等离子体反浮选分离黄铁矿与煤的可行性研究

为了增加黄铁矿与煤的可浮性差异,提出了采用低温空气等离子体改性的思路。采用扫描电镜(SEM)、能谱分析(EDS)、X射线光电子能谱分析(XPS)、接触角、浮选试验研究等离子体处理对黄铁矿和有机质表面性质、可浮性的影响。SEM结果显示,改性后黄铁矿表面形貌变化不大,而有机质表面形貌变化剧烈;EDS和XPS分析表明,黄铁矿表面O含量升高,S含量降低,有机质表面O含量升高,C含量降低,且C—C、C—H键含量减少,C—O、COO—键含量急剧增加;接触角及浮选试验结果表明,处理1~5 min黄铁矿与有机质接触角差值增大了3.5~9.7倍。单独浮选时处理后黄铁矿和有机质浮出率均下降,但有机质降幅更大。等离子体改性显著扩大了黄铁矿与有机质可浮性差异,利用其进行反浮选脱除黄铁矿是可行的。     

黄铁矿的电化学性质及可浮性调控

介绍了电化学电位对黄铁矿可浮性的重要影响，黄铁矿和相应金属间的金属电解电极的电化学调控原理及微浮选试验结果，证明了用电化学方法在煤浮选中控制黄铁矿可浮性的可能。     

还原剂法强化煤浮选脱硫的研究

为了拓宽电化学法在煤脱硫中的应用,研究了还原剂法脱硫的几个影响因素及其脱硫机理,利用X射线衍射对还原剂法处理前后的黄铁矿样进行了分析。结果表明:影响还原剂法脱硫的因素的次序为反应时间>pH值>还原剂用量>反应温度;确定了最佳反应条件,反应时间为20 min,pH=6.65,还原剂(连苯三酚)用量为75 mg,反应温度为30℃;在较优实验条件下,其脱硫率可达到60%。研究表明,还原剂法能使煤与黄铁矿颗粒表面朝不同的方向改性:提高了煤的可浮性,降低了黄铁矿的可浮性;同时还原剂法还能改善煤质,提高煤的燃烧值。     

煤的电化学脱硫机理研究

本文在研究煤的电化学脱硫基础上 ,利用 X-射线衍射和红外光谱等现代测试手段研究了煤中无机硫和煤系黄铁矿硫的电化学脱硫机理。研究表明煤中无机硫和煤系黄铁矿硫的脱硫机理有相似之处。首先在电极表面产生活性氧或高价离子 ,活性氧氧化煤或煤系黄铁矿中无机硫为单质硫或硫酸盐硫。其中煤中硫氧化为硫酸盐硫 ,煤系黄铁矿硫氧化为硫或硫酸盐硫。     

“细粒煤表面改性技术应用研究”通过鉴定

2006年7月15日，由中国煤炭工业协会组织有关专家在北京对山西焦煤西山煤电集团公司和山东矿机集团长沙开通科技有限公司完成“细粒煤表面改性技术应用研究”项目，进行了科技成果鉴定。该项目针对可浮性差的细粒煤难以浮选的技术难题，在山西焦煤西山煤电集团公司东曲选煤厂，改进和应用表面改质机，对难浮煤泥进行了改性处理，在保证精煤质量的前提下，浮选精煤产率提高，油耗降低，取得了较好的应用效果。     

金属腐蚀电偶法进行煤的还原浮选脱硫实验研究

用金属腐蚀电偶法对煤的还原浮选脱硫进行了研究,探索了矿浆电位、pH值、温度等因素对细粒煤浮选脱硫的影响,通过实验证实：在低的矿浆电位和一定的pH值、温度下,黄铁矿能被有效抑制,提高了脱硫效率。大量研究表明,金属腐蚀电偶法能高效脱出高硫煤中的硫分,提高产品质量。     

国外动态

微气泡浮选法脱除煤中黄铁矿硫美国匹茨堡的凯萨工程师公司正在实现微气泡柱浮选法脱除煤中90%黄铁矿硫这一技术的商业化。这一工艺系由弗吉尼亚综合技术学院及弗吉尼亚州立大学的研究人员开发,系基于利用很小的(0.1微米)空气泡。煤经粉碎后与水和化学品混合,化学品包括煤油     

黄铁矿的可浮性与半导性的关系

本文探讨了产自三个不同类型矿床黄铁矿在各种调整剂中的浮选行为,并对各种黄铁矿的半导性与可浮性的关系进行了讨论。单泡浮选试验结果表明,在正常丁黄药浓度下,各种黄铁矿的可浮性存在差异,它们分别受NaOH·FeSO_4·CaO等影响,所显示的可浮性大小顺序是一致的。作者提出一个半导性影响矿物表面形成双黄药的电化学过程动力学模型,利用这一模型,各种黄铁矿可浮性的差别可得到较好的解释。     

表面活性剂在煤浮选中的促进作用及机理

论述了两种表面活性剂在煤浮选中的作用及机理。研究认为：加入少量表面活性剂，能显著改善煤的浮选效果，提高精煤产率和浮选速率。     

化能自养型硫杆菌脱硫机制及脱硫策略

介绍了对化能自养型硫杆菌氧化煤中黄铁矿硫机制的认识过程,讨论了黄铁矿生物氧化机制的新观点:主要包括黄铁矿生物氧化的电化学本质、黄铁矿表面吸附细菌的功能、黄铁矿生物氧化的具体反应途径。采用氧化还原电势或[Fe3+]/[Fe2+]比建立的速率方程可用于描述化能自养型硫杆菌的生物氧化过程,其中中间产物元素硫的进一步氧化可能是限速步骤。针对目前黄铁矿生物氧化机制的新认识,提出了提高煤系黄铁矿硫生物脱除效率的研究策略。此外,如研究证实元素硫为超高硫煤中有机相硫的一部分,化能自养型硫杆菌也将能用于脱除煤中该部分有机硫。     

The flotation behavior of coal-pyrite in high-sulfur coal

ABSTRACT

The properties and flotation behavior of coal-pyrite were analyzed by the contact angle, induction time, and flotation tests. The results indicate that compared with coal, coal-pyrite has a smaller contact angle and longer induction time. The floatability of coal-pyrite is poor with dodecane as the collector. A part of fine liberated pyrite mixed with the clean coal in flotation. The linear relationship between the ash and liberated pyritic sulfur recoveries implies the same recovery mechanism, that is, mechanical entrainment. Molecular dynamics simulation also demonstrates that dodecane could not break through the hydrated film to be absorbed on the pyrite surface.     

Suppression of floatability of pyrite in coal processing by carrier microencapsulation

Carrier microencapsulation, CME, is a technique to form a thin layer of metal oxide or hydroxide on pyrite surface using a water soluble organic carrier combined with metal ions. The present study investigated the effect of CME using a tris-catecholato complex of Si⁴⁺, Si(cat)₃²⁻ on pyrite-coal separation by dynamic bubble pick-up experiments and Hallimond tube flotation experiments using coal, pyrite, and a coal-pyrite mixture. The mineral samples were treated in 0-5 mol m^− 3 Si(cat)₃²⁻ solutions at pH 4-9 at treatment times of 1-24 h. Dynamic bubble pick-up experiments showed that CME treatment converted the pyrite surface from hydrophobic to hydrophilic but did not affect coal's hydrophobic surface. The results of the Hallimond tube flotation experiments of a coal-pyrite mixture at pH 7-9 in the presence of kerosene as a collector showed that pyrite floatability was selectively suppressed after 1 h CME treatment with 0.5 mol^− 3 Si(cat)₃²⁻ while both coal and pyrite were floated without the treatment. This indicates that CME treatment is effective in suppressing pyrite floatability in coal-pyrite flotation.     

Floatability and desulfurization of a low-rank (Turkish) coal by low-temperature heat treatment

It is well known that higher rank coals are inherently hydrophobic whereas lower rank coals are more hydrophilic. Because of the hydrophilic character of low-rank coals, they are difficult to float even at high dosages of oily collectors. In the present study, the floatability behavior of a hydrophilic lignitic coal was investigated with and without low-temperature heat treatment using a column flotation and a Denver flotation cell. The floatability and hydrophobicity of the coal were investigated upon heating the coal at 105 °C. After heating it was found that the floatability, hydrophobicity, and separation efficiency of lignite increased dramatically. A change in the hydrophobicity of lignite before and after the low-temperature heating was determined by FTIR spectroscopy. On the other hand, reverse flotation experiments applied in natural, alkaline, and acidic conditions yielded rather good results. A concentrate assaying 1.52% total sulfur was obtained at natural pH from a feed of 2.50% sulfur.     

电化学技术脱除煤及烟气中的含硫组分研究进展

介绍了酸碱体系下的原料煤脱硫技术、电化学浮选脱硫技术以及电化学烟气脱硫技术（FGD）。对不同体系和不同工艺条件下的脱硫率以及电化学FGD影响因素进行了介绍,为选择脱硫条件提供了参考,并简要评述了电化学方法脱硫的发展前景及方向。     

The Influence of Reagent Dosage on the Floatability of Pyrite During Coal Flotation

Abstract

In general, as the quantity of frother and/or coal collector is increased, so too, does the flotation of the undesired pyrite. The problem is particularly serious with oily reagents. For some coals, however, a collector, such as fuel oil, is required to achieve a high coal recovery. This requires a compromise between the competing desires of a high coal recovery and a high pyrite rejection. This study gives the quantitative effect of reagent dosage on coal and pyrite floatability and details several means of minimizing pyrite floatability during coal flotation. The effect of fuel oil on coal flotation is especially interesting in that the flotation process changes from froth flotation to emulsion or agglomerative flotation as the amount of oil is increased. This phenomenon provides an additional method of rejecting pyritic sulfur.     

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。     

Performance,mixing and kinetics study in the flotation column reactor using coal

ABSTRACT

A flotation column has been designed and characterized with respect to gas velocity, slurry velocity, frother concentration, gas holdup, bubble surface area flux for the study of the mixing property, liquid phase residence time distribution, flotation recovery and rate constant. The study was performed using coal as solid. A strategy of integrating chemical kinetics into the flotation process to test the floatability behaviour of coal and to estimate floatability parameter of coal has been developed. The results indicate that the coal floatability parameter is 3.05 × 10^?4. A relationship between gas holdup and bubble surface area flux was developed.     

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。     

The influence of process parameters on desulfurization of Mezino coal by HNO3/HCl leaching

Coal desulfurization prior to usage is a preprocessing in order to achieve clean fuel and reduce environmental impacts such as acid rain. Desulfurization of Tabas Mezino coal was conducted with two consecutive steps of froth flotation at ambient temperature followed by leaching at various conditions. Reducing the ash content of Mezino coal by 35.7 wt.% and its total sulfur content by 36.9% using froth flotation process was successful. HCl and HNO₃ were used, separately, to leach the floated coal, and the effectiveness of each acid on Mezino coal desulfurization was investigated. Nitric acid was found to be much more effective than HCl and the effects of reaction time, acid concentration and temperatures as well as stirring speed were studied as major parameters in the nitric leaching process. Taguchi orthogonal experiment with the above mentioned parameter elements; one at three levels was used to optimize the experiment parameters by the analysis of variances. Applying of the Taguchi technique significantly reduced the time and cost required for the experimental investigation. The findings indicated that acid concentration, with a high contribution, had the most dominant effect on desulfurization performance, followed by temperature, stirring speed and time. Accordingly, the optimum condition was obtained as, temperature: 90 °C., acid concentration: 30%., and stirring rate: 1000 rpm. The total sulfur and ash removal after flotation and leaching at optimum condition reached to 75.4 and 53.2% respectively that is a remarkable result compared to the previous works.     

低阶煤可浮性及浮选速率模型研究

针对低阶煤浮选困难的问题,采用煤质分析和筛分试验研究了低阶煤的可浮性。在此基础上进行了低阶煤浮选速度试验,并利用试验结果对低阶煤的浮选速率模型进行曲线拟合,经过MATLAB数值计算建立了最终的浮选速率模型。煤泥可浮性试验表明:低阶煤中挥发分、水分和O含量较高,亲水性强,可浮性很差。浮选速度试验表明,随着浮选时间的增加,精煤产率逐渐升高,尾煤产率逐渐降低,当精煤灰分为11.50%时,精煤产率仅为34.46%,尾煤产率高达65.54%,尾煤灰分仅为19.95%;2种浮选速率模型中,一级矩形分布模型计算误差较小,且相关系数平方R2更接近1,达到了很高的拟合精度,因此一级矩形分布模型是低阶煤最合适的浮选速率模型。