Sinter Pot Tests Research Articles

Optimization of Dolomite Usage in Iron Ore Sintering Process

To achieve the action mechanism and optimal usage of dolomite in the sintering process, solid reaction tests, fluidity tests, bonding strength tests and sinter pot tests were conducted, then microstructure and energy spectrum were analysed further. Reaction temperature of dolomite with calcium ferrite was lower than that with limonite iron ore about 155°C. Fluidity of bonding phase and strength of sinter using dolomite were lower than that using light burned dolomite and serpentine owing to the higher MgO content in the calcium ferrite and formation of secondary bonding phase. Action mechanism of dolomite in sintering process mainly included 4 steps, thermal decomposition, solid reaction, formation of primary bonding phase and formation of secondary bonding phase. Dolomite mainly played it’s role in the third step in which high viscosity CFM (calcium ferrite with MgO) and magnetite solid solution formed. Increasing the solid solubility of MgO in magnetite by mixing dolomite with magnetite concentrate before granulation, decreasing the dispersity of MgO in sinter mixture by increasing the particle size of dolomite appropriately, increasing the separation degree of MgO and CaO by light-burning the dolomite, and decreasing the reaction amount of MgO by using big particle size magnesia, all could decrease the content of MgO in calcium ferrite, thus showed good performance in sinter pot tests.

Reduction of CO2 Emissions by Use of Pre-reduced Iron Ore as Sinter Raw Material

In order to reduce CO2 emissions at an ironmaking process, it is an effective measure to decrease a bonding agent rate at an iron ore sinter plant. In this study, effect of using a pre-reduced iron ore as a part of a sinter raw material on a sintering process was investigated mainly from a viewpoint of decreasing a bonding agent rate.Two brands of pisolitic iron ores were reduced up to wustite at 1173 K with reducing gas of which an oxidation degree was 55%. The pre-reduced iron ore was stable against reoxidation in the atmosphere and through a cyclic wet and dry treatment.Two brands of pisolitic iron ores and a Marra Mamba iron ore were pre-reduced and then used in a sinter pot test. A use of the pre-reduced iron ore was effective in decreasing a bonding agent rate at a given productivity. The reoxidation heat of the pre-reduced iron ore was estimated to be less than the combustion heat of the bonding agent being saved by use of the pre-reduced iron ore. The reoxidation heat is more effective in the sintering process than the combustion heat. The decrease of the bonding agent resulted in reduction of NOx emissions.A mass and heat balance shows that a use of a pre-reduced iron ore as a sinter raw material enables reduction of CO2 emissions not only at an ironmaking process but also at a whole integrated steel works.

Utilization of Biomass for Iron Ore Sintering

Decrease of carbon dioxide emission is a serious subject in the steel works. Utilization of biomass as a carbon-neutral agent is an attractive one for iron ore sintering. Sinter pot tests were carried out with using raw biomass and biomass carbonized char. It is not good on yield and exhaust gas that raw biomass is used directly as carbon material for iron ore sintering. While, it is good on the productivity and the exhaust gas (NOx, SOx, dust, dioxins) that biomass carbonized char is used as carbon material. With using biomass char for the sintering, it is necessary to optimize operation (size control and moisture control of the biomass char), because combustion rate of the biomass char is too high. Biomass carbonized char is evaluated on sinter yield as similar as anthracite or coke. The biomass char is effective to decrease CO2, NOx, SOx, dust etc. emission in sinter exhaust gas.

Sintering Properties and Optimal Blending Schemes of Iron Ores

In order to obtain good sintering performance, it is important to understand sintering properties of iron ores. Sintering properties including chemical composition, granulation and high-temperature behaviors of ores from China, Brazil and Australia. Furthermore, several indices were defined to evaluate sintering properties of iron ores. The results show that: for chemical composition, Brazilian ores present high TFe, low SiO2, and low Al2O3 content. For granulation, particle diameter ratio of Brazilian ores are high; particle intermediate fraction of Chinese concentrates are low; and average particle size and clay type index of Australian ores are high. For high-temperature properties, ores from China, Brazil and Australia present different characteristics. Ores from different origins should be mixed together to obtain good high-temperature properties. According to the analysis of each ore's sintering properties, an ore blending scheme (Chinese concentrates 20% + Brazilian ores 40% + Australian ores 40%) was suggested. Moreover, sinter pot test using blending mix was performed, and the results indicated that the ore blending scheme led to good sintering performance and sinter quality.

Operating condition influences on PCDD/Fs emissions from sinter pot tests with hot flue gas recycling

This study was designed to clarify the influence of operating conditions on the formation and emissions of polychlorinated-p-dibenzodioxins and dibenzofurans (PCDD/Fs) from a sintering process with hot flue gas recycling. A pilot scale sinter pot with simulated flue gas recycling was developed, and four key operational parameters, including temperature, oxygen content of the simulated waste flue gas, the coke rate of the sintering mixture, and the quicklime quality, were selected for exploring PCDD/Fs formation. The results showed that the temperature of the recycled flue gas had a major affect on PCDD/Fs formation, and a high temperature could significantly increase their formation during sintering. A clear linear correlation between the temperature of recycling flue gas and PCDD/Fs emission (r = 0.93) was found. PCDD/Fs could be reduced to a certain extent by decreasing the level of oxygen in the recycled flue gas, while sintering quality was unchanged. The coke rate had no significant influence on the formation of PCDD/Fs, but the quality of quicklime used in the sintering mixture could affect not only the amount of PCDD/Fs emissions but also the sintering productivity. Compared with a benchmark sinter pot test, PCDD/Fs emissions markedly decreased with improvements to quicklime quality. However, the reduction in PCDD/Fs emissions realized by using high-quality quicklime was limited by the temperature of the inlet gas. The highest reduction achieved was 51% compared with conventional quicklime when the temperature of the inlet gas was 150°C.

Prediction of Iron Ore Sintering Characters on the Basis of Regression Analysis and Artificial Neural Network

Iron ore sintering is a complex and hysteresis process, so the prediction of the iron ore sintering character is very necessary. By using stepwise regression analysis, this paper confirms the main factors that influence moisture content, fuel ratio, sintering speed and the sintering drum strength. By using BP artificial neural network, we construct the prediction model against the four characters mentioned afore, and prediction accuracy are 96.67%, 93.33%, 86.67% and 93.33% respectively. The model result used in sintering pot test, the experimental results show that the mix moisture and fuel ratio are optimized, and the sinter drum strength is improved.

Numerical Modeling of the Iron Ore Sintering Process

Iron ore sintering involves the movement of a flame front down a particulate bed, and a series of physico-chemical reactions over a large temperature range. In the literature simple and more sophisticated iron ore sintering models have been reported. In this paper a more comprehensive numerical model which incorporates most of the significant processes and heat transfer modes proposed in earlier models is given. Therefore, sub-models are available to describe the relationship between airflow rate through the bed and flame front speed, the evaporation and condensation of water ahead of the front, the calcination of fluxes nearer to the front, the reactions that occur in the front and cooling of the bed with the departure of the front. Improvements were made to several areas – such as coke combustion, and the melting and solidification processes – to more accurately quantify the phenomena involved. More recent progress in understanding the fundamentals of sintering from BHP Billiton studies have also been incorporated into the model. To date, twelve sinter pot tests have been used for validation studies. Reasonably good agreement was obtained between predicted and measured results – in areas such as bed temperature profiles and waste gas temperature and compositions. Work is continuing to further improve the model, and broaden the validation work to include other bed temperature profile parameters.

Lower fuel consumption model and air-flow segregation feeding system for sintering

In order to utilize the spontaneous accumulation of heat (SAH) reasonably and obtain the high quality sinter with low energy consumption, a lower fuel consumption modeling based on raw materials of a certain steel works was built. An air-flow segregation feeding (ASF) experimental equipment was designed to simulate strand feeding process and calculate the lower fuel consumption quantity. Compared with baseline test, the ASF experimental equipment was adopted. The results of sinter pot tests show that the solid fuel consumption is lower than that in baseline test, which is decreased by 5.8%. Meanwhile, other sinter indexes, such as pan yeild, tumbler strength and strand productivity are improved. The mineralogical examination indicates that the mineral compositions and micostructures are improved in sinter.

Research on Ore-Proportioning Optimization Technology in Sintering

In this paper, self-characteristics (the room-temperature characteristics and the high-temperature characteristic) of iron ores used in sintering, such as chemical composition, size distribution, assimilation, liquid phase fluidity, self-strength of bonding phase, etc, were studied. Then, the principles of ore-proportioning optimization basing on self-characteristics of iron ore during sintering were proposed. Schemes of ore-proportioning optimization were designed and sinter pot test were carried out．Results of sinter pot confirmed the method of optimizing ore proportioning based on iron ore self-characteristics. This work provides good countermeasure for improving sinter quality and reducing sinter cost as soon as possible, under the condition of making full use of the existing iron ore resources.

Mixed State and High Effective Utilization of Pilbara Blending Iron Ore Powder

Pilbara blending iron ore powder (PB powder) is blending ores with good and poor quality iron ores, so how to use PB power effectively is a problem. The self-characteristics of PB powder and its single-components were studied respectively, such as the macroscopic properties, microscopic properties, and high-temperature properties; the behavior and effect in the sintering were mastered. Then based on the new ore-proportioning idea of iron ores sintering characteristics complementary, the principles on the effective use of PB powder were discussed, and was further validated through the sintering pot test and industrial production. The results show that; PB powder is composed of three kinds of iron ore, and the sintering characteristics of different iron ores are obviously discrepant. With the ore-proportioning optimization based on the iron ores sintering characteristics complementary, the proportion of PB iron ore powder can be increased to more than 455%.

NO x reduction by coupling combustion with recycling flue gas in iron ore sintering process

A new process called ‘NOx reduction by coupling combustion with recycling flue gas (RCCRF)’ was proposed to decrease NOx emission during the iron ore sintering process. The simulation test of NOx reduction was performed over sintered ore and in the process of coke combustion. Experimentally, NOx reduction was also carried out by sintering pot test. For sintered ore, the amount of NOx emission is reduced by 15wt%–25wt% at 400–550°C using 2.0vol% H2 or 2.0vol% CO, or reduced by 10wt%–30wt% at 560–720°C using 0.15vol% NH3. NOx reduction is around 10wt% by coupling combustion of pyrolysis gas and coke, or around 16wt% by recycling flue gas into coke combustion. By RCCRF, the maximum NOx reduction ratio is about 23wt% in coke combustion experiment and over 40wt% in sintering pot test.

Sintering characteristics of fluxes and their structure optimization

Sintering characteristics of common fluxes and sintering blending ores, such as mineralization capacity, liquid generation capacity, consolidation strength, were examined to master the behavior and effect of fluxes in sintering. Based on fundamental studies, sinter pot tests were carried out to obtain the principles of optimizing the sinter flux structure. The results showed that strong mineralization capacity, liquid phase generation capacity, and consolidation strength were obtained as sintering blending ores combined with the calcareous flux, while relatively poor sintering characteristics were obtained as sintering blending ores combined with the magnesian flux. High reactive quicklime should be used as much as possible in the sintering mixture. It reached better sintering results while quicklime was used instead of limestone and its appropriate proportion in the sintering mixture was around 4wt%. On the premise of ensuring the MgO content, the dolomite amount should be decreased, and the substitution of quicklime for dolomite caused better sintering results. The granularity of serpentine should be refined with a proper size smaller than 2 mm. The application of the divided addition method brought the best sintering performance with 30wt% of quicklime and 70wt% of fuel.

Research on High-Temperature Properties of Typical Iron Ores Used in China and its Blending Optimization

High-temperature properties of 10 samples of iron ore from Brazil, Australia and China were measured. Several conclusions were made based on these experimental results. Assimilability of Brazilian ore, Australian ore and Chinese ore concentrate were low, high and medium, respectively. Optimal fluidity of liquid phase was observed in 2 types of Brazilian ores (BR-B, BR-C), 1 type of Australian ore (AU-C) and 1 type of Chinese ore (CH-D). For self-strength of the bonding phase, Australian ore presented low levels, while Brazilian and Chinese ore presented high levels. According to the experimental results of high-temperature properties of iron ore, schemes of ore blending optimization were designed and sinter pot test using these blends were performed. The results indicated that ore blends composed of 30~45% Brazilian ores + 25~50% Australian ores + 20~30% Chinese concentrates presented excellent sintering results, considering both the performance of the processing and quality of the sinter. Therefore this experiment has proved that ore blending optimization combining high temperature properties can lead to more efficient sintering mixes.

Influence of CeO 2 on NO x emission during iron ore sintering

The evolution of NO x during coke combustion in the presence and absence of CeO 2 was studied in a quartz fixed bed reactor. The distribution of CeO 2 in the coke was examined by SEM, and the effects of CeO 2 loading and CeO 2 particle size on NO x emission were discussed. NO x emission was also investigated by sintering pot tests with CeO 2 modified coke as sintering fuel. The results showed that CeO 2 was catalytically active in promoting not only coke combustion but also NO x reduction. SEM examination indicated that the CeO 2 particles were well distributed on the surface and in pore canals of coke. In coke combustion experiments, NO x and CO emission decreased with increasing CeO 2 loading up to 2.0 wt.% and decreasing CeO 2 particle size (28–150 µm), while sintering pot tests showed that NO x emission decreased by 18.8% with 2.0 wt.% CeO 2 modified coke as sintering fuel.

NO x reduction in the sintering process

A new process, NO x reduction with recycling flue gas and modifying coke breeze, was proposed. The effects of modified coke breeze and recycled flue gas on NO x reduction were investigated by sinter pot tests. The results show that the NO x reduction rate is over 10wt% in the sintering of modified coke breeze, the effects of the additives on NO x reduction are: CeO 2>CaO>K 2CO 3. The NO x reduction rate increases with the amount of recycled flue gas, and is 22.35wt% in the sintering with recycling 30vol% of the flue gas. When 30vol% of the flue gas is recycled into the sintering of CeO 2, CaO, and K 2CO 3 modified coke breeze, the NO x reduction rates are 36.10wt%, 32.56wt%, and 32.17wt%, respectively.

Production of Carbon Included Sinter and Evaluation of Its Reactivity in a Blast Furnace Environment

Recently, the reduction in the amount of the CO2 emission has become an important issue. It is important to increase the reactivity of iron sources used in a blast furnace to decrease of CO2 emission. Therefore, the carbon composite iron ore agglomerates are significant. The production experiments of a new agglomerate named CIS (Carbon Included Sinter), where green balls were granulated by a model pan pelletizer were carried out using pot tests. The reduction of produced CIS with CO–CO2 gas mixture were examined, and were compared with that of ordinary sinter ore. Also, the softening and melting property tests of 50% CIS–50% sinter mixed layer were carried out and compared with the results using 100% sinter layer. The results are summarized as follows:(1) A new agglomerate, which an anthracite particle was surrounded by a shell with the same components as ordinary sinter ore, was produced by sintering pot test.(2) When CIS was reduced by CO–CO2 gas mixture at 1273 K, the degree of reduction achieved 80% in 120 min, even though ordinary sinter ore achieved less degree of reduction.(3) 250 g CIS–250 g ordinary sinter ore packed bed achieved 1/3 maximum pressure drop of 500 g ordinary sinter ore packed bed in the softening-melting property test.

Optimization of Coke Breeze Segregation in Sintering Bed under High Pisolite Ore Ratio

Increased demand and the diminishing high grade resources have resulted in a shift to using low grade iron ore in Japanese steel mills. Especially, pisolite ore ratio is quite high. Therefore, decrease in sinter productivity became serious problem with increasing the amount of pisolite ore.To improve the sinter productivity, effective method at the charging device in sintering machine was investigated by laboratory experiments.The following results were obtained.1) It was expected that the holding time over 1200°C at the middle and bottom layer of the sintering bed decreased with high pisolite ore ratio. On the other hand, in order to preserve the sinter strength, it was suggested that the holding time over 1200°C in sintering must be extended under high pisolite ore ratio.2) There is the optimum coke segregation degree according to the pisolite ore ratio. It was decreased with increase of the pisolite ore ratio.3) To control the coke segregation in the sintering bed, Magnetic Braking Feeder (MBF) was introduced, and the operating conditions were investigated with the laboratory charging tests and sintering pot test.4) Based on the fundamental research, MBF has been applied to Keihin No. 1 sinter plant, and the productivity was improved by 4.2% under constant sinter strength.

Application of Modified Coke to NOx Reduction with Recycling Flue Gas during Iron Ore Sintering Process

A new process, named NOx reduction by the modified coke with recycling flue gas, was proposed. The coke samples loaded with K2CO3, CaO and CeO2 were characterized by SEM. The effects of the recycled flue gas and the modified coke on NOx reduction were investigated with a quartz fixed bed reactor and a sintering pot. The results showed that the extent of the contact between additives and coke was: K2CO3>CaO>CeO2. In the modified coke combustion with recycling flue gas, the concentration of NOx emission was decreased, furthermore, the NOx reduction ratio increased with the loading amount of additives. The NOx reduction ratios were 36.7%, 20.2% and 26.2% respectively when the loading amount of K2CO3, CaO and CeO2 was 2.0%. In sintering pot tests, the coke loaded with 2.0% CeO2 was used as fuel and the recycled flue gas, simulated by the gas mixture with 50 ppm NO, was introduced to sintering process, the NOx reduction ratio was 38.0%, which was about 13% higher than that of the base run with recycling flue gas.

Sintering Pot Test of Manganese Ore with Addition of Manganese Furnace Dust

Manganese furnace dust is formed from volatiles and fines collected during wet scrubbing of the off-gas from manganese alloy smelting furnaces. This dust, in the form of slurry, contains tar, alkalies, zinc, manganese oxide and other elements. Impediments to the recycling of the manganese furnace dust back to the ferroalloy furnaces are the potential accumulation of zinc and alkalies, which can cause irregularities in furnace operation, and handling. This paper examines the behaviour of zinc during sintering pot tests of manganese ore with addition of manganese furnace dust. Laboratory reduction experiments showed that at temperatures above 800°C zinc oxide was reduced by carbon in tar to zinc vapour. However, zinc removal in sintering pot tests was below 30%, which was attributed to reoxidation of the zinc vapour. Zinc removal was the highest from the bottom section of the sintering pot bed.

Fundamental Insights into the Sintering Behaviour of Goethitic Ore Blends

The main purpose of this paper is to examine the effect of altering the sintering parameters—viz., bed height, suction, and the levels of return sinter fines, coke, mix moisture, and limestone—of two blends, one containing over 50 mass% pisolite ore and the other 50 mass% pisolite ore and 30 mass% Marra Mamba ore. Pre- and post-ignition airflow rates were determined together with the traditional performance measures i.e., sintering time, yield, productivity, coke rate and sinter tumble index. Results from such a study provide useful information on tolerable variations in the sintering process parameters and insights into which are the more important parameters controlling sinter plant performance. Sinter pot test results show significant changes in airflow rates and sintering performance when the sintering parameters were altered, although the two blends did not always respond in the same manner. Many of the obtained relationships (e.g. increasing bed height results in the formation of stronger sinter) are well known, but in this study explanations on why and how the relationships exist are given. It is clear from this study that the temperature of the flame front, which has a significant influence on flame front permeability and the melt formation process, has a very large influence on sintering performance and the strength of the ensuing sinter product.