Effect of Na2CO3 and CaCO3 on Coreduction Roasting of Blast Furnace Dust and High-phosphorus Oolitic Hematite

Iron was recovered from blast furnace dust and high-phosphorus oolitic hematite in the presence of Na2CO3 and CaCO3 additives. The functions of Na2CO3 and CaCO3 during the coreduction roasting process were investigated by XRD and SEM-EDS analyses. Results indicate that these additives not only hinder the reduction of fluorapatite, CaCO3 also decreases the P content of direct reduced iron（DRI） by increasing the reduction alkalinity. P remains as fluorapatite in the slag, which can be removed by grinding and magnetic separation under optimal conditions. The Na2CO3 promotes hematite reduction and improves the iron recovery（εFe） by replacing the FeO from fayalite, which results in quick growth and aggregation of metallic iron and improvement of ε（Fe） in DRI. A DRI with 91.88 mass% Fe, and 0.065 mass% P can be achieved at a recovery of 87.86 mass% under the optimal condition.

MORPHOLOGICAL,MECHANICAL,THERMAL AND TRIBOLOGICAL PROPERTIES OF ENVIRONMENTALLY FRIENDLY CONSTRUCTION MATERIALS:RECYCLED LDPE COMPOSITES FILLED BY BLAST FURNACE DUST

This study focused on developing a sustainable composite material using metallic wastes of the iron-steel industry and plastic wastes of the plastic industry in order to reduce resultant waste from the production processes of various industrial products and to sustain waste management of these industries.In this study,different amounts of blast furnace dust(BFD),which is the major iron-steel industry waste and is used as filler for recycled low-density polyethylene(LDPE),was mixed with LDPE to produce the composite material.The morphology,mechanical,vicat softening temperature thermal conductivity,hardness and wear resistance properties of BFD filled LDPE composites were assessed.The increasing of BFD in recycled LDPE improved the heat resistance,increased thermal conductivity and wear resistance of composite materials.In addition,it was found that the composite materials had sufficient mechanical properties,when mechanical tests were evaluated.These results showed that the produced composite material could be used in buildings as a floor coating material and thereby saving raw materials and resources,as well as potentially reducing environmental problems.

Effect of CacO_(3) on volatilization of self-reduced zinc from blast furnace dust

To solve the problem of low reduction extraction rate of zinc from blast furnace dust,the effects of CacO3 addition,reduction temperature,and reduction time on self-reduction zinc extraction were studied through high-temperature reduction experiment,and the mechanism of how CaCO_(3) addition promotes zinc ferrite reduction was analyzed.The zinc removal rate can reach 98.82%when the blast furnace dust is reduced at 1000℃ for 25 min by adding 10 mass%CaCO_(3).At low temperature,CaCO_(3) can enhance the reduction and decomposition of ZnFe_(2)O_(4)(which is difficult to reduce)into ZnO and low-valent iron oxides.After CaCO_(3) is decomposed at high temperature,CO_(2) is produced to undergo gasification reaction with carbon in blast furnace dust,and co is generated to provide more reducing agents for the whole reduction system.CaO generated by decomposition can also catalyze the gasification reaction of carbon,thus improving the removal rate of zinc in the reduction process of dust.

Study on the volatilization kinetics of lead in carbon- containing pellets made of Zn- Pb- bearing dusts

This study investigated the volatilization kinetics of lead in pellets made of Zn-Pb-bearing dusts mixed with coal powder,in a nitrogen atmosphere and in the temperature range between 1 100 ℃ - 1 300℃ ,and showed that the reduction temperature has a significant effect on the volatilization rate of lead and that neither the particle size of the coal powder nor the extra carbon content has any effect on the volatilization rate. The obtained activation energy for the volatilization of lead is 88.74 kJ/mol. The volatilization rate of lead is controlled by both the lead evaporation reaction and the diffusion of gaseous lead through the gas boundary layer covering the surface of the reduced liquid lead.

Study on the volatilization kinetics of zinc in carbon-containing pellets made of Zn-bearing dusts

A study was carried out on the volatilization kinetics of Zn in the pellets made of Zn-bearing dusts mixed with coal powder in a nitrogen atmosphere and within the temperature range between 1 100℃and 1 300℃. The study shows that the reduction temperature has a significant effect on the volatilization rate of zinc and that either the coal particle size or the excess carbon content has no effect on the volatilization rate. The obtained activation energy for the volatilization of zinc is 79.42 kJ/mol. The volatilization rate of zinc is controlled by the reaction between the zinc oxides and CO.