Sustainable Mining and Metallurgy

Abstract:The iron and steel industry has always been a major carbon emitter. Studying the “zero emission” of carbon in iron and steel production and promoting the development of hydrogen metallurgy technology is an important direction for the global iron and steel industry to achieve “carbon peak and carbon neutralization”. In this paper, the carbon emission of steel manufacturing process was analyzed, and the progress of hydrogen metallurgy technology at home and abroad was sorted out. The facts show that ‘replacing carbon with hydrogen’ is a breakthrough for the steel industry to greatly reduce carbon emissions. Based on the national policy orientation, the development of hydrogen metallurgy was prospected from the perspective of coordinated development of upstream and downstream industrial chains, and new development models of “hydrogen metallurgy+” were proposed. Based on the fact that the iron and steel industry was in the primary stage of green transformation, it was suggested that the development of hydrogen metallurgy in China should pay attention to the problems of hydrogen energy supply, iron ore resource grade, technology and standard, investment and financing.

Abstract:The existing process of smelting secondary nickel concentrate in reverberatory furnace to produce nickel anode plate has some problems, such as low heat utilization rate of fuel, large fuel consumption, short service life of furnace refractory, fragile anode plate, high residual electrode rate, high operation cost, bad operation environment, etc. The process research of producing metallized nickel anode plate by smelting secondary nickel concentrate in oxygen enriched side-blown smelting technology has been completed. The composition of metallized nickel matte is Ni+Cu≥76%, Fe＜3%, and S 16%-20%. The optimum process parameters was as followed: the reaction temperature was 1450-1600℃, the oxygen concerntration was 65%-75%, the continuous feed rate was 100kg/h, the ratio of oxygen to feed was 10-45Nm³/t, and the reductant rate was 0.5%-1%. The oxygen enriched side-blown bath smelting technology can produce metallized nickel anode plate, realizes the purpose of “melting, iron removal and sulfur reduction” of secondary nickel concentrate, produces high metallized nickel anode plate, improves the yield of nickel anode plate, greatly improves the heat utilization rate, improves the production efficiency and energy production, and reduces the production cost.

Abstract:The offline baking steel ladle intelligent management system established in this paper uses Springboot+Vue to build the system framework, and realizes database data transmission through http protocol, OPC protocol and Mybatis-Plus middleware. It intelligently captures or calculates the variable parameters required for offline steel baking ladle calculation that are difficult to collect or define, and substitutes them into the calculation method of offline baking steel ladle quantity written at the back-end of the system. So the intelligent application of the offline baking steel ladle quantity calculation model in actual production is realized. Through the intelligent operation of the system, the problems that the offline baking steel ladle quantity calculation model is only described in the article and cannot be applied in practice are solved, such as the difficulty of manual understanding of variable parameters in the calculation model, the lack of description and inaccuracy of parameter collection methods, and the difficulty of data collection. Through accurate intelligent management of offline baking steel ladle, the production operation and time cost can be reduced, unreasonable gas consumption can be reduced, the production and operation efficiency of steel plant can be improved, and the digital and intelligent level of steelmaking production can be further improved. In the process of practical application, the system has calculated that the theoretical number of offline baking steel ladle in a steel plant was 4 and the current number of offline baking steel ladle was 8. It was recommended to decrease the number of 4 offline baking steel ladles, which was recommended that the number of offline baking steel ladle in the steel plant of the example should be reduced from 8 to 4 every 72 hours. This can reduce gas consumption by approximately 3.85 million m³ throughout the year and save production costs by 5.01 million yuan. In addition，The system fills the gap in China’s lack of systematic control over offline baking of steel ladle, and has important practical value under the theme of “green” production in the national “14th Five Year Plan”.

Abstract:This paper introduced a three furnaces process of double side-blown furnaces and fuming furnace for treating lead-containing raw materials from waste battery disassembly and primary ore mixture containing various valuable metals. From the aspects of material and cost, the traditional three furnaces process of bottom blown oxidation furnace-side blown reduction furnace-fuming furnace and the three furnaces process of double side-blown furnaces-fuming furnace were compared, and the technical advantages of side blown oxidation furnace and the process control in production were explored. The side-blown furnace is more suitable for processing mixed materials. When processing lead-containing mixed materials, the side-blowing furnace will not affect the production of long furnace knots, and does not need to change the oxygen lance regularly, which improves the actual production operation rate. In industrial production, the three furnaces process of double side-blown furnaces-fuming furnace can improve the economic benefits of enterprises while recycling waste lead-acid batteries, and has high environmental protection promotion value.

Abstract:The semi-wet process was used to treat copper anode slime in a copper smelter. The content of gold and silver in the silver separation slag produced was high, and the gold and silver was lost after returning to the copper smelting system for treatment. In view of this problem, the factors affecting the content of gold and silver in the final silver slag were analyzed in the process of raw materials, slurrying, sulfating roasting, acid leaching of copper, chlorination of gold and ammonia leaching of silver in the copper anode slime treatment process. Finally, the optimization process optimization suggestions were put forward. By optimizing the process parameters and strengthening the slag washing operation, the content of silver in the silver slag was reduced from 15000g/t to 4756g/t, and the gold content was reduced from 200g/t to 38g/t. The recovery rate of gold and silver was 99%, and the economic benefit was significantly improved.

Abstract:This paper proposed an intelligent control system for single-point breaking shell and feeding, which solved the problem of sticking during the breaking shell process by adjusting the depth of the shelling hammer, and reduced the labor intensity of workers to maintain the aluminum electrolytic cell. The intelligent breaking shell and feeding control system is composed of “digital” intelligent breaking shell and feeding system+“precise feeding control” process control algorithm intelligent slot control system+distributed industrial Ethernet voice partition broadcast system. The intelligent optimization of the shelling cylinder, the setting of the lower limit position of the shelling hammer, the control and management of the breaking shell depth, the balance strategy of the feeding amount of the tank control system and the control strategy of the alumina concentration were introduced. The system was applied to a 500kA series electrolytic cell of a large aluminum electrolysis company. The results show that after the installation of the intelligent shelling and blanking system, the number of sticking is reduced by 70%, the alumina concentration of the electrolytic cell is reduced by 0.04%, the cathode voltage drop is reduced by 2mV, the average voltage is reduced by 5mV, the current efficiency is increased by 0.31%, and the DC power consumption is reduced by 58kW·h/t.The energy saving effect is remarkable.

Abstract:When the chloride ion content in the zinc hydrometallurgy system is high, it will cause certain corrosion to equipments and anode plates in the electrolysis process. At the same time, the increase of lead content in the electrolyte will lead to the precipitation of cathode zinc and lead exceeding the standard, thereby reducing the zinc grade rate and affecting the normal production and economic benefits of the enterprise. In this paper, the self-produced copper slag in the process of zinc hydrometallurgy was used to study the dechlorination of neutral leaching solution and electrolytic waste liquid respectively, and the dechlorination slag was washed with alkali to realize the comprehensive utilization of dechlorination slag resources and determine the best process control conditions. The results showed that the optimum conditions for chloride removal from neutral leaching solution were as follows : initial pH value of 1.5, temperature of 55-65℃, reaction time of 2.0h, and the amount of copper slag was 4.0 times of the theoretical amount. Under these conditions, the removal rate of chloride ions was more than 80%. When the amount of sodium hydroxide used for alkali washing of dechlorination slag is 2.0 times of the theoretical value of chloride ion content in dechlorination slag, the chlorine removal rate of alkali washing was about 85%. The optimum control parameters of chlorine removal from electrolytic waste liquid were as follows: temperature 30-40℃, reaction time 1.0h, copper slag dosage 3.0 times of the theoretical amount. Under these conditions, the removal rate of chloride ion can reach more than 80%. When the amount of sodium hydroxide used for alkali washing of dechlorination slag was 2.5 times the theoretical value of chloride ion content in dechlorination slag, the chlorine removal rate of alkali washing reached about 80%.

Abstract:Based on the sustainable development needs of new energy materials, manganese-based cathode materials have attracted the attention of the industry due to their outstanding advantages such as high voltage, safety, abundant raw material supply and low cost. At present, the industrial application of manganese-based new energy materials is in the rising stage. This paper combed the technical characteristics, industrial application prospects and upstream and downstream structures of manganese-based new energy materials. Based on the current situation of the industry, it focused on the basic situation of new manganese-based materials such as lithium manganese iron phosphate, lithium nickel manganese oxide, lithium-rich manganese-based materials, and sodium ion battery cathode materials.

Abstract:With the increase of mining depth in Baguamiao mining area, the properties of raw ore have changed, especially the gold content of each particle size of raw ore has changed, and the original concentrate treatment process has been unable to meet the on-site production. Based on the analysis and comparison of the mineral composition, natural gold output form, shape and particle size of the upper ore and the deep ore, this paper put forward the reconstruction scheme of Nelson ore machine process gravity separation. Aiming at the comprehensive recovery and utilization of Nelson concentrate, the optimal treatment method was determined by comparing the schemes of leaching, flotation and regrinding. After the traditional shaking table separation of Nielsen gold concentrate, the grade of medium tailings is high. Through the automatic control system, the multi-batch and small-batch return to the production system for regrinding and re-separation can not only maintain a high recovery rate, but also eliminate the impact of high-grade tailings on the production system. Compared with the leaching and flotation recovery methods, the existing processes and equipment are better utilized, the cost of beneficiation is reduced, and better economic benefits are achieved.

Abstract:This paper took the coke oven flue gas of a coking plant in Tangshan as the object, explored the characteristics of coke oven flue gas, compared the current coke oven flue gas dust removal, desulfurization and denitrification technology, and finally selected the appropriate desulfurization and denitrification technology. The concentration of SO₂ in the coke oven flue gas of the coking plant was as high as 2000mg/Nm³, the NO_x content was lower than that of the conventional coke oven flue gas, and the flue gas temperature was low, which was 180~192℃. According to the characteristics of flue gas, the CFB semi-dry desulfurization and dust removal + secondary combustion SCR denitrification combined process was selected as the desulfurization and denitrification technology route, and the process principles of the two technologies were introduced. After using this process, the concentration of SO₂ in the outlet flue gas is less than 35mg/Nm³, the concentration of NO_x is less than 30mg/Nm3, and the dust emission is less than 5mg/Nm³. The parameters are better than the latest local coke oven emission standards, and the ultra-clean emissions of SO₂, NO_x and dust are realized.

Abstract:Waste incineration is the largest direct carbon emission process in the harmless treatment chain of domestic waste, and it is of great significance to calculate its carbon emissions. However, currently, the study on carbon accounting methods in China is usually focused on projects, while there are few methods for calculating carbon emissions from the incineration process. Therefore, this article conducted research on carbon accounting methods for waste incineration processes both domestically and internationally, and analyzed the characteristics, accuracy, stability, and application scenarios of various accounting methods. The methods of carbon emisson accounting in waste incineration process mainly include emission factor method, blance method, actual measurement method and indirect measurement method. The results show that the emission factor method is more suitable for macro or full life cycle carbon accounting. The actual measurement method has high accuracy but high investment and operation costs. The balance method and indirect measurement algorithm have low accounting costs, and have shown high accuracy and good stability, which are suitable carbon emission accounting methods for common projects.

Abstract:Industrial parks involve many kinds of enterprises and industries. The concentration of sewage pollutants discharged is high and the treatment is difficult. It has brought a series of water pollution and various environmental problems for a long time. This paper summarized the characteristics and sewage treatment modes of typical industrial park wastewater, analyzed the research hotspots of the main advanced treatment technologies of industrial wastewater, and deeply analyzed the problems existing in the development of industrial parks, and expounded the current situation of sewage treatment in industrial parks from multiple dimensions. Finally, from the perspective of park construction planning, sewage treatment mode and technology selection, management practice, etc., feasible suggestions were put forward for industrial parks to effectively treat sewage and achieve energy conservation and carbon reduction.

Abstract:Taking a wet desulfurization wastewater treatment project of ultra-high temperature subcritical gas power generation as an example, the desulfurization wastewater of this project was treated by triple-box chemical precipitation method, and the process conditions of pH value, coagulant aid and sludge production were optimized. The results showed that with the increase of lime milk dosage, the pH value of neutralization tank wastewater increased gradually, and the conductivity of wastewater decreased gradually. When the dosage of lime milk solution was 24g/L, the concentration of Mg²⁺ and SO^2-₄ ions in the desulfurization wastewater decreased significantly, while the concentration of Ca²⁺ ions increased, which exceeded the national standard requirements. In order to remove Ca²⁺ ions, sodium carbonate solution was added, and the optimum dosage of sodium carbonate was 6.9g/L; the flocculation effect of non-ionic coagulant aid in the treatment of desulfurization wastewater is better than that of anionic and cationic coagulant aid. The sludge yield increased with the increase of pH value of desulfurization wastewater. When the pH value was 11, the sludge yield reached the maximum. The main components of the sludge were CaSO₄·2H₂O, Mg(OH)₂ and Ca(OH)₂.

Abstract:Municipal solid waste has a wide range of sources, and the physical composition and chemical composition of various solid waste are quite different. Accurate investigation and analysis of waste sources provide a basis for the planning, collection, transportation and comprehensive utilization of solid waste treatment. Solid recovered fuel can truly realize the reduction and recycling of solid waste. In this paper, taking the representative urban solid waste as an example, combined with the current vigorous development of solid recovered fuel technology at home and abroad, investigated solid waste from different sources, deeply analyzed its total amount, composition, moisture content and calorific value and other characteristics, so as to provide the original analysis for the classification of solid waste and the preparation of solid recovered fuel products to.

Abstract:As the main technology of sludge harmless treatment, sludge drying and incineration in urban sewage treatment plants are more and more used in engineering. In the theoretical process calculation of sludge incineration, many key technical parameters such as sludge combustion calorific value, flue gas composition and flue gas enthalpy can be obtained. In this paper, the thermal calculation method of coal-fired boiler was used to analyze the influence of different moisture content on the temperature of sludge incineration flue gas through theoretical calculation, and the moisture content of sludge self-sustaining combustion was calculated by interpolation method. At the same time, the amount of auxiliary fuel ( general industrial solid waste ) needed to be added when the temperature of sludge incineration flue gas with different moisture content reaches 850 °C required by the standard was calculated theoretically. The research shows that the higher the moisture content of sludge, the lower the temperature of sludge incineration flue gas, and the more auxiliary fuels need to be supplemented; generally, industrial solid waste has a high calorific value and can be used as an auxiliary fuel for sludge, which can be used in conjunction with sludge incineration.

Abstract:With the rapid development of China’s economy, China has become the world’s first county in terms of car consumption increment and ownership, while the number of cars to be scrapped is also increasing. Non-ferrous metals, tires, glass and other materials and components in end-of-life vehicles can be recycled. So the dismantling industry of end-of-life vehicles has broad market prospects. This paper investigated the current situation of the dismantling industry of end-of-life vehicles at home and abroad, and took a dismantling project as an example for economic and technical analysis. Finally, it analyzed the current shortcomings of the domestic dismantling industry of end-of-life vehicles, and put forward corresponding suggestions. The dismantling of waste automobiles has good comprehensive economic, social and environmental benefits, which can promote the development of circular economy and achieve energy conservation and emission reduction. Although there are many shortcomings, with the gradual formulation and implementation of policies, the future automobile dismantling and recycling industry will gradually be standardized, clear and green.