预涂覆膜除粉技术的研究

在印刷过程中,印张要经过喷粉处理,喷粉既可以防止印张之间的粘结,又可以防止印张落下时蹭脏前一印张。经喷粉处理后的印刷品若要进行覆膜、过油或上光,必须要进行除粉。除粉装置采用了扫粉和粘粉相结合的结构。扫粉部采用3个毛刷辊,用一个大吸粉风箱罩住,粘粉部采用胶辊和热压钢辊、两辊边装有硬毛刷用以扫除辊上的墨粉,通过吸风管到喷粉过滤箱。对除粉原理进行了分析,并对除粉各工艺参数的确定进行了理论分析及讨论。

除粉功能的尿素板冷器技术开发和应用

具有除固体粒子粉尘功能和冷却双重功能的尿素板冷器,适合尿素、复合肥、塑料等固体颗粒物料生产,具备能耗低、运行成本低、占地面积小、无废气排放等优点,符合绿色低碳生产要求。

机制砂在高频振动下风力除粉的机理及试验研究

机制砂不同于天然河砂,在机械破碎过程中会产生大量石粉,科学地控制石粉含量是保证机制砂混凝土质量的关键.在对干法机制砂除粉工艺研究和试验的基础上,提出了一种首先通过高频振动对机制砂进行粉团分散、粉砂分离、粗细分级的预处理,然后通过风力除去所含石粉的除粉方法;借助离散元分析及流体动力学仿真软件,对高频振动与普通振动进行比较,研究团聚性石粉及黏附性石粉颗粒间黏结键断裂的机理,验证了机制砂经高频振动筛分后除粉效率得到较大提高的论述;对于传统除粉技术,高频振动筛分与风选相结合的除粉工艺,具有较大的优势和发展前景.

SAS离心式选粉机除粉效率的试验研究

针对目前制砂线成品砂级配中150μm以下石粉含量严重超标的窘境,提出SAS离心式选粉机+制砂线的解决方案,将石粉含量降到最低,保证机制砂符合水泥建筑用砂标准、沥青路用混凝土用砂标准。研究成果为公司制砂线成功上线提供了数据支持,并且为客户提供了机制砂整体解决方案,提升了公司产品的口碑。

离子风除粉器在塑料颗粒料处理中安全隐患的探讨

基于塑料颗粒料除粉处理领域,离子风除粉器在实际工况下与相关规范要求,分析了离子风除粉器可能存在粉尘爆炸隐患。

具有除粉尘功能的Solex尿素板冷器技术介绍

该技术是一种具有除固体粒子粉尘功能的尿素板冷器，具有除粉尘和冷却双重功能，适合既需要冷却又需要除粉尘的固体颗粒产品，如尿素、复合肥、塑料等固体颗粒物料行业，具有除粉尘功能的Solex板冷器具有能耗低、运行成本低、去除产品中粉尘、占地面积小、无废气排放等优点，是一种绿色低碳的冷却技术。

浅析高速旋转式压片机跑粉现象

通过试验设计的方法,对高速压片机的跑粉现象进行研究,并提出改进措施。

Preparation of high purity cadmium with micro-spherical architecture from zinc flue dust

This research has focused on the treatment of zinc flue dust by an acid leach process, combining an environmentally suitable impurity removal process to recover cadmium. Optimum conditions were found as follows： H2SO4 concentration 90 g/L, liquid/solid ratio 6：1, leaching temperature 60 ℃ and leaching time 1.0 h. Under these conditions, 95.8% cadmium was recovered. FeAsO4 and Fe（OH）3 precipitates with FeCI3 are found to be highly effective to obtain a high degree of separation of heavy metals and the oxyanions of arsenic from the leachate. The overall separation of arsenic and other heavy metals and precipitate settling rates are optimum at n（Fe）/n（As） ratio of 3：l and pH 6. The removal rates ofFe, Pb and Cu from the solution were greater than 98.9%, and As removal rate was 99.6%. A solvent extraction with P204 was used for the separation of zinc and cadmium. Optimum conditions are obtained as follows： 20% P204 （volume fraction） diluted with kerosene at room temperature, pH 3.0, and varying organic/aqueous （O/A） phase ratio 1：1. The extraction rate of zinc is 99.2% under these conditions. Spherical cadmium particles showing nearly uniform size were produced by hydrogen reduction at 310 ℃ and the crystal structure was cubic. In addition, the purity of the recovered cadmium powder is more than 99.99%.

Construction of Maize Universal Expression Vector PGM-35Sbar and Maize Transformation

[Objective] The paper was to construct maize universal expression vector, in order to provide basis for using transgenic methods to improve abiotic stress tolerance of maize. [Method] Based on the transformation of existing pGreen0229 plant expression vector, phosphinothricin-resistant selectable marker-bar gene driving by CaMv35S promoter was constructed, which could be used to connect target gene of maize expression vector PGM-35Sbar, and transform Ji444 maize inbred lines by pollen tube pathway. [Result] The universal expression vector for PGM-35Sbar maize had been successfully constructed. When the maize plants were transformed, 14 resistant plants were obtained, and 12 plants were identified to be positive plants by PCR detection. [Conclusion] The study provided basis for rapid construction of maize expression vector containing specific target gene.

Removal of aqueous Ni(Ⅱ) with carbonized leaf powder: Kinetics and equilibrium

Nickel is a heavy metal which has the potential threaten to human＇s health and attracts public concern recently. The carbonized leaf powder is expected as suitable adsorbent for Ni（II） removal became of the composition of some beneficial groups. In this work, carbonized leaf powder was evaluated for its adsorption performance towards Ni（II）. According to the results, adsorbent component, dosage, initial solute concentration, solution pH, temperature and contact time can significantly affect the efficiency of Ni（II） removal. Sips model fits the test results best, and the adsorption capacity towards Ni（II） is determined around 37.62 mg/g. The thermodynamic behaviors reveal the endothermic and spontaneous nature of the adsorption. The free adsorption energy （fluctuate around 8 kJ/mol） predicted by D-R model indicates that the adsorption capacity originated from both physical and chemical adsorption. Room temperature （15-25 ℃） is suitable for Ni（II） removal as well as low energy consumption for temperature enhancement. Further conclusions about the mechanism of chemical adsorption are obtained through analysis of the FT-IR test and XRD spectra, which indicates that the adsorption process occurs predominantly between amine, carbonate, phosphate and nickel ions.

Effects of atomization parameters of dust removal nozzles on the de-dusting results for different dust sources

In order to obtain appropriate spray pressure and enhance the spraying and dust removal efficiency, various factors including the dust characteristics, nozzle spraying angle, effective spraying range, water consumption and droplet size are taken into account. The dust characteristics from different mines and atomization parameters of different pressure nozzles were measured. It was found that the internal pressure of coal cutters and roadheaders should be kept at 2 MPa, which could ensure large droplet size, large spraying angle and low water consumption and hence realizing a large-area covering and capture for large particle dusts. However, the external spray pressure should be kept at 4 MPa for smaller droplet size and longer effective spraying range, leading to effective dust removal in the operator zone. The spray pressure of support moving, drawing opening, and stage loader on a fully mechanized caving face and stage loader on a fully mechanized driving face should be kept at 8 MPa, under which the nozzles have long effective spraying range, high water flow and small droplet size for the rapid capture of instantaneous, high-concentration and small size dust groups. From the applications on the caving and driving faces in the coal mines, it is indicated that the optimization of spray pressure in different spraying positions could effectively enhance dust removal efficiency. Selecting appropriate nozzles according to the dust characteristics at different positions is also favorable for dust removal efficiency. With the selected nozzles under optimal pressures, the removal rates of both total dust and respirable dust could reach over70%, showing a significant de-dusting effect.

Evaluation of Commercial Active Carbons for the Removal of s-Triazine Herbicides from Waters

The adsorption capacity of powdered active carbons, used in a water treatment facility, for the removal of the triazine herbicides propazine, prometryn and prometon, was evaluated. Kinetic studies showed that some of the carbon samples used could be suitable in the practice for the treatment of moderate contents of the herbicides in contaminated waters. Equilibrium studies showed that the data fit the Frumkin isotherm. The results show that in the adsorption process there are repulsive lateral interactions that depend mainly of the adsorbate molecules rather than the nature or distribution of adsorption sites. Such lateral interactions seem to be established mainly between the isopropyl groups of adjacent molecules, being of the same order for the three molecules. The effectiveness of the active carbons was evaluated by determining the percentage of reduction achieved by each product.

Silver removal from molten lead through zinc powder injection

A silver removal process was carried out on a Pb-Ag alloy through zinc powder injection of three different sizes （3.55, 44.4 and 734.8μm） with a top submerged lance using nitrogen as carrying gas. The higher silver removal was obtained for the zinc powder size of 44.4μm, while the lowest silver removal efficiency was attained for the smaller particle size. The AgZn phase was detected in the slag for the 44.4 and 734.8μm particle sizes by XRD, which was in agreement with SEM-EDS analysis. Experimental behavior was explained according to the melting and residence time of the injected particles.

PARTICLE ELECTROSTATIC COAGULATION AND ITS APPLICATIONS IN DUST CONTROL

Fine particulates instead of others create particulate pollution and they are easier to escape from almost all conventional collectors of low- or medium-efficiency. It is of practical significance to take full advantages of particle coagulation by electrostatic forces to upgrade the collertors' performance. This paper investigates the main mechanisms of coagulation, all possible electrostatic forces existing in the collectors and their effects on the particle coagulation. To make particle kinetic coagulation electrostatically enhanced be a step of the conventional collectors. operations,certain conditions should be created through some medifications of the collectors. Based on that ,the authors suggest that a precharger electro-cyclone technique be applied to improve the performance of common cyclones still widely used in many places. And a preliminary semi-industrial test has been carried out at Jiawang Power Station, Xuzhou, Jiangsu Province, and the results show that the modified cyclone increases its efficiency from about 80% to 92~94%.

A comparative study of dust control practices in Chinese and Australian longwall coal mines

Mine dust is one of the main hazards in underground longwall mines worldwide.In order to solve the mine dust problem,a significant number of studies have been carried out regarding longwall mine dust control,both in China and Australia.This paper presents a comparative study of dust control practices in Chinese and Australian longwall mines,with particular references to statutory limits,dust monitoring methods and dust management practices,followed by a brief discussion on the research status of longwall mine dust control in both countries.The study shows that water infusion,face ventilation controls,water sprays,and deep and wet cutting in longwall shearer operations are commonly practiced in almost all underground longwall mines and that both Chinese and Australian longwall mine dust control practices have their own advantages and disadvantages.It is concluded that there is a need for further development and innovative design of more effective dust mitigation products or systems despite the development of various dust control technologies.Based on the examinations and discussions,the authors have made some recommendations for further research and development in dust control in longwall mines.It is hoped that this comparative study will provide beneficial guidance for scholars and engineers who are engaging in longwall mine dust control research and practice.

Fly Ash Resistivity Profiling for South African Coal Fired Power Stations

Particulate emission is a major problem in industrial processes, mainly power plants that make use of coal as a primary source of energy. Stringent emissions limits, set by government organisations requires industries to conform to these limits to ensure that air quality is sustained and with minimum pollutant present. Electrostatic precipitators are typically used to filter and collect these particulate emissions. Fly ash resistivity is a primary parameter in the collection of particulate emissions, and there is a resistivity range at which electrostatic precipitator collection is most efficient and anything outside this range limits, their operation. High resistivity ash results in back-corona discharge, whilst low resistivity results in particle re-entrainment into the flue gas stream. The purpose of this paper is to investigate and obtain a fly ash resistivity profile for existing power plants in South Africa. Ash samples obtained from power plants are, tested making use of an ash-resistivity test oven, in accordance with IEEE Standard 548-1984. This paper discusses obtained experimental results, to determine the resistivity profile at which South African power plant electrostatic precipitators operate. The electrical efficiency of the electrostatic precipitator system is evaluated based on the obtained resistivity profiles.