Oil shale beneficiation by froth flotation

It was found that froth flotation is capable of upgrading oil shale to improve the oil yield in the Fischer assay from 0.117 to 0.175 1/kg at 75% organic recovery in 50% of the rock. Feed particle size affected the float yield and grade and thus the separation efficiency. For economic reasons, grinding to very small particle sizes was avoided. With moderate grinding, particles < 75 μm required less frother and collector to float than particles ? 150 μm and the selectivity was lower for < 75 μm particles. The best separation efficiency was achieved at a feed particle size of 500-150 μm. As the quantities of frother and collector increased, both the float yield and the percentage organic recovery increased, but the percentage mineral rejection decreased. As a result, the separation efficiency reached a maximum at float yields of 40–50%. The types of frother and collector affected the float yield. However, they had no significant effect on the grade of float if the amounts of frother and collector were controlled to achieve the same float yields.     

Removal of motor oil by continuous multistage froth flotation: Effect of operational parameters

A continuous multistage froth flotation column was employed to remove motor oil from water at a low concentration (500 mg/L) using an extended surfactant – branched alcohol propoxylate sulphate sodium salt (C_14-15–8PO–SO₄–Na) – as a frother. The highest separation efficiency (97% motor oil removal with the enrichment ratio of 16 for motor oil) was obtained at a foam height of 60 cm, an air flow rate of 40 L/min, a feed flow rate of 60 mL/min, a surfactant concentration of 0.3% (w/v), and an NaCl concentration of 1.5% (w/v). The process performance increased with increasing tray number but beyond 4 trays, the system could only offer lower concentrations of motor oil and surfactant in the effluent.     

An investigation of the recovery of cryolite from alumina-electrolyte froth by flotation

In the industrial production of aluminium by the electrolysis of alumina, electrolyte froth, which is a mixture of carbon and cryolite is obtained at a rate of 50 kg of froth per ton of aluminium produced. Cryolite can be recovered from this mixture by flotation. In this study, the effects of the following parameters on flotation were experimentally investigated: particle size, type, combination, dosage and ratio of reagents, and conditioning time. It is found that it is possible to decrease the carbon content of cryolite below 1% by suitably choosing the operating parameters. Electrolyte froth must be ground to —100 mesh size for the liberation of carbon particles captured in the cryolite matrix. Any combination of two of the reagents, kerosene, fuel oil, creosote and terebenthene yield good results if used together with pine oil. Pine oil is found to be a more effective frother compared to Pril, a commercial detergent. Satisfactory separations are obtained when a kerosene-fuel oil mixture (50:50, v/v) is used as the collector with a dosage of 3.7 kg per ton of feed together with pine oil, the frother, with a dosage of 0.095 kg per ton of feed.     

微生物培养液脱H2S及副产物的性质

以氧化亚铁硫杆菌培养液和酸性Fe2（SO4）3溶液为吸收剂,采用优化的工艺条件进行了H2S的脱除实验,并对微生物培养液脱H2S后的副产物硫磺的相关性质进行了测定分析,以期为工业应用中硫磺回收工艺的设计提供参考。实验结果表明：采用微生物培养液脱H2S比单纯使用酸性Fe2（SO4）3溶液的效果好,反应进行45 min后,脱硫率仍可保持在90%以上;微生物培养液脱H2S后的副产物硫磺颗粒不溶于水,微溶于乙醇,完全溶于二硫化碳和四氯化碳,密度为1. 90 g·cm-3,熔点为121℃;该颗粒为不规则球形,在溶液中极易发生团聚现象,加入分散剂后测得平均粒径为5. 09 μm;该副产物硫磺具有亲水性,在工业应用上优于具有疏水性的升华硫和酸性Fe2（SO4）3溶液脱H2S产生的硫;该副产物硫颗粒在溶液中的沉降速度为0. 125×10-2 m·s-1。     

Effect of frothers on removal of unburned carbon from coal-fired power plant fly ash by froth flotation

The effect of single frothers and their blends on bubble size, froth stability, and unburned carbon (UC) flotation performance was studied. Methyl isobutyl carbinol that produces smaller bubbles is efficient in floating ultrafine particles and producing concentrate. DF-250 that gives higher froth stability is effective for recovering coarse particles and improving recovery. The presence of DF-250 in the blend increases bubble size and significantly enhances froth stability, and hence the optimal flotation performance is achieved with 75% DF-250. It indicates that the frother giving high froth stability is better in UC flotation due to the little effect of UC on froth stability.     

The effect of different flotation operating parameters on the froth properties and their relation to clean coal ash content

Froth properties and their relation to the concentrate grade play an important role in monitoring flotation running conditions and predicting flotation concentrate quality. In this paper, the correlation between the froth properties and clean coal ash content was investigated under complicated conditions where the frother dosage, gas velocity, and froth height were changed together. For the froth properties under study, their degree of correlation with clean coal ash content decreased in the order of homogeneity, water recovery, gray value, and froth velocity. The coefficient of determination (R²) of the fitting relationship between homogeneity and clean coal ash content was as high as 0.9028, because homogeneity has a close correlation with the foam structure and foam destabilization behaviors.     

Electro-osmotic dewatering of coal froth flotation concentrates

Two coal flotation concentrates were dewatered by electroosmosis in small-scale laboratory tests to 84 and 88 wt% solids at an energy consumption of 25 and 69 kW h/dry tonne, respectively. Vacuum filtration at the washeries yielded 70–75 wt% solids.     

超声波辐射下煤中有机硫的脱除

考察了在甲醇溶剂中 ,超声波辐射下煤中有机硫的脱除。结果表明 :煤中有机硫的脱除率随着碘甲烷用量和超声波辐射时间的增加而增加。根据红外光谱仪和气相色谱 质谱联用分析仪分析结果 ,被脱除的有机硫包括硫醚和二硫化物。应用此工艺从青海煤和伊朗煤中还可脱除噻吩形态的有机硫。     

Biodepyritisation of coal

This review provides a detailed summary of the recent and past research activities in the area of biodesulfurisation of coal. It provides information about microorganisms important for biodesulfurisation of coal, with the emphasis on Thiobacillus ferrooxidans. The review presents an insight into various methods of desulfurisation of coal combining physical and biological methods. Also, there are discussions on coal structure, distribution, mechanism and kinetics of pyrite oxidation and jarosite precipitation. Finally, areas requiring further research are identified. Copyright © 2003 Society of Chemical Industry     

Enhanced desulfurizing flotation of high sulfur coal by sonoelectrochemical method

Enhanced desulfurizing flotation of high sulfur coal was investigated using the sonoelectrochemical method. The supporting electrolyte used in this process was calcium hydroxide and the additive was anhydrous ethanol. The effects of treatment conditions on desulfurization were studied by a single-factor method. The conditions include anhydrous ethanol concentration, sonoelectrolytic time, current density, and ultrasound intensity. For the coal sample with a particle size of − 0.076 mm, the optimal experimental conditions achieved for anhydrous ethanol, sonoelectrolytic time, current density, and ultrasound intensity are 2.1 mol/L, 20 min, 15 × 10^− 3 A/cm², and 1.2 W/cm², respectively. Optimal conditions cause a sulfur reduction of up to 75.4%. The raw and treated coals were analyzed by infrared spectroscopy and a chemical method. Pyritic sulfur, organic sulfur, and ash are partially removed. Compared with enhanced flotation by ultrasound or electrochemistry, desulfurizing flotation of high sulfur coal by sonoelectrochemistry is an effective technology.     

Bioleaching of molybdenum from coal liquefaction catalyst residues

It has been shown that the bacterium Thiobacillus ferrooxidans can solubilize MoS₂ from coal liquefaction catalyst residues. The MoS₂ is formed during the liquefaction process from a molybdenum catalyst precursor. MoS₂ is insoluble; in order to be recovered and reused, it must be converted to a soluble form. T. ferrooxidans can oxidatively solubilize the molybdenum in MoS₂ to molybdate, in which form it can be recovered as a soluble or HCl extractable material. Bioleaching experiments show that with a starting cell concentration of 1.0 × 10⁷ cells ml⁻¹, or greater, a significant amount of the molybdenum in the residue was solubilized. These experiments indicate that the amount of molybdenum biologically solubilized from the liquefaction residues is dependent on inoculum size, with all strains of T. ferrooxidans tested having equal ability, and on the particle size of the residue. An important factor in the solubilization of MoS₂ by T. ferrooxidans is the inhibitory effect of molybdate. Literature reports that as little as 10 ppm molybdate is inhibitory to growth or ferrous iron oxidation. However, leachates containing in excess of 70 ppm molybdenum (equivalent to 116 ppm molybdate) were generated as a result of bioleaching of the liquefaction residue. When cells from previous leaching experiments were used to inoculate flasks containing fresh media and additional liquefaction residue, the bacteria were able to bioleach the fresh residue. Recent experiments have focused on the ability of T. ferrooxidans to produce protective agents in the leachate that minimize the inhibitory effects of molybdate. We found that production of the protective factor(s) did not depend on previous exposure of the cells to molybdenum or liquefaction residue.     

浮选药剂联合使用及其在煤泥浮选中的应用研究

由于药剂协同作用的存在,在将高活性的芳烃MA捕收剂和高选择性的煤油捕收剂混合使用的时候,完善指标最高可超过53,在MA含量为0.4的时候精煤产率和灰分可达为81.8%和11.85%,相对于单一使用MA或煤油在保持高产率的同时,起到了降低灰分,提高完善指标的作用。     

难浮煤泥浮选工艺研究

阐述了难浮煤泥的特点及改善浮选效果的主要方法。以庞庞塔5号煤泥为浮选试样,研究了一次浮选、精煤再选、分支浮选3种不同浮选流程对难浮煤泥浮选效果的影响,从而找到了适合难浮煤泥浮选的工艺流程。结果表明,分支浮选流程可以在满足精煤灰分的要求下,提高精煤产率。     

Biodesulphurization of Hungarian lignite and sub-bituminous coal

The annual SO₂ emission is approx. 0.6 million tons in Hungary because of the high amount of sulphur in the power plant coals. Since Hungary has signed the European Environmental Agreement, the high sulphur emission has to be gradually reduced. To overcome the acid rain problem, the biodesulphurization of Hungarian power plant coals has also been started in Hungary. The R&D programe of biodesulphurization has been launched in 1990. According to our findings the biodesulphurization process is a suitable tool for reducing the pyritic sulphur content in lignite and sub-bituminous coal.     

广西合山高硫煤各种形态硫的分布及其利用途径

高硫煤中各种形态硫的分布及其镶嵌特征是选择煤的脱硫工艺和合理利用的基础,采用氯化锌重液分级和岩相分析手段对合山高硫煤的各种硫的分布作了深入细致的研究,表明合山高硫煤中的有机硫占80％以上,因而很难通过洗选的方法来脱除其硫分。     

基于浮选原理制备低灰煤的研究进展

结合中国煤炭资源现状及国家产业政策,介绍了低灰煤在中国煤炭深加工利用方面的重要性。阐述了制备低灰煤的原料煤性质,即必须具有内在灰分低、质脆易磨、矿物易于单体解离、可选性好等特点,且原煤中含有灰分小于2%的低灰组分,要尽量选择丝质体含量少且可浮性好的中、高变质程度煤。详细介绍了目前制备低灰精煤的2种方法,即预处理+浮选工艺和浮选柱分选工艺,并对2种分选方法的基本分选原理和分选效果进行了分析。最后论述了制备低灰煤的发展趋势,强调了应注重低灰煤专用、低成本、高效率化学药剂的研发和现有设备脱硫降灰效率的提高,采用严格的质量控制和过程控制来保证精煤的稳定性。     

煤炭高梯度磁选-浮选脱硫降灰试验

通过分析煤样性质,说明原煤中无机硫主要以硫化铁硫为主,有机硫较高,仅依靠物理方法很难达到理想脱除效果。通过煤粉高梯度磁选试验研究了磁介质、磁通密度、脉冲对煤炭磁选效果的影响。结果表明:聚磁介质选用不加铜套细网介质,当磁通密度为1.295 T,脉冲为25次/min时,煤粉湿法高梯度磁选脱硫效果最好,此时硫分为1.59%,精煤产率为85.44%,脱硫率为31.87%,脱灰率为38.17%,黄铁矿硫脱除率为45.02%。通过正交试验确定了最佳高梯度磁选条件为:煤粉粒度0.075 mm,磁通密度1.295 T,脉冲25次/min,可得到硫分1.35%,灰分10.37%的磁选精煤产品。最后对磁选精煤进行再浮选试验,得到最佳浮选条件为:石灰500 g/t,捕收剂1360 g/t,起泡剂90 g/t,可获得产率76.29%,硫分1.28%,灰分8.14%的精煤,产品脱硫率为57.73%,脱灰率为58.52%,黄铁矿硫脱除率为84.56%。采用磁选-浮选综合流程,煤粉基本达到理想的脱硫降灰效果,可作为煤种脱硫降灰技术方案的参考。     

泉店选煤厂浮选系统改造

通过分析泉店选煤厂原浮选系统工艺流程,提出了选煤厂主要存在浮选尾煤灰分低,浮选药耗高,浮选系统处理能力偏低,浮选床效率低,浮选精矿池泡沫量大等问题。针对选煤厂存在的问题,提出2种改造方案,并最终确定采用新建浮选车间并安装2台浮选机替换原有浮选床的改造方案。改造完成后,泉店选煤厂浮选尾煤灰分、精煤产率和可燃体回收率分别提高了55.61%,43.86%和44.51%,精煤灰分降低了0.29%,药剂用量减少了0.22 kg/t;浮选精矿池泡沫量明显降低,加压过滤机上料情况明显好转,处理量增大,且减少了1台空压机的使用;选煤厂每年增加精煤收益,节省电费和药剂费用总计12770.74万元。     

微生物起泡剂及其煤泥浮选应用的研究

分离一株能产生微生物起泡剂的假单胞菌(Pseudomonas sp.).考察了该菌株产生起泡剂的特性、起泡剂的成分以及起泡剂在煤泥浮选中的应用.结果表明,添加还原糖为20g/L,在第3d起泡剂达最高量.通过薄层层析分析,表明该起泡剂为脂肽类化合物,具有较高的起泡稳定性.通过微生物起泡剂进行煤泥浮选实验,其浮选效果与杂醇油相当.     

高灰氧化煤的浮选试验研究

针对高灰氧化煤存在的细粒级含量大、灰分高、难浮选等问题,研究了浮选机、浮选柱对高灰氧化煤浮选效果的影响,考察了脂肪醇(乙醇和丁醇)对氧化煤的去氧化作用。浮选机试验表明:经促进剂处理后,煤样浮选效果明显改善,与空白试验相比,丁醇处理后煤样的可燃体回收率提高了12.99%,精煤灰分降低了16.63%;丁醇改善氧化煤浮选效果的能力要强于乙醇,可燃体回收率提高了1.30%～11.43%,精煤灰分降低了0.21%～1.46%。浮选柱试验表明:丁醇对高灰氧化煤的浮选柱分选效果较乙醇好,在循环泵压力为0.16 MPa时,煤泥浮选效果最好,可燃体回收率为38.55%,精煤灰分为19.49%,比相同药剂条件下浮选机试验的可燃体回收率提高了6.26%,精煤灰分降低了3.32%。因此,经脂肪醇预处理后,煤泥浮选效果明显提高,且浮选柱的分选效果要好于浮选机。