Lei Wu,Guansheng Qi,Wei Lu,Zhenglong He,Jialiang Li,Jinliang Li,Min He
In the process of coal mining, coal spontaneous combustion in the gob area poses serious threats to the safety of mine production. Besides, coal combustion also produces a large amount of greenhouse gas CO 2 , which triggers a series of ecological environment problems. In order to solve these two problems, the idea of mineralizing CO 2 with the alkaline industrial waste calcium carbide slag and then sending the foams to the gob area for coal spontaneous combustion prevention was proposed in this study. First, the effects of calcium carbide slag foaming under the action of different types of foaming agents, including sodium dodecyl sulfate (SDS), sodium dodecyl benzene sulfonate (SDBS), polyoxyethylene fatty alcohol sodium sulfate (AES), and octyl decyl glucoside (APG0810), were tested and analyzed. Furthermore, the effects of water glass (WG), sodium alginate (SA), polyvinyl alcohol 1799 (PVA), cement, and silica micro-powder on the foam stability were analyzed by investigating the stability coefficient and drainage volume of calcium carbide slag foam. On this basis, the configuration scheme of calcium carbide slag foam with high efficiency and good stability was determined. The experimental results on CO 2 mineralization and coal spontaneous combustion inhibition reveal that the prepared calcium carbide slag foam can rapidly absorb CO 2 . Moreover, after calcium carbide slag foam treatment, the spontaneous combustion tendency of the coal sample is significantly reduced.
Chunhua Dong,Xingfu Song,Jie Zhang,Evert Jan Meijer,Hang Chen,Jianguo Yu
A thermal dissociation process (ideally, 100% atom utilization) to regenerate the amine extractant and to produce gaseous HCl which is the key to realizing the CO 2 mineralization with metal chloride waste liquids was investigated. Solvent effects on the thermal dissociation of tri-n-octylamine hydrochloride (TOAHCl) were predicted to be prominent via analyzing structure parameters, charge distribution, solvation free energy, apparent basicity, and N-H frequency with the help of molecular simulation and experiments. Inert solvents with low polarity such as decalin, dodecane were favorable in thermal dissociation experiments. In particular, decalin enhanced the dissociation most effectively which is in agreement with the prediction. In dilute solutions, the thermal dissociation kinetics was shown to be first order. The apparent reaction rate (3.0 × 10 −4 −1.5 × 10 −2 min −1 ) and activation energy (58.219-121.827 kJ/mol) differ a lot at 180-190°C in various solvents, confirming a strong solvent effect. A two-stage reaction scheme in dilute solutions has been proposed from the experimental study. The overall process is entropically driven, with the removal of HCl into gas phase from the solvated state. The work could offer a fundamental direction for the further actual process.
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