قائمة الطعام
The present work aimed to achieve valorization of Albian sands for the preparation of sodium silicates that are commonly used as a precursor to prepare silica gel. A siliceous sand sample was ...
In this research, the storage performance of sodium silicate-bonded sand core was significantly improved by adding compound additives, including micro-silica powder, PVB ethanol solution and cement. The orthogonal test determined that the optimal addition percentage for sodium silicate binder, micro-silica powder, PVB ethanol solution and …
The levels o f sodium silicate were kept fixed at 2. 5%, 3.5% and 4.5% of silica sand, af ter consulting the literature [2,8] and some of the dom estic foundries. Sodium silicate
of Basrah. . Abstract: In this study, a mix ture of (sand and sodium silicate (ratio 4:1) was composed, where sodium silicate is used as a bindi ng agent, and put in an furnace at different ...
Compared with sand samples containing 2% unmodified sodium silicate and 1% silica fume, the hot strength, 4-h tensile strength and 24-h tensile strength of …
Chemical compositions of silica sands by X-ray fluorescence are shown in Table 1. The amount of SiO 2 ranged from 88.80% to 97.40%. Silica content plays an important role in the production of pure sodium silicates from sands. Al 2 O 3 and Fe 2 O 3 reached 5.88% and 2.33%, respectively, together with small amounts of K and Mg …
The residues collected after each process were separated and weighed to calculate the percentage yield of sodium silicate. The collected silica residues are represented as R x/y, where R = residue (%), x = time (h), and y = temperature (°C). The yield of sodium silicate was calculated using equation (1): (1) Y i e l d (%) = 100 − [W e i …
A sequential extraction under these conditions can successfully attain an extraction efficiency of 70% of the silica. Subsequently, the sodium silicate derived from the bottom ash was used to ...
3. Results 3.1. Raw material characterization Fig. 1. Representative scheme of the attack of sand Sx by solution D1. 3.1.1. Silica sand The size distribution of silica grain used for the experimentation is shown in Fig. 2. The different grain size distributions (d50) are 250 μm, 340 μm and 560 μm respectively for S1, S2 and S3.
CO 2-hardening is the most common hardening method in preparing sodium silicate-bounded sand core [12]. In China, only about 30% of SS-WFS can be reused through dry and wet regeneration [12, 14] to reduce the treatment cost of foundry and sodium silicate waste sand [15, 16]. However, with the accumulation of pollutants on the surface of …
Abstract. This paper is concerned with the mechanism of the reaction between sodium carbonate and silica sand at 874° to 1022deg;C. A reaction path which evolves in four stages, i.e ...
Conventionally, the reaction of silica sand with soda ash at elevated temperatures of 1000–1400 °C forms water glass, which is crushed and digested with steam under pressure to obtain sodium silicate of the desired density (Friedman, 1948). ... The highest percentage of sodium silicate extraction was 43.6% resulting from water …
This binder consists of three components: liquid mixture of silicates (1.8–2.5%), highly mineralized activators (0.1–1.0%), and, if necessary, mineral material …
Sodium silicate powders with different SiO 2 /Na 2 O (silica modulus) were characterized by solubility rate, pH, and chemical structure (by 29 Si MAS-NMR) and compared in the preparation of one-part (or dry-mix) alkali-activated blast furnace slag mortar. The low SiO 2 /Na 2 O indicated the beneficial presence of less-polymerized …
1- The Composition of the Sodium silicate solution is Na2O: 10%, SiO2: 27%, H2O: 63% and the Density 1.39 g/ml. the Composition of the Sodium hydroxide is NaOH Solid and the density is 2.13 g/ml.
Synthesis and characterisation of sodium silicate from spent foundry sand: Effective route for waste utilisation | Semantic Scholar. DOI: 10.1016/j.jclepro.2020.121689. Corpus ID: …
Silica Sand or Ground Silica Page 2 of 9 Date of preparation/revision: May 4, 2015 3. COMPOSITION / INFORMATION ON INGREDIENTS Component CAS No. Percent Crystalline Silica (quartz) 1 95-99.9 4. FIRST-AID MEASURES Inhalation: First aid is not generally required. If irritation develops from breathing dust, move the person …
designs of experiments to establish input-output relat ionships for sodium silicate-bonded, CO. gas hardened moulding sand system. …
The sodium-silicate-bonded sand was heated for 40 s at 175 °C, and the addition content of sodium silicate was 2.0% for raw silica sand. Sodium-silicate-bonded sand was stored in a humidistat (temperature of 25 °C and humidity of 70%). ... Silica fume additive (as a percentage of the amount of binder) Instant tensile strength The tensile ...
Another way to make sodium silicate liquid is to put silica sand straight into a hot solution of caustic soda and water while the mixture is under pressure. 2 N a O H + S i O 2-> N a O 2. S i O 2 + H 2 O. Solid or liquid (Hydrated nanosodium silicate is available as a hydrous/anhydrous powder, lump, or packed bead) commercial Nanosodium ...
Materials were consolidated by an acidified sodium silicate solution with silicon concentration equal to 2.26 mol/l and pH value equal to 10.86 leading generally to irreversible gel formation [16].The mixture of acidified solution and silica is first realized and then sand was added according to the desired composition before gelation (Fig. 1). ...
Sodium silicate, represented by the molecular formula Na 2 SiO 3, is an ionic compound and has a range of physical forms. It can be produced in a solid state or in a liquid solution. The different physical states depend on the ratios of silica and sodium oxide and on the water content. When in a solid state, sodium silicate appears as white ...
2. Materials and Methods. The silica nanoparticles with different sizes were prepared by varying the concentrations sodium metasilicate (Na 2 SiO 3, Thermo Fisher Scientific, Pittsburgh, PA, USA).From an initial 0.10 M Na 2 SiO 3, four solutions with different concentrations were prepared in a logarithmic relationship.The final …
The conversion of sand to sodium silicate is also dependent on reaction time. At 60 minutes, the reaction was found to be almost complete. The precipitation of silica depends on factors such as duration of precipitation, the addition rate of acid, the temperature of precipitation, concentration and pH [11]. The reaction of sand with sodium ...
The addition of silica sand has been reported to produce a similar effect for the basal spacing of montmorillonite as determined by the X-ray diffraction method (Liu et al., 2003).A basal spacing of 1.88 nm, corresponding to the three-water-layer hydrate state of montmorillonite, was found in the mixture sample having a partial dry density of 1.6 …
When a sodium silicate solution is mixed on sand and then cured with CO2, complex chemical and physical changes occur that contribute to the hardening of the core or mold.The bonding phase that holds the sand together consists of (1) precipitated silica gel formed as a result of the reaction between CO2 and sodium hydroxide and the …
(5) can be rewritten in the important form shown below: Na20.2SiO2-xH20 + CO2 + Na2CO3 + Si02.YH20 (9) sodium carbon sodium hydrated silicate + dioxide ~ carbonate + silica solition gas solid gel where x and y are the number of moles of water either in sodium silicate solu- 79 tion or in the hydrated gel, which at present has no …
O (<2%) in silica sand, with percentage below the minimum threshold, and obtained silica sand with SiO 2 percentage was 98.38%.This percentage exceeded the minimum …
19 Citations. Explore all metrics. Abstract. This paper investigates the microsilica addition value in the improvement of the sand molds and cores properties …
The transformations of different sand samples, viz. fresh sand, SWFS, fresh sand calcined, fresh sand with sodium silicate as binder calcined (FSSC), and only sodium silicate (SS), calcined at ...
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