mixed at a predetermined ratio, and this mixture is fired to produce glass.
  • the solar cell layer is manufactured by using the polycrystalline solar grade silicon obtained in the metallurgical process or the refining process described above on the surface of the glass obtained in the glass manufacturing process.
  • a solar cell is manufactured.
  • the waste salt can be used for power generation by making CaMnO 3 from the contained calcium and using the temperature difference as a thermoelectric material.
  • This thermoelectric material can reduce the electrical resistance by increasing the amount of yttrium substitution.
  • a thermoelectric material made of CaMnO 3 is suitable for power generation by effectively utilizing high-temperature waste heat in the process of distilling seawater because it is excellent in high-temperature stability. It can also be used for power generation using the temperature difference between high temperature and sea water under hot weather in the desert.
  • the present invention effectively utilizes a large amount of waste salt generated by separating fresh water from seawater in order to obtain fresh water in the desert region, and further manufactures solar cells using sand existing in a large amount in the desert as a raw material. By using solar cells effectively, energy can be used extremely effectively as a total.

Abstract

Disclosed is a process for producing a solar battery that uses a waste salt, which is produced in a large quantity in a desert area, and sand in a desert as raw materials to produce solar-grade silicon. The process for producing a solar battery from a waste salt and sand in a desert comprises an electrolysis step of electrolyzing NaCl as a waste salt after the separation of fresh water from seawater to give Na and obtaining NaOH from Na, a sol-gel step of reacting NaOH with sand in a desert to give Na2SiO3, reacting Na2SiO3 with HCl to give H2SiO3, and firing H2SiO3 to enhance the purity of SiO2, a carbon reduction step of reducing SiO2 concentrated in the sol-gel step with C to give high-purity metal silicon, a metallurgical step of applying electron beams to the metal silicon in vacuo to remove impurities by evaporation and further performing oxidation to remove impurities to obtain solar-grade silicon, and a solar battery production step of producing a solar battery from the solar-grade silicon.

Description

廃棄塩と砂漠の砂から太陽電池を製造する方法Method for manufacturing solar cells from waste salt and desert sand
　本発明は、海水から真水を得るために海水から淡水が除去されて残る塩と、砂漠に多量に存在する砂とを原料として太陽電池を製造する方法に関する。 The present invention relates to a method of manufacturing a solar cell using as raw materials a salt remaining after fresh water is removed from seawater in order to obtain fresh water from seawater and sand existing in a large amount in a desert.
　砂漠地帯で真水を得るために、海水を蒸留して淡水を分離する方法、または海水を逆浸透膜に透過させて淡水を分離する方法が実用化されている。これらの方法は、砂漠地方で現実に利用されて、多量の淡水を製造している。ところが、これらの方法は、淡水を分離すると多量の塩が発生する。海水には、約３重量％の塩が含まれるので、淡水の３％の塩が発生する。多量に発生する塩は有効な用途がなく、また、海水に投棄することもできない。海水の塩分濃度が異常に高くなるからである。 In order to obtain fresh water in a desert area, a method of separating fresh water by distilling seawater or a method of separating fresh water by permeating seawater through a reverse osmosis membrane has been put into practical use. These methods are actually used in desert areas to produce large quantities of fresh water. However, these methods generate a large amount of salt when fresh water is separated. Since the seawater contains about 3% by weight of salt, 3% of freshwater salt is generated. Large amounts of salt do not have an effective use and cannot be dumped into seawater. This is because the salinity of seawater becomes abnormally high.
　また、淡水化装置が利用されるのは砂漠地方であるから、多量の砂がある。さらにまた、砂漠地方は降水量が極端に少ないことから晴天が多く、太陽電池を利用して効率よく発電できる。ところで、ポリシリコンから太陽電池を製造する方法はすでに実用化されている（特許文献１及び２参照）。したがって、淡水化によって発生している膨大な量の廃棄塩と、砂漠に無限に存在する砂から太陽電池の原料として使用されるポリシリコンが製造できるなら、廃棄塩を有効利用しながら太陽電池を製造することができ、製造された太陽電池で有効に発電できる理想的な環境が実現できる。
特開２００８－２８２９２１号公報 特開平９－６９６４３号公報 Since the desalination equipment is used in the desert region, there is a large amount of sand. Furthermore, the desert region has a lot of fine weather due to extremely low precipitation, and can efficiently generate power using solar cells. By the way, a method of manufacturing a solar cell from polysilicon has already been put into practical use (see Patent Documents 1 and 2). Therefore, if polysilicon that is used as a raw material for solar cells can be produced from the enormous amount of waste salt generated by desalination and sand that is infinitely present in the desert, solar cells can be used while effectively using the waste salt. An ideal environment that can be manufactured and that can effectively generate power with the manufactured solar cell can be realized.
JP 2008-282922 A Japanese Patent Laid-Open No. 9-69643
　本発明は、以上のことを実現することを目的に開発されたものである。本発明の重要な目的は、砂漠地方での淡水化によって多量に発生している廃棄塩を有効に利用し、さらに、ほとんど無限に存在する砂を原料としてソーラーグレードシリコンを製造して、太陽電池を製造し、雨の少ない砂漠で有効に発電することで理想的な環境を実現する廃棄塩と砂漠の砂から太陽電池を製造する方法を提供することにある。 The present invention was developed for the purpose of realizing the above. An important object of the present invention is to effectively use waste salt generated in large quantities due to desalination in the desert region, and further to produce solar grade silicon from almost infinite sand as a raw material. It is to provide a method for manufacturing solar cells from waste salt and desert sand, which realizes an ideal environment by producing electricity and effectively generating power in a desert with little rain.
課題を解決するための手段及び発明の効果Means for Solving the Problems and Effects of the Invention
　本発明の請求項１の廃棄塩と砂漠の砂から太陽電池を製造する方法は、海水から淡水の分離された廃棄塩のＮａＣｌを電気分解して得られるＮａからＮａＯＨを得る電気分解工程と、
　この電気分解工程で得られるＮａＯＨとＳｉＯ２を含む砂漠の砂とを(1)の式で示すように反応させてＮａ２ＳｉＯ３とし、さらに、このＮａ２ＳｉＯ３と、廃棄塩を電気分解して得られるＨＣｌとを反応させて(2)の式で示すようにＨ２ＳｉＯ３とし、得られたＨ２ＳｉＯ３を焼成してＳｉＯ２の純度を高くするゾル・ゲル工程と、
　(1)　ＳｉＯ２＋２ＮａＯＨ→Ｎａ２ＳｉＯ３＋Ｈ２Ｏ
　(2)　Ｎａ２ＳｉＯ３＋２ＨＣｌ→Ｈ２ＳｉＯ３＋２ＮａＣｌ
　以上のゾル・ゲル工程で濃縮されたＳｉＯ２を(3)の式で示すようにＣで還元して純度の高いメタルシリコンとする炭素還元工程と、
　(3)　ＳｉＯ２＋Ｃ→Ｓｉ＋ＣＯ２
　この炭素還元工程で得られたメタルシリコンを真空中で電子ビーム照射して不純物を蒸発除去すると共に、さらに酸化して不純物を除去してソーラーグレードシリコンを得る冶金工程と、
　この冶金工程で得られるソーラーグレードシリコンから太陽電池を製造する太陽電池製造工程とからなる。 The method for producing a solar cell from waste salt and desert sand according to claim 1 of the present invention includes an electrolysis step of obtaining NaOH from Na obtained by electrolyzing NaCl of waste salt separated from fresh water from seawater;
NaOH obtained in this electrolysis process and desert sand containing SiO 2 are reacted as shown by the formula (1) to form Na 2 SiO 3, and this Na 2 SiO 3 and waste salts are electrolyzed. A sol-gel process in which the resulting HCl is reacted to form H 2 SiO 3 as shown by the formula (2), and the resulting H 2 SiO 3 is fired to increase the purity of SiO 2 ;
(1) SiO 2 + 2NaOH → Na 2 SiO 3 + H 2 O
(2) Na 2 SiO 3 + 2HCl → H 2 SiO 3 + 2NaCl
A carbon reduction step in which SiO 2 concentrated in the above sol-gel step is reduced with C as shown by the formula (3) to form high-purity metal silicon;
(3) SiO 2 + C → Si + CO 2
The metal silicon obtained in this carbon reduction process is irradiated with an electron beam in vacuum to evaporate and remove impurities, and further oxidized to remove impurities to obtain solar grade silicon,
A solar cell manufacturing process for manufacturing a solar cell from solar grade silicon obtained in this metallurgical process.
　本発明の請求項２の廃棄塩と砂漠の砂から太陽電池を製造する方法は、海水から淡水の分離された廃棄塩のＮａＣｌを電気分解して得られるＮａからＮａＯＨを得る電気分解工程と、
　この電気分解工程で得られるＮａＯＨとＳｉＯ２を含む砂漠の砂とを(1)の式で示すように反応させてＮａ２ＳｉＯ３とし、さらに、このＮａ２ＳｉＯ３と、廃棄塩を電気分解して得られるＨＣｌとを反応させて(2)の式で示すようにＨ２ＳｉＯ３とし、得られたＨ２ＳｉＯ３を焼成してＳｉＯ２の純度を高くするゾル・ゲル工程と、
　(1)　ＳｉＯ２＋２ＮａＯＨ→Ｎａ２ＳｉＯ３＋Ｈ２Ｏ
　(2)　Ｎａ２ＳｉＯ３＋２ＨＣｌ→Ｈ２ＳｉＯ３＋２ＮａＣｌ
　以上のゾル・ゲル工程で濃縮されたＳｉＯ２を(3)の式で示すようにＣで還元して純度の高いメタルシリコンとする炭素還元工程と、
　(3)　ＳｉＯ２＋Ｃ→Ｓｉ＋ＣＯ２
　以上の炭素還元工程で得られたメタルシリコンを、以下の(4)と(5)式で示すように、塩素と反応させガス状の四塩化ケイ素とし、これを蒸留してソーラーグレードシリコンを得る精製工程と、
　(4)　Ｓｉ＋Ｃｌ２→ＳｉＣｌ４
　(5)　ＳｉＣｌ４＋２Ｈ２→Ｓｉ＋４ＨＣｌ　
　以上の精製工程で得られるソーラーグレードシリコンから太陽電池を製造する太陽電池製造工程とからなる廃棄塩と砂漠の砂から太陽電池を製造する方法。 The method for producing a solar cell from waste salt and desert sand according to claim 2 of the present invention includes an electrolysis step of obtaining NaOH from Na obtained by electrolyzing NaCl of waste salt separated from fresh water from seawater;
NaOH obtained in this electrolysis process and desert sand containing SiO 2 are reacted as shown by the formula (1) to form Na 2 SiO 3, and this Na 2 SiO 3 and waste salts are electrolyzed. A sol-gel process in which the resulting HCl is reacted to form H 2 SiO 3 as shown by the formula (2), and the resulting H 2 SiO 3 is fired to increase the purity of SiO 2 ;
(1) SiO 2 + 2NaOH → Na 2 SiO 3 + H 2 O
(2) Na 2 SiO 3 + 2HCl → H 2 SiO 3 + 2NaCl
A carbon reduction step in which SiO 2 concentrated in the above sol-gel step is reduced with C as shown by the formula (3) to form high-purity metal silicon;
(3) SiO 2 + C → Si + CO 2
As shown in the following formulas (4) and (5), the metal silicon obtained in the above carbon reduction process is reacted with chlorine to form gaseous silicon tetrachloride, which is distilled to obtain solar grade silicon. A purification process;
(4) Si + Cl 2 → SiCl 4
(5) SiCl 4 + 2H 2 → Si + 4HCl
A method for producing a solar cell from waste salt and desert sand comprising a solar cell production step for producing a solar cell from solar grade silicon obtained by the above purification process.
　以上の廃棄塩と砂漠の砂から太陽電池を製造する方法は、砂漠地方での淡水化によって多量に発生している廃棄塩を有効に利用し、さらに、砂漠地方にほとんど無限に存在する砂を原料としてソーラーグレードシリコンを製造して、太陽電池を製造し、雨の少ない砂漠で有効に発電することで理想的な環境を実現することができる。 The above-mentioned method for producing solar cells from waste salt and desert sand effectively utilizes waste salt generated in large quantities due to desalination in the desert region, and further uses sand that exists almost infinitely in the desert region. Solar grade silicon can be manufactured as a raw material, solar cells can be manufactured, and an ideal environment can be realized by effectively generating power in a desert with little rain.
　さらに、本発明の廃棄塩と砂漠の砂から太陽電池を製造する方法は、電気分解工程で得られたＮａを酸化して得られるＮａＯに、以下の(6)式で示すように二酸化炭素を反応させて炭酸ナトリウムとし、この炭酸ナトリウムをシリカに混入してガラスを製造するガラス製造工程と、
　(6)　４ＮａＯ＋２ＣＯ２→２Ｎａ２ＣＯ３＋Ｏ２
　以上のガラス製造工程で得られたガラスの表面に、前記ソーラーグレードシリコンを使用して太陽電池層を設ける太陽電池製造工程とから太陽電池を製造することができる。 Furthermore, in the method for producing a solar cell from the waste salt of the present invention and desert sand, carbon dioxide is added to NaO obtained by oxidizing Na obtained in the electrolysis process as shown in the following formula (6). A glass production process in which sodium carbonate is reacted to produce glass by mixing this sodium carbonate with silica;
(6) 4NaO + 2CO 2 → 2Na 2 CO 3 + O 2
A solar cell can be manufactured from the solar cell manufacturing process which provides a solar cell layer on the surface of the glass obtained by the above glass manufacturing process using the solar grade silicon.
　さらに、本発明の廃棄塩と砂漠の砂から太陽電池を製造する方法は、ゾル・ゲル工程において、電気分解工程で得られるＮａＯＨとＳｉＯ２を含む砂漠の砂とを(1)の式で示すように反応させて珪酸ナトリウムとし、
　(1)　ＳｉＯ２＋２ＮａＯＨ→Ｎａ２ＳｉＯ３＋Ｈ２Ｏ
　得られるケイ酸ナトリウムをシリカに混入してガラスを製造するガラス製造工程と、
　ガラス製造工程で得られたガラスの表面に、ソーラーグレードシリコンを使用して太陽電池層を設ける太陽電池製造工程とから太陽電池を製造することができる。 Furthermore, in the method for producing a solar cell from the waste salt of the present invention and desert sand, the desert sand containing NaOH and SiO 2 obtained in the electrolysis step is represented by the formula (1) in the sol-gel process. To make sodium silicate,
(1) SiO 2 + 2NaOH → Na 2 SiO 3 + H 2 O
A glass production process for producing glass by mixing the obtained sodium silicate into silica,
A solar cell can be manufactured from a solar cell manufacturing process in which a solar cell layer is provided on the surface of the glass obtained in the glass manufacturing process using solar grade silicon.
　以上の廃棄塩と砂漠の砂から太陽電池を製造する方法は、砂漠地方での淡水化によって多量に発生している廃棄塩と、さらに砂漠地方にほとんど無限に存在する砂を原料としてガラスを製造し、このガラスを使用して太陽電池を製造するので、廃棄塩と砂を利用して、ソーラーグレードシリコンとガラスの両方を製造し、これ等を利用して太陽電池を製造することから、廃棄塩と砂の両方を有効に利用して太陽電池を製造することができる。 The method of manufacturing solar cells from the above waste salt and desert sand is to produce glass from waste salt generated in large quantities due to desalination in the desert region and sand that is almost infinite in the desert region. Since this glass is used to manufacture solar cells, waste salt and sand are used to manufacture both solar grade silicon and glass, and these are used to manufacture solar cells. A solar cell can be manufactured using both salt and sand effectively.
　以下、本発明の実施例を図面に基づいて説明する。ただし、以下に示す実施例は、本発明の技術思想を具体化するための廃棄塩と砂漠の砂から太陽電池を製造する方法を例示するものであって、本発明は太陽電池の製造方法を以下の方法には特定しない。さらに、この明細書は、特許請求の範囲に示される部材を、実施例の部材に特定するものでは決してない。 Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the examples shown below exemplify a method of manufacturing a solar cell from waste salt and desert sand for embodying the technical idea of the present invention, and the present invention describes a method of manufacturing a solar cell. The following methods are not specified. Further, this specification does not limit the members shown in the claims to the members of the embodiments.
　図１は、廃棄塩と砂漠の砂から太陽電池を製造する方法を示す工程図である。廃棄塩と砂から、以下の電気分解工程と、ゾル・ゲル工程と、炭素還元工程と、冶金工程とでソーラーグレードシリコンを製造し、このソーラーグレードシリコンを使用して太陽電池を製造する。 FIG. 1 is a process diagram showing a method for producing a solar cell from waste salt and desert sand. Solar grade silicon is produced from waste salt and sand by the following electrolysis process, sol-gel process, carbon reduction process, and metallurgical process, and a solar cell is produced using the solar grade silicon.
［電気分解工程］
　この工程は、図２に示すように、海水から淡水の分離された廃棄塩のＮａＣｌを電気分解してＮａを分離し、このＮａを水に反応させてＮａＯＨを得る工程である。ＮａＣｌは融解塩電解して金属ナトリウムとすることができる。融解塩電解は、ＮａＣｌを加熱して融解し、これを電気分解してＮａを分離する。この工程は、ＮａＣｌの融点を低くするために融剤を添加する。融剤にはＣａＣｌ２が使用できる。ＮａＣｌの融点は約８００℃であるが、ＮａＣｌにＣａＣｌ２をモル比で５４：４６の割合で添加して、融点を約５００℃に低下できる。ＮａＣｌとＣａＣｌ２とを混合して加熱して溶解し、これにプラス側の電極１１とマイナス側の電極１２を配置して、電気分解する。 [Electrolysis process]
As shown in FIG. 2, this step is a step of electrolyzing NaCl, which is a waste salt separated from fresh water from seawater, to separate Na, and reacting this Na with water to obtain NaOH. NaCl can be converted to metallic sodium by molten salt electrolysis. In molten salt electrolysis, NaCl is heated and melted, and this is electrolyzed to separate Na. In this step, a flux is added to lower the melting point of NaCl. CaCl 2 can be used as the flux. Although the melting point of NaCl is about 800 ° C., the melting point can be lowered to about 500 ° C. by adding CaCl 2 to NaCl at a molar ratio of 54:46. NaCl and CaCl 2 are mixed and heated to be dissolved, and a positive electrode 11 and a negative electrode 12 are arranged on this to be electrolyzed.
　融解塩電解において、マイナス側の電極１２にＮａが生成され、プラス側の電極１１に塩素が生成される。生成されるＮａと塩素とが反応しないように、電極の間に隔膜（図示せず）が設けられる。融解塩電解において、プラス側の電極１１は炭素、マイナス側の電極１２はタングステン、ステンレス、モリブデン等の金属を使用する。マイナス側の電極１２には不活性ガスを供給して、生成されるＮａが空気中の酸素と反応するのを防止する。プラス側の電極１１とマイナス側の電極１２には７Ｖの直流電圧を印加して電気分解する。 In molten salt electrolysis, Na is generated on the negative electrode 12 and chlorine is generated on the positive electrode 11. A diaphragm (not shown) is provided between the electrodes so that the produced Na and chlorine do not react. In molten salt electrolysis, the positive electrode 11 uses carbon, and the negative electrode 12 uses a metal such as tungsten, stainless steel, or molybdenum. An inert gas is supplied to the negative electrode 12 to prevent the produced Na from reacting with oxygen in the air. The positive electrode 11 and the negative electrode 12 are electrolyzed by applying a DC voltage of 7V.
　以上の工程で得られる金属Ｎａは水と反応させてＮａＯＨとなり、酸素と反応させてＮａ２Ｏとなる。塩素は水と反応させてＨＣｌとなる。 Metal Na obtained in the above steps is reacted with water to become NaOH, and reacted with oxygen to become Na 2 O. Chlorine reacts with water to become HCl.
［ゾル・ゲル工程］
　この工程は、図３に示すように、電気分解工程で得られるＮａＯＨと、砂漠の砂の成分であるＳｉＯ２とを、以下の(1)の式で示すように反応させてＮａ２ＳｉＯ３とし、さらに、このＮａ２ＳｉＯ３と、廃棄塩を電気分解して得られるＨＣｌとを反応させて(2)の式で示すようにＨ２ＳｉＯ３とし、得られたＨ２ＳｉＯ３を焼成してＳｉＯ２の純度を高くする。
　(1)　ＳｉＯ２＋２ＮａＯＨ→Ｎａ２ＳｉＯ３＋Ｈ２Ｏ
　(2)　Ｎａ２ＳｉＯ３＋２ＨＣｌ→Ｈ２ＳｉＯ３＋２ＮａＣｌ [Sol / Gel process]
In this step, as shown in FIG. 3, NaOH obtained in the electrolysis step and SiO 2 which is a component of desert sand are reacted as shown by the following formula (1) to form Na 2 SiO 3. Further, this Na 2 SiO 3 is reacted with HCl obtained by electrolyzing the waste salt to obtain H 2 SiO 3 as shown in the formula (2), and the obtained H 2 SiO 3 is calcined. Thus, the purity of SiO 2 is increased.
(1) SiO 2 + 2NaOH → Na 2 SiO 3 + H 2 O
(2) Na 2 SiO 3 + 2HCl → H 2 SiO 3 + 2NaCl
　(1)の反応は、ＮａＯＨの水溶液に粉末状に粉砕した砂を懸濁してゾル状態とし、砂のＳｉＯ２をＮａＯＨに溶解してＮａ２ＳｉＯ３とする。この工程で、不純物のＭｇＯ、Ｓ（ＣｕＳ）、Ｃａ（ＣａＣＯ３）、Ａｌ（ＡｌＯ）、ＮｉＯ、Ａｇ、Ａｕ、Ｃｕ等の不純物は沈殿して除去される。生成されたＮａ２ＳｉＯ３を加水分解してゲル状のＨ２ＳｉＯ３からなる水ガラスを得る。このゲル状の水ガラスにＨＣｌを添加して、(2)で示すように反応させてＨ２ＳｉＯ３とする。この工程で、不純物のＮａＣｌは沈殿して除去される。さらに、生成されたＨ２ＳｉＯ３を焼成して水分を気化させて、ＳｉＯ２の純度を９９％と高くする。 In the reaction (1), sand pulverized in powder form is suspended in an aqueous solution of NaOH to form a sol, and SiO 2 in the sand is dissolved in NaOH to form Na 2 SiO 3 . In this step, impurities such as MgO, S (CuS), Ca (CaCO 3 ), Al (AlO), NiO, Ag, Au, and Cu are precipitated and removed. The produced Na 2 SiO 3 is hydrolyzed to obtain a water glass composed of gel-like H 2 SiO 3 . HCl is added to the gel water glass and reacted as shown in (2) to form H 2 SiO 3 . In this step, impurity NaCl is precipitated and removed. Furthermore, the produced H 2 SiO 3 is fired to evaporate moisture, and the purity of SiO 2 is increased to 99%.
［炭素還元工程］
　以上のゾル・ゲル工程で９９％と純度の高くなったＳｉＯ２を、図４に示すように、以下の(3)の式で示すようにＣで還元して純度の高いメタルシリコンとする。
　(3)　ＳｉＯ２＋Ｃ→Ｓｉ＋ＣＯ２ [Carbon reduction process]
As shown in FIG. 4, SiO 2 having a purity as high as 99% in the above sol-gel process is reduced with C as shown in the following formula (3) to obtain high-purity metal silicon.
(3) SiO 2 + C → Si + CO 2
　この工程は、ＳｉＯ２の粉末と、炭素の粉末を、１：１～１：２のモル比となるようにミキサー２２で混合し、ホッパー２３から炭素電極２１のアーク炉２０に供給する。アーク炉２０は、炭素電極２１をアーク放電させて、供給されるＳｉＯ２と炭素とを加熱して還元する。さらに、図に示すアーク炉２０は、下からバーナー２４で加熱している。アーク炉２０に供給されるＳｉＯ２と炭素は、(3)の式で示すように反応して、純度を９９．９％とするメタルシリコンが生成される。生成されたメタルシリコンの上にはスラグが分離される。この工程で窒素やイオウが除去される。生成される炭酸ガスは、アーク炉２０から排出される。この工程で、ＳｉＯ２と炭素は、一部を一酸化炭素として二酸化炭素と一緒にアーク炉２０から排出される。 In this step, the SiO 2 powder and the carbon powder are mixed by the mixer 22 so as to have a molar ratio of 1: 1 to 1: 2, and supplied from the hopper 23 to the arc furnace 20 of the carbon electrode 21. The arc furnace 20 arc-discharges the carbon electrode 21 to heat and reduce the supplied SiO 2 and carbon. Furthermore, the arc furnace 20 shown in the drawing is heated by a burner 24 from below. The SiO 2 and carbon supplied to the arc furnace 20 react as shown by the equation (3) to produce metal silicon having a purity of 99.9%. Slag is separated on the generated metal silicon. Nitrogen and sulfur are removed in this process. The generated carbon dioxide gas is discharged from the arc furnace 20. In this step, SiO 2 and carbon are discharged from the arc furnace 20 together with carbon dioxide, partly as carbon monoxide.
［冶金工程］
　以上の炭素還元工程で得られたメタルシリコンは、図５に示すように、真空中で溶融炉３０に供給されると共に、電子ビーム装置３１から電子ビームが照射されて、電子ビームで液体の不純物を蒸発させて除去する。不純物の除去されたメタルシリコンは、一方向凝固用ルツボ３２に排出されて凝固する。凝固したメタルシリコンは、不活性ガスのアルゴン中において、水素と酸素を供給して燃焼させて酸化させることで、さらに不純物を除去する。この工程で純度を９９．９９９９％とする多結晶のソーラーグレードシリコンが得られる。 [Metallurgy process]
As shown in FIG. 5, the metal silicon obtained in the above carbon reduction process is supplied to the melting furnace 30 in a vacuum, and is irradiated with an electron beam from the electron beam device 31 to be liquid impurities by the electron beam. Is removed by evaporation. The metal silicon from which impurities have been removed is discharged to the unidirectional solidification crucible 32 and solidified. The solidified metal silicon is further oxidized by supplying hydrogen and oxygen in an inert gas argon to burn and oxidize the metal silicon. In this step, polycrystalline solar grade silicon having a purity of 99.9999% is obtained.
［太陽電池製造工程］
　以上の冶金工程で得られた多結晶のソーラーグレードシリコンを使用して、従来から行われているように、以下のようにして太陽電池を製造する。多結晶のソーラーグレードシリコンを溶融し、種結晶を投下してこれを回転させながら引き上げて単結晶に成長させて円柱状のインゴットとし、このインゴットを０．３ｍｍ～０．４ｍｍと薄くスライスして、単結晶セルを製造する。ただ、多結晶のソーラーグレードシリコンは、単結晶とすることなく、多結晶の状態で固めたものをインゴットとして、このインゴットを薄くスライスして、多結晶セルを製造することもできる。 [Solar cell manufacturing process]
Using the polycrystalline solar grade silicon obtained by the above metallurgical process, a solar cell is manufactured as follows, as conventionally performed. Melt polycrystalline solar grade silicon, drop seed crystal, pull it up and rotate it to grow into a single crystal to form a cylindrical ingot, and slice this ingot thinly from 0.3mm to 0.4mm A single crystal cell is manufactured. However, polycrystalline solar grade silicon can be produced by slicing this ingot thinly by making the ingot solidified in a polycrystalline state without making it a single crystal.
　以上のようにして製造された単結晶セルまたは多結晶セルの片面からリンを拡散してｐｎ接合とし、両面に電極を設けて太陽電池とする。電極は、片面を透明電極として太陽光線を透過させる。透明電極を透過する太陽光線は、シリコンのｐｎ接合に入射して起電力を発生する。 Phosphorus is diffused from one side of the single crystal cell or polycrystalline cell manufactured as described above to form a pn junction, and electrodes are provided on both sides to form a solar cell. The electrode transmits sunlight through one side as a transparent electrode. Sun rays that pass through the transparent electrode are incident on a silicon pn junction to generate an electromotive force.
　以上の製造方法は、図１に示すように、電気分解工程と、ゾル・ゲル工程と、炭素還元工程と、冶金工程とでソーラーグレードシリコンを製造するが、本発明の製造方法は、図６に示すように、冶金工程を以下の精製工程として、電気分解工程と、ゾル・ゲル工程と、炭素還元工程と、精製工程とでソーラーグレードシリコンを製造することができる。 In the above manufacturing method, as shown in FIG. 1, solar grade silicon is manufactured by an electrolysis process, a sol-gel process, a carbon reduction process, and a metallurgical process. As shown in FIG. 2, solar grade silicon can be produced by an electrolysis process, a sol-gel process, a carbon reduction process, and a purification process using the metallurgical process as the following purification process.
［精製工程］
　この工程は、炭素還元工程で得られたメタルシリコンを、以下の(4)と(5)式で示すように、電気分解工程で得られる塩素と反応させて四塩化ケイ素とし、これを蒸留してソーラーグレードシリコンを得る。
　(4)　Ｓｉ＋Ｃｌ２→ＳｉＣｌ４
　(5)　ＳｉＣｌ４＋２Ｈ２→Ｓｉ＋４ＨＣｌ [Purification process]
In this step, metal silicon obtained in the carbon reduction step is reacted with chlorine obtained in the electrolysis step as shown in the following formulas (4) and (5) to form silicon tetrachloride, which is distilled. Get solar grade silicon.
(4) Si + Cl 2 → SiCl 4
(5) SiCl 4 + 2H 2 → Si + 4HCl
　以上の精製工程で得られるソーラーグレードシリコンを使用して、前述した太陽電池製造工程で太陽電池を製造することができる。 Using solar grade silicon obtained by the above purification process, a solar cell can be manufactured by the solar cell manufacturing process described above.
　さらに、本発明は、図７に示すように、廃棄塩と砂漠の砂からガラスを製造し、このガラスを使用して太陽電池を製造することができる。この製造方法は、以下に示すガラス製造工程でガラスを製造し、製造されたガラスを使用して太陽電池製造工程で太陽電池を製造する。 Furthermore, as shown in FIG. 7, in the present invention, a glass can be manufactured from waste salt and desert sand, and a solar cell can be manufactured using this glass. This manufacturing method manufactures glass by the glass manufacturing process shown below, and manufactures a solar cell by a solar cell manufacturing process using the manufactured glass.
［ガラス製造工程］
　この工程は、前述の電気分解工程で得られたＮａを酸化して得られるＮａＯに、以下の(6)式で示すように二酸化炭素を反応させて炭酸ナトリウムとし、この炭酸ナトリウムをシリカに混入してガラスを製造する。
　(6)　４ＮａＯ＋２ＣＯ２→２Ｎａ２ＣＯ３＋Ｏ２ [Glass manufacturing process]
In this step, NaO obtained by oxidizing Na obtained in the above-described electrolysis step is reacted with carbon dioxide as shown in the following formula (6) to form sodium carbonate, and this sodium carbonate is mixed into silica. To produce glass.
(6) 4NaO + 2CO 2 → 2Na 2 CO 3 + O 2
　この工程では、ガラスの原料となるシリカとして、砂漠に多量に存在する砂を使用する。すなわち、砂漠の砂に含まれるＳｉＯ２をガラスの原料として使用すると共に、電気分解工程で得られたＮａを酸化して得られるＮａＯから製造される炭酸ナトリウムを使用する。シリカと炭酸ナトリウムを所定の割合で混合させると共に、この混合物を焼成してガラスが製造される。 In this process, sand existing in a large amount in the desert is used as silica as a raw material for glass. That is, SiO 2 contained in desert sand is used as a raw material for glass, and sodium carbonate produced from NaO obtained by oxidizing Na obtained in the electrolysis process is used. Silica and sodium carbonate are mixed at a predetermined ratio, and this mixture is fired to produce glass.
　さらにまた、ガラス製造工程は、ゾル・ゲル工程において、電気分解工程で得られるＮａＯＨとＳｉＯ２を含む砂漠の砂とを(1)の式で示すように反応させて珪酸ナトリウムとし、得られるケイ酸ナトリウムをシリカに混入し、この混合物を焼成してガラスを製造することもできる。
　(1)　ＳｉＯ２＋２ＮａＯＨ→Ｎａ２ＳｉＯ３＋Ｈ２Ｏ Furthermore, in the glass manufacturing process, in the sol-gel process, NaOH obtained in the electrolysis process and desert sand containing SiO 2 are reacted as shown by the formula (1) to obtain sodium silicate. Glass can also be produced by mixing sodium acid into silica and firing the mixture.
(1) SiO 2 + 2NaOH → Na 2 SiO 3 + H 2 O
　さらに、太陽電池製造工程において、ガラス製造工程で得られたガラスの表面に、前述の冶金工程または精製工程で得られた多結晶のソーラーグレードシリコンを使用して製造された太陽電池を太陽電池層として設けて、太陽電池を製造する。 Furthermore, in the solar cell manufacturing process, the solar cell layer is manufactured by using the polycrystalline solar grade silicon obtained in the metallurgical process or the refining process described above on the surface of the glass obtained in the glass manufacturing process. A solar cell is manufactured.
　さらに、廃棄塩は、含有しているカルシウムからＣａＭｎＯ３を作成して、これを熱電材料として温度差を利用した発電にも利用できる。ＣａＭｎＯ３は、マンガンの一部をイットリウムで置換してＣａ１－ｘＹｘＭｎＯ３（ｘ＝０～０．１）とし、これを焼結しても熱電材料として使用できる。この熱電材料は、イットリウムの置換量を多くして電気抵抗を小さくできる。とくに、ＣａＭｎＯ３からなる熱電材料は、高温安定性に優れていることから、海水を蒸留する工程での高温廃熱を有効に利用しての発電に適している。また、砂漠での炎天下における高温と海水の温度差を利用しての発電にも使用できる。 Further, the waste salt can be used for power generation by making CaMnO 3 from the contained calcium and using the temperature difference as a thermoelectric material. CaMnO 3 can be used as a thermoelectric material by substituting a part of manganese with yttrium to obtain Ca 1-x Y x MnO 3 (x = 0 to 0.1). This thermoelectric material can reduce the electrical resistance by increasing the amount of yttrium substitution. In particular, a thermoelectric material made of CaMnO 3 is suitable for power generation by effectively utilizing high-temperature waste heat in the process of distilling seawater because it is excellent in high-temperature stability. It can also be used for power generation using the temperature difference between high temperature and sea water under hot weather in the desert.
　本発明は、砂漠地方において、真水を得るために海水から真水を分離して発生する膨大な廃棄塩を有効に利用し、さらに砂漠に多量に存在する砂を原料として太陽電池を製造し、晴天が多くて太陽電池を有効に利用ことで、エネルギーをトータルとして極めて有効に利用できる。 The present invention effectively utilizes a large amount of waste salt generated by separating fresh water from seawater in order to obtain fresh water in the desert region, and further manufactures solar cells using sand existing in a large amount in the desert as a raw material. By using solar cells effectively, energy can be used extremely effectively as a total.
本発明の一実施例にかかる廃棄塩と砂漠の砂から太陽電池を製造する方法を示す工程図である。It is process drawing which shows the method to manufacture a solar cell from the waste salt and desert sand concerning one Example of this invention. 電気分解工程を示す概略図である。It is the schematic which shows an electrolysis process. ゾル・ゲル工程を示す概略図である。It is the schematic which shows a sol gel process. 炭素還元工程を示す概略図である。It is the schematic which shows a carbon reduction process. 冶金工程を示す概略図である。It is the schematic which shows a metallurgical process. 本発明の他の実施例にかかる廃棄塩と砂漠の砂から太陽電池を製造する方法を示す工程図である。It is process drawing which shows the method of manufacturing a solar cell from the waste salt and desert sand concerning other Examples of this invention. 本発明の他の実施例にかかる廃棄塩と砂漠の砂から太陽電池を製造する方法を示す工程図である。It is process drawing which shows the method of manufacturing a solar cell from the waste salt and desert sand concerning other Examples of this invention.
符号の説明Explanation of symbols
　１１…プラス側の電極
　１２…マイナス側の電極
　２０…アーク炉
　２１…電極
　２２…ミキサー
　２３…ホッパー
　２４…バーナー
　３０…溶融炉
　３１…電子ビーム装置
　３２…一方向凝固用ルツボ DESCRIPTION OF SYMBOLS 11 ... Positive side electrode 12 ... Negative side electrode 20 ... Arc furnace 21 ... Electrode 22 ... Mixer 23 ... Hopper 24 ... Burner 30 ... Melting furnace 31 ... Electron beam apparatus 32 ... Unidirectional solidification crucible

Claims (4)

  1. 　海水から淡水の分離された廃棄塩のＮａＣｌを電気分解して得られるＮａからＮａＯＨを得る電気分解工程と、
    　この電気分解工程で得られるＮａＯＨとＳｉＯ２を含む砂漠の砂とを(1)の式で示すように反応させてＮａ２ＳｉＯ３とし、さらに、このＮａ２ＳｉＯ３と、前記廃棄塩を電気分解して得られるＨＣｌとを反応させて(2)の式で示すようにＨ２ＳｉＯ３とし、得られたＨ２ＳｉＯ３を焼成してＳｉＯ２の純度を高くするゾル・ゲル工程と、
    　(1)　ＳｉＯ２＋２ＮａＯＨ→Ｎａ２ＳｉＯ３＋Ｈ２Ｏ
    　(2)　Ｎａ２ＳｉＯ３＋２ＨＣｌ→Ｈ２ＳｉＯ３＋２ＮａＣｌ
    　以上のゾル・ゲル工程で濃縮されたＳｉＯ２を(3)の式で示すようにＣで還元して純度の高いメタルシリコンとする炭素還元工程と、
    　(3)　ＳｉＯ２＋Ｃ→Ｓｉ＋ＣＯ２
    　以上の炭素還元工程で得られたメタルシリコンを、真空中で電子ビーム照射して不純物を蒸発除去すると共に、さらに酸化して不純物を除去してソーラーグレードシリコンを得る冶金工程と、
    　この冶金工程で得られるソーラーグレードシリコンから太陽電池を製造する太陽電池製造工程とからなる廃棄塩と砂漠の砂から太陽電池を製造する方法。     Electrolysis step of obtaining NaOH from Na obtained by electrolyzing NaCl of waste salt separated from fresh water from seawater;
    NaOH obtained in this electrolysis step and desert sand containing SiO 2 are reacted as shown by the formula (1) to form Na 2 SiO 3, and this Na 2 SiO 3 and the waste salt are converted into electricity. A sol-gel process in which HCl obtained by decomposition is reacted with H 2 SiO 3 as shown by the formula (2), and the obtained H 2 SiO 3 is baked to increase the purity of SiO 2 ;
    (1) SiO 2 + 2NaOH → Na 2 SiO 3 + H 2 O
    (2) Na 2 SiO 3 + 2HCl → H 2 SiO 3 + 2NaCl
    A carbon reduction step in which SiO 2 concentrated in the above sol-gel step is reduced with C as shown by the formula (3) to form high-purity metal silicon;
    (3) SiO 2 + C → Si + CO 2
    The metal silicon obtained in the above carbon reduction process is irradiated with an electron beam in vacuum to evaporate and remove impurities, and further oxidized to remove impurities to obtain solar grade silicon,
    A method for producing a solar cell from waste salt and desert sand comprising a solar cell production step for producing a solar cell from solar grade silicon obtained in this metallurgical process.
  2. 　海水から淡水の分離された廃棄塩のＮａＣｌを電気分解して得られるＮａからＮａＯＨを得る電気分解工程と、
    　この電気分解工程で得られるＮａＯＨとＳｉＯ２を含む砂漠の砂とを(1)の式で示すように反応させてＮａ２ＳｉＯ３とし、さらに、このＮａ２ＳｉＯ３と、前記廃棄塩を電気分解して得られるＨＣｌとを反応させて(2)の式で示すようにＨ２ＳｉＯ３とし、得られたＨ２ＳｉＯ３を焼成してＳｉＯ２の純度を高くするゾル・ゲル工程と、
    　(1)　ＳｉＯ２＋２ＮａＯＨ→Ｎａ２ＳｉＯ３＋Ｈ２Ｏ
    　(2)　Ｎａ２ＳｉＯ３＋２ＨＣｌ→Ｈ２ＳｉＯ３＋２ＮａＣｌ
    　以上のゾル・ゲル工程で濃縮されたＳｉＯ２を(3)の式で示すようにＣで還元して純度の高いメタルシリコンとする炭素還元工程と、
    　(3)　ＳｉＯ２＋Ｃ→Ｓｉ＋ＣＯ２
    　以上の炭素還元工程で得られたメタルシリコンを、以下の(4)と(5)式で示すように、塩素と反応させガス状の四塩化ケイ素とし、これを蒸留してソーラーグレードシリコンを得る精製工程と、
    　(4)　Ｓｉ＋２Ｃｌ２→ＳｉＣｌ４
    　(5)　ＳｉＣｌ４＋２Ｈ２→Ｓｉ＋４ＨＣｌ　
    　以上の精製工程で得られるソーラーグレードシリコンから太陽電池を製造する太陽電池製造工程とからなる廃棄塩と砂漠の砂から太陽電池を製造する方法。     Electrolysis step of obtaining NaOH from Na obtained by electrolyzing NaCl of waste salt separated from fresh water from seawater;
    NaOH obtained in this electrolysis step and desert sand containing SiO 2 are reacted as shown by the formula (1) to form Na 2 SiO 3, and this Na 2 SiO 3 and the waste salt are converted into electricity. A sol-gel process in which HCl obtained by decomposition is reacted with H 2 SiO 3 as shown by the formula (2), and the obtained H 2 SiO 3 is baked to increase the purity of SiO 2 ;
    (1) SiO 2 + 2NaOH → Na 2 SiO 3 + H 2 O
    (2) Na 2 SiO 3 + 2HCl → H 2 SiO 3 + 2NaCl
    A carbon reduction step in which SiO 2 concentrated in the above sol-gel step is reduced with C as shown by the formula (3) to form high-purity metal silicon;
    (3) SiO 2 + C → Si + CO 2
    As shown in the following formulas (4) and (5), the metal silicon obtained in the above carbon reduction process is reacted with chlorine to form gaseous silicon tetrachloride, which is distilled to obtain solar grade silicon. A purification process;
    (4) Si + 2Cl 2 → SiCl 4
    (5) SiCl 4 + 2H 2 → Si + 4HCl
    A method for producing a solar cell from waste salt and desert sand comprising a solar cell production step for producing a solar cell from solar grade silicon obtained by the above purification process.
  3. 　前記電気分解工程で得られたＮａを酸化して得られるＮａＯに、以下の(6)式で示すように二酸化炭素を反応させて炭酸ナトリウムとし、得られた炭酸ナトリウムをシリカに混入してガラスを製造するガラス製造工程と、
    　(6)　４ＮａＯ＋２ＣＯ２→２Ｎａ２ＣＯ３＋Ｏ２
    　以上のガラス製造工程で得られたガラスの表面に、前記ソーラーグレードシリコンを使用して太陽電池層を設ける太陽電池製造工程とからなる請求項１または２に記載される廃棄塩と砂漠の砂から太陽電池を製造する方法。     NaO obtained by oxidizing Na obtained in the electrolysis step is reacted with carbon dioxide as shown in the following formula (6) to form sodium carbonate, and the obtained sodium carbonate is mixed into silica to form glass. A glass manufacturing process for manufacturing,
    (6) 4NaO + 2CO 2 → 2Na 2 CO 3 + O 2
    From the waste salt and desert sand according to claim 1 or 2, comprising a solar cell production step in which a solar cell layer is provided using the solar grade silicon on the surface of the glass obtained in the above glass production step. A method of manufacturing a solar cell.
  4. 　前記ゾル・ゲル工程において、前記電気分解工程で得られるＮａＯＨとＳｉＯ２を含む砂漠の砂とを(1)の式で示すように反応させて珪酸ナトリウムとし、
    　(1)　ＳｉＯ２＋２ＮａＯＨ→Ｎａ２ＳｉＯ３＋Ｈ２Ｏ
    　得られるケイ酸ナトリウムをシリカに混入してガラスを製造するガラス製造工程と、
    　以上のガラス製造工程で得られたガラスの表面に、前記ソーラーグレードシリコンを使用して太陽電池層を設ける太陽電池製造工程とからなる請求項１または２に記載される廃棄塩と砂漠の砂から太陽電池を製造する方法。     In the sol-gel process, NaOH obtained in the electrolysis process and desert sand containing SiO 2 are reacted as shown by the formula (1) to form sodium silicate,
    (1) SiO 2 + 2NaOH → Na 2 SiO 3 + H 2 O
    A glass production process for producing glass by mixing the obtained sodium silicate into silica,
    From the waste salt and desert sand according to claim 1 or 2, comprising a solar cell production step in which a solar cell layer is provided using the solar grade silicon on the surface of the glass obtained in the above glass production step. A method of manufacturing a solar cell.
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