Three kinds of mineral-supported polyethylene glycol (PEG) as form-stable composite phase change materials (CPCMs) were prepared to choose the most suitable CPCMs in asphalt pavements for the problems of asphalt pavements rutting diseases and urban heat islands. The microstructure and chemical structure of CPCMs were characterized by SEM, FT-IR and XRD. Thermal properties of the CPCMs were determined by TG and DSC. The maximum PEG absorption of diatomite (DI), expanded perlite (EP) and expanded vermiculite (EVM) could reach 72%, 67% and 73.6%, respectively. The melting temperatures and latent heat of CPCMs are in the range of 52–55 °C and 100–115 J/g, respectively. The results show that PEG/EP has the best thermal and chemical stability after 100 times of heating-cooling process. Moreover, crystallization fraction results show that PEG/EP has slightly higher latent heats than that of PEG/DI and PEG/EVM. Temperature-adjusting asphalt mixture was prepared by substituting the fine aggregates with PEG/EP CPCMs. The upper surface maximum temperature difference of temperature-adjusting asphalt mixture reaches about 7.0 °C in laboratory, and the surface peak temperature reduces up to 4.3 °C in the field experiment during a typical summer day, indicating a great potential application for regulating pavement temperature field and alleviating the urban heat islands.

Organic montmorillonite (OMMT) was obtained by reacting montmorillonite (MMT) with the surfactant cetyltrimethyl ammonium bromide (CTAB). The crystalline phases of MMT and OMMT were characterized by microscopic performance analysis using an X-ray diffractometer (XRD) and scanning electron microscope (SEM). The effects of rubber, attapulgite, columnar diatomite, and disk diatomite on the technological and rheological properties of OMMT-modified asphalt were studied using a dynamic shear rheometer, and the low-temperature properties were determined from their creep characteristics by a bending beam rheometer. The short-term, long-term, and ultraviolet (UV) aging of modified asphalt were tested, respectively. After adding five types of modifiers to the asphalt, the high-temperature rheological and aging resistance of matrix asphalt and modified asphalt can be improved. In particular, it is shown that modification with OMMT with attapulgite as comodifier had a positive influence on asphalt thermo-oxidative aging and UV aging.

The flotation separation of scheelite from calcite is problematic, where sodium silicate modified by polyvalent metal ions has shown some advantages for selective depression. In this study, an Al-Na₂SiO₃ polymer was used as the depressant for the flotation separation of scheelite from calcite using a lead complex of benzohydroxamic acid (Pb-BHA) as the collector. Furthermore, a number of measurements were conducted to investigate the structure of the Al-Na₂SiO₃ polymer and its adsorption behavior with Pb-BHA complexes on the mineral surface. Flotation experiments indicated that the Al-Na₂SiO₃ polymer shows good selectivity for the flotation separation of scheelite from calcite at pH 8, where the optimum ratio of sodium silicate to aluminum sulfate was 2:1. Fourier-Transform Infrared (FTIR) and solution chemical analyses revealed that aluminum hydroxide complexes and the hydroxy moiety of silicic acid are able to self-assemble via condensation affording an Al-Na₂SiO₃ polymer, i.e., a composite aluminosilicate polymer. The zeta potential measurements and adsorption capacity measurements indicated that, upon adsorption of the Al-Na₂SiO₃ polymer and Pb-BHA complexes on the mineral surface, the Al-Na₂SiO₃ polymer had less influence on the adsorption of Pb-BHA complexes on the scheelite surface, while the opposite was true for calcite. Therefore, more Pb-BHA complexes and fewer Al-Na₂SiO₃ polymers were deposited on the scheelite surface, while fewer Pb-BHA complexes and more Al-Na₂SiO₃ polymers were adsorbed on the calcite surface. The selective separation of scheelite from calcite was attributed to the cooperative selectivity of the Pb-BHA complexes and Al-Na₂SiO₃ polymer.

TiO₂ pillared montmorillonite (T/M) modifiers have been studied to alleviate the aging of asphalt pavement and degrade automobile exhaust, but the photocatalytic activity of ordinary TiO₂ is not good enough. In this study, in order to improve the photocatalytic performance of T/M, different metal (Ce, Cu, Fe) doped modifiers were prepared based on T/M. Metal doped TiO₂ pillared montmorillonite was prepared by the sol-gel method. The modifier was characterized by X-ray diffraction (XRD) and an Ultraviolet visible (UV-Vis) spectrophotometer. The results show that TiO₂ with different metal ions successfully entered into the layer of organic montmorillonite (OMMT) to form a pillared structure. Compared with the undoped TiO₂ pillared montmorillonite (T/M), the optical absorption edge of the metal doped TiO₂ pillared montmorillonite has an obvious red shift. In addition, the influences of the different content of modifiers on the properties of the original bitumen and catalytic capacities for automobile exhaust were also investigated. The results show that Ce doped TiO₂ (Ce-T/M) pillared montmorillonite has the best improvement in high temperature performance and ultraviolet (UV) resistance of bitumen. In the experiment of automobile exhaust degradation, the degradation law of NO and HC showed Cu-T/M > Ce-T/M > Fe-T/M > T/M. These three kinds of metal ions can effectively improve the photocatalytic degradation efficiency of T/M.

Pb–BHA complexes have been shown to be selective for the separation of tungsten and cassiterite minerals from calcium minerals. These minerals could be enriched synchronously to some extent using Pb–BHA complexes flotation. However, it is difficult to further improve the quality and recovery of the scheelite, wolframite, and cassiterite concentrate due to their different behavior in flotation, such as flotation rate and sensitivities to depressants. Moreover, the super fine particles create some challenges for the cleaning flotation process. In this study, advanced gravity separators for super fine particles were introduced for the cleaning process based on the slight difference in the specific gravity of scheelite, wolframite, and cassiterite. The new process featured pre-enrichment using Pb–BHA flotation, and upgrading using gravity separation, taking into account both the similarities and differences in floatability and density of the different minerals. The grades of WO₃ and Sn in the concentrate of the new process reached to 61% and 2.89%, respectively, and the recovery of Sn was significantly improved. In addition, gravity separation is highly efficient, cost effective, and chemical-free, which is environmentally friendly. This study has proven that physical separation can be used for the purification of flotation products and provide some solutions for separation problems of complex refractory ores, which has, up until now, been rarely reported in the literature and/or applied in mineral processing.

With the rapid development of economic construction, styrene-butadiene-styrene (SBS)-modified asphalt is being more and more widely used in highway engineering, but there are still many deficiencies in the process of its use. In order to further improve its performance for use, nano-organic palygorskite (A-Pal) and star-shaped SBS were compounded to obtain modified asphalt in this study. The high-temperature stability of SBS-modified asphalt was enhanced after incorporation with A-Pal for the high-temperature stability test by a dynamic shear rheometer. The A-Pal should improve the surface free energy and adhesion of SBS-modified asphalt by the water stability test analysis. The aging test shows that A-Pal can reduce the thermal oxygen decomposition of SBS and improve the anti-aging performance and the fatigue resistance of SBS-modified asphalt. A-Pal has a certain improvement effect on the low temperature performance of SBS-modified asphalt as shown by a low temperature crack resistance test. A-Pal-compounded SBS-modified asphalt features good storage stability in normal temperatures with the lowest critical compatibility temperature.