Cement News tagged under: clinker chemistry
Reducing cadmium volatility19 December 2018, Published under Cement NewsA recent news report for the Journal of Engineering described some experimental work that has been carried out in China designed to investigate the behaviour of some heavy metals, especially cadmium, in cement clinker. In particular the work looked at the influence of chalcogens on the volatility of cadmium. The content of cadmium in alternative fuels may be higher than in fossil fuels Chalcogens are a group of elements also known as the oxygen family. It consists of the element... |
Sulphate in clinker26 November 2018, Published under Cement NewsThe amount of sulphate (SO 3 ) varies widely in cement clinker. Arthur Harrisson discusses the sources of SO 3 and its impact on clinker composition. Figure 1: relationship between the contents of sulphate and aluminate in alite crystals from two cement plants The four main phases in Portland cement clinker are alite (C 3 S), belite (C 2 S), aluminate (C 3 A) and ferrite (C 4 AF). As has frequently been discussed, the chemical compositions suggested in brackets for these compou... |
Bringing on the substitutes18 July 2018, Published under Cement NewsAs part of its drive to reduce its CO 2 emissions, Votorantim Cimentos is using a range of clinker substitutes to lower its clinker-to-cement ratio. As a result, around 86 per cent of its product portfolio in Brazil has a reduced carbon footprint, lowering its impact on the environment. By Silvia R S S Vieira, Votorantim Cimentos, Brazil. The use of substitute materials such as acidic slags (pictured: maganese slag) and calcined clay is key to reducing a cement plant’s carbon foot... |
Alternative fuels and clinker crystal characteristics30 April 2018, Published under Cement NewsArthur Harrisson examines the effect of alternative fuel use on the characteristics of crystals present in clinker. Figure 1: difference in alite quantity measured by microscopy and the Bogue calculation when burning increasing quantities of PSP Some four years ago an article was published in International Cement Review about the microscopic effects due to the use of alternative fuels (AFs). 1 In the intervening years the author has examined some 200 clinker sampl... |
Modifying the Bogue calculation31 January 2018, Published under Cement NewsThe Bogue calculation helps cement chemists to allocate the four main oxides in Portland cement clinker to the four main phases present following the pyroprocess in the cement kiln. While not perfect, it remains an effective guide to the potential relative properties of such clinkers. How much of each phase is there? The Bogue calculation is a means of allocating the four main oxides in Portland cement clinker to the four main phases present after firing in a cement kiln. The ca... |
Crystal clusters in clinker13 December 2017, Published under Cement NewsWith increasing use of alternative fuels, short homogenisation times in precalciner kiln systems and the requirement for high alite cement, the presence of crystal clusters is not expected to be a thing of the past. While the impact of crystal clusters in clinker on quality is not always clear, some effects can be seen. Figure 1: brown and lighter blue belite crystals surrounding liquid phase Cement clinker for general-purpose Portland cement is composed essentially of four... |
Process impact on clinker17 July 2015, Published under Cement NewsThe fine microstructure of cement clinker provides a number of clues relating to the state of the process which made it, including the temperature, the chemistry, the fuel type and quality, the thermal profile through the process and the efficiency of cooling. Microscopic and macroscopic analysis can, in some cases, differentiate between different cement kiln types. More usefully, knowing details of the process which made the clinker is of immense value in interpretation of the significance ... |
The importance of raw materials17 February 2014, Published under Cement NewsProper analysis and identification of raw materials are essential to achieving the best clinker in the kiln. All clinkers will have a small degree of unwanted elements, but much can be learnt about reaching the desired levels of strength, setting time and crystal content by understanding what makes good- and poor-quality clinker. For a new cement plant the main raw material selection is generally the first and most important phase of development. If the everyday supply of limestone is not... |
Microscopy & practice08 April 2013, Published under Cement NewsIn this article Arthur Harrisson connects microscopy observations with the practical issues on the cement plant and in the market. He also identifies the benefits which are obtained by regular microscopic examination of cement clinker. Figure 1: effect of coarse silica in kiln feed. Oversized belite crystals are very difficult to combine with free lime In a previous article concerning microscopy (ICR July 2010) as a demonstration of the complexity of clinker mineralogy I took th... |