Combustion characteristics of Daqing oil shale and oil shale semi-cokes

Thermo-gravimetric-analysis(TGA) was used to analyze the combustion characteristics of an oil shale and semi-cokes prepared from it.The effect of prior pyrolysis and TGA heating rate on the combustion process was studied.Prior pyrolysis affects the initial temperature of mass loss and the ignition temperature.The ignition temperature increases as the volatile content of the sample decreases.TG/DTG curves obtained at different heating rates show that heating rate has little effect on ignition temperature.But the peak of combustion shifts to higher temperatures as the heating rate is increased.The Coats-Redfern integration method was employed to find the combustion-reaction kinetic parameters for the burning of oil shale and oil shale semi-coke.

Synthesis of biochar/clay mineral nanocomposites using oil shale semi-coke waste for removal of organic pollutants

Due to the poor surface/interfacial interaction and the large gaps in the size and microstructure between biomass and clay mineral,it was difficult to adjust the structure and performance of biochar/clay mineral composites at the molecular level.Herein,oil shale semi-coke composed of multi-minerals and organic matters was used as a promising precursor to prepare biochar/clay mineral nanocomposites via phosphoric acid-assisted hydrothermal treatment followed by KOH activation for removal of organic pollutants from aqueous solution.The results revealed that the nanocomposites presented well-defined sheet-like morphology,and the carbon species uniformly anchored on the surface of clay minerals.With the changes in the pore structure,surface charge and functional groups after two-step modification,the nanocomposites exhibited much better adsorption property toward organic pollutants than the raw oil shale semi-coke,and the maximum adsorption capacities of methylene blue,methyl violet,tetracycline,and malachite green were 165.30 mg g^(−1),159.02 mg g^(−1),145.89 mg g^(−1),and 2137.36 mg g^(−1),respectively.The adsorption mechanisms involved electrostatic attraction,π-πstacking and hydrogen bonds.After five consecutive adsorption-desorption,there was no obvious decrease in the adsorption capacity of malachite green,exhibiting good cyclic regeneration performance.It is expected to provide a feasible strategy for the preparation of biochar/clay mineral nanocomposites with the excellent adsorption performances for removal of organic pollutants based on full-component resource utilization of oil shale semi-coke.

棉秆和油页岩共热解生物炭的氨氮吸附性能研究

使用棉秆(CS)和油页岩(OS)为原料,采用共热解的方式制备了共热解生物炭,探究了对氨氮的吸附性能。考察了不同热解时间、CS和OS比例、热解温度、CS的粒径对共热解生物炭的氨氮吸附量的影响规律,确定了最佳制备条件,并研究了吸附动力学和吸附等温线模型。研究表明,棉秆和油页岩共热解后生物炭的结构特性和表面形貌有较大改善,对氨氮的吸附能力有明显的提高。最佳的制备条件是热解温度为500℃、m(棉秆)∶m(油页岩)=3∶1、热解时间为30 min和CS的粒径为0.20~0.30 mm。在投加量为10.0 g/L、pH 9.0时,最佳条件所制备炭的吸附量为4.89 mg/g,是棉秆生物炭的2.2倍。吸附过程以准二级动力学和Langmuir等温吸附模型描述。吸附机制主要包括为离子交换、静电吸附和配位作用。

油页岩改性生物炭对磷酸盐的吸附特性

为解决磷回收困难和固体废弃物难处理的问题,文章以棉秆和油页岩为原料,采用共热解法制备了油页岩改性生物炭(OS-CS),利用SEM-EDS,BET,FT-IR等测试手段对其进行了理化特性分析,考察了热解温度、吸附剂用量、溶液pH值等因素对OS-CS的磷酸盐吸附性能的影响,并研究了OS-CS的吸附动力学和吸附等温线模型。研究结果表明:进过改性后,OS-CS的结构性能和表面形貌有较大改善,对磷酸盐的吸附能力有明显的提高;在投加量为4.0 g/L、溶液pH值为5.0时,OS-CS的磷酸盐最大吸附量为7.01 mg/g,是棉秆炭的2.47倍,油页岩半焦的3.52倍。OS-CS吸附磷酸盐过程主要以拟二级动力学和Langmuir等温吸附模型进行描述,吸附机理主要包括表面沉淀、配体交换和静电吸引。油页岩改性生物炭复合材料为磷酸盐的去除和固体废弃物的资源化利用提供了新思路。

油页岩半焦基矿物生物炭对土壤理化性状影响研究

将油页岩半焦进行碳化后生产出的矿物生物炭与秸秆生物炭进行理化性能对比分析,并在甘肃省马军坪、张掖、白银3地的试验田进行了相关应用试验。研究结果表明,矿物生物炭比表面积较大、孔径小、具有一定疏水性,与秸秆生物炭类似,含有较高的养分,作为土壤改良剂可在一定程度上提升土壤肥力,有利于改良土壤结构、透气性、透水性及保水能力,作为农业或其他工业产品原料安全可行;在碱性土壤中施用后,会对土壤酸碱度下降有一定的促进作用;增施矿物生物炭能有效提高土壤有机质、全氮、水溶性钙含量,可为矿物生物炭在甘肃省不同属性土壤改良、农田种植中规模化应用、构建高标准高质量农田提供理论基础。

Effect of oil shale semi-coke on deposit mineralogy and morphology in the flue path of a CFB burning Zhundong lignite

The effect of oil shale semi-coke(SC)on the mineralogy and morphology of the ash deposited on probes situated in the flue path of a circulating fluidized bed(CFB)which burns Zhundong lignite(ZD)was investigated.10 wt%or 20 wt%SC was added to ZD,which were then combusted in the CFB furnace at 950℃.Two probes with vertical and horizontal orientations were installed in the flue duct to simulate ash deposition.Both windward and leeward ash deposits on probes(P_(1)W,P_(1)L,P_(2)W and P_(2)L)were analyzed by using a scanning electron microscopy with energy dispersive X-ray(SEM-EDX),X-ray diffraction(XRD),an inductively coupled plasma optical emission spectrometry ICP-OES,and a particle size analyzer.When ZD was burned alone,the P1W deposit was comprised of agglomerates(<30µm)enriched in CaSO_(4)and Na_(2)SiO_(3),incurring significant sintering.The P1L and P2W deposits,however,were of both discrete and agglomerated particles in similar mineral phases but with coarser sizes.The P_(2)L deposit was mainly fine ash particles where Na_(2)SiO_(3)and Na_(2)SO_(4)were absent.As SC was added,the agglomerates in both P1W and P1L decreased.Moreover,SiO_(2)and Ca/Na aluminosilicates dominated the mineral phases whereas Na_(2)SiO_(3)and Na_(2)SO_(4)disappeared,showing a decrease in deposit stickiness.Likewise,the P2W deposit was found less spread on the probe,decreasing its deposition propensity.Na-bearing minerals turned into(Na,K)(Si_(3)Al)O_(8)and(Ca,Na)(Si,Al)4O8 in the P_(2)W deposit.Moreover,Na in the deposits decreased from 32 mg/g to less than 15 mg/g as SC presented.The addition of SC would therefore help alleviate the propensity of ash deposition in the flue path in the CFB combustion of ZD.

油页岩半焦生物炭对玉米产量及土壤理化性状的影响

油页岩半焦含有丰富的有机质和无机营养物质,是复混肥理想的添加物料。为了提升油页岩半焦生物炭在农业生产中的利用价值,以玉米为指示作物,玉米品种先玉335为指示品种,设施油页岩半焦生物炭20、40、60、80 t/hm^(2),不施肥和仅施氮、磷肥(优化施肥)6个处理,采用随机区组设计,研究了不同油页岩半焦生物炭施用量对玉米产量及土壤养分状况的影响。结果表明,施用油页岩半焦生物炭后土壤性状发生显著变化,与播前相比,土壤容重下降了2.21%~8.82%,土壤孔隙度增加了-11.05%~4.08%,毛管孔隙度增加了-6.70%~3.74%,土壤pH下降了4.73%~7.84%。土壤储水量较对照不施肥处理增加了18.85%~30.57%。与优化施肥相比,土壤全氮增加了6.25%~20.83%,土壤全磷增加了0~25.51%,土壤全钾增加了0.92%~2.63%,土壤有机质增加了24.29%~88.26%,土壤碱解氮增加了-7.40%~14.21%,土壤速效磷增加了-30.27~80.37%,土壤速效钾增加了-12.87%~115.07%。在油页岩半焦生物炭投入量为60 t/hm^(2)时,玉米产量最高,达17681.4 kg/hm^(2),较对照不施肥处理增产20.10%。综合分析,施不同用量油页岩半焦生物炭均能明显改善土壤物理化学性状,显著提升土壤肥力,促进作物生长,进而提高作物产量。

油页岩半焦基矿物/生物炭复合材料制备及其吸附性能研究

基于油页岩半焦中富含的矿物质和有机质,以KOH为活化剂,联用机械力化学和热解炭化窑街油页岩半焦制备油页岩半焦基矿物/生物炭复合材料,考察了矿物/生物炭复合材料对水溶液中Pb^(2+)和Cd^(2+)的吸附效果.结果表明,制得的复合材料对Pb^(2+)和Cd^(2+)具有优异的吸附性能,最大吸附量分别为177.83和67.48mg·g^(-1),分别是原油页岩半焦的6.1倍和4.3倍.吸附动力学和热力学拟合数据显示,复合材料对Pb^(2+)和Cd^(2+)的吸附属于化学吸附主导的单层吸附,主要吸附机理涉及官能团吸附、Pb^(2+)-π和Cd^(2+)-π相互作用、静电吸附和矿物沉淀.该研究为从环境矿物材料角度探究油页岩半焦全组分综合利用提供了可行途径.

油页岩半焦制备生物炭的工程化问题探讨

【目的】通过国内首个油页岩半焦制备生物炭生产线的工程化设计,对该新技术工程化过程中的问题和难点进行探讨,为我国其他地区油页岩半焦综合利用提供参考。【方法】阐述了油页岩半焦的综合利用现状,针对油页岩半焦的性质,结合试验报告制定了油页岩半焦制备生物炭生产线的工艺路线,通过设计计算确定了主要工艺设备选型,完成工程化设计和生产调试。【结果】经过一段时间的生产调试,试验线产能达到设计预期,对新技术首次工程化过程暴露出的问题和难点进行了总结归纳。【结论】油页岩半焦制备生物炭的试验研究和工程化探索,有一定的科学价值,相关研究对解决我国油页岩半焦综合利用难题提供了参考。后续工程化设计时应重点关注炭化炉无氧条件的控制及热解气的处理。