Sustainable Mining and Metallurgy

Abstract:In the background of the current goal of “carbon neutrality and carbon peak”, in view of the current high carbon emissions in the electrolytic aluminum industry, the main concerns of carbon inventory inspection in electrolytic aluminum enterprises were analyzed, including the determination of carbon accounting boundaries, accounting scope and methods, carbon emissions management, etc. In combination with the current development of electrolytic aluminum enterprises, it was proposed to increase the proportion of clean energy, use high-quality prebaked anode, upgrade and transform existing cell types, innovate energy-saving technologies，strengthen production management, establish a carbon emission management system, increase waste aluminum recycling and other coping strategies, so as to promote energy-saving, carbon reduction, and high-quality development of electrolytic aluminum.

Abstract:This paper introduced the relevant standards, classification and calculation methods of greenhouse gas emissions, focused on the calculation method of carbon emissions in the electrolytic aluminum process, and put forward the carbon reduction direction of electrolytic aluminum production. The carbon emission of the electrolysis process involves direct emission (scope I) and indirect emission (scope II), namely, the PFCs emission generated by the net anode consumption and anode effect, as well as the emission of purchased power. The net anode consumption per ton of aluminum emission calculated according to the recommended value is 1.503tCO₂e, and the PFCs per ton of aluminum emission generated by the anode effect is 0.252tCO₂e. The net consumption of aluminum per ton of anode calculated according to the measured data is basically below 1.5tCO₂e, while the PFCs emission calculated from the measured data fluctuates greatly from 0.32 to 2.38tCO₂e/t, both of which are greater than 0.252tCO₂e. The electricity consumed in electrolytic aluminum production is the largest indirect emission in the aluminum production process. Due to different power supply emission factors, its emission is 0~16.2tCO₂e/t. Standardized and unified calculation and measurement methods are the prerequisite for obtaining accurate emission data. Relevant national departments and large aluminum industry groups should actively organize the measurement of direct emissions of electrolytic aluminum industry, especially PFCs emissions. Reducing anode consumption and anode effect is the key to reduce the direct emission of electrolytic aluminum process, saving electricity is the key to reduce indirect emission, saving the consumption of raw and auxiliary materials such as aluminum oxide is an important means, and adopting green electricity with low emission factor is also an important direction of carbon reduction.

Abstract:With the rapid increase in the penetration rate of new energy vehicles, the power battery recycling industry has entered the fast lane of development. This paper summarized the policy system of power battery recycling in China, and analyzed the development status of power battery recycling industry. At present, there are some problems in the recycling of power battery for new energy vehicles, such as poor recycling channels, insufficient technical reserves and perfect standards and regulations. In view of the above problems, the countermeasures and suggestions for promoting the high-quality development of the power battery recycling industry were proposed. First, improve the design of power batteries to achieve standardization, easy disassembly and easy recycling of power batteries ; second, innovate the recycling business model, standardize recycling channels and improve recycling networks ; the third is to carry out technical development and promote safe, environmentally friendly and efficient recycling technology ; fourth, improve policy measures and regulatory mechanisms.

Abstract:This article analyzed the current problems in the development of new energy in China, and introduced the current models of integrating new energy into the electricity market at home and abroad, and provided suggestions for China to accelerate the construction of a new era electricity market system. At present, there are problems in the development of new energy in China, such as insufficient consumption capacity of the power grid, reduced government subsidies, low technological level, and unclear participation models in the electricity market. At present, in order to accelerate the participation of new energy in the electricity market and build a complete new era electricity market system ，it should continuously improve the supporting policies for new energy in the electricity market, enhance the adaptability of the electricity market to renewable energy, enhance the regulatory capacity of the electricity system, optimize quota design of the system, and promote the coordinated development of the green certificate market and the carbon market.

Abstract:In order to achieve efficient dust removal from copper smelting high-temperature flue gas, this paper analyzed the current research status of dust removal technology in the field of high-temperature flue gas, built a pilot plant for high-temperature electrostatic precipitator based on the operating conditions of copper smelting flue gas, analyzed the morphology, particle size, and other characteristics of copper smelting dust, studied the impact of different flue gas flow rates and voltages on dust removal efficiency, and obtained the optimal setting method for key parameters of electrostatic precipitator. The results show that when the flue gas flow rate of the high-temperature electrostatic precipitator is 0.48m/s, the flue gas particles will not cause serious dust accumulation in the high-temperature electrostatic precipitator, nor will cause a large number of particles to escape, and the dust removal efficiency is the best; The higher the electric field voltage, the lower the dust concentration at the outlet, and the higher the dust removal efficiency. It is necessary to find the voltage value with the lowest energy consumption on the premise of meeting the dust removal efficiency. An engineering application test of high temperature electrostatic precipitator technology was conducted in a copper smelter in Fujian. The test results showed that the dust concentration in the flue gas at the outlet of the high temperature electrostatic precipitator decreased from 2.19g/m³ to 62mg/m³, and the dust removal efficiency was greater than 97.1%.

Abstract:In this paper, a vacuum carbothermal pre reduction hydrochloric acid leaching experiment was conducted using titanium concentrate as raw material, and the effects of vacuum carbothermal reduction temperature on metal weight loss, metallization rate, furnace pressure, and Fe, Si, and Mg volatilization were analyzed. The effects of different solid liquid ratios, hydrochloric acid concentration, and acid leaching time on the grade of synthetic rutile in hydrochloric acid leaching were studied, Thereby obtaining the optimal reaction conditions for the method of vacuum carbothermal pre reduction and hydrochloric acid leaching of titanium concentrate to prepare artificial rutile. The experimental results show that with the increase of reduction temperature, the metallization rate and weight loss rate gradually increase, and the volatilization rate of Fe, Si and Mg also gradually increase. The reduction temperature of 1500℃ is appropriate. The optimal conditions for hydrochloric acid leaching are hydrochloric acid concentration of 15%, solid liquid ratio of 1∶5, acid leaching time of 20minutes, and stirring speed of 120r/min. Vacuum carbothermal pre reduction can reduce the impurity content of titanium concentrate, reduce the impurity iron to form fine spherical particles, greatly increase its specific surface area, thereby reducing the reaction temperature, pressure, and reaction time of acid hydrolysis，so as under normal pressure conditions, acid leaching can be used to quickly reduce to obtain high-quality artificial rutile.

Abstract:The raw materials for nonferrous smelting are mostly metal sulfides, and a large amount of sulfur dioxide flue gas is generated during the pyrometallurgical process. Generally, the smelting flue gas is used for acid production. In the purification process of acid production, dilute acid captures a large amount of dust and impurities in the flue gas, which are settled by an efficient sedimentation tank. The supernatant returns to the system, and the underflow is sent to a filter press for filtration. The filter cake containing valuable metals is returned to the smelting system for recovery. The amount of smelting flue gas and impurity content fluctuate greatly. To meet the impurity removal efficiency under all operating conditions, it is necessary to increase the effective settling area of the settling tank or increase the particle settling speed, which increases the costs. This article conducted a feasibility analysis of using flocculant PAM to improve the sedimentation rate of impurities in purified dilute acid, and explored the impact of different PAM dosage on the sedimentation of impurities in purified dilute acid, so as to provide reference data for the selection of sedimentation tank,improve sedimentation efficiency and reduce equipment specifications. The experimental results show that the addition of PAM has a positive effect on particle deposition in refining dilute acid from smelting flue gas, and has no significant impact on the composition of refining dilute acid from smelting flue gas, and does not affect the flue gas purification effect.

Abstract:The accelerated life of RuO₂IrO₂/Ti and IrO₂Ta₂O₅/Ti was studied and compared, and the effects of fluorine ion on the accelerated life of the two above-mentioned electrodes were studied. Experimental results show that the accelerated life of IrO₂Ta₂O₅/Ti electrode is about 40 times that of RuO₂IrO₂/Ti electrode. The presence of 1mg/L fluorine ions can reduce the accelerated electrode life of RuO₂IrO₂/Ti electrode by 22% and the accelerated electrode life of IrO₂Ta₂O₅/Ti electrode by 82%. The causes of electrode failure were analyzed by scanning electron microscopy and energy spectroscopy. The analysis results show that the dissolution of the active ingredient in the electrode catalytic layer, the cracking and shedding of the electrode catalytic layer caused exposure and oxidation of the substrate could be the direct causes of the electrode failure.

Abstract:In this paper, the new alumina extracted from fly ash was used as the electrolytic raw material. According to the performance characteristics of the new alumina, the simulation calculation was carried out based on the 200kA aluminum electrolytic cell. The electrolyte flow field and the distribution of the new alumina concentration in the electrolytic cell were studied. The mass transfer factors affecting the dissolution, diffusion and convection of the new alumina were analyzed, and the dissolution transport performance in the new alumina electrolysis process was mastered. The results show that the new alumina dissolves quickly and uniformly in the electrolyte, the electrolyte flow field is stable, and the alumina at the aluminum end and the corner of the flue end dissolves fastest. In actual production, by reasonably configuring the feeder and the feeding point to control the dispersion and transport of alumina concentration, the uniform distribution of alumina concentration and the stability of electrolyte flow field can be maintained, which is beneficial to reduce the anode effect and improve the current efficiency.

Abstract:This article compared the performance of magnesium batteries with lithium batteries, zinc manganese batteries, and summarized the structures, advantages and disadvantages, current applications, and existing problems of magnesium manganese dry batteries, magnesium secondary batteries, magnesium seawater batteries, and magnesium air batteries. It was also pointed out that the oxidizability of magnesium, the negative difference effect of magnesium ions, the low creep resistance of magnesium, and the susceptibility to self corrosion reactions can affect the research of magnesium batteries. Solving these problems is the main research direction and performance of various magnesium batteries in the future.

Abstract:This paper discussed the reaction mechanism in the preparation of nickel cobalt manganese ternary precursor, and the effects of solid content, sodium hydroxide concentration, stirring speed, ammonia concentration, reaction temperature, and pH on the specific surface area, tap density and particle size distribution width of the ternary precursor Ni₆₅Co₇Mn₂₈ (OH)₂ in the preparation of medium high nickel precursor Ni₆₅Co₇Mn₂₈(OH)₂. The experimental results show that with the increase of solid content, the tamping density of the ternary precursor increases gradually, the specific surface area decreases, and the particle size distribution width has no obvious change; With the increase of stirring speed, the tamping density of the ternary precursor gradually increases, the specific surface area becomes smaller, and the particle size distribution width becomes wider; With the increase of reaction temperature, the tamping density of ternary precursor gradually decreases, the specific surface area increases, and the particle size distribution width narrows; With the increase of ammonia concentration, the tamping density of ternary precursor gradually increases, the specific surface area becomes smaller, and the particle size distribution width has no obvious change; With the increase of sodium hydroxide concentration, the tamping density of the ternary precursor gradually increases, the specific surface area becomes smaller, and the particle size distribution width becomes wider; When the pH value increases, the specific surface area increases significantly, but the tap density and particle size distribution width do not change significantly. The quality of the ternary precursor prepared under the conditions of solid content 84g/L, sodium hydroxide concentration 4mol/L, stirring speed 135r/min, ammonia concentration 5.5g/L, reaction temperature 65℃ is relatively ideal.

Abstract:At present, there are two common types of ternary precursor wastewater stripping and deamination processes. One is to use a distillation tower equipped with a reboiler and condenser, and inject saturated steam into the reboiler as a heat source. The other is to use a distillation tower equipped with only a condenser but no reboiler, and directly inject saturated steam from the bottom of the distillation tower as a heat source. These two processes have the problem of high energy consumption or a large amount of wastewater treatment discharged downstream. Therefore, this article proposed an optimized process route, which is to use a distillation tower with a reboiler and no condenser for ammonia distillation operation, fully utilizing the steam at the top of the distillation tower and the outlet liquid from the tower kettle for reasonable heat exchange with raw material wastewater, and the raw material liquid after heat exchange enters from the top of the distillation tower. And Aspen Plus process simulation software was used to simulate and compare the optimized process with the two traditional processes mentioned above. When modeling, ELECNRTL thermodynamic model and equivalent transformation were used to accelerate convergence. The simulation results indicate that the optimized process combines the advantages of two traditional processes, not only avoiding direct contact between steam heat sources and materials, but also reducing the amount of waste water in the ammonia tower kettle; Moreover, it fully utilizes the residual heat of the steam at the top of the ammonia distillation tower and the effluent from the tower kettle, thereby reducing the energy consumption of the entire system.

Abstract:In order to solve the problems of long process flow and high consumption of auxiliary materials in the recovery of valuable metals from ternary high magnetic materials, a low cost purification and recovery process for high magnetic materials was proposed. The effect of stirring speed and magnetic field intensity of permanent magnet rods on the adsorption effect of metal foreign particles in the leaching solution of high magnetic materials were studied. The effects of different additives such as polymerized iron sulfate and ferrous sulfate on the iron removal effect were also studied, as well as the use of manganese powder. The effect of removing iron from precursor accident materials as a neutralizer on the introduction of impurities. The experimental results show that the use of permanent magnetic rods to adsorb metal foreign particles in the leaching solution of high magnetic materials has a good effect, with a metal particle removal rate of 91%, and the stirring speed has no significant impact on it; The greater the magnetic field intensity of the permanent magnet rod, the stronger the adsorption capacity. The introduction of polymeric iron sulfate and ferrous sulfate during neutralization and hydrolysis for iron removal has poor iron removal efficiency, and it is difficult to filter after adding polymeric iron sulfate; Adding precursor accident materials has the best iron removal effect, with an iron removal rate of over 90%, and no other impurities will be introduced to affect the solution quality.

Abstract:Flame temperature, as one of the most important parameters characterizing the combustion state in the furnace of a garbage incinerator, has become the main method of combustion diagnosis by measuring flame temperature. Based on the flame characteristics of urban household waste and CCD image technology, combining image processing technology, image calibration, and radiation temperature measurement principles,a method and equipment for measuring the temperature of waste incineration furnace flames based on visible light radiation characteristics was proposed, and was applied to biomass flame experiments to detect its temperature measurement accuracy. The results show that the measurement accuracy of the image temperature measurement method is high, and the error with the thermocouple measurement value is less than 5%. This method can obtain the two-dimensional temperature distribution of the incinerator flame, which has the advantages of fast response, strong adaptability, and wide application range.

Abstract:Taking zinc smelting decommissioned plots as an example, this paper analyzed the characteristic pollutants in the zinc smelting industry, and put forward suggestions on soil environmental management of construction land under the background of “carbon peak” and “carbon neutrality” according to the current national soil management regulations. The characteristic pollutants of the zinc smelting industry include arsenic, cadmium, lead, copper, hexavalent chromium, mercury, nickel, zinc, antimony, indium, silver, cobalt, PAHs, fluoride, Total petroleum hydrocarbon, polychlorinated biphenyls and other toxic and harmful substances. The areas of sewage treatment, raw material storage, production, and solid waste storage in the original site are potential pollution areas that require attention. In the background of “carbon peak” and “carbon neutrality” , by improving the investigation work of retired land plots, constructing a risk control system, and strengthening green and low-carbon remediation technologies, strengthening the management of soil environmental risks , the goals of soil pollution risk control and improving environmental quality can be achieved.

Abstract:The long-term mining has formed a large number of high and steep exposed slopes, resulting in the destruction of mountain ecological environment, air pollution, water and soil loss, etc. the task of mine ecological governance is imminent. High-order aggregate spraying technology is widely used in the field of mine ecological restoration. Taking the abandoned mine in the northern mountainous area of Fangshan District as an example, this paper used the high-order pellet spraying technology to carry out the ecological restoration of mine slope, mainly introduced the principle, technical advantages, applicable conditions, construction process and technical points of high-order pellet spraying technology, so as to provide reference for the ecological restoration of similar mines.