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.

Sm-Nd dating and rare earth element geochemistry of the hydrothermal calcites from Guling carbonate-hosted talc mineralization in the central Guangxi province,South China

Many carbonate-hosted talc mineralization,which are widespread in South China,exclusively developed in Carboniferous dolomitic limestone with many siliceous bands and nodules,and cherts.One of those typical deposits is the Guling talc deposit in Mashan County,central Guangxi province,with a talc reserve of1.51 million tons.Mineral associations in the deposit are sample,mainly including talc and calcite.In this paper,Sm-Nd isotopic system and rare earth elements and yttrium(REE + Y) for the hydrothermal calcite intergrown with talc are used to constrain the age and origin of the talc mineralization.The hydrothermal calcite samples from the deposit display Sm and Nd concentrations ranging from 0.18 to 0.85 and 0.85 to 4.56 ppm,respectively,and variable Sm/Nd ratios of 0.21-0.24.These calcites further yield an Sm-Nd isochron age of 232 ±19 Ma(2a)(MSWD = 0.47) with an concordant initial ^(143)Nd-^(144)Nd ratios of 0.511967 ± 0.000017,which should be interpreted as the mineralization age of the Guling talc deposit.In addition,the calcite samples are enriched in REE with the variable SREE contents ranging from 4.82 to21.50 ppm and display relatively consistent chondritenormalized REE + Y patterns with the LREE enrichment(LREE/HREE=2.00-3.60)and the obvious negative Eu(δEu=0.52-0.68)and Ce(δCe=0.16-0.33)anomalies.The Y/Ho ratios of seven calcites varies from 43.30 to59.34,with a mean value of 49.73.The available mineral associations and REE parameters(i.e.,REE patterns and Y/Ho ratios) of those calcites indicate that the ore-forming fluids of the talc mineralization be probably derived from the meteoric waters,in particular evolved ones in the Karst areas and the ore-forming materials(e.g.,Si and Mg) are likely to be originated from the ore-bearing dolostone in the Yanguan Formation(C_1y) and underlying siliceous rocks in the Liujiang Formation(D_3l).Furthermore,the talc mineralization could take place within a hydrothermal system with relative oxidizing environment and middle temperature,due to the obvious negative Eu and Ce anomalies in the calcites in the Guling deposit.

The Experimental Study of Talc and Antigorite Evolution under Dry-Thermal Condition

The Xiuyan Jade samples were treated under thermal conditions. By polarizing microscope, the three kinds of jade were choosed. With DTA-TG analysis, three transition temperatures were obtained which were 600℃, 770℃ and 840℃. The study interpreted the mechanism of Xiuyan Jade under thermal condition through XRD analysis results. The mechanism of antigorite thermal activation was as following: when the temperature reached 600℃, the hydroxyl in octahedral sheet began dehydrating, and the new mineral phase forsterite was found, but the layer structure was maintained; when the temperature reached 770℃, the layer structure of antigorite was destroyed; when the temperature reached 840℃, the crystallinity of forsterite was improved, then another new mineral phase enstatite appeard. For talc, it was likely turn to enstatite directly while the temperature rising, and the appearance of SiO2 was most likely due to the conversion of 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.

Effectiveness of Talc Filler on Thermal Resistance of Recycled PET Blends

In general, high mechanical properties such as higher impact strength and thermal resistance are required for injection molded applications. Recycled PET (RPET) is well known to exhibit brittle behavior in the presence of notches and indicated the low heat distortion temperature. Therefore, we tried to improve the toughness and thermal resistance properties of RPET by incorporating E-GMA, talc filler and engineering plastics as an impact modifier and talc to increase the rigidity and heat distortion temperature of RPET. As a result, these blends with E-GMA exhibited significantly higher stiffness and strength especially with increasing E-GMA content. In addition, these blends with talc filler indicated the high heat distortion temperature due to the increase of the crystalinity of RPET blends. Therefore, it was found that talc played an important role in enhancing the heat resistance of RPET.

A Talc-Based Cement-Poor Concrete for Sealing Boreholes in Rock

Deep investigation boreholes in crystalline rock for site selection of repositories for high-level radioactive waste are proposed to be sealed by installing a series of dense concrete and clay plugs. These should prevent radionuclides from leaking canisters at depth to migrate to the biosphere through the holes. The concrete seals will be installed where the holes intersect water-bearing fracture zones to serve as stable and low-permeable supports for adjacent clay plugs. Low porosity and microstructural stability must be guaranteed for many thousands of years and ordinary Portland cement with organic superplastizer will not fulfill the requirements since the high pH will cause degradation of contacting clay and the organic additive can produce colloids with a capacity to carry radionuclides up to the biosphere. Very cement-poor concrete (

Compositional Features and Industrial Assessment of Talcose Rocks of Itagunmodi-Igun Area, Southwestern Nigeria

Talcose rocks from Itagunmodi and Igun areas within the Ilesa Schist Belt, southwestern Nigeria, were studied to determine their compositional affinities and industrial properties. The talcose bodies occurred as lensoid enclaves closely associated with amphibolites and quartz-mica schist. Petrographic and X-ray diffraction-aided mineralogical studies reveal that the talcose rocks are of the talc-chlorite schist variety composed predominantly of talc (average 73.63%), subordinate chlorite (average 16.08%) and accessory lizardite (average 6.5%). Total whole rock characterization of the samples using Lithium Fusion digestion revealed high mean concentrations of SiO2 (57.53%), MgO (24.84%) and Fe2O3 (7.73%) with significant enrichment of Ni, Co and Cr;and low values of Ba, Rb, Sr, V, Cu and Pb. The talc-chlorite schists plotted in the peridotitic komatiite field of the Al2O3-(FeO + TiO2)-MgO diagram. Water Absorption Capacity ranges from 6.25% - 8.20%, Loss on Ignition is 4.8% - 6.1% while Linear Shrinkage is 1.25% - 1.70% and firing colour is brown to dark-brown. The overall compositional features of the talcose rocks of the area, which were hitherto uncharacterized, show their suitability as raw materials for paint, coloured pottery, ceramic insulation, textile, rubber and plastic manufacture with varying beneficiation requirements. Their high trace element content however, makes them unsuitable for use in pharmaceutical and cosmetic applications.

Study of Physical, Chemical and Thermo-Mechanical Properties of Talc Filled Polyester Resin Composite Using Styrene Monomer

Fiber Reinforced Thermoplastic (FRTP) composites are emerging as potential materials in many engineering fields. In this research, the compression-molding process was used as the fabrication technique for producing talc-filled reinforced polyester composite. The weight percentage of these composites was varied, like 30 wt%, 40 wt%, 45 wt%, and 50 wt% talc, respectively. Besides, different percentages of styrene monomer, such as 0 wt%, 20 wt%, and 30 wt%, were also used in this study. Different types of physical, chemical, mechanical, and thermal properties were investigated. The water absorption percentage is increased for composites having a higher percentage of talc filler, while the elasticity of the composites shows a decreasing nature with the increase of talc content. Compressive strength is increased with higher talc content. After a certain limit, with the increase of talc content, it decreases and remains more or less constant. The flexural properties (flexural strength, tangent modulus, and flexural strain) of polyester-talc composites are higher initially, and as the percentage of talc increases, the flexural properties decrease or remain constant. The rate of water absorption is very low with the increase in soaking time. The thermal analysis of polyester-talc composites shows that the thermal stability of the composites is better than that of polyester.

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%.

Studies on the Structure and Properties of Cordierite Synthesized by Talc-Magnesite

Homogeneous cordierite has been synthesized at low cost by talc-magnesite and coal gangue as the main raw materials. The mechanism of synthesizing cordierite under such a composing system of raw materials, and the effect of temperature on the crystal cell parameters and microstructure and thermal expansion coefficient of cordierite crystal have been studied via testing methods of XRD, SEM, etc. The result shows that the homogeneous cordierite can be synthesized by the systematic composing materials of ＂talc-magnesite-coal gangue-talc＂ with heat pre-servation at 1350 ℃ for 1 h; as the keeping time is prolonged, Al^3＋ and Mg^2＋ in cordierite crystal are replaced by a few impurity ions such as Fe^3＋, Fe^2＋, etc., and the crystal cell parameters of cordierite present an increase trend; as the high-temperature heat preservation is prolonged, the content of glassy phase in the sample is increased, its density is improved, and its thermal expansion coefficient presents an increase trend.

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。

低品位滑石提纯工艺试验研究

我国低品位滑石需求量低,但高品位滑石供不应求,为了提高低品位滑石的利用价值,通过化学提纯与水热合成相结合的方法,以低品位滑石、硅酸钠为原料合成高品位滑石。分析了低品位滑石在不同时间下的酸溶解情况,探究了脉石矿物(菱镁矿)完全溶解的最佳时间。通过考查低品位滑石预处理方式、是否煅烧、前驱体形成条件、水热反应温度、时间等因素对产物结晶度和纯度的影响,得到最佳提纯合成工艺条件:在80℃下酸处理2 h后低品位滑石中的菱镁矿完全溶解;在60℃下将酸解混合液与硅酸钠混合,调节体系pH至7~8预反应6 h获得前驱体,前驱体在180℃水热条件下反应13 h,最终制备出了高品位滑石。研究成果可为我国低品位滑石的高值化利用提供借鉴。

填料对二次胶粘物沉积的影响

以丙烯酸树脂作为废纸回用过程中产生的二次胶粘物的模型物,对作为填料的滑石粉和轻质碳酸钙对二次胶粘物的吸附以及沉积性能的影响进行了研究。研究结果表明,填料级的滑石粉和轻质碳酸钙对二次胶粘物具有相近的吸附能力。在没有其他可造成二次胶粘物失稳的物质加入时,滑石粉和轻钙对二次胶粘物的吸附会导致沉积的产生;与不加入填料相比,在阳离子聚丙烯酰胺和阳离子淀粉加入量较低的情况下,填料的加入会导致沉积量的明显增加;而在阳离子聚合物加入量较大的情况下,阳离子聚合物与二次胶粘物以及填料形成的絮聚物在纤维上的有效吸附使这种影响减小。

STUDY OF THE EFFECT OF SOLUTION SURFACE TENSION ON THE FLOTATION BEHAVIOR OF GRAPHITE AND TALC

The effect of solution surface tension on the flotation behavior of natural hydrophobic minerals such as graphite and talc is studied. The best sol- ution surface tension range is also given in the graphite and talc flotation. And the critical sur- face tension distribution of floatability of them is analysed.

Electrochemical Oscillations during Cathodic Polarization Process of Aluminum Covered with Talc Coating

Talc coatings were produced with chemical method on the surface of pure aluminum. The characteristics of cathodic polarization in a 3.5% NaCl solution have been studied through the observation of the 'current oscillations' phenomenon.

ELECTRORHEOLOGICAL PROPERTIES OF TALC POWDER/SILICONE OIL SUSPENSIONS UNDER DC FIELDS

In this study, the electrorheological （ER） behavior of suspensions prepared from d50 = 2.4 lam talc powder, dispersed in insulating silicone oil （SO） medium was investigated. Sedimentation stabilities of suspensions （c = 5 wt%） prepared using these talc powder powders were determined to be 78 days. The ER activity of all the suspensions was observed to increase with increasing electric field strength, concentration and decreasing shear rate. The shear stress of talc powder suspensions increased linearly with increasing concentrations of the particles and with the applied electric field strength. Electric field viscosity of all the suspensions decreased sharply with increasing shear rate and showed a typical shear thinning non-Newtonian visco-elastic behavior. Effects of frequency on the ER activity of talc powder/SO system were also investigated.

刍议三仁汤君药之动态性

三仁汤之君药认定多有争议,目前主要存在2种观点:一者以杏仁、白蔻仁、薏苡仁(三仁)为君药,一者以滑石为君药。结合《黄帝内经》《本草纲目》《温病条辨》等中医古籍及近现代医家的相关文献、著述记载分析,发现上述2种观点并不矛盾,反而体现了君药的动态性。文章分别对2种观点进行阐述,认为治法方面以三仁为君药重在强调宣畅气机,以滑石为君药重在强调清热利湿,根据治疗的侧重点不同,其君药亦可随之而改变。

P-RC APMP浆与未漂DIP浆配抄新闻纸的研究

对三倍体毛白杨P-RCAPMP浆与未漂DIP浆配抄新闻纸进行了较为详细的试验研究,不但确定了配抄新闻纸所用浆料的较佳配比,而且对滑石粉用量对纸页性能的影响进行了讨论,同时还确定了调色时碱性品蓝和碱性品紫的较佳用量。从试验结果来看,以P-RCAPMP浆与未漂DIP浆为主、适当进行加填及调色进行配抄,可以抄造出较高档的新闻纸手抄片。

滑石型钼矿选别工艺和药剂研究进展

这是一篇矿物加工工程领域的论文。钼具有多项良好的物理化学性质,在多个领域得到广泛应用。钼主要来源于辉钼矿,但易选钼矿资源经长期开发而日益减少,如今滑石型等难选钼矿逐渐成为研究的焦点。滑石与辉钼矿的分离是滑石型钼矿分选的难点,两者具有相似的表面结构与天然可浮性,分离十分困难。文章概述了目前滑石型钼矿的选矿工艺与药剂等方面的研究进展,提出加强对滑石型钼矿选择性磨矿与有机大分子药剂的研究开发,以及加深药剂与矿物表面的作用机理和对原矿工艺矿物学的研究是今后分选滑石型钼矿的重要方向。