Methanol Production from Silicomanganese Off-Gas of Arc Submerged Furnace

The Erdos group with silicomanganese (SiMn) capacity of 3.3x105t/a by-produces off-gas approaching to about 4.48x108Nm3/a. These off-gases were usually combusted in lime or pellet production or for power generation. However, the thermal efficiency of such utilization is not high, and the added value is comparably low. In addition, all the CO is combusted into CO2 and discharged to the atmosphere. Although the CO direct emission has been solved, it cannot reduce the total CO2emission.To increase the value of silicomanganese off-gas (SMOG) and reduce CO2 emission, Erdos Power & Metallurgical Group (EPMG ) has implemented an off-gas high-efficient utilization project, including the first operating SMOG to methanol plant in China and a food-grade CO2 plant. The units in the methanol plant mainly consists of gas dedusting, washing, compression, one-step fine desulphurization, sulphur-free isothermal water-gas shift(WGS), pressure swing adsorption(PSA) decarbonization, methanol synthesis and rectification. The methanol plant can treat 3.44x108Nm3/a of SMOG producing methanol and by-producing enriched CO2 gas and steam. The methanol can be used as automotive fuel additive or feedstock for producing olefins and other chemicals. Besides, enriched CO2 gas is transported to Erdos food-grade CO2 Plant as raw material, and all steam is used for district heating. This project can reduce about 3.575x105t/a of CO2 emission, which accounts for 64% of total CO2 production from Erdos SiMn production. Its new annual profit is estimated to be more than 100 million RMB. The Chinese silicomanganese industry holds more than 20 million tons of annual production capacity, and its off-gas flow rate exceeds 120 billion Nm3/a. Accordingly, the information presented in this report provide a significant reference on high-efficient off-gas utilization for Chinese silicomanganese manufacturers.