Comparative study of the performance of conventional and column flotation when treating coking coal fines

Investigations were carried out on coking coal fines by conventional cell and column flotation techniques. The effects of different operating parameters were evaluated for both conventional and column flotation. The coal fines were collected from Bhojudih washery, India. These coal fines averaged 24.4% ash, 19.8% volatile matter and 53.8% fixed carbon on a dry basis. A commercial grade sodium silicate, light diesel oil and pine oil were used as depressant, collector and frother respectively. The flotation performance was compared with release analysis. The conventional flotation results indicated that a clean coal with 14.4% ash could be obtained at 78.0% yield with 88.4% combustible recovery. The ash of the clean coal could be further reduced to 10.1% at 72.0% yield with 85.6% combustible recovery by using column flotation. The column flotation results were close to those obtained by release analysis.     

A flotation study of refuse pond coal slurry

The flotation behavior of a refuse pond fine coal slurry sample was studied using mechanical and column flotation techniques. Flotation parameters investigated included type and dosage of frother and collector, agitation speed, scrubbing time, slurry pH, etc. for the mechanical flotation cell, and air flow rate, feed flow rate, and wash water flow rate for the column flotation. Flotation kinetics was also studied in the mechanical flotation cell. The results showed that the coal sample was very difficult to clean by flotation. Low yield (5–15%) and low combustible recovery (6–23%) and high product ash (about 22%) were obtained when methyl-isobutyl-carbinol (MIBC) was used as frother and #2 fuel oil as collector. Adjustment of operating parameters such as agitation intensity showed limited effects. However, flotation yield was significantly improved when MIBC and #2 fuel oil were replaced with frother P948 and collector SPP. Mechanical scrubbing was unable to restore the floatability of the coal sample. ‘Ken-Flote’ column flotation was inferior to mechanical flotation for oxidized coal and possible reasons were given.     

细粒难浮煤泥浮选试验研究

分析了内蒙古能源中心选煤厂煤泥性质,说明试验煤泥是以高灰细泥为主的极难浮煤;高灰细泥在浮选过程中容易因夹带、黏附作用而进入精煤,影响精煤质量。通过探索试验发现,煤浆质量浓度为40∥L,捕收剂、起泡剂用量均为1．0kg／t时,煤泥浮选效果最好,此时精煤产率为53．53％,灰分为13．92％,但仍未达到厂家要求。为将精煤灰分降至11％以下,对煤泥进行二次浮选试验。当煤浆质量浓度为50g／L,捕收剂、起泡剂用量均为1．5kg／t,搅拌时间为1min时,二次浮选效果最好,此时精煤产率为52．78％,精煤灰分为10．14％,中煤产率为6．57％,中煤灰分为57．30％,尾煤产率为40．65％,尾煤灰分为76．81％,中煤可直接出售。二次浮选工艺可有效降低精煤灰分,提高精煤产率,解决了煤泥难浮问题,满足了生产需求。     

望峰岗选煤厂煤泥可浮性研究

通过对望峰岗选煤厂煤泥性质的分析,说明入浮平均粒度较粗,各粒级煤泥灰分均在30％以上,嵌布较均匀,单体解离度低,为浮选降灰带来困难;煤泥表面接触角较小为50．06。,说明其天然可浮性较差,经捕收剂十二烷或柴油处理后,煤泥接触角增大,煤的可浮性提高;若要求精煤灰分为14％,则标准浮选精煤产率约为65％。通过单因素试验确定煤浆质量浓度为80g／L,捕收剂用量为800∥t,起泡剂用量为128g／t时,煤泥浮选效果较好,浮选完善度最高为66．94％,精煤灰分符合要求,精煤产率较高为71．67％。最后以捕收剂、起泡剂和煤浆质量浓度为正交因素设计正交试验,考察各因素对煤泥可浮性的影响,并得出最佳浮选药剂制度。结果表明：当捕收剂用量为1000g／t,起泡剂用量为42g／t,煤浆质量浓度为60g／L时,煤泥浮选效果最好,此时精煤产率为71．59％,精煤灰分为14．30％,达到高产降灰的目的。     

A novel process for preparation of ultra-clean micronized coal by high pressure water jet comminution technique

A novel process for the preparation of ultra-clean micronized coal is presented in this paper. High pressure water jet mill replacing the ball mill is employed for coal comminution in the new preparation process, which is the essential difference from the traditional one. To compare the new preparation process with the traditional one, the comparison experiments were performed, with froth flotation tests of the fine particles ground by both mills using 0# diesel oil and n-dodecane as collector, 2-octanol as frother, and sink–float separation tests using mixtures of carbon tetrachloride–benzene and carbon tetrachloride–bromoform as dense liquid. Different parameters including combustible recovery, ash content of the clean coal, separation efficiency, and energy consumption were investigated based on the two different preparation processes. The results show that the new preparation process has high combustible recovery, low ash content of the product, high separation efficiency, and low energy consumption compared with the traditional one.The comminution mechanism of high pressure water jet mill is introduced in this paper. The high pressure water jet comminution technique has great potential in coal pulverization, having the advantages of low energy consumption, low iron content, and low equipment wear.     

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。     

An Electrokinetic Study on the Oil Flotation of Oxidized Coal

Abstract

The objective of this investigation was to study the electrokinetic behavior of oxidized coals and of hydrocarbon emulsion droplets of flotation reagents to indicate the feasibility of separating the oxidized coals from ash materials and pyrite by an oil flotation process. The effects of surfactants and hydrolyzed metal ions were also included. The electrokinetic behavior of the oxidized coals and the hydrocarbon emulsion droplets were studied by an electrophoresis technique. Generally the isoelectric point (IEP) of the coals decreased with increasing degree of oxidation.

A model of selective flotation of oxidized coal is postulated on the basis of the electrokinetic results. This model simply states that in the presence of a suitable amount of collector and frother, the optimal selective flotation of oxidized coal will occur at the IEP of the oxidized coal. To achieve this condition at the coal surface, it is necessary to adsorb heavy metal hydroxide ions prior to flotation and to absorb hydrocarbon oil droplets containing positively charged organic functional groups during flotation. Oxidized coal becomes more hydrophobic at its IEP because most of its surface is relatively non-polarizable. In contrast, pyrite and ash minerals have relatively polarizable surfaces and remain in suspension even when they are at an IEP.     

粉煤灰浮选脱碳

通过一系列条件试验,最终确定＂一粗一扫＂浮选流程,选用轻柴油做捕收剂,粗选用量4000g/t,扫选1200g/t,仲辛醇做起泡剂,粗选用量400g/t,扫选200g/t,粗选矿浆浓度100g/L,充气量0.30 m3/（m2.min）,得到最终粉煤灰产品产率65.54%,烧失量4.21%,达到Ⅰ级灰标准,粗选精碳产率19.85%,灰分58%,有一定的市场价值。     

Optimization of design and operating parameters in a pilot scale Jameson cell for slime coal cleaning

The Jameson flotation cell has been commonly used to treat a variety of ores (lead, zinc, copper etc.), coal and industrial minerals at commercial scale since 1989. It is especially known to be highly efficient at fine and ultrafine coal recovery. However, although the Jameson cell has quite a simple structure, it may be largely inefficient if the design and operating parameters chosen are not appropriate. In this study, the design and operating parameters of a pilot scale Jameson cell were optimized to obtain a desired metallurgical performance in the slime coal flotation. The optimized design parameters are the nozzle type, the height of the nozzle above the pulp level, the downcomer diameter and the immersion depth of the downcomer. Among the operating parameters optimized are the collector dosage, the frother dosage, the percentage of solids and the froth height. In the optimum conditions, a clean coal with an ash content of 14.90% was obtained from the sample slime having 45.30% ash with a combustible recovery of 74.20%. In addition, a new type nozzle was developed for the Jameson cell, which led to an increase of about 9% in the combustible recovery value.     

Optimization of some parameters in column flotation and a comparison of conventional cell and column cell in terms of flotation performance

In this study, a comparative evaluation was made between column and mechanical flotation cells for fine coal cleaning. In addition, the optimum values of operating parameters were examined, which are important to achieve a desired separation performance in column flotation, such as the frother concentration, the collector dosage, the froth thickness, the wash water rate, the air rate and the feeding rate. The coal sample was collected from a classifying cyclone overflow stream consisting of nominally −130 μm material. Ash, volatile mater, fixed carbon and total sulfur contents of the sample were found to be 47.50%, 20.80%, 31.70% and 0.75%, respectively. Comparison of the column and mechanical flotation results indicated that column flotation was considerably more efficient than mechanical flotation for fine coal cleaning. High froth thickness and wash water addition during column flotation made it possible to obtain cleaner coals. The column flotation produced a 15.60% product ash with a 50.92% clean coal yield and 81.85% combustible recovery.     

Performance of classic oils and lubricating oils in froth flotation of Ukraine coal

In this study, the appropriate collector and collector amount for Ukraine coal in froth flotation was determined. For this purpose, the performance of classic oils (kerosene, diesel-oil and fuel-oil) and lubricating oils (spindle oil, bright stock and heavy neutral) was evaluated by combustible recovery, ash rejection and efficiency index. It was found that the combustible recovery and ash rejection changed, depending on the type and concentration of oil. The maximum combustible recovery was obtained by using bright stock. It was determined that bright stock, fuel-oil and kerosene were suitable for the flotation of Ukraine coal. On considering the flotation efficiency index values, the best results were obtained with bright stock and diesel-oil. Consequently, it was shown that bright stock and spindle oil could be used as alternative oils instead of classic oils for cleaning of Ukraine coal by the froth flotation.     

提高煤泥浮选捕收剂性能的试验研究

针对煤泥浮选捕收剂分散难、选择性差、用量大等问题,利用不同化工产品及表面活性剂,将煤油制备成复合捕收剂用于煤泥浮选。分别进行了煤油、复合捕收剂的优选试验及浮选速度试验。优选试验表明:当煤油用量为900 g/t,仲辛醇用量为450 g/t时,煤油浮选效果最佳;当Fy-4复合捕收剂用量为500 g/t,仲辛醇用量为450 g/t时,精煤灰分为9.96%,精煤产率为88.72%,可燃体回收率为94.82%,在精煤灰分相近的条件下,Fy-4复合捕收剂的用量比煤油降低了44.44%,精煤产率和可燃体回收率分别提高了0.06%和0.16%。浮选速度试验表明:Fy-4复合捕收剂不仅节省了药剂用量,而且提高了煤泥浮选活性,提升了精煤浮选速度。最后探讨了无机电解质NaCl对复合捕收剂浮选效果的影响,当NaCl浓度为0.05 mol/L时,煤泥颗粒Zeta电位更趋近零电点,降低了煤泥颗粒的相对接触角,改善了煤泥浮选效果。     

Recovery of unburned carbon from lime calcination process using statistical technique

In this study, unburned carbon recovery from lime calcination plant tailings was investigated using diesel oil, kerosene, MIBC and pine oil. A series of laboratory experiments using 2³ full factorial designs was conducted to determine the types and dosages of collector and frother. For these tests, data were analyzed by the paired t-test. The main and interaction effects on combustible recovery were evaluated using Yates' analysis. By optimizing the flotation parameters at slurry concentration of 34% solids, flotation time of 2.5 min, pH of 7.5, collector diesel oil dosage of 2780 g/t, and frother pine oil dosage of 2620 g/t, unburned carbon (UC) has been successfully recovered with 93.07% combustible recovery (CR) and 6030 kcal/kg calorifical value.     

45m~3机械搅拌式浮选机的设计与应用

为实现浮选机的大型化、高效化、节能化,设计了45 m3机械搅拌式浮选机。阐述了45 m3机械搅拌式浮选机的结构和工作原理,重点分析了浮选机的槽体、叶轮、定子、刮泡机构、假底稳流板等关键部件的设计要求。浮选机清水性能试验表明:叶轮转速137.58 m/s,浸没深度895 mm时,浮选机工艺指标最优。45 m3机械搅拌式浮选机在大阳泉选煤厂的应用结果表明:改造后浮选精煤灰分为10.69%,尾煤灰分为55.35%,浮选精煤产率为68.03%,满足生产要求,且浮选机对不同粒级煤泥都有很好的回收效果。与FCMC3000浮选柱相比,在入料灰分相差不大的情况下,XJM-S45浮选机的尾煤灰分、精煤产率、可燃体回收率、浮选完善指标分别提高了18.61%、18.84%、23.90%、18.30%。     

Beneficiation of Cassiterite Fines from a Tin Tailing Slime by Froth Flotation

The beneficiation of cassiterite fines from a tailing slime in the Datun concentration plant was studied through a froth flotation process, with the chemical scheme of benzohydroxamic acid as collector, lead nitrate as activator, and pine oil as frother. It was found that tin values are mainly contained in the fine fraction of the sample and cassiterite is mostly associated with iron minerals and calcium minerals, so that the desliming treatment and the addition of dispersants and depressants can not be used as it generally results in the undesired loss of tin values. A novel flotation process with no dispersant and depressant as well as no desliming was developed. It showed that this process was effective in recovering the tin values from the tailing slime assaying 0.18% Sn, and produced a concentrate assaying 3.5% Sn with the recovery of 74.16%. It has been found that pine oil played a significant role in improving the recovery for tin values.     

煤泥浮选起泡剂的优化试验

通过对原生煤泥的粒度分析,说明曙光煤业选煤厂煤泥属于高灰煤泥,煤泥中含有较多易泥化矿物质,这些矿物质在浮选过程中容易因机械夹带作用而进入精煤产品,影响精煤质量。以曙光煤业选煤厂原生煤泥为研究对象,分析了不同起泡剂种类和用量对煤泥浮选效果的影响。结果表明:GF油、仲辛醇、TY001的最优浮选药剂组合分别为煤油400 g/t、GF油45 g/t,煤油300 g/t、仲辛醇45 g/t,煤油400 g/t、TY001 45 g/t。当药剂用量相同时,从可燃体回收率看,仲辛醇作用效果最优,其次为TY001,GF油最差;从浮选完善指标看,TY001与仲辛醇性能相当,均明显高于GF油,精煤产率、浮选选择性明显提高,尾煤灰分均达到60%以上。从技术经济方面考虑,在精煤灰分Aj≤11%的条件下,选择煤油与仲辛醇组合较为适宜,最佳药剂用量为煤油300 g/t,仲辛醇45 g/t。     

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。     

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。     

废弃油脂制备煤泥捕收剂的研究

通过小筛分试验和可浮性试验,说明煤泥易泥化,细泥含量高,黏附、夹带严重,导致精煤灰分偏高;煤泥属难浮煤种。采用废弃油脂制备煤泥浮选捕收剂,并进行实验室浮选试验,同时分析药剂作用机理。煤泥浮选试验表明:在精煤灰分相近的条件下,生物柴油对煤泥的捕收性要低于柴油和煤油。当柴油、煤油与生物柴油分别以质量比1∶9复合时,煤泥浮选效果较好,精煤产率分别比生物柴油提高10.52%和9.06%,浮选完善度分别提高5.32%和4.33%。GC-MS分析表明:制备的浮选捕收剂中含有不饱和结构—C=C—、含氧官能团O||—C—和疏水性较强的长链烷烃。生物柴油与非极性烃类油组合用作捕收剂时,主要存在共吸附和促进吸附两种吸附机理,提高了煤泥可浮性,促进药剂在煤浆中分散,增大药剂与煤粒表面的接触概率,降低药耗。     

聚丙烯酰胺作用下的煤泥絮凝浮选

用六偏磷酸钠做分散剂,煤油做捕收剂,进行了不同聚丙烯酰胺（ＰＡＭ）用量下的煤泥絮凝浮选,并在此基础上,对不同煤油用量下,ＰＡＭ对煤泥浮选效果的影响规律进行了对比研究。ＰＡＭ可明显提高浮选速度和精度产率,并节省煤油用量,１ｇＰＡＭ相当于１００ｇ煤油。