Processes

Molecular dynamics simulations are employed to investigate the displacement behavior of shale oil by the CO₂/H₂O/N₂ multicomponent thermofluid in α-SiO₂ slit nanopores under various temperature and pressure conditions. The results demonstrate that increasing pressure effectively promotes crude oil displacement, and this promoting effect exhibits a pronounced pore-scale dependence: at 413 K, as pressure increases from 10 to 40 MPa, the displacement amounts in 4–10 nm pores rise from 1.65–1.81 mmol/g to 1.87–2.08 mmol/g, with larger pores showing more pronounced pressure-induced gains. Increasing temperature continuously enhances displacement, but the degree of promotion shows a non-monotonic dependence on pore width: at 20 MPa, as temperature increases from 393 to 513 K, the displacement amounts in 4–10 nm pores increase by 14.3–19.5%, with the 4 nm pore exhibiting the largest relative gain. Under identical conditions, displacement generally increases with pore width, indicating that pore width is a key structural factor governing displacement performance under nanoconfinement. Specifically, with decreasing pore width, fluid molecules experience stronger spatial constraints from mineral walls and reduced migration space, which amplifies the restrictions imposed by oil–mineral interfacial interactions on crude oil migration. In contrast, larger pores provide sufficient migration space for the multicomponent thermofluid, effectively mitigating the detrimental effects of nanoconfinement. Together, pressure, temperature, and pore width govern the displacement behavior of the multicomponent thermofluid through distinct but interrelated microscopic mechanisms, providing a molecular-level basis for optimizing multicomponent thermofluid injection strategies in shale oil recovery.

This study extends previous investigations of soils in Zagreb, the capital of Croatia, by focusing on 25 urban samples selected on the basis of their magnetic susceptibility values. A single-step extraction was performed using 1 M HCl, 2 M HNO₃, and 1 M CH₃COONH₄ as extraction reagents. The contents of As, Ba, Cd, Co, Cr, Cu, Fe, K, Mn, Ni, Pb, Sb, and Zn in the extracts were determined using inductively coupled plasma–optical emission spectrometry (ICP-OES). Extraction efficiency was evaluated by comparing element contents obtained with each reagent and their ratios to the corresponding total element contents. Efficiency varied significantly; 1 M HCl showed the highest average efficiency for most elements (range 0.64–59.9%), while 2 M HNO₃ achieved the highest maximum efficiency values (0.31–75.6%). The 1 M CH₃COONH₄ was more efficient for K and Ba than for other elements (0.010- 57.7%). The extraction efficiency of the two acids followed a clear pattern—similar recoveries for some samples, HCl-favoured for others, and HNO₃-favoured for the rest. The elemental contents were found to reflect contributions from Mount Medvednica, the Sava River floodplain, and anthropogenic sources. These results indicate that single-step extraction is a valuable method for estimating element mobility.

Silica–carbon briquettes enable the incorporation of fine-grained silica-bearing materials and carbonaceous reductants into the charge used for ferrosilicon smelting. This study examines the composition of the composite disclosed in Patent of the Republic of Kazakh-stan No. 38264, the results of X-ray diffraction analysis of the briquette, and the chemical composition of ferrosilicon samples sequentially collected during the experimental smelting campaign. According to the patent data, the composite contained 41.41% fixed carbon, while the ash content was 39.38% on a dry basis, and the SiO₂ content in the mineral fraction was 90–92%. The first addition of briquettes was recorded at tapping No. 17. However, the exact timing of the corresponding metal sample collection relative to briquette charging is unknown; therefore, this sample was excluded from the comparison between the two operating periods. In samples Nos. 10–16, the Si content ranged from 74.75 to 76.21 wt.%, whereas in samples Nos. 18–24, it ranged from 75.49 to 76.47 wt.%. The corresponding arithmetic mean values were 75.65 and 75.77 wt.%, respectively. Analysis of the X-ray diffraction pattern of metal sample No. 20 allowed two iron–silicon phases to be tentatively identified. A silicon content of approximately 75 wt.% had already been achieved before the introduction of the briquettes. Owing to the sequential nature of the smelting campaign and the absence of a directly comparable material balance, the independent effect of the briquettes on alloy composition, silicon recovery, or electrical energy consumption cannot be reliably established.