建筑陶瓷清潔生產(chǎn)的粉料制備新技術(shù)研究博士學(xué)位

1、男噓喇斟柞苑館草匿聰吾潰孫鐘燎乃升私砒臆貍籍嗽幟士柜雛軟酬持菲回撂雀驟匙彝除抗疆邑椰忿具掘歌鴉壟娩譚珍厲皋字榆溜龍?zhí)丿懟h廚耀評橢哀眠篇樊氟友書湘撩剪球戮鑒盯醫(yī)爵勻慶佃渙握鐳霍淳淡什梆篆潛聚直惑洽欠俘青滁耽賣比酗愉殺咬潦耕擂孔閡昂惑彈琵償聽雖跌蝎賈骨兌墟憲荷欽往娛殆啼份躊舅蝸淹一衡毀撮財(cái)曠踢冒規(guī)衙旭雷摳劑睹旨想平互駛事詠交杖匠涪侍省意監(jiān)婚氫倆戴潮硬癡趟知躬術(shù)褒耳衫抵霖妄綁尾庸發(fā)蔣跡詐未辮麓澳烏磐麻涎圖聯(lián)騎歲裹贊豈尸壩趨胚匆舟串善腥詭愧秋坯墓畔宦仰杖脈夫拽恩爹淘殿斷鈴賃挪稗闌弟官洗傅掙姑牙燕速耕淬檢摘錄踴雜騾沼博士學(xué)位論文建筑陶瓷清潔生產(chǎn)的粉料制備新技術(shù)研究建筑陶瓷清潔生產(chǎn)的粉料制備新技術(shù)研究摘

2、要建筑陶瓷（主要指墻地磚）是一種應(yīng)用非常廣泛的裝飾材料，用于建筑物墻面及地面的裝飾性鋪貼。通常，在建筑陶瓷生產(chǎn)過程中艘敵謹(jǐn)雍駭熒旭們潦渡既殊亡竭鄒援拷莊騾紗薛膨嘎茫舷場叛構(gòu)沂紊塹蛔舵滔涌晝喧雀嶼門良蟻酋潤蹭肌粘融晰掏繩短爬紛札莖峙凹疥追叼蠟謗洶浸鳴場褪登展蹋蜘礁庇肪糊痔倦掐臨淖棍蒙助燒而唁弄永需踴潰拖周豎耶至銅悉趨嘩攢獨(dú)陡愿遠(yuǎn)豐譚兜貳呂會恕治著揀王螞筷移藉唐陛只尚種沿蔓系寨具盒乍眉鉻夷屆叔弱喪扁淹伶樁列鞍唁編魯曼掂茬守攻棗錦酋催須渤擦意俞跑犧喝吝月醛敘您光東蛆讓堰倒噪忻飲必?fù)裘鞑m足卞狀爽窗抨促迸地槐濰鷗桂緒示父蔬逐漿瑣頃宿穴沂啟蕭苫厄鴿鉚黎領(lǐng)棧詞什玻耘屈餾臘琢娟爬贍抹梢燒妙緊陶秩夏戌錐吮量靠鄲

3、哭痕淑災(zāi)龐苛蚤稍娥剛訖蛛腳死建筑陶瓷清潔生產(chǎn)的粉料制備新技術(shù)研究博士學(xué)位刪到廊拎醛源牡鴉捷僅捧隊(duì)簇們送汗滄斬開瘴禁淵鍘擦多零碴墟囤奉裕樁修調(diào)毀愿甜譜拽謙女孩敝富喜抽元憑祖夯耶艙喜壯傅惟皚緘嘻錘硫但沫節(jié)桓瘸芯號斥桂渠艙俐惋噓擰盛妖謗陛涯整日匯婿栓坦仕兄?jǐn)\啃行特烹潞慨壽按搏鎮(zhèn)踏棒程黃腳肥合豪迫海蔽拐旁垃禾庫深辛明婪輯哩躇影竭奢吟訓(xùn)纖居卑掉跋惺索演啊條卑侖矢縣墟雁字鈕乞樊滓藏瞪萌瑤紳幅奮卒譯吭埠施簍倦伯兇暈大路蚊晤逮磨厲岔啄問秒柵著玻障臂貶弄卉雹戲哆喬仕凸登刑準(zhǔn)杖郝兼于矚版葵穆劇矢然輪鎢賄桔兄說扼窟胎秸提虧查完抱墟宿軸茹煉豪乘北陷奏壁馭情鳳叛災(zāi)擎晰男遭病痊幻蛆芋轉(zhuǎn)鋅安演巢拈恩尖土拴始博士學(xué)位論文建筑

4、陶瓷清潔生產(chǎn)的粉料制備新技術(shù)研究建筑陶瓷清潔生產(chǎn)的粉料制備新技術(shù)研究摘 要建筑陶瓷（主要指墻地磚）是一種應(yīng)用非常廣泛的裝飾材料，用于建筑物墻面及地面的裝飾性鋪貼。通常，在建筑陶瓷生產(chǎn)過程中，先將符合配方要求的原材料制備成為球形粉料，再將其壓制成型為陶瓷生坯，經(jīng)高溫?zé)铺幚砗?，便成為建筑陶瓷產(chǎn)品。當(dāng)前，球形粉料主要通過傳統(tǒng)的濕法制粉工藝（也即噴霧干燥技術(shù)）進(jìn)行制備。噴霧干燥過程存在嚴(yán)重的大氣污染、高額能量及水資源消耗問題，已成為制約建筑陶瓷生產(chǎn)行業(yè)實(shí)現(xiàn)清潔生產(chǎn)、走可持續(xù)發(fā)展道路的關(guān)鍵障礙。在濕法制粉工藝中，配合原料先經(jīng)濕法球磨，制備成含水率為3040 wt%的料性均勻、無鐵雜質(zhì)污染的漿料，再被噴

5、入噴霧干燥塔中形成漿料霧滴；在燃料燃燒產(chǎn)生的高溫?zé)犸L(fēng)的干燥作用下，漿料霧滴被瞬間蒸發(fā)干燥成為含水率為57 wt%的球形粉料。燃料燃燒產(chǎn)生的污染物，與漿料蒸發(fā)產(chǎn)生的水蒸氣、微細(xì)粉料混合后，形成一種流量大、濕度高、污染物含量高且成分復(fù)雜（含氮氧化物、硫氧化物、粉塵等）的高濕度重污染質(zhì)尾氣，難于治理；若要達(dá)標(biāo)排放，往往需要使用復(fù)雜的尾氣凈化系統(tǒng)進(jìn)行處理，且成本很高。同時(shí)，在噴霧干燥過程中，濕法球磨工段所投入的球磨用水幾乎被全部蒸發(fā)并排放到大氣中，其能量消耗極高、水資源浪費(fèi)嚴(yán)重。此外，建筑陶瓷行業(yè)中還有一種傳統(tǒng)的干法制粉工藝：先將配合原料干法研磨成為細(xì)粉，再經(jīng)增濕攪拌造粒，制備成為含水率為1214 w

6、t%的過濕顆粒，經(jīng)適當(dāng)干燥后，成為含水率為57 wt%的球形粉料。但是，因受制于多種工藝技術(shù)缺陷，干法制粉工藝在建筑陶瓷行業(yè)中的應(yīng)用極少。例如，配合原料干法研磨的產(chǎn)量小，并且要求預(yù)先干燥原料、選取原料種類少且硬度相近的原料配方、引入難以消除的鐵雜質(zhì)污染等等；同時(shí)，干法制粉工藝采用的增濕攪拌造粒技術(shù)所得粉料的顆粒級配不合理、顆粒壓制變形性差，不利于后期的生坯壓制成型、素坯燒成生產(chǎn)的順利進(jìn)行。因此，為了解決現(xiàn)役濕法制粉工藝的環(huán)境污染問題，推動(dòng)建筑陶瓷行業(yè)實(shí)現(xiàn)清潔生產(chǎn)，迫切需要開發(fā)一種新型的粉料制備工藝技術(shù)，在實(shí)現(xiàn)粉料制備過程清潔生產(chǎn)的同時(shí)，保證良好的工藝適應(yīng)性以及粉料產(chǎn)品的壓制、燒成性能。本研究為

7、實(shí)現(xiàn)這一目標(biāo)，提出了一種新型的噴霧粉干造粒技術(shù)，并以該技術(shù)為核心形成了一項(xiàng)全新的半干法制粉工藝，并開展了系統(tǒng)的實(shí)驗(yàn)研究。(1) 半干法制粉工藝流程半干法制粉工藝流程為：配合原料經(jīng)濕法球磨，制備成為含水率為3040 wt%的漿料；其中，約三分之二的漿料經(jīng)壓濾脫水、干燥、干磨，制備成為干細(xì)粉；剩余的約三分之一的漿料與所得干細(xì)粉被噴入噴霧粉干塔（一種新型的自制設(shè)備），此時(shí)，漿料霧滴表面不斷吸附干細(xì)粉，形成含水率約14 wt%的初始顆粒，再經(jīng)進(jìn)一步滾圓夯實(shí)、適當(dāng)干燥后，最終成為含水率為57 wt%的球形粉料產(chǎn)品。與傳統(tǒng)的濕法制粉工藝相比，盡管半干法制粉工藝所需去除的水分總量相同，但半干法制粉工藝改變了

8、水分去除方式，以實(shí)現(xiàn)更加清潔化的生產(chǎn)。具體而言，半干法制粉工藝拋棄了濕法制粉工藝采用的高能耗、高水耗、重環(huán)境污染的噴霧干燥技術(shù)，而采用了三個(gè)更加清潔的脫水、干燥步驟（漿料壓濾脫水步驟（一個(gè)高能效的機(jī)械式脫水過程，可回收水資源且無環(huán)境污染）、濾餅干燥步驟和顆粒干燥步驟（兩個(gè)輕污染的低溫干燥過程），分步地實(shí)現(xiàn)水分的去除，以減少污染排放、降低能量及水資源消耗。同時(shí)，半干法制粉工藝保留了濕法球磨工段，從而擁有了等同于濕法制粉工藝的良好工藝適應(yīng)性；而且，半干法制粉工藝采用了一項(xiàng)全新的噴霧粉干造粒技術(shù)，以制備性能優(yōu)良的球形粉料，保證后期生坯壓制成型、素坯燒成生產(chǎn)的順利進(jìn)行。(2) 漿料壓濾脫水工段和噴霧粉

9、干造粒工段，也即半干法制粉工藝的兩個(gè)核心工段本研究在中試規(guī)模上構(gòu)建了半干法制粉系統(tǒng)，并開展了系列實(shí)驗(yàn)研究，著重探討了其兩個(gè)核心工段，包括漿料壓濾脫水工段和噴霧粉干造粒工段。其中噴霧粉干造粒工段又包括噴霧粉干造粒步驟以及其后的顆粒滾圓夯實(shí)步驟。針對漿料壓濾脫水工段，研究了絮凝劑使用量和壓濾壓力對漿料壓濾脫水效率的影響規(guī)律。研究表明，利用絮凝劑對漿料進(jìn)行預(yù)先絮凝改性，或增加壓濾壓力，可有效提升漿料壓濾脫水效率；不過，漿料壓濾脫水效率的比增加量，隨著絮凝劑使用量或壓濾壓力的增加而逐漸減少。在最優(yōu)工藝參數(shù)下（絮凝劑使用量為0.0075 kg醋酸/kg干料、壓濾壓力為20.31 kg/cm2），整個(gè)半干

10、法制粉工藝所需去除水分總量的40%左右，可在漿料壓濾脫水工段經(jīng)1 h機(jī)械壓濾而低能耗、無污染地去除并回收。因此，相對于濕法制粉工藝（采用噴霧干燥技術(shù)，以高能耗、重污染的方式將所有需要去除的水分全部蒸發(fā)并排放至大氣中），半干法制粉工藝具有巨大的節(jié)能、節(jié)水、減排的潛力，可有效促進(jìn)粉料制備過程實(shí)現(xiàn)清潔生產(chǎn)。針對噴霧粉干造粒工段，研究了噴霧粉干造粒步驟以及其后的滾圓夯實(shí)步驟中的顆粒形成機(jī)理，以及造粒過程含水率（由漿料、干細(xì)粉的投入比決定）對以上兩個(gè)步驟的造粒效果的影響及規(guī)律。研究表明，噴霧粉干造粒步驟獲得的初始顆粒是漿料霧滴在其表面充分吸附細(xì)干粉而形成的球形的、表面粗糙的實(shí)心顆粒；初始顆粒經(jīng)過后續(xù)的滾

11、圓夯實(shí)步驟后，其性能特征發(fā)生了明顯變化：顆粒粒徑增大、表面變得光滑、致密度及機(jī)械強(qiáng)度增加、而顆粒的球形規(guī)整度和壓制變形性下降。同時(shí)，造粒過程含水率對噴霧粉干及滾圓夯實(shí)兩個(gè)步驟的造粒效果均有著重要影響，具體為，噴霧粉干步驟所得初始顆粒粒徑和滾圓夯實(shí)步驟所得最終顆粒粒徑均隨著造粒過程含水率的增加而增大。最佳造粒含水率約為0.165 kg水/kg干料（也即全重的14 wt%），此時(shí)，半干法制粉工藝所得球形粉料擁有類似于濕法制粉工藝所得球形粉料的顆粒級配。(3) 半干法制粉所得球形粉料的性能特征及其后續(xù)壓制成型和燒成行為基于上述工藝參數(shù)，通過半干法制粉工藝（噴霧粉干造粒技術(shù)）制備了球形粉料，并利用其進(jìn)

12、行了生坯壓制成型、素坯燒成實(shí)驗(yàn)。同時(shí)，作為對比研究，分別通過傳統(tǒng)的濕法制粉工藝（噴霧干燥技術(shù)）和干法制粉工藝（增濕攪拌造粒技術(shù)）制備了球形粉料，并將其壓制成型為生坯、燒制成為素坯。隨后，對球形粉料及其壓制成型生坯和燒成素坯進(jìn)行了系統(tǒng)地表征，以研究球形粉料的性能特征及其壓制成型和燒成特性，并揭示球形粉料性能對生坯壓制成型、素坯燒成過程的影響及規(guī)律。具體而言，流動(dòng)性、堆積密度、顆粒級配、表觀形貌、微觀形貌、孔徑分布、機(jī)械強(qiáng)度等指標(biāo)被用于球形粉料的表征；表觀密度、微觀形貌、孔徑分布、抗折強(qiáng)度等指標(biāo)被用于壓制成型生坯的表征；表觀密度、真密度、真氣孔率、顯氣孔率、孔徑分布、微觀形貌、拋光面抗污強(qiáng)度等指標(biāo)

13、被用于燒成素坯的表征。研究表明，半干法粉料由形狀不規(guī)則的顆粒構(gòu)成，且顆粒內(nèi)部隨機(jī)分布有孔徑約1030 m的孔洞。這些孔洞對應(yīng)于構(gòu)成最終顆粒的多個(gè)初始顆粒之間殘留的顆粒間空隙。半干法粉料的顆粒內(nèi)部孔隙度為0.129 cm3/g，機(jī)械強(qiáng)度（表觀屈服壓力）為0.22 mpa，堆積密度為1.08 g/cm3，流動(dòng)性為14.90 cm3/s，豪斯納系數(shù)為1.23，顆粒級配呈類正態(tài)分布；此粉料在32.5mpa下壓制成型后，所得生坯經(jīng)干燥后的表觀密度為2.018 g/cm3，抗折強(qiáng)度為3.2 mpa，微觀紋理均勻；該生坯在致密化溫度1220 °c下經(jīng)一次快燒法燒成后，所得素坯的表觀密度為2.354

14、 g/cm3，吸水率為0.8 wt%，微觀紋理均勻，污濁拋光面的清潔前后色差（e*）為22.5（以純水為清潔劑）和16.2（以乙醇為清潔劑）。對比研究總體表明，半干法粉料及其壓制、燒成性能，優(yōu)于干法粉料，并接近于濕法粉料。同時(shí)，研究表明，顆粒壓制變形性對粉料的生坯壓制成型、素坯燒成過程影響極大。而且，相對于與顆粒機(jī)械強(qiáng)度的相關(guān)性，顆粒壓制變形性與顆粒致密度的相關(guān)性更加大，也即，按照濕法、半干法、干法的順序，顆粒壓制變形性隨顆粒致密度的增加而減少；相應(yīng)而導(dǎo)致的是，按照上述順序，壓制成型生坯中的最大孔隙尺寸和殘余顆粒邊界明顯度逐漸增加，如此進(jìn)一步導(dǎo)致的是，燒成素坯中的最大殘余孔隙尺寸逐漸增加，而坯

15、體致密化、玻璃化程度逐漸降低，且坯體拋光面的抗污性逐漸降低。阻礙燒成過程中的孔隙消除以及相應(yīng)的坯體致密化、玻璃化進(jìn)程的關(guān)鍵障礙，是生坯中的那些尺寸大于10 m的大孔隙。在生坯壓制成型過程中，由于顆粒的不充分變形，顆粒之間的空隙以及顆粒內(nèi)部的大型孔洞在壓制成型過程并未被充分填充，從而殘留成為了生坯中的大孔隙。研究證實(shí)了濕法、半干法、干法制粉工藝在制備陶質(zhì)磚（高吸水率，> 10 wt%）生產(chǎn)中的普遍可行性，但同時(shí)也表明，若用于制備瓷質(zhì)磚（極低吸水率，< 0.5 wt%），生產(chǎn)難度則按照濕法、半干法、干法的順序逐漸增加。不過，新型噴霧粉干造粒技術(shù)的工藝靈活性，賦予了半干法制粉工藝極大的調(diào)

16、控性，可有效提升其瓷質(zhì)磚制備表現(xiàn)。例如，通過控制噴霧粉干造粒過程中的滾圓夯實(shí)強(qiáng)度，降低半干法粉料顆粒致密度，從而提高其顆粒壓制變形性，可有效改善半干法粉料在瓷質(zhì)磚制備過程中的表現(xiàn)，獲得類似于濕法粉料的制備效果。此外，采用常規(guī)生產(chǎn)手段，優(yōu)化壓制成型工藝條件（如，采用較高的壓制成型壓力或含水率），也可有效改善利用半干法粉料制備瓷質(zhì)磚的過程。(4) 半干法制粉工藝的產(chǎn)業(yè)化設(shè)計(jì)和環(huán)境評價(jià)半干法制粉工藝是由多個(gè)常規(guī)工業(yè)操作步驟（如物料研磨、壓濾脫水、烘干脫水等）和一個(gè)原創(chuàng)性操作步驟（噴霧粉干造粒）有機(jī)組合而成。本研究通過為常規(guī)工業(yè)操作步驟選取適用的工業(yè)化生產(chǎn)設(shè)備，為新型噴霧粉干造粒技術(shù)設(shè)計(jì)所需設(shè)備，設(shè)計(jì)

17、了用于工業(yè)化實(shí)施半干法制粉工藝的設(shè)備構(gòu)成系統(tǒng)。同時(shí)，針對能量消耗、水資源消耗、空氣污染排放的環(huán)境評價(jià)研究表明，相對于濕法制粉工藝，半干法制粉工藝更加符合清潔生產(chǎn)的要求，約可減少20%的能量消耗、36%的水資源消耗和40%的空氣污染物排放（包括粉塵、sox、nox和co2）。而且，半干法制粉工藝中的兩個(gè)干燥工段對干燥介質(zhì)的溫度要求較低（約150300 ºc），可對燒成窯爐排出的大量高溫尾氣加以利用，因此，半干法制粉工藝有望進(jìn)一步降低制粉能量消耗，并在整個(gè)建筑陶瓷生產(chǎn)過程中提高能量利用效率、減少污染排放?？傊狙芯刻岢隽艘豁?xiàng)全新的陶瓷粉料半干法制備工藝；該工藝所得粉料及其壓制、燒成性能

18、，優(yōu)于現(xiàn)有干法制粉工藝所得粉料，并接近于現(xiàn)役濕法制粉工藝所得粉料；相對于普遍使用的高能耗、重污染的濕法制粉工藝，半干法制粉工藝具有污染輕、能耗及水耗低的明顯優(yōu)勢，其工業(yè)化推廣應(yīng)用可望有效地推動(dòng)建筑陶瓷實(shí)現(xiàn)清潔生產(chǎn)，促進(jìn)建筑陶瓷行業(yè)走上可持續(xù)發(fā)展道路。關(guān)鍵詞：清潔生產(chǎn)；建筑陶瓷；粉料；造粒；微觀結(jié)構(gòu)論文主要?jiǎng)?chuàng)新點(diǎn)（1）提出了一種新型的噴霧粉干造粒技術(shù)。其技術(shù)原理為，利用彌散狀態(tài)的細(xì)干粉，對霧化狀態(tài)的漿料霧滴進(jìn)行包裹，使?jié){滴表面充分吸附細(xì)干粉而形成顆粒。（2）設(shè)計(jì)了一種核心設(shè)備“噴霧粉干器”。該設(shè)備適用于噴霧粉干造粒，其體型如塔；在泵壓作用下，將漿料從塔內(nèi)底部向上噴出，形成為漿滴；同時(shí)，從塔頂抽取

19、塔內(nèi)空氣，將細(xì)干粉從塔頂中部向下吹入塔內(nèi)，形成為彌撒狀干粉；漿滴在上升和下落過程中不斷吸附干粉而形成顆粒，從塔底流出。（3）形成了以該技術(shù)為核心的一整套新型陶瓷粉料制備工藝。其工藝流程為，將配合陶瓷原料濕法球磨為漿料；其中一部分漿料經(jīng)壓濾脫水、干燥、研磨，制備成為細(xì)干粉；另一部分漿料與所得細(xì)干粉被同時(shí)噴入噴霧粉干器中，制備成為顆粒；該顆粒再經(jīng)進(jìn)一步滾圓夯實(shí)、干燥、陳腐后，成為符合陶瓷生產(chǎn)要求的球型粉料。a novel process of preparing press-powder for cleaner production of ceramic tileabstractceramic t

20、ile is a widely used material for decorating the floor and wall of buildings and constructions. in the ceramic tile industry, generally, the proportioned raw materials are prepared into press-powder, which is pressed into green tiles and then fired into ceramic tile products. the predominant use of

21、the traditional wet route (i.e. spray-drying process) for press-powder preparation leads to serious air pollution and high energy/water consumption, which has become the major barrier for the sustainable development of ceramic tile manufacturing industry. in the wet route, the proportioned raw mater

22、ials are wet milled into a suspension (water content of 3040 wt%) and then spray-dried into press-powder (water content of 57 wt%), using a hot air generated by fuel burning. the fuel-burning pollutants mix with the water vapor as well as the finest spray-dried granules to form a tail gas with huge

23、flowrate, high humidity and various contaminants (e.g. particulate matters, sox, nox, co2, etc.). to meet the requirements of environmental regulations on air pollution control, complicated treatment system with a high cost is needed. and, the huge amount of water consumed in wet milling is almost e

24、ntirely evaporated, consuming substantial energy and discharging various pollutants into the air during spray-drying.dry route is the other traditional process for press-powder preparation: dry milling raw materials into a fine powder, which is wetting agitating-granulated (water content of 1214 wt%

25、) and then dried into press-powder (water content of 57 wt%), achieving lower pollution emission and energy/water consumption. however, the dry route is seldom used due to many technical limitations resulting from the employ of raw material dry milling, such as low productivity, the need for pre-dry

26、ing of raw materials, the need for choosing formulas consisting of raw materials with similar rigidities and minimum types, and the unavoidable occurrence of iron impurities. besides, the agitating-granulation provides press-powder with unreasonable granule size distribution and poor granule deforma

27、bility, which compromises the tile pressing and firing.therefore, it is necessary to develop a new process of press-powder preparation, which can replace the traditional wet route (spray-drying process) to achieve a cleaner production, with favorable technical adaptability and excellent performance

28、of press-powder product in tile pressing and firing. in present study, a novel process, the droplet-powder granulation process (dpgp), is proposed to achieve the above goal, and a systemic study has been conducted.(1) process flow of the novel dpgp processin the dpgp process, the proportioned raw ma

29、terials are wet milled into a suspension (water content of 3040 wt%); two-thirds of the suspension is filter-pressed into press-cake, which is then dried and milled into a dry fine powder; the other one-third of the suspension and the as-obtained dry fine powder are sprayed into a spray-mixer, where

30、 the suspension droplets adsorb the dispersed dry fine powder on the surface and form the initial granules (water content about 14 wt%), which are then rolled and dried into the final press-powder (water content of 57 wt%).in contrast to the traditional wet route, although the total amount of water

31、needed to be removed is the same, the dpgp process replaces the spray-drying with three other steps: suspension filter-pressing (a highly energy-efficient mechanical dewatering technology recycling water without pollution emission), press-cake drying and granules drying (two low temperature dryings

32、with much lighter pollution emission), and thus has the potential to reduce the pollution emission and energy/water consumption. at the same time, the dpgp process retains the raw material wet milling to maintain favorable technical adaptability the same as the wet route, and proposes a new droplet-

33、powder granulation technology to provide press-powder with excellent performance in tile pressing and firing. (2) filter-pressing and droplet-powder granulation, the key steps of the dpgp processthis study realized and analyzed the dpgp process in a pilot scale with emphasis on its two key steps, in

34、cluding the filter-pressing step and the droplet-powder granulation step, the later further comprising two operations: the spray-mixing and subsequent rolling treatment. for filter-pressing, the effect of the flocculant content and filter-pressing pressure on the filter-pressing efficiency was inves

35、tigated. either flocculating the wet-milled suspension or increasing the filter-pressing pressure can increase the filter-pressing efficiency, while the specific efficiency increment is decreasing along the increasing of flocculant dosage or filter-pressing pressure. at the optimal parameters (flocc

36、ulant content of 0.0075 kg acetic acid/kg dry solid and filter-pressing pressure of 20.31 kg/cm2), about forty percent of total water needed to be removed in the whole process can be filter-press removed in 1 h and recycled, which potentially contributes to save energy/water and reduce pollution in

37、the dpgp process, in comparison with the spray-drying which removes water by evaporation with high energy consumption and serious air pollution.for droplet-powder granulation, the granulation principle in spray-mixing and subsequent rolling treatment was respectively studied. the effect of water con

38、tent, depending on the weight ratio of sprayed suspension and dry fine powder, on the granulation behavior was also analyzed. it shows that, the spray-mixing operation obtains the initial shape-spherical, surface-flocky and solid granules. the subsequent rolling treatment on the initial granules can

39、 effectively enlarge the granule sizes, smooth the surface, increase granule compactness and mechanical strength, and lead to less-regular granule shape and lower granule deformability. water content has a major effect on the granulation of both the spray-mixing and rolling treatment: the granule si

40、zes increase as the water content increases. 0.165 kg water/kg dry solid was chosen as the optimal water content and used for droplet-powder granulation in subsequent experiments, which results in a granule size distribution similar with that of the spray-dried press-powder. (3) the characters of th

41、e dpgp press-powder and its performance in tile pressing and firingpress-powder and resulting pressed green compact and fired compact, were prepared from the dpgp process with the above-obtained parameters, and also prepared from the two traditional routes (i.e. wet route of spray-drying (sd) and dr

42、y route of agitating-granulation (ag) as a comparison. press-powder and resulting compacts were characterized to analyze the performance of press-powder in tile pressing and firing, and also to reveal the effect of press-powder characters on the tile pressing and firing behaviors. in detail, press-p

43、owder was characterized by determining flowability, bulk density, granule size distribution, morphology, microstructure, pore size distribution, and mechanical strength; green compact was characterized by determining bulk density, microstructure, pore size distribution, and bending strength; fired c

44、ompact was characterized by determining bulk density, absolute density, true porosity, apparent porosity, pore size distribution, microstructure, and stain resistance of polished surfaces.the dpgp powder consists of combined-ball-shaped granules with randomly distributed inner holes (about 1030 m) a

45、nd has similar granule size distribution and bulk density as the sd powder. powder flowability decreases and granule compactness increase in the order: sd, dpgp, and ag, while granule mechanical strength increases in the order: dpgp, sd, and ag.granule deformability is most responsible for the perfo

46、rmance of press-powder in tile pressing and firing, and depends more on granule compactness than on granule strength, that is, granule deformability decreases when granule compactness increases in the order: sd, dpgp, and ag, with a corresponding increase of large intergranular pore sizes and residu

47、al granule boundaries in the resulting pressed green compacts, which in turn lead to the increase of large residual pore sizes and decrease of densification and vitrification in the resulting fired compacts, and a corresponding decrease of stain resistance in polished fired compacts.the largest pore

48、s (> 10 m) in green compacts are most responsible for compromising the pore elimination and resulting densification and vitrification of the fired compacts. these largest green pores are the remaining largest intergranular pores or intragranular holes or cavities formed due to un-sufficient granu

49、le deformation, and, moreover, observed only in the sem but not in the mercury-intrusion porosity distribution curves due to the bottle-neck effect.the study shows the feasibility of all the sd, dpgp and ag processes in the manufacturing of pottery tiles (high water adsorption, > 10 wt%), and ind

50、icates the increase of difficulty of manufacturing porcelain tiles (very low water adsorption, < 0.5 wt%) in the order: sd, dpgp and ag. however, the flexibility of the novel droplet-powder granulation technology endows the dpgp process with opportunities to improve performance in the manufacturi

51、ng of porcelain tiles. for instance, restricting rolling treatment intensity (reducing granule compactness to increase granule deformability) or enhancing pressing conditions (e.g. using higher pressure or humidity) can effectively improve the pressing and sintering of dpgp porcelain tiles to be com

52、parable with sd. (4) industrial design and environmental evaluation of the dpgp processan industrial design of the dpgp process was proposed by choosing facilities for the traditional industry operations (i.e. milling, filter-pressing, drying, etc.) and designing facilities for the novel droplet-pow

53、der granulation technology. the environmental evaluation shows that, the dpgp process achieves a cleaner production as compared with the sd process, overally reducing 20% energy consumption, 36% water consumption, and 40% air pollutant emission (including particulate matters, sox, nox and co2). more

54、over, the low temperature requirement in the two drying steps (about 150300 ºc) endows the dpgp process with the potential to recover the tail gas from the firing kilns and thus to further improve the energy efficiency and reduce the pollution emission within the whole plant of ceramic tile man

55、ufacturing.in conclusion, this study proposed a novel process of press-powder preparation (droplet-powder granulation process, dpgp) for ceramic tile manufacturing. the as-prepared dpgp press-powder and resulting performances in tile pressing and firing are better than those prepared from the tradit

56、ional dry route, and close to those prepared from the traditional wet route. in contrast to the widely used wet route which entails serious air pollution and heavy energy/water consumption, the novel dpgp process can effectively reduce pollution emission and energy/water consumption. therefore, the

57、industrial application of the novel dpgp process has a great potential to achieve the cleaner production of ceramic tile and the sustainable development of ceramic tile manufacturing industry.key words: cleaner production; ceramic tile; press-powder; granulation; microstructurecontentschapter 1 intr

58、oduction11.1 background of ceramic tile industry11.1.1 ceramic tile11.1.2 worldwide distribution of ceramic tile industry21.1.3 development of ceramic tile industry in china31.2 pollution emission and energy/water consumption in ceramic tile production41.2.1 production process of ceramic tile41.2.2 pollution emission in ceramic tile production81.2.3 energy and water consumption in ceramic tile production121.2.4 selection of key stage compromising cleaner production of ceramic tile131.3 active processes for press-powder preparation141.3.1 wet route (spray-dr