In this paper, CaCO₃ waste marble dust (WMD) has been utilized in the production of concrete. Raw materials (Cement, Sand, WMD and Crush) were collected from Peshawar, Khyber Pakhtunkhwa, Pakistan. Concrete cubes were molded in the laboratory and investigated by XRD. Effect of WMD addition to the concrete was studied. It was reported that 10% addition of WMD as cement replacement showed enhanced performance of the compressive strength as compared to sand replaced WMD blended concrete. Increment in WMD contents beyond 10% resulted in significant decrement of compressive strength. Substituting WMD with cement resulted in a decrement of 29.76%, while with sand, the decrement was 6.09%. Concrete made with cement replaced WMD showed the lowest water absorption rate over 7 days curing as compared to sand replaced (intermediate water absorption) and clean concrete (highest water absorption) samples. Graphical Abstract

Manganese is one of the most difficult elements to be recovered from its respective solutions, due to its high solubility in both acid and neutral conditions. However, metal carbonate precipitation as manganese carbonate can be an effective way for its recovery. In this study, manganese carbonate (MnCO₃) was precipitated by mixing an aqueous solution of manganese sulfate (MnSO₄ containing 85% Mn²⁺) and sodium carbonate (Na₂CO₃) in different proportions. The maximum (∼72%) manganese was precipitated as MnCO₃ at a pH value of 3 for 5 g Na₂CO₃ at 80 °C and 40-min reaction duration. X-ray diffraction of precipitated sample confirmed the formation of single-phase rhodochrosite (MnCO₃). The observed microstructure comprised coarse grains composed of 15.69 wt.% C, 41.78 wt.% O, and 30.8 wt.% Mn along with Na and S as minor impurities. FTIR confirmed the presence of the characteristic MnCO₃ band at 724 cm⁻¹ corresponding to the C–O (CO₃^2–) bond. The kinetic study of the process indicated that the reaction process followed the first-order kinetics. The reaction rate constants were observed to gradually increase with increasing reaction temperature, and the apparent activation energy was calculated to be 27.338 kJ.mol⁻¹ demonstrating the existence of energy barrier between the reactants and products. A spontaneous and an endothermic nature of chemical reaction has been revealed by the thermodynamic parameters of activation (ΔH^#, ΔS^#, and ΔG^#), accompanied by the entropical changes at solid solution interface during precipitation.

To know about the nature of gangue associated with the ores, characterization has become an integral part in mineral processing and beneficiation, therefore, the as-mined iron ore collected from Karak region of KP has been characterized for its phase, microstructure and chemical composition via XRD, SEM and EDS respectively. Beneficiation of the iron ore has been carried out by shaking table and magnetic separator. XRD analysis confirmed the presence of iron oxide (Fe203) as the major phase along with quartz (Si02) as the minor phase. Finely grinded iron ore powder of 100 (149 µm) and 200 (74 µm) mesh sizes were passed via shaking table and magnetic separator subsequently. The iron ore was successfully upgraded from 28.27 wt.% to 36.51 wt.% at 100 mesh and 38.70 wt.% at 200 mesh via shaking table, thus achieving a maximum of 10% upgraded iron ore. The magnetic separator did not become so effective due to non- magnetic nature of hematite.

In medical and nuclear plants as well as industrial plants, radiation shielding materials are necessary and concrete composites are popular because they are structurally stable and economically viable. In this paper, the attenuation characteristics of barite-based concrete composites using gamma-rays were experimentally measured and compared with theoretical values. Five concrete samples with the thickness 1–5 cm, using 32.4% barite (BaSO₄) as high-density aggregate, were prepared and irradiated with 1.25 MeV gamma photons of a ⁶⁰Co source. The radiation sent through the ionization chamber was measured with the help of an ionization chamber-electrometer system and linear attenuation coefficient (µ) and mass attenuation coefficient (µ/ρ) were calculated. The experiment results indicated that µ depended on sample thickness and density depending on small differences of compaction, and µ/ρ was relatively constant across all samples. The experimental mass attenuation coefficients were found to be 0.0533–0.0548 cm²/g with high agreement to the theoretical values in the NIST XCOM database with the mean deviation of 0.67% and RMSE of 1.16. The half-value and tenth-value layers (HVL and TVL) were 4.32510 cm and 14.341695 cm respectively, which represented successful gamma attenuation. The optimized specimen was characterized mechanically and gave a compressive strength of 19.58 MPa and a Young modulus of 43.5 Gpa which showed sufficient structural performance in shielding. These findings prove barite addition as a successful technique in improving gamma attenuation and still achieving acceptable mechanical properties. These results are experimentally proven to give the use of barite-based concrete as viable shielding media to regulated radiation atmosphere.