DVMF REMOVES IRON-BEARING
TECHNOLOGY •
CONTAMINANTS IN LITHIUM AND OTHER HARD-TO-FLOW POWDERS
By Jose Marin, Eriez ® director, Mining & Minerals Processing
Eriez ® high-intensity Dry Vibrating Magnetic Filters( DVMF) are specifically designed to remove fine iron-bearing contaminants from hard-to-flow fine powders such as lithium. Typical applications include fine sand, glass power, talc, clays and other finely divided industrial minerals and chemical products.
All images © Eriez ®
Eriez ® high-intensity Dry Vibrating Magnetic Filter( DVMF).
This article explores the standard DVMF design, mode of operation, the bore of the separation zone, how a filter element concentrates the magnetic flux of the magnetic field and how scores of high-gradient collection zones capture magnetic contaminants as material filters through the element to produce a higher quality end product.
Source of Lithium in hard rock mining The main sources of lithium are spodumene, petalite and lepidolite from hard rock, accounting for 13 % of the global reserve. Salt flats – a brine solution – account for 87 % of the global reserve. 1
The DVMF is perfect for both lithium producers and users. Producers pulverise lithium before it goes to the user forming a fine powder with units placed prior to and after mill processing. As an additional check, many users position the DVMF at the point they receive lithium purchased from their producer.
When it comes to hard rock mining, the best practice among operators is to install equipment to protect crushers and belts. This is accomplished by combining suspended electromagnets( SEs) and metal detectors. The belt magnet removes ferrous material as it passes under a magnet on a belt or vibratory conveyor, while a metal detector detects ferrous metals missed by the SE and all nonferrous metals. This is an important preparation procedure while the fine powders move to the DVMF.
DVMF white paper The DVMF is perfect for feedstocks, glassmaking, talc, industrial ceramics and abrasives. Utilising a high-intensity electromagnet and revolutionary flux converging matrix, DVMFs are able to reduce contamination in lithium dramatically. The DVMF is fed vertically via gravity flow. As the feed material filters through the matrix and exits out the extremity, the matrix captures and holds the magnetic material as the non-magnetic material passes through( see figure 1).
The magnetic collection of fine particles requires a high-intensity, high-gradient magnetic field. This type of separator utilises a high intensity electromagnet and flux converging matrix. The matrix amplifies the magnetic field and provides high-gradient collection sites for the magnetic material as the feed materials filter through. A canister is attached to dual high-frequency, low-amplitude vibratory drives. These drives deliver a strong vibration to the canister assembly which enhances the fluidity of fine powders, resulting in a smooth and even flow of product through the matrix grid. This has been proven to be the most effective separation process for hard rock mining lithium applications.
The Eriez 5 000 gauss strength DVMFs reduce contamination to parts per billion, rather than parts per million.
The DVMFs are fully automated and feature a simplified cooling system. Other highlights include programmable controllers and the ability to handle four to 12-inch diameter sizes. The standard filters’ background magnetic field capacities are based on a fine powder flow range of up to 100 pounds per square inch of cross-sectional area of matrix. A 6-inch diameter is capable of treating up to 2 800 pounds per hour of material weighing 400lbs cu / ft.
Design features The magnetic filters consist of a solenoid electromagnetic coil enclosed in a steel housing. Figures 2 and 3 illustrate the 5 000 gauss Eriez DVMFs. The coil generates a uniform magnetic field throughout the bore of the coil, which represents the background
Figure 1 www. africanmining. co. za African Mining Publication African Mining African Mining • June 2025 • 15