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EN
In this study, the effect of MnCl2 on scheelite flotation with sodium oleate (NaOL) as a collector and sodium silicate as a depressant was assessed by a combination of flotation experiments, Fouriertransform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and solution chemistry. The flotation experiments confirmed that the addition of MnCl2 before sodium silicate showed an adverse effect on flotation and the recovery of scheelite gradually decreased as the amount of MnCl2 was increased. When MnCl2 was added afte r sodium silicate, the recovery of scheelite gradually increased with an increase in the amount of MnCl2. The results of FTIR, XPS, and solution chemistry indicated that MnCl2 acted on the surface of scheelite in the form of manganese ions. When MnCl2 was added before sodium silicate, manganese ions adsorbed on the surface of scheelite reacted with sodium silicate to form a hydrophilic silicate, which covers the surface of scheelite and blocks the adsorption of NaOL. However, when MnCl2 was added after sodium silicate, manganese ions are continued to be adsorbed on the surface of scheelite, which increases the cations on the surface of scheelite, and hence the condition becomes conducive for the interaction between scheelite and NaOL.
EN
The paper presents the results of preliminary research on the application of olivine moulding sands with hydrated sodium silicate containing 1.5 % wt. of binder to perform ecological casting cores in hot-box technology using a semi-automatic core shooter. The following parameters were used in the process of core shooting: initial shot pressure of 6 bar, shot time 3 s, the temperature of the core-box: 200, 250 and 300°C and the core curing time: 30, 60, 90, 120 and 150 s. The matrix of the moulding mixture was olivine sand, and the binder of the sandmix was commercial, unmodified hydrated sodium silicate with molar module SiO2/Na2O of 2.5. In one shot of the automatic core-shooter were formed three longitudinal specimens (cores) with a dimensions 22.2×22.2×180 mm. The samples obtained in this way were subjected to the assessment of the influence of the shooting parameters, i.e. shooting time, temperature and curing time in core-box, using the following criteria: core box fill rate, mechanical strength to bending RgU, apparent density, compaction degree and susceptibility to friability of sand grains after hardening. The results of trials on the use of olivine moulding sands with hydrated sodium silicate (olivine SSBS) in the process of core shooting made it possible to determine the conditions for further research on the improvement of inorganic hot-box process technology aimed at: reduction of the heating temperature and the curing time. It was found that correlation between the parameters of the shooting process and the bending strength of olivine moulding sands with sodium silicate is observed.
EN
The flotation separation of barite from calcite using sodium dodecyl sulfate (SDS) as the collector and sodium silicate (SS) as the depressant has been concretely studied in this paper. The results show that SDS has high collecting ability for both barite and calcite and that the flotation separation of barite from calcite cannot be achieved by using SDS alone. The depressant sodium silicate has a selective depression effect on calcite by the control of the pulp pH at 9.0 in the presence of SDS. Through locked cycle tests, a concentrate containing 95.54% BaSO4 can be obtained from an actual ore containing 24.5% BaSO4, with a recovery of 86.11%. The zeta potential measurements, adsorption analysis and infrared spectrum studies reveal that the pre-adsorption of sodium silicate strongly favors the adsorption of SDS on the calcite surface and adversely affects SDS adsorption on the barite surface. This property is the reason for the selective depression of SS on calcite.
EN
The grade of titanium dioxide (TiO2) from Panzhihua titanium concentrate (defined as the ilmenite rough concentrate in this paper) is generally around 47%. The high impurity content in the titanium concentrate causes difficulties for its successive use in the production of titania pigment. Further purification of the ilmenite concentrate will make it more useful for industrial use. In this study, a further cleaning process of the ilmenite rough concentrate is conducted using sodium silicate as the depressant, and the function of sodium silicate is determined by flotation, absorption measurements, Zeta potential measurements, and infrared spectral analysis. The results indicate that an ilmenite concentrate with a TiO2  grade of 50.37% can be achieved from 46.78% according to the stages on the flowsheet-one roughing, three cleaning and one scavenging-under the optimal conditions, and can also reflect the advantages of the excellent selectivity of sodium silicate. Sodium silicate can hinder the adsorption of salicylhydroxamic acid (SHA) on the titanaugite surface but has almost no effect on ilmenite. Multiple methods comprehensively confirm that sodium silicate provides a good selective depression effect for the further purification of the ilmenite rough concentrate.
EN
This study is an attempt to determine by Hot Distortion Test (HDT) the impact of physical methods of hardening inorganic binders in the moulding sands on phenomena caused by influence of thermal energy from heating elements with a temperature of 900°C +/- 10°C. Medium silica sand-based moulding mixtures were densified and then hardened using two physical methods: microwave heating at a frequency of 2.45 GHz or classical drying at a temperature of 110°C. Sodium silicate bonded sand (SSBS) with five unmodified kinds of hydrated sodium silicates subjected to two different types of hardening method were assessed in terms of their behaviour in high temperature. Thermal behaviour by means of deformation measurement was carried out with a modified Hot Distortion Test (mHDT). Due to this advanced, but unstable by appropriate standards Hot Distortion Test gives an opportunity to measure thermoplastic deformations (L) in moulding sands in many aspects, such as time of annealing. Research carried out in this way exposed differences between inorganic binders with molar module ranging from 3.4 to 2.0. It was established that deformations under the influence of high temperature last the longest in SSBS containing binders with molar module ranging from 3.4 to 2.9. Similarly, for these types of moulding sands the method of hardening the binder is found to be essential for increasing/decreasing the rate of thermoplastic deformations during the annealing of samples. The samples of SSBS made with binders with molar module from 2.5 to 2.0 are found to be excessively susceptible to thermoplastic deformation as a result of heating them in high environmental temperature presence.
EN
Moulding sands containing sodium silicate (water-glass) belong to the group of porous mixture with low resistance to increased humidity. Thanks to hydrophilic properties of hardened or even overheated binder, possible is application of effective methods of hydrous reclamation consisting in its secondary hydration. For the same reason (hydrophilia of the binder), moulds and foundry cores made of high-silica moulding sands with sodium silicate are susceptible to the action of components of atmospheric air, including the contained steam. This paper presents results of a research on the effect of (relative) humidity on mechanical and technological properties of microwave-hardened moulding mixtures. Specimens of the moulding sand containing 1.5 wt% of sodium water-glass with module 2.5 were subjected, in a laboratory climatic chamber, to long-term action of steam contained in the chamber atmosphere. Concentration of water in atmospheric air was stabilized for 28 days (672 h) according to the relative humidity parameter that was ca. 40%, 60% and 80% at constant temperature 20 °C. In three cycles of the examinations, the specimens were taken out from the chamber every 7 days (168 h) and their mechanical and technological parameters were determined. It was found on the grounds of laboratory measurements that moulds and cores hardened with microwaves are susceptible to action of atmospheric air and presence of water (as steam) intensifies action of the air components on glassy film of sodium silicate. Microwave-hardened moulding sands containing sodium silicate may be stored on a long-term basis in strictly determined atmospheric conditions only, at reduced humidity. In spite of a negative effect of steam contained in the air, the examined moulding mixtures maintain a part of their mechanical and technological properties, so the moulds and foundry cores stored in specified, controlled conditions could be still used in manufacture.
EN
The paper presents the results of preliminary research on the use of silica sands with hydrated sodium silicate 1.5% wt. of binder for the performance of eco-friendly casting cores in hot-box technology. To evaluate the feasibility of high quality casting cores performed by the use of this method, the tests were made with the use of a semiautomatic core shooter using the following operating parameters: initial shooting pressure of 6 bar, shot time 4 s and 2 s, core-box temperature 200, 250 and 300 °C and core heating time 30, 60, 90 and 150 s. Matrixes of the moulding sands were two types of high-silica sand: fine and medium. Moulding sand binder was a commercial, unmodified hydrated sodium silicate having a molar module SiO2/Na2O of 2.5. In one shot of a core-shooter were made three longitudinal samples (cores) with a total volume of about 2.8 dm3. The samples thus obtained were subjected to an assessment of the effect of shooting parameters, i.e. shooting time, temperature and heating time, using the criteria: core-box fill rate, bending strength (RgU), apparent density and surface quality after hardening. The results of the trials on the use of sodium silicate moluding sands made it possible to further refine the conditions of next research into the improvement of inorganic warm-box/hot-box technology aimed at: reduction of heating temperature and shot time. It was found that the performance of the cores depends on the efficiency of the venting system, shooting time, filling level of a shooting chamber and grains of the silica matrix used.
EN
This study shows the results of the investigation of the strength performance, and residual strength of a single component inorganic binder system Cast Clean S27®. The study was conducted using three different foundry sand sources in South Africa. Sample A is an alluvial coastal sample, sample B is an alluvial riverbed sample and Sample C is a blasted sample from a consolidated quartzite rock. The binder was also cured using three different curing mechanisms. The aim of the investigation was to determine the variation of strength performance and residual strength between the different South African sand sources based upon the physical and chemical properties of the sand sources. The moulding sand was prepared using three possible curing mechanisms which are carbon dioxide curing, ester curing and heat curing. The strength measurements were determined by bending strength. Sample A and sample C sand had good strength development. Sample B sand had inferior strength development and excellent high temperature residual strength. The study showed that the single component inorganic binders have good strength development and low residual strength. The silica sand properties have major contributing factors on both strength development and residual strength. The degree of influence of silica sand properties on strength performance and residual strength is dependent on the time of curing and method of curing.
EN
In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within 100 to 1200°C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.
EN
In the paper, a research on effects of baking temperature on chromite sand base of moulding sands bonded with sodium silicate is presented. Pure chromite sand and its chromite-based moulding sand prepared with use of sodium silicate were subjected to heating within 100 to 1200 °C. After cooling-down, changes of base grains under thermal action were determined. Chromite moulding sand was prepared with use of 0.5 wt% of domestic made, unmodified sodium silicate (water-glass) grade 145. After baking at elevated temperatures, creation of rough layer was observed on grain surfaces, of both pure chromite sand and that used as base of a moulding sand. Changes of sand grains were evaluated by scanning microscopy and EDS analyses. It was found that changes on grain surfaces are of laminar nature. The observed layer is composed of iron oxide (II) that is one of main structural components of chromite sand. In order to identify changes in internal structure of chromite sand grains, polished sections were prepared of moulding sand hardened with microwaves and baked at elevated temperatures. Microscopic observations revealed changes in grains structure in form of characteristically crystallised acicular particles with limited magnesium content, intersecting at various angles. EDS analysis showed that these particles are composed mostly of chromium oxide (III) and iron oxide (II). The temperature above that the a.m. changes are observed in both chromite-based moulding sand and in pure chromite sand. The observed phenomena were linked with hardness values and mass of this sand.
EN
In the paper, presented is a research on effectiveness of absorbing electromagnetic waves at frequency 2.45 GHz by unhardened moulding sands prepared of three kinds of high-silica base and a selected grade of sodium silicate. Measurements of power loss of microwave radiation (Pin) expressed by a total of absorbed power (Pabs), output power (Pout) and reflected power (Pref) were carried-out on a stand of semiautomatic microwave slot line. Values of microwave power loss in the rectangular waveguide filled with unhardened moulding sands served for determining effectiveness of microwave heating. Balance of microwave power loss is of technological and economical importance for manufacture of high-quality casting moulds and cores of various shapes and sizes. It was found that relative density influences parameters of power output and power reflected from samples of moulding sand placed in a waveguide. Absorption expressed by the parameter Pabs is not related to granularity of high-silica base: fine, medium and coarse. It was found that the semiautomatic microwave slot line supports evaluation of effectiveness of microwave absorption on the grounds of power loss measurements and enables statistic description of influence of relative density of the sandmix on penetration of electromagnetic waves in unhardened moulding sands.
13
Content available remote Podstawowe badania wytrzymałościowe zaprawy geopolimerowej
PL
W artykule omówiono badania nad materiałami geopolimerowymi w budownictwie. Przedstawiono również wyniki badań zaprawy geopolimerowej na bazie popiołu lotnego aktywowanego mieszaniną wodnego roztworu wodorotlenku sodu i krzemianu sodu. Do badań przygotowano dwie serie próbek, które różniły się stężeniem NaOHsol. Próbki zaprawy poddano badaniom wytrzymałości na zginanie oraz ściskanie (zgodnie z normą PN-EN 196-1 2006) po 7 i 28 dniach. Otrzymane wyniki posłużą jako podstawa do dalszych badań nad zastosowaniem geopolimerów w budownictwie.
EN
The article discusses research on geopolymer materials using in civil engineering. It also shows the results of research on mortar geopolymers based on fly ash activated with a mixture of aqueous solution of sodiumhydroxide and sodiumsilicate. There were tested two sets of samples which differed in concentration of NaOHsol. The samples of mortar were tested on flexural strength and compressive strength (according to PN-EN 196-1 2006) after 7 and 28 days. The results serve as a basis for further research on the use of geopolymers in construction.
PL
W artykule zostało przedstawione zastosowanie szkła wodnego w betonie z kruszywem z recyklingu i elementów żelbetowych z niego wykonanych. Celem badań było zaprojektowanie dwóch mieszanek betonowych z kruszywem z recyklingu i wykorzystanie ich w elementach próbnych. Jedna z mieszanek była modyfikowana szkłem wodnym. Zaprojektowane betony miały bardzo zbliżone wyniki po 28 dniach i uzyskały taką samą klasę betonu C35/45. Szkło wodne przyśpieszyło szybkość wiązania betonu bez zmiany ich wartości, zauważalny szybszy przyrost wytrzymałości na ściskanie oraz rozciąganie przy zginaniu. Zastosowanie szkła wodnego w elementach żelbetowych nie wpłynęło na siłę niszczącą belek. Dodatek szkła wodnego wpłynął pozytywnie na zachowanie się belek żelbetowych przy 2% stopniu zbrojenia.
EN
The article was presented to the use of sodium silicate in concrete with recycled aggregate and concrete elements made of it. The aim of this study was to design two concrete mixtures with aggregates from recycling and use them in the elements of trial. One of the mixtures was modified sodium silicate. Designed concrete results were very similar at 28 days and received the same concrete class C35/45. Sodium silicate bonding concrete accelerated rate without changing their values, a noticeable increase in higher compressive strength and tensile strength. The use of sodium silicate in concrete elements had no effect on the destructive power of the beams. The addition of sodium silicate had a positive influence on the behavior of reinforced concrete beams with 2% degree of reinforcement.
18
Content available Granulacja krzemianów sodu metodą prasowania
PL
W artykule opisano wstępne wyniki badań granulacji krzemianów sodu metodą prasowania. Prowadzone badania miały na celu sprawdzenie możliwości uzyskania z pylistych surowców granulatów o określonym rozkładzie ziarnowym. W badaniach laboratoryjnych stosowano pyliste krzemiany sodu o module 2,0-3,3 SiO2mol/ Na2Omol. Prowadzono je w prasie matrycowej firmy AWPMA. W ramach badań wyznaczono wpływ ciśnienia prasowania na stopień zagęszczenia oraz określono optymalne ciśnienie prasowania badanych krzemianów. Uzyskano produkty charakteryzujące się większym ziarnem i wyższymi gęstościami nasypowymi. Otrzymane wyniki umożliwiają dobór urządzeń przemysłowych do granulacji dwukrzemianów sodu jako głównego produktu, z jednoczesną możliwością otrzymania granulowanych krzemianów o innych module.
EN
The preliminary results of studies of sodium silicate granulation by pressing method was described. The studies was conducted to test the possibility of obtaining the powdery raw material granules with a specific particle size distribution. In laboratory studies powdered sodium silicates with module of 2 up to 3.3 SiO2 moles/Na2O moles were used. They were investigated in the AWPMA's matrix press. The studies determined the impact of compaction pressure on the densification degree and the optimal compression pressure of tested silicates was determined. The products of larger grains and higher bulk densities were obtained. The results allow the selection of industrial equipment for granulation of sodium disilicates as the main product and the possibility of obtaining granulated silicates of other module at the same time.
EN
Dispersion properties of colloidal silica were studied at subsequent stages of silica sols preparation. Dilute sols were obtained from solutions of sodium silicate by ion exchange method. In them SiO2 particles were built up and next the sols were concentrated. The concentrations of the sols in which SiO2 particles were built-up ranged from 5.89 to 6.44 wt. % SiO2, while the mean concentrations of the sols which were added into the heel sols were 3.28 and 6.20 wt. % SiO2. The particle size distributions were measured by DLS, while the contribution of the ionic form of silica was determined by the colorimetric method on the basis of the intensity of the yellow colour coming from the heteropolycomplexes of silicomolybdic acid.
PL
W pracy badano charakterystykę dyspersyjną krzemionki koloidalnej w kolejnych etapach otrzymywania zolu kwasu krzemowego. Rozcieńczone zole otrzymywano z roztworów krzemianu sodu metodą wymiany jonowej, nabudowywano w nich cząstki SiO2 i następnie zatężano. Stężenia zoli, w których nabudowywano cząstki zawierały się w przedziale 5,89÷6,44 % wag. SiO2, a zole stosowane do nabudowania miały średnie stężenia 3,28 i 6,20 % wag. SiO2. Rozkłady wielkości cząstek mierzono techniką DLS, a udział formy jonowej krzemionki oznaczano kolorymetrycznie mierząc intensywność żółtego zabarwienia heteropolikompleksu kwasu molibdenowo–krzemowego.
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