By analyzing the thermal and burden structure conditions inside the melter-gasifier of COREX process,the advantage and disadvantage of PCI into the melter-gasifier are clarified.The influence of PCI on the running condition inside the furnace is analyzed based on the information from production operation and mathematical and physical simulations,and measures to tackle with the problems arising from PCI are proposed.The main results are as follows.①Due to the unfavorable conditions for coking of coal in the melter-gasifier,coking of charged lumpy coal to get semicoke with good size and strength can hardly be expected.To maintain the permeability of the burden column,a packed bed similar to blast furnace is necessary.Therefore,a little more coke with PCI in place of most of the lumpy coal may improve the running of the reactor.This can also make the lumpy coal selection easier.②Overall heat balance analysis of the melter-gasifier shows that PCI has no effect on the thermal condition of the furnace as a whole.Local heat balance analysis,however,shows that the heath of the melter-gasifier is in a critical state of low heat supply.PCI into the hearth will deteriorate the thermal condition.To avoid the cooling of the hearth zone by PCI,more oxygen can be blown to the hearth zone,i.e.increase the oxygen supply to the hearth and decrease accordingly the oxygen supply to the freeboard.More oxygen supply to the hearth seems to bring out the issue of an increase in fuel rate and/or thereby the smelting intensity.Detailed analysis of the physical chemical processes concluded that PCI with more corresponding oxygen supply will not lead to the increase of fuel rate.③Comparing with blast furnace,the raceway volume of COREX melter-gasifier is about only 1/10～1/5 of that of corresponding-size blast furnace.This small raceway is not favorable for PCI.To enlarge the raceway to get more favorable condition for PCI,less tuyeres with more oxygen supply of each tuyere is proposed.④Comparing with lumpy coal feeding into the furnace top,PCI into the hearth will increase the heat consumption in the lower part and decrease the heat consumption in the upper part of the furnace,leading to an increase in freeboard temperature,as well as a heat insufficiency of the hearth zone.In addition to more oxygen supply to the hearth,a more active hearth for better heat transfer is thus also indispensible to maintain its thermal condition.This can be realized by greater raceway size and the consequent better central gas flow.⑤PCI from the primary tuyeres into the hearth can increase the gas volume from the raceway.It can also decrease the coal fines from the lumpy coal charged from the furnace top.These are all favorable to improve the central gas flow,and thereby improve the running of the furnace.⑥Comparing with blast furnace,COREX process is capable to easily control the direct reduction ratio of the overall reduction process,and thus,total fuel rate lower than blast furnace is attainable if the pursuance of coke-less operation is not overemphasized. By analyzing the thermal and burden structure conditions inside the melter-gasifier of COREX process, the advantage and disadvantage of PCI into the melter-gasifier are clarified. The influence of PCI on the running condition inside the furnace is analyzed based on the information from production operation and mathematical and physical simulations, and measures to tackle with the problems arising from PCI are proposed. The main results are as follows. ① Due to the unfavorable conditions for coking of coal in the melter-gasifier, coking of charged lumpy coal to get semicoke with good size and strength can hardly be expected. To maintain the permeability of the burden column, a packed bed similar to blast furnace is necessary. Herefore, a little more coke with PCI in place of most of the lumpy coal may improve the running of the reactor. This can also make the lumpy coal selection easier.②Overall heat balance analysis of the melter-gasifier shows that PCI has no effect on the thermal condition of the furnace as a whole. Local heat balance analysis, however, shows that the heath of the melter-gasifier is in a critical state of low heat supply. PCI into the hearth will deteriorate the thermal condition. To avoid the cooling of the hearth zone by PCI, more oxygen can be blown to the hearth zone, ieincrease the oxygen supply to the hearth and decrease accordingly the oxygen supply to the freeboard. More oxygen supply to the hearth seems to bring out the issue of an increase in fuel rate and / or thereby the smelting intensity. Detailed analysis of the physical chemical processes that that PCI with more corresponding oxygen supply will not lead to the increase of fuel rate. ③Comparing with blast furnace, the raceway volume of COREX melter-gasifier is about only 1 / 10 ~ 1/5 of that of corresponding-size blast furnace. This small raceway is not favorable for PCI.To enlarge the raceway to get more favorable condition for PCI, less tuyeres with more oxygen supply of each tuyere is proposed. ④ Comparing with lumpy coal feeding into the furnace top, PCI into the hearth will increase the heat consumption in the lower part and decrease the heat consumption in the upper part of the furnace, leading to an increase in freeboard temperature, as well as a heat insufficiency of the hearth zone. In addition to more oxygen supply to the hearth, a more active hearth for better heat transfer is thus also indispensible to maintain its thermal condition. This can be realized by greater raceway size and the consequent better central gas flow. from the primary tuyeres into the hearth can increase the gas volume from the raceway. It can also decrease the coal fines from the lumpy coal charged from the furnace top. These are all favorable to improve the central gas flow, and so improve the running of the furnace. ⑥Comparing with blast furnace, COREX process is capable to easily control the direct reduction ratio of the overall reduction process, and thus, total fuel rate lower than blast furnace is a ttainable if the pursuance of coke-less operation is not overemphasized.