McLanahan director of sales for the UK and Ireland Donal McNicholl shares his tips for optimising a jaw crusher’s size and feed to support long-term crushing.
Quarries working with resources such as dolomite, limestone, and sandstone or in emerging sectors like recycled and demolition materials rely on jaw crushers.
As a result, selecting the right size of jaw crusher is crucial.
“Jaw crushers are effective for crushing a wide range of materials and are a top choice for primary crushing in a variety of applications as well as in stationary, portable or modular plants,” McLanahan director of sales for the UK and Ireland Donal McNicholl said.
“They provide a 6:1 reduction ratio and can handle small and large tonnages. Jaw crushers are a low-wear, low-operation-cost option for material size reduction with minimal maintenance requirements.”
The fundamental considerations are the materials to be processed, their characteristics, the maximum feed size, the product size, and the feed rate.
“The characteristics of the feed material are extremely important. Not only do they help to determine the size of the jaw crusher required to do the job, but they also help to determine the materials of construction of the wear components,” McNicholl said.
“The characteristics of the feed material also help to determine if a jaw crusher is even the best type of crusher for the job or if another type of crusher would be better suited.
“Lab testing can provide an analysis of the material that can be shared with the equipment manufacturer for sizing the crusher.”
McNicholl said the best practice for sizing the jaw crusher was for the maximum feed size to be 80 per cent of the gape and width opening. This method reduces the likelihood of large feed sizes stuck in the crushing chamber and stalling production.
The site environment is also likely to influence the selection of the right jaw crusher for a quarry application. Key environmental factors include the method of extracting the raw material, the process of feeding the raw material, potential production increases, the site footprint, plant height restrictions, and site operating hours.
“You also want to consider if tramp metal relief is necessary. If there is a chance you could accidentally process a large piece of metal, such as a bucket tooth, on through to the Jaw Crusher, you may want to consider a hydraulic jaw crusher with tramp relief over a shim-adjust jaw crusher,” McNicholl said.
“The toggle on a shim-adjust jaw crusher can break in the event an uncrushable material enters the chamber, whereas the hydraulics on a hydraulic-adjust jaw crusher will relieve to pass the material.
“Another consideration is the method of adjusting the closed-side setting: manually with shims or hydraulically with the push of a button. Shim-adjust jaw crushers are lower in capital cost, but they require a complete plant shutdown when product-size adjustments need to be made, as well as someone to physically make the adjustments.”
Using the correct sizing and feeding methods can significantly enhance a jaw crusher’s performance.
Quarries can improve the maintenance and operation of their jaw crushers by using the best feeding practices.
Jaw crushers are often fed in line by a feeder or scalping screen where the feeding machine lines up with the feed opening of the jaw crushers. The in-line feeding method helps limit the possibility of materials clogging the jaw crusher and slowing production.
McNicholl said choke feeding was considered one of the best feeding methods for jaw crushers.
“Jaw crushers work best when the entire crushing chamber is used for material size reduction. Choke feed a Jaw crusher to maintain a crushing chamber that is at least 80 per cent full,” he said.
“This will help to draw the material down into the crushing chamber, as well as create a better material shape and improve overall efficiency.”
Beyond employing a choke feeding method, quarries can implement a series of actions to support their jaw crusher operation. These include pre-screening the feed to remove fines and removing oversized material from the feed.
“Removing oversize ahead of the Jaw crusher will help to avoid blocking and clogging of the crusher opening. A good rule of thumb is that the maximum feed size should be 80 per cent of the crusher opening. If the crusher opening is 30 inches, a 24-inch feed top size is recommended,” McNicholl said. “Fines in the feed can limit production for several reasons. They can clog the crushing chamber, reducing the tons per hour and efficiency of the crusher.
They can also prevent even distribution of particle sizes and generate an inconsistent product shape.
“Fines can also create unnecessary wear on crusher components. Scalping out this material ahead of time will help to prolong the life of wear components [jaw dies and side plates], as well as help to reduce the downtime required to change out worn components.”
Material characteristics, including the type, quality, and presence of tramp material, can impact the jaw crusher’s performance.
McNicholl said limiting the presence of steel or other materials in the feed and avoiding lightweight, sticky materials would support the jaw crusher’s performance.
“While jaw crushers can handle metal, such as steel, in a feed, and can even pass the steel without harm to the crusher if equipped with an automatic tramp relief system, it is best to limit the amount metal that enters the crusher,” he said.
“If the crusher does not feature a tramp relief system, the toggle that maintains the closed-side setting can break, potentially damaging other components in the plant as it falls out of the crusher as well as causing unplanned downtime to replace the toggle.
“Jaw crushers are known for being able to handle a wide variety of materials, specifically those that are very hard, very abrasive and non-friable. They can even handle some wet materials. Jaws are not designed for handling lightweight or sticky materials, however. Sticky materials can build up on the jaw plates and reduce efficiency. Lightweight materials don’t draw down into the crushing chamber well, which also reduces efficiency.”
By implementing these best practices, quarries can maximise the efficiency, lifespan, and productivity of their jaw crushers. Proper sizing, feeding, and maintenance not only improve overall performance but also help reduce downtime and operational costs, ensuring a more sustainable and profitable crushing operation.
As the demands of the industry continue to evolve, staying informed about innovative crushing solutions and best practices will be key to maintaining a competitive edge. For those looking to optimise their crushing operations, McLanahan offers a range of solutions designed to enhance efficiency and reliability in material processing. •
For more information, visit mclanahan.com
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