Silica Slag Research Articles

Study on the Mechanical Properties and Microstructure of Soil Stabilized with Alkali-Activated Slag–Steel Slag–Silica Fume

Abstract In order to solve the problem of low comprehensive utilization rate of industrial solid waste, this article focuses on the three problems of slag, which are steel slag, reuse of silica fume, and the strength enhancement and microscopic mechanism of slag-steel slag-silica fume composite material; analyzes the macro strength of the mixture under different curing ages from the two indexes of unconfined compressive strength and splitting tensile strength; and conducts microscopic tests such as X-ray diffraction, scanning electron microscopy, and Fourier transform infrared. The internal mechanism of hydration product formation and strength change of slag and steel wollastonite cementitious material under the excitation of sodium hydroxide and sodium silicate mixed solution as alkali activator was discussed. The strength results show that when the optimum mixture ratio of slag: steel slag: silica fume is 6:3:1, the modulus of lye is 1.2, the content of lye is 6 %, and the compressive strength of slag-steel slag-silica fume base polymer reaches 2.44 MPa under the standard curing condition of 28 day. The results show that the hydration products of geopolymer mainly consist of calcium-silicate-hydrate (C-S-H) gel and a small amount of ettringite (AFt) crystal. The addition of slag reduces the calcium/silicon ratio and increases the aluminum/silicon ratio, which makes the gel polymerization degree increase. C-S-H gel can be formed by the reaction of calcium hydroxide and silicon dioxide produced by steel slag hydration. Silica fume can provide highly reactive silicon for the system, and its seed effect and pozzolanic effect can accelerate the hydration process of the system.

EXPERIMENTAL STUDY OF CONCRETE AS PARTIAL REPLACEMENT OF COARSE AGGREGATE BY SILICA SLAG

Aggregate is a key component of concrete, greatly impacting its volume and influencing its mechanical strength, durability, and serviceability. This study examines using silica slag, an industrial by-product waste, as a partial replacement for coarse aggregate (Recycled Brick Chips) in concrete. It assesses concrete properties with silica slag replacing recycled brick chips at 0%, 20%, 40%, and 60%. The findings show that adding silica slag with recycled brick chips enhances both compressive and tensile strengths. Concrete mixes, prepared with superplasticizer (ASTM C-494: Type A & F), achieved improved workability while maintaining the required water-cement ratio. Various mechanical properties of silica slag, such as impact resistance, specific gravity, unit weight, void ratio, and water absorption, were thoroughly tested. The study reveals that a 40% replacement of coarse aggregate with silica slag results in optimal compressive strength, around 18 MPa. This indicates that concrete incorporating recycled brick chips and silica slag can achieve moderate compressive strength and meet structural requirements effectively to achieve sustainable development.

Modified H‐BEA Zeolites from Fluorinated Silica Slag Waste by Dry Gel Conversion Method for Shape‐Selective Acylation of 2‐Methoxynaphthalene

AbstractThe high value‐added utilization of the fluorinated silica slag (FSS) waste, an associated by‐product of the anhydrous HF production from the accompanying fluorine resources in phosphate ore, is of great importance, but it remains a challenge. In this work, the Mg modified and unmodified Hβ zeolites from FSS waste were successfully prepared by a green dry gel conversion crystallization method with tetraethylammonium hydroxide (TEAOH) as a structure‐directing agent (SDA). The in situ Mg modified Hβ zeolite (Mg−Hβ) shows much superior catalytic performance to unmodified (Hβ) and post Mg‐modified Hβ (Mg/Hβ) zeolites for acetylation of 2‐methoxynaphthalene (2‐MN) to 6‐acetyl‐2‐methoxynaphthalene (2,6‐AcMN), and the 40.2 % of conversion for 2‐MN with 66.3 % of selectivity for 2,6‐AcMN were achieved, ascribed to the high amount of B acidic sites and the promoted shape‐selective catalysis effect by higher surface area and volume of micropores. This work not only opens a new avenue for the high value‐added utilization of fluorinated silica slag waste, but also generates an efficient solid acid catalyst for the clean production of 2,6‐AcMN through the acetylation of 2‐MN with acetic anhydride.

磷矿硅渣合成NaA型分子筛及应用于湿法磷酸脱氟的研究

磷矿硅渣合成NaA型分子筛及应用于湿法磷酸脱氟的研究

Features and Restrictions of Electroslag Remelting with Silica‐Bearing Slags for Lightweight High Manganese Steel

Experiments are conducted to investigate the electroslag remelting process of Fe‐(20‐30)Mn‐(10‐12.0)Al‐(1‐2)C (wt%) steel in a short collar mold using a characteristic silica‐bearing slag to improve nonmetallic inclusion morphology. The effect of the “one‐slag melt” with silica on the changes in the chemical composition of the ESR ingot along its height is studied. The observed silicon pick‐up in metal at ESR is caused by the interaction of silica‐bearing slag with aluminum from metal composition (10%), stipulated by the ESR process nature and cannot be avoided. CALPHAD prediction of phase formation at observed changes of metal chemistry is proved by microstructure and EDS investigations of as‐cast metal of remelted ingot. Silicon pick‐up in obtained limits does not change the morphology of the main phases in the remelted Fe–Mn–Al–Cr‐C‐(Si) steel, but the microhardness of the phases becomes higher. Due to the low speed of remelting provided by ESR TC, the as‐cast metal structure and nonmetallic inclusions are refined. Experiments show that high silica‐bearing slag is not convenient for remelting high aluminum steels because of silicon transfer into ESR ingot at slag's silica reduction by aluminum.

Molten salt synthesis of mullite whiskers entirely derived from fly ash for electronic packaging toughening ceramic applications

Preparation of mullite from high-alumina coal fly ash (CFA) has become one of the most important ways for high-value utilization. However, low Al2O3/SiO2 ratio, poor reaction activity and various impurities in fly ash led to poor quality of mullite products. Conventional sintering method requires addition of aluminum sources and sintering additives, and high synthesis temperature. This paper proposes a new technical route for preparation of mullite whiskers entirely from fly ash by molten salt method based on additive activation-acid leaching process. The growth process and synthesis mechanism of mullite whiskers in Na2SO4 molten salt from fly ash were systematically investigated, and the application of fly ash-derived mullite whiskers in electronic packaging toughening ceramic was also explored. The results show that leaching liquor containing Al3+, Na+, and SO42−, and amorphous silica slag can be separated and obtained after acid leaching of activated fly ash at 80 °C, and the fly ash-derived mullite whiskers with a length of about 1 μm can be synthesized from the mixture of crystalline products and silica slag by the proposed method under the optimal synthesis conditions. Using amorphous silica slag with higher dissolution activity as the silicon source, the nucleation of mullite whiskers with homogeneous nucleation process is promoted and highly monodispersed mullite whiskers derived from fly ash form. The fly ash-derived mullite whiskers can improve the mechanical strength, reduce the dielectric constant and dielectric loss of the composite ceramic substrates, and the dielectric constant and dielectric loss of the composite ceramic are the lowest 5.16 and 0.006, respectively, when the mullite addition content is 20 wt.%, indicating that they could be used as electronic packaging materials. This paper provides a novel pathway for synthesis of mullite whiskers and high-value utilization of fly ash.

An experimental study on mechanical and durable properties of self-curing concrete by using Ferro silica slag aggregate

Construction industry concrete used heavily. The building industry relies heavily on coarse aggregate (C.A.). Due to the lack of C.A., artificial aggregate known as Ferro silica slag (F.S.S.) is the predominant alternative material. The Use of F.S.S. increases concrete strength and lowers construction costs. The strength of concrete is determined by how long it is allowed to cure. Because of improper curing, the hydration of cement problem can be solved by employing a self-curing mechanism. It’s possible to use paraffin wax Light and Heavy in Concrete have a variety of beneficial effects on S.C.C.’s fresh and hardened concrete qualities. The immersing curing agent is a material that retains Water and reduces evaporation; the self-curing admixture incorporates concrete after the standard setting of concrete on account of increased water retention capacity and compares to internally cured concrete. It gives inside assuaging, known explicitly as “self-curing concrete,” in short, less or no external curing is required in another way if outside mitigating may cause better warmth of hydration. Light molecular weight and high molecular weight are two examples of self-curing liquids that can boost the strength and serviceability of concrete. In this investigation, the percentage of paraffin wax in M25 grade concrete was altered from 0%, 0.1%, 0.5%, and 1.0% and compared to internally cured concrete(I). The replacement of coarse aggregate with the optimum amount of F.S.S. Paraffin is then added to concrete in a liquid form, resulting in varied dosages. Based on the literature, the optimum percentage of F.S.S. 40% with paraffin wax light and heavy 1.0% improvement of compression and flexure strength of concrete. Ultrasonic pulse velocity (U.P.V.) and Rapid chloride penetration tests (RCPT) were used to determine dense microstructure and enhanced durability of concrete.

Selective controlled precipitation mechanism of canasite and xonotlite in glass-ceramics from silica slag

In this paper, Na2OCaO-SiO2-X(NCSX) glass-ceramics was prepared to use industrial silicon slag as the main raw material. We employed XRD, FTIR and NMR to analyze the influence of Na2O/SiO2 on the composition of microstructure units Qn in the glass-ceramics. It revealed the precipitation mechanism of xonotlite and canasite. Spectroscopy study indicated that sodium atoms could selectively destroy the glass network to form Q3 units while silicon atoms could rebuild the network to form Q4 units. Q3 units can combine with calcium atoms to form Si-O-Ca bonds that generated the precipitation of xonotlite phase. However, Si-O-Si bond wrapped the Si-O-Ca bond to form an interlayer structure in canasite crystal. And the effective method for controlling the formation of canasite crystal was adopted cautiously. That is, synergistic regulation of Na2O/SiO2 and heat treatment to precipitate the canasite phase exclusively.

硅渣土壤调理剂施用对设施土壤物理性状影响研究

硅渣土壤调理剂施用对设施土壤物理性状影响研究

硅渣土壤调理剂施用对设施番茄产量和土壤磷素吸收影响研究

硅渣土壤调理剂施用对设施番茄产量和土壤磷素吸收影响研究

Determination of Critical Soil Silicon Levels for Rice Production in Louisiana Using Different Extraction Procedures

ABSTRACTWhile silicon (Si) fertilization is widely practiced in rice production, establishing critical soil Si levels has remained understudied. Field trials were established at 12 sites across Louisiana from 2013 to 2015 to determine critical soil Si for rice cultivation. Five silica slag (14% Si) rates at 0, 1, 2, 4, 6, and 8 Mg ha−1 and two lime rates (2 and 4 Mg ha−1) were arranged in randomized complete block design with four replications. Post harvest soil samples were analyzed for Si using seven extraction procedures. The critical soil Si levels established by the linear plateau model using 0.5 M acetic acid-1 hr (OAc-1) extraction procedure were 36, 41 and 50 mg kg−1 for plant Si uptake, grain yield, and relative yield as response variables, respectively. Generally, soils having high initial Si and pH had minimal responses to Si fertilization, whereas Si content of soils with low initial Si was significantly increased.

THERMODINAMIC ASPECTS OF HYDROGEN REMOVAL DURING WELDING UNDER FLUORINE-CONTAINING FLUXES

The article gives the thermodynamic assessment of the probability of hydrogen removal processes from the welded metal during welding under fl uoride fl ux in standard states at the temperature range 1700 – 2200 K. Na3AlF6 ж , ЅіО2 ж , SiF4 г , NaAlO2 тв , Na2SiO3 ж , CaF2 ж , CaSiO3 тв , Н2 г , SiF2 г , HFг , О2 г , SiFг , Ng have been selected as the standard states for substances reagents. As the result of calculation of standard Gibbs energy and the equilibrium constants of the reactions, it has been determined that the reactions of direct interaction between fl uorine agents of slag with hydrogen and oxygen in metal are the most probable reactions of the interaction with cryolite. In more complex mechanism of interaction involving in the reactions, except fl oriental, silica slag and the possible formation of an intermediate product SiF4 г , process of interaction with the fl uorite is more probable. The calculations have shown the feasibility of using Na3AlF6 compounds with fl uorite for hydrogen removal in submerged-arc welding. The calculations have formed the basis for the development of new compositions of fl ux-additives, protected by patents of the Russian Federation.

Evaluation of the protective C2S layer in the corrosion process of doloma-C refractories

The performance of doloma-C refractory bricks during the steel refining step is essential for a cost effective production of steel and should be well understood. Occasionally, in special runs, the industrial practice requires a fast adjust of slag composition to fulfill the metallurgical requirements. This procedure can lead to active corrosion of the refractories, which decrease dramatically their overall life. This work aims to investigate the phenomena involving the protective layer of dicalcium silicate (C2S), which is formed through the reaction between silica slag and dolomitic refractories. C2S layer samples were characterized by analyzing their chemical composition, phase formation and microstructure. C2S was observed as the main phase, but the presence of cuspidine, a silicate-based phase with low melting point, promoted the mechanism of C2S layer dissolution by a slag with a high content of fluorspar. This work was completed with a case study in which C2S/slag samples were taken from different points of the ladle in order to evaluate the effect of fluorspar on C2S layer dissolution. Post mortem doloma-C refractory brick samples were also analyzed to verify the influence of fluorspar on the corrosion process.

Effect of B2O3 addition on viscosity of mould slag containing low silica content

The viscosity of SiO2–30Al2O3–B2O3–12Na2O–CaO slag system (CaO/SiO2 = 2·68–7·35, B2O3 = 0–9 wt-%) was investigated in the present study. The objective is to study the influence of B2O3 on the viscosity and structure of mould slags containing low silica content. The research of the low silica slag system is meaningful because of it is less reactive with Al during continuous casting of steels containing high amounts of dissolved aluminium, such as transformation induced plasticity assisted steels. The viscosities of these quinternary slags decreased slightly with an increase in the content of additive B2O3 above the break temperature. The apparent activation energy of viscous flow was found to decrease with increasing B2O3 content. The break temperature also decreased with increasing B2O3 content. Based on the experimental data, the decrease in break temperature per mol.-% B2O3 ΔTbr is 15·23 K. An empirical model was then established to predict the break temperature of mould slags containing B2O3, and the deviation is between −25 and +25 K. Based on the viscosity and Fourier transform infrared analysis, it is proposed that the three-coordinated boron is dominated in these slags over the entire compositional range, and the borosilicate networks are loosened with increasing B2O3 content in the present study. The Riboud model was modified empirically based on the present experimental data, and the mean deviation is ∼13%.

Mineralogical overview of the behavior of gold in conventional copper electrorefinery anode slimes processing circuits

The behavior of gold in a conventional copper electrorefinery anode slimes treatment process is expounded on in this study. In the raw anode slimes generated in a copper electrorefinery, gold occurs mainly as tiny particles of metallic gold, which are commonly attached to selenide particles. Some gold is also present in selenide form. Decopperizing the anode slimes retains much of the metallic gold, but also promotes the incorporation of gold in the structure of silver-rich selenide species. A greater fraction of the gold is converted to (Ag,Au)2Se or Ag3AuSe2 when high-Se and high-Ag anode slimes are decopperized at elevated temperatures and pressures. After pelletization and roasting of the slimes, the gold is converted to a (Ag,Au)-alloy and Ag3AuSe2. Smelting of the roaster products eliminates the selenium and converts the gold to a silver-rich (Ag,Au,Pd)-alloy in the dore metal. In the subsequent silver electrorefining process, gold collects as a gold-rich (Au,Ag,Pd)-alloy in the gold mud. Dore smelting rejects many impurities as a silica slag; minor amounts of gold are present as a (Ag,Au,Pd)-alloy in the silica slag. This gold is recovered by flotation and is recycled to the dore furnace. Gold is identified in both the tellurium caustic leach residue and the parting plant wash water mud as tiny particles of metallic gold. These products are also recycled to the dore furnace to recover their gold values.

Dissolution of alumina particles in CaO-Al2O3-SiO2-MgO slags

The dissolution behaviour of alumina particles in CaO-Al2O3-SiO2-MgO slags was studied by confocal scanning laser microscopy. Three different slag systems were investigated to evaluate the effect of changing the MgO content in a high silica tundish slag, and the effect of decreasing the silica content when dissolving the particles in a ladle slag. A particle of 80 mum diameter dissolved in 50 s in a simulated ladle slag but needed 100 s to dissolve in a high silica slag at the same temperature. When the silica content was decreased, a decrease in the alumina particle dissolution time was noted. During dissolution of alumina particles in a slag containing MgO, the alumina particle reacts with the slag to form an MgAlO4 layer. No reaction layer was observed during the dissolution of alumina particles in slags that did not contain MgO. This work suggests that the dissolution time of large alumina particles is significant, increasing with particle size and with decreased temperature.

SILICA SLAG AND BARK SLAG INFLUENCE INFECTION OF PLASMODIOPHORA BRASSICA INFECTIONIN AN INTENSIVE CHINESE CABBAGE PRODUCTION SYSTEM.

Race 1 of Plasmodiophora brassica isolated from high altitude of vegetable production district induced clubroot on cabbage, and Chinese cabbage. Inoculation of race from northwestern coast of Taiwan resulted clubroot of Chinese cabbage neither in cabbage. The addition of bark slag or silica slag significantly decreased clubroot infection and increased the weight of Chinese cabbage in the infected field. The addition of 3 gram slaked lime +1 gram KC1 +1.78 gram ammonium sulfate + 1 gram calcium superphosphate at 500 gram soil 2 month after transplanting increased dry wight of cabbage and decreased infection root hair followed by inoculation of race 1.