Solid wastes generated by the metallurgical industry contribute significantly towards the enhancement of environmental pollution. The handling, utilization, and safe disposal of these solid wastes are major concerns f...Solid wastes generated by the metallurgical industry contribute significantly towards the enhancement of environmental pollution. The handling, utilization, and safe disposal of these solid wastes are major concerns for the world. Dolochar is such a solid waste generated by the sponge iron industry. Investigations were carried out on the physical, mineralogical, and chemical characteristics for the efficient utilization of dolochar. The detailed studies on physico-chemical properties and petrography were carded out by optical microscopy, X-ray diffraction （XRD）, and scanning electron microscopy （SEM）. Characterization studies revealed that the dolochar consists of quartz （free as well as locked）, free lime, Fe particles, and Ca or Mg and/or Ca＋Mg＋Fe oxide phases. The washability data of-300 ~m dolochar samples indicated that clean coal with 41wt% ash at 18% yield can be produced from dolochar with 78wt% ash. The studies further suggested that the liberation of the dolochar is hard to achieve for clear separation. The dolochar is observed to have high ash fusion temperature and the un- burned carbon can be best utilized for power generation.展开更多
In recent years,composite pellet production with added reductant has been developed instead of traditional iron production.Composite pellets produced by the addition of appropriate proportions of reductant produce spo...In recent years,composite pellet production with added reductant has been developed instead of traditional iron production.Composite pellets produced by the addition of appropriate proportions of reductant produce sponge iron in the reductant melting process at high temperatures.The elements created in the structure by pellet production directly affect the quality of the product obtained by determining the chemical composition and the appropriate reaction temperature.In this study,sponge iron ore concentrate(scale)and reductant(coke coal dust and sodium bentonite)were mixed at certain proportions to produce composite pellet samples;the effects of addition rate of the reductant material of sodium bentonite(1 wt%−4 wt%)and variation in reaction temperature(900−1200℃)on the metallization and compressive strength properties of the produced composite pellet samples were investigated.The analysis results show that the highest compressive strength is obtained from pellet samples produced with 3%sodium bentonite at 1100℃.Additionally,SEM-EDS analysis results of the samples show that the morphologic structure has much lower porosity rates compared to samples produced under the other conditions which makes the samples denser and increases the metallization properties.展开更多
Conducting complete energy audit (both process and utility) of a sponge iron unit is challenging as there is no laid down procedure to audit the process side. Further, the average heat to power ratio (kWth/kWe) of spo...Conducting complete energy audit (both process and utility) of a sponge iron unit is challenging as there is no laid down procedure to audit the process side. Further, the average heat to power ratio (kWth/kWe) of sponge iron plants ranges from (25:1) to (31:1). This shows that the manufacturing process mostly uses thermal energy and application of electrical energy is insignificant. The main & only source of thermal energy is coal and the entire coal is fed to the rotary kiln. Therefore we find that “Kiln” is the “Black-Box” of this industry and the success of energy efficiency is hidden in the kiln process chemistry. This article tries to establish detailed energy audit methodology of sponge iron manufacturing process or kiln operation with a view to finding out major energy saving potential of the unit. In the research work we find that it is the incomplete reaction of coal that causes the major energy inefficiency in the process. Substantial amount of un-reacted carbon comes out with the char (by-product) which has virtually zero commercial value. The article also puts a question mark on the justification of using high-grade imported coal in such energy inefficient industries.展开更多
基金the Odisha State Pollution Control Board,Bhubaneswar,India
文摘Solid wastes generated by the metallurgical industry contribute significantly towards the enhancement of environmental pollution. The handling, utilization, and safe disposal of these solid wastes are major concerns for the world. Dolochar is such a solid waste generated by the sponge iron industry. Investigations were carried out on the physical, mineralogical, and chemical characteristics for the efficient utilization of dolochar. The detailed studies on physico-chemical properties and petrography were carded out by optical microscopy, X-ray diffraction （XRD）, and scanning electron microscopy （SEM）. Characterization studies revealed that the dolochar consists of quartz （free as well as locked）, free lime, Fe particles, and Ca or Mg and/or Ca＋Mg＋Fe oxide phases. The washability data of-300 ~m dolochar samples indicated that clean coal with 41wt% ash at 18% yield can be produced from dolochar with 78wt% ash. The studies further suggested that the liberation of the dolochar is hard to achieve for clear separation. The dolochar is observed to have high ash fusion temperature and the un- burned carbon can be best utilized for power generation.
文摘In recent years,composite pellet production with added reductant has been developed instead of traditional iron production.Composite pellets produced by the addition of appropriate proportions of reductant produce sponge iron in the reductant melting process at high temperatures.The elements created in the structure by pellet production directly affect the quality of the product obtained by determining the chemical composition and the appropriate reaction temperature.In this study,sponge iron ore concentrate(scale)and reductant(coke coal dust and sodium bentonite)were mixed at certain proportions to produce composite pellet samples;the effects of addition rate of the reductant material of sodium bentonite(1 wt%−4 wt%)and variation in reaction temperature(900−1200℃)on the metallization and compressive strength properties of the produced composite pellet samples were investigated.The analysis results show that the highest compressive strength is obtained from pellet samples produced with 3%sodium bentonite at 1100℃.Additionally,SEM-EDS analysis results of the samples show that the morphologic structure has much lower porosity rates compared to samples produced under the other conditions which makes the samples denser and increases the metallization properties.
文摘Conducting complete energy audit (both process and utility) of a sponge iron unit is challenging as there is no laid down procedure to audit the process side. Further, the average heat to power ratio (kWth/kWe) of sponge iron plants ranges from (25:1) to (31:1). This shows that the manufacturing process mostly uses thermal energy and application of electrical energy is insignificant. The main & only source of thermal energy is coal and the entire coal is fed to the rotary kiln. Therefore we find that “Kiln” is the “Black-Box” of this industry and the success of energy efficiency is hidden in the kiln process chemistry. This article tries to establish detailed energy audit methodology of sponge iron manufacturing process or kiln operation with a view to finding out major energy saving potential of the unit. In the research work we find that it is the incomplete reaction of coal that causes the major energy inefficiency in the process. Substantial amount of un-reacted carbon comes out with the char (by-product) which has virtually zero commercial value. The article also puts a question mark on the justification of using high-grade imported coal in such energy inefficient industries.
