Reverse flotation was proposed as a potential method for the upgradation of low rank thermal coal. Higher combustible matter recovery in the float could be obtained using reverse flotation method compared to conventional flotation method. In order to reduce the entrainment of fine particles, oleic acid (OA) was used as froth regulator in coal reverse flotation process. Experimental data showed that the total volume of froth product in the absence of OA was almost 3 times more than that in the presence of 0.45 kg/Mg OA dosage. Reverse flotation results showed that the ash content of froth product increased with the increase of OA dosage which indicated that the entrained coal particles could be decreased by the addition of froth regulator OA.
Refined design of sustainable sorbent demands to tackle the strong dependence for additional mesoporous support and low utilization in hot coal gas desulfurization. Unlike the well-established preparation of loading sorbents supported on zeolites, a vacuum-assisted self-assemble strategy tapping into the ordered channels of walnut wood is proposed to facilely fabricate three-dimensional (3D) (a%Ce–Mn) y Al 2−y O x desulfurizers with anisotropy which provides a desirable macroporosity for rapid diffusion of H 2 S. Benefiting from the inherent straight channle in micron scale, the obtained (8%Ce–Mn) 1.5 Al 0.5 O x presents the highest breakthrough sulfur capacity (289.79 mg g −1 ) and effective utilization (88.42%) at 700 °C. The favorable rapid diffusion of gases in micro/macropores improves greatly the H 2 O-resistance and anti-interference ability of 3D (8%Ce–Mn) 1.5 Al 0.5 O x for high steam and concentration of reducing gas. The fast mass transport in sulfidation reaction at 700 °C is described perfectly by the improved deactivation kinetics model. This study opens a novel design of the ideal 3D desulfurizers with micron porosity inherited from hierarchical architecture of walnut wood for industrialization utilization in the near future.
Reverse flotation of Pingsuo thermal coal was investigated and it turned out that a large amount of DDA-HCL (dodecylamine hydrochloride) was needed in this process. Two fatty acids (dodecanoic acid and oleic acid) of different carbon chain lengths emulsified by DDA-HCL were used to compare with DDA-HCL in the experiments. Experimental results showed that the two emulsions had stronger collectivity than DDA-HCL. Dodecanoic emulsions had higher selectivity than OA (oleic acid) emulsions. The application of dodecanoic emulsions can obtain a lower ash content of the concentrate than DDA-HCL at the same collector dosage. And it can reduce DDA-HCL consumption greatly under the same concentrate ash content. Reverse flotation results of the two emulsions were also compared. The results indicated that the selectivity of dodecanoic emulsions dropped sharply when the amount of substance ratio of DDA-HCL and dodecanoic acid was less than 1:1.
Developing structurally stable sorbents for high-temperature H 2 S direct removal is recognized as a valuable energy-saving strategy for efficient utilization of hot coal gas (HCG), which depends upon their mesoporous features and desulfurization capabilities. Herein, tailored hierarchical Ca x Cu y Mn z O i /MAS-9 sorbents were fabricated via a facile sol–gel method using high-activity phase Ca x Cu y Mn z O i anchored onto versatile mesoporous MAS-9. After O/S-exchange procedure, noteworthy straight channels of MAS-9 ( S BET = 808 m 2 g −1 ) provided enough available spaces for the storage of generative large MeS y nanoparticles, which was better than other conventional zeolites. The probing of variables ( i.e. support type, active ingredient, loadings, and sulfidation temperature) on H 2 S removal revealed that 50%Ca 3 Cu 10 Mn 87 O i /MAS-9 shared an excellent breakthrough sulfur capacity (171.57 mg g −1 ) at 800 °C, even it experienced six reusable cycles, due to synergistic stabilizing effect of Ca-Cu-Mn and high-temperature tolerance of Si O Al framework of MAS-9. Especially, CaO dopant endowed the sorbent with superficial alkalinity and high-temperature resistance. The brilliant desulfurization behavior was also described by the fast H 2 S diffusion or component deactivation vs . duration time on stream according to the followed kinetic investigation. Thus, the refined Ca 3 Cu 10 Mn 87 O i /MAS-9 possesses the expected representative desulfurization nature and great potentiality for raw HCG in practical applications.
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