Effective crushing and screening key to quality

Efficient crushing and screening processes help produce quality products, Mike Woof reports

Having an efficient crushing and screening operation is crucial to the cost-effectiveness of a quarry as well as providing the best quality product. The crushing circuit is a key component in any quarry with the right selection of equipment as well as effective maintenance important factors in optimising performance. Manufacturers are unveiling innovative solutions to boosting the efficiency of crushing and screening circuits.

Sorting the feedstock before it enters the crushing cycle can make major gains in efficiency. This reduces the energy spent in processing undersized fines or contaminants and significantly boost throughput while also reducing unnecessary wear and tear on the crushing and screening plant and maximising finished product quality.

Placed at the start of the reduction cycle, this type of equipment can make major gains in output while cutting running costs and 229 Hazemag & EPR has developed a new system for this application. The firm's innovative VarioWobbler can cope with different materials as its size can be adjusted easily. The screening surface features rotating shafts that allow fines to pass through gaps while the coarse material stays in the system. A hydro-mechanical control system allows an infinite range of gap sizes between the individual shafts. The firm says that this function allows a quick reaction to feed requirements and is particularly useful where the water content of a material varies greatly. The system can deal with a variety of materials from hard rock through to clay and minerals with sticky inclusions and can deliver a capacity of up to 2500tonnes/hour and can be specified as a single or multi-stage plant.

Customers have a wide array of equipment for the crushing and screening process to choose from, including static and mobile plants. Different types of crushers are also offered to suit specific applications as well as the primary, secondary and tertiary stages in the crushing cycle.

Jaw crushers are typically used in the primary stage and US firm 2987 Telsmith says that its new Hydra-Jaw Model H2550 features advanced technology to maximise efficiency. According to Telsmith, the crusher delivers low operating costs when installed in wheeled or tracked mobile units. The firm says the new design helps increase uptime and production capacity.

A key feature of the H2550 is the hydraulic toggle system which features a heavy-duty hydraulic cylinder, custom-engineered for crushing applications. Innovative hydraulic adjustment, relief and clearing systems minimise downtime and prevent component damage, according to the firm. The crusher is said to be ideally suited for the portable contractor and is a low-profile unit while its fast hydraulic adjustment allows operators to cope with different applications and materials. The hydraulic overload relief system prevents crusher damage, downtime and difficult maintenance procedures by opening the crusher and allowing tramp metal and non-crushable materials to pass through, preventing damage, while the system will then automatically return the crusher to its previous setting. The unit offers a 635mm x 1,270mm feed opening and, depending on the conditions is capable of crushing between 145-440tonnes/hour.

Italian crushing specialist 2988 REV says that its new GCR100 machine is the first of a new generation of mobile crushers from the firm and is powered by a Tier 3/Stage IIIA emissions compliant Cat C7 diesel rated at 173kW. REV is working on a new line of mobile crushers that will be built along similar lines to upgrade its current eight model line-up. The GCR100 weighs in at 35tonnes and for road transport measures 2.5m wide to comply with Italian road regulations.

Depending on the material being crushed and the size setting, the GCR100 can produce from 150-300tonnes/hour. The jaws feature hydraulic adjustment and open automatically in the event of tramp metal entering the system. Features include magnetic separation a water spray system to minimise dust emissions, a remote control and a side conveyor as well as a full range of other options. The hydraulics feature load sensing pumps to maximise efficiency and reduce fuel consumption.

Impact crushers suit particular applications and this is a competitive market with various manufacturers offering high performance equipment. 261 Kleemann claims that its new generation of impact crushers offer high performance despite compact dimensions. The company says the higher capacity is achieved by a new chamber design, which improves material flow. The design prevents narrowing of the material stream, allowing the smaller of the machines with its inlet opening of 1100mm to deliver up to 250tonnes/hour, while the larger unit with a 1300mm opening offers capacities of up to 450tonnes/hour.

The new SHB series impact crusher has a hydraulically actuated crusher inlet in with a heavy-duty cast design and an optimised, steeper inlet angle to the new blow bar fastening system. The machines also feature a fully hydraulic crushing gap adjustment that can be operated easily and in mere seconds from the operating panel. The crusher bypass has also been redesigned to ensure an optimised flow of material, which is pre-screened and continually moved past the crusher.

According to Kleemann, the improved flow not only increases production rates but also helps to reduce wear. Both machines are powered by direct drives, which Kleemann says improve efficiency along with a loss-free fluid coupling and v-belts connected directly to the flywheel of the crusher. The direct drive means that the rotor speed can be adjusted in four stages, making it suitable for both quarry and recycling applications.

Meanwhile 325 Sandvik's new QI240 impact crusher is designed to process construction materials on site. This highly mobile, compact impactor is designed to work in a secondary or primary capacity, either independently, or in conjunction with other models in the Sandvik product line, to produce the highest quality materials.

Although developed for the recycling of construction material, the QI240 is ideal for smaller quarries where space and machine manoeuvrability are at a premium, and superb product shape and high levels of production are essential.

The machine is fitted with a pre-screen to ensure maximum scalping capability to prevent any undersize material passing through the impactor to maximise throughput and reduce wear costs. This also allows a specified sized product to be produced from the natural fines conveyor.

Designed for large fixed plant installations, the new Superior 60-2110E gyratory crusher and the Nordberg MP1250 cone crusher from 6934 Metso offer high throughput capabilities. Design and modelling software has been used to create the new Superior 60-110E primary gyratory crusher which provides a redesigned Spider, a one-piece bottomshell and a new rim liner retention system. The machine weighs 20% less than the firm's previous design but with no reduction in capacity, while it also offers reduced installation and transportation costs.

Metso's new MP1250 uses the same footprint as the MP1000 but offers greater productivity, with improvements in the mantle locknut to make maintenance quicker and easier. There are also upgrades in the hydraulic tramp protection system, bowl adjustment and removal, and faster. Firms running the MP1000 cone crusher can upgrade their plant using Metso's MP1250 retrofit kit, which includes a new sleeved, high-throw eccentric; large counterweight with bolt-on guard; upper head bushing; head ball; and socket liner. The design also includes an upgraded mainshaft assembly with a patented bearing ring that releases the pressure of the headnut for mantle change-out. This eliminates the risk of damage to the headnut or mantle and allows simple replacement.

1222 Terex is widening its static crushing plant line-up with the introduction of the Canica 2000 vertical shaft impactor and the Cedarapids Rollercone MVP450X cone crusher. The MVP450X features heavy duty roller bearings and has a hydraulically powered threaded upper assembly for quick crusher setting adjustment under load. Dual action tramp relief cylinders allow fast clearing of jammed feed material, while pinned cylinder ends remove quickly for fast cone separation and manganese change. The new Canica model offers throughputs of up to 250tonnes/hour with a 100mm feed size and a range of anvil options. The heavy duty bearing pedestal features self-aligning spherical roller bearings and all exposed crushing chamber parts are cast chrome protected.

Meanwhile a cost effective option to buying a new crushing plant is offered by US firm 2989 JW Jones, which offers upgrading and refurbishing of existing systems. The Indiana-based firm can supply complete refurbished plants for nearly half the price of a new plant. JW Jones completely disassembles each machine down to its individual components, which are assessed for quality, specification and continued life, and are either rebuilt or replaced. The reconditioning work includes new electrical, hydraulic and lube system components; and new chassis and support structures for portable plants. The firm says that the rebuilt plants often perform better than before as they benefit from new technology and engineering improvements developed since their original manufacture.

Screening the crushed aggregates efficiently provides another key factor in cost-effective production and 2992 Keestrack has developed a compact but productive version of its Novum range. The new model is designed to be versatile and can be quickly changed from having three or two output conveyors depending on the size of the working space available and the number of products required. This feataure allows the Novum's working width to be reduced from 14.5m to less than 10m. The right-hand conveyor can be removed, with the main one moved back hydraulically to take its place. Moving the conveyor maintains capacity and avoids the need to slow down the flow, while this new version uses the same hopper and screen as the standard model. The Novum comes with a range of options, such as a heavy-duty fingerscreen top deck, an anti-clogging system on the bottom deck and a screen flow brake.

Northern Irish firm 2991 Powerscreen is widening its range with the addition of a new mobile screen. The new 2400 model features a heavy duty incline screen with a high amplitude triple shaft drive mechanism, lending itself to screening, scalping, two or three way splitting and stockpiling materials like aggregates, topsoil, coal, construction, demolition waste and iron ore. The screen will accept a wide variety of media making it suitable for many applications.

Italian company 2990 Gasparin Impianti used the recent 688 Bauma event to introduce its new model, the GI CRUSHER OLIMPO GI118 mobile crusher, which is equipped with the latest generation management systems, and which the company says offers high production rates.

"The HCS (hydraulic crushing system) continuously checks and adjusts the different parts of the machine, and this means maximum performance in terms of low fuel consumption, low crushing chambers wear, and high production, which means low running costs," says Gasparin Impianti. The 42tonne machine has an output of up to 360tonnes/hour and is powered by a 196 Cummins engine.

It has a vibrating grizzly feeder with replaceable double step bars grid; the main belt conveyor's discharge height is 3.2m, and the hydraulic folding hopper is fitted with a with wedge-lock system.