Coating mechanism of nano-TiO_2 films on the surface of ultra-fine calcined coal kaolin particles

A new type of mineral composite was made by calcined coal kaolin.The interaction mechanism of an inorganic modification reagent TiOSO4 with the surface of ultra-fine calcined coal kaolin particles（substrate） was studied by X-ray photoelectron spectroscopy.The results show that chemisorption exists in the phase boundary between the modification agent and the substrate surface,while physical adsorption occurs on the modification layers of hydrate titanium dioxide.The interaction force was calculated and analyzed according to DLVO theory between ultra-fine calcined coal kaolin particles and hydrate titanium dioxide nano-particles in the modification system.It is shown that the both electrostatic force and van der Waals force are attractive,and the coacervation between ultra-fine calcined coal kaolin particles and hydrate titanium dioxide nano-particles leads to the coating of hydrate titanium dioxide on the surface of ultra-fine calcined coal kaolin particles.

In Situ Synthesis of NaY Zeolite with Coal-Based Kaolin

NaY zeolites were in-situ synthesized from coal-based kaolin via thehydrothermal method. The effects of various factors on the structure of the samples were extensivelyinvestigated. The samples were characterized by N_2 adsorption, XRD, IR and DTG-DTA methods, andthe results show that the crystallization temperature and amount of added water play an importantrole in the formation of the zeolite structure. The 4A and P zeolites are the competitive phasepresent in the resulting product. However, NaY zeolites with a higher relative crystallinity,excluding impure crystals and the well hydrothermal stability, can be synthesized from coal-basedkaolin. These zeolites possess a larger surface area and a narrow pore size distribution, and thismeans that optimization of this process might result in a commercial route to synthesize NaYzeolites from coal-based kaolin.

Research on the Occurrence of Titanium in Coal-Measure Kaoline in Songyi, Hubei

Using X-ray diffraction (XRD) analysis and an electron-probe microanalyser (EPMA), this research found that the main independent mineral of titanium (Ti) in the kaoline of Songyi is anatase. The granularity of anatase is from 0.5 μm to 1.5 μm, and some exceed 10 μm. This research provides important scientific evidence for the exploitation of the coal-measure kaoline in the South China.

Dry Separation of Iron Minerals from Low-Grade Coal-series Kaolin

Dry separation of iron mineral from low-grade coal-series kaolin in Hubei Province of China was investigated. The structure and chemical composition of the kaolin ore were determined by X-ray diffraction(XRD) and X-ray Fluorescence(XRF) analyses. The narrow particle size range classification, dry magnetic separation and calcination were carried out to evaluate the particle size distribution, and the relation between the content of iron and the whiteness. Experimental results revealed that the highest content of iron(3.70%) in kaolin ore was in the particle size range from 60 to 74 μm, and pyrite was the main occurrence of iron in the kaolin ore. Dry magnetic separation showed that the removal rate of iron in kaolin ore could be increased obviously after calcination, and the rate of iron removal was 60% in the particle size range from 60 to 74 μm. As pyrite can be transformed into hematite through calcination, thermodynamic studies and XRD analysis showed that the maximum content of hematite was obtained at 900 ℃, which would be more beneficial to magnetic separation.

Influence of Replacement Level of Coal-series Kaolin on Hydration of Ordinary Portland Cement by X-ray Diffraction/Rietveld Method

The influence of replacement level of calcined coal-series kaolin(CCK) on hydration of ordinary Portland cement(OPC) was studied by X-ray diffraction(XRD)/Rietveld method. X-ray diffraction/Rietveld method was used to quantify the crystalline phase composition of the hydrated samples. Additionally, the morphology of hydrated samples was observed by scanning electron microscopy(SEM). The results showed that, calcium hydroxide(CH), ettringite(AFt) and amorphous phase content in hydrated samples decreased as the replacement level of CCK increased, while AFm and str?tlingite increased, which was caused by the combination of dilute, physical and pozzolanic effects. The hydration of anhydrous cement phases was accelerated by physical effect but hindered by the retardation effect of CCK. The role of each effects was discussed in detail to analyze the mechanism of OPC hydration with CCK addition. The SEM images showed that the shortening of AFt at 1 day and the denser texture at 28 days was observed with CCK addition, which was caused by the physical and pozzolanic effects, respectively.

Synthesis of TiO₂/Al-MCM-41 Composites with Coal-Measure Kaolin and Performance in Its Photocatalysis

TiO2/Al-MCM-41 composites with various titania content were prepared by loading titania into the mesopores of Al-MCM-41 mesoporous molecular sieve from coal-measure kaolin as silicon and aluminum source via general sol-gel method and incipient wetness impregnation method. TiO2/Al-MCM-41 composites were characterized by XRD, FT-IR and SEM, and the photocatalytic degradation of methyl orange solution under visible light irradiation. The results showed that the titania crystalline phase was anatase, and the particles size of TiO2 increase with TiO2 content. The photocatalytic degradation rates of all samples prepared by sol-gel method and incipient wetness impregnation have been become stable by visible light irradiation for 150 min, and the highest degradation rate was 83.7% and 76% respectively.

Effect of Surfactant/Silica and Hydrothermal Time on the Specific Surface Area of Mesoporous Materials from Coal-Measure Kaolin

Mesoporous materials with the highest surface area were synthesized by hydrothermal treatment from coal-measure kaolin using cetyltrimethylammonium bromide（CTAB）as template.The effect of several factors on surface area of products also had been discussed.The products were characterized by FT- IR,HRTEM and N 2 adsorption and desorption isotherm plot methods.There was typical structure as Si-O,Si- OH and Si-O-Si of mesoporous materials in the framework of synthesized materials;the pore size distributions of the products showed a sharp peak at 3.82 nm.The effect of hydrothermal treatment time and the amount of template on the specific surface area of mesoporous materials was important,when the Surf/Si=0.135,and hydrothermal time=12 h,and the surface area of the product reached up to 1 070 m2/g,which was higher than other products.

STUDY ON UTILIZATION OF COAL-SERIES KAOLIN ROCK RESOURCES

In this paper, the main factors that influence on qualities of kaolin in the area are revealed by studying the properties of coal-series kaolin in Enshi, Hubei (P. R. China), technologies of ferrum and carbon elimination for coal-series kaolin are investigated , and ways to fully uti-lize the resource are hopeful to be sought.

高吸油量煅烧高岭土的制备与性能表征

通过插层剂二甲基亚砜、接枝剂甲醇和剥离试剂十六烷基三甲基溴化铵协同超声震荡辅助作用,将层状煤系高岭土剥离为超细片状煤系高岭土。通过X射线衍射(XRD)、傅里叶红外(FT-IR)、N_(2)吸附-脱附及扫描电镜(SEM)与能谱分析(EDS)等技术手段对煤系高岭土进行表征。结果表明,其层间距由层状煤系高岭土的0.708 nm扩大到片状煤系高岭土的1.12 nm,内部孔隙增加,形成了裂隙形状的介孔且孔径分布均匀。煅烧高岭土较煤系高岭土的吸油性能大幅提升,其吸油量从60~73 g/100 g煤系高岭土增至70~79 g/100 g煅烧高岭土。整个制备工艺流程中无引入强酸强碱等腐蚀性物质,提供了一种环境友好型煅烧高岭土制备技术。

煤矸石钠盐焙烧增白工艺与机理

大宗固体废弃物煤矸石的堆存带来严重的环境问题,因而综合利用与高值高效利用煤矸石十分紧迫与重要。煅烧是煤矸石资源化利用的重要加工手段。针对煅烧法存在能耗高、效率低的问题,通过研究钠盐种类及煅烧工艺对煤矸石增白效果的影响,得出了煤矸石煅烧前后样品的物相组成、微观形貌、孔结构及化学键变化情况,并在此基础上采用同步热分析与红外-质谱(TG-FTIR-MS)联用系统对NaCl煅烧过程中的气相产物与除杂增白机理进行了分析。结果表明:当煅烧温度为860℃时,NaCl煅烧煤矸石样品白度由原矿的38.5%提高到86.0%;碳质全部被氧化,黄铁矿(FeS_(2))脱硫转变为赤铁矿(Fe_(2)O_(3)),赤铁矿和金红石(TiO_(2))总质量分数下降到0.27%;当煅烧温度为800~860℃时,样品孔结构特性变化较小;当升高温度到950℃时,片层状的偏高岭石转变为圆球状的莫来石,比表面积和孔体积分别由原矿的12.91 m^(2)/g和0.056 cm^(3)/g显著下降到6.58 m^(2)/g与0.031 cm^(3)/g。当煅烧时间超过30 min后,煅烧产物的白度增加幅度变小,煅烧时间超过90 min后,煅烧产物的白度基本不再增加(86.6%~86.7%)。NaCl的加入对于煅烧产物化学键的影响较小,煅烧阶段的易挥发矿物质成分质量分数较低,主要气体产物为H_(2)O、HCl、CO_(2)和H_(2)S;NaCl与H_(2)O、SiO_(2)发生作用高温分解生成HCl气体,并与Fe_(2)O_(3)、TiO_(2)等杂质反应,生成气相氯化产物从料层表面逸出,实现了煤矸石除杂增白。

大同煤田石炭—二叠纪优质煤系高岭岩的成矿机制

以山西省大同煤田小峪煤矿的石炭—二叠系太原组优质煤系高岭岩为研究对象,开展了岩相学、矿物学、全岩地球化学、锆石U–Pb年代学和Lu-Hf同位素研究,旨在揭示优质煤系高岭岩的物源和成因机制。研究发现优质煤系高岭岩的矿物成分以高有序度高岭石为主,不含碎屑矿物石英、长石和白云母。部分样品含有勃姆石,是高岭石脱硅蚀变的产物。高岭岩中的锆石是典型的岩浆锆石,且年龄均一,集中在300 Ma左右,与煤层的沉积年龄一致,证实它们由火山灰蚀变形成。此外,高岭岩中普遍含有板/柱状和蠕虫状高岭石,也是火山灰蚀变的典型特征。这些粗晶高岭石认为是由火山灰中的晶屑,例如斜长石和黑云母等,蚀变形成的假象高岭石。锆石的εHf(t)以变化范围较大的负值为主,指示产出锆石的岩浆主要来源于古老大陆地壳物质的重熔,与华北北缘内蒙古隆起上同期大陆弧火山作用形成的岩浆岩锆石εHf(t)一致,说明它们之间存在同源关系。锆石的微量元素地球化学指纹也指示锆石的产出岩浆来源于大陆弧构造背景。华北克拉通北缘在晚古生代时期是安第斯型大陆边缘,在晚石炭—早二叠纪的聚煤时期,其北部的古亚洲洋板片在华北克拉通之下持续南向俯冲,诱发了频繁的大陆弧火山作用。喷发的火山灰降落在华北海陆过渡的泥炭沼泽中,经淋滤蚀变形成煤系高岭岩。

基于响应面法的煤矸石氯化焙烧除铁工艺参数优化

为解决煤矸石氯化焙烧除铁过程中氯化剂消耗量过高、焙烧时间掌握不准以及除铁率难以达到期望值的问题,以CaCl_(2)作为氯化剂对煤矸石进行氯化焙烧除铁,在焙烧温度分别为600℃,700℃,800℃,900℃,1000℃,CaCl_(2)添加量(质量分数)分别为5%,10%,15%,20%,25%,焙烧时间分别为90 min,120 min,150 min,180 min,210 min的单因素实验基础上,通过Design-Expert13.0.6软件设计和优化了煤矸石氯化焙烧除铁实验。通过方差分析、等高线分析、响应面分析证明了模型的可靠并分析了各变量之间的交互影响关系。运用响应面优化法以除铁率为指标优化了工艺参数。结果表明:焙烧温度与焙烧时间交互最为显著,CaCl_(2)添加量与焙烧时间交互最低。各影响因子按影响显著性由大到小依次为焙烧温度、CaCl_(2)添加量、焙烧时间;随着焙烧温度升高除铁率进一步提升,由于焙烧温度超过1000℃后产物会转为莫来石,因此控制焙烧温度不超过950℃,当CaCl_(2)添加量达到15%时除铁率最好,超过这一添加量会降低除铁率,焙烧时间达到180 min时除铁率基本上达到了最高值,继续延长焙烧时间对除铁率的影响不大;对响应面模型预测并优化后得到了最佳的工艺条件,即焙烧温度为915℃,CaCl_(2)添加量为15%,焙烧时间为175 min,在此条件下除铁率达到了95.23%,实验值与预测值基本一致。

煤矸石制备高岭土除铁技术进展

煤矸石及其灰渣中含有丰富的硅铝资源,其中的氧化铝和二氧化硅的占比与高岭石化学组成十分接近。以煤矸石为原料制备高岭土,既可以实现固废的资源化利用,还可以扩大高岭土的矿物来源。煤矸石中铁的存在会影响高岭土的制备质量,除铁是制备工艺的关键步骤之一。本文总结了煤矸石制备高岭土现状及煤矸石除铁的必要性,详细介绍了目前最常用的两种除铁方法,即磁选法和化学漂白法。煅烧煤矸石制备高岭土的主要技术路线有“先磨后烧”和“先烧后磨”,技术路线的选择主要取决于原料的性质和产品的需求。在实际应用中,需综合考虑煤矸石性质和除铁工艺的优缺点,选择合适的除铁方法和工艺流程,以实现高效、环保的除铁目标。

高岭土粒径对新疆煤积灰行为及烧结特性的影响

针对燃烧新疆煤面临严重的沾污结渣问题,添加高岭土添加剂是缓解该问题的有效途径。结合沉降炉积灰实验和固定床烧结实验对不同粒径高岭土的防控性能与机理进行研究。结果表明:高岭土通过自身的稀释作用和与煤中矿物的交互作用两方面共同改变新疆煤的成灰特性,进而影响积灰行为与烧结特性;细高岭土虽然通过交互作用可以有效抑制碱性物质气相沉积,但添加剂自身的稀释作用导致成灰粒径较小,更易在初始阶段形成积灰;在两方面的综合作用下,细高岭土和粗高岭土对初始阶段积灰生长的防控效果相近;此外,添加细高岭土后更小的成灰粒径分布促进灰烧结程度的发展,不利于沉积物的吹灰清除。

煤气化细渣基聚合硅酸铝铁絮凝剂的制备与性能研究

综合利用煤气化细渣的天然成份(富含Si、Al、Fe、Ca),以酸浸+碱溶方法制备新型聚合硅酸铝铁絮凝剂(PSAFC),在优化制备条件的基础上,采用X射线荧光光谱仪(XRF)、X射线衍射(XRD)和傅里叶变换红外光谱(FT-IR)对PSAFC进行了表征,证明PSAFC是由Si、Al、Fe、Ca等元素聚合而成非晶相、无定形的高分子无机絮凝剂。同时,以高岭土悬浊液为研究对象,对PSAFC絮凝性能进行了研究。结果表明:当PSAFC质量浓度为50 mg/L,pH为10时,高岭土悬浊液初始浊度低于1439 NTU时,PSAFC对其均具有较好的絮凝性能,浊度去除率均可达95%以上。该研究可为煤气化细渣的综合利用与高分子无机絮凝剂的制备提供新的途径与方法。

立式辊磨在煤系高岭土高细粉制备中的应用

根据煤系高岭土干法制粉的工艺系统现状及对制粉系统的要求,介绍了LM型立式辊磨机的结构、工作原理、及针对工艺要求对磨机做的特殊优化,并分享一个实际投产运行的一个案例。结果表明:我公司针对325目高岭土立磨改进的技术路线具有可行性,同时证明立磨在煤系高岭土干法制粉行业中可以满足大规模生产作业,适合推广。

不连沟煤矿煤矸石中分选高岭岩试验研究

为了实现煤矸石的多用途资源化利用,以不连沟煤矿煤矸石为研究对象,在分析煤矸石的理化特性,确定高岭岩在煤矸石中赋存状态的基础上,探讨了煤矸石分选高岭岩的理论与方法,并研究了不同煅烧温度、煅烧时间对高岭岩煅烧高岭土白度的影响。试验结果表明:通过基于图像识别和物质识别的智能干选及风力分选技术,可以从煤矸石中有效分选出高岭岩,高岭岩煅烧高岭土过程中,在煅烧温度为1 000℃、煅烧时间3 h的条件下,高岭土产品的白度可达84%,可满足二级白度高岭土的工业应用要求。

河南省煤系高岭岩资源特征与综合利用研究

煤炭是我国的基础能源,煤系中伴共生有储量大的高岭岩(土),加强煤系共伴生矿产资源综合利用,符合国家能源资源加工利用重大需求。针对河南省主要矿区对高岭岩矿产综合利用不高问题,分析了河南省煤系地层高岭岩的地质特征及分布规律,并通过对省内高岭岩样品的X射线、差热分析、扫描电镜各种测试结果的研究,阐述了煤系地层高岭岩理化特征,指出了本溪组上部、太原组中部、山西组上部和下石盒组底部泥岩中硬质高岭岩比较稳定、品位较优。同时,结合目前省内一些高岭岩加工厂利用情况,通过生产煅烧高岭岩的试验,认为河南省煤系高岭岩可用以生产造纸涂料和橡胶塑料系列产品,为煤矿企业绿色综合开发有益伴共生矿产资源提供了其利用方向。

高岭土对准东高碱煤煤灰熔融特性影响的量子化学与实验研究

采用量子化学理论计算与实验表征相结合的方法,研究了高岭土对准东高碱煤煤灰熔融特性及其熔融过程中矿物质演变规律的影响,并从矿物质微观结构特性角度阐述了高岭土对改变准东煤煤灰熔融特性的影响机制。结果表明,准东高碱煤煤灰熔融温度随高岭土的添加呈现先快速升高后逐渐变缓的趋势,当高岭土添加比例大于10%时,其提高煤灰熔融温度的趋势变缓;准东高碱煤添加高岭土后,其在1 000-1200℃下的低熔融矿物钙长石、硬石膏等量明显减少,1 200-1 300℃下有一定量的莫来石生成,是其煤灰熔点升高的主要原因;高岭石分子结构中的O(26)、O(22)、Si(6)、Si(8)的反应活性较高,能够与灰中的Fe^(2+)等金属离子成键,促使高岭石的铝氧键断裂。煤中的碱金属或碱土金属(Na或Ca)氧化物中的的O2-,作为亲核试剂,与高岭石的Si(6)和Si(8)发生亲核反应,使桥氧键S-O-Si断裂。

低成本耐盐性超强吸水复合材料的研制

在用聚丙烯酸制备超强吸水材料的过程中加入一定量的煅烧煤系高岭土和丙烯酰胺能有效降低材料成本和提高其耐盐性。通过正交实验,找出了制备成本低和耐盐性好的超强吸水复合材料的条件,当煅烧煤系高岭土量为丙烯酸单体质量50%,丙烯酰胺加入量为70%,中和度为90%,引发剂和交联剂量分别为0.3%和0.025%时,制得产品吸生理盐水(0.9%N aC l溶液)和吸自来水率分别达到60 g/g和325 g/g,吸水后凝胶强度明显提高。