Sustainable Mining and Metallurgy

Abstract:As the major component of China’s power supply, coal-fired power has been blame for its large carbon dioxide emissions for a long time.Under the guidance of the current goal of “ carbon neutrality and peak carbon dioxide emissions”, China’s energy and power industry will face a major transformation. In this process, “decoal” seems to become the best choice for energy conservation and emission reduction. However, In the process of gradually reducing the proportion of coal-fired power, it should be alert to the “accidental injury” of high-quality production capacity due to the misreading or amplification of the interpretation of national policies. More importantly, other power supply methods still have problems such as weak self-sufficiency of strong supply side, poor supply stability, low cost performance or immature technology. “decoal” road, need more patience.

Abstract:This paper compared and analyzed the technical characteristics of various nickel refining processes adopted by domestic and foreign nickel smelting enterprises, and briefly summarized the development of Jinchuan nickel refining technology and the major key technologies that had made breakthroughs and the key technical problems existing in Jinchuan nickel refining process. The results showed that the transformation from traditional nickel sulfide soluble anode electrolytic refining process to sulfuric acid leaching extraction separation electrowinning method or concentrated crystallization method, chlorination leaching extraction purification electrowinning method and carbonyl refining method was the mainstream direction of nickel refining technology improvement. Among them, the carbonyl refining method which had the advantages of the highest selectivity, the shortest process flow, the easiest to realize automation, the most environmental feature, significant energy saving and consumption reduction, and the key technologies had been broken through, was the most priority direction of nickel refining process improvement in large nickel refining enterprises.

Abstract:The differences between domestic and foreign tailings standards were compared from the aspects of tailings life definition, tailings classification definition, tailings flood control and drainage, anti-seismic calculation. Among them, foreign standards took Australia standards as an example. In terms of tailing pond life, the domestic standards required that the tailing pond should be closed and require reclamation in time after reaching the service life, the Australian standard was more inclined to the long-term existence of tailings and maintain long-term safety and stability. In terms of tailings pond classification, the domestic standards considered storage capacity, dam height and the influence of tailings pond accident, the Australian standard took into account the extent of the impact of the tailings dam accident. In terms of flood control and discharge, the domestic standards required the flood to discharge out of the reservoir in time, the Australian standard required reducing flood discharge through water balance management as far as possible, and gradually consuming flood through measures such as return water and evaporation. The anti-seismic calculation requirements of China and Australia were basically the same, and the seismic design and verification of important hydraulic structures should be adopted.

Abstract:Lead-zinc smelting enterprises were the key objects of long-term attention to environmental protection. There were many problems in their environmental management, such as prominent characteristics of “ three wastes ”, low quality of environmental protection publicity, low level of informatization, and lack of management data. It was imperative for lead-zinc smelting enterprises to establish an information-based environmental management platform to serve their own environmental management and decision-making. This paper discussed how to construct a new model of “ Internet+environmental management ” for lead-zinc smelting enterprises, so as to creat new ideas for the construction and service of modern green lead-zinc smelting enterprises.

Abstract:As the production capacity and particle size of metal zinc powder prepared by air injection method at the initial stage of production in a smelting company cannot meet the production demand, the effects of zinc liquid temperature, injection pressure, inner diameter of quartz tube, nozzle tooth number, nozzle processing and installation accuracy on the production capacity and particle size of metal zinc powder were explored. The results showed that under the process conditions of zinc liquid temperature 590-600℃, injection pressure 0.6-0.65MPa, quartz tube diameter 12mm, inner nozzle 30 teeth and outer nozzle 40 teeth, the production capacity of zinc powder increased from 20t/d to 28-30t/d, and the yield of -150 mesh zinc powder increases from 60% to more than 80%.

Abstract:A lead smelting enterprise in China used the combination of primary lead and recycled lead to realize the recovery of lead and zinc resources and the recycling of waste acid. The production process of nano-zinc oxide included leaching process, primary purification process, secondary purification process, synthesis process and baking process. In the production process, it was found that the recovery rate of nano-zinc oxide was low, resulting in high production cost. By optimizing the acid leaching times of the production process, reducing the zinc content of the acid leaching residue, comprehensively utilizing the zinc and cadmium metals in the secondary purification residue, recycling the synthetic tail liquor, and changing the NPP static baking furnace equipment to the dynamic baking furnace to improve the dust collection efficiency, the recovery rate of nano-zinc oxide was increased from 87.5% to 90.5%, and the economic benefit was good.

Abstract:By analyzing the causes of high zinc content of zinc dross and dust in a non-ferrous metal company’s 200000t/a zinc smelting, it was considered that the number of linear vibrating screen mesh equipped with the existing process was small, and some zinc particles entered dust during the screening process, resulting in high zinc content in dust. Therefore, adding 16 mesh and 35 mesh linear vibrating screen to sort the product of old 1^# and 2^# vibrating screen. By multistage screening, the technological process transformation effectively reduced the zinc content of zinc dross dust and obtained better economic benefits.

Abstract:Drying kiln was the key link in the use of volatilizing kiln lining. By analyzing the heat transfer between the flue gas flame and the kiln lining, and between the kiln lining and the kiln shell during the drying process, the mechanism of the drying kiln was expounded. By studying the changes in the temperature of the kiln shell and the temperature of the kiln head lining, and the time required for each section of the kiln shell to reach a certain temperature, it was deduced that the temperature of the kiln lining was 3~4times that of the kiln shell，and excessive heating should be avoid during drying, and the kiln lining had been dried when the shell temperature of the kiln tail exceeded 160℃. In addition, by analyzing the temperature distribution of kiln shell corresponding to different constant temperature at the end of the kiln, the main effect of each constant temperature was studied, which provided a basis for the drying process of the integral-casting lining of the volatile kiln.

Abstract:This paper introduced the equipment and process status of petroleum coke calcination cooler, analyzed the heat balance of the cooler, and designed a set of recovery schemes for sensible heat of high-temperature petroleum coke. According to the analysis of heat budget, the vaporization and heat absorption of cooling water and heat dissipation of tube wall of cooler account for about 71% of the total heat of calcined coke, indicating that the huge sensible heat resources in the cooling process of calcined coke were wasted by traditional disposal methods. To solve this problem, an inner cylinder was added on the basis of the existing cylinder to form a closed ring coelom between the inner cylinder and the outer cylinder, and then the heat transfer and utilization were realized through the water flow in the ring coelom. The proposed scheme can change the existing cooling mode, realize the effective recovery of sensible heat in the cooling process, and save about 4.6195 million yuan per year, which had good social, economic and environmental benefits.

Abstract:The alumina production process of a company used atmospheric condenser to absorb exhaust steam, and the heat of exhaust steam and condensate water were not fully utilized. Furthermore, the cooling tower needed to consume a large amount of circulating water, and the power consumption of circulating pump and cooling tower fan was high. In order to recover the waste heat of exhaust steam, through the comparison of schemes, the first type of vapor-cooled absorption lithium bromide heat pump was selected, and the circulating water system of evaporator was reformed to directly recover the latent heat of exhaust steam in the final evaporator of evaporation process, so as to make it become a heating source. Exhaust waste heat recovery can produce about 11.3 million yuan per year, and replace the boiler coal-fired heating, greatly reducing air pollution emissions.

Abstract:By analyzing of the problems affecting the waste heat recovery system of glass furnace, it can be seen that the amount of high-temperature flue gas, flue gas temperature, denitration facilities, steam pipeline length, steam output of waste heat boiler, and external steam consumption were all factors affecting the power generation of waste heat generating units. According to the analysis results, targeted energy-saving rectification measures were made, such as increasing the temperature of flue gas by holding the brick flue and steel flue of the furnace，reducing the temperature drop of denitration and dust removal system by heat preservation, sealing air leakage point and reducing ammonia injection，replacing tube of waste heat boiler and sealing air leakage，reducing external steam consumption, etc. After the implementation of the energy saving measures, the power generation was greatly improved, the power generation was increased from 2.5MW/h to 3.2MW/h, the daily power generation was more than 75MW, and the system maintenance cost was also reduced.

Abstract:The internal-external circulation anaerobic reactor (IC-EC) was used to treat the leachate of waste incineration plant. The engineering commissioning showed that the reactor could be started quickly in about 35 days and maintained long-term stability after inoculating the residual sludge in the plant. One year operation analysis results showed that though the water quality and quantity fluctuated continuously, but the operation effect of the reactor was stable, and the COD removal rate remained at 81.2%-94.1%, the sludge concentration at the bottom of the anaerobic reactor was 32.2-38.3g/L, and the effluent sludge concentration was only 1.8-2.5g/L, indicating that the reactor had a good sludge separation effect, which could reduce sludge loss and well retain microorganisms in the reactor.

Abstract:Combined with practical engineering cases, the application experience of in-situ barrier technology in the treatment of contaminated sites was summarized, mainly involving the determination of treatment objectives, the comparison and selection of overall technical schemes, the establishment of vertical seepage control system, and field closure technology. The determination of site restoration objectives and the selection of technical routes should be based on the conclusion of risk assessment, and the factors such as land use planning, restoration time and restoration cost should be comprehensively considered. The delineation of ecological isolation area should seal and control the vast majority of contaminated soil as much as possible, and reduce the excavation amount of contaminated soil. The structure form of vertical cut-off wall should comprehensively consider the permeability requirements of the wall, the rock and soil properties of the stratum, the construction cost and the working space. The permeability coefficient of the wall should reach the order of 10^-7cm/s. The depth of the bottom of the vertical cut-off wall entering the relative impervious layer was not less than 2m, and the curtain grouting and groundwater extraction can be adopted simultaneously.

Abstract:The wastewater treatment system of a factory in Beijing was old ，and the removal of _CODCr, ammonia nitrogen, phosphorus and other pollution factors was limited, so it was reformed in basis of the old system. The old intermediate water tank, regulation tank, biochemical tank and sand filter were transformed into anoxic denitrification tank, aerobic+MBR tank, chemical phosphorus removal sedimentation tank and breakpoint chlorination reaction tank, respectively. The optimal reagent concentration of chemical phosphorus removal and inflection point chlorination process was determined. After the transformation, the effluent quality of the system was stable, meeting the requirements of Integrated discharge standard of water pollutants (DB 11/307—2013 ).

Abstract:There were some problems in the open circulating cooling softened water system of Jinchuan Group, such as high water turbidity, high hardness of circulating softened water caused by concentration of Ca²⁺ and Mg²⁺, corrosion and spalling of tower concrete, damage and aging of filler, uncertainty of critical point of resin, etc. Starting from the composition of pollutants in the external environment, the blocking area and the causes of corrosion, the production process of the circulating cooling softened water system and the ion exchanger process were optimized by using the principle of microporous adsorption and cascade filtration of ion exchange resin. The softened water was introduced into the ion exchanger for reprocessing, and the advanced process of “N times small backwash+1 time large backwash” was used for resin regeneration. The turbidity index and microbial corrosion of the circulating cooling softened water were effectively reduced, and the water resources were effectively saved, the operation cost of the cooling circulating softened water production system was reduced, and the service life of the equipment was improved.

Abstract:This paper introduced the characteristics of industrial silicon smelting flue gas, the development of silicon smelting fume hood and the structure of the mainstream low smoke hood. From the geometric size design and flue gas pressure control of the low smoke hood, and the closed furnace cover, the technical feasibility of flue gas reduction was analyzed. It was pointed out that reducing the emission of silicon smelting flue gas can not be realized only by adjusting the operation of the smoke hood. It was necessary to improve the smelting process and the level of production automation， and apply new materials.

Abstract:This paper analyzed the problems of serious ash deposition, abnormal arching of combustion surface and abnormal closing of ash discharge door in the boiler exhaust chamber in Fukang smelter, and put forward some measures such as checking the scale type furnace exhaust in different periods, controlling the quality of coal combustion, blocking the leakage points of furnace body, and adopting pneumatic ash discharge method for ash discharge door. After the implementation of the measures, the problems affecting the air supply and air leakage of the boiler, such as serious ash deposition in the lower air bin of the grate, bridging, and slabing, were completely solved, which greatly improved the combustion conditions of the boiler and the combustion efficiency of the boiler.

Abstract:Based on the structure and anti-shock principle of isolation transformer, the differences between isolation transformer and ordinary transformer were compared. The isolation transformer had excellent isolation and anti-interference ability because the primary winding and secondary winding were arranged in different centers, or the windings were concentric, but the electrostatic shielding layers were set between the windings, and there were double insulation or enhanced insulation between the windings. This paper introduced the principle and key points of practical application of isolation transformer as electrical isolation, converting TN or TT system to IT system in the occasion of high requirements of electric shock protection, power supply for safe special low voltage system, and suppression of high frequency interference. In addition，three practical cases were cited to analyze the misuse of isolating transformer, and emphasize that the setting requirements of isolating transformer should be paid attention to when adopting isolating transformer, so as to avoid its functional failure，and it was not necessary to blindly select isolating transformer, so as to avoid increasing investment and causing waste of resources.

Abstract:The traditional silver ingot casting process had some problems such as high labor intensity, high risk coefficient, unstable quality of silver ingot products, and large silver loss, so a new automatic production line for silver ingots using nitrogen to protect molten silver was introduced. By introducing its principle, structure, process flow and advantages, it can be seen that as the new automatic production line of silver ingot used nitrogen to isolate the contact between silver and oxygen, and the whole process was controlled by PLC, it had the characteristics of automatic, green and environmental protection, no casting loss, and few defects in silver ingot.

Abstract:The traditional way of water intake usually consumes electric energy, or requires high terrain and geological conditions, resulting in a large number of excavation and slope support, or pipeline crossing the impervious layer cause the damage of the impervious layer. Using the pressure difference between the upstream water surface and the inner pipe, the siphon can lead the water flow from the upstream, across the highland to the downstream, and avoid the pipeline crossing the dam to destroy the anti-seepage layer. It was a better way to take water. HDPE geomembrane was used to prevent seepage on the dam surface and reservoir area of an acidic reservoir. In order to avoid damaging the seepage control system and save energy, siphon pipes were designed for water intake and transmission. By introducing the calculation of water conveyance capacity and installation elevation of siphon pipe, and accounting data, it was concluded that the siphon pipe meet the requirements of the project.

Abstract:Construction project completion environmental protection acceptance was an important part of environmental protection “three simultaneous” system. This paper reviewed the current situation of environmental protection self-acceptance of metal mining and dressing enterprises, summarized the common problems of self-acceptance, and put forward relevant opinions and suggestions in terms of acceptance content, acceptance deadline, acceptance condition, construction project change, acceptance implementation standards, and selection of acceptance units, so as to provide reference for enterprises to carry out self-acceptance according to laws and regulations and improve the quality of environmental protection acceptance of completion.

Abstract:Design optimization was an important work in the process of industrial architectural design, which run through project management. This paper introduced the design optimization contents and key points in the scheme design stage, construction drawing design stage and field construction, and illustrated them with examples. Quota design was an important manifestation of design optimization，which was often used to control project cost in fixed total price contracts. In addition, reducing design duplication errors was also a design optimization, and duplication errors should be avoided in design. In the design of industrial buildings, targeted optimization should be made according to the way of actual production and the actual use of buildings.