BMX-400 – ball mill for dry grinding

At Comex, we have developed a new dry milling system with a ball mill working with an air classifier in a closed circuit. The system we propose is intended for laboratory use. We have created a compact device that requires little input material. The control system provides fully automatic operation with registration of almost all operating parameters in the PLC system.

The throughput of such a system is typically in the range of several kilograms per hour, giving you considerable flexibility when working with small batches of material, various settings and operating parameters. The system can also simulate conditions in large industrial mills by setting the required process temperature to 120°C.

In addition, you can measure the particle size distribution in different parts of the system with an on-line analyzer. In this way, you will ensure constant control of the manufactured product. All parameters are recorded and can be exported to XL or another program after testing.

Dry grinding systems: challenges

Dry grinding systems that use ball mills are typically very complex and intricate. They often include closed-circuit ball mills with an air classifier. Such arrangements often require significant investments in mechanical equipment. The equipment itself must be equipped with advanced instrumentation, used for optimization. In addition, the research work carried out in such grinding systems is very complex and requires long, several hours of grinding. All of this results in dry milling systems consuming large amounts of input material.

Choose a system:

Capabilities and technical specification of the BMX-400 system

In order to present the specificity of the operation of our BMX-400 dry grinding system even more precisely, we present a detailed schedule and technical specification of our solution.


  • feeder performance measurement system
  • the ability to add chemicals
  • Mechanical tank agitation for efficient material flow

Ball mill:

  • mill diameter 350 mm
  • mill motor power 370 W
  • temperature adjustment from 30 to 150 degrees
  • mill speed and torque sensor
  • mill weight control

Aero classifier:

  • 3 to 300 micron product (d97)
  • air flow adjustment
  • measurement of coarse fraction mass flow to the mill

Cyclone and filter:

  • cyclone with shut-off valve for sampling
  • filter with automatic cleaning cycle

Control and instrumentation – parameters registered and stored in the system:

  • control capacity in kg/h
  • chemical dosing in g / t
  • mill speed in rpm
  • mill torque in Nm
  • mill barrel temperature in degrees Celsius
  • mill material temperature in degrees Celsius
  • amount of material returned to the mill in kg/h and as % of feed
  • classifier speed in rpm
  • classifier engine load in A
  • air flow rates: main and auxiliary in m3 / h
  • fan speed in rpm
  • specific energy during grinding in kWh / t

Grain composition control (optional):

  • continuous measurement of product grain composition
  • continuous measurement of the grain composition of the classifier’s coarse fraction
  • continuous grain composition measurement at the mill outlet
  • grain composition expressed as characteristic points, e.g. D97, d80, d50 etc.

Have a questions?

For more information on the Comex optical sorting system, please contact:

Jakub Koczwara

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