The limestone crushing system consists of a GBZ2000×10000 heavy-duty plate apron feeder and a PCF2018 single-stage hammer crusher. The designed production capacity is 500 t/h, but the actual production capacity is less than 400 t/h. After on-site observation, It was decided to transform the limestone crushing plant to increase the output to more than 460t/h.

Apron feeder


(1) Through observation, it is found that the apron feeder has a large installation angle (23°), and the material in the trough plate slides during operation, and the thickness of the material layer does not meet the design requirements.

(2) Since the materials come from the surrounding small mining areas, the granularity of the limestone entering the plant in each mining area is different, the soil contains large impurities, and there are parts of the mountain bark between individual mines, resulting in large fluctuations in the output of the crusher.

(3) Due to the long running time of the crushing system and the low output, in order to ensure the production needs, there is insufficient downtime for maintenance, and sometimes production will be delayed due to maintenance.


(1) Technical transformation of the mechanical part of the plate apron feeder

In order to increase the thickness of the material layer and reduce the material sliding phenomenon, a piece of 80 mm wide steel plate is welded to the tail of the conveyor trough plate of the plate apron feeder (vertical welding), and one piece is welded for every 3 hoppers. The hopper depth of the plate feeder is increased to increase the plate type. The feeding capacity of the feeder increases the thickness of the material layer.

(2) Technical transformation of apron feeder electrical appliances

The board feeder adjusts the feeding speed through frequency conversion speed regulation. The inverter has a rated power of 45kW and a rated frequency of 50Hz.

After inspection, the power of the motor and reducer can meet the frequency raising requirements, the inverter setting parameters are adjusted, the inverter frequency is adjusted from the previous 50Hz to 60Hz, and the inverter rated current is adjusted to the motor rated current 94A.

(3) Protection transformation of apron feeder

After parameter adjustment, a test run with load was carried out. According to the tested maximum load current, multiply by a reliability factor of 1.2 to further optimize the inverter current protection value. Adjusted from the previous 94A to 63A to ensure the reliability and sensitivity of the inverter protection action.

(4) Crusher protection transformation

In order to prevent leakage in the crusher after the speed of the frequency converter increases, causing the V-belt of the crusher to slip and burn, a belt stall protection device is installed at the pulley of the crusher. When the speed of the crusher pulley is as low as 70% of the rated speed, the crusher and the board feeder will jump directly.

(5) Change the feeding method of the apron feeder

The feed of the original apron feeder is tail feed, which is now transformed into double-sided feeding, which is beneficial to increase the thickness of the apron feeder material layer.

The effect after the technological transformation

After the above technical transformation and 3 months of continuous, safe and stable operation, good results have been achieved. Various energy consumption indicators have been significantly reduced. The power consumption has been reduced from 2.5 kWh/t to 1.8 kWh/t, and the output of the crusher has been increased from less than 400t/h to more than 500t/h, and the production capacity has been fully utilized.

Read also: Types of Feeders in Quarries

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