Crushing explained

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Does your operation require a crushing solution, but you’re not sure which chamber type is fit for your machine application and material? Our Sandvik product specialists have compiled the following crushing chamber breakdown to assist you in your decision-making process. To learn more about your crushing options and to get tailored plant advice, get in touch with Porter Equipment today.

Jaw crusher

Sandvik Jaw Crushers (QJ241, QJ341, UJ440i) are excellent for use in primary applications. With various jaw plate configurations available they are ideal for use in crushing hard rock products such as granite and basalt and other material with comprehensive strength below 320MPa for QJ models, and up to 450MPa for UJ models.

Jaw crushers operate via a squeeze/compression action which results is a ‘needle flake’ output that has a particle size range of 10-350mm depending on machine settings. The Sandvik jaw range all feature a simple single toggle arrangement for ease of use. In order to adjust the crushing action, operators need to set the CSS (closed side setting), controlling the width of the chamber opening during the crushing action. The Sandvik C10 and C12 jaw box configuration has a narrow nip angle preventing blockages caused by oversized rock.

The jaw chamber is made up of two jaw plates; a fixed and a moveable jaw (often known as the swing jaw) positioned in a V formation. The crushing action occurs when the moveable jaw is rocked against its fixed counterpart as the eccentric shaft at the top of the chamber rotates. An added benefit of Sandvik QJ model jaw crushers is the reversible hydrostatic drive which makes for easy blockage clearing and easy maintenance.

Jaw crushers are known for low fuel consumption comparative to other crushing modes and feature large feed sizes for high throughput and a lower wear rate. Jaw models typically have a low fines production and a somewhat limited reduction ratio. Ideal applications for jaw crusher models include recycling, demolition and as a primary crusher in quarrying plant configurations.

Cone crusher

Sandvik cone crushers are available in two cone chamber options: hydrocone (QH) and gyratory (QS) cones. Hydrocone crushers (QH332, QH441, UH440i) are designed for secondary crushing due to their limited feed capacity when compared to jaw and impact models. Gyratory cones (QS332, US440i) present added versatility and can be implemented as primary crushing units.

The cone crushing chamber operates via a central mantle cone which moves against external concave chamber walls. The mantle gyrates in an eccentric motion, that is, it doesn’t remain completely centred – it swings slightly as it rotates, continually altering the gap between the mantle and the concave chamber walls. As the mantle moves, it crushes the material against the concave at the points where the gap is smallest (see animation below).

To determine the desired reduction ratio operators must adjust the CSS. The CSS is the smallest distance between the concave and the central mantle. A typical reduction ratio in a secondary application is in the 1:4-1:6 range. This ratio is affected by the feed materials bulk density, crushability, size distribution and moisture content – among other factors – and will affect the crushing chamber performance.

Sandvik cone crushers produce high-quality product and are ideal for applications where consistency of material shape is required. Cone crusher end product size is largely determined by the selected wear parts and eccentric throw settings, with a wide range on offer from Sandvik. Sandvik cone crushers accept most feed material, though limited feed size is a consideration for prospective purchasers.

Impact crusher

Sandvik impact crushers (QI341, QI442, QI353) offer a versatile crushing solution, capable of both primary and secondary configurations. The impact crushing action varies from the compression-based jaws and cones and results in superior cubic product shape. Sandvik impactors are particularly suited to softer stone such as limestone, greywacke, and other brittle materials.

Sandvik impactors feature the patented Prisec Impact Crushing Chamber. Impact crushing is achieved, as you would expect, from high-velocity impact. Rock product enters the chamber and is propelled against a series of two aprons by rotating blow bars or hammers. Sandvik’s patented design features two pin positions for greater reduction variance when changing crusher configuration from primary to secondary (see animation below).

Impact crushers are renowned for their high production output due to their large feed size and versatility. While a higher wear rate is inevitable with impact crushing, Sandvik impactor models more than make up for this in quality throughput. The cubic end product makes impact crushers ideal for aggregate and gravel quarries, while the adjustable apron positioning system makes the Prisec impactor a popular model for a wide range of recycling and mining applications.