Cathode Ray Tube Funnel Glass Research Articles

Effect of Partial Replacement of Fine Aggregate with Copper Slag and CRT With Addition of Aramid Kevlar Fiber

Abstract: Concrete is the most widely used construction material and the second most consumed substance in the world. Different Copper Slag and CRT concretes were created in this study by using Aramid Kevlar fiber in place of fine Aggregates. Every construction makes use of a significant amount of concrete because of its importance. Cathode-Ray Tube (CRT) technology has lagged behind as a result of the constant replacement of new technologies, such as LED Display Panel and Liquid Crystal Displays (LCD), which is leading to an increase in the number of discarded CRTs that need to be disposed of each year globally. The heavy waste material known as CRT funnel glass can increase the weight per unit of concrete. In terms of the components of products made during the copper production process, copper slag qualifies as an industrial product. It is a crystalline granular substance that can be utilized as a finer aggregate in concrete because of its high density and sand-like particle size. Aramid Kevlar fiber are completely synthetic organic polymers, aromatic polyamides are sometimes known as kevlar fiber.

Value-added recycling of cathode ray tube funnel glass into high-performance radiation shielding concrete

This study proposed a novel method for recycling cathode ray tube (CRT) glass as heavy aggregates to prepare radiation shielding concrete (RSC). Microstructure, physical properties, radiation shielding characteristics, as well as economic and environmental benefits of CRT glass-based RSC were evaluated. Compared to conventional RSC, the CRT glass-based RSC showed a 13.8 % higher gamma ray shielding capacity. Although the mechanical properties of CRT glass-based RSC slightly decreased by 25.7 % due to the weak interfacial transition zone, the 28-day compressive strength of CRT glass-based RSC still fulfilled the requirement of criteria (> 30 MPa). Based on the cost-benefit assessment, there was 166.7 $/m3 profit in CRT glass-based RSC. Furthermore, CRT glass-based RSC demonstrated 47.7 % and 37.0 % reduction in fossil fuel depletion and carbon emissions compared with barite-based RSC.

The lead removal evolution from hazardous waste cathode ray tube funnel glass under enhancement of red mud melting and synthesizing value-added glass-ceramics via reutilization of silicate resources

Waste CRT funnel glass (FG) is a typical hazardous waste produced by the electronics industry that contains toxic lead oxide, red mud (RM) is the first waste produced during alumina production. Both of these are extremely difficult to reuse. Here, we report a method to control FG waste, in which RM was used to enhance the removal of Pb from FG via a vacuum thermal process. The removed residual glass was utilized to create glass-ceramics. The results showed that RM can enhance the lead removal from waste CRT funnel glass by the vacuum thermal process. When 30% RM was added, the removal rate reached 98.54%. A significant mechanism of enhancing delead is investigated by a Fourier transform infrared (FTIR) spectrometer and X-ray photoelectron spectroscopy (XPS). The results showed that the -Pb-O-Si-O- network structure was broken by the free calcium ions of RM. Afterward, valuable glass-ceramics with tetragonal-KAlSi2O6 and triclinic-CaSiO3 crystals were synthesized using the residual glass. The Pb, Ba, Cr, and Cu leaching concentrations of the glass-ceramics were well below the regulatory limit (5 mg/L) of the CA-EPA, as measured by the toxicity characteristic leaching procedure (TCLP) test. Overall, the results indicated that RM enhanced the removal of lead during the vacuum thermal process. The synthesis of value-added glass-ceramics reutilized silicate resources from waste cathode ray tube (CRT) funnel glass and RM.

Recycle of large amount cathode ray tube funnel glass sand to mortar with supplementary cementitious materials

Utilizing acid treated CRT funnel (T-CRTF) glass sand in mortar is a feasible option to lower natural resource consumption and protect the environment. In this study, T-CRTF glass sand replaces river sand in mortar at four levels (0, 25 %, 50 %, 75 %). The inclusion of T-CRTF glass sand improves the fluidity properties of mortar. At the initial curing period (3 days), T-CRTF glass sand mortar exhibits the larger hardened density, mechanical strength than river sand-based mortar. After all mortars cured in water for 90 days, the hardened densities and the mechanical strength of mortars with 25 %, 50 % T-CRTF glass sand are the slightly higher than control mortar. The use of the excessive T-CRTF glass sand can no increase anyway the long-term hardened density and mechanical strength of mortars. The recycle of T-CRTF glass sand to mortars reduces the water absorption, the chloride ion penetration, enhances the drying shrinkage, the alkali-silica reaction (ASR) expansion and the lead leaching amount. FA, GGBS mortars with 75 % T-CRTF glass sand have the lowest water absorption, chloride ion penetration in all mortars. The introduction of large amount T-CRTF glass sand to FA, GGBS mortars is more easily to induce the drying shrinkage, the ASR expansion and the long-term lead leaching from mortar. Considerations from the long- term mechanical strength, durability behaviors and environmental compatibility of mortar mixture, the application of 50 % T-CRTF glass sand in FA mortar is the sustainable method to dispose CRT funnel glass.

Heavy Metal Recovery from Waste CRT Funnel Glasses by the Combined Process of Rapid phase-separation and Mechanochemical Extraction

An innovative and sustainable method of extracting heavy metal oxides (PbO, BaO, and SrO) from a cathode ray tube (CRT) funnel glass was developed. Funnel glass was first remelted with 20 wt % B2O3 at 1000 °C for 30 min in air atmosphere. Most of the heavy metal oxides (PbO, BaO, and SrO) were quickly migrated from the funnel glass to the B2O3-rich phase. Then, heavy metal oxides were recovered efficiently from phase separation product by a sustainable wet ball-milling process (replaced the traditional strong acid) using ethylene diamine tetraacetic acid (EDTA) as extraction reagent at room temperature. Mechanical activation caused the rapid dissolution of the B2O3-rich phase in water. Thus, heavy metal cations (Pb2+, Ba2+, and Sr2+) could be extracted as a metal-EDTA, and the solid residue was high silica glass powder (silica purity >92 wt %). The extraction rates of Pb, Ba, and Sr were 95.74%, 93.57%, and 94.76% when only milling for 5 min and reached 99.35%, 98.07%, and 96.40% for 60 min under optimum conditions: EDTA adding amount, 2 g; rotational speed, 500 rpm; and water/solid ratio, 0.8, respectively. Heavy metal ions could be recovered by sulfate precipitation, and the soluble metal-EDTA could be transformed into solid EDTA when pH < 3. Thus, this paper provides a sustainable method for detoxification and reutilization of heavy metals containing silicate waste.

Pb Recovery of Waste Cathode Ray Tube Funnel Glass by PbO Vapor Vacuum Reduction (PVVR) Process and the Feasibility of Luminescent Glass Production

Pb Recovery of Waste Cathode Ray Tube Funnel Glass by PbO Vapor Vacuum Reduction (PVVR) Process and the Feasibility of Luminescent Glass Production

Mechanochemical activation for lead extraction from spent cathode ray tube

In this study, a mechanochemical activation technique to effectually extract lead from the funnel glass of cathode ray tube (CRT) is proposed. A planetary ball mill with zirconia balls (25:1 ratio) is employed for mechanochemical activation process in the presence of EDTA. About 85% of lead could be leached in 5 M NaOH solution at 80 °C. The effects of time and temperature on lead extraction were explored and a kinetic model was established to depict the kinetic relationship. The leaching process was contingent upon the mixed kinetic model and the calculated activation energy value was 39.44 kJ/mol. The proposed mechanism displayed that the chemical breakage in the glass inner structures increased the leachability of the activated lead glass. The mechanochemical activation with EDTA can be considered as an economic process for lead extraction from the CRT funnel glass.

Mix Design of High-Strength Concrete Incorporating Spherical and Crushed CRT Funnel Glass Waste

Cathode ray tube (CRT) funnel glass, due to its high content of lead oxide (PbO), is considered as hazardous waste. The growing volume of the disposed CRTs technology presents a risk of environmental contamination owing to the potential of toxic Pb metals leaching from glass. A typical way of recycling CRT funnel glass waste is by crushing it and partially replaced the cement and fine aggregates. However, this approach has been facing serious issues in terms of leaching of Pb. Hence, a new recycling method has been developed, that is by performing proper melting and annealing operations in producing the spherical CRT funnel glass (GS). GS does not show any harmful risk of the release of Pb to the environment. The Pb leaching value of CRT concrete specimens with GS is significantly lower than the allowable limit although it contains high concentration of PbO, 25%. While the performance of GS in leaching aspects have been determined, the optimum mix designs of high-strength concrete incorporating both GS and crushed CRT funnel glass (GC) as coarse aggregates yet remains to be investigated. Predominantly to provide a safe method of recycling CRT funnel glass as aggregate and to increase the confidence level of the industries, this paper addresses the mix design of high-strength concrete with GS and GC as coarse aggregates. Given the importance of selecting the materials and its contents, the influence of five parameters, i.e. water/binder (w/b) ratio, coarse aggregate (CA) content, superplasticizers (SP) dosage, and silica fume (SF) content were evaluated. It was found that the incorporating of GS and GC that differ in terms of morphologies (size, shape, texture) and water absorption rate than the natural rock have led to the increase of workability of CRT concrete mixtures, however, decrease the compressive strength. But the results also have highlighted that the CRT specimens that were designed with w/b ratio 0.31, 43% content of CA, 2% SP, and 10% SF were able to achieve the highest strength of 61 MPa, which was only 9% lower than control specimens. The optimum mix design of CRT concrete has greatly improved the strength of concrete and enhance its potential for future applications.

Potential use of spherical glass sourced from cathode ray tube funnel glass for the application as coarse aggregate in concrete

ABSTRACT Managing discarded waste cathode ray tube (CRT) funnels glass has become a major concern worldwide because it has toxic effects on the environment and human health if the hazardous lead leached to the surroundings. The common way of recycling this waste is by crushing it, where it was used as an alternative fine aggregate for concrete production. But the crushing technique has led to the formation of micro-cracks in the funnel glass products, causing to high lead leaching rate. On the other hand, recycling the CRT funnel glass waste through melting and annealing operations in producing the spherical CRT glass (GS) has proven will not danger the environment due to the leaching of lead. Therefore, this paper explored the feasibility of using GS as partial (20%, 50%) and full replacements (100%) of natural coarse aggregates in concrete. The workability, density, compressive strength, and splitting tensile strength were investigated. Given the importance of materials and exposure, the influence of silica fume content and CRT concrete strength subjected to high temperature were evaluated. Overall, the inclusion of GS increased the workability and decreased the density, but reduced the compressive and tensile strength. The use of GS as coarse aggregates should be limited to below 50% due to its negative impacts on the strength aspects have become obvious. However, the results show that the CRT concrete made with 20% GS and 10% silica fume have comparable properties with the control, 52 MPa where only 7% lower than control concrete. The addition of silica fume able to counteract the negative effect of GS.

The effect of melted-spherical and crushed CRT funnel glass waste as coarse aggregates on concrete performance

Waste management regarding discarded cathode ray tube (CRT) funnels glass has become a major concern worldwide due to its potential toxicological threat on the environment and surrounding population health. Conventional recycling process of CRT funnel glass waste typically involved a method of crushing and reutilization as fine aggregates for concrete works. However, this approach has been facing serious repercussions in terms of lead (Pb) leaching and concrete expansion due to the accompanying alkali-silica reaction (ASR). Hence, this study investigates the potential of exploiting alternative recycling method which incorporate the technique of melting and annealing in producing spherical CRT funnel glass (GS). CRT concrete containing GS and crushed CRT funnel glass (GC) as coarse aggregates in various ratios were tested for its properties concerning; workability, voids, mechanical strength, water absorption, drying shrinkage, alkali-silica reaction (ASR), leaching of Pb, and microstructure. Findings from this study had discovered the utilization of GS to have decreased the Pb leaching rate (0.516 mg/L) and ASR expansion (0.035%), which may be attributed to the minimal formation of micro-cracks as evidenced in the scanning of electron micrograph. Despite its strength reducing properties, combination of GS and GC at a specified ratio of 0.6:0.4 was found capable to achieve the highest CRT concrete strength of 64 MPa, only 12% lower than the control concrete specimen. Essentially, this research findings underpin the opportunities in the exploitation of recycling the CRT funnel glass as aggregate in the form of melted-spherical glass.

Acid and heat treatment to reduce lead leaching from cathode ray tube funnel glass

Acid and heat treatment to reduce lead leaching from cathode ray tube funnel glass

Utilization of waste cathode ray tube funnel glass for ultra-high performance concrete

Cathode ray tube (CRT) funnel glass is classified as a hazardous waste because it contains lead, which can endanger the environment and human health. In this paper, an innovative cementitious material, ultra-high performance concrete (UHPC) was introduced to recycle hazardous waste CRT without lead extraction. Crushed CRT funnel glass without lead extraction was used to replace sand as fine aggregate in various ratios in UHPC. The mechanical properties and toxic heavy metal leachability of UHPC were investigated. Results showed that the addition of CRT glass can increase the flowability and decrease the compressive and flexural strength of UHPC. Analyses by X-ray diffraction and scanning electron microscopy demonstrated that the CRT glass increases the porosity, inhibits cement hydration, and weakens the interfacial transition zone, resulting in the reduced strength of UHPC. Meanwhile, the leached lead concentration of UHPC was still below regulatory limit of U.S. code even when the replacement ratio reaches 100%. The working principle behind the sharp drop in leached lead in UHPC was proposed, that is the dense microstructure and low permeability coefficient of UHPC can effectively restrain the lead leaching from CRT glass. The findings of this study can provide an effective alternative to recycling hazardous waste CRT without limitations on the replacement ratio and safety concern.

Feasibility of using recycled CRT funnel glass as partial replacement of high density magnetite sand in radiation shielding concrete

Abstract The recycled cathode ray tube (CRT) funnel glass was used as replacement of magnetite sand in the concrete, and its mass replacement rates were 0, 20%, 40% and 60%, respectively. The flowability, apparent density and mechanical properties of the radiation shielding concrete were investigated, while its γ-ray radiation shielding parameters such as linear and mass attenuation coefficients (μ and μm, respectively), thickness values of half-value layer (hHVL) and tenth-value layer (hTVL) were obtained by theoretical calculation, experiment and Monte−Carlo N-Particle (MCNP) simulation code. The experimental results show that the flowability of the concrete increases significantly, whilst its apparent density, compressive strength and static elastic modulus decrease slightly. The calculated, simulated and experimental μm, μ, hHVL and hTVL values of all concrete samples are very consistent at the same γ-ray photon energy, and it is feasible to use MCNP code to simulate γ-ray radiation shielding parameters of materials. The calculated results show that in a wide range of γ-ray photon energy, the μm value of the concrete with CRT funnel glass replacing magnetite sand is improved effectively, and its radiation shielding performances are the same as those of the control concrete (M−1). By comprehensively comparing the flowability, mechanical properties and γ-ray radiation shielding properties, the concrete samples with 20%−40% funnel glass as fine aggregate have good performances.

An investigation on physical, mechanical, leaching and radiation shielding behaviors of barite concrete containing recycled cathode ray tube funnel glass aggregate

In order to explore the feasibility of using hazardous waste cathode ray tube (CRT) funnel glass to replace high density mineral aggregates in the radiation shielding concrete, various barite concrete samples were prepared with portland cement, ground funnel glass sand as the substitute for barite aggregates, and fly ash as mineral admixtures, and the rates of funnel glass for fine and coarse (5–10 mm) barite aggregate were 25%, 50%, 75%, 100% and 10%, 20%, 30%, respectively. The work performance, mechanical properties, dry shrinkage, alkali-silica reaction (ASR) expansion and lead leaching were investigated, and the γ-ray attenuation coefficients were obtained by experiment, XCOM program and MCNP code. The results show that the slump, ASR expansion and lead leaching of the concrete increase while its apparent density, mechanical properties, dry shrinkage, and γ-ray shielding properties decrease with the increase of the rate of funnel glass. Adding fly ash to the concrete can inhibit the leaching of Pb, and reduce the ASR expansion. The concrete samples with 25–50% fine funnel glass sand or 10–20% 5–10 mm coarse aggregate have good performances. The results show that it’s efficient, economical and environmental-benign to use funnel glass to produce the high density radiation shielding concrete.

Immobilization of Lead in Cathode Ray Tube Funnel Glass with Beneficial Use of Red Mud for Potential Application in Ceramic Industry

The soon-to-become obsolete cathode ray tube (CRT) funnel glass can cause a potential hazard to the environment because of its high level of lead content. Red mud is a hazardous material due to its...

Comparison of lead removal behaviors and generation of water-soluble sodium compounds in molten lead glass under a reductive atmosphere

Abstract We propose a method of reduction-melting at 1000 °C, using a sodium-based flux, to recover lead from cathode-ray tube funnel glass. To recover the added sodium from the treated glass, we combined a reduction-melting process with a subsequent annealing step at 700 °C, generating water-soluble sodium compounds in the molten glass. Using this combined process, this study compares lead removal behavior and the generation of water-soluble sodium compounds (sodium silicates and carbonates) in order to gain fundamental information to enhance the recovery of both lead and sodium. We find that lead removal increases with increasing melting time, whereas the generation efficiency of water-soluble sodium increases and decreases periodically. In particular, near 90% lead removal, the generation of water-soluble sodium compounds decreased sharply, increasing again with the prolongation of melting time. This is due to the different crystallization and phase separation efficiencies of water-soluble sodium in molten glass, whose structure continuously changes with lead removal. Previous studies used a melting time of 60 min in the processes. However, in this study, we observe that a melting time of 180 min enhances the water-soluble sodium generation efficiency.

Development of a novel recycling system for waste cathode ray tube funnel glass based on the integration of nanoscale Fe0 with ball milling

A novel and effective system was developed for recycling cathode ray tube (CRT) funnel glass wastes. Initially, the combination of nanoscale Fe0 with ball milling promoted lead transfer that was strongly encapsulated in the glass inner structure to the surface of funnel glass and/or adhere to iron substance due to the collapse of SiO bonds. This condition enhanced the dissolution of lead in the acid solution. A high lead extraction rate of 97.8% from funnel glass was achieved through nitric acid leaching by optimizing the operational parameters (Fe0/funnel glass mass ratio, 0.5:1; ball milling time; 72 h). Subsequently, lead sulfate, iron hydroxides, and sodium nitrate were gradually recovered from the acid leachate by using three simple operations, namely, sulfation, alkali neutralization, and salt evaporation. Meanwhile, the leaching results of short-term toxicity characteristic leaching (TCLP) and long-term multiple extraction procedures (MEP) clearly demonstrated that the residual high silica products (after acid leaching) had no impact on the environment and could be used to synthesize high value-added zeolites as raw materials. With the addition of Al sources, the complete conversion of high silica residues into high crystalline zeolites with high cation exchange capacity value was realized by applying an alkaline fusion method during the hydrothermal treatment. Furthermore, lead, NO−3, and SO2−4 concentrations of the resulting drainage were considerably lower than the relevant standard for surface water quality. Therefore, the proposed recycling system provided an eco-friendly and feasible technique for complete reutilization of obsolete CRT funnel glass.

Lead extraction from Cathode Ray Tube (CRT) funnel glass: Reaction mechanisms in thermal reduction with addition of carbon (C)

This study quantitatively determined the extraction of lead from CRT funnel glass and examined the mechanisms of thermally reducing lead in the products of sintering Pb-glass with carbon in the pre-heated furnace. The experimentally derived results indicate that a 90.3 wt% lead extraction efficiency can be achieved with 20 wt% of C addition at 950 °C for 3 min under air. The formation of viscous semi-liquid glass blocked the oxygen supply between the interaction of C and Pb-glass, and was highly effective for the extraction of metallic Pb. A maximum of 87.3% lead recover was obtained with a C to Na2CO3 ratio of 1/3 at 1200 °C. The decrease of C/Na2CO3 ratio enhanced the metallic lead recovery by increasing the glass viscosity for effective sedimentation of metallic lead in the bottom. However, with the further increase of temperature and treatment time, re-vitrification of lead back to silicate-glass matrix was detected in both Pb-glass/C and Pb-glass/C/Na2CO3 systems. The findings indicated that with proper controls, using C as an inexpensive reagent can effectively reduce treatment time and energy, which is crucial to a waste-to-resource technology for economically recovering lead from the waste CRT glass.

Lead extraction and glass-ceramics synthesis from waste cathode ray tube funnel glass through cooperative smelting process with coal fly ash

In this study, a novel process was developed for extracting lead from the hazardous waste cathode ray tube (CRT) funnel glass and simultaneously producing glass-ceramics. CRT funnel glass was mixed with coal fly ash and subjected to carbon thermal reduction with the addition of CaO. The homogeneous glass melt and reduced metallic lead were quenched in water. Glass-ceramics were produced from the parent glass through an appropriate heat treatment. The optimum carbon loading amount (calculated as the molar ratio of C/PbO), CaO/SiO2 ratio, smelting temperature and holding time for lead recovery were 1.0, 0.3–0.6, 1450 °C and 2 h, respectively. Under these conditions, more than 95% of lead can be extracted from the funnel glass and a low lead content of the resultant parent glass below 0.6 wt% was successfully achieved. CaO behaved as a network modifier to reduce the viscosity of the glass and also acted as a substitution to release lead oxide from the silicate network structure, resulting in a high lead separation efficiency. X-ray diffraction (XRD) analysis revealed that the main crystalline phase was gehlenite when 50–70 wt% funnel glass was added. Scanning electron microscopy (SEM) observation showed that well-crystallized crystals occurred in the specimens with 50–70 wt% funnel glass additions, whereas the specimens with 40 wt% and 80 wt% glass additions exhibited a relative low crystallization degree. Furthermore, property measurements, chemical resistance tests and leaching characteristics of heavy metals confirmed the possibility of engineering and construction applications of the superior glass-ceramic products. Overall results indicate that the process proposed in this paper is an effective and promising approach for reutilization of obsolete CRT funnel glass.

Combined Fe2O3 and CaCO3 Additives To Enhance the Immobilization of Pb in Cathode Ray Tube Funnel Glass

Cathode ray tube (CRT) funnel glass has posed an increasing threat to the environment due to its rapid replacement by new technology in recent years. In this study, a well-control thermal scheme was applied for synthesizing a specific crystalline phase, PbFe12O19, for Pb immobilization when reusing CRT funnel glass as raw materials for the ceramics industry. The Fourier transform infrared spectroscopy results show that introduction of CaCO3 facilitated the breakage of strongly connected bonds between O–Si–O and Pb–O, which were firmly linked in the glass network. The X-ray diffraction results demonstrate that 30 wt % CaCO3 loading effectively facilitated the transformation of Pb in CRT funnel glass to the stable-phase PbFe12O19. A higher sintering temperature increased Pb transformation efficiency while a longer dwelling time only showed a slight increase in PbFe12O19 formation. The prolonged toxic characteristic leaching procedure results show a substantial improvement in the acid resistance (approximate...