KT Brickman, Aug 20, 2020 6:00:00 AM
On its face, milling is a simple task: you start with a coarser raw material and mill or grind it to reduce its particle size to the desired fineness. Sounds easy enough, right?
But a number of factors can influence that process — from the inherent characteristics of the material to factors as external as the weather. And when processing efficiency is affected, so is cost.
That’s why it’s critical to consider experience and expertise when choosing to partner with a toll processor. It’s also important to keep in mind a few major factors that can affect the process of particle size reduction for your project.
1. When selecting raw feed, particle size matters—and finer is not always better
New customers often assume raw materials with a smaller particle size can save processing time and cost; in fact, the opposite can be true. Keep in mind that if your material is available in several grades, that likely means the finer grades have already been processed — and that can add costs.
It’s also critical to keep in mind some milling processes, such as jet milling, may actually benefit from larger initial particle size. Typically, raw materials a quarter-inch or smaller are appropriate for jet milling. Because jet milling creates high-velocity particle collisions to achieve the goal particle size, a larger initial mass can actually make the process more efficient. Smaller particles can require more time and energy to process.
That means choosing a larger, coarser raw feed may offer cost savings and process efficiencies. One notable exception is wet milling, in which a smaller initial particle size (less than 100 microns) is the best choice — the finer your raw material, the less time required on wet milling equipment.
It’s always a good idea to consult with your toll processor to determine the best initial particle size.
Did you know, CPS has pre-crushing capabilities for raw material that’s larger than the quarter-inch initial size needed for jet milling?
2. Many factors can influence shipping costs
Initial particle size and product density can influence packaging methods and materials — sacks vs. bags, for example — and packaging can have an impact on the handling and mode of transport needed to deliver your raw feed to your toll processor.
Depending on the size and scale of your project, it may be wise to run trials with several different raw material grades. If you’re faced with a decision about initial coarseness, packaging, and shipping costs, your toll processor can advise which particle size delivers the best process efficiency before you place a bulk order or pre-process your own product for milling.
Typically, material that’s closer to its raw state and packaged in a bulk format is less expensive. So it’s critical to ensure your toll processor has the capability to handle the material as it’s delivered.
Did you know, at our different locations, CPS can receive raw materials in quantities and formats ranging from tankers, rail cars, and dump trucks, down to a minimum milling quantity of 75 grams?
3. Initial particle size is just one consideration
Many material attributes impact the milling process and the conditions required for successful processing. Is your raw material ductile or rubbery? Smooth or tacky? Brittle or friable? Is it combustible?
Polymers and waxes, for example, can pose specific challenges in the milling process. Your toll processor’s expertise can help you overcome those challenges. Waxes, for example, can reach their maximum processing temperatures easily in the summer months, which can complicate — and add cost to — the milling process. It can pay to work with an expert and plan ahead.
While minerals tend to be more predictable, some possess absorbent qualities and can take up humidity from the air around them. So it’s important to coordinate with your toll processor to ensure they have the capacity to protect, store, and properly and promptly handle your materials.
Recycled or reclaimed materials, usually polymers, present unique challenges to the milling process and can make cost estimating difficult. Recycled materials tend to vary in characteristics and behavior on the mill from lot to lot, compared with virgin raw materials.
Reclaimed or salvaged raw material may not be available in an ideal particle size for processing; this can require special handling and can increase processing costs. Your toll processor should be able to clarify all the variables that contribute to the overall cost.
Did you know the material scientists and engineers at CPS can work with you to determine the best processing conditions, such as temperature, air flow, choice of milling equipment, and application of force to address material challenges and achieve your goal particle size?
4. Don’t discount the value of your own knowledge
Whether you’ve been working with another processor, or you’ve run a few elementary grinding trials in the laboratory, you may have data to share with the experts on your toll processing team. More information is better, so gather your data and share as much as possible — from pre-crushing steps to the best processing conditions.
You have already invested time and money, so informing your toll processor helps you continue to reap ROI from those learnings. CPS can use your experiential knowledge as a starting point, and make process improvements to help drive further efficiencies and cost savings on your project.
Did you know, because CPS charges customers based on yield, we share an interest in process efficiency? The information you share with us helps make processing more efficient and affordable.
5. The earlier your toll processor joins your project, the more they can help you streamline and reduce costs
Your point person tasked with contracting a toll processor may be a specialist in sourcing or supply chain logistics, rather than a material scientist with deep technical expertise. Your toll processing team should include R&D specialists, transdisciplinary science and engineering experts, business development experts, and others whose passion it is to achieve your material specifications with the greatest efficiency possible.
A team of scientific thinkers and engineers is the ideal complement to your supply chain management specialists.
Did you know you can connect with the CPS team by simply filling out our contact form? You can provide your project basics to get started, and we’ll reach out promptly to follow up.
No matter how far along you are in your project, our Grinding Project Application Checklist can help you review all the critical aspects of your particle reduction needs, to help us move quickly toward achieving your goals, and to help you better understand the factors that will impact processing and costs.