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Emerald Group Publishing Limited
Copyright © 2008, Emerald Group Publishing Limited
Assaying the anion profile of cement with IC
Article Type: Methods From: Anti-Corrosion Methods and Materials, Volume 55, Issue 3.
The 850 professional ion chromatography (IC) range from Metrohm can be used to determine any conductive anion and cation in a variety of different everyday products. Concrete has many uses in life and IC is a technique that enables the concentration of fluoride, chloride, sulphate and phosphate of the materials being fed into the kiln (kiln feed, coal, alternative fuels, etc.) to be determined quickly and accurately before they are used to prevent further problems arising with the cement quality down the line. The characteristic of cement is that after it has been mixed with water it will set hard as rock and will bind any rock or mineral fragments mixed with it. Mortar is made from a mixture of sand and cement, and bonds together bricks in a wall.
Most cement is mixed with both sand and aggregate to make concrete. The quality of the finished product cement is determined by the raw materials that are used to make cement's chemistry, and the process by which the chemistry is created in the kiln. Fluoride negatively impacts on cement quality; it affects the cement's strength and also the rate at which it sets, both of which are crucial factors.
Chlorine and sulphate are minor oxides in cement, coming from the raw materials used to make cement (limestone and shale) and the fuels that are used to power the kiln (e.g. car tyres or coal). These compounds negatively affect operation of the kiln and must therefore be tightly controlled. Chloride and sulfate are volatilised in the high temperatures of the kiln, and then blown by hot gases to the entrance of the kiln, where it is cooler, before they condense back into their original material.
The process occurs in cycles and leads to an accumulation of chlorine and sulfate that can cause great problems with kiln stability. Phosphate is a minor oxide that occurs in the raw materials used in the cement manufacturing process. Phosphate has a negative effect on cement resistance if it represents greater than 0.5 per cent total of the cement.
The 850 Professional IC and 858 Sample Processor are the result of more than 20 years of creative solutions through research and development to the field of IC and represent the third generation of IC instruments to come from Metrohm.
More information is available from www.metrohm.com