A bipolar plate for an electrolyzer, particularly a PEM electrolyzer, is formed with a central region and a peripheral region surrounding the central region. With a view to cost-effective production of the bipolar plate, the central region is made of metal sheet and the peripheral region is formed from a plastic frame. The plastic frame is made of at least one thermoplastic, particularly at least one high-temperature thermoplastic, and is injection-molded around the sheet metal.

A blast furnace operation method comprising a blast furnace to start up smoothly and perform operation after suspending air blowing by removing as much as possible residual coke that remains inside the furnace during suspension of air blowing and becomes an obstacle to discharging solidified matter. In this blast furnace operation method, air blowing is suspended with the height of a surface of a raw material-filled layer immediately above a blast-furnace tuyere reduced below the height of an upper end of a blast-furnace bosh and then air blowing is resumed. After air blowing into the blast furnace is suspended, oxygen or oxygen and a combustible gas are blown in through a burner inserted into a taphole to combust coke remaining inside the furnace and reduce the volume of residues inside the furnace, and after new coke is charged to a region where the volume decreased, air is blown through a tuyere.

A blast furnace operation method comprising a blast furnace to start up smoothly and perform operation after suspending air blowing by removing as much as possible residual coke that remains inside the furnace during suspension of air blowing and becomes an obstacle to discharging solidified matter. In this blast furnace operation method, air blowing is suspended with the height of a surface of a raw material-filled layer immediately above a blast-furnace tuyere reduced below the height of an upper end of a blast-furnace bosh and then air blowing is resumed. After air blowing into the blast furnace is suspended, oxygen or oxygen and a combustible gas are blown in through a burner inserted into a taphole to combust coke remaining inside the furnace and reduce the volume of residues inside the furnace, and after new coke is charged to a region where the volume decreased, air is blown through a tuyere.

A blast furnace operation method comprising a blast furnace to start up smoothly and perform operation after suspending air blowing by removing as much as possible residual coke that remains inside the furnace during suspension of air blowing and becomes an obstacle to discharging solidified matter. In this blast furnace operation method, air blowing is suspended with the height of a surface of a raw material-filled layer immediately above a blast-furnace tuyere reduced below the height of an upper end of a blast-furnace bosh and then air blowing is resumed. After air blowing into the blast furnace is suspended, oxygen or oxygen and a combustible gas are blown in through a burner inserted into a taphole to combust coke remaining inside the furnace and reduce the volume of residues inside the furnace, and after new coke is charged to a region where the volume decreased, air is blown through a tuyere.

A blast furnace operation method comprising a blast furnace to start up smoothly and perform operation after suspending air blowing by removing as much as possible residual coke that remains inside the furnace during suspension of air blowing and becomes an obstacle to discharging solidified matter. In this blast furnace operation method, air blowing is suspended with the height of a surface of a raw material-filled layer immediately above a blast-furnace tuyere reduced below the height of an upper end of a blast-furnace bosh and then air blowing is resumed. After air blowing into the blast furnace is suspended, oxygen or oxygen and a combustible gas are blown in through a burner inserted into a taphole to combust coke remaining inside the furnace and reduce the volume of residues inside the furnace, and after new coke is charged to a region where the volume decreased, air is blown through a tuyere.