Sustainable Mining and Metallurgy

Abstract:In this new developmental phase, it is of vital importance to elucidate the nexus between carbon emissions and growth in the steel industry, and delineate the carbon reduction pathway. This elucidation can catalyze high quality development in the steel sector and advance the “Dual Carbon” objectives within this realm. By utilizing carbon emissions data from China's steel industry for the period 2000—2019, the Tapio decoupling model was deployed to scrutinize the relationship between carbon emissions and industry growth. The Logarithmic Mean Divisia Index (LMDI) method was adopted for the decomposition of carbon emission drivers. The study indicates that from 2000 to 2019, the decoupling state between carbon emissions and industry growth in China's steel industry was primarily weak, demonstrating relative stability. The production scale effect and resource efficiency effect are the chief propellants of rising carbon emissions, whereas the energy structure and consumption intensity effects serve to restrain emissions. To facilitate a reduction in carbon emissions in the steel industry and foster high quality development under low carbon emissions, it is recommended to significantly augment research investment in the steel industry, adjust the industry's energy structure, innovate process flows, and envisage an evidence based development scale.

Abstract:Green factories serve as the main implementers in building a green manufacturing system, and their construction is a crucial aspect in promoting the development of green production methods. The establishment of green factories not only helps to reduce environmental pollution and improve resource utilization efficiency, but also enhances the green image and reputation of enterprises, thereby boosting their competitiveness. This article summarized the key progress made in China's green factory construction in recent years, analyzed the major challenges facing future green factory development, and finally put forward relevant countermeasures and suggestions in areas such as strengthening the research and application of green and low carbon technologies, further improving relevant policy systems, increasing promotion and coordination, and strengthening international cooperation.

Abstract:With the increasing supervision of tailings reservoirs by the state, the tailings reservoirs of mining enterprises are facing difficulties in new construction, heightening and expansion approval, which affects the sustainable development of enterprises.So it is necessary to vigorously promote tailings emission reduction. This paper introduced the methods of implementing tailings emission reduction in iron ore mining enterprises, analyzed the potential safety risks for different emission reduction methods, and put forward safety countermeasures, so as to achieve the goals of reducing the amount of tailings in storage or no tailings discharge, and reduce the safety risk of tailings pond, effectively alleviate the problem of insufficient capacity of tailings pond.

Abstract:With the construction of green mine in China from the pilot exploration stage into the comprehensive promotion stage, in the face of the new stage, the new situation, the green mine construction planning tasks and safeguard measures deserve further in depth thinking. This paper combined the development history of China's green mine, detailed the significance of green mine construction planning and the factors affecting the construction and planning of green mine, and from these influencing factors, put forward the basic principles and general requirements of green mine planning. At the same time, according to the importance of different influencing factors, the green mine planning tasks were introduced in eight aspects as followed: mine construction, rational resource development, land conservation and utilization, ecological restoration and management, energy saving and consumption reduction, “three wastes” emission, waste resource utilization and wastewater resource utilization. In addition, in order to ensure the implementation of the green mine planning, safeguard measures were put forward in four aspects: management, funding, system and supervision. This paper provides key points and guarantees for the planning tasks of green mine in China, which will help the comprehensive construction of green mine in China.

Abstract:Aiming at the technical problems of low smelting efficiency of lead matte complex materials, incomplete separation of Cu and Pb, and low grade of crude copper, a pilot test was carried out using a self developed oxygen enriched side top blown smelting test equipment. The experimental results show that under the condition of temperature 1250℃ and oxygen concentration 60%, lead matte side top blown smelting can produce crude copper in one step. The content of Cu in crude copper reaches 94.03%, the content of Pb is 0.11%, and the removal rates of main impurities Pb, As and Sb are approximately 99%, 90% and 85%, respectively. Using this process, smelting slag+blowing copper can be completed in the same reactor, the smelting cycle is shortened to 24h, and the coal rate is 9.6%. Compared with the traditional process, the smelting efficiency is greatly improved, the operating environment is good, and the energy consumption is low. It has a good application prospect.

Abstract:Alkaline substances such as CaO in steel slag react with precipitation during storage, resulting in an increase in the pH value of surrounding soil, which leads to soil pollution. In addition to free calcium oxide, 2CaO·SiO₂ 3CaO·P₂O₅ is the main mineral phase of alkaline dissolution in steel slag. In order to reduce its formation, the steel slag was modified by adding SiO₂ and MgO in this paper, and the effectiveness of SiO₂ and MgO in inhibiting the alkaline dissolution of steel slag was investigated. The results show that the formation of free CaO and 2CaO·SiO₂ 3CaO·P₂O₅ phases in steel slag can be significantly reduced by using SiO₂ and MgO to modify steel slag. With the increase of SiO₂ and MgO addition, the content of Ca²⁺ in the dissolution solution is gradually reduced, and the maximum pH value is significantly reduced. When the addition amount of SiO₂ is 30% and the addition amount of MgO is 10%, the maximum pH value of the leaching solution is reduced to 10.1, which is very close to the maximum pH value (10.03) of the CaCO₃ leaching solution. It can be considered that the modified steel slag will not cause serious alkali dissolution problems in practical applications.

Abstract:Copper electrolytic refining is an important technical link in the copper industry chain that determines the quality and performance of copper products. The principle, research progress and existing problems of cathode copper electrolytic refining technology such as traditional electrolytic refining method, permanent stainless steel cathode method, periodic reverse current method, pulsed current method, parallel flow electrolytic refining method, external field enhanced electrolytic refining method and high purity copper electrolytic refining technology prepared by single step or multiple step electrolytic refining were summarized and analyzed . The copper electrolytic refining technology was prospected, and it was pointed out that the cathode copper electrolytic technology would develop in the direction of strong adaptability of raw materials, high metal recovery rate, low production cost and energy consumption, and environmental friendliness,and the electrolytic refining technology of high purity copper is developing towards the direction of process simplification, energy saving and emission reduction, large scale production and high purification of products.

Abstract:Using zinc leaching residue as raw material, experimental research was conducted by RHF direct reduction and magnetic separation process. Press zinc leaching residue into pellets with reducing agents and binders in a certain proportion for reduction experiments. The results showed that under the conditions of carbon oxygen ratio of 1.2, reduction temperature of 1250℃, and reduction time of 35min, the zinc leaching residue was directly reduced to obtain metallized pellets. The volatilization rate of zinc exceeded 99%, the volatilization rate of lead exceeded 95%, the volatilization rate of indium was more than 79%, and the metallization rate of iron was more than 85%. The metallized pellets were subjected to magnetic separation under the conditions of first grinding for 10min, magnetic field strength of 0.18T, second grinding for 15min, and magnetic field strength of 0.12T, resulting in iron concentrate powder with an iron grade of 87.12%. The iron recovery rate was 83.04%, and the experimental indicators were good. The comprehensive recovery and utilization of valuable elements such as lead, zinc, indium, and iron in zinc leaching was realized.

Abstract:The purification and cobalt removal process of zinc hydrometallurgy reagent uses organic reagent sodium formate to remove cobalt. There are some problems in the production, such as poor cobalt removal effect, enrichment of organic decomposition products in zinc hydrometallurgy system, difficulty in zinc electrowinning burning plate and melting and casting materials. In this paper, the above problems were analyzed, and the measures of optimizing cobalt removal process, new liquid quality, germanium removal process parameters, and removing nano zinc sulfide were proposed. Through the implementation of optimization measures, the use of organic reagents is significantly reduced, the enrichment of organic matter in the system is also significantly reduced, the impurities such as cobalt and cadmium in the purified new liquid are further removed, and the system stability is better, which fundamentally solves the harm of organic matter decomposed by organic reagents to zinc electrowinning process.

Abstract:The original cell control technology of electrolytic aluminum enterprises is based on a single resistance signal to judge whether the operation of the electrolytic cell is stable, which cannot achieve the visual effect, and lacks the functions of collaborative control, optimization decision making and abnormal situation diagnosis. With the gradual enlargement of the electrolytic cell type, there are more and more problems that cannot be predicted in advance only by manual experience. Taking 400kA series electrolytic aluminum of electrolytic aluminum enterprise as the research object, a new digital slot control computer was developed. The composition and function of the new digital control system were introduced, and the system was applied in practice. The research shows that with the cooperation of the new intelligent optimization control system, the prevention ability and production stability of the 400kA series electrolytic cell emergencies are greatly improved, the power consumption and the cost of production raw materials are significantly reduced, and the labor efficiency and the stability of the electrolytic cell operation are significantly improved.

Abstract:Aiming at the problem of resource utilization of sodium sulfate in lead zinc smelting wastewater, the experiment of electrolytic preparation of acid (H₂SO₄) and alkali (NaOH) was carried out by using a self made electrolytic cell with diaphragm and two chambers. The effects of sodium sulfate concentration, current density, plate spacing and electrolysis time on the yield of acid and alkali were investigated, so as to determine the optimal electrolysis scheme. The experimental results show that the optimum experimental conditions are as follows: sodium sulfate concentration is 25%, current density is 85.0mA/cm₂, the volume of external circulating electrolyte is 70mL, the circulation rate is 50mL/min, the plate spacing is 5mm, and the electrolysis time is 3h. Under the above optimal conditions, the yields of acid and alkali can reach about 10%. While realizing environmental protection, it can also realize the recycling of high salt wastewater and improve the clean and sustainable development ability of lead zinc smelting.

Abstract:In the process of copper electrolytic refining, electrolyte temperature, electrolyte circulation speed, the amount of additives and current density are the key process parameters that determine the quality of copper. However, the control of these parameters is judged according to artificial experience, which lacks certain rationality. This paper proposed to use the artificial gorilla troops optimizer to optimize the control parameters in the copper electrolytic refining process in order to obtain the optimal parameter ratio. Experiments show that the quality of cathode copper is significantly improved and the power consumption is reduced by 6.173% by using the optimal parameters obtained by the artificial gorilla troops optimizer. The copper electrolysis process optimization model based on the artificial gorilla troops optimizer can accurately regulate the copper electrolysis process factors, and overcome the subjectivity of human experience control and the disadvantage of not being able to guarantee the optimal.

Abstract:The composition of biomass and coal is very complex, and these components jointly determine the sintering or slagging characteristics of ashes in the thermal conversion process of mixed biomass and coal, which has an important impact on the application and promotion of thermal conversion technology of the mixed biomass and coal. In this paper, typical biomass straw and bituminous coal were used as raw materials, and the influence of different mixing ratios, burning temperature and time on the sintering characteristics of the combustion ash of mixed biomass and coal was deeply studied. The results indicated that the higher the mixing ratio of corn stalk, the more obvious the deashing effect was. The ash content of rice straw mixed with bituminous coal was higher than that of corn straw mixed with bituminous coal, which was mainly caused by the different chemical compositions and structure of the two kinds of straw biomass. Under the same sintering temperature and biomass mixing ratio, the effect of sintering time on ash content was not obvious. With the increase of burning temperature, the lower the ash content of the mixed ash samples obtained from the thermal conversion of mixed corn straw and bituminous coal, the more obvious the ash removal effect. When the mixing proportion of corn straw increased from 25% to 75%, the ash morphology varied from irregular shape or honeycomb structure to obvious melting and bonding phenomenon. The slagging tendency of the mixed combustion ash was enhanced by the increase of the ignition temperature, while the effect of the burning time on the microstructure of the ash sample was small.

Abstract:The in situ leaching process of magnesium salt system is a new type of green mining process for ionic rare earth ore. Compared with the traditional ammonium sulfate leaching process, the new process avoids the problem of ammonia nitrogen pollution. However, the characteristic factors such as magnesium and TDS produced by the magnesium salt leaching mining process are also the key indicators of environmental protection control. Clarifying its environmental control requirements is the premise of environmental protection management and environmental impact assessment of the new process. In this paper, the environmental standards of magnesium at home and abroad were introduced. Through literature research, standard analogy, limit inversion and other methods, the characteristics of magnesium salt leaching process, the quality of regional water environment, the degree of harm of characteristic factors to the environment and human body were integrated. The relatively reasonable characteristic factor control requirements of magnesium salt leaching process were preliminarily put forward. It is suggested that the standard limit of magnesium in groundwater should refer to the standard of Poland (100mg/L), and the standard limit of magnesium in surface water should be 100mg/L; the emission control limit of magnesium in wastewater is suggested to be 500mg/L or not to set the emission limit, and the emission effect of magnesium is indirectly controlled through sulfate emission control.

Abstract:Urban wastewater treatment is an energy intensive and high energy consuming industry, its carbon emissions accounting for 1%~2% of the total emissions of society. In the context of the “Dual Carbon” target, reducing pollution and carbon emission, low carbon , green and sustainable development has become the main development direction of future wastewater treatment plant. This article analyzed the composition and source of greenhouse gases in wastewater and sludge treatment process, and summarized the current technologies and application cases for carbon reduction in wastewater treatment plant at home and abroad from the perspectives of process operation optimization, resource and energy recovery, clean energy utilization, and low carbon new process development. The article also proposed prospects for achieving carbon reduction in urban wastewater treatment plants in China, in order to provide reference for the promotion and application of low carbon technologies in wastewater treatment plant.

Abstract:At present, with the public's attention to environmental protection and resource sustainability, the effective treatment of hazardous waste has become a global problem. This paper reviewed the current situation of China's hazardous waste treatment industry and the evolution of hazardous waste related policies, and proposed a circular economy model of ‘source reduction + process reuse + end treatment’ for hazardous waste treatment.Taking an industrial park in Quzhou as an example, the three major cycles of enterprise internal circulation, industrial internal circulation and park internal circulation formed by hazardous waste treatment were introduced, the process of material circulation flow of “resource product hazardous waste renewable resource” were analyzed, the feasibility of resource recycling was explored , and suggestions on hazardous waste treatment under circular economy mode from the perspectives of policy, technology, economic benefits and management supervision were put forward.

Abstract:The eccentric reducer is one of the common components in industrial pipeline systems such as electricity, petroleum, and chemicals. The internal flow of eccentric reducers is influenced by changes in pipe diameter, which can lead to issues with flow accelerated corrosion. Based on computational fluid dynamics simulation，the fluid dynamic characteristics of eccentric reducers at different aperture ratios (ε=0.4~0.7) and velocities (1~7m/s) were investigated. The Sanchez Caldera model was used to analyze the distribution of flow acceleration corrosion rates in downstream pipelines of eccentric reducers . The results show that the location prone to failure in the downstream of eccentric reducers is on the side with the small aperture. Under the condition of inlet flow rate of 3m/s, as the ratio increases, the sensitive position for flow acceleration corrosion in downstream pipelines moves upwards. Under the condition of pore size ratio of 0.6, the flow accelerated corrosion rate increases significantly with the increase of inlet flow rate,changes in flow velocity have no effect on the sensitive position for flow acceleration corrosion in downstream pipelines.