Key Engineering Materials Vol. 748

Abstract: Recently, using CO2 as fluid to exploit thermal energy in hot dry rock has attracted the attention of researchers. The water-rock-CO2 interaction in hot dry rock CO2 will change reservoir mineral composition and physical characteristics (such as porosity and permeability) by precipitation and dissolution of mineral in artificial geothermal reservoir, which will influence the stable operation of CO2-EGS and affect the scaling and corrosion in pipes and equipment. On the other hand, water-rock-CO2 interaction is closely related to CO2 sequestration. In this paper, the interaction mechanism including phase equilibrium, mineral composition analysis, temperature and brine component , interaction region and interaction damage are summarized, which can be used as a guide for further research。We find that the water-rock-CO2 interaction analysis now is most for single factor and single mineral component. And the mechanism of reaction between single supercritical CO2 and mineral is not clear. Study about spatio-temporal evolution of mineral component and fluid component, combined with the spatio-temporal evolution of temperature and pressure, is little.

Abstract: The experiment focused on the bioleaching and desulfurization of pyrite roasting residues by the bacteria for the recovery of Cu, Zn and the magnetic materials. First of all, the study systematically performed XRD, which provided scientific and technique basis for extraction of valuable metals. Subsequently, the effect of the pH, the temperature and the bacterial inoculum volume ratio on the bioleaching was investigated. The data revealed that the condition under the pH of 1.2, the temperature of 45°C and bacterial inoculum volume ratio of 10% had the most significant effect on the bioleaching and the recovery rates of Cu, Zn and SO₄^2- reached up to 80%, 99% and 80%, respectively. Finally, multi-elements analysis before and after the bioleaching experiments was performed to further explore the ability of the NB bacteria to oxidize the Deerni pyrite roasting residues. The study demonstrated that the total Fe and sulfur contents of the bioleaching residues accounted for 68.47% and 0.28%, respectively. The content of Cu and Zn in the leaching residue were only 0.09% and 0.01%. The desulfurization effects are evident and bioleaching residues meet the requirements as magnetic materials in steel making industry.

Abstract: ANSYS finite element analysis theory was employed to simulate the process of biomass compression molding. The analysis and calculation like element selection, material attribute setting, mesh generation, contact pair establishment, load and constrain applying and solver setting were finished. The results shows that: The biomass produced in this mold contains heterogeneous density where the density in one end is higher than the other end; There is still shear stress at the section of molding fuel, which cannot be removed after molding; moreover, along with the natural expansion of biomass material after compression, crack is likely to appear on the surface of biomass molding fuel. With respect to mold, it is obvious that, the stress of top of compression material to mold is the largest, which is caused by the concentrated stress on mold generated by joint action of friction between raw material and mold, larger extrusion force at top and deformation force of raw material resisting compression. Thus, the abrasion of this mold at this part is the largest.