本文選題：水鎂石 + 氫氧化鎂�。� 參考：《東北大學(xué)》2010年博士論文

【摘要】：水鎂石是迄今為止發(fā)現(xiàn)的含鎂量最高的一種礦物,在世界上分布不廣,產(chǎn)出比較稀少,我國具有豐富的水鎂石資源。作為一種工業(yè)礦物,水鎂石在耐火材料、環(huán)境保護、建材、陶瓷和核工業(yè)等領(lǐng)域得到了廣泛應(yīng)用。但是,由于技術(shù)比較落后,目前我國的水鎂石的開發(fā)利用還處于原礦的出口及生產(chǎn)耐火材料等低附加值產(chǎn)品的初級階段,這對水鎂石資源造成了極大的浪費并限制了水鎂石的高效利用。為了避免這種浪費,應(yīng)將其用于高附加值、具有高技術(shù)含量的功能材料的生產(chǎn)與加工上。 用水鎂石制備環(huán)境友好型的氫氧化鎂無機阻燃劑受到了廣泛的關(guān)注,近年來,隨著人們環(huán)保意識的日益增強,氫氧化鎂作為環(huán)境友好型的無機阻燃劑,由于其阻燃、抑煙、無毒、熱穩(wěn)定性高等特點,在聚合物、電纜、建筑和裝飾材料等領(lǐng)域得到了廣泛的應(yīng)用。氫氧化鎂的晶形和粒度對其性能有十分顯著的影響,具有優(yōu)良阻燃性能的氫氧化鎂應(yīng)為纖維狀和片狀,純度大于97%,厚度大于80nm,顆粒的平均尺寸為0.5-1μm,(101)極性面的微觀應(yīng)變小于3.0×10-3。但是,以水鎂石為原料采用物理法所制得產(chǎn)品的純度不高、晶形難以控制,嚴重影響了其阻燃性能。目前,優(yōu)質(zhì)氫氧化鎂主要是以金屬鎂和鎂鹽為原料,采用化學(xué)法制備所得,成本較高。因此,利用水鎂石資源制備高純、超細的氫氧化鎂對提高我國優(yōu)勢鎂資源的市場競爭力具有十分重要的意義。 本文以水鎂石為原料,通過水熱合成和水熱處理法制備出了超細、高純、顆粒均一、分散均勻的具有不同形貌的氫氧化鎂顆粒,利用X-射線衍射儀(XRD)和掃描電子顯微鏡(SEM)對所制得氫氧化鎂顆粒的晶相、形貌和顆粒尺寸進行了表征,結(jié)合實驗結(jié)果,對水熱條件下晶粒的形成機理進行了研究。本文取得了以下研究成果： (1)通過現(xiàn)場調(diào)研和大量的資料分析,研究了遼寧省水鎂石礦床形成的地質(zhì)條件、不同形態(tài)水鎂石的形成及其礦物學(xué)性質(zhì),為水鎂石的開發(fā)利用提供了地質(zhì)依據(jù)。同時,結(jié)合遼寧省水鎂石資源特點,提出制備定形氫氧化鎂晶體的技術(shù)方法。 (2)采用水熱合成法和水熱處理法分別制備出了高純、分散均勻、厚度為80-100nm、直徑為200-400nm的六方片狀和直徑為100-500nm、長度為1-20μm纖維狀氫氧化鎂。所得產(chǎn)物的特征峰值與氫氧化鎂的標準峰值完全一致,沒有雜峰出現(xiàn),(101)晶面的微形變小于3.0×10-3,這表明,所得產(chǎn)物為高端無機阻燃劑。 (3)系統(tǒng)研究了攪拌速度、填充度、前驅(qū)物濃度、反應(yīng)溫度、反應(yīng)時間、pH值、氫氧化鉀、硫酸根離子、溶劑和表面活性劑等對氫氧化鎂晶形的影響。通過計算(001)晶面和(101)晶面的衍射強度比值I001/I101,對比了不同晶面的優(yōu)先生長方向。 (4)研究了晶體的晶形和結(jié)晶度與過濾性能的關(guān)系,發(fā)現(xiàn)六方片狀晶體與纖維狀晶體相比,具有較好的過濾性能,通過控制晶體的晶形和結(jié)晶度可以顯著改善其過濾性能。 (5)根據(jù)大量的實驗數(shù)據(jù),結(jié)合現(xiàn)代物理學(xué)、溶液化學(xué)和結(jié)晶學(xué)知識,以“負離子配位多面體模型”為基礎(chǔ),發(fā)現(xiàn)晶體的形貌和尺寸由其內(nèi)部結(jié)構(gòu)和外在生長條件共同決定,晶體生長過程是生長基元在其界面疊加的過程。生長基元在晶體晶面的疊加過程受晶面結(jié)構(gòu)和外在生長條件的共同影響。 Mg(OH)64為氫氧化鎂晶體的生長基元,根據(jù)鍵價理論模型計算表明,氫氧化鎂的理想生長形態(tài)為正六邊形。Mg(OH)64生長基元在不同晶面的疊加過程受晶面上Mg-O-Mg鍵橋和位于“三配位”位置OH基團數(shù)目的影響。 外在生長條件通過影響生長基元的形成和生長基元在晶面的疊加過程來影響晶體的形成。 通過理論分析得到了和實驗結(jié)果相一致的結(jié)論。通過本文的工作,可以看出,生長基元模型把晶體生長過程中晶體的結(jié)構(gòu)、外在生長條件和晶體的生長形態(tài)緊密的聯(lián)系起來,具有很強的生命力。 本文研究為水鎂石制備定形氫氧化鎂晶體提供了理論基礎(chǔ)和技術(shù)方法。
[Abstract]:As an industrial mineral , brucite has been widely used in refractory , environmental protection , building materials , ceramics and nuclear industry .

Magnesium hydroxide is widely used in the fields of polymer , cable , building and decorative materials . The crystal form and particle size of magnesium hydroxide have been widely used in the fields of polymer , cable , building and decorative material .

The crystal phase , morphology and particle size of the prepared magnesium hydroxide particles were characterized by hydrothermal synthesis and hydrothermal treatment by using brucite as the raw material . The crystal phase , morphology and particle size of the magnesium hydroxide particles were characterized by X - ray diffraction ( XRD ) and scanning electron microscopy ( SEM ) .

( 1 ) Through field investigation and abundant data analysis , the formation of brucite deposit in Liaoning province is studied , the formation of brucite in different forms and its mineral properties are studied , and the geological basis is provided for the development and utilization of brucite .

( 2 ) High purity , uniform dispersion , thickness of 80 - 100 nm , diameter of 200 - 400 nm and fibrous magnesium hydroxide of 100 - 500 nm and length of 1 - 20 渭m were prepared by hydrothermal synthesis and hydrothermal treatment respectively . The peak value of the product was 100 - 500 nm and the length was 1 - 20 渭m . The peak value of the product was identical with the standard peak value of magnesium hydroxide . The microdeformation of ( 101 ) crystal plane was less than 3.0 脳 10 - 3 , which showed that the product was high - end inorganic fire retardant .

( 3 ) The effects of stirring speed , filling degree , precursor concentration , reaction temperature , reaction time , pH value , potassium hydroxide , sulfate ion , solvent and surfactant on the crystal form of magnesium hydroxide were studied .

( 4 ) The relationship between crystal form and crystallinity and filtration performance was studied . It was found that the hexagonal flake crystals had better filtration performance than the fibrous crystals , and the filtration performance of the crystals could be improved by controlling the crystal form and crystallinity of the crystals .

( 5 ) Based on a large number of experimental data , based on the knowledge of modern physics , solution chemistry and crystallization , the morphology and size of crystals are determined by their internal structure and external growth conditions .

Mg ( OH ) 64 is a growth element of magnesium hydroxide crystal . According to the theoretical model of bond valence , it is shown that the ideal growth form of Mg ( OH ) 64 is regular hexagon . Mg ( OH ) 64 growth element is influenced by Mg - O - Mg bond bridge on the crystal plane and the number of OH groups in the " three coordination " position .

The external growth conditions affect the formation of the crystal by influencing the formation of growth elements and the stacking process of the growth elements on the crystal planes .

Through the work of this paper , it can be seen that the growth primitive model links the structure of the crystal to the growth condition and the growth form of the crystal in the process of crystal growth , and has strong vitality .

A theoretical basis and a technical method for preparing shaped magnesium hydroxide crystals from brucite are studied in this paper .
【學(xué)位授予單位】：東北大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2010
【分類號】：O614.22

【引證文獻】

相關(guān)碩士學(xué)位論文 前1條

1 孫元兵;鋰硼對氨法沉鎂的影響規(guī)律及氫氧化鎂晶體生長機理研究[D];中南大學(xué);2013年

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本文編號：1968543