Search

One of the research areas focused on improving the efficiency of diamond-bearing kimberlite beneficiation processes involves the utilization of technology aimed at enhancing the recovery of weakly and anomalously luminescent diamonds during the X-ray luminescence separation process using luminophore-containing chemical agents. The objective of this research was to select the optimal composition of agents that modify the spectral characteristics of minerals and the conditions for their application. A crucial factor for process efficiency is the effective attachment of modifying agents to diamond crystals while avoiding similar attachment to kimberlite mineral surfaces. This is achieved through the use of organic collectors with an optimal composition, characterized by their ability to both adhere to the diamond surface and retain inorganic luminophore grains. The evaluation of luminophore attachment efficiency was performed using visiometric analysis in the UV range. The capability of diamonds to retain luminophore collector droplets or films on their surfaces was evaluated using a technique to measure the three-phase limiting wetting angle. The spectral and kinetic characteristics of diamonds and their recovery during the X-ray luminescence separation process were determined using a separator “Polyus-M”. The feasibility of purposefully modifying the spectral characteristics of weakly and anomalously luminescent diamonds through luminophore-containing compositions based on zinc sulfides and zinc orthosilicate has been confirmed through the conducted studies. By considering the criterion of selectivity in the attachment of luminophore emulsion to diamonds and kimberlite minerals, calculated based on the measured surface concentrations of luminophores on the minerals, the optimal ratios between the masses of inorganic luminophore, organic collector, and the aqueous phase of the emulsion were determined. Dispersing agents that offer selective binding of luminophores to diamond crystals were identified, and rational parameters for the composition of the organic collector were established. The temperature range for treating diamond-containing material was defined. As a result of bench testing the modifying agents with the selected composition and conditions for their application in the diamond-containing material treatment cycle before XRF separation, it was confirmed that the recovery of anomalously and weakly luminescent diamonds could exceed 90%, while keeping the yield of kimberlite minerals in the concentrate below 1%.

Copyright of New Building Materials / Xinxing Jianzhu Cailiao is the property of New Building Materials Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study takes tartary buckwheat, highland barley and oats as the main raw materials to analyze and develop a high-fiber noodles premixed powder. The premixed powder is blended as the following proportion: 40% plain flour, 30% tartary buckwheat, 10% highland barley and 20% oat. This proportion gives us 6.94% dietary fiber, 1.9% beta glucan, 0.8% total flavonoids in the premixed powder. Through single factor experiment, combined with the response surface analysis test and taking finished product breakout rate and cooking loss rate and sensory evaluation as a comprehensive index, this study discusses the effects of gluten, salt, sodium carbonate and konjac purified powder on the quality of premixed powder. Results show that the optimal proportion of the compound improver is: 5.4% gluten, 1.3% salt, 0.2% sodium carbonate,and 1.1% konjac refined powder, which makes the processing process of high fiber noodles premixed powder easier and the quality of finished products higher

Heat energy retention and dissipation have become key points of global smart textiles in recent years. This study describes the designing of silicon resin by using a sol–gel process, which acts as the modifying agent for siloxane substrate. The modifying agent was effectively blocked by silicon resin mixed with the ethylene or aluminum bond group, to control the molecular weight. Advanced polymer chromatography confirmed that the number average molecular weight (Mn) of silicon resin is 41,301 g mol−1, the weight average molecular weight (Mw) is 47,982 g mol−1, and the molecular weight distribution is 1.1617, which is relatively narrow. When the addition of vinyl groups is 5%, the silicone resin Mn decreases to 18,906 g mol−1 and Mw decreases to 28,641 g mol−1. When the addition of aluminum bond groups is 5%, the silicone resin Mn decreases to 17,497 g mol−1 and Mw decreases to 27,114 g mol−1. The result of thermogravimetric analysis shows that the pyrolysis temperature rises from 265.43°C to 266.17°C after the ethylene is added to the silicon resin, and the index of heat tolerance increases from 179.14°C to 191.38°C. After the addition of aluminum bond groups, the pyrolysis temperature rises from 265.43°C to 309.37°C, and the index of heat tolerance increases from 179.14°C to 193.09°C, meaning the silicone resin has higher thermal stability. [ABSTRACT FROM AUTHOR]

The effect of sulfur, polymeric petroleum resin and castor oil on the structural and mechanical characteristics of petroleum-based bitumen binders has been studied. On the basis of tar, binders were obtained that meet the requirements for road bitumen. It was noted that vegetable oil is highly effective as a modifying agent of bitumen properties. In samples containing polymeric petroleum resin, sulfur and vegetable oil, changes in some characteristics of bitumen are demonstrated: penetration, ductility, softening point. The fundamental possibility of modifying the properties of oil binders through the use of inexpensive oil products and vegetables oil, and as a result, the increase of hydrocarbon resource base for production of road bitumen through the involvement of alternative sources of raw materials, is shown. [ABSTRACT FROM AUTHOR]

This article aimed to study the effects of chitosan fiber and a newly modifying agent, based on organosolv lignin, on mechanical and thermal performances and the enzymatic degradation of PLA/chitosan biocomposites. A newly modifying agent based on polyacrylic acid-grafted organosolv lignin (PAA-g-OSL) was synthesized via free radical copolymerization using t-butyl peroxide as the initiator. The biocomposites were prepared using an internal mixer and the hot-pressed method at various fiber loadings. The results demonstrate that the addition of chitosan fiber into PLA biocomposites remarkably decreases tensile strength and elongation at break. However, it improves the Young’s modulus. The modified biocomposites clearly demonstrat an improvement in tensile strength by approximately 20%, with respect to the unmodified ones, upon the presence of PAA-g-OSL. Moreover, the thermal stability of the modified biocomposites was enhanced significantly, indicating the effectiveness of the thermal protective barrier of the lignin’s aromatic structure belonging to the modifying agent during pyrolysis. In addition, a slower biodegradation rate was exhibited by the modified biocomposites, relative to the unmodified ones, that confirms the positive effects of their improved interfacial interaction, resulting in a decreased area that was degraded through enzyme hydrolysis.

The problem of prediction of the service life of asphalt concrete surface constructed with modified asphalt concrete application onto a traffic lane is examined. Asphalt concrete behaviour in road surface under the traffic loads was analysed. There were shown The results of experiments and their mathematical analysis of the assessment of standard and modified cold asphalt concrete fatigue life on road surface were shown. The service life of an asphalt concrete surface covered with standard and modified cold asphalt concrete is examined. The prediction has been received with an account of stress relaxation processes in asphalt concrete pavement and unevenness of traffic load application.

Purpose. To study various additives of a domestic production and to estimate expediency of their use for products of transport construction. Methodology. The study was conducted by introducing a superplasticizer and active mineral additives Findings. The complex additive should include effective superplasticizing admix, as well as additives which operate stiffening and hardening kinetics, air retaining substances and defoaming agents, dispersion and fine-dispersion mineral fillers. In recent years organo-mineral modifiers such as superplasticizer - an active mineral additive (microsilica, metakaolin, ash) obtained a wide circulation. Originality. The impact of various additives on the concrete quality is studied. It is found out that the complex additive PLKP deserves the special attention because it allows producing a concrete of very high durabilityand is recommended for use in railroad ties. Thus, the introduction of additives in the concrete can significantly increase the durability and reliability of concrete products. Practical value. Results of the research can be used to improve the reliability and durability of concrete structures. This calls for further researches on the selection of the concrete mixture with complex additive PLKP, as well as adding the active mineral components.

Sodium-montmorillonite (Na-MMT) nanoclay was modified with different concentrations of octadecylamine organic modifying agent at 0.5, 1.0 and 1.5 times the CEC of Na-MMT. Influence of concentration of modifying agent on properties of the organoclays and natural rubber/organoclay nanocomposites was investigated. It was found that the optimum concentration of modifying agent was 1.5 times the CEC of Na-MMT. That is, at this concentration, larger d -spacing of organoclay particles and higher degree of clay dispersion in natural rubber matrix were observed. Larger interlayer d -spacing also caused enhancement of the mechanical properties of the NR/organoclay nanocomposites. Additionally, the NR/organoclay nanocomposites with higher concentration of modifying agent exhibited faster curing reaction with higher crosslink density. Furthermore, the organoclays with larger d -spacing and higher degree of dispersion in the natural rubber matrix exhibited enhancement of the mechanical and dynamic properties and thermal stability of natural rubber/organoclay nanocomposites. [ABSTRACT FROM AUTHOR]

Copyright of Wool Textile Journal is the property of National Wool Textile Science & Technology Information Center and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The problem of prediction of the service life of asphalt concrete surface constructed with modified asphalt concrete application onto a traffic lane is examined. Asphalt concrete behaviour in road surface under the traffic loads was analysed. There were shown The results of experiments and their mathematical analysis of the assessment of standard and modified cold asphalt concrete fatigue life on road surface were shown. The service life of an asphalt concrete surface covered with standard and modified cold asphalt concrete is examined. The prediction has been received with an account of stress relaxation processes in asphalt concrete pavement and unevenness of traffic load application. [ABSTRACT FROM AUTHOR]

A commercial DLS setup was used for simultaneous DLS/SLS analysis of sol growth of titanium and titanium/silicon oxides. The scattering data were analyzed in dynamic and static modes which allowed evaluating particle size and concentration simultaneously. A binary solvent (acetone/ethanol mixture) was introduced which effectively controls monodisperse growth behavior by simply adjusting its ratio. Fixing the solvent composition to the ratio which delayed gelation the most, the effect of the amount of catalyst (acetic acid), hydrolyzing agent (water) and titanium oxide precursor (titanium tetraisopropoxide) on growth kinetics were studied. Taking the advantage of extra functionalities of the catalyst used, acetic acid, i.e., decreasing the reactivity of titanium tetraisopropoxide and increasing the reactivity of tetraethyl orthosilicate, hybrid titanium/silicon oxide growth was also studied. Here, we step-by-step showed that particle size, particle concentration and sol-to-gel transition time of titanium and titanium/silicon oxide systems can be well controlled by adjusting the composition of formulations in ambient conditions. We also showed how practical the laser light scattering is to evaluate even the early onsets of growth profiles long before visual identification of clouding. The findings reported here are particularly important for practical applications of sol-gel technology where the control of particle size/concentration and gelation time is advantageous. Graphical Abstract: [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The flocculation of coal fines using synthetic anionic flocculants based on acrylamide is considered. It is established that acrylamide may compete with water molecules at hydroxyl and carboxyl centers of the coal surface, to form molecular complexes with a hydrogen bond. Thanks to the presence of active polar centers-oxygen and nitrogen atoms-in the copolymer of acrylamide with sodium acrylate, the coal particles that are absorbing the flocculant become more hydrophilic, and consequently the effectiveness of coal flotation is reduced. To improve the flotation of coal fines, a modifying agent is supplied after preliminary flocculation. The modifier employed is Neonol, a product of petroleum processing. HyperChem software is used to confirm that the modifier may be adsorbed on the active centers of the flocculant and coal surface by means of hydrogen bonds. That renders the flocculated coal particles more hydrophobic and thus improves their flotation. This behavior of Neonol modifier is confirmed by gas-chromatographic data regarding the adsorption of chemical compounds on the coal surface and by studying coal flotation in a single-bubble system. If 0.001 kg/t Neonol modifier is used in the flotation of flocculated coal fines, the extraction of the coal's fuel component in the concentrate is increased by 2.0-4.2%, depending on the conditions. [ABSTRACT FROM AUTHOR]

This paper presents the results of studies aimed at developing an adhesion-active composition based low-molecular-weight polyethylene modified by polyacrylic-acid polymer complexes and ɛ-caprolactam with different ratios of components. The optimal composition and amount of the modifying agent were determined based on their effect on the tackiness and adhesive properties of the composition. It is shown that the properties of the developed composition allow it to be recommended for the use as a building mastic and basis for labeling adhesives and compositions for application to polymeric films. [ABSTRACT FROM AUTHOR]

For lack of laboratory and field performance data on stabilization of reclaimed asphalt pavement (RAP) aggregate and stabilized soil (S) for road bases and subbases construction, the influences of RAP/S ratio, cement and fly ash content, modifying agent (MA) on the compact, unconfined compressive strength, indirect tensile strength and water stability of the CIR mixtures were investigated. The experimental results showed that the maximum dry density and the optimum moisture content of the mixture changed significantly with the RAP/S ratio and cement-fly ash content. Unconfined compressive strength, indirect tensile strength and water stability were improved significantly by the addition of MA, and the water stability was improved by nearly 20% on average. Scanning electron microscopy(SEM) images indicated that MA accelerated the hydration of cement-fly ash system. Needle-like AFt and fibrous C-S-H gel were observed in the mixtures, which resulted in the cementation effect among the CIR mixture particles and a more compact microstructure. All these could be the cause of high strength of the CIR mixtures with MA. [ABSTRACT FROM AUTHOR]

The strength and stability of collapsible soils can present problems during construction. To overcome these problems, sulfur cement as a treatment method was developed and evaluated in view of its microstructure, mineralogical composition, physical, thermal, mechanical, hydraulic, and chemical properties. The treated soil was prepared from modified sulfur, sulfur, fly ash, and soil aggregates. Specimens were treated in air, water, and saline solutions at different temperatures, ranging from room temperature to 60°C, and time, ranging from 28 days to one year. After treatment, specimens were tested for their compressive strength. The results indicated that the strength of the treated soil is about three times higher than that stabilized by normal Portland cement. The results of hydraulic conductivity of the treated soils are ranged between 1.46 x 10-13 and 7.66 x 10-11 m/s making it a good candidate for its potential use as stabilizing agent in arid lands. Leachability of sulfur and metal ions from the solidified material was below the norms stated by various environmental agencies. The treated soil offers many advantages as an alternative construction material particularly in situations that require a fast solidification in places of extremely cold, hot climates or corrosion conditions. [ABSTRACT FROM AUTHOR]

The authors provide insight into the problem of selective flotation of fluorite from carbonate-fluorite ores. It is found that oxyhydrate collectors used in combination with sodium fluoride provide rather high level of selectivity in fluoride flotation from poor high-carbonate ores and make it possible to eliminate high-temperature pulp treatment with acceptable reduction in the flotation temperature to 15°C and below. [ABSTRACT FROM AUTHOR]

Abstract: Three different types of new adsorbents modified from wheat straw were synthesized after the reaction between epichlorohydrin and triethylamine by using ethylenediamine (EDA), diethylenetriamine (DETA) and triethylenetetramine (TETA) as modifying agents. The performance of the modified wheat straws (MWS) was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) and elemental analysis. Results showed that the optimal dosages for the three modifying agent (EDA, DETA and TETA) were 3, 4 and 3ml. The optimum synthesis temperature for the three MWS was 80, 85 and 95°C, respectively. The IR spectra of the three MWS were analogical, and nitrogen contents of the MWS were found to be consistent with their adsorption capacity. The pseudo-second-order equation generated the best agreement with the experimental data for adsorption systems. In addition, the adsorption process of the three MWS reached equilibrium at 10–15min. MWS (EDA) demonstrated the largest phosphate capacity than the other MWS. [Copyright &y& Elsevier]

To improve the slag/iron separation problems in CaO–Mg based hot metal desulphurisation, experiments were carried out to generate a more fluid slag and to reduce the amount of hot iron entrapped within the desulphurising slag. The optimised slag modifying agent effectively decreased the melting temperature and viscosity of CaO–Mg based desulphurising slag. The optimised modifying agent has been successfully applied to industrial production. Industrial tests show that the average desulphurisation exceeded 82% when using the 80CaO–15Mg–5CaF2 desulphurising agent at 3·5–4·0 kg t–1, and with an average final S of 0·005%. The skimming time decreased from nearly 12 min to ∼6·5 min. The heat loss during desulphurisation decreased to ∼19°C which is favourable to the subsequent steelmaking process. Average total Fe content in post-desulphurisation slag is 34% with 0·7–0·8 kg t–1 modifying agent, a decrease of ∼30% in iron loss compared with current status. [ABSTRACT FROM AUTHOR]

This article aimed to study the effects of chitosan fiber and a newly modifying agent, based on organosolv lignin, on mechanical and thermal performances and the enzymatic degradation of PLA/chitosan biocomposites. A newly modifying agent based on polyacrylic acid-grafted organosolv lignin (PAA-g-OSL) was synthesized via free radical copolymerization using t-butyl peroxide as the initiator. The biocomposites were prepared using an internal mixer and the hot-pressed method at various fiber loadings. The results demonstrate that the addition of chitosan fiber into PLA biocomposites remarkably decreases tensile strength and elongation at break. However, it improves the Young's modulus. The modified biocomposites clearly demonstrat an improvement in tensile strength by approximately 20%, with respect to the unmodified ones, upon the presence of PAA-g-OSL. Moreover, the thermal stability of the modified biocomposites was enhanced significantly, indicating the effectiveness of the thermal protective barrier of the lignin's aromatic structure belonging to the modifying agent during pyrolysis. In addition, a slower biodegradation rate was exhibited by the modified biocomposites, relative to the unmodified ones, that confirms the positive effects of their improved interfacial interaction, resulting in a decreased area that was degraded through enzyme hydrolysis. [ABSTRACT FROM AUTHOR]

Abstract: To select effective modifying agent for Al–Si alloys, in addition to conventional parameters such as the crystal structure and lattice constant, the mixing enthalpy, which was calculated by the Miedema model, was newly considered. The large negative value of mixing enthalpy was counted as a new parameter. According to the result of calculation, four elements, including Sr, Y, Sm and Gd, which have large negative mixing enthalpies with Si, were selected as modifying agent for eutectic Si crystals. It was observed that these elements result in the modification of the eutectic Si crystals and that the eutectic depression of the modified alloy is larger than 6K. [Copyright &y& Elsevier]

2-(Methacryloyloxy) ethylacetoacetate (MEEAH) was used as stabilyzing agent to control the chemical reactivity of Ti and Zr monomeric alkoxides in a Si—Ti—Zr sol. The organic and inorganic polymerizations were carried out simultaneously. The organic polymerization was performed using benzoyl peroxide as the initiator. The inorganic polymerization was done via the sol-gel process. The polymerization was studied by several spectroscopic techniques, including Fourier Transform Infrared (FTIR), UV-Vis, 29Si NMR, Small Angle X-ray Scattering (SAXS) and X-ray diffraction (XRD). Theoretical calculation and experimental results showed that MEEAH acted as a monodentate ligand, mainly. This led to a high condensation extent of the Si species in the sol. A short range order gel was obtained, according to the SAXS results. The Si—O—Ti and Si—O—Zr bonds were detected by FTIR. The bonds remained stable, because a sample calcined at 1173 K was amorphous according to the XRD results, indicating structural homogeneity. [ABSTRACT FROM AUTHOR]

Two chemical routes were employed to prepare Si−Ti polymers, using acetylacetone (acacH) and acetic acid (HOAc) as modifying agents. The homogeneous and transparent sols were studied at different aging times. The characterization techniques were29Si NMR, FTIR, UV-Vis and TGA. When HOAc was used, the oligomeric species in the first stages of polymerization were assigned by29 Si NMR. The Ti−O−Si bond vibration was detected by FTIR in the 950–960 cm−1 region. UV-Vis spectroscopy showed bands of acac bonded to Ti at 300 nm and 365 nm, and OAc− bonded to Ti was found at 320 nm. The TGA study allowed the establishment of the xerogel formulas. [ABSTRACT FROM AUTHOR]