There are four common operational problems in the field of processing high calcium stone for mine operators and crushing project managers: material blockage, machine malfunctions, low yield of qualified stone products, and frequent wearing of the crusher parts.Although operators have analyzed numerous crushing processes, they still fail to find the solution of how to combine high production capacity, specifications of the products, non-stop working cycle, and affordable cost. According to a real-life crushing and screening project implemented in Nanning, Guangxi, China, and now successfully operating, this paper analyses the operational issues of the original project, its customized crushing solution, equipment configuration logic, production workflow, and advantages of the project implementation.All technical data, equipment models, technical characteristics, project schedule, and results presented below are taken from the original project record.The project is an example of a successful upgrade of the high calcium stone processing line which can be used by other similar projects. This project is useful for industry professionals who want to create new crushing plants or optimize their current production process.
This project is a crushing plant installed in one of the high calcium stone processing plants of Nanning, Guangxi, China. The project is a closed-circuit crushing and screening production line specially designed in accordance with the characteristics of the locally available raw materials.All project information and milestones of the implementation process can be verified by means of the original documentation of the site.The production capacity of the crushing plant designed in the project is 1,000 tons per hour. The market demand is connected with the need in 40–80mm high calcium stone products.The target size of 60% should be produced at all times by the equipment.Project implementation schedule is clearly defined. All equipment was delivered in April 2024. The whole production line started its work in August 2024.Since the commissioning of the equipment, it has been successfully operating and hasn't experienced any failures. All the production targets have been achieved.Now the customer is satisfied with the work of the whole system.This project is an example of the well-designed solution of the problem of high calcium stone crushing, which has been tested by practice.
During the preliminary analysis of the current processes in the industry, the customer has performed practical tests in order to reveal the problems associated with traditional crushing process and their influence on the productivity.High hardness and moisture content, as well as the problem of over-crushing of high calcium stone, have led to a number of problems which have increased operating costs.The use of traditional crushing equipment leads to the over-crushing of the material. It causes the formation of a huge amount of powder waste. It decreases the production ratio of the qualified products of 40–80mm size and the efficiency of the material use.Accumulation and transport of waste materials cause additional expenses. In addition, the insufficient amount of the product makes it difficult to provide the customers with the products in time. It leads to the loss of clients and negative market reputation.Also, the local stone is characterized by its hardness and abrasiveness. Due to that, there is the frequent wear of the wearing parts of the conventional crushers. Frequent replacements of the parts lead to the stoppage of the work of the whole production line.Considering the additional expenses related to the spare part purchase and labor cost, the operational and maintenance costs become quite expensive in the long run.At the same time, the mined stone contains natural moisture. Due to this, there is the risk of blockage of plate feeders and fine mesh screens by the wet powder.Frequent manual cleaning operations disrupt production and cause unstable output and impossibility to conduct the 24-hour operation without stops.Moreover, traditional crushing processes are characterized by the low efficiency of screening and classification. There is the contamination of finished products with fine powder and impurities which makes it difficult to meet the requirements of the clients concerning the quality and shape of the material.Also, there are many machines involved and the complex configuration of the equipment leads to the increase in the risk of stoppage of the whole production line because of numerous possible points of failure.These factors affect each other and prevent conventional crushing configuration from balancing finished product yield, maintenance cost, non-stop operation capacity and product quality.That's why the customer needed the customized complete crushing solution for high calcium stone processing conditions.
With the account of the customer's request of 1,000 tons per hour production capacity, the proportion of 60% of 40–80mm finished stone and the characteristics of the locally available high calcium stone (high moisture content and abrasiveness), MP specialists have designed the customized integrated closed-circuit crushing and screening solution.The front section of the production line is based on grizzly feeder and grizzly screening technologies. The open-bar design helps to avoid wet material adhesion and reduce the risks of the blockages and frequent stoppages starting from the feeder.The middle section of the production line uses a high-capacity jaw crusher which ensures the high productivity of 1,000 TPH production line.As for the last crushing stage, a double toothed roll crusher is chosen as the fine crushing equipment which allows controlling the production ratio of target-sized products and minimizing unnecessary fine powder production due to the low-wear crushing characteristics of the equipment.The whole production line consists of just four machines which helps to decrease the potential points of failure but doesn't decrease the quality of the finished product and its stability.
The whole production line includes only four pieces of core processing equipment:VGF1860 Grizzly Feeder, PEV160 Jaw Crusher, 2DSKP120300 Double Toothed Roll Crusher and YAH2452 Grizzly Screen.Simplified equipment configuration effectively decreases failure possibility.Every machine model was selected considering production capacity demand, raw materials characteristics and specifications of the finished product. All technical parameters are closely related to the production demands and do not involve unnecessary equipment redundancy.
VGF1860 Grizzly FeederThe leading-end VGF1860 Grizzly Feeder has the total power of 45kW.It can crush the raw materials with the maximum feed size up to 1,200mm with the processing capacity range of 800-1,200 tons per hour, completely corresponding to the production capacity of 1,000 tons per hour for the current project.The feeding trough size is 1,800 × 6,000mm. The total equipment weight is 11,501kg and overall dimensions are 6,000 × 4,060 × 2,353mm.During the work process the grizzly spacing was selected as 200mm.The equipment is capable to pre-screen the fine materials before crushing them. The open-bar structure prevents the accumulation of wet materials and thus directly eliminates the problem of material blocking during feeding.
The PEV160 Jaw Crusher is the machine for the primary crushing process.The total power of the machine is 254kW, including the 250kW crushing motor and 4kW hydraulic station.With the big feed opening of 1,600 × 1,200mm the crusher is able to process the materials with the maximum size of 960mm.The closed-side discharge setting is adjustable within the range of 150–300mm, providing flexibility in controlling the crushed material size.The processing capacity ranges from 430-1,145 tons per hour.The equipment weight is 72.5 tons without motor and hydraulic station, the overall dimensions are 5,900 × 3,700 × 3,750mm.Sufficient processing capacity provides reliable support for the primary crushing load of the entire production line.Adjustable discharge size provides stable intermediate materials for the screening and secondary crushing processes.High power configuration ensures long-term reliable operation and continuous stable production capacity.
Being the equipment for final size control, the 2DSKP120300 Double Toothed Roll Crusher is equipped with rollers with the diameter of 1,200mm and width of 3,000mm.After crushing, the proportion of 40–80mm finished stone products stays stable at 60%, which corresponds perfectly to the customer's product requirements.Toothed roll crushing mechanism effectively reduces the excessive crushing and thus the amount of fine powder generation.In comparison with traditional crushing equipment, this mechanism has lower wear characteristics, which helps to reduce the wear parts replacement frequency due to processing of high-calcium stone.Also, the big width of the rollers provides stable handling of oversized materials returned from screening, which creates continuous closed loop for size adjustment process.
YAH2452 Grizzly Screen
The final screening step is performed using the YAH2452 Grizzly Screen.Grizzly spacing is set as 80mm, and the machine automatically separates the materials with the sizes bigger than 80mm and materials with sizes smaller than 80mm.In comparison with traditional fine mesh screens, the grizzly structure prevents the clogging because of the wet fine powder due to the equipment design.The screening capacity is fully correspondent to the output of the jaw crusher, thus providing the continuous and smooth material classification during all production process.
All equipment system works based on the concept of the full process:"Anti-blocking feeding at the front stage – high capacity primary crushing – efficient material classification – low wear controlled size crushing."Processing capacity, feed size, screening gaps and crushing specifications of each machine are precisely matched and complement each other.Every equipment solves the certain production problem using its own technological features.Combination of several machines creates the whole closed loop for crushing process, providing the customer's requirements for:Production capacity,Finished product specifications,Continuous operation,Low cost maintenance.
The whole production line is organized based on the logic of the continuous crushing process of:"Feeding – Primary Crushing – Screening – Fine Crushing – Finished Products Combining."The process connections are tight and the total number of machines is minimized to increase operational reliability.The high-calcium stone raw materials are initially transferred to the VGF1860 Grizzly Feeder for continuous and uniform feeding.Using 200mm grizzly spacing, some part of fine materials in the raw ore can be pre-separated, thus reducing unnecessary crushing load and increasing processing efficiency.The oversized materials after being separated in the feeder are transferred into the PEV160 Jaw Crusher for primary crushing.After primary crushing the mixture of crushed materials is transferred by the belt conveyor to the YAH2452 Grizzly Screen for classification.Using 80mm grizzly spacing, the material flow is separated in the certain size groups.The materials with the sizes bigger than 80mm after screening are transferred to the 2DSKP120300 Double Toothed Roll Crusher for further crushing.The crushed material is transferred back to the finished products flow.The screened materials with the sizes less than 0-80mm are combined with the output from the double toothed roll crusher and transferred to the downstream finished products screening system.The finished products with the sizes of 40-80mm of high-calcium stone are obtained.The entire closed loop process increases constantly the proportion of the target sized stone products.The whole production line uses grizzly-type equipment in all the critical steps of screening and feeding. Thus, it is very suitable for the processing of high-moisture stone materials. At the same time, the simplified equipment configuration decreases the failure possibilities while keeping the balance between production capacity, product output and continuous operation.
The customization crushing process is characterized by three major advantages.After implementation, it has effectively solved all major issues of the original process and implemented comprehensive improvements in production efficiency, stability and cost control.First of all, the production efficiency of the finished product has been considerably improved.Due to the size control ability of the double toothed roll crusher, the ratio of the target finished products of 40-80mm is constantly stable at 60%.The amount of the waste in the form of fine powders has been greatly reduced, increasing the efficiency of the raw materials utilization.As a result, additional costs connected with the accumulation of the waste materials, their transportation and shortage of the products have been minimized.Secondly, the production line is highly adaptable to high moisture conditions of the stone processing.Thanks to the technology of the grizzly feeding and grizzly screening, the system is resistant to any blockage due to wet materials.Thus, during high-calcium stone processing, the system does not suffer from the blockage failures and does not require any additional cleaning procedures.Therefore, the production line can operate for a long period continuously and achieve the planned productivity of 1,000 tons per hour.Finally, the entire production line requires fewer core machines, thus, minimizing the risk of failures.In addition, thanks to the low wearability of the double toothed roll crusher, the period of the wear parts replacement is increased.Thus, costs associated with purchasing spare parts, maintenance and labor requirements are effectively controlled.Also, reduction of shutdowns and startups of the equipment minimizes the mechanical loads on the machine and increases its service life.
From the standpoint of the real performance of the project, the equipment has been constantly operating since its installation in August 2024 and has fulfilled all initial production targets of the customer.The production line has achieved:1,000 tons per hour stable processing capacity with the constant ratio of 40-80mm high-calcium stone products;in the process of processing of the wet materials, the system does not have any blockage issues;lower equipment wear compared with traditional crushing combinations; thus, maintenance costs have been reduced;finished products are homogeneous in size and meet the requirements of the downstream clients.After the project implementation, all major issues, including:low yield of the finished products,high maintenance costs,frequent shutdowns,instability of product quality,have been successfully resolved.Thus, the project has achieved the optimization in five major areas:raw material utilization efficiency,continuous working time,maintenance costs,finished product quality,order fulfillment stability.This project provides an example for other similar high-calcium stone crushing projects, including the construction of new lines and upgrades of existing plants.
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