简易水处理活性炭的选择和应用方法

首先介绍活性炭性能测试与水处理活性炭选炭、吸附技术选择、工艺应用的关系,其次报导两个活性炭选用方面的改进方法。通过重新定义、整合、完善现有活性炭性能指标,建立了以酚值、碘值、亚甲基蓝、丹宁酸值为吸附性能指标的选炭方法。这四种指标化合物的分子量与直径覆盖了大多数有机污染物的范围,用此法可减少活性炭应用测试的炭型。在活性炭精选和吸附工艺应用研究中,用微型炭柱进行穿透实验可弥补缩小式传统型、小型炭柱的不足。相对于国外现用微型柱的实验方法,文中介绍的微型柱快速穿透(MCRB)方法的设备要求较低,操作简单,可以在国内大多数实验室中进行;通过对多种污染物质的实验结果,建立了MCRB方法的可信性和适用性。这两种新方法完善了活性炭水处理研究的实验体系,可降低其应用于水与污水处理的成本,有利于中国的环境保护。

中置生物活性炭滤池的选炭

实验通过对传统臭氧-生物活性炭工艺的调整,采用臭氧-曝气生物活性炭滤池-砂滤池工艺,对比研究了4mm柱状炭、4 mm破碎炭和1.5 mm柱状炭3种不同类型活性炭用于给水深度处理的运行效果。结果表明,粒径为1.5 mm的柱状炭对有机物和氨氮的去除效果以及出水浊度方面优于其他2种活性炭,但炭滤池水头损失偏大,且不够稳定,适当增加柱状炭的粒径可稳定和降低滤池的水头损失。

新疆煤基压块活性炭在BAC工艺中的应用

鉴于新疆丰富的煤炭资源,本研究对由2种不同指标新疆煤基压块活性炭(LBC和HBC)组成的上向流活性炭柱构成的小试生物活性炭(biological activated carbon,BAC)工艺进行了为期约300 d的实验研究。考察了2种不同指标的压块活性炭柱(LBC-O_(3)与HBC-O_(3))的运行情况。结果表明,LBC-O_(3)对于COD_(Mn)的去除效果优于HBC-O_(3)(进水平均值为1.56 mg·L^(-1),出水平均值为0.55 mg·L^(-1));而HBC-O_(3)对于UV_(254)所代表有机物去除效果优于LBC-O_(3)(进水平均值为0.053 cm^(-1),出水平均值为0.005 cm^(-1))。LBC-O_(3)对COD_(Mn)的较佳去除性能,促成了活性炭表面微生物量的生长,进而构成了吸附和生物降解的良性循环;而兼具发达次微孔和中孔结构的HBC-O_(3)对UV_(254)代表的有机物表现出了靶向吸附性;微生物检测结果和炭柱出水中溶解性有机物的光谱特性分析验证了该结论。因此,结合目标水体中污染物的特性靶向选择相应指标(孔隙结构)的压块活性炭可取得更佳的BAC工艺处理效果:提高污染物去除率、节约资源,符合双碳目标。

Low Density Dry Coal Beneficiation Using an Air Dense Medium Fluidized Bed

For the production of low ash content clean coal, separation at low density is required for some raw coals.Based on analyzing the fluidizing characteristics of magnetic-pearls with a specific size clistribution and formation mechanism of a microbubble fluidized bed, optimal technological and operating parameters suitable for low density coal separation were determined. The experimental results show that an air dense medium fluidized bed with low den-sity can be formed using magnetic pearls as medium solids, which can efficiently beneficiate coal of 6-50 mm size with a probable error Ep value of 0.05 at a separating density of 1.44 g/cm^3.

Green coal mining technique integrating mining-dressing-gas draining-backfilling-mining

Aiming to address the following major engineering issues faced by the Pingdingshan No. 12 mine:(1) difficulty in implementing auxiliary lifting because of its depth(i.e., beyond 1000 m);(2) highly gassy main coal seam with low permeability;(3) unstable overlying coal seam without suitable conditions for implementing conventional mining techniques for protective coal seam; and(4) predominant reliance on ‘‘under three" coal resources to ensure production output. This study proposes an integrated, closed-cycle mining-dressing-gas draining-backfilling-mining(MDGBM) technique. The proposed approach involves the mining of protective coal seam, underground dressing of coal and gangue(UDCG), pressure relief and gas drainage before extraction, and backfilling and mining of the protected coal seam. A system for draining gas and mining the protective seam in the rock stratum is designed and implemented based on the geological conditions. This system helps in realizing pressure relief and gas drainage from the protective seam before extraction. Accordingly, another system, which is connected to the existing production system, is established for the UDCG based on the dense medium-shallow trough process. The mixed mining workface is designed to accommodate both solid backfill and conventional fully mechanized coal mining, thereby facilitating coal mining, USCG, and backfilling. The results show that: The mixed mining workface length for the Ji15-31010 protected seam was 220 m with coal production capacity 1.2 million tons per year, while the backfill capacity of gangue was 0.5 million tons per year. The gas pressure decreased from 1.78 to 0.35 MPa, and the total amount of safely mined coal was 1.34 million tons. The process of simultaneously exploiting coal and draining gas was found to be safe, efficient, and green.This process also yielded significant economic benefits.

Research on Existing Pattern of Carbon and Its Removal from Fly Ash

Fly ash is a fine and dispersed powder discharged from power station after the coal being burned. With the deepening of people’s recognition about the pollution problem of fly ash, the ways of utilizing fly ash are gradually increasing. Utilizing value of fly ash is closely related to the unburned carbon content.On the basis of analysis of modern testing method,a fundamental thinking is theoretically posed for decreasing unburned carbon content from fly ash by a dry removing carbon technology. The triboelectric separation method shown that the above mentioned thinking of dry removing carbon from fly ash is practical.

Modeling of fine coal flotation separation based on particle characteristics and hydrodynamic conditions

Flotation is a complex multifaceted process that is widely used for the separation of finely ground minerals. The theory of froth flotation is complex and is not completely understood. This fact has been brought many monitoring challenges in a coal processing plant. To solve those challenges, it is important to understand the effect of different parameters on the fine particle separation, and control flotation performance for a particular system. This study is going to indicate the effect of various parameters （particle Characteristics and hydrodynamic conditions） on coal flotation responses （flotation rate constant and recovery） by different modeling techniques. A comprehensive coal flotation database was prepared for the statistical and soft computing methods. Statistical factors were used for variable selections. Results were in a good agreement with recent theoretical flotation investigations. Computational models accurately can estimate flotation rate constant and coal recovery （correlation coefficient 0.85, and 0.99, respectively）. According to the results, it can be concluded that the soft computing models can overcome the complexity of process and be used as an expert system to control, and optimize parameters of coal flotation process.

Nanobubble generation and its applications in froth flotation(part IV):mechanical cells and specially designed column flotation of coal

Coal is the world's most abundant fossil fuel.Coal froth flotation is a widely used cleaning process to separate coal from mineral impurities.Flotation of coarse coal particles,ultrafine coal particles and oxidized coal particles is well known to be difficult and complex.In this paper,the nanobubbles' effects on the flotation of the varying particle size,particle density and floatability coal samples were evaluated using a bank of pilot scale flotation cells,a laboratory scale and a pilot scale specially designed flotation column.The parameters evaluated during this study include the flow rate ratio between the nanobubble generator and the conventional size bubble generator,the superficial air velocity,collector dosage,frother concentration,flotation feed rate,feed solids concentration,feed particle size,and the superficial wash water flow rate,etc.The results show that the use of nanobubbles in a bank of mechanical cells flotation and column flotation increased the flotation recovery by 8%～27% at a given product grade.Nanobubbles increased the flotation rate constants of 600～355,355～180,180～75,and 75～0 microns size coal particles by 98.0%,98.4%,50.0% and 41.6%,respectively.The separation selectivity index was increased by up to 34%,depending on the flotation feed characteristics and the flotation conditions.

Coal washing scenario in India and future prospects

Coal Washing Exploration in India dates back to 1900s; though, first coking coal washeries in India were installed after independence. At present, most of the coking coal washeries are owned by Public Sector Companies; whereas, most of the non-coking coal washeries are owned by Private Sector. Even after six decades of coal washing practices, there has not been significant development in the coal washing intelligentsia. Indian Coal Washing industry is still dependent on imported equipment, which has been designed to treat coal that is significantly different from Indian coal of drift origin. In this paper, authors have ventured into evolution of Indian Coal Washing Industry （with a focus on coking coal washing sector）, its present condition and future prospect for growth. The paper emphasizes need for developing indigenous solutions to industrial challenges and highlights importance of increased coordination among academia-research institutions and coal industry.

Treatment of flotation wastewater using biological activated carbon

A laboratory scale up-flow biological activated carbon(BAC) reactor was constructed for the advanced treatment of synthetic flotation wastewater. Biodegradation of a common collector(i.e., ethyl xanthate) for non-ferrous metallic ore flotation was evaluated. The results show that the two stages of domestication can improve microbial degradation ability. The BAC reactor obtains a chemical oxygen demand(COD) reduction rate of 82.5% for ethyl xanthate and its effluent COD concentration lowers to below 20 mg/L. The kinetics equation of the BAC reactor proves that the activated carbon layers at the height of 0 mm to 70 mm play a key role in the removal of flotation reagents. Ultraviolet spectral analysis indicates that most of the ethyl xanthate are degraded by microorganisms after advanced treatment by the BAC reactor.

Cassava Anthracnose Disease and Varietal Screening for Resistance in Akwa Ibom State of Nigeria

Cassava （Manihot esculenta Crantz） production in Akwa Ibom State is limited by cassava anthracnose disease （CAD） which causes enormous losses in planting materials. Survey of the disease was conducted in the wet and dry seasons in six major cassava-growing areas （Essien Udim, Ikono, Itu, Nsit Atai, Oruk Anam and Uyo） of the State to determine the incidence and severity of the disease. Ten commonly grown cassava varieties were then screened in the greenhouse by inoculating each variety with the spore suspension of virulent isolate of the cassava anthracnose pathogen. Disease severity was assessed using size of lesions on the inoculated plants and defoliation caused by the infection. Results of the survey showed that Nsit Atai is a high infection area for CAD. It recorded the highest disease incidence and severity in both the wet season （36.59% and 3.52） and dry season （9.26% and 2.20）, respectively. The mean disease incidence （24.10%） and severity （3.23） for the six study areas were higher in the wet season indicating the importance of this season in the occurrence of CAD. Results of the screening test showed that TMS 98/30572 was resistant to the disease. The small lesion size （5.00 mm） observed in this variety would ensure less stem disruption and timely delivery of resources to the actively growing points. The low defoliation （5,65%） observed in the same variety would enhance the photosynthetic capacity of the plant. Therefore, TMS 98/30572 may be recommended to cassava farmers in Akwa Ibom State.

Vibrated fluidized bed air classification of moist raw coal

Vibrated fluidized bed air classification is completely different from traditional screening in principle. It extracts fine coal from moist raw coal by entrainment of an ascending airflow in a vibrated fluidized bed. Pilot tests showed that air classification efficiencies varied from 74.85% to 93.84% at cut-size 6, 4, 3, 2, 1, and 0.5 mm when free moisture of coal is in the range of 1.7% to 9.5%, and ash contents of fine coal products were 2%～3% lower than those of the same size fractions in feed, and 4%～10% lower than those of feeds for most cases because of the density differences between coal and waste, which is beneficial to producing lower ash fine coal from raw coal as fuel of blast furnaces or pulverized coal firing boilers. A commercial unit of 100 t/h has been in smooth operation, and several 300～400 t/h units are in plan or construction.

Coal washing improvement by determination of optimal mixture of feed blends

Coals from different mines are feed in the Zirab plant without any control on weight percentage blending of them. Three major coal types of different ranks (Kiasar, Lavidj and Karmozd) were blended in various proportions to find an optimum condition in flotation circuit in Alborz Markazi coal washing plant. Flotation tests were conducted for prepared blended coal samples to assess floatability of various coal samples. In this paper, mixture design as a statistical method was used to optimize coal blend to increase recovery and grade in Zirab coal washing plant. The statistical analysis showed that the weight percent blending of different coals and interaction between Lavidj and Karmozd regions coal had significant effects on the coal recovery. The optimum condition of 95% recovery and 12% ash content could be reached with 10%, 20%, and 70% blending portion of Kiasar, Lavidj and Karmozd regions coal, respectively.

AN INVESTIGATION OF THE HYDROPHOBIC AGGLOMERATION CHARACTERISTICS OF EASY DEGRADATION COAL FINES IN WATER

The separation of ultrafine coal from three Chinese coal samples of easy degradation coal fines in water has been investigated by the application of a hydrophobic agglomeration process. In addition to yielding clean coal with high recovery, this process requires significantly less oil concentration for agglomeration (less than 0.4% in oil-water weight ratio) and produces stabler agglomerates than general oil agglomeration process, the cost of the oil would no longer be an important consideration for its commercial application. Neutral diesel oil was used to make oleophilic coal particles agglomerated with good rejection of clay minerals under little oil consumption and certain agitation speed at 2000 r/min. An important advantage of this process compared with other cleaning fine coal methods is that it can extremely reduce or eliminate the effects of coal degradation and some clay minerals on coal preparation.

RESEARCH ON THE QGS2020 TYPE PIANO-WIRE PROBABILITY SCREEN

Integrating the probability screen with the piano-wire screen, the authors developed the QGS2020 type piano-wire probability screen (PWPS), a new screen which has a large capacity, high efficiency, and no blinding. The results of the indus trial tests show that this screen is suitable for dry sCreening the fine particles from high-moisture raw coal. This paper describes the operation principles, the structure features and the mechanical model of the QGS2020 type PWPS, and also includes data from industrial tests.

Coal flotation using wash oil as a new type of collector

The use of wash oil as a coal collector is proposed to overcome the disadvantages of regular collectors in coal slime flotation. These disadvantages include high price, limited sources and high consumption. The effect of additives on flotation was studied and an innovative ＂one rough separation--one cleaning separation＂ flotation technology was developed. The experimental resuits show that the clean coal ash content decreases by about 1.36% and the clean coal yield declines by around 10% with the application of the depressant. There is an increase of 3.76% in the yield of clean coal and a decrease of 0.40% in the ash content caused by utilizing a dispersant. An ultimate product having an ash content of 10.78% and yield of 70.12% can be attained using a combination of dispersant and depressant. The use of this new technology decreases the ash content by 1.21%, decreases the yield by 2.80% and an increases the coal flotation perfect index by 2.03%. Compared to common flotation, the utilization of the new technology reduces ash by 0.17%, increases yield by 5.3% and increases perfect index by 4.18%.

Flotation of Brazilian and Colombian Coals Using a Negative Bias

Brazil and Colombia have large reserves of coal. Those reserves in Brazil are located predominantly in the south and the main reserves in Colombia are located in the north. Despite the relative ease of exploitation, these resources have been underestimated as a source of energy. Currently, these countries are developing projects and partnerships aiming to qualify this mineral resource, adding quality to the final product of the processing plants. In this scenario, the processing of Brazilian and Colombian coal in flotation columns appears as a promising alternative, having been successful in mineral systems containing fine particles. The paper aims to study the overall process of column flotation for a specific Brazilian coal and a specific Colombian coal. The material used in this study consists of fine coal from Brazil （Copelmi） and Colombia （Cerrejon）. The objective is to recover carbonaceous matter and reduce the ash and contaminants grade. The two coals were floated using a negative bias in a 5 cm diameter conventional flotation column of 5 m high. Flotation parameter investigated included air velocity in the range 0.6 to 1.5 cm/s. For all runs, a constant negative bias of-0.25 cm/s and a pulp concentration of 8% w/w were used. For Cerrej6n coal, 300 g/ton of frother and 907 g/ton of collector was used, whereas for Copelmi coal, 600 g/ton of frother and 1,815 g/ton of collector was employed. The frother was a commercial Aerofroth 65 （AF65）, whereas the collector was Kerosene. For the Colombian coal, in general, yield, organic recovery, ash recovery and water recovery decreased with the increasing air rate. However, for Brazilian coal the air rate had no significant effect. For Colombian coal, the highest yield （60% w/w） and organic recovery （69% w/w） were obtained at the lowest air rate （0.6 cm/s）.

Catalytic Performance of Carbon Materials Supported Pd Nanoparticles in Selective Hydrogenation of Acetylene

Pd/C catalysts were prepared by deposited Pd nanoparticles （NPs） on different carbon supports including activated carbon （AC）, graphite oxide （GO）, and reduced graphite oxide （rGO） using sol-immobilization method. Through transmission electron microscopy, powder X-ray di raction, and X-ray photoelectron spectroscopy, the role of the carbon supports for the catalytic performances of Pd/C catalysts was examined in selective hydrogenation of acetylene. The results indicate that Pd/AC exhibited higher activity and selectivity than Pd/GO and Pd/rGO in the gas phase selective hydrogenation of acetylene. Thermal and chemical treatment of AC supports also have some effect on the catalytic performance of Pd/AC catalysts. The differences in the activity and selectivity of various Pd/C catalysts were partly attributed to the metal-support interaction.

EXPERIMENTAL STUDY OF DESULFURIZATION OF ZHONG LIANG SHAN HIGH SULFUR COAL BY FLOTATION

Emission of large amount of SO2 from combustion of liigh sulfur ctal causes serious envitonmcntai pollution. Pre-combustion desunrization of high sulfur coal has become a necessity.Thts paper reports test results of fine coal dcaulfurization with different flotation technology and theeffect of pyrite depressant. Test work showed that when the coal sample from Zhong Liang Shanwas processed with a Free Jet Flotation Column its pyritic sulfur content was reduced from 3.08%to 0. 84%, with 72. 22% recovery ofcomhustiblc matter in clean coal. The coneept of Desulfuriza tion Efficiency Index E for comprehensive evaluation of desumirhation process is proposed, whichis deffeed as the product of the ratio of sulfur content reduction of clean ctal and the recovery ofcomhustihle matters.