Screw Conveyor Solves Housekeeping Issues for Chromium Production Facility Castle Hayne, NC

General Description

Chromium chemical products are used in a variety of applications ranging from pigments for paints, chrome coatings for appliances and automobiles to additives used in the tanning process to produce leather. The most common use of chromium is as an additive to iron, producing steel that is corrosion-resistant. Elementis is a leader in the chromium industry with manufacturing facilities located in North Carolina and Texas.

At the facility in Castle Hayne, NC one of the processes involves conveying chromium paste from a pair of filter presses to a dryer. Historically, this was accomplished using a belt conveyor, but it was a highly inefficient process. Chromium paste would constantly fall off the belt, leading to significant man hours spent cleaning the surrounding area. After careful consideration, Elementis chose to partner with KWS because of their proven track record of resolving the most difficult bulk material handling applications.

Design Parameters

1. Product Type: Chromium Paste
2. Material Density: 70 to 90 Lbs. per Cubic Foot
3. Moisture Content: 18 Percent by Volume
4. Capacity: 1,535 Cubic Feet per Hour
5. Duty: 24 Hours per Day, 7 Days per week

KWS Advantages

Since the new KWS screw conveyor was replacing an existing belt conveyor, there was minimal clearance between the belt filter presses and the down-stream equipment. KWS assigned a veteran Project Manager with over 35 years in the industry to the task. Every obstacle was carefully dimensioned and modeled using three-dimensional software to ensure a problem-free installation. Bolted covers created a dust-tight enclosure and kept the chromium paste completely contained within the trough housing throughout the conveying process. Reducing clean up and housekeeping issues allows Elementis employees to focus on preventative maintenance and improving the process rather than daily clean up.

Special Features

Chromium paste is very abrasive and the new KWS screw conveyor was designed for the application. Heavy-duty U-troughs with 3/8-inch thick abrasion-resistant AR400 wear liners form a long-lasting housing that will hold up to the abrasive chromium paste. Possible buildup of chromium paste on the screw flights and center pipe was a concern of Elementis. To prevent buildup, a system of spray nozzles was installed along the length of the trough to continuously coat the screw with a small amount of water to encourage the paste to release and convey to the discharge point.

The screws were designed for long life while conveying the chromium paste efficiently. Close-clearance between the outside diameter of the screws and inside diameter of the U-troughs allows for maximum cleanout of material, leaving very little in the troughs. Typical clearance between a screw and housing is ½-inch, but KWS reduced the clearance to ¼-inch for this application. Hardsurfacing is commonly used to extend the wear life of a screw by welding on a highly abrasion-resistant coating along the carrying face of the flights. KWS also applied the hardsurfacing to around the periphery and non-carrying face of the flights, which completely encapsulates the screw flights with an ultra-hard and abrasion-resistant protective layer.