Efficient improvement for dissociation behavior and thermal decomposition of manganese ore by microwave calcination

Li, Kangqiang; Chen, Jin; Peng, Jinhui; Omran, Mamdouh; Chen, Guo

doi:10.1016/j.jclepro.2020.121074

Cited by 44 publications

(14 citation statements)

References 34 publications

(25 reference statements)

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“…The temperature reached a higher value in the same time period, which denoted that the greater the microwave power, the faster the material heating rate will be. Under certain conditions, increasing the microwave output power means the enhancement in the electric field intensity [46][47][48]. As the electric field intensity (E) increases, the microwave can penetrate into the roasting material better and evenly, increasing the microwave penetration of zinc-containing residues and promoting the absorption of microwave power, further to make the material heat up quickly Therefore, appropriately increasing the microwave power can shorten the heating time and increase the apparent average heating rate of zinc-containing residues.…”

Section: Analysis Of Microwave Heating Characteristicsmentioning

confidence: 99%

Investigations on the Thermodynamics Characteristics, Thermal and Dielectric Properties of Calcium-Activated Zinc-Containing Metallurgical Residues

Zheng

Gao

et al. 2022

Materials

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An activate pretreatment of zinc-containing metallurgical residues were proposed by adding CaO and introducing microwave heating approach into the CaO activation pretreatment process to realize the conversion of refractory ore phases into pre-treated ore phase. Thermodynamic characteristics analysis indicated that adding CaO can realize the conversion of refractory ore phases, with the same effect as the carbon additives. Thermal conductivity properties analysis denoted that the thermal conductivity properties of ZnS and ZnFe2O4 were relatively poor. Meanwhile, the thermal conductivity properties of the residues sample added with 25% CaO were significantly superior to the residues added with other CaO contents, with the maximum specific heat value of 1.348 J/g·K at 350 °C. Dielectric properties analysis highlighted that adding CaO with the dielectric constant properties significantly higher than that of other substances can enhance the microwave absorption capacity of zinc-containing residues. The decrease in dielectric loss and loss tangent value with the increase of temperature and the residues having large microwave penetration depth guaranteed to obtain better uniformity of microwave heating. Furthermore, adding 25% CaO promoted the microwave penetration depth of the residues sample increased in the range of 300–500 °C. This work can lay a theoretical research foundation for solving the key difficulty for efficient Zn recovery from complex zinc-containing metallurgical residues.

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Section: Analysis Of Microwave Heating Characteristicsmentioning

confidence: 99%

Investigations on the Thermodynamics Characteristics, Thermal and Dielectric Properties of Calcium-Activated Zinc-Containing Metallurgical Residues

Zheng

Gao

et al. 2022

Materials

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“…During the microwave activation pretreatment process, the microwave-absorbing properties of useful minerals and gangues present huge differences, leading to the uneven heat distribution in this multi-element and multi-phase complex ore system. The unique selective heating mode of microwave generates thermal stress between useful minerals and gangues, which causes the mineral inclusion particles to crack, strengthens the dissociation of useful minerals, achieving the dissociation effect that is difficult to achieve by conventional methods [43,44]. Meanwhile, the increased reaction area at the interface of useful minerals and accelerated diffusion efficiency also accompanies with the generation of crack, further contributing to the enhanced leaching of zinc from ZMR.…”

Section: Sem Characterisationmentioning

confidence: 99%

“…By contrast, under microwave activation pretreatment, Ca(OH) 2 phase in raw ZMR material was decomposed completely at 400 • C, and CaCO 3 phase was formed at 300 • C. The findings denoted that microwave heating can shorten the process temperature compared with conventional heating, further reducing the production cost and energy consumption of the secondary zinc resource recovery industry. The excellent process advantage demonstrated by microwave heating is assigned to that microwave heating can realise selective heating based on the difference in the dielectric loss of various minerals, and the rapid dissociation and temperature increase in valuable minerals and gangue are achieved due to the complex compositions of ZMR under the action of microwave[44]. Therefore, the complete transformation temperature of mineral phases under microwave activation pretreatment is further reduced compared with the conventional pretreatment.Figure6presents the XRD patterns of the microwave-activated ZMR sample at 400 • C and the leaching residue.…”

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confidence: 99%

Enhanced Leaching of Zinc from Zinc-Containing Metallurgical Residues via Microwave Calcium Activation Pretreatment

Zheng

Gao

et al. 2021

Metals

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Given the shortage of zinc resource, the low utilisation efficiency of secondary zinc resource, and the crucial problem that the synchronous dissolution of zinc from different mineral phases, an activation pretreatment method merged with calcium activation and microwave heating approach was proposed to enhance the zinc leaching from complex encapsulated zinc-containing metallurgical residues (ZMR). Results indicated that under the optimal pretreatment conditions, including microwave activation temperature of 400 °C, CaO addition of 25% and activation time of 20 min, the zinc leaching rate reached 91.67%, which was 3.9% higher than that by conventional roasting pretreatment. Meanwhile, microwave heating presents excellent treatment effects, manifested by the zinc leaching rates, all exceeding that of conventional roasting under the same conditions, while the process temperature is decreased by 200 °C. In addition, XRD and SEM-EDS analysis denoted that microwave calcification pretreatment can effectively promote the transformation of the refractory zinc minerals like Zn2SiO4 and ZnFe2O4 into the easily leachable zinc oxides. The distinctive selective heating characteristics of microwave heating strengthened the dissociation of mineral inclusion, and the generated cracks increased the interfacial reaction area and further enhancing the leaching reaction of zinc from ZMR.

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“…Microwaves generate molecular movement through the migration of ionic species and the rotation of dipolar species. Microwave heating of material directly depends on the relationship between the dielectric loss and the dielectric constant, also known as the dissipation factor [9][10][11] . Haque et al 9 reported an extensive review on the application of microwave energy in mineral treatment processes, which observed that a thermal expansion of the target mineral would occur with specific heating, resulting in the formation of cracks that will allow a better degree of reduction of the ore during heating.…”

Section: Introductionmentioning

confidence: 99%

Analysis of the Carbothermic Reduction of Iron Ore-Coke Composite Mixtures by Microwave Heating

et al. 2021

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In recent decades, microwave energy has been successfully experimented for mining and metallurgy processes and is considered a promising new method for ironmaking. In this context, in the present work, self-reducing mixtures composed of fines of iron ore and coke were prepared, intending to evaluate the degree of reduction of iron ore using microwave energy, applying different contents of coke, levels of power, and reaction times. For this, the degree of reduction was assessed as a function of these variables. Additionally, the reduction kinetics was investigated using chemical and diffusional models, and the microstructure of the samples was evaluated using scanning electron microscopy (SEM). The highest degree of reduction obtained after the experiments was greater than 60% and a statistical investigation showed that the reaction time is the factor with the greatest influence on these results, followed by microwave power and coke content. The investigation of the reaction kinetics showed that the process is chemically controlled, depending on the gasification steps governed by the Boudouard reaction. The images obtained by SEM led to the conclusion that the temperature inside the sample reached 1200°C. Pig iron was found both in the form of whiskers and in the form of metallic droplets.

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Efficient improvement for dissociation behavior and thermal decomposition of manganese ore by microwave calcination

Cited by 44 publications

References 34 publications

Investigations on the Thermodynamics Characteristics, Thermal and Dielectric Properties of Calcium-Activated Zinc-Containing Metallurgical Residues

Investigations on the Thermodynamics Characteristics, Thermal and Dielectric Properties of Calcium-Activated Zinc-Containing Metallurgical Residues

Enhanced Leaching of Zinc from Zinc-Containing Metallurgical Residues via Microwave Calcium Activation Pretreatment

Analysis of the Carbothermic Reduction of Iron Ore-Coke Composite Mixtures by Microwave Heating

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