Lime Production Expertise.

The production of high-grade lime demands very complex knowhow. For the latest shaft preheater generation, Maerz and Polysius therefore combined their experience.

Rheinkalk GmbH is part of the Belgian Lhoist Group, the world's largest lime producer. In spring 2007, the company decided to optimise the burnt lime production in its Hönnetal plant. The preheater was commissioned on schedule in April 2008. The preheater system achieved the guaranteed values within the first month of operation and continues to exceed the target level of performance for daily production, product quality and fuel efficiency.

The innovative Polysius conversion concept aims for reduced heat consumption, an increased production capacity, the production of high-quality steelworks lime and a substantial reduction of the dust emissions. The existing long rotary kiln will be shortened and equipped with a shaft preheater which was specially designed for this kind of application.

To produce cellular concrete, the building materials industry requires low reactive burnt lime, the so-called hard burnt lime. In many lime plants, it is still produced in traditional coke-fired kilns for mixed combustion.

In Matozinhos in the Brazilian state of Minas Gerais, the largest Maerz shaft kiln is being erected. It will have an output of 800 tpd burnt lime. It is the second shaft kiln that Mineração Belocal Ltda., a company of the Lhoist Group, has commissioned Maerz Ofenbau to build in this location.

The extreme rise of price for and the increasing shortage of both metallurgical coke and anthracite required some three years ago that a new concept for using coal dust as fuel was being developed.

Since then, Maerz has already converted five mixed-combustion kilns into kilns fired with brown coal dust in Germany. These kilns are exclusively supplied with fuel by movable peripherical burners projecting into the bulk material.

This new technology makes it possible to convert existing mixed-combustion kilns with large inside diameters into coal dust-fired kilns. Moreover, the throughput of the kilns can be increased, while at the same time, the pollutant emissions can be significantly reduced.