Papers by Keyword: Pyrophyllite

Abstract: The present work investigates the use of an alumino-silicate material, the pyrophyllite as cement substitution, synthetic polypropylene fibers and binder to create an unusual ultra-performance fiber concrete; new composite, which offers a wide field of possible use in construction industry. Effect of pyrophyllite on the physical-mechanical properties is analyzed. One reference fiber concrete without pyrophyllite and three fiber concretes containing 10%, 20%, 30% of pyrophyllite were elaborated. Results show that the pyrophyllite affects the characteristics of the concrete. Indeed, in the hardened state, the density of fiber concrete decreased with pyrophyllite rate increasing. Moreover, the use of pyrophyllite slows down the hardening process of concrete, consequently producing at early ages, compressive, flexural and tensile strengths and elastic modulus of concretes approaching without exceeding those of the reference fiber concrete. The fiber concretes are also considered to be of good quality. It seems that the rate of 10 % of pyrophyllite generates the best physical-mechanical performances that approach those of the reference fiber concrete. The use of pyrophyllite as a cement substitution is beneficial since it can help to decrease the production of cement; the amount of CO₂ released and protects the environment.

Abstract: The mechanical destruction of the pyrophyllite structure and final ground products upon grinding with a laboratory planetary ball mill were investigated using high-resolution transmission electron microscope (HRTEM) coupled with selected area electron diffraction (SAED), field emission scanning electron microscope (SEM) and X-ray diffraction (XRD). Grinding produced a profound structural alteration, resulting in increasing amorphization. Increasing the intensity of grinding resulted in acceleration of the mechanically induced amorphization of the pyrophyllite structure. The pyrophyllite phase was transformed into its anhydride phase during the process of the prolonged grinding. Increasing the grinding intensity resulted in faster destruction of the pyrophyllite structure. The plate-like microcrystal exhibited the 2M-pyrophyllite crystal structure. The pyrophyllite anhydride phase was existed after grinding.

Abstract: Soda-lime glass is produced by melting sand (SiO2), soda ash (Na2CO3), lime stone (CaCO3) together with effective additives such as dolomite (CaMg(CO3)2) and an important structural modification, alumina (Al2O3) in which the melting temperature is very high around 1500°C. With this reason, to dissolve alumina, high amount of energy is needed. Consequently, one of possibilities to reduce the melting energy is replacing alumina by the raw material with a lower enthalpy of melting. The heat required for melting the batch of raw materials from atmosphere temperature to melting temperature is called exploited heat (Hex), which can be calculated from chemical enthalpy (H°chem) and heat content (Hmelt) at reference temperature (Tex). From thermodynamic approach, chemical enthalpy of alumina is higher than feldspar (KAlSiO3) or pyrophyllite (Al2Si4O10(OH)2). For the glass batch with alumina, the calculated exploited heat is 540 kWh/ton while the batch with feldspar or pyrophyllite is lower, namely 534 and 484 kWh/ton, respectively. This means that the melting process can be emerged easier than the batch with alumina because the melting point of feldspar is around 1200°C and pyrophyllite dehydroxylates around 900°C. The kinetic properties of batch melting were investigated by Batch-Free Time method, which defines the melting ability of the modified batch. According to thermodynamic calculation, it was found that both alternative batches were melted easier. The study showed that feldspar or pyrophyllite could be used instead of alumina without significant changes in glass chemical composition and physical properties. The concern of using feldspar or pyrophyllite is the quantity of minor impurities which affect to the color appearance especially in clear glass products.

Abstract: As a harmful impurity, Pyrophyllite must be remove in synthetic diamond purification process. It commonly use chemical method. A trial research is made on the removing of pyrophyllite impurity in synthetic diamond by physical method. As a result, after synthetic diamond materials containing pyrophyllite are selectively interground in the ball grinding machine, the pyrophyllite is effectively broken and removed from the coarse – medium grade diamond only by physical method, but diamond quality is not affected.

Abstract: Promoting of mullite generation has been studied by replacing kaolinite with pyrophyllite because of mullite has excellent strength and thermal shock resistance. Effects of promoting of mullite generation and vitrification by replacing kaolinite with pyrophyllite on the mechanical and thermal properties were investigated. Addition of 45-55% pyrophyllite as a replacement of kaolinite (pyrophyllite (45-55%)-feldspar (30%)-clay (20%)) could vitrify samples (water absorption: 0.05%, bulk density: 2.66g/cm3) and improve the strength (122MPa) of samples fired at 1280°C. In ternary porcelain system, pyrophyllite-feldspar-clay, mullite generation of samples with 50% pyrophyllite reaches about 78.7% and thermal expansion coefficient is 5.4×10-6/K. Beyond 50% pyrophyllite addition, quartz and cristobalite phases increased. And thermal expansion coefficient of samples decreased with increasing of mullite amount.

Abstract: Pyrophyllite was the cheap, environmentally friendly alumina silicate clay minerals. This paper studied optimization of conditions for extraction of acid-soluble Al₂O₃ from pyrophyllite. Qualitative tests had been performed in studying pyrophyllite crystal at different temperatures by using scanning electron microscopy. Dissolution experiments showed that after thermal activation the behavior of alumina in acid the dissolution was different, which was affected by hydrochloric acid concentration, heat activation temperature and acid leaching time. When the calcinations temperature was 700 °C and hydrochloric acid concentration was 25%, the dissolution amount of alumina largest. The fit results indicated that the research for the relationship between dissolution and time by Using Exponential function series Asymptotic1 model to fitting match was the best. So the above function could be used to estimate each time the dissolution of alumina from pyrophyllite in hydrochloric acid.

Abstract: This paper studied the influence of heat treatment on the pyrophyllite structure and acid-soluble properties of alumina. Qualitative tests had been performed in studying pyrophyllite crystal at different temperatures by XRD, TG-DTA, FT-IR and quantitative analysis of Al2O3. The quantitative titration method studied the dissolve characteristics of the different heat treatment samples in different acid conditions, and then a numerical simulation was done. The results showed that at temperatures below 480 °C, the pyrophyllite did not change the basic structure. 480~700 °C dehydroxylation reaction occurred, and the structure water of pyrophyllite is removed, and then turned into partial pyrophyllite. Dissolution experiments showed that after thermal activation the behavior of alumina in acid the dissolution was different, which was affected by hydrochloric acid concentration, heat activation temperature and acid leaching time. When the calcinations temperature was 700 °C, the dissolution amount of alumina was largest. These works could provide some theoretical basis for further application of pyrophyllite research.

Abstract: In this experiment, pyrophyllite as the main materials used the flame photometer to measure adsorption. Using the qualitative analysis of the samples of XRD with internal structure and found that pyrophyllite used in the experiment as a natural mineral, the presence with other minerals. Meanwhile, scanning electron micrographs (SEM) from the display showed that the effect of pyrophyllite adsorption for cations should be more significant. Therefore, this experiment focused on the time, Na⁺ concentration, on the pyrophyllite and different pyrophyllite concentrations (adsorbent dosage) effect on the adsorption, in addition to the adsorption dynamics. The results showed that pyrophyllite adsorption sodium in the best time of equilibrium was 20 minutes, the concentration of NaCl was 50 mg/L, pH = 7, temperature was 313 K, the concentration of pyrophyllite was 5 mg/L.

Abstract: The present investigatory founded an effectiveness of inexpensive and eco-friendly alumina silicate clay minerals, sericitic pyrophyllite (SP), as an adsorbent for the possible application in the absorption of K+. The crystal structure of pyrophyllite, size and morphology were characterized by XRD and SEM. In addition to pyrophyllite, quartz and were also contained in the minerals. The area of lamellar SP was about dozens um2. The results showed that potassium was absorbed on the SP under different pH and concentrations, and the best condition was pH=6, the time of equilibrium absorption = 30 min. It has been found that these natural minerals are effective in removing 55−75% of K+ from 5.0 to 20 mgL-1 KNO3 solutions. The applicability of the Langmuir, Freundlich and Dubinin-Radushkevich adsorption isotherms in each case of potassium was examined separately. We found that the adsorption process was endothermic in the case of SP and the Freundlich adsorption model was to more suitably represent the data. The work could provide the theoretical basis of the study of potassium ions adsorbed by pyrophyllite applying in fertilizer.

Abstract: Mechanical and vulcanization behaviors of styrene-butadiene rubber(SBR)/N330 and SBR/N330/PBMCN nanocomposites were investigated via partial replacement of SBR with pyrophyllite based modified composite nanopowder(PBMCN), which were prepared by melt mixing procedure. Results show a fairly good dispersion of PBMCN in the SBR/N330/PBMCN composites characterized by field-emission scanning electron microscope (FESEM). Mechanical and vulcanization behaviors of the as-abtained pruducts were measured according to GB/T 528-2009 and GB/T 16584-1996, respectively. Near properties in tensile strength, elongation at break and vulcanization behaviors were observed in SBR/N330/PBMCN nanocomposites when SBR was partially replaced by PBMCN for 8% mass fraction. A possible reinforcement mechanism of PBMCN to SBR/N330/PBMCN nanocomposites is also dicussed based on the experiment.