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The coal gasification process produces a large amount of wastewater which is seriously polluted and difficult to biochemically treat. The regasification of coal water slurry produced from gasification wastewater meets the requirements of clean and efficient use of energy and the concept of circular economy. In this paper, the slurryability of coal water slurry prepared with gasification wastewater was measured, and the influence mechanism of organic matter, metal ions, and ammonia nitrogen components in coal gasification wastewater on slurryability has been studied. Results show that (a) Coal water slurry can be prepared with gasification wastewater, and the composition of wastewater has a great influence on the slurryability. (b) Phenols and alcohols in wastewater are not conducive to slurryability, while urethane in wastewater is beneficial for slurrying. (c) K+ and Na+ in wastewater have little effect on the slurryablity even in high concentration, while Mg2+ and Ca2+ have basically no effect on the slurryability under the concentration range of coal gasification wastewater. However, Fe3+ has a negative effect and Cu3+ has a positive effect on the slurryability at low concentrations. (d) Ammonia nitrogen can affect the slurryability of coal water slurry by affecting the pH of the solution. NH4OH solution is alkaline, which is conducive to slurrying, while (NH4)2SO4 and NH4Cl solutions are acidic, resulting in poor slurryability of coal water slurry. [ABSTRACT FROM AUTHOR]

Abstract: Bioferment residue of drugs (BRD) is one kind of harmful and hazardous substance which has complex compositions. Thus, proper treatment of these residues has become an important concern. BRD can be utilized harmlessly and economically by mixing it with coal powder, water, and dispersant to prepare slurry fuel, named as coal‐BRD‐slurry (CBRDS). In this study, the influence of BRD on the slurry ability and combustion behaviour of CBRDS was investigated with coal water slurry (CWS) as reference. Results showed that the dispersant can reduce the slurry viscosity of CBRDS and CWS, and its optimum dosage was 0.6 wt% on the dried coal basis. The fixed‐viscosity concentration of CBRDS decreased with increasing BRD dosage. CBRDS and CWS exhibited shear‐thinning behaviour. The rheological behaviour was fitted by the power law. CBRDS exhibited higher apparent viscosity and stronger shear‐thinning behaviour because of the flocculent structure and well‐developed pores of the BRD. BRD can improve the stability of CWS by decreasing solid‐liquid separation of the slurry. Addition of BRD decreased the ignition temperature and increased the ash residues, suggesting a synergistic effect of CWS and BRD occurred during the combustion of CBRDS. [ABSTRACT FROM AUTHOR]

• CWWS is prepared using various types of coal chemical wastewater. • GWW, SW, IW, and MW promote slurryability, while CW shows a negative effect. • All CWWSs exhibit pseudoplastic fluid property and good stability. • CMWS shows high carbon conversion rate and cold gas efficiency when being gasified. The coal water slurry gasification combined with ammonia synthesis process produces various complex wastewaters that are difficult to handle, and the improper disposal of these wastewaters causes great harm to the environment. In this paper, coal wastewater slurry was prepared from these wastewaters, and its slurryability, rheology and stability were measured. The gasification characteristics were studied in a coal water slurry gasifier. Results show that (a) The gas washing wastewater, sulfur wastewater and industrial wastewater can promote slurryability, whereas carbonized water is not conducive to promoting slurryability. The mixed wastewater, that comprises all four types of wastewater mentioned above, promotes slurryability and has a slurry concentration of 62.0%. All coal wastewater slurries exhibit pseudoplastic fluid property, which are beneficial for industrial pumping and atomization. The stability of the samples was evaluated by analyzing the water separation rate, and all coal wastewater slurries show better stability than the coal deionized water slurry. (b) In the industrial application process, the active component of the syngas produced from the gasification of the coal mixed wastewater slurry can reach 78.6% and has a higher H 2 content than the syngas produced from ordinary coal water slurry. Moreover, using the coal mixed wastewater slurry can increase cold gas efficiency by 1.57% and carbon conversion rate by 0.45% in industrial processes. Therefore, preparing and using coal mixed wastewater slurry in coal water slurry gasification combined with ammonia synthesis process not only treats high-concentration wastewater but also achieves sustainable development and a circular economy model. [ABSTRACT FROM AUTHOR]

• High concentration organic waste liquids was investigated to reduce clean water consumption. • Mixing two types of organic waste liquids that are insoluble in each other evenly. • The total interaction energy in the entire WCWS system is greater than 0. • The steric stabilization energy is introduced into the system by xanthan gum. • Xanthan gum serves as a bridge in the system based on its molecular characteristic. High-concentration organic waste liquids have complex components and their treatment is difficult. These liquids also contain hydrophobic organic pollutants. The preparation of waste liquid coal water slurry (WCWS) can aid with environmental protection and resource utilization. In this study, xanthan gum was selected from 11 types of additives because it overcomes the problem of solution incompatibility during the mixing of various high-concentration organic waste liquids. The experimental results showed that with 0.08 wt% addition of xanthan gum, no stratification occurred in the mixed waste liquid and the apparent viscosity of the WCWS was 921.1 mPa ∙ s. In this study, the role of xanthan gum was studied, and the effect of its addition on the coal particle surface was characterized by zeta potential and contact angle measurement. In addition, various interaction energies in the WCWS system were calculated using the extended DLVO theory. The results showed that xanthan gum introduced steric hindrance interaction energy into the WCWS system, enabling the system to be stably dispersed. [ABSTRACT FROM AUTHOR]