Lithium is the lightest metal on the periodic table. However, some general characteristics remain. The properties of lithium dust can vary depending on its source, form, and processing conditions.
The challenges of lithium dust require careful design and planning to build a proficient system to control it. Best practices will analyze lithium dust characteristics and customize a dust management approach to optimize its safe capture.
Lithium dust characteristics
Lithium is either mined from either hard rock or brined from salt deserts. Groundwater brine supplies approximately half of the world’s lithium. Lithium-ion batteries account for much of the lithium mined and processed. However, lithium and its compounds serve other industrial functions, within lubricants, as flux additives and within glass and ceramic formation.
Lithium processing yields dust from its mining through grinding and milling, with this dust exhibiting typical characteristics such as:
Fine particle size: Particles can measure less than 5 microns, making capturing challenging.
Reactivity: Lithium is a highly reactive metal. This characteristic makes it a valuable component of batteries, but also reactive within the processing environment and sensitive to exposure to water, air and other chemicals.
Flammability: The dust from lithium processing can ignite spontaneously in the presence of air or moisture.
Poor flow characteristics: This property makes lithium dust more likely to cling to surfaces or equipment.
Health hazards: Lithium dust, if inhaled or ingested, can cause various health issues, including skin and eye irritation or respiratory ailments.
Corrosivity: Lithium dust can be corrosive to certain metals. Careful consideration of equipment and materials selection for dust capture can help mitigate this characteristic.
Given these properties, it is crucial to implement appropriate dust management and limit exposure to lithium dust in industrial settings. These measures include selecting the proper dust collection equipment, personal protective gear, ventilation systems, combustion prevention measures, and an effective and comprehensive maintenance plan.
Top tips for configuring an appropriate lithium dust collection system
The type of dust collection equipment matched to the processing system depends on several variables, including the lithium production stage. More than likely, a dust collection effort will incorporate a baghouse. It might require a cyclone, wet scrubber, or loading spout.
Two of the most essential considerations are appropriately sizing the baghouse and its inlet design. Inlet loading (in grains per dry standard cubic foot) will dictate the air to cloth ratio and guide one to either incorporate a traditional hopper inlet or a high side inlet.
Hopper inlets are used when capturing nuisance dust from transfer points, screeners or filling operations, while a high side inlet may be more appropriate when handling heavy dust loading experienced during process operations and milling. Which design is best suited for the application will be determined by our engineering team, based upon accumulated knowledge from decades of successful installations.
Another important characteristic of many types of dust is combustibility. And given the explosive nature and reactivity of lithium dust, appropriate explosion protection expertise should be employed.
More comprehensive information about the dust collection options is available in the white paper on lithium processing. However, specific design considerations or tips design engineers use to configure a system to help overcome challenges posed by lithium dust management can include:
Adjusting the slope in the baghouse hopper.
As stated above, lithium has very poor flow characteristics, which causes it to stick to surfaces. Environmental factors such as humidity and even altitude can impact dust properties.
Some methods towards managing dust with poor flow include increasing the slope of the hopper, adding vibrators or a compressed air fluidization system. All of which will encourage movement of bulk material.
Another challenge is dust sticking together will accumulate or “bridge” across a discharge outlet. In the case of combustible dust, bridging poses a significant risk factor. Designers can calculate an effective angle of repose to facilitate the dust’s flow. This computed value helps determine the hopper's slope or optimal steepness.
Selecting the proper filter media.
Numerous baghouse filter options are available as well as engineered fabrics specific for challenging applications. Whether handling elevated temperatures or gas streams having moisture, acids, solvents or other agents, there are many options available.
The fabric or media choice helps determine whether a baghouse will operate at maximum effectiveness and efficiency. Design engineers can recommend the best combination of fiber types and filters to aid with dust capture and, equally important, dust cake release.
For example, an ePTFE membrane helps capture tiny particles from the airstream, which could assist operations interested in recycling captured lithium dust into the production stream. This membrane also improves the cake release of sticky dust.
Other factors influencing media selection include dust shape (spherical or regular) and micron size. Sly offers many baghouse filter mediums to release particles with the finest grain or stickiest properties.
Recalculate inlet location and placement.
The fine nature of the lithium dust, its weight and size help determine the inlet placement on the baghouse. Lithium dust has a density of approximately 25 lbs. per cubic foot. Lighter materials such as this might benefit from a higher inlet placement.
Often the OEM equipment dictates the placement of the inlet to match the outlet and outflow from a dryer, for example.
Customization is the key to meeting unique specifications
This points out the value of working with a company that can customize the build of its dust collection equipment. In-house manufacturing is the key. When a company controls its fabrication process instead of outsourcing, it controls the design and manufacturing process. This supplies the customer with uniquely designed and tailored equipment to suit application specifications.
Another benefit of customized manufacturing is that the equipment can be designed to fit within the allotted square footage or plant footprint. It also makes fitting the components into shipping containers easier for overseas installation. Sly works with companies around the globe and can implement design procedures that optimize system efficiency while reducing the size of a baghouse, for example, to accommodate shipping size constraints.
Lithium dust exhibits behaviors unlike any other substance. It requires an experienced team of engineers and a dedicated manufacturer to create an efficient system that performs safely and is up to specifications. In addition, lithium dust collection projects share two factors in common—each is unique, and each requires strict confidentiality for OEMs to maintain the secrecy of proprietary processing methods.
Sly Inc. offers over 20 years of experience designing and building dust management systems for lithium processing. Sly keeps its manufacturing in-house, allowing for customization in design and fabrication to meet customer needs.
Lithium processing companies can achieve processing goals, maintain plant safety and trust in complete confidentiality with the team at Sly. Call us today or download our white paper on “Lithium Dust Collection: When Every Mote Counts.”
Author: Dave Mosinski, Regional Sales Manager
Dave has been in the dust collection industry and with Sly for over 26 years.