Mass Flow Screw Feeder and Dual Actuated Slide Gate for Soda Ash

General Description

Black Thunder Coal Mine, located in Wright, WY produces 100 million tons of coal every year, which is eight percent of the yearly coal supply in the U.S. In operation since 1977, Black Thunder Coal Mine is owned by Arch Coal, a producer of high-quality metallurgical and thermal coal, used to manufacture steel and generate electricity.

Black Thunder needed a heavy duty screw feeder with a maintenance slide gate for an existing soda ash storage silo. Previous soda ash feeders were very problematic due to bridging and plugging. Arch Coal contacted Cementation AG, who are mining industry leaders. Arch Coal needed a highly experienced supplier to solve their difficult bulk material flow problems. Cementation partnered with KWS for the supply of the screw feeder and maintenance gate.

Design Parameters

1. Product Type: Soda Ash
2. Material Density: 64 Lbs. per Cubic Foot
3. Capacity: 10,000 to 100,000 Lbs. per hour
4. Duty: 24 Hours per Day, 7 Days per Week

KWS Advantages

KWS provided a guarantee to Arch Coal that the new screw feeder would operate 24/7 with minimum downtime to meet the demands of their mine. KWS has extensive experience conveying and metering difficult bulk materials such as soda ash. KWS provided references of past successful installations and technical articles addressing the concerns of Arch Coal as well as 3D models of the equipment to assist in the system layout and design.

Special Features

The new KWS screw feeder was designed with a large rectangular inlet and mass-flow screw to allow for even draw of soda ash from the silo. The design provided by KWS eliminated rat-holing and bridging in the silo. Arch Coal is now able to achieve the desired flow rate to keep the mine running properly. The design of the mass-flow screw is based on proven technology developed by Jenike & Johanson. KWS and Jenike & Johanson regularly work together to solve difficult bulk material metering applications.

The screw feeder motor has 1000-to-1 turn-down capabilities for a very wide capacity range. The drive unit provides constant torque through the full speed range. KWS supplied safety guards in compliance with MSHA standards to protect plant personnel.

A dual-blade electrically actuated slide gate was supplied and attached to the inlet of the screw feeder. The slide gate was designed to withstand the massive material head load of soda ash in the silo. Maintenance can be performed on the screw feeder or downstream equipment without the need to empty the silo.