Conveying Iron Oxide Filter Cake for MP Materials in Mountain Pass, CA

General Description

Rare earth elements are vital to our modern technologies and used in electric vehicles, computers, smartphones, and many other products. Most mining of rare earth elements occurs primarily outside the United States causing supply chain issues for many of America’s “green technology” industries. MP Materials operates a mine in Mountain Pass, CA to produce rare earth elements for production of electric cars and wind turbines. Mountain Pass has one of the richest deposits of rare earth elements in the world.

Extensive processing is required to separate rare earth elements from mined ore. As part of the process, MP Materials uses plate-and-frame filter presses to remove water from waste material. KWS provided a twin-screw conveyor to receive dewatered cake material from the filter press, break it up and transport it to trucks for disposal.

Design Parameters

1. Product Type: Iron Oxide Filter Cake
2. Material Density: 134 Lbs. per Cubic Foot
3. Capacity: 432 Cubic Feet per Hour
4. Duty: Continuous

KWS Advantages

KWS excels at solving difficult bulk material handling problems involving corrosive, abrasive, and dense bulk materials. Engineers from M.W. Watermark and KWS worked closely to design a conveying system to receive dewatered iron oxide material and transfer it to trucks for disposal. A flared hopper with breaker bars fit up under the plate-and-frame press to receive and breaking up the material as it discharged from the press. Cake discharged from each plate is two cubic feet in size, weighs approximately 190-pounds, and needs to be broken up prior to entering the twin-screw conveyor. KWS understood the requirements of the application and created a simple, cost-effective solution.

KWS Special Features

KWS designed and manufactured a flared hopper to bolt up to the press, creating a direct connection. The hopper was built with cake breaker bars across the opening, to break up the material discharged from the press.

Directly under the hopper was a KWS twin-screw conveyor to transfer the damp and sluggish filter cake to a take-away conveyor and then truck load-out. The twin-screw conveyor had internal hanger bearings due to the long length. The hanger to supporting brackets had an inverted angle on top to deflect falling material and keep the hangers from being impacted.

Since the bulk material is wet and corrosive, Duplex 2205 stainless steel material was used for construction. Due to the dampness and stickiness of the material, integral leg ribbon screws keep the material from building up on the center pipe. Duplex 2205 material is twice the strength of 304 or 316 Stainless Steel, has superior resistance to corrosion cracking, pitting, erosion, and general corrosion in severe environments and is work hardened.