Sustainable Mining and Metallurgy

Abstract:The arsenic-antimony bearing dust produced by pyrometallurgical treatment of lead anode slime was used as the treatment object. Combined with oxygen pressure alkali leaching test and XRD, ICP-OES and other characterization methods, the effects of oxygen pressure, liquid-solid ratio, sodium hydroxide concentration, leaching temperature, leaching time on the distribution behavior of arsenic, antimony and lead were investigated. The results show that under the conditions of oxygen partial pressure of 2.0MPa, liquid-solid ratio of 10mL/g, sodium hydroxide concentration of 2mol/L, leaching temperature of 200℃ and leaching time of 2h, more than 99.5% of arsenic enters the solution, antimony, lead and bismuth enter the leaching residue, and the arsenic content in the washing residue is less than 0.5%，which can be used to prepare high-quality antimony products. The deep separation of arsenic and antimony is realized by oxygen pressure alkali leaching-water washing process.

Abstract:This article has carried out the research of smelting nickel slag modification. Firstly, the relationship between Gibbs free energy of main reactions and temperature during smelting nickel slag is obtained by thermodynamic calculation, which shows that under the conditions of 750~1600℃, coke powder as reductant and limestone as flux, all main reactions can occur. On this basis, combined with the theory of increasing calcium and decreasing silicon, nickel slag was modified in the high temperature box resistance furnace to obtain a reasonable slag type. The effects of limestone addition, iron silicon ratio and temperature on the content of nickel and copper in nickel slag were discussed, and the effects of calcium oxide and limestone on the properties of nickel slag were studied. The test results show that under the conditions of smelting temperature 1420℃, iron silicon ratio 1.2~1.3, limestone content 9%~11%, and settling time 60min, the nickel content and copper content can be reduced to 0.37% and 0.27% respectively, reducing the mechanical inclusion loss and chemical dissolution loss of nickel copper valuable metals in nickel slag. The XRD phase analysis of the modified nickel slag shows that the addition of limestone will destroy the complex iron magnesium silicate structure and transform it into a Fe2SiO4 structure with simple structure and easy reduction. The modification effect of limestone on nickel slag is better than that of calcium oxide. This study is beneficial to reduce the loss of valuable metals in nickel slag, and lays a theoretical and practical foundation for the research on slag type of nickel smelting system.

Abstract:In this paper, the particle size, composition, radioactivity, corrosion and leaching toxicity of a tungsten tailings in Hunan were analyzed. The results show that the main components of the tungsten tailings are SiO_2, CaO and Fe₂O₃, which are basically consistent with the mineral composition required for cement hydration. The radioactive, corrosive and leaching toxicity indexes are lower than the limit values of national standard, indicating that the tungsten tailings are harmless to the environment and can be explored for resource utilization. On this basis, using the tungsten tailings as the main raw material, a new type of composite admixture was prepared by physical excitation and chemical excitation, using reasonable raw material mix ratio and advanced preparation process, and the performance of the new composite admixture was tested and analyzed by mortar method and test cake method respectively. The test results show that the 28d activity index of 1^# and 2^# samples of the new composite admixture with moderate amount of tungsten tailings micropowder, large amount of grinding aid admixture and alkaline activator is ≥95%, and the stability of five samples is qualified. When the amount of tungsten tailings powder is constant, the increase of activity index of new composite admixture is proportional to the amount of grinding aid admixture and alkaline activator, and the activation effect of alkaline excitation plays a certain role in promoting the increase of activity index.

Abstract:The leaching residues of zinc hydrometallurgy are different in composition, but all contain valuable metals such as zinc and silver, as well as heavy metals such as lead, cadmium and arsenic. They are hazardous wastes and need to be harmlessly treated and recovered. At present, the main zinc leaching residue treatment technologies in China include rotary kiln, fuming furnace, top blowing furnace and so on. These technologies have been applied for many years, and the technologies are mature and reliable, but there is still much room for improvement in energy conservation and environmental protection. In recent years, oxygen-enriched side-blowing technology has been successfully applied to the treatment of zinc leaching residue, mainly including the side-blowing submerged combustion technology of China ENFI and the Vanukov side-blowing technology. On the basis of summarizing the current situation of zinc leaching residue treatment technology, this paper introduced the melting mechanism of zinc leaching residue molten pool and the process flow of ' side blowing furnace + fuming furnace ', and introduced the application of two side blowing technologies of Vanukov side-blowing furnace and side-blowing submerged combustion furnace in China 's zinc smelting plant, and analyzed and compared the furnace structure, production operation and technical indicators. The side-blowing submerged combustion technology of China ENFI has the advantages of low energy consumption, controllable smelting temperature, simple operation, high degree of automation, low opening cost, stable flue gas and low nitrogen oxide content. In the future, it will become the mainstream treatment process of zinc smelting slag in China and even in the world.

Abstract:In this paper, the generation principle, distribution and related sites of waste heat in oxygen pressure leaching of refractory gold ore was studied. According to different gold ore and manufacturing technique, a waste heat recovery system was established, including waste heat cleaning, waste heat collection, waste heat transformation, waste heat utilization and other steps. This waste heat recovery system can maximize the recycling of waste heat of oxygen pressure preleaching process of refractory gold ore and energy saving and emission reduction, and enhance the adaptability and integrity of oxygen pressure preleaching process for refractory gold ore.

Abstract:Regular furnace side is the key factor for aluminum reduction cells to achieve good economic indicators and long cell life. In the production process, the furnace side is eroded and damaged with the increase of cell age or due to poor management, which further affects the current efficiency of aluminum reduction cells and the safe production of aluminum reduction cells. In this paper, the feasibility of the regeneration of the electrolytic cell furnace side was analyzed from the aspects of the electrolyte system, the damage mechanism of the furnace side and the conditions for the establishment of the furnace side. Taking the electrolytic cell with unstable cell condition, thin furnace side or no furnace side as the test cell, the practical operation scheme was put forward, and the changes of the furnace side thickness, voltage, current efficiency and the temperature of the cooling hole in the whole cell before and after the furnace side regeneration were compared. After the regeneration of the furnace side, the average thickness of the furnace side A and B increased from the previous 3cm and 7cm to 9cm and 13cm, respectively, and an ideal furnace side was formed in the position where there was no furnace side before. The temperature of the cooling hole decreased, the operation of the electrolytic cell was gradually stable, the running voltage of the cell was obviously reduced, and the current efficiency was also improved.

Abstract:The process of aluminum electrolysis follows the principle of double balance of voltage and energy, and energy balance is an important factor restricting the energy saving of electrolytic cell. In this paper, the factors affecting the heat dissipation of electrolytic cell were analyzed based on the principle of heat transfer, and the measures adopted in the industry were summarized, such as adjusting the ambient temperature, cell temperature, thermal conductivity of the cell, the whole heat dissipation area, flue gas flow rate and so on. This paper points out that adjusting the aluminum level of the electrolytic cell, the flue gas flow rate and the covering material coverage system are commonly used measures to adjust the heat dissipation of the electrolytic cell, which are simple and effective, and the cost is low. Adjusting the cathode lining structure of the electrolytic cell has the greatest influence on the energy balance of the electrolytic cell, and the effect is obvious, but the technical requirements and the cost are the highest. Specific measures need to be based on their own situation.

Abstract:An enterprise uses the side wall directional solidification segregation method to produce refined aluminum, and the content of zinc and vanadium impurities cannot meet the requirements of the industry standard 3N5 refined aluminum. In this paper, through theoretical analysis of the equilibrium distribution coefficient of each impurity element in primary aluminum and combined with the actual production, it can be seen that the reason why zinc impurities cannot meet the requirements is that the content of zinc impurities in primary aluminum is high, and the equilibrium distribution coefficient of zinc in aluminum is relatively large, and the removal efficiency is low. The reason why vanadium impurities cannot meet the requirements is that the equilibrium distribution coefficient of vanadium in aluminum is 5.1, which is larger than 1 and cannot be purified by segregation method. Therefore, according to the impurity control requirements of refined aluminum and the purification and impurity removal efficiency, the control requirements of each impurity component in the alumina were calculated, and put forward the measures to adopt high-grade and high-quality raw materials; in order to solve the problem that vanadium cannot be removed by segregation method, borax and strontium chloride were used to remove vanadium. Finally, the directional solidification segregation method was successfully applied to produce qualified refined aluminum products.

Abstract:In the process of alumina production, the formation of pipeline scab in high pressure dissolution process is inevitable. Scab will reduce heat transfer efficiency, increase energy consumption and increase production costs. On the basis of introducing the composition and phase of scab, the cause and harm of scab, this paper analyzed the problems existing in the removal of scab in the high pressure dissolution process of Zunyi Aluminum Co., Ltd., and optimized and improved the existing high pressure water removal method. There are great differences in the mechanism and phase composition of the formation of high pressure dissolution pipeline scab. The low temperature section scab is mainly sodium silicon slag, and the high temperature section scab is mainly perovskite and hydroxyl perovskite. For low-temperature casing, scab removal can be achieved by increasing the cleaning pressure; for the high temperature section, the method of molten salt heating dry burning combined with high pressure water removal can be used to eliminate the scab. The production practice showed that under the conditions of salt dry burning for 3~4h, temperature of 300~320℃ and cleaning pressure of 150MPa, the cleaning effect of casing scar in high temperature section is obviously improved, and the heat transfer coefficient is obviously improved, with an average value of 900W/m²·℃. The optimization method has achieved good cleaning effect.

Abstract:When dealing with low temperature, high turbidity and high alkali water in a water plant in Xinjiang, there were problems of difficult settlement of alum flower and high turbidity of effluent, and high energy consumption and operation cost. In this paper, from the perspective of strengthening the coagulation effect of the process, PAFC and PACS were obtained by compounding iron salt and aluminum sulfate with PAC respectively. PAFC and PACS were used as coagulants for water treatment experiments, and anionic coagulant PAM was added .The effect of compound coagulants on the treatment of low temperature, high turbidity and high alkali water was studied. The experimental results show that when the dosage of PAFC and PACS is 50mg/L, the turbidity of the effluent is reduced to 7.3NTU and 1.58NTU respectively, which meets the requirements of the water plant. After the addition of anionic coagulant PAM, especially the use of drinking water level PACS with anionic PAM, the effluent turbidity decreased to 0.34NTU. Using drinking water level PACS or PACS+anionic PAM to treat low temperature, high turbidity and high alkali raw water, the drug consumption can be reduced by 37.5%,and the amount of bleaching powder can be reduced by 40%, achieving the goal of saving energy and reducing operating costs.

Abstract:The collected fugitive gas desulfurization of a smelter adopts the sodium alkali process, and the acid tail gas desulfurization adopts the active coke process. The desulfurization device has the problem that the tail gas after desulfurization cannot meet the special emission limit requirements. This paper put forward the optimization scheme on the basis of discussing the operation status of the existing device (SO₂≤100mg/m³, NO x ≤100mg/m³, particle content≤10mg/m3). The principle, process flow, equipment selection and system performance of ionic liquid desulfurization were mainly discussed. In view of the problems of large fluctuation of SO₂ concentration in flue gas, unstable SO₂ concentration in tail gas emission, excessive consumption of ionic liquid and high concentration of thiosulfate in ionic liquid, the corresponding treatment measures were put forward. After optimization, the SO₂ concentration in the tail flue gas was less than 100mg/m³, and most of the time is less than 30mg/m³. Practice has proved that the desulfurization process is selected correctly, the design parameters are set reasonably, the device runs smoothly, and the desulfurization achieves the ideal effect.

Abstract:In this paper, the content of indium and germanium in white dust was detected by inductively coupled plasma atomic emission spectrometry. The sample was dissolved by HCl-HNO3 system, and the furnace temperature and reagent addition time were strictly controlled to make the sample completely dissolved and clarified. Indium germanium standard solution was prepared, and ICP-AES instrument was used to select indium and germanium spectral lines and correct interference. The method is simple, rapid, accurate, sensitive, and has good precision and accuracy. The detection limits of germanium and indium are 0.043μg/mL and 0.020μg/mL, respectively. The relative standard deviation ( n =7) is 1.0%~2.0%, and the recovery rate is 95.61%~99.15%. It can detect the content of indium and germanium in whitedust of copper smelter.

Abstract:Rotary kiln incinerator is a multi-purpose incinerator with strong adaptability and can burn a variety of liquid and solid waste. The application of reverse flow rotary kiln in the field of hazardous waste disposal is gradually increasing due to its pyrolysis-based incineration process. Due to the diverse sources and complex composition of hazardous waste, the material combination, slag burming reduction rate and coking in the process of rotary kiln incineration are the issues of concern in the industry. Based on the operation experience of China ENFI Xiaogan Solid Waste Disposal Center project, this paper discusses the process of countercurrent rotary kiln, including the proportion of incineration, the key points of process control in the feeding process, the control method of slag thermal burning rate, the causes of coking in each part of incineration system and the prevention and control measures, in order to provide reference for the long-term stable operation of countercurrent rotary kiln in the industry.

Abstract:In this study, three sites of historical gold heap leaching tailings in Gansu and Xinjiang were taken as the research object, and the pollution status of gold heap leaching tailings and surrounding soil and groundwater in the three sites was studied. A total of 195 gold heap leaching tailings samples and 469 soil samples (including 12 control point samples) and 45 groundwater samples (including 3 control point samples) were collected. The results showed that total cyanide (in terms of CN-), Cu, As, Cd, Zn, Pb and Ni factors were detected by acid leaching or water leaching in the samples of historical gold heap leaching tailings. The arsenic elements of some monitoring points in the soil around the gold heap leaching tailings exceeded the standard. The arsenic content in the soil and groundwater around the heap leaching tailings is obviously higher, which is related to the high arsenic content in the gold mine associated with cyanide heap leaching gold extraction. With the passage of time, after rain water scour and leachate, the soil and groundwater at the bottom of the tail slag and nearby suffer arsenic pollution.

Abstract:The organic waste gas produced in the production process of the extraction workshop is mainly composed of extractant and solvent oil. It has high volatility, flammability and certain toxicity, which will pollute the atmosphere. This paper introduced the ventilation technology currently used in the extraction workshop, and focused on the principles, devices and adaptability of commonly used organic waste gas treatment schemes, such as purification tower-activated carbon adsorption scheme, RTO regenerative combustion scheme, polymer material absorption + steam regeneration scheme, etc., and gave suggestions on the selection of organic waste gas purification schemes according to the actual situation.

Abstract:In this paper, the flow field was established for the branch, ring and mesh water distributors used in the anaerobic reactor for landfill leachate, and the flow state of the wastewater after entering the water distributor is simulated respectively. The effects of main parameters such as different water distributor structure and branch outlet angle on the water distribution effect were discussed. The simulation results show that the flow distribution of each outlet in the annular distributor is the most uniform, and when the angle between the branch pipe and the annular main pipe increases, the flow distribution of each outlet becomes more uniform. When the angle between the branch pipe and the main pipe axis is 60°, the water distribution uniformity is the best.