Sustainable Mining and Metallurgy

Abstract:Bleeding of backfill material has a significant impact on the backfill rate, retaining wall pressure, and mechanical properties of the backfill body, but the current understanding of the bleeding mechanism is unclear. Therefore, the effects of the ash-sand ratio, quality ratio, particle size distribution, and superplasticizer dosage on the bleeding of backfill material were studied, and the evolution of the microstructure during the bleeding process was tested using CT technology. The results show that the bleeding of the backfill material is affected by the particle size distribution, ash-sand ratio, quality ratio, and superplasticizer dosage, and increasing the fine particles, ash-sand ratio, and quality ratio can significantly reduce the amount of bleeding, while adding superplasticizer increases the risk of bleeding. Based on the CT test results and Porous Network Modeling, the bleeding process of backfill material can be divided into five stages: induction period, accelerating period, constant period, consolidation period, and final consolidated period. The formation, development, and closure of the channels occur throughout the entire bleeding cycle. The research results are of great significance for deepening the understanding of the slurry bleeding process and achieving the regulation of slurry bleeding.

Abstract:Impact velocity and time are important parameters for the crusher. In order to optimize the working parameters of the crusher, reduce energy consumption and improve efficiency, this paper took the green sandstone as the research object, simplified the simulation of the impact model, and used the engineering simulation software ANSYS-Workbench based on finite element analysis to carry out the transient analysis of the impact process of the green sandstone, and studied the rock impact time under different falling heights. The results show that the change of acceleration during the impact process of green sandstone can be divided into four stages of the unchanged stage before contact, the rapid increase stage, the slow decrease stage, and the unchanged stage after contact; the impact time of green sandstone is short, generally millisecond, and increases with the increase of falling height. The results have certain theoretical guiding significance for the design optimization of crusher and other machinery.

Abstract:To effectively control the dust in the working face and ensure the safe and efficient production in the coal mine, taking the fast excavation working face of 20202 return airway in Sunjiacha Longhua Coal Mine as an example, by analyzing the dust production characteristics and dust migration distribution law of the working face, the dust control technology was studied for the main dust source points. The results show that the main dust source of the fast excavation working face of the 20202 return airway is the continuous high-strength cutting and caving impact of the anchor machine drum. The dust in the fully mechanized excavation face enters the eddy current area with the air flow, so that the high concentration dust is mainly concentrated in the eddy current area. The dust concentration exceeds 1000mg/m³, but the dust diffusion range is small in the rear. Furthermore, the organic comprehensive dust control technology system of “dust suppression, dust control and dust removal” was proposed. A fast-connecting air-control dust removal device with a length of 1.5m, a weight of no more than 5kg, a radial air outlet around the periphery, an axial air outlet at the front end, and a simple axial and radial air adjustment was developed, and an airborne negative pressure dust removal system and supporting processes were developed to form a supporting dust prevention technology and equipment. After the application of the above comprehensing treatment technology in the working face, the dust reduction efficiency of the workers at the operating site of the driving anchor machine platform reached 88.1%; the dust reduction efficiency at 4-5m after the bolter is 81.21%, which effectively realizes the comprehensive dust control of the working face.

Abstract:Converter vanadium slag is a kind of multi-metal mineral resource containing vanadium, titanium and chromium, and its available value is very high. In this paper, the principle, process flow and process characteristics of traditional vanadium extraction process and new process of vanadium slag were reviewed, and the development direction of comprehensive utilization of vanadium slag was prospected. The traditional vanadium extraction process from vanadium slag are sodium roasting-water leaching process and calcification roasting-acid leaching process. Subsequently, salt-free roasting-acid leaching process, magnesium salt roasting-acid leaching process, manganese salt roasting-acid leaching process and other improved processes were successively developed. The characteristics of these processes are as follows: vanadium slag is first subjected to high temperature oxidation roasting, and then vanadium is extracted by water leaching or acid leaching. The characteristics of new processes such as sub-molten salt method and sulfuric acid oxygen pressure leaching method are that vanadium slag does not need oxidation roasting, and vanadium is directly extracted by acid leaching or alkali leaching under a certain oxygen pressure. By constructing a reasonable and efficient new physical and chemical system of acid leaching or alkali leaching metallurgy, the direct extraction of vanadium, titanium and chromium from vanadium slag by wet leaching process and the comprehensive recovery of valuable elements such as iron and manganese will be the development trend of comprehensive utilization of vanadium slag.

Abstract:A novel process for the recovery of nickel, cobalt, manganese and lithium from spent lithium battery cathode materials was proposed. Nickel, cobalt, manganese and lithium metals in cathode materials were recovered by two-step carbothermal reduction-hydrometallurgical leaching process, and the recovery mechanism and process of valuable metals in cathode materials were studied. The results show that lithium metal is preferentially extracted by two carbothermal reduction processes. Under the optimum conditions of calcination temperature 650℃, carbon content 8%, water immersion time 2h, pyrolysis temperature 95℃ and pyrolysis time 4h, the lithium recovery rate can reach 88.7%, and the purity of lithium carbonate is 98.84%. The valuable metals of nickel, cobalt and manganese were recovered by hydrometallurgical leaching process. The valuable metals of nickel, cobalt and manganese were recovered by wet leaching process. The optimum experimental conditions of high acid leaching process were as follows: the amount of hydrogen peroxide was 1.2 times of the theoretical amount, the leaching temperature was 60℃, the leaching time was 2h, and the pH value of the solution was 1.5. The optimum experimental conditions for the iron and aluminum removal process are temperature 90℃, reaction time 2h, and solution pH value 3.5. Under the optimum conditions, the yields of nickel, cobalt and manganese were 99.4%, 99.5% and 98.9%, respectively.

Abstract:In this paper, nickel sulfate, a by-product of copper electrolysis, was refined and purified by the process of “roasting deamination-dissolution liquid-oxidation iron removal-P204 extraction impurity removal-evaporation crystallization”. The experimental results show that after 40min calcination and deamination, there is almost no ammonium ion in the crude nickel sulfate; using H2O2 as oxidant and Ni(OH)2 as neutralizer, under the conditions of reaction time 60min, reaction temperature 60-70℃ and no adjustment of acidity, the removal rates of iron and arsenic were 98.8% and 94.3%, respectively. Using P204 as extractant, the extraction rate of nickel is only 0.72%, the extraction rates of calcium, copper, iron, manganese and zinc impurities are all greater than 99%, and the concentrations of calcium, copper, iron, manganese and zinc in the raffinate are all less than 10mg/L; finally, the main grade of nickel sulfate obtained by evaporation crystallization is more than 22%, which meets the requirements of refined nickel sulfate products of HG/T 2824—2022.

Abstract:Aiming at the reduction leaching solution of zinc anode slime in wet zinc smelting, battery grade manganese sulfate (qualified product) was prepared by iron jarosite method to remove potassium and sodium, neutralization and hydrolysis to precipitate iron, manganese fluoride to remove calcium and magnesium, hydrogen sulfide to remove heavy metals, and evaporation-concentration-crystallization method. The single factor experiment was carried out to investigate the influence of step-by-step purification process conditions. The results showed that the concentration of potassium, sodium, calcium and magnesium in the solution was less than 60mg/L, the concentration of iron ion was less than 1mg/L, and the concentration of heavy metal lead and zinc was less than 5mg/L under the conditions of the molar ratio of iron to potassium and sodium was 5, the pH of neutralization hydrolysis precipitation of iron was 4.0, the excess coefficient of manganese fluoride was 1.4, hydrogen sulfide dosage was 0.2 mol, and the temperature was 60-97℃. The solution was stirred in a water bath for 4-6h and then evaporated and crystallized. The obtained crystal product was baked at 105℃ for 12h to obtain a manganese sulfate monohydrate product. Its chemical composition meets the standard requirements. The product was characterized by XRD and SEM-EDS. The results show that manganese sulfate monohydrate has high purity, concentrated particle distribution, rough surface but no floccules.

Abstract:The flue gas composition of cathode carbon block carbon roasting for aluminum is complex, which contains a large number of high concentration pollutants such as particulate matter, asphalt fume, sulfur dioxide and nitrogen oxides. In this paper, an ultra-low emission technology of asphalt fume was proposed. The raw material powder produced by cathode carbon for aluminum was used as the adsorption powder. The adsorbed asphalt powder was returned to the workshop to continue to be used as the production raw material. The process flow and key equipment of the technology were introduced, and the particle size, specific surface area and adsorption effect of the adsorption powder were studied. The technology was applied in a carbon plant and operated stably for 6 months. Using this technology, zero emission of hazardous waste was achieved, and there was no pipeline blockage, paste bag and other phenomena. After the transformation, the concentration of particulate matter in the roasting flue gas decreased from 15.9mg/m3 to 1.7mg/m3, the concentration of sulfur dioxide decreased from 96.0mg/m3 to 13mg/m3, and the emission concentration of asphalt smoke decreased from 33.5mg/m3 to 12.8mg/m3. The flue gas treatment effect was good.

Abstract:Oxygen enriched side blown technology has been widely promoted in the recycling of hazardous waste, especially in the recycling of non-ferrous metal hazardous waste. This paper introduced the process and equipment of the oxygen enriched side blown process, and analyzed the mechanism of the oxygen enriched side blown process for the treatment of hazardous waste, including the combustion process, the reduction process of metal oxides, and the slagging process. The trend of main components of hazardous waste such as water, organic matter, sulfur, fluorine, chlorine, and heavy metal elements were introduced in order to more clearly grasp the core of the process optimization and clarify the direction of subsequent improvement of the process level, and provide technical support for the subsequent improvement of the resource utilization process.

Abstract:Coal coking process produces a large amount of coke oven gas. The hydrogen content in coke oven gas is process 55%-60% (volume fraction). After purification, hydrogen can be widely used in the chemical industry. Hydrogen is one of the main raw materials for polysilicon production. Hydrogen is used in many places and in large quantities in the production of polysilicon. This paper mainly studied the feasibility of coke process by-product hydrogen after PSA deep purification for polysilicon production system. The experimental results show that the purity of hydrogen produced by the coke process after deep purification is stable above 5N, and does not contain organic impurity methane, which meets the requirements of polysilicon production for hydrogen quality. The content of polysilicon impurities produced by the coke process by-product hydrogen is mostly lower than that of the original hydrolysis hydrogen production. Although the content of C impurities fluctuates greatly, its average value meets the requirements of electronic grade 2 products. The production cost of polysilicon can be reduced by 270-360 yuan/t by using hydrogen produced by coal coking process instead of traditional electrolytic water to produce hydrogen.

Abstract:High temperature arsenic-containing flue gas will be produced when arsenic-containing concentrate is treated in non-ferrous smelting industry. The conventional arsenic flue gas recovery process is a one-step quenching method, which has problems such as low grade of arsenic trioxide products in crude arsenic, low dust collection efficiency and service life of electrostatic precipitators. Therefore, this paper proposed a new process of arsenic-containing flue gas grading and quenching treatment, that is, to cool the flue gas by grading absorption, to set up a first-stage quenching tower at the inlet of the electrostatic precipitator, to spray and absorb the impurities such as sulfur trioxide, hydrogen fluoride and hydrogen chloride in the flue gas, and to set up a second-stage quenching tower at the outlet of the electrostatic precipitator. The flue gas is rapidly cooled by spraying liquid water, which effectively improves the arsenic trioxide grade in the crude arsenic in the arsenic recovery system after the second-stage quenching tower. After the process optimization, the grade of arsenic trioxide produced is more than 95%, which is much higher than the grade of 70%-80% of arsenic trioxide produced by one-step quenching method, and the recovery rate of valuable metals such as gold, silver and copper in flue gas is improved. When the ore grade is the same, the grading treatment process can greatly reduce the crude arsenic production and the corresponding disposal cost of the arsenic collection system, which is more conducive to the resource utilization of crude arsenic and can bring obvious economic benefits to the enterprise.

Abstract:The content of iron minerals (alumino goethite and hematite) in the red mud dissolved by the Bayer method reaches more than 60%, which can replace high iron ore as an auxiliary material to prepare sintering clinker and improve the net dissolution rate of alumina. In this paper, based on the theory, the laboratory experiment was carried out to analyze the change of sinter grade, clinker chemical composition, clinker dissolution index and clinker dissolution and sedimentation performance after red mud ore blending, and compared with the index of high iron ore blending mode. The experimental results show that the alumina content and aluminum-silicon ratio (A/S) of the clinker are reduced by using the low-temperature Bayer process red mud to prepare the sintering clinker, but the standard dissolution rates of alumina and sodium oxide are basically the same. The absorbance of the coarse liquid after the clinker dissolution is reduced, and the sedimentation and compression properties of the red mud produced by the clinker dissolution are comparable. Therefore, it is feasible to use low-temperature Bayer red mud to prepare sintering clinker. After adopting red mud ore blending, by adjusting the clinker alkali ratio and calcium ratio, correcting the [F/A] control range, adjusting the fixed carbon content of raw slurry and other measures in the actual production site, the optimization and improvement of the operation index of alumina production by sintering method is achieved, which not only reduces the ore cost of sintering system, but also realizes the reuse of red mud. It is of certain significance to improve the net dissolution rate of alumina in the production of alumina by sintering method of low grade bauxite in China.

Abstract:Hydroxamic acid plays a very important role in improving concentrate grade in bauxite flotation. In this paper, the influencing factors of the synthesis process of benzohydroxamic acid were discussed. The synthesis process of benzohydroxamic acid was optimized by adjusting the proportion of material addition, optimizing the cooling system and prolonging the reaction time. After optimization, the content of benzohydroxamic acid is increased, and the dosage of hydroxylamine hydrochloride is also reduced by about 17 %, which not only reduces the production cost, improves the working environment, but also significantly improves the beneficiation index. Because the raw materials for the synthesis of hydroxylamine hydrochloride are highly toxic, and the synthesis rate is low and the price is high, the feasibility of replacing hydroxylamine hydrochloride with hydroxylamine sulfate was discussed, and the process of synthesizing benzohydroxamic acid from hydroxylamine sulfate was optimized. The results show that the index of benzohydroxamic acid produced by hydroxylamine sulfate meets the standard and meets the needs of bauxite beneficiation. It can replace hydroxylamine hydrochloride to synthesize benzohydroxamic acid, alleviate the product tension and reduce the production cost.

Abstract:The heavy metal contaminated soil in a mining area of Hubei Province was selected. The leaching toxicity and speciation changes of heavy metals Cu, Pb and Zn before and after remediation by blast furnace slag ( BFS ) and its compound material with potassium dihydrogen phosphate ( MKP ) were investigated by passivation experiment and metal speciation analysis experiment. The results showed that the passivation effect of BFS-MKP compound material on soil was better than that of BFS alone. The passivation effect of BFS-MKP compound material on Cu and Pb in soil was better than that of Zn. The passivation efficiency of Cu and Pb reached 86.1% and 88.2%, respectively. In addition, the BFS-MKP compound material can promote the transformation of Cu and Pb with higher activity into more stable forms in the soil. After adding compound materials and curing for 28 days, the proportion of exchangeable Cu and Pb in soil can be reduced from 16.6% and 22.7% to 0.6% and 4.3% respectively, while the proportion of residual Cu and Pb can be increased from 64.3% and 41.7% to 89.3% and 81.9% respectively.

Abstract:In this paper, domestic waste and medical waste after high-temperature cooking treatment in a city were taken as the research objects. By comparing and analyzing the physical and chemical properties, incineration technical indicators, incineration flue gas emission standard limits of the two, and conducting a mixed combustion test of domestic waste and medical waste at a ratio of 1∶50, the feasibility and impact of co-firing medical waste in domestic waste were discussed. The analysis results show that there are some differences in the components and incineration technical standards of domestic waste and medical waste, mainly because the components of domestic waste and medical waste are different, but the requirements of the two in flue gas purification treatment system, slag disposal and thermal energy utilization are basically the same. The contents of SO₂, NO_x, HCl and dioxins in flue gas emissions increased after co-combustion, but they were still controlled within the national standard. Co-firing has no obvious effect on the content of CO and particulate matter in flue gas. The consumption of lime and urea in the flue gas purification system increased after co-firing The above results verify the feasibility of co-combustion medical waste in domestic waste.

Abstract:Biomass pyrolysis and gasification is the key technology of biomass energy utilization. It has great significance to study the pyrolysis and gasification characteristics of straw biomass for the efficient utilization of a large number of biomass straw resources in rural areas of China. In this paper, the typical wheat straw and rice straw in rural areas of China were taken as the research objects. Based on the tube furnace system, a biomass pyrolysis and gasification experimental platform was built to study the pyrolysis and gasification of wheat straw and rice straw in N₂ atmosphere. The law of gas production was analyzed, and the influence mechanism of different pyrolysis temperatures on its pyrolysis gas production was analyzed. The results show that with the increase of pyrolysis temperature, four kinds of gases such as CO, CO, CH₄ and H₂ are produced in the pyrolysis process of straw. The content of CO in syngas is more and more with the increase of temperature, and the second CO yield peak appears in the pyrolysis of wheat straw at high temperature stage. CO mainly comes from cellulose pyrolysis, followed by hemicellulose pyrolysis. The content of CO₂ and CH4 increases first and then decreases with the increase of the temperature, while the content of H₂ continued to increase. This is because CH4 is easily decomposed into H₂ at high temperature, and the broken bond recombination of —CC— and —CH— and the secondary cracking reaction of volatiles further increase the content of H₂.

Abstract:The main supply sources of ammonium sulfate in China are coking grade and caprolactam grade, accounting for 70%-85% of the total supply, and the others are cyanuric acid grade, methyl methacrylate grade, acrylonitrile grade, power plant and various chemical by-products. In order to better understand the current market situation of ammonium sulfate, this paper summarized the current market supply and demand of ammonium sulfate based on a large number of data and literature analysis, and analyzed the problems existing in the ammonium sulfate industry and the market operation trend in the next five years, and put forward some suggestions for the development of the ammonium sulfate industry.