Dust removal and purification of calcium carbide furnace off-gas

摘要

A large amount of CO contained in calcium carbide furnace off-gas can be recycled and used as an important raw material for C1 (one carbon) industrial chemical manufacturing. The key to the recovery is the removal of dust and gaseous impurities from the off-gas. For this purpose, an industrial device has been used for removing the dust. This consists of a laboratory-scale fixed-bed reactor with two kinds of adsorbents, prepared in our laboratory, for removing HCN and COS. The results show that the dust content after the dedusting process was less than 20 mg/m~3. The dust particles are composed of microspheres, with an obvious tendency to agglomerate, and with an average diameter of about 6.71 μm. After adsorption, the outlet concentrations of both HCN and COS were less than 1 mg/m~3. In order to remove HCN, activated carbon (AC) was used, impregnated with 0.15 mol/L Cu(CH_3COO)_2 solution. The optimum calcination temperature was 350 °C. The AC, modified with Cu(CH_3COO)_2, was examined by means of N_2-BET and X-ray photoelectron spectroscopy (XPS) before and after off-gas treatment. The results indicate that the chemisorption products were mainly present in the AC micropores and mesopores, with radius 0.81-1.51 nm. After dust removal and purification, the calcium carbide furnace off-gas is fit for use as a raw material in the C1 chemical manufacturing industry.