Grinding Aids to Reduce CO2
Reducing CO2 Through Cement Grinding Optimisation
A ready alternative to changing base clinker quality is to use a cement performance additive. These are compounds that allow cement producers to increase the output and "performance, quality and handling of the finished cement, thereby allowing an increase in cement productivity and profitability. This article looks at the various methods available to help lower the clinker factor in cement, what issues need to be considered in each case and their potential impact on CO2 emissions.
Saving Water in VRMs
Reducing Prehydration
Cement produced from VRMs are much more likely to suffer from prehydration compared to cement produced from conventional ball mills. This is due primarily to the additional water spray used to stabilise the VRM grinding bed. A prehydrated cement will have deteriorated properties, such as lower compressive strength and longer setting time. In order to reduce water spray in a VRM, grinding aids can be used to help stabilise the grinding bed. In the two field trials discussed here, replacement of a standard grinding aid with a grinding aid optimised for VRM grinding have been demonstrated to allow for a substantial reduction in water spray, with corresponding decreases in prehydration level. As a result, compressive strengths were increased by up to 5 MPa and initial setting time was decreased up to 45 mi.
Ball Mills
Fine Grinding
The optimisation of cement ball mills requires careful attention to the many parameters involved and this includes the optimum circulating load and the application of smaller media in the fine grinding zone (typically chamber 2). The application of appropriate grinding aids or cement additives themselves can also provide significant benefits to process efficiency. However, it is evident from the mechanisms involved that these areas require a simultaneous optimisation approach if the maximum benefits of each are to be fully realized.
Sustainable VRM Operations
Making VRM Cement Production Greener
With water stress a particular concern of climate change, vertical roller mills (VRMs) consume a considerable amount of water to stabilise the grinding bed against excessive vibrations. A key enabler of lowering water spray is the use of an appropriate grinding aid product designed for use in VRMs. Using two cement industry case studies, GCP explains how its grinding aid products for VRMs can save water, fuel and CO2.
Vertical Roller Mills (VRMs)
VRM Optimisation
The difference in performance between ball mill and VRM cement is largely due to process factors. The observed performance discrepancy relates to the management of total moisture in the mill circuit and not just water applied for bed stabilisation. Additionally, the use of a grinding aid coupled with best-in-class process expertise from an industry-leading cement additives supplier will result in substantial improvements in the performance and quality of the finished cement.
Sustainable Grinding Aids
Admixtures and Sustainability
With reducing the environmental impact of cement manufacture high on the agenda for producers, sustainable cement additives based on renewable materials can contribute towards reducing a plant’s carbon footprint and lowering costs.