Leaching of a low-grade chalcocite-covellite ore containing iron in sulphuric acid: The influence of pH and particle size on the kinetics of copper leaching

A new improved method is proposed for the leaching and extraction of niobium from a low-grade refractory niobium–tantalum ore.The ore was roasted and decomposed with concenrated H2SO4 then leached with dilute sulfuric acid. The effects of various factors, such as roasting temperature and time, acid to ore mass ratios,as well as particle size, on the dissolution kinetics of niobium were comprehensively investigated. The optimal conditions were particle size-38μm, roasting temperature 300°C,reacting time 2h and acid to ore mass ratio 1:1. The roasting residue reacted for 2 h with sulfuric acid in the ore/acid weight ratio of 3:1 at 90°C, the niobium was recoveried as high as 90.3%.

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The Effects of Sulphuric Acid and Sodium Chloride Agglomeration and Curing on Chalcopyrite Leaching

Metals ◽

10.3390/met11060873 ◽

2021 ◽

Vol 11 (6) ◽

pp. 873

Author(s):

Víctor Quezada ◽

Antoni Roca ◽

Oscar Benavente ◽

Montserrat Cruells ◽

Evelyn Melo

Keyword(s):

Sodium Chloride ◽

Sulphuric Acid ◽

Copper Extraction ◽

Curing Time ◽

X Ray Diffraction ◽

Sulphide Ores ◽

Reflected Light ◽

Copper Leaching ◽

Kinetics Of ◽

Leaching Efficiency

An option to improve the leaching efficiency of chalcopyrite is pretreatment prior to leaching. Pretreatment variables, such as the curing time and the addition of chloride, can increase the kinetics of copper extraction, particularly for sulphide ores. However, there has been little research on the topic. The reactions that govern this phenomenon have not been clearly identified. In this study, the effects of sulphuric acid and sodium chloride agglomeration and curing on chalcopyrite leaching were evaluated at various temperatures: 25, 50, 70, and 90 °C. The pretreated ore and leach residues were characterised by X-ray diffraction, scanning electron microscopy, and reflected light microscopy. Under the conditions of 15 kg/t of H2SO4, 25 kg/t of NaCl, and 15 days of curing time (as pretreatment), the following products were identified: CuSO4, NaFe3(SO4)2(OH)6, Cu2Cl(OH), and S0. Increasing the curing time and leaching temperature increased copper leaching. The copper extraction was 94% when leaching at 90 °C after pretreatment with 50 g/L of Cl- and 0.2 M of H2SO4. Elemental sulphur, jarosite, and copper polysulphide (CuS2) were detected in the leaching residues.

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Influence of pH on the dissolution kinetics of iron in sulphuric acid solutions

Hydrometallurgy ◽

10.1016/0304-386x(96)00019-9 ◽

1996 ◽

Vol 43 (1-3) ◽

pp. 79-93 ◽

Cited By ~ 9

Author(s):

Milovan Vuković

Keyword(s):

Sulphuric Acid ◽

Dissolution Kinetics ◽

Acid Solutions ◽

Influence Of Ph ◽

Kinetics Of

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Effect of particle size distribution on the kinetics of solid phase-gas reactions

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19751119 ◽

1975 ◽

Vol 40 (4) ◽

pp. 1119-1125 ◽

Cited By ~ 2

Author(s):

J. Skřivánek ◽

J. Šubrt

Keyword(s):

Particle Size ◽

Particle Size Distribution ◽

Size Distribution ◽

Solid Phase ◽

Effect Of Particle Size ◽

Gas Reactions ◽

Kinetics Of

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Reduction Mechanism of Fine Hematite Ore Particles in Suspension

Metallurgical and Materials Transactions B ◽

10.1007/s11663-021-02173-y ◽

2021 ◽

Author(s):

Zhiyuan Chen ◽

Christiaan Zeilstra ◽

Jan van der Stel ◽

Jilt Sietsma ◽

Yongxiang Yang

Keyword(s):

Particle Size ◽

Temperature Drop ◽

Reduction Rate ◽

Reduction Process ◽

Reciprocal Relationship ◽

Drop Tube ◽

Surface Nucleation ◽

Order Of Magnitude ◽

Relationship Of ◽

Kinetics Of

AbstractIn order to understand the pre-reduction behaviour of fine hematite particles in the HIsarna process, change of morphology, phase and crystallography during the reduction were investigated in the high temperature drop tube furnace. Polycrystalline magnetite shell formed within 200 ms during the reduction. The grain size of the magnetite is in the order of magnitude of 10 µm. Lath magnetite was observed in the partly reduced samples. The grain boundary of magnetite was reduced to molten FeO firstly, and then the particle turned to be a droplet. The Johnson-Mehl-Avrami-Kolmogorov model is proposed to describe the kinetics of the reduction process. Both bulk and surface nucleation occurred during the reduction, which leads to the effect of size on the reduction rate in the nucleation and growth process. As a result, the reduction rate constant of hematite particles increases with the increasing particle size until 85 µm. It then decreases with a reciprocal relationship of the particle size above 85 µm.

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Feasibility of fly ash as fluxing agent in mid- and low-grade phosphate rock carbothermal reduction and its reaction kinetics

Green Processing and Synthesis ◽

10.1515/gps-2021-0008 ◽

2021 ◽

Vol 10 (1) ◽

pp. 157-168

Author(s):

Biwei Luo ◽

Pengfei Li ◽

Yan Li ◽

Jun Ji ◽

Dongsheng He ◽

...

Keyword(s):

Particle Size ◽

Fly Ash ◽

Reaction Time ◽

Carbothermal Reduction ◽

Industrial Waste ◽

Phosphate Rock ◽

Molar Ratio ◽

Low Grade ◽

Carbon Excess ◽

Fluxing Agent

Abstract The feasibility of industrial waste fly ash as an alternative fluxing agent for silica in carbothermal reduction of medium-low-grade phosphate ore was studied in this paper. With a series of single-factor experiments, the reduction rate of phosphate rock under different reaction temperature, reaction time, particle size, carbon excess coefficient, and silicon–calcium molar ratio was investigated with silica and fly ash as fluxing agents. Higher reduction rates were obtained with fly ash fluxing instead of silica. The optimal conditions were derived as: reaction temperature 1,300°C, reaction time 75 min, particle size 48–75 µm, carbon excess coefficient 1.2, and silicon–calcium molar ratio 1.2. The optimized process condition was verified with other two different phosphate rocks and it was proved universally. The apparent kinetics analyses demonstrated that the activation energy of fly ash fluxing is reduced by 31.57 kJ/mol as compared with that of silica. The mechanism of better fluxing effect by fly ash may be ascribed to the fact that the products formed within fly ash increase the amount of liquid phase in the reaction system and promote reduction reaction. Preliminary feasibility about the recycling of industrial waste fly ash in thermal phosphoric acid industry was elucidated in the paper.

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