D-SOx™ Cyclone

The D-SOx™ system, exclusively developed by FLSmidth, is a proven and simple method that provides a SO2 emission reduction in the range of 25-30% without addition of reagents

D-SOx™ Cyclone
  • Overview

Key benefits

  • Effective emission control
  • Easy operation
  • Highly reliable
  • Internal system
  • No external inputs
  • For continuous or intermittent use

How it works

The D-SOx™ system can be used in any cement plant where the kiln feed contains pyritic sulfur that creates SO2 emissions.

The D-SOx system is designed to take advantage of the free lime (CaO) that is created in the calciner. A portion of the calciner exit gas is taken from the calciner exit duct and goes up to the D-SOx cyclone which separates most of the entrained dust from the gas. The captured dust is then fed to the cyclone exit duct where the pyritic sulfur is converted to SO2.


The free lime in the calciner dust absorbs some of the SO2 to give a 25-30% reduction. This translates to approximately 5% of the calciner exit gas being diverted to the D-SOx system for plants with a significant level of pyrite.

The exit gas from the D-SOx system is returned to the outlet of the second stage cyclone. This means that the gas taken to the D-SOx system is effectively bypassing two to four stages of the preheater tower depending on the total number of preheater stages. Since the gas moving through the D-SOx system has an easier path than the gas that goes through the bottom cyclones, the natural draft of the preheater can be used to pull the gas through the D-SOx system. Therefore, no additional fan is required.

In order to control the amount of gas taken through the D-SOx system, a damper is located in the ducting after the D-SOx cyclone.