Glass foams are modern developed building materials which are now favorably competing with conventional materials for applications in thermal insulation. In this study, glass foams are synthesized ...solely from waste container glasses of mixed colors using sodium silicate (water glass) as foaming agent. Several glass foams of 150 × 150 × 30 mm were prepared from waste glasses of 75 μm, 150 μm and 250 μm size with addition of 15 wt % sodium silicate respectively and pressed uniaxially under a pressure of 10 MPa. The prepared glass foams were then sintered at temperatures of 800 °C and 850 °C respectively. Tests such as bulk density, estimated porosity, flexural strength, compressive strength and microstructure evaluation were used to assess the performance of the developed glass foams. The results showed that with increasing temperature and grain sizes, the percent porosity of the developed foams increased while the bulk density decreased. The microstructure evaluation showed that the finer the grain sizes used, the more homogenized are the pores formed and the higher the temperature, the larger the pores but are mostly closed. Both compressive and flexural strength were found to decrease with grain sizes and higher temperatures. The thermal conductivities of all the developed foam glasses satisfy the standard requirement to be used as an insulating material as their thermal conductivities did not exceed 0.25 W/m.K.
Fluorite is easily affected by the slime coating of fine barite during the froth flotation separation. In this work, the water glass (WG) was utilized as a dispersant to improve the flotation ...separation performance between fluorite and barite slimes. The single minerals flotation results revealed that barite slimes could be selectively depressed by gelatinized starch (GS), while WG had little effect on the floatability of barite and fluorite using sodium oleate (NaOl) as a collector. The flotation results of artificially mixed minerals showed that the separation efficiency of fluorite from barite was significantly reduced when barite existed as slimes. However, the presence of WG could eliminate the negative effect of barite slimes on the flotation fluorite by using the reagents scheme of GS/NaOl. Zeta potential results indicated that the fluorite surface charge turned from positive to negative with the addition of WG, then the barite slimes coating was detached from the fluorite surface because of the electrostatic repulsion, allowing the cleaning fluorite surface to once again interact with NaOl. The DLVO calculation was also conducted to reveal the agglomerate and disperse of different particles in the flotation system of fluorite-barite slimes.
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•Fluorite flotation is easily affected by the barite slimes because of the hetero-coagulation.•WG makes the interaction between fluorite and barite slimes turn to electrostatic repulsion.•WG can act as a dispersant to strip barite slimes from fluorite surfaces.•WG can improve the flotation separation of fluorite from barite slimes.
The similar flotability of scheelite, fluorite, and calcite resulted in the difficult separation by flotation. This work revealed the effect of water glass on the flotation of scheelite by FTIR and ...the wettability change of the usual cleavage plane, and proved that water glass inevitably influenced the flotation of tungsten minerals to a large extent in traditional fatty acid flotation process. A new collector, lead complexes of benzohydroxamic acid, was found to be selective for the separation of scheelite and calcium minerals with little water glass. Hence a novel flotation process was developed for the recovery of tungsten minerals in Shizhuyuan Mine in China. Normal temperature flotation of tungsten minerals was developed to instead of the classical “Petrov's process” for scheelite-calcite-fluorite type ores. Compared with the traditional process, the recovery was improved by almost 10% and the grade of scheelite concentrate was above 55%. The disappearance or decreasing of water glass contributed to improving the recovery of tungsten and the circulation of water and reagents.
•Water glass adversely influenced the recovery of tungsten minerals.•Pb-BHA complexes were selective for separation of calcium minerals.•Trace of water glass was added and recovery was improved by almost 10%.•“Petrov's process” was replaced.•Circulation of water was beneficial for the environment.
When AWG was added to the scheelite and calcite slurry, AWG is chemically adsorbed on the mineral surface and generate new species, and AWG is more adsorbed on the calcite surface than scheelite. In ...the presence of AWG, DDA is selectively adsorbed on scheelite surface.
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•AWG has depressant effect on flotation of calcite.•AWG can selectively chemically absorb on calcite surface in the form of H2SiO42− and H3SiO4−.•AWG affects the adsorption of DDA from mixed collectors on scheelite surface.•A possible adsorption mechanism and adsorption mode is proposed.
In this paper, the effect of acidified water glass (AWG) on the flotation separation of scheelite from calcite using mixed collector of dodecylamine (DDA) and sodium oleate (NaOL) was investigated. The flotation results show that AWG could selectively depress the flotation of calcite at pH 7. A series of mechanism experiments confirm that the chemisorption of AWG on calcite surface is more intense than scheelite. Although the chemisorption of NaOL on calcite surface is almost unaffected by the presence of AWG, the chemisorption of AWG hinders the adsorption of DDA on calcite surface.
Acidified water glass shows selective depression for calcite, which allowing preferential flotation separation of barite from calcite when using sodium oleate (NaOl) as collector.
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...Flotation separation of the barite from calcite by adding depressant acidified water glass (AWG) and collector sodium oleate (NaOl) was investigated in this study. The micro-flotation results presented that NaOl has a good collecting ability for both barite and calcite while AWG has the selective depressing ability of calcite. The flotation of artificial mixed minerals confirmed that the separation of barite from calcite could be achieved by using AWG as depressant. Zeta potential revealed that the addition of AWG prior to NaOl prevented the adsorption of NaOl on the surface of calcite while it did not hinder NaOl absorbed on the surface of barite, then causing the different floatability of minerals.
•Mixture of glass powder and water glass is atmosphere sensitive.•Reaction with CO2 results in the formation of carbonates.•Newly formed carbonates are the main source of expansion gas (CO2).•New ...mechanism of foaming with water glass proposed.
Water glass is a common additive in the process of direct foaming of glass, however, the currently accepted foaming mechanism lacks experimental validation. A foaming mixture of waste cathode ray tube panel glass and water glass was investigated for its expansion and gas evolution behavior via hot stage microscopy and thermogravimetry coupled with mass spectroscopy, respectively. The evolution of a significant amount of CO2 during the heating of the foaming mixture was detected and an overwhelming presence of CO2 within the pores of the foamed glass was confirmed with gas chromatography. With this investigation, we reveal an underlying foaming mechanism, where a carbonate phase forms after mixing water glass with the glass powder and later acts as the foaming agent. The unveiled mechanism could help further research in the field of foamed glass, with the potential to produce more sustainable materials with better performance via less energy-demanding processes.
•Both the liquid and solid phase existed in the Pb-water glass.•The solid phase has inconspicuous effect on both scheelite and calcite flotation.•The liquid phase has a strong depression effect on ...calcite, but not on scheelite.•The Pb-silicate species in the liquid phase result in the selective flotation.
In this study, lead ion was combined with water glass to separate scheelite from calcite using flotation. The effects and underlying mechanisms of the liquid and solid phases generated in this combined depressant (Pb-water glass, a mixture of lead ion and water glass) on the flotation performance of scheelite and calcite were investigated through micro-flotation experiments, X-ray diffraction (XRD) measurements, ultraviolet–visible (UV–Vis) spectrophotometer measurements, fourier transform infrared spectrometer (FTIR) analysis, zeta potential measurements, and X-ray photoelectron spectroscopy (XPS) tests. The flotation results indicate that the selective flotation separation of scheelite from calcite results from the liquid phase, not the solid phase. The XRD and FTIR results indicate that under different mass ratios of lead ion to water glass, the solid phases are the lead-silicate with amorphous structures, while the UV–Vis results reveal significant absorption differences in the liquid phases under different mass ratios of lead ion to water glass. The zeta potential and XPS results indicate that less metal silicate polymers are adsorbed on the scheelite surface than on the calcite surface, allowing NaOL to be adsorbed on the scheelite surface, but not on the calcite surface, and selective flotation separation of scheelite from calcite is therefore achieved. XPS results further reveal that the metal silicate polymers in the liquid phase are adsorbed on both mineral surfaces by firstly breaking the Ca-O group and then reacting with the Ca active sites.
•Low-burned magnesium oxide is the auxiliary material of MPC, and the water-binder ratio is 1.•Fresh-state properties of grouts with MPC, fly ash, bentonite and waterglass are studied.•Mechanical ...properties and of grouts with MPC, FA, B and water class are studied.•Combined effects of fly ash, bentonite and water glass are studied.•Microstructure characteristics of MPC based grouts with FA and waterglass are presented.
Water inflow in a karst area has the characteristics of a large water volume and a fast flow rate, which makes the water inrush of a karst conduit flow extremely difficult to treat. Ordinary inorganic grouting materials have weak bonding with the interface, long initial and final setting time intervals and high loss rates of dynamic water filling. Phosphate cement has good interfacial bonding and instantaneous final setting after the initial setting, which is suitable for dynamic water conduit plugging. In this work, we developed anti-scouring grouts based on light-burned magnesia, potassium dihydrogen phosphate, Class F fly ash, water glass, and bentonite. A condensate based on potassium magnesium phosphate cement (MKPC) is formed using Class F fly ash (0–30%) to replace some of the MgO and KH2PO4. Then, the three materials form a cementitious material system. The water-cement ratio is 1:1 and is then modified with bentonite (5%) and water glass (0–6%). The basic properties of the grouts were studied by measuring the setting time, viscosity, compressive strength (after 3 d, 7 d, and 28 d), and flow distance. The microscopic properties of the hardened stone were studied by using both X-ray diffraction (XRD) and scanning electron microscope (SEM). The experiments show that the molar ratio of MgO to KH2PO4 (M/P) along with the water glass and fly ash contents play a significant role in the setting time, compressive strength, and viscosity of the grouts. The addition of fly ash can reduce the fluidity of the grouts and the early strength; however, the 28-day compressive strength of the grouting material mixed with 30% class F fly ash is higher than that of the grouting material mixed with 10% and 20% Class F fly ash. Water glass can reduce the setting time and fluidity of the grouts and can increase the strength of the grouts.
As one of the novel green foundry binders, the bonding strength of two-component inorganic binder system (water glass-microsilica) under wet conditions needs to be further improved. In this work, ...γ-(methacryloxypropyl) trimethoxy silane (MPS) was added to water glass. The effect of MPS on the storage stability of sand core was studied, based on which the mechanisms of condensation and hydrophobicity of water glass-microsilica were discussed. The results showed that the maximum bonding strength of 1.0 wt% MPS modified sand core was increased by 15.5% at 80–85% RH. MPS promoted the dehydration condensation between water glass and microsilica, which will make its three-dimensional network more complex. Moreover, it formed a hydrophobic organosilane layer on the surface of the bonding bridge, which can play a role in shielding hydrophilic Na+ and prevent the destruction of bonding film by forming Si–O–R bonds, preventing the external water from damaging.
