A Vertical Shaft Impact (VSI) crusher is a mineral crushing machine that uses velocity and impact to reduce the size of minerals fed into it. VSIs are renowned for the particle shape they produce. This is because of their rock-on-rock crushing action (as opposed to a rock-on-metal crushing action).
VSIs come in three main configurations:
- Standard hard parts
Autogenous VSI units use a rock-lined rotor and a rock-lined chamber; semi-autogenous use a rock-lined rotor and a crushing chamber with anvils; a standard VSI uses a rotating impeller with iron wear shoes and a chamber with anvils.
Within these three primary machines, REMco offers over 30 standard configurations to meet specific product requirements.
VSIs are not only less expensive to operate; they also have a higher profit margin when operated correctly. REMco VSI Crushers can produce materials smaller than 1/2" (13 mm) at lesser costs than cone crushers.
Yes! VSI crushers can produce the same products as a cone crusher. Closed circuit operation is preferred when the VSI is operated in a 3rd or 4th stage application. One of the significant benefits of a VSI, when compared to a cone crusher, is the shape of the finished particle, which is typically more cubical and uniform when compared to a cone crusher product. REMco VSI discharge grading is finer than cone crusher gradings when operating in closed circuit.
Not at all. The REMco rock-on-rock VSI's product grading is affected by power demand for the feed load, feed grading, and rotor speed. The grading remains constant regardless of wear part conditions. For REMco ST/AR machines with anvils, wear of the crushing parts will coarsen the discharge grading.
VSIs need about the same amount of service as any other crusher – no more no less.
Like all other crushing machines, visual inspection daily is highly recommended. These machines go through a lot, and they need to be looked after as a result. Actual service and maintenance intervals though are variable and depend on the crushing application, the abrasiveness of the rock, and the expertise of the operator.
REMco VSIs are considered noisy. During normal operation, sound levels range from 75-85 decibels at a point of 1 meter from the machine. Noise levels will vary with installation. As a precaution, it’s important to wear earplugs when machines are running.
When the rotor is balanced correctly, there should be minimal vibration depending on a few variables. Some vibrations during the crushing process can be expected such as with courser feeds. Finer feeds tend to result in smoother operation. Pulsing vibration levels are also typical as the rotor builds and sheds different sized rock pieces. When in doubt, though, feel free to contact us with your concerns.
Dust is a common concern when crushing materials, so we’ve fitted our machines with an air re-circulating system designed to reduce the air pressure build-up that happens is the machines.
Sometimes when the feed material is very dry, or you want to make a very finely crushed product, dust is inevitable, in which case, we suggest using a water fogging nozzle to add some moisture to the feed before it enters the crusher.
Absolutely. You can install our crushers on a wide variety of support systems. The vibration isolators protect not only the crusher but also the structure is it mounted on from most vibrational loads. We have seen many installed on old existing crusher footings of fabricated construction or concrete. REMco offers a low-cost installation kit or adapter plate if required.
- The larger models of REMco units (5080 and 9150 series) up to 4" / 100 mm sized feed
- The medium units (2040 and 4060 series) up to 3" / 75 mm sized feed
- The smaller units (2040 series) 2" / 50 mm or smaller sized feed
REMco VSIs are the best at improving product shape – that’s why we love them and why we think you’ll like them too. To achieve the product shape, you’re looking for look no further than a REMco VSI. We'll work with you one on one to find the right machine, speed, and circuit for your rocks and minerals.
Anvil Type Crushing Chamber
An anvil crushing chamber consists of 15-20 chrome-iron -or chromite- blocks positioned around the circumference of the machine against which the rotor throws the rocks, minerals, or ores to crush.
Anvil VSI crushers, crush rocks by striking them against the metal. This type of VSI is particularly suitable for less abrasive applications like limestone. The anvils are positioned at an angle to maximize the perpendicular impact of the rock as it exits the rotor. When the rocks strike the anvil surface, particle breakage occurs.
Yes, the anvils are a wear part and need to be replaced regularly. The wear rate, as measured in hours, days, weeks, or tons produced, will depend on several factors such as:
- Tonnage being fed into the crusher
- Particle size being fed to the crusher
- Rotor speed
- Percent of total abrasives content of the rock. (SiO2 Silica; AL203 Alumina; and Fe Iron).
- The content of water (H2O)
The higher the pressure you put on your crusher system, the more often the anvil will wear. Stay aware of the content you are giving your crusher, and you'll have a better idea of when you will need to replace your anvil.
The use of anvils is a common and very successful for the crushing of low to medium abrasion material. It's acceptable when the material being crushed contains less than 15% total abrasives. Anvils will provide superior crushing at an acceptable wear parts cost per ton. The lower the content of the abrasive, the longer the life of the wear parts.
Anvils are also useful for minimizing any oversize that's produced by the crusher and minimizing recycle loads. Anvils will produce a sharper, less cubical material than rock-on-rock chambers, but the product shape will be more cubed in comparison to the product of compression crushers such as jaws, gyratories, and cones.
An anvil rock chamber in a VSI crusher, depending on rock type being crushed, may produce fewer micro fines in the product in comparison with a rock-on-rock type chamber. This applies to material smaller than 200 mesh, .075 microns.
An anvil chamber should not be used if the material to be crushed is known to contain more than 15% abrasives as noted above. Extremely wet feeds should not be applied to an anvil crushing chamber. With sound, hard stone, when reduction ratios exceed 4:1 of feed to the final product, the use of anvils should be carefully evaluated for cost and product rate.
When feeding fine feeds, smaller than 1/2” (12 mm), to produce sand, extreme care must be used to size the crusher properly to the required feed and production rate. Underfeeding an anvil type VSI can result in poor wear patterns and higher crushing costs.
Feel free to contact us for guidance.
- A REMco crusher with an anvil chamber as a tertiary feeding minus 3” (76.2mm) will typically produce minus 3/4” (20mm) for 0.25 to 0.40 cents per ton wear cost.
- Depending on the nature of the material being crushed, an anvil chamber has to be changed between once a week to once a year.
- An anvil chamber will require more frequent inspections and a higher labor cost for service.
- The crusher discharge grading of an anvil crushing chamber varies during the life of the anvils. The wear can reduce crushing efficiency and increases the production of a coarser product.
- A REMco crusher with a rock-on-rock chamber as a tertiary feeding minus 3” (76.2mm) will typically produce minus 3/4” (20mm) for 0.05 to 0.10 cents per ton wear cost.
- Depending on the nature of the rock being crushed, a rock-on-rock chamber insert will need to be changed between once a year to once every five years.
- A rock-on-rock chamber will require infrequent inspections and needs little or to no cost for service.
- The crusher discharge grading of a rock-on-rock crushing chamber will remain constant as long as feed rate and rotor speeds are maintained. Crushing efficiency remains constant.
Of course, all REMco crushers designated as ST/AR models can be readily converted in the field from anvil chamber to the rock-on-rock chamber designation, ST. The process to change from an anvil chamber to a rock-on-rock chamber is simple and requires only a few quick, easy steps. You first remove of the anvils and the anvil support ring, then ensure the chamber is clear of rock build up, and finally the installation of a rock chamber insert which is bolted into position. Rotor speed or type of rotor may have to be altered depending on the required crushing task.
REMco's expert technicians can take you through the process at any time!
Rock-on-Rock Crushing Chamber
A rock-on-rock crushing chamber, also known as an autogenous chamber, is a circular ring of pockets, that fill with rock, positioned in the crusher around the full interior circumference of the machine at a position directly opposite the rotor. It is lined and packed with the feed material and through the rotor. REMco rock-on-rock chambers are designed as an insert and can quickly and easily be changed or replaced in the field.
A rock-on-rock crushing chamber smashes the rocks against each other to crush them instead of against a piece of metal. Rock-on-rock crushing produces beautifully shaped aggregates that are well-graded, cubical, and to specification. A rock-on-rock crushing chamber not only creates excellent shape, but it also saves on wear parts because there’s no need for the anvil wear iron that’s used in anvil type and other crushers. Instead of metal wear parts, the chamber fills with a tightly packed rock-lined bed of material that the feed material is crushed against. By using a rock-lined chamber, the crushing cost is signification reduced because there is no need for this particular piece of wear iron.
A rock-on-rock crushing chamber typically does not experience any significant wear when the crusher is fed the proper material at a constant rate. The feed rate should be such that it causes the consumption of at least 60% of the crusher’s drive power. With the crusher adequately fed and with regular inspections, a rock-on-rock chamber can last the life of the crusher with no service, or replacements required.
If a rock-on-rock crushing chamber is fed very dry material, a low feed rate, or only coarse stones, the rock lining of the chamber may be scoured out, or it may not be able to build up properly. This kind of crushing will cause damage and erosion of the rock-on-rock chamber gussets. Conversely, feeding very wet or sticky material can also cause wear of the rock-on-rock chamber insert.
In order to protect your crushing chamber, it’s essential to inspect the crusher and run it under the specifications it was built for regularly within a well-designed circuit if your crusher feed or desired output change, your crusher’s setup may need to be adjusted.
Rock-on-rock crushing chambers are most effective when handling abrasive materials. They can also be used for the production of sand and other fine products. Rock-on-rock chambers are available for REMco crushers in a variety of configurations to meet specific application requirements.
All REMco crushers can be converted in the field to any of the three basic models, SandMax, RockMax, and ST/AR. RockMax and SandMax rock-on-rock chambers differ in that the RockMax chambers are more open and provide a reduced density for the coarse material typically fed to RockMax crushers. SandMax rock-on-rock chambers are more closed and achieve a denser particle cloud within the crusher. This versatility allows for a greater concentration of the crushing energy, producing a finer end product.