The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pel...The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pellets require higher preheating temperature and longer preheating time to attain required compression strength of pellets compared with the common magnetite oxidized pellets. It is found that when the hematite concentrates are pretreated by high pressure roll grinding （HPRG）, the compression strengths of preheated and roasted oxidized hematite pellets get improved even with lower preheating and roasting temperatures and shorter preheating and roasting time. The mechanism for HPRG to improve roasting properties of oxidized pellets were investigated and the cause mainly lies in the increase of micro-sized particles and the decrease of dispersion degree for hematite concentrates, which promotes the hematite concentrate particles to be compacted, the solid-phase crystallization, and finally the formation of Fe203 bonding bridges during subsequent high temperature roasting process.展开更多
The experiments were conducted on the changes of sintering performance of one kind of ultra fine-sized iron concentrate with or without being processed by high pressure roll grinding （HPRG）. The experimental results...The experiments were conducted on the changes of sintering performance of one kind of ultra fine-sized iron concentrate with or without being processed by high pressure roll grinding （HPRG）. The experimental results indi eate that the specific surface area increases from 1723.0 to 2 201.6 cm^2/g when the iron concentrate is processed by HPRG. The permeability of sintering mix increases and the iron concentrate becomes easy to react with CaO reagent at high temperature. The effect gets intensified when iron concentrate and lime are processed together By HPRG. The further studies indicate that compared with the base case, the sinter quality also gets improved, in which the yield of sinter increases from 67.24% to 69.52% and further to 71.68%, the tumble index （TI） increases from 60.38% to 62.13% and further to 64.45%, and the productivity increases from 1.42 to 1.57 t/（m^2 · h） and further to 1.62 t/（m^2 · h） when the iron concentrate is processed by HPRG or is processed with lime together. The metallurgical properties of sinter also get improved when the iron concentrate is pretreated by high pressure roll. The results indicate that it is conducive to the increase of sinter quality and productivity when the iron concentrates are processed by HPRG.展开更多
Investigation was conducted on roasting properties of pellets with an iron concentrate of complex mineral composition. The results indicated that the pellets of complex mineral composition concentrate required higher ...Investigation was conducted on roasting properties of pellets with an iron concentrate of complex mineral composition. The results indicated that the pellets of complex mineral composition concentrate required higher pre- heating temperature and longer preheating time than that of single magnetite concentrate. Therefore, it is difficult for preheated pellets to withstand the mechanical collision in the roasting process in rotary kiln. It was found that after the iron concentrate being subjected to high pressure roll grinding, the specific surface area reached 2 029. i cm2/g. Consequently, the preheating and roasting temperature of pellets were decreased by 70 and 50 ℃ and preheating and roasting time were decreased by 2 and 4 min, respectively. Meanwhile, the compression strength of preheated and roasted pellets were increased by 200 N for a pellet and 220 N for a pellet, respectively. The mechanism lied in that the increase of specific surface area activated thermal reaction and promoted formation of inter-grain bridge.展开更多
基金Project(50725416) supported by the National Natural Science Funds for Distinguished Young Scholars of China
文摘The mechanism of high pressure roll grinding on improvement of compression strength of oxidized hematite pellets was researched by considering their roasting properties. The results indicate that oxidized hematite pellets require higher preheating temperature and longer preheating time to attain required compression strength of pellets compared with the common magnetite oxidized pellets. It is found that when the hematite concentrates are pretreated by high pressure roll grinding （HPRG）, the compression strengths of preheated and roasted oxidized hematite pellets get improved even with lower preheating and roasting temperatures and shorter preheating and roasting time. The mechanism for HPRG to improve roasting properties of oxidized pellets were investigated and the cause mainly lies in the increase of micro-sized particles and the decrease of dispersion degree for hematite concentrates, which promotes the hematite concentrate particles to be compacted, the solid-phase crystallization, and finally the formation of Fe203 bonding bridges during subsequent high temperature roasting process.
基金Sponsored by Program for New Century Talents in University of China(NCET-10-0834)
文摘The experiments were conducted on the changes of sintering performance of one kind of ultra fine-sized iron concentrate with or without being processed by high pressure roll grinding （HPRG）. The experimental results indi eate that the specific surface area increases from 1723.0 to 2 201.6 cm^2/g when the iron concentrate is processed by HPRG. The permeability of sintering mix increases and the iron concentrate becomes easy to react with CaO reagent at high temperature. The effect gets intensified when iron concentrate and lime are processed together By HPRG. The further studies indicate that compared with the base case, the sinter quality also gets improved, in which the yield of sinter increases from 67.24% to 69.52% and further to 71.68%, the tumble index （TI） increases from 60.38% to 62.13% and further to 64.45%, and the productivity increases from 1.42 to 1.57 t/（m^2 · h） and further to 1.62 t/（m^2 · h） when the iron concentrate is processed by HPRG or is processed with lime together. The metallurgical properties of sinter also get improved when the iron concentrate is pretreated by high pressure roll. The results indicate that it is conducive to the increase of sinter quality and productivity when the iron concentrates are processed by HPRG.
基金Item Sponsored by National Natural Science Foundation of China(50725416)
文摘Investigation was conducted on roasting properties of pellets with an iron concentrate of complex mineral composition. The results indicated that the pellets of complex mineral composition concentrate required higher pre- heating temperature and longer preheating time than that of single magnetite concentrate. Therefore, it is difficult for preheated pellets to withstand the mechanical collision in the roasting process in rotary kiln. It was found that after the iron concentrate being subjected to high pressure roll grinding, the specific surface area reached 2 029. i cm2/g. Consequently, the preheating and roasting temperature of pellets were decreased by 70 and 50 ℃ and preheating and roasting time were decreased by 2 and 4 min, respectively. Meanwhile, the compression strength of preheated and roasted pellets were increased by 200 N for a pellet and 220 N for a pellet, respectively. The mechanism lied in that the increase of specific surface area activated thermal reaction and promoted formation of inter-grain bridge.
