Multisource Data Ensemble Modeling for Clinker Free Lime Content Estimate in Rotary Kiln Sintering Processes

2015 ◽  
Vol 45 (2) ◽  
pp. 303-314 ◽  
Author(s):  
Weitao Li ◽  
Dianhui Wang ◽  
Tianyou Chai
Keyword(s):  
Rotary Kiln ◽  
Ensemble Modeling ◽  
Free Lime ◽  
Lime Content ◽  
Sintering Processes

scholarly journals Preparation of β-belite using liquid alkali silicates

2017 ◽  
Vol 67 (328) ◽  
pp. 140 ◽  
Author(s):  
P. Koutník
Keyword(s):  
Silica Fume ◽  
Raw Materials ◽  
Mineralogical Composition ◽  
Potassium Silicate ◽  
X Ray Diffraction ◽  
Free Lime ◽  
Burning Temperature ◽  
Lime Content ◽  
Powdered Limestone ◽  
Alkali Silicates

The aim of this study is the preparation of β-belite by a solid-state reaction using powdered limestone, amorphous silica and liquid alkali silicates. The raw materials were blended, the mixtures were agglomerated and then burnt. The resulting samples were characterized by X-ray diffraction analysis and scanning electron microscopy. Free lime content in the β-belite samples was also determined. The effects of CaO/SiO2 ratio (1.6–2.1), burning temperature (800–1400 °C), utilization of different raw materials (silica fume, synthetic silica, potassium silicate, sodium silicate, potassium hydroxide) and burning time (0.5–16 h) on free lime content and mineralogical composition were investigated. The purest ?-belite samples were prepared from a mixture of powdered limestone, silica fume and liquid potassium silicate with a ratio CaO/SiO2 = 2 by burning at temperatures between 1100 and 1300 °C for more than 2 h. Decreasing of the CaO/SiO2 ratio led to rankinite formation and lower a burning temperature led to the formation of wollastonite.

Measurement of free lime content in lime mud

TAPPI Journal ◽  
2015 ◽  
Vol 14 (7) ◽  
pp. 481-489 ◽  
Author(s):  
XIAOSONG MAO ◽  
WEI REN ◽  
HONGHI TRAN
Keyword(s):  
Thermal Decomposition ◽  
Systematic Study ◽  
Kraft Pulp ◽  
Measurement Methods ◽  
Pulp Mills ◽  
Free Lime ◽  
Lime Content ◽  
Lime Kilns ◽  
Lime Mud ◽  
Kraft Pulp Mills

Overliming and the consequent presence of unreacted lime (or free lime) in the lime mud are commonly believed to be the cause of many problems in the operation of causticizing plants and lime kilns in kraft pulp mills. The free lime content in lime mud is typically determined in mill laboratories using a so-called ammonium chloride (NH4Cl) method and in commercial laboratories using a thermal decomposition (TD) method. Over the years, we analyzed many lime mud samples from mills and found that the free lime content was consistently low, < 3 wt% calcium hydroxide (Ca(OH)2), even in cases where overliming was suspected to have caused problems. A systematic study was therefore conducted to investigate the validity of free-lime measurement methods, the reason for the consistently low free lime content in lime mud, and if free lime values can be used to indicate overliming. The results show that the NH4Cl method is not suitable for determining free lime. The TD method is good, but the possible interference of magnesium hydroxide (Mg(OH)2) must be taken into account. Since most pulp mills perform their free lime analysis on mud samples collected from pre-coat filters which have been washed, the resulting free lime value is low, and thus, cannot be used to assess the extent of overliming in the causticizing plant.

Effect of free lime content on properties of cement–fly ash mixtures

2013 ◽  
Vol 38 ◽  
pp. 829-836 ◽  
Author(s):  
Krittiya Kaewmanee ◽  
Pitisan Krammart ◽  
Taweechai Sumranwanich ◽  
Pongsak Choktaweekarn ◽  
Somnuk Tangtermsirikul
Keyword(s):  
Fly Ash ◽  
Free Lime ◽  
Lime Content

Prediction of free lime content in cement clinker based on RBF neural network

2012 ◽  
Vol 27 (1) ◽  
pp. 187-190 ◽  
Author(s):  
Jingling Yuan ◽  
Luo Zhong ◽  
Hongfu Du ◽  
Haizheng Tao
Keyword(s):  
Neural Network ◽  
Rbf Neural Network ◽  
Cement Clinker ◽  
Free Lime ◽  
Lime Content

Understanding the Behavior of Calcium Compounds in Petroleum Coke Fluidized Bed Combustion (FBC) Ash

2006 ◽  
Vol 128 (4) ◽  
pp. 290-299 ◽  
Author(s):  
E. J. Anthony ◽  
L. Jia ◽  
S. M. Burwell ◽  
J. Najman ◽  
E. M. Bulewicz
Keyword(s):  
Particle Size ◽  
Fluidized Bed ◽  
Petroleum Coke ◽  
Bound Water ◽  
Mineral Matter ◽  
Fluidized Bed Combustion ◽  
Free Lime ◽  
Size Fractions ◽  
Lime Content ◽  
Calcium Compounds

With growing understanding of the differences between solid residues from the fluidized bed combustion of petroleum coke and of coal, the significance of fuel-derived and sorbent-derived components of the ash has become clearer. It is well documented that hydration of the ashes is necessary prior to disposal or utilization or as a reactivation method. Initially, hydration of the lime was thought to involve water reacting only with CaO to form Ca(OH)2 but when the free lime content of the ashes is looked at before and after hydration, it is apparent that the process is more complex. Detailed analyses have shown that the free lime can decrease and vary within the same ash in different particle size ranges. The complexity of the reactions is reflected in problems with the assessment of the free lime content of the materials and the effect of hydration on different particle size fractions of the ash. The free lime content of the ash is significantly lower than expected based on the elemental analysis. Bed ash from the circulating fluidized bed combustion boilers owned and operated by the Nelson Industrial Steam Company Ltd. (NISCO) was examined in detail to elucidate the fate of calcium in the ash during hydration, using a range of techniques. The objective of the study is to determine the amount of CaO available for hydration/reactivation and to better understand interactions of Ca and other mineral components of the ash. Analysis results indicate that in NISCO ashes up to about 6% of the analytical CaO may be combined as acid soluble and insoluble OCCs (other calcium compounds). This implies up to about 10% less free lime than would be inferred from standard chemical analyses. About 1% of the missing CaO can be present as acid insoluble Ca and Mg vanadates, with up to 2% bound in soluble OCCs. The remaining 3-4% is still not accounted for. It is clear that even very minor quantities of mineral matter, other than CaO or CaSO4, associated mainly with the coarser size fractions, are important. The amount of bound water in the hydrated ash, other than that combined in portlandite or brucite, can be as large as 3-5%. This cannot be ignored when sample mass change on hydration or heating is used as a measure of the extent of CaO to Ca(OH)2 conversion.

Effect and limitation of free lime content in cement-fly ash mixtures

2016 ◽  
Vol 102 ◽  
pp. 515-530 ◽  
Author(s):  
Adnan Nawaz ◽  
Parnthep Julnipitawong ◽  
Pitisan Krammart ◽  
Somnuk Tangtermsirikul
Keyword(s):  
Fly Ash ◽  
Free Lime ◽  
Lime Content

Technical Note on the Determination of Free Lime (CaO) in Fly Ash

1984 ◽  
Vol 43 ◽  
Author(s):  
Scott Schlorholtz ◽  
Turgut Demirel
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Recent Work ◽  
Technical Note ◽  
Fly Ashes ◽  
Major Drawback ◽  
Free Lime ◽  
Chemical Test ◽  
Lime Content

AbstractMany fly ashes contain free lime (CaO) and periclase (MgO) [1,2]. These two compounds, when present in excessive amounts, are known to cause soundness problems in portland cement [3,4]. Recent work [5] has indicated that the autoclave expansion of portland cement-fly ash pastes is related to the concentration of CaO and MgO in a given paste, free lime typically being more detrimental than periclase. The purpose of this technical note is to briefly discuss two methods that are currently available for determining the free lime content of fly ash, and to suggest a supplement to the autoclave test (described in ASTM C 151). The major drawback of the autoclave test is that it requires approximately two days to complete and therefore it would be helpful to have a quick chemical test that could be used to indicate the soundness properties of a given fly ash.

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