Effects of frothers on bubbles size and flotation performance of hydrophobic minerals

Frothers facilitate the reduction of bubbles size by preventing bubbles coalescence and produce more stable froths.The collision probability of the bubbles and particles substantially increases by decreasing bubble size.For the same volume system,fewer bubbles result from a distribution of large-sized bubbles,and more bubbles result from a distribution of small-sized bubbles.In this research,fundamental two-phase frother characterization parameters were aimed to link with three-phase coal and talc flotation behavior.For this purpose,the effect of single and dual frother systems on inhibiting bubble coalescence was investigated with methyl isobutyl carbinol(MIBC),isooctanol(2 ethyl hexanol),pine oil,and Dowfroth 250.Based on the results of single frothers,isooctanol at the lowest critical coalescence concentration(CCC)value of 6×10^(−6) achieved the smallest bubbles with Sauter mean diameter of 0.80 mm.By blending Dowfroth 250 and pine oil,the bubbles size decreased significantly,reaching 0.45 mm.While the highest recoveries in coal flotation were obtained in single and frother blends where the bubbles size was measured as the smallest in two-phase system,and such a relationship was not found for talc flotation.

Enhanced inhibition of talc flotation using acidified sodium silicate and sodium carboxymethyl cellulose as the combined inhibitor

The flotation separation of chalcopyrite and talc is challenging due to their similar natural floatability characteristics.Besides,it is usually difficult to effectively inhibit talc by adding sodium carboxymethyl cellulose(CMC)alone during chalcopyrite flotation.Here,a combined inhibitor comprising acidified sodium silicate(ASS)and CMC was employed to realize effective flotation separation of chalcopyrite and talc,and the combined inhibition mechanism was further investigated.Microflotation results showed that adding ASS strengthened the inhibitory effect of CMC on talc and improved the separation of chalcopyrite and talc.The zeta potential,Fourier transform infrared,and X-ray photoelectron spectroscopy analysis indicated that CMC was mainly adsorbed on the talc surface via hydroxyl and carboxyl groups.Moreover,the addition of ASS improved the adsorption of carboxyl groups.Furthermore,the adsorption experiments and apparent viscosity measurements revealed that adding ASS dispersed the pulp well,which reduced the apparent viscosity,improved the adsorption amount of CMC on the talc surface,and enhanced the inhibition of talc in chalcopyrite flotation.

Using pectin to separate talc and molybdenite through the surface modification with Cu^(2+):Applications and mechanism

Organic depressants have low selectivity in separating molybdenite and talc because their metal sites lack activity for organics chemisorption.In this study,surface modification by copper sulfate was used to induce the differential adsorption of pectin onto molybdenite and talc surfaces for enhanced flotation separation.Contact-angle experiments,scanning electron microscopy,adsorption measurements,timeof-flight secondary-ion mass spectrometry,and X-ray photoelectron spectroscopy analyses were conducted to reveal the interaction mechanism.Results illustrated that molybdenite and talc could not be separated using pectin alone,while molybdenite was selectively depressed after surface modification by copper sulfate and this effect was strengthened under alkaline conditions.Metal sites(Mg,Si and Mo)of talc and molybdenite themselves were unable to react with pectin,whereas Cu+would deposit and further function as active site for pectin chemisorption after surface modification.However,the quantity of deposited Cu sites dropped on talc surface and increased on molybdenite surface with increased pH,and the Mo atoms of molybdenite crystal were activated to take part in pectin chemisorption.Therefore,more pectin was adhered on molybdenite surface,which imparted molybdenite stronger wettability.Herein,surface-modification through metal ions can enable the differential adsorption of organic depressants and enhance the flotation separation of minerals.

PP/Talc复合材料的非等温结晶动力学

用差示扫描量热法(DSC)研究聚丙烯(PP)及PP/Talc复合材料的非等温结晶过程,加入滑石粉后,PP/Talc的结晶速率、结晶度得到明显提高。结合Avrami和Ozawa方程得出一个适合于非等温的结晶动力学方程,并由此获得PP/Talc复合材料的非等温结晶动力学参数,计算表明Talc能促进PP材料的结晶。

基于Logistic模型对TALC模型各阶段的定量划分——兼论美国十大国家公园的旅游生命周期模式

TALC模型是旅游学界讨论最多的模型之一,在诸多讨论的议题中,关于该模型各阶段的划分和确认一直是一个未能解决的难题。文章基于用Logistic模型解决TALC模型各阶段定量划分的目的,在运用微分知识分析Logistic模型数学性质的基础上,发现了该模型有3个时间节点。然后分析了Logistic模型对TALC模型各阶段的定量划分的适用性,并对美国十大国家公园上百年的时间序列数据进行回归分析,实证了美国十大国家公园的旅游生命周期模式。分析得出:(1)Logistic模型可以很好地拟合TALC模型的前5个阶段,即探查-参与阶段、发展阶段、巩固阶段、停滞阶段;(2)利用Logistic模型求得划分TALC模型的3个时间节点((a-1.317)/r,K/(4.732))、(a/r,K/2)、((a+1.317)/r,K/(1.268));(3)美国国家公园的旅游生命周期模式可以分为3类:Ⅰ型—标准型、Ⅱ型—断崖型、Ⅲ型—跳跃型。研究发现TALC模型各阶段可以进行定量划分和确认,文章得出的3个时间节点就是一次探索性尝试。

H_2O_2环氧化TAIC制备TGIC

在无机锰盐催化下,以H2O2为氧源环氧化三烯丙基异氰尿酸酯(TAIC)制备异氰尿酸三缩水甘油酯(TGIC),用FTIR和1HNMR测试技术分析了产物的化学结构。研究了物料配比、催化剂用量、缓冲液和反应时间对产率的影响。在n(TAIC)∶n(H2O2)=1∶15,n(TAIC)∶n(无机锰盐)=1∶0.1,缓冲液为NH4HCO3的乙醇溶液,反应时间为25 h,反应温度为25℃的最佳反应条件时,H2O2的利用率和TGIC的选择率分别为15%和69%。探讨了其反应的机理,得出BAP(bicarbonate activated peroxide)体系可以提供使C C双键环氧化的活性氧;Mn2+的加入能够明显提高H2O2的利用率和TGIC的选择率。

基于演化经济地理学模型的 乡村旅游合作社发展分析

当前我国乡村旅游进化到了较为复杂的时期,突破了传统的微观投资阶段,走向了多功能农业经济体。这其中包括了基于历史空间发展的多重路径,旅游合作社的演化研究,这些问题是国内外研究的焦点。基于“有限理性”假设,阐述演化经济地理学EEG研究框架,突出其系统科学方法论的特征,着重研究乡村旅游合作社的路径依赖与各部门在政策调整下的分布关联,使用其中的代表性模型TALC(旅游地生命周期,意译)研究国内旅游合作社的增长状况,着重分析以东南沿海典型乡村旅游合作社为样板的研究。通过历史性空间变化与路径依赖的分析,发现东南沿海乡村旅游增长是农业结构中农村设施、农民行为、区域与全国政策、市场这4个子系统之间的协调作用的结果。为乡村旅游经济的研究提供案例,并对旅游合作社的研究提供了一个不同的视角。

磷酸酯偶联剂(FX-1)对PP/POE/Talc复合材料性能的影响

通过熔融共混法制备了PP/POE/Talc复合材料,研究了偶联剂磷酸酯(FX-1)不同含量对滑石粉表面性能的影响,得出了偶联剂磷酸酯(FX-1)的最佳质量分数为1%;同时,考察了超细滑石粉经偶联剂磷酸酯(FX-1)改性前后与基体PP界面的粘接情况对PP/POE/Talc复合材料力学性能的影响。

液态三元乙丙橡胶固化和力学性能的研究

液体EPDM(三元乙丙橡胶)是相对低分子量的乙烯-丙烯-共轭二烯三元共聚物,针对它的研究较少。该文主要研究了采用DCP过氧化物硫化体系硫化的液体EPDM的固化和力学性能。液体EPDM在引发剂DCP和助交联剂TAIC的作用下,凝胶含量随DCP增加无明显变化,而随TAIC增加而增大。力学性能有相似变化,不随DCP增加而改变,但随TAIC增加而增大。结果表明,交联产物的凝胶含量所表现出的其交联程度的状况导致相同的力学性能变化。实验表明,当DCP为4%、TAIC为12%时,液体EPDM的交联产物有较好的力学性能。

超分散剂改性Talc/PP复合材料结晶行为及微观结构分析

合成了YB超分散剂并制备talc/PP复合材料。采用红外光谱(FT-IR)、差示扫描(DSC)、X衍射(XRD)和扫描电镜(SEM)等方法研究了复合材料的结晶行为和微观结构。结果表明:改性后的talc表面连接了新的有机基团;talc的加入具有异相成核作用,提高了PP结晶温度,但无晶型转变,当talc用量超过30%,异相成核作用减弱;超分散剂与talc存在异相成核协同作用,进一步提高结晶温度,并且对β晶型具有诱导效应,YB超分散剂加入,使部分α晶型向β晶型转变;同时使复合材料的冲击断面从脆性断裂转变为强韧性断裂。

Characterization of Isotactic Polypropylene/Talc Composites Prepared by Extrusion Cum Compression Molding Technique

Extrusion-Compression molded isotactic polypropylene (iPP) composites containing 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% of talc filler were studied by scanning electron microscopy (SEM), simultaneous thermal analysis (STA) and physical testing. The scanning electron microscope (SEM) micrographs of neat iPP and composites with 10 wt%, 20 wt%, 30 wt%, 40 wt% and 50 wt% talc content show that neat PP, 10 wt%, 20 wt%, and 30wt% talc composites surface is smooth in comparison to 40 wt% and 50 wt% talc composites. It is also observed that talc is dispersed uniformly in the matrix and this uniform dispersion is not decreased even with talc content as high as 30 wt% talc. The composites of 40 wt% and 50 wt% talc contain more crack, agglomerates or larger particles. Bulk density of the composites decreases with the increase of talc content. With the increase of percentage of talc and period of immersion, the water absorption (WA) increases. Thermal analyses indicate a considerable increase of thermal stability of the composites with filler addition.

Flotation separation of molybdenite and talc using tragacanth gum as depressant and potassium butyl xanthate as collector

Tragacanth gum(TG)was explored as a depressant to realize the flotation separation of molybdenite and talc.The flotation experiments indicated that when using potassium butyl xanthate(PBX)as a collector,molybdenite showed excellent floatability while talc was completely depressed by TG,thus realizing the flotation separation of the two minerals.X-ray photoelectron spectroscopy(XPS)analysis results showed that TG was adsorbed on molybdenite surface via chemisorption.The results of contact angle measurement,Fourier transform infrared(FTIR)spectroscopy,and time-of-flight secondary ion mass spectrometry(ToF-SIMS)indicated that the pre-adsorption of TG on molybdenite could not hinder the further chemisorption of PBX on molybdenite.Because PBX has no collecting ability on talc,the flotation separation of molybdenite and talc came true using PBX to collect molybdenite and TG to depress talc.

Selective depression behavior of guar gum on talc-type scheelite flotation

The depression behavior and mechanism of guar gum on talc-type scheelite flotation were systematically investigated by flotation experiments, adsorption tests, zeta-potential measurements, and infrared spectroscopic analyses. The flotation results for monominerals, mixed minerals, and actual mineral samples indicated that guar gum exhibited much higher selective depression for talc than for scheelite. Bench-scale closed-circuit tests showed that a tungsten concentrate with a WO_3 grade of 51.43% and a WO_3 recovery of 76.18% was obtained. Adsorption tests, zeta-potential measurements, and infrared spectral analyses confirmed that guar gum absorbed more strongly onto the talc surface than onto the scheelite surface because of chemisorption between guar gum and talc. This chemisorption is responsible for the guar gum's highly selective depression for talc and small depression for scheelite. The flotation results provide technical support for talc-type scheelite flotation.

Mineralogical Characteristics of Unusual Black Talc Ores in Guangfeng County, Jiangxi Province, China

Talc is a hydroxyled, magnesium-rich, layered silicate that has the ideal chemical formula Mg3Si4O10(OH)2. Due to its unique properties, such as softness, chemical inertness, high thermal stability, low electrical conductivity, lamellar habit, adsorption properties, and occurrence of a wide range of particle sizes that can be easily reduced by milling and high specific surface area, talc is widely used in many industries. A stratified deposit of unusual black talc, an occurrence of talc estimated to be more than half a billion tons, was found exposed in the late Neoproterozoic Dengying Formation, located in Guangfeng County, Jiangxi Province, southeastern China. The ores occur primarily as oolitic structures (Fig. 1). The mineralogical and geochemical characteristics of the ores were investigated by using multiple techniques. The ores were found to mainly consist of talc (30%–70%), dolomite, quartz, and magnesite. Most of talc crystals are ultrafine (with an average crystallite size of smaller than 5 μm) and appear as irregular broken or distorted lamellar flakes. The total organic carbon (TOC) content of the black talc ore samples is generally lower than 1.0%. Electron-microprobe analysis (EPMA) revealed low contents of Na, K, Ca and Mn, Fe, Ni, Al in the talc oolitic particles. The talc ores have low contents of toxic elements and relatively high contents of Li and Zn. The infrared spectrum of the black talc is similar to that of white talc from Trimouns (Pyrenees, France), and their Brunauer–Emmett-Teller (BET) specific surface areas, ranging from 15.7 to 23.2 m2/g, is much higher than those of white talc (normally lower than 5.0 m2/g), which may be due to the small size of the talc crystals.

Preparation of Ultra-nano Talcum in Sand Mill and Its Application in the Polypropylene

The grinding of ultra-fine talcum powder and its application in a polypropylene （PP） matrix were investigated. Ultra-fine talcum powder was prepared by adjusting the grinding parameters of the physical milling process. The talcum powder exhibited polymodal distribution. The layered morphology of talcum particles in a horizontal sand mill was rarely damaged or destroyed. PP-talcum nanocomposites were prepared by melt blending using a twin-screw extruder. Nano talcum can be seen as a single particle, although it is not very apparent. The bending strength of talcum-filled PP was gradually increased by approximately 28%. The impact strength linearly decreased as the filler weight ratio increased. The overall maximum improvement in mechanical properties was recorded when the filler ratios increased from 15 wt% to 20 wt%.

TMC-210与Talc联合对PLLA结晶调控及性能研究

为了克服聚乳酸(PLLA)结晶速率慢、专用单一成核剂(TMC-210)价格昂贵的不足,采用TMC-210与Talc(滑石粉)协同调控PLLA的结晶与性能,利用差示扫描量热仪(DSC)、X射线粉末衍射仪(XRD)、小角X射线散射仪(SAXS)、扫描电子显微镜(SEM)、偏光显微镜(POM)和力学性能测试评估了TMC-210联合Talc对PLLA结晶和力学性能的协同影响。结果表明,TMC-210和Talc协同改善了PLLA的结晶能力,使成核密度增加、结晶速率加快,晶体尺寸和长周期均减小,但对PLLA的结构和晶型没有影响。力学测试表明,在PLLA中同时添加质量分数为0.2%的TMC-210和质量分数为4%的Talc,PLLA/TMC-210/Talc三元共混物的断裂伸长率达到23.6%,比PLLA/TMC-210二元共混物提高了262%;当添加质量分数为0.2%的TMC-210和质量分数为1%的Talc时,PLLA/TMC-210/Talc三元共混物的韧性达到5.65kJ/m2的最大值,比PLLA/TMC-210二元共混物、PLLA分别提高了29.3%和210%。

Magnesite and talc origin in the sequence of geodynamic events in Veporicum, Inner Western Carpathians, Slovakia

This paper summarizes recent data about magnesite and talc genesis in Carboniferous host rocks of Western Carpathians (Slovakia) , which occur in two distinct belts in tectonic superunit Veporicum and its contact zone with Gemericum. The northern Sinec magnesite and talc belt (with main deposits Kokava, Sinec, Samo, Hnust'a-Mutnik) contains economic accummulation of magnesite and talc, while in the southern Ochtina belt ( main deposits in Dubrava massif-Dubrava, Mikova, Jedl'ovec; Lubenik, Ochtina, Kosice-Bankov, Banisko, Medvedia) the magnesite is dominating.The magnesite genesis by successive replacement of Carboniferous calcite to dolomite and magnesite during metamorphic process Ml (northern belt 280-400℃; , southern belt 370-420℃: ; Radvanec & Prochaska, 2001; Kodera & Radvanec, 2002) , being supplied by Mg from Permoscythian evaporitic bittern brines, relates to Variscan post-collisional (post-VD) evolution. The extensional tectonics and the high heat flow facilitated the generation of a hydrothermal system.The time-separated later metamorphic and sourcely different fluid flow event (M2; 1. c. ) produced talc. Tectonic, microtectonic, metamorphic and geochronological data relate the talc origin with the Alpine Upper Cretaceous (88-84 Ma; Maluski in Kovacik et al. , 1996) tectonothermal event AD2. This event, being the consequence of Alpine collisional ( AD1 ) crustal thickening and metamorphic core complex origin, meant regional extension and pervasive fluid flow of open system in crustal discontinuities. This process was prominent in the northern belt ( Sinec shear zone) located more closely to Veporic thermal dome, while towards its peripheral parts (southern Ochtina belt) the M2 metamorphic process and steatitization gradually weakened.Studies from Sinec shear zone (being the prominent AD2 -AD3 structure of northern Sinec belt) , where the dolomite/magnesite lenses (replacement in M1) and their accompanying lithology were in AD1 sandwitched between more competent basement blocks, proved in AD2 the pervasite steatitization, the talc and dolomite 2 origin in extensional microstructures ( metamorphic process M2; 490 -540℃, 240-330 MPa, 1. c. ).The economic accummulations of talc in Sinec belt are the products of antithetic shearing during the AD3 phase, being the gradual continuation of AD2 ( change of kinematics from unroofing to regional transpressional shearing). Contrary to the northern Sinec belt having located the AD3 deformation into narrow shear zone with soft lithology surrounded by hard lithology, in southern Ochtina belt the deformation AD3 was accommodated by wide soft rock column with rigid carbonate blocks floating inside. The lower P-T ( M2)conditions and deformational gradient in Ochtina belt during AD2 and AD3 phases caused why no economic talc accummulations developed there.The results of presented study can be used as general criteria for magnesite and talc prospection in Alpine type terranes.

Insights into the adsorption performance and mechanism of hydrated Ca ion on talc(001) basal surface from DFT calculation

The utilization of Ca ion as assistant depressant of CMC on talc has been widely reported.Thus,the study on the adsorption mechanism of Ca ion on talc surface is very crucial for understanding the performance of CMC on talc depression.In this paper,mechanism insights into hydrated Ca ion adsorption on talc(001) basal surface were creatively provided using DFT calculation.[Ca(H_(2)O)_6]^(2+) and [Ca(OH)(H_(2)O)_(3)]^(+) were determined as the effective hydrate components for Ca ion adsorption,and the top O site was the most favorable position for their adsorptions on talc surface.Furthermore,the adsorption mechanisms of [Ca(H_(2)O)_6]^(2+) and [Ca(OH)(H_(2)O)_(3)]^(+) on talc surface were found to be not the Ca-O chemical bond,but the hydrogen bonding formed by the H atom of the H_(2)O ligand and the surface O atom.H_(2)O acted like a bridge to connect them to the talc surface.Moreover,the hydrogen bonding was formed due to the hybridization of H 1s orbital with the O 2s,O 2p orbitals.Simultaneously,electrons transferred between the H atom and the surface O atom.This work provides theoretical insights into the Ca ion adsorption on talc surface,which can help deeply understand the talc flotation using CMC as depression.

Investigation of nano-talc as a filling material and a reinforcing agent in high density polyethylene (HDPE)

An experiment of producing high density polyethylene (HDPE) nano-composite filled with 4wt.% talc was presented. Acting as filler and a reinforcing agent in the HDPE, talc powder, sized at around 5 μm, was surface-treated with aluminum diethylene glycol dinitrate coupling agent before adding to the HDPE. Analyses of the reinforced HDPE nano-composite show significant improvement in its mechanical properties including, tensile strength (>26 MPa), break elongation (<1.1%), flexural strength (>22 MPa), and friction coefficients<0.11. The results demonstrate that, after surface-treated, talc can be used as a promising filling material and a reinforcing agent in making HDPE nano-composite.

Management of recurrent malignant pleural effusions with a tunneled indwelling pleural catheter

In this review, we report on the use of indwelling pleural catheters in the treatment of malignant pleural effusions. We describe the most commonly used catheter. Also, treatment with indwelling pleuralcatheters as compared to talc pleurodesis is reviewed. A comparison of efficacy, costs, effects on quality of life, and complications is made. Only one randomized controlled trial comparing the two is available up to date, but several are underway. We conclude that treatment for malignant pleural effusions with indwelling pleural catheters is a save, cost-effective, and patientfriendly method, with low complication rates.