A kinetic study on the mechanisms of metal leaching from the top surface layer of copper aluminates and copper ferrites

Copper Mineral Leaching Mathematical Models—A Review

Mineral leaching is the key unit operation in metallurgical processes and corresponds to the dissolution of metals. The study of leaching is carried out in many areas, such as geology, agriculture and metallurgy. This paper provides an introduction to the theoretical background regarding the mathematical modelling of the leaching process of copper minerals, establishing an overall picture of the scientific literature on technological developments and the generation of representative mathematical and theoretical models, and indicating the challenges and potential contributions of comprehensive models representing the dynamics of copper mineral leaching.

Assessment of geochemical modeling applications and research hot spots-a year in review

Geochemical modeling has been employed in several fields of science and engineering in recent years. This review seeks to provide an overview of case studies that applied geochemical modeling in the 2019 year, which includes over 250 articles. This review is intended to inform new users on the possibilities that geochemical modeling brings, while also informing existing and past users on its latest developments. The survey of studies was conducted with an emphasis on the modeling techniques, the objective of studies, the prevalent simulated variables and the use of specific software packages. The analysis showed that geochemical modeling is still predominantly employed in experimental projects and in the form of equilibrium modeling. PHREEQC and Visual MINTEQ were recognized as the most popular software packages for simulating a wide range of processes, using equilibrium or other geochemical modeling forms. The study of fluid-rock interactions and pollution and remediation processes can be regarded as the principal geochemical modeling objectives, constituting 37% and 36% of the reviewed studies, respectively. Focusing on fluid-rock interactions, hydrogeochemical processes, carbon capture and storage and enhanced oil recovery have been the main topics examined with geochemical modeling. Assessments of the toxicity of metals in terms of leachate and mobilization, as well as their removal from soil and water systems, have been major topics investigated with the aid of geochemical modeling in terms of pollution and remediation research. It was found that the scholars benefit from geochemical modeling in their research both as a main technique and as an accessory tool. Saturation index, elemental concentration and speciation, mineral mass and composition and pH were among the most common variables modeled in reviewed studies. Geochemical modeling has gained a wider user base in recent years, and many research groups have used it in consecutive studies to deepen knowledge. However, much potential for further dissemination still remains.

Develop spinel structure and quantify phase transformation for nickel stabilization in electroplating sludge

Nickel-laden electroplating sludge (Ni sludge) has always been a critical concern due to its potential hazards to the environment. This study proposed a strategy to stabilize nickel (Ni) via phase transformation into stable crystal structures through ceramic sintering. The Ni sludge was collected, and then fired with two ceramic precursors (α-Fe₂O₃ and γ-Al₂O₃) within a temperature range of 700-1400 °C for 5 h. After sintering scheme, phase identification was performed on the products, showing the NiFe₂O₄ and NiAl₂O₄ spinels as predominant Ni-hosting phases respectively in α-Fe₂O₃ and γ-Al₂O₃ series. Then, the Rietveld refinement was applied to quantify weight fractions of all phases (including crystal and amorphous phases), and the quantification results showed that the weight fractions of NiFe₂O₄ or NiAl₂O₄ spinels can reach around 87.7% and 83.1%, respectively in 1200 °C sintered products of both series. The transformation ratio (TR) of Ni was calculated as 99.9% and 99.7% accordingly, showing almost complete incorporation of Ni into the spinel structures. With a prolonged leaching procedure, the Ni stabilization effect after sintering was evaluated. The Ni leachability was dramatically decreased with the development of spinel structure under sintering processes, and the Ni leached ratio from the sintered products can reach lower than 0.06% even after 20-d prolonged leaching. Through this study, a promising and quantitative method was proposed for controllable Ni stabilization of the hazardous industrial sludge via developing spinel structures in the sintered products, which may provide a feasible strategy for the treatment and beneficial utilization of heavy metal-laden solid wastes.