ZENITH has completed the supply, installation and commissioning of two MTW198G Euro-type trapezium grinding lines at a limestone powder plant in Xinzhou, Shanxi Province, China. Delivered in 2025, the two lines produce 325 mesh (D93) limestone powder at a combined capacity of 19 t/h and supply the flue-gas desulfurization (FGD) system of a coal-fired power plant.

Two lines for a supply that cannot stop

Desulfurization is a continuous duty: the absorber has to be fed with limestone powder for as long as the boiler is running. That is why the customer did not simply ask for more capacity from a single mill, but installed two identical MTW198G lines side by side. Each line has its own feeding, grinding, classification, collection and dedusting equipment, so one unit can keep supplying the FGD system while the other is inspected or serviced.

Both lines are housed in a steel-structure plant building, with the mills, classifiers, cyclones and ducting laid out so that the two circuits can be operated and maintained independently.

Grinding limestone to 325 mesh D93

Limestone is ground in the MTW198G between the rollers and the grinding ring. Air from the mill fan lifts the ground material into the classifier above the grinding chamber, where the coarse fraction is rejected and returned to the grinding zone while the fine fraction passes through and is collected downstream. The circuit is set to deliver a product with 93% passing 325 mesh — the fineness the customer's FGD system needs for efficient absorption.

Dust control built into the circuit

The line runs under negative pressure throughout. A pulse-jet bag filter collects the fine limestone powder from the air stream and returns it to the product, so the working area stays clean, material losses stay low and emissions remain within the limits expected of a modern industrial plant. Ducting, cyclone and bag filter are matched to the airflow of the mill, which keeps the circuit stable when the feed rate changes.

From feed hopper to finished silo

Raw limestone enters the circuit through a feed hopper and a belt conveyor, which delivers it to the mill at a controlled rate. The ground powder is carried pneumatically to the bag filter, discharged through an airlock and lifted by bucket elevator into the finished-product silos, from where it is loaded out and delivered to the power plant.

Commissioning and handover

ZENITH's engineers carried out the mechanical installation checks, alignment and no-load running of both lines, then commissioned them under load and tuned the classifier speed and airflow to hold the 325 mesh D93 specification at the required output. Operators were trained on start-up, shut-down and normal operation before handover, and the plant has since run the two lines in normal production.

About ZENITH grinding solutions

ZENITH designs and manufactures crushing and grinding equipment and delivers complete powder-production plants, with capacities from 0.5 t/h to more than 100 t/h and finished fineness from coarse 80 mesh up to ultrafine 2500 mesh. Its MTW Euro-type trapezium mills are used for limestone, gypsum, calcite, bentonite, phosphate rock and other mineral powders, including limestone powder for flue-gas desulfurization.

If you are planning a limestone grinding project for FGD or another application, send us the raw material, the target fineness and the required capacity, and our engineers will recommend a process and an equipment configuration. You can reach us at [email protected] or on WhatsApp at +8618037697586.