Sustainable Mining and Metallurgy

Abstract:The oxygen-enriched top blown submerged smelting process is a copper smelting technology introduced in a specific period and realized digestion innovation and wide application in China. It has made an important contribution to the leap of China 's copper smelting industry from traditional smelting process to modern intensive smelting process. In recent years, with the rapid development of continuous copper smelting technology and short process technology, matte smelting has made continuous breakthroughs in the direction of high oxygen concentration, high matte grade, high temperature and high processing capacity. Under the background of high-quality development requirements and rapid technological progress, domestic production enterprises have continuously carried out a series of exploration and research on green energy saving and consumption reduction of copper smelting system in combination with their own reality, and achieved a series of results. This paper focused on the process innovation and process reengineering of the technological upgrading and transformation of the copper concentrate oxygen-enriched top blown submerged smelting plant in the new era, and put forward the general idea and development direction, including the addition of side blown lances to the main equipment air supply device, and the corresponding transformation of the structure of the metallurgical furnace body and other supporting facilities, the abolition of the raw material granulation system and the settling electric furnace, the realization of high-grade copper matte smelting and continuous copper smelting. The upgrading and transformation of the melting plant technology and equipment provides technical reserves, guidance and reference, and promotes the industry to move towards low-carbon, green and environmental protection.

Abstract:In order to carry out the comparison and optimization of physical energy storage methods in underground space of abandoned mines, on the basis of summarizing and analyzing the principles and development status of pumped storage, gravity energy storage and compressed air energy storage in abandoned mines, the analytic hierarchy process was used to select 6 first-level indicators, 19 second-level indicators and 3 energy storage schemes, and the evaluation index system of physical energy storage methods in underground space of abandoned mines was established. Taking Baijiazhuang Coal Mine in Shanxi Province as an example, based on the expert scoring method, the weights of each index and scheme layer are analyzed, and the main control factors and influence degree of the primary and secondary indicators in the evaluation system are obtained. Based on this analysis, the advantages and disadvantages of three physical energy storage methods are compared. The results show that among the first-level indicators, the weight of safety and security is the highest, followed by environmental impact, an then resource conditions, economic benefits, energy consumption level, and finally technical solutions. Among the secondary indicators, the three indicators with the highest weight are technical support, natural ecology and capital investment; among the three schemes, gravity energy storage has the most advantages, followed by pumped storage, and finally compressed air energy storage. The research results can provide reference for the selection of physical energy storage methods in underground space of abandoned mines.

Abstract:The rapid development of economy has put forward higher requirements for the development and utilization of mineral resources in China. Promoting the development of green mines is the only way to balance resources and environment. This paper pointed out the problems existing in the construction of green mines in China, including the unscientific evaluation mechanism, the inability of evaluation standards to accurately guide the construction of green mines, the lack of endogenous power of enterprises, and the inability of economic benefits of enterprises to support the construction of green mines, and proposed solutions from the three dimensions of relevant government departments, third-party evaluation institutions and enterprises. The government should do a good job in top-level design, improve the policy and standard support system, train a group of third-party institutions and evaluation experts with evaluation ability, guide enterprises to establish a green mine management system, upgrade and transform the production system in the process of green mine construction, reduce the operation cost of enterprises, hedge the capital investment in the construction of green mines, and focus on establishing the balance of resources and environment such as mineral resources balance, energy balance, carbon balance, water balance, solid waste balance and land balance, so as to promote the construction of green mines.

Abstract:The adsorption performance of manganese based adsorbents for low-grade Li+ in Sichuan Zigong underground brine was studied by static and dynamic adsorption and desorption experiments. The results show that the adsorption capacity of the adsorbent for low-graded Li+ in brine increases with the increase of pH value, and the dissolution loss of manganese is the smallest when the pH value is about 7. The temperature has little effect on the adsorption effect, and the adsorbent has a good adsorption effect at room temperature. With the prolongation of time, the adsorption capacity increased, and the adsorption reached equilibrium at 2h, and the adsorption capacity reached 7.85mg/g; the adsorption process conforms to the pseudo-second-order kinetic model and the Langmuir isothermal adsorption model of monolayer adsorption, and has good adsorption selectivity and stability for Li+. After desorption with 0.08mol/L sulfuric acid for 2h, the desorption rate of the adsorbent reached 96%. In the dynamic adsorption process, the adsorption efficiency of the adsorbents at different flow rates were higher before effluent volume reached 40BV, and the adsorbents reached the adsorption equilibrium at 70BV. In the dynamic desorption process, the concentration of Li+ in the desorption solution increased first and then decreased, and 3~4BV desorption solution could be collected as a qualified solution for subsequent concentration production.

Abstract:The phase evolution of silver in lead-silver slag during melting-fuming process was studied. The thermodynamic mechanism of silver phase volatilization in lead-silver slag was analyzed by thermodynamic calculation and analysis. Based on the thermodynamic theory calculation, the influence of single factor (reaction temperature, carbon proportion and holding time ) on silver recovery rate was studied, and the optimum process parameters were obtained. Then, by observing the microstructure morphology, combined with theoretical calculation and experimental results, the evolution law of silver phase in lead-silver slag during melting-fuming process was clarified. The thermodynamic analysis results show that Ag₂O in the lead-silver slag is preferentially volatilized into the soot. AgCl in the slag does not undergo oxidation reaction, reduction reaction and decomposition reaction, and will volatilize into the dust. Ag₂S in lead-silver slag does not volatilize or undergo reduction reaction, and will be oxidized to Ag₂SO₄. At low temperature, Ag₂SO₄ will be reduced to elemental silver, and elemental silver will form an alloy with lead and zinc, which will be carried into the soot. At high temperatures, the vapor pressure of Ag₂SO₄ increases sharply and Ag₂SO₄ volatilizes into the dust. The experimental results of silver slag show that the phases in the dust are Ag₂O, AgCl, Ag₂SO₄ and elemental silver, which is consistent with the results of thermodynamic analysis. The single factor experiment showed that the optimum process parameters for silver recovery from lead-silver slag were reaction temperature of 1300℃, carbon proportion of 16.30%, holding time of 150min. Under these conditions, the silver recovery rate was 80.26%.

Abstract:The recycling process of spent power batteries has strong negative externalities. In order to promote the establishment of compensation mechanism for spent power batteries, the negative externalities of spent power batteries were analyzed in detail, which were divided into three categories: waste of resources, destruction of ecological environment and damage to health and safety. By using the user cost model, the damage environment cost measurement model and the human resource method model, the negative externalities in the recycling process were quantified, the resource depletion cost quantification model. The ecological environment damage quantification model and the health and safety damage quantification model were built. Based on the above models, the negative externalities compensation mechanism of spent power batteries was studied, including the subject and object，compensation standards and compensation methods of resource compensation, ecological environment compensation, health and safety compensation, etc. According to the manifestations of negative externalities, it is considered that the setting of the compensation mechanism needs to consider indicators such as the amount of waste power battery recycling and metal recovery rate, evaluate the negative externalities caused by the ecological environment in detail, and quantify the possible damage to human health.

Abstract:The application of new materials is of great significance to the energy saving, carbon reduction and quality improvement of electrolytic aluminum production. This paper focused on the application of new materials such as metal materials, coating materials, ceramic materials, carbon materials and refractory materials in the energy saving and carbon reduction technology of large aluminum reduction cells in recent years. The application of metal materials in the electrolytic cell mainly includes low resistance anode steel claw, high conductivity cathode steel rod, super wear-resistant shell hammer, etc. The application of coating materials mainly includes heat reflection insulation coating of the tank cover plate, anode and steel claw oxidation resistance coating, etc. The application of ceramic materials mainly includes ceramic-based cathodes and ceramic-based inert anodes. Carbon materials are mainly used in graphite or graphitized cathode carbon blocks; in terms of refractory materials, there are mainly new anti-seepage and thermal insulation materials, new silicon carbide/carbon composites and so on. While continuously optimizing the production and operation process, domestic electrolytic aluminum production enterprises pay more and more attention to the application of new materials in energy-saving and efficiency-increasing technology. At the same time, it is pointed out that the application of new materials still needs systematic research.

Abstract:The sulfur dioxide converter using traditional single stage axial gas distribution devices is prone to problems such as uneven flue gas distribution, large temperature difference at the temperature measurement points of the catalyst layer, and substandard sulfur oxidation conversion rate. In order to find out the fundamentally cause of the problem and solve the problem, the gas distribution effect of single-stage axial gas distribution device was analyzed with the help of computational fluid dynamics simulation software. A new type of axial gas distribution device was proposed based on the idea of multi-stage gas distribution, and the dimensions of key factors affecting the gas distribution effect and pressure drop of the new axial gas distribution device were optimized and studied. The traditional single stage axial gas distribution device has a single structure. Affected by the throttling factor of the sieve orifice plate, there are significant velocity and flow differences after the airflow through the sieve orifice and the airflow that is blocked by the sieve orifice plate reaches the surface of the catalyst layer, resulting in uneven gas distribution of the gas distribution device. Through multi-stage gas distribution, the new axial gas distribution device effectively overcomes the gas distribution defects of the single stage sieve plate, and its performance has been tested in practical engineering applications. After the technical transformation, the sulfur dioxide conversion rate, catalyst bed temperature difference, sulfuric acid production and other indicators have been significantly improved.

Abstract:There is a small amount of cadmium in the materials in the lead smelting system, and most of the cadmium enters the soot after smelting in the smelting furnace, and the soot contains about 10%~20% cadmium. In this study, cadmium was leached by acid leaching, and the leach residue was returned to lead smelting system. Sponge cadmium was prepared by adding zinc powder to cadmium-rich solution, and zinc was recovered by electrodeposition system after replacement. The effects of sulfuric acid acidity, reaction temperature, reaction time, liquid-solid ratio and stirring speed on the leaching rate of cadmium and zinc were investigated. The results show that under the condition of sulfuric acid acidity of 50g/L, the liquid-solid ratio of 5∶1, the temperature of 50℃, reaction time of 2.0h, the stirring speed of 70r/min, the cadmium leaching rate of cadmium-containing soot is 95.24%, cadmium leaching effect is good. Using the above optimum test conditions, the production practice shows that the leaching rate of cadmium and zinc in cadmium ash are stable above 95%, and the purity of cadmium in sponge is above 95%.

Abstract:In the production of alumina by the Bayer process, after each cycle of the mother liquor, the caustic alkali is lost and the invalid alkali is increased, resulting in a decrease in the efficiency of evaporation and salt discharge, and an increase in energy consumption and alkali consumption. In order to recover the lost caustic alkali and reduce the invalid alkali, this paper took the domestic diaspore alumina production system with high carbon content as an example, and designed three process conditions: evaporation salt discharge causticization, evaporation salt discharge causticization+red mud dealkalization and recovery, evaporation salt discharge causticization+red mud dealkalization and recovery+first washing solution causticization. The flow direction of Na₂O in the production process was studied, and the loss, conversion and recovery of effective alkali in the system were calculated. From the technical and economic aspects, the characteristics of red mud alkali removal and causticization of primary lotion were analyzed and compared. The dealkalization of red mud can remove and recover the Na₂O in the sodium silicon slag of red mud and return it to the production system. The causticization of the first lotion can convert Na₂CO³ in the mother liquor into NaOH and reduce the carbon-alkali content of the system. Dealkalization of red mud and causticization of primary lotion can reduce the alkali consumption of alumina production and save production costs. Taking an alumina plant with a capacity of 100t/a as an example, the alkali consumption of production can be reduced by 66~70_kg/t by using red mud alkali removal and causticization of primary washing liquid, and the production cost of alumina can be saved by 85~134yuan/t.

Abstract:The flue gas treatment system of a lead smelter has certain instability, and the emission of SO₂ and NO_x can’t meet the environmental protection requirements. This paper introduced the basic situation of organic amine desulfurization technology in the original flue gas treatment process, discussed the problems existing in the current process, and put forward improvement measures, including adjusting the direction of desulfurization flue gas and amine liquid, increasing ozone denitrification system, and ensuring that environmental protection facilities are compatible with production capacity. The flue gas treatment process after the transformation was optimized from the aspects of amine liquid selection, flue gas purification, amine liquid desalination, flue gas temperature and so on. After the transformation and optimization of the flue gas treatment system, the emissions of SO₂ and NO_x are up to standard.

Abstract:Heavy metal chromium not only pollutes groundwater after entering the soil, but also accumulates in plants and endangers human health. Leaching technology has the advantages of simple operation, cost saving and remarkable effect. It is a commonly used treatment method for chromium contaminated soil. This paper summarized the current research on the leaching of chromium-contaminated soil, introduced the leaching principle, application and existing problems of various eluents, and analyzed the factors affecting the leaching effect, such as soil properties, eluent properties, eluent pH value, leaching time, liquid-solid ratio and enhancement methods. It was pointed out that the leaching of chromium-contaminated soil has problems such as low efficiency of chromium leaching in cohesive soil, insufficient ecological risk assessment of soil after leaching, and insufficient treatment and resource utilization of leaching wastewater. In the future, it is necessary to strengthen the research on these problems.

Abstract:Based on the analysis of the current situation of solid waste pollution in Baiyin City, through data investigation and related data, this paper analyzed the current situation of the generation and disposal of general industrial solid waste and dangerous solid waste in Baiyin City, predicted the future solid waste production and utilization and disposal capacity gap, clarified the problems existing in the process of pollution prevention and control, and explored the development path and countermeasures of Baiyin City as a resource-exhausted city to achieve the goal of industrial solid waste pollution prevention and control planning under the background of carbon neutrality and carbon peak, in order to provide reference for the construction of zero-waste cities.

Abstract:Increasing the main steam parameters of the domestic waste incineration boiler can improve the cycle efficiency of the thermal system. Based on Rankine cycle and theoretical cycle thermal efficiency, this paper discussed the relationship between cycle thermal efficiency and main steam parameters, and discussed the determination of main steam parameters series of boilers in China, and analyzed the influence of improving steam pressure level on boiler operation management. The thermal efficiency of the steam cycle increases with the increase of the initial pressure of the steam. In the actual operation process, the influence of increasing the steam pressure level on the operation and management process such as steam-water circulation ratio, circulation system type, drum heat storage capacity, boiler pressure component material and steam-water quality should be fully considered.

Abstract:In this paper, the principle, advantages and disadvantages of the current modification technology of vegetable oil and the modification technology used in bio-based degradable lubricating oil were analyzed. The performance of bio-based degradable lubricating oil and mineral-based lubricating oil was compared, and bio-based degradable lubricating oil was used instead of mineral-based lubricating oil in aluminum electrolysis multifunctional crane. Bio-based degradable lubricating oil uses green vegetable oil as the main raw material. Compared with mineral-based lubricating oil, bio-based degradable lubricating oil has high viscosity index and flash point, low pour point, high biodegradation rate and long service life. Therefore, it has the characteristics of green environmental protection, degradability and renewability. In the application of multifunctional crane, bio-based degradable lubricating oil can meet the performance requirements of actual scenarios such as crane operation heating and large temperature difference between day and night. The lubrication performance is more significant, the friction coefficient is smaller, and the oil film coverage is higher. It can effectively prolong the service life of the crane and improve the production efficiency of aluminum electrolysis.