Kudret Tahsin Perek

Comminution is the most energy-intensive stage of mineral processing and plays a decisive role in plant performance, equipment selection, and operating costs. Consequently, the preliminary design of crushing circuits requires reliable engineering calculations and systematic evaluation of ore characteristics and design criteria. This paper presents the modernization and verification of the C&G Circuit Designer, a computer-aided engineering application developed to generate preliminary crushing circuits based on established comminution design principles. The application integrates particle size distribution analysis, distribution coefficient estimation, equipment selection, reduction ratio evaluation, and stage-wise mass balance calculations within a unified engineering framework, using the Gaudin–Schuhmann particle size distribution model. Verification against an independently prepared reference design showed close agreement in the predicted distribution coefficient, generated crushing circuit, and stage-wise mass balance, confirming the correct implementation of the stated equations; broader validation against industrial plant data or established commercial simulators is identified as necessary future work. Unlike conventional comminution software, which generally requires engineers to define a process flowsheet before analysis, the developed application generates preliminary crushing circuits directly from ore properties and engineering design criteria, providing a consistent basis for subsequent engineering evaluation and detailed plant design. The modular software architecture supports future expansion through additional equipment databases, closed-circuit finishing stages, and optimization modules while preserving the established design methodology.

This study presents an efficient and environmentally friendly approach for lithium recovery from biotite-rich wastes generated during nepheline syenite processing by combining mechanical activation with sulfuric acid leaching. Mechanical activation was applied as a pretreatment to enhance extraction of lithium and minimize acid consumption. After optimizing the process parameters, lithium extraction efficiencies of up to approximately 91% were achieved. The results clearly demonstrated that mechanical activation substantially reduced sulfuric acid demand up to 85.7%, allowing lithium recoveries comparable to those obtained with 1.75 mol L⁻¹ acid in direct leaching to be achieved using only 0.25 mol L⁻¹ acid. Structural and morphological analyses (XRD, SEM, FTIR, and particle size analysis) confirmed progressive amorphization of biotite, accompanied by the weakening of -OH and siloxane (Si-O-Si) bonds. Needle-like and layered biotite particles transformed into rounded and agglomerated morphologies with increasing activation time, leading to an initial decrease in particle size followed by agglomeration-dominated growth. Although crystallinity continuously decreased with activation time, partially reversible behavior was observed beyond 120 min. Overall, mechanical activation enabled a low-acid, and effective process design for lithium recovery from biotite-rich nepheline syenite wastes.

The hydrometallurgical route of zinc hydroxide and synthesis of nanocrystalline ZnO is a particularly attractive method to recover oxidized lead and zinc from lead-zinc flotation tailings. In Turkey, lead-zinc complex/mixed ores along with high iron content are not suitable for conventional mineral processing methods and need hydrometallurgical treatments. Therefore, the control of iron during zinc processes is really important. In this study, hydrometallurgical process route for zinc recovery from Pb-Zn flotation tailings was investigated by considering the effects of H2SO4 concentration, leaching and roasting temperatures on the zinc dissolution considering the Eh-pH variations. The iron and zinc products were also individually examined by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) images in order to compare before and after leaching, precipitation and roasting steps. 83.1% Zn and 91.6% Cd leaching efficiencies were obtained from Pb-Zn flotation tailing particles with the size range of 50-110 nm from AFM image cross-sections, while lead and iron were not dissolved. Elemental sulfur started to form and produce a layer around the particles or a partially agglomerated particle in the size of 170 nm during the sulphuric acid leaching. However, majority of the particles was determined to be less than 20 microns, and AFM images showed that the size reduction between the leached and unleached particles was over 50%. Selective precipitations of iron and zinc in the form of hydroxide were performed in high recovery efficiencies of 90.1% and 99%, respectively. After the heat treatment, nanocrystalline zincite clusters of 96.6% purity were produced in the ZnO mineral form and nearly 13 nm in size. Zinc can be successfully recovered and a flotation tailings ore can be a good candidate for the production of high technology needs of nanocrystalline ZnO nanoparticles.

The effect of mechanical activation on metal dissolutions by pressure leaching of massive rich copper ore taken from Küre copper ore deposit (Turkey) was investigated. The dissolution efficiencies of sulfide minerals are significantly improved by ultrafine grinding, also known as mechanical activation. This grinding results in decrease of particle size and an increase in crystal distortion of sulfide minerals. Leaching efficiencies of copper, cobalt, and Zinc increased from 45.2%, 25.9%, and 87.7% to 98%, 85%, and 97%, respectively, after 3-h mechanical activation. At the end of the activation, leaching was carried out at a temperature of 110°C, 10-bar oxygen partial pressure, and 150-g/L solid concentration without addition of acid. This study has also indicated that mechanical activation involving fine milling as a pretreatment is not only effective on copper minerals dissolution but also on the dissolution of other associated minerals, such as cobalt and zinc sulfides.

A combination of semicoking followed by a permanent roll magnetic separator (PERMROLL) has been used for the upgrading of a Turkish low-rank lignitic coal. The lignite samples were subjected to a low temperature carbonization process at 600°C and then upgraded by the PERMROLL. Under optimum conditions, carbonization of lignite particles in −9 + 0.5 mm size range which contained 12.18 wt.% ash and 3.38 wt.% total sulfur produced a product containing 25.90 wt.% ash and 3.19 wt.% total sulfur all reported on a dry basis. Dry magnetic separation employing the PERMROLL upgraded this product to 11.20 wt.% ash and 1.40 wt.% total sulfur with a recovery of 31.52 wt.% based on feed to the carbonization process. The mechanism of desulfurization is discussed on the basis of the presence of iron in the coal that complexes with sulfur to form a magnetic product upon semicoking and its subsequent removal by magnetic separation.