JP2021050114A - Granulated body of mixed powder and granulation method - Google Patents
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本発明は、無機物からなる2種以上の粉末が混合された混合粉末の造粒体及び造粒方法に関し、より詳しくは、Liイオン二次電池用負極材の製造原料として好適な、Si粉末及び金属珪酸塩粉末を含む酸化珪素系混合粉末の造粒体及び造粒方法に関する。 The present invention relates to a granulated material and a granulating method of a mixed powder in which two or more kinds of powders made of an inorganic substance are mixed, and more specifically, a Si powder and a Si powder suitable as a raw material for producing a negative electrode material for a Li ion secondary battery. The present invention relates to a granule of a silicon oxide-based mixed powder containing a metal silicate powder and a granulation method.
酸化珪素(SiOx)は電気容量が大きく、寿命特性に優れたLiイオン二次電池用負極材であることが知られている。この酸化珪素系負極材は、酸化珪素粉末、導電助剤及びバインダーを混合してスラリー化したものを、銅箔等からなる集電体上に塗工して薄膜状の負極とされる。ここにおける酸化珪素粉末は、例えばSiの粉末とSiO2の粉末とを混合した珪素系混合粉末を減圧下で加熱して生成したSiOガスを冷却し、析出させた後、そのSiO析出物を細かく破砕することにより得られる。このような析出法で製造される酸化珪素粉末は、アモルファスの部分を多く含み、Liイオンの吸蔵による体積変化を小さくして、サイクル特性を向上させることが知られている。 Silicon oxide (SiOx) is known to be a negative electrode material for Li-ion secondary batteries having a large electric capacity and excellent life characteristics. This silicon oxide-based negative electrode material is obtained by coating a slurry made by mixing silicon oxide powder, a conductive auxiliary agent, and a binder on a current collector made of copper foil or the like to obtain a thin-film negative electrode material. The silicon oxide powder here is, for example, a silicon-based mixed powder obtained by mixing Si powder and SiO 2 powder, which is heated under reduced pressure to cool and precipitate a SiO gas, and then the SiO precipitate is finely divided. Obtained by crushing. It is known that the silicon oxide powder produced by such a precipitation method contains a large amount of amorphous portions, reduces the volume change due to occlusion of Li ions, and improves the cycle characteristics.
このような酸化珪素系負極材に特徴的な問題点として初期効率の低さがある。これは正極のLiが、充放電に寄与しない不可逆容量となるLi化合物の生成に消費されてしまうことが原因である。これを解消する手法として、電池に組み込む前の酸化珪素粉末にLiを添加するLiドープや、その酸化珪素粉末にMgを添加するMgドープが知られており、Liドープの一つの手法として、近時、本出願人はSi粉末と珪酸リチウム粉末とを混合して減圧下で加熱する手法を開発した(特許文献3参照)。 A characteristic problem of such a silicon oxide-based negative electrode material is low initial efficiency. This is because Li on the positive electrode is consumed to produce a Li compound having an irreversible capacity that does not contribute to charging and discharging. As a method for solving this, Li dope in which Li is added to silicon oxide powder before being incorporated into a battery and Mg dope in which Mg is added to the silicon oxide powder are known. At that time, the applicant developed a method of mixing Si powder and lithium silicate powder and heating them under reduced pressure (see Patent Document 3).
ところで、前述した酸化珪素粉末の製造工程、特に、珪素系混合粉末を加熱してSiOガスを発生させるSiOガス発生工程においては、原料である珪素系混合粉末、すなわちSi粉末とSiO2粉末との混合粉末を造粒玉などと称される造粒体に成形して、反応容器内に装填することがしはしば行われる(特許文献1及び2参照)。これは、反応容器内において原料微粒子が発生ガスに乗って製品に混入するのを防ぐこと、及び通気性を向上させることを目的としており、その造粒径は造粒体間における通気性確保の観点から1〜20mmが適当とされている。また、ここにおける造粒方法としては、Si粉末とSiO2粉末との混合粉末を水と混合し、混練して、所定の粒状に成形して乾燥させる湿式造粒法が比較的多く採用されている。 By the way, in the above-mentioned manufacturing process of silicon oxide powder, particularly in the SiO gas generation step of heating a silicon-based mixed powder to generate SiO gas, the silicon-based mixed powder as a raw material, that is, Si powder and SiO 2 powder is used. The mixed powder is often formed into a granulated body called a granulated ball and loaded into a reaction vessel (see Patent Documents 1 and 2). The purpose of this is to prevent the raw material fine particles from getting mixed in the product on the generated gas in the reaction vessel and to improve the air permeability, and the particle size is to ensure the air permeability between the granules. From the viewpoint, 1 to 20 mm is suitable. Further, as a granulation method here, a wet granulation method in which a mixed powder of Si powder and SiO 2 powder is mixed with water, kneaded, formed into predetermined granules and dried is relatively often adopted. There is.
Si粉末とSiO2粉末との混合粉末を水と混合し混練して成形する湿式造粒法の場合、水を使わない乾式造粒法に比べると、造粒体の機械的強度は高い。しかし、実操業においては、その機械的強度は十分とは言えず、造粒体が反応容器内に投入される過程等で解砕して微粉化することにより、原料粉末が製品に混入するとか、或いは反応容器内で所定の粒径が確保されなくなることにより、反応容器内での通気性が不足するといった問題を生じる危険性がある。特に、連続操業のための追加投入を考慮した場合、この危険性が高くなる。 In the case of the wet granulation method in which a mixed powder of Si powder and SiO 2 powder is mixed with water and kneaded for molding, the mechanical strength of the granulated material is higher than that of the dry granulation method that does not use water. However, in actual operation, its mechanical strength is not sufficient, and the raw material powder may be mixed into the product by crushing and pulverizing the granulated material in the process of being put into the reaction vessel. Alternatively, there is a risk that a problem such as insufficient air permeability in the reaction vessel may occur due to the inability to secure a predetermined particle size in the reaction vessel. In particular, this risk is high when considering the additional input for continuous operation.
造粒体の機械的強度を高めるために有機バインダーや無機バインダーを用いることは考えられる。いずれのバインダーの場合も造粒体の機械的強度は上昇するが、バインダー成分が反応の過程でガスを発生させて炉内圧力を上昇させることによる反応性低下が生じたり、バインダー成分そのものが不純物となったりする可能性が高く、実用的とは言えない。 It is conceivable to use an organic binder or an inorganic binder to increase the mechanical strength of the granulated material. In the case of any of the binders, the mechanical strength of the granulated product increases, but the binder component generates gas in the reaction process to increase the pressure in the furnace, resulting in a decrease in reactivity, or the binder component itself is an impurity. There is a high possibility that it will become, and it cannot be said that it is practical.
本発明の目的は、Liイオン二次電池用負極材の製造原料として特に適した酸化珪素系混合粉末の造粒体であって、機械的強度が高く、しかも不純物による汚染の危険が少ない酸化珪素系混合粉末の造粒体及び造粒方法を提供することにある。 An object of the present invention is a granulated material of a silicon oxide-based mixed powder particularly suitable as a raw material for producing a negative electrode material for a Li-ion secondary battery, which has high mechanical strength and a low risk of contamination by impurities. It is an object of the present invention to provide a granulated body of a system mixed powder and a granulated method.
Liイオン二次電池に使用される酸化珪素系負極材に特徴的な問題点として初期効率の低さがあること、その低さを解消する手法として、酸化珪素粉末にLiを添加するLiドープがあること、及びそのLiドープの一つの手法として、Si粉末と珪酸リチウム粉末とを混合して減圧下で加熱する手法を本出願人が先に開発したことは、前述したとおりである。 A characteristic problem of silicon oxide-based negative electrode materials used in Li-ion secondary batteries is low initial efficiency, and as a method to solve this low initial efficiency, Li dope that adds Li to silicon oxide powder is used. As described above, the applicant has previously developed a method of mixing Si powder and lithium silicate powder and heating them under reduced pressure as one method of Li-doping.
この手法によると、Si単体が共存する状況下において珪酸リチウムが減圧下で加熱されることにより、SiOガスとLiガスが同時に発生し、発生ガスを冷却して析出させることにより、SiOとLiが均一に混合した析出体が得られる。その結果、この析出体を粉砕して粉末化すると、そのLi含有SiO粉末は、粉末粒子間におけるLi濃度分布の不均一も、個々の粉末粒子中におけるLi濃度分布の不均一も共に解消された、均質性の高い負極材が得られる。 According to this method, when lithium silicate is heated under reduced pressure in the situation where Si alone coexists, SiO gas and Li gas are generated at the same time, and the generated gas is cooled and precipitated to generate SiO and Li. A uniformly mixed precipitate is obtained. As a result, when this precipitate was pulverized and pulverized, both the non-uniformity of the Li concentration distribution among the powder particles and the non-uniformity of the Li concentration distribution in the individual powder particles of the Li-containing SiO powder were eliminated. , A negative electrode material with high homogeneity can be obtained.
この負極材は、負極材用粉末粒子中におけるLi濃度分布の不均一と、粉末粒子間におけるLi濃度分布の不均一の両方が共に解消されることにより、Li濃度分布の不均一に起因する電池性能の低下を効果的に回避して、電池性能の大幅向上を図ることが可能である。 This negative electrode material is a battery caused by non-uniformity of Li concentration distribution by eliminating both non-uniformity of Li concentration distribution in powder particles for negative electrode material and non-uniformity of Li concentration distribution among powder particles. It is possible to effectively avoid the deterioration of the performance and greatly improve the battery performance.
本発明者は、この負極材の開発に当初より深く関与しており、その過程で今回、Si粉末と珪酸リチウム粉末との混合粉末は、電池性能の向上に貢献するばかりでなく、造粒玉等と呼ばれる造粒体の製造に極めて高い適性を示すことを知見した。すなわち、Si粉末と珪酸リチウム粉末とを含む混合粉末は、水のみによる造粒を行っても、バインダーを使用したときに匹敵する高い機械的強度を造粒体に付与できることが、本発明者による調査検討の結果、判明したのである。 The present inventor has been deeply involved in the development of this negative electrode material from the beginning, and in the process, this time, the mixed powder of Si powder and lithium silicate powder not only contributes to the improvement of battery performance, but also the granulated balls. It was found that it shows extremely high suitability for the production of granules called. That is, according to the present inventor, the mixed powder containing Si powder and lithium silicate powder can impart high mechanical strength comparable to that when a binder is used to the granulated material even when granulated only with water. As a result of investigation and examination, it became clear.
本発明は、かかる知見を基礎として開発されたものであり、その造粒体はSi粉末と金属珪酸塩粉末を原料の全部又は一部とし、水のみによる混練成形により造粒されたバインダーレス造粒体である。 The present invention has been developed based on such findings, and the granulated material is a binderless structure obtained by kneading with only water using Si powder and metal silicate powder as all or a part of the raw materials. It is a granular material.
また、本発明の造粒方法は、Si粉末と金属珪酸塩粉末とを原料の全部又は一部とし、これらの原料粉末を混合した後に水のみを用いて混練し、成形した後に乾燥させるバインダーレス造粒体の製造方法である。 Further, the granulation method of the present invention uses Si powder and metal silicate powder as all or a part of raw materials, mixes these raw material powders, kneads them with water only, molds them, and then dries them without a binder. This is a method for producing a granulated material.
本発明のバインダーレス造粒体は、Li含有SiO粉末、Mg含有SiO粉末といった金属元素含有SiO粉末の製造原料として主に使用される。例えば、金属珪酸塩として珪酸リチウムを用いた場合は、Li含有SiOの製造原料となり、珪酸マグネシウムを用いた場合は、Mg含有SiOの製造原料となる。これらの製造原料を減圧下で加熱してガスを発生させ、発生したガスを冷却することにより、珪酸リチウムの場合はLi含有SiOの析出体が得られ、珪酸マグネシウムの場合はMg含有SiOの析出体が得られる。これらの析出体を粉砕して得た粉末の造粒体が、均質性の高い負極材の製造原料となることは前述したとおりである。 The binderless granulated material of the present invention is mainly used as a raw material for producing metal element-containing SiO powder such as Li-containing SiO powder and Mg-containing SiO powder. For example, when lithium silicate is used as the metal silicate, it becomes a raw material for producing Li-containing SiO, and when magnesium silicate is used, it becomes a raw material for producing Mg-containing SiO. By heating these production raw materials under reduced pressure to generate gas and cooling the generated gas, a Li-containing SiO precipitate is obtained in the case of lithium silicate, and a Mg-containing SiO precipitate in the case of magnesium silicate. The body is obtained. As described above, the powder granules obtained by pulverizing these precipitates can be used as a raw material for producing a negative electrode material having high homogeneity.
珪酸リチウム、珪酸マグネシウム以外の金属珪酸塩としては、珪酸バリウム、珪酸カルシウムなどがある。珪酸カリウム、珪酸ナトリウムなどもあるが、これらは水に非常に溶けやすく、また、その水溶液のpHが高くなるため、水を用いたバインダーレス造粒体の原料粉末としては適さない。 Examples of metal silicates other than lithium silicate and magnesium silicate include barium silicate and calcium silicate. Potassium silicate, sodium silicate, etc. are also available, but these are very soluble in water and the pH of the aqueous solution is high, so that they are not suitable as raw material powders for binderless granules using water.
珪酸リチウムについても、これはLi2OとSiO2の複合酸化物であり、Li2O比が高いLi4SiO4、或いはそれ以上にLi2O比が高いものは、水と混合したときに水に溶けるのではなく、水と激しく反応して強いアルカリと熱を生じ、Si粉末と水の反応を促進するため、水を用いたバインダーレス造粒体の原料粉末としては適さない。 As for lithium silicate, this is a composite oxide of Li 2 O and SiO 2 , and Li 4 SiO 4 having a high Li 2 O ratio or a higher Li 2 O ratio is when mixed with water. It does not dissolve in water, but reacts violently with water to generate strong alkali and heat, which promotes the reaction between Si powder and water, so it is not suitable as a raw material powder for binderless granules using water.
すなわち、金属珪酸塩が珪酸リチウムの場合は、モル比でLi2O/SiO2<2であれば、水を用いたバインダーレス造粒体の原料粉末に用いることが可能であり、好ましくはLi2O/SiO2≦1、更に好ましくはLi2O/SiO2≦0.5である。 That is, when the metal silicate is lithium silicate, if the molar ratio is Li 2 O / SiO 2 <2, it can be used as a raw material powder for a binderless granule using water, and Li is preferable. 2 O / SiO 2 ≦ 1, more preferably Li 2 O / SiO 2 ≦ 0.5.
このような金属珪酸塩粉末とSi粉末とを含む混合粉末を水と混合し混練して造粒すると、図1A及び図1Bに示すように、混合粉末中の金属珪酸塩粉末が水に僅かに溶けて、その水を適度にアルカリ化する。そして、その弱アルカリ性の水がSi粉末の表面に形成されているSiO2皮膜を僅かに溶かすことにより、SiO2皮膜がバインダーの役目を果たす。その結果、混合粉末を混練するための液体として水しか使用しないにもかかわらず、バインダーを使用したのと同様に、金属珪酸塩粉末とSi粉末の粉末同士が強固に接着され、製造される造粒体の機械的強度が向上する。 When such a mixed powder containing the metal silicate powder and the Si powder is mixed with water and kneaded for granulation, as shown in FIGS. 1A and 1B, the metal silicate powder in the mixed powder is slightly mixed with water. It dissolves and moderately alkalizes the water. Then, the weakly alkaline water slightly dissolves the SiO 2 film formed on the surface of the Si powder, so that the SiO 2 film acts as a binder. As a result, even though only water is used as the liquid for kneading the mixed powder, the metal silicate powder and the Si powder powder are firmly adhered to each other and manufactured in the same manner as when a binder is used. The mechanical strength of the granules is improved.
水を用いたバインダーレス造粒体の原料粉末として適する金属珪酸塩の種類については、前述の各種金属珪酸塩以外にも、その金属珪酸塩粉末2gを純水100gに投入して作製した25°Cの懸濁液のpHが9〜12を示すものは、水を用いたバインダーレス造粒体の原料粉末として適する。ここにおける懸濁液のpHは、11.5以下が特に好ましい。混練用の水のpHが低いと、Si粉末の表面に形成されたSiO2皮膜の溶解が生じない。反対に、この水のpHが高すぎると、SiO2皮膜の溶解が進み、内部のSiが、水と下記の化学式(1)に示される化学反応を連続的に起こして、熱と水素を生じるために危険である。また、反応原料としてのSiが酸化されるために品質上も問題が生じる。 Regarding the type of metal silicate suitable as a raw material powder for binderless granules using water, in addition to the above-mentioned various metal silicates, 2 g of the metal silicate powder was added to 100 g of pure water to prepare 25 °. A suspension of C having a pH of 9 to 12 is suitable as a raw material powder for a binderless granule using water. The pH of the suspension here is particularly preferably 11.5 or less. When the pH of the kneading water is low, the SiO 2 film formed on the surface of the Si powder does not dissolve. On the contrary, if the pH of this water is too high, the SiO 2 film dissolves, and the Si inside continuously causes a chemical reaction represented by the following chemical formula (1) with water to generate heat and hydrogen. Because it is dangerous. In addition, since Si as a reaction raw material is oxidized, a problem arises in terms of quality.
Si+2H2O→SiO2+2H2↑・・・(1) Si + 2H 2 O → SiO 2 + 2H 2 ↑ ・ ・ ・ (1)
水を用いたバインダーレス造粒体の原料粉末として適する前述の各種金属珪酸塩は、言うまでもなく、この条件を満たし、その粉末2gを純水100gに投入して作製した25℃の懸濁液のpHが9〜12を示す。ただし、金属珪酸塩が同じ化合物であっても、その粉末の粒度、不純物量等によって、このpHは微妙に変化する。使用する金属珪酸塩粉末の懸濁液がこの条件を満たすことが重要である。 Needless to say, the above-mentioned various metal silicates suitable as raw material powders for binderless granules using water satisfy this condition, and 2 g of the powder is added to 100 g of pure water to prepare a suspension at 25 ° C. The pH shows 9-12. However, even if the metal silicate is the same compound, this pH changes slightly depending on the particle size of the powder, the amount of impurities, and the like. It is important that the suspension of metal silicate powder used meets this requirement.
また、同じpHであっても造粒中(混練、成形中)の水温が高いとSiO2の溶解が激しくなり、やはり前述の問題が生じる。このため、造粒中(混練、成形中)の水温は30℃以下が望ましく、15℃以下が更に望ましく、5℃以下が特に望ましい。 Further, even if the pH is the same, if the water temperature during granulation (during kneading and molding) is high, the dissolution of SiO 2 becomes intense, and the above-mentioned problem also occurs. Therefore, the water temperature during granulation (during kneading and molding) is preferably 30 ° C. or lower, more preferably 15 ° C. or lower, and particularly preferably 5 ° C. or lower.
造粒体を構成する混合粉末の組成については、この混合粉末がLiイオン二次電池用負極材の製造原料であるという観点から、混合後の粉末のモル比で表して、0.8≦O/Si≦1.2であることが望ましい。O/Siが1に比して小さすぎると、余剰のSiが炉内に残留して連続操業の妨げになり、逆に1に比して大きすぎると、余剰の珪酸塩が炉内に残留して同じく連続操業の妨げになる。 Regarding the composition of the mixed powder constituting the granules, from the viewpoint that this mixed powder is a raw material for producing a negative electrode material for a Li ion secondary battery, it is expressed as a molar ratio of the mixed powder, 0.8 ≦ O. It is desirable that / Si ≦ 1.2. If O / Si is too small compared to 1, excess Si remains in the furnace and hinders continuous operation, and conversely, if it is too large compared to 1, excess silicate remains in the furnace. It also hinders continuous operation.
造粒体の機械的強度に関しては、Si粉末、珪酸塩粉末ともに粒度が小さい方が表面積が増え、接着点が多くなるために、その強度が上昇するが、小さくなり過ぎた場合はpHが高くなり過ぎたり,化学式1の反応が進みすぎたりするために、適度な粒度であることが重要である。この観点から、Si粉末の粒度は、平均粒径で1〜18μmが望ましく、1〜10μmが更に望ましく、1〜5μmが特に望ましい。金属珪酸塩粉末の粒度については、金属元素にもよるが、一般的には平均粒径で1〜30μmが望ましく、1〜20μmが更に望ましく、1〜15μmが特に望ましい。珪酸リチウム粉末の場合は、まさにこの粒径範囲が適切である。 Regarding the mechanical strength of the granules, the smaller the particle size of both Si powder and silicate powder, the larger the surface area and the more adhesive points, so the strength increases, but if it becomes too small, the pH is high. It is important that the particle size is appropriate because it may become too large or the reaction of Chemical Formula 1 may proceed too much. From this viewpoint, the particle size of the Si powder is preferably 1 to 18 μm, more preferably 1 to 10 μm, and particularly preferably 1 to 5 μm in terms of average particle size. The particle size of the metal silicate powder depends on the metal element, but generally, the average particle size is preferably 1 to 30 μm, more preferably 1 to 20 μm, and particularly preferably 1 to 15 μm. In the case of lithium silicate powder, this exact particle size range is appropriate.
なお、本発明において、平均粒径とは、レーザ回折式の粒度分布計を用いて体積基準の粒度分布を測定した場合のメディアン径、いわゆるD50のことをいう。 In the present invention, the average particle size refers to the median diameter, the so-called D 50 in the case of measuring the particle size distribution based on volume using a particle size distribution meter of the laser diffraction.
造粒体の直径、すなわち造粒径については0.25〜10mmが望ましく、0.5〜8mmが更に望ましく、0.5〜5mmが特に望ましい。造粒径が大きすぎる場合は、造粒体が落下したときの衝撃が大きくなり過ぎて解砕が生じやすくなる。反対に小さすぎる場合は造粒体の流動性が悪化し、追加の投入が困難となる。 The diameter of the granules, that is, the particle size, is preferably 0.25 to 10 mm, more preferably 0.5 to 8 mm, and particularly preferably 0.5 to 5 mm. If the particle size is too large, the impact when the granulated material is dropped becomes too large and crushing is likely to occur. On the other hand, if it is too small, the fluidity of the granulated material deteriorates and it becomes difficult to add additional material.
造粒体を製造するための装置は、公知の装置を用いることができる。例えばSi粉末と金属珪酸塩粉末との混合には公知のV型混合機などを用いることができる。混練、成形は手でこねることでも可能であるし、パン型造粒機やディスクペレッタ、流動層式造粒機などを用いることでも可能である。 As an apparatus for producing the granulated material, a known apparatus can be used. For example, a known V-type mixer or the like can be used for mixing the Si powder and the metal silicate powder. Kneading and molding can be performed by kneading by hand, or by using a pan-type granulator, a disc peretta, a fluidized bed granulator, or the like.
乾燥には一般的な加熱乾燥の他に、減圧乾燥も用いることができる。加熱乾燥では一次的に化学式1の反応が促進されるが、温度が高いために乾燥が速い。乾燥すれば、化学式1の反応は停止する。減圧乾燥を用いれば、加熱せずに乾燥させることができるため、化学式1の反応を最小限に抑制することができる。但し、加熱乾燥に比べてバインダーとして働くSiO2が少なくなり、強度は劣る傾向となる。 In addition to general heat drying, vacuum drying can also be used for drying. In heat drying, the reaction of Chemical Formula 1 is primaryly promoted, but the drying is fast due to the high temperature. Once dried, the reaction of Chemical Formula 1 ceases. If vacuum drying is used, it can be dried without heating, so that the reaction of Chemical Formula 1 can be suppressed to a minimum. However, compared to heat drying, the amount of SiO 2 that acts as a binder is reduced, and the strength tends to be inferior.
本発明の混合粉末の造粒体及び造粒方法は、Si粉末と金属珪酸塩粉末とを含む混合粉末を混練形成して造粒するに当たり、混練形成のための液体として水を使用し、バインダーを使用しないにもかかわらず、バインダーを使用したときに匹敵する機械的強度を造粒体に付与することができる。このため、造粒体の使用過程での解砕が抑制され、反応容器内での通気性の悪化を回避できる。また、バインダー成分による汚染の危険性へ回避できる。 In the granulated material and granulating method of the mixed powder of the present invention, water is used as a liquid for kneading and forming a binder when the mixed powder containing Si powder and metal silicate powder is kneaded and formed. Despite not using, it is possible to impart mechanical strength comparable to that when using a binder to the granulated material. Therefore, crushing in the process of using the granulated material is suppressed, and deterioration of air permeability in the reaction vessel can be avoided. In addition, the risk of contamination by the binder component can be avoided.
以下に本発明の実施形態として、Liイオン二次電池用負極材の製造原料として使用される混合粉末の造粒体及び造粒方法を、典型例について説明する。 Hereinafter, as an embodiment of the present invention, a typical example of a granulated material and a granulated method of a mixed powder used as a raw material for producing a negative electrode material for a Li-ion secondary battery will be described.
事前段階として、Si粉末及び金属珪酸塩粉末を製造する。Si粉末については、Siウエハをボールミルで粉砕し、粒度を調整することにより、所定の粒度のSi粉末を製造することができる。Si粉末の粒度は、前述したとおり、平均粒径で1〜18μmが望ましく、1〜10μmが更に望ましく、1〜5μmが特に望ましい。 As a preliminary step, Si powder and metal silicate powder are produced. With respect to the Si powder, the Si powder having a predetermined particle size can be produced by crushing the Si wafer with a ball mill and adjusting the particle size. As described above, the particle size of the Si powder is preferably 1 to 18 μm, more preferably 1 to 10 μm, and particularly preferably 1 to 5 μm in terms of average particle size.
金属珪酸塩粉末については、所定金属の炭酸塩又は酸化物をSiO2と所定の比率で混合した後に融点以上に加熱して金属珪酸塩を作製した後、ボールミルで粒度を調整することにより、所定の粒度の金属珪酸塩粉末を作製することができる。 For the metal silicate powder, a carbonate or oxide of a predetermined metal is mixed with SiO 2 at a predetermined ratio and then heated to a temperature equal to or higher than the melting point to prepare a metal silicate, and then the particle size is adjusted with a ball mill. It is possible to prepare a metal silicate powder having a particle size of.
ここにおける金属珪酸塩粉末は、例えば珪酸リチウムであり、その珪酸リチウムは、モル比でLi2/SiO2<2を満足するものが好ましく、更に好ましくはLi2/SiO2≦1、特に好ましくはLi2/SiO2≦0.5を満足するものである。また、当該粉末2gを純水100gに投入したときに、25℃でpHが9〜12を示す懸濁液を生成可能である。 The metal silicate powder here is, for example, lithium silicate, and the lithium silicate preferably satisfies Li 2 / SiO 2 <2 in terms of molar ratio, more preferably Li 2 / SiO 2 ≦ 1, and particularly preferably. It satisfies Li 2 / SiO 2 ≤ 0.5. Further, when 2 g of the powder is added to 100 g of pure water, a suspension having a pH of 9 to 12 at 25 ° C. can be produced.
金属珪酸塩粉末の粒度は、前述したとおり、平均粒径で1〜30μmが望ましく、1〜20μmが更に望ましく、1〜15μmが特に望ましい。いずれの粉末についても、粒度は、レーザ回折式の粒度分布測定装置により測定しておく。粒度分布測定条件は以下のとおりである。 As described above, the particle size of the metal silicate powder is preferably 1 to 30 μm, more preferably 1 to 20 μm, and particularly preferably 1 to 15 μm in terms of average particle size. The particle size of each powder is measured by a laser diffraction type particle size distribution measuring device. The particle size distribution measurement conditions are as follows.
粒度分布測定条件
装置: マルバーン・パナリティカル 社製 Mastersizer 2000
分散媒:イソプロピルアルコール
粒子屈折率:実数部1.544 虚数部1
分散媒屈折率:1.390
Particle size distribution measurement condition device: Mastersizer 2000 manufactured by Malvern PANalytical Co., Ltd.
Dispersion medium: Isopropyl alcohol particles Refractive index: Real part 1.544 Imaginary part 1
Dispersion medium refractive index: 1.390
Si粉末及び金属珪酸塩粉末が製造されると、第1段階として、製造されたSi粉末と金属珪酸塩粉末とを混合する。製造されたSi粉末と金属珪酸塩粉末との混合は、V型混合機により行うことができる。必要に応じて、O量調整のためのSiO2粉末等を混合することができる。混合粉末の組成は、混合後の粉末のモル比で表して、0.8≦O/Si≦1.2であることが望ましい。 When the Si powder and the metal silicate powder are produced, as a first step, the produced Si powder and the metal silicate powder are mixed. The produced Si powder and the metal silicate powder can be mixed by a V-type mixer. If necessary, SiO 2 powder or the like for adjusting the amount of O can be mixed. The composition of the mixed powder is preferably 0.8 ≦ O / Si ≦ 1.2 in terms of the molar ratio of the mixed powder.
ここにおけるSi濃度は、Li濃度などと同様に、ICP発光分析によって求めることができる。O濃度については、LECO社製 TC-436 を使用して、不活性ガス融解−赤外線吸収法(inert gas fusion infrared absorption method;GFA )により測定することができる。 The Si concentration here can be determined by ICP emission analysis as well as the Li concentration and the like. The O concentration can be measured by the inert gas fusion infrared absorption method (GFA) using TC-436 manufactured by LECO.
また、金属珪酸塩粉末の特性調査のために、混合前の金属珪酸塩粉末2gを100gの純水に投入して攪拌し、懸濁液を作製して、そのpHを測定しておく。pH測定条件は以下のとおりである。 Further, in order to investigate the characteristics of the metal silicate powder, 2 g of the metal silicate powder before mixing is put into 100 g of pure water and stirred to prepare a suspension, and the pH thereof is measured. The pH measurement conditions are as follows.
pH測定条件
装置:HORIBA製 F-72
電極内部液:HORIBA製 比較電極内部液300
校正に用いる標準液:HORIBA製 pH標準液 100-4 (フタル酸塩標準液)
HORIBA製 pH標準液 100-7 (中性リン酸塩標準液)
HORIBA製 pH標準液 100-9 (ホウ酸塩標準液)
pH measurement condition device: HORIBA F-72
Electrode internal liquid: HORIBA comparative electrode internal liquid 300
Standard solution used for calibration: HORIBA pH standard solution 100-4 (phthalate standard solution)
HORIBA pH standard solution 100-7 (neutral phosphate standard solution)
HORIBA pH standard solution 100-9 (borate standard solution)
Si粉末と金属珪酸塩粉末とを含む混合粉末が作製されると、第2段階として、混合粉末を水により造粒する。すなわち、混合粉末を水により混練し、粒状に成形する。造粒機としてはアーステクニカ製ハイスピードミキサーを使用することができる。水と混合粉末は、ここでは重量比で10:90の割合で造粒機に投入する。 When a mixed powder containing the Si powder and the metal silicate powder is prepared, as a second step, the mixed powder is granulated with water. That is, the mixed powder is kneaded with water and molded into granules. As a granulator, an EarthTechnica high-speed mixer can be used. The water and the mixed powder are charged into the granulator at a weight ratio of 10:90 here.
造粒後に造粒機から排出された造粒体を目開き500μm、目開き10mmの篩で分級することにより、微粉と粗粒を除去する。分級後の造粒体を棚型乾燥機を用いて120℃で12hr乾燥する。乾燥後の造粒体を構成する粉末のSi濃度及びO濃度を、混合後の粉末の場合と同様にして測定する。また、乾燥後の造粒体をJIS Z8841に規定される造粒物の落下強度試験に供して、その機械的強度を測定する。落下強度試験における落下操作は1回のみとし、落下操作後に使用するふるいの目開きは250μmとした。 Fine powder and coarse particles are removed by classifying the granulated material discharged from the granulator after granulation with a sieve having a mesh size of 500 μm and a mesh size of 10 mm. The granulated material after classification is dried at 120 ° C. for 12 hours using a shelf-type dryer. The Si concentration and the O concentration of the powder constituting the granulated material after drying are measured in the same manner as in the case of the powder after mixing. Further, the dried granules are subjected to a drop strength test of the granules specified in JIS Z8841 to measure the mechanical strength thereof. In the drop strength test, the drop operation was performed only once, and the mesh size of the sieve used after the drop operation was 250 μm.
上記実施形態で説明した方法により実際に造粒を行った結果を、実施例として以下に説明し、合わせて比較例を示す。また、各例における各種数値を表1に整理して示す。 The result of actually granulating by the method described in the above embodiment will be described below as an example, and a comparative example is also shown. Table 1 shows various numerical values in each example.
(実施例1−1)
Si粉末と、金属珪酸塩粉末であるLi2Si2O5とをV型混合機により混合し、その混合粉末を造粒機(アーステクニカ製ハイスピードミキサー)により混練して粒状に成形した後、棚型乾燥機により乾燥した。造粒機内では適宜常温の水を加え、乾燥後の強度を最適化した。
(Example 1-1)
After mixing Si powder and Li 2 Si 2 O 5 which is a metal silicate powder with a V-type mixer and kneading the mixed powder with a granulator (High Speed Mixer manufactured by EarthTechnica) to form granules. , Dried by a shelf-type dryer. In the granulator, water at room temperature was added as appropriate to optimize the strength after drying.
Li2Si2O5は〔x(Li2O)+y(SiO2)〕(x=1,y=2)であり、Li2O/SiO2=0.5である。 Li 2 Si 2 O 5 is [x (Li 2 O) + y (SiO 2 )] (x = 1, y = 2), and Li 2 O / SiO 2 = 0.5.
Li2Si2O5粉末の粒度は平均粒径で15μmである。Si粉末の粒度は平均粒径で2.5μmである。混合粉末のO/Siモル比は1である。造粒径は0.5〜10mmである。 The particle size of the Li 2 Si 2 O 5 powder is 15 μm on average. The average particle size of the Si powder is 2.5 μm. The O / Si molar ratio of the mixed powder is 1. The particle size is 0.5 to 10 mm.
造粒体を乾燥した後、その造粒体を構成する混合粉末のO/Siモル比を測定したが、1.1であり、O濃度比が上昇したこと、すなわち造粒過程でSiの酸化反応が発生したことが確認された。この酸化反応に伴って水素が発生したが、水素発生量は少量であり、このことはO濃度比の変化からも明らかである。ここにおける水素発生量は、5段階評価で中間の「3」であり、「5」は造粒が困難な領域である。 After the granulated material was dried, the O / Si molar ratio of the mixed powder constituting the granulated material was measured and found to be 1.1, indicating that the O concentration ratio increased, that is, the oxidation of Si during the granulation process. It was confirmed that the reaction had occurred. Hydrogen was generated along with this oxidation reaction, but the amount of hydrogen generated was small, which is clear from the change in the O concentration ratio. The amount of hydrogen generated here is an intermediate "3" on a 5-point scale, and "5" is a region where granulation is difficult.
また、造粒とは別に、ここで用いたLi2Si2O5粉末2gを純水100gと混合して作製した懸濁液は、25℃でpH=11.2を示した。 In addition to granulation, the suspension prepared by mixing 2 g of the Li 2 Si 2 O 5 powder used here with 100 g of pure water showed pH = 11.2 at 25 ° C.
そして、乾燥後の造粒体の機械的強度を測定したが、Si粉末とSiO2粉末を水と混合して造粒した場合と比べて格段に向上した。そして、ここにおける造粒体の機械的強度を「100」とし、Si粉末とSiO2粉末を水と混合して造粒した場合を「20」として、造粒体の機械的強度を相対評価した。ちなみに、Si粉末とSiO2粉末を水と混合して造粒した例は、後に比較例1として示されている。 Then, the mechanical strength of the granulated material after drying was measured, and it was significantly improved as compared with the case where Si powder and SiO 2 powder were mixed with water and granulated. Then, the mechanical strength of the granulated material was set to "100", and the case where Si powder and SiO 2 powder were mixed with water to granulate was set to "20", and the mechanical strength of the granulated material was relatively evaluated. .. Incidentally, an example in which Si powder and SiO2 powder are mixed with water and granulated is shown later as Comparative Example 1.
(実施例1−2)
Si粉末の粒度を平均粒径で6.5μmに大きくした。これ以外は実施例1−1と同じである。
(Example 1-2)
The particle size of the Si powder was increased to 6.5 μm on average. Other than this, it is the same as in Example 1-1.
実施例1−1と比べて、混合粉末を水と混合して混練、成形したときのSiの酸化反応が抑制されている。その一方で、造粒体の機械的強度が若干低下した。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder is mixed with water, kneaded and molded is suppressed. On the other hand, the mechanical strength of the granules was slightly reduced.
(実施例1−3)
Si粉末の粒度を平均粒径で10μmと更に大きくした。これ以外は実施例1−1と同じである。
(Example 1-3)
The particle size of the Si powder was further increased to 10 μm on average. Other than this, it is the same as in Example 1-1.
実施例1−1と比べて、混合粉末を水と混合して混練、成形したときのSiの酸化反応が更に抑制されている。その一方で、造粒体の機械的強度が更に少し低下した。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder is mixed with water, kneaded and molded is further suppressed. On the other hand, the mechanical strength of the granules was further reduced.
(実施例1−4)
Si粉末の粒度を平均粒径で15μmと更に大きくした。これ以外は実施例1−1と同じである。
(Example 1-4)
The particle size of the Si powder was further increased to 15 μm on average. Other than this, it is the same as in Example 1-1.
実施例1−1と比べて、混合粉末を水と混合して混練、成形したときのSiの酸化反応が更に抑制されている。その一方で、造粒体の機械的強度が更に少し低下した。機械的強度の評価は「50」であり、後述する比較例1での造粒体の機械的強度の評価が「20」であることを考えると、評価が「50」までは十分に満足できるレベルである。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder is mixed with water, kneaded and molded is further suppressed. On the other hand, the mechanical strength of the granules was further reduced. The evaluation of the mechanical strength is "50", and considering that the evaluation of the mechanical strength of the granulated material in Comparative Example 1 described later is "20", the evaluation up to "50" is sufficiently satisfactory. It is a level.
(実施例1−5)
金属珪酸塩粉末としてのLi2Si2O5粉末の粒度を、実施例1−1と比べ、平均粒径で12μmと小さくした。これ以外は実施例1−1と同じである。
(Example 1-5)
The particle size of the Li 2 Si 2 O 5 powder as the metal silicate powder was reduced to 12 μm in average particle size as compared with Example 1-1. Other than this, it is the same as in Example 1-1.
実施例1−1と比べて、混合粉末を水と混合して混練、成形したときのSiの酸化反応が活発化し、水素発生量の評価が「3」から「4」に上昇した。その一方で、造粒体の機械的強度が若干上昇した。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder was mixed with water, kneaded and molded became active, and the evaluation of the amount of hydrogen generated increased from "3" to "4". On the other hand, the mechanical strength of the granules increased slightly.
ここで用いたLi2Si2O5粉末2gを純水100gと混合して作製した懸濁液は、25℃でpH=11.3を示し、アルカリ度が若干上昇した。Siの酸化反応が活発化したのはこのためと考えられる。 The suspension prepared by mixing 2 g of Li 2 Si 2 O 5 powder used here with 100 g of pure water showed pH = 11.3 at 25 ° C., and the alkalinity was slightly increased. It is considered that this is the reason why the oxidation reaction of Si is activated.
(実施例1−6)
金属珪酸塩粉末としてのLi2Si2O5粉末の粒度を、実施例1−1と比べ、平均粒径で20μmと大きくした。これ以外は実施例1−1と同じである。
(Example 1-6)
The particle size of the Li 2 Si 2 O 5 powder as the metal silicate powder was increased to 20 μm in average particle size as compared with Example 1-1. Other than this, it is the same as in Example 1-1.
実施例1−5と比べて、混合粉末を水と混合して混練、成形したときのSiの酸化反応が抑制され、実施例1−1と同程度に戻った。水素発生量の評価も「3」に戻った。その一方で、造粒体の機械的強度が若干低下した。 Compared with Example 1-5, the oxidation reaction of Si when the mixed powder was mixed with water, kneaded and molded was suppressed, and returned to the same level as in Example 1-1. The evaluation of the amount of hydrogen generated also returned to "3". On the other hand, the mechanical strength of the granules was slightly reduced.
ここで用いたLi2Si2O5粉末2gを純水100gと混合して作製した懸濁液は、25℃でpH=11.0を示し、アルカリ度が若干低下した。Siの酸化反応が抑制されたのはこのためと考えられる。 The suspension prepared by mixing 2 g of Li 2 Si 2 O 5 powder used here with 100 g of pure water showed pH = 11.0 at 25 ° C., and the alkalinity was slightly lowered. It is considered that this is the reason why the oxidation reaction of Si was suppressed.
(実施例1−7)
金属珪酸塩粉末としてのLi2Si2O5粉末の粒度を、実施例1−1と比べ、平均粒径で30μmと更に大きくした。これ以外は実施例1−1と同じである。
(Example 1-7)
The particle size of the Li 2 Si 2 O 5 powder as the metal silicate powder was further increased to 30 μm in average particle size as compared with Example 1-1. Other than this, it is the same as in Example 1-1.
混合粉末を水と混合して混練、成形したときのSiの酸化反応が抑制され、水素発生量の評価は「3」である。その一方で、造粒体の機械的強度が若干低下した。 The oxidation reaction of Si when the mixed powder is mixed with water, kneaded and molded is suppressed, and the evaluation of the amount of hydrogen generated is "3". On the other hand, the mechanical strength of the granules was slightly reduced.
ここで用いたLi2Si2O5粉末2gを純水100gと混合して生成した懸濁液は、25℃でpH=11.0を示した。 The suspension produced by mixing 2 g of Li 2 Si 2 O 5 powder used here with 100 g of pure water exhibited pH = 11.0 at 25 ° C.
(実施例2)
金属珪酸塩粉末をLi2Si2O5粉末から、Li2SiO3粉末に変更した。Li2SiO3は〔x(Li2O)+y(SiO2)〕(x=1,y=1)であり、Li2O/SiO2=1である。これ以外は実施例1−1と同じである。
(Example 2)
The metal silicate powder was changed from Li 2 Si 2 O 5 powder to Li 2 SiO 3 powder. Li 2 SiO 3 is [x (Li 2 O) + y (SiO 2 )] (x = 1, y = 1), and Li 2 O / SiO 2 = 1. Other than this, it is the same as in Example 1-1.
実施例1−1と比べ、混合粉末を水と混合して混練、成形したときのSiの酸化反応が活発化し、水素発生量の評価は「4」である。その一方で、造粒体の機械的強度は若干上昇した。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder was mixed with water, kneaded and molded was activated, and the evaluation of the amount of hydrogen generated was "4". On the other hand, the mechanical strength of the granules increased slightly.
ここで用いたLi2SiO3粉末2gを純水100gと混合して作製した懸濁液は、25℃でpH=11.7を示し、実施例1−1〜7と比べアルカリ度が上昇した。 The suspension prepared by mixing 2 g of Li 2 SiO 3 powder used here with 100 g of pure water showed pH = 11.7 at 25 ° C., and the alkalinity was increased as compared with Examples 1-1 to 7. ..
(実施例3)
金属珪酸塩粉末を珪酸リチウムから、珪酸マグネシウムであるMg2Si3O8粉末に変更した。これ以外は実施例1−1と同じである。
(Example 3)
The metal silicate powder was changed from lithium silicate to Mg 2 Si 3 O 8 powder which is magnesium silicate. Other than this, it is the same as in Example 1-1.
実施例1−1と比べ、混合粉末を水と混合して混練、成形したときのSiの酸化反応は著しく抑制され、水素発生量の評価は「1」である。その一方で、造粒体の機械的強度は若干低下した。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder was mixed with water, kneaded and molded was significantly suppressed, and the evaluation of the amount of hydrogen generated was "1". On the other hand, the mechanical strength of the granules decreased slightly.
ここで用いたMg2Si3O8粉末2gを純水100gと混合して作製した懸濁液は、25℃でpH=9.9を示し、弱アルカリ水ではあるものの、実施例1−1〜7と比べてアルカリ度が低い。 The suspension prepared by mixing 2 g of Mg 2 Si 3 O 8 powder used here with 100 g of pure water showed pH = 9.9 at 25 ° C., and although it was weakly alkaline water, Example 1-1 The alkalinity is lower than that of ~ 7.
(実施例4−1)
実施例1−1において、造粒に使用する水の温度を25℃から15℃に下げた。これ以外は実施例1−1と同じである。
(Example 4-1)
In Example 1-1, the temperature of the water used for granulation was lowered from 25 ° C. to 15 ° C. Other than this, it is the same as in Example 1-1.
実施例1−1と比べて、混合粉末を水と混合して混練、成形したときのSiの酸化反応が抑制されている。その一方で、造粒体の機械的強度が若干低下した。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder is mixed with water, kneaded and molded is suppressed. On the other hand, the mechanical strength of the granules was slightly reduced.
(実施例4−2)
造粒に使用する水の温度を更に低い5℃に下げた。これ以外は実施例1−1と同じである。
(Example 4-2)
The temperature of the water used for granulation was further lowered to 5 ° C. Other than this, it is the same as in Example 1-1.
実施例1−1と比べて、混合粉末を水と混合して混練、成形したときのSiの酸化反応が更に抑制されている。その一方で、造粒体の機械的強度が更に少し低下した。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder is mixed with water, kneaded and molded is further suppressed. On the other hand, the mechanical strength of the granules was further reduced.
(実施例4−3)
実施例2において、造粒に使用する水の温度を25℃から5℃に下げた。これ以外は実施例2と同じである。
(Example 4-3)
In Example 2, the temperature of the water used for granulation was lowered from 25 ° C. to 5 ° C. Other than this, it is the same as in the second embodiment.
実施例2と比べて、混合粉末を水と混合して混練、成形したときのSiの酸化反応が抑制されている。その一方で、造粒体の機械的強度が若干低下した。 Compared with Example 2, the oxidation reaction of Si when the mixed powder is mixed with water, kneaded and molded is suppressed. On the other hand, the mechanical strength of the granules was slightly reduced.
(比較例1)
Si粉末と、SiO2粉末(酸化珪素粉末)とをV型混合機により混合し、その混合粉末を造粒機(アーステクニカ製ハイスピードミキサー)により混練して粒状に生成した後、棚型乾燥機により乾燥した。Si粉末と混合する粉末の種類が異なる以外、実施例1−1と同じである。
(Comparative Example 1)
Si powder and SiO 2 powder (silicon oxide powder) are mixed by a V-type mixer, and the mixed powder is kneaded by a granulator (high-speed mixer manufactured by Arstecnica) to produce granules, and then shelf-type drying. It was dried by the machine. It is the same as Example 1-1 except that the type of powder to be mixed with the Si powder is different.
SiO2粉末(酸化珪素粉末)を水と混合して混練、成形したときのSiの酸化反応は発生していないが、造粒体の機械的強度は「20」と、上述した一連の実施例に比して著しく低下した。 Although the oxidation reaction of Si did not occur when SiO 2 powder (silicon oxide powder) was mixed with water and kneaded and molded, the mechanical strength of the granulated material was "20", which is a series of the above-mentioned examples. It decreased significantly compared to.
ここで用いたSiO2粉末(酸化珪素粉末)2gを純水100gと混合して作製した懸濁液は、25℃でpH=7.1と、ほぼ中性を示した。 The suspension prepared by mixing 2 g of SiO 2 powder (silicon oxide powder) used here with 100 g of pure water showed a pH of 7.1 at 25 ° C., which was almost neutral.
(比較例2−1)
実施例1−1と同様に、Si粉末とLi2Si2O5粉末とをV型混合機により混合し、その混合粉末を造粒機(アーステクニカ製ハイスピードミキサー)により混練して粒状に成形した後、棚型乾燥機により乾燥した。
(Comparative Example 2-1)
In the same manner as in Example 1-1, Si powder and Li 2 Si 2 O 5 powder are mixed by a V-type mixer, and the mixed powder is kneaded by a granulator (EarthTechnica high-speed mixer) to granulate. After molding, it was dried by a shelf type dryer.
実施例1−1と相違するのは、Si粉末の粒度であり、その平均粒径は20μmと大きい。これ以外は実施例1−1と同じである。 The difference from Example 1-1 is the particle size of the Si powder, the average particle size of which is as large as 20 μm. Other than this, it is the same as in Example 1-1.
実施例1−1と比べ、混合粉末を水と混合して混練、成形したときのSiの酸化反応は著しく抑制され、水素発生量の評価は「1」である。その一方で、造粒体の機械的強度は「30」と大きく低下した。ただし、その機械的強度は比較例1より高い。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder was mixed with water, kneaded and molded was significantly suppressed, and the evaluation of the amount of hydrogen generated was "1". On the other hand, the mechanical strength of the granulated material was greatly reduced to "30". However, its mechanical strength is higher than that of Comparative Example 1.
ここで用いたLi2Si2O5粉末2gを純水100gと混合して作製した懸濁液は、実施例1と同じであり、25℃でpH=11.2を示す。 The suspension prepared by mixing 2 g of Li 2 Si 2 O 5 powder used here with 100 g of pure water is the same as in Example 1 and exhibits pH = 11.2 at 25 ° C.
(比較例2−2)
金属珪酸塩粉末であるLi2Si2O5粉末の粒度を平均粒径で45μmとした。これ以外は実施例1−1と同じである。
(Comparative Example 2-2)
The particle size of the Li 2 Si 2 O 5 powder, which is a metal silicate powder, was set to an average particle size of 45 μm. Other than this, it is the same as in Example 1-1.
実施例1−1と比べ、混合粉末を水と混合して混練、成形したときのSiの酸化反応が抑制され、水素発生量の評価は「2」である。その一方で、造粒体の機械的強度は「30」と大きく低下した。ただし、その機械的強度は比較例1より高い。 Compared with Example 1-1, the oxidation reaction of Si when the mixed powder was mixed with water, kneaded and molded was suppressed, and the evaluation of the amount of hydrogen generated was "2". On the other hand, the mechanical strength of the granulated material was greatly reduced to "30". However, its mechanical strength is higher than that of Comparative Example 1.
ここで用いたLi2Si2O5粉末2gを純水100gと混合して作製した懸濁液は、実施例1と同じであり、25℃でpH=11.0を示す。 The suspension prepared by mixing 2 g of Li 2 Si 2 O 5 powder used here with 100 g of pure water is the same as in Example 1 and exhibits pH = 11.0 at 25 ° C.
(比較例2−3)
造粒体の直径、すなわち造粒径を0.5〜40mmとした。これ以外は実施例1−1と同じである。
(Comparative Example 2-3)
The diameter of the granulated material, that is, the particle size was set to 0.5 to 40 mm. Other than this, it is the same as in Example 1-1.
混合粉末を水と混合して混練、成形したときのSiの酸化反応は実施例1−1と同程度に抑制され、水素発生量の評価は「3」である。また、混合粉末を水と混合して混練、成形したときのSiの酸化反応も実施例1−1と同程度に抑制されている。 The oxidation reaction of Si when the mixed powder was mixed with water, kneaded and molded was suppressed to the same extent as in Example 1-1, and the evaluation of the amount of hydrogen generated was "3". Further, the oxidation reaction of Si when the mixed powder is mixed with water, kneaded and molded is also suppressed to the same extent as in Example 1-1.
しかしながら、造粒体の機械的強度は「10」と大きく低下した。これは、単純に造粒体のサイズが大きすぎるためであり、金属珪酸塩粉末であるLi2Si2O5粉末の表面が水に溶解する現象、その現象により水が弱アルカリ化する現象、その弱アルカリ水により、Si粉末の表面に形成されているSiO2皮膜が僅かに溶解する現象、これらの現象によるバインダー効果が消滅したわけではない。 However, the mechanical strength of the granulated material was greatly reduced to "10". This is simply because the size of the granulated product is too large, and the surface of the Li 2 Si 2 O 5 powder, which is a metal silicate powder, dissolves in water, and the phenomenon causes the water to become weakly alkaline. The weak alkaline water slightly dissolves the SiO 2 film formed on the surface of the Si powder, and the binder effect due to these phenomena is not eliminated.
(比較例3)
金属珪酸塩粉末をLi2Si2O5粉末からLi4SiO4粉末に変更した。Li4SiO4は〔x(Li2O)+y(SiO2)〕(x=2,y=1)であり、Li2O/SiO2=2である。これ以外は実施例1−1と同じである。
(Comparative Example 3)
The metal silicate powder was changed from Li 2 Si 2 O 5 powder to Li 4 SiO 4 powder. Li 4 SiO 4 is [x (Li 2 O) + y (SiO 2 )] (x = 2, y = 1), and Li 2 O / SiO 2 = 2. Other than this, it is the same as in Example 1-1.
混合粉末を水と混合して混練、成形したときのSiの酸化反応が激しく、水素発生量の評価は、造粒が困難な「5」であった。 When the mixed powder was mixed with water, kneaded and molded, the oxidation reaction of Si was intense, and the evaluation of the amount of hydrogen generated was "5", which was difficult to granulate.
ここで用いたLi4SiO4粉末2gを純水100gと混合して懸濁液としたところ、その懸濁液は25℃でpH=12.1を示した。また、Li4SiO4粉末が水と激しく反応し、強いアルカリ及び熱を生じた。この高温の強アルカリ水がSiと激しく反応したことが、混合粉末の混練、成形過程でSiが激しく酸化し、多量の水素を発生した現象の要因である。 When 2 g of the Li 4 SiO 4 powder used here was mixed with 100 g of pure water to form a suspension, the suspension showed pH = 12.1 at 25 ° C. In addition, Li 4 SiO 4 powder reacted violently with water to generate strong alkali and heat. The violent reaction of this high-temperature strong alkaline water with Si is the cause of the phenomenon in which Si is violently oxidized during the kneading and molding processes of the mixed powder to generate a large amount of hydrogen.
Claims (11)
前記金属珪酸塩は、珪酸リチウムであるバインダーレス造粒体。 In the binderless granule according to claim 1,
The metal silicate is a binderless granule which is lithium silicate.
前記珪酸リチウムの組成がモル比でLi2O/SiO2<2であるバインダーレス造粒体。 In the binderless granule according to claim 2.
A binderless granule having a composition of lithium silicate of Li 2 O / SiO 2 <2 in molar ratio.
前記金属珪酸塩粉末は、当該粉末2gを純水100gに投入して作製した懸濁液のpHが9〜12を示すバインダーレス造粒体。 In the binderless granule according to any one of claims 1 to 3.
The metal silicate powder is a binderless granule having a pH of 9 to 12 of a suspension prepared by adding 2 g of the powder to 100 g of pure water.
造粒径が0.25〜30mmであるバインダーレス造粒体。 In the binderless granule according to any one of claims 1 to 4.
A binderless granule having a particle size of 0.25 to 30 mm.
前記Si粉末の粒度が平均粒径で1〜18μmであるバインダーレス造粒体。 In the binderless granule according to any one of claims 1 to 5.
A binderless granule having an average particle size of 1 to 18 μm of the Si powder.
前記金属珪酸塩粉末の粒度が平均粒径で1〜30μmであるバインダーレス造粒体。 In the binderless granule according to any one of claims 1 to 6.
A binderless granule having an average particle size of 1 to 30 μm of the metal silicate powder.
前記Si粉末と前記金属珪酸塩粉末の混合比が、混合後の元素モル比で0.1≦0.O/Si≦1.2であるバインダーレス造粒体。 In the binderless granule according to any one of claims 1 to 7.
The mixing ratio of the Si powder and the metal silicate powder is 0.1 ≦ 0. Binderless granules with O / Si ≦ 1.2.
前記混練及び前記成形における水の温度を15℃以下に維持するバインダーレス造粒体の製造方法。 In the method for producing a binderless granule according to claim 9.
A method for producing a binderless granule in which the temperature of water in the kneading and molding is maintained at 15 ° C. or lower.
前記乾燥を減圧乾燥により行うバインダーレス造粒体の製造方法。 In the method for producing a binderless granule according to claim 9 or 10.
A method for producing a binderless granule, in which the drying is carried out by drying under reduced pressure.
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