Alternative Evaluation of the grindability of Pozzolanic Materials for Cement Production

K Dvořák,D Dolák

doi:10.1088/1757-899x/251/1/012011

K Dvořák, D Dolák

Open Access

https://doi.org/10.1088/1757-899x/251/1/012011

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Abstract

An ecological way of reducing CO2 emissions in cement production is the usage of blended cement with an active pozzolan. A part of this issue is the adjustment of granularity of raw materials. This is often achieved by the grinding of the input components. All conventional methods for the evaluation of grindability require a specific grinding instrument. These grinding instruments do not have any other practical use and thus are not very common. This paper focuses on the alternative evaluation of grindability. Inspired by the VTI method used in the coal industry, which uses porcelain laboratory ball mill and compares material based of oversize particles, a new method was created. The first modification in methodology was the use of a planetary mill instead of a porcelain drum mill. Another modification was in the measurement of undersize by means of laser granulometry. This method was then tested on clinker, slag, and recycled glass, which can also be used as an active pozzolan in blended cement. Also, co-milling measurements were made on clinker-pozzolan combinations. These results were then used in the calculation of the grindability index, which can be used for the comparison of properties. The modification of the VTI methodology has a positive impact on the evaluation of grindability, especially with regard to fine particles, thanks to the use of laser granulometry and at the same time it makes use of more a commonly available grinding apparatus

Highlights

The cement industry produces a large amount of CO2
Eight percent of global CO2 emissions can be attributed to the production of cement
Another possibility is the production of blended cement, to which latent hydraulic, pozzolanic or even inert materials are added [2]

Summary

Introduction

The cement industry produces a large amount of CO2. Eight percent of global CO2 emissions can be attributed to the production of cement. When the particle size is reduced further, the number of such areas gradually decreases, and this increases their resistance to further disintegration This is one of the main causes of the high specific energy consumption in fine particle grinding [5]. Hardgrove as a method of determining the grindability of coal This method uses a small amount of material with a specific granularity, which is ground in a grinding track by 8 grinding balls. The method was designed for grinding coal, but it later expanded to other materials as well [6] Another method is the Zeisel method, which was invented in 1953 and is based on Hardgrove. The oversize remainder on the sieve 0.09 mm is measured This amount is substituted into the formula (1) to calculate the grindability index KVTI of the material. The first one was the use of a commonly used planetary ball mill and the second one was the attempt to employ laser granulometry instead of sieve analysis for evaluation

Materials and methods

Results

Discussion

Conclusion