Fate of sulfur compounds in coal during oxidative dissolution in perchloric acid

The sulfur forms in coal (sulfate, pyrite and organic) have been clearly delineated by oxidation with perchloric acid. Perchloric acid was chosen as an oxidizing agent because its oxidizing power can be varied by changing its concentration and subsequent boiling point. Using this property, the stepwise oxidation of an Illinois No. 6 coal, a coal-derived pyrite, and a New Zealand coal (in which almost all of the sufur was organic) was effected. At low temperatures, sulfate was removed without oxidizing the pyrite or organic material. At a moderate temperature (155°C), the pyrite was oxidized to sulfate and a sulfur-containing gas. Little or no organic sulfur was oxidized at 155°C. Boiling concentrated perchloric acid (203°C) converted all the sulfur to sulfate and a sulfur-containing gas. The sulfur-containing gas was produced primarily from the pyrite; organic sulfur produced very small amounts of a sulfur-containing gas as an oxidation product.     

Sulfur variability and element geochemistry of the No. 11 coal seam from the Antaibao mining district,China

The roof, bottom and 24 coal ply samples were collected by finely partitioning No. 11 coal seam from Antaibao mining district, Shanxi, China in terms of lithotypes. Proximate and sulfur analyses, ICP-AES, ICP-MS, AFS, XRD, SEM–EDX techniques were used on these samples, in order to investigate the vertical variability and origin of sulfur and also the geochemistry of major and trace elements in the seam. The weighted mean content of total sulfur of the 24 coal plies is 2.4 wt%, belonging to the medium-sulfur coal, but there are great differences in the contents of total sulfur and forms of sulfur between the 24 plies: total sulfur content >3.0 wt% for 5 plies, organic sulfur content >1.0 wt% for 13 plies and pyritic sulfur content >2.0 wt% for 4 plies. It is found that the differences were mainly caused by the degree of marine influences and the contents of clay minerals as well as the organic matter. The ply 21 has an abnormal high content of inorganic sulfur (pyritic sulfur 9.45 wt% and sulfate sulfur 5.97 wt%). This was caused by the presence of bauxite minerals-bearing kaolinite in the underlying ply 22 blocking the further infiltration of sulfate from the overlying plies during the deposition. The seam is dominated in kaolinite and, to a lesser extent, in pyrite, and there also exist minor amounts of szomolnokite, diaspore, boehmite, calcite, siderite, dolomite, magnesite, feldspar, gypsum. Szomolnokite and gypsum possibly resulted from the oxidation of pyrite. The seam is greatly characterized by finely-grained pyrite concentrating in cutinite. Hazardous trace elements Hg, Pb and As are mainly concentrated in pyrite, so that they can be partially removed by physical coal cleaning with an aim of removal of sulfur, while thalassophile elements Br, Ca, Cl, Mg and Sr, are clearly associated with the organic sulfur, reflecting that their contents can be decreased by coal blending means due to a partial organic affinity.     

Desulfurization of a Turkish lignite at various gas atmospheres by pyrolysis. Effect of mineral matter

An investigation was made of the removal of pyritic and organic sulfur by pyrolysis at ambient pressure of a Turkish lignite under nitrogen and carbon dioxide atmospheres and the effect of mineral matter on the sulfur removal in pyrolysis of HCl and HCl/HF-treated coal under carbon dioxide atmosphere. Results obtained indicated that both pyritic and organic sulfur removal increased with increasing pyrolysis temperature. The pyrolysis in carbon dioxide atmosphere had more effect on the organic sulfur removal at high temperatures. As a consequence of treatment of coal with HCl, pyritic sulfur removal increased but organic sulfur removal decreased. This implies that the removal of carbonates from coal negatively affects the organic sulfur removal. The observed decrease in organic sulfur removal may be related to the decrease in pyrolytic conversion. It was observed that HCl/HF treatment has an increased effect on the pyritic removal and organic sulfur removal during pyrolysis. The increase in organic sulfur removal after HF-treatment therefore might be due to the removal of clay minerals in the raw coal structure. In addition, it may be said that the presence of silicate minerals in the coal matrix can be induced that the easily removable organic sulfur compounds are converted to thermally stable and non-removable organic sulfur compounds (thiophenic or condensed thiophenic compounds) at these temperatures. Increase in the pyritic sulfur removal of HCl-treated and HCl/HF-treated coal samples may be attributed to the fact that increase of mass and/or heat transport in comparison with untreated coal as a result of elimination of mineral matter.     

利用高硫煤矸石改良土壤的探讨

测定了高硫煤矸石与土壤混合培养不同时间后,土壤ｐＨ值、氧化还原电位值及硫酸盐含量的变化。结果表明：高硫煤矸石中的黄铁矿和有机硫在土壤中氧化,产生硫酸,中和土壤中的盐基物质,从而有效地降低土壤的ｐＨ值,同时,提高了土壤氧化还原电位。     

高硫煤粉永磁干法强磁选试验研究

以平顶山庚组高硫煤粉为煤样,利用实验室自制的永磁强磁选机进行分选试验,发现:随着颗粒粒径的增大,其灰分、硫分也随之增加;该磁选机的最佳分选粒度范围为0.25～0.5mm;磁选脱除的主要是煤中黄铁矿硫,而硫酸盐硫和其他有机硫则变化不大。     

Automated determination of organic sulphur in coal: Use of scanning electron microscopy and energy-dispersive X-ray microanalysis

Scanning electron microscopy combined with energy-dispersive X-ray microanalysis in fully automated form was used for the determination of organic sulphur in coal. The values found by this technique are in good agreement with those found by the usual classical methods, provided the coal has a low content of pyrite. For coals high in pyrite, however, SEM/XRMA gives considerably lower values of organic sulphur. The discrepancy is probably due to the incomplete extraction of pyrite inclusions in the wet analysis leading to a low value for the pyrite content, and consequently, a high value for organic sulphur. Apart from primarily being a method for the determination of organic sulphur, the method presented affords additional information; for example, it may enable a differentiation to be made between a single coal sample and a blend of several types of coal.     

Reductive pyrolysis study of sulfur compounds in different Tabas coal samples (Iran)

A comparative study of the effects of mineral and pyrite removal on the determination of organic sulfur functionalities in representative, as well as its low and high sulfur analogue samples of Tabas coal (C1 seam) were studied by atmospheric pressure-temperature-programmed reduction (AP-TPR) method. The AP-TPR investigation showed the presence of di-aryl sulfides, aryl-alkyl sulfides, simple and complex thiophenic structure in all representative, low and high sulfur samples. There is no indication of the presence of pure di-alkyl sulfides, disulfides or thiols, nor oxidised sulfur forms in the samples. Only minor differences in sulfur functionalities were detected qualitatively between the three analogue samples. Quantitatively differences in sulfur forms were found to be more pronounced. The presence of CH fragments on gases emitted during AP-TPR investigation of demineralised and demineralised pyrite-free samples, shows evidence for the formation of shorter CH chains and of polyaromatic compounds, and lower molecular weight material in the demineralization and pyritic sulfur removal stages.     

乌达矿区煤的洁净利用地质技术与动态评价——地质-采矿-选矿的有机融合、动态协调技术在矿区的实际应用

通过对乌达矿区主采煤层中主要矿物黄铁矿、粘土矿物和有机硫的赋存状态分析 ,认为在现有的技术和经济条件下 ,对单个煤层的降硫脱灰是不切实际的 ,只有综合考虑矿区所有的主采煤层 ,合理布置采区 ,针对不同的煤层 ,选择合适的配比进行煤的洗选 ,实现地质 -采矿 -选矿的有机融合、动态协调是目前提高煤炭质量的最佳途径     

Solubilized coal as a substrate for biodesulfurization

Problem areas in a multi-step coal desulfurization process were investigated. The process involves mild hot air oxidation, followed by alkaline extraction to separate the resultant humic acid molecules from the insoluble pyrite and ash, and microbial removal of organic sulfur from the solubilized coal molecules. A computer-controlled and -monitored solubilization reactor for humic acid production was constructed. Studies designed to evaluate the physical/chemical nature and solubility characteristics of the humic acids were undertaken, with the ultimate aim of ensuring accessibility of sulfur atoms buried in the interior of these large hydrocarbon macromolecules. One per cent Tween-80 enhanced the solubility of humic acids four-fold. Radiotracer labelled humic acids containing 10.8 × 10⁻¹¹ Bq mg⁻¹ of ¹²⁵I were produced. These labelled humic acids will be used to develop an accurate and dependable assay for microbial organic desulfurization.     

云浮硫铁矿尾矿特性及其用作辅助性胶凝材料的性能分析

云浮硫铁矿尾矿堆存量巨大,影响周边环境且浪费资源。本文探讨将尾矿用作辅助性胶凝材料的可行性,以期实现尾矿的高消纳量利用,分析了尾矿的矿物与化学组成以及硫的赋存状态及含量,研究了尾矿用作辅助性胶凝材料的性能和含有的石膏、黄铁矿的演变及其对性能的影响。结果表明:云浮硫铁矿尾矿属于高硫型尾矿,尾矿中的硫以黄铁矿(FeS₂)、磁黄铁矿(Fe_1-xS)、石膏三种矿物形态存在;在硬化水泥浆体中,尾矿中的FeS₂在180 d龄期时氧化程度仍很低;石膏在28 d龄期时大部分已反应生成钙矾石(AFt),是影响性能的主要因素;掺30%(质量分数)硫铁矿尾矿的水泥胶砂28 d活性指数最高可达74%,但相较于3 d和7 d,28 d活性指数不增长甚至下降,180 d龄期抗压强度出现倒缩;将尾矿同时用作水泥混合材和调凝剂可能是一种更好的利用方式。     

Coal Desulfurization and Deashing by Oil Agglomeration

Abstract

Coal organic matter was separated from its associated mineral matter by reducing the material to a fine-size, suspending the particles in water, selectively agglomerating with oil the particles which were largely organic, and screening the suspension to recover the agglomerates. Since particles of iron pyrites tended to be agglomerated with the coal, various means of preventing the agglomeration of pyrite were investigated. In some cases pyrite agglomeration was prevented by suspending the particles in an alkaline solution. In other cases it was prevented by pretreating the particles with a warm alkaline suspension through which air was bubbled to oxidize the surface of the pyrite. However, when this method of pretreatment was applied to several Pennsylvania coals, a considerable part of the pyritic sulfur was extracted through dissolution. An unexpected discovery revealed by scanning electron microscopy was the unusual stability of the coal microagglomerates which remained after the oil was extracted.     

Prospects for biodesulfurization of coal: mechanisms and related process designs

Recent developments in microbiological desulfurization of coal are reviewed. Microbiological removal of organic sulfur from coal remains to be proven conclusively, but is under active study for petroleum biodesulfurization. Microbiological removal of pyritic sulfur from coal is well established in the laboratory and recent efforts have been aimed at scale-up designs and process considerations. Microbiological depyritization may be as inexpensive as other forms of advanced coal desulfurization but it has not been tested on a large scale. Processes based on ‘indirect’ bioleaching of pyrite from coal may also have applications. Other forms of sulfur in coal, such as elemental sulfur, are usually quantitatively insignificant, but nonetheless can be removed microbiologically. Thermophilic bacteria remove pyritic sulfur from coal at faster rates than mesophilic bacteria, in part due to faster abiotic rates of pyrite oxidation at elevated temperatures. Future work in biological desulfurization of coal should include studies on treatment of waste coal or refuse material.     

Surface characterisation of mineral matter in an Australian bituminous coal (Whybrow seam,NSW) using X-ray photoelectron spectroscopy and laser ionisation mass analysis

X-ray photoelectron spectroscopy (XPS), laser ionisation mass analysis (LIMA) and X-ray diffraction (XRD) have been used to investigate composition, occurrence and association of mineral species on polished, fractured and powder surfaces of an Australian bituminous coal from the Whybrow seam, Saxonvale Colliery, New South Wales. XPS on raw coal samples revealed composition and the likely mineral types present which were concentrated predominantly in different bands of the coal. This was further confirmed using a new rapid and selective LIMA experimental method which is devised and optimised for in situ mineral particle identification. A series of mineral species occurring as fine, distributed inclusions were rapidly identified using LIMA, including quartz, pyrite, and a number of clays and carbonates. In addition, evidence for organic and inorganic sulfur species and some trace elements were also obtained from individual particles. Mineral identifications were confirmed by ashing the samples and analysis using XRD. This work highlights the advantages of using XPS and LIMA as complementary methods for coal mineral study.     

川、渝地区高硫煤中硫的分布形态及其脱除率的初步研究

研究了川、渝地区主要高硫煤矿区各种硫的分布形态和经过实验室洗选后各种硫的脱除特性。试验表明,这些高硫煤中的硫大多数为硫铁矿硫,经过洗选大部分可以脱除,而有机硫含量较大的矿区,洗选脱硫的效果不甚理想。     

An investigation on the heterogeneous nature of mineral matters in Assam (India) coal by CCSEM technique

This is a very first preliminary investigation on the distribution of heterogeneous nature of mineral matter in one of the industrially important Assam (India) pulverized coal using computer-controlled scanning electron microscopy (CCSEM). The results show that clay minerals, quartz, pyrite, and pyrrhotite form the bulk of the mineral matter. Minor minerals, such as calcite, dolomite, ankerite, barite, oxidized pyrrhotite, and gypsum, are also observed in the sample. The particle size distribution (PSD) of the included minerals is generally observed to be finer than that of the excluded ones in the coal. As a consequence, the coal rich in included minerals has more small mineral particles, which may affect its reactivity. Regarding the association of individual mineral species, the proportion of included to excluded is found to be higher in major cases. With regard to the modes of occurrence of major inorganic elements, it is found that Si mostly occurs as quartz and clay minerals, while Al mostly occurs as silicate minerals. Fe is primarily present as iron sulfides, iron oxide, and Fe-Al-silicate. S is partitioned into iron sulfides and gypsum. Most Ca occurs as carbonates and gypsum, with a minor fraction associated with clay minerals. Mg is mainly present as dolomite and clay minerals, with a very minor fraction present as ankerite. The majority of alkali elements are associated with aluminosilicates. P is mostly associated with kaolinite and/or present as more complex compounds containing Al, Si, and other elements as apatite is found to be absent in the coal studied. Ti is mainly present as rutile and kaolinite.     

皖北刘二煤在Shell气流床气化过程中熔渣形成机理初探

选取安庆石化sheu气化炉使用的皖北刘二煤（简称AQ007）及气化过程产生的大块渣和细渣样品，利用X-射线衍射仪（XRD），考查了AQ007煤在弱还原性气氛下不同加热温度下煤灰熔融过程中的矿物演变过程，对煤灰的熔融机理进行了探讨，对Shell气化过程产生的大块渣和细渣的晶体矿物组成进行了对比研究。结果表明：AQ007煤中的主要晶体矿物有高岭石、石英、方解石、白云母等。在还原性气氛下，煤灰随着温度的升高，石英、硬石膏等结晶矿物含量逐渐减少，生成新的矿物质，莫来石的生成是导致AQ007煤灰熔点高的主要原因。大量钙长石的生成是导致安庆石化sheu气化炉产生大块熔渣和堵渣主要原因。     

煤中黄铁矿对活性焦SO2和NO吸附性能的影响及机制

黄铁矿(FeS₂)是煤中主要含铁矿物质,且对煤利用具有重要影响,本研究以物理混合的方式在脱灰宁夏无烟煤上负载不同质量分数(0.5%,1%,2%,3%)的黄铁矿,通过水蒸气活化制备活性焦,分析黄铁矿对活性焦制备及污染物脱除性能的影响。结果表明:黄铁矿在活性焦制备过程中发生分解,在水蒸气的参与下最终转化为赤铁矿(Fe₂O₃),且对活性焦的孔结构、微晶结构和表面化学性质等理化结构的形成起调控作用;黄铁矿的加入进一步促进了活性焦微中孔的发育,过量的黄铁矿使煤焦碳结构的无序性增加、石墨化程度降低、孔结构坍塌,NX-1%FeS₂-AC(NX为宁夏酸洗煤,AC为活性焦)的比表面积最高,达到了771 m²/g;黄铁矿可以促进活性焦酸碱官能团的生成,随着黄铁矿含量的增加,活性焦硫容呈现先升高后下降趋势,NX-1%FeS₂-AC表现出最佳的脱硫能力,为68.49 mg/g;与SO₂吸附相比,NO的吸附效果较差,随着黄铁矿含量的增加,NO转化率降低;同时脱硫脱硝过程中,NO吸附迅速达到饱和,整体硫容升高。     

开辟我国硫酸生产的新原料路线--关于湖南湘福石膏矿硬石膏制硫酸联产水泥的可行性探讨

针对我国硫酸生产原料结构的变易,硫磺进口量猛增受国际市场的控制。国内石膏资源丰富并拥有成熟的石膏制酸技术与装备,提出了用硬石膏（CaSO4）生产硫酸的新原料路线。与以硫磺或硫铁矿为原料相比,硬石膏制硫酸（联产水泥）的生产成本比硫铁矿制酸的低（分别为244．63、287．50元／吨）,每吨硫酸的建设投资为413．70元。与硫铁矿制酸的406元／吨不相上下,资源综合利用,认为湘福的“10-15工程”是可行的．该项目对稳定我国硫酸市场,开辟硫酸生产的新原料路线具有战略意义。     

EXTRACTIVE SEPARATION OF URANIUM AND ZIRCONIUM SULFATES BY AMINES

ABSTRACT

This paper describes an amine extraction process for zirconium and uranium separation. The behaviour of an extraction system containing uranium (VI) sulfate, zirconium (IV) sulfate, 0.2 and 0.5 M sulfuric acid (as the original aqueous phase), tertiary amine tri-n-lauryl- amine or primary amine Primene JMT in benzene (as the original organic phase) is discussed on the basis of equilibrium data.

The measured dependences show that the degree of extraction of zirconium at the sulfuric acid concentration of 0.5 M and above is only slightly affected by a presence of uranium in solution. From this surprising behaviour it follows that zirconium may be employed for the displacement of uranium from the organic phase. This effect is more pronounced with the primary amine Primene JMT than with TLA.     

煤浆法烟气脱硫过程中二硫化铁浸出的研究

煤浆洗涤法烟气脱硫基于液相催化氧化原理.实验通过分析含SO2烟气与煤浆中二硫化铁作用后浆液中铁离子浓度及pH的变化,重点探讨了浆液量、煤样粒径等对煤中二硫化铁浸出量的影响规律.实验结果表明,煤浆上清液中的铁离子浓度随反应进行而增加;在反应进行约60 min后,铁离子析出速率相对较快.故此法在脱除烟气中二氧化硫的同时也可降低煤中黄铁矿硫含量.随脱硫过程的进行,pH值逐渐下降,在反应最初30 min内下降较快,随后下降幅度减小.