Research on Factors Affecting Flotation and Desulfurization of Coal by Electrochemical Method

Influence of factors such as potential of electrolyte, electrolyzing time, concentration of electrolyte, and pH value on flotation and desulfurization of coal was researched. The result shows that the electrochemical reduction can enhance the desulfurization effect and increase the yield of clean coal under certain conditions. So it is an effective method.

Feasibility studies on cleaning of high sulfur coals by using ionic liquids

Coal has been used as an energy resource around the world, primarily for the generation of electricity. The cleaning of coal by removing its unwanted sulfur and mineral matter components is utmost essential before their gainful utilizations. The ionic liquids （ILs） are considered as non-toxic solvents for using in different industrial processes. The effect of two ILs namely, 1-n-butyl, 3-methylimidazolium tetrafluoro borate （ILl） and 1-n-butyl, 3-methylimidazolium chloride （IL2） in oxidative de-sulfurization and de-ashing of two industrially important high sulfur coal samples from Meghalaya （India） is discussed in this paper. The maximum removal of total sulfur, pyritic sulfur, sulfate sulfur and organic sulfur are observed to be 37.36 %, 62.50 %, 83.33 % and 31.63 % respectively during this oxidative process. The quantitative diffuse reflectance Fourier transform-infrared spectroscopy analysis supports the formation of sulfoxides （S--O） and sulfones （-SO2） and their subsequent removal during the oxidation of the coals in presence of ILs. The X-ray fluorescence combined with near edge X-ray absorption fine structure and scanning electron microscopic studies reveal the removal of mineral matters （ash yields） from the coal samples. The thermogravimetric analysis of the raw and clean coals indicates their high combustion efficiencies and suitability for using in thermal plants. The method is partially green and the ILs could be recovered and reused in the process.

Physico-chemical and elemental investigation of aqueous leaching of high sulfur coal and mine overburden from Ledo coalfield of Northeast India

Acid mine drainage （AMD） is one of the major problems in high sulfur coal mining areas generating acidic water. The acidic mine water generated contain hazardous elements in varying concentrations. The Northeastern Indian coalfield produces considerable amounts of AMD. The AMD and metal leaching from coal and mine over burden （OB） are the two important naturally occurring processes. In order to know the AMD potential, the aqueous leaching experiment of a few coal and OB samples from the Ledo colliery of the Northeastern coalfield, Mergherita （India）, at different time periods （1, 3, 5, and 8 h） and at different temperatures （25, 45, 65, and 90℃） were performed in the laboratory. The physico- chemical analysis of the aqueous leachates shows the pH, electrical conductivity （EC）, and total dissolved solid （TDS） in the range of 1.62-3.52, 106-2006 μs/cm, and 106-1003 ppm for the raw coal samples respectively. The OB samples produced pH, EC, and TDS in the range of 3.68-6.92, 48.6-480 μs/cm, and 69.5-240 ppm respectively. From the study, it was revealed that the concentrations of major （Si, A1, K, Na, Fe, Ca, Mg）, minor （Mn） and trace/hazardous elements （As, Ba, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, Zn） considerably change with leaching time as well as with leaching temperature. Out of these elements As, Cd, Hg, Pb, Cr, and Se are of greater environmental importance. Alteration of the physico-chemical structure of the coal and OB samples resulting from leaching was also studied by field emission scanning electron microscope- energy-dispersive X-ray spectroscopy method. The release of the potentially hazardous elements from the raw coal and OB during leaching time periods to the leachates was detected by inductively coupled plasma-atomic emission spectroscopy and ion-chromatographic analyses. The major minerals found in coal and OB are quartz （SiO2）, pyrite （FeS2）, hematite, marcasite, and kaolinite. The association of different functional groups in minerals and their mode of association were studied by Fourier-transform infrared spectroscopy and X-ray diffraction analytical techniques. The present laboratory study will be useful in relating the characteristics of aqueous leaching from coal and mine OB with the natural weathering condition at the coal mine area.

THE APPLICATION OF REVERSE FLOCCULATION METHOD IN HIGH SULFUR COAL DESULFURIZATION

The reverse flocculation method for removing pyritic sulfur from high sulfor coals has been conceptually beveloped and investigated. The tentative tests on China high sulfur coals have shown that this advanced physical separation techaique can be very efficient in coal desulfurization, provided the process parameters are properly optimized. Under the circumsances of acquiring high coal recovery, the total sulfur rejection with four kinds of coal samples normally falls in tbe range 57% to 71 % by one-step reverse flocculation, and within the range 40% to 59% by one-step normal flocculation process.

Matter Composition and Two Stage Evolution of a Liangshan Super High-Sulfur Coal Seam in Kaili,Eastern Guizhou

Super-high sulfur coal resultes in serious coal-derived pollution but might have a particular genesis. Thus,a columnar section of an Early Permian Liangshan Formation coal seam. weight average sulfur content 5.80%,from Kaili,eastern Guizhou,was studied using the methods of coal petrology and geochemistry. The results show that the seam was apparently formed in seawater-effected peat bogs that developed in two distinct stages. During the first stage various layers were formed in a supratidal bog and have a composition characteristic of a bog with a gradually decreasing sea-water effect,decreasing water dynamics,and an increasingly reductive environment. Layers in the upper seam formed during a second stage in an intertidal bog. These layers are very high in total and inorganic sulfur,the ratios of or-ganic/inorganic sulfur and V/I drop,they are high in coal ash yield and have a high ash component index,considerable barkinite,oxidized and detrital macerals,have a porphyroclatic micro-structure and are rich in pyrite,all of which indi-cate the coal-forming environment had higher oxidation potential,strong and roiling water dynamics,and intermittent exposure to a sulfur rich environment.

REE Geochemistry of Moderate-and High-Sulfur Coals from North Shanxi, China

Contents of the rare-earth elements (REE) in two coal seams from North Shanxi Province, China, were determined using the instrumental neutron activation method. Based on the REE distribution patterns, and correlation analysis and cluster analysis, the main conclusions were drawn as follows. The REE contents are controlled mainly by the coal-forming environments, but might be affected by acidic solution leaching after peat sedimentation. The REE distribution patterns should be nearly the same in the sublayers of the same coal seam, and the occurrence of abnormal patterns might indicate the geological effect during post-sedimentation. The REE in coals are present mainly in the inorganic phase, and might be derived mainly from terrigenous detrital minerals. Some harmful elements, such as V, P, Mo, Cr, Cu, Mo, Th and Cd, might have cleaning potential during processing and dressing by washing because they are associated with REE.

Characterization and Desulfurization Possibilities of High Sulfur Gediz-Turkey Coal

Coal is one of the important energy sources, but it causes serious environmental problems such as air pollution, acid rain and greenhouse effects. Sulfur in coal is one of the responsibilities of these negative effects. Coal includes two types of sulfur： organic and inorganic. While inorganic sulfur can be completely removed with physical desulfurization methods, organic sulfur can be removed only by chemical desulfurization methods. But chemical methods are not only expensive but also difficult processes. Firstly in desulfurization, types of the sulfur content in coal should be well characterized. High sulfur Gediz-Turkey coal has been chosen to this study. This coal basin is located in the centre of the Turkey. In this study, characterization and desulfurization possibilities of high sulfur Gediz coal were investigated. For this purpose, several physical and chemical characterization methods such as proximate and ultimate coal analysis （ash, calorific value, volatile matter, moisture and sulfur analysis）, mineralogical and petrographic analysis, fourier transform infrared spectroscopy, scanning electron microscope were used. Results of these analysis are shown that Gediz coals include 3.15% pyritic sulfur and 2.89% organic sulfur. Removing pyritic sulfur from Gediz-Turkey coal with physical methods such as gravity and sink-float separation is not possible because pyrite particle has 1-2 micron liberation size in coal.

STUDY ON REGULATIONS OF SULFUR OCCURRENCE AND PYRITE MAGNETISM OF LATE PERMIAN COALS IN SOUTHWEST CHINA

The Permian coal in southwest China contains highest sulfur among the Chinese coal .Compositional variations of sumir in coal are mainly controlled by palaogeographital environmentsduring peat accumulation. High organic sulfur coal is formed in peat swamp developing in tidal flat of limited carbonate platform, and it is provided with especial petrologital and geochemical characteristics, and its organoschr-containing compounds are mainly thiophene series. The macroscopitaland microscopical shapes or types of pyrites in Late Permisn coal are diversined. Bituminous coal and anthracite are diamagnetic, but the pyrites are paramagnetic. The magnetic susceptibility oftbe pyrites is depended on the content of paramagnatic elements associnted with pyrites.

Mechanism of sulfur capture during coal briquette combustion

The mechanisms of sulfur capturing during coal briquette combustion was discussed. Various factors affecting sulfur removal efficiency have been studied. Characterization of the slag left after combustion has been carried out by using X ray diffraction (XRD), Messbauer spectroscopy (MS), scanning electron microscopy (SEM), energy dispersion X ray analysis (EDAX), and electron spectroscopy for chemical analysis (ESCA). No other sulfur containing species besides CaSO 4 was found. Small amount of CaFe 3(SiO 4) 2OH, some complexes of CaO SiO 2 Fe 2O 3 and vitreous iron oxides were identified on the surface of CaSO 4 grains. This might explain the mechanism of sulfur fixation during coal briquettes combustion.

电石渣和煤矸石对型煤固硫性能的影响及作用机制研究

研制高效低成本的耐高温固硫剂和添加剂有助于解决型煤高温燃烧环境下钙基固硫产物的分解问题。电石渣和煤矸石属于典型的工业固体废弃物,利用固废作为添加剂制备固硫型煤有助于降低固硫型煤成本和挖掘固废资源价值,发挥这两种固废中矿物组分协同作用可改善高温条件下型煤固硫效果。开展了电石渣和煤矸石分别作为固硫剂和添加剂制备环保型煤的研究,考察了固硫剂种类(碳酸钙、氧化钙、氢氧化钙和电石渣)、钙硫物质的量比(1.5~4.0)、燃烧温度(900℃~1300℃)、煤矸石用量(2%~7%)对型煤固硫效果的影响。通过型煤燃烧评价实验发现,仅用电石渣作为固硫剂,在钙硫物质的量比为3.0时制得的型煤在燃烧温度低于1000℃时固硫率能达到80%以上,燃烧温度提高到1300℃时型煤固硫率下降40%,结合分析表征数据发现主要原因是固硫产物硫酸钙的高温分解。添加的煤矸石在高温条件下被电石渣组分活化后起到辅助固硫作用,当添加的煤矸石的质量分数达到5%时型煤的固硫率能维持在60%以上,在此基础上增加煤矸石用量并不能明显提升型煤固硫率。通过固硫产物热稳定性研究并结合分析表征数据发现,高铝煤矸石灰渣活性组分发生高温反应生成硫铝酸钙、钙黄长石、硅酸三钙等耐高温稳定物相,在一定程度上抑制了CaSO_(4)的分解,从而提高了型煤的高温固硫率。

内蒙古某含碳高硫锌锡矿石选矿试验研究

内蒙古某含碳高硫锌锡矿石锌品位1.02%、锡品位0.86%,硫和碳含量分别为14.02%、1.68%。矿石矿物组成较复杂,主要有用矿物为闪锌矿、锡石和黄铁矿,脉石矿物主要为石英、绿泥石和绢云母等。为确定矿石合理的开发利用工艺,采用预先脱碳—浮重联合工艺流程开展选矿试验研究。结果表明,矿石经预先脱碳、1粗1扫1精锌硫混选、1粗1扫3精锌硫分离浮选流程处理,闭路试验可得到Zn品位为45.16%、Zn回收率为71.19%的锌精矿,S品位为46.92%、S回收率81.91%的硫精矿;浮选尾矿采用摇床重选,经粗选、精选、复选和中矿再选,可获得Sn品位45.52%、Sn回收率81.99%的锡精矿,以及Sn品位3.13%、Sn回收率11.09%的锡中矿。所设计试验流程较好地解决了矿石中有机碳对浮选的不利影响,综合回收了有价矿物,可为同类矿石的开发利用提供理论借鉴。

掺杂秸秆的高硫煤气化脱硫行为研究

通过热重分析法研究高硫肥煤与玉米秸秆混合物的热解动力学,并利用Coats-Redfern法计算混合物的活化能、指前因子。通过对其混合物的热解实验,发现掺杂玉米秸秆对高硫煤有明显的脱硫作用。

高压辊磨对某铜矿浮选指标影响的研究

为了研究高压辊磨破碎对国内某低品位铜矿石后续浮选指标的影响,采用单因素分析方法进行了高压辊磨破碎试验、浮选优化条件试验和浮选开路对比试验。结果表明,在磨矿细度-0.074 mm占65%,粗选氧化钙用量1000 g/t、MAC-12用量20 g/t、丁基黄药用量10 g/t,扫选MAC-12用量10 g/t、丁基黄药用量5 g/t条件下,经1粗1扫浮选流程,常规破碎产品浮选可获得铜、硫品位分别为4.31%和22.46%,铜、硫回收率分别为74.382%和79.053%的粗精矿;辊压产品浮选粗精矿铜、硫品位分别为4.76%和23.06%,铜、硫回收率分别为88.137%和87.082%。铜、硫品位分别提高0.45和0.60个百分点,铜、硫回收率分别提高13.755和8.029个百分点。由此可知,通过高压辊磨破碎作业,可提高该铜矿石浮选精矿的铜、硫品位和回收率。

燃用高硫煤锅炉空预器选型分析

为有效解决2×660MW燃用高硫煤超超临界机组空预器堵塞问题,研究了回转式空预器和管式空预器特性,分析了机组特点,提出了回转式空预器和管式空预器两级换热器串联方案,并探究了该方案对机组锅炉效率的影响。研究表明,相比于常规回转式空预器方案,采用回转式空预器和管式空预器两级换热器串联方案时,回转式空预器的出口排烟温度高于烟气酸露点,有效解决了机组空预器腐蚀堵塞问题,同时在保证设备安全下使锅炉效率提高1%。

高硫煤基多孔碳材料的可控制备及其用于锂硫电池

高性能、低成本的多孔碳材料是理想的锂硫电池硫宿主材料,但利用廉价的原料实现其规模化制备仍面临巨大挑战。以资源丰富的高硫煤为原料,采用氧化镁和氢氧化钾作为模板剂和活性剂,制备了煤基多孔碳材料,并研究了其作为锂硫电池硫宿主材料的构效关系。研究发现,煤基碳材料制备过程中,模板剂MgO作用下产生介孔(占比74%);活性剂KOH主要导致微孔(占72%)生成;MgO和KOH共同作用制备的碳材料PCMgO+KOH比表面积大(1616 m^(2)/g)、孔容高(1.02 m^(3)/g)、孔结构丰富(介孔54%、微孔46%)。电化学性能测试结果表明,S@PCMgO+KOH具有良好的倍率性能和优异的循环稳定性,在1 C充放电倍率循环500圈后容量仍能保留553.2 mAh/g,容量保持率达65.5%,每个循环的衰减率低至0.069%;在2 C下,循环500圈后容量为484.0 mAh/g,容量保持率为63%,每圈衰减率仅0.075%,具有良好的倍率性能和优异的循环稳定性。PCMgO+KOH优异的电化学性能主要来自其较小的欧姆电阻和电荷转移电阻、快速的多硫化物氧化还原反应动力学及对多硫化锂优异的束缚能力。本研究为价廉性高的锂硫电池硫宿主材料的制备提供了可选择的路线。

某高硫砷难处理金矿石选矿试验研究

某高硫砷金矿石金、银品位分别为2.90 g/t和59.00 g/t,As含量为6.06%、S含量为5.20%。矿石中金矿物粒度较细,均为显微金与细粒金,其与黄铜矿、磁黄铁矿等硫化矿连生于毒砂中,单体解离困难。为进一步实现高硫砷难处理金矿的高效利用,在矿石工艺矿物学研究的基础上,进行了浮选和氰化浸出试验研究,确定采用浮选—氰化浸出的联合工艺流程进行试验。结果表明:适宜药剂制度下,原矿在磨矿细度为-0.074 mm占75%时,进行1次粗选试验,粗精矿再磨至-0.038 mm占99%时,进行2粗2精浮选—1次硫砷分离流程试验。最终获得金品位为17.19g/t、金回收率为79.06%,银品位为269.00 g/t、银回收率为68.73%的金精矿。将浮选尾矿磨至-0.010 mm占86%时,采用氰化浸出工艺处理,金浸出率为22.22%,银浸出率为57.78%。选冶综合金回收率达到83.71%,银回收率达到了86.80%,实现了金、银的有效回收利用。

云南某贫细硫化铜矿石选矿工艺优化研究

云南某低品位细粒嵌布的铜矿石铜、硫品位分别为0.161%和9.704%,有价铜矿物嵌布粒度细,铜硫分离富集难度较大。为实现该硫化铜矿石资源的高效开发利用,在选厂原选矿流程及原矿工艺矿物学研究基础上,进行了系统的磨浮试验。结果表明:矿石采用磨矿—1粗2扫铜硫混合浮选—混浮粗精矿再磨—1粗3精2扫铜硫分离浮选闭路流程处理,可获得铜品位14.69%、铜回收率63.15%的铜精矿,硫品位29.16%、硫回收率75.10%的硫精矿,试验铜精矿品位较现场提高近3个百分点,铜回收率提高15个百分点以上,显著优于现场生产指标,达到了理想的综合回收铜硫效果。研究结果可作为工艺流程优化的依据。

广东某高硫铁矿石脱硫工艺试验

为了合理开发利用广东某高硫铁矿石,针对铁精矿硫含量超标难以销售的问题,在矿石性质研究的基础上,进行了阶段磨矿—阶段磁选、浮选—磁选—浮选、磁选—浮选—磁选3种工艺方案的对比探索试验。试验结果表明:磁选—浮选—磁选工艺对该高硫铁矿石的脱硫效果最好,在一段磨矿细度为-0.074 mm 65%,磁场强度为80 kA/m的条件下进行弱磁选,可得到磁性产品和非磁性产品;将磁性产品再磨至-0.045 mm 90%,固定新型活化剂X用量3000 g/t,捕收剂丁基黄药用量90 g/t,起泡剂2^(#)油用量60 g/t,通过1粗1扫反浮选脱除硫铁矿,扫选尾矿在磁场强度为80 kA/m的条件下进行弱磁选,最终获得了铁品位64.88%、含硫0.42%、全铁回收率50.68%的合格铁精矿。

介孔氧化硅分子筛负载金属氧化物高温煤气脱硫剂结构调控与脱硫过程放硫的研究进展

煤气化是煤炭清洁高效利用的核心技术,但气化粗煤气中所含硫化氢(H_(2)S)会腐蚀设备并污染环境,因此需要对煤气进行净化脱硫。介孔氧化硅分子筛具有大比表面积、大孔容和有序的介孔结构等特性,将其作为金属氧化物的载体可促进金属氧化物的分散,并为脱硫反应提供大量的反应活性位点,减少传质阻力。脱硫剂构效关系是煤气脱硫技术的关键科学难题之一,然而对于负载型高温煤气脱硫剂而言,上述关系受介孔氧化硅分子筛、脱硫活性组分种类、脱硫剂改性手段和脱硫条件等多因素叠加影响,因而要明晰其本质极具挑战。为此,首先探讨了不同介孔氧化硅分子筛的孔道结构特性,剖析了介孔氧化硅分子筛负载活性组分后的脱硫行为差异,发现拥有丰富孔结构及较厚孔壁的载体的脱硫剂在高温脱硫过程中表现更优。同时,分析了近年来针对锌基、锰基和铁基等金属氧化物负载型脱硫剂的结构调控策略及其对脱硫性能的影响规律,认为通过金属掺杂复合改性可提高活性组分脱硫活性;并对脱硫过程中的放硫机制、放硫规律及抑制手段进行了探讨,认为在脱硫剂中引入催化羰基硫(COS)氢解助剂可有效抑制放硫行为。本综述内容可为高性能高温脱硫剂结构设计与功能化构筑提供理论依据。

高硫煤矸石协同飞灰制备多孔玻璃物相转变机理

采用高硫煤矸石协同垃圾焚烧飞灰制备多孔玻璃,同时利用玻璃体固定垃圾焚烧飞灰中的Pb、Cd、Zn、Cr、Cu、Mn等重金属,实现多源固废、危废协同无害化处置和资源化利用。针对多孔玻璃轻质和高强度难以兼顾的问题,一方面,通过还原气氛抑制残碳在中低温氧化反应,使高硫煤矸石中残碳在1000℃以上与Fe_(2)O_(3)反应生成CO_(2)气体,促进熔体发泡,多孔玻璃容重由900 kg/m^(3)降低至300 kg/m^(3);另一方面,通过在配合料中添加高岭土,使多孔玻璃孔壁的主要晶相由长石转变为莫来石,莫来石独特的交联结构使多孔玻璃具有较高强度。当容重在500 kg/m^(3)时,多孔玻璃强度提升了80%。多孔玻璃重金属浸出毒性分析结果表明,各种重金属的浸出浓度远远低于规定的标准限值(5.0 mg/L),多孔玻璃中重金属Pb的浸出浓度降低至1.1×10^(-2)mg/L,其它重金属的浸出浓度也普遍呈现出显著的下降趋势,说明多孔玻璃对多元重金属具有良好的固定效果。