Uzimet: clearing the air

In mid-2008 De Jong Thermal Engineering was commissioned by the Rijswijk company Uzimet B.V. to design and construct a flue-gas treatment installation. Uzimet processes lead. This metal is stripped of contaminants via a number of process steps. After treatment the purified lead is once again fully suitable for the production of a variety of semi-manufactures.

The issue
During the smelting process odour components are released, which are entrained in the process gases. To prevent odour nuisance for the surrounding area Uzimet decided to install a modern flue-gas treatment facility for extensive purification of the process gases. This facility was installed in mid-2009 and commissioned at the end of 2009. As the only Dutch lead smelter, Uzimet has a unique operating process. The process of smelting and purification takes place on a batch basis and has various intermediate stages, each with its own specific process conditions and characteristics. This product-specific process naturally also needs a specific solution, capable of optimum performance of its task under all operating conditions: in other words a customised solution.

The solution
The heart of the flue-gas treatment installation is a post-combustion unit for removing irritating process gas components (in particular odorous components). An existing study indicated that this approach would produce the best results (Best Available Technology). Post-combustion is based on the principle of breaking down (oxidising) the components at a high temperature (approximately 850 °C). By performing this post-combustion using a regenerative thermal oxidiser (RTO) the energy consumption (natural gas) remains very low. The thermal efficiency is approximately 95%! As it has been possible for optimisation and re-use of heat to take place at various points within the existing process, the ultimate energy consumption (natural gas) per tonne of lead processed has scarcely increased. The overall flue-gas treatment process comprises several interlinked sub-installations, including a multiple dust-removal installation and a spark arrester. This gives the overall design a high degree of safety and reliability, resulting in higher availability of the production process and hence ultimately profit and benefit for both the organisation and the surrounding area.

Result
The installation supplied satisfies the emission requirements established by the licensing authority (the South Holland province) as well as the operational requirements set by the client Uzimet B.V.

 

Technical data
process gas flow	17.500 m3/h @ 100 °C
exhaust temperature	150 °C
burner capacity	2x300 KW (start-up capacity)
production cycle	16 hours a day / 5 days a week
smelting process	lead recycling