The new „parallel flow regenerative” (PFR) lime kiln had been built by Swiss Maerz Ofenbau AG, the world market leader in lime shaft kilns. Both companies share a history of many years of co-operation. The first PFR lime kiln by Maerz with an oil firing was put into operation by KFN in 1994. In 2013, that kiln was switched to natural gas firing. This new kiln project started with the signing of the contract in August 2018. After a successful acceptance it was handed over last November.
New procedure prevents recarbonization
To answer increasing market requirements, the new PFR lime kiln has a natural gas firing and an aftercooler. The kiln was designed specifically to produce quicklime that has both, a very low residual CO2-content and a very high reactivity. In order to sustain this high product quality in the long run, it was necessary to develop a PFR lime kiln with a direct cross-over-channel. Before it was introduced, the recarbonization of the quicklime in the cooling zone was unavoidable. This innovative new procedure prevents that from happening.
Large degree of utilization of the limestone
With its new kiln, KFN can now cover its entire lime demand. Which is why it is important to achieve a degree of utilization of the lime quarry that is as high as possible. In order to do this, the limestone is crushed to pieces of about 100 mm in a two-stage crushing plant with two double roll crushers. This plant was also built by Maerz in 2010. After that, the lime stones of 15 to 40 mm and those of 40 to 100 mm are sifted through and washed. The lime stones of different sizes are then fed to the kiln in equal parts. By using double roll crushers and the very wide range of stone sizes, the new PFR lime kiln allows a degree of utilization of roughly 85 per cent of all the lime mined in the quarry. Subsequently, this lime will be processed into the renowned lime and limestone products from the Netstal that are used in a variety of businesses.
Further information on the new PFR lime kiln of KFN can be found in this article of ZKG magazine.