Fundamental Study for The Production of Metallurgical Coke by Hydrothermal Treatment

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The extraction behavior of mineral impurities from Brazilian coal was investigated from 180 to 250ﾟC in the Ca(OH)_2/NaOH solution...Among them, removal of phosphorus was better realized than other inert matters. The phosphorus extraction reached the highest results at lower temperatures between 180ﾟC and 200ﾟC.It was also found that lower concentrations could give better results; especially in the case of Ca(OH)_2. Using Ca(OH)_2, the better concentration range was considered to be from 0.5 mol/kg-H_2O to 1.0 mol/kg-H_2O. NaOH 2.0 mol/kg-H_2O leads more phosphorus to be removal. In the case of NaOH, significant lost of coal matter was observed either for the temperature increasing or for the concentration increasing. When the temperature goes up more than 200ﾟC, the calcium-phosphate complexes convert into hardly soluble matter such as hydroxyl apatite and turn back to the residue again.The SiO_2 and Al_2O_3 behaviors are quite similar: the higher the temperature and the reagent concentration, the higher the extraction degree of SiO_2 and Al_2O_3 in the case of NaOH. In addition, the increasing of temperature can promote more removal of SiO_2. The Ca(OH)_2 was not effective for SiO_2 and Al_2O_3 extraction.Compared the effects of Ca(OH)_2 and NaOH, Ca(OH)_2 showed more promising results. Furthermore, Ca(OH)_2 is much suitable than NaOH in the production factory. Nevertheless at atmospheric pressure conditions, hot water bath, NaOH is better than Ca(OH)_2 for removing phosphorus.