Life cycle assessment and cost analysis for copper hydrometallurgy industry in China

Life cycle assessment of copper concentrate production and improvement potentials for tailing management

Due to the widespread application and development of copper, there is growing concern about increasing pressure on available resources and significant environmental repercussions. To support improvements in copper mining, this study addressed the life cycle assessment of copper concentrate production from cradle to gate, along with the feasibility of tailings reuse, which has received less attention. To fill a critical gap, the alternative use of tailings in building and landfilling disposal was also conducted. Sodium hydroxide (36.63%-95.22%), copper concentrate (4.73%-99.4%), and carboxymethyl cellulose (0.06%-46.35%) were identified as the main contributors. Marine ecotoxicity was prioritized in terms of environmental burdens (31.28%) followed by human toxicity and freshwater ecotoxicity potential. It is interesting to note that photovoltaic systems and treated wastewater provided the required energy and water for copper concentrate production, which alleviated the final impacts. For tailings management, it was initially found that landfilling intensified the environmental impacts by 1.67-65.15 times higher than copper production processing. However, the utilization of tailings in cement production and road construction provided environmental benefits and conserved resources. Summing up, this study provided additional insights into environmental indicators of the copper industry and tailings efficiency for future applications.

Assessing the environmental impacts of copper cathode production based on life cycle assessment

The demand for copper is growing considerably in parallel with economic and technological development. The rate increase in copper consumption in Iran increases pressure on the numerous unexploited mines in southeast Iran and causes the environmental crisis alongside the northern Levar wind in this area. Given this, this study systematically explored the environmental impacts of a one-ton copper cathode processing operation from a cradle-to-gate perspective, using life cycle assessment (LCA). Moreover, the release of greenhouse gases and the energy consumption during the copper cathode production were also assessed. The results indicated that sulfuric acid use in the smelting and extraction stages, metal leaching from tailings, and CO2 dominated more than 50% of contributions to freshwater and marine ecotoxicity, human toxicity, and global warming. The energy analysis revealed 88.92% of crude oil use especially for the electrowinning stage, which should be promoted technologically. For global warming, the indirect CO2 emission from electricity consumption using fossil fuels was the main contributor (94.56%). Therefore, shifting from conventional energy systems to renewable energy systems could alleviate the overall environmental impact. For a 0.57-ton sulfuric acid effluent per one ton of copper cathode production, its treatment and reuse in the process is recommended. Summing up, the results of this study provide the environmental hot spots for copper cathode production for further investigation. Integr Environ Assess Manag 2024;20:1180-1190. © 2023 SETAC.

Zero-carbon inertization processes of hazardous mine tailings: Mineral physicochemical properties, transformation mechanism, and long-term stability

Hazardous mine tailings (HMTs) dam failures can cause devastation to the ecology environment, people's lives and property, which require expensive and complicated remediation engineering systematacially. A cheap and sustainable inertization disposal is proposed for de-risking HMTs without any carbon emissions, stabilizing hazardous heavy metal cations within safety minerals and also sequestering CO2 in the process, simultaneously. Herein, lead-zinc tailings as target HMTs were inertized by using waste rice husk ashes (RHAs) and carbide slag (CS) with a certain ratio, and lead-zinc tailings hardened pastes (LZTHPs) were investigated based on the experimental performance, analytical characteristics, and simulation diffusion methods, to deeply unveil the minerals transformation mechanisms and long-term stability from the cation perspectives. Results revealed that LZTHPs' compressive strength ranged from 1.04-4.73 MPa and leaching toxicity concentrations of Pb, Zn, Cr, and Cd reached 0.03 mg/L, 1.78 mg/L, 0.01 mg/L, and 0.01 mg/L, respectively. C-S-H gels (Type I and II), cation hydroxides and CO2 mineralization carbonates were the hydrates in LZTHPs. Pb (86%), Zn (78%), Cr (76%), and Cd (65%) were immobilized as residual state, and CO2 mineralization capacity was 0.16 kg/kg. The diffusion coefficient of Pb, Zn, Cr, and Cd below 4.48 × 10-10 cm2/s, 1.39 × 10-10 cm2/s, 4.72 × 10-10 cm2/s, and 0.30 × 10-12 cm2/s, which would be sufficient in most scenarios to adequately stabilize tailings. Diffusion control is the leaching mechanism of cations. After 100 years of simulation diffusion, the diffusion areas of Pb, Zn, Cr, and Cd are 1.33 × 10-3∼1.49 cm2, 2.47 × 10-4∼0.48 cm2, 2.47-8.61 × 10-4 cm2, and 1.49 cm2, respectively, and the environmental impact of LZTHPs was negligible. This study provides promising solutions for alleviating hazardous tailings dangerous, achieving sustainable development with zero-carbon emission, implying the concept of eliminating waste by waste, synchronously.

Environmental and economic assessment of advanced oxidation for the treatment of unsymmetrical dimethylhydrazine wastewater from a life cycle perspective

As a high-performance liquid rocket fuel, unsymmetrical dimethylhydrazine (UDMH) will produce wastewater during transportation, storage and cleaning containers. The wastewater will have a bad impact on human health and ecological environment, and it must be properly handled. There are many reports about the technical feasibility of UDMH wastewater treatment. Less attention is paid to analyzing the impact on the environment during the treatment process. This paper quantifies the environmental impacts and economic benefits of four advanced oxidation processes for the treatment of UDMH wastewater based on life cycle assessment and life cycle costing methods. Taking the UDMH wastewater produced by an aerospace group of Tianjin, China as the research object, using Fenton method, UV-Fenton method, electro catalytic oxidation (EC) with ruthenium iridium titanium (Ti/TiO₂-RuO₂-IrO₂) as electrode and electro catalytic oxidation with boron-doped diamond (BDD) as electrode as treatment methods, on the basis of the laboratory test, the industrialized device is adopted. The resource consumption, energy consumption, pollutant discharge and cost were compared when the TOC removal rate was the same, and a better method of treating unsymmetrical dimethyl hydrazine wastewater was discussed. The results show that the impact on most types of environments is as follows: UV-Fenton < Fenton < EC (BDD) < EC (Ti/TiO₂-RuO₂-IrO₂), and the four advanced oxidation methods are all beneficial to reduce eutrophication. The life cycle cost of UV-Fenton is the lowest (US$1.53/m³). Combined with environmental and economic analysis, it can be seen that UV-Fenton is the best choice. Through sensitivity analysis, it can be seen that reducing chemical reagents and electricity consumption, and changing the way of generating electricity to renewable energy can significantly reduce the environmental and economic impact. The life cycle cost of EC(BDD) as the electrode is the highest (US$26.20/m³), but it can achieve a TOC removal rate of 97.75 %, so it is a better choice when only the removal rate is required regardless of cost.

Life Cycle Energy Consumption and GHG Emissions of the Copper Production in China and the Influence of Main Factors on the above Performance

The copper demand and production in China are the largest in the world. In order to obtain the trends of the energy consumption and GHG emissions of copper production in China over a number of years, this paper uses a life cycle analysis method to calculate the above two indexes, in the years between 2004 and 2017. The life cycle energy consumption ranged between 101.78 and 31.72 GJ/t copper and the GHG emissions varied between 9.96 and 3.09 t CO2 eq/t copper due to the improvements in mining and smelting technologies. This study also analyses the influence of electricity sources, auxiliary materials consumption, and copper ore grade on the life cycle performance. Using wind or nuclear electricity instead of mixed electricity can reduce energy consumption by 63.67–76.27% or 64.23–76.94%, and GHG emissions by 64.42–77.84% or 65.08–78.63%, respectively. The GHG emissions and energy consumption of underground mining are approximately 2.97–7.03 times that of strip mining, while the influence of auxiliary materials on the above two indexes is less than 3.88%.

Environmental impact of mining and beneficiation of copper sulphate mine based on life cycle assessment

China is a major producer of copper concentrate as its smelting capacity continues to expand dramatically. The present study analyzes the life cycle environmental impact of copper concentrate production, along with selection of a typical copper sulphate mine in China. Life cycle assessment (LCA) was conducted using SimaPro with ReCiPe 2016 method. The midpoint and endpoint results were performed with uncertainty information based on Monte Carlo calculation. Normalization of midpoint results revealed that impact from the marine ecotoxicity category was the largest contributor to the total environmental impact, followed by freshwater ecotoxicity, human carcinogenic toxicity, human non-carcinogenic toxicity, and terrestrial ecotoxicity. The mining activity, backfilling activity, and electricity generation were proved to be the dominant factors. In addition, main processes and substances to the identified key categories were also classified. Specifically, the cement production in the backfilling process, blasting activity, on-site emission, and electricity generation was regarded as the critical processes. Copper to air and zinc emission to water were considered the critical substances. The sensitivity analysis revealed the most effective measure to solve the environmental problems caused by the concentrate production process, which is controlling on-site emissions and reducing pollution from cement production. Finally, the corresponding technical and management measures were proposed to facilitate the development of cleaner metal industry.

Environmental Benefit Assessment of Blended Cement with Modified Granulated Copper Slag

This study aimed to investigate the environmental impact of modified granulated copper slag (MGCS) utilization in blended cement production at a representative cement plant in China. Sensitivity analysis was performed on the substance inputs, and the life cycle impact assessment (LCIA) model was applied. A detailed comparative analysis was conducted of the environmental impact of cement production in other studies, and ordinary Portland cement production at the same cement plant. Results showed that calcination has the largest contribution impact of all the impact categories, especially in causing global warming (93.67%), which was the most prominent impact category. The life cycle assessment (LCA) result of blended cement was sensitive to the chosen LCIA model and the depletion of limestone and energy. In this study, producing blended cement with MGCS effectively mitigated the environmental impact for all the selected impact categories. Results also show a reduction in abiotic depletion (46.50%) and a slight growth (6.52%) in human toxicity. The adoption of MGCS in blended cement would therefore generally decrease the comprehensive environmental impact of cement, which contributes to the development of sustainable building materials.

Cost-Effectiveness of Life Cycle Cost Theory-Based Large Medical Equipment

The purpose of this study is to use the life cycle cost theory to analyze the efficiency of large medical equipment in hospitals, so as to implement life cycle cost (LCC) management and solve the current problems in hospitals. The analysis model of cost benefit of large medical equipment is established, and the cost-effectiveness of 4 large medical equipment between 2019 and 2021 is investigated and analyzed. In terms of the data in each information system of hospitals, the utilization of large medical equipment is quantitatively evaluated and analyzed by life cycle theory. The results show that the Revolution 256 row has the highest revenue of 113.29%. The annual depreciation of Signa 3.0 T HDxt is the highest, amounting to 4,160,000 yuan. However, there is lack of quality control and preventive maintenance of most equipment during use. The cost and benefit of large medical equipment in hospitals are analyzed, which demonstrates that Signa 3.0 T HDxt shows better effectiveness. Too high hospital warranty cost reflects the weak maintenance strength of hospital engineering technicians. The fundamental point of the maintenance and management of large medical equipment is to strengthen the performance evaluation of medical engineering technicians.