Layers of injustice: A distributional assessment of toxic chemical facilities, releases, and cleanups.

The Resource Conservation and Recovery Act of 1976 (RCRA) is a cornerstone of environmental policy in the United States. The law regulates the generation, transportation, storage, and disposal of hazardous chemicals. Although regulated, hazardous releases can still occur at RCRA sites due to flawed equipment, human error, and dated historical practices. Releases are investigated and remediated through what is known as a Corrective Action (CA). Using Census data and a novel dataset of RCRA facilities across the contiguous U.S., we examine the possibility of systematic inequities with regards to the (i) siting of RCRA facilities, (ii) occurrence of releases and CAs, (iii) duration of CAs, and (iv) permanence of remediation methods. We find evidence of disproportionate impacts across racial, ethnic, and income dimensions. The results vary, however, depending on the different aspects of the siting and cleanup process, thus highlighting the need for multi-layered analyses to identify and fully understand potential inequities associated with environmental programs.

Treatment of chromium-containing sludge using sintering and ironmaking combined technology: A risk-reducing strategy for environmental impact.

The efficient, safe and eco-friendly disposal of the chromium-containing sludge (CCS) has attracted an increasing concern. In this study, Co-processing of CCS was developed via employing sintering and ironmaking combined technology for its harmless disposal and resource utilization. Crystalline phase and valence state transformation of chromium (Cr), technical feasibility assessment, leaching risk, characteristics of sintered products, and pollutant release during CCS co-processing were investigated through a series of laboratory-scale sintering pot experiments and large scale industrial trials. The results showed that the content of Cr(VI) in sintered products first increased then decreased with increasing temperature ranges of 300 °C-800 °C, and reached a maximum of 2189.64 mg/kg at 500 °C. 99.99% of Cr(VI) can be reduced to Cr(III) at above 1000 °C, which was attributed to the transformation of the Cr(VI)-containing crystalline phases (such as, MgCrO4 and CaCrO4) to the (Mg, Fe2+)(Cr, Al, Fe3+)2O4. The industrial trial results showed that adding 0.5 wt‰ CCS to sintering feed did not have adverse effects on the properties of the sintered ore and the plant's operating stability. The tumbler index of sinter was above 78% and the leaching concentrations of TCr (0.069 mg/L) was significantly lower than the Chinese National Standard of 1.0 mg/L (GB5085.3-2007). The TCr contents of sintering dust and blast furnace gas (BFG) scrubbing water were less than 0.19 wt‰ and 0.11 mg/L, respectively, which was far below the regulatory limit (1.5 mg/L, GB13456-2012). The mass balance evaluation results indicated that at least 89.9% of the Cr in the CCS migrated into the molten iron in the blast furnace (BF), which became a useful supplement to the molten iron. This study provided a new perspective strategy for the safe disposal and resource utilization of CCS in iron and steel industry.

Transformation behavior of heavy metal during Co-thermal treatment of hazardous waste incineration fly ash and slag/electroplating sludge.

In this study, the behavior of heavy metal transformation during the co-thermal treatment of hazardous waste incineration fly ash (HWIFA) and Fe-containing hazardous waste (including hazardous waste incineration bottom slag (HWIBS) and electroplating sludge (ES)) was investigated. The findings demonstrated that such a treatment effectively reduced the static leaching toxicity of Cr and Pb. Moreover, when the treatment temperature exceeded 1000 °C, the co-thermal treated sample exhibited low concentrations of dynamically leached Cr, Pb, and Zn, indicating that these heavy metals were successful detoxified. Thermodynamic analyses and phase transformation results suggested that the formation of spinel and the gradual disappearance of chromium dioxide in the presence of Fe-containing hazardous wastes contributed to the solidification of chromium. Additionally, the efficient detoxification of Pb and Zn was attributed to their volatilization and entry into the liquid phase during the co-thermal treatment process. Therefore, this study sets an excellent example of the co-thermal treatment of hazardous wastes and the control of heavy metal pollution during the treatment process.

Assessment and characterization of solid and hazardous waste from inorganic chemical industry: Potential for energy recovery and environmental sustainability.

Rapid global urbanization and economic growth have significantly increased solid waste volumes, with hazardous waste posing substantial health and environmental risks. Co-processing strategies for industrial solid and hazardous waste as alternative fuels highlight the importance of integrated waste management for energy and material recovery. This study identifies and characterizes solid and hazardous industrial wastes with high calorific values from various industrial processes at Nirma Industries Limited. Nine types of combustible industrial wastes were analyzed: discarded containers (W1), plastic waste (W2), spent ion exchange resins from RO plants (W3), sludge from effluent treatment in soap plants (W4), glycerine foot from soap plants (W5), rock wool puff material (W6), fiber-reinforced plastic waste (W7), spent activated carbon (W8), and spent cartridges from reverse osmosis plants (W9). Physical characterization, proximate and ultimate analysis, heavy metal concentration evaluation, and thermogravimetric analysis were conducted to assess their properties, revealing high calorific values exceeding 2500 kcal/kg. Notably, W1 and W2 exhibited the highest calorific values (∼10,870 kcal/kg), followed by W6 and W8 (∼6000 kcal/kg) and W9 (∼8727 kcal/kg). Safe heavy metal levels are safe, and high calorific values support the prospects of energy recovery and economic and environmental benefits, reducing landfill reliance and enhancing sustainable waste management.

Solidification and utilization of municipal solid waste incineration ashes: Advancements in alkali-activated materials and stabilization techniques, a review.

Researchers are actively investigating methodologies for the detoxification and utilization of Municipal Solid Waste Incineration Bottom Ash (MSWIBA) and Fly Ash (MSWIFA), given their potential as alkali-activated materials (AAMs) with low energy consumption. Recent studies highlight that AAMs from MSWIFA and MSWIBA demonstrate significant durability in both acidic and alkaline environments. This article provides a comprehensive overview of the processes for producing MSWIFA and MSWIBA, evaluating innovative engineering stabilization techniques such as graphene nano-platelets and lightweight artificial cold-bonded aggregates, along with their respective advantages and limitations. Additionally, this review meticulously incorporates relevant reactions. Recommendations are also presented to guide future research endeavors aimed at refining these methodologies.

A review of cleaner production of glass-ceramics prepared from MSWI fly ash.

Municipal solid waste incineration (MSWI) fly ash, classified as a hazardous waste due to its high toxicity, poses a significant environmental challenge that existing treatment methods struggle to manage effectively. Although high-temperature thermal treatment has proven effective in handling hazardous waste, its large-scale industrial adoption is hindered by the associated high costs and energy demands. A promising alternative is the conversion of MSWI fly ash into high-value glass-ceramic materials, which presents both environmental and economic benefits. This review provides insights into a cleaner production technique for glass-ceramics derived from MSWI fly ash. It begins with an analysis of the physical and chemical characteristics of MSWI fly ash and its environmental impact. The review then explores advancements in MSWI fly ash-based glass-ceramic production, mainly focusing on the processes of crystallization and the immobilization of heavy metals. Furthermore, the potential for heat recovery is considered, with a discussion on optimizing the heat treatment process for sustainable and cleaner production. The review concludes by proposing a systematic approach to reduce energy consumption, demonstrating the potential to save approximately 39.5 % at least compared to traditional methods.

Factors influencing illegal dumping of hazardous waste in China.

In recent years, illegal dumping of hazardous waste (IDHW) in China has become a recurring problem. Effective identification and exploration of the factors influencing illegal dumping are crucial for incident prevention and hazardous waste management, but its analysis has rarely been reported. Thus, this study focused on 568 cases of IDHW officially reported by the government. Through regular expressions, the categories of dumped wastes and the provinces where the incidents occurred were extracted. Furthermore, a comprehensive set of influencing factors was constructed by text mining for the case content and by the integration from the existing literature. On this basis, the unstructured and structured data were integrated using a Boolean dataset to respectively explore the association rules of influencing factors for the overall IDHW and for major waste categories, in conjunction with the extracted province information. Subsequently, a Bayesian network was constructed by utilizing the results of association rules mining and the key factors were identified through corresponding analysis. The findings of this study reveal a close connection between various influencing factors, with distinct key factors identified for different categories of hazardous waste. Among them, law-enforcement emerges as a crucial factor in most IDHW cases, while the factor of public monitoring for metallic hazardous waste and the factor of government supervision for distillation residue waste and other waste play a key role in their respective cases of illegal dumping. These findings offer a fresh research perspective for investigating the factors influencing IDHW and present helpful insights for developing effective strategies to prevent and control such incidents.

Hazardous waste management (Buxus papillosa) investment for the prosperity of environment and circular economy: Response surface methodology-based simulation.

Dealing with the current defaults of environmental toxicity, heating, waste management, and economic crises, exploration of novel non-edible, toxic, and waste feedstock for renewable biodiesel synthesis is the need of the hour. The present study is concerned with Buxus papillosa with seeds oil concentration (45% w/w), a promising biodiesel feedstock encountering environmental defaults and waste management; in addition, this research performed simulation based-response surface methodology (RSM) for Buxus papillosa bio-diesel. Synthesis and application of novel Phyto-nanocatalyst bimetallic oxide with Buxus papillosa fruit capsule aqueous extract was advantageous during transesterification. Characterization of sodium/potassium oxide Phyto-nanocatalyst confirmed 23.5 nm nano-size and enhanced catalytic activity. Other characterizing tools are FTIR, DRS, XRD, Zeta potential, SEM, and EDX. Methyl ester formation was authenticated by FTIR, GC-MS, and NMR. A maximum 97% yield was obtained at optimized conditions i.e., methanol ratio to oil (8:1), catalyst amount (0.37 wt%), reaction duration (180 min), and temperature of 80 °C. The reusability of novel sodium/potassium oxide was checked for six reactions. Buxus papillosa fuel properties were within the international restrictions of fuel. The sulphur content of 0.00090% signified the environmental remedial nature of Buxus papillosa methyl esters and it is a highly recommendable species for biodiesel production at large scale due to a t huge number of seeds production and vast distribution.

Influence of chlorine on co-processing of hazardous wastes in brick kilns.

Brick kiln co-treatment is a novel industrial hazardous wastes (IHWs) utilization process. However, the effects of chlorine (Cl) in wastes on heavy metals (HMs) during this process are overlooked. This study investigated the stabilization/solidification (S/S) and volatilization, as well as long and short-term leaching, of HMs in Cl-containing bricks. The results indicated enhanced formations of stable mineral phases (NiFe2O4, Ni2SiO4, Cd3Al2Si3O12, CdSiO3, FeCr2O4, Cr2O3, CuFe2O4, and CuAl2O4) in bricks at a low sintering temperature (800 °C) due to the affinity between Cl and HMs. By comparing HM concentrations before and after sintering in bricks, the study observed that Cl's presence significantly elevated the volatilization rates for Cd and Cu by 30.8% and 14.2%, respectively. In contrast, the effect on volatilization for Ni and Cr was not significant. Additionally, utilizing the NEN 7375 method, the cumulative leaching rates of Ni, Cd, Cr, and Cu over a 64-day experiment under extremely acidic conditions were 0.22%, 7.18%, 0.01%, and 1.46%, respectively. Similarly, higher short-term leaching rates of Cd (4.03%) and Cu (5.73%) than those of Ni (0.94%) and Cr (0.08%) were observed. This finding might be attributed to the lower stability of the Cd and Cu solid phases under acidic environments compared to those of Ni and Cr. Surface wash-off, dissolution, and diffusion were the processes governing HM leaching from bricks. The 10-year projections revealed a minimal release of HMs during future extended leaching, implying the successful S/S of HMs. This study provides a reference for assessing the environmental impacts of brick kiln co-processing of Cl-containing IHWs.

Neurodevelopmental outcomes in children living near hazardous waste sites: a systematic review.

Mismanagement of hazardous waste (HW) causes severe threats to ecosystems and human health. We conducted a systematic literature review and evaluated the evidence regarding the association between residential exposure to HW and childhood neurobehavioral effects. We consulted international agencies websites and conducted a search on MEDLINE and EMBASE databases by applying a "Population-Exposure-Comparator-Outcome" question. The evidence evaluation, based on the quality of the studies and their concordance, was graded in sufficient/limited/inadequate. Documents from international agencies were not found. Of the seventy-five studies screened, nine met the eligibility criteria. Studies agree on the association between residential exposure to HW sites and negative neurodevelopmental effects. The evidence of the association was attributed limited to cognitive and behavioral outcomes, and inadequate to Autism Spectrum Disorder. The evidence was evaluated sufficient for HW sites releasing lead and cognitive disorders. Residential exposure to unsafe HW sites may contribute to childhood neurobehavioral alterations. It is urgent to implement environmental remediation of contaminated sites and counteracting illegal and unsafe HW management practices.

History and investigation of the chemical odors and explosion in the University Avenue sanitary sewer.

During the summer of 2022, a fire and explosion occurred in a sanitary sewer tunnel adjacent to the University of Minnesota Twin Cities campus, propelling utility maintenance covers several meters into the air and jeopardizing the safety of the public and emergency responders. The investigation into the explosion highlighted the complex variables involved in the response to sanitary sewer events. This case study outlines current approaches and proposes recommendations for agencies to be better prepared to prevent, detect, and respond to sewer-related incidents in the future. Our recommendations include the following: (1) proactive use of remote volatile organic compound (VOC) and lower explosive limit (LEL) monitoring in sanitary sewer tunnels, especially downstream of waste discharge sites; (2) incident responders should have access to instruments that measure oxygen, LEL, VOC concentration, carbon monoxide, and hydrogen sulfide; (3) better characterization of the relationship between sewer pressurization, elevation profiles, and vapor movement; (4) verification processes for oil/water separators used by industrial facilities discharging into the sanitary sewer system; (5) installation of ventilated or anchored pressure relief utility maintenance covers where allowed by code; and (6) building maintenance protocols that include regular drain flushing to keep drain traps filled. These measures are recommended to protect infrastructure and the health and safety of the public and the responders.

Proposal for a framework for environmental zoning of areas near gold mines based on the distribution of potentially toxic elements, pollution indices, and bioindicators: a case study in Antioquia, Colombia.

Gold mining, even under strict environmental regulations, inevitably causes environmental impacts and liabilities. To address this, the study proposes a framework for environmental zoning around gold mines based on the distribution of potentially toxic elements (PTEs), pollution indices, and bioindicators. Soil samples were collected from municipalities affected by gold mining projects, and concentrations of As, Cd, Pb, and Cr were measured. Then, the Pollution Load Index (PLI) was calculated. A plant model was used for the biomonitoring of PTEs, and the Plant Vigor Index (PVI) was determined. Finally, environmental zoning was proposed through geospatial analysis combining PTEs, PLI, and PVI values. The concentrations of PTEs were as follows: As ranged from 1.7 to 892, Cd from 0.1 to 65.2, Pb from 18.5 to 2345, and Cr from 5.4 to 118.4. Spearman's rank correlation showed significant relations (ρ > 0.76) between bioindicators and PTE concentrations and PLI. The PVI correlated significantly with PTE concentrations (ρ - 0.41 to - 0.67) and PLI (ρ - 0.65). The municipalities were categorized into three zones: highly contaminated, moderately contaminated, and minimally contaminated. Overall, the environmental zoning maps serve as a management tool for environmental monitoring.

Large Virtual Transboundary Hazardous Waste Flows: The Case of China.

The Basel Convention and prior studies mainly focused on the physical transboundary movements of hazardous waste (transporting waste from one region to another for cheaper disposal). Here, we take China, the world's largest waste producer, as an example and reveal the virtual hazardous waste flows in trade (outsourcing waste by importing waste-intensive products) by developing a multiregional input-output model. Our model characterizes the impact of international trade between China and 140 economies and China's interprovincial trade on hazardous waste generated by 161,599 Chinese enterprises. We find that, in 2015, virtual hazardous waste flows in China's trade reached 26.6 million tons (67% of the national total), of which 31% were generated during the production of goods that were ultimately consumed abroad. Trade-related production is much dirtier than locally consumed production, generating 26% more hazardous waste per unit of GDP. Under the impact of virtual flows, 40% of the waste-intensive production and relevant disposal duty is unequally concentrated in three Chinese provinces (including two least-developed ones, Qinghai and Xinjiang). Our findings imply the importance of expanding the scope of transboundary waste regulations and provide a quantitative basis for introducing consumer responsibilities. This may help relieve waste management burdens in less-developed "waste havens".

Ingenious use of autocatalytic hydrodeoxygenation for the separation and recovery of oil and iron from rolling oil sludge.

This paper introduces a transformative hydrodeoxygenation process for the simultaneous recovery of oil and iron from hazardous rolling oil sludge (ROS). Leveraging the inherent catalytic capabilities of iron/iron oxide nanoparticles in the sludge, our process enables the conversion of fatty acids and esters into hydrocarbons under conditions of 4.5 MPa, 330 °C, and 500 rpm. This reaction triggers nanoparticle aggregation and subsequent separation from the oil phase, allowing for effective resource recovery. In contrast to conventional techniques, this method achieves a high recovery rate of 98.3% while dramatically reducing chemical reagent consumption. The reclaimed petroleum and iron-ready for high-value applications-are worth 3910 RMB/ton. Moreover, the process facilitates the retrieval of nanoscale magnetic Fe and Fe0 particles, and the oil, with an impressive hydrocarbon content of 87.8%, can be further refined. This energy-efficient approach offers a greener, more sustainable pathway for ROS valorization.

Safe handling of hazardous drugs.

Background: This evidence-based practice guideline was developed to update and address new issues in the handling of hazardous drugs including being compliant with NAPRA (National Association of Pharmacy Regulatory Authorities) and USP 800 (United States Pharmacopeia) standards, the use of personal protective equipment and treatment in diverse settings including in the home setting. Methods: This guideline was developed from an adaptation and endorsement of existing guidelines and from three systematic reviews. Prior to publication, this guideline underwent a series of peer, patient, methodological and external reviews to gather feedback. All comments were addressed and the guideline was amended when required. This guideline applies to and is intended for all health care workers who may come into contact with hazardous drugs at any point in the medication circuit. Results: The recommendations represent a reasonable and practical set of procedures that the intended users of this guideline should implement to minimize the opportunity for accidental exposure. These recommendations are not limited to just the point of care, but cover the entire chain of handling of cytotoxics from the time they enter the institution until they leave in the patient or as waste. Conclusions: Decreasing the likelihood of accidental exposure to cytotoxic agents within the medication circuit is the main objective of this evidenced-based guideline. The recommendations differ slightly from previous guidelines due to new evidence.

Data-driven models applying in household hazardous waste: Amount prediction and classification in Shanghai.

Precisely predicting the amount of household hazardous waste (HHW) and classifying it intelligently is crucial for effective city management. Although data-driven models have the potential to address these problems, there have been few studies utilizing this approach for HHW prediction and classification due to the scarcity of available data. To address this, the current study employed the prophet model to forecast HHW quantities based on the Integration of Two Networks systems in Shanghai. HHW classification was performed using HVGGNet structures, which were based on VGG and transfer learning. To expedite the process of finding the optimal global learning rate, the method of cyclical learning rate was adopted, thus avoiding the need for repeated testing. Results showed that the average rate of HHW generation was 0.1 g/person/day, with the most significant waste categories being fluorescent lamps (30.6 %), paint barrels (26.1 %), medicine (26.2 %), battery (15.8 %), thermometer (0.03 %), and others (1.22 %). Recovering rare earth element (18.85 kg), Cd (3064.10 kg), Hg (15643.43 kg), Zn (14239.07 kg), Ag (11805.81 kg), Ni (4956.64 kg) and Li (1081.45 kg) from HHW can help avoid groundwater pollution, soil contamination and air pollution. HVGGNet-11 demonstrated 90.5 % precision and was deemed most suitable for HHW sorting. Furthermore, the prophet model predicted that HHW in Shanghai would increase from 794.43 t in 2020 to 2049.67 t in 2025.

Review on treatment and utilization of barium slag in China.

Barium slag (BS) is generated as a by-product waste during the production of barium salts from barite. A large amount of BS is discharged annually threating the ecological environment and restricting the development of the barium salts industry. In China, BS is classified as hazardous waste due to its corrosivity, and more importantly because of its extraction toxicity of barium. Soluble barium is toxic and can result in barium poisoning for environment and human beings. The current review presents a detailed summary on general characteristics, discharge and disposal status, harmless treatment pathways and comprehensive utilization of BS in China. BaO, SiO2, CaO, and SO3 occur as main chemical compositions in BS, especially BaO accounting approximately for 35-40%. The mineral compositions include unreacted barite, quartz, clay minerals, newly-formed phases from the side reactions such as BaCO3, BaSiO3 and BaSO3, and residual carbon. A special attention is given to the assessment of the harmless treatment methods for BS from hazardous waste to general waste, which will decrease its management costs. Precipitation and solidification of soluble barium is the common pathway for harmless treatment of BS, and the using of other industrial waste can realize cost-saving. Methods for comprehensive utilization of BS include recovery of barium and carbon, application in building materials, and using as adsorbents for wastewater treatment. In particular, we analyzed and discussed the advantages and disadvantages of these existing process routes, intending to promote potentials for comprehensive utilization of BS in the future.

Co-vitrification of hazardous waste incineration fly ash and hazardous waste sludge based on CaO-SiO2-Al2O3 system.

Based on the CaO-SiO2-Al2O3 system, the feasibility of co-vitrification of hazardous waste incineration fly ash (FA) and hazardous waste sludge (HWS) was verified. In the CaO-SiO2-Al2O3 ternary system diagram, the melting point of the system gradually decreases with an appropriate increase in SiO2 content when the CaO/Al2O3 ratio is determined to be approximately 1. The TG-DSC results revealed that the liquid phase generation temperature in the FA and HWS mixture system was significantly lower than those of FA and HWS individually owing to the different CaO, SiO2, and Al2O3 contents; this is consistent with the results of the theoretical melting characteristics analysis, which show that the melting characteristic temperatures can be reduced by controlling the CaO-SiO2-Al2O3 ratio in the system. The co-vitrification experimental results confirmed that a vitreous content above 92%, a loss ratio on acid dissolution less than 1.74%, and leaching toxicity of heavy metals lower than 0.15 mg/L could be obtained by adjusting the CaO, SiO2, and Al2O3 contents in the FA and HWS system to 20 wt%-32.5 wt%, 35 wt%-61 wt% and 14 wt%-32.5 wt%, respectively, and under a melting temperature of 1350 °C.

Insight into the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans in hazardous waste incineration and incinerators: Formation process and reduction strategy.

Incineration technology has been widely adopted to safely dispose of hazardous waste (HW). While the incineration process causes the formation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). Due to its extreme toxicity, many scholars have been committed to determining the PCDD/F formation process and reducing emissions in incinerators. Previous studies ignored the impact of incineration and fluctuation of feeding materials on PCDD/F formation in hazardous waste incinerators (HWIs). In this study, differences in PCDD/F formation between HWIs and municipal solid waste incinerators (MSWIs) were pointed out. The incineration section in HWIs should be carefully considered. Laboratory experiments, conventional analysis and thermogravimetry experiments were conducted. An obvious disparity of PCDD/F formation between 12 kinds of HWs was found. Distillation residue was found with remarkably higher PCDD/F concentrations (11.57 ng/g). Except for the Cl content, aromatic rings and C-O bond organics were also found with high correlation coefficients with PCDD/F concentrations (>0.92). And PCDD/Fs were formed through a chlorination process and structure formation process. All of these are helpful to further understand the PCDD/F formation process during HW incineration, optimize the operation conditions in HWIs and reduce the emission pressure of PCDD/Fs in the future.

Thermal plasma vitrification treatment of oil-based drill cuttings: Product characterization and harmless transformation.

Oil-based drill cuttings (OBDCs) are hazardous wastes associated with the process of oil and gas extraction. In this paper, OBDCs were treated using a self-designed plasma vitrification system. The basic physicochemical properties of the OBDCs were analyzed, followed by a plasma vitrification mechanism investigation of the OBDCs. The environmental pollution risk of the vitreous slags obtained from thermal plasma treatment was also evaluated with the heavy metal extraction toxicity procedure. The batch of vitreous slags with an average glass phase content of 98.60% had a dense and smooth surface and an oxygen-to-silicon (O/Si) ratio ranging from 3.68 to 4.32, according to the findings. The melting temperature and treatment duration have a great effect on the loss ratio on acid dissolution. The leaching concentrations of Pb and Zn were 0.0004 mg/L and 0.068 mg/L, respectively, consistent with the chlorination reaction promoted by thermal plasma. Fourier transform infrared spectroscopy analysis showed that there was no organic matter in the vitreous slag, achieving the goal of harmless transition. The specific energy consumption of vitreous slags was predicted and verified by response surface methodology (RSM). This study describes the vitrification process and harmless treatment of OBDCs by thermal plasma technology, and vitreous slags have great potential for resource utilization.