Sustainable Mining and Metallurgy

Abstract:As a crucial basic material for new energy batteries, non-ferrous metals are closely related to the development of the battery industry and have a significant impact on its development trend. The promulgation of the new EU Battery Regulation compels the low-carbon development of the EU battery industry, at the same time, raises the threshold for Chinese new energy batteries to enter the European market. It also imposes special requirements on upstream non-ferrous metal-related products and engineering construction in the industry chain. This article elucidated the content and background of the new EU Battery Regulation, analyzed its impact on the non-ferrous metal industry and standard system, specifically focusing on the carbon footprint of battery life cycle and the recycling of raw materials. Combining with the existing standard system of China’s non-ferrous metal industry, suggestions were made to accelerate the establishment of a carbon footprint accounting and evaluation standard system, improve the recycling and reuse standard system, and further enhance international cooperation in standards.

Abstract:In view of the problems of dispersion and low enrichment rate of valuable metals in the zinc leaching residue of a zinc hydrometallurgy plant by oxygen-enriched side-blown smelting-fuming process of pulverized coal, industrial tests were carried out to investigate the effects of temperature, pulverized coal rate, oxygen-enriched concentration, calcium-silicon ratio and reaction time on the metal volatilization rate and the direction of valuable metals in the side-blown smelting furnace and fuming furnace. The results show that under the optimum conditions of pulverized coal rate of 21%, oxygen concentration of 65%, furnace temperature of 1250℃ and time of 150min, the volatilization rates of lead and silver in side-blown smelting furnace are 90.3% and 86.5%, respectively. Lead and silver are mainly enriched in the dust of side-blown smelting furnace. Under the optimum conditions of pulverized coal rate of 13%, calcium-silicon ratio of 0.6 and blowing time of 120min, the zinc volatilization rate of side-blown smelting furnace reached 86.9%, and zinc is mainly enriched in fuming furnace dust.

Abstract:The impurity content of raw materials in the wet nickel refining production line of a factory is high, especially the content of calcium and magnesium. With the increase of processing capacity, calcium and magnesium are enriched in the follow-up system to achieve saturated precipitation crystallization, which affects the stable operation of the production line. On the basis of summarizing and comparing the common methods of removing calcium and magnesium, such as chemical precipitation method, concentration static method, ion exchange method and extraction method, combined with the existing extraction process, this paper used P204 extractant to carry out multi-stage countercurrent extraction of nickel sulfate solution, and analyzed the extraction effect of P204 under different pH values and different feed concentration conditions. The results showed that when P204 was used to extract C272 raffinate, the extraction rate of calcium showed a fluctuating upward trend with the increase of extraction stages, and reached the maximum after six-stage countercurrent extraction. The extraction rate of magnesium increased steadily with the increase of the number of stages, and remained about 98% after ten-stage countercurrent extraction. Under the same experimental conditions, the lower the pH value, the higher the extraction rate of calcium and magnesium ions, and the lower the extraction rate of iron and cobalt ions. When the nickel ion in the solution was high, nickel was precipitated before calcium and magnesium during P204 extraction, and the nickel removal rate was high. The solution was viscous after the reaction and the filtration performance was poor. Therefore, the extraction of the solution with higher nickel ions does not have practical significance.

Abstract:Numerical simulations of the temperature field of an slab of 960 high strength steel with a cross-section size of 230mm×1330mm have been carried out based on a solidification heat transfer model. The solidification heat transfer model was validated and optimized by nail shooting and surface temperature measurement experiments, and the effects of specific water flow, superheat and casting speed on the temperature field and solidification end of slabs were analyzed. When the specific water flow in the second cooling zone increases by 0.05L/kg, the solidification end position of the billet moves forward by about 0.376m; when the superheat increases by 10K, the solidification end position of the billet moves backward by about 0.82m; when the pulling speed increases by 0.1m/min, the solidification end position moves backward by about 2.15m. The solidification end position of the billet moves backward by about 2.15m. The solidification end position of the billet moves backward by about 2.15m. Finally, the reduction position and amount were adjusted, from 3 segments to 2 segments, the reduction position was changed from 9th,10th,11th segment to 11th,12th segment, and the reduction amounts of 11th,12th segment were changed to 2.5,2.0mm, respectively. After the process optimization, the center segregation and center porosity of the billet are obviously improved, and the rating results of the two are reduced from 2.0 to 1.5 before optimization.

Abstract:China’s electroplating sludge production is large, and a large number of toxic heavy metals are enriched, which is a hazardous waste. This paper introduced the principle, advantages and disadvantages of the traditional treatment process of electroplating sludge. Based on the existing problems of the current process, and according to the characteristics of various copper-containing secondary resource materials, different treatment processes were used to merge the smelting process, and an integrated innovation process of “oxygen-enriched side-blown submerged combustion smelting-oxygen bottom-blown continuous blowing” was proposed. At the same time, taking a copper-containing secondary resource utilization project as an example, the application effect of the process in the comprehensive utilization of copper-containing electroplating sludge and copper-containing solid waste was expounded. The process has the advantages of both side-blown submerged combustion and bottom-blown smelting, and has the advantages of wide adaptability of raw materials, high thermal efficiency, low investment and low operating cost. It has effectively realized the ' reduction, recycling and harmlessness ' of industrial solid waste, and created a new benchmark for the solid waste disposal industry.

Abstract:Waste lead-acid batteries contain lead, waste sulfuric acid and other harmful substances, which are hazardous wastes. If improperly disposed, they will cause pollution to the environment. Therefore, harmless disposal and comprehensive recovery are needed. This paper introduced the recovery process of lead-acid battery. On the basis of comparing various lead paste recovery processes, the advantages of oxygen-enriched side-blown bath smelting process for treating waste lead-acid battery were summarized. Taking a recycled lead recovery practice as an example, the process design, key points and parameters of oxygen-enriched side-blown bath smelting process for treating waste lead-acid battery were reviewed and summarized, which provides reference for factory design and technology upgrading of domestic recycled lead industry.

Abstract:According to the requirements of national ultra-low emissions, the paper analysed the limitations of the conventional electric precipitator, bag dust collector, electric bag composite dust collector in processing flue gas of aluminum hydroxide calciner, and put forward that the high temperature resistant metal electric bag composite dust collector is the best choice of aluminum hydroxide calciner to achieve ultra-low emissions, and analysed in detail the principle and technical characteristics of high temperature resistant metal electric bag composite dust collector. Taking one aluminum company’s ultra-low emission reconstruction of aluminum hydroxide calciner as an example, the technical scheme and application effect were introduced. The engineering practice shows that using the high temperature resistant metal electric bag composite dust collector, the dust emission concentration at the outlet of the dust collector is less than 5mg/Nm3, and the maximum resistance of the dust collector is less than 800 Pa, which fully meets the national ultra-low emission requirements. The high temperature resistant metal filter bag electric bag composite dust collector combines the advantages of electrostatic precipitator and bag filter. It is not limited by fuel and dust property, and has high capture efficiency for fine ultrafine particles. It has the advantages of wide application range, high temperature resistance, corrosion resistance, high dust removal efficiency and relatively low operating resistance.

Abstract:Lithium smelting mostly uses lepidolite and spodumene as raw materials, and pyrometallurgical smelting is carried out in a rotary kiln. The generated flue gas contains a large amount of heavy metal dust, SO₂ and NO_x. Taking the flue gas purification of rotary kiln of a 50000t/a battery-grade lithium salt project as the object, the characteristics of lithium smelting flue gas were explored, and the high-temperature dust-nitrate integration combined with sodium-alkali desulfurization process was selected to purify the flue gas. The process flow, system configuration and core design parameters were described in detail, and the field operation data were provided. After the flue gas is dedusted, denitrified and desulfurized by this process, the SO₂ concentration of the net flue gas at the outlet of the device is lower than 100mg/Nm₃, the NOx concentration is lower than 100mg/Nm₃, and the dust emission concentration is lower than 10mg/Nm₃. The parameters meet the ultra-low emission requirements, which provides a reference for the design of flue gas purification in similar lithium industry.

Abstract:The control requirements of metal impurity content in electronic grade polycrystalline silicon are high, and its production process and post-treatment process are strict. The electronic grade polysilicon material will inevitably cause the problem of secondary metal introduction in the crushing treatment, so it is particularly important to clean the broken electronic grade polysilicon material. This paper analyzed the factors affecting the cleaning quality of electronic grade polysilicon materials, including cleaning process,cleaning agent selection，cleaning equipment material, environmental cleanliness and human operation factors, and put forward corresponding control measures.

Abstract:The waste heat boiler of oxygen-enriched side-blown furnace in a lead smelter has serious fouling and coking, the flue gas channel becomes smaller, and a large amount of flue gas overflows, resulting in the system unable to produce normally. This paper mainly analyzed the main components, formation mechanism and causes of ash deposition and coking, and put forward measures to reduce coking and prevent coking. The fouling and coking of waste heat boiler are mainly affected by secondary air volume, furnace charge, side-blown furnace process control, negative pressure and other factors. By reasonably controlling the secondary air volume of the side-blown furnace, reducing the sulfur content of the high-lead slag in the bottom-blown furnace, controlling the input ratio of harmful elements, and reasonably controlling the reducing atmosphere and negative pressure of the side-blown furnace, the problem of ash deposition and coking in the waste heat boiler of the side-blown furnace was basically solved. The cleaning time was greatly reduced, from the original 90h to 15h, and the monthly operation rate of the side-blown furnace was increased from 89% to 94%.

Abstract:A zinc smelting company uses a rotary kiln method to recover zinc from the leaching residue produced by the wet system. This paper introduced the process principle, process flow and composition control standards of leaching residue and coke powder in a large rotary kiln production system in China, and further extended the influence of rotary kiln tail temperature and system pressure on production and control essentials. The formation principle of the middle and rear coking of the rotary kiln, the influence on production and the operation method of eliminating the ringing of the chemical kiln were discussed in depth. In addition, the key equipment and process parameters of the subsequent treatment process of rotary kiln, namely waste heat boiler, electric dust collection and zinc oxide desulfurization process, were analyzed, and the problems and solutions that were easy to occur in production were pointed out, in order to provide practical equipment, process and operation experience for the rotary kiln production system of zinc smelting industry.

Abstract:The 1.2 million t/a copper slag beneficiation system in some company mainly recovers copper metal from flash smelting slag through slow cooling, crushing, grinding, flotation, dehydration and other processes. Based on the aspects of safe production, energy saving and consumption reduction, and automation technology application in slag beneficiation, this paper focused on the optimization and improvement of the production process of copper slag beneficiation and the results achieved.

Abstract:The development and utilization of mineral resources have different degrees of negative impact on the natural environment and ecosystems. It is of great significance to study the relationship between mineral resources development and environmental protection. In this context, this paper studied the relationship between environmental pollution caused by mineral resources development and environmental remediation capacity, as well as the relationship between ecosystem impact caused by mineral resources development and ecosystem remediation capacity, and analyzed how to use environmental self-purification and ecological self-remediation capacity to achieve the balance between resource development and ecological protection at the lowest cost. The difficulty of artificial restoration under the conditions of protective mining and non-protective opening of different mines was given by combining qualitative and quantitative analysis, which guided the construction of green mines from the macro level.

Abstract:In this paper, a water balance model and a water quality model were constructed to quantitatively analyze the impact of seepage water from a tailings pond on the downstream surface water quality, and to provide a basis for the construction of the seepage control facilities. First, a two-dimensional seepage analysis of the tailings dam was conducted, and the calculated seepage was used in the water balance and water quality models. Then the water balance model and water quality model of the tailings facility were established to simulate the water quality of the tailings seepage water, surplus water in the pond and downstream river water under different schemes, i.e. with or without seepage control facilities. By comparing and analyzing the results of water quality prediction, it shows that the leakage of tailings pond has a significant impact on the water quality of downstream river, and it is recommended that a horizontal seepage control scheme for the whole facility should be adopted, with HDPE geomembrane liner installed on the upstream embankment, and a 1m thick soil liner over the basin and side slopes of the facility, and the basin soil liner should be well compacted to reach a permeability of 10-5~10-6cm/s, and the width of the tailings beach should be greater than 200m, and the cleaner and rougher tailings should be discharged separately, with cleaner tailings kept submerged.

Abstract:Lead and zinc smelting activities are one of the important sources of soil heavy metal pollution. The situation of heavy metal pollution in the soil of lead and zinc smelting sites in China is becoming increasingly serious, which seriously threatens human health and safety, and needs to be treated and repaired urgently. At first, the pollution status and pollution characteristics of soil pollution in lead and zinc smelting sites in China were analyzed. Then, the principles, advantages, disadvantages and applicability of several commonly used heavy metal contaminated soil remediation technologies were discussed, including physical and chemical repair method, bioremediation and combined repair method. Finally, the joint remediation technology was proposed as the main research direction of soil heavy metal pollution control and remediation in lead and zinc smelting sites in the future. In the process of contaminated soil remediation and treatment, it is necessary to combine the degree, scope and characteristics of site soil pollution, select remediation technologies in a targeted manner, and continue to strengthen the basic innovation of remediation technologies, and explore a variety of remediation technologies to cooperate with efficient governance models to improve the efficiency and adaptability of remediation technologies.

Abstract:Sweet sorghum straw is a kind of biofuel.Rotary cylinder solid-state fermentation is often used to produce ethanol, but heat accumulation is easy to occur in the rotary solid-state fermentation process, resulting in low fermentation efficiency.In this paper, the thermal properties of straw were measured experimentally, and the changes of thermal conductivity and specific heat capacity under different bulk density (porosity), temperature and moisture content of straw were analyzed, which provided basic data for the subsequent study of the motion characteristics of rod-shaped particles in rotary cylinder.The results shows that there is a linear relationship between the porosity of straw and the bulk density.With the increase of bulk density, the porosity decreases.The density of water-bearing straw has a linear relationship with water content, and the density increases with the increase of water content.With the increase of temperature, moisture content and density, the thermal conductivity of straw increases, and the order of influence is: temperature ＞ moisture content ＞ density.In this paper, the specific heat capacity of straw particle pile remains almost unchanged with the increase of water content and bulk density.As the temperature increases, the specific heat capacity increases.

Abstract:Medium-sized water companies have the characteristics of moderate scale, flexible management, and professional personalized services. They play a central role in the development of the water industry and face many challenges. In this context, medium-sized water enterprises need to improve the development level of enterprises through scientific strategic management. This paper proposed to use SWOT analysis method as the core tool for the strategy formulation of medium-sized water enterprises, analyzes the role of SWOT analysis method in strategy formulation, and finally introduced the strategy formulation process and performance evaluation method and index system of medium-sized water enterprises. This paper put forward solutions such as attaching importance to strategic awareness, reasonably setting up performance appraisal mechanism and strengthening lean management, so as to improve the strategic management ability of medium-sized water enterprises and promote the sustainable and healthy development of enterprises.