Recycling of mill scale in sintering process

This investigation deals with the effect of replacing some amount of Baharia high barite iron ore concentrate by mill scale waste which was characterized by high iron oxide content on the parameters of the sintering process., and investigation the effect of different amount of coke breeze added on sintering process parameters when using 5% mill scale waste with 95% iron ore concentrate. The results of this work show that, replacement of iron ore concentrate with mill scale increases the amount of ready made sinter, sinter strength and productivity of the sinter machine and productivity at blast furnace yard. Also, the increase of coke breeze leads to an increase the ready made sinter and productivity of the sintering machine at blast furnace yard. The productivity of the sintering machine after 5% decreased slightly due to the decrease of vertical velocity

Thermal Treatment of Titania Slag under Oxidation-Reduction Conditions

The present work provides a method for beneficiating of an Egyptian titanium slag by a thermal oxidation and reduction in a controlled gas atmosphere to obtain leachable slag suitable for use as a feed material in the production of TiO2 by chlorination process. The mechanism of that process has been studied and the proposed reactions are presented. The effect of oxidation on the enrichment of titanium into rutile phase by blowing oxygen into the slag was studied at relatively high temperatures (900-1100 °C) for different times (30-90 min). Heating of a fully divided slag under oxidizing conditions resulted in a major portion of iron in the ferric state Fe3+ and titanium species in Ti4+ state. The results demonstrate that through oxidation, the content of pseudobrookite and rutile phases increase. Reducing of the pre-oxidized slag was carried out using hydrogen gas at 800 °C for different period of times to convert the major portion of iron in ferric state Fe3+ to ferrous state Fe2+. As a result of these treatments most of titania phases were converted into rutile. Thereafter, the reactive ore was treated with aqueous HCl acid then sodium hydroxide solutions to leach impurities to obtain a beneficiated product with an increased TiO2 content

Kinetic reduction of mill scale via hydrogen

Mill scale is very attractive industrial waste since it is rich in iron (about = 72 % Fe) and it is suiTab. for direct recycling to the blast furnace via sintering plant. In this paper the characterizations of raw materials were studied by different methods of analyses. The produced briquettes were reduced with different amounts of hydrogen at varying temperatures, and the reduction kinetics was determined. Two models were applied and the energy of activation was calculated

Removal of Lignin from Pulp Waste Water's Black Liquor via By-Pass Cement Dust

The potential use of inexpensive and available by-pass cement dust as an inorganic sorbent for the removal of organic matter (lignin) from black liquor of pulp wastewater by adsorption methodology was investigated using the batch technique. The cement dust is found to remove lignin efficiently from black liquor (the untreated cement dust (70.47%), the thermally treated one at 1000 °C (78.63%), and chemically treated dust (80.62%). The factors affecting the uptake percentage such as time, dose, pH and temperature were investigated to assess the optimum conditions for lignin removal. X-ray patterns were studied to reveal the relationship between the main constituents of each cement dust phase (untreated, thermally and chemically treated) and lignin uptake. By applying Langmuir and Frendlich adsorption isotherms it was found that the adsorption process of lignin from black liquor on by-pass cement dust achieves Frendlich model, which suggests that adsorption is not restricted to one specific layer of sites but involves multi-layers. Also, stripping of lignin by using different strippers (organic, mineral acids, bases and salts) was investigated. The results obtained show that the organic strippers give high stripping percentage for cyclohexane (90.10%) because lignin is a non-polar compound that dissolves in non-polar solvents. In the case of acids, bases and salts the best results were obtained with much diluted solutions (0.001 mol/L). Stripping of lignin from by-pass cement dust is considered as a way of its recycling for different applications

The Study of the Formation of Sodium Chromate from El-Baramiya High-Silica Chromite Ore Concentrate Using Hydrated Lime

The formation of sodium chromate from a mixture of high-silica chromite ore concentrate (48.8%), soda ash and hydrated lime was investigated. Hydrated lime was added to an optimal mixture of Cr2O3:Na2CO3 (mole ratio 1:2.5) (mole ratio of CaO 0-3) and the materials were roasted at 1000°C for 60 min and PO2 0.21 atm. Results revealed a significant decrease in sodium chromate yield (from 42% to 25%) as the (CaO/Cr2O3) mole ratio increased from 0-0.5. Increasing the (CaO/Cr2O3) mole ratio above 1.0, an optimal chromate yield of 70% was achieved at the mole ratio of 2.5. In addition, roasting of optimal mixtures of soda ash, chromite ore and hydrated lime (CaO) (mole ratio 2.5:1:2.5) within the temperature range of (900-1000 °C) provided a maximum chromate yield of 92% at 1000 °C after 2 hours. Overall, the data revealed that while the hydrated lime addition significantly increased the reaction product yield, it also increased the process energy of activation from 112 kJ/mole for the Na2CO3:Cr2O3 (mole ratio 2.5:1) mixture to 171.6 kJ/mole during roasting time (40-100 minutes)

Studying the pelletization of rosseta ilmenite concentrate with coke breeze using molasses and reduction kinetics of produced pellets at 800-1150ºC

Ilmenite ore fine and coke breeze as reduced material which were pelletized with different amounts of molasses were studied in this investigation. The produced pellets at optimum condition were reduced in nitrogen atmosphere at temperature range 800-1150ºC to determine the controlling mechanism. The reduction indicated that the reduction rates increased as the temperature increased and the controlling mechanism of reaction rate is solid-solid reaction

Effect of recycling blast furnace flue dust as pellets on the sintering performance

The Egyptian Iron and Steel Company generates a great amount of blast furnace flue dust. The recovery of metals and carbon from this flue dust becomes a very important demand due to the increase of the price of coke breeze and the decrease of the primary source of metals. At the same time, it make the environment more safe by decreasing pollution. Introducing these dust fines in the sintering process proves to be very harmful for different operating parameters. Thus, this study aims at investigating the production of pellets resulting from these fines, using molasses as organic binder and its application in sintering of iron ore. The sintering experiments were performed using flue dust as pellets as a substitute of coke breeze. The results revealed that, sintering properties such as inter strength increases with using the flue dust pellets, while productivity of both the sinter machine and sinter machine at blast furnace yard decreases. Also the vertical velocity of the sinter machine and the weight loss during the reduction of produced the sinter by hydrogen decrease

Granulation of coke breeze fine for using in the sintering process

Coke breeze is the main fuel used in the sintering process. The value of -3+1 mm. represents the most favorable particle size for coke breeze in the sintering process. About 20% of total coke fines (-0.5 mm) are produced during different steps of preparation. Introducing these fines during the sintering process proves to be very harmful for different operating parameters. Thus ,this study aims at investigating the production of granules resulting from these fines using molasses as organic binder and its application in sintering of an iron ore. The results showed that the granules having the highest mechanical properties were obtained with 14.5 wt % molasses addition. The sintering experiments were performed by using coke breeze in different shapes (-3+1 mm in size, coke breeze without sieving and coke breeze granules -3+1 mm). The reduction experiments, microscopic structure and X-ray analysis for the produced sinter were carried out. The results revealed that, all sinter properties (such as shatter test, productivity of sinter machine and blast furnace, reduction time and chemical composition) for produced sinter by using coke breeze with size -3+1 mm and coke breeze granules were almost the same. The iron ore sinter which was produced by using coke breeze without sieving yielded low productivity for both sinter machine and blast furnace. Furthermore, using coke breeze without sieving in sintering of an iron ore decreases the vertical velocity of sinter machine and increases the reduction time

Efektywność procesu rozdziału w osadzarce

There are many parameters affecting of the sintering process such as: amount of water added, basicity of sinter, amount of sinter return, amount of coke breeze, any addition of iron bearing material (mill scale) and time of ignition. Thus the aim of this work is devoted to study the optimum condition for sintering process of the Egyptian iron ore.Istnieje wiele parametrów mających wpływ na proces spiekania: ilość dodanej do procesu wody, odczyn pH spieku, ilość pyłu koksowego, każdy dodatek stopu żelaza oraz czas zapłonu. Celem pracy jest określenie optymalnych warunków dla procesów spiekania rud żelaza w Egipcie