JP5795728B2 - Solid particulate collection method - Google Patents

Solid particulate collection method Download PDF

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JP5795728B2
JP5795728B2 JP2011208967A JP2011208967A JP5795728B2 JP 5795728 B2 JP5795728 B2 JP 5795728B2 JP 2011208967 A JP2011208967 A JP 2011208967A JP 2011208967 A JP2011208967 A JP 2011208967A JP 5795728 B2 JP5795728 B2 JP 5795728B2
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liquid
particle size
fine particles
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JP2013066871A (en
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芳宏 久保田
芳宏 久保田
知生 樋口
知生 樋口
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Shin Etsu Chemical Co Ltd
Shinano Electric Refining Co Ltd
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Shinano Electric Refining Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
    • B01D21/01—Separation of suspended solid particles from liquids by sedimentation using flocculating agents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D21/00—Separation of suspended solid particles from liquids by sedimentation
    • B01D21/26—Separation of sediment aided by centrifugal force or centripetal force
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J8/00—Chemical or physical processes in general, conducted in the presence of fluids and solid particles; Apparatus for such processes
    • B01J8/005—Separating solid material from the gas/liquid stream
    • B01J8/0055—Separating solid material from the gas/liquid stream using cyclones
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/90—Carbides
    • C01B32/914—Carbides of single elements
    • C01B32/956—Silicon carbide
    • 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
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F11/00—Treatment of sludge; Devices therefor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2215/00—Separating processes involving the treatment of liquids with adsorbents
    • B01D2215/02—Separating processes involving the treatment of liquids with adsorbents with moving adsorbents
    • B01D2215/029—Centrifuge-like arrangements
    • C—CHEMISTRY; METALLURGY
    • C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F2101/00—Nature of the contaminant
    • C02F2101/10—Inorganic compounds

Description

本発明は、液に含まれるＳｉＣやＳｉの固体微粒子を液中から分離して回収する方法及びその回収した固体微粒子を再利用可能に再生する方法に関するものである。   The present invention relates to a method for separating and recovering SiC or Si solid fine particles contained in a liquid, and a method for reclaiming the recovered solid fine particles so as to be reusable.

近年、炭化珪素粉（ＳｉＣ粉）はＳｉ、水晶、ＳｉＣ、ＧａＡｓ、ＧａＮ等の単結晶や多結晶の基板、ガラス、又はセラミックス等の切断や研削や研磨に使用されるだけでなく、ＳｉＣ成形体の原料としても使用されており、幅広く用いられている。このＳｉＣ粉は、通常、アチソン法によりバッチ反応で製造されている。   In recent years, silicon carbide powder (SiC powder) has been used not only for cutting, grinding and polishing of single crystal and polycrystalline substrates such as Si, quartz, SiC, GaAs, and GaN, glass, or ceramics, but also for SiC molding. It is also used as a raw material for the body and is widely used. This SiC powder is usually produced by a batch reaction by the Atchison method.

アチソン法は、大気開放のＵ型炉で、中心に長手方向にグラファイト電極を通し、その電極周りに、数ｍｍ〜数ｃｍの珪砂及び炭素の混合物を蒲鉾状に積み上げ、グラファイト電極に大電流を流し加熱してＳｉＣを製造するものである。この反応（ＳｉＯ2＋３Ｃ→ＳｉＣ＋ＣＯ）は吸熱反応であり、グラファイト電極のみが発熱体で高温なので、電極周りにおいてよく反応し、主として高温安定型結晶のαＳｉＣが生成する。一方、電極から離れた部分では、未反応であったり、比較的用途が限定されている低温安定型結晶のβＳｉＣとαＳｉＣとの混合物等が多く生成したり、反応が不十分である。反応後は、塊状に硬く固まった炉内物を粗く砕き、所望のαＳｉＣ部分のみを選別し、更に微粉砕する。残りの未反応物やβＳｉＣとαＳｉＣとの混合物は、不要品として再度、反応原料に戻される。微粉砕されたαＳｉＣは、各種用途に応じて、水等を用いた湿式分級や、空気や窒素等を用いた乾式分級で、その用途に応じた最適な粒度や粒度分布に調整される。このようにして得られたＳｉＣ微粉は、前記の切断、研削、研磨の砥粒、研削材として、又はＳｉＣ成形体の原料粉末として、大量に用いられている。 The Atchison method is a U-shaped furnace that is open to the atmosphere. A graphite electrode is passed in the longitudinal direction at the center, and a mixture of several millimeters to several centimeters of silica sand and carbon is piled up in a bowl shape. The SiC is manufactured by flowing and heating. This reaction (SiO 2 + 3C → SiC + CO) is an endothermic reaction, and since only the graphite electrode is a heating element and has a high temperature, it reacts well around the electrode and mainly produces αSiC as a high-temperature stable crystal. On the other hand, in a portion away from the electrode, a large amount of a mixture of β-SiC and α-SiC, which is unreacted or has relatively limited use, is produced, or the reaction is insufficient. After the reaction, the in-furnace hardened and hardened material is roughly crushed, and only the desired αSiC portion is selected and further pulverized. The remaining unreacted material and the mixture of βSiC and αSiC are returned to the reaction raw material again as unnecessary products. The finely pulverized αSiC is adjusted to an optimum particle size and particle size distribution according to the application by wet classification using water or the like, or dry classification using air, nitrogen or the like according to various applications. The SiC fine powder obtained in this way is used in large quantities as the above-mentioned cutting, grinding, polishing abrasives, abrasives, or as raw material powder for SiC compacts.

ＳｉＣ微粉の製造では、使用目的や用途により最適な平均粒径や粒度分布が要求されるため、所望粒度と不要粒度とを分ける分級工程が不可欠である。この分級では、比較的低コストで精密分級が可能な水分級法が一般的であるが、需要の無い不要なＳｉＣ微粉を含有する水溶液が多量に発生する。同様に、乾式分級の場合でも不要なＳｉＣ微粉が発生し、それらの処理が問題となっている。また、単結晶や多結晶のＳｉインゴットや成形物を研削する際にも、切子のＳｉ微粒子を含有した廃液が多量に発生しており、その処理も問題となっている。   In the manufacture of SiC fine powder, an optimum average particle size and particle size distribution are required depending on the purpose of use and application, and therefore a classification process for separating desired particle size from unnecessary particle size is indispensable. In this classification, a moisture classification method that enables precise classification at a relatively low cost is common, but a large amount of an aqueous solution containing unnecessary SiC fine powder that is not in demand is generated. Similarly, unnecessary SiC fines are generated even in the case of dry classification, and their treatment is a problem. Further, when grinding single crystal or polycrystalline Si ingots or molded products, a large amount of waste liquid containing faceted Si fine particles is generated, and the treatment thereof is also a problem.

この溶液や廃液の処理として、遠心分離機や濾過機でＳｉＣやＳｉの微粒子を回収し有効利用しようとしても、そのままでは超微細な粒子が混在しているため、完全な固液分離が極めて難しい。産業廃棄物として焼却処分するか、大量な熱で加熱乾燥した後に乾燥残渣のＳｉＣやＳｉを回収し、精々、経済的価値の低い溶鉱炉の脱酸剤として利用されたり、アチソン炉の原料として戻され利用されたりすることが一般的である。ＳｉＣやＳｉの微粒子を除去した後の液体は、場合により蒸留して再利用されることもあるが、熱エネルギー代が高く経済的ではない。   As a treatment of this solution and waste liquid, even if it tries to collect and effectively use SiC and Si fine particles with a centrifuge or a filter, it is extremely difficult to completely separate solid and liquid because it contains ultrafine particles. . It is disposed of by incineration as industrial waste, or heat-dried with a large amount of heat, and then the dried residue of SiC and Si is recovered and used as a deoxidizer for blast furnaces with low economic value, or returned as raw materials for the Atchison furnace It is common to be used. The liquid after removal of SiC or Si fine particles may be reused by distillation in some cases, but the heat energy cost is high and it is not economical.

また、ＳｉＣを遊離砥粒としてスラリー状態でワイヤーにより切断する遊離砥粒ワイヤーソーでは、水又は油の溶媒中に研削材のＳｉＣ微粉とエチレングリコール、界面活性剤、防錆剤等の種々の添加材とを加えたスラリーを作りＳｉインゴット等の切断に使用する。このスラリーは、単結晶や多結晶Ｓｉを多量に切断すると、最適であったＳｉＣの粒径や粒度分布から、磨耗、割れ、へたり、細粒化により粒度分布が広がり切断能力が低下すると共に、切子のＳｉ微粒子が蓄積してスラリー粘度が上昇し、スラリーの循環使用が不能となり、新しいスラリーと交換される。使用不能となったスラリー廃液には、水又は油の溶媒以外に消耗し細粒化したＳｉＣや切子のＳｉや各種の添加剤が存在しており、排水汚染の問題により単純に廃棄することができない。同様に、ダイヤモンド粒を固定したダイヤモンド固定ワイヤーソーによりウエハーや薄片を製造する際に発生する切子のＳｉ微粒子を含有したスラリー廃液においても、これまで再利用が難しく、その処理が問題とされている。   In addition, in the free abrasive wire saw that cuts SiC in the slurry state as free abrasive grains, various additions such as SiC fine powder and ethylene glycol, surfactant, rust preventive agent etc. in water or oil solvent A slurry is added to the material and used to cut Si ingots. When a large amount of single crystal or polycrystalline Si is cut, this slurry expands the particle size distribution due to wear, cracks, sag, and finer particles, resulting in a decrease in cutting ability. Then, the Si fine particles of the face accumulate and the viscosity of the slurry rises, so that the slurry cannot be circulated and replaced with a new slurry. Unusable slurry waste liquid contains not only water or oil solvent but also consumed SiC and fine-grained SiC, faceted Si, and various additives. Can not. Similarly, slurry waste liquid containing Si fine particles of facets generated when manufacturing wafers and flakes with a diamond-fixed wire saw with diamond grains fixed is difficult to reuse so far, and its treatment has been a problem. .

これらのワイヤーソースラリー廃液のＳｉＣとＳｉとの混合微粉については、これまで幾つかの回収、有効活用方法が提案されており、例えば、特許文献１に研削泥中の金属けい素を炭化けい素に転化するのに必要な量の炭素を加え、非酸化条件下で１２００℃以上に加熱する炭化けい素結晶体の製造方法が開示されている。また、特許文献２に、廃シリコンスラッジに炭素を添加混合して得られた混合物を加熱する炭化珪素の製造方法が開示されている。   Regarding the mixed fine powders of SiC and Si in these wire saw slurry waste liquids, several recovery and effective utilization methods have been proposed so far. For example, Patent Document 1 discloses silicon carbide as silicon carbide in grinding mud. A method for producing a silicon carbide crystal is disclosed in which an amount of carbon necessary for conversion into carbon is added and heated to 1200 ° C. or higher under non-oxidizing conditions. Patent Document 2 discloses a method for producing silicon carbide in which a mixture obtained by adding and mixing carbon to waste silicon sludge is heated.

これらの方法は、廃液中に含有されている微細なＳｉをＳｉＣに転換するために必要とされる量の炭素、例えば、石油コークスやカーボンブラックを廃スラリーに添加して加熱乾燥、又はその廃スラリーを遠心分離や濾過して得られた固形スラッジを加熱して切子のＳｉをＳｉＣ（Ｓｉ＋Ｃ→ＳｉＣ）として回収し活用しようとするものである。しかし、これらの方法では、超微細な粒子が混在しているため、実際には遠心分離や濾過が難しく完全な固液分離による回収が困難であり、超高速回転の高価な装置や膨大な濾過面積が必要とされることでコスト高となり実用化が難しい。現状、遠心分離機又は液体サイクロンで比較的大粒径の粒子のみを分離して回収し、再利用することは可能であるが、残りの超微粉であるＳｉＣやＳｉを含んだ残液は固液分離が難しく、そのまま廃棄物となっている。また、加熱コストが掛る蒸留法で固液を分離し再利用する場合でも、超微粉であるＳｉＣ及びＳｉは細か過ぎるため、利用価値がなく、廃棄物として処理されるのが一般的である。   In these methods, an amount of carbon required for converting fine Si contained in the waste liquid into SiC, for example, petroleum coke or carbon black, is added to the waste slurry and dried by heating, or the waste thereof. Solid sludge obtained by centrifuging or filtering the slurry is heated to recover and utilize the Si of the facets as SiC (Si + C → SiC). However, in these methods, since ultrafine particles are mixed, it is actually difficult to perform centrifugation or filtration, and it is difficult to recover by complete solid-liquid separation. Since the area is required, the cost becomes high and practical application is difficult. Currently, it is possible to separate and collect only relatively large particles with a centrifuge or a hydrocyclone and collect them for reuse, but the remaining liquid containing SiC and Si, which are the remaining ultrafine powder, is solid. Liquid separation is difficult and it becomes waste as it is. Moreover, even when solid-liquid is separated and reused by a distillation method that requires heating costs, SiC and Si, which are ultrafine powders, are too fine and generally have no utility value and are treated as waste.

溶液や廃液を固液分離せずにそのまま加熱乾燥する方法は、大きな熱量が必要で経済的でない。仮に廃スラリー中からＳｉＣ微粒子を回収したとしても、へたりや細粒化されており、そのままの状態では、ワイヤーソー等の高度な用途には再度使用することができない。また、ＳｉＣ微粒子と共に回収された切子のＳｉ微粒子は、加熱によりカーボンと反応し、新たにＳｉＣを生成できるが、元々回収されたＳｉはワイヤーソーの切子ゆえ超微粉で且つ粒度分布が広いため、生成されるＳｉＣも微粒子で粒度分布が広くなってしまう。回収されるＳｉＣと同様に、所要の比較的大きな粒径且つ狭い粒度分布が要求されるワイヤーソー用等には不向きな低付加価値のものであり、これらの改善が望まれている。   A method of heating and drying a solution or a waste liquid as it is without solid-liquid separation requires a large amount of heat and is not economical. Even if the SiC fine particles are recovered from the waste slurry, they are sagged or finely divided and cannot be used again for advanced applications such as a wire saw. In addition, the Si fine particles collected together with the SiC fine particles react with carbon by heating, and can newly generate SiC, but the originally collected Si is a fine powder and a wide particle size distribution because of the wire saw face, The generated SiC is also fine particles and the particle size distribution becomes wide. Like the recovered SiC, it is of low added value that is unsuitable for wire saws that require a required relatively large particle size and narrow particle size distribution, and these improvements are desired.

特開平１１−１１６２２７号公報Japanese Patent Laid-Open No. 11-116227 特開２００２−２５５５３２号公報JP 2002-255532 A

本発明は前記の課題を解決するためになされたもので、ＳｉＣやＳｉの固体微粒子を含む液から比較的大粒径の固体微粒子を分離して回収するだけでなく、その固体微粒子より小粒径である超微細な固体微粒子を効率よく固液分離し、それら全ての固体微粒子を回収する方法、及びその回収した固体微粒子におけるＳｉをＳｉＣに転化すると共に、へたりや細粒化され使用困難で利用価値のないＳｉＣを利用価値の高い粒径や粒度を有しワイヤーソー、ラッピング、ポリシング用等の高付加価値の研削材、砥粒、研磨材に利用可能で、有用なＳｉＣとして再生する方法を提供することを目的とする。   The present invention has been made to solve the above-described problems, and not only separates and collects relatively large solid particles from a liquid containing SiC or Si solid particles, but also smaller particles than the solid particles. Efficient solid-liquid separation of ultrafine solid fine particles with a diameter, and recovering all of these solid fine particles, and converting the recovered solid fine particles into SiC and making them sluggish and fine, difficult to use Non-useful SiC can be used for high-value-added abrasives, abrasives, abrasives, etc., with high-use particle size and particle size, for wire saws, lapping, polishing, etc., and recycled as useful SiC It aims to provide a method.

前記の目的を達成するためになされた、特許請求の範囲の請求項１に記載されたＳｉＣ及び/又はＳｉの固体微粒子回収方法は、ＳｉＣ及び/又はＳｉの固体微粒子を含む液を、遠心分離又は／及び液体サイクロンにより該固体微粒子中の平均粒径が４〜１５μｍである比較的大粒径の固体微粒子を分離して回収し、平均粒径が０．１〜５μｍである比較的小粒径の固体微粒子が残存する液を排出する第一工程と、第一工程から排出された液に、下記化学式（１）

Figure 0005795728
（式中、Ｒ １ は水素原子又はメチル基であり、Ｒ ２ は炭素数１〜１０のアルキル基であり、ＸはＣｌ、Ｂｒ、及びＦから選ばれる何れかのハロゲン化物であり、ａは０〜１０の数、ｂは１〜１０の数、ｍは最小で３の数である）で示されるカチオン性有機凝集剤からなる有機凝集剤を添加して該平均粒径が０．１〜５μｍである比較的小粒径の固体微粒子が平均粒径３〜１５μｍに凝集して形成された凝集体が含まれる液を、遠心分離又は濾過して該凝集体を回収する第二工程とを有する、方法である。 The method for recovering SiC and / or Si solid fine particles according to claim 1, which has been made to achieve the above object, includes centrifuging a liquid containing SiC and / or Si solid fine particles. Alternatively, and / or relatively small particles having an average particle size of 0.1 to 5 μm , which are separated and recovered by using a liquid cyclone and having a relatively large particle size of 4 to 15 μm. In the first step of discharging the liquid in which the solid fine particles of the diameter remain, and in the liquid discharged from the first step, the following chemical formula (1)
Figure 0005795728
 (Wherein, R 1 is a hydrogen atom or a methyl group, R 2 is an alkyl group having 1 to 10 carbon atoms, X is any halide selected from Cl, Br, and F, and a is The average particle diameter is 0.1 to 10 by adding an organic flocculant composed of a cationic organic flocculant represented by the number 0 to 10, b is a number 1 to 10 and m is a number 3 at the minimum. A second step of collecting the aggregate by centrifuging or filtering a liquid containing an aggregate formed by agglomerating solid microparticles having a relatively small particle size of 5 μm to an average particle diameter of 3 to 15 μm; Having a method.

請求項２に記載された固体微粒子回収方法は、請求項１に記載されたものであって、前記第二工程が、前記凝集体が含まれる液を、遠心分離又は濾過して固形分である前記凝集体と透明な液分である液体とに固液分離して、前記凝集体と該液体とを回収することを特徴とする。 The solid particulate collection method described in claim 2 is the solid particulate collection method described in claim 1, wherein the second step is a solid content obtained by centrifuging or filtering the liquid containing the aggregate. The aggregate and the liquid are recovered by solid-liquid separation into a liquid that is a transparent liquid .

請求項３に記載された固体微粒子回収方法は、請求項１または２に記載されたものであって、第一工程から排出された液１００重量部に対して、前記有機凝集剤を０．０１〜１０重量部とすることを特徴とする。   The solid fine particle recovery method described in claim 3 is the method described in claim 1 or 2, wherein 0.01% of the organic flocculant is added to 100 parts by weight of the liquid discharged from the first step. -10 parts by weight.

請求項４に記載された有用なＳｉＣへの再生方法は、請求項１の固体微粒子回収方法により回収した前記凝集体に、炭素、又は炭素と酸化珪素とを添加して非酸化性雰囲気下で最低でも１８００℃で加熱して前記ＳｉＣの平均粒径を肥大化させ、又は前記ＳｉからＳｉＣへ転化させることを特徴とする。   A useful method for regenerating SiC according to claim 4 is to add carbon or carbon and silicon oxide to the aggregate recovered by the solid particulate recovery method of claim 1 under a non-oxidizing atmosphere. Heating at least 1800 ° C. increases the average particle size of the SiC, or converts the Si to SiC.

請求項５に記載された有用なＳｉＣへの再生方法は、請求項４に記載の再生方法において、炭素、又は炭素と酸化珪素とともに、Ｂ、Ｂ４Ｃ、及びＢ２Ｏ３から選ばれる何れかの焼結助剤を添加することを特徴とする。 The method for regenerating SiC useful according to claim 5 is any one selected from B, B 4 C, and B 2 O 3 together with carbon or carbon and silicon oxide in the regeneration method according to claim 4. The sintering aid is added.

本発明のＳｉＣ及び/又はＳｉの固体微粒子回収方法によれば、ＳｉＣやＳｉの固体微粒子を含む液から、効率よく固液を完全分離して、これらの超微粉である固体微粒子を回収することができる。この回収工程として第一工程と第二工程との２段階で回収することで、粒度分布が広く種々の粒径の固体微粒子が含有される液から、比較的大粒径の固体微粒子と比較的小粒径の固体微粒子とを分けて回収することができる。この回収された固体微粒子のうち、比較的大粒径の固体微粒子は、そのまま、再度リサイクルして使用することができ、比較的小粒径の固体微粒子は、再生して使用することができる。また、この固体微粒子回収方法によれば、各微粒子側の固形分と完全透明な液分とに分離することができるため、排水を汚濁せず、排水汚染の問題を生じることがない。固液分離された液体も、再度使用することができる。   According to the SiC and / or Si solid fine particle recovery method of the present invention, the solid liquid is efficiently and completely separated from a liquid containing SiC or Si solid fine particles, and the solid fine particles, which are ultrafine powders, are recovered. Can do. By recovering in two steps, the first step and the second step, as a recovery step, a solid particle having a relatively large particle size and a relatively large particle size distribution can be obtained from a liquid containing a wide range of particle size distribution and various particle sizes. Small solid particles can be collected separately. Among the collected solid fine particles, the solid fine particles having a relatively large particle size can be recycled and used as they are, and the solid fine particles having a relatively small particle size can be regenerated and used. Further, according to this solid fine particle recovery method, the solid content on each fine particle side and the completely transparent liquid content can be separated, so that the waste water is not polluted and the problem of waste water pollution does not occur. The liquid which has been subjected to solid-liquid separation can also be used again.

本発明の固体微粒子回収方法は、液に直接炭素を添加することで遠心分離の量や濾過量を増加させて固液分離の負担を一層大きくし効率が悪いうえ、炭素が微粒子の場合に必要量の炭素を添加するとグリースや団子状になり固液分離の操作が全く不可能になるような従来の方法に比べて、第一工程で比較的大粒径の固体微粒子を回収した後に、第二工程で比較的小粒径の固体微粒子を凝集させ固液分離するため、超高速回転や膨大な濾過面積を有するような高価な装置を使用する必要がなく、経済的であり実用化することができる。   The solid fine particle recovery method of the present invention increases the amount of centrifugal separation and filtration by adding carbon directly to the liquid to further increase the burden of solid-liquid separation and is inefficient, and is necessary when carbon is fine particles. Compared with the conventional method in which the operation of solid-liquid separation becomes impossible at all when the amount of carbon is added, it becomes grease or dumpling, and after collecting solid particles with a relatively large particle size in the first step, Since solid particles with a relatively small particle size are agglomerated and separated into solid and liquid in two steps, there is no need to use an expensive device with ultra-high speed rotation and a huge filtration area, and it is economical and practical. Can do.

本発明の再生方法によれば、これらの回収された固体微粒子のうち、比較的小粒径の固体微粒子を、ＳｉをＳｉＣへ転化したり、微細なＳｉＣを肥大化したりして、所望の粒径及び粒度分布を有し利用価値の高い粒子へと再生することができる。   According to the regeneration method of the present invention, among these recovered solid fine particles, the solid fine particles having a relatively small particle size are converted into Si or SiC, or the fine SiC is enlarged to obtain desired particles. It can be regenerated into particles having a diameter and a particle size distribution and high utility value.

以下、本発明の実施の好ましい形態について詳細に説明するが、本発明の範囲はこれらの形態に限定されるものではない。   Hereinafter, preferred embodiments of the present invention will be described in detail, but the scope of the present invention is not limited to these embodiments.

本発明のＳｉＣ及び/又はＳｉの固体微粒子回収方法は、ＳｉＣ粉を製造する際の分級工程で副産物として生成する目的粒径以下の不要なＳｉＣ微粒子を含んだ溶液、単結晶や多結晶のＳｉインゴットや成形物を研削する際の切子のＳｉ微粒子を含有した廃液、ＳｉＣを遊離砥粒として単結晶や多結晶Ｓｉをスラリー状態でワイヤーにより切断する遊離砥粒ワイヤーソー又はダイヤモンド粒を固定したダイヤモンド固定ワイヤーソーによりウエハーや薄片を製造する際に発生するＳｉＣ微粒子やＳｉ微粒子を含有したスラリー廃液等の懸濁液から、これまで利用が難しく廃棄物とされていたＳｉＣ微粒子やＳｉ微粒子やこれらの混合微粉を、経済的で効率良く分離して回収する方法である。   The method for recovering SiC and / or Si solid fine particles according to the present invention includes a solution containing unnecessary SiC fine particles having a target particle size or less generated as a by-product in a classification step when producing SiC powder, single crystal or polycrystalline Si. Waste liquid containing faceted Si fine particles when grinding ingots and molded products, free abrasive grain wire saws that cut single crystals or polycrystalline Si in a slurry state using SiC as free abrasive grains, or diamond with diamond grains fixed From the suspension of SiC fine particles and slurry waste liquid containing Si fine particles that are generated when wafers and flakes are produced with a fixed wire saw, SiC fine particles and Si fine particles that have been difficult to use until now, and these This is a method for separating and recovering mixed fine powder economically and efficiently.

本発明の固体微粒子回収方法における各工程について詳細に説明する。   Each step in the solid fine particle recovery method of the present invention will be described in detail.

この固体微粒子回収方法は、ＳｉＣやＳｉの固体微粒子を含む液から遠心分離や液体サイクロンにより固体微粒子中の比較的大粒径の固体微粒子を分離して回収する第一工程と、第一工程から排出された液に有機凝集剤を添加して比較的小粒径の固体微粒子が凝集して形成される凝集体が含まれる液を、遠心分離機又は濾過機で固液分離して、凝集体を回収する第二工程とを有するものである。   The solid fine particle recovery method includes a first step of separating and recovering a relatively large particle size solid particle in a solid fine particle by centrifugation or a liquid cyclone from a liquid containing SiC or Si solid fine particles; A liquid containing an aggregate formed by adding an organic flocculant to the discharged liquid and agglomerating solid microparticles with a relatively small particle diameter is subjected to solid-liquid separation with a centrifuge or a filter, and the aggregate And a second step of recovering.

第一工程では、固体主成分としてＳｉＣやＳｉの固体微粒子を含む液を、遠心分離機や液体サイクロンを用いて遠心分離や分級して、固体微粒子のうち比較的大粒径の固体微粒子又はそれを含む液と、比較的小粒径の固体微粒子が残存する液とに分離する。そのうち、比較的大粒径の固体微粒子を回収して、比較的小粒径の固体微粒子が残存する液を排出する。   In the first step, a liquid containing SiC or Si solid fine particles as a solid main component is centrifuged or classified using a centrifuge or a liquid cyclone, and the solid fine particles having a relatively large particle size or the same And a liquid in which solid fine particles having a relatively small particle size remain. Among them, the solid particles having a relatively large particle diameter are collected, and the liquid in which the solid particles having a relatively small particle diameter remain is discharged.

比較的大粒径の固体微粒子は、その平均粒径が４〜１５μｍであると好ましい。この固体微粒子は、比較的粒径が大きいため、再度リサイクルして使用することができる。ここで、粒子の平均粒径とは、レーザー測定法の日機装社製マイクロトラックＨＲＡでの平均径を言う。   The solid fine particles having a relatively large particle diameter preferably have an average particle diameter of 4 to 15 μm. Since the solid fine particles have a relatively large particle size, they can be recycled and used again. Here, the average particle diameter of the particles refers to the average diameter of Microtrac HRA manufactured by Nikkiso Co., Ltd. in the laser measurement method.

比較的大粒径の固体微粒子を遠心分離する遠心分離機としては、デカンターバケット型遠心濾過機等の遠心力が５００〜３０００Ｇの遠心力を利用した固液分離機が挙げられる。比較的大粒径の固体微粒子を分級して分離する液体サイクロンとしては、粗細固形粒子を含むスラリーを接線方向に導入し、旋回運動を利用した遠心力で粗粒子と細粒子とを分離するものが挙げられる。粗粒子は下方から濃厚スラリーとして排出され、細粒子は上方向から希釈スラリーとして排出される。第一工程は、遠心分離機や液体サイクロンにより、固形分として比較的大粒径の固体微粒子を分離してもよく、比較的大粒径の固体微粒子を含む液として分離してもよい。   Examples of the centrifuge for centrifuging solid particles having a relatively large particle diameter include a solid-liquid separator using a centrifugal force having a centrifugal force of 500 to 3000 G, such as a decanter bucket type centrifugal filter. A hydrocyclone that classifies and separates solid fine particles with relatively large particle diameters, in which slurry containing coarse and fine solid particles is introduced in the tangential direction, and coarse particles and fine particles are separated by centrifugal force using swirl motion. Is mentioned. Coarse particles are discharged as a concentrated slurry from below, and fine particles are discharged as a diluted slurry from above. In the first step, solid particles having a relatively large particle size as a solid content may be separated by a centrifugal separator or a liquid cyclone, or may be separated as a liquid containing solid particles having a relatively large particle size.

第二工程では、第一工程から排出された液である比較的小粒径の固体微粒子が残存する液に、有機凝集剤を添加して、比較的小粒径の固体微粒子を凝集して凝集体を形成する。その凝集体を含む液を遠心分離機又は濾過機により固形分である凝集体と透明な液分とに固液分離して、凝集体を回収する。   In the second step, an organic flocculant is added to the liquid discharged from the first step, in which solid fine particles having a relatively small particle size remain, and the solid fine particles having a relatively small particle size are aggregated to agglomerate. Form a collection. The liquid containing the aggregate is solid-liquid separated into a solid aggregate and a transparent liquid by a centrifuge or a filter to collect the aggregate.

有機凝集剤としては、例えば、ポリアクルアミド、ポリエチレンアミン、ポリエチレンイミン、各種のカチオン系の有機凝集剤等が挙げられる。特に、下記化学式（１）で示されるカチオン性有機凝集剤が効果的である。   Examples of the organic flocculant include polyacramide, polyethyleneamine, polyethyleneimine, various cationic organic flocculants, and the like. In particular, a cationic organic flocculant represented by the following chemical formula (1) is effective.

Figure 0005795728
式中、Ｒ１は水素原子又はメチル基であり、Ｒ ２ は炭素数１〜１０のアルキル基であり、ＸはＣｌ、Ｂｒ、及びＦから選ばれる何れかのハロゲン化物であり、ａは０〜１０の数、ｂは１〜１０の数、ｍは３以上の数である。
Figure 0005795728
 In the formula, R 1 is a hydrogen atom or a methyl group , R 2 is an alkyl group having 1 to 10 carbon atoms, X is any halide selected from Cl, Br, and F, and a is 0 Is a number of 1 to 10, b is a number of 1 to 10, and m is a number of 3 or more.

これらの有機凝集剤は、無機凝集剤と異なり、後述する粒子の再生において、Ｓｉ微粒子からＳｉＣへの転化やＳｉＣ微粒子の肥大化の際に加熱分解して炭素になるため、無機凝集剤のように残存して不純物とならず、再生における反応原料の一部となり好適である。   Unlike the organic flocculants, these organic flocculants, like the inorganic flocculants, are decomposed into carbon during the regeneration of particles, which will be described later, when they are converted from Si fine particles to SiC or when SiC fine particles are enlarged. Therefore, it remains as an impurity and becomes a part of the reaction raw material in the regeneration.

有機凝集剤の添加量は、第一工程から排出された液１００重量部に対して０．０１〜１０重量部であると好ましい。   The amount of the organic flocculant added is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the liquid discharged from the first step.

第一工程から排出された液に残存する比較的小粒径の固体微粒子（０．１〜５μｍ程度）が凝集して回収される凝集体の平均粒径は、３〜１５μｍであると好ましい。３μｍより小さいと効率よく分離して回収することが困難となる。この比較的小粒径の固体微粒子は、割れやへたりを有していたり、磨耗や細粒化されており、再利用が困難で利用価値が無いものである。そこで、回収された凝集体に、炭素、又は炭素と酸化珪素とを添加して１８００℃以上で加熱することで、利用価値が無いとされる比較的小粒径の固体微粒子から、利用価値が高く比較的大きな粒径を有し、それら粒子の粒度分布が狭い有用なＳｉＣへと再生することができる。   It is preferable that the average particle size of the aggregates collected by agglomerating and recovering solid fine particles (about 0.1 to 5 μm) having a relatively small particle size remaining in the liquid discharged from the first step is 3 to 15 μm. If it is smaller than 3 μm, it is difficult to efficiently separate and collect. The relatively small solid particles have cracks and sags, are worn or refined, are difficult to reuse, and have no utility value. Therefore, by adding carbon or carbon and silicon oxide to the collected agglomerates and heating at 1800 ° C. or more, the utility value is reduced from relatively small solid particles having no utility value. It can be regenerated into useful SiC having a high and relatively large particle size and a narrow particle size distribution of the particles.

本発明の有用なＳｉＣへの再生方法は、比較的小粒径の固体微粒子を凝集して回収した凝集体に、炭素、又は炭素及び酸化珪素、さらに必要に応じて焼結助剤を添加した後、１８００℃以上で加熱反応させることで、比較的小粒径の固体微粒子におけるＳｉＣを肥大化させ、またＳｉからＳｉＣへ転化させて、これら固体微粒子を再生する方法である。ここで、再生とは、微細化されているＳｉＣが粒成長により肥大化して利用価値の高いＳｉＣとなること、またＳｉから新たにＳｉＣが生成すること、その新たに生成したＳｉＣが粒成長により肥大化し利用価値の高いＳｉＣとなることである。これらの再生されるＳｉＣはαＳｉＣであると好ましい。   In the method of regenerating SiC according to the present invention, carbon or carbon and silicon oxide and, if necessary, a sintering aid are added to the aggregate obtained by aggregating and collecting solid fine particles having a relatively small particle size. Thereafter, by heating and reacting at 1800 ° C. or higher, SiC in the solid fine particles having a relatively small particle size is enlarged and converted from Si to SiC to regenerate these solid fine particles. Here, the term “regeneration” means that SiC that is refined is enlarged by grain growth to become SiC having high utility value, SiC is newly generated from Si, and the newly generated SiC is grown by grain growth. It is enlarged and becomes SiC with high utility value. These regenerated SiCs are preferably α SiC.

加熱反応させる温度は、１８００℃以上の高温であると、残存するＳｉＣやＳｉである反応物がαＳｉＣに結晶転移するため好ましく、１８００℃未満であると反応物を完全にαＳｉＣに結晶転移するのが困難である。   When the temperature for the heat reaction is 1800 ° C. or higher, the remaining SiC or Si reactant is preferably crystallized to αSiC, and when it is less than 1800 ° C, the reactant is completely crystallized to αSiC. Is difficult.

添加される炭素は、ＳｉＣとなる反応原料の一部として機能するものであって、残存するＳｉＣを肥大化させる原料、新たにＳｉＣを生成する原料、その新たに生成されるＳｉＣを成長させ肥大化させる原料となるものである。さらにこの炭素は、ＳｉＣの反応原料となるだけでなく、反応し易い環境即ち反応の場として機能し、反応速度や生成するＳｉＣの収率に影響を与える。従って、炭素は粉末や粉体であると好ましく、その粒径は１００μｍ以下であると好ましい。粒径が余り大きいと反応速度が遅くなると共に生成するＳｉＣの収率が低下するため経済的ではない。   The added carbon functions as a part of the reaction raw material that becomes SiC, and is a raw material that enlarges the remaining SiC, a raw material that newly produces SiC, and a newly produced SiC that grows and enlarges. It becomes a raw material to be converted. Furthermore, this carbon not only serves as a reaction raw material for SiC, but also functions as a reactive environment, that is, a reaction field, and affects the reaction rate and the yield of SiC produced. Therefore, carbon is preferably powder or powder, and its particle size is preferably 100 μm or less. If the particle size is too large, the reaction rate becomes slow and the yield of SiC produced decreases, which is not economical.

炭素の添加量は、回収された凝集体の組成により変化する。炭素の添加量は、凝集体におけるＳｉの１．０モルに対して、１．０〜１．５モルであると好ましい。   The amount of carbon added varies depending on the composition of the collected aggregates. The amount of carbon added is preferably 1.0 to 1.5 mol with respect to 1.0 mol of Si in the aggregate.

添加される酸化珪素は、前記の炭素と異なり、生成するＳｉＣの収率に殆ど影響を与えない。しかし、その粒径が余り大き過ぎると反応速度が遅くなるため、得策ではない。酸化珪素は粉末や粉体であると好ましく、その粒径は２００μｍ以下であると好ましい。   The added silicon oxide has little influence on the yield of SiC produced, unlike the carbon. However, if the particle size is too large, the reaction rate becomes slow, which is not a good idea. Silicon oxide is preferably powder or powder, and its particle size is preferably 200 μm or less.

炭素と酸化珪素とが添加される場合、炭素のみが添加される場合と同様で、共に、残存するＳｉＣを肥大化させる原料、新たにＳｉＣを生成する原料、その新たに生成されるＳｉＣを成長させ肥大化させる原料となる。   When carbon and silicon oxide are added, it is the same as when only carbon is added, and the raw material that enlarges the remaining SiC, the raw material that newly generates SiC, and the newly generated SiC are grown. It becomes a raw material to make it enlarge.

炭素及び酸化珪素の添加量は、回収された凝集体の組成により変化する。炭素及び酸化珪素の添加量は、凝集体におけるＳｉＣ及び／又はＳｉの１．０モルに対して、０．１〜１０モルであると好ましい。０．１モル未満の場合、残存するＳｉＣの肥大化が不十分であったり、新たに生成されるＳｉＣの粒径が極めて微小であったり、実用的なＳｉＣを得ることができない。また、１０モル以上の場合、必要量に対して過剰となるため、反応後にその過剰分を除去する工程が必要になると共に必要以上に粒径が大きくなり過ぎる。炭素及び酸化珪素の混合比率は、炭素：酸化珪素＝３〜４：１であると好ましい。   The amount of carbon and silicon oxide added varies depending on the composition of the collected aggregates. The addition amount of carbon and silicon oxide is preferably 0.1 to 10 mol with respect to 1.0 mol of SiC and / or Si in the aggregate. When the amount is less than 0.1 mol, enlargement of the remaining SiC is insufficient, the particle size of newly generated SiC is extremely small, and practical SiC cannot be obtained. When the amount is 10 moles or more, the amount is excessive with respect to the required amount, so that a step of removing the excess after the reaction is required and the particle size becomes excessively large. The mixing ratio of carbon and silicon oxide is preferably carbon: silicon oxide = 3-4: 1.

必要に応じて添加される焼結助剤は、凝集体に、少なくとも炭素、又は炭素及び酸化珪素と共に混合して添加される。焼結助剤としては、一般的に用いられるＳｉＣの焼結助剤を用いることができるが、Ｂ、Ｂ４Ｃ、及びＢ２Ｏ３から選ばれる少なくとも一種であると焼結促進効果が高く好ましい。 The sintering aid added as necessary is added to the agglomerates in a mixture with at least carbon or carbon and silicon oxide. As the sintering aid, a commonly used SiC sintering aid can be used, but if it is at least one selected from B, B 4 C, and B 2 O 3, the sintering promoting effect is high. preferable.

これらの工程により再生され回収されるＳｉＣは、その用途に応じた最適な粒径や粒度分布に調整することができる。例えば、ワイヤーソースラリーにおけるＳｉＣとＳｉとの混合微粉中、ＳｉＣの平均粒径が１μｍ未満まで過度に使用されると切断速度が落ち、生産性が悪くなるため、新しいスラリーと交換される。また平均粒径が２０μｍ以上であると大きな研削傷や切断ロスを多く発生させ易いので通常は用いられない。従って、再生化されたＳｉＣの平均粒径は、１〜２０μｍであると好ましい。   The SiC regenerated and recovered by these steps can be adjusted to an optimum particle size and particle size distribution according to the application. For example, in the mixed fine powder of SiC and Si in the wire saw slurry, if the average particle size of SiC is excessively used to less than 1 μm, the cutting speed is lowered and the productivity is deteriorated. Further, when the average particle size is 20 μm or more, a large grinding flaw and cutting loss are likely to be generated, so that it is not usually used. Therefore, the average particle diameter of the regenerated SiC is preferably 1 to 20 μm.

以下、本発明の実施例を詳細に説明するが、本発明の範囲はこれらの実施例に限定されるものではない。   Examples of the present invention will be described in detail below, but the scope of the present invention is not limited to these examples.

（実施例１）
アチソン法で製造したαＳｉＣを平均粒径１８μｍに粉砕した後、水分級で粗めと細かめとにカットした。粗めにカットしたαＳｉＣは再度、粉砕原料として回した。
第一工程として、平均粒径１０μｍ以下の細かめにカットしたαＳｉＣの水溶液を、ＣＭＳ社製の縦型固液分離装置で１０００〜２０００Ｇで遠心分離し、２μｍ以上の粒子である比較的大粒径の固体微粒子を分離し、回収した。
第二工程として、第一工程から排出された液であって、２μｍ未満の微粒子を多く含有している溶液に、ポリエチレンイミン凝集剤をその溶液１００重量部に対して１重量部を添加し、溶液中の固形分を凝集させた。その後、この溶液をエクセルフィルターで濾過をした。固液分離は微粉が凝集しているため、濾過は容易で濾過速度も速く、濾過液は微粉の混入もなく透明であり、回収された濾過液はリサイクル可能であった。
回収された固形分である凝集体を乾燥し、この乾燥固形分４００Ｋｇに平均粒径８０μｍ、比表面積３９３ｍ２／ｇの木炭粉４８Ｋｇと、平均粒径１２０μｍのシリカ粉７０Ｋｇとをよく混合して再生における反応原料とした。これを、１８５０℃に温度制御したプッシャー炉でＡｒガスの流通下において、容器に入れた反応原料を移動させながら加熱反応させた。得られた反応生成物は、完全にαＳｉＣの結晶であった。さらに大気中、７５０℃で過剰な炭素を除去した。その結果、平均粒径２μｍ未満でこれまで使用することができなかった細かめ部分のαＳｉＣ微粉は平均粒径９．５μｍのαＳｉＣとして、肥大化（粒成長）して再生、回収され有用なＳｉＣ粉となった。このＳｉＣ粉はワイヤーソー用の砥粒として好適なものであった。 Example 1
ΑSiC produced by the Atchison method was pulverized to an average particle size of 18 μm, and then cut into coarse and fine in the moisture class. The coarsely cut αSiC was again used as a pulverized raw material.
As a first step, an α-SiC aqueous solution finely cut with an average particle size of 10 μm or less is centrifuged at 1000 to 2000 G with a vertical solid-liquid separator manufactured by CMS, and the particles are relatively large particles of 2 μm or more. Solid fine particles having a diameter were separated and collected.
As a second step, 1 part by weight of a polyethyleneimine flocculant is added to 100 parts by weight of the solution discharged from the first step and containing a large amount of fine particles of less than 2 μm, Solids in the solution were agglomerated. Thereafter, this solution was filtered with an Excel filter. In the solid-liquid separation, since the fine powder is aggregated, the filtration is easy and the filtration speed is fast, the filtrate is transparent without the inclusion of the fine powder, and the collected filtrate is recyclable.
The collected aggregates are dried, and the dry solid content of 400 kg is well mixed with charcoal powder 48 kg with an average particle size of 80 μm and specific surface area of 393 m 2 / g and silica powder with an average particle size of 120 μm of 70 kg. Used as a reaction raw material in regeneration. This was subjected to a heat reaction in a pusher furnace whose temperature was controlled at 1850 ° C. while moving the reaction raw material in the container under the flow of Ar gas. The obtained reaction product was completely αSiC crystals. Further, excess carbon was removed at 750 ° C. in the atmosphere. As a result, αSiC fine powder in the finer portion, which has not been used so far with an average particle size of less than 2 μm, is enlarged and regenerated and recovered as αSiC with an average particle size of 9.5 μm, which is useful SiC. It became powder. This SiC powder was suitable as an abrasive for a wire saw.

（比較例１）
有機凝集剤を添加しないこと以外は実施例１と同様の条件、方法で回収を行ったところ、微粉のＳｉＣで濾布が目詰まりし、固液分離が困難となった。さらに、わずかに流出した濾液は混濁して濾液に超微粉のＳｉＣが含まれており、完全な固液分離がなされていなかった。 (Comparative Example 1)
Recovery was carried out under the same conditions and method as in Example 1 except that no organic flocculant was added. As a result, the filter cloth was clogged with fine powdered SiC, and solid-liquid separation became difficult. Further, the filtrate that slightly flowed out was turbid, and the filtrate contained ultrafine SiC. Thus, complete solid-liquid separation was not achieved.

（実施例２）
第一工程として、ワイヤーソー廃液（固形成分；αＳｉＣ：３０重量％、Ｓｉ：４．１重量％、Ｆｅ：０．９重量％、溶液成分；エチレングリコール＋界面活性剤＋水混合物６５重量％）から、ＣＭＳ社製の縦型固液分離装置で１０００〜２０００Ｇで遠心分離し、１０μｍ以上の比較的粗い粒子である比較的大粒径の固体微粒子を分離して回収した。
第二工程として、第一工程から排出された液１００重量部に対して、下記化学式（１）で示され、Ｒ１＝メチル基、Ｒ２＝アルキル基、Ｘ＝ハロゲン化物、ａ＝１、ｂ＝５、ｍ＝５、であるカチオン性有機凝集剤０．０２重量部を、第一工程から排出された液に添加し、固形分を凝集させた後、加圧濾過機を用いて３ｋｇ／ｃｍ２の圧力で加圧濾過し、固液分離した。この分離した濾液は透明であった。この濾液はワイヤーソー装置にリサイクル可能であった。
回収された固形分である凝集体を乾燥した後、この乾燥固形分３５０ｋｇに平均粒径１５μｍに粉砕した比表面積５０ｍ２／ｇのコークス７６ｋｇと、平均粒径５０μｍのシリカ粉５０ｋｇとを添加し混合して、再生における反応原料とした。これを１９００℃のロータリー炉でＡｒガス流通下において、加熱反応させた。得られた反応物生成物は、１００％のαＳｉＣで平均粒径８μｍであり、これは使用前のＳｉＣ砥粒の平均粒径８．５μｍとほぼ同じに再生することができた。なお、再生前の廃液中のＳｉＣは平均粒径４μｍでかなりくたびれ、へたったものであった。 (Example 2)
As a first step, wire saw waste liquid (solid component: α SiC: 30% by weight, Si: 4.1% by weight, Fe: 0.9% by weight, solution component; ethylene glycol + surfactant + water mixture 65% by weight) Then, centrifugal separation was performed at 1000 to 2000 G with a vertical solid-liquid separator manufactured by CMS, and solid particles having a relatively large particle size, which was relatively coarse particles of 10 μm or more, were separated and collected.
As the second step, with respect to 100 parts by weight of the liquid discharged from the first step, it is represented by the following chemical formula (1): R 1 = methyl group, R 2 = alkyl group, X = halide, a = 1, 0.02 part by weight of a cationic organic flocculant having b = 5 and m = 5 is added to the liquid discharged from the first step to aggregate the solids, and then 3 kg using a pressure filter. The solution was filtered under pressure at a pressure of / cm 2 and separated into solid and liquid. The separated filtrate was clear. This filtrate could be recycled to the wire saw device.
After drying the aggregate which is the collected solid content, 76 kg of coke having a specific surface area of 50 m 2 / g pulverized to an average particle size of 15 μm and 50 kg of silica powder having an average particle size of 50 μm were added to 350 kg of the dry solid content. It mixed and was used as the reaction raw material in reproduction | regeneration. This was heated and reacted in a 1900 ° C. rotary furnace under Ar gas flow. The obtained reaction product was 100% αSiC and had an average particle size of 8 μm, which could be regenerated almost the same as the average particle size of 8.5 μm of the SiC abrasive grains before use. Note that the SiC in the waste liquid before regeneration was quite heavy with an average particle size of 4 μm, and was sparse.

（実施例２−１）
シリカ粉を添加しないこと以外は実施例２と同様の条件、方法で再生、回収を行った。細粒化したＳｉＣの粒径は肥大化（粒成長）せず、殆ど平均粒径６μｍそのままであり、切子のＳｉ微粉とコークスとの反応で生成した新たなＳｉＣの平均粒径は１μｍで２つのピークを示す広い粒度分布であった。ワイヤーソー等の高度な用途には不向きなものであった。 (Example 2-1)
Regeneration and recovery were performed under the same conditions and method as in Example 2 except that no silica powder was added. The grain size of the refined SiC is not enlarged (granular growth), and the average grain diameter remains almost 6 μm, and the average grain diameter of new SiC produced by the reaction between the faceted Si fine powder and coke is 2 at 1 μm. It was a wide particle size distribution showing two peaks. It was unsuitable for advanced applications such as wire saws.

（実施例３）
第一工程として、単結晶Ｓｉインゴットを円筒研削した際の切子のＳｉ微粒子を含有した廃液を、遠心分離機を用いて１０００〜２０００Ｇで遠心分離し、２μｍ以上の粒子である比較的大粒径の固体微粒子を分離して回収した。
第二工程として、第一工程から排出された液である分離後の残液１００重量部に対して、前記化学式（１）で示され、Ｒ１＝メチル基、Ｒ２＝アルキル基、Ｘ＝ハロゲン化物、ａ＝８、ｂ＝９、ｍ＝２０であるカチオン性有機凝集剤の７重量部を、残液に添加し、微粉を一括、凝集させた後に遠心分離機で、５００〜１０００Ｇで遠心分離し２μｍ未満の超微粒子の固液分離を行った。超微粉は凝集しているため、固液はよく分離し、分離液は無色透明であり、そのまま排水可能であった。
回収された固形分である凝集体を乾燥し、その乾燥固形分２５３Ｋｇ（切子、平均粒径１．１μｍのＳｉ微粒子を２５．３重量％、微量のアミン系防錆材を含有）に、平均粒径３２μｍ、比表面積６９５ｍ２／ｇの活性炭１２４Ｋｇと、平均粒径１７０μｍの石英粉２５Ｋｇとを加え、よく混合して再生における反応原料とした。これを実施例１と同じプシャー式反応炉で１９５０℃に温度制御し、Ａｒガスの流通下において、容器に入れた反応原料を４０分毎に各ゾーンを移動させながら加熱反応させた。反応物生成物は完全にαＳｉＣ化していた。さらに大気中、７５０℃で過剰な炭素を除去した。その結果、平均粒径１μｍ未満の超微粉のＳｉ切子は平均粒径７．５μｍのαＳｉＣとして回収され、有効資源化された。この回収されたαＳｉＣは、ラップ研磨用砥粒やＳｉＣ成形原料用に好適な利用価値の高いものであった。 (Example 3)
As a first step, a waste liquid containing faceted Si fine particles when cylindrically grinding a single crystal Si ingot is centrifuged at 1000 to 2000 G using a centrifuge, and a relatively large particle size of 2 μm or larger particles. The solid fine particles were separated and recovered.
As the second step, 100 parts by weight of the remaining liquid after separation, which is the liquid discharged from the first step, is represented by the chemical formula (1), and R 1 = methyl group, R 2 = alkyl group, X = 7 parts by weight of a halide, a cationic organic flocculant having a = 8, b = 9, m = 20 are added to the remaining liquid, and the fine powder is aggregated in a lump and then centrifuged at 500 to 1000 G. Centrifugation was performed, and solid-liquid separation of ultrafine particles of less than 2 μm was performed. Since the ultrafine powder was agglomerated, the solid liquid was well separated, and the separated liquid was colorless and transparent and could be drained as it was.
Aggregates, which are recovered solids, are dried, and the dry solids are 253 Kg (cut face, 25.3 wt% Si fine particles with an average particle size of 1.1 μm, containing a trace amount of amine-based rust preventive) 124 kg of activated carbon having a particle size of 32 μm and a specific surface area of 695 m 2 / g and 25 kg of quartz powder having an average particle size of 170 μm were added and mixed well to obtain a reaction raw material for regeneration. This was temperature controlled to 1950 ° C. in the same pusher type reactor as in Example 1, and the reaction raw material placed in the container was heated and reacted while moving through each zone every 40 minutes under the flow of Ar gas. The reaction product was completely converted to α SiC. Further, excess carbon was removed at 750 ° C. in the atmosphere. As a result, the ultrafine Si facets having an average particle size of less than 1 μm were recovered as α-SiC having an average particle size of 7.5 μm and turned into effective resources. The recovered α-SiC had high utility value suitable for lapping abrasive grains and SiC forming raw materials.

（比較例２）
カチオン性有機凝集剤の代わりに、アニオン系凝集剤（アクリルアミドアクリル酸ソーダ共重合体）又はノニオン系凝集剤（アクリルアミド共重合体）を、それぞれ添加したこと以外は実施例３と同様の条件、方法で回収を行った。何れの場合もよく凝集せず、その後の遠心分離や濾過での固液の分離も上手くできずに濾過液中に固形分が多く流出してしまった。 (Comparative Example 2)
The same conditions and method as in Example 3 except that an anionic flocculant (acrylamide soda acrylate copolymer) or a nonionic flocculant (acrylamide copolymer) was added in place of the cationic organic flocculant. The recovery was performed. In either case, the agglomeration did not occur well, and the solid and liquid could not be separated successfully by subsequent centrifugation or filtration, so that a large amount of solid content flowed into the filtrate.

（実施例４）
実施例３においてプシャー式反応炉に入れる前の反応原料に、５重量％のＢ４Ｃを添加し混合した。その後の反応及び除炭も実施例３と同一条件で行った。その結果、平均粒子径が１２μｍのαＳｉＣとして再生され、ワイヤーソー用の砥粒として有効なものであった。 Example 4
In Example 3, 5 wt% B 4 C was added to and mixed with the reaction raw material before being put into the pusher reactor. The subsequent reaction and decarburization were also performed under the same conditions as in Example 3. As a result, it was regenerated as α-SiC having an average particle diameter of 12 μm and was effective as an abrasive for a wire saw.

本発明のＳｉＣ及び/又はＳｉの固体微粒子回収方法は、ＳｉＣ粉の製造において副産物として生成する目的粒径以下の不要なＳｉＣ微粒子を含んだ溶液、Ｓｉインゴットや成形物を研削する際の切子のＳｉ微粒子を含有した廃液、ワイヤーソースラリー廃液などの処理として、含有される微細なＳｉＣやＳｉである固形分と液分とを分離、さらにその固形分である各固体微粒子の回収に用いられる。   The SiC and / or Si solid fine particle recovery method of the present invention is a method of cutting a face when grinding a solution, Si ingot or molded product containing unnecessary SiC fine particles having a target particle size or less generated as a by-product in the production of SiC powder. As a treatment of waste liquid containing Si fine particles, wire saw slurry waste liquid, etc., it is used to separate the solid content and liquid content that are fine SiC and Si contained therein, and to recover each solid fine particle that is the solid content.

この固体微粒子回収方法により回収された各固体微粒子は、不要な粒径とされたＳｉＣ微粒子、循環使用で消耗してへたりや微細化したＳｉＣ微粒子、切子のＳｉ微粒子から、用途に応じた最適な粒径や粒度分布を有する利用価値の高いＳｉＣに再生することができる。これらは、ワイヤーソー、ラッピング、ポリシング用等の高付加価値の研削材、砥粒、研磨材として利用される。   Each solid fine particle collected by this solid fine particle recovery method can be selected from SiC fine particles with unnecessary particle size, SiC fine particles that have been exhausted and refined through circulation use, and Si fine particles of facets. Can be regenerated into SiC having a high particle size and particle size distribution and high utility value. These are used as high-value-added abrasives, abrasive grains, and abrasives for wire saws, lapping, polishing, and the like.

Claims (5)

ＳｉＣ及び/又はＳｉの固体微粒子を含む液を、遠心分離又は／及び液体サイクロンにより該固体微粒子中の平均粒径が４〜１５μｍである比較的大粒径の固体微粒子を分離して回収し、平均粒径が０．１〜５μｍである比較的小粒径の固体微粒子が残存する液を排出する第一工程と、
第一工程から排出された液に、下記化学式（１）
Figure 0005795728
 （式中、Ｒ １ は水素原子又はメチル基であり、Ｒ ２ は炭素数１〜１０のアルキル基であり、ＸはＣｌ、Ｂｒ、及びＦから選ばれる何れかのハロゲン化物であり、ａは０〜１０の数、ｂは１〜１０の数、ｍは最小で３の数である）で示されるカチオン性有機凝集剤からなる有機凝集剤を添加して該平均粒径が０．１〜５μｍである比較的小粒径の固体微粒子が平均粒径３〜１５μｍに凝集して形成された凝集体が含まれる液を、遠心分離又は濾過して該凝集体を回収する第二工程とを有する、ＳｉＣ及び/又はＳｉの固体微粒子回収方法。 A liquid containing SiC and / or Si solid fine particles is separated and recovered by centrifugal separation and / or liquid cyclone to separate and collect relatively large solid particles having an average particle size of 4 to 15 μm in the solid fine particles, A first step of discharging a liquid in which solid fine particles having a relatively small particle size having an average particle size of 0.1 to 5 μm remain;
In the liquid discharged from the first step, the following chemical formula (1)
Figure 0005795728
 (Wherein, R 1 is a hydrogen atom or a methyl group, R 2 is an alkyl group having 1 to 10 carbon atoms, X is any halide selected from Cl, Br, and F, and a is The average particle diameter is 0.1 to 10 by adding an organic flocculant composed of a cationic organic flocculant represented by the number 0 to 10, b is a number 1 to 10 and m is a number 3 at the minimum. A second step of collecting the aggregate by centrifuging or filtering a liquid containing an aggregate formed by agglomerating solid microparticles having a relatively small particle size of 5 μm to an average particle diameter of 3 to 15 μm; A method for recovering solid fine particles of SiC and / or Si. 前記第二工程が、前記凝集体が含まれる液を、遠心分離又は濾過して固形分である前記凝集体と透明な液分である液体とに固液分離して、前記凝集体と該液体とを前記回収することを特徴とする請求項１に記載の固体微粒子回収方法。 In the second step, the liquid containing the aggregate is subjected to centrifugal separation or filtration to solid-liquid separation into the solid that is a solid and the liquid that is a transparent liquid, and the aggregate and the liquid The solid fine particle recovery method according to claim 1, wherein the recovery is performed . 第一工程から排出された液１００重量部に対して、前記有機凝集剤を０．０１〜１０重量部とすることを特徴とする請求項１または２に記載の固体微粒子回収方法。   The method for recovering solid fine particles according to claim 1 or 2, wherein the organic flocculant is 0.01 to 10 parts by weight with respect to 100 parts by weight of the liquid discharged from the first step. 請求項１の固体微粒子回収方法により回収した前記凝集体に、炭素、又は炭素と酸化珪素とを添加して非酸化性雰囲気下で最低でも１８００℃で加熱して前記ＳｉＣの平均粒径を肥大化させ、又は前記ＳｉからＳｉＣへ転化させることを特徴とする有用なＳｉＣへの再生方法。   The average particle size of the SiC is increased by adding carbon or carbon and silicon oxide to the aggregate recovered by the solid fine particle recovery method of claim 1 and heating at least 1800 ° C. in a non-oxidizing atmosphere. Or a useful method for regenerating SiC, wherein the Si is converted to SiC. 請求項４に記載の再生方法において、炭素、又は炭素と酸化珪素とともに、Ｂ、Ｂ４Ｃ、及びＢ２Ｏ３から選ばれる何れかの焼結助剤を添加することを特徴とする有用なＳｉＣへの再生方法。 5. The regeneration method according to claim 4, wherein a sintering aid selected from B, B 4 C, and B 2 O 3 is added together with carbon or carbon and silicon oxide. Reproduction method to SiC.
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