Vertimill®

Vertimill® is a unique product offered exclusively by Metso Outotec. Grinding efficiency, reduced media consumption, lower installation cost, minimal maintenance, and minimal liner wear make Vertimill® the lowest total cost of ownership in many applications, substantially improving the profitability of concentrators.

Mechanically, Vertimill® is a simple machine with an agitating screw suspended into the grinding chamber, supported by spherical roller bearings and driven by a fixed speed motor through a planetary gearbox.

The capacity of each unit size is relative to the required power input for the intended grind, however, mills have been operated with throughputs exceeding 750 mtph.

Lower capital cost

Vertimill® requires a simple and small foundation, which means less floor space is required. In fact, in the same application a Vertimill® has 50% less footprint than a ball mill.

Lower operating cost

Vertimill® is an energy efficient grinding machine. They tend to grind more efficiently than, for example, ball mills with feeds as coarse as 6 mm to products finer than 20 microns. This provides up to a 40% higher energy efficiency. 

With the Vertimill® simple and robust design, limited liner replacement is required. This also allows for up to 95% or greater uptime for more productivity and profitability.

Versatile applications

Vertimill® has proven to be a versatile tool that exhibits many advantages over traditional ball milling in various applications.

It is capable of handling a wide range of feed sizes typically from 400 to 90 microns.

Support from Metso Outotec experts

Metso Outotec draws from more than 100 years of mill design and manufacturing expertise, and over four decades of successful Vertimill® applications.

Our engineers will review your specifications and recommend the proper Vertimill® for your application.

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Vertimill® is typically arranged in closed circuit and fed by the cyclone underflow. The motor power turns the Vertimill® screw at constant speed to stir the grinding balls and slurry.

As the particles are ground, they rise to the top of the mill and overflow into the separating tank. A change in the rotational direction of the slurry when it transitions from the mill to the separating tank causes turbulence which facilitates a settling of the coarser material.

Product from the mill exits the tank through a stand pipe and then to the cyclone sump. The slightly coarser portion of the mill overflow is recycled back into the bottom of the Vertimill®.

The recycle system can reduce cyclone circulating load by allowing the mill to preferentially grind the coarser material. Also, the uprising velocity in the mill can be controlled by a recycle pump to affect the product size distribution, prevent over grinding, and reduce the circulating load from the cyclone.

Final product size is a factor of applied grinding power, flow rate, and slurry density. The effective operation of the Vertimill® requires these parameters to be accurately and constantly monitored and adjusted to meet the required product specifications.

Motor power and media addition

The power drawn by the Vertimill motor is required to establish the grinding rate. Motor power should be measured using corrected power.

As the grinding media wears fine enough to be carried out by the uprising velocity in the mill, the total media charge will diminish, and the power draw will decrease.

Consistent power draw is required to achieve the desired product size, so media should be added either manually or automatically periodically to maintain as consistent a power draw as possible.

Vertimill® has an excellent turndown ratio and can be operated at lower than installed power with less effect on grind efficiency than for example horizontal ball mills.

Feed Flow-Rate

This parameter is used in conjunction with the feed density and motor power to establish the grinding rate in kWh/mt.

Vertimill®can easily handle a fluctuating flow but it should be monitored and can be varied to achieve required product requirement.

Feed Density

The feed density is required, in conjunction with the feed flow-rate, to establish the feed rate of solids.