Modern mine-duty crushers generally do their jobs amazingly well. In fact, its possible that their broad versatility and effectiveness can sometimes mask deficiencies in upstream or downstream processes such as drilling and blasting during the mining sequence, or pebble handling from SAG mill grinding, respectively.
This isnt the fault of the crusher itself or the companies that build these highly efficient machines. Crushers, when properly sized for the application and well maintained, can handle mostif not allof the material dumped into them with very little outside assistance. Its up to mine management and technical staff to decide what goes in them and what comes out in order to achieve optimal process performance.
Several speakers at a recent mining conference touched upon the real possibility that when it comes to optimizing mine-to-mill product flow, a simple shift in focus may produce significant improvements in overall cost control and asset utilizationand as an added benefit, crusher availability and efficiency might be improved even more.
For example, one speaker offered the example of a mine manager focused solely on getting tons to the crusher. Optimal fragmentation size from drilling and blasting isnt a primary consideration, as in: We have this gigantic gyratory crusher. It can handle pretty much anything. Why worry about fragmentation? Theactual issues related to poor fragmentation, the expert noted, arent primarily associated with the crusher; they take the form of loading and haulage inefficiency, high secondary blasting costs and accelerated equipment wear and failure, to name a few.
Looking further downstream, another speaker suggested that a mill might expend a lot of energy and money on crushing and rehandling those troublesome, grind-resistant pebbles that come out of the SAG milland which may not contain enough metal to make their treatment a significant contributor to overall recovery rates.
And yet another pointed to site-specific quirks of mineralogy that can lead to unnecessary crushing and rehandling. At one mine, a study found that fines accounted for a surprisingly large portion of available metal content, with larger fragments being much lower in value. By taking advantage of the natural segregation of material in the ore stockpilewith fines remaining at the top while larger fragments worked their way to the bottomthe mine could harvest the top 20% of the pile and maintain recovery rates, while the larger fragments could be crushed and handled on a more selective and cost-effective basis.
The economic forces currently in play across the hard rock mining sector put additional pressure on operators to get the most out of their equipment in terms of performance, cost of ownership and safety. Are crusher manufacturers meeting the challenge? Heres a brief rundown on recent product announcements from the industrys leading suppliers.
At the bauma 2016 trade fair held earlier this year in Munich, Germany, thyssenkrupps Industrial Solutions group introduced the industrys largest gyratory crusher. The KB 63-130 features a design, which, despite a roughly 14% larger mantle diameter of 130 in. (3.3 m), weighs less than its predecessor, the KB 63-114, at 490 tons. Its rated throughput of up to 14,000 metric tons per hour (mt/h) is more than 30% higher than that of the preceding model, said the company. It also noted that the new unit achieved this level of compactness and performance because thyssenkrupps crushing technology specialists moved beyond customary design principles during its development.
The increase in throughput and significant weight reduction was made possible by combining proven Finite Element Method (FEM) with advanced Discrete Element Method (DEM) simulations. In the past, the rule of thumb was the bigger the diameter, the taller the crusher, said Detlef Papajewski, head of mineral processing at thyssenkrupp Industrial Solutions. But, because users generally only need a bigger diameter to increase output, the KB 63-130 is exactly the same height as the other crushers in the 63-in. series despite the larger mantle diameter.
Technical highlights of the new crusher include a rotatable countershaft assembly for setting tooth clearance, and an eccentric bearing assembly with top bevel gear. Along with enabling better balancing of the machine, the new bearing system permits a much more compact design as well as maintenance-friendly assembly and disassembly.
The KB 63-130s housing exhibits the fish belly design seen on other large thyssenkrupp gyratory crushers, intended to reduce stress and increase the overall strength of the housing. However, when used in a semimobile crushing plant (SMCP), for example, crusher weight can be reduced by around 200 mt prior to relocation by removing certain parts. These parts, such as the heavy main shaft fitted with crushing tools, can also be easily removed for maintenance purposes.
Introduction of the gyratory follows the companys revision and standardization of its Kubria line of cone crushers. On display at bauma was the Kubria F/M 90, whose nomenclature stems from the size of the machines lower cone diameter of 90 cm. The F/M indicates that crushers of this type are used for fine and medium crushing; i.e., mainly as secondary and tertiary crushers. Depending on requirements, the F/M 90 can be equipped with a feed opening of 180 mm and can achieve throughputs of up to 200 mt/h.
Thyssenkrupp refined and optimized the Kubria line to increase the crushers throughput rates, while at the same time standardizing certain modulesa change that will provide customers with both lower prices and shorter delivery times for the Kubria models, according to the company.
On the updated models, the cone is mounted in an eccentric bearing and driven by a spiral bevel gear with Cyclo-Palloid toothing, which permits the transmission of high crushing forces while ensuring smooth operation. The hydraulic cylinder beneath the machine serves both to adjust the crusher gap and to protect against overloading of the crusher.
Telsmith describes its T900 cone crusher as a true mine-duty machine. Offering output rates ranging from 550 mt/h to 2,100 mt/h with up to 15-in. (38-cm) feed size, the company said the T900 offers the largest in-class clearing stroke, the highest in-class crushing force, and features 900-hp performance.
Among the crushers reliability and ease-of-maintenance features, Telsmith noted that the T900 is designed with eight cylinders (versus 12 cylinders in conventional units) for reduced maintenance time and costs. The crusher also offers an improved anti-spin feature that prevents head spin, thus extending manganese life. According to Telsmith, the T900 also has the largest-in-class hybrid bearings, which, unlike roller bearings, offer both a static and dynamic lift to efficiently carry the crushing forces. Hybrid bearings feature a washer and ramp design that replaces the conventional use of a socket, socket liner and head ballall of which typically require time-consuming removal when servicing the machine.
The T900 is equipped with a release system that eliminates the need for maintenance-intensive hydraulic accumulators. Further operational cost savings stem from features such as a concave (bowl liner) retention system, which consists of a specially designed and positioned lip ring that centers the bowl and achieves retention without the use of hammers and other hand tools. The T900 also can reduce inventory costs because it enables the use of a single bowl for all liners over its range of operation, providing versatility in any hard rock mining application.
Metso recently launched a new generation of upgrades aimed at improvingthe productivity of older crusher models while reducing maintenance costs and bringing equipment in line with enhanced safety practices. They come in kits with installation instructions; alternatively, Metso can provide the customer with a field service team for support or for the complete upgrade installation.
Metso understands the tough nature of the current mining market for our customers, so we made it our goal to design a new generation of crusher upgrades that would enable them to generate more ROI without the need for expensive capital investments, said Jaakko Huhtapelto, sales development director for Metsos spare parts business.
Metso said installing the upgradescan improve productivity through increased product rate capability, easiersetting adjustments, better crusher reliability and reduced bridging from over-sized materials. Maintenance can be reduced through the improved lifetime ofcomponents, more reliable crushing andeasier maintenance procedures. Safety can be enhanced through better maintenance practices, reduced stoppages from bridging, and the usage of automatic or remote settings.
Also available from Metso are new maintenance platforms that enhance worker safety when changing wear parts in jaw crushers. The maintenance platforms, for all C Series jaw crushers, include hand rails, a sturdy work platform and a control mechanism that enables precise placement at the desired height of the jaw opening. The aluminum platforms are light enough for one person to move; depending on model size, they weigh between 12 kg and 23 kg.
With a small investment, Metsos new maintenance platform offers a huge improvement in safety when making jaw changes. When the platform is installed correctly into the opening, it holds the jaw in place so that it cannot drop, even if the jaws upper mounting hardware is loosened or even removed. The platform is lightweight and it is easy to handle and adjust to fit the desired level in the crusher cavity, said Ilkka Somero, product manager of Metsos jaw crusher line.
Sandviks latest crusher models include the CH860 cone, designed for high-capacity secondary crushing, and the CH865 cone for high-reduction tertiary and pebble applications; both feature higher crushing forces relative to mantle diameter and a 500-kW motor. According to the company, both new crushers combine a range of advanced automation features for a more secure and productive process.
We scaled down our larger Sandvik CH890 and Sandvik CH895 mining cone crushers to create two mid-range models, said Andreas Christoffersson, product line manager for cone crushers at Sandvik Mining. Depending on the application, the CH860 and Sandvik CH865 outperform competing equipment in the midrange segment by as much as 30% and deliver a twofold increase in performance range.
FLSmidth offers a comprehensive line of cone crushers, starting at the smaller end of the capacity spectrum with the Raptor 200, which features a low-profile design suitable for mounting on a portable chassis, inverted tramp release cylinders that keep hydraulics cleaner than conventional designs, and a single accumulator for less maintenance. At the other end of the Raptor line is the Raptor 2000, a candidate for worlds largest and configured with model-specific features such as spiral bevel gearing, double-acting tramp release and clearing cylinder, easy access to critical load-carrying bearings, design elements that include substantial eccentric throw and high pivot point crushing action, and 2,500-hp direct drive with a variable speed option.
In the gyratory crusher market, FLSmidth continues to offer its line of TS gyratories, built around the principle that major crusher service and maintenance functions should be made as safe and convenient as possible. Accordingly, in the TS line the eccentric assembly, bushings and hydraulic piston are easily accessible and removed through the top of the crusher.
The TS line has two variations available, depending on the application and customer requirements. Heavy Duty TS units are suitable for most mining applications, while Ultra Duty TSU units are designed for extreme applications where additional motor power and heavier sections are necessary.
TAKRAF now offers standardized primary and secondary sizers for various crushing applications. The primary sizer product range covers inlet sizes from 2.5 m to 4 m with throughputs of up to 10,000 mt/h, while the secondary sizer range offers inlet sizes from 2 m to 4 m with throughput rates up to 3,500 mt/h.
TAKRAF said it paid close attention to ease of maintenance, reduced downtime and extended service life during the lines initial development. Some of the innovations resulting from this focus are provisions for convenient changeout of crushing segments, and the use of advanced wear-resistant items such as hard-faced segments and tungsten picks. Other features include an inching drive for roll maintenance, a heavy-duty drivetrain and an efficient oil lubrication system.
Meanwhile, thyssenkrupp announced that its complete RollSizer seriescapable of crushing medium-hard rock as well as sticky and soft materialhas been standardized and new models added. As a result, according to the company, the entire range of crushing applications can now be handled by RollSizers.
The company highlighted its RollSizer DRS 660X3000 S at the bauma show. With a roll length of 3 m and shaft center distance of 660 mm, the RollSizer DRS 660X3000 S is the second largest member of the family of secondary and tertiary RollSizers. The DRS 660X3000 S features a direct drive system consisting of two spur gears with fluid couplings. The couplings allow startup even under the load of a full crushing chamber, and also provide overload protection; when thesizer encounters an uncrushable object, the fluid slip provided by the couplings protects the machine against damage. Drive torque is provided by two 250-kW electric motors.
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DEM with a particle breakage model has been used to successfully model crushers.Five types of compression crushers have been simulated.Contact forces determine breakage with geometric rules for progeny generation.Predictions include power draw, liner stresses and wear, product size and throughput.The models allow flow and breakage in crushers to be better understood.
Discrete Element Method (DEM) simulation using a breakage model is applied to study a broad range of existing compression based crushers to better understand machine level operation and to demonstrate that such modelling is now possible. Predictions for five types of crushers: jaw crusher, cone crusher, gyratory crusher, impact crusher and double roll crusher are presented. The breakage method used is based on facture of particles using geometric rules for progeny generation and estimates of the force applied to the particles as they flow through the crusher. From these simulations, estimates of power, product size, throughput rate and crusher wear are made.
In this study, an analytical perspective is used to develop a fundamental model of a jaw crusher. Previously, jaw crushers were modelled in regard to certain aspects, for example, energy consumption (Legendre and Zevenhoven, 2014) or kinematics (Oduori et al., 2015). Approaches to date have been mainly property specific. In this work a physical modelling approach has been used to derive the modules, which are based on established facts of comminution machines, from the literature. A modelling methodology mainly inspired by Evertsson has been applied (Evertsson, 2000). The modules are divided into kinematics, flow, breakage, capacity, pressure and power. Each module has been derived and tested decoupled from the other modules to provide increased transparency of the module and its behaviour. The results of the modelling are presented for a baseline case of one industrial-scale jaw crusher and compared to manufacturer data. Future work will include validation and DEM simulations.
Nordberg HP Series cone crushers are characterized by the optimized combination of crusher speed, eccentricity, and cavity profile. This mix has proved revolutionary, providing higher capacity, better product quality and suitability to a wider range of applications.
From limestone to compact hematite, from ballast to manufactured sand production, and from small aggregate plants to large mining operations, Nordberg HP crushers are unbeatable in secondary, tertiary, and quaternary applications.
Nordberg HP crushers feature a unique combination of crusher speed, throw, crushing forces and cavity design. This combination is renowned for providing higher capacity and superior end-product quality in all secondary, tertiary and quaternary applications.
In a size-class comparison, Nordberg HP crushers have a higher output capacity, higher density in the crushing chamber, better reduction ratio, and they produce higher on-spec yield end products with the same energy consumption.
Nordberg HP crushers produce finer products by limiting crushing stages, which lowers your investment cost and saves energy. This is achieved through a combination of optimized speed, large throw, crushing chamber design and increased crushing force. The efficient crushing action of the best power utilization per cone diameter.
Designed for your needs, Nordberg HP crushers are safe and easy to maintain. Fast and easy access to all the main components from the top, and dual-acting hydraulic cylinders significantly reduce downtime and are more environmentally friendly.
Nordberg HP crushers are engineered to ensure maximum operator safety and easy maintenance. The crushers have an access from the top of the crusher to the principal components, an easy access for liner maintenance, and mechanical rotation of the bowl for removal with a simple press of a button. Maintenance tools are also available.
With Metso IC70C you can control maintenance, setting modifications, production follow-up and data extraction. All parameters can be adapted to your plant characteristics, and you can easily do all this close to the crusher or remotely from the control room.
You set the goals and Metso IC70C helps you reach them. It allows you to monitor the feeding, change the settings automatically depending on the load or liners wear, and select the product size distribution according to your preference of coarse or fine aggregate production.
Get the maximum potential out of your size reduction process to achieve improved crushing performance and lower cost per ton. By using our unique simulation software, our Chamber Optimization experts can design an optimized crushing chamber that matches the exact conditions under which you operate.
A DEM modelling framework for simulation of cone crushers is proposed.Rock material model based on bonded particle model and calibrated against breakage experiments.Simulation results are compared with industrial scale cone crusher experiments.Novel insight regarding internal mechanical dynamics and particle flow behaviour and breakage.
Compressive crushing has been proven to be one of the most energy efficient principles for breaking rock particles (Schnert, 1979). In this paper the cone crusher, which utilizes this mechanism, is investigated using the discrete element method (DEM) and industrial scale experiments. The purpose of the work is to develop a virtual simulation environment that can be used to gain fundamental understanding regarding internal processes and operational responses. A virtual crushing platform can not only be used for understanding but also for development of new crushers and for optimisation purposes.
Rock particles are modelled using the bonded particle model (BPM) and laboratory single particle breakage tests have been used for calibration. The industrial scale experiments have been conducted on a Svedala H6000 cone crusher operated as a secondary crushing stage. Two different close side settings have been included in the analysis and a high speed data acquisition system has been developed and used to sample control signals such as pressure and power draw in order to enable detailed comparison with simulation results. The crusher has been simulated as a quarter section with a batch of breakable feed particles large enough to achieve a short moment of steady state operation. Novel methods have been developed to estimate the product particle size distribution using cluster size image analysis. The results show a relatively good correspondence between simulated and experimental data, however further work would be need to identify and target the sources of observed variation and discrepancy between the experiments and simulations.
A new breakage method for non-round particles is proposed for DEM.Progeny distributions use the t10 method and data from breakage testers.The model is successfully applied to a cone crusher predicting realistic flow.Particles break by compression as they approach the choke point of the crusher.The predicted product size distribution includes resolved and unresolved components.
Predictions of particle flow and compression breakage of non-round rock passing through an industrial scale cone crusher are presented. The DEM (Discrete Element Method) particle breakage model is generalised to allow non-round particles to be broken into non-round progeny. Particles are broken in this DEM model when the elastic energy of a contact is sufficiently high to initiate fracture. Progeny size distribution data from JKMRC Drop Weight Test (JKDWT) or JKMRC rotary breakage test (JKRBT) is used to generate the specific daughter fragments from each breakage event. This DEM model is able to predict the production of both coarser progeny which are resolved in the DEM model and finer progeny which are not. This allows the prediction of product down to very small sizes, limited only by the fineness of the fragments measured in the breakage characterisation. The predicted flow of material through the crusher, product size distribution and liner wear are discussed. The generalised breakage model demonstrated here is suitable for modelling all forms of crushers.