China Nonferrous Metallurgy

Abstract:Aqueous zinc-ion batteries have broad application prospects in the field of large-scale energy storage due to their low cost, high safety and environmental friendliness. Thus, it is of vital importance to develop high-performance cathode materials. In this paper, a simple hydrothermal method was used to prepare (NH₄)₂V₄O₉ cathode materials. The structure and zinc storage performance of these materials synthesized under different pH values were investigated. It is found that the pH value has a significant influence on the crystallinity and phase purity of the material. The specimen obtained at pH=45 demonstrates the highest crystallinity and phase purity, showing the optimal electrochemical properties. Its reversible capacities at current densities of 01, 02, 05, 1, 2 and 5A·g^-1 are 3851, 3388, 2767, 23200, 1995 and 1581mAh·g^-1, respectively. A discharge capacity of 1218mAh·g^-1 is still maintained after 5000 cycles at a high current density of 5A·g^-1 as well as the capacity retention rate of 865%. The results show that the excellent cycling stability and rate capability of pure (NH₄)₂V₄O₉ electrode can benefit from the “pillar” effect of NH⁺₄ between the VO layers and the high pseudo capacitive contribution rate at a large current density.

Abstract:Surfactants play an important role in morphology control during materials synthesis. In order to improve the comprehensive electrochemical performance of the high nickel ternary cathode material LiNi_0.8Co_0.1Mn_0.1O₂ the surfactants were used to control the morphology of the ternary material. Different surfactants were added in the synthesis process of the cathode material precursor LiNi_0.8Co_0.1Mn_0.1 (OH)₂ to control the morphology of ternary materials, and then morphology and electrochemical performance of LiNi_0.8Co_0.1Mn_0.1O₂ the high nickel ternary product material obtained from calcining, were analyzed. The results show that the product materials synthesized by surfactants have more regular morphology and crystal structural stability. The electrochemical test shows that the specific capacity of the first charge can reach 2322, 2481, 2313 and 2161mAh·g ^-1 after adding sodium dodecyl benzene sulfonate, sucrose, cetyltrimethylammonium bromide and polyethylene glycol. Among them, the first discharge specific capacity of cetyltrimethylammonium bromide reaches 1939mAh·g ^-1, and the cyclic performance is good, which indicates that the auxiliary synthesis of surfactants is beneficial to the morphology control and electrochemical performance improvement of materials.

Abstract:Ultra-high nickel cathode material, as one of the development directions of nickel-rich layered oxide cathode materials, is expected to become the next generation of lithium-ion battery cathode material due to its high specific capacity and cost reduction. The ultra-high nickel cathode material has the highest nickel content, which can improve the energy density, but deteriorate the cycle performance and thermal stability. In this paper, the capacity decline mechanism of ultra-high nickel cathode material is briefly analyzed. Combined with the domestic and foreign literature, the modification means such as element doping, surface coating, morphology design and crystal design are summarized. It is pointed out that the current modification means can improve the cycle stability of ultra-high nickel cathode material to a certain extent. However, there are still the problems of mismatch between energy density and structural stability, and how to scale up the industrial production from the laboratory stage. It is necessary to deeply explore the impact mechanism of alternative elements, the doping amount range and its doping process, and combine with a variety of modification methods to solve the problem of mismatch between energy density and structural stability.

Abstract:With the vigorous development of small electronic equipment and new energy vehicle industry, the number of decommissioned lithium-ion batteries has increased year by year. The recycling of waste lithium-ion batteries has become an important strategic direction of the new energy industry. As a major producer and consumer of new energy vehicles in the world, enterprises related to the industrial chain have successively deployed lithium-ion battery recycling in response to the national strategy. Among them,lithium cobaltate is one of the most widely used and successful cathode materials, and its recycling process research and development has attracted the attention of researchers. Combined with the status-quo of lithium cobaltate cathode material industry, this paper analyzes the economic benefits and environmental friendliness of waste lithium cobaltate cathode materials treated by different processes, which can be a reference for the frontier layout of the enterprise.

Abstract:In order to promote the industrial production of red mud, the emission and physicochemical properties of red mud were analyzed in this paper, and the current situation of red mud industrial application in China were summarized.It’s pointed out that the main problems in the industrial application of red mud are lack of corporate responsibility of red mud users, high cost of disposal technology, lack of product standards, poor market recognition, restricted large-scale application, and less cross-sector collaborative utilization. Finally, suggestions were given to promote the comprehensive utilization of red mud:namely, establishing red mud utilization and product standard system, strengthening industry-academic research cooperation to further reduce the cost of red mud disposal, establishing inter-regional solid waste cooperation platform and building demonstration lines for cross-domain collaboration in red mud disposal.

Abstract:As a major alumina producer, China discharges 100 million tons of red mud every year. However, due to the lack of effective methods for large-scale comprehensive utilization of red mud, the cumulative stockpile stock has exceeded 1 billion tons. The Implementation Plan for Accelerating the Comprehensive Utilization of Industrial Resources and the Work Plan for Preventing and Resolving the Safety Risks of Tailings Pond issued in 2022 put forward requirements for the comprehensive utilization of red mud. Large scale comprehensive utilization of red mud is imminent. Based on the previous research work and literature research, this paper systematically summarizes and analyzes the physical and chemical characteristics, production status and current utilization of red mud. Combined with the characteristics of red mud, this paper comprehensively combs the key research directions and existing problems of red mud in the four fields of metallurgy, architecture, environment and fire protection. Some development suggestions have been put forward to provide references for the future resource utilization of red mud.

Abstract:A large amount of red mud is produced in the process of alumina smelting. The high alkalinity of red mud restricts its large-scale consumption and application. In this paper, the alkali removal test of red mud was carried out with waste acid of activated clay. The effects of leaching temperature, leaching time, solid-liquid ratio and stirring speed on the removal rate of sodium oxide from red mud were investigated, and the composition, particle size and phase of red mud before and after acid leaching were analyzed. The following conclusions were drawn: the better conditions for alkali removal of red mud are temperature 55℃, time 2h, solid-liquid ratio 150g/L, stirring speed 260r/min, addition of waste acid of activated clay per unit of red mud 00022mol. Under this condition, the removal rate of sodium oxide in red mud is more than 90%, the content of sodium oxide in red mud after leaching is 046%, and the scale consumption of composite red mud is required; after acid leaching, the red mud has coarsened particle size, smooth surface, reduced voids, disappeared sodium silicon slag phase, and clavicular gypsum crystals are formed when the acid is excessive. The dealkalized red mud can be used to prepare cement, silicon calcium sulfur magnesium fertilizer, soil improver, etc. The process simultaneously treats two kinds of hazardous wastes, namely waste acid of activated clay and red mud, and achieves the goal of treating wastes with wastes.

Abstract:Aiming at the poor separation effect of metal from slag because of TiC in slag in the process of titanomagnetite smelting in electric furnace, a new method of carbothermal pre-reduction-silicothermal reduction melting separation is proposed in this paper. That is in the later stage of the reduction process, silicon was used instead of carbon for reduction reaction to avoid the formation of TiC, and the condition test and product and slag detection analysis were carried out.The condition tests of carbon thermal pre-reduction show that low carbon (-C-=012%~022%) products can be obtained at 1200℃ by controlling reaction time and carbon content (16~19 times of theoretical carbon ratio). The condition tests of siliconthermal reduction smelting show that the yield of V increases with the increase of Si ratio, and the yield of Fe increases with the increase of Si ratio. Under the same Si ratio, the lower the C ratio in the pre-reduction stage, the lower the Fe yield and the higher the V yield. When the Si ratio is increased to 18 Si, the V yield is 7771%~8162% and the Fe yield is 9723%~9989% under different carbon ratios, and the separation effect of metal from slag is good. Slag X-ray diffraction spectrum shows that the main phases in the slag are magnesium aluminum titanate (Mg₄Al₂Ti₉O₂₅) and magnesium aluminum spinel (MgAl₂O₄), without TiC. According to the spectrum and energy spectrum, it is calculated that with the increase of Si ratio, the content of TiO₂ in slag increases, which can be controlled at 2728%~3486% when the ratio of Si is 18. This method uses Si instead of C for deep reduction, which significantly improves the yield of V. The recovered vanadium can make up for the cost caused by silicon consumption, and the potential economic benefits are significant.

Abstract:Regarding MHP obtained from lime milk precipitation, this paper studies the process of MHP acid leaching with sulfuric acid as the leaching agent and neutralization of post-leaching solution by MHP based on its alkaline features. The paper also investigates the impact of the temperature, end point pH and MHP holding time on the leaching behavior of Ni, Co and Mn during acid leaching of MHP. The results show that leaching rates of Ni, Co and Mn in MHP reach 9950%, 9884% and 3858% respectively, with acid leaching performed at a temperature of 85℃, end point pH of 10 and MHP holding time for 3 days. To prevent Co in MHP and Mn in manganese hydroxide from being exposed to the air for a long time and thus oxidized, enhance the leaching rate of Co and Mn and reduce the amount of added reductant, MHP obtained from pressure filtration shall be subjected to acid leaching process after direct slurrying during the industralized production. Meanwhile, this paper studies the impact of the temperature and end point pH on the metal leaching rate during the neutralization of fresh MHP. It is found that Ni, Co and Mn leaching rates don’t change significantly, which reach 995%, 985% and 75% respectively, when the temperature is between 70℃ and 80℃ and the end point pH is 20 to 30. This process can realize efficient leaching of Ni and Co and selective leaching of Mn in MHP, which can provided a reference for nickel laterite project with full-process preparation of nickel sulfate by hydrometallurgical process.

Abstract:Although the scandium content in laterite nickel ore is not high, the scandium yield from by-product in nickel extraction process is much higher than other scandium resources, due to the large processing capacity of laterite nickel ore.In this paper, the typical process flow of nickel-cobalt hydroxide intermediate product ( MHP ) produced by high pressure acid leaching (HPAL) of laterite nickel ore was statistically analyzed, and the influence of parameter adjustment of each key process position on scandium distribution was studied.The results show that the leaching rate of scandium in the process of HPAL is very high, and it can be considered that all of them enter the liquid phase. Scandium is mainly distributed in the first iron and aluminum removal slag, the second iron and aluminum removal slag and MHP products. All of them can be used as raw materials for the extraction of scandium. The distribution ratio of scandium in each phase is related to pH of the process.Reducing the pH of the solution after the first and second iron and aluminum removal is beneficial to the enrichment of scandium in MHP products, but it will lead to the entry of impurity elements such as iron and aluminum into MHP products and increase the cost of subsequent refining treatment. In production, the subsequent negative effects of impurity elements should be quantitatively considered to maximize the economic benefits.

Abstract:Under the background of current energy shortage, carbon peaking and carbon neutralization, bioleaching technology has been widely used in the extraction of various mineral resources due to its advantages of low cost, low pollution, and simple operation. However, due to the slow leaching rate, its practical application has been seriously affected. Therefore, this paper discussed the enhancement effect of the applied electric field on bioleaching, and the effect of the applied electric field on the extracellular electron transfer, cell permeability and community of microbial cells was taken as an example to analyze the mechanism of the enhanced microbial leaching by the applied electric field. Finally, the influence of the applied electric field on the metal dissolution rate, solute and the seepage capacity of microorganisms during the leaching process was analyzed.The methods to improve the bioleaching efficiency from the perspective of electrochemical strengthening were proposed, which can be of reference for future research in this field.

Abstract:In this work, the green and ammonium-free leaching agents for ion-absorbed rare earth ore in southern China were explored. The effects of leaching agent concentration, liquid-solid ratio and pH value on rare earth leaching by ammonium sulfate, magnesium sulfate and SAK (a complex salt of aluminum and potassium) were investigated, and the leaching effects were compared among these three leaching agents. The results showed that the leaching efficiency of rare earth and impurities including Fe, Si, Al and Ca increased and then became flat with the increase of the leaching agent concentration or liquid-solid ratio, and decreased with the increase of the pH value. Under the leaching conditions (leaching agent concentration of 2%, liquid-solid ratio of 06∶1, pH value of 50 for ammonium sulfate and magnesium sulfate, and pH value of 30 for SAK). The leaching efficiency of impurity Al followed the order of ammonium sulfate ＞ magnesium sulfate ＞ SAK, and the leaching efficiency of Fe, Si, and Ca was in the order of SAK ＞ ammonium sulfate ＞ magnesium sulfate. At the same time, the leaching velocity of ammonium sulfate and SAK were significantly higher than that of magnesium sulfate, the volume of washing water dropped sharply comparing with magnesium sulfate. And SAK was determined as the new kind of leaching agent based on environmental protection and leaching effect. The optimal leaching behavior with SAK can be obtained at the leaching agent concentration of 2%, liquid-solid ratio of 06∶1, as well as pH value of 30, with corresponding leaching efficiency of RE and impurity Al of 9693% and 1378%, respectively.

Abstract:In this paper, the standard -k-ε- turbulence model and VOF model are selected to study the scale-up effect of bottom-blown furnace under four different scale-up criteria by numerical simulation. The scale-up criteria are power consumption per unit volume (P/V), modified Froude number (Fr′), Reynolds number (Re) and flow per unit volume (Q/V). The results show that: the distribution characteristics of velocity field in bottom-blown furnace are basically unchanged under different scale-up criteria; The mixing time of different monitoring points is also different, but it is reduced by the influence of measuring position at a larger flow rate; scale-up of equal

Abstract:In this study, hydrochloric acid and thiourea were used to separate palladium from palladium adsorbent. Based on thermodynamic analysis of the reaction, the chemical morphology and distribution characteristics of palladium products were explored, and the mechanism of desorption process was revealed. Meanwhile, the effects of time, concentration of hydrochloric acid, concentration of thiourea and volume of desorption agent on the separation effect and the effects of regeneration times on the regeneration performance of the adsorbent were investigated. The results show that the palladium-containing products exist as PdCl₃[SC(NH₂)₂]- after ion exchange with Cl^- and thioureas in the palladium-loaded adsorbent. The quasi-second-order kinetic model is the best model for desorption kinetics. Under the conditions that the palladium-loaded adsorbent of 10mg, temperature of 25℃, desorption time of 60min, desorption agent (10mol·L ^-1 hydrochloric acid and 06mol·L ^-1 thiourea) of 20mL, the maximum desorption rate of palladium was 9626%. The results showed that the optimal regeneration times of adsorbent was 4.

Abstract:In order to explore the characteristics and influence of the flow field of autoclave in the pressure leaching process, the operating pressure is set at 10MPa and standard -k-ε- turbulence model and the multiple reference frame method are adopted to numerically simulate the fluid dynamics of the pressure leaching process based on CFD method. The influence of different impeller heights and blade inclination angles on the flow field and flow pattern and the relationship between stirring speed and flow field distribution, turbulent kinetic energy and turbulent dissipation rate are analyzed. The reliability of the model is verified through PIV test. The results show that the flow pattern has a double-loop structure when using the paddle agitator, the height of the agitator distance from the bottom of the autoclave has a great influence on the flow pattern and vortex position. The stirring power decreases with the increase of blade inclination angle, and the main flow in the autoclave transfers to the axial flow, the circulation effect in the autoclave is better when the blade inclination angle is 45°. When the speed is increased, the stirring power rises exponentially, when the stirring speed is 600r/min, the range of the dead zone is the smallest and then further increasing the stirring speed cannot effectively improve the circulating mixing capacity in the autoclave. The turbulent kinetic energy of the flow field rises with the increase of the stirring speed, and peaks in the blade region and rapidly declines in the upper part of the autoclave. The turbulent dissipation is mainly concentrated in the blade vortex region and grows exponentially with the increase of the stirring speed.

Abstract:Anode effect is the most frequent fault in the aluminum electrolysis production, and accurate prediction of the anode effect can reduce energy consumption and reduce accidents. Starting from deep learning, this paper proposes a prediction model based on stacked noise reduction autoencoder and long short term memory network. The stacked noise reduction autoencoder is used to find key fault feature information, and meanwhile the long short term memory network is used to realize fault diagnosis. Finally, the historical production data of an aluminum factory is collected to verify the performance of the model. The experimental results show that the prediction accuracy and -F-1 score of the model are 9756% and 09686, respectively. This paper makes a comparative analysis of the BP neural network, generalized regression neural network, LSTM and SDAE-RF. The experimental results show that the SDAE-LSTM model constructed in this paper has the best performance with more accurate prediction of the anode effect, which has important guiding significance for the actual production of aluminum electrolysis.

Abstract:Based on the principle of compound structure, the core-shell structure of ZSM-5 zeolite and CeO₂ catalyst was constructed, and the effect of core-shell structure on catalytic performance, especially H₂O and SO₂ tolerance and hydrothermal stability was explored.It was found that Cu/(ZSM-5@CeO₂) core-shell catalyst exhibited superior NH₃-SCR performance and good SO₂ tolerance. Through a series of characterization analysis, it show that the synergistic action of Ce and Cu in the core-shell catalyst can improve the denitration performance of the catalyst, and ZSM-5 zeolite can provide a large number of acidic sites, enabling the adsorption and conversion of CeO₂ shell can not only stabilize the existence of copper ions and reduce the formation of CuO_x aggregates, but also produce more oxygen vacancy and adsorb oxygen species, which improved the catalytic activity at low temperature. In addition, the SO₂ tolerance test also proves that CeO₂ shell can effectively inhibit the formation of nitrate and ammonium sulfate, showing high SO₂ tolerance.Therefore, the construction of core-shell catalyst is of great significance to promote the practical application of NO_x -removal catalyst.

Abstract:Bentonite is oftern used for adsorption and solidification of radionuclide uranium, but the silica structure of natural bentonite has a strong hydrophilicity, leading to a poor adsorption effect on pollutants. In this paper, DTAB organic modified bentonite was prepared by co-precipitation method with DTAB as a modifier and bentonite as raw material.And the effects of pH value,dosage of modified bentonite, temperature,adsorption time and initial concentration of U(VI) solution on the adsorption of U(VI) contained in wastewater by DTAB organic modified bentonite were investigated. It is concluded that the adsorption effect of modified bentonite is greatly improved with a wider pore and spacing as well as a large number of hydrophobic functional groups. The experimental results show that the best adsorption effect is achieved at pH 40, the modified bentonite dosage of 01g (2g/L), the temperature of 33315K, the initial concentration of U(VI)-containing wastewateras 10mg/L and the adsorption time of 240min, and the U(VI) removal rate could reach 9957% under such condition. The kinetics-equation fitting shows that the adsorption model of the material is in accordance with the quasi-secondary kinetic model, indicating that the adsorption is dominated by chemisorption. The isothermal adsorption model fitting shows that the adsorption model is more consistent with the Langmuir isothermal adsorption model, and the fitted maximum adsorption amount is 3445mg/g.