Burnability Of Raw Mix Research Articles

Waste Glass Valorization as Raw Material in the Production of Portland Clinker and Cement.

The paper presents experimental results regarding the synthesis of Portland clinker starting from raw mixes based on two types of clayey precursors, i.e., clay and marl (the most common types of raw materials used in the cement industry), with and without glass waste content. The soda-lime glass waste addition (5.36–5.59 wt %), used to control the silica ratio of the raw mix, improved the raw mix burnability and decreased the calcination temperature (by 20 °C), leading to a decrease in fuel consumption and contributing to the reduction in CO2 emissions associated with clinker and cement production. The clinkers obtained by the calcination of raw mixes with glass waste content at 1430 °C with a 30 min plateau had a similar mineralogical composition and microstructure to the clinkers obtained from the reference raw mixes and fulfilled the requirements of the specific standard EN 197-1. The obtained clinkers were used to produce two types of Portland cement, i.e., a unitary cement (CEM I) and a binary blended cement with slag (CEM II/B-S). The main characteristics of these cements, i.e., loss on ignition, insoluble residue, sulfate and chloride contents, as well as the setting time and soundness, meet the conditions stipulated in the EN 197-1 standard. The values of compressive strength, assessed on mortars after 2, 7 and 28 days of curing, allow the classification of all CEM I cements in the 42.5 R class. In the case of CEM II/B-S cements, those obtained from raw mixes with clay can be classified in the 42.5 N class, while those obtained from raw mixes with marl are classified in the 32.5 R class.

Moroccan oil shale and coal waste as alternative raw materials in Portland cement clinker manufacture. Clinkerisation reactions and clinker characterisation

For some time the cement industry has been seeking procedures to effectively lower the higher energy costs involved in cement manufacture. Timahdit oil shale and Jerada coal waste could potentially be used as alternative raw materials to produce clinker. This study explored the possibility of applying those materials to a greener use, based on the reactivity and burnability of raw mixes containing Moroccan oil shale and coal waste. The findings showed that, irrespective of particle size, oil shale mixes delivered higher reactivity than coal waste materials, although reactivity was highest in the oil shale clinker with a particle size < 45 μm. The clinkers bearing oil shale with a particle size < 90 μm or a blend of oil shale and coal waste with a size < 45 μm contained higher proportions of alite ( > 70 %).

Use of Late-Barremian sands from Central Tunisia in white cement clinker

The present work focuses on the ability of Late-Barremian sands from Ouaddada Mountain (Central Tunisia), to produce high-quality white cement clinker. Results indicate that these sands are particularly characterized by their fineness of grains (mean grain-size 90–140 μm), high cleanness (sand equivalent 88–98%), extremely low coloring oxides and volatiles levels (less than 0.03 and 1.9% respectively) and high values of whiteness and lightness indices (more than 86 and 90% respectively). Studies based on Bogue calculation, X-ray diffraction (XRD), burnability of raw mixes, Point Counting and Scanning Electron Microscopy (SEM) with Energy-Dispersive X-Ray Spectroscopy (EDS) methods, reveal that the Late-Barremian sands from Ouaddada Mountain can be used in the production of white Portland clinker by mixing with 70.8–75.6% of local limestones and 3.5–24.8% by weight of common Mediterranean kaolins from Guadalajar province (Central Spain), Tamazert (North-East Algeria), Şile (North-West Turkey), Sebha (South-West Libya), and Abu Zanima area (West-Central Sinai, Egypt). Synthesized clinkers are composed largely of alite (75–76.2%), belite (12.8–16.5%) and aluminate (7.4–8.9%) with subordinate quantities of ferrite (less than 1%), slightly harder to burn and seem to be much whiter than Mediterranean ones with a whiteness index β more than 86%.

Preparation of Portland cement with sugar filter mud as lime-based raw material

Abstract The objective of this study was to assess the preparation of Portland cement with sugar filter mud (FM) as lime-based raw material. Burnability of raw mix, SEM characteristic and phase component of clinker, compressive strength, setting time and hydration characteristic of cement are investigated. The results show that FM can improve the raw mix burnability, and increase liquid phase amount. Less than 20% FM is helpful to promote the C3S formation, and heighten the C3S content in clinker. More than 20% FM will result in the new phase formation. Compressive strength, setting time and hydration characteristic of cement all are related to the replacement ratio of limestone with FM. It is found that the proper FM amount can raise the compressive strength, cut down the setting time, and promote the cement hydration in the initial and acceleration period. Excessive FM will lead to the decrease of compressive strength, the delay of setting time and prolongation of cement hydration.

Preparation of Sulphoaluminate Cement-Based Material from Municipal Solid Waste Incineration (MSWI) Fly Ash

This letter presents a feasible method for the preparation of Sulphoaluminate cement-based material (SCBM) from a hazardous industrial waste, i.e., MSWI fly ash. The produced materials were characterized by X-ray powder (XRD), field emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDS) and mercury intrusion porosimeter (MIP). Experimental results show that a type of SCBM was successfully prepared from MSWI fly ash by controlling compositional parameters at right values, and firing the raw mixes at 1200°C for 2 h. Results also show that MSWI fly ash improves the burnability of raw mixes significantly, and for the investigated fly ash sample the maximum allowable content is 30 wt%. The morphology of C4A3S in the produced materials appears smaller in size, rounded in shape crystals and tends to form large agglomerates, in contrast to the slightly angular outline of beton-C2S grains. MIP test result indicates that the critical pore diameter decreases rapidly at early ages (< 1 day), and attains to a steady-state after 3 days of hydration.

Effect of TiO2 on mineral formation and properties of alite-sulphoaluminate cement

The effect of TiO2 on the mineral formation and properties of alite-sulphoaluminate cement was studied, using pure chemicals and commercial raw materials. The results showed that a smaller amount of TiO2 (<1·0%) could improve the burnability of raw mix, accelerate the absorption of f-CaO, and promote the formation of the major minerals C3S and C4A3S. If the amount of TiO2 is larger than 1·0%, the content of f-CaO increased, while C3S and C4A3S decreased. A proper amount of TiO2 can increase the strength of cement at various hydration ages. Little amount of TiO2 could rarely affect the setting time of cement, but when the amount is over 1·0%, the setting time of cement was obviously delayed.

The use of oil well-derived drilling waste and electric arc furnace slag as alternative raw materials in clinker production

Through laboratory burnability tests and industrial runs carried out for 1 month in a dry process-cement kiln it has been found that an oil well-derived drilling waste and an electric arc furnace (EAF) slag generated in a steel plant are suitable partial substitutes for both limestone and clay in the kiln feed. Drilling waste was available in two streams: the one, muddy and argillaceous; the other, rocky and calcareous. Both gave satisfactory burnability indexes (BI) and high percentages of replacement of limestone (up to 38%) and clay (up to 72%). EAF slag was introduced in the kiln feed at a lesser degree (20%), but promoted a better raw mix burnability: furthermore, being a non-carbonated source of lime, it allows a reduction of both thermal requirement and emission of CO 2, gas responsible for the greenhouse effect. The manufacturing process of waste-based clinkers was environmentally compatible and the related cements were similar in performance to common hydraulic binders.

Use of copper slag in the manufacture of Portland cement

Given its chemical and mineralogical characteristics, copper slag, a solid industrial by-product, may serve as a partial substitute for silica and hematite in raw mixes used to manufacture Portland cement clinker. The benefits of such substitution include lower production costs and energy savings. The effect of slag-containing raw mixes on the reactivity of the CaO-Si0 2 -Al 2 0 3 -Fe 2 0 3 system was studied at three temperatures (1,350, 1,400 and 1,450oC). Four mixes were used: M-1 and M-2 prepared with conventional prime materials and M-3 and M-4, in which ignimbrite and hematite were substituted for slag. In M-3 the slag replaced 45.54% of the ignimbrite and 100% of the hematite, and in M-4 100% of the mineral iron. The samples were clinkerized at 1,350, 1,400 and 1,450oC. At 1,400oC, clinker M-3 was found to have 10.7% less free lime than M-1, while the level in M-4 it was 15.93% lower than in M-2. The presence of the main clinker phases was confirmed by X-ray diffraction, which also showed that adding slag during c/inker manufacture slightly improves raw mix burnability without generating new unwanted phases. Consequently, recovery in cement kilns would appear to be an economically and environmentally feasible alternative to coprocessing such waste, although the industrial use of slag depends on its heavy metal content.

Use of Selected Minerals as Secondary Raw Materials in Cement Industry. Part I: Effect on the Burnability of Raw Mix

Use of Selected Minerals as Secondary Raw Materials in Cement Industry. Part I: Effect on the Burnability of Raw Mix

Use of Selected Minerals as Secondary Raw Materials in Cement Industry Part II: Effect on Clinker Structure

The use of selected secondary materials for improving the reactivity of cement raw mix, is a challenging subject. It is known that certain foreign elements exert a considerable effect on the cement raw mix burnability and clinker structure, even at low concentration. This work is part of a project on the use of selected minerals as a source of elements having a positive effect on the burnability of cement raw mix. The minerals, iron rich wolframite, stibnite and a wolframite- stibnite assemblage, were selected in order to introduce W, Sb and S in the cement raw mix. One reference and twelve modified mixtures, prepared by mixing the reference sample with 0.5, 1.0, 1.5 and 2.0 % w/w of the above minerals, were studied. Their effect on the burnability is discussed in Part I. The subject of this paper is their effect on the structure of the produced clinker. The XRD studies, performed in samples that were burned at 1450 o C, showed that the diffraction patterns correspond to a structure of a typical clinker, obtained at the above temperatures. In addition, samples sintered at lower temperature (1200-1400 o C) were examined in order to investigate the effect of the additives on the intermediate products. It is concluded that the added compounds affect mainly the structure of calcium aluminate and calcium aluminoferrite phases, due to their dissolution in the melt formed during the sintering. Scanning Electron Microscopy was used in order to examine the structure of the clinker and the distribution of the foreign elements in its main phases. It is shown that W and Sb are mainly concentrated in the solidified melt. In addition, bigger and more roundish alite crystals are found in these samples. These modifications are attributed to the effect of the added elements on the properties of the melt.

Influence of sand nature on burnability of white cement RAW mixes made using CaF 2 and CaSO 4 fluxing/mineralizer pair

The influence of sand nature on the burnability of white cement raw mixes manufactured using CaF 2 and CaSO 4 as flux and mineralizer has been studied. A methodology based on a statistical method called Experimental Design is used to establish a model. Raw mixes burnability models have been compared depending on sand nature. An Al 2O 3 and CaO rich sand enhances raw mix burnability, favouring clinkering. The enhancement is attributed to the different distribution of clayey material in the raw mix.

Simulating minerals pyroprocessing by thermal analysis

TG and DTA studies on laboratory cement raw mixes and raw dolomite have been extensively reported in the literature. This paper discusses four aspects. (1) Calcination kinetics of raw mix by isothermal TG and calculation of rate constants to derive activation energy by Arrhenius plots. (2) Quantification by TG of minerals in Indian laterites. The amount of goethite appears to influence burnability of raw mix. (3) Determination of practical heat of clinker formation from DTA studies and establishment of enthalpy temperature relationship of raw mix for heat transfer studies in rotary kilns. (4) Prediction of material temperature profile in a dolomite kiln from DTA studies of raw dolomite.

Factorial Design in Cement Raw Mix Reactivity Investigation

The present paper corroborates, that experimental design technics are applicable to raw mix burnability investigations, and with it the obtained results could cover all the range of possible concentrations of industrial interest. Obtained results agree with theory. A negative interaction was found between lime saturation factor (LSF) and silicate module (Ms) in raw mix burnability and in cement reactivity. In the concentration range studied, working with high LSF and low Ms is recommended.