纳米泡提高细粒煤浮选效果的研究

泡沫浮选槽中微细粒级低效浮选的原因是颗粒与气泡的碰撞概率低,而粗颗粒浮选回收差的原因是大量颗粒从气泡上脱落,采用文丘里管产生纳米泡,研究了利用纳米泡提高细粒煤浮选效果的机理,结果表明:纳米泡浮选过程中,纳米泡会优先聚集在疏水性颗粒表面,通过调整给料速度、捕收剂添加量等浮选条件,可燃体回收率提高10%～30%,纳米泡起到了辅助捕收的作用,并可以减少药剂用量1/3～1/2.     

有机抑制剂对微细粒锡石可浮性的影响

通过系列微浮选试验研究了柠檬酸、羧甲基纤维素钠、木质素磺酸钙和淀粉等4种有机抑制剂对油酸钠体系中微细粒锡石可浮性的影响.在pH=8,油酸钠质量浓度为80mg/L条件下,5~20μm粒级锡石浮选回收率为92.50%;pH=8时,柠檬酸、羧甲基纤维素钠、木质素磺酸钙和淀粉的最佳质量浓度分别为20,10,20,80mg/L,分别使锡石回收率降低了17.92,24.44,10.65,32.42个百分点.浮选溶液化学分析、动电位检测及接触角测量结果显示:油酸钠在锡石表面的吸附作用以化学吸附为主;柠檬酸与锡石发生螯合反应而化学吸附于锡石表面,促进其表面亲水薄膜生成,并占据活性位点阻碍油酸钠吸附,从而实现对锡石的抑制作用.     

煤泥浮选过程中粒度对泡沫性质的影响

针对复杂的三相浮选泡沫,探索了不同粒度煤炭颗粒在浮选过程中产率和灰分的变化规律及其对浮选泡沫性质的影响.将煤炭浮选入料分为粗(500～250μm)、中(250～74同的情况下μ,m)、细(-74μm)3个粒级分别进行单独和混合浮选,在入料性质不同而操作条件相分析各粒级煤炭的浮选精煤产率和灰分,以及相应的浮选泡沫性质,包括水回收率、均一性(气泡尺寸)、破裂气泡尺寸、破裂气泡个数和泡沫速度等.结果表明:粗颗粒的浮选精煤产率明显受到细颗粒的影响,加入细颗粒后产率从30%升高到60%,但粗颗粒精煤灰分基本不变;细颗粒的浮选产率独立性好,基本不受粗颗粒和中颗粒的影响,但细颗粒精煤灰分随粗颗粒和中颗粒的加入而升高.通过对浮选泡沫性质的分析,发现粗颗粒促使气泡破裂并破坏泡沫的稳定性,中颗粒能够显著提高泡沫速度,而细颗粒能够增强泡沫稳定性并且降低泡沫速度.当浮选入料性质,即颗粒粒度改变时,各浮选泡沫性质与精煤灰分的相关性规律与入料性质不变而操作条件改变的常规浮选不同,主要是由不同粒度颗粒的特性差异所导致.     

煤泥浮选过程中粒度对泡沫性质的影响

针对复杂的三相浮选泡沫,探索了不同粒度煤炭颗粒在浮选过程中产率和灰分的变化规律及其对浮选泡沫性质的影响.将煤炭浮选入料分为粗(500～250μm)、中(250～74μm)、细(-74μm)3个粒级分别进行单独和混合浮选,在入料性质不同而操作条件相同的情况下,分析各粒级煤炭的浮选精煤产率和灰分,以及相应的浮选泡沫性质,包括水回收率、均一性(气泡尺寸)、破裂气泡尺寸、破裂气泡个数和泡沫速度等.结果表明:粗颗粒的浮选精煤产率明显受到细颗粒的影响,加入细颗粒后产率从30%升高到60%,但粗颗粒精煤灰分基本不变;细颗粒的浮选产率独立性好,基本不受粗颗粒和中颗粒的影响,但细颗粒精煤灰分随粗颗粒和中颗粒的加入而升高.通过对浮选泡沫性质的分析,发现粗颗粒促使气泡破裂并破坏泡沫的稳定性,中颗粒能够显著提高泡沫速度,而细颗粒能够增强泡沫稳定性并且降低泡沫速度.当浮选入料性质,即颗粒粒度改变时,各浮选泡沫性质与精煤灰分的相关性规律与入料性质不变而操作条件改变的常规浮选不同,主要是由不同粒度颗粒的特性差异所导致.     

煤泥浮选过程中粒度对泡沫性质的影响

针对复杂的三相浮选泡沫,探索了不同粒度煤炭颗粒在浮选过程中产率和灰分的变化规律及其对浮选泡沫性质的影响.将煤炭浮选入料分为粗(500～250μm)、中(250～74同的情况下μ,m)、细(-74μm)3个粒级分别进行单独和混合浮选,在入料性质不同而操作条件相分析各粒级煤炭的浮选精煤产率和灰分,以及相应的浮选泡沫性质,包括水回收率、均一性(气泡尺寸)、破裂气泡尺寸、破裂气泡个数和泡沫速度等.结果表明:粗颗粒的浮选精煤产率明显受到细颗粒的影响,加入细颗粒后产率从30%升高到60%,但粗颗粒精煤灰分基本不变;细颗粒的浮选产率独立性好,基本不受粗颗粒和中颗粒的影响,但细颗粒精煤灰分随粗颗粒和中颗粒的加入而升高.通过对浮选泡沫性质的分析,发现粗颗粒促使气泡破裂并破坏泡沫的稳定性,中颗粒能够显著提高泡沫速度,而细颗粒能够增强泡沫稳定性并且降低泡沫速度.当浮选入料性质,即颗粒粒度改变时,各浮选泡沫性质与精煤灰分的相关性规律与入料性质不变而操作条件改变的常规浮选不同,主要是由不同粒度颗粒的特性差异所导致.     

微细粒锂辉石矿浆流变性特征及对浮选的影响

在锂辉石选矿过程中,易产生较多的微细粒锂辉石与长石.微细粒矿物在浮选过程中易发生非选择性吸附与聚集,并形成一定的网状结构,使得矿浆流变性发生改变,从而影响锂辉石矿物的浮选效果.为了充分了解微细粒锂辉石矿浆流变性特征及对浮选的影响,采用流变特性测试、浮选试验、表面动电位测试和EDLVO理论计算的方法进行系列试验.结果表明：矿物粒度的减小,会提高流体屈服应力与黏度值,在一定粒度范围内恶化锂辉石、长石的浮选效果;长石质量分数的增加提高了微细粒锂辉石矿浆流体的屈服应力与黏度值,导致锂辉石回收率下降,影响微细粒锂辉石浮选效果;通过添加六偏磷酸钠,可以增大微细粒锂辉石、长石颗粒的表面电负性,增强微细粒锂辉石、长石颗粒间的双电层静电作用斥力,降低矿浆体系的黏度与屈服应力,优化流变性能,进而改善了微细粒锂辉石与长石的浮选分离效果,达到优化调控微细粒锂辉石浮选效果的目的.     

微细粒疏水矿物表面微泡强化浮选的作用机理

微泡在微细粒矿物浮选中,体现了较高的回收率和较好的选择性.相比较大气泡而言,微气泡对浮选的显著改善主要是由于气泡-颗粒之间碰撞频率和附着概率的增加.研究结果表明：矿物表面的微气泡,即已经附着在颗粒上的气泡,可增加浮选回收率;细辉钼矿颗粒(D₅₀=21.8μm)的微泡浮选试验表明,通过流体空化产生的表面微泡可以实现更高的回收率.辉钼矿可浮性的提高主要原因是：矿物表面微泡引起的颗粒团聚和颗粒与浮选气泡之间的诱导时间减少.Zeta电位分布的分析表明微泡在矿物颗粒表面空化.经光学显微镜观察,发现矿物颗粒是通过表面微泡形成团聚.通过动态力装置(Dynamic Force Apparatus, DFA)观测到了表面微泡和浮选气泡之间液膜的快速排液过程.本文拓展了微细粒浮选中表面微泡的理论深度,对实际生产具有一定的指导意义.     

多孔电极的制备及其在煤岩显微组分电浮选分离中的应用

为了提升煤岩显微组分的电浮选分离效果,采用氢气泡模板法在镍和铜电极表面进行了微孔构筑.采用扫描电子显微镜、接触角测量和气泡在线分析系统研究了电极表面孔结构和润湿性对电解氢气泡尺寸、浓度及上浮速度等的影响;在H型电浮选柱反应器中,以神府高惰质组烟煤为对象,考察了电解气泡特征对煤显微组分电浮选分离效果的影响规律.结果表明：经电沉积处理后,电极材料表面可形成孔径在3～70μm之间的间隙结构,且亲水性显著增强,电解时的氢气泡尺寸更小、浓度更高、上升速率更快.调控电沉积反应时间,可实现电解氢气泡尺寸在8～88μm、气泡浓度在13.75～44.85 cm³/cm³之间的调变,进而可控制神府煤岩显微组分的电浮选分离效果;当沉积时间为60 s时,煤岩显微组分电浮选分离的上浮物回收率为64.8%,浮物中镜质组富集率可达95.5%,下沉物回收率为35.2%,沉物中惰质组富集率达到92.9%.电浮选煤浆体系制氢效率更高,与纯水电解制氢相比,煤浆电浮选体系的制氢能耗可降低20.59%,氢气收率增加12.88%.     

基于胶磷矿反浮选过程粒级变化特征的分步浮选研究

为进一步提高胶磷矿反浮选的全粒级回收效果,研究了工业生产过程的粒级变化特征、循环压力及充气量对主要适配参数气泡尺寸的影响,开展了胶磷矿分步浮选半工业试验并对产品进行了分析.基于粒度对于矿化过程的重要影响,提出了与浮选过程粒级变化特征相适配的分步强化思路.结果表明:反浮选过程中细颗粒优先浮出,粗颗粒后期浮出;分步浮选前期应提高循环压力、充气量,后期与之相反;与常规系统相比,精矿回收率提高了1.88个百分点,捕收剂、抑制剂用量分别降低了14%和10%,表明通过粗、细颗粒的分步浮选强化可有效提高浮选效果.     

微泡浮选柱选煤技术

分析了微泡浮选柱的理论基础，气泡大小与浮选速率的关系，气泡大小对生产能力的影响．另外还介绍了实验室、半工业和工业生产规模微泡浮选柱的分选效果．很显然，减小气泡直径是改善超细粒物料回收率和取得最大处理能力的关键因素     

Investigation of condition-induced bubble size and distribution in electroflotation using a high-speed camera

In the flotation process, bubble is a key factor in studying bubble-particle interaction and fine particle flotation. Knowledge on size distribution of bubbles in a flotation system is highly important. In this study, bubble distributions in different reagent concentrations, electrolyte concentrations, cathode apertures, and current densities in electroflotation are determined using a high-speed camera. Average bubble sizes under different conditions are calculated using Image-Pro® Plus (Media Cybernetics®, MD, USA) and SigmaScan® Pro (Systat Software, CA, USA) software. Results indicate that the average sizes of bubbles, which were generated through 38, 50, 74, 150, 250, 420, and 1000 μm cathode apertures, are 20.2, 29.5, 44.6, 59.2, 68.7, 78.5, and 88.8 μm, respectively. The optimal current density in electroflotation is 20 A/m². Reagent and electrolyte concentrations, current density, and cathode aperture are important factors in controlling bubble size and nucleation. These factors also contribute to the control of fine-particle flotation.     

A novel quantificational assessment method of frothers effect on bubble characteristics

A new visual method for quantitative measurement of frothers effect and flotation efficiency was presented. A self-designed electrolytic cell was chosen as the reaction environment with sodium chloride (NaCl) as the electrolyte. Constant current, supplied by a self-designed power supplier and fixed cathode and anode equipment, guaranteed the constant bubble volume per unit time. Even aperture of the cathode material guaranteed the original bubbles size to be uniform. Bubble generating equipment was connected with a microscopical camera. Statistic data collected by high speed charge-coupled device (CCD) and processed by software Sigmascan and Matlab could reflect bubble characteristics. The efficiency of dipropylene glycol monomethyl ether (DPM) and tripropylene glycol n-butyl ethel (TPnB) were measured at the same condition, and 2×10⁻⁴ mol/L and 5×10⁻² mol/L were found to be the inflexions of bubble size changes.     

Interactions between bubble and particles of key minerals of diasporic bauxite through the extended DLVO theory

The flotation of diasporic bauxite is to separate diaspore (valuable mineral) from aluminosilicate minerals (gangue minerals, mainly including kaolinite, illite and pyrophyllite), and the microscopic interaction force between the two types of minerals and air bubbles determines the separation efficiency. In this paper, based on the extended Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, the van der Waals, electrostatic and hydrophobic interaction between particles of the four minerals mentioned above and air bubbles in collectorless solution were calculated first, and then diaspore and kaolinite were taken as examples to analyze the influence of various factors such as electrolyte concentration, mineral particle size, air bubble size, collector type (dodecylamine hydrochloride (DAH) and sodium oleate (NaOL)) and concentration, and pulp pH on the interactions between the particles of valuable mineral and gangue minerals and air bubbles. The results showed that the total extended DLVO interactions between the four minerals and air bubbles were repulsive in most cases in collectorless solution. The increase in electrolyte concentration reduced the interaction force or even changed the direction of the force under certain circumstances. The addition of DAH and NaOL can reduce the adhesion energy barrier of kaolinite-bubble and diaspore-bubble respectively. Each type of minerals exhibited a specific interface interaction response with air bubbles in each collector with different pH values. The research results have theoretical guiding significance for the optimization and directional control of diasporic bauxite flotation conditions.     

Flotation and adsorption of quaternary ammonium salts collectors on kaolinite of different particle size

The flotation behaviors of decyltrimethylammonium (103C), dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC) and cetyltrimethylammonium chloride (CTAC) on kaolinite of different particle size fraction were studied. The adsorbed amount and adsorption isotherms of collectors on kaolinite were determined for painstaking investigation into the adsorption of quaternary amines at kaolinite–water interface by ultraviolet spectrophotometer methods. The flotation results show that the flotation recovery of kaolinite of different particle fraction increases with an increase in pH when 103C, DTAC, TTAC and CTAC are used as collectors. As the concentration of collectors increases, the flotation recovery increases. Particle size of kaolinite has a strong effect on flotation. The flotation recovery of fine kaolinite decreases with the carbon chain of quaternary ammonium salts collectors increasing, while coarse kaolinite is on the contrary. The adsorbed amount tests and adsorption isotherms show that adsorbed amount increases when the particle size of kaolinite increases or when the carbon chain length of quaternary ammonium salts increases. Within the range of flotation collector concentration, the longer the hydrocarbon chain, the more probable to be absolutely adsorbed by fine kaolinite particles and then the lower the collector concentration in the bulk, which leds to lower flotation recovery.     

碳酸根对方解石浮选速率的影响及机理研究

通过方解石单矿物浮选试验,研究了不同浓度碳酸根离子以及矿浆pH值对方解石浮选速率的影响,结果表明:加入1.5mmol/L碳酸根离子时,方解石完全上浮的时间由原来的2min缩短至30s,浮选速率显著提高,而pH值对其浮选速率无显著影响.利用ζ-电位测定、溶液化学计算以及颗粒间相互作用原理,探讨了碳酸根离子影响方解石浮选速率的作用机理,结果表明:碳酸根离子在方解石表面发生静电吸附,生成碳酸钙沉淀,中和了颗粒表面电性,方解石颗粒间的静电排斥力减小,颗粒间的两种吸引力即范德华作用力和疏水作用力占主导地位,颗粒相互吸引靠拢产生聚沉,颗粒更易于向气泡附着,使得方解石浮选速率显著提高.     

Bubble size measurement in three-phase system using photograph technology

A special experiment setup was designed to observe the interaction between bubbles and particle in flotation cell and to analyze the bubble characteristics such as bubble size, distribution and bubble-loading efficiency. Bubbles in water-gas system and three-phase system were measured. The results indicate that with the current setup the bubbles as small as 10μm can be easily distinguished. The average size of the bubbles generated under the given conditions in two-phase system is 410μm at frother concentration of 0. 004%, which is in good correspondence with the results of other works. The effect of frother on bubble size was probed. Increasing frother concentration from 0 to 0. 004% causes a reduction of bubble size from 700 to 400μm. The bubble loading efficiency was reported. The result indicates that the fine particle is more easily entrapped than the coarse particle. Some factors, which have effect on measurement accuracy were discussed. The aeration speed has a significant effect on the accuracy of results, if it surpasses 30 mL/s, and the image becomes unclear due to the entrapment of fine particle. Another factor, which can affect observing results, is the sampling position. At a wrong sampling position, the images become unclear.     

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.     

矿物浮选过程的耗散结构分析

利用耗散结构理论分析了矿物浮选过程热力学和动力学特征．结果表明，进行浮选的矿浆体系是一个开放系统，矿浆处于湍流状态，系统的熵较大．随着浮选药剂和空气的不断输入，系统从环境吸入负熵流，悬浮矿粒与浮选药剂作用，使系统的熵降低，最后稳定在新的有序状态，形成耗散结构，有利于提高矿物回收率．以回收某镍尾矿为例，由于层流态的浮选柱有效泡沫层厚，底部的旋流力场赋予颗粒动能，能够容易地克服颗粒与气泡间的能垒，形成耗散结构．与浮选机相比，利用浮选柱回收的镍尾矿精矿品位提高0．29％，回收率提高3．02％．     

几种煤用浮选剂的比较

在1.5升的实验室浮选机中研究了五种浮选剂对攀枝花煤的浮选效果,以及淀粉添加剂,pH、原煤粒度、浮选时间等对浮选的影响。     

Investigation of different coal types effect on the overall plant recovery

Coal washing plants are usually fed from various sources. Coals include different combinations which should be considered for increasing the plant proficiency. Thus different methods have been used to enrich various coal types. In this study, Alborz-Sharghi coal washing plant was investigated which is fed from five coalmines. The optimum recovery was achieved for all coal types individually through experimental design. The controllable operation parameters in the experiments were collector dosage, frother dosage, solid percent content and particle size. The other parameters such as impeller speed, pH, conditioning time and flotation time were kept constant for all experiments. The optimum combination of coals was also specified. The results show that the optimum recovery for coal blends is 91.2% which shows much improvement relative to the plant conditions.