Characterization of Ring Deposits Inside a Quicklime Producing Long Rotary Kiln

Eriksson, Matias; Carlborg, Markus; Broström, Markus

doi:10.1021/acs.energyfuels.9b00865

Cited by 14 publications

(8 citation statements)

References 19 publications

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“…To reduce the residence time and increase production capacity, the quicklime temperature in a lime kiln reaches 1100-1450 • C [15,16], far exceeding the calcination temperature of 800-900 • C. After calcination, the quicklime continues to exhibit phase transformations as the temperature in the lime kiln increases, and the final phase composition will depend on the maximum temperature reached. Eventually, the final product quality is also influenced by cooling, post-processing such as crushing and sieving, storage, and transport to the end user.…”

Section: Introductionmentioning

confidence: 99%

Impact of Limestone Surface Impurities on Quicklime Product Quality

Eriksson,

Sandström,

Carlborg

et al. 2024

Minerals

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Quicklime is produced through the thermal processing of limestone in industrial kilns. During quarry operations, fine particulate quarry dust adheres to limestone lump surfaces, increasing the bulk concentration of impurities in limestone products. During thermal processing in a kiln, impurities such as Si, Mg, Al, Fe, and Mn react with Ca, reducing quicklime product quality. Which reactant phases are formed, and the extent to which these result in a reduction in quality, has not been extensively investigated. The present study investigated as-received and manually washed limestone product samples from two operational quarries using elemental compositions and a developed predictive multi-component chemical equilibrium model to obtain global phase diagrams for 1000–1500 °C, corresponding to the high-temperature zone of a lime kiln, identifying phases expected to be formed in quicklime during thermal processing. The results suggest that impurities found on the surface of the lime kiln limestone feed reduce the main quality parameter of the quicklime products, i.e., calcium oxide, CaO (s), content by 0.8–1.5 wt.% for the investigated materials. The results also show that, in addition to the effect of impurities, the quantity of CaO (s) varies greatly with temperature. More impurities result in more variation and a greater need for accurate temperature control of the kiln, where keeping the temperature below approximately 1300 °C, that of Hatrurite formation, is necessary for a product with higher CaO (s).

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Section: Introductionmentioning

confidence: 99%

Impact of Limestone Surface Impurities on Quicklime Product Quality

Eriksson,

Sandström,

Carlborg

et al. 2024

Minerals

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“…Deposit formation in a rotary kiln is frequently observed in iron ore pellet production by the grate-kiln process, disturbing normal production and decreasing productivity . The deposit of fluxed iron ore pellets is more severe than acidic iron ore pellet production. , …”

Section: Introductionmentioning

confidence: 99%

“…10 The deposit of fluxed iron ore pellets is more severe than acidic iron ore pellet production. 11,12 Many researchers 13−19 have focused on the deposition mechanism in rotary kilns for acidic iron ore pellet productions. In the rotary kilns fueled by pulverized coal, preheated iron ore pellet powder and coal ash are the material basis for deposit formation.…”

Section: Introductionmentioning

confidence: 99%

Effects of Pellet Basicity on the Simulated Deposit Formation in Coal-Fired Rotary Kilns for Iron Ore Pellet Production

et al. 2022

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Deposit formation in the coal-fired rotary kiln is frequently found in the production of fluxed iron ore pellets by the grate-kiln process and affects normal production. In this paper, the effects of pellet basicity (CaO/SiO2 mass ratio) on the simulated deposit formation were investigated. The results show that the porosity of deposits samples increases from 30.8 to 41.5% as the pellet basicity increases from 0.6 to 1.2, and most of the holes are irregular in shape. The contents of CaO and Fe2O3 in the silicates of the deposit samples increased with increasing basicity. The primary phase of the deposit samples changed from the M2O3 phase region to the clinopyroxene phase region with a lower melting point. As the basicity increased, the calculated proportions of the liquid phases in the deposit samples had an increasing trend. Moreover, the deposit sample adhesion to the refractory brick increases with the increase in pellet basicity.

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“…Several studies have analyzed mature deposits formed in industrial rotary kilns, calciners, and preheaters. − An overview of the crystalline phases found in mature deposits formed during cement production and their typical locations are shown in Table .…”

Section: Introductionmentioning

confidence: 99%

“…Controlling the amount of volatile constituents in any local part of the kiln charge was recommended as a precautionary measure to prevent the formation of the coating. Eriksson et al 32 sampled ring deposits from a rotary kiln when the plant was shut down and identified three hardening mechanisms of the deposits, referring to the increased densification of ring deposits, the formation of calcite and spurrite, and the intrusion of molten fuel ash into the refractory, resulting in a strong attachment of the deposit to the refractory. Belgacem et al 24 investigated the form and amount of the compounds in different deposit samples from the kiln inlet and proposed that the fluctuating operating temperature and the low calcination degree were the main reasons for the ring formation and growth.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of Mineral Particle Deposition in the Cement Production Process

et al. 2022

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This study aims to improve the understanding of the formation and prevention of deposits caused by the introduction of alternative fuels in the cement industry. Experiments were conducted with cement mineral materials in a laboratory-scale entrained flow reactor. To simulate the temperature conditions in a cement calciner, two different deposit probe systems were used: a high probe surface temperature (HPST) deposit system with a probe surface temperature range of 700–1200 °C and a low probe surface temperature (LPST) deposit system with a probe surface temperature range of 500–700 °C. The effects of fed materials (raw meal, hot meal, bypass dust), flue gas temperature (700–1200 °C), deposit probe surface temperature (550–1200 °C), gas velocity (0.9–2.7 m/s), and experimental duration (5–60 min) on the deposit formation rate were investigated. The results revealed that the concentration of KCl in the fed materials has a large influence on deposit formation. In HPST experiments with furnace temperatures ranging from 700 to 1100 °C, the bypass dust has a higher deposition rate than hot and raw meals, due to a large amount of K and Cl (>10 wt %) in the bypass dust, which forms melts and increases the stickiness between impacting particles and deposits. In LPST experiments, the presence of KCl facilitated the deposit formation rate by providing a sticky layer on the deposit probe via condensation, resulting in a higher deposition rate of bypass dust than the raw meal. An increase in gas velocity showed a negative effect on the deposit formation rate due to an increase in rebound. The present study suggests that keeping the calciner wall temperature at 900–1100 °C and a low level of KCl content would effectively reduce the deposit formation, thereby increasing the equipment life and reducing the operating cost during cement production.

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Characterization of Ring Deposits Inside a Quicklime Producing Long Rotary Kiln

Cited by 14 publications

References 19 publications

Impact of Limestone Surface Impurities on Quicklime Product Quality

Impact of Limestone Surface Impurities on Quicklime Product Quality

Effects of Pellet Basicity on the Simulated Deposit Formation in Coal-Fired Rotary Kilns for Iron Ore Pellet Production

Experimental Investigation of Mineral Particle Deposition in the Cement Production Process

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