劉存成 ,馬家玉 ,2,覃遠(yuǎn)航 ,2,吳再坤 ,2,王存文 ,2*
1.武漢工程大學(xué)化工與制藥學(xué)院,湖北 武漢 430205;
2.綠色化工過程教育部重點(diǎn)實(shí)驗(yàn)室(武漢工程大學(xué)),湖北 武漢 430205
表面活性劑對(duì)磷鉀伴生礦中鉀浸出的影響
劉存成1,馬家玉1,2,覃遠(yuǎn)航1,2,吳再坤1,2,王存文1,2*
1.武漢工程大學(xué)化工與制藥學(xué)院,湖北 武漢 430205;
2.綠色化工過程教育部重點(diǎn)實(shí)驗(yàn)室(武漢工程大學(xué)),湖北 武漢 430205
針對(duì)我國嚴(yán)重匱乏可溶性鉀鹽資源,而非可溶性鉀資源卻非常豐富,如磷鉀伴生礦,因而探索從磷鉀伴生礦中提取可溶性鉀具有重要意義.本文強(qiáng)化了磷鉀伴生礦的酸浸過程,研究了在HCl-CaF2體系下,表面活性劑對(duì)磷鉀伴生礦中鉀浸出的影響.結(jié)果表明:陰離子表面活性劑可以強(qiáng)化鉀的浸出,陽離子表面活性劑對(duì)鉀的浸出未產(chǎn)生明顯影響,非離子表面活性劑會(huì)抑制鉀的浸出.通過篩選得到較佳的表面活性劑為十二烷基硫酸鈉(SDS),其添加量為1.25 g/L,與未添加SDS的相比,鉀浸出率提高了約8.5%,達(dá)到了98.01%.
表面活性劑;磷鉀伴生礦;鉀;鉀長石;浸出率
我國化肥營養(yǎng)元素比例嚴(yán)重失調(diào),多氮少磷、鉀的現(xiàn)象十分嚴(yán)重,因此急需發(fā)展磷鉀復(fù)合肥.湖北宜昌地區(qū)有豐富的磷鉀伴生礦資源[1],可考慮用來制備磷鉀復(fù)合肥.將礦中的磷、鉀變成可溶性的物質(zhì)是制備磷鉀復(fù)合肥的首要.礦中的磷容易浸出,因?yàn)榱字饕苑姿徕}的形式存在,而鉀主要存在于鉀長石中難以浸出,這是因?yàn)殁涢L石具有穩(wěn)定的Al-Si-O四面體結(jié)構(gòu),常溫常壓下幾乎不被分解.前期課題組用鹽酸處理磷鉀伴生礦,在優(yōu)化的工藝條件下,鉀浸出率高達(dá)90%以上[2].但仍然存在酸用量及添加劑用量大,反應(yīng)時(shí)間過長等問題,因此,急需對(duì)磷鉀伴生礦的酸浸過程進(jìn)行強(qiáng)化.
近年來表面活性劑的乳化、分散、潤濕、滲透等作用已經(jīng)有效的應(yīng)用于強(qiáng)化礦物浸出過程[3-5].如陳宇研究結(jié)果表明:陽離子表面活性劑可強(qiáng)化磷礦中磷的浸出,而陰離子表面活性劑則有一定的抑制作用[6];韓效釗[7]采用陰離子表面活性劑及陰離子與非離子表面活性劑的復(fù)配劑成功的提高了鉀長石粉中鉀的浸出率;吳愛祥[8]研究了加十二烷基硫酸鈉對(duì)銅浸出的影響,其可顯著提高銅的浸出率;Owusu[9]研究了鄰二胺以及間苯二胺對(duì)鋅礦中鋅的浸出的影響,結(jié)果表明礦中超過99%的鋅被浸出.但是,有關(guān)表面活性劑對(duì)磷鉀伴生礦的強(qiáng)化浸出研究極其有限,因此,本文采用不同類型的表面活性劑,研究其對(duì)磷鉀伴生礦中鉀浸出的影響,尋求較佳的表面活性劑及其用量.
十二烷基苯磺酸鈉(sodium dodecyl benzene sulfonate,SDBS)、油酸鈉(sodium oleate)、十二烷基硫酸鈉(sodium dodecyl sulfate,SDS)、三油酸甘油酯、聚乙烯醇(polyvinyl alcohol,PVA)、聚乙二醇(6000,polyethylene glycol,PEG)、十六烷基三甲基溴化銨(cetrimonium bromide,CTMAB)、溴化十六烷基吡啶(bromohexadecyl pyridine,CPB)、六次甲基四胺(hexamethylen etetramine)均為化學(xué)純;氟化鈣、鹽酸、氯化鉀等均為分析純;磷鉀伴生礦(主要化學(xué)成分見表1)來自湖北宜昌殷家坪礦區(qū).
表1 宜昌磷鉀伴生礦化學(xué)組成Tab.1 Chemical compositions of phosphorus-potassium associated ore from Yichang of China %
集熱式恒溫加熱磁力攪拌器(DS-101S),循環(huán)式水式真空泵(SHZ-DIII),原子吸收分光光度計(jì)(4530F),電子天平(PL203),量筒(100 mL)等.
將一定質(zhì)量分?jǐn)?shù)的鹽酸溶液80 mL加入到三口燒瓶中,到達(dá)一定溫度后,將提前混合均勻的礦粉、表面活性劑及氟化鈣加入瓶中.在規(guī)定的時(shí)間內(nèi)取樣、過濾,濾液定容在容量瓶中,其濃度由火焰原子吸收分光光度計(jì)法測定[10],同時(shí)計(jì)算鉀的浸出率.待反應(yīng)一定時(shí)間結(jié)束后,將酸浸液和反應(yīng)殘?jiān)M(jìn)行過濾分離,濾渣用去離子水洗滌3次后放在干燥箱中烘干,其物相組成由XRD確定.
磺酸鹽型與硫酸鹽型是最具有代表性的陰離子表面活性劑,實(shí)驗(yàn)中考察SDBS、油酸鈉、SDS三種陰離子表面活性劑對(duì)鉀浸出率的影響,實(shí)驗(yàn)結(jié)果如圖1所示.
圖1 陰離子表面活性劑對(duì)鉀浸出的影響(液固比4∶1;鹽酸質(zhì)量分?jǐn)?shù)22.5%;浸出溫度90℃;氟化鈣質(zhì)量4 g;浸出時(shí)間 7 h):(a)SDBS,(b)油酸鈉,(c)SDSFig.1 Effect of anionic surfactants on dissolution fraction of potassium.(L/S 4∶1;HCl concentration 22.5%;leaching temperature 90 ℃;CaF2dosage 4 g;leaching time 7 h):(a)SDBS;(b)sodium oleate;(c)SDS
圖1表明,陰離子表面活性劑可強(qiáng)化磷鉀伴生礦的浸出過程,提高鉀的浸出率和縮短反應(yīng)達(dá)到平衡的時(shí)間.隨著陰離子表面活性劑的濃度的增大,鉀浸出率逐漸增大.不同濃度的陰離子表面活性劑對(duì)鉀的浸出具有不同的促進(jìn)作用,比如SDS、SDBS和油酸鈉的較佳濃度分別為1.25 g/L,3.75 g/L和2.5 g/L.陰離子表面活性劑的這種強(qiáng)化浸出作用可解釋如下:當(dāng)陰離子表面活性劑溶解到酸浸液中,將會(huì)發(fā)生水解[11],然后通過離子交換吸附到固液界面上,從而降低了酸浸液表面張力,增加了礦物接觸表面潤濕性能.另一方面,當(dāng)陰離子表面活性劑發(fā)生水解后吸附到固液界面上,從而產(chǎn)生吸附膜,使得礦物顆粒的分散性和酸浸液中鹽酸和氟化氫的滲透性增強(qiáng),有利于鉀的浸出[12].但是當(dāng)陰離子表面活性劑的濃度進(jìn)一步增加,可能超過表面活性劑的臨界膠束濃度,形成膠束,從而抑制了鉀的浸出[13].通過比較,可知較佳的陰離子表面活性劑為SDS,其添加量為1.25 g/L,與未添加SDS的相比,鉀浸出率提高了約8.5%,達(dá)到了98.01%.
研究了CTMAB,CPB,六次甲基四胺三種常見陽離子表面活性劑對(duì)鉀浸出率的影響,實(shí)驗(yàn)結(jié)果如圖2所示.
由圖2可知,陽離子表面活性劑能夠加快反應(yīng)速率,縮短反應(yīng)達(dá)到平衡的時(shí)間,但是對(duì)鉀的浸出率未產(chǎn)生明顯影響.可能原因是強(qiáng)酸性溶液降低了陽離子的表面活性,導(dǎo)致陽離子表面活性劑不能夠吸附到固液界面上[14].因此,陽離子表面活性劑僅縮短反應(yīng)達(dá)到平衡的時(shí)間,但不能提高鉀的最終浸出率,并且不同濃度的陽離子表面活性劑對(duì)體系的影響作用也不同.
由于非離子表面活性劑在水中不電離,有更強(qiáng)的乳化性能[15],不同于陰離子及陽離子表面活性劑.選用三油酸甘油酯(glycerol trioleate)、PVA、PEG三種常見的非離子表面活性劑,考察陰離子表面活性劑對(duì)鉀浸出的影響,結(jié)果如圖3所示.
由圖3可知,當(dāng)非離子表面活性劑被加入到體系當(dāng)中,鉀的浸出受到了抑制,隨著加入量的增加,鉀的浸出率出現(xiàn)明顯的下降.原因可能是可非離子表面活性劑在水中無法解離成離子狀態(tài),因而不可以在固體表面產(chǎn)生強(qiáng)烈吸附,只有弱的靜電力作用于礦物表面,不可能使鉀長石的表面性質(zhì)發(fā)生顯著變化,鉀長石表面Al3+區(qū)不會(huì)產(chǎn)生正電荷空洞[16].另外,由于非離子表面活性劑容易形成大量泡沫,對(duì)礦表面產(chǎn)生包裹現(xiàn)象,阻礙了氫氟酸和鹽酸[17]與礦的反應(yīng).由此可知,非離子表面活性劑不利于鉀的浸出.
圖2 陽離子表面活性劑對(duì)鉀浸出的影響(液固比4∶1;鹽酸分?jǐn)?shù)22.5%;浸出溫度90℃;氟化鈣質(zhì)量4 g;浸出時(shí)間7 h):(a)CTMAB;(b)CPB;(c)六次甲基四胺Fig.2 Effect of cationic surfactants on dissolution fraction of potassium(L/S 4∶1;HCl concentration 22.5%;leaching temperature 90℃;CaF2dosage 4 g;leaching time 7 h):(a)CTMAB;(b)CPB;(c)hexamethylenetetramine
圖3 非離子表面活性劑對(duì)鉀浸出的影響(液固比4∶1;鹽酸質(zhì)量分?jǐn)?shù)22.5%;浸出溫度90℃;氟化鈣質(zhì)量4 g;浸出時(shí)間 7 h):(a)三油酸甘油酯;(b)聚乙烯醇;(c)聚乙二醇Fig.3 Effect of nonionic surfactants on dissolution fraction of potassium(L/S 4∶1;HCl concentration 22.5%;leaching temperature 90 ℃;CaF2dosage 4 g;leaching time 7 h):(a)glycerol trioleate;(b)1 750±50,polyvinyl alcohol(PVA);(c)PEG-6000,polyethylene glycol
對(duì)分別加入 SDBS、SDS、PEG-6000、CTMAB、PVA及未加表面活性劑的浸出渣進(jìn)行了XRD分析,同時(shí)與原礦XRD做了對(duì)比,結(jié)果如圖4所示.圖4表明:鉀長石、膠磷礦及石英是原礦的主要物相組成.加入陰離子表面活性劑后,鉀長石的結(jié)構(gòu)遭到破壞,因而其衍射峰基本消失;而陽離子表面活性劑CTMAB加入后,鉀長石的衍射峰高度與未加表面活性劑的相當(dāng),說明CTMAB的添加未影響鉀的浸出率;與未加表面活性劑的相比,加入非離子表面活性劑(PEG-6000與PVA)后,鉀長石的衍射峰增強(qiáng),因此可以說,非離子表面活性劑對(duì)于鉀的浸出具有抑制作用,與前述實(shí)驗(yàn)結(jié)果相一致.
用鹽酸處理磷鉀伴生礦,表面活性劑的加入影響了鉀的浸出率.
1)陰離子表面活性劑(SDBS、SDS、油酸鈉)有利于鉀的浸出.而較佳的表面活性劑為SDS,其添加量為1.25 g/L,與未添加SDS的相比,鉀浸出率提高了約8.5%,可達(dá)98.01%.
2)陽離子表面活性劑(CTMAB、CPB、六次甲基四胺)的加入未對(duì)鉀的浸出率產(chǎn)生明顯影響,但縮短了反應(yīng)到達(dá)的平衡時(shí)間.
3)非離子表面活性劑(如三油酸甘油酯、PVA、PEG)可抑制鉀的浸出,并且隨著添加量的增加,鉀浸出的抑制作用愈明顯.
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Effect of Surfactants on Leaching of Potassium from Phosphorus-Potassium Associated Ore
LIU Cuncheng1,MA Jiayu1,2,QIN Yuanhang1,2,WU Zaikun1,2,WANG Cunwen1,2*
1.School of Chemical Engineering&Pharmacy,Wuhan Institute of Technology,Wuhan 430205,China;
2.Key Laboratory of Green Chemical Process(Wuhan Institute of Tchnology),Ministry of Education,Wuhan 430205,China
China is rich in the insoluble potash ores such as phosphorus-potassium associated ore compared with the soluble hoevellite as a scarce resource in China.Thus,the extraction of soluble potassium from phosphorus-potassium associated ore has important significance.The intensification of the acid leaching process of phosphorus-potassium associated ore was investigated in this paper.The effect of surfactants on the leaching of potassium from phosphorus-potassium ore in HCl-CaF2media was studied.It was found that anion surfactants could enhance the dissolution fraction of potassium.Cationic surfactants has not obvious effect and nonionic surfactants could inhibit the leaching of potassium.Moreover,sodium dodecyl sulfate(SDS)has the best effect in the selected surfactants.The leaching rate of potassium increases by 8.5%compared with no SDS and reaches 98.01%by adding 1.25 g/L SDS.
surfactant;phosphorus-potassium associated ore;potassium;K-feldspar;leaching rate
1674-2869(2017)06-0536-05
TF826.1;TQ443.5
A
10.3969/j.issn.1674-2869.2017.06.003
2017-04-16
湖北省教育廳科學(xué)技術(shù)研究計(jì)劃青年人才項(xiàng)目(Q20151506)
劉存成,碩士研究生.E-mail:1052127804@qq.com
*通訊作者:王存文,博士,教授,博士研究生導(dǎo)師.E-mail:wangcw0120@163.com
劉存成,馬家玉,覃遠(yuǎn)航,等.表面活性劑對(duì)磷鉀伴生礦中鉀浸出的影響[J].武漢工程大學(xué)學(xué)報(bào),2017,39(6):536-540.
LIU C C,MA J Y,QIN Y H,et al.Effect of surfactants on the leaching of potassium from phosphorus-potassium associated ore[J].Journal of Wuhan Institute of Technology,2017,39(6):536-540.
張 瑞