Rotary Drum Furnace

Process Description

The powdered or granulated feed material is melted in a rotary drum furnace, where the drum is in a lying position. Due to their construction and their high operational flexibility, rotary drum furnaces are particularly suitable for inhomogeneous starting materials. For this reason, they are often used to melt recycled starting materials such as batteries or valuable lead-containing materials. There is a difference between stationary and tiltable rotary drum furnaces. Fundamentally, environmental regulations stipulate whether the rotary drum furnace can be operated with soda slag at process temperatures of approx. 900 °C or with a silicate slag at up to 1200 °C. Energy input is through burners mounted on the front of the drum.  

Stationary rotary drum furnace for lead production

In the case of stationary rotary furnaces, the metal and slag is removed via spouts. With tiltable rotary furnaces the entire furnace is lifted hydraulically and metal and slag is tapped at the feed opening. The required energy input is carried out with burner systems such as Oxyfuel.

Gas Application

In the Oxyfuel process, the combustion processes are carried out by means of an oxygen burner (Oxyfuel burner) which is operated with pure oxygen or oxygen-enriched air as an oxidising agent. Messer has developed the family of Oxipyr burners for this purpose. 

In comparison to burners which use air as an oxidant, Oxipyr burners provide a range of process technology advantages: 

• Higher combustion efficiency
• Higher melting rate
• Faster heating-up times
• Lower fuel consumption
• Higher processing temperatures possible
• Faster reaction speeds
• Lower exhaust gas levels
• Less dust
• Lower emissions
• Lower production costs

The table shows, using the example of a 20 t rotary drum furnace in the lead industry, the typical potential savings in energy and process duration associated with the use of Oxipyr burner technology in a rotary drum furnace.

Possible savings when changing from an air to oxygen burner

More than 70 Oxipyr burner systems have been installed in rotary drum furnaces worldwide, of which more than 20 are in the lead industry. 

Messer Process

In addition to the gases required for your process, Messer offers a variety of equipment for its optimisation under the brand names Oxipyr and Oxijet. 

In order to select the optimum system, experts from Messer first carry out a comprehensive process analysis. Following calculations and basic engineering, suggestions are made for optimisation and further procedures. 

Oxipyr – Flex L with water cooling and moving device

Oxipyr – Burner Technology

The characteristics of the burner types are multi-faceted and range from low to high momentum burners, oxyfuel to oxygen/air mixing burners and burners for different fuels or fuel combinations. The systems are controlled manually, semi- or fully automatically following compositions or temperature. 

Oxipyr- IPC (internal post-combustion)  

The combustion ratio of fuel and oxidising agent is selectively altered, with the oxygen flow regulated as a function of exhaust gas parameters and/or further process parameters. As a result, high-quality fuels can be substituted with replacement fuels and through the post-combustion of pollutants in the exhaust gas, can be relieved especially of the burden of volatile organic components (VOC).  Messer developed the Oxipyr-IPC process for this purpose.  When using the Oxipyr-IPC process in rotary drum furnaces, oxygen and fuel requirements as well as the drum’s rotation speed are controlled automatically.  Oxygen is always supplied via Oxipyr burners; with Oxijet oxygen lances used for certain types of furnace.

Advantages:

• Lower consumption of conventional fuels
• Use of cheaper alternative fuels
• Reduces post-combustion burden
• Recovery of caloric residues
• Savings in waste-disposal costs
• Lowering of production costs