The valorization of flotation tailings in terms of the concept of the circular economy: characterization, environmental risk assessment, and waste utilization routes

Flotation tailings (FT), as a product of the exploitation and processing of copper ore, represent a significant environmental and health risk due to the high content of heavy metals and sulfide compounds. Contemporary concepts of sustainable development and circular economy increasingly emphasize the need for rational use of resources and minimization of all types of waste, including mining waste. In this context, the reuse of flotation tailings in the construction industry represents a significant step towards closing the material flow in the mining and construction sectors. In order to reduce the negative impact of FT on the environment, the possibility of its application as a substitute for a portion of cement in the production of concrete was investigated. The main challenge is to reduce the negative impact of sulfides, originating from sulfide compounds, in order to achieve the desired concrete quality. Limestone aggregates of different size fractions (0/4, 4/8, 8/16 mm) were used for sulfide neutralization. Pyrite concentrate was used as a sulfide source, which together with FT provides the mixtures FT-7, FT-14, FT-25, and FT-40, with sulfur contents of 7.56, 13.84, 25.02, and 39.82%, respectively. FT mixtures were used as a substitute for Portland cement (PC) in the preparation of concrete. Test methods included XRD (X-ray diffraction), XRF (X-ray fluorescence), SEM (scanning electron microscopy), LP (leaching procedure), TCLP (toxicity characterization leaching procedure), assessment of acid eluate generation potential (AP—acid potential, NP—neutralization potential, and NNP—net neutralization potential), NEN (determination of heavy metals in cured concrete eluate), and UCS (uniaxial compressive strength of cured concrete). The results showed that the chemical characteristics of FT, as well as the chemical and mechanical properties of hardened concrete, allow the efficient use of these tailings in concrete mixes, which significantly utilizes FT, reduces the generation of mining waste, and contributes to the reduction of the negative impact on the environment and achieving sustainable development in mining.

Environmental quality is fundamental for the well being of human life. Environmental risk assessment and analysis have a crucial role for guaranteeing the safety of the population, especially in intensive urbanized and industrialized areas, such as the Campania region (Italy). In Italy, after the Legislative Decree 152/2006, the environmental risk assessment has become mandatory for contaminated lands such as brownfields and dismantled industrial activities. Despite the importance and fragility of the soil, it is rarely taken into account as a resource to be preserved. Moreover, due to the heterogeneity of many variables involved in the process, the environmental and human health risk assessments are used at the scale of a site, while the regional evaluation is very difficult, and keeps the administration sceptical in taking it into account for land planning and decision-making processes. During the last years, some international methodologies for ecological and human health risk assessment have been developed by national environmental agencies in many industrialized countries. An idea recently took place regarding the protection of soils: the monitoring of soil should be limited only to risk areas, as opposed to monitoring systems covering the entire territory. Focusing monitoring in selected areas would help to define priorities, increase efficiency of monitoring activities and reduce the monitoring costs. This is the reason why many methodologies for preliminary and simplified risk assessment of (potentially) contaminated sites, for the prioritization and planning of soil remediation and protection programmes, were developed. The only lack that these methodologies have is the absence of the spatial analysis. The aim of this research was to implement the human health risk assessment. For the purposes of the study we used 3535 topsoil samples, collected across the whole regional territory. The concentrations of 53 elements have been determined at Bureau Veritas Analytical Lab. Ltd (Vancouver, Canada), by means of an Aqua Regia extraction followed by a combination of ICP-MS and ICP-AES methods. After the statistical and cartographic elaboration of these regional dataset, we integrated one of the model of relative risk assessment for single contaminated sites with spatial analysis procedures. In order to support the spatial assessment of contaminated sites at the regional scale, the most suitable tool is the Geographic Information System (GIS). A new approach was applied, in order to assess/rank environmental risk by using geospatial analysis in a GIS platform to adapt a European-wide accepted methodology for the preliminary assessment of human health risks at single contaminated sites to a regional scale. The developed regional risk assessment methodology can be used by the regional administrations to select at regional level the or priority areas. The identification of the problem areas is necessary for developing an efficient monitoring system and to produce a ranking of the risky areas to be used as a reference in determining the development of intervention plans, for better addressing the resources dedicated to the environmental remediation of widely contaminated regions. The methodology chosen as a reference for the risk assessment procedures is the PRA.MS (Preliminary risk assessment model for the identification of problem areas for soil contamination in Europe, 2005). Following the PRA.MS guidelines, a conceptual model for the human health risk assessment for the Campania region has been based on four different exposure routes: 1) dispersion of contaminants in groundwater, 2) dispersion in surface water, 3) dispersion in air, 4) direct contact with the contaminated media (soils). The source, the pathway and the receptor for each of the exposure route are scored on the base of a quantitative or qualitative analysis of some featuring characteristics (parameters). A total of 14 representative parameters were chosen, basing on the available regional data for Campania. Starting from these parameters values, the information is aggregated to higher levels in several steps, adopting a mixed additive and multiplicative algorithm, up to the overall risk score. The final risk map is classified according four classes of risk. This map was useful to identify the problem areas, characterized by a higher risk, where more detailed analysis had to be carried out. The identified area was located in a wide territory in the center of Campania region, between Avellino and Salerno municipalities, an high populated zone, where intensive agricultural and industrial activities are well developed. A high density survey has been carried out in this priority area; the concentrations of 53 elements have been measured on 102 new topsoil samples, followed by statistic and cartographic elaboration of the 15 potentially toxic elements (Sb, As, Be, Cd, Co, Cr, Cu, Hg, Ni, Pb, Se, Sn, Tl, V, Zn) for which the Italian legislation (D.Lgs. 152/06) established the trigger and action limits, by defining the contamination threshold values (CSC) for the amount of metals in topsoils or waters. The new methodology of GIS-based human health risk assessment has been again applied, in order to select sites of particular significance in terms of danger for the resident population. Some small areas characterized by high risk have been identified. New in situ measurements and classic follow up risk assessment should be here carried out to confirm if remediation actions are needed to guaranteeing the safety of the population. Other works has been contemporaneously elaborated during the PhD. Six months have been spent at the Geological Survey of Finland (GTK), where a work on a humus samples dataset have been carried out, under the supervision of Dr. Timo Tarvainen. Moreover a new Geochemical Atlas will be completed based on inorganic elements and organic compounds concentrations in marine sediments samples, collected in the Gulfs of Naples and Salerno.

The increased exploitation of ores leads to the generation of mining waste, which has a negative impact on the environment and human health. For this reason, it is necessary to take care of it in an adequate way by applying some of the possible treatments. In addition to protecting the environment by applying appropriate treatment, there is also the possibility of making a profit by valorizing useful elements from mining waste. In order to choose the most adequate treatment, it is necessary to perform the characterization of mining waste. This paper contains a detailed characterization of the flotation tailings deposited at the Old Flotation Tailings in eastern Serbia, originating from copper ore processing. Characterization includes physico-chemical analysis, polarizing microscope analysis, X-ray Diffraction analysis (XRD) and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) analysis analysis. The obtained results indicate that the investigated flotation tailings can be used as a secondary raw material for metal recovery, in this case primarily copper (whose content is about 0.24%), gold (with a content of about 0.43 ppm) and silver (with a content of about 1.7 ppm). Considering that the content of valuable elements is quite low, it is suggested to apply hydrometallurgical treatment for their recovery.

Biodegradation is an important removal mechanism for natural and synthetic organic chemicals released to aquatic, benthic, and terrestrial ecosystems. It results in a decrease in the overall mass or load of chemicals present in the environment and is key in preventing the accumulation and persistence of chemicals in specific environmental compartments. Although biodegradation is an important process for minimizing potential adverse impacts on environmental systems, it has not been traditionally considered in a quantitative fashion in environmental risk assessments. This article outlines an approach and provides simple kinetic criteria for incorporating biodegradation rate data into environmental exposure and risk assessments. The approach is a generic one that relates biodegradation half-lives to chemical residence times in specific environmental compartments. It is broadly applicable to any organic chemical in a range of environmental compartments and has potential use as a technical and regulatory tool to better quantify environmental exposure and risk.

Preface

Preface.- Acknowledgements.- Part 1. Environmental Security.- Environmental Security, Critical Infrastructure and Risk Assessment: Defmitions and Current Trends D.A. Belluck, R. Hull, S.L. Benjamin, I Alcorn, I. Linkov.- Security and the Environment in the Middle-East Water Issues B. Morel.- Potential of Solar Thermal Desalination to Defuse Water as a Conflict Issue in the Middle East - Proposal for Functional Cooperation in the Gulf of Aqaba H. G. Brauch.- Water Resources Management and Environmental Security in MediterraneanTransboundary River Basins I. Ganoulis .- The Role of Comparative Risk Assessment in Decision Analysis. Marshlands of Mesopotamia and Affected Riparian Countries C. Maxwell .- A Future for the Dead Sea Basin: Options for a More Sustainable Water Management C. Lipchin .- Are Standard Risk Acceptability Criteria Applicable to Critical Infrastructure Based on Environmental Security Needs? D.A. Belluck et al.- From global warming to water scarcity: what are the most urgent environmental problems of the region. Report of the discussion Group on Environmental Security A. Morel, B. Morel .- Part 2. Environmental Management.- The Interconnection Between the Built Environment, Ecology and Health H. S. Koren, C. D. Butler.- Statistical Models for Distributions of Ambient Fine Particulate Matter S. Yeh, M J. Small.- QnD: A Scenario-Based Gaming System for Modeling Environmental Processes and Management Decisions G. A. Kiker et al.- Mapping of Relative Risk U. Schlink et al. Understanding Risk Culture and Developing a 'Soft' Approach to Risk Assessment Methodologies S. Rao .- Different Preventive Strategies Require Diversified Risk Assessment Models S. Menoni.- Coupling Public Participation and Expert Judgment for Assessment of Innovative Contaminated Sediment Technologies T. P. Seager et al. Environmental Risk Assessment and Management: Promoting Security in the Middle East and in the Mediterranean Region.Report o fthe Working Group on Environmental Risk Assessment and Management J. Ganoulis, L. Simpson .- Part 3. Case Studies in Environmental Security and Environmental Management.- Reuse of Wastewater in Agriculture- Economic Assessment of Treatment and Supply Alternatives as Affecting Aquifer Pollution N. Haruvy.- Minimizing the Risks Associated with Water Scarcity S. Arlosoroff.- Integrated Risk-Based Management of Water Resources in the Jordan River Basin E. Levner.- Outcome of Nato Workshop on Radiological Risk in Central Asia M.K.. Zaidi et al.- Public Transport Policy & Measures That Could Improve the Air Quality in Major Cities in Syria, A Case Study: Damascus J. Chahoud .- The Modeling of Combine Impact of Waste Heat Discharge into Offshore Strip from Cooling Systems and Power Plants A. Andrijievskij et al.- Role of Synergy in Biological Risk Assessment N. Goncharova.- Cooperative Networks for Environmental Risk Analysis Studies: The Case of the Middle East Region M.K. Zaidi, I. Ganoulis.- List of Participants.- Author Index .-

The results show technological possibility and economical feasibility for joint processing of two technological waste materials generated in the process of copper ore treatment. Smelter slag and flotation tailings from the Mining and Smelting Basin - RTB Bor, Serbia, are two technological waste materials stored on dumps and emerging permanently. They represent the major polluters of the environment, but also the potential raw material resources, according to the content of useful components. Due to the specific physical, chemical and mineralogical characteristics, individual processing of these waste materials do not guarantee a profitable business. Joint processing of smelter slag and old flotation tailings, in mass ratio 90% of slag and 10% of flotation tailings, in the original process technology, increases recovery of copper in the flotation process for approximately 15%, efficiency of grinding and classification processes are also increasing, thereby power consumption is reduced 10 -15%, making the processing of these waste materials to have both the positive economic and ecological effect.

Awareness of environmental risk and the demand for oil spill response planning associated with offshore marine operations has increased during the last decades. Environmental Risk Assessments (ERAs) are a crucial part of planning and execution of oil and gas (O&G) activities offshore. A sound ERA can support the O&G industry in environmental risk management (ERM) of operations. Authorities and Operating companies have requested updated methodology based on more recent research from oil spill events such as the Deep Water Horizon incident, with the possibility to perform more detailed analyses in e.g. sensitive areas. ERA Acute is developed to meet these requirements. It is a transparent method of quantitative analysis for environmental screenings, ERAs and Net Environmental Benefit Analyses (NEBAs) of oil spills in four compartments: Sea surface, shoreline, water column and sea floor. The methodology is grid-cell based and results can therefore be shown in a geographical information system (GIS) for any region globally. The user can identify areas of high risk - for use in decision support and spill response planning - independently of the region. Three levels of detail are defined, depending on availability of VEC data, suitable for screening purposes or more detailed studies. Calculations are carried out in two main steps: First, ERA Acute uses input from an oil spill fate and distribution model of choice to calculate exposure and impact to Valued Ecosystem Components (VECs) in each grid cell and for each simulation. Calculations follow a common methodology framework, applying different mechanisms of impact and recovery for each compartment. Impacts are summarised, and in the second step, potential lag-and/or restitution time and risk are calculated for each VEC. The resulting resource impact factor (RIF) is an index that combines the extent of impact and recovery time. A statistical approach is used, based on numerous oil spill simulations covering each season in order to capture variations in spill drift and fate, species abundance and vulnerability. This paper describes the method. ERA Acute methodology is validated in sensitivity studies, field validations, comparison to relevant ERA methods, and documented in several dissemination steps including a guideline for best industry practice. The ERA Acute project is carried out by a consortium of industry partners (Statoil, Total, Norwegian Oil and Gas Association) and experts in environmental risk analysis (Acona, Akvaplan-niva (project manager), DNV-GL and SINTEF), supported by the Research Council of Norway.

Combined environmental and natural disaster risk assessment of tailing ponds in China and diverse responses analysis.

With the speed of industrialization in today’s global community, the costs of disparities in environmental health and risk assessment can be dangerously high in developing countries without broad, stable regulatory and protective measures in place. Addressing capacity-building problems will depend largely upon the implementation of proactive measures within the borders of these developing nations—measures that participants sought to create at the Risk Assessment and Quality Assurance Training Workshop of the African Society for Toxicological Sciences (ASTS), held 21–28 October 2006 in Limbe, Cameroon. The workshop was cosponsored by the NIEHS as part of its efforts to expand global environmental health initiatives, as outlined in the institute’s Strategic Plan. Forty-seven experts in toxicology research, environmental policy, and government from Cameroon, Nigeria, Sudan, South Africa, the United States, and Europe convened for the purpose of generating ideas for new sustainable development initiatives. Attendees also took part in training modules and a site visit to a local oil refinery. Sanmi Areola, a toxicologist with the Metro Nashville/Davidson County (Tennessee) Public Health Department and incoming ASTS president, says that organizations such as the ASTS serve as necessary bridges of communication between developed and developing nations. “Continuing and emerging environmental [and] public health issues present differently in Africa compared to the developed countries of the world primarily because of the lack of enforceable policies and regulations and the nonexistence of infrastructures, [which are] poor where and when they exist,” says Areola. He explains that the negative impacts of environmental stressors on public health in Africa are exacerbated by poverty, political instability, urbanization, and overpopulation, among other factors. “These issues must be addressed through a multifaceted, multidisciplinary, region-specific approach where the identification of hazards and characterization of the risks take into consideration the uniqueness of the African geopolitical and ecological divides,” he says. According to Areola, the ASTS is uniquely positioned to provide a platform and serve as the facilitator for a collaborative partnership with agencies from developed nations to build approaches for managing and alleviating these risks. In the past 10 years, the ASTS has built solid networking structures, working with policy makers, scientists, and agencies within and outside Africa. Outgoing ASTS president Hoffman Moka Lantum, director of practice variance with Excellus BlueCross BlueShield, agrees, saying that a multidisciplinary, international exchange of ideas has been and will continue to be integral to the success of the ASTS’s efforts. He points out that very few data are based on studies done in Africa despite exponential growth in the use of large-volume chemicals in the petrochemical, mining, agrochemical, textile, and food industries, plus disproportionate underlying disease and nutritional disorders from food deficiency and toxicity. “The effects of the chemical burden from imported new classes of drugs, detergents, and industrial hydrocarbons on the biology and ecology of Africa are largely unknown and unappreciated, and may never be talked about if our colleagues in developed countries do not participate in this [ongoing] discussion,” he says. Kenneth Olden, a founding member of the ASTS and past director of the NIEHS and the National Toxicology Program, says all parties can benefit from such collaborative efforts. “Environmental health issues are national in scope, so it is important that nations, including the United States, cooperate in research, training, and exchange of prevention and remediation technology. All nations, including the African nations, have much to contribute to environmental protection,” he says.

Floatation tailings (FT) are the main by-products of the hydrothermal sulfidation-flotation process. FT (FT1 and FT2) were obtained by treating two different neutralization sludges (NS) (NS1 and NS2). This paper quantitatively evaluated the environmental risks of heavy metals (Zn, Cd, Cu, Pb, and As) in FT versus NS. The total concentration and leaching rates (R 2) of heavy metals in FT were much lower than those in NS, demonstrating that the hydrothermal sulfidation-flotation process was able to effectively suppress the mobility and leachability of heavy metals. The BCR-three sequence leaching procedure of FT confirmed that all metals were transformed into more stable forms (residue and oxidizable forms) than were found that in NS. The potential ecological risk index indicated that the overall risks caused by heavy metals decreased significantly from 6627.59 and 7229.67 (very serious risk) in NS1 and NS2, respectively, to 80.26 and 76.27 (low risk) in FT1 and FT2, respectively. According to the risk assessment code, none of the heavy metals in FT posed significant risk to the natural environment except Zn (with low risk). In general, the risk of heavy metals in FT had been well controlled.

The flotation process is used to extract copper-molybdenum sulfide minerals from ore. The selection of the flotation technology scheme largely depends on factors such as the composition of sulfide ore in the ore body, grain size, and characteristics of the ore mineral association. The chemical and mineralogical analysis of flotation products was collected from the Erdenetiin Ovoo Cu-Mo porphyry deposit. The deposit is the largest porphyry copper-molybdenum deposit in Mongolia. The aim of this study was to demonstrate the occurrence mechanism of copper minerals in flotation tailing using the fully automated Tescan Integrated Mineral Analyzer. The chemical analysis of the flotation products (feed, concentrates and tailings) sample was conducted by X-ray fluorescence, and the mineralogical composition of the flotation feed sample was characterized using X-ray diffraction. The copper content of the flotation tailing was 0.024%. Mineralogical characterization results showed that almost all copper minerals occurred within coarse gangue particles, the primary and secondary copper minerals were accumulated in the size fractions less than 150 μm and 13.5 μm, respectively. The finest grain size distribution was observed in secondary copper particles of size -19 μm. Chalcopyrite was the main copper-bearing mineral, and it was closely associated with K-feldspar and silicate in the flotation tailings. The flotation tailing sample still contained 24.1 wt% liberated primary copper (chalcopyrite) and 24.13 wt% secondary copper due to their extremely fine grain size particle. The mineral map derived from Tescan Integrated Mineral Analyzer analysis revealed that copper minerals mainly occurred as finely disseminated and fully enclosed structures within gangue minerals.

Environmental hazard and risk assessment under the United States Toxic Substances Control Act

Environmental (hazardous chemical) risk assessment- era in the European Union

Variability of the copper isotopic composition in soil and grass affected by mining and smelting in Tsumeb, Namibia