Effect of particle size distribution and calcium aluminate cement on the rheological behaviour of all-alumina refractory castables

2012 ◽  
Vol 226 ◽  
pp. 107-113 ◽  
Author(s):  
Abílio P. Silva ◽  
Ana M. Segadães ◽  
Deesy G. Pinto ◽  
Luiz A. Oliveira ◽  
Tessaleno C. Devezas
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Calcium Aluminate ◽  
Rheological Behaviour ◽  
Calcium Aluminate Cement ◽  
Refractory Castables ◽  
Effect Of Particle Size ◽  
Alumina Refractory ◽  
Aluminate Cement

MPT Influence on the Rheological Behaviour of Self-Flow Refractory Castables

2008 ◽  
Vol 587-588 ◽  
pp. 133-137 ◽  
Author(s):  
Abílio P. Silva ◽  
Ana M. Segadães ◽  
Tessaleno C. Devezas
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Mechanical Strength ◽  
Size Distribution ◽  
Fine Particles ◽  
Rheological Behaviour ◽  
Response Surfaces ◽  
Coarse Particles ◽  
Aggregate Particle ◽  
Refractory Castables

The success of a refractory castable is largely due to the quality of its properties and ease of application. Self-flow refractory castables (SFRC), with high flowability index (>130%), can be easily accommodated in a mould without the application of external energy, being ideal for the manufacture of monolithic linings. SFRC castables without cement require a matrix of very fine particles, which guarantees improved rheological behaviour and performs the role of the binder in the absence of the refractory cement. The presence of the aggregate (coarse particles) hinders the flowability index, but improves the castable mechanical strength and reduces firing shrinkage, and also contributes to the reduction of the castable costs. The control of the maximum paste thickness (MPT) allows the reduction of the coarse particles interference, minimizing the number of contact points among the grains and avoiding the formation of an aggregate skeleton that impairs the flowability of the mixture. In the present work, 100% alumina SFRCs without cement were produced with a fixed matrix of fine particles, whose particle size distribution was optimized using statistical techniques (mixtures design and triangular response surfaces). Different aggregate particle size distributions were used, with several MPT values, with the objective of evaluating which was the mean distance that maximized the flowability index, simultaneously ensuring good mechanical strength for the refractory castable. Ensuring a minimum surface area of 2.22m2/g, the mixtures reach the self-flow turning point with a minimum water content and the maximum flowability is obtained for an aggregate particle size distribution modulus of q=0.22, and consequently an optimized MPT value. SFRC with high mechanical strength (>60MPa) were obtained.

The Effect of Particle Size Distribution of Lime on Properties of the Autoclaved Calcium Hydrosilicate Materials

2017 ◽  
Vol 908 ◽  
pp. 29-34
Author(s):  
Dana Kubátová ◽  
Martin Boháč
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Rheological Behaviour ◽  
Deionized Water ◽  
Hydrothermal Conditions ◽  
Slaked Lime ◽  
Effect Of Particle Size ◽  
Calcium Hydrosilicate

This investigation was made to examine how the particle size of lime influence the properties of calcium hydrosilicate materials. Quicklime was sorted in three fractions: 0-1 mm, 1-11.2 mm and 11.2.-22.4 mm. Slaked lime putties were prepared in the laboratory by mixing lime fractions and deionized water under vigorous stirring. The C/H ratio was 1:8. The lime putties were mixed with finely ground sand with the C/S ratio equal to 0.85. The hydrosilicate materials were prepared under hydrothermal conditions: temperature 205 °C, pressure 16 bar. This work focuses on lime putty rheological behaviour and on composition and properties of lime hydrosilicates. It was found that hydrated particles of fractionated lime form smaller aggregates than standard lime. Plasticity increases with the increasing size of fraction. When separate fractions are used, 11.3 Å tobermorite crystallization is slower.

Effect of Particle Size Distribution of Raw Materials on Properties of Magnesia-Alumina Refractory

2016 ◽  
Vol 697 ◽  
pp. 595-598
Author(s):  
Zhin An Chai ◽  
Cheng Ji Deng ◽  
Hong Xi Zhu ◽  
Xiao Jun Zhang ◽  
Liang Yi Zhou
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Distribution Coefficient ◽  
Size Distribution ◽  
Rate Of Change ◽  
Refractory Materials ◽  
Crushing Strength ◽  
Linear Rate ◽  
Effect Of Particle Size ◽  
Alumina Refractory

Starting from different sizes of magnesia and bauxitewith sodium hexametaphosphate as anchoring agent, specimens obtained by suppression were sintered at 1500°C and 1550°C and heat preservation for 3h in the electric hearth furnace, respectively. The effect of particle size distribution of magnesia and bauxite on the properties of magnesia-alumina refractory materials was investigated. The composition of magnesia-alumina refractory which consists of various particle size distributions was determined, according to Andreasen packing model, with distribution coefficient (q) of 0.15, 0.20, 0.25, 0.30, 0.35, 0.40 and 0.50. The fractographs of the specimen were observed by scanning electron microscopy. The linear rate of change, apparent porosity, bulk density and crushing strength of these specimens were studied. The results showed: a crushing strength of 52.39 MPa, an apparent porosity value of 15.55% and a bulk density value of 2.91 g/cm3 were obtained via a particle size distribution coefficient of 0.30 at 1550°C. Simultaneously, the refractory materials had small linear rate of change.

Effect of Micro-Sized Alumina Powder on the Hydration Process of Calcium Aluminate Cement

2018 ◽  
Vol 281 ◽  
pp. 249-254
Author(s):  
Zhong Feng Xia ◽  
Zhou Fu Wang ◽  
Xi Tang Wang ◽  
Hao Liu ◽  
Yan Ma
Keyword(s):  
Calcium Aluminate ◽  
Cement Hydration ◽  
Calcium Aluminate Cement ◽  
Hydration Heat ◽  
High Alumina ◽  
Alumina Powder ◽  
Hydration Products ◽  
Refractory Castables ◽  
Alumina Refractory ◽  
Aluminate Cement

Micro-sized alumina powder is widely used in low cement high-alumina refractory castables. The hydration of calcium aluminate cement can be affected by adding micro-sized alumina powder. This work addresses the hydration of a commercial cement at 25°C with 50 wt% micro-sized alumina powder added. The hydration heat was measured by isothermal micro-calorimetry. The phase composition and microstructure of the hydration products at the designated times were studied by XRD and SEM, respectively. The results showed that micro-sized alumina powder accelerated the dissolution of CAC. The induction period of the cement hydration reduced from 13h to 4.5h, and the hydration heat within 50hs was increased from 469J/g to 587J/g with the addition of micro-sized alumina powder. The morphology of the hydrates was flocculent amorphous at the beginning, and then transformed to short rods or cubic shape with micro-sized alumina powder added.

scholarly journals The effect of particle size distribution on froth stability in flotation

2017 ◽  
Vol 184 ◽  
pp. 240-247 ◽  
Author(s):  
A. Norori-McCormac ◽  
P.R. Brito-Parada ◽  
K. Hadler ◽  
K. Cole ◽  
J.J. Cilliers
Keyword(s):  
Particle Size ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Froth Stability ◽  
Effect Of Particle Size
Sign in / Sign up

Export Citation Format

Share Document