钛制设备在焦化行业中的应用

介绍焦化行业钛设备的应用,剖析了分块式钛泡罩塔盘的结构特点,并对其经济性作了分析。     

Destabilising persistent coal froth using silicone oil

Persistent froth is becoming more and more common in coal and mineral flotation plants and presents safety and operational challenges. No effective method has been developed to destabilise persistent froth. As a new initiative, this study examined the structural difference between persistent foam and coal froth, based on which a solution was developed to maximumly destabilise coal froth. Destabilisation test, oscillatory rheology measurement and scanning electron microscopy (SEM) analysis indicated that the coal froth was more stable than the foam due to the formation of thin capillaries and tightly arranged coal particles on bubble surfaces. Although 107 µm silicone oil droplet could completely destabilise the foam at 2 mmol/L concentration, it only destabilised less than 50% coal froth even at 6 mmol/L concentration. To maximumly destabilise the coal froth formed by −38 and −20 µm particles, 24 and 18 µm silicone oil droplets were required to pass through the thin capillaries and enter the bubble films, respectively. However, smaller silicone oil droplets could not bridge the bubble films to destabilise coal froth and therefore a critical droplet size occurred depending on the size of particles stabilising the froth.     

PRESSURE DISTRIBUTION IN THE AIR-SPARGED HYDROCYCLONE

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Flow field in air-sparged hydrocyclone

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Modelling Gas Holdup in Flotation Column Froths

A one‐dimensional steady‐state model is developed for the prediction of axial variation of the gas holdup in flotation column froths. Froth is considered as an inverse fluidized bed of bubbles and hence the frictional pressure gradient is obtained based on the energy balance. Pressure gradient can also be obtained from the Ergun equation with adjustable constants. The model correctly captures the effect of superficial gas velocity, superficial liquid velocity and bubble diameter on the variation of the gas holdup along the froth height. The predictions of the model are in agreement with the experimental data from the literature.     

Clustering-driven watershed adaptive segmentation of bubble image

In order to extract froth morphological feature, a bubble image adaptive segmentation method was proposed. Considering the image’s low contrast and weak froth edges, froth image was coarsely segmented by using fuzzy c means (FCM) algorithm. Through the attributes of size and shape pattern spectrum, the optimal morphological structuring element was determined. According to the optimal parameters, some image noises were removed with an improved area opening and closing by reconstruction operation, which consist of image regional markers, and the bubbles were finely separated from each other by watershed transform. The experimental results show that the structural element can be determined adaptively by shape and size pattern spectrum, and the froth image is segmented accurately. Compared with other froth image segmentation method, the proposed method achieves much high accuracy, based on which, the bubble size and shape features are extracted effectively.     

Nanobubble generation and its applications in froth flotation (part Ⅲ): specially designed laboratory scale column flotation of phosphate

Froth flotation is used widely for upgrading raw phosphate. The flotation recovery of coarse phosphate (-1.18+0.425 mm) is much lower than that achieved on the -0.425+0.15 mm size fraction. Enhanced recovery of coarse phosphate particles is of great economic and environmental importance for phosphate industry. In this investigation, four different phosphate samples were aquired, characterized and tested in a specially designed laboratory-scale flotation column. Significant recovery improvement of coarse phosphate flotation was achieved using cavitation-generated nanobubble though its effects differ among the four testing phosphate samples. The laboratory-scale flotation column test results indicate that nanobubble increased P2O5 recovery by up to 10%-30% for a given Acid Insoluble (A.I.) rejection, depending on the characteristic of phosphate samples. The improvement ef-fect of nanobubble on the hard-to-float particles was more significant than that on easy-to-float particles, especially at lower col-lector dosages. Nanobubbles reduced the collector dosage by 1/3 to 1/2. Nanobubbles almost doubled the coarse phosphate flotation rate constant and increased the flotation selectivity index by up to 25%.     

Surface chemical study of the selective separation of chalcopyrite and marmatite

FCLS (Ferric Chromium Lignin Sulfonate) was used to aid the separation of chalcopyrite from marmatite. Flotation, adsorption and zeta-potential tests of treated marmatite and chalcopyrite were performed. The flotation of marmatite was strongly depressed, while that of chalcopyrite was only slightly depressed, over a wide range of pH values when FCLS was used as depressant in the presence of Butyl Xanthate (BX). The adsorption of BX onto chalcopyrite or marmatite takes place over a wide pH range. The adsorption density of BX on chalcopyrite and marmatite decreases as the pH increases. The adsorption density of FCLS onto marmatite is greater than the adsorption density onto chalcopyrite. The zeta potentials of chalcopyrite and marmatite become more negative due to the addition of xanthate and FCLS.     

基于VC＋＋6．0的浮选泡沫图像识别系统

浮选生产过程涉及许多变量以及存在严重的非线性,很难建立精确的数学模型,它的监控一直是困扰控制技术人员的难题。文中设计开发了一个用于选厂自动控制的浮选泡沫图像识别系统，并给出该系统VisualC 6．0的部分实现。利用该系统可以计算浮选泡沫图像的一些物理参数，通过这些物理参数以及浮选泡沫图像识别实验可以建立一定的数学模型，再通过这些数学模型可以精确预测浮选过程的工艺技术指标,从而为选厂过程的在线控制提供可靠数据依据。     

N-[(3-二甲氨基)丙基]-脂肪酸酰胺泡沫浮选一水硬铝石的研究

研究了N-[(3-二甲氨基)丙基]-脂肪酸酰胺对一水硬铝石(Al2O3·H2O)的泡沫浮选行为.结果表明,使用该捕收剂,一水硬铝石的回收率最高达99.7％以上.在等电点附近一水硬铝石的回收率最高.碱性条件下,一水硬铝石的回收率急剧下降.增加N-[(3-二甲氨基)丙基]-脂肪酸酰胺的用量,可有效地提高一水硬铝石的回收率.通过测定矿物的Zeta电位,表明一水硬铝石的等电点(IEP)大约为6.2.根据矿物的红外吸收光谱和Zeta电位,讨论了表面吸咐机理,认为N-[(3-二甲氨基)丙基]-脂肪酸酰胺主要通过静电力和氢键的方式吸咐在矿粒表面.