| Semi-coke is solid product of low metamorphic bituminous coal and lignite under lowtemperature carbonization, its production is mainly concentrated in the northwest region ofour country. After decades of development, semi-coke has formed industrial chains on thebasis of coal carbonization, including magnesium, iron alloy, chemical fertilizer, calciumcarbide, power generation, etc. The lump coke of semi-coke is widely used in smelting ofcalcium carbide, calcium and silicon ferroalloy, while fine grained semi-coke’ s small sizeand high ash content result in low added value and narrow purposes. With the popularizationof internal heating rotary kiln technology and solid heat carrier pyrolysis technology usingpulverized coal as raw material, the production of fine grained semi-coke will increasesharply. With the implementation of the coal high quality clean efficient conversion andutilization route, it is imperative to turn semi-coke into a clean and efficient energy byimproving the quality of the fine grained semi-coke, and increasing the utilization rate ofresources.This paper aimed at the characteristics of small size, high ash content of fine grainedsemi-coke, to realize the effective resource utilization of fine grained semi-coke throughimproving the quality by flotation. Semi-coke has developed pore structure and lots ofhydrophilic oxygen-containing functional groups, so it’s difficult to achieve effective flotationwith conventional flotation reagents. For this reason, the fine grained semi-coke was surfacemodified by means of adding different types of surfactants to flotation pulp respectively toimprove the effect of flotation. The experiments were conducted through adding cationicsurfactant (DTAB, TTAB, CTAB), anionic surfactant (DBS, SDS) and nonionic surfactant(Triton X-100) separately. The results show that the flotation effect of nonionic surfactantTriton X-100is the best among the selected surfactants, followed by anionic surfactant DBSand cationic surfactant CTAB. Then, orthogonal tests conducted with better subsequentflotation of Triton X-100and DBS, and the results reveal that when the dosage of DBS was 1800g/t, slurry density was60g/L, the amount of diesel was800g/t,2-octyl alcoholconsumption was600g/t, pure mineral rate was59.88%, ash was7.85%, combustible bodyrecovery rate was63.34%;When the dosage of Triton X-100was800g/t, slurry concentrationwas80g/L, diesel consumption was1200g/t,2-octyl alcohol consumption was800g/t, theflotation effect of semi-coke was the best, concentrate production rate was as high as66.73%,ash was8.34%, combustible recovery was70.02%. Vacuum filtration dehydration is used toexplore the influence of different filter on concentrate dehydration. The results show that thedehydration effect of silicone oil was better than SDS and DBS; the concentrate moisturedecreased from27.64%to19.26%by adding silicone oil.Cationic surfactant adsorbs on the surface of semi-coke by electrostatic interaction. TheDBS of anionic surfactant absorbs on the surface of semi-coke by the conjugation effect ofaromatic ring and benzene ring, and the adsorption force of SDS in the semi-coke surface isvery weak, it plays an emulsification role in collecting agent. Nonionic surfactant adsorbs onthe semi-coke surface through hydrogen bonds and the conjugation effect of aromatic ringand benzene ring. |
PDF Full Text Request