Effect of inorganic salt impurities on seeded precipitation of silica hydrate from sodium silicate solution

To clarify the precipitation of silica hydrate from the real desilication solutions of aluminosilicate solid wastes by adding seeds and improve integrated waste utilization,the seeded precipitation was studied using synthesized sodium silicate solution containing different inorganic salt impurities.The results show that sodium chloride,sodium sulfate,sodium carbonate,or calcium chloride can change the siloxy group structure.The number of high-polymeric siloxy groups decreases with increasing sodium chloride or sodium sulfate concentration,which is detrimental to seeded precipitation.Calcium chloride favors the polymerization of silicate ions,and even the chain groups precipitate with the precipitation of high-polymeric sheet and cage-like siloxy groups.The introduced sodium cations in sodium carbonate render a more open network structure of high-polymeric siloxy groups,although the carbonate ions favor the polymerization of siloxy groups.No matter how the four impurities affect the siloxy group structure,the precipitates are always amorphous opal-A silica hydrate.

Synergistic strengthening mechanism of Ca^(2+)-sodium silicate to selective separation of feldspar and quartz

Inhibitors are important for flotation separation of quartz and feldspar.In this study,a novel combined inhibitor was used to separate quartz and feldspar in near-neutral pulp.Selective inhibition of the combined inhibitor was assessed by micro-flotation experiments.And a series of detection methods were used to detect differences in the surface properties of feldspars and quartz after flotation reagents and put forward the synergistic strengthening mechanism.The outcomes were pointed out that pre-mixing combined inhibitors were more effective than the addition of Ca^(2+)and SS in sequence under the optimal proportion of 1:5.A concentrate from artificial mixed minerals that was characterized by a high quartz grade and a high recovery was acquired,and was found to be 90.70wt% and 83.70%,respectively.It was demonstrated that the combined inhibitor selectively prevented the action of the collector and feldspar from Fourier-transform infrared(FT-IR)and adsorption capacity tests.The results of X-ray photoelectron spectroscopy(XPS)indicated that Ca^(2+)directly interacts with the surface of quartz to increase the adsorption of collectors.In contrast,the chemistry property of Al on the feldspar surface was altered by combined inhibitor due to Na^(+)and Ca^(2+)taking the place of K^(+),resulting in the composite inhibitor forms a hydrophilic structure,which prevents the adsorption of the collector on the surface of feldspar by interacting with the Al active site.The combination of Ca^(2+)and SS synergically strengthens the difference of collecting property between quartz and feldspar by collector,thus achieving the effect of efficient separation.A new strategy for flotation to separate quartz from feldspar in near-neutral pulp was provided.

Carbonation of Dicalcium Silicate Enhanced by Ammonia Bicarbonate and Its Mechanism

The strength development law of γ-type dicalcium silicate (γ-C_(2)S) under different carbonation processes was investigated,and the carbonation mechanism of γ-C_(2)S under the action of NH_(4)HCO_(3) was clarified by using a wide range of test methods,including XRD and SEM.A method of saturated NH_(4)HCO_(3) solution as a curing agent was identified to improve the carbonation efficiency and enhance the carbonation degree of γ-C_(2)S,and then a high-strength carbonated specimen was obtained.Microhardness analysis and SEM morphology analysis were conducted on the carbonised specimens obtained under atmospheric pressure carbonisation conditions using the curing agent.It was found that γ-C_(2)S could perform carbonisation well under atmospheric pressure,which promoted the carbonisation efficiency and decreased the carbonisation cost simultaneously.Therefore,a new carbonisation process solution was proposed for the rapid carbonisation of γ-C_(2)S.

Natural Silicate as a Solid Support for the Calix[4]Thiophosphorus Derivative for Removal Mercury (II), as Picrate from Water

Currently a technique widely used for gold extraction is mercury by amalgamation technique, the tailing produced pollutes water of all kinds, so it is necessary to develop a form of selective mitigation, for which it is necessary to use complexing agents based on calixarene functionalized with mercury sequestering agents. These are immobilized by adding supports based on natural silica to form polymers and make them insoluble in all types of solvents, so that they can be used as an extractor and at the same time regenerate to their original properties for continuous reuse.

Effectiveness of Sodium Silicate on the Corrosion Protection of AA7075-T6 Aluminium Alloy in Sodium Chloride Solution

The influence of sodium silicate on the corrosion behaviour of aluminium alloy 7075-T6 in 0.1 M sodium chloride solution was studied by open circuit potential (OCP) and electrochemical impedance spectroscopy (EIS) techniques. Scanning electron microscopy (SEM) was used to characterize the AA7075-T6 surface. Silicate can significantly reduce corrosion deterioration and the inhibition efficiency increases with the concentration of Na2SiO3. The corrosion inhibition mechanism involves the formation of a protective film over the alloy surface by adsorption of aluminosilicate anions from solution, as has also been suggested by others in literature.

Research and Advances of Silicate Plugging Agent in the Oilfields

The paper overviews the research and application of silicate plugging agent, according to the different mechanisms and application forms, the plugging agent is divided into silicate gel, silicate precipitation, silicate/polymer, silicate/surfactant, silicate gel/foam and so on. This paper chiefly introduces the conception, mechanism and development tendency of the different systems mentioned above. The development tendency manifests as fully utilize personal properties and cooperate with other plugging agents or technologies, including the study of reaction mechanism, combination of plugging agent, grasping water flood timing, developing deep profile control and water shutoff technology, combining with other measures (chemicals huff and puff), in order to play the role of such blocking agents, further enhance oil recovery.

Adsorption of sodium polyacrylate at interface of dicalcium silicate-sodium aluminate solution

The adsorption isotherm of sodium polyacrylate on dicalcium silicate（2CaO-SiO2） in sodium aluminate solution at 80 ℃ was studied.The type of surface adsorption of sodium polyacrylate is saturated adsorption,and the adsorption behavior belongs to L-type,according with the monolayer adsorption model of Langmuir equation.The surface coverage of sodium polyacrylate is 1.06 mol/μm2.The relation curve between the surface pressure and the molecular area of adsorption film was obtained by Gibbs formula.The variation of interfacial energy caused by adsorption as well as the relationship between the relation curve and the type of adsorption was discussed.

Leaching kinetics of zinc silicate in ammonium chloride solution

The leaching kinetics of zinc silicate in ammonium chloride solution was investigated. The effects of stirring speed （150？400 r/min）, leaching temperature （95-108 ℃, particle size of zinc silicate （61-150 μm） and the concentration of ammonium chloride （3.5-5.5 mol/L） on leaching rate of zinc were studied. The results show that decreasing the particle size of zinc silicate and increasing the leaching temperature and concentration of ammonium chloride can obviously enhance the leaching rate of zinc. Among the kinetic models of the porous solids tested, the grain model with porous diffusion control can well describe the zinc leaching kinetics. The apparent activation energy of the leaching reaction is 161.26 kJ/mol and the reaction order with respect to ammonium chloride is 3.5.

Self-healing mechanism of composite coatings obtained by phosphating and silicate sol post-sealing

Silicate sol post-treatment was applied to form a complete composite coating on the phosphated zinc layer. The chemical compositions of the coatings were investigated using XPS. The coated samples were firstly scratched and then exposed to the neutral salt spray(NSS) chamber for different time. The microstructure and chemical compositions of the scratches were studied using SEM and EDS. And the non-scratched coated samples were compared. The self-healing mechanism of the composite coatings was discussed. The results show that during corrosion, the self-healing ions in composite coatings dissolve, diffuse and transfer to the scratches or the defects, and then recombine with Zn2+ to form insoluble compound, which deposits and covers the exposed zinc. The corrosion products on the scratches contain silicon, phosphorous, oxygen, chloride and zinc, and they are compact, fine, needle and flake, effectively inhibiting the corrosion formation and expansion of the exposed zinc layer. The composite coatings have good self-healing ability.

Influence of sodium silicate on manganese electrodeposition in sulfate solution

The influences of sodium silicate on manganese electrodeposition in sulfate solution were investigated. Manganese electrodeposition experiments indicate that a certain amount of sodium silicate can improve cathode current efficiency and initial pH 7.0?8.0 is the optimized pH for high cathode current efficiency. The analyses of scanning electron microscopy (SEM) and X-ray diffraction (XRD) indicate the compact morphology and nanocrystalline structure of electrodeposits. X-ray photoelectron spectrometry (XPS) analysis shows that the elements of Mn, Si and O exist in the deposit. The solution chemistry calculations of sulfate electrolyte and sodium silicate solution indicate that species of Mn2+, MnSO4, Mn(SO4)2?2 , Mn2+, MnSiO3, Mn(NH3)2+, SiO32?and HSiO3? are the main active species during the process of manganese electrodeposition. The reaction trend between Mn2+ and Si-containing ions is confirmed by the thermodynamic analysis. In addition, polarization curve tests confirm that sodium silicate can increase the overpotential of hydrogen evolution reaction, and then indirectly improve the cathode current efficiency.

Local structure of calcium silicate melts from classical molecular dynamics simulation and a newly constructed thermodynamic model

The distributions of local structural units of calcium silicate melts were quantified by means of classical molecular dynamics simulation and a newly constructed structural thermodynamic model. The distribution of five kinds of Si-O tetrahedra Qi from these two methods was compared with each other and also with the experimental Raman spectra, an excellent agreement was achieved. These not only displayed the panorama distribution of microstructural units in the whole composition range, but also proved that the thermodynamic model is suitable for the utilization as the subsequent application model of spectral experiments for the thermodynamic calculation. Meanwhile, the five refined regions mastered by different disproportionating reactions were obtained. Finally, the distributions of two kinds of connections between Qi were obtained, denoted as Qi-Ca-Qj and Qi-[Ob]-Qj, from the thermodynamic model, and a theoretical verification was given that the dominant connections for any composition are equivalent connections.

Occurrence mechanism of silicate and aluminosilicate minerals in Sarcheshmeh copper flotation concentrate

The Sarcheshmeh copper flotation circuit is producing 5× 10^4 t copper concentrate per month with an averaging grade of 28% Cu in rougher, cleaner and recleaner stages. In recent years, with the increase in the open pit depth, the content of aluminosilicate minerals increased in plant feed and subsequently in flotation concentrate. It can motivate some problems, such as unwanted consumption of reagents, decreasing of the copper concentrate grade, increasing of Al2O3 and SiO2 in the copper concentrate, and needing a higher temperature in the smelting process. The evaluation of the composite samples related to the most critical working period of the plant shows that quartz, illite, biotite, chlorite, orthoclase, albeit, muscovite, and kaolinite are the major Al2O3 and SiO2 beating minerals that accompany chalcopyrite, chalcocite, and covellite minerals in the plant feed. The severe alteration to clay minerals was a general rule in all thin sections that were prepared from the plant feed. Sieve analysis of the flotation concentrate shows that Al2O3 and SiO2 bearing minerals in the flotation concentrate can be decreased by promoting the size reduction from 53 to 38 μm. Interlocking of the Al2O3 and SiO2 bearing minerals with chalcopyrite and chalcocite is the occurrence mechanism of silicate and aluminosilicate minerals in the flotation concentrate. The dispersed form of interlocking is predominant.

Identification and Practical Application of Silicate-dissolving Bacteria

Slime-forming bacteria were isolated from soils, rock surface and earthworm intestine, and their effects on dissolving silicate minerals and tomato growth were examined. One of the bacteria, Bacillus mucilaginosus RGBc13, had particularly strong ability to form slime and dissolve silicates. RGBc13 could also colonize and develop in both non-rhizosphere and rhizosphere soil. Total number of slime-forming bacteria increased from 2.9 × 103 cfu·g-1and 8.4 × 103 cfu·g-1 to 9.6 × 106 cfu·g-1 and 6.0 × 107 cfu·g-1 in the non-rhizosphere and rhizosphere soils respectively. Potassium and phosphorus nutritional conditions in the rhizosphere were markedly improved through inoculation of this bacterium. Available K and P respectively increased from 25. 86 and 3. 63mg · kg-1 in the non-rhizosphere soil to 91. 23 and 5. 74mg · kg-1 in the rhizosphere soil. Tomato biomass increased by 125%, K and P uptakes were more than 150%, greater than the non-inoculation. Thus, there is a potential in applying RGBcl3 for improving plant K and P nutrition.

Determination of Iron in Layered Crystal Sodium Disilicate and Sodium Silicate by Flame Atomic Absorption Spectrometry with Boric Acid as a Matrix Modifier

The effects of matrix silicate and experimental conditions on the determination of iron in flame atomic absorption spectrometry （FAAS） were investigated. It was found that boric acid as a matrix modifier obviously eliminated silicate interference. Under the optimum operating conditions, the determination results of iron in layered crystal sodium disilicate and sodium silicate samples by FAAS were satisfactory. The linear range of calibration curve is 0-10.5 μg.mL^-1, the relative standard deviation of method is 1.2%-2.2%, the recovery of added iron is 96.0%- 101%, the sensitivity is 0.19 μg.mL^-l and the detection limit is 77 ng.mL^-1. The effect of the determination of iron of the standard curve method, standard addition calibration and colorimetry method was the same, but the first has the merits of rapid sample preparation, reduced contamination risks and fast analysis.

Influence of Na_(2)SiO_(3)/NaOH Ratio on Calcined Magnesium Silicate Based Geopolymer——Experimental and Predictive Study

This study aims to investigate the behavior of alkali activated mortar,which is made of naturally available magnesium silicate as source material.For magnesium silicate,ultrafine natural steatite powder(UFNSP)is used as the primary source of binder,and the activation is initiated through the alkali liquid which is proportioned in various combinations of silicate to hydroxide ratio(Na_(2)SiO_(3)/Na OH)ratio,and this ratio in this study varies from 1 to 3.The UFNSP is calcined at two difierent temperatures,700 and 1000℃.The mortar mix is proportioned as 1:3 between powder and the fine aggregate,and the mortar is prepared with hydroxide molarity(M)of 10 M.The mortar is cured for 48 hours at 60℃and the compressive strength was studied.All the mix were studied for its microstructural behavior along with compressive strength.The mix proportion of the mortar,and the results obtained through microstructural characterization were combinedly formed as input for artificial neural network(ANN)predictive modelling.The model is designed to predict the compressive strength,which is trained through Bayesian regularization algorithm with varying hidden neurons of 7 to 10.This experimental and predictive study shows that the strength is influenced by both Na_(2)SiO_(3)/Na OH ratio and calcination process.And the ANN is influenced by mainly calcination temperature and uncorrelation occurs in selected samples of 1000℃calcined UFNSP mix.

Effect of Minor Elements on Silicate Cement Clinker

The effect of rare-earth and HX addition agent on the burn-ability of silicate cement dinker was investigated by orthogonal experiment. The result shows, compared with blank sample, f CaO of the .samples added with rare-earth and HX agent drops by 84.95% , its 3 d and 28d compressive strength enhances by 24.40% and 16.90% , respectively. It was discovered by means of X-ray diffrnction and high temperature microscope analysis that sintering temperature of the sample added with rare-earth and HX addition agent is about 1320℃. At the same time, the tmrning temperature of triealeium silicate desends and its crystal growth forming- rate increases. Tricalcium silicate content in burning clinker is higher and its crystal is larger.

STUDY ON THE POLYMERIZATION DEGREE OF SILICATE ANIONS IN THE SILICATE GLASS BY TRIMETHYLSILYLATION METHOD

In the present paper,a mixed solvent method is applied to the trimethylsilylation of silicate glass,and the polymerization degree and its distribution of silicate anions in the silicate glass are measured by means of the analyses of gas chromatography-mass spectrography.

Examination of Silicate Limitation of Primary Production in Jiaozhou Bay,North ChinaⅢ.Judgment Method,Rules and Uniqueness of Nutrient Limitation Among N,P,and Si

Analysis and comparison of Jiaozhou Bay data collected from May 1991 to February 1994(12 seasonal investigations) provided by the Ecological Station of Jiaozhou Bay revealed the characteristic spatiotemporal variation of the ambient concentration Si:DIN and Si:16P ratios and the seasonal variation of Jiaozhou Bay Si:DIN and Si:16P ratios showing that the Si:DIN ratios were < 1 throughout the year in Jiaozhou Bay; and that the Si:16P ratios were < 1 throughout Jiaozhou Bay in spring, autumn and winter. The results proved that silicate limited phytoplankton growth in spring, autumn and winter in Jiaozhou Bay. Analysis of the Si:DIN and Si:P ratios showed that the nutrient Si has been limiting the growth of phytoplankton throughout the year in some Jiaozhou Bay waters; and that the silicate deficiency changed the phytoplankton assemblage structure. Analysis of discontinuous 1962 to 1998 nutrient data showed that there was no N or P limitation of phytoplankton growth in that period. The authors consider that the annual cyclic change of silicate limits phytoplankton growth in spring, autumn and winter every year in Jiaozhou Bay; and that in many Jiaozhou Bay waters where the phytoplankton as the predominant species need a great amount of silicate, analysis of the nutrients N or P limitation of phytoplankton growth relying only on the N and P nutrients and DIN:P ratio could yield inaccurate conclusions. The results obtained by applying the rules of absolute and relative limitation fully support this view. The authors consider that the main function of nutrient silicon is to regulate and control the mechanism of the phytoplankton growth process in the ecological system in estuaries, bays and the sea. The authors consider that according to the evolution theory of Darwin, continuous environmental pressure gradually changes the phytoplankton assemblage's structure and the physiology of diatoms. Diatoms requiring a great deal of silicon either constantly decrease or reduce their requirement for silicon. This will cause a series of huge changes in the ecosystem so that the whole ecosystem requires continuous renewal, change and balancing. Human beings have to reduce marine pollution and enhance the capacity of continental sources to transport silicon to sustain the continuity and stability in the marine ecosystem.nt

Adsorption of Methylene Blue on magnesium silicate: Kinetics, equilibria and comparison with other adsorbents

Batch adsorption from aqueous solutions in a slightly basic medium of Methylene Blue, up to 2500 mg/L, onto synthetic magnesium silicate （Florisil） of three particle size ranges （mean diameters of 112, 200 and 425 μm） was compared to the corresponding adsorption onto activated carbon and Amberlite XAD-2. The best fit of the kinetic results was achieved by a pseudo second-order equation. The equilibrium data were found to be well represented by the Langmuir isotherm equation. Amberlite XAD-2, an unspecific adsorbent capable of adsorbing exclusively through a surface effect, exhibited a poor dye uptake, confirming that the adsorption mechanism on Florisil was due to electrostatic attraction and ion exchange. Moreover, the comparison between Florisil and the other adsorbents was performed on the basis of the evaluation of the surface area and pore volume occupied by the adsorbed dye.

Electrochemical mechanism and flotation of chalcopyrite and galena in the presence of sodium silicate and sodium sulfite

The electrochemical mechanism involved in the selective separation of chalcopyrite from galena was investigated by flotation and electrochemical methods in the presence of sodium sulfite and sodium silicate,respectively,as a single depressant and their mixture as a combined depressant.Flotation tests revealed that the floatability of chalcopyrite was unaffected by depressants and its recovery remained constant(>80%)within the studied dosage range.Galena flotation was severely depressed with descending depressing order as follows:combined depressant﹥sodium silicate﹥sodium sulfite.Electrochemical analysis confirmed the high affinity of depressants on the galena surface,resulting in the formation of hydrophilic species,such as lead sulfite,lead sulfate,and lead orthosilicate.The oxidation of chalcopyrite surface and depressants did not exhibit any signals;conversely,the self-oxidation of chalcopyrite was depressed.The results of cyclic voltammograms well agreed with flotation results,demonstrating that chalcopyrite primarily reacted with the collector O-isopropyl-N-ethyl thionocarbamate and that galena mostly reacted with depressants.