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1.
金精矿样品的粒度,直接影响金精矿中金含量测定的精密度和稳定性,本文通过对Golden Grove金精矿采用不同的磨样工具和磨样时间,得到不同粒度的样品,对不同样品进行了金含量的测定,并对测定结果的精密度进行了分析。其中磨样方式:滚筒磨样机、磨样时间为5h、磨样粒度为0.040mm(360目)95%以上的B样品,测定精密度最好。C样品测定精密度相对较差,反映出振动粉碎机磨样均匀度相对较差。 相似文献
2.
We have measured the contamination of samples of granite, quartz porphyry, greenstone and dolerite after grinding them in steel and cemented carbide grinding mills. The steel mill contaminated the granite with Fe. The cemented carbide mill contaminated all samples with W and Co, and the granite and quartz porphyry with Ta. Contamination during grinding is proportional to the free quartz content of the rock and to the grinding time. 相似文献
3.
The study of contamination effect during cryogenic grinding of pure cellulose was carried out. The optimisation of important parameters of the grinding process (pre-cooling time, grinding time, cooling time and number of cycles) was performed and the different sources of a possible contamination of samples (earlier processed sample, metal parts of grinding tool) were evaluated. The results of ICP-oa-TOF MS analysis after microwave digestion of cellulose samples were used in this study. Significant contamination of cellulose samples by Fe at the level 130 microg kg(-1) caused by wearing of steel stoppers and an impact bar was detected. Cross-contamination by Fe, Cr, Mn and Cu at the level 400, 200, 200 and 2100 microg kg(-1), respectively was caused by previous grinding of electro-waste sample. This cross-contamination was possible to be avoided by changing of a polycarbonate part of a grinding vessel. 相似文献
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本实验应用X射线光电子谱仪,在获取磨削弧区温度的基础上研究了K 417镍基铸造高温合金表面氧化膜的成分和结构,其中包括正常缓磨后及出现不同层次烧伤色后的氧化膜,结果表明,氧化膜不是出现烧伤色的试样所特有,对正常缓磨试样也存在,只是氧化膜厚度不同而已。磨削弧区温度越高,烧伤色层次越深,对应的氧化膜厚度亦越大。氧化膜是Ni、Cr、Ti、Al等元素的氧化物及晶体态Ni等以掺合结构所组成。 相似文献
6.
研磨破乳的规律及其机理 总被引:5,自引:0,他引:5
报道了研磨破乳的实验规律,讨论了研磨破乳的基本步骤:(1)过滤过程中乳状液内相液滴在研磨剂表面铺展成膜并进一步聚结──过滤破乳;(2)研磨剂的相互碰撞使乳状液的分散液滴受到摩擦力和剪切力,导致液滴聚结──研磨破乳。 相似文献
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Hrachová J Madejová J Billik P Komadel P Fajnor VS 《Journal of colloid and interface science》2007,316(2):589-595
Structural changes in Ca and octadecyltrimethylammonium (ODTMA) montmorillonite induced by dry grinding in a high-energy planetary ball mill were investigated by X-ray powder diffraction (XRD) analysis, infrared (IR) spectroscopy, and scanning electron microscopy (SEM). The organomontmorillonite is more resistant toward mechanical destruction than the Ca form. Both XRD and IR analyses indicate a complete breakdown of the mineral layers after 5 min of grinding of Ca-JP. The XRD pattern of the ODTMA clay shows disappearance of the layer ordering along the c axis after 40 min of grinding, while persistence of the layered structure for all tested samples is proven by the IR spectroscopy. The grinding process affects chemical bonds in the OH, SiOAl, and SiOSi groups of montmorillonite; however, no changes are observed for CH bonds of the organocations. In contrast to the Ca form, all absorption bands typical for montmorillonite appear in the IR spectrum of the ODTMA montmorillonite even after 40 min of grinding. The majority of the bands are undetectable in the spectrum of Ca montmorillonite ground for 5 min. Amorphization of the montmorillonite caused by an intense grinding process is markedly slower after replacing the inorganic cations with the long-chain alkylammonium cations. 相似文献
9.
G. Stringari Ivo Pancheri Frank Möller Osvaldo Failla 《Accreditation and quality assurance》1998,3(3):122-126
Chemical analyses of trace elements are affected by relatively high analytical errors due to the different steps of the laboratory
procedures: samples grinding, mineralisation and instrumental measurements. In the present communication, the influence of
the grinding phase on the global uncertainty of Pb, Cd, Ni and Cr determinations in plant samples by the classical method
of atomic absorption spectrometry/electrothermal atomisation (AAS-ETA) after dry ashing is quantified. Two grinding machines,
a planetary mill with balls and jars of agate versus a stainless steel grinder were compared by analysing leaf samples of
cucumber, strawberry, kiwivines, apple trees and grapevines from agricultural experimental plots under controlled conditions.
Variance components due to the difference between grinding methods and experimental plots were estimated. Further, the simultaneous
effects of the grinding methods on all considered metals have been evaluated by analysis of variance. With the stainless steel
grinder, on average, higher levels of the considered heavy metals were obtained (up to 67% of the mean values). On average,
the increments were similar for metals contained in steel (Ni and Cr) and those not contained (Pb and Cd). The true causes
of these differences need further investigation to determine whether the higher metal detection is due to possible contamination,
to a different grinding quality or to other reasons. Finally, the grinding methods did not seem to affect the combined uncertainty
of the analyses.
Received: 3 November 1997 · Accepted: 29 November 1997 相似文献
10.
V. Balek L. A. Pérez-Maqueda J. Poyato Z. Černý V. Ramírez-Valle I. M. Buntseva J. L. Pérez-Rodríguez 《Journal of Thermal Analysis and Calorimetry》2007,88(1):87-91
The effect of grinding
on thermal behavior of pyrophyllite and talc as commonly used ceramic clay
minerals was investigated by DTA, TG, emanation thermal analysis (ETA), B.E.T.
surface area (s.a.) measurements, X-ray diffraction (XRD) and scanning electron
microscopy (SEM).
A vibratory mill was used in this study, grinding
time was 5 min. It was found that the grinding caused an increase in surface
area and a grain size reduction of the samples. From TG and DTA results it
followed that grinding caused a decrease of the temperature at which the structure
bound OH groups released. The formation of high temperature phases was enhanced
with the ground samples. For the ground talc sample the crystallization of
non-crystalline phase into orthorhombic enstatite was observed in the range
of 800°C. For ground pyrophyllite a certain agglomeration of grains was
observed in the range above 950°C. Moreover, for both clays the ETA characterized
a closing up of subsurface irregularities caused by grinding as a decrease
of the emanation rate in the range 250–400°C. The comparison of
thermal analysis results with the results of other methods made it possible
to better understand the effect of grinding on the ceramic clays. 相似文献
11.
《Analytical letters》2012,45(3):647-668
Abstract An automated system to grind geologic samples has been successfully tested. A Zymate II robotic system, along with specially designed or modified hardware, was used to process partially pulverized geologic samples. the system is capable of processing samples on a 24-hour basis with an average per-samples grinding time of 12.4 minutes. A sample grinding period is followed by a cleanout sequence of air purges, vacuuming and grinding for surface cleaning with quartz sand. Routine operator involvement is limited to adjusting the grinding plates on the Bico vertical grinder at the beginning of each preparation interval. Studies conducted using variable amounts of cleaning sand between grinding of samples indicate that the adjustment interval can be extended to 50 samples (25g cleaning sand) using an acceptance criteria of 80% of sample passing 80 mesh. the processed samples are suitable for direct geochemical analysis using a variety of standard chemical digestions. Cross contamination studies using soil, chromite, and galena/sphalerite samples have revealed that the grinding system is capable of clean-out efficiencies exceeding 99% using as little as 25g of cleaning sand. 相似文献
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S Puttipipatkhachorn E Yonemochi T Oguchi K Yamamoto Y Nakai 《Chemical & pharmaceutical bulletin》1990,38(8):2233-2236
The effect of grinding on the dehydration of crystal water of theophylline has been studied. It was observed that the water content of theophylline hydrate decreased with increased grinding time. As the grinding time proceeded, the results of differential scanning calorimetry (DSC) indicated that crystal water of ground theophylline hydrate dehydrated in three steps at ca. 58, 44, and 17 degrees C, respectively. Powder X-ray diffraction study revealed that the crystal lattice of theophylline monohydrate collapsed by grinding, and part of the theophylline molecules subsequently rearranged the collapsed lattice to form theophylline anhydrate. The result of Fourier transformed infrared spectroscopy demonstrated that the hydrogen bonds between crystal water molecules and theophylline molecules were weakened or destroyed to some extent by grinding. It was supposed that crystal water in the ground theophylline hydrate might exist at least in three molecular states of different hydrogen-bonding. From DSC study, it was suggested that the ruptured hydrogen bonds of water molecules in the ground theophylline hydrate were strengthened after storage under 96.5% relative humidity at 30 degrees C. 相似文献
13.
A. I. Sokol’skii A. A. Kotkov E. P. Barulin 《Russian Journal of Applied Chemistry》2008,81(3):500-502
Combined three-stage installation with swirling flows for drying and grinding of shungite was designed. Experimental data on drying and grinding of this mineral in the third stage of the installation are presented. 相似文献
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H2 generation during mechanochemical treatment of kaolinite by dry grinding was examined by X-ray diffraction analysis, Fourier transform infrared spectroscopy, and BET surface area measurement. The H2 concentration in the mill pot, measured by gas chromatography, increased with grinding time up to a maximum concentration of 156 ppm (0.35 micromol) after 600 min. This H2 generation is considered to occur as a result of three processes: (1) structural destruction characterized by the delamination and loss of hydroxyl groups as a result of dry grinding, (2) transformation of liberated hydroxyls into water molecules by mechanochemical effects such as prototropy, and (3) H2 generation through reaction between surface water molecules and mechanoradicals created by the rupture of Si-O or Al-O-Si bonds. Although the surface area plateaued after 240 min grinding, the H2 concentration continued to increase, indicating that surface mechanoradicals are created during this later grinding stage. Thus, H2 generation can be used as an indicator of mechanoradical formation during mechanochemical treatment. 相似文献
16.
The question whether fatigue is induced during mechanical pulping was addressed experimentally. The grinding process was interrupted
to image partly ground spruce samples. The grinding was performed at five different feed velocities using two different grindstones.
This approach allowed creating an in situ snapshot of the developing grinding zone in the wood samples. The depth profiles
of the stiffness modulus and nm-scale pores, close to and within, the grinding zone were quantified by ultrasonic pitch-catch
measurements and thermoporosimetry. To perform these profiling measurements, wood material was iteratively removed layer-by-layer
with a microtome from the sample surface after taking the snapshot. The grinding-induced changes in cell morphology inside
the sample were imaged using microcomputed tomography, whereas the changes on the surface of the samples were imaged with
optical microscopy and SEM. A layer that penetrated 0.5–1.5 mm into the sample exhibiting up to 80% decreased stiffness modulus—compared
to the unaltered sample parts—was detected when the Wave-type grindstone was employed. The corresponding layer thickness was
0.3 mm with the conventional grindstone. The results match previously measured temperature profiles, and confirm the Atack-May
hypothesis that grinding induces a fatigue layer. Confirming this old, widely used hypothesis is significant for the field
of energy efficiency research related to mechanical pulping and may provide new opportunities for grinding research. 相似文献
17.
It is shown that, currently, the most effective grinding and dispersant equipment in the technology of coating production are fluidized-bed devices—devices in which grinding and dispersion of pigments and fillers occur via ferromagnetic bodies driven by an electromagnetic field. 相似文献
18.
Frost RL Horváth E Makó E Kristóf J Cseh T 《Journal of colloid and interface science》2003,265(2):386-395
The effect of mechanochemical activation upon the intercalation of formamide into a high-defect kaolinite has been studied using a combination of X-ray diffraction, thermal analysis, and DRIFT spectroscopy. X-ray diffraction shows that the intensity of the d(001) spacing decreases with grinding time and that the intercalated high-defect kaolinite expands to 10.2 A. The intensity of the peak of the expanded phase of the formamide-intercalated kaolinite decreases with grinding time. Thermal analysis reveals that the evolution temperature of the adsorbed formamide and loss of the inserting molecule increases with increased grinding time. The temperature of the dehydroxylation of the formamide-intercalated high-defect kaolinite decreases from 495 to 470 degrees C with mechanochemical activation. Changes in the surface structure of the mechanochemically activated formamide-intercalated high-defect kaolinite were followed by DRIFT spectroscopy. Fundamentally the intensity of the high-defect kaolinite hydroxyl stretching bands decreases exponentially with grinding time and simultaneously the intensity of the bands attributed to the OH stretching vibrations of water increased. It is proposed that the mechanochemical activation of the high-defect kaolinite caused the conversion of the hydroxyls to water which coordinates the kaolinite surface. Significant changes in the infrared bands assigned to the hydroxyl deformation and amide stretching and bending modes were observed. The intensity decrease of these bands was exponentially related to the grinding time. The position of the amide C=O vibrational mode was found to be sensitive to grinding time. The effect of mechanochemical activation of the high-defect kaolinite reduces the capacity of the kaolinite to be intercalated with formamide. 相似文献
19.
The aim of this study was to produce Lantana camara essential oil by SFE and to study the effect of matrix grinding on the yield and/or composition of the extract. Experiments were carried out on grinding matrices (G) and on not grinding matrices (NG). The extracts were analyzed by GC-MS. A comparison with the oil obtained by hydrodistillation is also given. Finally, the antibacterial and antifungal activity of the various extracts has been assayed. 相似文献
20.
Trask AV Haynes DA Motherwell WD Jones W 《Chemical communications (Cambridge, England)》2006,(1):51-53
Neat grinding and solvent-drop grinding methods are found to be effective screening tools for indicating the potential for crystalline salt formation involving a given acid-base pair, as demonstrated with two model pharmaceuticals. 相似文献