Sulfur phase and sulfur removal in high sulfur-containing bauxite

The sulfur phase in high sulfur-containing bauxite was studied by an X-ray diffraction analysis and a chemistry quantitative analysis.The methods for the removal of different shaped sulfur were also discussed.The results show that sulfur phases in high sulfur-containing bauxites exist in the main form of sulfide sulfur （pyrite） or sulfate sulfur,and the main sulfur forms of bauxites from different regions are not the same.Through a combination of an X-ray diffraction analysis and a chemistry quantitative analysis,the sulfur phases of high sulfur-containing bauxite could be accurately investigated.Deciding the main sulfur form of high sulfur-containing bauxite could provide theoretical instruction for choosing methods for the removal of sulfur from bauxite,and an oxidizing-roasting process is an effective way to remove sulfide sulfur from high sulfur-containing bauxite,the content of S^2-in crude ore in the digestion liquor is above 1.7 g/L,but in the roasted ore digestion liquor,it is below 0.18 g/L.Using the sodium carbonate solution washing technology to wash bauxite can effectively remove sulfate sulfur,the content of the total sulfur in ore is lowered to below 0.2% and can meet the production requirements for the sulfur content.

Toward high-sulfur-content,high-performance lithium-sulfur batteries:Review of materials and technologies

Lithium sulfur batteries(LSBs)are recognized as promising devices for developing next-generation energy storage systems.In addition,they are attractive rechargeable battery systems for replacing lithium-ion batteries(LIBs)for commercial use owing to their higher theoretical energy density and lower cost compared to those of LIBs.However,LSBs are still beset with some persistent issues that prevent them from being used industrially,such as the unavoidable dissolution of lithium polysulfide intermediates during electrochemical reactions and large volume expansion(up to 80%)upon the formation of Li_(2)S,resulting in serious battery life and safety limitations.In the process of solving these problems,it is necessary to maintain a high sulfur content in the cathode materials to ensure that the LSBs have high energy densities and excellent cycle performance.In this review,the novel preparation methods and cathode materials used for preparing LSBs in recent years are reviewed considering the sulfur content and cycle performance.In addition,the problems and difficulties in practically applying cathode materials are described,and the development trend is discussed.

Regulation of carbon distribution to construct high-sulfur-content cathode in lithium-sulfur batteries

Lithium-sulfur(Li-S)battery is regarded as one of the most promising next-generation energy storage systems due to the ultra-high theoretical energy density of 2600 Wh kg^(-1).To address the insulation nature of sulfur,nanocarbon composition is essential to afford acceptable cycling capacity but inevitably sacrifices the actual energy density under working conditions.Therefore,rational structural design of the carbon/sulfur composite cathode is of great significance to realize satisfactory electrochemical performances with limited carbon content.Herein,the cathode carbon distribution is rationally regulated to construct high-sulfur-content and high-performance Li-S batteries.Concretely,a double-layer carbon(DLC)cathode is prepared by fabricating a surface carbon layer on the carbon/sulfur composite.The surface carbon layer not only provides more electrochemically active surfaces,but also blocks the polysulfide shuttle.Consequently,the DLC configuration with an increased sulfur content by nearly 10 wt%renders an initial areal capacity of 3.40 mAh cm^(-2) and capacity retention of 83.8%during 50 cycles,which is about two times than that of the low-sulfur-content cathode.The strategy of carbon distribution regulation affords an effective pathway to construct advanced high-sulfur-content cathodes for practical high-energy-density Li-S batteries.

A crosslinking hydrogel binder for high-sulfur content S@pPAN cathode in rechargeable lithium batteries

High-energy density lithium-sulfur(Li-S) batteries have received intensive attention as promising energy storage system.Among diverse sulfur-based cathodes,sulfurized pyrolyzed poly(acrylonitrile)(S@pPAN)cathode delivered superior electrochemical performance.However,the sulfur content of S@pPAN is relatively low(<50 wt%),which significantly limits the energy density.Herein,a hydrogel SA-Cu binder was proposed with a crosslinking network constructed by Cu^(2+) ions.The introduction of Cu^(2+) ions enabled excellent electrochemical behaviors of S@pPAN cathode even with high sulfur content of 52.6 wt% via chemical interaction with sulfur and polysulfide.Moreover,a favorable cathode interphase was formed containing electrochemically active and conductive CuSx.S@pPAN/SA-Cu exhibited a high sulfur utilization of 85.3%,long cycling stability over 1000 cycles and remarkable capacity of 1200 mAh g_(s)^(-1) even at10 C.Furthermore,ascribed to the improved electrode structure,high-loading electrode(sulfur loading:4 mg cm^(-2)) displayed stable cycling with areal capacity of 5.26 mAh cm^(-2)(1315 mAh g_(s)^(-1)) after 40 cycles.This study provides new directions to prepare high-sulfur content and high-loading S@pPAN cathode for higher energy density.

Hierarchically porous Fe/N/S/C nanospheres with high-content of Fe-Nx for enhanced ORR and Zn-air battery performance

Heteroatom-doped carbon-based transition-metal single-atom catalysts(SACs) are promising electrocatalysts for oxygen reduction reaction(ORR). Herein, with the aid of hierarchically porous silica as hard template, a facile and general melting perfusion and mesopore-confined pyrolysis method was reported to prepare single-atomic Fe/N–S-doped carbon catalyst(FeNx/NC-S) with hierarchically porous structure and well-defined morphology. The FeNx/NC-S exhibited excellent ORR activity with a half-wave potential(E_(1/2)) of 0.92 V, and a lower overpotential of 320 mV at a current density of 10 mA cm^(-2)for OER under alkaline condition. The remarkable electrocatalysis performance can be attributed to the hierarchically porous carbon nanospheres with S doping and high content of Fe-Nx sites(up to 3.7 wt% of Fe), resulting from the nano-confinement effect of the hierarchically porous silica spheres(NKM-5) during the pyrolysis process. The rechargeable Zn-air battery with FeNx/NC-S as a cathode catalyst demonstrated a superior power density of 194.5 mW cm-2charge–discharge stability. This work highlights a new avenue to design advanced SACs for efficient sustainable energy storage and conversion.

Outstanding long-cycling lithium−sulfur batteries by core-shell structure of S@Pt composite with ultrahigh sulfur content

Here we proposed a novel approach to greatly enhance the electrochemical performance of Li-S batteries by designing a composite electrode material composed of a core-shell structure of S@Pt composite(sulfur content,85%)grown on the S surface.The platinum(Pt)nanosheets provide physical barrier and strong chemical binding to anchor LiPSs and improve the electronic conductivity of S.Significantly,by introducing carbon nanofibers(CNFs)as the interlayer,we achieved outstanding Li-S battery with a high initial discharge capacity of 1040 mAh g^(-1)at 1.0C and a reversible capacity of 742 mAh g^(-1)after 350 cycles,demonstrating its excellent long-term cycling stability with a low capacity decay rate of 0.08%per cycle.According to the density functional theory(DFT)calculations,we proposed that the superior performance is attributed to the cooperative effects of the strong interfacial interaction between Pt(111)surface and the S8 molecule,and very low reaction energy of decomposition,−6.4​eV.

Preparation and Properties of a New Mediumdensity and High-strength Ceramic Proppant

Based on the needs of the market,a new 52 MPa medium-density and high-strength ceramic proppant was prepared by adopting third grade bauxite and clay as raw materials and using the solid phase sintering method,and the effect of the firing temperature on the microstructure,phase composition and mechanical properties of the ceramic proppant was studied. The broken resistance mechanism of this ceramic proppant was also discussed. The results show that the main phases of the prepared ceramic proppant are mullite and corundum; the broken rates are 3. 92% and 7. 21% under 52 MPa and69 MPa,respectively.

Electrochemical behaviors of anode materials and their performance for bauxite desulfurization

Pyrite inside bauxite could be oxidized into soluble S-containing ions by electrolysis, and thus achieving bauxite desulfurization by using filtration. However, S-containing ions in electrolyte had some corrosion effects on electrode, especially for anode. In this work, six kinds of traditional materials were selected as anode, and their corrosion behaviors were examined by using electrochemistry characterization. Tafel and CV curves from simulating electrolyte suggested that their corrosion potentials were in the following order: Ni﹥C﹥SS﹥Fe﹥Cu﹥Pb–Ag. As expected, the desulfurization ratio and cell voltage from bauxite electrolysis were in the following order respectively: Cu﹥Ni﹥Fe﹥SS﹥C﹥Pb–Ag and Ni﹥Fe﹥SS﹥Cu﹥C﹥Pb–Ag. Finally, Ni was proposed a kind of excellent electrode material for bauxite desulfurization from electrolysis.

Preparation of High Ga Content Cu(In,Ga)Se₂Thin Films by Sequential Evaporation Process Added In₂S₃

High Ga content Cu(In,Ga)Se2 thin films incorporated sulfur were prepared by sequential evaporation from CuGaSe2 and CuInSe2 ternary compounds and subsequently Ga2Se3, In2Se3 and In2S3 binary compounds. The In2S3/(Ga2Se3+ In2Se3) ratio was varied from 0 to 0.13, and the properties of the thin films were investigated. XRD studies demonstrated that the prepared thin films had a chalcopyrite Cu(In,Ga)Se2 structure. The S/(Se+S) mole ratio in the thin films was within the range from 0 to 0.04. The band gaps of Cu(In,Ga)Se2 thin films increased from 1.30 eV to 1.59 eV with increasing the ?In2S3 /(Ga2Se3+ In2Se3) ratio.

The construction of technical standard system for ultra deep and high sour gas fields in Northeast Sichuan

To deal with the exploitation difficulties of gas fields in Northeast Sichuan with deep marine strata, after researching the relative standards domestic and abroad extensively, summarizing and promoting the successful experiences and failure lessons of project construction technology application scientifically, Sinopec has established an integrated technical standard system for the exploration and development of ultra deep and high sour gas fields. The system consists of 51 enterprise standards and covers 7 professions including geophysical prospecting, drilling, drilling log, well logging, gas formation test and production, sour gas gathering and transferring system, and HSE (health,safety,environment). It guides and guarantees the safe, high-quality and high-efficiency project construction effectively by means of enhancing the engineering design criterion, recommending the data processing and interpretation methods, identifying the requirements of operation and field inspection and standardizing the application of technical equipments.

Effects of electrolyte recycling on desulfurization from bauxite water slurry electrolysis

To lower the cost of bauxite electrolysis desulfurization using NaOH solution as the supporting electrolyte, effects of electrolyte recycling on bauxite electrolysis desulfurization were investigated. The results indicate that electrode corrosion, cell voltage, the desulfurization rate and the pH value of the electrolyte have no obvious changes with the increase of cycle times. Additionally, there were some transitive valence S-containing ions in electrolyte after the electrolysis, such as SO3^2-,S2O3^2- . However, most of the sulfur in bauxite was eventually oxidized into SO4^2- into the electrolyte, and these S-containing ions did not affect the recycling utilization for electrolyte.

Sulfur polymerization strategy based on the intrinsic properties of polymers for advanced binder-free and high-sulfur-content Li–S batteries

Lithium-sulfur(Li-S)batteries are the promising next-generation secondary energy storage systems,because of their advantages of high energy density and environmental friendliness.Among numerous cathode materials,organosulfur polymer materials have received extensive attentions because of their controllable structure and uniform sulfur distribution.However,the sulfur content of most organosulfur polymer cathodes is limited(S content<60%)due to the addition of large amounts of conductive agents and binders,which adversely affects the energy density of Li-S batteries.Herein,a hyperbranched sulfur-rich polymer based on modified polyethyleneimine(Ath-PEI)named carbon nanotubeentangled poly(allyl-terminated hyperbranched ethyleneimine-random-sulfur)(CNT/Ath-PEI@S)was prepared by sulfur polymerization and used as a Li-S battery cathode.The high intrinsic viscosity of Ath-PEI provided considerable adhesion and avoided the addition of PVDF binder,thereby increasing the sulfur content of cathodes to 75%.Moreover,considering the uniform distribution of elemental sulfur by the polymer,the utilization of sulfur was successfully improved,thus improving the rate capability and discharge capacity of the battery.The binder-free,sulfur-rich polymer cathode exhibited ultra-high initial discharge capacity(1520.7 mAh g^(−1) at 0.1 C),and high rate capability(804 mAh g^(−1) at 2.0 C).And cell-level calculations show that the electrode exhibits an initial capacity of 942.3 mAh g^(−1) electrode,which is much higher than those of conventional sulfur-polymer electrodes reported in the literature.

Graphene/RuO2 nanocrystal composites as sulfur host for lithium-sulfur batteries

An optimized graphene/RuO2/S composite is prepared by hydrothermal growth of RuO2 particles on graphene oxide sheets as the positive electrode for rechargeable lithium-sulfur batteries. The electrode with 6.1 wt% RuO2 nanocrystals and a high sulfur content of 79.0 wt% delivers an optimal electrochemical performance with high residual capacities of 508 mAh g-1 after 200 cycles and 389 m Ah g-1 after800 cycles at 1 C with a low capacity decay of 0.054%. The RuO2 nanocrystals promote the redox reaction kinetics and facilitate the transformation of sulfur chemistry, leading to large improvements in reversibility and rate capability of the composite electrode. The density functional theory calculations signify the formation of Li–O and Ru–S bonds through chemical interactions between RuO2 and Li polysulfides while the adsorption energies between graphene and polysulfide species are much higher in the presence of RuO2 than that of the neat graphene acting alone. These discoveries support the efficient entrapment of polysulfides by the composite electrode to the benefit of enhanced cyclic stability of the battery.

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。

高硫高铁铝土矿悬浮焙烧同步脱硫除铁试验研究

中国铝土矿资源质量每况愈下,高品位铝土矿资源日渐枯竭,资源问题已成为中国铝工业发展的重要难题,而尚未得到工业规模开发利用的高硫高铁铝土矿属于难利用资源,具有巨大的潜在工业价值,对高硫高铁铝土矿开展脱硫除铁基础研究具有重要的理论与实际意义。针对广西高硫高铁铝土矿综合开发利用难题,采用“悬浮氧化焙烧—还原焙烧—磁选”工艺进行了系统的铝土矿脱硫除铁试验,并利用X射线衍射分析(XRD)、化学物相分析和X射线光电子能谱分析(XPS)等方法,研究了焙烧过程中矿物物相的转化。结果表明,矿物中主要含硫和含铁矿物为黄铁矿,采用“悬浮氧化焙烧—还原焙烧—磁选”工艺可同步实现硫元素的高效脱除和铁元素的富集分离。当悬浮氧化焙烧条件为焙烧温度700℃、焙烧时间40min、O2浓度40%、总气量600mL/min,可获得St为0.396%、脱硫率为98.10%的氧化焙烧产品;然后进行悬浮还原焙烧条件为焙烧温度550℃、焙烧时间20min、CO浓度20%、总气量600mL/min、磁场强度150kA/m时,可获得TFe为54.79%的铁精矿和St为0.248%、TFe为4.37和Al2O3含量为75.27%的富铝矿。此技术大幅度提高了高硫高铁铝土矿的Al2O3含量,有利于后续铝土矿溶出,达到了脱硫除铁提铝的技术目标。该工艺为该类难选高硫高铁铝土矿资源的高效利用提供了一种新的技术途径。

高硫高铁铝土矿脱硫除铁研究进展

铝是人们现代生活中重要的金属材料,铝土矿是生产铝的主要原料,随着国内铝工业的持续发展,铝土矿资源的需求量在逐年增加。但国内铝土矿资源品质较低,供给不足,铝土矿对外依存度较高,严重制约了我国铝资源的供应安全,对我国铝工业的可持续性发展产生较大威胁。为了应对我国高品质铝土矿资源的匮乏问题,开发高硫高铁等复杂难选铝土矿资源,对确保我国铝土矿资源的战略安全至关重要。我国高硫高铁等复杂铝土矿资源量大,约15亿t以上,并伴生其他战略金属资源,目前亟待高效开发,利用先进工艺可实现此类典型贫杂铝土矿的工业化应用。铝土矿中过多的硫杂质和铁杂质会对拜耳法提铝工艺产生不可忽视的影响,如腐蚀设备和管道、增加碱耗和赤泥量、影响氧化铝的质量等。因此,从我国高硫高铁铝土矿的资源现状及特点入手,综述了高硫高铁铝土矿脱硫除铁工艺现阶段的研究进展,总结了浮选脱硫、预焙烧脱硫、生物法脱硫、湿法脱硫等主要脱硫技术及物理法除铁、化学法除铁、生物法除铁等主要除铁技术,探讨了各种工艺的工业化应用水平并列举了几个典型高硫高铁铝土矿的工业化应用实例,将为我国开发利用复杂铝土矿资源提供理论支撑,使难利用铝资源得到有效利用,降低我国对国外铝资源的依赖水平,提高铝土矿资源的保障力。

我国高硫铝土矿脱硫及伴生钴资源综合利用研究进展

铝土矿是战略性紧缺矿产资源,我国高硫铝土矿占比高,其高效开发利用有利于减轻我国铝工业原料的供应压力。针对高硫铝土矿的资源特点,对高硫铝土矿脱硫研究现状进行了总结,综述了预先脱硫和氧化铝生产过程中脱硫的优缺点;并基于浮选脱硫方式,探究了铝土矿中伴生钴资源的综合利用思路。高硫铝土矿脱硫的目标是将硫含量降低到符合氧化铝生产或其他工业应用的要求。焙烧脱硫、浮选脱硫、沉淀法脱硫等是高硫铝土矿脱硫的主要方式。其中,浮选脱硫是脱硫方式中较为成熟的工艺,具有效率高、成本低的优点;浮选脱硫也是伴生钴资源综合利用的关键一步,工业推广前景可观。对高硫铝土矿伴生钴资源进行综合回收,能够提高资源综合利用率,提高国内钴资源的自给率,降低对国外资源的依赖程度。对于高硫铝土矿伴生硫钴资源的回收利用,选冶联合是综合回收硫钴重点攻关方向。

高硫铝土矿脱硫方法研究进展

高品质铝土矿在我国属于紧缺性矿产资源,我国有大量高硫铝土矿资源,但高硫铝土矿冶炼会降低Al_(2)O_(3)溶出率、降低赤泥沉降性能、污染氢氧化铝产品、腐蚀生产设备等,因此高硫铝土矿脱硫技术成为实现其高效综合利用、缓解铝土矿资源短缺的关键。目前高硫铝土矿脱硫技术主要分为预处理脱硫和溶出过程脱硫。预处理脱硫包括浮选法、焙烧法、电化学脱硫、微生物脱硫等。浮选法适合于含硫较低的铝矿石资源,对于低品位、高硫含量的铝矿石则存在浮选药剂用量大、废水排放量大等问题;焙烧法脱硫效率高,但传统堆积焙烧存在焙烧时间长、能耗高等问题;电化学脱硫具有低温、常压、高脱硫率、无二次污染等优点,但存在能耗高、生产规模受限制等问题;微生物脱硫生产成本和能耗较低、环保性较高,但特定菌种对生长环境要求苛刻,培育菌种周期长。溶出过程脱硫包括氧化蒸发法脱硫、沉淀法脱硫和石灰法脱硫等。氧化蒸发法能够清除铝酸钠溶液中大部分S^(2-),但对其他形态硫氧化效果不明显;沉淀法脱硫操作较为简单,但存在脱硫剂成本高,难以应用于实际生产的问题;石灰法只能脱除溶液中SO_(4)^(2-),对其他类型硫离子并未产生显著去除作用。未来,建议从以下几个方向着手解决高硫铝土矿脱硫问题:开发低温高效、低能耗焙烧工艺;改善或者研发新型脱硫捕收剂;筛选高效、易培育菌种,研究混合菌脱硫效果。

某高硫低品位铜矿浮选试验研究

安徽某高硫低品位铜矿硫品位41.30%、铜品位0.53%,易氧化,选矿指标不稳定。为了改善铜硫分离效果,研究了磨矿细度、药剂种类和药剂用量等对浮选指标的影响。结果表明,磨矿细度-0.074 mm粒级占83.88%,采用一粗二精二扫闭路浮选流程,以CaO+Na_(2)S为组合抑制剂、Z-200为捕收剂、2#油为起泡剂,获得了铜品位15.27%、回收率80.96%的技术指标。试验结果可为高硫低品位铜矿浮选回收铜提供参考。

土壤中全硫测定——硫分析仪选择及方法优化

全硫含量是土壤调查项目中的必测项目。在燃烧法直接测定固体样品的硫分析仪中,高频红外碳硫仪检测限低,检测速度快,燃烧温度高,测定土壤标准物质的准确度高,是快速测定土壤中全硫的最佳仪器。应用高频红外碳硫仪测定样品过程中,坩埚空白、通氧流量、样品称样量、助熔剂添加量、定量方法等均会对测定结果准确度产生影响。通过对上述影响条件进行优化,研究确定了测定土壤中全硫含量的最佳条件:在严格控制坩埚空白的前提下,通氧流量设定为2~3 L/min,依次称取0.1 g样品(精度:0.0001 g)、0.5 g纯铁(精度:0.001 g)和1.0 g钨粒助熔剂(精度:0.001 g)混合后上机分析,对不同浓度样品进行分段校正。值得注意的是,本研究证实了利用化学物质标准品建立工作曲线的可行性,为后期仪器优化和改进提供了宝贵思路。国家土壤标准物质测定结果的相对标准偏差(RSD)小于2%(n=6),测定值与标准值相对误差(RE)的绝对值小于1%(n=6),方法检出限为4.50μg/g,说明方法的准确度和精密度高,适用于低含硫量土壤样品的批量检测。