JP3553717B2 - Method for producing crystalline silicate compound - Google Patents
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- JP3553717B2 JP3553717B2 JP35449095A JP35449095A JP3553717B2 JP 3553717 B2 JP3553717 B2 JP 3553717B2 JP 35449095 A JP35449095 A JP 35449095A JP 35449095 A JP35449095 A JP 35449095A JP 3553717 B2 JP3553717 B2 JP 3553717B2
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Description
【０００１】
【発明の属する技術分野】
本発明は結晶性珪酸化合物を工業的に有利に製造する方法に関する。さらに詳しくは、焼成装置内での結晶化速度を向上させ、生産性の高い結晶性珪酸化合物の製造方法に関する。
【０００２】
【従来の技術】
結晶性珪酸化合物を製造する際に、原料となる無定形の含水珪酸化合物を高温にて加熱することにより結晶化させる方法が知られている。
従来、結晶性珪酸化合物の製造方法として特公平５−６６８８８号公報、特公平６−６９８９０号公報等に記載された方法が挙げられる。
特公平５−６６８８８号公報では、噴霧乾燥された粉末状の無定形ケイ酸ナトリウムを移動固体層を有する灼熱帯域中で、温度５００〜８００℃で、灼熱帯域から搬出された結晶性ケイ酸ナトリウムを機械的に粉砕することによって得られた返送物、少なくとも１０重量％の存在で１〜６０分熱処理する方法が提案されている。
特公平６−６９８９０号公報では、低温かつ滞留時間の短い噴霧乾燥によって高い嵩密度を有する粉末状の無定形の含水ケイ酸ナトリウムとし、これを断熱した内熱式回転管状炉において５００〜８５０℃の煙道ガスで加熱し、結晶性ケイ酸ナトリウムを得ている。この際に、回転管状炉の中間領域および粉末状の無定形ケイ酸ナトリウムの導入に用いられる端部の領域において吸引し、フィルターにて捕集して得たケイ酸ナトリウムを原料となる無定形含水ケイ酸ナトリウムに連続的に配合する方法が提案されている。
【０００３】
【発明が解決しようとする課題】
しかしながら、特公平５−６６８８８号公報、特公平６−６９８９０号公報記載の方法においては、いずれの方法においても焼成時の雰囲気中の水分量については触れられていない。
さらに、特公平５−６６８８８号公報記載の方法では、結晶性ケイ酸ナトリウムを返送することにより、焼成炉に供給される原料の実質の含水率が低くなり、また、特公平６−６９８９０号公報記載の方法では、炉内から吸引されたケイ酸ナトリウムは含水率が低く、これが連続的に配合されて供給されるため、原料に伴って供給される水分も少なくなる。さらに、回転管状炉内からケイ酸ナトリウムをフィルターにて捕集するためにガスを吸引することにより、炉内の水蒸気分圧が低下する。
しかしながら、このような低水分雰囲気下では、結晶化反応の速度が遅く、結晶化に要する時間が長くなるか、より高い反応温度を必要とする。
【０００４】
【課題を解決するための手段】
本発明者らは水蒸気の存在下において珪酸化合物の結晶化が促進されることを見出し、さらに研究を進めて本発明を完成した。即ち、本発明の要旨は、
（１） 露点が３０℃以上、９０℃以下の水分を含む雰囲気下にて無定形珪酸化合物を焼成することを特徴とする結晶性珪酸化合物の製造方法であって、該結晶性珪酸化合物が、一般式ｘＭ 2 Ｏ・ｙＳｉＯ 2 ・ｚＭ’Ｏ（但し、ＭはＮａ及び／又はＫを示し、Ｍ’はＣａ及び／又はＭｇを示し、ｙ／ｘ＝０．５〜３．５、ｚ／ｘ＝０．００５〜１．０である。）で表わされる化合物である、結晶性珪酸化合物の製造方法、
（２） 露点が４５℃以上、７５℃以下である前記（１）記載の製造方法、
（３） 無定形珪酸化合物の含水率が０．１〜５０重量％（湿量基準）である前記（１）又は（２）記載の製造方法、
（４） 焼成炉に水蒸気を導入して焼成を行うことを特徴とする前記（１）〜（３）いずれか記載の製造方法、に関するものである。
【０００５】
【発明の実施の形態】
以下、本発明を詳細に説明する。
本発明の製造方法で用いられる無定形珪酸化合物は特に限定されるものではないが、含水率としては、湿量基準の値で０．１〜５０重量％、好ましくは１０〜４０重量％、さらに好ましくは１５〜２８重量％である。水分の蒸発に要する熱負荷を抑える観点から５０重量％以下が好ましい。水分の蒸発に要する熱負荷が増大すると、処理物の温度上昇に必要な時間の増加が結晶化速度の向上による結晶化時間の短縮効果を上回り、焼成工程に必要な時間が増加する。
【０００６】
該無定形珪酸化合物を調製する方法は特に限定されないが、工業的に生産されている珪酸塩溶液や、これに水酸化ナトリウム溶液及び／又は水酸化カリウム溶液等を添加してアルカリ金属濃度を適宜調製したもの、さらにＣａ、Ｍｇの供給源としてこれらの水酸化物、塩化物または硝酸塩を添加した珪酸化合物溶液を、噴霧乾燥等の公知の乾燥方法により乾燥することにより得ることができる。
【０００７】
本発明の結晶性珪酸化合物の製造方法は、所定の露点の水分を含む雰囲気下にて無定形珪酸化合物を焼成することを特徴とする。
本発明における焼成とは、無定形珪酸化合物を結晶化させて結晶性珪酸化合物にする反応をいう。焼成温度範囲としては通常行われる公知の範囲で良く、５００℃〜ガラス化開始温度の範囲が好ましく、より好ましくは、結晶性珪酸化合物を収率よく製造する点から５５０〜８３０℃である。なお、無定形珪酸化合物の結晶化を図る観点から、焼成温度は５００℃以上が好ましく、珪酸化合物がガラス化するのを抑える観点からガラス化開始温度以下が好ましい。
【０００８】
また、焼成時間としては通常行われる公知の範囲で良く、１０分間〜２０時間が好ましく、より好ましくは３０分間〜１０時間である。無定形珪酸化合物を所定の焼成温度に至らしめる観点から、焼成時間は１０分間以上が好ましく、生産性の観点から２０時間以下が好ましい。
焼成炉としては、特に限定されることはなく、回転管状炉や流動層などの動的焼成炉でも、バケットやベルトを用いた静置式焼成炉のいずれでも構わない。また、回分式、連続式のいずれでも構わない。加熱方式についても特に限定されないが、水蒸気を含有する燃焼ガスによる直接加熱式がより好ましい。
また、焼成炉中の雰囲気としては特に限定されるものではなく、例えば空気雰囲気、窒素雰囲気等の公知のもので良い。
【０００９】
本発明においては、所定の露点の水分を含む雰囲気下にて、無定形珪酸化合物を焼成することを特徴とする。
雰囲気の露点としては３０〜９０℃で、好ましくは４０〜８０℃、さらに好ましくは４５〜７５℃である。低含水率の無定形珪酸化合物を用いた場合での結晶化速度の向上を図る観点から露点は３０℃以上が好ましく、雰囲気の比熱を抑える観点から露点は９０℃以下が好ましい。雰囲気の比熱が大きくなると、必要な加熱量が大きくなりエネルギー的に不利になる。
焼成炉への水分の導入方法としては、水を液体状態のまま、もしくは水蒸気の状態でもいずれでも構わないが、焼成炉の熱効率からは、気化熱を要しない水蒸気の方が好ましい。
上記より、本発明の製造方法において、露点、焼成温度、焼成時間の好適な組み合わせとしては、３０〜９０℃、５００℃〜ガラス化開始温度、１０分間〜２０時間であり、より好ましくは４０〜８０℃、５５０〜８３０℃、３０分間〜１０時間であり、特に好ましくは４５〜７５℃、５５０〜８３０℃、３０分間〜１０時間である。
【００１０】
焼成工程において、無定形珪酸化合物が結晶化する段階で水分が作用し、そして結晶化速度を向上させることから、水分の供給方法としては連続式焼成炉の場合は供給する無定形珪酸化合物と水分が向流に供給する方が望ましい。また、回分式焼成炉では焼成の後半における水分の供給が重要である。即ち、雰囲気の露点を目的の範囲に維持する期間は焼成工程全般にわたってでも構わないが、無定形珪酸化合物中の水分が放出され、実質的に水分を含まない状態（０．７重量％以下）になって以降のみでも結晶化速度向上の効果を得ることができる。従って、回分式焼成炉を用いる場合、無定形珪酸化合物が上記の実質的に水分を含まない期間において、少なくとも雰囲気の露点を目的の範囲に維持していれば、本発明の効果は達成される。
【００１１】
本発明の製造方法によって得られる結晶性珪酸化合物は、種々の用途に用いることが可能であり、例えば、一般的に水軟水化剤として用いられることが知られている。
また得られる結晶性珪酸化合物の組成については特に限定されるものではないが、一般式ｘＭ２ Ｏ・ｙＳｉＯ２ ・ｚＭ’Ｏ（但し、ＭはＮａ及び／又はＫを示し、Ｍ’はＣａ及び／又はＭｇを示す。）において、ｙ／ｘ＝０．５〜３．５、ｚ／ｘ＝０〜１．０であることが好ましく、さらに好ましくはｙ／ｘ＝０．５〜２．０、ｚ／ｘ＝０．００５〜１．０である。
【００１２】
【実施例】
以下、実施例および比較例により本発明をさらに詳しく説明するが、本発明はこれらの実施例等によりなんら限定されるものではない。
【００１３】
実施例１
３号水ガラス（大阪硅曹社製、３号Ｋ）２１３ｋｇを３００リットル攪拌槽に仕込み、常温にて攪拌下４８％ＮａＯＨ溶液（東ソー社製）６１ｋｇ及びＣａ（ＯＨ）２ （土佐石灰社製）２６ｋｇを投入した。３時間攪拌した後、生成した白濁スラリー３００ｋｇをそのまま噴霧乾燥塔（ニロジャパン社製、塔径３．０ｍ、塔高５．６ｍ）に供給し、送風温度２６０℃、排風温度１２０℃の条件で乾燥した。その結果、平均粒子径１５５μｍ、嵩比重０．７ｇ／ｃｃ、含水率１９重量％（湿量基準）の乾燥粉末１１８ｋｇ（無定形珪酸化合物粉末）を得た。
含水率は電気炉にて７００℃にて１時間加熱した時の重量減少値より求め、湿量基準で表した。平均粒子径は篩による重量分率の累積５０％の値で示した。また、嵩比重は２００ｃｃのメスシリンダーを用いてタッピングせずに求めた。
【００１４】
この乾燥粉末を３０ｃｃのＮｉ坩堝７個に各５ｇ仕込み、これを小型電気炉（モトヤマ社製）に入れ昇温を開始した。この電気炉は電気ヒーターによる輻射伝熱により試料を加熱する形式の炉である。炉内温度が１００℃を超えた後に、炉内に空気を３．５リットル毎分、水を０．５ｇ毎分の速度で供給し、炉内の雰囲気の露点を５５℃に保持した状態で、６５０℃まで２時間で昇温した後、９時間保持した。
炉内温度が６５０℃に達した後、０．５、１、２、３、５、７、９時間後に炉内より坩堝を１個ずつ取り出し、冷却後焼成物を乳鉢にて粉砕した。
【００１５】
得られた焼成物粉末に内部標準試料としてシリコン微粉末を２０重量％添加してさらに乳鉢で充分混合したものをＸ線回折装置（リガク社製、ＣｕＫα線）にて分析し、最強ピーク（ｄ＝２．４２Ａ）の強度とシリコンのピーク（ｄ＝３．１４Ａ）の強度の比（Ｉｄ＝２．４２／Ｉｄ＝３．１４）を結晶化度の指標とし、その経時変化を測定した。
その結果を図１に示すが、ピーク強度比は炉内温度を６５０℃に保持後、２時間でほぼ一定値に達し、結晶化反応が完結していることが示された。
また、得られた焼成物粉末のうち、結晶化反応が完結しているもの（結晶性珪酸化合物）の組成をＸ線回折装置にて分析したところ、充分に結晶化した珪酸化合物Ｎａ２ Ｏ・１．５ＳｉＯ２ ・０．５ＣａＯであった。
【００１６】
比較例１
焼成炉内に空気のみを通気し、炉内雰囲気の露点を３℃に保持した以外は、実施例１と同じ条件で行った。
その結果を図１に示すが、炉内温度を６５０℃に保持後、５時間経過してもピーク強度比が低く、また、増加し続けていることから、結晶化反応が未だ完結していないことが示された。
【００１７】
実施例２
実施例１で調製した無定形珪酸化合物粉末１１ｋｇをバケット（ＳＵＳ３１０Ｓ製、５００×５５０×２００ｍｍ）に仕込み、これを炉内温度を３５０℃に加熱した電気炉（モトヤマ社製）に入れた。この電気炉は電気ヒーターで加熱した空気を炉内に循環させ、対流伝熱により試料を加熱する形式の炉である。この炉内に空気を３５リットル毎分、水を５ｇ毎分の速度で供給し、炉内の雰囲気の露点を５５℃に保持した状態で６５０℃まで１時間３０分で昇温した後、５時間保持した。
その結果、５００×５５０×１４０ｍｍの焼成塊を得た。この焼成塊の上表面中心と全体の中心とから各５ｇのサンプルを取り出し、粉砕した後、Ｘ線回折装置にて分析した。
結晶化反応は伝熱に伴い、表面部から中心部に向けて進行することから、得られた焼成塊の中心部のサンプルと表面部のサンプルの最強ピークの強度比により、結晶化反応の進行度合いの指標としたところ、その強度比（中心部の最強ピーク／表面部の最強ピーク）は０．９５で、中心部まで充分結晶化していることが示された。
【００１８】
実施例３
炉内に空気を２９リットル毎分、水蒸気を７．８ｇ毎分の速度で供給し、炉内の雰囲気の露点を７０℃に保持した以外は実施例２と同じ条件で行った。
得られた焼成塊の中心部のサンプルと表面部のサンプルの最強ピークの強度比は０．９６で、中心部まで充分結晶化していることが示された。
【００１９】
比較例２
炉内に空気のみを４０リットル毎分の速度で供給し、炉内の雰囲気の露点を３℃に保持した以外は実施例２と同じ条件で行った。
得られた焼成塊の中心部のサンプルと表面部のサンプルの最強ピークの強度比は０．７８で、中心部が未だ充分結晶化していないことが示された。
【００２０】
実施例４
最初の３時間は炉内に空気のみを４０リットル毎分の速度で供給し、炉内の雰囲気の露点を３℃に保持し、後半の３時間３０分は炉内に空気を３５リットル毎分、水を５ｇ毎分の速度で供給し、炉内の雰囲気の露点を５５℃に保持した以外は実施例２と同じ条件で行った。別途行った同条件の実験結果より、雰囲気の露点を５５℃に維持し始めた時点での珪酸化合物の含水率は０．６重量％であった。
得られた焼成塊の中心部のサンプルと表面部のサンプルの最強ピークの強度比は０．９５で、中心部まで充分結晶化していることが示された。
【００２１】
【発明の効果】
本発明の結晶性珪酸化合物の製造方法によると、焼成時の結晶化速度が向上することにより、より生産性が高く結晶性珪酸化合物を製造することができる。
【図面の簡単な説明】
【図１】図１は、本発明の露点範囲の水分を持つ雰囲気下で焼成を行った場合（実施例１）と、水分が少ない雰囲気下で焼成を行った場合（比較例１）の、結晶化挙動を比較して示したものである。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for industrially advantageously producing a crystalline silicate compound. More specifically, the present invention relates to a method for producing a crystalline silicate compound having a high productivity by improving the crystallization rate in a firing apparatus.
[0002]
[Prior art]
In producing a crystalline silicate compound, a method is known in which an amorphous hydrous silicate compound as a raw material is crystallized by heating at a high temperature.
Conventionally, as a method for producing a crystalline silicate compound, a method described in Japanese Patent Publication No. 5-68888, Japanese Patent Publication No. 6-69890 or the like can be mentioned.
Japanese Patent Publication No. 5-68888 discloses a method in which a spray-dried powdery amorphous sodium silicate is transferred from a burning zone at a temperature of 500 to 800 ° C. in a burning zone having a moving solid layer. , A heat-treated product in the presence of at least 10% by weight for 1 to 60 minutes has been proposed.
In Japanese Patent Publication No. 6-68990, powdery amorphous hydrated sodium silicate having a high bulk density is formed by spray drying at a low temperature and a short residence time, and is heated to 500 to 850 ° C. in an internally heated rotary tubular furnace insulated therefrom. To obtain crystalline sodium silicate. At this time, in the intermediate region of the rotary tube furnace and the end region used for introducing the powdery amorphous sodium silicate, the amorphous sodium silicate obtained by sucking and collecting with a filter is used as a raw material. A method has been proposed in which the compound is continuously mixed with hydrous sodium silicate.
[0003]
[Problems to be solved by the invention]
However, in the methods described in Japanese Patent Publication No. 5-68888 and Japanese Patent Publication No. 6-69890, the amount of moisture in the atmosphere at the time of firing is not mentioned in any of the methods.
Furthermore, in the method described in Japanese Patent Publication No. 5-68888, by returning the crystalline sodium silicate, the actual water content of the raw material supplied to the firing furnace is reduced. In the method described, sodium silicate sucked from the furnace has a low water content and is continuously blended and supplied, so that the water supplied along with the raw material is also reduced. Further, by sucking gas from the inside of the rotary tubular furnace to collect sodium silicate with a filter, the partial pressure of water vapor in the furnace is reduced.
However, under such a low-moisture atmosphere, the speed of the crystallization reaction is slow, and the time required for the crystallization is long, or a higher reaction temperature is required.
[0004]
[Means for Solving the Problems]
The present inventors have found that crystallization of a silicate compound is promoted in the presence of water vapor, and have further studied to complete the present invention. That is, the gist of the present invention is:
(1) A method for producing a crystalline silicate compound, comprising firing an amorphous silicate compound in an atmosphere containing moisture having a dew point of 30 ° C. or more and 90 ° C. or less , wherein the crystalline silicate compound is formula xM 2 O · ySiO 2 · zM'O ( where, M represents a Na and / or K, M 'represents Ca and / or Mg, y / x = 0.5~3.5, z / x = 0.005 to 1.0), a method for producing a crystalline silicate compound ,
(2) The production method according to the above (1), wherein the dew point is 45 ° C. or more and 75 ° C. or less,
(3) The production method according to the above (1) or (2), wherein the water content of the amorphous silicate compound is 0.1 to 50% by weight (wet weight basis);
(4) The method of producing the (1) to (3) according to any one which is characterized in that the baking furnace firing by introducing steam into it relates to.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail.
The amorphous silicate compound used in the production method of the present invention is not particularly limited, but the moisture content is 0.1 to 50% by weight, preferably 10 to 40% by weight on a wet basis, and more preferably 10 to 40% by weight. Preferably it is 15 to 28% by weight. From the viewpoint of suppressing the heat load required for evaporating water, the content is preferably 50% by weight or less. When the heat load required for evaporating the water increases, the time required for raising the temperature of the processed product exceeds the effect of shortening the crystallization time by improving the crystallization speed, and the time required for the firing step increases.
[0006]
The method for preparing the amorphous silicate compound is not particularly limited, but an industrially produced silicate solution or a sodium hydroxide solution and / or a potassium hydroxide solution may be added thereto to adjust the alkali metal concentration appropriately. It can be obtained by drying the prepared silicate compound solution to which a hydroxide, chloride or nitrate is added as a supply source of Ca and Mg by a known drying method such as spray drying.
[0007]
The method for producing a crystalline silicate compound according to the present invention is characterized in that the amorphous silicate compound is calcined in an atmosphere containing water having a predetermined dew point.
The firing in the present invention refers to a reaction of crystallizing an amorphous silicate compound into a crystalline silicate compound. The calcination temperature range may be a commonly known range, and is preferably from 500 ° C to the vitrification start temperature, and more preferably 550 to 830 ° C from the viewpoint of producing a crystalline silicate compound in good yield. The firing temperature is preferably 500 ° C. or higher from the viewpoint of crystallization of the amorphous silicate compound, and is preferably equal to or lower than the vitrification start temperature from the viewpoint of suppressing vitrification of the silicate compound.
[0008]
The baking time may be in a known range that is usually performed, and is preferably 10 minutes to 20 hours, and more preferably 30 minutes to 10 hours. The firing time is preferably 10 minutes or more from the viewpoint of bringing the amorphous silicate compound to a predetermined firing temperature, and is preferably 20 hours or less from the viewpoint of productivity.
The firing furnace is not particularly limited, and may be a dynamic firing furnace such as a rotary tubular furnace or a fluidized bed, or a stationary firing furnace using a bucket or a belt. Further, any of a batch type and a continuous type may be used. The heating method is not particularly limited, but a direct heating method using a combustion gas containing water vapor is more preferable.
The atmosphere in the firing furnace is not particularly limited, and may be a known atmosphere such as an air atmosphere or a nitrogen atmosphere.
[0009]
The present invention is characterized in that the amorphous silicate compound is calcined in an atmosphere containing water having a predetermined dew point.
The dew point of the atmosphere is 30 to 90 ° C, preferably 40 to 80 ° C, more preferably 45 to 75 ° C. The dew point is preferably 30 ° C. or higher from the viewpoint of improving the crystallization rate when an amorphous silicate compound having a low water content is used, and the dew point is preferably 90 ° C. or lower from the viewpoint of suppressing the specific heat of the atmosphere. When the specific heat of the atmosphere increases, the required amount of heating increases, which is disadvantageous in terms of energy.
As a method for introducing water into the firing furnace, water may be kept in a liquid state or in a water vapor state, but from the thermal efficiency of the firing furnace, steam which does not require heat of vaporization is preferable.
From the above, in the production method of the present invention, a suitable combination of the dew point, the calcination temperature, and the calcination time is 30 to 90 ° C, 500 ° C to the vitrification start temperature, 10 minutes to 20 hours, more preferably 40 to 90 hours. 80 ° C, 550 to 830 ° C, 30 minutes to 10 hours, particularly preferably 45 to 75 ° C, 550 to 830 ° C, 30 minutes to 10 hours.
[0010]
In the firing step, water acts at the stage of crystallization of the amorphous silicate compound, and the crystallization rate is improved. Therefore, in the case of a continuous firing furnace, the water is supplied in the form of an amorphous silicate compound and water. Is preferably supplied countercurrently. In a batch type furnace, it is important to supply water in the latter half of the firing. That is, the period during which the dew point of the atmosphere is maintained in the target range may be over the entire firing step, but the water in the amorphous silicate compound is released and substantially free of water (0.7% by weight or less). Only after that, the effect of improving the crystallization speed can be obtained. Therefore, when using a batch-type firing furnace, the effects of the present invention are achieved if the amorphous silicate compound maintains at least the dew point of the atmosphere within the target range during the period substantially free of moisture. .
[0011]
The crystalline silicate compound obtained by the production method of the present invention can be used for various uses, and for example, it is known that it is generally used as a water softener.
The composition of the obtained crystalline silicate compound is not particularly limited, but is represented by the general formula xM 2 O.ySiO 2 .zM′O (where M represents Na and / or K, M ′ represents Ca and / Or Mg.), Y / x = 0.5-3.5, z / x = 0-1.0, more preferably y / x = 0.5-2.0. , Z / x = 0.005 to 1.0.
[0012]
【Example】
Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples and the like.
[0013]
Example 1
213 kg of No. 3 water glass (No. 3 K, manufactured by Osaka Keiso Co., Ltd.) is charged into a 300-liter stirring tank, and 61 kg of 48% NaOH solution (manufactured by Tosoh Corporation) and Ca (OH) 2 (manufactured by Tosa Lime Co., Ltd.) are stirred at room temperature. ) 26 kg was charged. After stirring for 3 hours, 300 kg of the produced cloudy slurry was directly supplied to a spray drying tower (manufactured by Niro Japan Co., Ltd., tower diameter: 3.0 m, tower height: 5.6 m) under the conditions of a blowing temperature of 260 ° C. and an exhaust temperature of 120 ° C. Dried. As a result, 118 kg (amorphous silicate compound powder) of a dry powder having an average particle size of 155 μm, a bulk specific gravity of 0.7 g / cc, and a water content of 19% by weight (wet weight basis) was obtained.
The water content was determined from the weight loss value when heated at 700 ° C. for 1 hour in an electric furnace and expressed on a wet basis. The average particle size was indicated by a value of 50% of the cumulative weight fraction by the sieve. The bulk specific gravity was determined without tapping using a 200 cc measuring cylinder.
[0014]
5 g of each of the dried powders was charged into seven 30 cc Ni crucibles, placed in a small electric furnace (manufactured by Motoyama), and the temperature was increased. This electric furnace is a furnace of a type in which a sample is heated by radiant heat transfer by an electric heater. After the furnace temperature exceeded 100 ° C., 3.5 liters of air and 0.5 g of water were supplied into the furnace at a rate of 0.5 g per minute, and the dew point of the atmosphere in the furnace was maintained at 55 ° C. The temperature was raised to 650 ° C. for 2 hours and then maintained for 9 hours.
After the furnace temperature reached 650 ° C., 0.5, 1, 2, 3, 5, 7, and 9 hours later, the crucibles were taken out of the furnace one by one, cooled, and the fired product was ground in a mortar.
[0015]
20% by weight of a silicon fine powder was added to the obtained fired product powder as an internal standard sample, and the mixture was further mixed well in a mortar and analyzed with an X-ray diffractometer (CuKα ray, manufactured by Rigaku Corporation). = 2.42A) and the intensity of the silicon peak (d = 3.14A) (Id = 2.42 / Id = 3.14 ) as an index of crystallinity, and the change over time is measured. did.
The results are shown in FIG. 1. The peak intensity ratio reached an almost constant value in 2 hours after the furnace temperature was maintained at 650 ° C., indicating that the crystallization reaction was completed.
When the composition of the obtained calcined product powder in which the crystallization reaction was completed (crystalline silicate compound) was analyzed by an X-ray diffractometer, a sufficiently crystallized silicate compound Na 2 O · It was 1.5SiO 2 .0.5CaO.
[0016]
Comparative Example 1
The procedure was performed under the same conditions as in Example 1 except that only air was passed through the firing furnace and the dew point of the atmosphere in the furnace was maintained at 3 ° C.
The results are shown in FIG. 1. The peak intensity ratio was low even after 5 hours since the temperature in the furnace was maintained at 650 ° C., and since the peak intensity ratio continued to increase, the crystallization reaction was not completed yet. It was shown.
[0017]
Example 2
11 kg of the amorphous silicate compound powder prepared in Example 1 was charged into a bucket (manufactured by SUS310S, 500 × 550 × 200 mm) and placed in an electric furnace (manufactured by Motoyama) heated to a furnace temperature of 350 ° C. This electric furnace is of a type in which air heated by an electric heater is circulated in the furnace, and the sample is heated by convection heat transfer. Air was supplied into the furnace at a rate of 35 liters per minute and water at a rate of 5 g per minute, and the temperature of the furnace was raised to 650 ° C. in 1 hour 30 minutes while the dew point of the atmosphere was kept at 55 ° C. Hold for hours.
As a result, a fired lump of 500 × 550 × 140 mm was obtained. 5 g of each sample was taken out from the center of the upper surface of the fired mass and from the center of the whole, crushed, and analyzed by an X-ray diffractometer.
Since the crystallization reaction proceeds from the surface to the center with heat transfer, the crystallization reaction proceeds according to the intensity ratio of the strongest peak between the sample at the center and the sample at the surface of the obtained fired mass. As an index of the degree, the intensity ratio (the strongest peak at the center / the strongest peak at the surface) was 0.95, indicating that the crystal was sufficiently crystallized up to the center.
[0018]
Example 3
Example 2 was carried out under the same conditions as in Example 2 except that air was supplied into the furnace at a rate of 29 liters per minute and steam at a rate of 7.8 g per minute, and the dew point of the atmosphere in the furnace was maintained at 70 ° C.
The intensity ratio of the strongest peak between the sample at the center and the sample at the surface of the obtained fired lump was 0.96, indicating that the sample was sufficiently crystallized up to the center.
[0019]
Comparative Example 2
The procedure was performed under the same conditions as in Example 2 except that only air was supplied into the furnace at a rate of 40 liters per minute, and the dew point of the atmosphere in the furnace was maintained at 3 ° C.
The intensity ratio of the strongest peak between the sample at the center and the sample at the surface of the obtained fired lump was 0.78, indicating that the center was not yet sufficiently crystallized.
[0020]
Example 4
For the first three hours, only air is supplied into the furnace at a rate of 40 liters per minute, the dew point of the atmosphere in the furnace is maintained at 3 ° C., and in the latter three hours 30 minutes, air is supplied into the furnace at 35 liters per minute. , Water was supplied at a rate of 5 g per minute, and the dew point of the atmosphere in the furnace was maintained at 55 ° C., under the same conditions as in Example 2. From the results of the experiment conducted separately under the same conditions, the water content of the silicate compound at the time when the dew point of the atmosphere was started to be maintained at 55 ° C. was 0.6% by weight.
The intensity ratio of the strongest peak between the sample at the center and the sample at the surface of the obtained fired lump was 0.95, indicating that the sample was sufficiently crystallized up to the center.
[0021]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the manufacturing method of the crystalline silicate compound of this invention, the crystallization rate at the time of baking improves, and productivity can be higher and a crystalline silicate compound can be manufactured.
[Brief description of the drawings]
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a case where baking is performed in an atmosphere having moisture in a dew point range according to the present invention (Example 1) and a case where baking is performed in an atmosphere having low moisture (Comparative Example 1). This is a comparison of the crystallization behavior.
Claims (4)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35449095A JP3553717B2 (en) | 1995-12-28 | 1995-12-28 | Method for producing crystalline silicate compound |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP35449095A JP3553717B2 (en) | 1995-12-28 | 1995-12-28 | Method for producing crystalline silicate compound |
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| Publication Number | Publication Date |
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| JPH09183611A JPH09183611A (en) | 1997-07-15 |
| JP3553717B2 true JP3553717B2 (en) | 2004-08-11 |
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| JP35449095A Expired - Fee Related JP3553717B2 (en) | 1995-12-28 | 1995-12-28 | Method for producing crystalline silicate compound |
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