Influence of surface roughness on flotation kinetics of quartz

Surface roughness of quartz particles was determined by measuring the specific surface area of particles. The wettability characteristics of particles were determined by measuring the flotation rate using a laboratory flotation cell. Experimental results show that the rod mill product has higher roughness than the ball mill product. For the particles with larger surface roughness, the flotation kinetics constant is also higher. Finally, empirical relationships between surface roughness (r) and the flotation kinetics constant (k) of quartz particles as k=A+Br+Cr ^0.5lnr+D/lnr+E/r and k=A+Br are presented, in which A, B, C, D and E are constants related to experimental conditions and mineralogical properties of mineral.     

Mechanism of separating muscovite and quartz by flotation

Flotation experiments were performed to investigate the separation of muscovite and quartz in the presence of dodecylamine（DDA）, tallow amine（TTA） and dodecyltrimethylammonium bromide（DTAC）. The adsorption mechanisms of these three kinds of amines on muscovite and quartz were studied by FT-IR spectrum analysis, contact angle measurement and molecular dynamics（MD） simulation. The results reveal that the separation of muscovite from quartz is feasible at strong acid pulp condition using amine collectors. TTA and DTAC show poorer collecting ability for flotation of the two minerals compared with DDA. Physical adsorption is found to be the main adsorption module of amine collectors on muscovite and quartz by FT-IR analysis. MD simulation results show a strong physical adsorption ability of DDA＋ cation on muscovite and quartz（muscovite（001）：-117.31 kJ/mol, quartz（100）：-89.43 kJ/mol）, while neutral DDA molecular can hardly absorb onto the surface of these two minerals. These findings provide a novel explanation for the flotation mechanism from the perspective of MD simulation.     

Alkaline treatment kinetics of calcium phosphate by piezoelectric quartz crystal impedance

Calcium phosphate film was prepared by electrochemical deposition technology. Subsequently, the alkaline treatment process of calcium phosphate film in 0.1 mol/L NaOH solution was monitored on real time by the piezoelectric quartz crystal impedance (PQCI) technique. The variations of morphology and composition for the alkaline treatment products were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) and X-ray diffraction (XRD), respectively. The dynamic variations of calcium phosphate can be characterized by the change of equivalent circuit parameters. The results show that the forming process of hydroxyapatite (HA) is composed of three stages: (1) acidic calcium phosphate dissolution; (2) phase transformation; and (3) HA formation. Furthermore, the correlative kinetic equations and parameters are obtained by fitting the static capacitance (C _s)—time curves. Foundation item: Project(2005CB623901) supported by the Major State Basic Research and Development Program of China     

Effects of nanobubble and hydrodynamic parameters on coarse quartz flotation

Quartz, the second most abundant mineral in the earth's crust, is a gangue mineral in practically every flotation process. Coarse quartz flotation has been a long standing problem in various mineral processing plants to reduce milling cost and increase valuable mineral recovery. Based on this, the effects of nanobubbles(NBs) and hydrodynamic parameters on coarse quartz particle flotation were systematically investigated. Mechanical flotation experiments were carried out using the 7 cm and 9 cm diameter impellers in order to produce different hydrodynamic conditions. 900–1300 rpm impeller speeds were used for the 7 cm diameter impeller and 554–786 rpm for the 9 cm diameter impeller. The results show that the presence of NBs increased the flotation recovery of à425 + 106 lm quartz by up to 21%. For the7 cm diameter impeller, the maximum flotation recoveries of 86.4% and 98% were obtained in the absence and presence of NBs at Reynolds number(Re) of 81,000 and 66,000, respectively. For the 9 cm diameter impeller, the maximum recoveries of 86.3% and 97.5% were obtained in the absence and presence of NBs at Re of 90,000 and 75,000, respectively. NBs increased the flotation rate constant up to 36%.     

Study on interaction energy between flotation reagent and mineral surface

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Existence and release of fluid inclusions in bornite and its associated quartz and calcite

The existence and release of fluid inclusions in bornite and its associated minerals, namely, quartz and calcite were investigated and confirmed. The structures, forms, and phases of these large quantities of fluid inclusions were also studied. A mass of fluid inclusions with various sizes, distributions, shapes, and phases exist in bornite and its associated minerals. Their sizes vary from a few micrometers to tens of micrometers, and the forms appear as negative crystals, or elongated, elliptical, and irregular. At room temperature, fluid inclusions were mainly characterized as gas-liquid two- phase. However, small amounts of fluid inclusions with pure gas phase and pure liquid single-phase were also observed in quartz and calcite. These fluid inclusions initially broke during the ore crushing and grinding process and then released into the flotation pulp in the flotation process. The quantitative analysis of fluid inclusions in the solution and the comparisons of mineral dissolution show that the amount of copper and iron released by fluid inclusions in the bornite sample is higher than the amount dissolved by the mineral; fluid inclusions in the associated gangue minerals, quartz, and calcite also make contribution.     

Nano-microbubble flotation of fine and ultrafine chalcopyrite particles

As is well known to mineral processing scientists and engineers, fine and ultrafine particles are difficult to float mainly due to the low bubble-particle collision efficiencies. Though many efforts have been made to improve flotation performance of fine and ultrafine particles, there is still much more to be done. In this paper, the effects of nano-microbubbles (nanobubbles and microbubbles) on the flotation of fine (−38 + 14.36 μm) and ultrafine (−14.36 + 5 μm) chalcopyrite particles were investigated in a laboratory scale Denver flotation cell. Nano-microbubbles were generated using a specially-designed nano-microbubble generator based on the cavitation phenomenon in Venturi tubes. In order to better understand the mechanisms of nano-microbubble enhanced froth flotation of fine and ultrafine chalcopyrite particles, the nano-microbubble size distribution, stability and the effect of frother concentration on nanobubble size were also studied by a laser diffraction method. Comparative flotation tests were performed in the presence and absence of nano-microbubbles to evaluate their impact on the fine and ultrafine chalcopyrite particle flotation recovery. According to the results, the mean size of nano-microbubbles increased over time, and decreased with increase of frother concentration. The laboratory-scale flotation test results indicated that flotation recovery of chalcopyrite fine and ultrafine particles increased by approximately 16–21% in the presence of nano-microbubbles, depending on operating conditions of the process. The presence of nano-microbubbles increased the recovery of ultrafine particles (−14.36 + 5 μm) more than that of fine particles (−38 + 14.36 μm). Another major advantage is that the use of nano-microbubbles reduced the collector and frother consumptions by up to 75% and 50%, respectively.     

基于Origin的表面粗糙度参数的计算机评定

介绍了国家标准中表面粗糙度的主要评定参数,利用Origin软件实现了表面粗糙度参数的计算,并用实例验证了计算的有效性,这种计算机评定方法简单、易操作,不仅在教学而且在实际生产中也有一定的推广价值。     

乙醛废水生物处理动力学的研究

在加压条件下测定了乙醛废水的动力学参数 ,建立了废水生物处理动力学模型 ,为乙醛废水处理装置的工业化设计提供了设计参数     

振动对车削表面粗糙度的影响

本文提出了产生振动时,车削表面粗糙度的理论计算方法,导出了产生振动时表面粗糙度计算公式,并进行了相应的讨论。     

衬底材质及表面粗糙度对SnO2薄膜结构的影响

SnO2透明导电膜的光学、电学特性与它的结构密切相关，研究了衬底材质及表面粗糙度对薄膜结构的影响。结果表明：衬底材质影响薄膜晶粒大小、致密度及优势面；表面粗糙度影响薄膜结晶难易程度和致密度。     

金刚石线锯加工表面粗糙度的建模与预测

视线锯的磨粒为圆锥状,考虑磨粒突起高度为正态分布,同时用截断高斯分布模型表示线锯的磨损,根据线锯和工件的相对运动,给出了粗糙度的理论模型和预测方法.此方法通过求得不同突起高度的磨粒残留痕迹的交点,得到加工工件的最终轮廓,从而得到表面粗糙度.实验证明,此方法所得表面粗糙度与实测的表面粗糙度一致.     

金刚石线锯加工表面粗糙度的建模与预测

视线锯的磨粒为圆锥状，考虑磨粒突起高度为正态分布，同时用截断高斯分布模型表示线锯的磨损，根据线锯和工件的相对运动，给出了粗糙度的理论模型和预测方法．此方法通过求得不同突起高度的磨粒残留痕迹的交点，得到加工工件的最终轮廓，从而得到表面粗糙度．实验证明，此方法所得表面粗糙度与实测的表面粗糙度一致。     

A Series Piezoelectric Quartz Crystal Response Kinetics for T.ferrooxidans Growth in the Presence of Cu(Ⅱ)

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Insights into the influence of temperature on the adsorption behavior of sodium oleate and its response to flotation of quartz

Temperature affects the flotation of quartz in the calcium/sodium oleate(NaOL)system,while there is a lack of understanding of its potential mechanism.Therefore...     

Prediction of operational parameters effect on coal flotation using artificial neural network

Artificial neural network procedures were used to predict the combustible value (i.e. 100-Ash) and combustible recovery of coal flotation concentrate in different operational conditions. The pulp density, pH, rotation rate, coal particle size, dosage of collector, frother and conditioner were used as inputs to the network. Feed-forward artificial neural networks with 5-30-2-1 and 7-10-3-1 arrangements were capable to estimate the combustible value and combustible recovery of coal flotation concentrate respectively as the outputs. Quite satisfactory correlations of 1 and 0.91 in training and testing stages for combustible value and of 1 and 0.95 in training and testing stages for combustible recovery prediction were achieved. The proposed neural network models can be used to determine the most advantageous operational conditions for the expected concentrate assay and recovery in the coal flotation process.     

Al-Al2O3-Ni隧道结中的表面粗糙度效应

用真空蒸发镀膜法在光滑的玻璃基片和粗糙的CaF2薄膜表面上制备了Al-Al2O3-Ni隧道结，观测了CaF2薄膜的表面粗糙度对隧道结伏安特性的影响，首次观测到这种界面粗糙结的光发射．采用梯形势垒模型计算伏安特性，并与实验伏安特性拟合，得到了结的有效势垒参数．结果表明，与界面光滑的结比较，界面粗糙的结的有效势垒宽度较窄，有效势垒面积较小．这可归因为在粗糙的Al2O3表面投射式的沉积Ni原子时，在Al2O3-Ni界面留下了空隙．同时分析了结的发光机理，讨论了影响发光效率的因素．     

新型对接棱台状FPSO的浮体参数和水动力分析

为解决传统船型和棱柱筒状FPSO的性能局限,提出一种具有对接棱台状浮式主体的新概念FPSO.根据所研发的新型对接棱台状浮体模型,确定了能够反映浮体几何形状、FPSO基本功能和水动力性能的5个相互独立的外形参数.然后,采用基于频域势流理论的边界元数值模拟方法研究了新型对接棱台状浮体在波浪中的运动响应,并且定性分析了不同浮体外形参数(下倾角、水线面外接圆半径等)对浮体水动力性能的影响.最后,根据频域势流理论和工程近似方法,分析并概括出基于垂荡运动性能的新型浮体设计准则和方案.在此基础上,结合某棱柱型FPSO的基本功能(载重量、排水量、储油空间、上甲板面积的设计值),完成新型FPSO的主浮体设计.通过性能比较,证明了对接棱台状FPSO的水动力性能优势和设计方案有效合理性,以期能够为深水油气开发提供一种有效的新型工程装备和解决方案.     

工程地表面不平度测量系统设计

为实现工程地表面不平度的智能测量,提出了一种自动化、智能化的工程地表面不平度测量系统,并对系统关键技术进行了详细描述。该系统采用了独特设计的光学传感器和先进的自动化技术,并采用高速数字信号处理器(DSP)、支持热插拔的通用串行总线(USB)以及可编程的CPLD器件。本系统通过测试并达到了预期的目的,为灵活方便地测量工程地表面、评定工程地表面的级别提供了一种可靠的工具,具有非常实用的使用和推广价值。     

颗粒尺寸与药剂性质对胶磷矿浮选过程的影响

通过磷矿颗粒的分级浮选、药剂对比及组合浮选对湖北保康钙质磷矿和大峪口硅钙质磷矿进行了系统研究.结果表明:分级后粒径为-65μm的小颗粒磷矿更有利于反浮选,且保康磷矿反浮选效果优于大峪口磷矿;复合药剂和酸性抑制剂均能改善保康钙质磷矿浮选效果,最终磷精矿品位达到36.14%,磷回收率为96.10%;药剂表面张力降低能增强药剂对磷矿颗粒的湿润.最后,通过测量电动电位和亲水亲油平衡值,对浮选过程效率进行了分析,并对浮选机理进行了讨论.