Autor: Wen, S. - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Flocculation/dispersion of hematite with caustic digested starch
Autorzy:: Tang, M.
Wen, S.
Powiązania:: https://bibliotekanauki.pl/articles/109542.pdf
Data publikacji:: 2015
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: starch
alkali-digestion
flocculation
dispersion
Opis:: Selective flocculation of hematite with starch is a process well-known in practice. However, the separation of hematite from other minerals depends strongly on the methods of starch digestion performed either as heating-digestion or alkali-digestion (different type and dosage of alkali). The purpose of this study is to identify possible influence of the alkali-digested starch on flocculation of ultra-fine hematite when the starch was digested at different concentrations of sodium hydroxide at room temperature. Adsorption of starch digested with sodium hydroxide at different concentration on hematite was investigated by abstraction and co-precipitation tests. Turbidities tests, settling rates, flocculation/dispersion measurement and Fourier transform infrared spectroscopic analysis (FTIR) have also been conducted. Based on the results of the above mentioned tests it is suggested that the flocculating power of caustic digested starch towards fine particles may be significantly weakened, while its dispersing ability starts to play a role instead, if the concentration of sodium hydroxide is high enough in starch digestion. When the weight ratio of NaOH /starch is lower than 2, incomplete gelatinization of starch granules may lead to coagulation of fine particles of hematite mostly due to non-selective electrostatic attraction. The weight ratio of NaOH /starch from 2 to 4 helps to flocculate mineral surfaces selectively and efficiently, assuring a complete digestion of starch granules and a small amount of acidic functional products on the starch chain. However, much smaller and homogenous short-chain granules resulting from higher concentration of sodium hydroxide (the weight ratio of NaOH /starch is more than 4) used to digest starch may weaken the flocculating capacity of the caustized starch for hematite and lead to its dispersion.
Źródło:: Physicochemical Problems of Mineral Processing; 2015, 51, 2; 477-489
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Caustic-digested starch and its adsorption on hematite
Autorzy:: Tang, M.
Wen, S.
Tong, X.
Powiązania:: https://bibliotekanauki.pl/articles/110383.pdf
Data publikacji:: 2017
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: starch
digestion
alkali
carboxylic group
Opis:: Adsorption characteristics on hematite of caustic-digested starch by sodium hydroxide or potassium hydroxide were investigated through a series of tests, like adsorption tests, paste titration and zeta potentials measurement, scanning electron microscope measurement (SEM) and Fourier transform infrared spectroscopic analysis (FTIR) as well. An attempt was made in order to identify the possible effects of starch digested with alkali at different concentrations on its adsorption on mineral surfaces. All results pointed out that a different amount of carboxyl groups in the starch gel were harvested from alkali-digestion as a function of concentrations of sodium hydroxide or potassium hydroxide; more acidic groups were produced if higher concentrations of alkali were added. These carboxyl groups may contribute the acid/base interaction of the caustic-digested starch on hematite. Also, different concentrations of sodium hydroxide to digest starch seem to induce different degrees of its gelatinization from the SEM results, partially attributing to a wide range of its adsorption capacities on mineral surfaces. The optimum adsorption density of the caustic-digested starch on mineral surfaces, 9.87 mg/g hematite for sodium hydroxide and 10.51 mg/g hematite for potassium hydroxide, respectively, was achieved at the weight ratio of starch to sodium/potassium hydroxide as 1:2.
Źródło:: Physicochemical Problems of Mineral Processing; 2017, 53, 1; 69-81
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: Process improvement and kinetic study on copper leaching from low-grade cuprite ores
Autorzy:: Bai, S.
Fu, X.
Li, C.
Wen, S.
Powiązania:: https://bibliotekanauki.pl/articles/109660.pdf
Data publikacji:: 2018
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: cuprite
dissolution kinetics
sulfuric acid leaching
SCM
Opis:: Process improvement and kinetic study on copper leaching from low-grade cuprite ores in sulfuric acid solution are presented in this paper. Effects of major leaching parameters on copper leaching efficiency are determined. The results indicate that copper minerals in the raw ores are mainly cuprites. The reaction rate of this ore increases with an increase in temperature, reaction time, sulfuric acid concentrations and decrease in the particle size of ore. Leaching of about 92.5% of copper is achieved using 0.125-0.074 mm ore particle size at a reaction temperature of 353 K for 180 min reaction time with 150 g/dm3 sulfuric acid. The solid/liquid ratio was maintained constant at 1:15. Leaching kinetic indicates experimental data complies with shrinking core mode (SCM). It is found in the study that agitation rate is not an influential factor on leaching rate and that the dissolution rate is controlled by surface chemical reaction. The average activation energy of the process is determined to be 45.28 kJ mol-1, and the reaction order of H2SO4 is 0.8093.
Źródło:: Physicochemical Problems of Mineral Processing; 2018, 54, 2; 300-310
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Influence of synergistic effect between dodecylamine and sodium oleate on improving the hydrophobicity of fluorapatite
Autorzy:: Cao, Q.
Luo, B.
Wen, S.
Cheng, J.
Powiązania:: https://bibliotekanauki.pl/articles/109587.pdf
Data publikacji:: 2017
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: fluorapatite
hydrophobicity
synergistic effect
mixed collector
Opis:: The influence of synergistic effect between dodecylamine (DDA) and sodium oleate (NaOl) on the hydrophobicity of fluorapatite (FA) was investigated with contact angle, surface tension, XPS and zeta potential studies. The role of pH and the mixing ratio of surfactants on the synergistic behavior were considered. Basing on the contact angle results the suitable pH for the NaOl-DDA mixture was pH 9.5. A further study indicated that the 3:7 DDA-NaOl mixtures could notably improve the contact angle comparing to that only with DDA or NaOl. In the solution of this mixture, the DDA cation and DDA molecule both adsorb at the FA surface as revealed by the XPS spectra results. The zeta potential analysis further suggested that the adsorption of oleate at the FA surface was also improved. The presence of DDA cation and DDA molecule was expected to result in a uniform packing of surfactants at the FA surface.
Źródło:: Physicochemical Problems of Mineral Processing; 2017, 53, 1; 42-55
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: The surface features of activated stibnite surface with copper or lead ion
Autorzy:: Cao, Q.
Huang, Y.
Zou, H.
Wen, S.
Powiązania:: https://bibliotekanauki.pl/articles/110393.pdf
Data publikacji:: 2018
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: stibnite
flotation
activation
active layer
Opis:: Cu2+ and Pb2+ are widely used as activators for the flotation of stibnite. In this work, by the treatment of Cu2+ or Pb2+, the activation product and the thickness of activation layer on the stibnite surface were both investigated. Based on the flotation results, zeta potential analysis and X-ray photoelectron spectroscopy (XPS) study, it was found that Cu2+ was reduced to Cu+ at the stibnite surface and a layer of Cu2S was formed at the surface. While, a PbS layer presenting at the stibnite surface is responsible for the activation flotation of stibnite with Pb2+. Time of flight secondary ion mass spectrometry (TOF-SIMS) analysis further implies that, when stibnite was activated with 5×10-5 mol/dm3 of CuSO4 or Pb(NO3)2, the thickness of Cu2S layer on the Cu-activated surface was close to 2.7 nm, while the thickness of PbS layer was about 1.8 nm on the Pb-activated surface.
Źródło:: Physicochemical Problems of Mineral Processing; 2018, 54, 3; 763-770
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Effect of pH on surface characteristics and flotation of sulfidized cerussite
Autorzy:: Feng, Q.
Wen, S.
Zhao, W.
Liu, J.
Liu, D.
Powiązania:: https://bibliotekanauki.pl/articles/110234.pdf
Data publikacji:: 2016
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: cerussite
sulfidization
excessive sulfide ions
pH
surface analysis
Opis:: The effect of pH on surface characteristic and flotation of sulfidized cerussite was studied by micro-flotation tests, dissolution experiments, scanning electron microscopy (SEM) energy dispersive spectrometer (EDS), and X-ray photoelectron spectroscopy (XPS). The micro-flotation tests demonstrated that higher recovery of cerussite was achieved in acidic solutions than that in alkaline solutions. Despite the addition of high collector concentrations, cerussite flotation did not improved in alkaline solutions. The dissolution performance of sulfide-treated cerussite at different pH values indicated that the lead sulfide layer on the surface of sulfide-treated cerussite could exist in acidic solutions and it was more stable at acidic pH than in alkaline solutions. This finding was proved by the SEM-EDS and XPS analyses.
Źródło:: Physicochemical Problems of Mineral Processing; 2016, 52, 2; 676-689
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Investigation of leaching kinetics of cerussite in sodium hydroxide solutions
Autorzy:: Feng, Q.
Wen, S.
Wang, Y.
Zhao, W.
Deng, J.
Powiązania:: https://bibliotekanauki.pl/articles/110621.pdf
Data publikacji:: 2015
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: cerussite
sodium hydroxide
leaching
kinetics
activation energy
Opis:: The leaching kinetics of cerussite in alkaline medium was investigated with respect to experimental variables such as sodium hydroxide concentration, temperature, particle size and stirring speed. The results showed that leaching reagent concentration and reaction temperature exerted significant effects on the extraction of lead, whereas particle size and stirring speed exhibited a relatively moderate effect on the leaching rate. The leaching process followed the kinetic law of the shrinking core model, and the dissolution rates were controlled by the surface chemical reaction with an apparent activation energy value of 43.79 kJ/mol. A corresponding dissolution kinetic equation was also proposed to describe the dissolution reaction. The results indicated that sodium hydroxide could be used as an effective leaching reagent for extracting lead from cerussite.
Źródło:: Physicochemical Problems of Mineral Processing; 2015, 51, 2; 491-500
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 8.

Tytuł:: Copper adsorption reaction rate and ion exchange ratio during the copper activation of sphalerite
Autorzy:: Liu, J.
Luo, D.
Huang, L.
Wang, Y.
Wen, S.
Powiązania:: https://bibliotekanauki.pl/articles/110651.pdf
Data publikacji:: 2018
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: sphalerite
copper activation
solution chemistry
ion exchange ratio
reaction rate
Opis:: A theoretical analysis method of the solution chemistry characteristic of Cu(II) at various pH values was developed. Using such method, the existence form of Cu species and their proportions in aqueous solution can be clearly determined. After that, the copper adsorption and ion exchange ratio (E) during the copper activation of sphalerite were investigated. The results indicated that the copper activation of sphalerite can be divided into two stages, i.e., the fast activation stage (t ≤4 min) and slow activation stage (t >4 min). The general form of the copper adsorption rate was determined as ΓCu=K1ln(t) +Γ1, which is confirmed by the data fitting of the fast activation stage. The lower activation pH results in higher ion exchange efficiency for Cu substituting Zn. For a strong acid pH of 4.1, the E maintains about 1:1 in the entire activation time range and is not dependent on the activation time. However, the value of E is greater than 1 under weak acidic (pH=6.2) and alkaline (pH=9.1) pH conditions and it significantly depends on the activation time. For such conditions, E decreases with increase in the activation time, which supports the ion exchange mechanism, but within short activation time, it is not a 1:1 ion exchange process.
Źródło:: Physicochemical Problems of Mineral Processing; 2018, 54, 2; 377-385
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Flotation behaviour and surface characteristic of anosovite in a sodium oleate solution
Autorzy:: Wang, Y.
Wen, S.
Zhang, J.
Wu, D.
Xian, Y.
Shen, H.
Powiązania:: https://bibliotekanauki.pl/articles/110766.pdf
Data publikacji:: 2017
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: anosovite
sodium oleate
flotation
adsorption
Opis:: Properties of anosovite in titanium slag, anosovite flotation response in a collector solution of sodium oleate, and adsorption behaviour of sodium oleate on the mineral surface were studied in the present work using XRD, Raman spectra, flotation tests, zeta potential analysis, FTIR and XPS. The results show that the anosovite crystal contains magnesium, and its chemical composition is Mg0.09Ti2.91O5. The chemical bonds on the anosovite surface mainly comprise Ti-O bonds. Micro-flotation tests indicate that anosovite has better floatability at a wide pH range and the recovery reaches 88% at pH=6, when the dosage of sodium oleate is only 4·10−6 mol/dm3. The point of zero charge of anosovite was determined near pH 3.2 by the zeta potential measurement. In the flotation process, chemical adsorption occurs between the carboxyl of sodium oleate and the titanium sites on the anosovite surface.
Źródło:: Physicochemical Problems of Mineral Processing; 2017, 53, 2; 714-723
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 10.

Tytuł:: Efficient sulfidization of lead oxide at high temperature using pyrite as vulcanizing reagent
Autorzy:: Zheng, Y.-X.
Lv, J.-F.
Wang, H.
Wen, S.-M.
Huang, L.
Powiązania:: https://bibliotekanauki.pl/articles/110351.pdf
Data publikacji:: 2018
Wydawca:: Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:: lead oxide
sulfidization roasting
pyrite
reaction mechanism
TG
Opis:: A sulfidization roasting-flotation process was usually viewed to be effective in treating the refractory oxide ore. In this paper, pyrite was proposed to be applied as a potential vulcanizing reagent to transform PbO or its surface to PbS based on feasibilities of technology and economy. The evolution process, phase and characteristics of crystal growth were investigated by TG, XRD and SEM-EDS, respectively, to interpret the interaction mechanism of lead oxide and pyrite at high temperature. It was found that the decomposition process of pyrite under argon atmosphere was a slow process of sulfur released from FeS2 to FexS, which made the process easier to be controlled. When PbO was introduced into the system, the initial solid-solid (PbO-FeS2) reaction and prevailing solid-gas (PbO-S2(g)) reaction occurred at about 500 °C and 700 °C, respectively. Combined with the SEM-EDS analyses results, the optimal temperature for the sulfidization of PbO should be in the range of 700-750 °C.
Źródło:: Physicochemical Problems of Mineral Processing; 2018, 54, 2; 270-277
1643-1049
2084-4735
Pojawia się w:: Physicochemical Problems of Mineral Processing
Dostawca treści:: Biblioteka Nauki

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